JP2012233984A - Fine structure sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fine structure sheet that enables manufacturing of a light guide plate capable of reducing linear poor appearance generated by interference of light due to fine irregularities formed on a smooth surface included in an optical deflection element, and a rib-like structure when light is incident from the edge surface of the light guide plate.SOLUTION: A fine structure sheet comprises: a first rib-like structure 3 continuously formed on one surface of a resin sheet; a second rib-like structure 4a formed on the other surface at a constant interval; and a smooth surface 4b formed between the rib-like structures 4a on the other surface. In the smooth surface 4b, a first ten-point average roughness in a drawing direction of the second rib-like structure 4a is larger than a second ten-point average roughness in a direction perpendicular in plan view to a drawing direction of the second rib-like structure 4a, and the average roughness of the first ten points is 0.25 μm or less.

Description

  The present invention relates to a microstructure sheet, and is a material of a light guide plate used for illumination light path control as a backlight of a liquid crystal display device or the like, for example. Here, the light guide plate refers to one obtained by cutting the microstructure sheet into a desired size.

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

  On the other hand, in an edge light type lighting device, a plurality of cold-cathode tubes and LEDs are arranged on an end face of a translucent plate called a light guide plate. In general, incident light incident from the end surface of the light guide plate is efficiently applied to a surface (that is, a light deflection surface) provided on the side opposite to the exit surface of the light guide plate (that is, the surface facing the image display element). A light deflection element that leads well to the exit surface is formed. Currently, the light deflection element formed on the light deflection surface is generally printed with white ink in the form of dots (for example, Patent Document 1), but the light incident on the white dots diffuses almost omnidirectionally. Since it is reflected, the light extraction efficiency to the exit surface side of the light guide plate is low. Also, light absorption by white ink cannot be ignored.

  Therefore, recently, a method of forming a microlens on the light deflection surface of a light guide plate by an inkjet method, a method of forming a light deflection element on a light guide plate by a laser ablation method, and the like have been proposed. Unlike the case where white ink is used, the light guide plate formed by these methods uses reflection, refraction, and transmission due to the difference in refractive index between the resin forming the light guide plate and the air around the light guide plate. Therefore, light absorption hardly occurs. Therefore, it is possible to obtain a light guide plate having a higher light extraction efficiency than when white ink is used.

However, the formation of the light deflection element by the above-described ink jet method or laser ablation method is formed in a separate process after the light guide plate is formed into a flat plate, as in the case of white ink printing, so the number of manufacturing steps is not reduced. Rather, the takt time is longer than that of the white ink printing process, and the initial cost of the equipment is increased, which may increase the cost.
Therefore, a method has been proposed in which the light guide plate is formed by an injection molding method or an extrusion molding method, and the light deflection element is directly formed at the time of extrusion (for example, Patent Document 2). In this method, since the light deflection element is formed simultaneously with the formation of the light guide plate, the number of processes is reduced, and the cost can be reduced.

However, when manufacturing a light guide plate by the injection molding method, the larger the size of the light guide plate, the higher the pressure required for the injection molding machine. Therefore, the manufacture of a relatively small light guide plate used for mobile phones, notebook computers, etc. However, it is difficult to apply to a large light guide plate used in a television or the like.
On the other hand, the extrusion molding method is a method suitable for manufacturing a large-sized light guide plate, and is basically formed by “Roll to Roll” using a cylindrical roll mold. For example, when an optical deflection element composed of a bowl-shaped structure and a smooth surface is formed by an extrusion method, a groove for forming the bowl-shaped structure and a smooth surface for forming the smooth surface are formed. A roll mold having a curved surface may be used.

  Here, the smooth curved surface formed in the roll mold needs to be processed with high smoothness in consideration of the cylindricity or roundness of the roll mold. However, since it is very difficult to perform surface processing with high smoothness, fine unevenness may be formed on the smooth curved surface. And this fine unevenness | corrugation may be transcribe | transferred by the smooth surface of a light deflection | deviation element when forming a light deflection | deviation element using an extrusion method. For this reason, when light is incident from the end face of the light guide plate, the light interferes with the fine irregularities formed on the smooth surface of the light deflection element and the bowl-shaped structure, and a linear or uneven appearance defect occurs. There was a problem.

