JP2009170205A - Light guide plate, light guide plate link body, backlight unit, and display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light guide plate capable of achieving, responding to a point light source, a high luminance, thinning, a light weight and a large size without unevenness in luminance, to provide a light guide plate link body, to provide a backlight unit using the same, and to provide a display. <P>SOLUTION: The light guide plate 7 has a light emitting face 11 of regular polygon shape, a thick portion formed in the center and the vicinity of the light-emitting face 11, a housing portion 9 which is formed in the thick portion of the rear face opposed to the light-emitting face 11 and houses a light source 1, a thin portion which is located at the end part of the light-emitting face 11, and an inclined portion 13 which is inclined so that it becomes gradually thinner from the thick portion to the thin end portion in the rear face. A light guide plate link body 91 in which a plurality of light guide plates 7 are connected, a backlight unit 31 using the same and a display 37 are provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light guide plate that diffuses light incident from a point light source in a planar direction and emits uniform illumination light from a light exit surface, or a display element in which a display pattern is defined according to a transparent state / scattering state The present invention relates to a backlight unit and a display device that illuminate a display unit on which a light source is disposed from the back side.

  In recent years, liquid crystal display devices using TFT type display units and STN type display units have been commercialized mainly for color notebook PCs (personal computers) and liquid crystal televisions in the OA field.

  Such a liquid crystal display device employs a so-called backlight method in which a light source is disposed on the back side of the display unit (the back side of the viewing surface) and the display unit is illuminated with light from the light source.

  This backlight system includes an edge light system that illuminates the display surface by setting a light source outside the display surface (outside the display region) and making the light from the light source uniform with a light guide plate, etc. There is a direct-type backlight system in which a light source is installed on the back surface of the light source, an optical sheet such as a diffuser plate or a lens sheet is disposed on the light source, and the display surface is illuminated with uniform light from the light source.

Especially for large display devices such as large liquid crystal televisions, the display surface is large, so the edge light method tends to be darker in the vicinity of the center of the display surface than the edge of the display surface. Is often adopted.

However, in the above-described direct type, since the light source is installed in the display area of the display device, there is a problem that the observer visually recognizes the light source when the light from the light source cannot be sufficiently uniformed.
In particular, when the distance between the light source and the optical sheet is small, the light directly above the light source cannot be diffused sufficiently uniformly by the optical sheet. It is necessary to provide a sufficient distance (a sufficient light diffusion space) between the light source and the optical sheet, and as a result, the display device becomes thicker and heavier. It was the cause.

  In order to solve the above-mentioned problems, there is a light guide plate light guide method, which is made of acrylic resin or the like having excellent light transmittance, and multi-reflects light incident on the light guide plate within the light guide plate (patented). References 1 and 2).

FIG. 33 shows a schematic perspective view of a surface light source device having the light guide plate 100 disclosed in Patent Document 1, respectively.
In the surface light source device shown in FIG. 33, after the fluorescent lamp 102 is embedded in the light guide plate 100, the reflection sheet 104 is disposed on the back surface of the light guide plate 100, and the transmitted light amount correction sheet 106 and the light diffusion plate 108 are disposed on the output surface of the light guide plate 100. The prism sheet 110 is laminated.
The light guide plate 100 has a substantially rectangular shape and is formed using a resin in which fine particles that diffuse illumination light are dispersed and mixed. In addition, the upper surface of the light guide plate 100 is flat and assigned to the exit surface. Further, a groove 100a having a U-shaped cross-section for embedding the fluorescent lamp 102 is formed on the back surface (surface opposite to the emission surface) of the light guide plate 100, and the emission surface of the light guide plate 100 is directly above the fluorescent lamp 102. Avoiding this, a light amount correction surface 100b that prompts emission of illumination light is formed.
As described above, in Patent Document 1, the light guide plate 100 is formed by mixing fine particles, and the illumination light is corrected by the light amount correction surface 100b formed on a part or all of the emission surface except directly above the fluorescent lamp 102. It is described that by promoting emission, the entire thickness can be reduced and luminance unevenness can be reduced.

Further, Patent Document 2 discloses a rectangular irradiation surface so that the liquid crystal display device can be reduced in size, weight, thickness, and cost and power consumption can be reduced without reducing the irradiation amount from the planar light source device. In addition, a rectangular cross-section groove for inserting a light source hollowed in parallel with the long side at the center of the short side, and the plate thickness gradually decreases in the direction of both side surfaces of the long side across the groove. A light guide plate having a back surface formed as described above is disclosed.

The light guide plates disclosed in the above-mentioned Patent Documents 1 and 2 are intended to reduce the thickness, size, weight, power consumption, and cost of the liquid crystal display device. Alternatively, a plurality of grooves are provided, and the rod-shaped light source is accommodated in the grooves, and in particular, the thickness of the planar light source device is reduced by forming it so that the plate thickness gradually decreases from the groove portion toward the end surface. .
Japanese Patent Laid-Open No. 9-304623 JP-A-8-62426

The above-described planar light source devices of Patent Documents 1 and 2 correspond to a rod-shaped light source.
In recent years, compared to a common cold cathode tube (hereinafter referred to as CCFL) as a rod-shaped light source, the mercury essential for CCFL is not used, the luminous efficiency is superior to CCFL, and the backlight is made thinner and thinner. The demand for light-emitting diodes (hereinafter referred to as LEDs) is increasing from the standpoint of possible miniaturization.
However, since the LED is a point light source, it emits light in a planar shape in all directions, not in a linear direction like a rod-shaped light source. Therefore, in order to make the light of the LED uniform, it is necessary to diffuse the light not only in the direction orthogonal to the linear direction but also in the planar direction, so it is difficult to reduce the luminance unevenness compared to the rod-shaped light source. It is.
In the above-described light guide plates of Patent Documents 1 and 2, light is diffused only in the direction orthogonal to the longitudinal direction of the groove that houses the bar light source of the light guide plate, that is, in the direction orthogonal to the linear direction in which the bar light source emits light. Therefore, when the LED, which is a point light source, is housed in the groove of the light guide plate of Patent Documents 1 and 2, light is not diffused in the light guide plate in the longitudinal direction of the groove. Brightness unevenness occurs.
Therefore, in the above-mentioned Patent Documents 1 and 2, it is not possible to deal with an LED that is a point light source.

Further, although a method of arranging LEDs in a row to form a pseudo-bar light source is conceivable, it is necessary to arrange a plurality of LEDs, resulting in high cost.
Furthermore, there is also a method in which light from an LED is incident on a rod-shaped light guide to guide the rod-shaped light guide, and this light guide is made a pseudo rod-shaped light source. However, the light utilization efficiency is reduced due to the loss of light that occurs when light enters the rod-shaped light guide from the LED and the loss of light that occurs when light is guided through the rod-shaped light guide. There is a problem that decreases.

The present invention has been made in view of such circumstances, solves the problems of the prior art, is thin and lightweight corresponding to point light sources such as LEDs, more uniform and less uneven from the light exit surface, Another object of the present invention is to provide a light guide plate, a light guide plate assembly, a backlight unit, and a display device that can emit illumination light with higher luminance.
In addition to the first object described above, another object of the present invention is that a plurality of light guide plates can be arranged so that the light exit surfaces are substantially flat, and elimination of bright lines generated at the connection portion between the light guide plates. In addition to preventing moiré and maintaining a stable light guide plate connection structure, a light guide plate capable of supporting an image display unit such as a liquid crystal display element of a predetermined size by connecting an arbitrary number of light guide plates Another object is to provide a light guide plate assembly, a backlight unit, and a display device.

In order to solve the above problems, the present invention proposes the following means.
The light guide plate according to the present invention is formed in the light exit surface, the thick portion formed near the center of the exit surface, and the thick portion on the back surface facing the exit surface, and accommodates the light source. A light guide plate comprising: a concave portion; a thin portion located at an end portion of the emission surface; and a slant portion inclined so that the thickness gradually decreases from the thick portion toward the thin end portion on the back surface. The shape of the light exit surface is a regular polygon.
Moreover, it is preferable that the shape of the oblique portion is a flat surface or a shape including a curved surface in a part thereof.

The light guide plate coupling body of the present invention is a light guide plate coupling body in which a plurality of the light guide plates are arranged and the thin end portions of the light guide plates are coupled to each other. It is characterized by comprising regular polygons having the same shape.
Or the light-guide plate coupling body of this invention is a light-guide plate coupling body which arranged the said light-guide plate in multiple numbers, and connected the thin edge parts of the said light-guide plate, Comprising: The light emission of each said light-guide plate The surface may be composed of at least two different regular polygons.
Moreover, it is preferable that it consists of an uneven | corrugated shape which the shape of the edge part of the thin part of the said light-guide plate of each said light-guide plate coupling body fits.
Furthermore, it is preferable that the light emission surfaces of the light guide plates of each of the light guide plate connectors are connected with a step along the thickness direction of the light guide plate.
It is preferable that the light guide plate of the light guide plate connector is manufactured by injection molding or extrusion molding.

The backlight unit of the present invention includes, in a housing, the light source, a power supply path portion that supplies power to the light source, a reflecting member provided on an outer side portion of the light guide plate, and It has the said light-guide plate coupling body.
In the backlight unit, it is preferable that a luminance ratio between the vicinity of the end of the housing and the other portion of the light emission surface is 0.1 to 10 times.

The display device of the present invention has at least an optical sheet on the light exit surface of the backlight,
Further, an image display unit is disposed on the image display unit.

ADVANTAGE OF THE INVENTION According to this invention, the light guide plate corresponding to a point light source, the brightness nonuniformity which arises on the light emission surface of a light guide plate can be eliminated efficiently, and can radiate | emit higher-intensity illumination light, and a light guide plate coupling body In addition, a backlight unit and a display device can be provided.
In addition, a plurality of light guide plates can be arranged so that the light exit surfaces are substantially flat, the bright lines generated at the connection portions of the light guide plates can be eliminated, moire can be prevented, and a stable light guide plate connection structure can be maintained. Providing a light guide plate, a light guide plate assembly, a backlight unit, and a display device that can correspond to an image display unit such as a liquid crystal display element of a predetermined size by connecting any number of light guide plates. it can.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1A, a display device 37 according to an embodiment of the present invention includes an optical sheet 33 and a display unit in order from the bottom on a backlight unit 31 that irradiates light to the viewer side X. (Screen display unit) 35 is a liquid crystal display device configured by overlappingly providing a display light whose display is controlled by an image signal from the display unit 35 toward the viewer side X. An image is displayed. In the following, the upper direction in FIG. 1A is referred to as the viewer side X, and the lower direction is referred to as the back side.

In addition, the display device 37 is a liquid crystal display device including the display unit 35. However, if the display device 37 includes at least the backlight unit 31, the backlight unit 31 may be a projection screen device, a plasma display, an EL display, or the like. The type of the image display unit that displays an image using the light from the display light as display light is not limited.

The light source 1 supplies light used for image display of the display device 37, and emits light from the power supply device 17 through the electric wiring 15.

Here, examples of the light source 1 used in the present invention include the following. The light source 1 is a point light source and is preferably an LED having good luminous efficiency.
In FIG. 2A, a blue LED element 50 that emits blue light used in a mobile device such as a cellular phone is covered with a phosphor 51 that emits yellow light applied inside the LED lens 53 to make it pseudo white. The white LED 46 emits light.
This method has an advantage that pseudo white light emission can be realized simply by covering the phosphor with a single-color LED element. In addition, the light source 1 used in the present invention is not limited to the above-described one, and may be one in which one single-color LED element is covered with at least one kind of phosphor.

