KR20120087604A - Manufacturing method of light guide plate for backlight unit and the same - Google Patents

Abstract

PURPOSE: A method for manufacturing a light guide plate for a backlight unit and a light guide plate manufactured by the same are provided to form a uniform optical pattern on a light guide plate material. CONSTITUTION: A method for manufacturing a light guide plate for a backlight unit comprises the steps of: supplying a light guide plate material to an extruder(110), continuously extruding the light guide plate material into plates, forming an optical pattern(11a) on the surface of an extruded material(11) using a pressing unit(120), and cutting the extruded material with a cutter(130) to a predetermined size, thereby obtaining a light guide plate(11') with an optical pattern(11'a).

Description

Manufacturing method of light guide plate for backlight unit and the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide plate of a backlight unit that provides light in various liquid crystal display devices including LCD-TVs (including LED-TVs) or computer LCD monitors, as well as lighting devices using surface light sources. The present invention relates to a method for manufacturing a light guide plate for a backlight unit and a light guide plate for simplifying the overall process of manufacturing including a pattern forming process.

As is well known, the backlight unit (BLU) is applied to various liquid crystal display devices that require a surface light source, that is, an LCD monitor of an LCD-TV or a computer, so that the display image is evenly visible from the back of the LCD. It is a light source device that serves to illuminate. In addition, the backlight unit is also applied to a lighting device employing a light emitting diode (LED) as a light source to achieve surface light emission.

Such a backlight unit includes a lamp represented by a cold cathode fluorescent lamp (CCFL) or a light emitting diode (LED), which are light sources for emitting light, and a light guide plate for converting light emitted from the lamp into a surface light source, It is composed of a reflection sheet disposed on the back of the light guide plate to reflect the light emitted to the rear of the light guide plate, and an optical sheet such as a diffusion sheet and a prism sheet stacked on the top of the light guide plate. do.

In particular, the light guide plate is a key component of the backlight unit that converts the light incident from the light source into uniform plane light, and its material is PMMA, which is an acrylic resin having excellent transparency and gloss due to its low absorption of light in the visible region. (PolyMethoy MethAcryl).

In addition, the reflective sheet is positioned below the light guide plate to reflect light incident from the light source toward the light emitting surface of the backlight to increase light utilization efficiency. The luminance of the entire light emitting surface of the backlight is uniform by adjusting the amount of reflection of the entire incident light. To have. The material of the reflector is mainly a polyester (PET) film or a metal coating film.

In addition, the diffusion sheet is located on the light exit surface side of the light guide plate, and diffuses and scatters the light incident through the light guide plate to increase and uniform the luminance in the front direction of the light exit surface. As a material of the diffusion plate, a polyester resin having good light diffusing ability and high luminance is mainly used, and a surface diffusion layer is coated on the PET film to increase the light diffusing ability.

The prism sheet prevents light from the diffusion sheet from exiting in a direction other than the front surface of the light-emitting surface, improves light directivity, and narrows the viewing angle, thereby increasing the brightness toward the backlight light-emitting surface front.

In the backlight unit configured as described above, the light guide plate of the present invention will be described in more detail as follows.

1 shows a configuration of a backlight unit, wherein a lamp 2 serving as a light source is disposed at an edge portion of the light guide plate 1 with respect to the center of the light guide plate 1, and a reflective sheet is formed on the rear part of the light guide plate 1. (3) is arrange | positioned, and the diffusion sheet 4 and the prism sheet 5 are arrange | positioned in order on the light exit surface of the light guide plate 1. And the back surface of the light guide plate 1 is formed with the optical pattern 1a for uniformly distributing the light irradiated from the lamp 2 to the light guide plate 1.

The optical pattern 1a is usually formed in a U-shape or a V-shape, so that light irradiated from the lamp 2 causes diffuse reflection to uniformly reflect toward the light-emitting surface of the light guide plate 1.

On the other hand, the manufacturing method of the light guide plate as shown in Figure 2 (a), (b), (c), (d) of Figure 2, the method of cutting and printing the extruded plate after printing, the ink printing method, the injection method, And laser processing.