JP-A-1-241590 JP 2000-89033 A

  The problem of the present invention is that when light is incident from the end face of the light guide plate, the light is interfered by the fine irregularities formed on the smooth surface and the bowl-shaped structure included in the light deflecting element, and linear or uneven It is an object of the present invention to provide a microstructure sheet capable of obtaining a light guide plate that can reduce the occurrence of poor appearance.

  One aspect of the present invention for solving the above problems is a resin sheet, a plurality of first bowl-shaped structures formed on and adjacent to one surface of the resin sheet, and the one side The other surface on the opposite side of the first surface is formed with a uniform stretching direction at regular intervals, and has the stretching direction that intersects the stretching direction of the first cage structure at a certain angle in plan view. A plurality of second hook-like structures and a smooth surface formed between the second hook-like structures on the other surface, wherein the second hook-like structures are provided on the smooth surface. The first ten-point average roughness (Rz) in the stretching direction is larger than the second ten-point average roughness (Rz) in the direction orthogonal to the stretching direction of the second cage structure in plan view. The first ten-point average roughness (Rz) is 0.25 μm or less.

  Moreover, another aspect of the present invention is a resin sheet, a plurality of ridge-like structures formed adjacent to one surface of the resin sheet and aligned in the extending direction, and on the opposite side of the one surface. A plurality of groove-like structures formed on the other surface with the stretching direction aligned at regular intervals and having the stretching direction intersecting with the stretching direction of the bowl-shaped structure at a constant angle in plan view; A smooth surface formed between the groove-like structures on the surface, wherein the first ten-point average roughness (Rz) in the extending direction of the groove-like structure is the groove. Larger than the second ten-point average roughness (Rz) in a direction orthogonal to the extending direction of the structure in plan view, and the first ten-point average roughness (Rz) is 0.25 μm or less. It is characterized by.

In another aspect of the present invention, an outline of a cross section in a direction orthogonal to the extending direction of the first saddle-shaped structure in a plan view is an arc shape or a square shape, The outline of the cross section in the direction orthogonal to the stretching direction in plan view may be an arc shape or a square shape.
In another aspect of the present invention, an outline of a cross section in a direction orthogonal to the extending direction of the bowl-shaped structure in a plan view is an arc shape or a square shape, and in the extending direction of the groove-shaped structure and a plan view. The outline of the cross section in the orthogonal direction may be an arc shape or a square shape.

Another aspect of the present invention is characterized in that the extending direction of the first cage-like structure and the extending direction of the second cage-like structure are orthogonal to each other in plan view. Also good.
Another aspect of the present invention may be characterized in that an extending direction of the bowl-shaped structure and an extending direction of the groove-shaped structure are orthogonal to each other in plan view.

According to the fine structure sheet, when this is cut into a desired size to form a light guide plate, and light is incident from the end face of the light guide plate, the extending direction of the first hook-like structure and the second hook-like structure Since the extending direction of the body intersects at a certain angle, the incident light is reflected by the second bowl-shaped structure and emitted toward the exit surface side of the light guide plate (that is, the liquid crystal display device side). be able to. For this reason, the light extraction efficiency at the time of emission can be increased as compared with the case where the extending direction of the first hook-shaped structure is parallel to the extending direction of the second hook-shaped structure.
Furthermore, since the incident light does not interfere with the fine unevenness formed on the smooth surface of the light deflection element and the second bowl-shaped structure, it is possible to reduce the occurrence of a linear or uneven appearance defect. .

