KR101034313B1 - Light guide plate for surface light source device and backlight unit using same - Google Patents

Abstract

According to the present invention, a light guide plate including an incident surface on which light is incident from a lamp arranged along a predetermined axis, an exit surface on which the incident light is emitted, and a rear surface facing the exit surface, wherein the rear surface has a plurality of micro-prism patterns engraved therein. The unit cells of are distributedly arranged, wherein a cross-section in which at least one of the unit prisms of the micro-prism pattern is perpendicular to the ridge direction is composed of four or more light reflection surfaces, and the prism array axis and the ramp formed by the ridge direction of the micro-prism pattern Provided is a light guide plate for a surface light source device, characterized in that arranged in a cross angle of the arrangement axis.
The light guide plate for the surface light source device of the present invention has not only high front luminance but also excellent uniformity of luminance and no moiré phenomenon. In the case of using the backlight unit, it is possible to reduce the use of the optical sheet stacked on the light guide plate, thereby making it possible to slim down the liquid crystal display module and simplify the manufacturing process and lower the manufacturing cost. In addition, the light guide plate can freely control the viewing angle to allow the manufacture of a backlight unit having excellent visibility at various angles.

Description

Light Guiding Plate for Surface Light Source Device and Back Light Unit using the Same}

The present invention relates to a light guide plate for a surface light source device and a backlight unit using the same, and more particularly, a plurality of unit cells engraved with a micro prism pattern are disposed on a rear surface of an emission surface, and at least one of the unit prisms of the micro prism pattern is disposed. The cross section perpendicular to the ridge direction is composed of four or more light reflection surfaces, and the intersection angle between the prism array axis formed by the ridge direction of the micro prism pattern and the array axis of the lamp is disposed at an angle. A light guide plate and a backlight unit using the same.

A light guide plate is generally applied to a liquid crystal display and used as a means for applying light to an LCD module which is a passive element. That is, light is guided and diffused from the light source disposed at the side or the bottom of the light guide plate, for example, the LED lamp, and applied to the LCD module stacked on the surface side.

In addition, by forming a backlight by stacking a diffusion sheet, a prism sheet, or the like on the surface side of the light guide plate from which the light is emitted, the luminance amount and the viewing angle of the light are controlled.

However, in recent years, efforts have been made to reduce the number of components and thus simplify the structure or reduce the cost by implementing various components added to the light guide plate in the light guide plate itself.

For example, Patent Literature 1 discloses a light guide plate having a diffuse reflection portion composed of fine unevenness on either the lower surface or the surface of the light guide plate, and having a reflecting plate for controlling the amount of diffuse reflection such as a transparent ink. According to such a configuration, a light guide plate having good diffuse reflection efficiency and brightness can be manufactured simply and quickly. However, the proposal only mentions controlling the amount of light through diffuse reflection and attachments. In addition, a manufacturing method using a pattern of intaglio engraving on the back of the light guide plate is generally utilized, which has a small increase in brightness compared to a light guide plate of a printing method, but still requires a large amount of optical sheets. There is a problem of cost increase.

In order to solve such a problem, there has been attempted to develop a technology for dramatically increasing luminance by controlling an optical path through pattern molding of a triangular structure or the like on the light guide plate. For example, Patent Document 2 discloses a light guide plate provided with a triangular reflector on the back surface of a light exit surface. However, in this technique, the triangular back reflecting surface has a characteristic of exhibiting non-uniform optical distribution with excellent brightness but insufficient luminance uniformity because it reflects in a specific direction in a limited direction. There is a problem that moiré phenomenon caused by combination of prism shapes occurs when using a low prism.

In addition, while using the LED lamp as a light source, the problem of brightness uniformity due to the formation of the dark portion between the LED lamp and the lamp, and the problem of moiré generation by the combination of the prism structure on the back of the light guide plate and the prism sheet used as the optical sheet continues. have. Therefore, the present inventors moire by improving the front luminance distribution by arranging the ridge direction of the prism pattern formed on the back surface of the light emitting plate or the micro prism pattern formed on the back unit cell at a right angle with the direction in which light is incident. It was confirmed that the phenomenon can be suppressed and the present invention has been completed.

Japanese Patent Laid-Open No. Hei 6-118247 Republic of Korea Patent No. 580890

An object of the present invention is to provide a light guide plate for a surface light source device that not only has high front luminance but also excellent uniformity of luminance.

Another object of the present invention is to provide a backlight unit using the light guide plate for the surface light source device.

