TW201728974A - Light guide, back light unit, liquid crystal display, attachable sheet and method for manufacturing the light guide - Google Patents

Abstract

A light guide is in a plate-shaped light guide and configured for a back light unit and able to guide the light incident on its edge to pass through its surface. The light guide has a glass plate and a resin layer laminated on a back surface of the glass plate. The resin layer has a plurality concaves formed on its back side and a plurality convexes formed around the concaves. The average thickness of the resin layer ranges between 5 [mu]m and 50 [mu]m. The average depth L of the concaves ranges between 1 [mu]m and 10 [mu]m. The average diameter D of the concaves ranges between 10 [mu]m and 50 [mu]m. In addition, the convexes are arranged in a ring shape from top view. The average width W of the convexes ranges between 1[mu]m and 15 [mu]m.

Description

Light guide, backlight unit, liquid crystal display device, adhesion preventing sheet, and light guide for backlight unit

The present invention relates to a light guide, a backlight unit, a liquid crystal display device, an adhesion preventing sheet, and a method of manufacturing a light guide for a backlight unit.

A backlit liquid crystal display device that illuminates a liquid crystal panel from the back side to emit light has been widely used, and a backlight unit such as a side light type or a direct type is mounted on the back side of the liquid crystal panel. As shown in FIG. 9, the edge type backlight unit 101 included in the liquid crystal display device generally includes a light source 102, a square plate-shaped light guide plate 103, and an end portion disposed along the light source 102; and a plurality of optical sheets 104. The surface of the light guide plate 103 is superposed on the surface of the light guide plate 103, and the reflection sheet 105 is disposed on the back side of the light guide plate 103. The light guide plate 103 is usually made of synthetic resin, and polycarbonate, acrylic resin or the like is used as a main component. As the light source 102, an LED (light emitting diode), a cold cathode tube, or the like is used, but from the viewpoints of miniaturization and energy saving, LEDs have been widely used. Further, as the optical sheet 104, (1) a light diffusion sheet 106 having a light diffusion function mainly disposed on the surface side of the light guide plate 103, and (2) disposed on the surface side of the light diffusion sheet 106, having light rays directed toward the normal line The ruthenium 107 of the refractive function of the refracting direction side, and the like.

In order to improve the sharpness, sharpness, and the like of the display image, the liquid crystal display device is required to have a high luminance in the front direction. In addition, in order to meet such a demand, a light guide plate made of a glass plate having a higher light guiding property than a synthetic resin has been proposed (refer to Japanese Laid-Open Patent Publication No. 2015-72896).

Prior art literature:

Patent Document 1: Japanese Patent Laid-Open Publication No. 2015-72896.

The present inventors have found that the use of such a light guide plate composed of a glass plate causes a problem that the brightness of the liquid crystal display surface becomes uneven. In view of the above-mentioned problems, the inventors of the present invention have found that the back surface of the light guide plate is in close contact with the reflection sheet or the like disposed on the back side of the light guide plate, and light is incident on the adhesion portion. Uneven brightness.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a light guide, a backlight unit, a liquid crystal display device, and an adhesion preventing sheet which can suppress uneven brightness and can achieve high luminance. Further, another object of the present invention is to provide a method of manufacturing a light guide for a backlight unit capable of suppressing unevenness in luminance and achieving high luminance.

In order to solve the above problems, the present invention provides a light guide body that is a plate-shaped light guide body for a backlight unit that emits light incident from an end surface from a surface, the light guide body having a glass plate and laminated thereon The resin layer on the back side of the glass plate has a plurality of concave portions on the back surface and is recessed toward the front surface side, and a plurality of raised portions are present around the plurality of concave portions and protrude toward the back side.

The light guide body has a resin layer laminated on the back side of the glass sheet, and the resin layer has a plurality of raised portions protruding toward the back side on the back surface, so that the light guide body and the rear surface of the light guide body are disposed. The other members on the side abut on the dispersed points by the plurality of ridges. Therefore, the light guide body can be prevented from being in close contact with other members disposed on the back side. Further, since the resin layer of the light guide body has a plurality of concave portions recessed toward the front surface side on the back surface, light rays incident on the plurality of concave portions can be scattered toward the surface side. In particular, since the ridge portion is present around the concave portion, the light guide body can appropriately prevent the concave portion from being in close contact with the concave portion. Therefore, unevenness in brightness caused by light scattered by the concave portion can be satisfactorily prevented. Further, since the glass plate has a good light guiding property, the light guiding body can achieve high luminance.

The average thickness of the resin layer is preferably 5 μm or more and 50 μm or less. By setting the average thickness of the resin layer within the above range, it is possible to suppress the thickness of the light guide from being unnecessarily thick, and it is possible to suppress damage to other members disposed on the back surface of the light guide. Further, by making the average thickness of the resin layer within the above range, the plurality of concave portions and the plurality of raised portions can be easily and reliably formed.

The average depth L of the concave portion is preferably 1 μm or more and 10 μm or less. Thus, by making the average depth L of the concave portion within the above range, it is possible to easily and reliably form a concave portion having a good scattering function for incident light.

The average diameter D of the concave portion is preferably 10 μm or more and 50 μm or less. As described above, by making the average diameter D of the concave portion within the above range, it is possible to easily and reliably form a concave portion having a good scattering function for incident light.

The average height H of the raised portion is preferably 0.1 μm or more and 5 μm or less. By setting the average height H of the raised portion within the above range, it is possible to easily and appropriately prevent the surface of the other member disposed on the back side of the light guide from being damaged. Further, by setting the average height H of the raised portion within the above range, it is possible to more reliably prevent the vicinity of the concave portion and the concave portion from being in close contact with other members disposed on the back side of the light guide body, thereby being more reliably prevented Light unevenness is caused by light scattered by a plurality of concave portions.

Preferably, the raised portion is formed in a substantially annular shape in plan view so as to surround the concave portion, and the average width W of the raised portion is preferably 1 μm or more and 15 μm or less. By forming the raised portion so as to surround the concave portion so as to form a substantially annular shape in plan view, it is possible to more reliably prevent the vicinity of the concave portion and the concave portion from being in close contact with other members disposed on the back side of the light guide. In addition, by making the average width W of the raised portion within the above range, it is possible to suppress an increase in the contact area between the light guide and other members disposed on the back side of the light guide, and it is possible to appropriately prevent The surface of other components is damaged.

The height ratio (H/W) of the average height H to the average width W of the raised portion is preferably 0.05 or more and 0.5 or less. By setting the height ratio (H/W) of the average height H of the raised portion to the average width W within the above range, it is possible to reliably prevent the surface of other members disposed on the back side of the light guide from being damaged.

An edge-lit backlight unit of the present invention for solving the above problems, comprising: the light guide; and a light source that illuminates an end surface of the light guide.

Since the backlight unit includes the light guide body, it is possible to suppress unevenness in luminance as described above and to achieve high luminance.

Further, a liquid crystal display device of the present invention for solving the above problem includes the backlight unit.

Since the liquid crystal display device includes the backlight unit, it is possible to suppress unevenness in luminance as described above and to achieve high luminance.

Further, the adhesion preventing sheet of the present invention for solving the problem is adhered to a glass plate for preventing adhesion of the back surface of the glass sheet, and the adhesion preventing sheet has a plurality of concave portions on the back surface, facing the surface a side recess; and a plurality of ridges present around the plurality of recesses and protruding toward the back side.

The adhesion preventing sheet is adhered to the glass plate to form a resin layer laminated on the back side of the glass plate. That is, the light guide is obtained by adhering the adhesion preventing sheet to a glass plate, and the light guide body includes a glass plate and a resin layer laminated on the back side of the glass plate, the resin layer having a back surface a plurality of concave portions that are recessed toward the surface side, and a plurality of raised portions that are present around the plurality of concave portions and protrude toward the back side. Therefore, by adhering the adhesion preventing sheet to the glass plate, unevenness in brightness can be suppressed and high luminance can be achieved.

Further, in the method of manufacturing a light guide for a backlight unit of the present invention, the light guide for a backlight unit is a plate-shaped light guide for a backlight unit that emits light incident from an end surface from a surface. The method for manufacturing a light guide for a backlight unit includes a step of forming a resin layer having a plurality of concave portions on one surface and recessed toward the other surface side, and a plurality of raised portions present in the plurality of a periphery of the concave portion and protruding toward one surface side; and a step of adhering the other surface of the resin layer to the glass plate.