Similarly, according to the microstructure sheet, when it is cut into a desired size to obtain a light guide plate, and light is incident from the end face of the light guide plate, the extension direction of the bowl-like structure and the extension of the groove-like structure Since the direction intersects at a certain angle, the incident light can be reflected by the groove-like structure and emitted toward the exit surface side of the light guide plate (that is, the liquid crystal display device side). For this reason, the light extraction efficiency at the time of emission can be increased as compared with the case where the extending direction of the ridge-like structure and the extending direction of the groove-like structure are parallel.
Furthermore, since the incident light does not interfere with the fine unevenness formed on the smooth surface of the light deflection element and the groove-like structure, it is possible to reduce the occurrence of a linear or uneven appearance defect.

The figure which shows the microstructure sheet | seat which concerns on 1st embodiment. The figure which shows the surface in which the 2nd bowl-shaped structure and the smooth surface were formed. The figure which shows the manufacturing apparatus of a microstructure sheet. The figure which shows the roll metal mold | die 2a. The figure which shows the roll metal mold | die 2b. FIG. 11 illustrates a liquid crystal display device. The figure which shows the evaluation result of a microstructure sheet. The figure which shows the microstructure sheet | seat which concerns on 2nd embodiment. The figure which shows the microstructure sheet | seat which concerns on 3rd embodiment. The figure which shows the microstructure sheet | seat which concerns on 4th embodiment.

[First embodiment]
(Microstructure sheet)
The microstructure sheet according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing the entire microstructure sheet 5. FIG. 2 is an enlarged view of a surface 1b on which a second bowl-shaped structure 4a and a smooth surface 4b described later are formed. FIG. 3 is a diagram showing a method for manufacturing the microstructure sheet 5. FIG. 4 is a view showing a roll metal fitting 2a used for forming a first flange-like structure 3 to be described later on a resin sheet 5a. FIG. 5 is a view showing a roll metal fitting 2b used for forming a second flange-like structure 4a and a smooth surface 4b described later on the resin sheet 5a. Here, the “resin sheet 5a” refers to a base material used when the microstructure sheet 5 is formed.

  As shown in FIG. 1, the microstructure sheet 5 includes a plurality of first ridge-like structures 3 formed continuously adjacent to one surface. And the extending | stretching direction of each 1st bowl-shaped structure 3 is aligned in the fixed direction. Further, as shown in FIG. 2, the surface 1 b on the side opposite to the surface 1 a on which the first cage structure 3 is formed is formed at a constant interval, and the extending direction of the first cage structure 3 And a plurality of second bowl-shaped structures 4a having extending directions perpendicular to each other in plan view. And the extending | stretching direction of each 2nd bowl-shaped structure 4a is aligned in the fixed direction. Furthermore, each 2nd bowl-shaped structure 4a is formed apart, and the smooth surface 4b is formed between the 2nd bowl-like structures 4a.

As for the shape of the first cage structure 3, for example, the height H1 of the ridge is 50 μm, and the width P1 of the ridge is 150 μm. And the outline of the cross section in the direction orthogonal to the extending | stretching direction of the 1st bowl-shaped structure 3 by planar view is an arc shape, For example, the outline is a semi-ellipse.
The shape of the second ridge-like structure 4a is, for example, a heel height H2 of 25 μm and a ridge width P2 of 25 μm. And the outline of the cross section in the direction orthogonal to the extending | stretching direction of the 2nd bowl-shaped structure 4a by planar view is an arc shape, for example, the outline is a semicircle.

The smoothness of the smooth surface 4b is such that the ten-point average roughness Rz (1) in the direction 22 parallel to the extending direction of the second cage structure 4a is flat with the extending direction of the second cage structure 4a. It is larger than the ten-point average roughness Rz (2) in the direction 23 orthogonal to the view. Further, the ten-point average roughness Rz (1) is 0.25 μm or less.
In addition, although the relationship between the extending direction of the first cage structure 3 and the extending direction of the second cage structure 4a has been described in the case of being orthogonal in a plan view, the present invention is limited to this. For example, it is only necessary to intersect at a certain angle. If the extending direction of the first cage structure and the extending direction of the second cage structure intersect at a certain angle, the light incident on the microstructure sheet 5 (that is, incident light) is the first. 2 so that the incident light can be efficiently guided as compared with the case where the extending direction of the first saddle-shaped structure is parallel to the extending direction of the second saddle-shaped structure. The light can be emitted toward the exit surface side of the light plate (that is, the liquid crystal display device side).

