JP2015032396A - Light guide body, lighting device and display apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide body, a lighting device and a display apparatus which can emit high luminance light and make an image of a light deflection element and moire inconspicuous.SOLUTION: In a light guide body 7, a plurality of light deflection elements 18 for deflecting light toward an emission surface 7b are disposed on a light deflection surface 7a, a plurality of unit lenses 7d extended in a Y direction are arrayed in an X direction on the emission surface 7b, the light deflection elements 18 constitute unit arrays which are arranged in a prescribed average pitch and at least one unit group arrayed such that an adjacent interval is decreased as the plurality of unit arrays get distant from the light incident surface 7L along the Y direction in the range of dy/2 from the light incident surface 7L, arrangement density of light deflection elements 18 is gradually increased in such a direction as to get distant from the light incident surface 7L through the interior of unit group in the range of dy/2 and the unit group, and the unit arrays in the unit group are disposed such that mutual arrangement is differentiated for at least two arrays in which arrangement of the light deflection elements 18 in the X direction becomes adjacent in the Y direction.

Description

  The present invention relates to a light guide, a lighting device, and a display device.

  In recent large-sized liquid crystal televisions, flat display panels and the like, a direct type illumination device and an edge light illumination device are mainly used. In the direct type illumination device, a plurality of CCFLs (Cold Cathode Tubes) and LEDs (Light Emitting Diodes) are regularly arranged as light sources on the back surface of the panel. Between the image display element such as a liquid crystal panel and the light source, a diffuser plate having a strong light scattering property is used so that a cold cathode tube or LED as a light source is not visually recognized.

On the other hand, in an edge light type illumination device, a plurality of cold cathode fluorescent lamps and LEDs are arranged on an end face of a translucent plate called a light guide. In general, a light deflection element that efficiently guides incident light incident from the end face of the light guide to the exit surface is formed on a surface (light deflection surface) opposite to the exit surface of the light guide. At present, the light deflection element formed on the light deflection surface is generally printed with white ink in the form of dots (see, for example, Patent Document 1).
In recent years, in order to further improve the light extraction efficiency, a method of forming a microlens on the light deflection surface of a light guide by an ink jet method, a method of forming a light deflection element by a laser ablation method, and the like have been proposed. . There has also been proposed a method in which a light guide is formed by injection molding or extrusion, and the light deflection element is directly shaped during extrusion (see, for example, Patent Document 2).

The light deflection element used in such a light guide body needs to improve the light extraction efficiency and make the luminance distribution of the light emitted from the light guide body uniform, so the shape of the light guide body and the light incidence It is necessary to arrange based on a specific pattern determined according to the arrangement of the surface.
For this reason, the conventional light deflection element is formed of regularly arranged reflective layers and structures, for example, when moire is seen when used in combination with a prism sheet for improving light extraction efficiency, There is a problem that an image of the light deflection element is visually recognized.
In order to solve such a problem, Patent Document 3 describes that the light guide includes a convex lens array in which the radius of curvature and the arrangement pitch are appropriately adjusted.

JP-A-1-241590 JP 2000-89033 A JP 2003-270447 A

However, the conventional light guides, illumination devices, and display devices as described above have the following problems.
The technique described in Patent Document 3 makes it difficult for the image of the light deflection element to be visually recognized by changing the degree of condensing of the deflected light by the light deflection element by the prism sheet. If the arrangement of the light deflection elements and the prisms has a certain degree of regularity, there is a problem that moiré is inevitable.
As a means for solving such a problem, it is conceivable to arrange a diffusion film between the light guide and the prism sheet. However, in this case, since light is diffused, the luminance in the front direction is totally reduced. There is a problem that it falls.

  The present invention has been made in view of the above-described problems, and is capable of emitting high-intensity light, and makes it difficult to see an image or moire of a light deflection element, a light guide, a lighting device, and a display An object is to provide an apparatus.

In order to solve the above-described problem, the light guide according to the first aspect of the present invention is made of a light-transmitting material, and is disposed so as to face each other in a positional relationship between the light incident surface and the light incident surface. A first surface and a second surface, and guides light incident from the light incident surface between the first surface and the second surface and emits a part of the light from the second surface. The first surface is provided with a plurality of light deflection elements that deflect the light toward the second surface, and the second surface intersects the light incident surface. A plurality of unit lenses extending along a first direction are arranged along a second direction orthogonal to the first direction, and the light deflection element is arranged so that the light deflection element extends in the second direction. And a plurality of unit rows arranged at a constant average pitch and a plurality of unit rows within a certain distance from the light incident surface. And one or more unit groups arranged so that the adjacent interval decreases as the distance from the light incident surface increases along the direction of, and within the unit group and within the unit group in the range of the constant distance Through all, the arrangement density of the light deflection elements gradually increases in the direction away from the light incident surface along the first direction, and each of the unit rows in the unit group includes the second The arrangement is such that the arrangement of the light deflection elements in the direction is different from the arrangement of two or more rows adjacent in the first direction.
Here, “two or more adjacent columns” means two or more columns in a neighboring region on one side. That is, when two unit columns are present in the vicinity on both sides in the first direction, the arrangement is different from at least the four neighboring columns. In addition, when there is only one unit column or less on one side as in the unit column at the end, the arrangement is different between one column or less on one side and at least two columns on the other side. Further, “the arrangements are different from each other” means that the positions of the light deflection elements in the unit row are different as a whole. Here, “as a whole” includes the case where all the positional relationships do not match and the case where some of them match. In the case where some of them match, it is assumed that the matching rate is 10% or less of the light deflection elements constituting the unit column.

  In the light guide, it is preferable that the light deflection elements in the unit row have adjacent intervals in the second direction that change along the second direction.

In the light guide, it is preferable that the adjacent space in the second direction has a variation coefficient CV in the unit row satisfying the following formula (1).
0 <CV ≦ 1/6 (1)

  In the light guide, it is preferable that the adjacent interval in the second direction changes irregularly along the second direction.

  In the light guide, the light deflection elements in the unit row are arranged at a constant pitch along the second direction, and the unit row in the unit group is adjacent in the first direction. It is preferable that the arrangement position in the second direction is different from that of two or more other unit columns.

In the light guide, in the unit row in the unit group,
When the coordinate value for each unit column representing the arrangement position in the second direction is X _j (j = 1,..., N) and the constant pitch is Qx, the following equations (2), (3), It is preferable to satisfy (4).

  In the light guide, in the unit column in the unit group, it is preferable that the arrangement position in the second direction is irregularly changed along the first direction.

  In the light guide, it is preferable that the unit lens has an arc shape or an elliptic arc shape at least at the top of the lens cross section.

  An illumination device according to a second aspect of the present invention includes the light guide and a light source arranged to face the light incident surface, and makes light from the light source incident on the light incident surface, The illumination light is emitted from the second surface of the light guide.

  The lighting device preferably includes a reflecting member disposed at a position facing the first surface of the light guide.

  The illumination device preferably includes at least one transmissive optical sheet disposed at a position facing the second surface of the light guide.

  A display device according to a third aspect of the present invention is configured to include the illumination device and an image display element that displays an image by irradiating the illumination light from the illumination device.

  According to the light guide, the illumination device, and the display device of the present invention, the light deflection element is divided into a plurality of unit groups so that the arrangement density increases as the distance from the light incident surface increases along the first direction. , And the arrangement position of the light deflection elements along the second direction is different from that of the two or more neighboring unit columns, so that high-luminance light can be emitted and the image of the light deflection elements And moire can be made difficult to see.

It is typical sectional drawing which shows the structure of the display apparatus of the 1st Embodiment of this invention. It is the typical perspective view which shows an example of the light guide of the 1st Embodiment of this invention, its AA sectional drawing, and BB sectional drawing. It is the elements on larger scale of the cross section along the X direction of the light guide of the 1st Embodiment of this invention. It is a schematic diagram which shows the outline | summary of the arrangement pattern of the light deflection | deviation element of the light guide of the 1st Embodiment of this invention. It is a schematic diagram which shows the detail of the arrangement pattern of the light deflection | deviation element of the light guide of the 1st Embodiment of this invention. It is a schematic diagram which shows arrangement | positioning of the light deflection | deviation element in the adjacent part of the unit group of the light guide of the 1st Embodiment of this invention. It is the top view which shows the mode of propagation of the light in the light guide of the 1st Embodiment of this invention, and the schematic diagram of the C view. It is the top view which shows the mode of propagation of the light in the light guide of the 1st comparative example which does not have a unit lens, and the schematic diagram of the D view. It is a schematic diagram which shows the luminance distribution of planar view in the light guide of the 1st Embodiment of this invention, and the luminance distribution in the light guide of the 1st comparative example which does not have a unit lens. FIG. 6 is a schematic diagram illustrating an example of an image of a light deflection element viewed through a unit lens, and a schematic diagram illustrating an example of an image of a light deflection element viewed through a unit lens and an isotropic light diffusing member. It is a schematic diagram which shows the 2nd comparative example of the arrangement pattern of an optical deflection | deviation element. It is a schematic diagram which shows the 3rd comparative example of the arrangement pattern of an optical deflection | deviation element. It is the typical perspective view which shows an example of the light guide of the 1st modification of the 1st Embodiment of this invention, its EE sectional drawing, and FF sectional drawing. It is a schematic diagram which shows the detail of the arrangement pattern of the light deflection | deviation element of the light guide of the 2nd Embodiment of this invention. It is a fragmentary perspective view which shows the modification of the condensing sheet | seat which can be used for the illuminating device of the 1st and 2nd embodiment of this invention. It is a typical top view which shows the measurement position of a luminance fall rate.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In all the drawings, even if the embodiments are different, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.

