KR20120139278A - Light guide plate and backlight unit assembly comprising the same - Google Patents

Abstract

PURPOSE: A light guide plate and a backlight unit assembly including the same are provided to improve pattern etching machinability by improving the shape stability of a pattern when the pattern is formed on a heat resistance resin layer. CONSTITUTION: A light guide plate includes a base layer(1), a structure layer(2) and a heat resistant resin layer(3). The structure layer is formed on the base layer. The heat resistance resin layer is formed on the lower surface of the base layer and includes a pattern. The base layer and the structure layer are made of styrene methylmethacrylate.

Description

Light Guide Plate and Backlight Unit Assembly Comprising the Same

The present invention relates to a light guide plate used in a liquid crystal display and a backlight unit assembly including the same.

BACKGROUND ART A liquid crystal display used as an optical display element is an indirect light emission method in which an image is controlled by controlling a transmittance of an external light source, and a backlight unit, which is a light source device, is used as an important component for determining characteristics of a liquid crystal display.

In the backlight unit (hereinafter, abbreviated as "BLU"), a light source such as a Cold Cathode Fluorescent Lamp (CCFL) or an External Electrode Fluorescent Lamp (EEFL) may be used. The light emitted by the light sequentially passes through the light guide plate or the diffusion plate, the diffusion sheet, and the prism sheet to reach the liquid crystal panel.

Here, the light guide plate is used for the edge type of the light source is emitted from the side of the two types divided by the light source position of the backlight unit (BLU) used as the light emitting device of the liquid crystal display (LCD) device, the light is transmitted to the front through the light guide plate. In particular, it must be excellent in transparency, and there is a feature that can not be applied when there is a color problem.

According to the size of the existing LGP market, the small (mobile display) market mainly uses PCs, and in the medium and large markets, PMMA is mainly used. While PC is excellent in optical and physical characteristics, it is very expensive and difficult to use in the medium and large market. PMMA is cheaper than PC, but in recent years, demand has surged, resulting in unit price increase and supply and demand imbalance, leading to development of alternative raw materials. Compared to the conventional PMMA, the heat generated during the laser pattern etching process causes a problem of machining defects, which is urgently needed to solve the problem.

The present invention is to provide a light guide plate having a low cost and excellent laser pattern etching process as a conventional light guide plate for replacing the PMMA light guide plate.

Accordingly, the present invention provides a substrate layer as a first preferred embodiment; A light guide plate including a heat-resistant resin layer having patterns arranged on a bottom surface of the base layer, wherein the base layer provides a light guide plate made of styrene methyl methacrylate (MS).

On the upper surface of the substrate layer according to the embodiment, the structure layer in which the pattern is arranged may be formed.

The base layer and the structural layer according to the embodiment is MS (Styrene Methyl Methacrylate); And PMMA, polycarbonate resins, polystyrene resins, acrylic resins, olefin resins, copolymer resins thereof, and mixtures thereof.

The structural layer according to the embodiment may have a pattern formed in the form of a prism having a triangular cross section, a prism having a vertex round with a cross section of 0.1 to 3.0 mm, and a lenticular shape.

Heat-resistant resin layer according to the embodiment may be a material of the optical resin having a heat resistance (Tg) 110 ℃ or more.

Optical resin having a heat resistance (Tg) 110 ℃ or more according to the embodiment may be a resin selected from PMMA, polycarbonate resins, acrylic resins and mixtures thereof.

The pattern formed on the heat-resistant resin layer according to the embodiment may be characterized in that the cross-section is an intaglio pattern having a shape selected from the group consisting of hemispheres, triangles and trapezoids.

The present invention also provides a backlight unit assembly including the light guide plate as a second preferred embodiment.

1 is an example of a light guide plate according to an embodiment of the present invention.
FIG. 2 is an example of a lower surface laser pattern etched shape (a) processed on a light guide plate manufactured by an example method and a lower surface laser pattern etched shape processed on a light guide plate manufactured by a comparative example method.
* Explanation of the main symbols in the drawings *
1: base material layer 2: structural layer
3: heat-resistant resin layer 10: light guide plate

Hereinafter, the present invention will be described in more detail.