A light guide plate for a surface light source device according to an embodiment of the present invention is a light guide plate comprising an incident surface to which light is incident from a lamp disposed along a predetermined axis, an exit surface to which the incident light is emitted, and a rear surface facing the exit surface. The plurality of unit cells engraved with a micro prism pattern are distributedly disposed on the rear surface, and a cross section perpendicular to the ridge direction of the micro prism pattern includes four or more light reflection surfaces; And a crossing angle between the prism array axis formed in the ridge direction of the micro prism pattern and the array axis of the lamp is disposed at a right angle.

At least one of the unit prisms has two first reflecting surfaces that are symmetrical with respect to the vertical line passing through the vertex and extend from the vertex, and the left and right symmetry with respect to the vertical line passing through the vertex and end of the first reflecting surface. It is preferable to have two second reflecting surfaces, which extend from and extend to the bottom of the unit cell.

The vertex angle θ1 of the first reflection surface and the vertex angle θ2 of the second reflection surface are different from each other, and may be 60 to 120 °, respectively.

The vertex angle θ1 of the first reflective surface may be smaller or larger than the vertex angle θ2 of the second reflective surface.

It is preferable that the height of the first reflecting surface and the height of the second reflecting surface are 1: 0.5 to 1: 2.

The longest axis of the unit cell is preferably 1 ~ 2,000um.

Preferably, the intersection angle between the microprism array axis on the unit cell and the array axis of the lamp is 0.1 to 10 °.

According to another aspect of the present invention, a light guide plate for a surface light source device includes a light incident plate on which a light is incident from a lamp disposed along a predetermined axis, an emission surface on which the incident light is emitted, and a rear surface facing the emission surface. The plurality of unit cells engraved with a micro prism pattern are distributedly disposed on the rear surface, and a cross section perpendicular to the ridge direction of the micro prism pattern includes four or more light reflection surfaces; An intersection angle between a prism array axis formed in the ridge direction of the micro prism pattern and the array axis of the lamp is disposed at an opposite angle; A lenticular pattern is formed on the exit surface.

The ridgeline direction of the lenticular pattern is preferably parallel to the incident direction of light.

The lenticular pattern is preferably a pitch of 10 ~ 300um.

The light guide plate for the surface light source device of the present invention has not only high front luminance but also excellent uniformity of luminance and no moiré phenomenon. In the case of using the backlight unit, it is possible to reduce the use of the optical sheet stacked on the light guide plate, thereby making it possible to slim down the liquid crystal display module and simplify the manufacturing process and lower the manufacturing cost. In addition, the light guide plate can freely control the viewing angle to allow the manufacture of a backlight unit having excellent visibility at various angles.

1 is a perspective view of a light guide plate 100 for a surface light source device according to an embodiment of the present invention.
Figure 2 is a partially enlarged view of the rear surface 140 of the light guide plate for the surface light source device according to an embodiment of the present invention.
3 is a schematic diagram of the unit prisms 152, 153, and 154 of the micro prism pattern formed on the unit cell 160 of the light guide plate 100.
4A to 4D are schematic views showing the shape of the unit cell 160 formed on the rear surface 140 of the light guide plate for the surface light source device according to the embodiment of the present invention.
5 is an exemplary view showing an arrangement direction of unit cells.
6 is a perspective view of a light guide plate for a surface light source device according to another embodiment of the present invention.
7A-7D illustrate a pattern that may be formed on an exit surface in another embodiment of the present invention.

Hereinafter, a light guide plate for a surface light source device according to an embodiment of the present invention will be described with reference to the drawings.

1 is a perspective view of a light guide plate 100 for a surface light source device according to an embodiment of the present invention. In FIG. 1, the light guide plate 100 for a surface light source device of the present invention includes an incident surface 120 through which light is incident from a lamp 110 disposed along a predetermined axis, an exit surface 130 through which the incident light is emitted, and the In the light guide plate including a rear surface 140 facing the exit surface, the plurality of unit cells 160 in which the micro-prism pattern 150 is engraved is disposed on the rear surface 140.

The light guide plate 100 starts the path of the light toward the exit surface 130 through the action of reflection, refraction, diffraction, etc., starting from the lamp 110 and entering the light guide plate 100 through the entrance surface 120. As a function of changing the material, a polymer material having a high visible light transmittance, high strength, and low deformation and breakage is used. Examples of the polymer used for this purpose include acrylic resins, polycarbonates, cyclic olefin copolymers and the like, and acrylic resins are preferred, and polymethyl methacrylate is particularly preferred.