Next, FIG.2 (b) adds the prism shape to the lens 53 for LED of Fig.2 (a). By using the prism, the light distribution of the light emitted from the white LED 46 can be adjusted.

FIG. 2C shows a case where a plurality of white LEDs 46 are installed. By installing a plurality of white LEDs 46, the luminance is improved as compared with the case where one white LED 46 is used. Further, the size of the light guide plate 7 can be increased as compared with the case where one white LED 46 is used.
Furthermore, by efficiently installing a plurality of white LEDs 46, the efficiency is increased in the vicinity of the tops of the regular polygons of the light emitting surface 11 having the longest distance from the light source 1 compared to the case where the white LEDs 46 are installed alone. It becomes possible to guide light well.
Therefore, the relative light amount difference between the vicinity of each apex of the regular polygon of the above-described light exit surface 11 that is the region with the least amount of light and the vicinity of the center of the light exit surface 11 that is the region with the most light amount is reduced. Therefore, luminance unevenness can be reduced.

FIG. 3 shows a method of emitting pseudo white light by combining LED devices (red LED element 48, green LED element 49, and blue LED element 50) that emit light of a single color as another method of LEDs emitting pseudo white light. In this case, compared with the case of FIG. 2 as described above, the problem that the phosphor 51 deteriorates due to the heat generated from the LED elements can be avoided, and an arbitrary color can be obtained by adjusting the amount of light of each LED element. Can do.

FIG. 4 shows a combination of single color LEDs (red LED 54, green LED 55, blue LED 56) that emit light in a single color. In this case, the red LED 54, the green LED 55, and the blue LED 56 may be combined one by one as shown in FIG. 4B, or a plurality of colors with weak light output (for example, the green LED 55) may be used as shown in FIG. You may arrange and install.

The light source 1 is not limited to the above-described LED. For example, as shown in FIG. 5, the light of a monochromatic semiconductor laser (red semiconductor laser 57, green semiconductor laser 58, blue semiconductor laser 59) is mixed through a fiber 60 and emitted from a semiconductor laser lens 61. Also good. In addition, a normal fluorescent lamp 61 may be used as shown in FIG.

Next, the light from the light source 1 enters the light guide plate 7 from the incident surface of the storage portion 9 of the light guide plate 7 (a surface other than the bottom surface of the storage portion 9). That is, the storage unit 9 stores the light source 1 and refracts the light from the light source 1 to enter the light guide 7.
Therefore, the storage unit 9 of the light guide plate 7 is preferably transparent. Further, by changing the shape of the storage unit 9, the light distribution of the light emitted from the light exit surface 11 to the viewer side X can be controlled.

Here, it is assumed that the shape of the storage unit 9 can be appropriately designed in accordance with a desired light distribution characteristic, and FIG. 7 shows a specific example of the storage unit 9. FIG. 7 shows a cross-sectional shape including a normal line (hereinafter referred to as a light guide plate central axis C) lowered from the center of the light guide plate 7 to the light exit surface 11.
FIG. 7A shows a flat surface directly above the light source 1. In this case, since the light directly above the light source 1 is a flat surface, the light directly above the light from the light source 1 is emitted without being deflected, so that the brightness directly above the light source 1 can be increased. .
FIG. 7B is a view in which the tip of the storage unit 9 is sharpened and the cross-sectional shape including the central axis C of the light guide plate is changed to a V shape. In this case, since the light directly above the light source 1 is thin and sharp, the light in the directly upward direction from the light from the light source 1 is refracted and emitted, so that the light emitted from directly above decreases, resulting in the light source The luminance directly above 1 can be lowered.
FIG. 7C shows a cross-sectional shape including the central axis C of the light guide plate in a semi-spherical or semi-elliptical sphere shape. In this case, a light distribution characteristic intermediate between those shown in FIGS. 7A and 7B can be obtained.
In addition, the shape which sharpens the front-end | tip of a storage part is not the shape where the cross-sectional shape containing the light-guide plate center axis | shaft C shown in FIG.3 (b) is V-shaped, but also the shape of FIG. Such a shape may be used. FIG. 7D shows a shape composed of a curve that swells outside the light guide 7, and FIG. 7E shows a shape composed of a curve that swells inside the light guide 7. Moreover, the cross-sectional shape including the central axis C of the light guide plate as shown in FIGS. 7F to 7G may be a shape combining a plurality of straight lines or curves. In these cases, the light of the light guide plate 7 The degree of freedom in designing the light distribution on the exit surface 11 is improved.
Further, as shown in FIG. 7 (h), the cross-sectional shape including the central axis C of the light guide plate may be a shape combining a curve and a straight line. For example, it may be substantially conical, and the apex portion of the substantially conical shape may be rounded. The storage unit 9 may be formed in a shape by combining, for example, the shapes shown in FIGS. In addition, the shape of the storage part 9 shown to Fig.7 (a)-(h) is an illustration, and is not limited to these shapes.

The shape of the storage portion 9 is preferably an axisymmetric shape around the light guide plate central axis C, but may be non-axisymmetric. For example, a part in the circumferential direction of the storage unit 9 may be formed in a flat surface, and the remaining part in the circumferential direction may be formed in a curved shape that bulges outward. Thus, by making the storage part 9 into a non-axisymmetric shape, luminance unevenness can be reduced in the light guide plate 7 installed in the vicinity of the end of the backlight unit 31 described later.

From FIG. 8, it is preferable that the depth H ₀ of the storage unit 9 is determined so that a part of the light source 1 does not protrude from the bottom side of the storage unit 9, and the dimensions of the light source 1 and the mechanical strength of the light guide plate 7 are determined. It is preferable to determine the time-dependent change. Moreover, the thickness of the thick part and the thin part of the light guide plate 7 can be arbitrarily changed according to the dimension of the light source 1 and the light distribution. In particular, the depth H0 of the storage portion 9 is preferably 90% or less with respect to the thickness of the thick portion of the light guide plate 7.

The light emission direction of the light source 1 may be installed on the back side. In this case, the storage unit 9 may be formed in the vicinity of the center of the light emission surface 11 and the light source 1 may be stored with the light emission direction on the back side.
When the light emission direction of the light source 1 is set to the back side, the distance that the light of the light source 1 guides the light in the storage unit 9 and the light guide 7 as compared with the case where the light emission direction is set to the viewer side X. Therefore, the light diffusion space can be increased in a pseudo manner. Therefore, in the above-described configuration, the light emitted from the light exit surface 11 can be made more uniform.
Further, the storage unit 9 is formed near the center of the light emitting surface 11 and the light source 1 is stored with the light emitting direction on the back side, so that the storage unit 9 is installed on the back side of the light guide 7. Thus, the distance that the light from the light source 1 is guided through the light guide 7 is increased, so that the light diffusion space can be increased in a pseudo manner, and the light emitted from the light exit surface 11 is further uniformized. be able to.

Next, the light from the light source 1 enters the light guide plate 7 from the incident surface of the storage portion 9 of the light guide plate 7 (a surface other than the bottom surface of the storage portion 9). Part of the light from the light source 1 is reflected by the reflector 3 installed on the bottom surface of the storage unit 9 of the light guide plate 7 and reenters the incident surface of the storage unit 9.

That is, the reflector 3 is provided behind the light source 1 so as to close the storage portion 9 of the light guide plate 7. The reflector 3 can reflect light from the lower surface of the light source 1 and allow light to enter from the incident surface of the storage unit 9 of the light guide plate 7 (that is, the entire portion other than the bottom of the storage unit 9).

The above-described reflector 3 can be formed of, for example, the same material as the reflective sheet 5, that is, a resin material, a metal foil, or a metal plate that imparts sufficient reflectivity to the surface.

As shown in FIG. 1A, the light incident on the light guide plate 7 propagates through the light guide plate 7. The light a that has been emitted and propagated from the upper part of the storage unit 9 is emitted from the exit surface 11 to the viewer side X. At that time, a part of the light is reflected back inside the light guide plate 7 on the light exit surface 11.
Further, the light b propagated from other than the upper part of the storage unit 9 enters the oblique part 13 of the light guide plate 7, is further reflected by the oblique part 13, and enters the light emitting surface 11.

Here, the reflective sheet 5 is installed on the back surface of the oblique portion 13. The reflection sheet 5 is for reflecting the light leaking from the oblique portion 13 of the light guide plate 7 so as to enter the light guide plate 7 again, and the light use efficiency can be improved. The reflection sheet 5 is formed so as to cover the oblique portion 13 of the light guide plate 7.

  The reflection sheet 5 may be formed of any material as long as it can reflect light leaking from the oblique portion 13 of the light guide plate 7. For example, PET, PP (polypropylene), etc. may be filled with filler or air. Resin sheet with high reflectivity by forming voids by stretching after kneading, sheet with mirror surface formed by vapor deposition of aluminum on transparent or white resin sheet surface, metal foil such as aluminum or resin carrying metal foil It can be formed of a sheet or a metal thin plate having sufficient reflectivity on the surface. In addition, the reflector 3 can be formed of, for example, the same material as the reflective sheet 5, that is, a resin material, a metal foil, or a metal plate that imparts sufficient reflectivity to the surface.

From the above, the oblique portion 13 reflects the light from the light source 1 emitted from the storage portion 9 and reflects it to the light exit surface 11.
Here, the inclination angle θ of the inclined portion 13 can be appropriately designed in accordance with desired light distribution characteristics, but 10 ° <θ <80 ° is preferable. This is because when θ is 10 ° or less, light directed toward the light exit surface 11 is reduced. If it is 80 ° or more, the thickness of the light guide plate 7 becomes large, and it is difficult to reduce the thickness.

For this reason, from FIG. 8, the central portion C of the light exit surface 11 is the thickest portion where the thickness of the light guide plate 7 is the largest, and the thickness of the light guide plate 7 decreases as it goes to the end surface 38. The end part is a thin part.

Next, FIG. 9 shows a specific example of the shape of the oblique portion 13.
FIG. 9A shows an oblique portion 13 formed with a straight line. In this case, the light guide plate 7 can be easily manufactured.
FIG. 9 (b) shows the slant portion 13 that is a curve and is formed by a curve that swells inside the light guide plate 7. In this case, the light distribution direction can be appropriately designed according to the distance from the light source 1. That is, from FIG. 9B, in the region near the light source 1 from the vicinity of the inflection point Y of the oblique portion 13, most of the light incident on the oblique portion 13 is incident from the storage portion 9 like the light ray a. This light is directly incident on the oblique portion 13. Therefore, it is preferable to design the inclination angle θ of the oblique portion 13 so that the light beam a is reflected by the oblique portion 13 and directed toward the light exit surface 11 in the region near the light source 1 from the inflection point Y of the oblique portion 13. Further, in a region far from the inflection point Y of the oblique portion 13 to the light source 1, light that is reflected back from the inside of the light guide plate 7 of the light exit surface 11 is often incident like the light ray b. Therefore, it is preferable to design the inclination angle θ of the oblique portion 13 so that the light beam b is reflected by the oblique portion 13 and reenters the light exit surface 11.
FIG. 9C shows a curve formed on the outer side of the light guide plate 7.
FIG. 9D shows a shape in which a plurality of types of straight lines having different inclination angles are combined.
FIG. 9E shows a shape in which a curve that swells outside the light guide plate 7 and a curve that swells inside the light guide plate 7 are combined.
Moreover, as shown in FIG.9 (f), the shape which combined the straight line and the curve may be sufficient. For example, the oblique portion 13 may be formed in a linear shape from the storage portion 9 to the vicinity of the thin portion, and may be formed in a curved shape that is recessed inward in the vicinity of the thin portion.
Furthermore, the shapes of FIGS. 9A to 9F may be combined.
In addition, the shape of the oblique part 13 shown to Fig.9 (a)-(f) is an illustration, and is not limited to these shapes.