[First Embodiment]
The light guide, the illumination device, and the display device according to the first embodiment of the present invention will be described.
FIG. 1 is a schematic cross-sectional view showing the configuration of the display device according to the first embodiment of the present invention. FIG. 2A is a schematic perspective view showing an example of the light guide according to the first embodiment of the present invention. 2B and 2C are an AA cross-sectional view and a BB cross-sectional view in FIG. FIG. 3 is a partially enlarged view of a cross section along the X direction of the light guide according to the first embodiment of the present invention. FIG. 4 is a schematic diagram showing an outline of an arrangement pattern of light deflection elements of the light guide according to the first embodiment of the present invention. FIG. 5 is a schematic diagram showing details of the arrangement pattern of the light deflection elements of the light guide according to the first embodiment of the present invention. FIG. 6 is a schematic diagram illustrating the arrangement of the light deflection elements in the adjacent portion of the unit group of the light guide according to the first embodiment of the present invention. In addition, since each drawing is a schematic diagram, dimensions, shapes, numbers, and the like are exaggerated or omitted (the same applies to the following drawings).

  As shown in FIG. 1, the liquid crystal display device 1 (display device) according to the present embodiment includes an image display element 2 and an illumination device 3 arranged facing the light incident side of the image display element 2.

The image display element 2 is configured by sandwiching a liquid crystal layer 9 between two polarizing plates 10 and 11.
The image display element 2 is preferably an element that transmits and blocks light in pixel units and displays an image, and more preferably a liquid crystal display element. A liquid crystal display element is a typical element that transmits / shields light in pixel units and displays an image, and can improve image quality and reduce manufacturing cost compared to other display elements. Can do.

The illuminating device 3 includes a diffusion sheet 28 (transmissive optical sheet), a light collecting sheet 20 (transmissive optical sheet), an isotropic light diffusing member 8 (transmissive optical sheet), and a light guide 7 toward the image display element 2. The laminated body 21 arranged in this order, the light source 6 arranged on the side surface of the light guide 7, and the reflection plate 5 (reflecting member) surrounding the light guide 7 and the light source 6 are included.
The illuminating device 3 is disposed with the diffusion sheet 28 facing the image display element 2.

The isotropic light diffusing member 8 is a member having a function of isotropically diffusing light emitted from the light guide 7 to be described later, and is disposed facing the light guide 7.
For the isotropic light diffusing member 8, for example, a microlens sheet in which a large number of hemispherical microlenses are arranged on the surface of a transparent substrate can be used. Specifically, for example, spherical particles dispersed in a transparent resin and a part of the spherical particles protruding from the surface can be used.

  The condensing sheet 20 is a member having a function of condensing the light diffused by the isotropic light diffusing member 8 in the visual direction F. For example, a prism having a plurality of prisms 24 formed on the surface of the base material 23. A sheet can be employed.

The diffusion sheet 28 diffuses the light collected by the light collecting sheet 20 and protects the light collecting sheet 20, and the periodic structure formed on the light collecting sheet 20 and the periodic structure of the image display element 2. Has the function of reducing the occurrence of moiré.
As the diffusion sheet 28, for example, a sheet member in which an acrylic resin in which spherical particles are dispersed on a PET (polyethylene terephthalate) film can be employed.
Further, the diffusion sheet 28 may have a function of separating the polarization of the light collected by the light collecting sheet 20.
As the diffusion sheet 28 having such a polarization separation function, for example, reflective polarized light that transmits one polarized light and reflects the other polarized light as represented by DBEF (registered trademark) (manufactured by 3M). A separation sheet can be used.

  The reflecting plate 5 (reflecting member) reflects light leaking from the light guide 7 to the light guide 7 side, and is composed of, for example, a reflective sheet such as a white polyethylene terephthalate film. In this embodiment, the structure which has arrange | positioned such a reflection sheet on the inner surface of the housing | casing surrounding the light deflection surface 7a of the light guide 7 and the light source 7 mentioned later is employ | adopted.

The light source 6 supplies light emitted from the light guide 7 toward the isotropic light diffusing member 8 from the side surface of the light guide 7, and a point-like, linear, or planar light source is adopted. Can do.
Examples of light sources suitable as the light source 6 include LEDs.
Examples of the type of LED include a white LED and an RGB-LED formed of red, green, and blue chips that are the three primary colors of light.
Alternatively, the light source 6 may be a fluorescent tube represented by a cold cathode fluorescent tube (CCFL).
The light source 6 in the illuminating device 3 of the present embodiment is a point light source in which a plurality of light sources are arranged apart from each other in the vicinity of a light incident surface 7 </ b> L that is two end surfaces facing each other of a light guide 7 described later. Adopted.
As an example, the optical axis of each light source 6 is arranged in a direction substantially orthogonal to the light incident surface 7L (including a case where it is orthogonal).

The light guide 7 guides the light incident from the light source 6 and transmits the light from the exit surface 7 b (second surface) which is a planar region facing the isotropic light diffusing member 8. It is a member which injects towards
In this embodiment, as shown in FIG. 2A, the light guide 7 is a planar light deflection surface that internally reflects light guided to one plate surface of the flat plate portion 7c that is rectangular in plan view. 7a (first surface) is formed, and a plurality of unit lenses 7d constituting the exit surface 7b are formed on the opposite side of the light deflection surface 7a.
In the present embodiment, the unit lens 7d is formed so as to cover the lens forming surface portion 7b ′ that is a rectangular region facing the light deflection surface 7a.
The thickness h7c of the flat plate portion 7c is not particularly limited, but can be, for example, 0.300 mm or more and 3.00 mm or less.
A pair of side surfaces facing each other on the side surface of the light guide body 7 constitutes a light incident surface 7 </ b> L that allows light emitted from the light source 6 to enter the inside of the light guide body 7. In the following, the direction in which the light incident surfaces 7L face each other is the Y direction (first direction), and in the plane parallel to the light deflection surface 7a, the direction orthogonal to the Y direction is the X direction (second direction). The direction orthogonal to the direction and the Y direction is referred to as the Z direction.
Therefore, the Y direction is a first direction that intersects the light incident surface 7L at a right angle, and the X direction is a second direction that is orthogonal to the Y direction.
The light incident surface 7L of the present embodiment has a rectangular shape having a long side in the X direction and a short side in the Z direction. For this reason, the X direction coincides with the longitudinal direction of the light incident surface 7L. .

As shown in FIG. 3, in the present embodiment, the unit lens 7d has a cylindrical lens shape in which at least the top portion 7e has an arc shape or an elliptical arc shape, and a cross section convex to the outside extends in the Y direction. They are arranged without a gap in a direction (X direction) orthogonal to the extending direction.
Therefore, the lens forming surface portion 7b ′ is a virtual plane in which the bottoms of the unit lenses 7d are aligned and is covered by the entire unit lens 7d.
As a result, the exit surface 7b of the light guide 7 is an uneven surface with a U-shaped cross section in which the surface of each unit lens 7d is continuous.
Each unit lens 7d is formed in a curved shape in which a rounded top portion 7e and a curved side surface 7f from both sides toward the lens forming surface portion 7b ′ are smoothly connected.
The tangent angle at the vertex T1 of the unit lens 7d is 0 degree, and the tangent angle gradually increases from the vertex T1 to the lens forming surface portion 7b ′, and the tangent angle becomes maximum at the end E1 of the unit lens 7d.
The shape of the top portion 7e can be represented by a height f (t) from the lens forming surface portion 7b ′, where t is the distance along the lens forming surface portion 7b ′ with the end E1 of the unit lens as the origin.
f (t) is a function composed of a part of an arc.

With such a configuration, when a point light source is installed on the light deflection surface 7a side, the oblique light K emitted from the point light source is condensed by refraction on the surface of the unit lens 7d, and is visually observed along the Z direction. Launched in direction F. Thereby, when observing a point light source from the emission surface 7b side of the light guide 7, the point light source is visually recognized as a linear light source extending in the Y direction.
The height of the unit lens 7d from the lens forming surface portion 7b 'is h7d, the width in the X direction of the bottom surface of each unit lens 7d is T7d, and the arrangement pitch of the unit lenses 7d in the X direction is P7d.
A preferable range of the height h7d is, for example, 2 μm or more and 20 μm or less. A preferable range of the width T7d is, for example, 20 μm or more and 200 μm or less. A preferable range of the arrangement pitch P7d is, for example, 20 μm or more and 200 μm or less.
In this embodiment, in particular, P7d = T7d.

On the light deflection surface 7 a of the light guide 7, a light deflection element 18 that deflects incident light from the light source 6 toward the emission surface 7 b is formed.
Examples of the light deflection element 18 include a reflective surface patterned by printing and an example of a dot-like structure. However, when the light deflection element 18 is formed of a printing pattern, when the light incident from the light incident surface 7L is scattered by the printing pattern, the unit lens 7d is scattered in all directions without directivity. There is also a possibility that the light scattered by can not be collected effectively.
For this reason, the light deflection element 18 is more preferably a dot-like structure.

As a dot-like structure suitable for the light deflection element 18, the light incident from the light incident surface 7L and internally reflected in the light guide 7 is guided by an angle smaller than the incident angle with respect to the light deflection surface 7a. There is no particular limitation as long as it can be deflected in such a direction. For example, a concave microlens shape, a convex microlens shape, a pyramid shape, a conical shape, or the like can be given. The amount of light deflection by the light deflection element 18 toward the exit surface 7b increases as the area occupied by the light deflection element 18 per unit area increases.
The light deflection element 18 made of a dot-like structure can select either a convex portion or a concave portion, and can also be used by mixing the convex portion and the concave portion.
When the light deflection element 18 is formed of a concave portion formed on the light deflection surface 7a, the light incident from the light incident surface 7L is totally reflected on the inner surface of the light deflection element 18 which is a convex surface in the light guide 7, and directivity is obtained. Light travels from the light deflection surface 7a side toward the exit surface 7b above it. Such deflected light can be efficiently collected by the unit lens 7d.

In the present embodiment, a concave microlens is employed as an example of the light deflection element 18. Specifically, a concave elliptical surface formed in the range of an ellipse whose major axis is directed in the X direction in plan view (Z direction view) is adopted.
That is, as shown in FIGS. 2B and 2C, the light deflection element 18 of this embodiment has a major axis in the plan view of wx, a minor axis of wy, and a depth from the optical deflection surface 7a of h18. . A preferable range of the major axis wx is, for example, 30 μm or more and 100 μm or less. A preferable range of the minor axis wy is, for example, 30 μm or more and 100 μm or less. A preferable range of the depth h18 is, for example, 2 μm or more and 20 μm or less.

