KR101582373B1 - Method for preparing light guide plate, light guide plate prepared from the same and liquid crystal display comprising the same - Google Patents

Abstract

The present invention includes a step of pressing one surface of a thermoplastic resin continuously extruded in a plate form into a first pattern roll and pressing the other surface of the thermoplastic resin pressed by the first pattern roll to a second pattern roll adjacent to the first pattern roll Wherein a plurality of non-dot-shaped optical patterns are arranged in the first pattern roll with the longitudinal direction of the first pattern roll in the longitudinal direction of the optical pattern, and in the second pattern roll, And a dot-shaped optical pattern having a density as close to the density as it goes from both outer edges to the center in the longitudinal direction, and a liquid crystal display including the light guide plate manufactured thereby .

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a light guide plate, a light guide plate manufactured from the same, and a liquid crystal display device including the same. BACKGROUND ART [0002]

The present invention relates to a method of manufacturing a light guide plate, a light guide plate manufactured from the same, and a liquid crystal display device including the same.

The light guide plate is included in the backlight unit of the liquid crystal display device, and can convert the light incoming from the light source into the light plane. In recent years, attempts have been made to add a pattern shape to the light guide plate to exclude a sheet or a film included in the backlight unit. In order to achieve this, a pattern shape that can increase the light output angle should be added to the light guide plate.

As a method for producing a patterned light guide plate having a pattern shape, there is a method for manufacturing a patterned light guide plate, which comprises a step of applying a UV radiation resin to a base film and transferring the pattern to UV radiation, an injection step, a step of directly processing the pattern, a step of transferring using rolls, Is being developed. Especially, in case of Hot Stamping process, the pattern was transferred to both sides of extruded light guide plate, and align marker was attached to the light guide plate. However, this method involves an align cutting process which requires processing of the patterned light guide plate by a predetermined number of inches, so that the yield of the light guide plate is low and the yield stability can not be obtained. In addition, as described above, in order to exclude a sheet or film in a conventional backlight unit, the light guide plate pattern transfer ratio must also be high.

In this regard, Korean Patent Registration No. 10-1204690 discloses a method of manufacturing a light guide plate having a pattern formed by pressing a light guide plate material extruded using a press panel having an optical pattern formed thereon.

It is an object of the present invention to provide a method for manufacturing a light guide plate having no yielding and high yield in manufacturing a light guide plate.

Another object of the present invention is to provide a method for manufacturing a light guide plate having a high double-sided pattern transfer ratio in a double-sided pattern light guide plate.

A method of manufacturing a double-side patterned light guide plate, which is one aspect of the present invention, includes patterning one surface of a thermoplastic resin continuously extruded in a plate shape into a first pattern roll, and patterning the other surface of the thermoplastic resin patterned by the first pattern roll, Patterning the first pattern roll with a second pattern roll adjacent to the first pattern roll, wherein a plurality of non-dot-like optical patterns arranged in the longitudinal direction of the optical pattern are formed in the first pattern roll And the second pattern roll may be provided with a dot-shaped optical pattern having a density as close to the center as the center of the second pattern roll in the longitudinal direction of the second pattern roll.

The light guide plate, which is another aspect of the present invention, can be manufactured by the above manufacturing method.

The liquid crystal display device according to another aspect of the present invention may include the light guide plate.

The present invention provides a method for manufacturing a light guide plate that does not require align cutting when manufacturing a light guide plate and has a high yield. The present invention provides a method of manufacturing a light guide plate having a high double-sided pattern transfer ratio in a double-sided pattern light guide plate.

1 is a flow chart of a method of manufacturing a light guide plate according to one embodiment of the present invention.
2 is an enlarged view of the first pattern roll surface.
3 is an enlarged view of the second pattern roll surface.
4 is a perspective view of a light guide plate manufactured according to one embodiment of the present invention.
5 is a detailed view of a light guide plate manufacturing method of a comparative example.