  In addition, although the description has been given of the case of the arcuate shape of the cross section in the direction orthogonal to the extending direction of the first cage structure 3 in plan view, the present invention is not limited to this, for example, a corner It may be a shape. For example, the cross-sectional outline may be triangular. Even in this case, as will be described later in the section of (Evaluation Method of Microstructure Sheet), the same effects as those obtained when the contour of the cross section of the first bowl-shaped structure 3 is arcuate are obtained. Can do.

  In addition, although the description has been given of the case of the arcuate shape of the cross-sectional outline in the direction orthogonal to the extending direction of the second bowl-shaped structure 4a in plan view, the present invention is not limited to this, for example, a corner It may be a shape. For example, the cross-sectional outline may be triangular. Even in this case, as will be described later in the section of (Evaluation Method of Microstructure Sheet), the same effect as that obtained when the contour of the cross section of the second bowl-shaped structure 4a is arcuate is obtained. Can do.

Further, the width of the smooth surface 4b may be constant between the light source side and the side opposite to the light source side, or may be increased as the light source side is narrowed and moved away from the light source side.
In FIG. 1, the first cage structure 3 is described as a linear cage structure in a plan view. However, the present invention is not limited to this. A mold-like structure may be used.

In FIG. 2, the second hook-like structure 4 a is described as a straight hook-like structure in a plan view, but the present invention is not limited to this. A mold-like structure may be used.
As described above, in the case of the fine structure sheet 5, when the fine structure sheet 5 is cut into a light guide plate and light is incident from the end face of the light guide plate, the fine structure formed on the smooth surface of the light deflection element. Since the light does not interfere with the unevenness and the bowl-shaped structure, the occurrence of a linear appearance defect can be reduced.

(Manufacturing method of fine structure sheet)
Next, a method for manufacturing the microstructure sheet 5 will be described with reference to FIG. FIG. 3 shows a manufacturing apparatus 6 for the microstructure sheet 5 using the extrusion forming method. The manufacturing apparatus 6 is a roll mold 2a for forming the first bowl-shaped structure 3 (see FIG. 4). ), A roll mold 2b (see FIG. 5) for forming the second bowl-shaped structure 4a and the smooth surface 4b, and a die 7 for molding the resin into a sheet shape.
First, a thermoplastic polycarbonate resin manufactured by Teijin Kasei Co., Ltd. was blended and melted with a die 7, and a thermoplastic polycarbonate resin (hereinafter referred to as a sheet) was formed by extruding the molten resin from a gap provided in the die 7. Also referred to as a resin sheet.) 5a was obtained.

Next, the microstructure sheet 5 shown in FIG. 1 was obtained by pressing this resin sheet 5a with a roll mold 2a and a roll mold 2b from both sides with a constant pressure. The light guide plate was obtained by cutting the microstructure sheet 5 thus obtained into a desired size.
Hereinafter, the roll mold 2a and the roll mold 2b used for manufacturing the microstructure sheet 5 will be described.
(Roll mold 2a)
As shown in FIG. 4, the roll mold 2a is formed with a plurality of grooves 3a corresponding to the first bowl-shaped structures 3 so as to surround the circumference of the cylindrical member (that is, in the circumferential direction of the cylindrical member). It has a different shape. Each groove 3a is formed adjacent to each other. Further, the extending direction of the grooves 3a is formed linearly along the axial direction of the roll mold 2a, and the extending directions of the respective grooves 3a are aligned.
In addition, although the linear groove | channel 3a is formed in the roll metal mold | die 2a, this invention is not limited to this. For example, instead of the linear groove 3a, a corrugated corrugated structure can be formed on the microstructure sheet 5 by forming corrugated grooves in the roll mold 2a.