In such a light deflection element 18, the arrangement density in the X direction is substantially uniform at each position in the Y direction, and in the Y direction from each light incident surface 7L toward the center of the light guide 7 in the Y direction. It arrange | positions so that the arrangement | positioning density along may increase gradually.
For this reason, the average arrangement density of the light deflection elements 18 is symmetric with respect to the center plane S7. In the following, as shown in FIG. 2C, the distance between each light incident surface 7L is dy, and in the light guide 7, the distance dy / 2 from one light incident surface 7L to the center plane S7 in the Y direction is The first region 7A in the range and the second region 7B in the range of the distance dy / 2 from the other light incident surface 7L to the center surface S7 are referred to.

With reference to FIGS. 4 to 6, the arrangement of the light deflection elements 18 will be described in detail using an example of the first region 7 </ b> A.
The arrangement pattern of the light deflection elements 18 is divided into a plurality of regions in the Y direction. As an example, FIG. 4 shows a case where the light is divided into three regions a, b, and c in order from the light incident surface 7L side. However, the method of dividing the region is not limited to this, and the number of divisions and the size of the divided regions can be appropriately selected.
In each of the regions a, b, and c, as schematically shown in FIG. 5, m light deflection elements 18 are arranged in the X direction and n in the Y direction. However, the sizes of m and n differ depending on each region.
Hereinafter, an arrangement pattern common to each region will be described, and different points will be described as necessary. In this case, when it is clearly stated that the numerical values are different depending on the respective areas a, b, and c, the area names are added with suffixes such as ma, na, mb, nb, mc, and nc. Unless otherwise specified, other variables and constants are also represented in the same manner.

  The light deflection elements 18 are arranged in a straight line in the X direction to form unit rows, and these unit rows are arranged at different intervals in the Y direction. The na, nb, and nc unit columns arranged in the regions a, b, and c constitute a unit group.

The light deflection element 18 of each unit group is represented as E (i, j). Here, i is an integer sign attached to the light deflection elements 18 arranged from the first to the m-th from one end side (the lower end side in the figure) to the other end side in the X direction. j is an integer attached to the light deflection elements 18 arranged from the first to the n-th from the end (left side in the figure) on the light incident surface 7L side in the Y direction toward the end opposite to the light incident surface 7L. It is a sign.
Further, the position coordinates of E (i, j) are expressed as (x _ij , y _ij ).

The average pitch Px _j in the X direction in each unit row is equal to a constant average pitch Px regardless of j, as shown in the following equation (5). Δx _{ij in} the following equation (5) is an adjacent interval (center-to-center distance) between E (i + 1, j) and E (i, j), and is represented by the following equation (6).
The average pitch Px is different for each of the regions a, b, and c, and is Pxa, Pxb, and Pxc (where Pxa>Pxb> Pxc), respectively.

Further, each unit column is different from the other two or more adjacent unit columns in the arrangement position in the X direction.
Here, “two or more adjacent columns” means two or more columns in a neighboring region on one side. That is, when two unit columns are present in the vicinity on both sides in the Y direction, the arrangement is different from at least the four neighboring columns. In addition, when there are only one unit column or less on one side as in the unit column at the end in the Y direction, the arrangement is different from one column or less on one side and at least two columns on the other side. .
Further, “the arrangements are different from each other” means that the positions of the light deflection elements in the unit row are different as a whole. Here, “as a whole” includes the case where all the positional relationships do not match and the case where some of them match. In the case where some of them match, it is assumed that the matching rate is 10% or less of the light deflection elements constituting the unit column.

In this embodiment, as an example, the arrangement positions of the unit columns are made different from each other for all j with high probability. In order to realize such an arrangement, in the present embodiment, the position of the light deflection element 18 in each unit column in the X direction is set so that the adjacent interval Δx _ij changes in the X direction.
In the present embodiment, the change in the X direction of the adjacent interval Δx _ij satisfies the following expressions (7) and (8).

Here, CV is obtained by dividing the standard deviation of the adjacent interval Δx _ij in each unit column by the average value Px _j (= Px) as defined by the above equation (8), and the adjacent interval Δx _ij Coefficient of variation.
In the normal distribution, about 99.7% of the whole is included in the range of ± 3σ of the average value. Therefore, when the distribution of Δx _ij is the normal distribution, about 99.7% of the above expression (7) It means that it is below Px.
Therefore, the above formula (7) includes the case where the adjacent light deflection elements 18 overlap each other. However, in order to deflect light more efficiently by the light deflection element 18, it is preferable that the light deflection elements 18 do not overlap each other.
For this reason, in order to reduce the probability that such overlap occurs, the CV is more preferably 1/8 or less, 1/10 or less, and the like.
Further, in order to reliably prevent the overlap, it is more preferable to satisfy the following expression (9) in addition to the above expressions (7) and (8).

Δx _ij that changes in such a range may change regularly as long as the arrangement is different in two or more neighboring columns, or may change so as not to have regularity. Good. When there is no regularity, it may change randomly or may change based on a specific probability density distribution.

When the Y-direction adjacent spacing (inter-center distance) Δy _j between unit columns is expressed by the following equation (10), Δy _j decreases as j increases in the unit group. Thereby, the arrangement density (hereinafter simply referred to as density) D of the light deflection elements 18 is a function that monotonously increases as the distance from the light incident surface 7L increases in the Y direction in the unit group.
Here, the density D is a ratio of the projected area of the light deflection element 18 per unit area to the light deflection surface 7a.

  Here, the change in the density D is set so that the luminance distribution emitted from the light guide 7 can be made substantially uniform (including the case where it is uniform). In the present embodiment, as shown in the graph of FIG. A monotonically increasing function (see curve 100) that increases with distance from the light incident surface 7L is adopted throughout the regions a, b, and c.

Here, in the case of being substantially uniform, the luminance unevenness may be uniformly distributed over the entire light guide 7 or may have a distribution in which the luminance unevenness tends to be present.
For example, in applications such as the liquid crystal display device 1, it is preferable that the luminance of the central portion of the screen is higher than the peripheral portion of the screen from the viewpoint of display quality. It is more preferable that the distribution has a higher luminance.

For example, when the coordinate value in the Y direction of the light incident surface 7L is Y = 0 and the coordinate value in the center plane S7 is Y = dy / 2, the density D changes as follows. Yes, it increases substantially linearly as the y coordinate increases, and increases rapidly from Y = 0.6 · dy / 2 to y = dy / 2, and when Y = dy / 2, A change such that the maximum density Dmax = 10 · D0 can be employed.
Since the average pitch Px of the light deflection elements 18 is constant for each unit group, the density D is substantially constant in the X direction (including a constant case) as schematically shown as the straight line 101 in FIG. ).

If the density D is small, the amount of light incident from the light incident surface 7L is deflected in the direction along the visual direction F, and the luminance of the light emitted from the emission surface 7b decreases.
For this reason, the density D0 needs to be 0.01 or more.
When the density D is less than 0.01, for example, in the light guide 7 having a thickness of 3 mm and a size of 40 inches (500 mm × 900 mm), the luminance reduction rate in the vicinity of the light incident surface 7L is as large as 30% or more.
The luminance reduction rate defined here refers to the reduction rate with respect to the maximum value of the luminance within the surface of the light guide 7.
When the luminance reduction rate is 30% or more, when the illumination device 3 is viewed from the diffusion sheet 28 side, the luminance difference between the vicinity of the light incident surface 7L and the central portion can be clearly seen with eyes. A quality problem of the display device 1 occurs. The density D is required to be 0.01 or more so that the luminance reduction in the vicinity of the light incident surface 7L of the light guide 7 cannot be visually recognized.

  As a function suitable as such a change in the density D, an example of a function represented by the following equation (11) can be given, where y is a position coordinate in the Y direction with the light incident surface 7L as the origin.

In the above formula (11), the variable B is a variable contributing to the luminance distribution at the position in the Y direction.
This arrangement is possible because the average pitches Pxa, Pxb, and Pxc in the X direction in the unit group have different sizes and decrease in this order.

Next, an example of a method for arranging the light deflection elements 18 in this way will be described.
In the present embodiment, the regular reference arrangement area of the light deflection elements 18 is determined so that the density D of the light deflection elements 18 satisfies the above formula (11). Next, the final arrangement of the light deflection elements 18 is determined by randomly shifting the light deflection elements 18 in the X direction from the center position of the reference arrangement area.

A reference array area e (i, j) in the unit group of the light deflection element 18 is indicated by a broken line in FIG.
The reference array area e (i, j), like E (i, j), forms m unit rows along the direction, and this unit row has an adjacent interval Δy _j in the Y direction and n A column is arranged.
The position coordinates of e (i, j) are expressed as (X _ij , Y _ij ).
e (i, j) are arranged at equal intervals in the X direction at a constant pitch equal to the average pitch Px of the light deflection elements 18 in the X direction.
Further, the unit columns adjacent in the Y direction are arranged so as to be alternately shifted in the X direction by ½ of the average pitch Px.
Here, the average pitch Px is Pxa, Pxb, and Pxc different from each other in the regions a, b, and c (where Pxa>Pxb> Pxc), as described above.
That is, the average pitch Px changes discontinuously at the boundaries of the regions a, b, and c, and decreases as the distance from the light incident surface 7L increases.
For this reason, for example, in order to make the density D of the reference arrangement area equal at the boundary between the areas a and b, the adjacent interval in the X direction has a relationship of Pxa> Pxb as shown in FIG. Δy _na , Δy _1b , which are adjacent intervals, may be set to appropriate values such as Δy _na <Δy _1b .

Next, the position coordinates (x _ij , y _ij ) of E (i, j) are set by the following equations (12) to (16).

Here, the coefficient α is a constant that defines the maximum value of the deviation width in the X direction with respect to the reference arrangement area e (i, j) of the light deflection element E (i, j), and is an appropriate value greater than 0 and less than 1. Can be adopted.
Rn (i, j) is a random function that generates a numerical value randomly selected from a numerical range of 0 to 1. _Therefore, the amount of deviation from _{X ij} of _{x ij} is changed randomly. Therefore, the adjacent interval Δx _ij also changes randomly.
As shown in the above equation (15), δ (j) is a function that becomes 1 when j is an even number and 0 when it is an odd number.
Y ₁ is a coordinate value in the Y direction of the unit row closest to the light incident surface 7L in the unit group, and takes values of Y ₁ a, Y ₁ b, and Y ₁ c for each region.

