KR20080012004A - Mold for manufacturing light guide plate having a prism and hologram pattern and method for manufacturing thereof - Google Patents

Abstract

A mold for manufacturing a light guide plate having a prism and a hologram pattern and a manufacturing method thereof are provided to form a minute prism unevenness on an upper surface of the light guide plate and form a hologram pattern on a lower surface of the light guide plate, thereby obtaining uniform surface light sources and high luminance. A prism pattern mold unit(58) is manufactured by the following steps of: forming a photo resist layer pattern on a silicon substrate; forming the silicon substrate in a quadrangular pyramid uneven shape by etching the patterned photo resist layer and the silicon substrate; forming a metal layer through electroplating on the silicon substrate where the quadrangular pyramid unevenness is formed; separating the metal layer; and performing surface polishing of a pattern another surface and a side of the separated metal layer. A hologram pattern mold unit(76) is manufactured by the following steps of: exposing a photo resist layer, formed on a glass substrate, through refraction interference light; forming a photo resist layer of a hologram pattern; forming a metal layer through electroplating on the photo resist layer of the hologram pattern; separating the metal layer; and performing surface polishing of a pattern another section and a side of the separated metal layer.

Description

Mold for manufacturing light guide plate having a prism and hologram pattern and method for manufacturing thereof

1 is a view showing a backlight device for LCD (LCD) to which a conventional light guide plate is applied.

2 is a view showing a conventional prism sheet and a light guide plate.

3 is a view showing a prism pattern mold part of a mold for manufacturing an integrated light guide plate having a prism and a hologram pattern according to the present invention;

Figures 4a to 4g is a prism pattern mold part manufacturing process diagram of a mold for manufacturing an integrated light guide plate having a prism and a hologram pattern according to the present invention.

5 is a view showing a hologram pattern mold portion of a mold for manufacturing an integrated light guide plate having a prism and a hologram pattern according to the present invention;

Figure 6a to 6g is a hologram pattern mold part manufacturing process diagram of a mold for manufacturing an integrated light guide plate having a prism and a hologram pattern according to the present invention.

7 is a view showing the application to the injection device of the mold for manufacturing an integrated light guide plate having a prism and a hologram pattern of the present invention.

<Explanation of symbols for main parts of drawing>

10: square pattern 11: square pyramid irregularities

31: Spherical wave 32: Hologram wavefront

51,54,71,74 photoresist layer 52,56 silicon substrate

53 mask pattern 57,75 metal layer

58: prism pattern mold portion 72: glass substrate

76: hologram pattern mold portion 91: light source

The present invention relates to a mold manufacturing method for manufacturing a light guide plate, and more particularly, to form a fine prism irregularities on an upper surface of the light guide plate, and to form a hologram pattern having scattering and diffusion functions on the lower surface of the light guide plate, thereby providing a uniform surface light source. A mold for manufacturing an integrated light guide plate having a prism and a hologram pattern having high brightness, and a manufacturing method thereof.

LCD and PDP are one of the well known flat panel display devices. Since both LCD and PDP apply the same light guide plate, only the LCD will be described below.

1 is a view showing a backlight device for an LCD (LCD) to which a conventional light guide plate is applied, and FIG. 2 is a view showing a conventional prism sheet and a light guide plate.

As shown in FIG. 1, as a backlight device of a general LCD in which a light guide plate is coupled, the light guide plate in the LCD brightens the liquid crystal environment of the upper part by emitting light incident from a fluorescent lamp attached to the side evenly through the surface. The main acts as a backlight. The backlight is generally a light guide plate 2 and a reflecting sheet 1 below the light guide plate 2 and a diffusion sheet 5, prism sheets 6 and 7 and a protective sheet 8 above the light guide plate 2. And a lamp reflector 4 for fixing the light source 3 and the light source 3 to one side of the light guide plate to reflect light. That is, it is a part that serves to convert the point light source or the line light source by the lamp 3 on the side or the back into the surface light source form. The material of the light guide plate 2 is made of transparent optical resin or PC (polycarbonate), especially PMMA resin called acryl, which is mainly manufactured by injection molding, and is mainly manufactured by injection molding. To emit light, various patterns are attached or engraved on the surface for scattering and reflection of light.