A method of manufacturing a light guide plate according to an aspect of the present invention includes patterning a first surface of a thermoplastic resin continuously extruded in a plate form into a first pattern roll and patterning the other surface of the thermoplastic resin patterned by the first pattern roll Wherein the first pattern roll is formed with a plurality of non-dot-shaped optical patterns arranged with the longitudinal direction of the first pattern roll in the longitudinal direction of the optical pattern, And the second pattern roll may be formed with a dot-shaped optical pattern having a density which is closer to the central portion from both outer portions in the longitudinal direction of the second pattern roll.

In the above manufacturing method, a light guide plate patterned on both sides of a plate-extruded thermoplastic resin using rolls of a first pattern roll and a second pattern roll can be produced in-line. The 'in-line' means that the same or different patterns can be transferred to one side and the other side of the light guide plate in one continuous process using two rolls.

For convenience, the 'one side' and the 'other side' may be upper and lower surfaces of the thermoplastic resin extruded into a plate, respectively, and may be light emitting surfaces of the light guide plate.

The terms 'upper', 'upper surface', 'lower', and 'lower surface' in this specification are based on the drawings for convenience, and the terms 'upper' and 'upper' ',' Lower 'may be changed to' upper ', and' lower surface 'may be changed to' upper surface '.

1 is a flow chart of a method of manufacturing a light guide plate according to one embodiment of the present invention.

1, a thermoplastic resin 10 for producing a light guide plate is melted in a molten portion 20 of a melt extruder and continuously extruded from the extruded portion 21 to produce an extruded thermoplastic resin plate 30 have.

The thermoplastic resin 10 is not limited as long as it is transparent in visible light and can be patterned upon extrusion and pressurization of a pattern roll. In an embodiment, the thermoplastic resin is a resin having a glass transition temperature (Tg) of 90 占 폚 to 150 占 폚, and may include, for example, polymethyl (meth) acrylate (PMMA).

The melted thermoplastic resin is extruded in the form of a plate. The thickness of the extruded thermoplastic resin 30 in the form of a plate may be 1 mm to 5 mm in consideration of the thickness of the final light guide plate.

The upper surface 31 of the extruded thermoplastic resin 30 is in contact with the first pattern roll 40 and one surface of the thermoplastic resin, that is, the upper surface 31 of the thermoplastic resin 30, (111). ≪ / RTI > The patterning method may include, but is not limited to, pressing by rotation or the like of the first pattern roll 40 and the like.

Thereafter, the other surface of the thermoplastic resin on which the upper surface 31 is patterned by the first pattern roll, that is, the lower surface 32 is brought into contact with the second pattern roll 50, and the thermoplastic resin That is, the lower surface 32 may be patterned with the second pattern 121. The patterning method may include, but is not limited to, pressing by rotation or the like of the second pattern roll 50 and the like.

From this, a double-side patterned light guide plate having a first pattern formed on the upper surface and a second pattern formed on the lower surface can be manufactured. At this time, in addition to the rotation of the pattern roll, normal pressing means may be further applied to facilitate pattern formation.

The first pattern roll 40 may be formed with a first pattern arranged in the longitudinal direction of the optical pattern in a first direction (a y-axis direction in FIG. 1) that is the longitudinal direction of the first pattern roll 40 . The first pattern may include a non-dotted optical pattern. The 'non-dot type optical pattern' may mean an optical pattern in which optical patterns having a predetermined cross section are not spaced apart from each other by a predetermined distance, or are separated only in one direction. For example, a prism pattern having a lenticular lens-like pattern or a predetermined cross-sectional shape (e.g., a polygon such as a triangle or a quadrangle).

The first pattern may be a relief pattern or a relief pattern.

In FIG. 1, the longitudinal direction of the first pattern is denoted as a y-axis direction, the width direction as an x-axis direction, and the height direction as a z-axis direction, and the x-, y-, and z-axes are orthogonal to each other.

In Fig. 1, the longitudinal direction of the first pattern roll is indicated as a y-axis direction, and the radial direction is indicated as an x-axis direction. In Fig. 1, the thermoplastic resin moves in the x-axis direction.

Fig. 2 is an enlarged view of the surface of the first pattern roll 40. Fig.