When α is 0 in the above equation (11), all the light deflection elements E (i, j) are regularly arranged in the same manner as the reference arrangement area e (i, j). However, since α is larger than 0, the regularity is reduced according to the size of α, and the adjacent interval Δx _ij has a certain variation.
When α is equal to or greater than 1 in the above formula (11), the light deflection element E (i, j) is shifted in the X direction, and the adjacent light deflection element E (i−1, j) or E (i + 1, j) Touch or overlap. However, since α is less than 1, a gap is surely formed between the adjacent light deflection elements E (i−1, j) and E (i + 1, j).
For this reason, the adjacent distance Δx _ij in the X direction in the light deflection element E (i, j) shows a variation satisfying the expression (7).
It can also be seen that the adjacent interval Δx _ij is in the range of the above equation (9).

The smaller the value of α, the stronger the regularity of the arrangement of the light deflection elements E (i, j), and the less the effect of moire suppression described later.
Further, the larger the value of α, the larger the variation in the distance between the light deflection element E (i, j) and the adjacent light deflection element E (i−1, j) or E (i + 1, j), Unevenness of the deflected light tends to occur.
For this reason, the range of α is preferably narrower. For example, the lower limit value is more preferably 0.2, 0.4, and the upper limit value is more preferably 0.4, 0.6.

The density D of the light deflection elements E (i, j) arranged in this way will be described.
As shown in FIG. 5, since the reference arrangement area e (i, j) is regularly arranged, the density De can be accurately calculated. The design value of the density D of the light deflection element E (i, j) can be calculated similarly.
If the area of the measurement area of an appropriate size is R, and the area of the reference arrangement area e (i, j) included therein is Sa, then by measuring the area Sa, De = Sa / R Can be sought.
For example, the measurement area for obtaining the density De of e (i, j) is, for example, a distance from the center of an adjacent unit column in the Y direction to Px or more in the X direction as indicated by a two-dot chain line in FIG. The density De can be measured by adopting a rectangle having a size equal to or greater than the sum of Δy _i-1 + Δy _i .
On the other hand, the arrangement position of the light deflection element E (i, j) in the X direction varies depending on the location. For this reason, when the density D of the light deflection element E (i, j) is actually measured, the same measurement is repeated while changing the measurement position in the X direction, and the average is obtained.
In the present embodiment, the position of the light deflection element E (i, j) in the X direction is randomly shifted from the position of the reference array area e (i, j). Therefore, if a sufficient number of measurements are performed, The average value of the density D matches the density De of the reference arrangement area e (i, j).

  Heretofore, the configuration of the light guide 7 has been described in the example of the first region 7A. Since the configuration of the second region 7B arranged symmetrically with this is the same except for the difference in the arrangement position, detailed description is omitted.

  Examples of a light-transmitting material suitable for the light guide body 7 having such a configuration include, for example, an acrylic resin typified by PMMA (polymethyl methacrylate), a PET (polyethylene terephthalate) resin, a PC (polycarbonate) resin, and a COP. Examples thereof include transparent resins such as (cycloolefin polymer) resin, PAN (polyacrylonitrile copolymer) resin, and AS (acrylonitrile styrene copolymer) resin.

As a manufacturing method of the light guide 7, the light deflection element 18 and the unit lens 7d are integrally formed by using the resin as described above by an extrusion molding method, an injection molding method, or a hot press molding method. Is possible. Alternatively, after the plate-like member is formed by the above-described manufacturing method, the light deflection element 18 and the unit lens 7d are formed by using, for example, a printing method, a UV curable resin, a radiation curable resin, or the like, so that the light guide body is formed. 7 can also be produced.
The light guide 7 is preferably formed by integrally molding the light deflection element 18 and the unit lens 7d using the extrusion molding method among the manufacturing methods described above. In this case, the number of steps for producing the light guide 7 is reduced, and the mass productivity can be increased because the molding is performed by roll-to-roll.

Next, the operation of the liquid crystal display device 1 and the illumination device 3 of the present embodiment having such a configuration will be described focusing on the operation of the light guide 7 of the present embodiment.
FIG. 7A is a plan view schematically showing a state of light propagation in the light guide according to the first embodiment of the present invention. FIG.7 (b) is a schematic diagram of the C view in Fig.7 (a). FIG. 8A is a plan view schematically showing a state of light propagation in the light guide of the first comparative example that does not have a unit lens. FIG. 8B is a schematic diagram of view D in FIG. FIG. 9A is a schematic diagram showing a luminance distribution in plan view in the light guide according to the first embodiment of the present invention. FIG. 9B is a schematic diagram showing the luminance distribution in the light guide of the first comparative example that does not have a unit lens. FIG. 10A is a schematic diagram illustrating an example of an image of a light deflection element viewed through a unit lens. FIG. 10B is a schematic diagram illustrating an example of an image of the light deflection element viewed through the unit lens and the isotropic light diffusing member.

As shown in FIGS. 7A and 7B, when each light source 6 is turned on, the light from the light source 6 enters the front light incident surface 7L while diffusing.
The light incident on the light incident surface 7L is guided toward the center surface S7 while being repeatedly reflected between the light deflecting surface 7a and the exit surface 7b. At this time, the light reflected in the direction spreading in the X direction by the light deflecting surface 7a is internally reflected on the convex surface (concave surface from the inner surface side) of the unit lens 7d, as shown in FIG. Light is guided while changing position. However, since the unit lens 7d has an outwardly convex U-shaped cross section, incident light is collected and reflected toward the light deflection surface 7a below the unit lens 7d. For this reason, as shown in FIG. 7A, the reflected light by the internal reflection of the unit lens 7d does not spread so much in the X direction, but is guided along the Y direction, which is the extending direction of the unit lens 7d.
Thus, in this embodiment, since the exit surface 7b is configured by the unit lens 7d, the light incident from the light source 6 is guided along the extending direction by the unit lens 7d positioned in front of the light source 6. Lighted.
Although only one light source 6 is shown in FIG. 7B, since a plurality of light sources 6 are arranged along the X direction, the light from the other light sources 6 is similarly centered. The light is similarly guided toward S7.

On the other hand, in the case of the light guide 70 in which the unit lens 7d is deleted from the light guide 7 of the present embodiment as in the first comparative example shown in FIGS. 8A and 8B, the emission surface 70b is The plane is parallel to the light deflection surface 7a.
Therefore, the light emitted from the light source 6 in the oblique direction toward the light deflection surface 7a and the emission surface 70b is internally reflected and guided in the X direction as shown in FIG. 8B.
In plan view, as shown in FIG. 8A, the light beam diffused from the light source 6 is guided toward the center plane S7 in a fan-shaped state without being condensed.
As described above, in the light guide body 70 of the first comparative example, the light from the light source 6 is diffused and guided in the left and right directions in the X direction. Decreases with distance from 7L.
Therefore, the brightness of the light guided by the light guide 7 is suppressed from being diffused in the X direction even at a position away from the light incident surface 7L as compared to the first comparative example. There is much less decrease in brightness.

Heretofore, the light guide path in the light guide 7 has been described with reference to an example in which light enters from one light source 6 to the light incident surface 7L. In the liquid crystal display device 1, since a plurality of such light sources 6 are arranged along the extending direction of the light incident surface 7 </ b> L, the light guide 7 as a whole has a luminance distribution in which the light from each light source 6 is superimposed. become.
In the light guide 7, incident light from the light source 6 is guided to a narrow range in front of the light source 6 as described above. For this reason, as shown in FIG. 9A, luminance unevenness does not occur even if the light incident from each light source 6 is overlapped, and substantially uniform luminance is combined with the action of the light deflection element 18 described later. Distribution is obtained.
On the other hand, in the light guide 70 of the first comparative example, the incident light from the light source 6 spreads in a fan shape and propagates in front of the light source 6 as described above. For this reason, even if the light deflection element 18 similar to that of the light guide 7 is provided, as shown in FIG. 9 (b), the both ends in the X direction spread from the light incident surface 7L toward the center surface S7. A triangular dark portion Sh is generated.

Next, the operation of the light deflection element 18 will be described.
Since many light deflection elements 18 are formed on the light deflection surface 7 a of the light guide 7, the light that has reached the light deflection element 18 is deflected according to the surface shape of the light deflection element 18. The Specifically, since the light is scattered by the light deflection element 18, the component deflected toward the exit surface 7 b immediately above the light deflection element 18 increases. For this reason, each light deflection element 18 has an effect equivalent to that of a point light source disposed on the light deflection surface 7a.
As shown in FIG. 3, the deflection component of the light deflection element 18 has a smaller incident angle at the exit surface 7b than the reflected light that is totally reflected and guided by the light deflection surface 7a. It passes through and is injected outside. At this time, since the emitted light is collected by the lens action of the unit lens 7d, the emitted light is emitted along the visual direction F as a light beam whose spread in the X direction is suppressed (see the light K in FIG. 3).
Therefore, when the light guide 7 is observed from the exit surface 7 b side, it is visually recognized that the linear light source is disposed at the position of the light deflection element 18 due to the deflection component of the light deflection element 18.
That is, when the light guide 7 is observed from the exit surface 7b side through the unit lens 7d, the light deflection element 18 appears to expand linearly in the X direction as shown by a solid line in FIG. However, since FIG. 10A is a schematic diagram, the light deflection elements 18 are repeatedly arranged at a pitch Lx in the X direction and at a pitch Ly in the Y direction.
Actually, since the light deflection elements 18 of the light guide 7 are randomly arranged in the X direction, the image of the light deflection elements 18 spreading linearly is also randomly displaced in the X direction.