According to the method for producing a light guide for a backlight unit, the light guide may be provided with a glass plate and a resin layer laminated on the back side of the glass plate, the resin layer having a back surface a plurality of concave portions that are recessed toward the surface side, and a plurality of raised portions that are present around the plurality of concave portions and protrude toward the back side. Therefore, in the method of manufacturing a light guide for a backlight unit, it is possible to manufacture a light guide for a backlight unit capable of suppressing unevenness in luminance and achieving high luminance.

In the present invention, the term "surface side" means the viewer side of the liquid crystal display device, and the "back side" means the side opposite to the "surface side". In addition, "surface" means the surface on the surface side, and "back surface" means the surface opposite to the "surface". "Plate shape" means having two opposite faces (the outermost surface and the rearmost face), and the opposite faces are parallel in a region of 70% or more in plan view, and it is preferable that 80% or more of the regions are parallel, more preferably More than 90% of the area is parallel. Further, the "parallel" of the opposite sides means that the angle formed between the average interfaces on the opposite sides is 5 or less, preferably 3 or less, and more preferably 1 or less. "Average thickness" means the average value of the thickness of any 10 points. In addition, the "average thickness of a resin layer" means the average thickness of the flat surface which does not have the several recessed part and several ridges. The "average depth of the concave portion" refers to the average depth from the average interface of the back surface of the resin layer, and is an extraction of an arbitrary 20 concave portions, and an average value of 10 depths of 5 having a large depth and 5 having a small depth is removed. In addition, the "average interface of the back surface of the resin layer" means the interface of the flat surface of the back surface of the resin layer which does not have a plurality of recessed parts and a plurality of raised portions. The "diameter of the concave portion" means the diameter of the concave portion on the average interface of the back surface of the resin layer, and indicates the intermediate value between the maximum diameter of the concave portion and the diameter perpendicular to the maximum diameter direction. In addition, the "average diameter of the concave portion" means that an arbitrary 20 concave portions are extracted, and an average value of 10 diameters of five large diameters and five small diameters is removed. The "average height of the raised portion" means the average height from the average interface of the back surface of the resin layer, and represents the average value of the heights of the arbitrary ten raised portions. The "width of the ridge portion" means the difference between the outer radius and the inner radius of the ridge portion on the average interface of the back surface of the resin layer. For example, the width of the raised portion can be obtained by subtracting the value of 1/2 of the inner diameter from the value of 1/2 of the outer diameter of the largest portion of the raised portion. The "average width of the ridges" refers to the average of the widths of any of the ten ridges.

As described above, the light guide, the backlight unit, the liquid crystal display device, and the adhesion preventing sheet of the present invention can suppress unevenness in luminance and can achieve high luminance. Further, in the method for producing a light guide for a backlight unit of the present invention, it is possible to manufacture a light guide for a backlight unit which can suppress unevenness in brightness and can achieve high luminance.

The above description of the disclosure and the following description of the embodiments of the present invention are intended to illustrate and explain the spirit and principles of the invention, and to provide further explanation of the scope of the invention.

The detailed features and advantages of the present invention are set forth in the Detailed Description of the Detailed Description of the <RTIgt; </ RTI> <RTIgt; </ RTI> </ RTI> </ RTI> <RTIgt; The objects and advantages associated with the present invention can be readily understood by those skilled in the art. The following examples are intended to describe the present invention in further detail, but are not intended to limit the scope of the invention.

[First Embodiment]

<Liquid crystal display device>

The liquid crystal display device 1 of Fig. 1 is configured as a portable terminal. The liquid crystal display device 1 includes an operation unit 2 and a liquid crystal display unit 3, and the liquid crystal display unit 3 is rotatably (openably and closably) connected to the operation unit 2. In the liquid crystal display device 1, the thickness of the casing (outer casing) constituting the constituent portion of the liquid crystal display device 1 (the thickest portion at the time of closing the liquid crystal display portion 3) is 21 mm or less, and is an ultra-thin notebook computer ( Hereinafter, it is sometimes referred to as "ultra-thin computer 1").

The liquid crystal display unit 3 of the ultra-thin computer 1 includes a liquid crystal panel 4 and a side-light type ultra-thin type backlight unit, and the side-light type ultra-thin type backlight unit emits light from the back side toward the liquid crystal panel 4. The periphery of the back surface, the side surface, and the surface of the liquid crystal panel 4 is held by the outer casing 5 for the liquid crystal display portion of the casing. Here, the liquid crystal display unit casing 5 has a top plate 6 disposed on the back surface (and the back surface) of the liquid crystal panel 4, and a surface supporting member 7 disposed on the surface side around the surface of the liquid crystal panel 4. The casing of the ultra-thin computer 1 includes a casing 5 for a liquid crystal display unit and a casing 9 for an operation portion, and the casing 9 for the operation portion is rotatably provided to the casing 5 for the liquid crystal display portion via a hinge portion 8, and is built in There are central computing processing devices (ultra-low voltage CPUs) and so on. The average thickness of the liquid crystal display unit 3 is not particularly limited as long as the thickness of the casing is within a desired range. The lower limit of the average thickness of the liquid crystal display unit 3 is preferably 2 mm, more preferably 3 mm. More preferably, it is 4 mm. On the other hand, the upper limit of the average thickness of the liquid crystal display portion 3 is preferably 7 mm, more preferably 6 mm, still more preferably 5 mm. If the average thickness of the liquid crystal display unit 3 is less than the lower limit, there is a problem that the strength of the liquid crystal display unit 3 is lowered and the brightness is lowered. On the other hand, if the average thickness of the liquid crystal display unit 3 exceeds the upper limit, there is a problem that the thinning request of the ultra-thin computer 1 is not satisfied.

<backlight unit>

The backlight unit 11 of FIG. 2 is provided in the liquid crystal display unit 3 of the ultra-thin computer 1. The backlight unit 11 is configured as an edge-light type backlight unit. The side-light type backlight unit includes a light guide body 12, a light source 13 that irradiates light to an end surface of the light guide body 12, and a reflection sheet 14 disposed on a back side of the light guide body 12; The optical sheet 15 is disposed on the surface side of the light guide body 12.

(light guide)

The light guide body 12 causes the light incident from the end surface to be emitted substantially uniformly from the surface. The light guide body 12 is formed in a plate shape (non-wedge shape). Further, the light guide body 12 is formed in a substantially square shape in plan view. The light guide body 12 is provided with a glass plate 16 and a resin layer 17, and the resin layer 17 is laminated on the back side of the glass plate 16. The glass plate 16 and the resin layer 17 are bonded by the adhesive layer 18. The light guide body 12 is configured as a three-layer structure of the glass plate 16, the resin layer 17, and the adhesive layer 18.

The lower limit of the average thickness of the light guide body 12 is preferably 100 μm, more preferably 150 μm, still more preferably 200 μm. On the other hand, the upper limit of the average thickness of the light guide body 12 is preferably 600 μm, more preferably 580 μm, still more preferably 550 μm. If the average thickness of the light guide body 12 is smaller than the lower limit, there is a problem that the strength of the light guide body 12 becomes insufficient, and there is a problem that the light of the light source 13 cannot be sufficiently incident into the light guide body 12. On the other hand, if the average thickness of the light guide body 12 exceeds the upper limit, there is a problem that it is difficult to use the ultra-thin portable terminal.

The lower limit of the necessary light guiding distance from the end surface on the light source 13 side of the light guide body 12 is preferably 7 cm, more preferably 9 cm, still more preferably 11 cm. On the other hand, the upper limit of the necessary light guiding distance from the end surface on the light source 13 side of the light guide body 12 is preferably 45 cm, more preferably 43 cm, still more preferably 41 cm. If the necessary light guiding distance is smaller than the lower limit, there is a problem that it cannot be used for a large terminal other than a small mobile terminal. On the other hand, if the necessary light guiding distance exceeds the upper limit, there is a problem that the glass plate 16 may be broken. In addition, the necessary light guiding distance of the light guide body 12 from the end surface on the light source 13 side means a light beam which is emitted from the light source 13 and incident on the end surface of the light guide body 12, and a distance required to travel from the end surface toward the opposite end surface direction. . Specifically, for example, for a single-sided edge type backlight unit, the necessary light guiding distance of the light guide body 12 from the end surface on the light source 13 side refers to the distance from the end surface of the light guide body to the opposite end surface. In the side-lit backlight unit, the necessary light guiding distance of the light guide body 12 from the end surface on the light source 13 side means the distance from the end surface of the light guide body to the center portion.