Referring to FIG. 2, a plurality of lenticular lens-like patterns 41 may be formed on the surface of the first pattern roll 40 in the shape of an obtuse angle and arranged in the longitudinal direction of the first pattern roll. The lenticular lens-like pattern may be a pattern having a semicircular or semi-elliptical cross-section and a length in a predetermined range as shown in Fig. The length, width, and height of the lenticular lens-like pattern can be changed according to the light guide plate to be finally manufactured.

In a specific example, the length La of the lenticular lens-like pattern is 1500 mm to 1700 mm in accordance with the roll length, the pitch (width, Pa) of the lenticular lens-like pattern is 10 μm to 500 μm, The height Ha may be 20 占 퐉 to 150 占 퐉. Within this range, there may be a linear effect of light.

In Fig. 2, the longitudinal direction of the first pattern is denoted as a y-axis direction, the width direction as an x-axis direction, and the height direction as a z-axis direction, and the x-, y-, and z-axes are orthogonal to each other.

A dot-shaped optical pattern may be formed on the second pattern roll. The 'dot-shaped optical pattern' may mean an optical pattern in which a plurality of optical patterns having a predetermined cross-section are spaced apart from each other by a predetermined distance over all four directions.

The dotted optical pattern may be a relief pattern or a relief pattern, and may include, for example, a dotted optical pattern whose cross section is circular, semicircular, elliptical, semi-elliptical or amorphous.

Fig. 3 is an enlarged view of the surface of the second pattern roll 50. Fig.

Referring to FIG. 3, the dot-shaped optical pattern 51 is formed in a relief pattern.

In Fig. 3, the longitudinal direction of the second pattern roll is indicated as a y-axis direction, the width direction as an x-axis direction, and the height direction as a z-axis direction, and the x-, y-, and z-axes are perpendicular to each other.

The dot-shaped optical patterns may be formed at different densities on the second pattern roll surface in order to increase the application and brightness of the light guide plate.

Referring to FIG. 3, the dot-shaped optical pattern may be formed at a density as small as possible from the outer edge of the pattern roll to the center thereof with respect to the longitudinal direction of the pattern roll. This can increase the center luminance in the edge type backlight unit in which the light source is formed on both sides.

In a specific example, the pitch Pb between the patterns in the dotted optical pattern may be 0.3 mm to 0.5 mm at the central portion most tightened at 1.0 to 1.2 mm in both outer portions of the roll as the light-entering portion, and the width of the pattern Lb ) May be 100 m to 300 m, and the height Hb of the pattern may be 20 m to 60 m. Within the above range, the luminance uniformity may be effective.

As described above, the patterns of the above-described predetermined shapes are formed on the surfaces of the first pattern roll and the second pattern roll. In manufacturing the light guide plate of Fig. 4, there is no need of align cutting after forming the second pattern, Since only the process of cutting the light guide plate is required, mass production of the light guide plate can be enhanced.

The first pattern roll and the second pattern roll may be formed with a first pattern and a second pattern on the entire roll surface in order to secure the above-described mass productivity. This is because the ultraviolet ray-curable thermoplastic resin can be simply cut into a light guide plate having a desired size.

The above manufacturing method is characterized in that the extruded thermoplastic resin is patterned by a plate-extruded thermoplastic resin, and the extruded thermoplastic resin is first transferred by the rotation of the first pattern roll, and then by the rotation of the second pattern roll The second pattern may be sequentially transferred.

When the thermoplastic resin is allowed to pass between the first pattern roll and the second pattern roll while simultaneously rotating the first pattern roll and the second pattern roll so that both patterns are simultaneously formed on one surface and the other surface of the thermoplastic resin, This is because cooling of the resin is not smooth and the pattern transfer rate can be lowered.

The first pattern roll and the second pattern roll can change the surface temperature, the surface temperature difference, the peripheral speed difference, the diameter, etc. in order to increase the transfer rate of the first pattern and the second pattern.

In a specific example, the surface temperatures of the first pattern roll and the second pattern roll may be lower than the glass transition temperature of the thermoplastic resin by 20 DEG C or lower, preferably 0 DEG C to 20 DEG C, respectively. Within this range, there may be a pattern transfer effect.