The light emitted from the emission surface 7b enters the isotropic light diffusion member 8 and isotropically diffuses. Thereby, the unevenness of the luminance distribution according to the arrangement position of the light deflecting element 18 is leveled, and the image of the light deflecting element 18 by the deflected light spreads in the X direction and the Y direction and becomes blurred.
FIG. 10B schematically shows how an image of the light deflection element 18 is seen when the light guide 7 is observed through the isotropic light diffusing member 8. As shown in FIG. 10B, the image of the light deflecting element 18 is also spread in the Y direction by the isotropic light diffusing member 8, so that it is visually recognized as a planar light source overlapping each other in the X direction and the Y direction. The As a result, a dot-like image of the light deflection element 18 and a linear image in which the light deflection element 18 is continuous in the X direction are not visually recognized.

The light transmitted through the isotropic light diffusing member 8 enters the light collecting sheet 20 and is collected toward the visual direction F.
The light emitted from the light collecting sheet 20 enters the diffusion sheet 28 and is diffused, and the luminance unevenness caused by the light collecting direction of the light collecting sheet 20 is leveled.
In this way, light with suppressed luminance unevenness is emitted from the diffusion sheet 28, and the image display element 2 is illuminated from the polarizing plate 10 side.
In this state, when the image display element 2 is driven according to the image signal, an image or video corresponding to the image signal is displayed on the image display element 2, and the image or video can be observed from the outside. .

Here, the operation of the light deflection element 18 of the light guide 7 will be described in detail.
In the light guide 7, in each of the first region 7A and the second region 7B, the density D of the light deflection element 18 monotonously increases from the light incident surface 7L toward the center surface S7.
For this reason, the deflection component in the visual direction F by the light deflection element 18 increases in proportion to the density D.
Therefore, by increasing the density D of the light deflection element 18 so as to cancel out the luminance decrease during propagation in the Y direction in the light guide 7, the luminance distribution in the Y direction of the emitted light on the exit surface 7 b. Can be made uniform.
Further, in the X direction, although the arrangement position of the light deflection element 18 is randomly changed with a gap between the light deflection elements 18 adjacent to each other, as indicated by a straight line 101 in FIG. On the average, they are arranged at a substantially uniform density in the X direction, so that luminance unevenness in the X direction is suppressed.

In the light guide 7 of the present embodiment, in order to realize such an arrangement of the density D, the first region 7A and the second region 7B are respectively arranged in the Y direction according to, for example, the regions a, b, and c. The light deflection element 18 is divided into a plurality of unit groups, and the average pitch in the X direction is changed to Pxa, Pxb, Pxc for each unit group. Accordingly, the adjacent interval in the Y direction of each unit row in each unit group is gradually reduced from the light incident surface 7L side to the center plane S7 side, and the average pitch in the X direction at the boundary of the unit group The adjacent spacing in the Y direction changes discontinuously.
Thus, since the density D that monotonously decreases is formed by the combination of the adjacent interval in the X direction and the adjacent interval in the Y direction, the luminance distribution in the Y direction can be made substantially uniform and the Y direction can be made uniform. The unevenness of the light deflection element 18 can be suppressed. As a result, the light extraction efficiency is improved, and it is possible to suppress luminance unevenness due to the uneven density of the light deflection element 18.
These points will be described with reference to the second comparative example and the third comparative example of the light guide 7.
FIG. 11 is a schematic diagram illustrating a second comparative example of the arrangement pattern of the light deflection elements. FIG. 12 is a schematic diagram illustrating a third comparative example of the arrangement pattern of the light deflection elements.

The light guide 71 of the second comparative example shown in FIG. 11 includes the light deflection element 18 so that each of the first region 7A and the second region 7B of the light guide 7 forms a unit group similar to the region a. It is an example in the case of arrangement.
Therefore, in each unit column, the average pitch in the X direction is Pxa, and the number of unit columns in the Y direction is Na, which is larger than na. The adjacent interval in the Y direction of the unit column is a decreasing number sequence such as Δy _1a ,..., Δy _Na .
In such an arrangement, in order to increase the density D of the light deflection elements 18 steeply in the vicinity of the center plane S7, it is necessary to narrow the adjacent interval Δy _ja of the unit rows. However, even if the adjacent interval Δy _ja is close to 0, there is a gap in the X direction, and therefore the density D cannot be increased beyond a certain limit. For this reason, for example, as indicated by the curve 102 in the graph of FIG. 11, the maximum value Dmax ′ of the density D cannot be increased too much.
Thereby, in the vicinity of the center plane S7, the deflection component in the visual direction F by the light deflection element 18 is reduced, and the luminance of the emitted light from the emission surface 7b is reduced, so that the light guide 7 of the present embodiment. Compared to the above, the uniformity of the luminance distribution in the Y direction is significantly reduced.
Further, since the light that has not been deflected by the light deflection element 18 is directly guided into the light guide 71, for example, a large amount of light leaks from the light incident surface 7L on the opposite side and is extracted from the exit surface 7b. I can't. Therefore, it is not possible to obtain a high-luminance lighting device 3.

In the light guide 72 of the third comparative example shown in FIG. 12, the light deflection element 18 is configured such that each of the first region 7A and the second region 7B of the light guide 7 is formed as one region d. This is an example in the case of arranging.
However, unlike the light guide 71 of the second comparative example, the average pitch Pxd in the X direction (where Pxd <Pxa) is the maximum density Dmax that requires the density D of the light deflection elements 18 in the vicinity of the center plane S7. It is set to be. Accordingly, the number of unit columns in the Y direction is Md, and the adjacent interval in the Y direction of the unit columns is a monotonically decreasing number sequence such as Δy _1d ,..., Δy _Md .
Here, since Pxd <Pxa, the adjacent interval in the Y direction in the vicinity of the light incident surface 7L needs to be wider than the adjacent interval in the corresponding light guide 7 such as Δy _1d > Δy _1a. is there.
According to such an arrangement, the change in the density D is equivalent to that in the light guide 7. For this reason, the luminance of the deflected light in the visual direction F is kept high even in the vicinity of the center plane S7, and the amount of light leaking from the light incident surface 7L on the opposite side is reduced. Is obtained.
However, since the average pitch Pxd of each unit row is small, the unit row becomes linear and is easily visible. In particular, in the vicinity of the light incident surface 7L, the adjacent interval in the X direction is narrowed and the adjacent interval in the Y direction is conversely widened. As a result, a gap is generated between the unit columns in the Y direction, so that the linear light is easily noticeable. . That is, the uniformity of the light source is deteriorated, resulting in uneven brightness, and the images of the light sources arranged in a line are easily visually recognized.

  According to the arrangement of the light deflection elements 18 of the light guide 7 of the present embodiment, problems such as a decrease in luminance, luminance unevenness, and increase in the visibility of the light source in the second comparative example and the third comparative example are suppressed.

Next, the operation of the arrangement of the light deflection elements 18 for each unit group will be described.
When the light deflection elements 18 are regularly arranged in the X direction in the unit group, the light deflection elements 18 are regularly arranged in the X direction with the arrangement pitch P7d, and the X direction and the Y direction. Since the image display element 2 having pixels arranged at a constant pixel pitch overlaps with the image display element 2, moire may be visually recognized due to a periodic shift in pitch.
Such moire impairs the illumination quality and display quality of the illumination device and the liquid crystal display device.
In the illumination device 3 and the liquid crystal display device 1 of the present embodiment, since the light guide 7 of the present embodiment is used, the adjacent spacing of the light deflection elements 18 varies irregularly in the X direction. It does not have regularity of adjacent spacing. For this reason, moire is suppressed.
Further, in the light guide 7, since the adjacent interval also changes in the Y direction, moire does not occur between the pixels of the image display element 2.

Thus, in the liquid crystal display device 1 and the illumination device 3 of the present embodiment, the light deflection elements 18 are divided into a plurality of unit groups so that the density D increases in the Y direction as the distance from the light incident surface 7L increases. The light guide 7 is disposed and the adjacent interval of the light deflection elements 18 is changed so that the average pitch Px is constant in the X direction.
For this reason, the light guide 7 can efficiently extract the light incident from the light source 6 from the emission surface 7b and emit high-luminance light. In addition, luminance unevenness can be suppressed along the X direction and the Y direction. In addition, since the arrangement of the light deflection elements 18 does not have regularity, it is possible to make the image and moire of the light deflection elements less visible. Thereby, the display quality and illumination quality of the liquid crystal display device 1 and the illumination device 3 can be improved.

When the illumination device 3 is applied as a backlight such as a liquid crystal display, for example, it is desirable to increase the surface center luminance while maintaining in-plane luminance uniformity within a certain reference.
According to the arrangement of the light deflection element 18 in the light guide 7 of the present embodiment, a coarse and dense distribution is obtained that is sparser as it is closer to the light incident surface 7L and denser as it is farther from the light incident surface 7L. The surface center luminance can be increased without sacrificing the in-plane luminance uniformity of the device 3.

[First Modification]
Next, a light guide 37 according to a first modification of the first embodiment of the present invention will be described.
FIG. 13A is a schematic perspective view showing an example of a light guide according to a first modification of the first embodiment of the present invention. FIGS. 13B and 13C are an EE sectional view and an FF sectional view in FIG.

As shown in FIGS. 13A, 13 </ b> B, and 13 </ b> C, the light guide 37 of the present modification is an optical deflection instead of the light deflection element 18 of the light guide 7 of the first embodiment. Element 38 is provided.
The light guide 37 of this modification can be used in place of the light guide 7 in the liquid crystal display device 1 and the illumination device 3 of the first embodiment.
Hereinafter, a description will be given centering on differences from the first embodiment.

The light deflection element 38 of the light guide 37 is a convex portion protruding from the light deflection surface 7a, whereas the light deflection element 18 of the first embodiment is composed of a depression formed on the light deflection surface 7a. Only one point is different.
That is, the light deflection element 38 has an elliptical shape with a major axis wx and a minor axis wy similar to the light deflection element 18 in a plan view, and the protrusion height from the light deflection surface 7a is h38. A preferable range of the protrusion height h38 is, for example, 2 μm or more and 20 μm or less.
The arrangement pattern of the light deflection elements 38 is the same as that of the light deflection elements 18 of the first embodiment.
Such a light guide 37 can be manufactured by the same method as the light guide 7 of the first embodiment.