(Roll mold 2b)
As shown in FIG. 5, the roll mold 2b is formed with a plurality of grooves 4c corresponding to the second bowl-shaped structures 4a so as to surround the circumference of the cylindrical member (that is, in the circumferential direction of the cylindrical member). And each groove | channel 4c has the shape formed in the fixed space | interval. And this groove | channel 4c is formed in linear form along the axial direction of the roll metal mold | die 2a. Further, a smooth curved surface 4d for forming the smooth surface 4b shown in FIG. 1 is formed between the grooves 4c. And the extending direction of each groove 4c is aligned.

  The ten-point average roughness Rz (1) and the ten-point average roughness Rz (2) on the smooth surface 4b included in the microstructure sheet 5 shown in FIG. 1 are the ten points on the smooth curved surface 4d shown in FIG. It can be arbitrarily adjusted by changing the average roughness Rz (3) and the ten-point average roughness Rz (4). For example, when the roll member 2b is manufactured by polishing a cylindrical member, the ten-point average roughness of the smooth curved surface 4d can be changed by changing the type and processing direction of the polishing grindstone for polishing. Further, the smooth curved surface 4d in which the ten-point average roughness is changed can be formed not only by grindstone polishing but also by buffing or lathe processing.

The plate used for the extrusion forming method is not limited to a roll mold, and a resin sheet transferred from the roll mold may be used as the plate. Even when this resin sheet is used, it can be formed on the microstructure sheet 5.
Moreover, although the linear groove | channel 4c is formed in the roll metal mold | die 2b, this invention is not limited to this. For example, instead of the linear groove 4 c, a corrugated corrugated structure can be formed on the microstructure sheet 5 by forming corrugated grooves in the roll mold 2 b.

(Evaluation method of microstructure sheet)
The microstructure sheet 5 was evaluated using the liquid crystal display device 21 shown in FIG. The liquid crystal display device 21 includes a polarizing plate 11, a liquid crystal panel 12, a polarizing plate 13, a prism film 14, a prism film 15, a diffusion film 16, a light source lamp 17, a lamp reflector 18, a reflection film 19, and a light guide plate 20. .
When the microstructure sheet 5 is evaluated, the light guide plate 20 made from various types of microstructure sheets 5 corresponding to Examples 1 to 6 and Comparative Examples 1 to 3 described later is placed on the liquid crystal display device 21 and visually observed. Thus, the state of unevenness and defects of the microstructure sheet 5 was observed. The arrangement direction of the light guide plate 20 was set so that the extending direction of the second bowl-shaped structure 4 a was parallel to the arrangement of the light source lamps 17.

  In evaluating unevenness and defects of the microstructured sheet 5 that is a material of the light guide plate 20, independent setting items (so-called parameters) are set as ten-point average roughness Rz (1) and ten-point average roughness Rz (2). ), The outline of the cross section in the direction orthogonal to the extending direction of the first cage structure 3, the outline of the cross section in the direction orthogonal to the extension direction of the second cage structure 4a, and the second with respect to the microstructure sheet 5 The five items of the arrangement of the bowl-shaped structures 4a were used. Here, the “independent setting item” refers to a numerical value, shape, or the like that can be set independently (that is, arbitrarily).

The independent setting items and the numerical values or shapes of the microstructure sheets corresponding to Examples 1 to 6 and Comparative Examples 1 to 3 are shown in FIG.
The outline of the cross section in the direction orthogonal to the extending direction of the first bowl-shaped structure 3 is an arc shape with a width P1 of 150 μm and a height H1 of 50 μm in Examples 1-4, 6 and Comparative Examples 1-4 (specifically Is a semi-ellipse). And in Example 5, it is a square shape (specifically, a triangle) whose width P1 is 150 μm and whose height H1 is 75 μm.

