TW201409098A - Light guide plate, method for preparing the same, backlight unit including the same, and liquid crystal display including the same - Google Patents

Abstract

A light guide plate, a method for preparing the same, a backlight unit including the same, and a liquid crystal display including the same. The light guide plate includes divided optical patterns to provide outstanding shielding properties to optical sheets including prism sheets and the like when mounted on a backlight unit, can guide uniform output of light emitted from a light source, permits change in height, width, or length of the optical patterns to facilitate adjustment of optical properties including exit angle, and has an adjustable appearance.

Description

Light guide plate, method for preparing the light guide plate, backlight unit including the same, and liquid crystal display including the same Field of invention

The present invention relates to a light guide plate, a method of preparing the light guide plate, a backlight unit including the light guide plate, and a liquid crystal display including the same. More particularly, the present invention relates to a light guide plate comprising separate optical patterns for providing significant shielding properties to an optical sheet, such as a cymbal, when mounted on a backlight unit, for directing emission by a light source. The uniform output of light allows the height, width or length of the optical patterns to be varied to adjust the optical properties including the exit angle and has an appearance adjustment function. The invention also relates to a method for preparing the light guide plate, a backlight unit including the light guide plate, and a liquid crystal display including the backlight unit.

Description of related technology

Since one of the backlight units of a liquid crystal display is not a self-illuminating device, the backlight unit includes a light source for supplying light. The backlight unit includes a light guide plate for guiding an output of light emitted by the light source, and A plurality of optical sheets including a ruthenium or the like and stacked on the light guide plate to increase the output efficiency of light passing through a front surface of the light guide plate. The light guide plate can be prepared by injection molding, compression or molding.

As described in Korean Patent No. 0898740, a rotatable main roller is formed on one circumference thereof and has a plurality of optical patterns, and is separated by a predetermined distance from one surface of the main roller by a feed. The roller feeds a base film. When the base film is transferred, a UV hardenable material is coated on the base film. Then, when the base film passes through the rotating main roll, the optical patterns are transferred onto the UV hardenable material, and the UV hardenable material is hardened by UV irradiation, thereby providing a form comprising forming on the main roll a light guide plate of the optical patterns (linear patterns).

Typically, the optical pattern is formed into a line on a main roll by a turning diamond tip. However, since the pattern processing requires accuracy, the optical patterns are formed in a uniform cross-sectional shape, size or pitch, or across the entire surface of the light guide plate. When the light guide plate on which the optical patterns are formed is mounted on a backlight unit, the shielding properties are attenuated due to the pattern lines, and visible light and hatching are generated outside thereof.

Summary of invention

According to an aspect of the present invention, a light guide plate includes: a side surface, and light emitted by a light source is incident on the side surface; a front surface is adjacent to the side surface and outputs light; and a rear surface, Adjacent to the side surface and reflecting light, wherein the front surface may be formed with a plurality of optical patterns, and the optical patterns are formed by a plurality of dots.

The optical patterns can be formed by intaglio.

The optical patterns can have a distance of between about 200 μm and about 1,000 μm.

The optical patterns can have a reduced distance as the distance from the source increases.

The optical patterns can have a height, width, or length that increases as the distance from the source increases.

The optical patterns may have a height of from about 4 μm to about 80 μm, a width of from about 4 μm to about 80 μm, and a length of from about 50 μm to about 300 μm.

In a horizontal direction with respect to a direction of light incident by the light source, a range can be defined between a line connecting the centers of the unidirectionally disposed optical patterns and a direction of light incident by the light source. Angle (θ).

The angle (θ) can range from greater than about 0° to less than about 90°.

The light guide plate may include optical patterns having different angles (θ), and the equal angles (θ) are defined between the lines connecting the respective centers of the optical patterns and the direction of the incident light.

The optical patterns can include 稜鏡, lenticular, or microlens patterns.

The optical patterns may have a triangular pyramid shape or a square column shape.

According to another aspect of the present invention, a method for preparing a light guide plate The method comprises: pressing an initial plate for a light guide plate by a pressure roller, and the pressure roller is formed with a plurality of patterns for forming an optical pattern, wherein the patterns for forming the optical pattern can be opposite The horizontal direction and the horizontal direction of one of the pressure rollers are separated from each other.

The patterns for forming the optical pattern have a distance of from about 50 μm to about 1,000 μm.

