KR20090065834A - Light guide plate for backlight unit, stamp for light guide plate and method for manufacturing stamp - Google Patents

Abstract

A light guide plate for backlight, a stamp for the light guide plate, and a stamp manufacturing method are provided to form respectively a complex micro pattern capable of diffusing and concentrating light to the upper and lower sides of the light guide plate, thereby removing an optical sheet while improving the luminance of backlight. A light guide plate(100) for backlight includes a prism pattern(110) and a micro lens pattern(150). As to the prism pattern, floor(111) and valley(113) are repeatedly formed in the upper side of the light guide plate. The micro lens pattern is formed in one of an inclined surface between the floor of and valley of the prism pattern and valley between floor and floor at least.

Description

LIGHT GUIDE PLATE FOR BACKLIGHT UNIT, STAMP FOR LIGHT GUIDE PLATE AND METHOD FOR MANUFACTURING STAMP}

The present invention relates to a light guide plate and a stamp for manufacturing a light guide plate, and in particular, a light guide plate for a backlight, a light guide plate stamp, which repeatedly forms a prism pattern having floors and valleys formed on an upper surface of the light guide plate or a stamp, and forms a microlens pattern on the prism pattern. A stamp manufacturing method.

Recently, as the information society develops, the demand for display devices is increasing in various forms. Accordingly, liquid crystal display (LCD), plasma display panel (PDP), electro luminescent display (ELD), and vacuum fluorescent display (VFD) Various flat panel display devices have been researched and developed.

Here, LCD has been widely used as a mobile flat panel display due to its excellent image quality, light weight, thinness, and low power consumption, and is particularly used as a laptop, computer monitor, and television display. However, LCDs do not emit light by themselves and require a separate external light source to realize high quality images. Therefore, the LCD structure further includes a backlight unit as a light source of the liquid crystal display panel in addition to the liquid crystal display panel, so that the backlight unit uniformly supplies a high brightness light source to the liquid crystal display panel, thereby realizing high quality images.

In general, a backlight of a liquid crystal display is classified into an edge-lighting and a direct-lighting backlight according to a method of disposing a light source, and as a light source, a CCFL (Cold Cathode Fluorescent Lamp), Cylindrical fluorescent lamps such as Hot Cathode Fluorescent Lamp (HCFL) and External Electrode Fluorescent Lamp (EEFL), Light Emitting Diode (LED) devices, Electro Luminescence (EL) devices and the like are used.

Due to its relatively thin thickness, the side backlight is mainly used for LCDs for thinning portable communication devices and laptops, and the direct type backlight is mainly used for LCDs for large screens such as television displays and computer monitors due to its high light efficiency. Is used.

As shown in FIG. 1, the general structure of the conventional side-type backlight is shown in FIG. 1, the light guide plate 10, the fluorescent lamp 20, the lamp reflector 25, the reflector plate 30, the diffusion sheet 40, the first and the like. The second prism sheets 51 and 55 and the protective sheet 60 are configured.

In the backlight of this structure, light emitted from the fluorescent lamp 20 is incident on the light guide plate 10, and the light guide plate 10 is converted into a uniform surface light source by total internal reflection, scattering and refracting the light of the fluorescent lamp incident on the light guide source. In addition, the lower reflection plate 30 reflects the light to the upper side of the light guide plate 10.

In addition, the diffusion sheet 40 and the first and second prism sheets 51 and 55 positioned on the light guide plate 10 may diffuse, condense, and scatter light again to improve optical characteristics such as brightness and uniformity. By emitting to the liquid crystal display panel (not shown) located on the upper side, it serves as a backlight.

The principle of changing the light path of the light guide plate is to use the refraction or reflection of light, and the injection molding method is a general method for manufacturing the light guide plate. The injection molding method is a method of injection molding the entire surface at a time so that a minute optical pattern is formed on the lower surface or the upper and lower surfaces of the light guide plate, and the light provided from the side is reflected or refracted by the shape of the optical pattern to progress toward the upper surface. It is a way.

The most important thing in the injection molding method of manufacturing the light guide plate is the production of a mold having a fine pattern to be transferred to the light guide plate, that is, a stamp or a mold. Conventionally, these patterns are manufactured by stamping a micropattern through a machine tool processing, electroplating, and printing method.