The lamp 110 functions as a light source. Not only a linear light source but also a lamp in which point light sources are linearly arranged. It is common to use a light emitting diode (LED) or a cold cathode tube (CCFL).

In the light guide plate 100 for the surface light source device according to the embodiment of the present invention, the crossing angle θ of the prism array axis 151 formed in the ridge direction of the micro-prism pattern and the array axis 111 of the lamp is at an angle. It is characterized in that the arrangement. In the present invention, the offset angle means that the angle of intersection (θ) between the prism array axis 151 and the array axis 111 of the lamp is not 0 degrees, that is, the prism array axis 151 and the array axis of the lamp ( 111) is not parallel. By the arrangement of the angles as described above, the luminance distribution of the light guide plate may be further increased. It is preferable that the said crossing angle (theta) is 0.1-10 degrees. If the crossing angle θ does not reach 0.1 °, the luminance uniformity cannot be expected. If the crossing angle θ exceeds 10 °, the luminance uniformity can be secured, but the luminance itself decreases. By the crossing angle in the above range, the LED light having excellent straightness generates a reflection having a gradient of intensity by the prism structure, thereby gradually reducing the luminance deviation compared to the dark region where the LED light does not pass, thereby uniforming the brightness of the light guide plate. This will be improved.

The plurality of unit cells 160 having the micro prism pattern 150 engraved therein are disposed on the rear surface 140 of the light guide plate 100. FIG. 2 is a partially enlarged view showing only a few unit cells 160 engraved with the prism pattern 150 formed on the rear surface 140. In the unit cell 160 illustrated in FIG. 2, the unit cell 160 is engraved on the rear surface 140 in an engraved manner, but the unit cell 160 is not necessarily limited thereto and may be engraved on the back surface 140. In addition, the bottom surface of the micro prism pattern 150 on the unit cell 160 may be the same surface as the rear surface 140. In this case, the shape of the unit cell 160 is provided only by the shape of the micro-prism pattern 150.

3 is a schematic diagram of the unit prisms 152, 153, and 154 of the micro prism pattern formed on the unit cell 160 of the light guide plate 100. In FIG. 3, at least one of the unit prisms 152, 153, and 154 of the micro-prism pattern 150 has a cross section perpendicular to the ridge direction and includes four or more light reflection surfaces. In particular, when at least one of the unit prisms has four light reflecting planes, two first reflecting planes 156 and 156` which are symmetrical with respect to the vertical line passing through the vertices and extend from the vertices, and pass through the vertices. Two second reflecting surfaces 158 and 158 ', which are symmetrical with respect to a vertical line and extend from ends of the first reflecting surfaces 156 and 156` to extend to the bottom surface 157 of the unit cell 160. It has a form.

The vertex angles θ1 of the first reflection surfaces 156 and 156 'and the vertex angles θ2 of the second reflection surfaces 158 and 158' are different from each other, and preferably 60 to 120 degrees. When the prism angle is less than 60 ° and the angle exceeds 120 °, the brightness of the vertex decreases due to an increase in the side lobe, and the vertex angle θ1 of the first reflection surface may be smaller than the vertex angle θ2 of the second reflection surface. It can be big. However, it is preferable in terms of uniformity that the vertex angle θ2 of the second reflective surface is larger than the vertex angle θ1 of the first reflective surface.

The height H1 of the first reflection surface and the height H2 of the second reflection surface are preferably 1: 0.5 to 1: 2. If it is less than 1: 0.5, the viewing angle is narrowed, and if it is more than 1: 2, there is a problem that luminance decreases due to an increase in side lobes. The unit prism pitch is preferably 1 to 100um. If the pitch of the prism is less than 1 μm, the light reflection effect is insufficient and the luminance increase effect is not. If the prism is more than 100 μm, the total thickness of the light guide plate is affected, resulting in an increase in the overall thickness of the backlight unit.