In the conventional light guide plate, light rays scattered by a pattern do not have a constant direction and are diffusely reflected at various angles and emitted to the outside as shown in FIG. 2. In the conventional backlight device, a diffuser sheet 5 is mounted on the light guide plate to evenly spread the light scattered from the pattern portion and the prism to collect light scattered at various angles in the front direction perpendicular to the plane. By mounting the sheets 6, 7 and the protective sheet 8 on the light guide plate, the surface luminance seen from the front side is improved.

However, the price of the prism sheets has been a major factor to increase the cost of the backlight device for LCD, and efforts have been made to form a fine prism irregularity directly on the upper surface of the light guide plate to serve as a prism sheet. In order to manufacture the mold core for the prism light guide plate, the prism irregularities having a depth of 50 μm or less are engraved over the entire surface of the core, and the fabricated surface is mirrored.

In general, steel lumps are frequently used as a material for injection mold cores. In the conventional manufacturing process, casting, forging, and rolling while cooling molten iron are performed. The uniformity of crystallization of metallographic structures is reduced due to bubble generation and anisotropic arrangement of crystals. Therefore, when the micro-depth cutting process of about 5㎛ to 50㎛ for these materials, it is difficult to obtain the mirror surface level of 10 nm or less of average surface roughness (Ra) required for prism irregularities, and it is difficult to carry out the lapping process even after cutting. Therefore, there is a problem that it is difficult to manufacture a mold core having a mirror surface fine prism irregularities with existing materials and processes.

In addition, a method of rotating the abrasive stone at high speed is generally used for mirror surface machining of minute uneven portions, but it is difficult to maintain the precision of the polished stone so as to sharply sharpen the corners of the vertices.

For this reason, despite the many advantages and efforts expected of the separate integrated prism LGP, mass production on a commercial scale has not been achieved until now due to difficulty in manufacturing a mold.

In order to solve the above problems, an object of the present invention is to expose the prisms and hologram-integrated pattern manufactured by forming a pattern shape by varying the depth of etching according to light exposure by exposing than a method of directly grinding and cutting a conventional mold core. Provided is a mold for manufacturing a high brightness light guide plate.

In the mold manufacturing method for an integrated light guide plate made of a prism pattern mold part and a hologram pattern mold part of the present invention for achieving the above object,

The prism pattern mold portion,

Forming a photoresist layer pattern on the silicon substrate;

Etching the patterned photoresist layer and the silicon substrate to form a silicon substrate in a quadrangular pyramid irregularities;

Forming a metal layer on the silicon substrate on which the square pyramid irregularities are formed by an electroplating method;

Separating the metal layer; And

Mirror surface processing of one side surface and the other end surface of the separated metal layer;

The hologram pattern mold portion,

Exposing the photoresist layer formed on the glass substrate with refractive interference light;

Forming a holographic patterned photoresist layer;

Forming a metal layer on the hologram pattern photoresist layer by an electroplating method;

Separating the metal layer; And

And mirror-processing one side surface and the other end surface of the patterned metal layer.

The isosceles triangle inner angle A of the quadrangular pyramid is preferably formed at 50 to 60 degrees, more preferably 57.4 degrees.

The square pattern of the bottom surface of the square pyramid is preferably formed in 0.5 ~ 50㎛.

The metal layer is preferably formed to a thickness of 0.3mm to 1cm, preferably formed by alloying any one or two or more of nickel, copper, tin, and chromium, and more preferably formed of nickel.

In addition, in the mold for manufacturing an integrated light guide plate made of a prism pattern mold part and a hologram pattern mold part of the present invention for achieving the above object,

A prism pattern mold part having an isosceles triangle inner angle (A) of a square pyramid of 50 ° to 60 ° and a periodic pattern having a square pattern length of 0.5 μm to 50 μm on the bottom of the square pyramid;

And a hologram pattern mold part which is widened at regular intervals in the shape of a square wave protrusion and has a width of 0.1 μm to 20 μm.

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

3 is a view showing a prism pattern mold part of a mold for manufacturing an integrated light guide plate having a prism and a hologram pattern according to the present invention.

As shown in FIG. 3, a large amount of square patterns 10 are formed on the upper surface of the light guide plate in a predetermined order, and the square patterns 10 have an upward quadrangular pyramid irregularity 11 shape so that the light source is uniformly upward. Direct sunlight is created.