The lower limit of the surface area of the light guide body 12 is preferably 150 cm 2 , more preferably 180 cm 2 , still more preferably 200 cm 2 . On the other hand, the upper limit of the surface area of the light guide body 12 is preferably 1000 cm 2 , more preferably 950 cm 2 , still more preferably 900 cm 2 . If the surface area of the light guide body 12 is smaller than the lower limit, there is a problem that it cannot be used for a large terminal other than a small mobile terminal. On the other hand, if the surface area of the light guide body 12 exceeds the upper limit, there is a problem that the glass plate 16 may be broken.

(glass plate)

The glass plate 16 is disposed on the outermost surface of the light guide body 12. The glass plate 16 internally propagates the light that is radiated from the light source 13. The glass plate 16 is transparent, especially colorless and transparent, because it needs to transmit light. The glass plate 16 is formed, for example, using soda glass, borosilicate glass, alkali-free glass, quartz glass, lead glass, crystallized glass, or the like. The glass sheet 16 may have rigidity or may have flexibility.

The lower limit of the average thickness of the glass plate 16 is preferably 80 μm, more preferably 150 μm, still more preferably 200 μm. On the other hand, the upper limit of the average thickness of the glass plate 16 is preferably 580 μm, more preferably 550 μm, still more preferably 500 μm. If the average thickness of the glass sheet 16 is less than the lower limit, there is a problem that the glass sheet 16 cannot obtain sufficient strength and the glass sheet 16 may be broken. Further, if the average thickness of the glass plate 16 is less than the lower limit, there is a problem that the light irradiated from the light source 13 cannot be sufficiently incident into the glass plate 16. On the other hand, if the average thickness of the glass plate 16 exceeds the upper limit, there is a problem that it is difficult to use the ultra-thin portable terminal. Further, when the average thickness of the glass sheet 16 exceeds the upper limit, there is a problem that the weight of the glass sheet 16 increases, and the reflection sheet 14 disposed on the back side of the light guide body 12 may be damaged.

The lower limit of the refractive index of the glass plate 16 is preferably 1.45, more preferably 1.47, still more preferably 1.49. On the other hand, as the upper limit of the refractive index of the glass plate 16, it is preferably 1.6, more preferably 1.58, still more preferably 1.56. If the refractive index of the glass plate 16 is less than the lower limit, there is a problem that the light transmittance in the glass plate 16 is lowered. On the other hand, when the refractive index of the glass plate 16 exceeds the upper limit, there is a problem in that the difference in refractive index between the glass plate 16 and the resin layer 17 is large, and it is difficult for the light emitted from the resin layer 17 to enter the glass plate 16.

The upper limit of the coefficient of thermal expansion of the glass sheet 16 is preferably 100 × 10 ^-7 / ° C, more preferably 80 × 10 ^-7 / ° C, still more preferably 70 × 10 ^-7 / ° C. If the coefficient of thermal expansion of the glass sheet 16 exceeds the upper limit, there is a problem that it is difficult to appropriately maintain the positional relationship between the light guide body 12 and the light source 13 due to the dimensional change of the glass sheet 16. In addition, the "thermal expansion coefficient" means a value obtained based on JIS-R3102:1995.

(resin layer)

The resin layer 17 is disposed on the rearmost side of the light guide body 12. The resin layer 17 has a plurality of concave portions 19 recessed toward the surface side on the back surface. Further, the resin layer 17 has an adhesion preventing portion on the back surface. Specifically, the resin layer 17 has a plurality of ridges 20 that are present around the plurality of recesses 19 and protrude toward the back side as the adhesion preventing portion. The raised portion 20 is disposed adjacent to the concave portion 19, and the inner side surface of the raised portion 20 is continuous with the formation surface of the concave portion 19.

The resin layer 17 has flexibility. Since the resin layer 17 has flexibility, the light guide body 12 can suppress damage of the reflection sheet 14 disposed on the back side of the light guide body 12. The resin layer 17 is transparent because it needs to transmit light, and is particularly colorless and transparent. Examples of the main component of the resin layer 17 include polycarbonate, acrylic resin, polyethylene terephthalate, polyethylene naphthalate, polystyrene, and methyl (meth)acrylate. A styrene copolymer, a polyolefin, a cycloolefin polymer, a cyclic olefin copolymer, cellulose acetate, weather resistant vinyl chloride, an active energy ray-curable resin, and the like. Among them, an acrylic resin which can appropriately maintain the strength of the resin layer 17 and can easily reduce the difference in refractive index between the resin layer 17 and the glass plate 16 is preferable. In addition, the term "main component" means a component having the highest content, and is, for example, a component having a content of 50% by mass or more, preferably a component having a content of 70% by mass or more, and more preferably a content of 90% by mass or more. ingredient.

In addition, the resin layer 17 may also contain an ultraviolet absorber, a flame retardant, a stabilizer, a lubricant, a processing aid, a plasticizer, an impact modifier, a phase difference reducer, a matting agent, an antibacterial agent, an antifungal agent, Any component such as an antioxidant, a release agent, or an antistatic agent.

The lower limit of the average thickness of the resin layer 17 is preferably 5 μm, more preferably 10 μm, still more preferably 15 μm. On the other hand, the upper limit of the average thickness of the resin layer 17 is preferably 50 μm, more preferably 40 μm, still more preferably 30 μm. If the average thickness of the resin layer 17 is less than the lower limit, there is a problem that the reflection sheet 14 disposed on the back side of the light guide body 12 is not sufficiently damaged. Further, when the average thickness of the resin layer 17 is less than the lower limit, there is a problem that it is difficult to form the plurality of concave portions 19 and the plurality of raised portions 20 which will be described later. On the other hand, if the average thickness of the resin layer 17 exceeds the upper limit, there is a problem that the resin layer 17 is unnecessarily thick, which is in violation of the problem of the thinning requirement of the light guide body 12.

The lower limit of the ratio of the average thickness of the resin layer 17 to the average thickness of the glass plate 16 is preferably 0.0083, more preferably 0.02, further preferably 0.03, and particularly preferably 0.04. On the other hand, the upper limit of the ratio of the average thickness of the resin layer 17 to the average thickness of the glass plate 16 is preferably 0.33, more preferably 0.2, still more preferably 0.15, and particularly preferably 0.1. If the ratio of the thickness is less than the lower limit, there is a problem that the performance of preventing damage to the surface of other members disposed on the back side of the light guide body 12 is prevented. On the other hand, if the ratio of the thickness exceeds the upper limit, there is a problem that the light guiding property of the light guide body 12 is lowered.

The lower limit of the refractive index of the resin layer 17 is preferably 1.45, more preferably 1.46, still more preferably 1.48. On the other hand, the upper limit of the refractive index of the resin layer 17 is preferably 1.6, more preferably 1.58, still more preferably 1.55. If the refractive index of the resin layer 17 is out of the above range, there is a problem that the difference in refractive index between the resin layer 17 and the glass plate 16 becomes large, and control of the light incident on the light guide body 12 becomes difficult.

The upper limit of the difference between the refractive index of the glass plate 16 and the refractive index of the resin layer 17 is preferably 0.05, more preferably 0.03, still more preferably 0.01. If the difference between the refractive index of the glass plate 16 and the refractive index of the resin layer 17 exceeds the upper limit, there is a problem that the light transmittance in the glass plate 16 is lowered. Further, the lower limit of the difference between the refractive index of the glass plate 16 and the refractive index of the resin layer 17 is not particularly limited, and may be zero.

It is preferable that the surface of the resin layer 17 is a flat surface. The upper limit of the arithmetic mean roughness Ra of the surface of the resin layer 17 is preferably 0.5 μm, more preferably 0.1 μm, still more preferably 0.05 μm. When the arithmetic mean roughness Ra of the surface of the resin layer 17 exceeds the upper limit, there is a problem that the adhesion to the glass sheet 16 is lowered. In addition, the lower limit of the arithmetic mean roughness Ra of the surface of the resin layer 17 is not particularly limited, and may be, for example, 0.001 μm. In addition, the "arithmetic average roughness Ra" is a value in accordance with JIS-B0601:2001, a cutoff λc of 2.5 mm, and an evaluation length of 12.5 mm.