According to the light guide 37, when light incident from the light incident surface 7L and guided between the exit surface 7b and the light deflection surface 7a is irradiated, the light deflection element 38 is concave from the inner surface side. Are internally reflected and collected along the concave optical axis. For this reason, a deflection component directed in the visual direction F is generated.
Therefore, the light deflection element 38 of this modification and the illumination device 3 and the liquid crystal display device 1 including the same are the same as the light guide 7, the illumination device 3, and the liquid crystal display device 1 of the first embodiment. Luminance light can be emitted, and the image and moire of the light deflection element can be made difficult to see.

[Second Embodiment]
Next, the light guide according to the second embodiment of the present invention will be described.
FIG. 14 is a schematic diagram showing details of the arrangement pattern of the light deflection elements of the light guide according to the first embodiment of the present invention.

As shown in FIGS. 1 and 2, the light guide 47 of the present embodiment is different from the light deflection element 18 of the light guide 7 of the first embodiment only in the arrangement pattern in the X direction of the light deflection element 18. The light deflection element 48 is changed.
The light guide 47 can be used in place of the light guide 7 in the liquid crystal display device 1 and the illumination device 3 of the first embodiment.
Hereinafter, a description will be given centering on differences from the first embodiment.

In the light deflection element 48, the arrangement density in the X direction is substantially uniform at each position in the Y direction, similarly to the light deflection element 18 in the light guide body 7 of the first embodiment, and from each light incident surface 7L. It arrange | positions so that the arrangement | positioning density along a Y direction may increase gradually toward the center of the Y direction of the light guide 7. As shown in FIG.
For this reason, also in the light guide 47, the average arrangement density of the light deflection elements 48 in the first region 7A and the second region 7B is symmetric with respect to the center plane S7.

Hereinafter, the arrangement of the light deflection elements 48 will be described with an example in the case of the first region 7 </ b> A, focusing on differences from the first embodiment.
The arrangement pattern of the light deflection elements 48 is divided into a plurality of regions in the Y direction as in the light guide 7, and as shown in FIG. 4, for example, regions a, b, c are sequentially arranged from the light incident surface 7L side. Are divided into a plurality of regions.
In each of the regions a, b, and c, as schematically shown in FIG. 14, m light deflection elements 48 are arranged in the X direction and n in the Y direction. However, the sizes of m and n differ depending on each region.
Hereinafter, the arrangement common to each region will be described, and different points will be described as necessary. At this time, when it is clearly stated that the numerical values are different depending on the areas a, b, and c, the area names are added with suffixes such as ma, na, mb, nb, mc, and nc. Unless otherwise specified, other variables and constants are also represented in the same manner.

  The light deflection elements 48 are arranged in a straight line in the X direction to form unit rows, and these unit rows are arranged at different intervals in the Y direction. The na, nb, and nc unit columns arranged in the regions a, b, and c constitute a unit group, and are arranged as described below.

The light deflection element 48 of each unit group is represented as F (i, j). Here, i is an integer sign attached to the light deflection elements 48 arranged from the first to the m-th from one end side (the lower end side in the figure) to the other end side in the X direction. j is an integer attached to the light deflection elements 48 arranged from the first to the n-th from the end (left side in the figure) on the light incident surface 7L side in the Y direction toward the end opposite to the light incident surface 7L. It is a sign.
In addition, the position coordinates of F (i, j) are expressed as (x _ij , y _ij ).

The adjacent spacing in the X direction in each unit row is equal to a constant pitch Qx. Here, the adjacent interval is, for example, a center-to-center distance between F (i + 1, j) and F (i, j).
The pitch Qx is different for each of the regions a, b, and c, and is Qxa, Qxb, and Qxc (where Qxa>Qxb> Qxc), respectively.
The pitch Qx adopts the same value as the average pitch Px in the first embodiment.

Further, each unit column is different from the other two or more adjacent unit columns in the arrangement position in the X direction.
In this embodiment, as an example, the arrangement positions of the unit columns are made different from each other for all j with high probability. In order to realize such an arrangement, in this embodiment, the position in the X direction of the entire light deflection element 48 in each unit column is set to change in the X direction.
When the coordinate value representing the position in the X direction of each unit column is X _j , the following expressions (17) and (18) are satisfied.
As the coordinate value X _j , for example, x _1j that is the x coordinate of F (1, j) can be adopted.

Here, δ (j) is a function defined by the above equation (16).
In the above equation (18), each unit row has a deviation amount ΔX _j = X _j −X ₁ with respect to the reference position where the position in the X direction is shifted by Qx / 2 every other row in the Y direction. The standard deviation of the deviation amount ΔX _j is shown.
The above equation (17) represents the range of the ratio of this standard deviation to the pitch Qx. In the normal distribution, about 99.7% of the whole is included in the range of ± 3σ of the average value. Therefore, when the distribution of the deviation amount ΔX _j is a normal distribution, the above equation (16) is about 99.7%. It means that it is within the range of ± Qx / 2.

The Y-direction adjacent interval (center-to-center distance) between the unit columns is Δy _j similar to that in the first embodiment.
The change in the density D is the same as that in the first embodiment.

Next, an example of a method for arranging the light deflection elements 48 in this way will be described.
In the present embodiment, as in the first embodiment, the regular reference arrangement area of the light deflection elements 48 is determined so that the density D of the light deflection elements 48 satisfies the above formula (11). . Next, the final arrangement of the light deflection elements 48 is determined by randomly shifting the light deflection elements 48 in the X direction for each unit column from the center position of the reference arrangement area.

The reference array area in the unit group of the light deflection elements 48 is e (i, j) similar to that in the first embodiment (see the broken line in FIG. 14).
However, the arrangement interval in the X direction at e (i, j) is equal to the pitch Qx.
Further, the unit columns adjacent in the Y direction are arranged so as to be alternately shifted by a half of the pitch Qx in the X direction.
That is, the pitch Qx changes discontinuously at the boundaries of the regions a, b, and c, and decreases as the distance from the light incident surface 7L increases.

Next, position coordinates (x _ij , y _ij ) of F (i, j) are set by the following equations (19) to (23).

Here, the coefficient β is a constant that defines the maximum value of the deviation width in the X direction with respect to the reference arrangement area e (i, j) of the light deflection element F (i, j), and is an appropriate value greater than 0 and less than 1. Can be adopted.
Rn (j) is a random function that generates a numerical value randomly selected from a numerical range of 0 or more and 1 or less.
δ (j) is a function defined by the above equation (16).
Y ₁ is a coordinate value in the Y direction of the unit row closest to the light incident surface 7L in the unit group, and takes values of Y ₁ a, Y ₁ b, and Y ₁ c for each region.

In the above equation (23), when β becomes 0, all the light deflection elements F (i, j) are regularly arranged in the same manner as the reference arrangement area e (i, j). However, since α is larger than 0, ΔX _j changes according to the size of α, so that the entire light deflection element F (i, j) is in the reference array area e (i, j) for each unit column. Deviate. For this reason, for example, if the coordinates x _1j of F (1, j) are totaled in the Y direction, a certain variation occurs.
In the above formula (23), when β is 1 or more, the light deflection element 48 comes off at one end in the X direction, and the density D in the X direction changes. However, since β is less than 1, the density D in the X direction is constant even at the end in the X direction.

The smaller the value of β, the stronger the regularity of the arrangement of the light deflection elements F (i, j), and the less the effect of suppressing moire.
Further, the larger the value of β, the more the light deflection element 18 becomes Y between the light deflection element F (i, j) and the adjacent light deflection element F (i−1, j) or F (i + 1, j). It becomes easy to adjoin in the direction, and unevenness of the deflected light easily occurs.
For this reason, it is preferable that the range of β is narrower. For example, the lower limit is more preferably 0.2, 0.4, and the upper limit is more preferably 0.4, 0.6.

  The density D of the light deflection elements F (i, j) arranged in this way can be designed and measured in the same manner as in the first embodiment.

  Heretofore, the configuration of the light guide 47 has been described in the example of the first region 7A. Since the configuration of the second region 7B arranged symmetrically with this is the same except for the difference in the arrangement position, detailed description is omitted.

According to the light guide 47 of the present embodiment, the adjacent intervals in the Y direction of the unit rows in the unit group and the arrangement of the unit rows in the Y direction through the entire unit group are the light guides of the first embodiment. This is the same as the light deflection element 18 in the body 7, and the change in the density D of the light deflection element 48 is also the same. For this reason, the luminance distribution in the Y direction is the same as that of the light guide 7, and the light extraction efficiency is improved and substantially uniform illumination is possible.
Further, the light deflection elements 48 in the light guide 47 are regularly arranged with a pitch Qx having a constant adjacent interval in each unit row. However, the neighboring unit columns are arranged so that the light deflection elements 48 in the Y direction are not aligned because the arrangement positions in the X direction are randomly shifted.
For example, in the reference array area e (i, j), when viewed along the Y direction, a pitch Qx / 2 is opened in the X direction, for example, e (1, 1), e (3, 1), e ( 5, 1), etc., every other row of reference arrangement areas is aligned on a straight line. On the other hand, the light deflection element 48 is, for example, arranged such that F (1,1), F (3,1), F (5,1)... Are randomly shifted from these positions in the X direction. Therefore, they are not aligned on a straight line.

Thus, since the alignment of the arrangement seen along the Y direction is disturbed, even if the unit Q is regularly arranged with the pitch Qx, it is regularly arranged with the arrangement pitch P7d in the X direction. Moire with the unit lens 7d thus made can be suppressed.
This is because, on the unit row, the brightness of the brightness that causes moire is generated due to the regular arrangement, but the probability that this shading pattern continues in the Y direction is low.
Further, the illumination device 3 and the liquid crystal display device 1 of the present embodiment using the light guide 47 can emit high-luminance light and suppress luminance unevenness. Moire can be difficult to see. Thereby, the display quality and illumination quality of the liquid crystal display device 1 and the illumination device 3 can be improved.
In particular, according to the light guide 47, since it is regularly arranged in the X direction, the manufacture becomes easy.