At this time, the size of the square pattern 10 is preferably formed to about 0.5㎛ to 50㎛, the square pyramid irregularities 11 isosceles triangle inner angle (A) is preferably formed to 50 to 60 °, optimal It is more preferable to form the 57.4 degrees for the brightness of.

4A to 4G are diagrams illustrating a process of manufacturing a prism pattern mold part of a mold for manufacturing an integrated light guide plate having a prism and a hologram pattern according to the present invention.

As shown in FIGS. 4A to 4C, first, a photoresist layer 51 is formed on a silicon substrate 52, and the photoresist layer 51 is exposed using a mask pattern 53, followed by etching. The photoresist layer 54 is formed.

Subsequently, as illustrated in FIG. 4D, the photoresist layer 54 and the silicon substrate 52 patterned with a potassium hydroxide (KOH) solution are etched to form a silicon substrate 56 having a square pyramid irregularities. At this time, the length of the square pattern on the bottom of the square pyramid is preferably formed to 0.5 to 50㎛, the inner angle (A) of the quadrangular pyramidal isosceles triangle is preferably formed to 50 to 60 °, more preferably for optimal brightness Form 57.4˚.

Subsequently, a release agent mixed with potassium dichromate (K ₂ Cr ₂ O ₇ Potassium Dichromate (6 g)) and ultrapure water (DI WATER, 2000 ml) is sprayed onto the square pyramidal uneven silicon substrate 56 to apply the spray.

Subsequently, as shown in FIG. 4E, the metal layer 57 is formed on the upper surface of the silicon pyramid-shaped concave-convex shape by an electroplating method with a thickness of 0.3 mm to 1 cm. At this time, when electroplating the silicon substrate 56 of the square pyramid irregularities shape by attaching a mold (not shown) of a predetermined size to prevent damage of the silicon substrate 56 due to the internal tension by the thickness of the plating layer to distribute the internal tension To make.

Subsequently, as shown in FIG. 4F, the metal layer 57 is separated from the silicon substrate 56 having the rectangular pyramidal irregularities. At this time, the release agent is spray-coated to the square pyramid concave-convex silicon substrate 56 to be easily separated. In addition, the metal layer 57 is preferably formed by alloying any one or two or more of nickel, copper, tin, and chromium, and more preferably, nickel.

Finally, as shown in 4g, one side surface and the other end surface of the metal layer 57 are cut or specularly applied to the injection apparatus to form the mold portion 58 of the prism pattern. At this time, the metal layer 57 is mirror-machined for the average surface roughness Ra of 10 nm or less required for cutting the prism to perform cutting and surface processing according to the LCD backlight unit model to form the mold portion 58 of the prism pattern. do.

FIG. 5 is a diagram showing a hologram pattern mold part of a mold for manufacturing an integrated light guide plate having a prism and a hologram pattern of the present invention. FIG.

As shown in FIG. 5, the lower surface of the light guide plate forms a spherical wave 31 and a hologram wave surface 32 that are widened at regular intervals at the other end of the one light source 91. In this case, the hologram wavefront 32 diffuses the light transmitted from the light source 91 on one side to a uniform surface light source.

6A to 6G are diagrams illustrating a process for manufacturing a hologram pattern mold part of a mold for manufacturing an integrated light guide plate having a prism and a hologram pattern according to the present invention.

6A to 6C, first, a photoresist layer 71 is formed on the upper surface of the glass substrate 72 and then exposed to a refractive interference light source. In this case, as shown in FIG. 5, the hologram pattern photoresist layer 74 is formed by the difference of the replica light of the hologram wavefront 32 of the spherical wave 31, and the refractive interference light is exposed by varying the refractive angle of the light. The pattern is formed according to the contact amount.

Subsequently, as illustrated in FIGS. 6D and 6E, the exposed photoresist layer 71 is etched to form a hologram pattern photoresist layer 74, followed by potassium dichromate (K ₂ Cr ₂ O ₇ Potassium Dichromate, 6g). And a release agent mixed with ultrapure water (DI WATER, 2000 ml) is applied by spraying, and a metal layer 75 having a thickness of 0.3 mm to 1 cm is formed by an electroplating method. In this case, the metal layer 57 is preferably formed by alloying any one or two or more of nickel, copper, tin, and chromium, and more preferably, nickel.