The lower limit of the peel strength of the glass plate 16 and the resin layer 17 is preferably 100 gf/cm, and more preferably 120 gf/cm. If the peeling strength is less than the lower limit, there is a problem that, for example, when the light guide body 12 is formed by cutting the laminated body after laminating the glass plate 16 and the resin layer 17, the glass plate 16 and the resin layer 17 are formed. It is easy to peel off from the cut portion. On the other hand, the upper limit of the peeling strength of the glass plate 16 and the resin layer 17 is not particularly limited, and may be, for example, 300 gf/cm. In addition, the "peel strength" refers to the peeling adhesive strength measured at a peeling speed of 100 mm/min in accordance with JIS-K6854-2:1999 "Binder-Peel Strength Test Method, Part 2: 180-degree peeling".

The plurality of concave portions 19 function as a light scattering portion that scatters incident light toward the surface side. As shown in FIGS. 3 and 4, each of the recesses 19 is formed in a substantially circular shape in plan view. Further, each of the recesses 19 is formed to face the surface side, and the diameter is gradually reduced. The shape of the concave portion 19 is not particularly limited, and may be a hemispherical shape, a semi-elliptical shape, a conical shape, a truncated cone shape or the like. Among them, the shape of the concave portion 19 is preferably a hemispherical shape or a semi-elliptical shape. By making the concave portion 19 hemispherical or semi-elliptical, the formability of the concave portion 19 can be improved, and the light incident on the concave portion 19 can be well scattered.

The plurality of recesses 19 do not penetrate the glass sheet 16. That is, the bottoms of the plurality of concave portions 19 are located on the side of the back surface side of the surface of the resin layer 17. As described above, the concave portion 19 of the light guide body 12 can be easily and reliably formed by not allowing the plurality of concave portions 19 to penetrate the glass plate 16. Further, according to this configuration, since the plurality of concave portions 19 can be formed on the resin layer 17, the resin layer 17 can be laminated on the glass plate 16, so that the light guide body 12 can be easily manufactured.

As shown in FIG. 3, it is preferable that the arrangement pattern of the plurality of concave portions 19 is formed such that the density gradually decreases from one end side to the other end side. In particular, it is more preferable that the arrangement pattern of the plurality of concave portions 19 is formed such that the density of the edge from the edge opposite to the light source 13 side toward the light source 13 side gradually decreases. By forming the plurality of concave portions 19 in this manner, the light scattering ratio in the vicinity of the light source 13 can be suppressed and the light scattering ratio of the portion separated from the light source 13 can be increased, so that the surface uniformity of the emitted light can be improved. For example, by keeping the size of each concave portion 19 substantially uniform and adjusting the number of the plurality of concave portions 19, the density of the plurality of concave portions 19 depending on the distance from the light source 13 can be adjusted.

The lower limit of the average depth L (see (a) of FIG. 4) of the concave portion 19 is preferably 1 μm, more preferably 2 μm, still more preferably 4 μm. On the other hand, the upper limit of the average depth L of the concave portion 19 is preferably 10 μm, more preferably 9 μm, still more preferably 7 μm. If the average depth L of the concave portion 19 is smaller than the lower limit, there is a problem that the light scattering function cannot be sufficiently obtained. On the other hand, if the average depth L of the concave portion 19 exceeds the upper limit, there is a problem that luminance unevenness occurs.

The lower limit of the average diameter D (refer to (b) of FIG. 4) of the concave portion 19 is preferably 10 μm, more preferably 12 μm, still more preferably 15 μm. On the other hand, the upper limit of the average diameter of the concave portion 19 is preferably 50 μm, more preferably 40 μm, still more preferably 30 μm. If the average diameter D of the concave portion 19 is smaller than the lower limit, there is a problem that the light scattering function cannot be sufficiently obtained. On the other hand, if the average diameter D of the concave portion 19 exceeds the upper limit, there is a problem that luminance unevenness occurs.

The ridge portion 20 is continuously formed from the flat surface of the resin layer 17. As shown in FIGS. 3 and 4, the raised portion 20 is formed in a substantially annular shape in plan view so as to surround the concave portion 19. The light guide body 12 can easily and reliably prevent the vicinity of the concave portion 19 and the concave portion 19 from being disposed on the back side of the light guide body 12 by forming the raised portion 20 so as to surround the concave portion 19 in a substantially annular shape in plan view. The reflection sheet 14 is in close contact. Therefore, the light guide body 12 can suppress unevenness in brightness due to incidence of light scattered by the concave portion 19 on the adhering portion of the light guide body 12 and the reflection sheet 14.

Preferably, the top of the ridge 20 is curved. By bending the top of the ridge portion 20, the light guide body 12 can improve the performance of preventing damage to the surface of the reflection sheet 14 disposed on the back side.

Preferably, the ridge 20 is formed in a continuous manner with the recess 19. Specifically, it is preferable that the raised portion 20 protrudes toward the back side from the lower end of the concave portion 19, and it is more preferable that the inner side surface of the raised portion 20 is smoothly connected to the formation surface of the concave portion 19. By forming the raised portion 20 and the concave portion 19 continuously, it is possible to improve the function of suppressing unevenness in brightness caused by light scattered by the concave portion 19.

The lower limit of the average height H (refer to (a) of FIG. 4) of the ridge portion 20 is preferably 0.1 μm, more preferably 0.3 μm, still more preferably 0.5 μm. On the other hand, the upper limit of the average height H of the ridge portion 20 is preferably 5 μm, more preferably 4 μm, still more preferably 3 μm. When the average height H of the raised portion 20 is smaller than the lower limit, there is a problem that the light guide body 12 and the reflection sheet 14 disposed on the back side of the light guide body 12 are in contact with each other at a portion other than the raised portion 20, and as a result, The reflection sheet 14 is not sufficiently suppressed from being damaged. Further, if the average height H of the ridge portion 20 is smaller than the lower limit, there is a problem that the light guide body 12 cannot be sufficiently prevented from being in close contact with the reflection sheet 14 disposed on the back side of the light guide body 12, The light incident on the adhering portion of the light guide body 12 and the reflection sheet 14 causes unevenness in brightness. On the other hand, if the average height H of the ridges 20 exceeds the upper limit, there is a problem in that the tips of the plurality of ridges 20 are sharpened to prevent the surface of the reflection sheet 14 disposed on the back side of the light guide body 12 from being sharpened. The performance that causes damage is reduced.

Preferably, the height of the plurality of ridges 20 is uniform. The upper limit of the coefficient of variation of the height H of the plurality of raised portions 20 is preferably 0.2, more preferably 0.1, still more preferably 0.05. If the coefficient of variation of the height H of the plurality of raised portions 20 exceeds the upper limit, there is a problem that the heights of the plurality of raised portions 20 become uneven, and the load is biased toward the raised portion 20 having a high height, thereby generating a pair of reflecting sheets. 14 caused damage. Further, the lower limit of the coefficient of variation of the height H of the plurality of raised portions 20 is not particularly limited, and may be, for example, zero. Further, the "variation coefficient" of the height H of the plurality of raised portions 20 is a value obtained by dividing the standard deviation of the height of any of the ten raised portions 20 by the average height.

The lower limit of the average width W (refer to (b) of FIG. 4) of the ridge portion 20 is preferably 1 μm, more preferably 3 μm, still more preferably 5 μm. On the other hand, the upper limit of the average width W of the ridge portion 20 is preferably 15 μm, more preferably 12 μm, still more preferably 10 μm. When the average width W of the ridge portion 20 is smaller than the lower limit, there is a problem in that the tip end of the ridge portion 20 is sharpened, and the performance of damaging the surface of the reflection sheet 14 disposed on the back side of the light guide body 12 is prevented from being lowered. On the other hand, if the average width W of the ridge portion 20 exceeds the upper limit, there is a problem that the abutment area of the ridge portion 20 and the reflection sheet 14 disposed on the back side of the light guide body 12 becomes large, and is incident on the The light in the abutting portion causes uneven brightness.

The lower limit of the height ratio (H/W) of the average height H to the average width W of the ridge portion 20 is preferably 0.05, more preferably 0.06, still more preferably 0.08. On the other hand, the upper limit of the height ratio (H/W) of the average height H and the average width W of the ridge portion 20 is preferably 0.5, more preferably 0.45, still more preferably 0.4. If the height ratio (H/W) of the average height H of the ridge portion 20 to the average width W is smaller than the lower limit, there is a problem in that the ridge portion 20 and the reflection sheet 14 disposed on the back surface side of the light guide body 12 are in contact with each other. The joint area becomes large, and unevenness in brightness is caused by light incident on the abutting portion. On the other hand, if the height ratio (H/W) of the average height H of the ridge portion 20 to the average width W exceeds the upper limit, there is a problem in that the tip end of the ridge portion 20 is sharpened to prevent the pair of the light guide body 12 from being disposed. The surface of the reflection sheet 14 on the back side is degraded in performance.