Among them, the method of cutting and printing the extruded sheet material ((a)) shows that the PMMA extruded sheet material is cut to size, the cut surface is smoothly processed, the optical resin is applied to the light emitting surface, and the optical pattern is printed. As a construction method, there is a disadvantage that a lot of labor.

In the case of the inkjet printing method (b), a method of forming a dot type or embossed optical pattern by forming a pattern mask and ink squeezing on individual cut PMMA plates, There is a problem in the life of the pattern mask in comparison with the productivity, and a problem in the ink formulation and the process setting.

In addition, the injection method ((C)) is a method of making a mold and producing it by injection. The method of injecting an optical pattern directly into a mold and injecting a stamper (thin metallic plate) with an optical pattern from the outside is applied to the mold. There is a way to install. This injection method has a disadvantage in that the mold cost is high because a mold using expensive special steel is required because the mold must be able to withstand thousands of tons of pressure in the manufacturing process. In addition, there is a problem in that it is difficult to manufacture a light guide plate used for an LED which is rapidly emerging as a next-generation light source because it cannot manufacture a light guide plate in a thin film form by the injection method.

Finally, the laser processing method (Figure 3) is a method of fabricating PMMA plate by specification and then scanning the laser beam onto the surface of PMMA plate to imprint the designed optical pattern on the surface. Although it claims to be a processing method, the cost of the equipment is expensive, and it is difficult to form a uniform optical pattern due to etching while reciprocating the laser beam against the surface of the light guide plate material. In particular, in consideration of the structure in which the lamp, which is a light source, is disposed at the edge portion of the light guide plate, in order to secure high luminance at the center of the light guide plate, it is preferable that the optical pattern at the center of the light guide plate is formed with a high density. There is a problem that is difficult to form.

The present invention was developed to improve the problems of the prior art as described above, the manufacturing process of the light guide plate for the backlight unit that can form a uniform optical pattern, the process step, time and cost is reduced compared to the conventional manufacturing method It is an object to provide a method and a light guide plate thereof.

The present invention for achieving the above object is a method of manufacturing a light guide plate for a backlight unit for processing a light guide plate material to form a light guide plate constituting the backlight unit of the liquid crystal display device, and to form an optical pattern on the surface of the light guide plate material. And continuously extruding the light guide plate material into a plate shape, pressing the extruded material surface of the extruded light guide plate material by pressing means having an optical pattern to form an optical pattern on the surface of the extruded material, and then cutting the extruded material into the size of an individual light guide plate. Thus, the light guide plate is manufactured in a consistent continuous process.

In the above configuration, as the pressing means, a rotary roller, a press panel, or a D-shaped roll having an optical pattern formed on the surface to be in contact with the surface of the extruded material can be used. In particular, it is preferable to use for the pressing means that the optical pattern in the center portion is formed at a higher density than the optical pattern in the outer portion.

On the other hand, the present invention provides a light guide plate for a backlight unit manufactured by the manufacturing method as described above.

In the manufacturing method of the present invention configured as described above, the light guide plate is manufactured in a consistent continuous process from extrusion of the light guide plate material to optical pattern formation and cutting, so that the number of processes is high and the manufacturing time is high compared to conventional methods. This simplifies and reduces manufacturing time, greatly improving productivity.

In addition, since the optical pattern is formed in the light guide plate according to the present invention by the pressing process by the pressing means immediately after extrusion, the optical patterns are neatly formed throughout the light guide plate, so that no traces such as scars remain on the light guide plate when the optical pattern is formed. As a result, uniform luminance is obtained at all portions of the light guide plate. Therefore, the light guide plate of the present invention has an effect of contributing to providing a backlight unit of excellent quality that emits planar light of uniform brightness.