Recently, the backlight has been developed to focus on high brightness, thinning, and low power, and for this purpose, a research on complexing a light guide plate and an optical sheet is being conducted. Conventional light guide plate is not limited to the function of providing a linear light source as a surface light source, and the function of the optical sheet is compounded by forming a fine pattern on the upper and lower surfaces of the light guide plate. The light guide plate, which is a core part of the backlight device, was initially produced through a printing pattern. However, since a non-printing light guide plate and a prismless light guide plate were developed, cost reduction and a composite of sheet functions have been actively conducted.

The cross-sectional structure of the conventional light guide plate 10 to which the composite micropattern is applied is shown in FIG. 2, and the light guide plate 10 gradually moves from the light incident surface 11 on which the fluorescent lamp 20 is located to the light incident surface 19. The prism pattern 17 is formed on the upper surface of the light incident surface 11 from the light incident surface 11 to form a wedge shape having a thin thickness, and a diffuse reflection pattern 15 having a dot or V-cut shape is formed on the lower surface thereof. .

Thus, by applying a fine pattern directly to the upper and lower surfaces of the light guide plate of the backlight, the overall backlight device is further reduced in weight and thickness.

The wedge-shaped light guide plate 10 is to add the prism pattern 17 or diffuse reflection pattern 15 to the upper and lower surfaces to combine the function of the prism sheet and the diffusion sheet function, thereby reducing the manufacturing cost of the thin film and the backlight, Since the pattern to be transferred to is a shape having optical characteristics, the stamp of a complex micropattern has difficulty in manufacturing.

In addition, even if it is possible to form the composite pattern (15, 17) on the upper and lower surfaces of the light guide plate 10, as the diffusion sheet or the first and second prism sheet still need to be disposed on the top, the manufacturing cost of the backlight is not reduced, the assembly process There was still a complicated problem.

An object of the present invention is to form a diffuse reflection pattern on the lower surface of the light guide plate, repeatedly forming a prism pattern formed with the floor and the valley on the upper surface of the light guide plate and to the slope between the floor and the valley of the prism pattern or / and the valley between the floor and the floor The present invention provides a backlight light guide plate, a light guide plate stamp, and a stamp manufacturing method capable of improving scattering and condensing characteristics of incident light.

Another object of the present invention is to form a complex fine pattern for diffusing, condensing, and scattering light on the upper and lower surfaces of the light guide plate, thereby improving the brightness of the backlight and removing the optical sheet, and a light guide plate for a light guide plate stamp And a method for producing a stamp.

Backlight light guide plate of the present invention for achieving the above object, the prism pattern is formed on the upper surface of the light guide plate repeatedly grooves and valleys; And a microlens pattern formed on at least one of the slope between the floor and the valley of the prism pattern and the valley between the floor and the valley.

Specifically, the light guide plate is characterized in that the side of the light source is disposed on the side, the microlens pattern is characterized in that the embossed or intaglio shape, the microlens pattern is a light incident surface from the light incident surface of the light guide plate by light simulation The density toward the side, or toward each corner surface side is characterized in that formed.

Stamp for producing the light guide plate of the present invention for achieving the above object, the prism pattern is formed on the upper surface of the stamp from the light incident surface to the side of the light incident surface repeated grooves and valleys; And a microlens pattern formed on at least one of the slope between the floor and the valley of the prism pattern, and the valley between the floor and the valley.

Specifically, the microlens pattern is characterized in that the intaglio or embossed shape.

Method of manufacturing a stamp for manufacturing the light guide plate of the present invention for achieving the above object, the step of applying a photoresist on the upper surface of the base material on which the prism pattern is formed; Exposing and developing the photoresist-coated base material to form a micro pattern on top of the prism pattern; Heating the base material to process the micropattern into a microlens pattern; Laminating and plating a metal layer on an upper surface of the prism pattern and the microlens pattern of the base material; And separating the metal layer from the base material to complete the metal stamp on which the pattern of the base material is transferred to the metal layer.

Specifically, the plating method of the metal layer is characterized in that the electroforming plating method, the metal layer on the upper surface of the prism pattern and the microlens pattern of the base material is characterized in that the nickel (Ni), when heating the base material It is characterized by heating at a temperature of 160 ° C to 180 ° C.

The microlens pattern is characterized in that its density is formed as it goes from the light incident surface of the light guide plate toward the light incident surface side or toward each corner surface side.

Stacking a metal layer on the finished metal stamp using an electroforming plating method; And separating the metal stamp and the metal layer to complete a second stamp having a piece (embossed) having a shape different from that of the metal stamp.

The prism pattern has a pitch of approximately 20 to 50 µm, a height of approximately 10 to 20 µm, and a microlens pattern having a diameter of approximately 5 to 20 µm and a height of approximately 5 to 20 µm. It is done.