In the description of each of the embodiments and the modifications described above, an example in which the illumination device 3 is used in the liquid crystal display device 1 has been described. However, the illumination device 3 is not applied only to the liquid crystal display device 1. For example, it can be used as a lighting device for a display device other than a liquid crystal display device such as a signboard or an electronic book.
Further, it is not essential to combine with a display device, and for example, it can be used as a single lighting device.

In the description of each of the embodiments and the modification examples described above, the diffusion sheet 28 and the light collecting sheet 20 are provided between the image display element 2 and the light guide. The configuration of is also possible.
For example, when the required diffusion performance can be obtained only by the isotropic light diffusion member 8, the diffusion sheet 28 can be deleted.
Further, the light collecting sheet 20 has been described with an example in which the prisms 24 extending in one direction are arranged on the base material 23. For example, other condensing sheets 20 shown in FIGS. The configuration of is also possible.
FIGS. 15A and 15B are partial perspective views showing modifications of the condensing sheet that can be used in the illumination devices of the first and second embodiments of the present invention.

A condensing sheet 20A (transparent optical sheet) shown in FIG. 15A includes a triangular prism 24a extending in one direction on a base material 23 and a triangular prism 24b extending so as to intersect with the triangular prism 24a. Prepare.
A condensing sheet 20B (transparent optical sheet) shown in FIG. 15B is provided with a trapezoidal prism 24c having a trapezoidal cross section extending in one direction on a base material 23, and on the top of the trapezoidal prism 24c, Many small prisms 24d having a triangular cross section are formed adjacent to each other in a direction orthogonal to the extending direction of the trapezoidal prism 24c.

In the description of each of the embodiments and the modification examples described above, the light deflection elements are described as examples in which the light deflection elements are irregularly arranged by randomly shifting in the X direction from the reference arrangement region having a regular arrangement in the X direction and the Y direction. . However, as described in the second embodiment, even when moire occurs on a unit row, the continuity with the moire by neighboring unit rows is reduced, so that the visibility of moire is also lowered.
Therefore, even if the arrangement is regular for each unit row, moire can be suppressed if the arrangement of neighboring unit rows in the direction orthogonal to the unit row is different.
In the above description, all the arrangements in the Y direction are described as being different with a high probability. However, depending on the size of the repetitive pitch of the member that causes moire, at least if it differs from the two adjacent rows on both sides In some cases, moire can be reduced satisfactorily.

In the description of each of the above embodiments and modifications, it has been described that the light deflection elements of each unit row are aligned in the X direction. This is because the optical deflection element is unlikely to generate moire because the adjacent interval changes in the Y direction.
When moire is conspicuous due to the influence of the adjacent interval in the Y direction, the moire reduction effect may be improved by shifting the light deflection element regularly or irregularly in the Y direction. For this reason, in the above configuration, a configuration in which the light deflection element is shifted from the reference array area is possible.

  In the description of each of the embodiments and the modification examples described above, the light deflection elements are arranged so as to be shifted from the reference arrangement area so as to obtain a constant dispersion in all the unit groups. In the case where it differs depending on the place, the way of shifting the light deflection element may be changed between the position in the unit group or between the unit groups. Specifically, the coefficients α and β in the above equations (12) and (23) can be set not as constants but as variables whose values change depending on the position.

  In the description of each of the embodiments and the modification examples described above, the light deflection element formed on the light deflection surface 7a has been described as an example in which three unit groups are provided between the light incident surface 7L and the center surface S7. When dy is short, the unit group can have one configuration.

In the description of each of the above-described embodiments and modifications, since the light guide has an example of a pair of light incident surfaces 7L facing each other, the direction in which the light incident surfaces 7L are opposed is the first direction. Explained in the example.
However, if the first direction in the light guide is a direction that intersects the light incident surface 7L, an appropriate direction can be adopted as necessary to guide light. That is, the first direction can be a direction that intersects the light incident surface 7L other than 90 °.

  In the description of each of the embodiments and the modification examples described above, an example in which a suitable luminance distribution is formed only by the arrangement of the light deflection elements has been described. It is also possible to adjust or change the size and shape of the light deflection element. In this case, it is possible to correct the luminance distribution more finely.

  All the constituent elements described above can be implemented by appropriately changing or deleting combinations within the scope of the technical idea of the present invention.

Next, examples of the above embodiments will be described together with comparative examples.
[Examples 1 to 4]
Examples 1-4 are the illuminating device and the liquid crystal display device which were created using the light guide which has the same structure as 7 A of 1st area | regions of the light guide 7 of the said 1st Embodiment.
Therefore, strictly speaking, this light guide is not the light guide 7 itself described above, but in the following, when there is no possibility of misunderstanding, the corresponding member code, parameter name, etc. The symbols and names used in the description of the first embodiment are used.

  Table 1 summarizes the conditions and evaluation results of each example and each comparative example.

The light guides of the respective examples were all 13-inch cuboids having a flat plate portion of 170 mm × 300 mm in plan view, and the thickness h7c of the flat plate portion was 0.55 mm.
The light source 6 employs an LED, and is disposed at every 5 mm facing the light incident surface 7L which is a side surface on one side constituting the long side of the flat plate portion.

The light deflection element 18 has an elliptical shape with a major axis in a plan view of wx = 100 (μm), a minor axis of wy = 70 (μm), and a depth of h18 = 10 (μm).
The light deflection element 18 was divided into three regions a, b, and c and arranged in a unit group for each of the light deflection surfaces 7a. The density of the light deflection elements 18 was arranged to increase from 0.035 to 0.041 as the distance from the light incident surface 7L in the Y direction increased.
The average pitch in the X direction of the light deflection elements 18 was Pxa = 0.5 (mm), Pxb = 0.400 (mm), and Pxc = 0.330 (mm).
The arrangement position of each light deflection element 18 was determined based on the above formulas (12) to (16).
For this reason, the adjacent interval Δy _{j in} the Y direction of the light deflection element 18 is 0.35 mm for Δy ₁ a closest to the light incident surface 7L, and 0.15 mm for Δy _n−1 c farthest from the light incident surface 7L. did.

The difference between the light guides of the first to fourth embodiments is the difference in the arrangement of the light deflection elements 18, and the arrangement of the light deflection elements 18 is different from each other in two or more rows adjacent in the X direction. In this case, a light guide having a CV defined by the above equation (8) of 1/10 and the coefficient α in the above equation (12) having a different magnitude as described below is provided.
In Example 1, α = 0.10.
In Example 2, α = 0.20.
In Example 3, α = 0.40.
In Example 4, α = 0.50.

  The unit lens 7d of the light guide has a cross-sectional shape formed of a part of a circular arc shape with a radius of 0.3 mm, extends in the Y direction, and has a pitch P7d in the X direction with a unit lens having a height h7d of 0.030 mm. And arranged. The pitch P7d was 100 μm.

  Such a light guide transfers the pattern of the light deflection element 18 formed on the roll mold and the pattern of the unit lens 7d to the acrylic resin surface by extrusion molding of acrylic resin (PMMA, refractive index 1.49). As a result, it was produced integrally.

The isotropic light diffusing member 8 uses a microlens sheet in which a number of hemispherical microlenses are arranged on the surface of a transparent substrate, and has a scattering angle α of 15 ° when collimated light is incident on the microlens sheet. It was used.
As the diffusion sheet 28, a polarization separation sheet (DBEF (registered trademark) (manufactured by 3M)) was used.

  The image display element 2 is arranged on the visual direction F side of the illumination device 3 having such a configuration, and the liquid crystal display device 1 is manufactured. The pixel pitch of the image display element 2 was 0.15 mm (X direction) × 0.12 mm (Y direction).

[Comparative Examples 1-5]
Comparative Example 1 is an example in which the light deflection elements 18 are regularly arranged, that is, a light guide in which the light deflection elements 18 are arranged with the coefficient α in the above equation (12) set to 0 is provided. In this case, the CV in equation (8) is zero.
Comparative Example 2 is an example in which a light guide in which the light deflection elements 18 are arranged with the coefficient α in Equation (12) set to 1 is provided. In this case, the CV is not obtained because the variation in the adjacent pitch increases and the number of the light deflection elements 18 adjacent to each other in the X direction increases.
In Comparative Example 3, the light deflection elements 18 are formed in unit rows in which the CV defined in the above formula (8) is 1/10, and this unit row is arranged in every other row in the Y direction, so that the Y direction In this example, a light guide body in which the arrangement of the light deflection elements 18 is matched every other row is provided. Since the adjacent unit columns are shifted in the X direction by ½ of the average pitch, the arrangement of the adjacent unit columns is different from each other.
Comparative Example 4 is an example in which a light guide in which the light deflection elements 18 are arranged is provided with the CV defined in the above formula (8) being 1/5 and the coefficient α in the above formula (12) being 0.6. .
In Comparative Example 5, the light deflection elements 18 are arranged with the CV defined in the above equation (8) being 1/10, the coefficient α in the above equation (12) being 0.6, and the exit surface of the light guide 7 This is an example in which a light guide having a flat surface is formed on 7b without forming the unit lens 7d.

[Examples 5 to 7]
Examples 5 to 7 are illumination devices and liquid crystal display devices created by using a light guide having the same configuration as the first region 7A of the light guide 47 of the second embodiment. Configurations other than the light guide are the same as those in the first to third embodiments. Further, since the light guide is also common to the first to third embodiments except for the arrangement pattern of the light deflection elements 48, the following description will focus on the differences in the arrangement pattern. Moreover, unless there is a possibility of misunderstanding, the code | symbol and name used for description of the said 2nd Embodiment are used similarly to the above.

The shape of the optical deflection element 48 was the same as that of the optical deflection element 18 in the first to fourth embodiments.
The light deflection element 48 is arranged so that the light deflection surface 7a is divided into three regions a, b, and c, and constitutes a unit group, similarly to the light deflection element 18 of the first to fourth embodiments. The density of the light deflection element 48 is the same as that of the light deflection element 18 of the first to fourth embodiments in both the Y direction and the X direction. The pitch Qx in the X direction of the light deflection element 48 is Qxa = 0.5 (mm), Qxb = 0.400 (mm) and Qxc = 0.330 (mm).
The arrangement position of each light deflection element 48 was determined based on the above formulas (19) to (23).
For this reason, the adjacent interval Δy _{j in} the Y direction of the light deflection element 48 is the same as that of the light deflection element 18 in the first to fourth embodiments.