4 is a schematic diagram showing the shape of the unit cell 160 in which the micro-prism pattern 150 is formed. That is, the unit cell 160 may be circular (Fig. 4a), elliptical (4b), square (4c) or hexagonal (4d), and is not necessarily limited to the illustrated form, for example, Of course, it is possible to modify any number of rectangles, diamonds, or a combination thereof. In the case where the shape of the unit cell 160 is circular, the diameter of the unit cell 160 is preferably 1 to 2,000 um. If the unit cell size does not reach 1um, the light reflection effect is insignificant, and if it exceeds 2,000um, uniform control of the brightness between the LED lamp and the LED lamp is impossible. In other words, the uniformity control between the lamp and the lamp is also controlled through the distribution of the unit cells.In the case of unit cells exceeding 2,000um, the density of the unit cells per unit area is increased to a certain level by being limited by the distribution adjustment. It is an inhibition. On the other hand, when the shape of the unit cell is elliptical, the long axis and / or short axis thereof are polygonal, and the length of one side may be within the above range.

5 is an exemplary view showing an arrangement direction of unit cells. In the present invention, the cell 160 of the stage may be arranged such that the ridge direction of the micro-prism pattern 150 formed in the unit cell 160 coincides between all the unit cells, as shown in FIG. 5A. In addition, as shown in FIG. 5B, a group of unit cells and another group of unit cells may be arranged so that directions of the respective ridges cross each other. In this case, the alignment of the ridges may be zigzag between the unit cells. In addition, although not illustrated as a diagram, the ridge lines of the prism pattern may be arranged in a zigzag form in one unit cell.

The distribution of the unit cells 160 formed on the rear surface 140 may be adjusted by adjusting the density of the unit cells 160 having the same diameter. That is, the density of the unit cell 160 decreases closer to the side on which light is incident, and may be configured to have a distribution having a gradient that increases as far away. In addition, the distribution of the unit cells may be adjusted by changing the size of the unit cell. That is, the unit cell 160 may be configured to have a distribution having a gradient that is smaller as the size of the unit cell 160 is closer to the side on which light is incident, and becomes larger as it is farther.

6 is a perspective view of a light guide plate 200 for a surface light source device according to another embodiment of the present invention. The light guide plate 200 for a surface light source device according to the second embodiment of the present invention includes an incident surface 220 through which light is incident from a lamp 210 arranged along a predetermined axis, and an exit surface 330 through which the incident light is emitted. And a rear surface 240 facing the exit surface 230, wherein the plurality of unit cells 260 having the micro prism pattern 250 engraved therein are distributedly disposed on the rear surface, and the ridge lines of the micro prism pattern are disposed. The cross section perpendicular to the direction is composed of four or more light reflection surfaces; An intersection angle [theta] of the prism array axis 251 formed in the ridge direction of the micro prism pattern and the array axis 211 of the lamp is arranged at an angle; A pattern is formed on the exit surface.

The lenticular pattern 270 disposed on the exit surface is a structure that controls the path of the light emitted from the light guide plate at the outermost angle, and is a secondary means of controlling the contrast between the curved line and the dark line. That is, due to the phase separation function of the surface lenticular pattern 270, the image of the bright portion is divided, the area of the dark portion is gradually smaller. The emission angle of the light reflected from the rear surface 240 is controlled by the lenticular pattern 270 to adjust the light distribution having excellent visibility and vertical luminance.

Figure 7 illustrates a pattern that may be formed on the exit surface in the second embodiment of the present invention. In Fig. 6, the pattern formed on the exit surface is a circular semicircular lenticular pattern, as shown in Fig. 7A. In addition, the exit surface of the light guide plate 200 according to the third embodiment of the present invention has a parabolic lens (Fig. 7B) and a prism. It may be a round prism lens pattern (Fig. 7c) having a vertex angle, and an independent hemispherical lens array (Fig. 7d).

In the third embodiment of the present invention, when the pattern 270 formed on the exit surface is a lenticular pattern, a parabolic lens pattern, or a round prism lens pattern, the direction formed by the ridge line of the pattern is parallel to the light incident from the lamp 210. (Or perpendicular to the arrangement of the lamps).

The pitch of the lenticular pattern 270 is preferably 10 ~ 300um. If the pitch is less than 10 um, the outermost specific surface area for producing the lens function is reduced, and the brightness enhancement function is lowered. If the pitch is more than 300 um, the image quality is deteriorated due to moiré generation with the liquid crystal device.

On the other hand, in the third embodiment of the present invention, the configuration other than the pattern of the exit surface described above, for example, the back unit cell, the prism pattern formed in the unit cell, the crossing angle and the like are the same as those described in the first embodiment.

The light guide plate for a surface light source device according to the present invention is used as a backlight assembly including a protective film having a light source installed on one side of an incident surface of the light guide plate and having a diffusion function stacked on an exit surface of the light guide plate.