The outline of the cross section in the direction orthogonal to the extending direction of the second bowl-shaped structure 4a is an arc shape (specifically, in Example 1-5 and Comparative Examples 1-4 having a width P2 of 50 μm and a height H2 of 25 μm). Is a semicircle). And in Example 6, it is a square shape (specifically, a triangle) with a width P1 of 50 μm and a height H1 of 25 μm.
In Example 4, the 2nd bowl-shaped structure 4a is arrange | positioned with respect to the microstructure sheet | seat 5 at convex shape. On the other hand, Examples 1-3, 5, and 6 and Comparative Examples 1-4 are a groove-shaped structure with respect to the microstructure sheet | seat 35, as shown by 3rd embodiment (refer FIG. 9) mentioned later. 4e is formed (that is, the second bowl-shaped structure 4a is disposed in a concave shape).

(Evaluation result of microstructure sheet)
As shown in FIG. 7, unlike Examples 1 to 6, Comparative Examples 1 and 2 are microstructured sheets in which the ten-point average roughness Rz (2) is larger than the ten-point average roughness Rz (1). . In addition, streak-like appearance defects were confirmed in these fine structure sheets. This is considered to be manifested as a streak-like defect due to the interference of incident light due to the fine irregularities formed on the second bowl-shaped structure 4a and the smooth surface 4b.

Comparative Examples 3 and 4 are microstructured sheets having a ten-point average roughness Rz (1) larger than those in Examples 1 to 6. These fine-structure sheets were confirmed to have streak-like appearance defects. This is presumably because the unevenness formed on the smooth surface 4b is large, so that the transmitted light of the smooth surface 4b becomes non-uniform and appears as uneven defects.
From the above evaluation results, the 10-point average roughness Rz (1) is larger than the 10-point average roughness Rz (2) and the 10-point average roughness Rz (1) satisfies 0.25 μm or less. It has been found that a microstructured sheet with no surface can be produced.

Further, the ten-point average roughness regardless of whether the cross-sectional contours in the direction orthogonal to the extending direction of the first cage structure 3 and the second cage structure 4a are arc-shaped or square-shaped. It was found that by satisfying the relationship between Rz (1) and ten-point average roughness Rz (2), a microstructure sheet having no appearance defect can be produced.
Note that “x” shown in the column of “external appearance defect evaluation result” in FIG. 7 indicates that a streaky or uneven appearance defect has been confirmed, and “◯” indicates that there is no appearance defect.

[Second Embodiment]
FIG. 8 is a view showing the microstructure sheet 25 according to the second embodiment of the present invention. The microstructure sheet 25 includes a resin sheet 8 on which the first cage structure 3 is formed, a resin sheet 9a on which the second cage structure 4a and the smooth surface 4b are formed, the resin sheet 8 and the resin sheet. And an adhesive layer 10 for adhering to 9a. That is, a single microstructure sheet 25 is formed by the resin sheet 8, the resin sheet 9 a, and the adhesive layer 10. Thus, the microstructure sheet 25 has substantially the same structure as the microstructure sheet 5 according to the first embodiment shown in FIG.

  However, the microstructure sheet 5 shown in FIG. 1 is integrally formed by extrusion using the roll mold 2a and the roll mold 2b, whereas the microstructure sheet 25 shown in FIG. The microstructure sheet is formed by bonding the resin sheet 8 on which the first cage structure 3 is formed and the resin sheet 9a on which the second cage structure 4a is formed using the adhesive layer 10. It is different from 5. Therefore, only this different point will be described, and description of other parts will be omitted.