In a specific example, the surface temperature difference between the first pattern roll and the second pattern roll (the surface temperature of the first pattern roll-the surface temperature of the second pattern roll) may be preferably 0 ° C to 10 ° C. In the above range, the pattern transfer effect and roll curling can be minimized.

In an embodiment, the peripheral velocity of the second pattern roll may be 100% to 102%, preferably 100% to 101% of the peripheral velocity of the first pattern roll. Within this range, there may be a pattern transfer effect.

In an embodiment, the diameter of the second pattern roll may be 100% to 150% of the diameter of the first pattern roll. In the above range, there may be a cooling uniform effect on the upper and lower portions of the sheet.

Referring to FIG. 1, a double-side patterned light guide plate having a first pattern and a second pattern formed on the upper and lower surfaces of the thermoplastic resin extruded by rotation of the first pattern roll and the second pattern roll, respectively, can be manufactured.

The first pattern roll and the second pattern roll are rotated in one direction. For example, as shown in FIG. 1, the first pattern roll may be rotated counterclockwise and the second pattern roll may be rotated clockwise.

The extruded thermoplastic resin can be brought into contact with the second pattern roll adjacent to the first pattern roll after contacting with the first pattern roll. In order to increase the pattern transfer rate and prevent sagging of the extruded thermoplastic resin, The second pattern rolls come into contact with each other and the extruded thermoplastic resin 30 passes between the first pattern roll 40 and the second pattern roll 50 as shown in Fig. May be desirable.

The first pattern roll and the second pattern roll may be formed of a metal material. In a specific example, a roll of steel or stainless steel (SUS) material may be coated with a coating material such as copper plating, polishing, black coating or UV treatment, laser processing, etching, black coating removal, brushing, patterning, And the like. The first pattern roll and the second pattern roll may be provided with a separate metal layer on the surface of the roll in order to reduce the adhesion of the extruded thermoplastic resin.

Since the thermoplastic resin extruded from the extruder is at a temperature higher than the glass transition temperature, it may be subjected to a predetermined cooling process before being pressurized by the first pattern roll in order to increase the pattern transfer rate. In embodiments, the thermoplastic resin extruded from the extruder may be subjected to a step of contacting the first cooling roll. 1, the first cooling roll 60 and the first pattern roll 40 are adjacent to each other, and the thermoplastic resin 30 extruded from the extruder is passed through the first cooling roll 60 and the first pattern roll 40 ). ≪ / RTI >

In addition, the thermoplastic resin having the dot-shaped optical pattern formed thereon may also be brought into contact with the second cooling roll 70 in order to increase the pattern transfer rate.

The surface temperature of the first cooling roll and the second cooling roll may preferably be lower than the glass transition temperature of the thermoplastic resin by 0 占 폚 to 20 占 폚.

A step of cutting the light guide plate with a predetermined length and width after transferring the second pattern or processing the mirror surface of the cut light guide plate may be further roughened.

Referring to FIG. 1, a double-side patterned light guide plate having a first pattern 111 formed on the upper surface 110 and a second pattern 121 formed on the lower surface 120 can be manufactured by the above- .

The light guide plate thus manufactured may have a thickness of 1 mm to 5 mm. In the above range, it can be used for a backlight unit application. In an embodiment, the upper surface on which the lenticular lens-shaped pattern is formed and the lower surface on which the dot-shaped pattern is formed may be a light output surface in the backlight unit.

The light guide plate, which is another aspect of the present invention, can be manufactured by the above manufacturing method.

4 is an exploded perspective view of a specific example of the light guide plate.

4, the light guide plate 200 includes a side surface 215 on which light generated from the light source 210 is incident, a front surface 220 and a back surface 225 connected to the side surface 215 to emit the light, A lenticular lens type optical pattern 235 formed on the front surface 220 and having a predetermined sectional shape and an optical pattern 235 formed on the rear surface 225 and extending from the light source 210 to the side surface 215 And a dot pattern 240 in which the pattern density is changed from a small density to a dense density toward the central portion from the outer periphery of the back surface with reference to a direction in which light is incident (arrow direction).