  The oblique portion 13 may be formed with a prism shape or a lens shape on the surface thereof. That is, by forming the prism shape and the lens shape in the oblique portion 13, the light incident on the oblique portion 13 can be more uniformly diffused, and thus the light exit surface 11 of the light guide 7 emits light. This is because the emitted light can be made more uniform.

Further, the shape of the oblique portion 13 is preferably symmetric with respect to the central axis C of the light guide plate, but may be non-axisymmetric. For example, the inclination angle θ of a part of the oblique portion 13 may be increased and the inclination angle θ of the remaining portion may be made smaller than the aforementioned angle. Alternatively, a part of the oblique portion 13 may be formed with a flat surface and the remaining portion may be formed with a curved surface. Thus, by making the oblique portion 13 a non-axisymmetric shape, luminance unevenness can be reduced in the light guide plate 7 installed in the vicinity of the end portion of the backlight unit 31 described later.

FIG. 10 shows a perspective view of the shape of the oblique portion 13.
In FIG. 10A, the oblique portion 13 is formed as a flat surface. When the oblique portion 13 is a flat surface, the oblique portion 13 can be easily formed.
In FIG. 10B, the oblique portion 13 is formed as a curved surface. When the slant portion 13 is a conical curved surface, the distance between the light source 1 and each slant portion 13 is substantially equal, so that most of the light emitted from the light source 1 has a substantially uniform optical path length. On the other hand, in FIG. 10A, since the distance between the light source and each oblique portion 13 is different, the light in FIG. 10B is more uniform in the light guide plate 7 (hereinafter referred to as mixing effect).
Similarly, FIGS. 11 (a) and 11 (b) show the case where the light exit surface 11 is a regular hexagon, the case where the oblique portion 13 is a flat surface, and the case where the oblique portion 13 is a conical curved surface. The light guide plate 7 is shown. Also in this case, the mixing effect is higher when the oblique portion 13 is a curved surface.

Further, due to the structure of the light guide 7, it is necessary to form the inclined portion 13 as a flat surface from the light exit surface 11 to the thickness H <b> 1.
In that case, a relationship satisfying 0.1 ≦ H2 / (H1 + H2) ≦ 0.9 is preferable, where H2 is a thickness at which the oblique portion 13 is a curved surface. The larger H2 / (H1 + H2) is, the greater the mixing effect is. If H2 / (H1 + H2) is less than 0.1, the light guide 7 is not easily manufactured.

  As described above, the light transmitted through the light guide plate 7 enters the light exit surface 11. The light exit surface 11 emits light toward the viewer side X.

Here, the shape of the light exit surface 11 is preferably a regular polygon. FIG. 12 shows the shape of the light exit surface 11. FIG. 12A shows the light exit surface 11 having a regular triangle. FIG. 12B shows the light exit surface 11 having a square shape. FIG. 12C shows the light exit surface 11 having a regular hexagonal shape. FIG. 12 (d) shows the light emission surface 11 having a regular octagon.
Further, in the light guide plate 7 installed near the end of the backlight unit 31 to be described later, the light exit surface 11 may not be a regular polygon.

Further, the regular polygonal shape of the light exit surface 11 of the light guide 7 has a greater mixing effect as the number of sides increases. That is, since the brightness becomes darker in proportion to the distance from the light source 1, the light source 1 and the light guide plate 7 in FIGS. 13 (b) and (A-B) than in FIGS. 13 (a) and (A-B). This is because since the difference between the maximum distance A and the minimum distance B from the end is small, more uniform light is emitted.
If the ratio of the maximum distance A between the light source 1 and the end of the light guide plate 7 and the minimum distance B satisfies 0.5 ≦ B / A <1, the mixing effect of the light guide plate 7 is sufficient.
Further, satisfying √3 / 2 ≦ B / A <1 is preferable because the mixing effect is further enhanced.

  As long as the light guide plate 7 has transparency, heat resistance, mechanical strength, and solvent resistance that can withstand manufacturing, various materials can be applied depending on the application. For example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene terephthalate-isophthalate copolymer, terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer, polyethylene terephthalate / polyethylene naphthalate Polyester resins such as co-extruded films, polyamide resins such as nylon 6, nylon 66 and nylon 610, polyolefin resins such as polyethylene, polypropylene and polymethylpentene, vinyl resins such as polyvinyl chloride, polyacrylates and polymetas Acrylic resins such as acrylate / polymethylmethacrylate, imide resins such as polyimide, polyamideimide, and polyetherimide, polyarylate, polysulfone , Engineering resins such as polyethersulfone, polyphenylene ether, polyphenylene sulfide (PPS), polyaramid, polyetherketone, polyethernitrile, polyetheretherketone, polyethersulfite, polycarbonate, polystyrene, high impact Examples include polystyrene, acrylonitrile polystyrene copolymers, styrene resins such as ABS resin, cellophane, cellulose triacetate, cellulose diacetate, and cellulose films such as nitrocellulose.

The light diffuses due to the difference in refractive index between the fine particles and the resin constituting the light guide plate 7 in the light guide plate 7, so that the uniformity of light from the light exit surface can be improved.

The light guide plate 7 uses the above-described materials, for example, a method of molding a heated raw material resin by extrusion molding or injection molding, a cast polymerization method of polymerizing monomers, oligomers, etc. in a mold and the like. Can be manufactured. For example, you may shape | mold by pressing with the type | mold using a metal and resin.

Next, FIG. 14 shows another form of the shape of the light guide plate 7.
The light guide plate block 41 shown in FIG. 14 is formed by forming the light guide plate block side surface 43 in the shape of the light guide plate 7 and forming the light guide plate block internal space portion 45 surrounded by the oblique portion 13 and the light guide plate block side surface 43. It is.
The light guide plate block side surface 43 is a flat surface formed extending from each side of the light exit surface 11 of the light guide plate block 41 to the back side from the light exit surface 11. The light guide plate block side surface 43 is preferably formed along the direction perpendicular to the light exit surface 11.
When the plurality of light guide plate blocks 41 are arranged, the light guide plate block side surface 43 can simplify positioning and stabilize the light guide plate block 41 after the arrangement.
By providing the light guide plate block internal space portion 45, an optical member such as a reflection portion described later can be installed. In addition, since the surface area of the light guide can be increased, a structure in which heat is easily released can be obtained, and warpage due to thermal expansion due to heat radiation from the light source can be suppressed.
By providing a reflection part in the light guide plate block internal space 45, light leakage from the oblique part 13 can be prevented and light utilization efficiency can be improved.
The reflective part may be formed so as to cover the oblique part 13 with the reflective sheet 5, or the light guide plate block internal space part 45 has little light absorption such as titanium oxide, alumina, and barium sulfate. Fine particles may be filled.
The oblique portion 13 may be a flat surface as shown in FIG. 14A or a curved surface as shown in FIG. Further, as shown in FIG. 15, the light exit surface 11 may be a regular hexagon.

  As long as the light guide plate block 41 described above has transparency, heat resistance, mechanical strength, solvent resistance to withstand manufacturing, and the like, various materials can be applied depending on the application. For example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene terephthalate-isophthalate copolymer, terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer, polyethylene terephthalate / polyethylene naphthalate Polyester resins such as co-extruded films, polyamide resins such as nylon 6, nylon 66 and nylon 610, polyolefin resins such as polyethylene, polypropylene and polymethylpentene, vinyl resins such as polyvinyl chloride, polyacrylates and polymetas Acrylic resins such as acrylate / polymethylmethacrylate, imide resins such as polyimide, polyamideimide, and polyetherimide, polyarylate, polysulfone , Engineering resins such as polyethersulfone, polyphenylene ether, polyphenylene sulfide (PPS), polyaramid, polyetherketone, polyethernitrile, polyetheretherketone, polyethersulfite, polycarbonate, polystyrene, high impact Examples include polystyrene, acrylonitrile polystyrene copolymers, styrene resins such as ABS resin, cellophane, cellulose triacetate, cellulose diacetate, and cellulose films such as nitrocellulose.

Such transparent resin may be mixed with fine particles for scattering light, whereby the light emission efficiency from the light exit surface 11 can be further increased.
The light guide plate block 41 can be manufactured using, for example, a method in which a heated raw material resin is molded by injection molding or hot press molding, a casting polymerization method in which a monomer, an oligomer, or the like is polymerized and molded in a mold. it can. Moreover, it can manufacture by cutting raw material resin.

FIG. 16 shows a ray diagram and an illuminance distribution on the light exit surface 11 in a cross section including the central axis C of the light guide plate.
The light of the light source 1 enters the light guide plate 7 from the incident surface of the storage portion 9 of the light guide plate 7 (that is, the entire portion other than the bottom side of the storage portion 9). The light incident on the light guide plate 7 propagates through the light guide plate 7.
A part of the propagated light is refracted at the light exit surface 11 like the light ray c and is emitted to the viewer side X.
A part of the light incident on the light exit surface 11 is reflected and returned on the inner side of the light guide plate 7 on the light exit surface 11 like a light beam e. Then, the light enters the oblique portion 13, is reflected, reenters the light exit surface 11, is refracted, and exits to the viewer side X.
A part of the propagated light is directly incident on the oblique portion 13 of the light guide plate 7 like the light ray d, reflected by the oblique portion 13 and incident on the light exit surface 11. Then, it is refracted and emitted to the viewer side X.
As a result, as shown in FIG. 16B, the brightness near the center of the light exit surface 11 becomes brighter. In FIG. 16A, the shape of the storage portion 9 of the light guide plate 7 is a shape with a sharp point, so that the light emitted directly above the light source 1 is refracted. Therefore, the luminance peak is not directly above the light source 1 on the light exit surface 11 but in the peripheral portion thereof. The above-described luminance peak region can be appropriately changed depending on the shape of the storage unit 9 and the shape of the oblique portion 13.

  Next, the light emitted from the light exit surface 11 enters the diffusion plate 21. The light incident on the diffusion plate 21 is scattered inside the diffusion plate 21 and emitted as diffused light.

  The diffusion plate 21 is, for example, PET (polyethylene terephthalate), PP (polypropylene), PC (polycarbonate), PMMA (polymethyl methacrylate), benzyl methacrylate or MS resin, PET (polyethylene terephthalate), PP (polypropylene), PC (polycarbonate). ), Acrylonitrile polystyrene copolymer, PMMA (polymethyl methacrylate), benzyl methacrylate, MS resin, other acrylic resins, or light on a flat plate member made of optically transparent resin such as COP (cycloolefin polymer). It is formed by imparting diffusibility. The method is not particularly limited. For example, the surface of the flat plate member is subjected to surface roughening by fine unevenness processing or polishing (hereinafter, the surface on which these are applied is referred to as “sand-rubbed surface”) to impart diffusibility. Or pigments such as silica, titanium oxide, and zinc oxide that scatter light on the surface, or beads such as resin, glass, zirconia, etc., together with a binder, or the above-mentioned pigments and beads that scatter light into the above resin It is formed by kneading a kind.