The lower limit of the ratio (W/D) of the average width W of the ridge portion 20 to the average diameter D of the concave portion 19 is preferably 0.1, more preferably 0.2, still more preferably 0.3. On the other hand, the upper limit of the ratio (W/D) of the average width W of the ridge portion 20 to the average diameter D of the concave portion 19 is preferably 1, more preferably 0.8, still more preferably 0.6. When the ratio (W/D) is less than the lower limit, there is a problem in that the effect of preventing the light guide body 12 from being in close contact with the reflection sheet 14 disposed on the back side of the light guide body 12 is insufficiently obtained. On the other hand, if the ratio (W/D) exceeds the upper limit, there is a problem in that the abutment area of the ridge portion 20 and the reflection sheet 14 disposed on the back side of the light guide body 12 becomes large, and is incident on the object. The light of the abutting portion causes uneven brightness.

(adhesive layer)

The binder constituting the binder layer 18 is not particularly limited, and examples thereof include a hot-melt adhesive and a photocurable adhesive. Examples of the hot-melt adhesive include an ethylene-vinyl acetate copolymer (EVA), a polyester, a polyamide, a thermoplastic polyurethane, and a polyolefin. Examples of the photocurable adhesive include an acrylic ultraviolet curable adhesive, an epoxy ultraviolet curable adhesive, and the like.

The lower limit of the average thickness of the adhesive layer 18 is preferably 5 μm, more preferably 7 μm, still more preferably 10 μm. On the other hand, the upper limit of the average thickness of the adhesive layer 18 is preferably 50 μm, more preferably 40 μm, still more preferably 30 μm. If the average thickness of the adhesive layer 18 is less than the lower limit, there is a problem that the adhesion between the glass plate 16 and the resin layer 17 is lowered. On the other hand, if the average thickness of the adhesive layer 18 exceeds the upper limit, there is a problem that the thinning requirement of the light guide body 12 is violated.

The lower limit of the refractive index of the adhesive layer 18 is preferably 1.45, more preferably 1.46, still more preferably 1.48. On the other hand, the upper limit of the refractive index of the adhesive layer 18 is preferably 1.6, more preferably 1.58, still more preferably 1.55. If the refractive index of the adhesive layer 18 is out of the above range, there is a problem that the difference in refractive index between the adhesive layer 18 and the resin layer 17 and the glass plate 16 becomes large, and it is difficult to control the light incident on the light guide body 12.

(light source)

The light source 13 is disposed such that the irradiation surface faces (or abuts) the end surface of the light guide body 12. In particular, it is preferable that the light source 13 is disposed such that the irradiation surface faces (or abuts) the end surface of the glass plate 16. A wide variety of light sources can be used as the light source 13, and for example, a light emitting diode (LED) can be used. Specifically, as the light source 13, a light source obtained by arranging a plurality of light-emitting diodes along the end surface of the light guide body 12 can be used.

(A reflective sheet)

The reflection sheet 14 is disposed on the back side of the light guide body 12 so as to be in contact with the plurality of raised portions 20 formed on the back surface of the light guide body 12 . The reflection sheet 14 reflects the light emitted from the back side of the light guide body 12 toward the surface side. The reflection sheet 14 is obtained by dispersing a filler in a white sheet obtained by using a base resin such as polyester, and by depositing a metal such as aluminum or silver on the surface of a film formed of polyester to obtain specular reflectance. Improved mirrors, etc.

(optical sheet)

The optical sheet 15 has an optical function such as diffusion or refraction of light incident from the back side. Examples of the optical sheet 15 include a light-diffusing sheet having a light diffusing function, and a ruthenium sheet having a refractive function of refracting light toward the normal direction side.

<Method of Manufacturing Light Guide>

The method for manufacturing the light guide body 12 includes a step of forming a glass plate 16 and a step of forming a resin layer having a plurality of concave portions on one surface and recessed toward the other surface side, and a plurality of raised portions present a step of projecting toward the one surface side around the plurality of concave portions; and a step of adhering the other surface of the resin layer to the glass plate 16.

(glass plate forming process)

The glass plate forming step can be carried out by a known method such as an overflow down method, a down hole drawing method, a floating method, a roll out method, or a re-introduction method.

(Resin layer forming process)

For example, the resin layer forming step described above can be carried out by the following method.

(a) an injection molding method of injecting a resin layer forming material in a molten state into a molding die having a plurality of concave portions and an inverted shape of a plurality of raised portions existing around the concave portion;

(b) a method of transferring a shape by reheating a sheet body composed of a material for forming a resin layer and sandwiching the sheet body between a molding die having the inverted shape and a metal plate or a roll;

(c) a method of using an extrusion molding method by supplying a resin layer forming material in a molten state to a T mold and extruding the forming material from an extruder and a T die to form a sheet, The sheet is sandwiched between a molding die having the inverted shape and a metal plate or a roll, thereby transferring the shape;

(d) a casting method (solution casting method) which melts a resin layer forming material in a solvent to form a fluid solution (coating), and causes the solution to flow into a molding die having the inverted shape to cause a solvent evaporation;

(e) a method of filling an uncured active energy ray-curable resin into a molding die having the inverted shape and irradiating an active energy ray such as ultraviolet rays;

(f) Using a molding die having an inverted shape having only a plurality of concave portions, by forming a plurality of concave portions on one surface of the sheet body by the same method as the above (a) to (e), using photolithography and etching a method of forming a plurality of ridges around a plurality of recesses on one side of the sheet;

(g) cutting one surface of a sheet body made of a resin layer forming material by using a superhard cutter head, a diamond cutter head, an end mill, or the like to form a plurality of concave portions and a plurality of raised portions existing around the concave portion method.

(forming die)

As described above, as the molding die, the following molding die is used:

(i) a molding die having a plurality of concave portions arranged in a predetermined pattern on the surface and an inverted shape of a plurality of ridge portions existing around the concave portion, or

(ii) A molding die having an inverted shape in which a plurality of concave portions arranged in a predetermined pattern are provided on the surface.

(Manufacturing method of a molding die using a master mold)

The molding die of the above (i) can be produced by using a mother die having a plurality of concave portions arranged in a predetermined pattern on the surface and a plurality of raised portions existing around the plurality of concave portions.

As a manufacturing method of the master mold, for example,

(A) a method of irradiating a surface of a substrate forming a master mold with laser light while forming the plurality of concave portions and the plurality of raised portions,

(B) A method of cutting the surface of the base material forming the master mold by using a superhard cutter head, a diamond cutter head, an end mill, or the like, and simultaneously forming the plurality of concave portions and the plurality of ridge portions.

The material for forming the master mold produced by the method of the above (A) is, for example, a metal such as SUS. On the other hand, as a material for forming the master mold produced by the method of the above (B), in addition to a metal such as SUS, a relatively hard synthetic resin such as polycarbonate or acrylic resin may be mentioned.

Further, when the laser irradiation is performed, the portion irradiated by the laser is melted. As a result, when the concave portion is formed, the molten material is deposited around the concave portion to form a raised portion. On the other hand, when the cutting is performed, the base material of the portion to be cut is deposited around the concave portion formed by the cutting to form a ridge portion. The depth and diameter of the concave portion, the height, width, shape, and the like of the raised portion are adjusted in accordance with the irradiation of the laser, the strength of the cutting, the angle, the diameter, and the like. Further, in this manner, by depositing the molten material around the concave portion, it is easy to form the raised portion so as to surround the concave portion.

Further, the laser for forming the plurality of concave portions and the plurality of raised portions to be irradiated onto the surface of the mother mold is not particularly limited, and examples thereof include carbon dioxide laser, carbon monoxide laser, semiconductor laser, YAG (yttrium aluminum garnet) laser, and the like. . Among them, a carbon dioxide laser having a wavelength of from 9.3 μm to 10.6 μm is suitable for forming a fine shape. Examples of the carbon dioxide laser include a lateral atmospheric pressure excitation (TEA) type, a continuous oscillation type, and a pulse oscillation type.