As described above, the present invention forms a diffuse reflection pattern on the lower surface of the light guide plate, repeatedly forming a prism pattern having a floor and a valley formed on the upper surface of the light guide plate, and between the slope and / or the floor between the floor and the valley of the prism pattern. By forming the microlens pattern in the valley of the light scattering and condensing characteristics of the incident light can be improved, there is an advantage that can increase the brightness of the backlight.

In addition, by forming a composite micropattern for diffusing, condensing, and scattering light on the upper and lower surfaces of the light guide plate, the brightness of the backlight and the optical sheet can be removed, thereby reducing the manufacturing cost of the backlight. have.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3A to 3D illustrate a light guide plate for a backlight according to an embodiment of the present invention, wherein a diffuse reflection pattern 101 such as a dot or a V-CUT formed on a bottom surface of the light guide plate 100 and a light guide plate 100 are provided. The upper surface includes a prism pattern 110 in which the ridges 111 and the valleys 113 are repeatedly formed from the light incident surface to the light incident surface side, and a microlens pattern 150 formed on the top of the prism pattern 110.

3A illustrates a microlens pattern 150 formed on the prism pattern 110 of the light guide plate 100. The microlens pattern 150 includes a triangular prism pattern 110 having a ridge 111 and a valley 113. Embossed on the inclined surface between the floor 111 and the valley 113 of the). The microlens pattern 150 of the embossed pattern serves to scatter and diffuse a light source emitted through the prism pattern 110, thereby having the effect of a diffusion sheet.

The microlens pattern 150 may be formed to have a higher density from the light incident surface of the light guide plate toward the light incident surface side or toward each corner surface by light simulation.

On the other hand, FIG. 3B illustrates that the intaglio microlens pattern 160 is formed on the inclined surface between the ridge 111 and the valley 113 of the prism pattern 110. Likewise, when the light is focused in the lateral direction and viewed from the front of the backlight, the light can be simultaneously focused and diffused, thereby increasing the viewing angle and screen quality.

3C illustrates that the microlens pattern 170 is embossed on the valley 113 between the floor 111 and the adjacent floor 111 of the prism pattern 110, and the microlens pattern 170 of the relief pattern is By scattering and diffusing the light source emitted through the prism pattern 110, it has the effect of a diffusion sheet.

On the other hand, FIG. 3D illustrates that the negative microlens pattern 180 is formed in the valley 113 between the floor 111 and the floor 111 of the prism pattern 110, and the microlens pattern 180 of the negative pattern is formed. The light condenses in the lateral direction like a prism, and when viewed from the front of the backlight, the light can be condensed and diffused simultaneously, thereby increasing the viewing angle and screen quality.

Therefore, the light guide plate 100 according to the present invention causes light condensing and scattering as the prism pattern 110 and the microlens patterns 150, 160, 170, or 180 are formed in a complex manner. Accordingly, since the light guide plate 100 may implement the functions of the diffusion sheet and the prism sheet of FIG. 1, the diffusion sheet and the plurality of prism sheets disposed on the top surface of the light guide plate 100 may be selectively or removed. have.

In FIGS. 3A to 3D, only a single type of microlens pattern is illustrated on the prism pattern 110 for convenience of description. However, according to the result of optical simulation for each product to which the light guide plate 100 is applied, the embossment and intaglio are applied to the prism pattern 110. May be formed by mixing the microlens patterns 150, 160, 170, or 180. Of course, it is also possible to form the microlens patterns 150, 160, 170, or 180 simultaneously on the slope and the valley of the prism pattern 110.

The microlens patterns 150, 160, 170, or 180 formed on the prism pattern 110 may have different sizes and densities for each location according to the results of optical simulation for each product, and thus, the microlens patterns 150, The light guide plate 100 having 160, 170 or 180 shows better light condensing and scattering effects in the side type type backlight than the direct type type.

The prism pattern 110 has a pitch of approximately 20 to 50 µm and a height of approximately 10 to 20 µm, while a microlens pattern formed on an upper end of the prism pattern 110 ( 150, 160, 170, or 180 have a diameter of about 5 to 20 μm and a height of about 5 to 20 μm, so that the microlens pattern 150 is considerably smaller than the prism pattern 110, and thus it is not easy to form. not.

Therefore, in order to form the microlens patterns 150, 160, 170, or 180 on the light guide plate 100, it is important to manufacture a stamp (mould) for manufacturing the light guide plate 100, and thus the prism pattern 110 and the microlens The manufacturing process of the stamp on which the pattern 150 is formed will be described below.