Moreover, the resin sheet which formed the void by kneading and extending | stretching a filler in PET, PP (polypropylene), etc., and raised the diffusivity may be sufficient.
In the present invention, as the diffusing plate 21, it is preferable to use a member having the thickness of 0.01 mm or more and 5.0 mm or less to which the above-described material is used and to which light diffusibility is imparted.
When the diffusion plate 21 requires rigidity, the diffusion plate 21 having a thickness of 1.0 mm or more and 5.0 mm or less is preferable. When the diffusion plate 21 is required to have flexibility, the diffusion plate 21 having a thickness of 0.01 mm or more and 1.0 mm or less is preferable.
Further, the surface of the diffusion plate 21 may be formed with a concavo-convex shape or a mat shape. Thereby, the uniformity of the light emitted from the diffusion plate can be further improved. In this case, the concavo-convex shape is preferably a prism shape or a lens shape having a center line average roughness Ra of 3 μm to 1,000 μm. In the case of the prism shape, the prism shape is preferably polygonal, the prism apex angle is preferably 40 ° to 170 °, and the prism pitch is preferably 20 μm to 700 μm. The prism shape may be a pyramid shape or a truncated pyramid shape. The uneven shape described above may change its shape according to the illuminance or brightness of light incident on the uneven shape. For example, in the region where the illuminance or brightness of light incident on the uneven shape is large, the prism tops described above may be used. The corner may be increased.
Furthermore, the total light transmittance of the diffusion plate in this case is preferably 40% or more and 98% or less, the haze is preferably 20% to 100%, and the water absorption is preferably 0.25% or less.

The diffused light emitted from the diffusion plate 21 described above enters the light control sheet 21. The light control sheet 23 improves the light utilization efficiency of the diffused light from the diffusion plate 21 by utilizing light refraction, transmission, reflection, polarization, and the like.

The light control sheet 23 is not particularly limited as long as desired light refraction, transmission, reflection, and polarization can be obtained. A specific example is shown in FIG.
FIG. 17A shows a polarization separation / reflection sheet. The light utilization efficiency can be increased by transmitting only light in a specific polarization state and separating and reflecting light in other polarization states.
FIG. 17B shows a prism sheet having a prism structure on a base material. The prism structure can retroreflect light in the front direction and increase the light utilization efficiency.
FIG. 17C shows a prism sheet having a curved surface at the apex. Wear physical properties can be improved by forming a curved surface at the apex of the prism.
FIG. 17D shows a sheet in which the shape of the corrugated structure is formed. Moire can be reduced because the shape is such that the boundary line is not generated along with the collection of light.
FIG. 17E shows a lenticular lens sheet. Compared with FIG. 17B, the side lobes can be reduced.
FIG. 17F shows a lens sheet having an asymmetric cross-sectional shape. For example, a cross-sectional shape in which one side is formed in a linear shape and the other is formed in a convex curved shape on the outside, and the above-described linear shape and the curved shape are rounded and connected at the lens apex portion. In this case, the light distribution can be changed asymmetrically.
FIG. 17G shows a lens sheet in which the lens height or lens pitch is random. In this case, moire can be reduced. Random height or pitch may be applied to the prism sheet.
FIG. 17H shows a double-sided lens sheet in which lenses are formed on both the back side and the viewer side. Condensing efficiency can be improved by attaching lenses to both sides.
FIG. 17 (i) shows a double-sided lens sheet that is a double-sided lens sheet and one lens is a plurality of lenses on one side. Condensing efficiency can be improved by using a plurality of lenses on one side.
FIG. 17J shows an inverted V-shaped recess formed on the top of the lenticular lens sheet. By forming the recesses, retroreflection can be performed to improve the light utilization efficiency.

In addition, at least one light control sheet 23 may be stacked. Furthermore, you may put at least 1 or more diffusion film. In this case, the light control sheet 23 or the diffusion film having the same structure may be stacked, or the light control sheet 23 or the diffusion film having a different structure may be stacked.
When the light control sheets 23 are stacked, if the pattern is on a stripe, the light distribution in both the horizontal direction and the vertical direction can be controlled with respect to the screen by making the stripe patterns orthogonal. In the case of overlapping, at least one light control sheet 23 may be fixed by installing a fixing element 89 at the end of the light control sheet 23 as shown in FIG.
In addition, the prism sheet and the lens sheet may be arranged so that the prism structure and the lens structure face the light exit surface 11 of the light guide plate 7, or vice versa. Such prism and lens shapes may be appropriately set in order to obtain a desired light distribution.

In FIG. 17, a prism sheet, a lenticular lens sheet, and the like are used, but a sheet in which optical elements similar to prisms are regularly arranged may be used instead. In addition, a sheet that regularly includes an optical element such as a concave lens, a convex lens, and a pyramid type that has a lens effect can be used instead of the prism sheet.

As the material of the light control sheet 23, various materials can be applied depending on the use as long as the material has transparency, heat resistance, mechanical strength, solvent resistance to withstand manufacturing, and the like. For example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene terephthalate-isophthalate copolymer, terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer, polyethylene terephthalate / polyethylene naphthalate Polyester resins such as coextruded films, polyamide resins such as nylon 6, nylon 66 and nylon 610, polyolefin resins such as polyethylene, polypropylene and polymethylpentene, vinyl resins such as polyvinyl chloride, polyacrylates and polymetas Acrylic resins such as acrylate and polymethyl methacrylate, imide resins such as polyimide, polyamideimide, and polyetherimide, polyarylate, and polysulfone , Engineering resins such as polyethersulfone, polyphenylene ether, polyphenylene sulfide (PPS), polyaramid, polyetherketone, polyethernitrile, polyetheretherketone, polyethersulfite, polycarbonate, polystyrene, high impact There are styrene resins such as polystyrene, acrylonitrile polystyrene copolymer, ABS resin, cellophane, cellulose triacetate, cellulose diacetate, cellulose films such as nitrocellulose, etc.

In the case of a polarized light separating / reflecting sheet, the light control sheet 23 may be manufactured by stretching a multi-layered film in which two types of layers having different refractive indexes are alternately stacked in a single axis direction.
In the case of a prism sheet, a lens sheet, etc., it is formed by an extrusion molding method, an emission molding method, or a hot press molding method well known in the art. In this case, the base material and the lens portion may be composed of one base material made of the same material, or may be made from different base materials of different materials. In addition, a step may be provided on the non-light-condensing part on the opposite side of the lens part to mold the part.
The lens portion may be molded using UV or radiation curable resin (the type is not particularly limited as long as the resin includes a material curable by UV or radiation).

As described above with reference to FIG. 16, the light emitted from the light exit surface 11 of the light guide plate 7 is often bright at the center of the light exit surface and dark and uniform at the peripheral edges. Such non-uniform light emitted from the light exit surface 11 may not have a uniform illuminance distribution even through the diffusion plate 21 or the light control sheet 23.
In this case, as shown in FIG. 1B, a uniform illuminance distribution can be obtained by installing a transmittance adjusting sheet 22 between the light guide plate 7 and the diffusion plate 21.

Here, the transmittance adjustment sheet 22 displayed in FIG. 1B is obtained by forming the transmittance adjustment pattern 20 on the support base material 18.
The arrangement distribution of the transmittance adjustment pattern is a position on the light exit surface 11 of the light guide plate 7 where the amount of emitted light is large, for example, in the vicinity of the central portion immediately above the light source 1 on the light exit surface 11 as shown in FIG. The illuminance distribution can be made uniform by increasing the density of the transmittance adjustment pattern 20 and reducing the density of the transmittance adjustment pattern 20 at a position where the amount of emitted light is small, for example, near the end of the light exit surface 11. As a result, luminance unevenness can be reduced.

Here, the transmittance adjusting sheet 22 has a configuration in which a transmittance adjusting pattern is arranged on the transparent support base 18. This transmittance adjustment pattern 20 may be provided on either the viewer side X or the back side of the support substrate 18, or may be provided on both sides depending on the application.

In FIG. 1B, the transmittance adjustment sheet 22 is installed between the light guide plate 7 and the diffusion plate 21, but the installation position is not particularly limited as long as it is between the light guide plate 7 and the display unit 35. In addition, at least one transmittance adjusting sheet 22 may be installed. For example, a plurality of transmittance adjustment sheets 22 having different in-plane density distributions of the transmittance adjustment pattern 20 may be stacked and installed. By arranging a plurality of transmittance adjusting sheets 22 in an overlapping manner, it is possible to make the light more uniform.
Further, the transmittance adjustment pattern 20 may be provided on the light exit surface 11 of the light guide plate 7, the diffusion plate 21, or the light control sheet 23. When the light guide plate 7 is provided on the light emission surface 11, the diffusion plate 21, or the light control sheet 23, the support base material 18 is not necessary, so that the optical sheet 23 can be thinned and light loss can be reduced. . When the transmittance adjustment pattern 20 is provided on the light control sheet 23, it is preferably provided on the back side of the light control sheet 23 in order not to impair the characteristics of light controlled by the light control sheet 23.

The support substrate 18 is made of PET (polyethylene terephthalate), PP (polypropylene), PC (polycarbonate) PMMA (polymethyl methacrylate), benzyl methacrylate, MS resin, other acrylic resins, COP (cycloolefin polymer), acrylonitrile polystyrene. It is formed of an optically transparent member such as a copolymer.
The transmittance adjustment pattern 20 is a dot of various sizes having a predetermined transmittance, and has a shape such as a quadrangle, a circle, or a hexagon, and a predetermined pattern, for example, the dot size according to the position, It is formed by a known printing method such as screen printing or gravure printing or a photolithography method on the entire surface of the support base 18 on the light guide plate 7 side in a pattern (halftone dot pattern) in which the number of dots is different.

The material of the transmittance adjustment pattern 20 is not particularly limited, and for example, a pigment or resin such as silica, titanium oxide, or zinc oxide that scatters light, or a bead such as glass or zirconia coated with a binder is also used. be able to.
In addition, as a material that can be used as the transmittance adjustment pattern 20, general white ink used in screen printing, offset printing, and the like can be used. Examples include inks in which titanium oxide, zinc oxide, zinc sulfate, barium sulfate, etc. are dispersed in acrylic binders, polyester binders, vinyl chloride binders, etc., and inks in which silica is mixed with titanium oxide to impart diffusibility. Can be used.
The transmittance adjustment pattern 20 may be composed of a single material or a plurality of materials.

  In addition, in the light guide plate 7, if the light can be sufficiently uniformed, it is not necessary to install the transmittance adjusting sheet 22 as shown in FIG.

Moreover, you may use the said diffuser plate 21 and the light control sheet | seat 23 integrally.
As an integration method, a bonding layer 82 using a pressure-sensitive adhesive or an adhesive is formed between the diffusion plate 21 and the light control sheet 23, and an air layer is held and integrated.
As shown in FIG. 19A, the air layer 85 may be held between the light control sheet 23 and the diffusing plate 21 via a spacer 83 to be laminated and integrated.
As shown in FIG. 19B, the air layer 85 may be held between the light control sheet 23 and the diffusing plate 21 via the light reflecting layer 87 and integrated. In that case, it is preferable that the optical elements of the prism layer and the lens of the air layer 85 and the light control sheet 23 are in a position corresponding to 1: 1.
As shown in FIG. 19C, a step may be provided on the opposite side of the lens structure, and the light reflecting layer 85 may be formed on the step to be laminated and integrated. Further, the light reflection layer 85 may be formed and integrated without being formed. In this case, since the light control sheet 23 itself has a step, the air layer 85 can be easily secured.
As shown in FIG. 19D, a lens shape may be formed between the steps in the structure of FIG. In this case, the light collection efficiency can be improved.
As shown in FIG. 19E, if there is a step on the opposite side of the lens structure, the light reflecting layer 87 may be filled without providing an air layer. In this case, since it is not necessary to ensure the air layer 85, manufacture becomes easy.
As shown in FIG. 19F, the total reflection of light at the boundary between the air layer 85 and the light control sheet 23 may be used by using a trapezoidal prism.