The resin sheet 8 presses the roll mold 2a against the ultraviolet curable resin applied on the transparent substrate, and irradiates the ultraviolet rays from the substrate side, whereby the first cage structure is applied to the ultraviolet curable resin. 3 is obtained, and then the transparent substrate is peeled off.
The resin sheet 9a is also obtained by a method substantially similar to the resin sheet 8, by pressing the roll mold 2b against the ultraviolet curable resin applied on the transparent substrate and irradiating ultraviolet rays from the substrate side, The second cage structure 4a and the smooth surface 4b are formed on the ultraviolet curable resin, and then the transparent substrate is peeled off.
The microstructure sheet 25 shown in FIG. 8 is obtained by bonding the resin sheet 8 and the resin sheet 9a manufactured in this way with the adhesive layer 10 interposed therebetween.

Separately from the above method, for example, a resin sheet 8 in which the first ridge-like structure 3 is formed in advance on one surface is manufactured by an extrusion forming method, and the second ridge-like structure 4a is formed on the ultraviolet curable resin. Thus, the resin sheet 9a may be manufactured, and then the resin sheet 8 and the resin sheet 9a may be bonded to form the microstructure sheet 25. Even in this case, the microstructure sheet 25 can be obtained.
As described above, in the case of the fine structure sheet 25, when the fine structure sheet 25 is cut into a light guide plate, and light is incident from the end face of the light guide plate, the fine structure formed on the smooth surface of the light deflection element. Since the light does not interfere with the unevenness and the bowl-shaped structure, the occurrence of a linear appearance defect can be reduced.

[Third embodiment]
FIG. 9 is a view showing a microstructure sheet 35 according to the third embodiment of the present invention. This fine structure sheet 35 is bonded to the resin sheet 8 on which the first flange-like structure 3 is formed, the resin sheet 9b on which the groove-like structure 4e is formed, and the resin sheet 8 and the resin sheet 9b. Layer 10. That is, a single microstructure sheet 35 is formed by the resin sheet 8, the resin sheet 9 b, and the adhesive layer 10. As shown in FIG. 9, the microstructure sheet 35 has substantially the same structure as the microstructure sheet 25 according to the second embodiment shown in FIG. However, the second cage-like structure 4a shown in FIG. 8 is convex with respect to the microstructure sheet 25 shown in FIG. 8, but the groove-like structure 4e according to the third embodiment is shown in FIG. It differs in that it is concave with respect to the microstructure sheet 35 shown.

In addition, the presence or absence of an appearance defect is determined based on whether the second ridge-like structure 4a (that is, the convex structure) is formed on the microstructure sheet or the groove-like structure 4e (that is, the concave structure). The fact that it is not formed is explained in the above section (Evaluation of microstructure sheet).
As described above, in the case of the fine structure sheet 35, when the fine structure sheet 35 is cut into a light guide plate, and light is incident from the end face of the light guide plate, the fine structure formed on the smooth surface of the light deflection element. Since the light does not interfere with the unevenness and the bowl-shaped structure, the occurrence of a linear appearance defect can be reduced.

[Fourth embodiment]
FIG. 10 is a view showing a microstructure sheet 45 according to the fourth embodiment of the present invention. As shown in FIG. 10, the fine structure sheet 45 has substantially the same structure as the fine structure sheet 5 according to the first embodiment shown in FIG. However, the second ridge-like structure 4a according to the first embodiment is convex with respect to the microstructure sheet 5 shown in FIG. 1, but the groove-like structure 4e according to the fourth embodiment is shown in FIG. It differs in that it is concave with respect to the microstructure sheet 35 shown.

In addition, the presence or absence of an appearance defect is determined based on whether the second ridge-like structure 4a (that is, the convex structure) is formed on the microstructure sheet or the groove-like structure 4e (that is, the concave structure). The fact that it is not formed is explained in the above section (Evaluation of microstructure sheet).
As described above, in the case of the fine structure sheet 45, when the fine structure sheet 45 is cut into a light guide plate and light is incident from the end face of the light guide plate, the fine sheet formed on the smooth surface of the light deflection element. Since the light does not interfere with the unevenness and the bowl-shaped structure, the occurrence of a linear appearance defect can be reduced.