The present invention relates to a light guide plate comprising a substrate layer, a structural layer, and a heat resistant resin layer comprising MS (styrene methyl methacrylate) and a heat resistant resin, thereby improving laser etching processability when forming a pattern of the heat resistant resin layer. Specifically, a substrate layer; A structural layer formed on an upper surface of the base layer; And a heat resistant resin layer including a pattern formed on the bottom surface of the base layer, wherein the base layer and the structural layer are made of Styrene Methyl Methacrylate (MS). It is about.

MS is a lightweight and inexpensive thermoplastic, and in the present invention, by using MS as the main material of the light guide plate, the MS can provide a light guide plate having the same physical properties as that of the conventional PMMA light guide plate and having a low cost.

In the light guide plate including the base layer, the structural layer, and the heat resistant resin layer, MS may be used as the main material of the base layer and the structural layer, and together with the MS, PMMA, polycarbonate resin, polystyrene resin, acrylic resin, olefin resin and these At least 1 sort (s) of resin chosen from the copolymer resin of can be used.

As mentioned above, the light guide plate made of MS as a main material is to provide a light guide plate that can solve the problem of non-uniformity in pattern formation due to laser heating during etching.

In the present invention, the heat-resistant resin used in the heat-resistant resin layer may be an optical resin having a heat resistance (Tg) of 110 ° C. or more, which is the heat resistance of PMMA, and specifically, may be PMMA, polycarbonate resin, acrylic resin, and mixtures thereof. Can be.

For example, in the light guide plate according to the present invention, the structure layer and the base layer are made of a conventional light guide plate material, and the heat resistant resin layer is a light guide plate made of PMMA, or the structure layer and the base layer are made of a conventional light guide plate material, and The resin layer may be a light guide plate made of a polycarbonate resin.

On the other hand, the structural layer included in the light guide plate may be a pattern is formed, the pattern is selected from the group consisting of a prism of the cross-section is a triangle, a prism of the triangle having a vertex angle round of 0.1 ~ 3.0㎜ and a lenticular Can be. The acrylic layer or the olefin resin may be applied as the structural layer forming resin to form the pattern by UV or thermosetting. In this case, the groove may be inscribed using a pre-indented engraving means. have.

On the other hand, the heat-resistant resin layer formed on the lower surface of the base layer may include a pattern formed by laser etching or mechanical etching in consideration of the improvement in brightness and the uniformity of light emitted to the front surface. If the pattern is not etched in the lower part of the light guide plate, the light from the light source continues to be reflected in total reflection inside the light guide plate, and the light is not emitted out of the light guide plate. . Therefore, it may be desirable to perform pattern etching on the heat-resistant resin layer because a pattern pattern is formed and the reflected light matches the etching pattern so that the path of the light exits to the front side.

The pattern engraved in the heat-resistant resin layer may be an intaglio pattern having a cross section whose shape is selected from the group consisting of hemispheres, triangles, and trapezoids, wherein the triangles and trapezoids have angles of 65 degrees or less at the sides of which the vertices are round. It may be in the form. In addition, the diameter of 10 ~ 100㎛ or having a ratio between the length and the width of 1 ~ 10 while the depth of 10 ~ 100㎛ may be in the form of getting wider or narrower.

The pattern engraved in the heat-resistant resin layer having the form as described above reflects the light incident from the side to the front, thereby improving the luminance by the light condensing effect.

Such a light guide plate may be obtained by coextrusion of a base material layer, a structural layer, and a heat resistant resin layer.

In addition, when the light guide plate is applied to a backlight unit assembly, particularly an edge type BLU in which an LED light source is arranged, the light transmission plate may be more uniformly and smoothly due to the stabilization of the pattern etching.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to the following Examples.

<Comparative Example>

400 kg / hr of MS (NSC, MS300) was introduced into an extruder having a screw diameter of 120 mm and extruded at 220 to 240 ° C. to prepare a light guide plate having an MS 2.0T base layer and a structure layer formed on the top surface of the base layer.

<Examples>

4 Kg / hr PMMA (LGMMA, HP202) was co-extruded with the heat resistant resin layer on the lower surface of the base material layer of the light-guide plate manufactured in the comparative example, and the light-guide plate was manufactured by the same method.

After the laser pattern etching process of the heat resistant resin layer of the light guide plate obtained from the said Example and the comparative example in the cross-sectional form of the pattern of Table 1, the shape uniformity and luminance uniformity of the pattern were measured, and the result is shown in Table 2.