(Manufacturing method of molding die)

A method for producing a molding die using the master mold includes: a plating layer forming step (S1) of forming a plating layer on a surface of the master mold by electroforming, the master mold having a plurality of concave portions arranged in a predetermined pattern and a plurality of ridges present around the plurality of recesses, the plating layer having an inverted shape of the master mold on a surface thereof; and a step of peeling the plating layer from the master mold (S2). Further, examples of the material for forming the molding die in the case of using the master mold include metals such as nickel, gold, silver, copper, and aluminum.

For example, in the plating bath, the metal nickel is used as an anode, the master mold is used as a cathode, and the plating is performed, and a plating layer is deposited on the surface of the master mold to perform a plating layer forming step (S1).

The plating layer deposited on the surface of the master mold in the plating layer forming step (S1) is peeled off from the master mold to perform a plating peeling step (S2). Further, in order to increase the strength of the plating layer peeled off from the master mold, the plating layer peeling step (S2) may further include a step of reinforcing the plating layer with a reinforcing member.

(Manufacturing method of a molding die that does not use a master mold)

The molding die of the above (ii) can be manufactured without using a master mold. As a method of producing the molding die of the above (ii), for example, an inverted shape in which a plurality of concave portions are formed on the surface of the base material constituting the molding die by photolithography and etching can be mentioned. Further, in this case, as a material for forming the molding die, a relatively hard synthetic resin such as polycarbonate or acrylic resin can be used.

(adhesion process)

The other side of the resin layer obtained in the resin layer forming step can be adhered to one surface of the glass sheet 16 obtained in the glass sheet forming step by the adhesive constituting the adhesive layer 18, and the pasting can be performed. Process.

<advantage>

In the light guide body 12, the resin layer 17 is laminated on the back side of the glass sheet 16, and the resin layer 17 has a plurality of ridges 20 projecting toward the back side on the back surface, so that the light guide body 12 is disposed at The other members on the back side of the light guide body 12 are abutted by a plurality of raised portions 20 so as to be scattered. Therefore, it is possible to suppress the light guide body 12 from being in close contact with other members disposed on the back side thereof. Further, in the light guide body 12, since the resin layer 17 has a plurality of concave portions 19 recessed toward the surface side on the back surface, the light guide body 12 can illuminate the light incident on the plurality of concave portions 19 toward the surface side. scattering. In particular, since the ridge portion 20 is present around the concave portion 19, the adhesion between the concave portion 19 and the concave portion 19 can be appropriately prevented, so that the light guide body 12 can well prevent the light scattered by the concave portion 19 The resulting brightness is uneven. Further, since the glass plate 16 has excellent light guiding properties, the light guide body 12 can achieve high luminance.

In general, when the vicinity of the concave portion of the light guide body is in close contact with another member disposed on the back surface side of the light guide body, the light guide body and the other members are easily and firmly bonded by the presence of the concave portion. On the other hand, since the raised portion 20 is disposed close to the concave portion 19, the light guide body 12 can easily and reliably prevent the close contact in the vicinity of the concave portion 19.

The light guide body 12 has a glass plate 16 as compared with the conventional light guide plate containing a synthetic resin as a main component, and can suppress bending. Therefore, the light guide body 12 can be suitably used for a liquid crystal display device that promotes a large screen. Further, since the adhesive layer 18 is laminated on the back surface of the glass sheet 16 in the light guide body 12, even when the glass sheet 16 is broken, the expansion of the crack can be suppressed by the adhesive layer 18. Further, since the adhesive layer 18 is laminated on the back surface of the glass sheet 16 in the light guide body 12, the breakage of the glass sheet 16 can be prevented by the adhesive layer 18.

Since the backlight unit 11 includes the light guide body 12, it is possible to suppress adhesion to other members disposed on the back side of the backlight unit 11. Further, by allowing the ridge portion 20 to exist around the concave portion 19, the backlight unit 11 can well prevent unevenness in brightness caused by light scattered by the concave portion 19. Further, since the glass plate 16 has excellent light guiding properties, the backlight unit 11 can achieve high luminance.

Since the liquid crystal display device 1 includes the backlight unit 11, it is possible to suppress unevenness in luminance as described above and to achieve high luminance.

According to the method of manufacturing a light guide for a backlight unit, the light guide body 12 capable of suppressing luminance unevenness and achieving high luminance can be easily and reliably manufactured.

[Second Embodiment]

(adhesion prevention sheet)

The adhesion preventing sheet 26 of Fig. 5 is provided with an adhesion preventing portion that is adhered to another optical sheet to prevent adhesion of the optical sheet. Specifically, the adhesion preventing sheet 26 is adhered to the back surface of the glass sheet as in the first embodiment, and adhesion of the back surface of the glass sheet can be prevented.

The adhesion preventing sheet 26 is provided with a base material layer 17 having the adhesion preventing portion. The base material layer 17 has a plurality of ridge portions 20 as the adhesion preventing portion on the back surface, and has a plurality of concave portions 19 disposed around the ridge portion 20. The structure of the raised portion 20 and the recessed portion 19 is the same as that of the first embodiment, and thus the description thereof is omitted. In addition, the material, the average thickness, the refractive index, and the like of the base material layer 17 are also the same as those of the resin layer 17 of the first embodiment, and thus the description thereof is omitted.

The adhesion preventing sheet 26 includes an adhesive layer 27 laminated on the surface of the base material layer 17. The adhesive layer 27 has a viscosity. The adhesive layer 27 can be formed using a known adhesive resin such as an acrylic resin or a urethane resin. Further, as the binder layer 27, a substance to which a tackifier is added to the adhesive resin is preferably used. Further, in addition to the known adhesive resin, a binder layer may be formed by mixing a thermoplastic resin such as a high-pressure method low-density polyethylene, an elastomer such as a synthetic rubber or a natural rubber, a binder such as a terpene resin or a petroleum resin, or the like. 27. The average thickness of the adhesive layer 27 is not particularly limited, and may be, for example, 10 μm or more and 40 μm or less.

The adhesion preventing sheet 26 is provided with a release sheet 28 that is peelably laminated on the surface of the adhesive layer 27. The release sheet 28 has a substrate layer such as polyethylene terephthalate, polyethylene naphthalate or the like, polyethylene, polypropylene, polymethylpentene A synthetic resin such as a polyolefin such as polyolefin or nylon 6, a vinyl resin such as polyvinyl chloride, an acrylic resin such as polymethyl methacrylate, or a cellulose resin such as polycarbonate, cellophane or cellulose acetate is used as a main component.

The release sheet 28 may be composed only of the base material layer. However, in order to improve the mold release property with the adhesive layer 27, a release layer may be provided on the lamination surface side laminated with the adhesive layer 27. Examples of the main component of the release layer include an anthracene resin, a melamine, a fluorinated polymer, and a synthetic resin. Examples of the synthetic resin include a melamine resin, a urea resin, a polyurethane, a polyester, a phenol resin, an epoxy resin, and an amino alkyd resin.

The average thickness of the release sheet 28 is not particularly limited, and may be, for example, 20 μm or more and 2 mm or less.

<advantage>

The adhesion preventing sheet 26 is adhered to the glass plate to form the resin layer 17 of the light guide body 12 of the first embodiment laminated on the back side of the glass sheet. That is, the light guide body 12 is obtained by adhering the adhesion preventing sheet 26 to a glass plate, and the light guide body 12 is provided with a glass 16 plate and a resin layer 17 laminated on the back side of the glass plate 16, the resin The layer 17 has a plurality of concave portions 19 on the back surface and is recessed toward the front surface side, and a plurality of raised portions 20 existing around the plurality of concave portions 19 and protruding toward the back side. Therefore, the adhesion preventing sheet 26 is adhered to the glass plate 16, and unevenness in brightness can be suppressed and high luminance can be achieved.

[Third embodiment]

(light guide)

The light guide 21 of FIG. 6 is used in place of the light guide 12 of the backlight unit of FIG. The light guide body 21 emits light incident from the end surface substantially uniformly from the surface. The light guide body 21 is formed in a plate shape (non-wedge shape). Further, the light guide body 21 is formed in a substantially square shape in plan view. The light guide body 21 is provided with a glass plate 16 and a resin layer 22 laminated on the back side of the glass plate 16. The glass plate 16 and the resin layer 22 are bonded by the adhesive layer 18. The light guide body 21 has the same structure as the light guide body 12 of FIG. 2 except for the structure of the resin layer 22. Therefore, only the resin layer 22 will be described below.