DESCRIPTION OF SYMBOLS 1a The surface 1b in which the 1st bowl-shaped structure is arrange | positioned The surface 2a in which the 2nd bowl-like structure is arranged 2a Roll mold 2b Roll mold 3 The first bowl-shaped structure 3a The first bowl-shaped structure Groove 4a corresponding to 2nd bowl-like structure 4b smooth surface 4c groove 4d corresponding to second bowl-like structure smooth surface 4e corresponding to smooth surface groove-like structure 5 microstructure sheet according to the first embodiment 5a Resin sheet 6 Microstructure sheet manufacturing apparatus 7 Die 8 Resin sheet 9a on which first ridge-like structure is formed Resin sheet 9b on which second ridge-like structure and smooth surface are formed Grooved structure and smooth Surface-formed resin sheet 10 Adhesive layer 11 Polarizing plate 12 Liquid crystal panel 13 Polarizing plate 14 Prism film 15 Prism film 16 Diffusion film 17 Light source lamp 18 Lamp reflector 19 Reflective film 20 Light guide plate 21 Liquid crystal display device 2 A direction parallel to the extending direction of the second bowl-shaped structure 23 A direction 25 orthogonal to the extending direction of the second bowl-shaped structure 25 A microstructure sheet 35 according to the second embodiment A microstructure sheet according to the third embodiment 45 Fine Structure Sheet P1 According to the Fourth Embodiment P1 Width P2 Width H1 １ Height H2 高 Height Rz (1) Ten-point average roughness Rz (2) on smooth surface Ten-point average on smooth surface Roughness Rz (3) Ten-point average roughness Rz (4) on a smooth curved surface Ten-point average roughness on a smooth curved surface

Claims (6)

A resin sheet;
A plurality of first hook-like structures formed on and adjacent to one surface of the resin sheet,
The stretching direction formed on the other surface opposite to the one surface with the stretching direction aligned at a constant interval and intersecting the stretching direction of the first cage structure at a certain angle in plan view A plurality of second bowl-shaped structures having:
A smooth surface formed between the second bowl-shaped structures on the other surface,
In the smooth surface, the first ten-point average roughness (Rz) in the extending direction of the second bowl-shaped structure is the second in the direction perpendicular to the extending direction of the second bowl-shaped structure. The microstructure sheet is characterized by being larger than the ten-point average roughness (Rz) and having the first ten-point average roughness (Rz) of 0.25 μm or less. A resin sheet;
A plurality of bowl-shaped structures formed on and adjacent to one surface of the resin sheet,
A plurality of the extending directions which are formed on the other surface opposite to the one surface so as to align the extending direction at a constant interval and intersect the extending direction of the bowl-shaped structure at a fixed angle in plan view; A grooved structure of
A smooth surface formed between the groove-like structures on the other surface,
In the smooth surface, the first ten-point average roughness (Rz) in the extending direction of the groove-like structure is the second ten-point average roughness in a direction orthogonal to the extending direction of the groove-like structure in plan view. A microstructure sheet characterized by being larger than (Rz) and having the first ten-point average roughness (Rz) of 0.25 μm or less. The outline of the cross section in a direction orthogonal to the extending direction of the first bowl-shaped structure in a plan view forms an arc shape or a square shape,
2. The microstructure sheet according to claim 1, wherein an outline of a cross section in a direction orthogonal to the extending direction of the second bowl-shaped structure in a plan view is an arc shape or a square shape. The outline of the cross section in a direction orthogonal to the extending direction of the bowl-shaped structure in a plan view forms an arc shape or a square shape,
The microstructure sheet according to claim 2, wherein the outline of a cross section in a direction orthogonal to the extending direction of the groove-like structure in a plan view is an arc shape or a square shape.   4. The microstructure according to claim 1, wherein the extending direction of the first cage structure and the extending direction of the second cage structure are orthogonal to each other in plan view. Sheet.   5. The microstructure sheet according to claim 2, wherein an extending direction of the ridge-like structure and an extending direction of the groove-like structure are orthogonal to each other in plan view.

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