The light guide plate according to each embodiment of the present invention can be produced using an injection method. In this case, a light guide plate is produced by processing each pattern of the back surface and the exit surface in the injection mold, and injecting the polymer material into the mold. In another production method, a plate serving as a base material of the light guide plate may be prepared, and the plate may be manufactured through pattern processing on the plate. The method of processing the pattern on the plate may be a stamping method by pressing, heating, an imprint method using a UV resin and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples. This is for explaining the present invention more specifically, but the scope of the present invention is not limited to these Examples.

<Examples>

1. Manufacturing of light guide plate

PMMA was used as a raw material to produce a PMMA plate of 3.5mm thickness, 20cm in width, 10cm in length. The PMMA plate utilized an extrusion method, and the extruder used a conventional single screw extruder.

The upper surface of the plate is formed with a lenticular pattern 270, the lenticular pattern 270 was produced in the shape of pitch 200um, height 40um.

2. Mold manufacturing for pattern processing

Copper plating was performed on the cold alloy tool steel (SKD-11) to produce a mold disc of copper thickness of 30 um. Lathe machining was carried out with a diamond bite on the original mold disk to produce a 200um diameter unit cell, 80 ° between the first reflecting surface, and 120 ° between the second reflecting surface (pentagon), and unit of prism pitch 20um. The cell was processed. The distribution of unit cells was arranged by adjusting the density at the same diameter. That is, the density of the unit cell decreases as the light source is incident to the light source, and is composed of a distribution having a gradient increasing as far as possible. In this experiment, the unit cell density per unit area (10x10mm) at the light source side was 10%, the unit cell density per unit area (10x10mm) at the center was 70%, and the gradient change per 0.2cm distance from the light source side to the center. And placed.

3. Cell molding and light guide plate production

In order to form the cell pattern on the lower surface side of the prepared plate, a pre-prepared pattern mold was mounted on a press molding equipment, and press molded at a molding temperature of 200 ° C., a press time of 1 minute, and a press pressure of 10 kg / m ² to complete the light guide plate. At this time, the crossing angles of the array axis of the prism pattern formed on the unit cell and the lamp array axis were 0.5, 2, and 5 °, respectively.

Comparative Example 1

A light guide plate was manufactured in the same manner as in Example, except that the prism formed in the unit cell was a triangular prism, the crossing angle θ was 0 °, and the lenticular pattern was not provided on the emission surface.

Comparative Example 2

In the prism formed in the unit cell, the light guide plate was manufactured in the same manner as in the embodiment in the form of a five-angle prism and an intersecting angle θ of 0 ° and a lenticular pattern provided on the emission surface.

Comparative Example 3

The light guide plate was manufactured in the same manner as in the embodiment in that the prism formed in the unit cell was provided with a triangular prism, a cross angle θ of 0.5 °, and a lenticular pattern on the emission surface.

<Comparative Example 4>

In the prism formed in the unit cell, the light guide plate was manufactured in the same manner as in the embodiment, in the form of a five-angle prism and an intersection angle θ of 0.5 °, and no lenticular pattern on the emission surface.

<Evaluation>

1. Front luminance measurement

Measuring equipment: Topcon BM-7

Measuring method: The light guide plate was mounted on a backlight equipped with a 32-inch LED lamp, and the 32-inch area was divided into nine equal parts, and the luminance of each center portion was measured. The luminance was measured by arithmetic average of nine points.

2. Uniformity Measurement

Measuring equipment: Topcon BM-7

Measuring method: The 32-inch LED lamp was mounted on the backlight, and the 32-inch area was divided into 30 pieces. The luminance of each center part was measured, and the uniformity was calculated by calculating the ratio of the minimum value to the maximum value.

The evaluation results for the above Examples and Comparative Examples are summarized in Table 1 below.

division Crossing angle (°) Prism Pattern
shape Appearance
Lenticular Front luminance (cd / m ² ) Uniformity
(%) Example 1 0.5 Pentagram Prism U 3520 70 Example 2 2 Pentagram Prism U 3500 72 Example 3 5 Pentagram Prism U 3000 75 Comparative Example 1 0 Triangular prism radish 3450 55 Comparative Example 2 0 Pentagram Prism U 3550 61 Comparative Example 3 0.5 Triangular prism U 3550 63 Comparative Example 4 0.5 Pentagram Prism radish 3400 64

As in the results of Examples 1 and 2 and Comparative Example 2 of Table 1, the light guide plate having an angle of 0.5 ° and 2 ° between the microprism array axis and the lamp array axis has similar luminance as compared with Comparative Example 2 having an angle of 0 ° of the array axis. It can be seen that the uniformity is improved by 15 to 18% in the value. In addition, as shown in the results of Example 1 and Comparative Example 3, when the pattern shape of the micro-prism of the back unit cell is pentagonal, an improvement in uniformity of about 11% was observed compared to the case of a triangle.