Here, the light reflecting layer 87 is, for example, a white layer or a metal layer. As a material for the white layer, a composite material in which a white pigment made of an inorganic substance such as titanium dioxide, barium sulfate, and magnesium oxide is dispersed in a transparent resin can be used. As the metal layer, for example, a vapor deposition layer made of a material having high reflectivity and low light absorption such as silver and aluminum can be used.
The light reflecting layer 87 may be directly formed on the light control sheet 23 by printing or vapor deposition. Alternatively, the light reflecting layer 87 may be formed by transfer. For example, a photosensitive resin film is attached to the surface of the light control sheet 23 on which the light reflecting layer 87 is formed, and the photosensitive resin film is exposed to ultraviolet rays through the light control sheet 23. Thereby, the adhesive force of the photosensitive resin film is reduced only at the focal point of the lens provided on the light control sheet 23 and the area in the vicinity thereof. Thereafter, the laminate of the light control sheet 23 and the photosensitive resin film is pressed against the light reflecting layer 87 formed on the release paper, and then the laminate is released from the release paper. In this way, the light reflecting layer 87 having the air layer 85 in the focal point of the lens and the region in the vicinity thereof is obtained.
When the printing method is used, the light reflecting layer 87 can be easily formed by printing if a step is provided in the non-light-condensing portion on the opposite surface of the lens when the lens sheet is manufactured.
Further, the air layer 85, preferably the line connecting the apex of each lens and the center of the air layer 85 corresponding thereto is positioned so as to be substantially orthogonal to the light reflecting layer 87. The shape of the air layer 85 viewed from the normal direction of the light reflecting layer 87 may be any shape such as a circular shape, a square shape, an elliptical shape, or a stripe shape.
FIGS. 19A to 19F are examples, and the configuration is not limited. Any configuration may be used as long as the diffusion plate 23 and the light control sheet 21 can be integrated.

In the optical sheet 33 described above, at least one diffusion film may be appropriately placed on the light control sheet 23 or between the diffusion plate 21 and the light control sheet 23. This makes it possible to reduce moire and improve light uniformity.
Further, the light control sheet 23 may not be provided, and an optical sheet 33 having at least one diffusion film in place of the light control sheet 23 may be used.

The light emitted from the light control sheet 23 is collected and enters the display unit 35. The display unit 35 drives the liquid crystal layer 25 sandwiched between the polarizing plates 27 by a liquid crystal drive device 29, adjusts transmission / non-transmission of incident light, and performs image display.

In the liquid crystal television, the screen size is increased, and it is conceivable to use a plurality of light guide plates 7 connected together instead of one. Here, as a method of connecting and combining the plurality of light guide plates 7, there is the following.

FIG. 20 shows a connection made only with congruent regular polygons. In addition, what connected the light-guide plate 7 is called the light-guide plate coupling body 91 below.
When connected by only congruent regular polygons, the light emitting surface 11 of each light guide plate 7 has the same area, so that a difference in luminance between the light guide plates 7 is unlikely to occur.
As such a thing, the light-emitting surface 11 of the light-guide plate 7 has a square (FIG. 20 (a)), a regular hexagon (FIG. 20 (b)), and a regular triangle (FIG. 20 (c)), for example. .
Here, in the case of an equilateral triangle or a square, since the coupling portions 40 are connected to each other in a straight line, it is possible to simplify alignment and reduce luminance unevenness when installed near the end of the backlight unit 31 described later. It is. Further, the regular hexagon has a honeycomb structure, and the strength in a state in which the light guide plate 7 is connected is stronger than in the case of the regular triangle or square described above. That is, in the case of a square, when stress is generated in the light guide plate 7 in the direction along the light exit surface 11, the light guide plate is displaced in that direction. On the other hand, the regular hexagon has a larger number of sides than the square, and is not structurally misaligned even if stress is generated in the direction along the light exit surface 11, so that the structure is strong.

Next, there is a method of connecting the light guide plates 7 in shapes having different areas of the light exit surface 11.
FIG. 21A shows a connection of squares having different sizes. FIG. 21B shows a concatenation of equilateral triangles having different sizes.
FIG. 22 shows a combination of a square and a regular octagon as an example of connecting two types of regular polygons. In this way, two or more kinds of regular polygons may be connected. In this case, since the shape of the connecting portion 40 between the light guide plates 7 can be a more complicated zigzag shape instead of a linear shape, moire and bright lines described later can be reduced.

Here, when regular polygons having different sizes are connected, luminance unevenness is likely to occur when the output of the light source 1 is the same.
Accordingly, when the light guide plates 7 having different areas of the light exit surface 11 are connected, if the following conditions are satisfied, there is a sufficient mixing effect.
When the area of the light exit surface of one light guide plate is S1 and the area of the light exit surface of another light guide plate is S2, it is necessary to satisfy 0.5 ≦ S2 / S1 ≦ 2 when the light output of the light source 1 is the same. There is.
That is, when S2 / S1 is less than 0.5 or greater than 2, the difference in brightness between the light guides 7 is visually recognized on the viewer side X.
When the light output of the light source 1 is different, it is necessary to satisfy 0.05 ≦ S2 / S1 ≦ 20. This is because if S2 / S1 is less than 0.1 or greater than 20, the difference in brightness between the light guides 7 cannot be compensated for by the light output of the light source 1, and is viewed on the viewer side.

Next, FIG. 23B shows a shape in which the light guide plate connecting side surface 39 is provided on the light guide plate 7.
The light guide plate connecting side surface 39 is a flat surface formed by extending from each side of the light emitting surface 11 of the light guide 7 to the back side along the normal direction of the light emitting surface 11 and connected to the oblique portion 13. is there.
When the light guide plate connecting side surface 39 is provided, the light guide plates 7 can be stably connected to each other. Since the area of the light guide plate connecting side surface 39 can be effectively used for bonding the light guide plates 7, environmental characteristics such as warpage of the light guide plate 7 and peeling of the bonded portion are improved as compared with FIG.

In the light guide plates 7 connected as described above, the light guide plate 7 is thermally expanded due to the heat radiation of the light source 1, and warpage occurs. FIG. 23 shows a case where warpage occurs in the light guide plate 7.
FIG. 24A shows a state before thermal expansion, and the connecting side surfaces 39 are connected without a gap.
Next, when receiving heat radiation from the light source 1, the storage portion 9 is thermally expanded and warped convexly toward the light source 1 as shown in FIG. When the light emitting surface 11 is formed with a concavo-convex shape, the light emitting surface 11 may be warped convexly as shown in FIG.
When such warpage occurs, the direction of warpage of each light guide plate 7 differs depending on the heat radiation of the light source 1, the material of the light guide plate 7, etc., and individual differences in the warpage between the thin end portions of the plurality of light guide plates 7 that are in contact with each other As a result, the light guide plate 7 cannot be disposed without a gap, and a deviation occurs. Due to individual differences in warpage of individual light guide plates 7, different gaps 65 are generated between the adjacent light guide plates 7 as shown in FIG. 24 (d), and are generated by the gaps 65 through the display unit 35 from the viewer side. The bright part or the dark part depending on the situation is confirmed, which causes a problem in use of the display device 37.

Therefore, as shown in FIG. 25, an uneven shape may be formed on each side of the light exit surface 11 of the light guide plate 7. By forming such a concavo-convex shape, alignment in the direction along the light emission surface 11 between the light guide plates 7 during connection is facilitated, and along the light emission surface 11 between the light guide plates 7 due to thermal expansion. Can be prevented from being misaligned.
Here, the uneven shape is a linear sawtooth shape (FIG. 25A), a corrugated shape (FIG. 25B), a rectangular shape (FIG. 25C), or a semicircular shape (FIG. 25D). Or a triangular shape (FIG. 25E). Moreover, you may use an uneven | corrugated shape combining these with respect to the one light-guide plate coupling body 91. FIG. 25A to 25E are examples, and the shape is not particularly limited.

In addition, as shown in FIG. 26, by forming a concavo-convex shape on the light guide plate connecting side surface 39 and forming an inverted concavo-convex shape on the adjacent light guide plate connecting side surface 39, positional deviation in the thickness direction of the light guide plate 7 can be prevented. Can do.
The uneven shape in this case may be a linear sawtooth shape (FIG. 26A), a rectangular shape (FIG. 26B), or a wave shape (not shown). FIGS. 26A to 26B are examples, and the shape is not particularly limited.

Further, even if the light guide plate 7 is warped due to thermal expansion, a step is provided between the light guides 7 in advance as shown in FIG. 27 in order to prevent problems in using the display device 37. There is a way to connect.
By providing a step and connecting, even if warpage occurs, the light guide plate 7 is shifted upward or downward (difference in the step is increased), and no gap is generated between the light guides 7.
As shown in FIG. 27A, the light guide plate 7 that is easily affected by warpage may be connected with a step provided on the lower side. When receiving heat radiation from the light source 1, the light guide plate that is susceptible to warpage moves downward, and when there is no heat dissipation and the light guide plate 7 cools, it moves upward.
Further, as shown in FIG. 27B, the light guide plate 7 that is easily affected by warpage may be connected with a step provided on the upper side. When receiving heat radiation from the light source 1, the light guide plate that is susceptible to warpage moves upward, and when there is no heat dissipation and the light guide plate 7 cools down, it moves downward.

As shown in FIG. 28, the fixing element 67 may be installed on the light guide plate block side surface 43 of the light guide plate block 41 or on the lower surface of the light guide plate block.
Warpage can be prevented by fixing the light guide plate block 41 in the backlight unit 31 by the fixing element 67 or by fixing it to the adjacent light guide plate block 41. As the fixing element 67, for example, an adhesive, an adhesive, or a magnet is preferable.

When the above-described light guide plate 7 is connected, moire can be reduced.
That is, when linear patterns are overlaid, a periodic light / dark pattern, that is, moire occurs, which causes a problem in use of the display device.
Conventionally, the occurrence of moire has been reduced by overlapping linear patterns that are not parallel but intersected at a certain angle (hereinafter referred to as bias).
Here, in the light guide plate 7 having a regular hexagonal light exit surface 11, the connecting portion 40 between the light guide plates 7 has a zigzag shape, and therefore always intersects the linear pattern at an angle. Can be reduced.
Further, as shown in FIG. 25, when each side of the emission surface 11 is formed in a concavo-convex shape, the effect of reducing moire is further increased.

When the light guide plates 7 are connected to each other, bright lines are likely to occur. Here, the bright line is brighter than the region V as shown in FIG. 29A when light leaks from the side surface 39 of the light guide plates 7 to each other. It will be visually recognized. In FIG. 29A, since the connecting portion 40 is a straight line, it becomes a striped bright line 79 (a) with a small bright line width U and is visible from the viewer side X.
On the other hand, in FIG.29 (b), since the connection part 40 is not a straight line but zigzag shape, the bright line width U becomes large compared with FIG.28 (b). Therefore, the bright line 79 (b) is relatively dark compared to FIG. 29 (a). As a result, the brightness difference with the bright line peripheral region V becomes small, and the bright line becomes inconspicuous. Further, as shown in FIG. 25, when each side of the emission surface 11 is formed in a concavo-convex shape, the effect of reducing the bright line is further increased.
In addition, when two or more types of regular polygons are coupled as shown in FIG. 20, the shape of the coupling part between the light guides is more complicated than the case of coupling only with a congruent regular hexagon. Therefore, the moire reduction and bright line reduction effects are further increased.

A plurality of the light guide plates 7 as described above are connected to each other, and are housed in the housing 19 and configured as the backlight unit 31.

Here, when the light emission surfaces 11 of the light guide plate 7 are connected as regular triangles and squares, the end portion of the light guide plate connecting body 91 is a straight line, so there is no particular problem, but other regular polygons are connected. In this case, since the end portion does not become a straight line, it is necessary to incorporate the backlight unit 31 or the housing of the liquid crystal display device 37 so that luminance unevenness does not occur at the end portion of the backlight unit 31.