1 is a cross-sectional view showing the configuration of a backlight unit.
2 is a view showing a conventional light guide plate manufacturing method.
3 is a view showing a method of manufacturing a light guide plate according to the present invention.
4 is a view illustrating a state in which an optical pattern is formed on an extruded material of a light guide plate using a rotating roller which is an example of a pressing means applied to the manufacturing method of the present invention.
5 is a view showing a press panel as another example of the pressing means applied to the manufacturing method of the present invention.
It is a figure which shows the D-shaped roll which is another example of the press means applied to the manufacturing method of this invention.
FIG. 7 is a diagram illustrating a state in which an optical pattern is formed on an extruded material of a light guide plate using the D roll of FIG. 6.
8 illustrates an optical pattern of a light guide plate manufactured according to the manufacturing method of the present invention.
9 is a photograph showing an optical pattern of a light guide plate manufactured by a conventional laser processing method.
FIG. 10 is an enlarged photograph of the optical pattern of FIG. 9.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it should be understood that the following embodiments are provided so that those skilled in the art can understand the present invention without departing from the scope and spirit of the present invention. It is not.

3 is a view illustrating a method of manufacturing a light guide plate according to the present invention. In the present invention, an acrylic resin, that is, a material of the light guide plate, that is, PMMA (PolyMethoy MethAcryl) is continuously extruded into a plate shape to manufacture a light guide plate. same.

First, the light guide plate material (ie, PMMA: 10) supplied to the extruder 110 is continuously extruded into a plate shape having a thickness corresponding to the thickness of the light guide plate product. At this time, the extruded extruded material 11 is not cooled in a completely solidified state.

The optical pattern 11a is formed on the surface of the extruded material 11 thus extruded (that is, the back surface of the light guide plate opposite to the light exit surface in the backlight unit). Formation of the optical pattern 11a with respect to the extruded material 11 uses the press means 120 in which the optical pattern same as the optical pattern to form is imprinted. That is, the pressing means 120 may use those illustrated in Figs. 4 to 6, which will be described later.

The extruded material 11 having the optical pattern 11a formed by the pressing means 120 is cut into the size of the individual light guide plate by using the cutter 130, thereby completing the light guide plate 11 'having the optical pattern 11'a. do.

As described above, in the present invention, the light guide plate material 10 is continuously extruded through the extruder 110, and the optical pattern 11a is applied to the extruded material 11 of the light guide plate material 10 that is extruded by using the pressing means 120. After forming, the light guide plate 11 'is finished by cutting according to the standard, thereby greatly simplifying the manufacturing process of the light guide plate 11' and greatly reducing the manufacturing time.

That is, in the conventional post-cutting printing method, the inkjet printing method, the injection method, the laser processing method, and the like, which have been described in the above description of the background art, the PMMA sheet used as the light guide plate material is manufactured to meet individual specifications through a separate manufacturing process. Next, since the optical pattern must be formed in the optical pattern forming line, there is a problem in that the number of processes is large and the manufacturing time is long. However, in the present invention, since the light guide plate is manufactured in a consistent continuous process from extrusion of the light guide plate material to formation and cutting of the optical pattern, this problem is remarkably improved.

On the other hand, the extruded material 11 from which the light guide plate material 10 is extruded may be cooled to a temperature that does not interfere with the formation of the optical pattern before pressurizing it by the pressing means 120 to form the optical pattern, or extrusion It may be cooled in a state where it is completely solidified after pressing by the pressurizing means 120 without performing cooling immediately after cutting to the size of the individual light guide plate.

Next, a specific example of the pressing means 120 mentioned above will be described.

First, FIG. 4 shows an example of using the rotary roller 121 as the pressing means 120. That is, the optical pattern 121a is formed on the outer circumferential surface of the rotary roller 121 which comes into contact with the surface of the extruded material 11, and the rotary roller 121 which rotates with respect to the surface of the extruded material 11 is extruded material 11. The optical pattern 11a is formed by pressing the surface of. In order to have the optical pattern of the same shape for each individual light guide plate, it is preferable that the circumference of the rotating roller 121 is made with the size corresponding to the length of an individual light guide plate.

5 shows an example in which the press panel 122 is used as the pressing means 120. The bottom part of the press panel 122 has the same size as that of the individual light guide plate and an optical pattern to be imprinted on the surface of the extruded material. 122a) is formed, and the optical pattern is carved while lifting up and down against the extruded material.

6 and 7 illustrate an example in which an optical pattern is formed on the extruded material 11 using the D-shaped roll 123 having a 'D' shape as the pressing means 120. That is, the D-shaped roll 123 has a curved surface to be in contact with the surface of the extruded material 11, and the optical pattern 123a is formed on the curved surface. Therefore, the optical pattern is imprinted on the surface of the extruded material 11 while rolling the curved portion of the D-shaped roll 123 against the surface of the extruded material 11.