The liquid crystal display device according to another aspect of the present invention may include a backlight unit including the light guide plate. Considering the double-sided pattern of the light guide plate, the liquid crystal display device may be a liquid crystal display device including both side light sources.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

Example  One

The molten polymethylmethacrylate resin was extruded from the extruder in the form of a plate, and sequentially pressed by the first pattern roll and the second pattern roll by means of Figs. 1 to 3, thereby producing the light guide plate of Fig.

Comparative Example  One

In Example 1, the pattern roll (a) of Fig. 5 was used instead of the first pattern roll of Fig. 2, the pattern roll (b) of Fig. 5 was used in place of the second pattern roll of Fig. The light guide plate of Fig. 4 was manufactured in the same manner.

Comparative Example  2

In Example 1, the pattern rolls of Figs. 2 and 3 were arranged as shown in Fig. 5 (c), the thermoplastic resin was extruded, and both surfaces of the extruded thermoplastic resin were simultaneously patterned to produce the light guide plate of Fig.

The yields of the light guide plate and the pattern transfer ratio prepared in the above Examples and Comparative Examples were evaluated. The yield of the light guide plate was calculated by the ratio of the weight of the light guide plate to the weight of the light guide plate manufacturing raw material, and the pattern transfer rate was measured with a microtiter ET4000.

Example 1 Comparative Example 1 Comparative Example 2 Light guide plate production yield (%) 86 76 86 Pattern Transfer Rate (%) 65 65 54 알로 cutting
Presence or absence Without include Without

As shown in Table 1, the light guide plate manufacturing method of the present invention can manufacture the light guide plate at a high yield without an aline cutting process, and it is confirmed that the pattern transfer rate is also high.

On the other hand, Comparative Example 1, which is a conventional method for manufacturing a light guide plate, requires an aline cutting process, so that the yield of a light guide plate is lowered due to an area loss and an alignment cutting defect.

In Comparative Example 2 in which the first pattern roll and the second pattern roll were simultaneously patterned, an aline cutting process was required and the pattern transfer rate was also low.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (12)

Patterning one surface of a thermoplastic resin continuously extruded into a plate into a first pattern roll and patterning the other surface of the thermoplastic resin patterned with the first pattern roll into a second pattern roll adjacent to the first pattern roll and,
A plurality of non-dot-shaped optical patterns arranged in the first pattern roll with the longitudinal direction of the first pattern roll in the longitudinal direction of the optical pattern,
Wherein the second pattern roll is provided with a dot-shaped optical pattern having a dense density at a small density from both outer edges to the center of the second pattern roll with respect to the longitudinal direction of the second pattern roll,
Further comprising the step of contacting the extruded thermoplastic resin with the first cooling roll before patterning the first pattern roll. The method of manufacturing a double-side patterned light guide plate according to claim 1, wherein the non-dotted optical pattern includes at least one of a lenticular lens and a prism having a predetermined cross section. The method of manufacturing a double-side patterned light guide plate according to claim 1, wherein the thermoplastic resin patterned by the first pattern roll passes between the first pattern roll and the second pattern roll. The method according to claim 1, wherein the surface temperatures of the first pattern roll and the second pattern roll are 0 ° C to 20 ° C lower than the glass transition temperature of the thermoplastic resin, respectively. The method of manufacturing a double-side patterned light guide plate according to claim 1, wherein the peripheral speed of the second pattern roll is 100% to 102% of the peripheral speed of the first pattern roll. The method of manufacturing a light guide plate according to claim 1, wherein the diameter of the second pattern roll is 100% to 150% of the diameter of the first pattern roll. The method of manufacturing a double-side patterned light guide plate according to claim 1, wherein the first pattern roll and the second pattern roll each have a positive or negative optical pattern. The method of manufacturing a double-side patterned light guide plate according to claim 1, wherein the thermoplastic resin comprises polymethyl (meth) acrylate. delete The method of manufacturing a double-side patterned light guide plate according to claim 1, further comprising the step of contacting the patterned thermoplastic resin with the second pattern roll with a second cooling roll. The method of manufacturing a double-side patterned light guide plate according to claim 1, further comprising cutting the light guide plate to a predetermined size. A light guide plate manufactured by the manufacturing method of any one of claims 1 to 8 and 10 to 11.

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