The pattern for forming the optical pattern has a distance from one side of the pressure roller to the other side of the pressure roller.

The patterns used to form the optical pattern may include a bismuth, a lenticular lens, or a microlens pattern.

Still another aspect of the present invention relates to a backlight unit and a liquid crystal display. The backlight unit and the liquid crystal display may include the light guide plate.

10a‧‧‧ side surface

10b‧‧‧ side surface

20‧‧‧ front surface

30‧‧‧Back surface

40a-40g‧‧‧ optical pattern

42a‧‧‧ side

43a‧‧‧ side

50a-50e‧‧‧ optical pattern

60a-60g‧‧‧ optical pattern

80a, 80b, 80a', 80b'‧‧‧ pattern

90‧‧‧Typical undivided pattern

100‧‧‧Light guide plate

110‧‧‧roller

120‧‧‧ turning tools

200‧‧‧Light guide plate

300‧‧‧Light guide plate

400,500,600‧‧‧pressure roller

H‧‧‧ Height

L‧‧‧ length

S1, S2, S3, ..., S‧‧‧ spacing

T1, T2, T3, ..., T‧‧‧ spacing

W‧‧‧Width

x,x1,x2‧‧‧ line

αB, βB, γB‧‧‧ angle

θ, θ1, θ2‧‧‧ angle

1 is a perspective view of a light guide plate in accordance with an embodiment of the present invention.

Figure 2 is a cross-sectional view of the light guide plate taken along line A-A' of Figure 1.

Figure 3 is a cross-sectional view of the light guide plate taken along line BB' of Figure 1.

Figure 4 is an enlarged cross-sectional view showing one of the light guide plates in accordance with an embodiment of the present invention.

Figure 5 is another enlarged cross-sectional view of the rim of the light guide plate in accordance with an embodiment of the present invention.

Figure 6 is a perspective view of a light guide plate in accordance with another embodiment of the present invention.

Figure 7 is a perspective view of a light guide plate in accordance with still another embodiment of the present invention.

Figure 8 is a diagram showing preparation of a light guide plate according to an embodiment of the present invention. Roll of the figure.

Figure 9 is a view showing the preparation of a pressure roller of a light guide plate according to another embodiment of the present invention.

Figure 10 is a flow chart showing the process of preparing a pressure roller of a light guide plate according to an embodiment of the present invention.

Figure 11 is a photograph of a light guide plate prepared in Example 1.

Fig. 12 is a photograph showing the evaluation results of one of the shielding properties of the light guide plate prepared in Example 1.

Figure 13 is a photograph of a light guide plate prepared in a comparative example.

Fig. 14 is a photograph showing the evaluation results of the shielding properties of the light guide plate prepared in the comparative example.

Detailed description of the preferred embodiment

According to an aspect of the present invention, a light guide plate includes: a side surface, and light emitted by a light source is incident on the side surface; a front surface is adjacent to the side surface and outputs light; and a rear surface, Adjacent to the side surface and reflecting light, wherein the front surface may be formed with a plurality of optical patterns, and the optical patterns are formed by a plurality of dots.

Hereinafter, a light guide plate according to an embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

1 to 7 show a light guide plate in accordance with the present invention.

A light guide plate 100, 200 or 300 according to an embodiment of the present invention includes: a side surface 10a, and light emitted by a light source is incident on the side surface 10a; a front surface 20 is adjacent to the side surface and Output light; and one after Surface 30 is adjacent to the side surface and reflects light. The side surface, the front surface, and the rear surface are integrated to form the light guide plate. The light guide plate may include another side surface (not shown) opposite to the side surface, and a further side surface 10b connecting the side surfaces.

The light guide plate may have a thickness of from about 0.5 mm to about 6 mm, and is not limited thereto.

The position of the light source can be determined according to one of the backlight units on which the light guide plate is mounted. Here, it is assumed that the light source is placed to face the side surface 10a. Of course, the backlight unit can include a plurality of light sources placed at different locations.

The rear surface may refer to a lower surface of a typical light guide plate. For example, the rear surface may be free of an optical pattern, or an optical pattern including a ruthenium pattern, a lenticular lens pattern, a microlens pattern, an embossed pattern, or the like may be formed.

The front surface is formed with a plurality of optical patterns 40a, 40b, ..., 40f, 40g. The optical patterns allow light incident from the side surface to be transmitted through total reflection.