On the other hand, the optical pattern (121a, 122a, 123a) provided in the pressing means (120: 121, 122, 123a) is preferably formed with a higher density than the center portion. That is, in the backlight unit, since the light source lamp is disposed at the edge portion of the light guide plate, the light incident from the light source lamp to the light guide plate is lowered in luminance due to distance from the center of the light guide plate due to the distance from the center of the light guide plate. The incident light should be more diffusely reflected. Therefore, since the diffuse reflectivity is improved only when the optical pattern at the center of the light guide plate is formed at a high density, the optical patterns 121a, 122a, and 123a of the pressing means 120 are preferably formed at a higher density at the center than at the outer portion. Therefore, in the present invention, in applying the pressing means 120, such as the rotary roller 121, the press panel 122 or the D-shaped roll 123, the optical pattern (121a, 122a, 123a) at the center of the outer portion Use a high density of.

Next, FIG. 8 is a view showing the optical pattern of the light guide plate manufactured according to the manufacturing method of the present invention as described above, Figure 9 and Figure which is a photograph showing the optical pattern of the light guide plate manufactured by a conventional laser processing method It compares with 10 and demonstrates.

First, as shown in FIG. 9, when the optical pattern of the light guide plate manufactured by the conventional laser processing method is used, it can be seen that the optical patterns in one row and the optical patterns in the other row are not aligned with each other and have an irregular arrangement. . In addition, as can be seen in Figure 10, one end of each of the optical patterns (upper end or lower end of each optical pattern on the drawing) it appears that the traces remain as a scar due to the etching by the laser beam. As described above, the light guide plate manufactured by the laser processing method has a problem in that luminance of the entire light guide plate is not uniform due to irregular optical pattern arrangements and traces of laser processing such as scars.

On the other hand, as shown in Fig. 8, in the light guide plate manufactured according to the manufacturing method of the present invention, the optical pattern 11 'is pressed while pressing means in which the optical pattern is imprinted against the extruded material of the light guide plate material extruded from the extruder. Since the a) is formed, the optical patterns 11'a are uniformly formed over the light guide plate 11 ', and no traces such as scars remain on the light guide plate 11' when the optical pattern is formed. Therefore, in the present invention, the light guide plate can be manufactured with uniform luminance at the entire site.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, This is possible.

10: light guide plate material 11: extruded material of the light guide plate material
11a, 11'a: optical pattern 11 ': light guide plate
110: extruder 120: pressurizing means
121: rotating roller 122: press panel
123: D-shaped roll 121a, 122a, 123a: optical pattern
130: cutter

Claims (6)

In the manufacturing method of the light guide plate for a backlight unit which processes a light guide plate material in order to manufacture the light guide plate which comprises the backlight unit of a liquid crystal display device, and forms an optical pattern on the surface of the said light guide plate material,
By continuously extruding the light guide plate material into a plate shape, by pressing the surface of the extruded material of the light guide plate material extruded by a pressure means formed with an optical pattern to form an optical pattern on the surface of the extruded material, and then cutting the extruded material to the size of the individual light guide plate And manufacturing a light guide plate in a consistent continuous process.
The method of claim 1,
And a rotating roller having an optical pattern formed on an outer circumferential surface of the extruded material to be in contact with the surface of the extruded material.
The method of claim 1,
The pressurizing means is a manufacturing method of a light guide plate for a backlight unit, characterized in that the use of a press panel having an optical pattern formed on the surface to be in contact with the surface of the extruded material.
The method of claim 1,
The pressing means is a method for manufacturing a light guide plate for a backlight unit, characterized in that the D-shaped roll formed with an optical pattern formed on the surface to be in contact with the surface of the extruded material.
The method of claim 1,
The pressing means is a method for manufacturing a light guide plate for a backlight unit, characterized in that the optical pattern in the center portion is formed with a higher density than the optical pattern in the outer portion.
The light guide plate for backlight units manufactured by the manufacturing method of any one of Claims 1-5.

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