(resin layer)

The resin layer 22 has a plurality of concave portions 19 on the back surface and is recessed toward the front surface side, and a plurality of raised portions 20 are present around the plurality of concave portions 19 and protrude toward the back side. Further, the resin layer 22 has a plurality of convex portions 23 which are disposed in a region of the back surface in which the plurality of raised portions 20 are not present, in a dispersed manner. The resin layer 22 has an adhesion preventing portion on the back surface. Specifically, the resin layer 22 has a plurality of ridge portions 20 and a plurality of convex portions 23 as the adhesion preventing portions. In addition, since the plurality of concave portions 19 and the plurality of raised portions 20 are the same as those of the light guide body 12 of FIG. 2, the same reference numerals will be given, and the description thereof will be omitted.

The resin layer 22 has flexibility. By making the resin layer 22 flexible, the light guide body 21 can suppress damage to other members disposed on the back side of the light guide body 21. The main component of the resin layer 22 may be the same as the main component of the resin layer 17 of the light guide body 12 of Fig. 2 . Further, the resin layer 22 may contain the same additive as the resin layer 17 of the light guide body 12 of FIG. The average thickness and refractive index of the resin layer 22 may be the same as those of the resin layer 17 of the light guide body 12 of Fig. 2 .

The plurality of convex portions 23 prevent the light guide body 21 from being in close contact with other members disposed on the back side of the light guide body 21. The plurality of convex portions 23 are continuously formed from the flat surface of the resin layer 22. As shown in FIG. 7, the convex portion 23 is formed in a substantially circular shape in plan view. Further, the top of the convex portion 23 is curved. The shape of the convex portion 23 is preferably a hemispherical shape or a semi-elliptical shape. By making the shape of the convex portion 23 into a hemispherical shape or a semi-elliptical shape, the formability of the convex portion 23 can be improved, and the performance of preventing damage to the surface of other members disposed on the back side of the light guide body 21 can be improved. As shown in FIG. 6, as the arrangement pattern of the plurality of convex portions 23, it is preferable that the density gradually increases from one end side to the other end side. In particular, as the arrangement pattern of the plurality of convex portions 23, it is preferable that the density of the edge from the end edge on the side opposite to the light source side to the light source side gradually increases.

The plurality of convex portions 23 are disposed such that the total density of the plurality of raised portions 20 and the plurality of convex portions 23 on the entire back surface of the resin layer 22 is substantially uniform.

The total thickness of the ridge portion 20 and the convex portion 23 on the back surface of the resin layer 22 has a lower limit of density, preferably 40 pieces/mm2, more preferably 60 pieces/mm ² , still more preferably 80 pieces/mm ² . On the other hand, as the total of the ridge portion 20 and the convex portion 23 on the back surface of the resin layer 22, there is an upper limit of the density, preferably 500 / mm ² , more preferably 400 / mm ² , still more preferably 300 /mm ² . If the total density of the ridge portion 20 and the convex portion 23 is less than the lower limit, there is a problem in that the light guide body 21 cannot be appropriately prevented from being disposed on the entire surface of the back surface of the light guide body 21 The other parts on the back side are in close contact. On the other hand, when the total density of the ridge portion 20 and the convex portion 23 exceeds the upper limit, the possibility of damage on the surface of the other member disposed on the back side of the light guide body 21 becomes large. In addition, the total density of the ridge portion 20 and the convex portion 23 means that the number of the ridge portions 20 and the convex portions 23 in the field of view observed by magnifying 1000 times in the laser microscope is measured and the value calculated using the field of view area is used. . Further, when a plurality of ridges 20 are present around one recess 19, the ridges 20 are combined into one.

The lower limit of the average height of the convex portions 23 (the average height from the back surface average interface of the resin layer 22) is preferably 2 μm, more preferably 3 μm, still more preferably 4 μm. On the other hand, the upper limit of the average height of the convex portion 23 is preferably 7 μm, more preferably 6 μm, still more preferably 5 μm. If the average height of the convex portion 23 is less than the lower limit, there is a problem that the other members disposed on the back side of the light guide body 21 cannot be sufficiently prevented from being in close contact with each other. On the other hand, when the average height of the convex portion 23 exceeds the upper limit, there is a problem that the surface of the other member disposed on the back surface side of the light guide body 21 is damaged by the contact with the convex portion 23 .

It is preferable that the heights of the plurality of convex portions 23 are uniform. The upper limit of the coefficient of variation of the height of the plurality of convex portions 23 is preferably 0.2, more preferably 0.1, still more preferably 0.05. If the coefficient of variation of the height of the plurality of convex portions 23 exceeds the upper limit, there is a problem that the heights of the plurality of convex portions 23 become uneven, and the load is biased toward the convex portion 23 having a high height, thereby causing the arrangement to be The surface of the other member on the back side of the light guide 21 is damaged. In addition, the lower limit of the coefficient of variation of the height of the plurality of convex portions 23 is not particularly limited, and may be, for example, zero.

The lower limit of the height ratio of the average height to the average diameter (the average diameter on the back surface average interface of the resin layer 22) of the convex portion 23 is preferably 0.05, more preferably 0.07, still more preferably 0.1. On the other hand, as the upper limit of the height ratio, it is preferably 0.5, more preferably 0.3, still more preferably 0.2. If the height ratio is smaller than the lower limit, there is a problem that the contact area between the light guide body 21 and another member disposed on the back side of the light guide body 21 becomes large, and the incident is caused by the incident The light in the connected portion causes uneven brightness. On the other hand, if the height ratio exceeds the upper limit, there is a problem in that the tip end of the convex portion 23 is sharpened, and the performance of damaging the surface of other members disposed on the back side of the light guide body 12 is prevented from being lowered.

The lower limit of the height ratio of the average height of the convex portion 23 to the average height of the ridge portion 20 is preferably 0.5, more preferably 0.65, still more preferably 1. On the other hand, as the upper limit of the height ratio, it is preferably 7, more preferably 5, still more preferably 3. If the height ratio is outside the range, there is a problem that the difference between the average height of the convex portion 23 and the average height of the raised portion 20 becomes large, and the load is biased toward the plurality of convex portions 23 or the plurality of raised portions 20 On the other hand, damage is caused to the surface of other members disposed on the back side of the light guide body 21.

The method of forming the plurality of convex portions 23 is not particularly limited, and a plurality of concave portions 19 and a plurality of raised portions 20 may be simultaneously formed, or a plurality of convex portions may be additionally formed after the plurality of concave portions 19 and the plurality of raised portions 20 are formed. twenty three. As a method of forming the plurality of convex portions 23 after forming the plurality of concave portions 19 and the plurality of raised portions 20, for example, a known printing method such as screen printing or inkjet printing; and a photolithography method and an etching method are used. Method, etc. In addition, the plurality of convex portions 23 may be formed of a material different from the resin layer 22, but is preferably formed of the same material as the resin layer 22.

<advantage>

The resin layer 22 has a plurality of concave portions 19 that are recessed toward the front side and a plurality of raised portions 20 that are present around the plurality of concave portions 19 and protrude toward the back side, and are disposed so as to be dispersed in a non-existent manner. Since the plurality of convex portions 23 in the region of the plurality of raised portions 20, the light guide body 21 can more appropriately prevent the light guide body 21 from being in close contact with other members disposed on the back side thereof. Further, since the light guide body 21 has the plurality of convex portions 23, it is possible to more appropriately prevent the surface of other members disposed on the back side of the light guide body 21 from being damaged. Therefore, the light guide body 21 can more reliably prevent light from entering the adhering portion of the light guide body 21 and other members disposed on the back side thereof, and other members disposed on the back side of the light guide body 21 The damaged portion of the surface causes uneven brightness.

[Other embodiments]

Further, in the light guide, the backlight unit, the liquid crystal display device, the adhesion preventing sheet, and the method for producing the light guide for the backlight unit of the present invention, various modifications and improvements can be made in addition to the above embodiments. For example, the light guide may include a glass plate and a resin layer laminated on the back side of the glass plate, and may have other layers than the glass plate and the resin layer. As such another layer, for example, another resin layer laminated on the surface side of the glass plate or the like can be given. Further, the light guide body may be directly laminated with a resin layer on a glass plate.