FIG. 4 is a flowchart illustrating a manufacturing process of a light guide plate manufacturing stamp according to an embodiment of the present invention. The manufacturing process of the stamp will be described with reference to the process diagrams of FIGS. 5A to 5H.

First, a substrate 200 on which a prism pattern 210 is formed is prepared. The base material 200 is a material such as glass for producing the stamp 300. As will be described below, the pattern 300 formed on the base material 200 is transferred to the stamp 300 to complete the stamp 300. Done. In addition, the prism pattern 210 formed on the base material 200 may be a type continuously formed from a light incident surface to a light incident surface, or may be a type in which vertical or horizontal prism patterns are repeatedly formed, and such a prism pattern 210 may be formed. Since it corresponds to the known art, the manufacturing process for the prism pattern 210 is omitted.

Subsequently, in the base material 200 on which the prism pattern 210 is formed, a photoresist (PR) is applied to the upper surface of the prism pattern 210 as shown in FIG. 5A (S1).

After applying the photoresist to the upper surface of the prism pattern 210, as shown in Figure 5b is placed on the upper surface of the substrate (Photo Mask) designed the microlens pattern on the upper surface of the base material 200, UV exposure process of exposing ultraviolet rays Perform (S2). The photomask PM is an optical design and is designed to increase the density of the microlens patterns from the light incident portion to the light incident portion, that is, the number of the microlens patterns increases.

When the exposed base material 200 is developed as described above, when the photoresist is positive, as shown in FIG. 5C, all of the photoresist exposed to ultraviolet light is removed, leaving only the portion not exposed to ultraviolet light. ) Is generated (S3).

When the cylindrical micro-pattern 240 is generated as described above, by placing the base material 200 on a heating plate and applying heat of approximately 160 ° C to 180 ° C, the photoresist of the photoresist is reflowed, and FIG. 5D. As shown in FIG. 4, the microlens pattern 250 is implemented on the top surface of the prism pattern 210. That is, when heat is applied to the base material 200, the edge surface of the cylinder having weak surface tension is first melted in the micropattern 240, and the cylinder is processed into a lens shape. In the above, when the heating temperature of the base material 200 is lower than 160 ° C., the micro pattern 240 may not be reflowed and may not be processed into a lens shape. When the heating temperature is higher than 180 ° C., the cylindrical micro pattern 240 ) May melt, so the heating temperature of the base material 200 is preferably about 160 ° C to 180 ° C.

As described above, the microlens pattern 250 is formed on the top surface of the prism pattern 210 of the base material 200 through the process of FIGS. 5A to 5D, and the base material 200 on which the microlens pattern 250 is formed is formed. Look at the process of producing the stamp 300 using the.

After imparting conductivity by depositing a chromium film on the top surface of the base material 200 on which the microlens pattern 250 is formed, a metal layer having a predetermined height as shown in FIG. 5E by using electroforming (hereinafter, referred to as 'electric pole') plating method. 300 is formed (S5). That is, the composite pattern (prism pattern and microlens pattern) of the base material 200 is transferred to the metal layer 300 through the electroplating. Here, the height of the metal layer 300 is a thin layer of about 0.3 to 0.5mm, and the metal plating is most preferably using nickel (Ni). Nickel is suitable for electroplating due to low internal stress.

Subsequently, when the base material 200 and the metal layer 300 electroplated on the upper surface of the base material 200 are separated from each other, as shown in FIG. 5F, the prism pattern 310 and the microlens pattern 350 are intaglio stamped. Production of the 300 is completed (S6). The engraved stamp 300 is used to fabricate the light guide plate 100 in which the prism pattern and the microlens pattern are embossed, as shown in FIGS. 3A and 3C.

Through this process, the microlens patterns 350 are formed on the top surface of the stamp 300, and the microlens pattern 350 is formed on the inclined surface between the floor and the valley of the prism pattern 310, and the floor and the floor. It is formed in at least one of the bones.

5G and 5H illustrate a process of manufacturing an embossed stamp 400 by using an intaglio stamp 300 having a complex pattern engraved therein.

That is, the intaglio stamp 300 is formed by using the electroplating method to form a metal layer 400 having a predetermined height as shown in FIG. 5G. That is, the composite pattern (prism pattern and microlens pattern) of the intaglio stamp 300 is transferred to the metal layer 400 through the electroplating.