FIG. 30 shows an installation method of the light guide plate 7 in the vicinity of the end of the backlight unit 31.
In the case where the connecting portion 40 is not linear, as in the case where the light emitting surface 11 has a regular hexagonal light guide plate 7, the luminance unevenness is not visually recognized from the observer side as shown in FIG.

That is, in FIG. 30A, the end portion of the light guide plate connector 91 is covered with the housing 19. Thereby, the visual recognition of luminance unevenness can be prevented.

However, when the area of the light exit surface 11 of the light guide plate 7 is large, the outer frame of the backlight unit 31 becomes large if the casing 19 covers the end portion of the light guide plate connector 91. This is because if the outer frame is large, the display surface of the display device becomes small as a result.
Therefore, when the shape of the light emission surface 11 of the light guide plate 7 installed at the end is not a regular polygon but a plurality of light guide plates 7 are connected, the backlight of the light guide plate 7 as shown in FIG. The end of the unit 31 may have a linear shape.

As shown in FIG. 30 (c), a reflective agent in which fine particles such as titanium oxide, alumina, and barium sulfate are dispersed in an adhesive between the casing 19 and the light guide plate 7 installed at the end of the light guide plate connector 91. 69 may be filled to make the luminance uniform.
Moreover, you may arrange | position the light-guide plate 7 in which the light source 1 is not installed between the housing | casing 19 and the light-guide plate 7 installed in the light-guide plate coupling body 91 edge part.
Furthermore, you may arrange | position a diffuse reflection material (The thing which disperse | distributed the bubble of air to PET film, or vapor-deposited silver, aluminum, etc. with high reflectance) on the housing | casing 19 side.

Further, as shown in FIG. 30 (d), the method described above is used between the method of using the light guide plate 7 whose light exit surface 11 is not a regular polygon and the light guide plate 7 installed at the end of the light guide plate connector 91. A method of filling the reflective agent 69 may be combined.
This method is effective when cutting a light guide plate 7 which will be described later by integral molding in accordance with the size of the backlight unit 31.

Further, the light guide plate 7 used in the vicinity of the end of the backlight unit 31 has the light source 1 installed from the vicinity of the center of the light exit surface 11 as shown in FIG. You may shift. The shift direction and the shift amount may be appropriately determined depending on the shape of the light exit surface 11 and the distance from the end of the backlight unit 31.
In addition, the light guide plate 7 used in the vicinity of the end of the backlight unit 31 is formed in a non-axisymmetric shape with respect to the central axis C of the light guide plate 7 as described above, or the light guide plate 7. The shape of the oblique portion 13 may be non-axisymmetric with respect to the central axis C of the light guide plate.
Moreover, the manufacturing method of the light-guide plate 7 in which the light emission surface 11 is not a regular polygon may manufacture the light-guide plate 7 in the shape which is not a regular polygon at the time of manufacture. Alternatively, the light guide plate 7 may be manufactured in a regular polygon and cut into a shape other than the regular polygon by cutting in a subsequent process.

The above-described light guide plate connector 91 may be formed by integrally forming a plurality of light guide plates 7.
In the case of integral molding, there is no gap in the connecting portion between the light guide plates, so that loss of light and luminance unevenness caused by the gap can be prevented.

The light guide plate connector 91 integrally formed with the light guide plate 7 includes, for example, a method of molding a heated raw material resin by extrusion molding or injection molding, a casting polymerization method of polymerizing monomers, oligomers, etc. in a mold. Can be used.
The size of the light guide plate connector 91 may be changed for each size of the backlight unit 31.
Further, a light guide plate coupling body 91 in which a large size light guide plate 7 is integrally formed may be manufactured and cut to match the size of the backlight unit 31. In this case, it is not necessary to make a mold for forming the light guide plate for each size of the backlight unit 31, and it can be manufactured at a lower cost.

Cutting methods include laser cutting (FIG. 32A), cutting using a blade (not shown), punching (not shown), and the like.
When cutting, it is preferable that the area of the light emitting surface 11 of the light guide plate 7 at the end of the light guide plate connector 91 integrally formed with the light guide plate 7 after cutting is substantially equal. (FIG. 32 (b))
Moreover, the area of the light emission surface 11 of the light guide plate 7 at the end of the light guide plate connector 91 integrally formed with the light guide plate 7 after cutting may be different. In that case, the method of making the storage portion 9 of the light guide plate 7 non-axisymmetric with respect to the light guide plate central axis C described above, or the shape of the oblique portion 13 of the light guide plate 7 with respect to the light guide plate central axis C is not. Using a method of forming an axial symmetry, a method of shifting the installation position of the light source 1 from the central axis C of the light guide plate, and a method of filling the reflective agent 69 between the housing 19 and the light guide plate 7 installed at the end. Also good.

Example 1
A light guide plate 7 having a light emission surface 11 having a square shape and a size of 28 mm × 28 mm was manufactured by an extrusion molding method.
Here, polycarbonate was used as the material of the light guide plate 7.
The shape of the storage portion 9 of the light guide plate 7 is a substantially conical shape with a bottom surface having a diameter of 5.3 mm and a depth of 4.5 mm, and a conical vertex having a curvature radius of 0.25 mm. The thickness of the thickest portion of the light guide plate 7 is set to 5.5 mm, and the thickness of the light guide plate 7 having the smallest thickness when the end of the inclined portion 13 is flat is set to 1.5 mm. did. The oblique portion 13 is guided with a radius of curvature of 15 mm so that the angle θ formed with the light exit surface 11 in the vicinity of the storage portion 9 is 15.76 degrees, and in the vicinity of the end portion, θ becomes 0 degree as the end portion is approached. The curve swells inside the light plate 7.
As the light source 1, a blue LED 50 that emits blue light is covered with a phosphor 51 that emits yellow light applied inside the LED lens 53, and a white LED 46 that emits pseudo white light is used.
As the reflection sheet 5, a resin sheet in which voids made of air were formed on PET to increase the reflectance was used, and the reflection sheet 5 was integrated with the oblique portion 13 with an adhesive.
The reflector 3 used the same resin sheet as the reflection sheet 5 and closed the storage portion 9 of the light guide plate 7.
The above-described configuration was installed in the housing 19 to configure the backlight unit 31.
On the backlight unit 31, the transmittance adjusting sheet 22, the diffusion plate 21, and the light control sheet 23 were stacked as the optical sheet 33 in order from the back side.
The transmittance adjusting sheet 22 is manufactured by printing a white ink in which titanium oxide is dispersed as a pigment on a PET film (thickness: 75 μm) of the support substrate 18 as a transmittance adjusting pattern 20 by a screen printing method. did. A pattern similar to FIG. 18 was formed in a halftone dot shape. The size of one dot pattern of halftone dots was a square shape of 0.5 mm × 0.5 mm.
The diffusion plate 21 is manufactured by an extrusion molding method in which a filler is dispersed in a polycarbonate which is a transparent resin. The thickness of the diffusing plate 21 was 2.0 mm, the total light transmittance was 65%, and the haze was 99%.
As the light control sheet 23, a lenticular lens sheet obtained by molding a lens on a PET film (thickness: 75 μm) using a UV ray curable resin was used. The lens pitch of the lenticular lens sheet was 98 μm, and the lens shape was an aspheric lens shape.
As a result of measuring the luminance from the backlight unit 31 and the optical sheet 33 having the above-described configuration, the ratio of maximum luminance / minimum luminance was 5 times, and luminance unevenness visually recognized on the viewer side X did not occur.

(Example 2)
The light guide plate 7 in which the light emission surface 11 has a regular hexagonal shape and the length of each side of the regular hexagon is 14 mm was manufactured by an extrusion molding method.
Here, polycarbonate was used as the material of the light guide plate 7.
The shape of the storage portion 9 of the light guide plate 7 is a substantially conical shape with a bottom surface having a diameter of 5.3 mm and a depth of 4.5 mm, and a conical vertex having a curvature radius of 0.25 mm. The thickness of the thickest portion of the light guide plate 7 is set to 5.5 mm, and the thickness of the light guide plate 7 having the smallest thickness when the end of the inclined portion 13 is flat is set to 1.5 mm. did. The oblique portion 13 is guided with a radius of curvature of 15 mm so that the angle θ formed with the light exit surface 11 in the vicinity of the storage portion 9 is 15.76 degrees, and in the vicinity of the end portion, θ becomes 0 degree as the end portion is approached. The curve swells inside the light plate 7.
As the light source 1, a blue LED 50 that emits blue light is covered with a phosphor 51 that emits yellow light applied inside the LED lens 53, and a white LED 46 that emits pseudo white light is used.
As the reflection sheet 5, a resin sheet in which voids made of air were formed on PET to increase the reflectance was used, and the reflection sheet 5 was integrated with the oblique portion 13 with an adhesive.
The reflector 3 used the same resin sheet as the reflection sheet 5 and closed the storage portion 9 of the light guide plate 7.
The above-described configuration was installed in the housing 19 to configure the backlight unit 31.
On the backlight unit 31, the transmittance adjusting sheet 22, the diffusion plate 21, and the light control sheet 23 were stacked as the optical sheet 33 in order from the back side.
The transmittance adjusting sheet 22 is manufactured by printing a white ink in which titanium oxide is dispersed as a pigment on a PET film (thickness: 75 μm) of the support substrate 18 as a transmittance adjusting pattern 20 by a screen printing method. did. A pattern similar to FIG. 18 was formed in a halftone dot shape. The size of one dot pattern of halftone dots was a square shape of 0.5 mm × 0.5 mm.
The diffusion plate 21 is manufactured by an extrusion molding method in which a filler is dispersed in a polycarbonate which is a transparent resin. The thickness of the diffusing plate 21 was 2.0 mm, the total light transmittance was 65%, and the haze was 99%.
As the light control sheet 23, a lenticular lens sheet obtained by molding a lens on a PET film (thickness: 75 μm) using a UV ray curable resin was used. The lens pitch of the lenticular lens sheet was 98 μm, and the lens shape was an aspheric lens shape.
As a result of measuring the luminance from the backlight unit 31 and the optical sheet 33 having the above-described configuration, the ratio of maximum luminance / minimum luminance was doubled, and luminance unevenness visually recognized on the viewer side X did not occur. It was confirmed that the ratio of maximum luminance / minimum luminance was reduced by making the light emission surface 11 a regular hexagon as compared with Example 1 in which the light emission surface 11 was square.