The term "optical pattern" as used herein includes both relief and intaglio patterns. That is, the optical patterns include all of the embossed optical patterns protruding from the light guide plate and an intaglio optical pattern recessed on a flat surface of the light guide plate by recessing the light guide plate. 1 to 7 show a light guide plate including an intaglio optical pattern.

On the front surface of the light guide plate, a plurality of optical patterns 40a, 40b, ..., 40f, 40g are formed by a plurality of dots. The term "dot" as used herein means that a polarized light is separated from other optical patterns adjacent thereto. For example, the "dot" may have an island structure surrounded by a non-patterned area that does not form a pattern. The non-patterned area can be a planar area.

On the front surface of the light guide plate, the optical patterns are separated from each other by a certain distance between the ranges S1 and S2 in the horizontal (x direction) and vertical (y direction) directions with respect to one of the incident lights emitted by the light source. , S3, ..., S, T1, T2, T3, ..., T. As shown in FIGS. 1 to 7, in this configuration, the light guide plate includes a split optical pattern formed by dividing a typical meander pattern linearly disposed thereon. That is, since the one line is divided into a plurality of dot patterns on a backlight unit, the naked eye does not see the pattern lines outside the backlight unit.

As used herein, the term "pitch" means that the optical patterns are separated from one another by a distance relative to the direction of the incident light.

Figure 2 is a cross-sectional view of the light guide plate taken along line A-A' of Figure 1. The pitches S1, S2, S3, ... may be the same or different, and the pitches S1, S2, S3, ... are in a unidirectional arrangement in a vertical direction (y direction) with respect to the direction of incident light. The separation distance between the optical patterns 40a, 40e, 40f, 40g. The equal intervals S1, S2, S3, ... may range from about 50 μm to about 1,000 μm.

Figure 3 is a cross-sectional view of the light guide plate taken along line BB' of Figure 1. The pitches T1, T2, T3, ... may be the same or different, and the pitches T1, T2, T3, ... are in a horizontal direction (x direction) with respect to the direction of incident light, and are arranged in one direction. The separation distance between the optical patterns 40a, 40b, 40c, 40d.

The distance between the optical patterns may decrease as the distance from the light source increases (gradient type) so that the light emitted by the light source can be uniformly transmitted Out. The equidistances T1, T2, T3, ... may range from about 50 μm to about 1,000 μm.

One of the distances T (representing T1, T2, T3, ...) in the vertical direction (y direction) with respect to the direction of the incident light is a distance S in the horizontal direction (x direction) (representing S1, S2, S3) The ratio of ..., can be adjusted according to the shape, separation distance, and the like of the optical patterns.

A plurality of separate planes are formed on the surface formed on the front surface of the light guide plate. As used herein, the term "separate plane" means a portion of the surface of the light guide plate formed between the optical patterns and having no relief or intaglio optical patterns.

The shape of the separate planes may vary depending on the kind of the optical pattern, the distance between the optical patterns, and the like. The divided planes may have a rectangular shape, a square shape, a trapezoidal shape, a parallelogram shape, an irregular shape, and the like, and are not limited thereto. Since the separate planes are formed between the optical patterns, when the light guide plate is mounted on the backlight unit, an optical sheet including a crucible or the like can ensure shielding properties. Moreover, the shielding properties of the optical sheet can be improved by adjusting the length and/or width of the separate planes. In Figures 1, 6 and 7, the separate planes have a rectangular or trapezoidal shape.

The divided planes unidirectionally arranged in the vertical direction (y direction) with respect to the direction of the light incident by the light source may have the same or different areas.

The divided planes unidirectionally arranged in the horizontal direction (x direction) with respect to the direction of the light incident by the light source may have the same or different areas. As shown in Figure 1, the split planes may have an area that decreases as the distance from the source increases to allow the light emitted by the source to be evenly output.

In the present invention, the light guide plate can use any of the typical optical patterns conventionally used in the art.

For example, although the optical patterns are shown as having a meandering shape in FIGS. 1 through 7, the optical patterns may include lenticular or microlens patterns and the meandering patterns. The optical patterns can include triangular or quadrangular prism patterns.

Hereinafter, the optical patterns will be described with reference to the enthalpy patterns. However, it should be understood that the description of the 稜鏡 pattern can also be applied to the lenticular or microlens pattern.