The difference between the light guides in Examples 5 to 7 is the difference in the arrangement position of the light deflection element 48. Specifically, the CV defined in the above equation (8) is 1/8, and the above equation (23). This is an example in which light guides having different coefficients β are provided as follows.
In Example 5, β = 0.30.
In Example 6, β = 0.40.
In Example 7, β = 0.60.
In Example 8, β = 0.70.

[Comparative Examples 6 and 7]
In Comparative Examples 6 and 7, in the illumination device 3 and the liquid crystal display device 1 in Examples 5 to 8 described above, a light guide having a different arrangement of the light deflection elements 48 was provided instead of the light guide in each Example. .
Comparative Example 6 is an example in which a light guide is provided when the light deflection elements 48 are regularly arranged, that is, when the coefficient β in the above equation (23) is 0.
Comparative Example 7 is an example in which the light deflection element 48 is provided with a light guide when the coefficient β in the above equation (23) is 1.

[Evaluation method]
As the evaluation, the light deflection element when the illumination device 3 is viewed from the visual direction F, whether or not the dark portion Sh is visually recognized, the measurement of the luminance reduction rate in the vicinity of the light incident surface 7L, and the liquid crystal display device 1 Evaluation of the visibility of moire when viewed from the visual direction F was performed as follows.

The evaluation of the visibility of the light deflecting element is performed by viewing the image of the light deflecting element 18 when the illuminating device 3 is viewed with the viewpoint at a position 50 cm away from the outermost surface of the illuminating device 3 in the visual direction F side. It was performed by visually evaluating whether or not.
In Table 1, this evaluation result was described as "(circle)" (Good) and "*" (No good). “◯” represents that the image was not visually recognized, and “X” represents that the image was visually recognized.

The luminance reduction rate is measured by installing a spectral radiance meter SR3 (trade name; manufactured by Topcon Co., Ltd.) at a position 50 cm away from the outermost surface of the lighting device 3 in the visual direction F side. Was measured.
FIG. 16 is a schematic plan view showing the measurement position of the luminance reduction rate.
In this measurement, as shown in FIG. 16, the luminance LA of the area SA 20 mm away from the light incident surface 7L of the light guide W of the lighting device 3 and the luminance LB of the central area SB of the lighting device 3 are measured. did. The luminance reduction rate was calculated by the ratio LA / LB between the two.
Here, a dotted line that intersects the region SB shown in FIG. 16 as a center is a virtual straight line that is orthogonal to the long side and the short side of the light guide W.
In Table 1, this evaluation result was described as "(circle)" (Good) and "*" (No good). “O” represents that LA / LB was 0.7 or more, and “X” represents that LA / LB was less than 0.7.

The evaluation of the visibility of the dark portion Sh is based on whether or not the dark portion Sh is visually recognized when viewing the lighting device 3 with the viewpoint at a position 100 cm away from the outermost surface of the lighting device 3 toward the visual direction F side. Visually evaluated.
The evaluation results are shown in Table 1 as “◯” (good), “Δ” (fair), and “×” (no good). “◯” represents that the dark part Sh was not visually recognized, “Δ” represents that the dark part Sh is visually recognized as being thin, and “x” represents that the dark part Sh is not acceptable. Indicates that it was visually recognized.

In evaluating the visibility of moire interference fringes, first, a reference light guide for moire evaluation was produced. In the light guide for reference, the light deflection element is arranged in the reference array area. That is, in the above formulas (9) and (20), they are arranged at positions where α = 0 and β = 0.
In the reference light guide, the arrangement pitch Lx in the X direction of the light deflection elements takes a constant value for each unit group and is equal to the above Px and Qx.
Further, the adjacent spacing Δy _{j in} the Y direction of the light deflection elements of the reference light guide is arranged so as to change from 0.50 mm to 0.45 mm as the distance from the light incident surface 7L increases.
Such a reference light guide was incorporated in the liquid crystal display device 1 in place of the light guide W, and moiré was observed as a reference for visual determination.
The observation was performed by looking at the liquid crystal display device 1 with a viewpoint at a position 20 cm away from the outermost surface of the liquid crystal display device 1 toward the visual direction F side.
This moire was compared with the moire when the light guide W of the example and the comparative example was incorporated in the liquid crystal display device 1 in the liquid crystal display device 1.
In Table 1, the evaluation results are shown as “◯” (good) and “×” (no good). “◯” indicates that the moire is less conspicuous than the reference moire, and “x” indicates that the moire is not different from the reference moire or worsened.

As shown in Table 1 above, the evaluation results of the visibility of the light deflection elements of the illumination device 3 incorporating the light guides of Examples 1 to 8, the evaluation result of the luminance reduction rate, and the evaluation results of the visibility of the dark portion Sh are as follows. Both were good. Moreover, the moiré of the liquid crystal display device 1 incorporating these light guides was all improved compared to the moiré observed when the reference light guide was incorporated.
On the other hand, Comparative Examples 1 to 7 were results in which any of the evaluation results of moire, the visibility of the light deflection element, and the visibility of the dark portion S was defective (x).
In Comparative Example 1, since the light deflecting elements 18 are regularly arranged, moire is visually recognized and is defective.
In Comparative Example 2, although the coefficient α is 1 and the regularity of the light deflection elements 18 is sufficiently disturbed, a region where adjacent light deflection elements contact each other appears and a region where the light deflection elements 18 do not contact each other In comparison, the light deflection element is visually recognized and defective.
In Comparative Example 3, since the light deflecting elements 18 are regularly arranged in every other row in the X direction, moire is visually recognized and is defective.
Since the C / V in the light deflection element 18 is as large as 1/5, the comparative example 4 is defective because the arrangement of the light deflection element 18 is biased and visually recognized.
In Comparative Example 5, since the unit lens 7d is not formed on the exit surface 7b of the light guide 7, the dark portion S is visually recognized and is defective.
In Comparative Example 6, since the light deflecting elements 18 are regularly arranged, the moire is visually recognized and is defective.
In Comparative Example 7, the coefficient β is 1, and the regularity of the light deflection elements 18 is sufficiently disturbed, but a region where adjacent light deflection elements are in contact with each other appears, and a region where the light deflection elements 18 are not in contact with each other In comparison, the light deflection element is visually recognized and defective.

1 Liquid crystal display device (display device)
2 Image display element 3 Illumination device 5 Reflector (reflective member)
6 Light source 7, 37, 47 Light guide 7a Light deflection surface (first surface)
7b Injection surface (second surface)
7d Unit lens 7B Reference light guide 7L Light incident surface 8 Isotropic light diffusing member (transmissive optical sheet)
9 Liquid crystal layer 10, 11 Polarizing plate 18, 38, 48 Light deflection element 18a Reference point 20, 20A, 20B Condensing sheet (transmissive optical sheet)
23 Base material 24 Prism 24a Trapezoidal prism 24b Small prism 28 Diffusion sheet (transmissive optical sheet)
D Density F Visual direction Px, Pxj, Pxa, Pxb, Pxc, Pxd Average pitch Qx, Qxa, Qxb, Qxc Pitch S7 Center plane

Claims (12)

Light that is made of a translucent material, has a light incident surface, and a first surface and a second surface that are disposed to face each other with a positional relationship sandwiching the light incident surface, and is incident from the light incident surface A light guide that guides light between the first surface and the second surface and emits part of the light from the second surface,
On the first surface,
A plurality of light deflecting elements for deflecting the light toward the second surface;
On the second surface,
A plurality of unit lenses extending along a first direction intersecting the light incident surface are arranged along a second direction orthogonal to the first direction,
The light deflection element is
A unit row in which the light deflection elements are arranged at a constant average pitch along the second direction, and a plurality of unit rows in a range of a constant distance from the light incident surface are in the first direction. And one or more unit groups arranged so that an adjacent interval decreases as the distance from the light incident surface increases.
And the arrangement density of the light deflecting elements gradually increases in the direction away from the light incident surface along the first direction throughout the unit group and all of the unit groups in the fixed distance range,
In addition, the unit columns in the unit group are provided so that the arrangement of the light deflection elements in the second direction is different from the two or more columns that are adjacent in the first direction. The light guide. The light deflection element in the unit row is:
2. The light guide according to claim 1, wherein an adjacent interval in the second direction changes along the second direction. 3. The light guide according to claim 2, wherein the adjacent interval in the second direction has a coefficient of variation CV in the unit row satisfying the following expression (1).
0 <CV ≦ 1/6 (1) 4. The light guide according to claim 2, wherein an adjacent interval in the second direction changes irregularly along the second direction. 5. The light deflection element in the unit row is:
Arranged at a constant pitch along the second direction,
The unit string in the unit group is:
2. The light guide according to claim 1, wherein an arrangement position in the second direction is different from two or more other unit columns neighboring in the first direction. In the unit sequence in the unit group,
When the coordinate value for each unit column representing the arrangement position in the second direction is X _j (j = 1,..., N) and the constant pitch is Qx, the following equations (2), (3), The light guide according to claim 5, wherein (4) is satisfied.

In the unit sequence in the unit group,
The light guide according to claim 5 or 6, wherein the arrangement position in the second direction is irregularly changed along the first direction. The unit lens is
The light guide according to any one of claims 1 to 7, wherein the lens cross section has an arc shape or an elliptical arc shape at least at the top. The light guide according to any one of claims 1 to 8,
A light source arranged to face the light incident surface;
With
An illumination device, wherein light from the light source is incident on the light incident surface and emitted from the second surface of the light guide to form illumination light. The lighting device according to claim 9, further comprising a reflecting member disposed at a position facing the first surface of the light guide. 11. The lighting device according to claim 9, further comprising one or more transmissive optical sheets disposed at a position facing the second surface of the light guide. The lighting device according to any one of claims 9 to 11,
An image display element for displaying an image by irradiating the illumination light from the illumination device;
A display device comprising:

Images