Subsequently, when the intaglio stamp 300 and the metal layer 400 electroplated on the upper surface of the intaglio stamp 300 are separated from each other, the prism pattern 410 and the microlens pattern 450 are embossed as shown in FIG. 5H. Production of the formed stamp 400 is completed. The embossed stamp 400 is used to fabricate the light guide plate 100 in which the prism pattern and the microlens pattern are engraved as shown in FIGS. 3B and 3D.

On the other hand, although the manufacturing process of the stamp for forming the diffuse reflection pattern 101 formed on the lower surface of the light guide plate 100 has not been described, the manufacturing process of the stamp for forming the diffuse reflection pattern 101 and the stamp for forming the composite pattern are different. , The stamp for producing the diffuse reflection pattern is not the gist of the present invention, and since a known technique may be used, detailed description thereof is omitted.

The light guide plate 100 having the composite pattern as shown in FIGS. 3A to 3D is formed by using the stamp 300 having the prism pattern 310 and the microlens pattern 350 and the stamp (not shown) having the predetermined diffuse reflection pattern formed thereon. ).

Preferred embodiments of the present invention are disclosed for purposes of illustration, and those skilled in the art will be able to make various modifications, changes and additions within the spirit of the present invention. Additions should be considered to be within the scope of the following claims.

1 is an exploded perspective view showing a backlight device according to the prior art.

2 is a side view showing a light guide plate of the backlight device according to the prior art.

3A to 3D are diagrams illustrating a light guide plate for a backlight according to each embodiment of the present invention.

4 is a flowchart illustrating a manufacturing process of a stamp for manufacturing a light guide plate according to an embodiment of the present invention.

5a to 5h is a view showing a stamp manufacturing process according to an embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

100: light guide plate 101: diffuse reflection pattern

110: prism pattern 150 to 180: microlens pattern

200: Master 210: Prism pattern

250: microlens pattern 300: stamp

310: prism pattern 350: microlens pattern

400: embossed stamp

Claims (13)

A prism pattern in which floors and valleys are repeatedly formed on an upper surface of the light guide plate; And And a microlens pattern formed on at least one of the slope between the floor and the valley of the prism pattern and the valley between the floor and the valley. The method of claim 1, wherein the light guide plate, A light guide plate for a backlight, characterized in that the side light source is disposed on the side. The method according to claim 1 or 2, wherein the microlens pattern, Light guide plate for a backlight, characterized in that the embossed or intaglio shape. The method according to claim 1 or 2, wherein the microlens pattern, A light guide plate for a backlight, characterized in that the density of the light guide plate toward the light-receiving surface toward the side or toward each corner surface formed higher. In the stamp for manufacturing the light guide plate, A prism pattern in which a floor and a valley are repeatedly formed on an upper surface of the stamp from a light incident surface to a light incident surface; And And a microlens pattern formed on at least one of the slope between the floor and the valley of the prism pattern, and the valley between the floor and the valley. The method of claim 5, wherein the microlens pattern, A stamp for a backlit light guide plate, characterized by an intaglio or embossed shape. In the manufacturing method of the stamp which manufactures a light-guide plate, Applying a photoresist to an upper surface of the base material on which the prism pattern is formed; Exposing and developing the photoresist-coated base material to form a micro pattern on top of the prism pattern; Heating the base material to process the micropattern into a microlens pattern; Laminating and plating a metal layer on an upper surface of the prism pattern and the microlens pattern of the base material; And Separating the metal layer from the base material to complete a metal stamp on which the pattern of the base material is transferred to the metal layer. The method of claim 7, wherein the plating method of the metal layer, A method for manufacturing a stamp for a light guide plate, characterized in that the electroforming plating method. The method according to claim 7 or 8, And a metal layer on the upper surface of the prism pattern and the microlens pattern of the base material is nickel (Ni). The method according to claim 7 or 8, The method of manufacturing a stamp for a light guide plate, characterized in that when heating the base material to a temperature of approximately 160 ℃ to 180 ℃. The method of claim 7 or 8, wherein the microlens pattern, The method of manufacturing a stamp for a light guide plate, characterized in that its density is formed as it goes from the light incident surface of the light guide plate toward the light incident surface side or toward each corner surface side. The method according to claim 7 or 8, Stacking a metal layer on the finished metal stamp using an electroforming plating method; And separating the metal stamp and the metal layer to complete a second stamp having a piece (embossed) having a shape different from that of the metal stamp. The method according to claim 7 or 8, The prism pattern has a pitch of approximately 20 to 50 µm, a height of approximately 10 to 20 µm, and a microlens pattern having a diameter of approximately 5 to 20 µm and a height of approximately 5 to 20 µm. The manufacturing method of the stamp for light guide plates made into them.

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