Subsequently, as shown in FIG. 6F, the metal layer 75 is separated from the photoresist layer 74 of the hologram pattern. At this time, the mold release agent is applied to the photoresist layer 74 of the hologram pattern and is easily separated.

Finally, as shown in FIG. 6G, one side surface and the other end surface of the metal layer 75 may be cut or specularly applied to an injection apparatus to form a mold portion 76 having a hologram pattern. Here, the mold portion 76 of the hologram pattern is formed in a non-periodic pattern having a square wave protrusion shape at regular intervals at a single center point at the other end side of the light source 91 and having a width of 0.1 μm to 20 μm.

7 is a view showing the application to the injection device of the mold for manufacturing an integrated light guide plate having a prism and a hologram pattern of the present invention.

As shown in FIG. 7, the prism pattern mold part 58 and the hologram pattern mold part 76 are mounted inside the injection apparatus including the cylinders 81 and 83 and the supports 82, 84, and 85, and face the pattern. Put the poly methyl meta acrylate (PMMA), PC (polycarbonate) or resin resin in between to move the cylinder (81,83) up and down, and at the same time the prism pattern mold unit 58 is lowered and the hologram The pattern die 76 is raised and pressurized to form the light guide plate.

According to the present invention, a mold may be manufactured by electroplating a prism pattern and a hologram pattern on both sides of a light guide plate for supplying a uniform surface light source in a backlight unit, and may be easily processed by mirror processing. When applied to a light guide plate injection molding process or a press process using the mold made as described above, a uniform and stable pattern can be produced. In addition, when the light guide plate is manufactured by using the mold thus manufactured, the light luminance transmitted from the side surface of the light guide plate is greatly improved, and the light source of the upper surface of the light guide plate is uniformly emitted upward in a straight line to obtain uniform high brightness. In addition, due to the brightness increase effect of the light guide plate, it is possible to reduce the additional device for improving the brightness is expected to reduce the cost.

Claims (7)

In the mold manufacturing method for manufacturing an integrated light guide plate consisting of a prism pattern mold part and a hologram pattern mold part, The prism pattern mold portion, Forming a photoresist layer pattern on the silicon substrate; Etching the patterned photoresist layer and the silicon substrate to form a silicon substrate in a quadrangular pyramid irregularities; Forming a metal layer on the silicon substrate on which the square pyramid irregularities are formed by an electroplating method; Separating the metal layer; And Mirror surface processing of one side surface and the other end surface of the separated metal layer; The hologram pattern mold portion, Exposing the photoresist layer formed on the glass substrate with refractive interference light; Forming a holographic patterned photoresist layer; Forming a metal layer on the hologram pattern photoresist layer by an electroplating method; Separating the metal layer; And Mirror surface processing of one side surface and the other end surface of the separated metal layer; manufacturing method of a light guide plate manufacturing. The method of claim 1, Before forming the metal layer, a method for manufacturing a light guide plate, characterized in that it further comprises applying a release agent mixed with potassium dichromate (K ₂ Cr ₂ O ₇ Potassium Dichromate) and ultrapure water (DI WATER). The method of claim 1, The isosceles triangle inner angle (A) of the quadrangular pyramid is preferably formed at 50 to 60 degrees, more preferably 57.4 degrees, the manufacturing method of the mold for light guide plate manufacturing. The method of claim 1, The square pattern length of the bottom surface of the square pyramid is a mold manufacturing method for manufacturing a light guide plate, characterized in that formed in 0.5 ~ 50㎛. The method of claim 1, The metal layer is a method for manufacturing a light guide plate, characterized in that formed in a thickness of 0.3mm to 1cm. The method of claim 1, The metal layer is preferably formed by alloying any one or two or more of nickel, copper, tin and chromium, and more preferably formed of nickel. In the integrated light guide plate manufacturing mold which consists of a prism pattern metal mold part and a hologram pattern metal mold part, A prism pattern mold part including an isosceles triangle inner angle (A) of the square pyramid having a periodic pattern having a square pattern length of 0.5 µm to 50 µm at a bottom of the square pyramid; A light guide plate manufacturing mold comprising: a hologram pattern mold part which is widened at regular intervals in the shape of a square wave protrusion and has a width of 0.1 μm to 20 μm.

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