In addition, in Example 1 having a lenticular pattern compared to Comparative Example 4 having no lenticular on the surface, it was confirmed that the luminance and luminance uniformity were simultaneously improved.

In conclusion, in comparison with Comparative Example 1, which has a cross angle of 0 ° and a lenticular without a lenticular surface having a triangular pattern, the angle between the dot prism array axis and the lamp array axis is 0.5 °, and the back micro prism has a pentagon shape. In the case of the light guide plate having a lenticular shape on the surface, it was confirmed that the luminance and the uniformity of the luminance were simultaneously improved.

The above results indicate that the optical path control is possible through the control of the cross angle and the control of the microprism shape, and in particular, it is confirmed that the luminance improvement and the uniformity control effect by the exit surface lenticular pattern can be obtained.

The light guide plate for the surface light source device of the present invention and the backlight unit including the same may be used for various purposes for light emission control in a device using an LED lamp such as an LCD and an illumination device.

100, 200 ... Light guide plate 110 ... Lamp
111 ... Lamp array axis 120 ... Incident plane
130 ... exit 140 ... rear
150 ... micro-prism pattern 151 ... ridge axis
160 ... unit cell 370 ... exit surface pattern

Claims (12)

In the light guide plate including an incident surface to which light is incident from a lamp disposed along a predetermined axis, an emitting surface to which the incident light is emitted, and a rear surface facing the emitting surface,
A plurality of unit cells in which a micro prism pattern is engraved is disposed on the rear surface, and a cross section perpendicular to the ridge direction of the micro prism pattern includes four or more light reflecting surfaces;
And a crossing angle between the prism array axis formed in the ridge direction of the micro prism pattern and the array axis of the lamp is disposed at a right angle. The device of claim 1, wherein at least one of the unit prisms is symmetrical with respect to a vertical line passing through a vertex and two first reflection surfaces that are symmetric with respect to a vertical line passing through the vertex, and symmetrical to the left and right with respect to a vertical line passing through the vertex. The light guide plate for the surface light source device, characterized in that it has two second reflection surface which extends from the end of the first reflection surface to the bottom surface of the unit cell. The light guide plate according to claim 2, wherein the vertex angle (θ1) of the first reflection surface and the vertex angle (θ2) of the second reflection surface are different from each other, and are 60 to 120 degrees, respectively. 4. The light guide plate according to claim 3, wherein the vertex angle θ1 of the first reflecting surface is smaller than the vertex angle θ2 of the second reflecting surface. 4. The light guide plate according to claim 3, wherein the vertex angle θ1 of the first reflection surface is larger than the vertex angle θ2 of the second reflection surface. The light guide plate according to claim 2, wherein the height of the first reflecting surface and the height of the second reflecting surface are 1: 0.5 to 1: 2. The light guide plate according to claim 1, wherein the longest axis of the unit cell is 1 to 2000 um. The light guide plate of claim 1, wherein an intersection angle between the microprism array axis on the unit cell and the array axis of the lamp is 0.1 to 10 °. In the light guide plate including an incident surface to which light is incident from a lamp disposed along a predetermined axis, an emitting surface to which the incident light is emitted, and a rear surface facing the emitting surface,
A plurality of unit cells in which a micro prism pattern is engraved is disposed on the rear surface, and a cross section perpendicular to the ridge direction of the micro prism pattern includes four or more light reflecting surfaces;
An intersection angle between a prism array axis formed in the ridge direction of the micro prism pattern and the array axis of the lamp is disposed at an opposite angle;
The lenticular pattern is formed on the exit surface; the light guide plate for a surface light source device. The light guide plate of claim 9, wherein a ridge direction of the lenticular pattern is parallel to an incident direction of light. The light guide plate of claim 9, wherein the lenticular pattern has a pitch of 10 to 300 um. The light guide plate according to any one of claims 1 to 11; A lamp provided on one side of an incident surface of the light guide plate; And a protective film having a diffusion function stacked on an exit surface of the light guide plate.

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