The light guide body may have a biconvex shape or the like on the surface, so that the emitted light can be controlled. Further, in order to suppress unevenness in brightness in the vicinity of the light source, the light guide body may have a plurality of slits such as a V shape or a trapezoid shape formed continuously or at a predetermined interval from the end surface on the light source side. The arrangement pattern of the plurality of ridges is not particularly limited. As the arrangement pattern of the plurality of ridges, for example, in the case of the two-side optical backlight unit in which the light sources are disposed at opposite side ends of the light guide body, the density may be from the both side ends toward the center density A configuration that gradually grows larger. Further, the plurality of convex portions are disposed in a region where a plurality of raised portions are not present as dispersed dots, and the arrangement pattern thereof is not particularly limited.

The planar shape of the plurality of concave portions is not limited to a substantially circular shape, and may be a polygonal shape or the like. Further, the planar shape of the plurality of raised portions is not limited to a substantially annular shape, and may be a polygonal ring shape or the like. Further, the plurality of ridges need not necessarily be arranged to completely surround the outer circumference of the recess. Fig. 8 illustrates shapes other than the above-described embodiments of the plurality of recesses and the plurality of ridges. In (a) of FIG. 8, a part of the annular annular portion 32 is disposed around the concave portion 31 having a circular shape in plan view. In (b) of FIG. 8, the square-shaped raised portion 42 is disposed around the concave portion 41 having a circular shape in plan view. In (c) of FIG. 8 , one raised portion 52 having an annular shape in plan view is disposed to surround the plurality of concave portions 51 . In (d) of FIG. 8 , the ridge portion 62 having an annular shape in plan view is disposed around the rectangular recess 61 in plan view. Even in the case where the concave portion and the ridge portion are disposed as described above, the light guide body can suppress unevenness in brightness and can achieve high luminance.

The molding die of (ii) can be manufactured by electroforming using a master having a plurality of recesses on the surface. As a method of producing the master mold having a plurality of concave portions on the surface, for example, a method of forming a plurality of concave portions on the surface of the base material constituting the master mold by photolithography and etching can be mentioned.

In the case where the resin layer is produced by an extrusion molding method in which a forming material in a molten state is supplied to a T mold and the forming material is extruded from an extruder and a T die to form a sheet, a sandwich may be used. One of the pair of press rolls of the extruded sheet body serves as a molding die having a plurality of concave portions and an inverted shape of a plurality of raised portions existing around the concave portions. As a method of forming the inverted shape on the surface of one of the pressure rolls, for example, a plating layer having a plurality of concave portions arranged in a predetermined pattern on the surface and a plurality of raised portions existing around the concave portions may be laminated on the plating layer. A method of pressing the surface of the roll, a method of forming the inverted shape by laser cutting or cutting on the surface of the press roll.

In the second embodiment, the adhesion preventing sheet is provided with the adhesive layer and the release sheet, but the adhesion preventing sheet of the present invention does not necessarily have to have the adhesive layer and the release sheet. For example, it is also within the scope of the present invention to form the adhesion preventing sheet only by the base material layer of the second embodiment and to adhere the base material layer to another optical sheet, for example, by a binder or the like.

The backlight unit does not necessarily have to be disposed on the back side of the light guide body. For example, the surface of the top plate disposed on the back side of the light guide body may be formed as a polished reflective surface, and the reflective surface may be replaced by the reflective surface. Tablet use. By forming the top surface of the top plate as the rearmost surface of the backlight unit in this manner, the backlight unit can remove the reflection sheet and can contribute to thinning.

As the liquid crystal display device, in addition to the above-described notebook computer, various configurations such as a portable terminal such as a mobile phone terminal such as a smart phone or a portable information terminal such as a tablet terminal, a desktop computer, and a thin television can be used. Further, even when the liquid crystal display device is configured as a notebook computer, the thickness of the casing of the notebook computer need not necessarily be 21 mm or less.

Industrial applicability

As described above, the light guide of the present invention can be applied to a high-quality liquid crystal display device because it can suppress luminance unevenness and can achieve high luminance.

Although the present invention has been disclosed above in the foregoing embodiments, it is not intended to limit the invention. It is within the scope of the invention to be modified and modified without departing from the spirit and scope of the invention. Please refer to the attached patent application for the scope of protection defined by the present invention.

1‧‧‧Liquid display device, ultra-thin computer
2‧‧‧Operation Department
3‧‧‧Liquid display
4‧‧‧LCD panel
5‧‧‧LCD housing
6‧‧‧ top board
7‧‧‧Surface bearing parts
8‧‧‧Hinges
9‧‧‧Operating parts housing
11‧‧‧Backlight unit
12, 21‧‧‧ Light guide
13‧‧‧Light source
14‧‧‧reflector
15‧‧‧ optical film
16‧‧‧ glass plate
17‧‧‧Resin layer, substrate layer
18‧‧‧Binder layer
19, 31, 41, 51, 61‧‧ ‧ recess
20, 32, 42, 52, 62‧ ‧ ridges
22‧‧‧ resin layer
23‧‧‧ convex
26‧‧‧Adhesive film
27‧‧‧Binder layer
28‧‧‧ peeling film
101‧‧‧Backlight unit
102‧‧‧Light source
103‧‧‧Light guide plate
104‧‧‧ optical film
105‧‧‧reflector
106‧‧‧Light diffuser
107‧‧‧ Picture

1 is a perspective view of a liquid crystal display device according to an embodiment of the present invention, wherein (a) of FIG. 1 shows a state in which the liquid crystal display portion is opened, and (b) of FIG. 1 shows a liquid crystal display portion is turned off. status. 2 is a schematic end view of a backlight unit of the liquid crystal display device of FIG. 1. 3 is a schematic rear view of the light guide body of the backlight unit of FIG. 2. 4 is an enlarged schematic view showing a concave portion and a raised portion of the light guiding body of FIG. 3, wherein (a) of FIG. 4 is an end view, and (b) of FIG. 4 is a rear view. FIG. 5 is a schematic end view of an adhesion preventing sheet according to an embodiment of the present invention. Fig. 6 is a schematic end view of a light guide body of a different form from the light guide of the backlight unit of Fig. 2; Fig. 7 is a schematic rear view of the light guide of Fig. 6. Fig. 8 is a schematic rear view showing a concave portion and a raised portion which are different from the concave portion and the raised portion of the light guiding member of Figs. 3 and 6; 9 is a perspective view of a conventional edge-lit backlight unit.

11‧‧‧Backlight unit

12‧‧‧Light guide

13‧‧‧Light source

14‧‧‧reflector

15‧‧‧ optical film

16‧‧‧ glass plate

17‧‧‧ resin layer

18‧‧‧Binder layer

19‧‧‧ recess

20‧‧‧ Uplift

Claims (11)

A light guide body for a plate-shaped backlight unit that emits light incident from an end surface from a surface, the light guide body comprising: a glass plate; and a resin layer laminated on the back side of the glass plate The resin layer has a plurality of concave portions and a plurality of raised portions on the back surface, and the concave portions are recessed toward the surface side, and the raised portions are located around the concave portions and protrude toward the back side. The light guide body according to claim 1, wherein the resin layer has an average thickness of from 5 μm or more to 50 μm or less. The light guide body of claim 1, wherein the recesses have an average depth (L) of from 1 μm or more to 10 μm or less. The light guide body according to claim 1, wherein the recesses have an average diameter (D) of 10 μm or more and 50 μm or less. The light guide according to claim 1, wherein the ridges have an average height (H) of 0.1 μm or more and 5 μm or less. The light guide according to claim 1, wherein the raised portions are formed in a substantially annular shape in a plan view so as to surround the concave portions, and the average width (W) of the raised portions is 1 μm or more and 15 μm or less. The light guide according to claim 6, wherein the height ratio (H/W) of the average height (H) to the average width (W) of the raised portions is 0.05 or more and 0.5 or less. An edge-lit backlight unit comprising: the light guide according to any one of claims 1 to 7; and a light source that illuminates the end surface of the light guide. A liquid crystal display device comprising the edge-lit backlight unit of claim 8. An adhesion preventing sheet which is adhered to a glass plate for preventing adhesion of the back surface of the glass sheet, wherein the adhesion preventing sheet has a plurality of concave portions and a plurality of ridge portions on the back surface, and the concave portions are recessed toward the surface side, The ridges are located around the recesses and protrude toward the back side. A method for producing a light guide for a backlight unit, wherein the light guide for a backlight unit is a plate-shaped light guide for a backlight unit that emits light incident from an end surface from a surface, and the manufacturing method includes a step of forming a resin layer The resin layer has a plurality of recesses and a plurality of ridges on one side, the recesses being recessed toward the other side, the ridges being located around the recesses and protruding toward one side; and the resin layer The other side is adhered to the glass plate.