(Example 3)
A light guide plate 7 having a light emission surface 11 having a square shape and a size of 28 mm × 28 mm was extruded.
Here, polycarbonate was used as the material of the light guide plate 7.
The shape of the storage portion 9 of the light guide plate 7 is a substantially conical shape with a bottom surface having a diameter of 5.3 mm and a depth of 4.5 mm, and a conical vertex having a curvature radius of 0.25 mm. The thickness of the thickest portion of the light guide plate 7 is set to 5.5 mm, and the thickness of the light guide plate 7 having the smallest thickness when the end of the inclined portion 13 is flat is set to 1.5 mm. did. The oblique portion 13 is guided with a radius of curvature of 15 mm so that the angle θ formed with the light exit surface 11 in the vicinity of the storage portion 9 is 15.76 degrees, and in the vicinity of the end portion, θ becomes 0 degree as the end portion is approached. The curve swells inside the light plate 7.
As the light source 1, a blue LED 50 that emits blue light is covered with a phosphor 51 that emits yellow light applied inside the LED lens 53, and a white LED 46 that emits pseudo white light is used.
As the reflection sheet 5, a resin sheet in which voids made of air were formed on PET to increase the reflectance was used, and the reflection sheet 5 was integrated with the oblique portion 13 with an adhesive.
The reflector 3 used the same resin sheet as the reflection sheet 5 and closed the storage portion 9 of the light guide plate 7.
The above-described configuration is aligned in the housing 19 with the sides of the light emitting surface 11 aligned, and the light guide plate coupling body 91 is configured and incorporated in the backlight unit 31. When connected, the light guides 7 were connected with a step as shown in FIG.
On the backlight unit 31 described above, as the optical sheet 33, the transmittance adjusting sheet 22, the diffusion plate 21, and the light control sheet 23 were stacked in order from the back side.
The transmittance adjusting sheet 22 is manufactured by printing a white ink in which titanium oxide is dispersed as a pigment on a PET film (thickness: 75 μm) of the support substrate 18 as a transmittance adjusting pattern 20 by a screen printing method. did. A pattern similar to FIG. 18 was formed in a halftone dot shape. The size of one dot pattern of halftone dots was a square shape of 0.5 mm × 0.5 mm.
The diffusion plate 21 is manufactured by an extrusion molding method in which a filler is dispersed in a polycarbonate which is a transparent resin. The thickness of the diffusing plate 21 was 2.0 mm, the total light transmittance was 65%, and the haze was 99%.
As the light control sheet 23, a lenticular lens sheet obtained by molding a lens on a PET film (thickness: 75 μm) using a UV ray curable resin was used. The lens pitch of the lenticular lens sheet was 98 μm, and the lens shape was an aspheric lens shape.
A display unit 35 is built on the backlight unit 31 and the optical sheet 33 described above to constitute a display device 37.
As a result of observing the display device 37 after 6 hours have passed since the light source 1 was turned on and the temperature inside the backlight unit 31 reached the maximum temperature, the light guide plate connector 91 did not warp, and the light guide plate 7 The bright line between them was not visible from the viewer side X.

Example 4
In the fourth embodiment, the transmittance adjustment sheet 22 is removed from the configuration of the third embodiment.
A light guide plate 7 having a light emission surface 11 having a square shape and a size of 28 mm × 28 mm was extruded.
Here, polycarbonate was used as the material of the light guide plate 7.
The shape of the storage portion 9 of the light guide plate 7 is a substantially conical shape with a bottom surface having a diameter of 5.3 mm and a depth of 4.5 mm, and a conical vertex having a curvature radius of 0.25 mm. The thickness of the thickest portion of the light guide plate 7 is set to 5.5 mm, and the thickness of the light guide plate 7 having the smallest thickness when the end of the inclined portion 13 is flat is set to 1.5 mm. did. The oblique portion 13 is guided with a radius of curvature of 15 mm so that the angle θ formed with the light exit surface 11 in the vicinity of the storage portion 9 is 15.76 degrees, and in the vicinity of the end portion, θ becomes 0 degree as the end portion is approached. The curve swells inside the light plate 7.
As the light source 1, a blue LED 50 that emits blue light is covered with a phosphor 51 that emits yellow light applied inside the LED lens 53, and a white LED 46 that emits pseudo white light is used.
As the reflection sheet 5, a resin sheet in which voids made of air were formed on PET to increase the reflectance was used, and the reflection sheet 5 was integrated with the oblique portion 13 with an adhesive.
The reflector 3 used the same resin sheet as the reflection sheet 5 and closed the storage portion 9 of the light guide plate 7.
The above-described configuration is aligned in the housing 19 with the sides of the light emitting surface 11 aligned, and the light guide plate coupling body 91 is configured and incorporated in the backlight unit 31. When connected, the light guides 7 were connected with a step as shown in FIG.
On the backlight unit 31 described above, as the optical sheet 33, the diffusion plate 21 and the light control sheet 23 were stacked in order from the back side.
The diffusion plate 21 is manufactured by an extrusion molding method in which a filler is dispersed in a polycarbonate which is a transparent resin. The thickness of the diffusing plate 21 was 2.0 mm, the total light transmittance was 65%, and the haze was 99%.
As the light control sheet 23, a lenticular lens sheet obtained by molding a lens on a PET film (thickness: 75 μm) using a UV ray curable resin was used. The lens pitch of the lenticular lens sheet was 98 μm, and the lens shape was an aspheric lens shape.
A display unit 35 is built on the backlight unit 31 and the optical sheet 33 described above to constitute a display device 37.
As a result of observing the display device 37 after 6 hours have elapsed since the light source 1 was turned on and the temperature inside the backlight unit 31 reached the maximum temperature, bright lines were visually recognized between the viewer side X and the light guide plate 7. It was. Further, moire was generated between the light guides 7 and was visually recognized from the viewer side X.

(Example 5)
The light guide plate 7 in which the light emission surface 11 has a regular hexagonal shape and the length of each side of the regular hexagon is 14 mm was manufactured by an extrusion molding method.
Here, polycarbonate was used as the material of the light guide plate 7.
The shape of the storage portion 9 of the light guide plate 7 is a substantially conical shape with a bottom surface having a diameter of 5.3 mm and a depth of 4.5 mm, and a conical vertex having a curvature radius of 0.25 mm. The thickness of the thickest portion of the light guide plate 7 is set to 5.5 mm, and the thickness of the light guide plate 7 having the smallest thickness when the end of the inclined portion 13 is flat is set to 1.5 mm. did. The oblique portion 13 is guided with a radius of curvature of 15 mm so that the angle θ formed with the light exit surface 11 in the vicinity of the storage portion 9 is 15.76 degrees, and in the vicinity of the end portion, θ becomes 0 degree as the end portion is approached. The curve swells inside the light plate 7.
As the light source 1, a blue LED 50 that emits blue light is covered with a phosphor 51 that emits yellow light applied inside the LED lens 53, and a white LED 46 that emits pseudo white light is used.
As the reflection sheet 5, a resin sheet in which voids made of air were formed on PET to increase the reflectance was used, and the reflection sheet 5 was integrated with the oblique portion 13 with an adhesive.
The reflector 3 used the same resin sheet as the reflection sheet 5 and closed the storage portion 9 of the light guide plate 7.
The above-described configuration is aligned in the housing 19 with the sides of the light emitting surface 11 aligned, and the light guide plate coupling body 91 is configured and incorporated in the backlight unit 31. When connected, the light guides 7 were connected with a step as shown in FIG.
In the vicinity of the end of the backlight unit 31, the light guide plate connector 91 was installed by the following four methods.
Respectively, it is set as Example 5 (a)-5 (d).
In Example 5 (a), the end portion of the light guide plate coupling body 91 is covered with the housing 19 as shown in FIG. 30 (a). The width | variety which the housing | casing 19 covers the edge part of the light-guide plate coupling body 91 was 10 mm.
In Example 5 (b), the shape of the light exit surface 11 of the light guide plate 7 installed at the end of the backlight unit is not a regular polygon as shown in FIG. 30 (b), but the end of the backlight unit 31 of the light guide plate 7. It is the structure which made the shape into which a part becomes a linear form. Here, all the light incident surfaces 11 of the light guide plate 7 installed at the end of the backlight unit 31 are pentagonal as shapes other than the regular polygon.
In Example 5 (c), as shown in FIG. 30 (c), reflection in which fine particles of titanium oxide are dispersed in an adhesive between the housing 19 and the light guide plate 7 installed at the end of the light guide plate coupling body 91. In this configuration, the agent 69 is filled. Here, the light incident surfaces 11 of the light guide plate 7 installed at the end of the backlight unit are all regular hexagons.
In Example 5 (d), as shown in FIG. 30 (d), a method of using the light guide plate 7 whose light emission surface 11 is not a regular polygon, and a light guide plate installed at the end of the casing 19 and the light guide plate coupling body 91 are used. 7 and the method of filling the same reflective agent 69 as in Example 5 (c). Here, in the light guide plate 7 in which the light incident surface 11 installed at the end of the backlight unit 31 is not a regular polygon, the area of the light incident surface 11 is the same as that of the light incident surface 11 installed other than the end. When the area is 50% or less compared to the area of the light incident surface 11 of the light guide plate 7 having a polygonal shape, no light source is installed on the light guide plate 7. In addition, the light incident surface 11 of the light guide plate 7 installed at the end of the backlight unit 31 is a heptagon, hexagon, pentagon, square, or triangle as a shape other than a regular polygon.
As a result of measuring the luminance of the backlight unit 31 described above, the luminance near the center of the backlight unit is L, and the luminance at a position 20 mm away from the end of the casing in the vertical direction near the end of the backlight unit 31 is L *. L * / L is 0.9 times in Example 5 (a), 1.1 times in Example 5 (b), 0.8 times in Example 5 (c), and Example 5 ( In d), the brightness was 0.5 times, and the luminance unevenness visually recognized on the viewer side X did not occur.
From this result, it was confirmed that when L * / L was 0.1 or more and 10 or less, it was not visually recognized as luminance unevenness.
On the backlight unit 31 described above, as the optical sheet 33, the transmittance adjusting sheet 22, the diffusion plate 21, and the light control sheet 23 were stacked in order from the back side.
The transmittance adjusting sheet 22 is manufactured by printing a white ink in which titanium oxide is dispersed as a pigment on a PET film (thickness: 75 μm) of the support substrate 18 as a transmittance adjusting pattern 20 by a screen printing method. did. A pattern similar to FIG. 18 was formed in a halftone dot shape. The size of one dot pattern of halftone dots was a square shape of 0.5 mm × 0.5 mm.
The diffusion plate 21 is manufactured by an extrusion molding method in which a filler is dispersed in a polycarbonate which is a transparent resin. The thickness of the diffusing plate 21 was 2.0 mm, the total light transmittance was 65%, and the haze was 99%.
As the light control sheet 23, a lenticular lens sheet obtained by molding a lens on a PET film (thickness: 75 μm) using a UV ray curable resin was used. The lens pitch of the lenticular lens sheet was 98 μm, and the lens shape was an aspheric lens shape.
A display unit 35 is built on the backlight unit 31 and the optical sheet 33 described above to constitute a display device 37.
As a result of observing the display device 37 after 6 hours have passed since the light source 1 was turned on and the temperature inside the backlight unit 31 reached the maximum temperature, which of the examples 5 (a) to 5 (d) Even in the configuration, the light guide plate connector 91 was not warped, and no bright line was seen from the viewer side X between the light guide plates 7.