The meandering pattern unidirectionally arranged in the horizontal direction (x direction) with respect to the direction of the light incident from the light source may have a polygonal cross section, and the polygonal cross section includes a shape such as a triangle, a rectangle, or the like. Figures 1 to 7 show a triangular ridge having a triangular cross section. The triangular cross section may include an equilateral triangular cross section, an isosceles triangular cross section, three sides having one of different lengths, an equilateral triangular cross section, and the like.

Referring to FIG. 4, the angle between the two sides of the one of the triangular cross sections 40a and the front surface 20 of the light guide plate is represented by αB and βB, respectively, and the angle between the two sides of the crucible is γB. In the representation, the exit angle of one of the light sources can be adjusted by adjusting αB, βB and a vertical angle γB (αB+βB+γB=180°).

In a crucible having a triangular cross section, αB is an angle between the one side 42a of the crucible facing the light source and the front surface 20 of the light guide plate and may be from about 40° to about 60° Within the scope. βB is the other side 43a of the crucible facing the side opposite to the light source and the light guide plate An angle between the front surfaces 20 can be in the range of from about 40° to about 60°. By adjusting αB to be the same as βB, the crucible may have an equilateral triangle or an isosceles triangle cross section. γB is an angle between the sides of the crucible before the surface of the light guide plate is not included and may be 180-(αB+βB)°.

The crucible disposed unidirectionally in the vertical direction (y direction) with respect to the direction of the light incident by the light source may have a rectangular cross section, a trapezoidal cross section, a parallelogram cross section, a square cross section, and a quadrangular cross section. Deformation of the section, etc. Figure 5 shows the length of a length of L, the height of a H, and a rectangular cross section.

Uniform illumination efficiency can be obtained by adjusting the height (H), width (W) or length of the optical patterns. The height, width or length of the optical patterns may decrease (gradient type) as the distance from the light source increases in a horizontal direction relative to the direction of light incident by the light source. Therefore, the light emitted by the light source can be output uniformly.

The optical patterns may have a height of from about 4 μm to about 80 μm, a width of from 4 μm to about 80 μm, and a length of from 50 μm to about 300 μm.

Referring to FIG. 6, in a horizontal direction (x direction) with respect to a direction of light incident by the light source, a line connecting the centers of the unidirectionally disposed optical patterns 50a, 50b, 50c, 50d, 50e ( x) Defining a range of angles (θ) from the direction of the light incident by the source. The angle can range from greater than about 0° to less than about 90°, and preferably from about 12° to about 45°.

Just in the horizontal direction relative to the direction of the light incident by the source In the case of an optical pattern having a quadrangular cross section upward, the center of the optical pattern may represent one of the two diagonal intersections of the quadrilateral cross section of the crucible.

The angle (θ) may vary in a vertical direction (y direction) with respect to a direction of light incident by the light source. That is, the light guide plate may include an optical pattern defining different angles (θ). Figure 7 shows a light guide plate comprising optical patterns having different angles (θ1, θ2). In Fig. 7, the line (x1) and the center of each of the optical patterns 60a, 60b, 60c, 60d, 60e are connected to each other with respect to the horizontal direction (x direction) of the direction of the light incident from the light source. An angle (θ1) defined between the directions of the light incident from the light source may be between a line connecting the centers of the unidirectionally disposed optical patterns 60a, 60f, 60g (x2) and the direction of the light incident by the light source. The defined angle (θ2) is different.

Another aspect of the invention relates to a method of preparing a light guide plate using a pressure roller. A light guide plate with adjustable optical properties can be prepared by implementing separate optical patterns having different widths, heights or lengths.

A method of preparing a light guide plate includes pressurizing one of the initial plates for the light guide plate using a pressure roller. Figures 8 and 9 show a pressure roller for preparing a light guide plate for use in the method according to the present invention. Each of the pressure rollers 400, 500 forms a pattern 80a, 80b on one surface thereof for forming an optical pattern, and the patterns can be in contact with the initial plate for one of the light guide plates on the light guide plate, followed by pressurization operation An optical pattern having a certain shape is formed. Further, the pressure roller for the light guide plate may include a roller shaft 110 for supporting and rotating the roller.

Although FIGS. 8 and 9 show a relief pattern for forming an optical pattern, the pressure roller may include an intaglio pattern for forming an optical pattern.

On the surface of the pressure roller, the pattern for forming the optical pattern forms a point shape. That is, the pattern for forming the optical pattern is separated from each other by a certain distance S, T in a horizontal and vertical direction with respect to one of the pressing directions of the pressing roller.