(1) uniformity measurement

After the light guide plate manufactured in the above Examples and Comparative Examples was randomly sampled by an optical microscope to measure pattern shape uniformity after laser pattern etching, the aspect ratio of the laser pattern etching shape was measured to calculate the deviation between samples. Compared, stacked on the 42 ″ backlight unit assembly with LED Edge type light source for luminance uniformity measurement, and using a luminance meter (model name: BM-7, TOPCON Japan), 10 points horizontally and 7 points vertically A total of 17 points were measured, and the standard deviation of luminance was calculated, and the luminance uniformity was compared.

Cross section of the pattern Comparative Example 1 hemisphere 15㎛ diameter Comparative Example 2 hemisphere 80㎛ diameter Comparative Example 3 Oval Depth: Width = 50 μm: 10 μm Comparative Example 4 Oval Depth: Width = 10 μm: 50 μm Comparative Example 5 triangle Vertex part is round Comparative Example 6 hemisphere 5㎛ diameter Comparative Example 7 hemisphere 110㎛ diameter Example 1 hemisphere 15㎛ diameter Example 2 hemisphere 80㎛ diameter Example 3 Oval Depth: Width = 50 μm: 10 μm Example 4 Oval Depth: Width = 10 μm: 50 μm Example 5 triangle Vertex part is round

Aspect ratio deviation Average brightness Luminance deviation Comparative Example 1 0.7528 4,128 268.95 Comparative Example 2 0.9422 4,987 396.24 Comparative Example 3 0.6235 4,356 212.30 Comparative Example 4 0.6842 3,684 186.73 Comparative Example 5 0.5128 4,867 368.48 Comparative Example 6 0.4215 3,176 162.87 Comparative Example 7 1.1038 5,632 562.49 Example 1 0.2158 4,387 116.93 Example 2 0.3124 4,821 143.68 Example 3 0.2561 4,828 136.78 Example 4 0.2422 4,574 109.85 Example 5 0.2954 4,761 125.32

From the results in Table 2, the light guide plate coextruded using MS and the heat-resistant resin (FIG. 2A) has a reduced aspect ratio deviation of the laser pattern etching processing shape compared to the light guide plate extruded only with MS (FIG. 2B), thereby improving luminance uniformity and processability. Appeared.

As a result, the use of inexpensive raw materials using various light guide plate materials beyond the limited range in which raw materials other than resins having excellent heat resistance such as PMMA or polycarbonate are not used in manufacturing the light guide plate which requires the etching process of the lower surface of the light guide plate through the present invention. And it can be seen that you can escape from difficulties such as lack of raw materials.

Claims (8)

A base layer; And
A light guide plate including a heat-resistant resin layer in which a pattern is arranged on a lower surface of the base layer,
The base layer is a light guide plate, characterized in that made of styrene methyl methacrylate (MS, Styrene Methyl Methacrylate).
The method of claim 1,
The light guide plate, characterized in that the upper surface of the substrate layer is a structural layer arranged pattern.
The method according to claim 1 or 2,
Base layer or structural layer
Light guide plate made of a resin selected from MS (Styrene Methyl Methacrylate), PMMA, polycarbonate resin, polystyrene resin, acrylic resin, olefin resin and copolymer resins thereof.
The method of claim 1,
The structural layer is a light guide plate, characterized in that formed in the pattern of the shape selected from the group consisting of a prism having a triangular cross section, a prism having a vertex angle round of the cross section of 0.1 ~ 3.0mm and lenticular.
The method of claim 1,
The heat-resistant resin layer is a light guide plate, characterized in that the material is an optical resin having a heat resistance (Tg) of 110 ℃ or more.
The method of claim 5,
The optical resin having a heat resistance (Tg) of 110 ° C. or more is selected from PMMA, polycarbonate resin, acrylic resin, and mixtures thereof.
5. The method of claim 4,
The pattern formed on the heat-resistant resin layer is a light guide plate, characterized in that the cross-section is a negative pattern having a shape selected from the group consisting of hemispheres, triangles and trapezoids.
A backlight unit assembly comprising the light guide plate of any one of claims 1, 2, and 3-7.

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