(Example 6)
In the sixth embodiment, the transmittance adjustment sheet 22 is removed from the configuration of the fifth embodiment.
The light guide plate 7 in which the light emission surface 11 has a regular hexagonal shape and the length of each side of the regular hexagon is 14 mm was manufactured by an extrusion molding method.
Here, polycarbonate was used as the material of the light guide plate 7.
The shape of the storage portion 9 of the light guide plate 7 is a substantially conical shape with a bottom surface having a diameter of 5.3 mm and a depth of 4.5 mm, and a conical vertex having a curvature radius of 0.25 mm. The thickness of the thickest portion of the light guide plate 7 is set to 5.5 mm, and the thickness of the light guide plate 7 having the smallest thickness when the end of the inclined portion 13 is flat is set to 1.5 mm. did. The oblique portion 13 is guided with a radius of curvature of 15 mm so that the angle θ formed with the light exit surface 11 in the vicinity of the storage portion 9 is 15.76 degrees, and in the vicinity of the end portion, θ becomes 0 degree as the end portion is approached. The curve swells inside the light plate 7.
As the light source 1, a blue LED 50 that emits blue light is covered with a phosphor 51 that emits yellow light applied inside the LED lens 53, and a white LED 46 that emits pseudo white light is used.
As the reflection sheet 5, a resin sheet in which voids made of air were formed on PET to increase the reflectance was used, and the reflection sheet 5 was integrated with the oblique portion 13 with an adhesive.
The reflector 3 used the same resin sheet as the reflection sheet 5 and closed the storage portion 9 of the light guide plate 7.
The above-described configuration is aligned in the housing 19 with the sides of the light emitting surface 11 aligned, and the light guide plate coupling body 91 is configured and incorporated in the backlight unit 31. When connected, the light guides 7 were connected with a step as shown in FIG.
In the vicinity of the end of the backlight unit 31, the light guide plate connector 91 was installed by the following four methods.
These are designated as Examples 6 (a) to 6 (d).
In Example 6 (a), the end portion of the light guide plate coupling body 91 is covered with the housing 19 as shown in FIG. 30 (a). The width | variety which the housing | casing 19 covers the edge part of the light-guide plate coupling body 91 was 10 mm.
In Example 6 (b), the shape of the light exit surface 11 of the light guide plate 7 installed at the end of the backlight unit is not a regular polygon as shown in FIG. 30 (b), but the end of the backlight unit 31 of the light guide plate 7. It is the structure which made the shape into which a part becomes a linear form. Here, all the light incident surfaces 11 of the light guide plate 7 installed at the end of the backlight unit 31 are pentagonal as shapes other than the regular polygon.
In Example 6 (c), as shown in FIG. 30 (c), a reflection in which fine particles of titanium oxide are dispersed in an adhesive between the casing 19 and the light guide plate 7 installed at the end of the light guide plate coupling body 91. In this configuration, the agent 69 is filled. Here, the light incident surfaces 11 of the light guide plate 7 installed at the end of the backlight unit are all regular hexagons.
Example 6 (d) is a method using a light guide plate 7 whose light exit surface 11 is not a regular polygon as shown in FIG. 30 (d), and a light guide plate installed at the end of the casing 19 and the light guide plate connector 91. 7 and the method of filling the same reflective agent 69 as in Example 5 (c). Here, in the light guide plate 7 in which the light incident surface 11 installed at the end of the backlight unit 31 is not a regular polygon, the area of the light incident surface 11 is the same as that of the light incident surface 11 installed other than the end. When the area was 50% or less compared to the area of the light incident surface 11 of the light guide plate 7 having a polygonal shape, no light source was installed on the light guide plate 7. In addition, the light incident surface 11 of the light guide plate 7 installed at the end of the backlight unit 31 is a heptagon, hexagon, pentagon, square, or triangle as a shape other than a regular polygon.
As a result of measuring the luminance of the backlight unit 31 described above, the luminance near the center of the backlight unit is L, and the luminance at a position 20 mm away from the end of the casing in the vertical direction near the end of the backlight unit 31 is L *. L * / L is 0.9 times in Example 6 (a), 1.1 times in Example 6 (b), 0.8 times in Example 6 (c), and Example 6 ( In d), the brightness was 0.5 times, and the luminance unevenness visually recognized on the viewer side X did not occur.
From this result, it was confirmed that when L * / L was 0.5 or more and 10 or less, it was not visually recognized as luminance unevenness.
On the backlight unit 31 described above, as the optical sheet 33, the diffusion plate 21 and the light control sheet 23 were stacked in order from the back side.
The diffusion plate 21 is manufactured by an extrusion molding method in which a filler is dispersed in a polycarbonate which is a transparent resin. The thickness of the diffusing plate 21 was 2.0 mm, the total light transmittance was 65%, and the haze was 99%.
As the light control sheet 23, a lenticular lens sheet obtained by molding a lens on a PET film (thickness: 75 μm) using a UV ray curable resin was used. The lens pitch of the lenticular lens sheet was 98 μm, and the lens shape was an aspheric lens shape.
A liquid crystal panel is incorporated as the display unit 35 on the backlight unit 31 and the optical sheet 33 described above to constitute a display device 37.
As a result of observing the display device 37 after the elapse of 6 hours after the light source 1 was turned on and the temperature inside the backlight unit 31 reached the maximum temperature, which of the examples 6 (a) to 6 (d) Even in the configuration, the light guide plate connector 91 was not warped, and no bright line or moire was observed between the light guide plates 7 from the viewer side X.
From this result, when the light emission surface 11 was a regular hexagon, since the connection part was zigzag-shaped, it confirmed that generation | occurrence | production of a bright line and moire was suppressed.

It is a schematic sectional drawing which shows an example of the display apparatus of this invention. It is the schematic which shows an example of white LED as a light source. It is the schematic which shows the other example of white LED as a light source. It is the schematic which shows the combination of monochromatic LED as a light source. It is the schematic which shows an example of a semiconductor laser as a light source. It is the schematic which shows an example of a fluorescent lamp as a light source. (A)-(h) is a transmission figure which shows the modification of the storage part shape of a light-guide plate. It is a perspective view which shows the light source in the display apparatus shown in FIG. 1, a light-guide plate, and an optical sheet. (A)-(f) is sectional drawing which shows the modification of the oblique part shape of a light-guide plate. It is a perspective view which shows the modification of the oblique part shape of a light-guide plate. It is a perspective view at the time of making the light-projection surface shape of a light-guide plate into a regular hexagon. (A)-(d) is a top view which shows the modification of the light-projection surface shape of a light-guide plate. It is a top view which shows the change of the maximum distance from a light source to an edge part at the time of increasing the number of sides of the regular polygon shape of a light-projection surface. It is a perspective view which shows a light-guide plate block. It is a perspective view which shows the modification of a light-guide plate block. It is a cross-sectional shape including the central axis of the light guide plate, showing the ray diagram and the illuminance distribution on the light exit surface. It is sectional drawing which shows the example of a light control sheet. It is the schematic which shows the density distribution of the transmittance | permeability adjustment pattern of the transmittance | permeability adjustment sheet. It is a figure which shows the structural example which integrated the diffuser plate and the light control sheet. It is a top view which shows the example at the time of connecting a congruent regular polygon. It is a top view which shows the example at the time of connecting the regular polygon from which an area differs in the same shape. It is a top view which shows the example at the time of connecting the regular polygon from which two or more types of shapes differ. It is a perspective view which shows the modification of the light guide body connection side surface of a light guide plate. It is sectional drawing and the top view which show the behavior of the light-guide plate by a thermal expansion, and a light-guide plate coupling body. It is a top view which shows the example which formed uneven | corrugated shape in each edge | side of the light-projection surface of a light-guide plate. It is sectional drawing which shows the example which formed uneven | corrugated shape in the light guide body connection side surface of a light-guide plate. It is a perspective view which shows the light-guide plate coupling body which provided the level | step difference between the light-guide plates and connected. It is a perspective view which shows the example which provided the fixing element in the light-guide plate block. It is the top view which showed the bright line reduction at the time of making a light-projection surface into a regular hexagon. It is the top view which showed the arrangement | positioning method of the light-guide plate in the backlight unit edge part vicinity. It is a top view which shows the example which shifted the position of the storage part of the light-guide plate in the backlight unit edge part vicinity from the center part of the light-projection surface. It is the schematic which showed the method of laser-cutting the light-guide plate coupling body which integrally formed the light-guide plate. It is a perspective view which shows the structure of the conventional backlight unit.

Explanation of symbols

a, b, c, d, e ... light, the minimum distance between the maximum distance, B ... source and the light guide plate end of the A ... light source and the light guide plate end, C ... light guide plate center axis, H 0 _... storage section Depth, H ₁ ... Thickness of flat part formed by flat surface, H ₂ ... Thick part of curved part formed by curved surface, S ₁ , S ₂ ... Area of light exit surface, U. ... bright line peripheral area, X ... observer side, θ ... angle formed by oblique part and light emission surface 1 ... light source, 3 ... reflector, 5 ... reflection sheet, 7 ... light guide plate, 9 ... storage part, 11 ... light emission Surface, 13 ... oblique part, 15 ... electric wiring, 17 ... power supply, 18 ... support base material, 19 ... housing, 20 ... transmittance adjustment pattern, 21 ... diffusion plate, 22 ... transmittance adjustment sheet, 23 ... light Control sheet, 25 ... Liquid crystal layer, 27 ... Polarizing plate, 29 ... Liquid crystal drive device, 31 ... Backlight unit, 33 ... Optical sheet, 35 ... Display unit, 37 ... Display device , 38 ... end face, 39 ... light guide plate connection side surface, 40 ... connection part, 41 ... light guide plate block, 43 ... light guide plate block side surface, 45 ... light guide plate block internal space part, 46 ... white LED, 47 ... LED substrate, 48 ... red LED element, 49 ... green LED element, 50 ... blue LED element, 51 ... phosphor, 53 ... LED lens, 54 ... red LED, 55 ... green LED, 56 ... blue LED, 57 ... red semiconductor laser, 58 ... Green semiconductor laser, 59 ... Blue semiconductor laser, 60 ... Fiber, 61 ... Semiconductor laser lens, 61 ... Fluorescent lamp, 65 ... Gap, 67 ... Fixing element, 69 ... Reflective agent, 71 ... Roll, 73 ... Laser oscillation 75 ... Laser light, 77 ... Cutting line, 79 (a), 79 (b) ... Bright line, 81 ... Transmittance adjustment pattern high density region, 82 ... Junction layer, 83 ... Sa, 85 ... air layer, 87 ... light reflection layer, 89 ... fixing element, 91 ... light guide plate connecting body

Claims (10)

A light exit surface;
A thick portion formed near the center of the exit surface;
A recess for accommodating a light source formed in the thick part on the back surface facing the emission surface;
A thin portion located at the end of the exit surface;
A slanted portion inclined so that the thickness gradually decreases from the thick portion to the thin end portion on the back surface, and a light guide plate comprising:
The light guide plate is characterized in that the shape of the light exit surface is a regular polygon. A light exit surface;
A thick portion formed near the center of the exit surface;
A recess for accommodating a light source formed in the thick part on the back surface facing the emission surface;
A thin portion located at the end of the exit surface;
A slanted portion inclined so that the thickness gradually decreases from the thick portion to the thin end portion on the back surface, and a light guide plate comprising:
The light guide plate according to claim 1, wherein the shape of the oblique portion is a flat surface or a shape including a curved surface in a part thereof. A plurality of the light guide plates according to claim 1 or 2,
A light guide plate assembly in which thin end portions of the light guide plates are connected to each other,
The light guide plate coupling body, wherein the light exit surfaces of the light guide plates are formed of the same regular polygon. A plurality of the light guide plates according to claim 1 or 2,
A light guide plate assembly in which thin end portions of the light guide plates are connected to each other,
The light guide plate assembly, wherein the light exit surface of each of the light guide plates comprises at least two different regular polygons. A plurality of the light guide plates according to claim 1 or 2,
A light guide plate assembly in which thin end portions of the light guide plates are connected to each other,
Each of the light guide plates has an uneven shape in which the shape of the end of the thin portion is fitted. It is a light-guide plate coupling body of Claim 3 thru | or 5, Comprising:
The light guide plate coupling body, wherein the light exit surfaces of the respective light guide plates are connected with a step along the thickness direction of the light guide plate. The said light-guide plate is produced by injection molding or extrusion molding, The light-guide plate coupling body of Claim 1 characterized by the above-mentioned. In the housing,
The light source;
A power supply path section for supplying power to the light source;
A reflective member provided on the outer side of the light guide plate;
The light guide plate connector according to claim 3 or 6,
A backlight unit comprising: The backlight unit according to claim 8, wherein
9. The backlight unit according to claim 8, wherein, of the light emission surface, the luminance ratio between the vicinity of the end of the housing and the other portion is 0.1 to 10 times. On the light exit surface of the backlight, at least an optical sheet,
Furthermore, an image display unit is arranged on the display device.