All of the foregoing descriptions of the optical patterns can also be applied to the pattern used to form the optical pattern.

That is, as in the above optical pattern, the pattern for forming the optical pattern may have the same or different pitches S1, S2, S3, ... in the horizontal direction (y direction) with respect to the rotational direction of the roller. The equal intervals S1, S2, S3, ... may range from about 50 μm to about 1,000 μm.

The unidirectional arrangement pattern for forming the optical pattern may have the same or different pitches T1, T2, T3, ... in the vertical direction (x direction) with respect to the rotation direction of the roller. The equidistances T1, T2, T3, ... may range from about 50 μm to about 1,000 μm.

The pattern for forming the optical pattern may have a distance from one side of the pressure roller to the other side of the pressure roller.

Figure 10 is a flow chart for preparing a process for one of the pressure rollers of the light guide plate.

A pressure roller 600 for a light guide plate is prepared which includes a typical undivided pattern 90 for forming an optical pattern. The roller rotates at a fixed speed and then stops. Then, a turning tool 120 is horizontally moved at a position on the roller in a direction for forming a separate pattern to cut and remove a portion of the typical patterns, thereby forming a pattern 80a' for forming an optical pattern. , 80b'. By repeating the procedure for removing such typical patterns, A pressure roller 400 for a light guide plate is prepared, and the pressure roller 400 includes separate patterns 80a, 80b for forming an optical pattern, as shown in FIG.

Alternatively, a pressure roller for a light guide plate is prepared which includes a typical undivided pattern for forming an optical pattern. The roller rotates at a fixed speed and then stops. Then, when the roller rotates at a certain speed, the turning tool is horizontally moved at a position on the roller in a direction for forming a separate pattern, thereby preparing a pressure roller 500 for the light guide plate, wherein a pattern The removed portion forms a spiral curve as shown in FIG.

In order to adjust an exit angle, the optical patterns including the pupils to be applied to the light guide plates have an anisotropic triangle instead of an isosceles triangle, and the pupils also have various pitches, heights or widths. Gradient pattern. In a typical main roll for fabricating a light guide plate, it is difficult to adjust an exit angle because the patterns for forming the optical pattern have the same pitch and the crucible has an isosceles triangular cross section. Conversely, the pressure roller for a light guide plate according to the embodiments may allow adjustment of the direction of the turning tool or the like to provide a light guide plate having adjustable optical properties.

The light guide plate can be prepared by pressurizing an initial plate for a light guide plate using the above-described pressure roller for a light guide plate.

As the initial plate for the light guide plate, any transparent resin generally used for preparing the light guide plate can be used. Examples of the transparent resin may include (meth)acrylic resin, polycarbonate resin, styrene resin, olefin resin, polyester resin, and the like. Preferably, the initial plate for the light guide plate is formed of a poly(methyl methacrylate) resin.

Although the conditions for pressurizing the initial plate are not particularly limited, However, when the initial sheet is formed of an acrylic resin, the pressurization of the initial sheet is carried out at a temperature of from about 80 ° C to about 110 ° C.

Another aspect of the present invention relates to a backlight unit and a liquid crystal display. The backlight unit and the liquid crystal display may include the light guide plate. The backlight unit can be disposed on an optical display device by a typical method.

Hereinafter, the present invention will be described with reference to certain examples. It should be understood that the examples are only illustrative and should not be construed as limiting the invention in any way.

For the sake of clarity, descriptions of the details known to those of ordinary skill in the art will be omitted.

example 1

A pressure roller for a light guide plate having no separate pattern for forming an optical pattern is prepared. The pattern used to form the optical pattern has a triangular cross section when viewed in a horizontal direction relative to one of the directions of rotation of the roller. After rotating and stopping the roller, a portion of the pattern is cut and removed by moving a turning tool horizontally on the roller. At this time, the pattern for forming the optical pattern has a distance of 400 μm to 800 μm, a width of 6 μm to 12 μm, and a height of 4 μm to 10 μm to have a graded state. A pressure roller for a light guide plate having a pattern for forming an optical pattern was prepared as shown in FIG. A pilot plate for a light guide plate formed of poly(methyl) propylene methyl ester was fed and pressurized by a pressure roller for a light guide plate, thereby preparing a light guide plate.

Example 2

As in Example 1, by using a pressurization for a light guide plate The roller is pressed to prepare a light guide plate, but the light guide plate has an angle θ of 25° in Fig. 6.

Comparative example

A pressure roller for a light guide plate having no separate pattern for forming an optical pattern is prepared. Next, a light guide plate is pressed using a pressure roller for a split pattern according to an embodiment of the present invention, and another light guide plate is pressed using a typical pressure roller for a turn pattern.

Regarding the shielding properties, light guide plates prepared as in the examples and comparative examples were evaluated.

The shielding property of the light guide plate was evaluated by visually observing a pattern on a lower surface of the light guide plate when an MLA film was stacked on a light guide plate of a backlight unit. After opening a 32-inch LCD module using an edge-type LED light source, a die (MLA film) is placed on the light guide plate and it is determined whether the pattern on one of the lower surfaces of the light guide plate can be visually observed. The results are shown in Table 1 and Figures 11 to 14.

Fig. 11 shows a light guide plate having a split-line pattern on its lower surface as prepared in Example 1, and Fig. 12 shows the evaluation results of the shielding properties thereof. As shown in Fig. 12, the separate line-shaped pattern on the lower surface of the light guide plate cannot be seen by the naked eye. Thus, it will be appreciated that a single MLA film can be used to shield a light guide in accordance with the present invention.

Fig. 13 shows a light guide plate having a typical turn pattern as prepared in the comparative example, and Fig. 14 shows the evaluation results of the shielding properties thereof. As shown in Fig. 14, the eyelid pattern can be slightly seen by the naked eye as compared with the light guide plate according to the present invention. Therefore, it can be understood that the light guide plate cannot use only one MLA. The film is shielded and an additional optical sheet is required.

o: The line pattern on the surface is not visible to the naked eye.

x: The crepe pattern on the surface is visible to the naked eye.

10a‧‧‧ side surface

10b‧‧‧ side surface

20‧‧‧ front surface

30‧‧‧Back surface

40a-40g‧‧‧ optical pattern

S‧‧‧ spacing

T‧‧‧ spacing

100‧‧‧Light guide plate

Claims (16)

A light guide plate comprising: a side surface, wherein light emitted by a light source is incident on the side surface; a front surface adjacent to the side surface and outputting light; and a rear surface being associated with the side surface Adjacent and reflected light, wherein the front surface is formed with a plurality of optical patterns, and the optical patterns are formed by a plurality of dots. The light guide plate of claim 1, wherein the optical patterns are formed by indentation. The light guide of claim 1, wherein the optical patterns have a distance of between about 50 μm and about 1,000 μm. The light guide of claim 1, wherein the optical patterns have a reduced distance as the distance from the source increases. The light guide of claim 1, wherein the optical patterns have a height, a width, or a length that increases as the distance from the light source increases. The light guide plate of claim 1, wherein the optical patterns have a height of from about 4 μm to about 80 μm, a width of from about 4 μm to about 80 μm, and a length of from about 50 μm to about 300 μm. The light guide plate of claim 1, wherein a line connecting the centers of the unidirectionally disposed optical patterns and the light incident by the light source are in a horizontal direction with respect to a direction of light incident by the light source The angle (θ) of a certain range is defined between the directions. The light guide of claim 7, wherein the angle (θ) is in a range from greater than about 0° to less than about 90°. The light guide plate of claim 7, wherein the optical patterns have different angles (θ), and the equal angles (θ) are defined between the lines connecting the respective centers of the optical patterns and the direction of the incident light. The light guide of claim 1, wherein the optical patterns comprise a bismuth, a lenticular lens, or a microlens pattern. The light guide plate of claim 1, wherein the optical patterns have a triangular pyramid shape or a square pillar shape. A method for preparing a light guide plate comprising: pressurizing an initial plate for a light guide plate with a pressure roller, and the pressure roller is formed with a plurality of patterns for forming an optical pattern for forming an optical pattern The pattern forms a little shape. The method of claim 12, wherein the patterns for forming the optical pattern have a distance of between about 50 μm and about 1,000 μm. The method of claim 12, wherein the pattern for forming the optical pattern has a distance from one side of the pressure roller to a distance from the other side of the pressure roller. The method of claim 12, wherein the pattern for forming the optical pattern comprises a bismuth, a lenticular lens, or a microlens pattern. A backlight unit comprising the light guide plate according to any one of claims 1 to 11.