JP2002210744A - Manufacturing method of mold for light guide - Google Patents

Abstract

(57) [Problem] To provide a method for manufacturing a mold capable of efficiently and accurately reproducing unevenness on the surface of a light guide such as a liquid crystal display device. SOLUTION: A step of applying a copper plating 3 on a surface of a roller 1, a step of engraving a concave portion 4 of a predetermined pattern on the surface of the copper plating 3 by an engraving machine, and applying a release agent to the surface of the copper plating 3 After that, a step of further applying a copper plating 6, a step of peeling off the upper copper plating 6 to obtain a copper plating sheet 8, and a light guide using the plating sheet 8 as a mold of a light guide such as a liquid crystal display device. How to make the body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a light guide for a back light used in a liquid crystal display device or the like having an uneven surface for scattering or reflecting light by injection molding. The present invention relates to a method for efficiently and accurately manufacturing a mold used at the time.

[0002]

2. Description of the Related Art A light guide for a backlight of a surface light source device used for a liquid crystal display device or the like is used to obtain a surface light source for uniformly illuminating a liquid crystal screen from a linear light source such as an LED or a fluorescent lamp. The light from the LED or the fluorescent lamp is scattered inside the light guide, and light as uniform as possible is emitted to one entire surface of the light guide.

There are various principles, such as printing a paint reflecting light in a predetermined pattern on the surface of the light guide opposite to the surface having liquid crystal that emits light or diffusing light. There are ones having a shape surface and ones having a function of diffusing light to the light guide material itself.

Here, as an example of a surface of the light guide opposite to the light exit surface as a surface for diffusing light, there is a surface roughened surface, but irregularities of a predetermined pattern are formed on the surface. There is a method of providing light and diffusing light, and this method is excellent in that it can uniformly irradiate the emission surface of the light guide by appropriately controlling the pattern of the unevenness.

There are various methods for forming irregularities on the surface of the light guide, and various methods such as a sand blast method and a melting method using a laser beam have been developed.
In general, a method of molding a light guide made of acrylic or the like with an uneven surface on the surface by injection molding using a mold provided with irregularities is widely used in terms of cost.

[0006] Japanese Patent Application Laid-Open No. 9-222514 discloses a method of manufacturing a light guide, in which a mold having an uneven surface is formed by an etching method using a photoresist. .

[0007]

In recent liquid crystal display devices, there has been a demand for uniformity of illuminance with increasing size, improvement of accuracy with decreasing thickness, and higher efficiency for lower power consumption. Also, with respect to the light guide, high accuracy is required for the uneven surface for diffusing light.

However, for example, the formation of the uneven surface by the sand blast method has difficulty in maintaining the uniformity of the entire product and has a problem in accuracy and the like. In this case, the concave portion or the groove portion is directly formed on the acrylic by melting with a laser beam. However, it is difficult to control the output of the laser and the cost is high.

Further, even when integrally molded with a mold having irregularities, the irregularities are affected by the accuracy of the irregularities themselves. Particularly, in the case where the irregularities of the mold are manufactured by an etching method, the irregularities are formed by corrosion by a liquid. Therefore, unevenness is likely to occur, and there is a problem in the accuracy of the uneven portion.

The present invention solves the above-mentioned problems and provides a method for manufacturing a metal mold capable of efficiently and accurately reproducing unevenness on the surface of a light guide.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a first aspect of the present invention is to provide a step of applying a copper plating to a roller having a surface capable of plating copper, and engraving the surface of the plated copper. A step of engraving a predetermined pattern with a machine, a step of further applying copper plating after applying a release agent to the surface of the copper, a step of removing a copper plating of an upper layer to obtain a copper plating sheet, and This is a method for manufacturing a light guide used as a mold for a light guide such as a display device.

Further, according to a second aspect of the present invention, the roller after the copper plating sheet is peeled off by the manufacturing method of the first aspect is further subjected to a copper plating step, and the upper layer copper plating is peeled off. This is a method for manufacturing a mold for a light guide, which repeats the steps of obtaining a copper-plated sheet.

[0013] The invention of claim 3 is a method of manufacturing a mold in which the copper plating sheet having a predetermined pattern obtained by the method of claim 1 or 2 is used for various printing dies.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIGS.

First, FIG. 1 shows a roller 1 used in the present invention, which is similar to a printing roller used for gravure printing or the like, has an iron cylindrical shape, and has a width W. The radius R of the roller is arbitrary depending on the size of the die to be manufactured.

Next, as shown in FIGS. 2A and 2B,
The thickness of the iron 2 on the surface of the roller 1 is 100 to 15
Copper plating 3 (first layer) having a thickness of about 0 μm and a hardness of about 230 to 260 is applied.

The thickness and hardness of the copper plating 3 are adjusted by appropriately adjusting the chemicals used for plating (hydrochloric acid, sulfuric acid, additives), temperature, liquid temperature, current, roller rotation, and the like.

The surface of the copper is polished on the roller 1 having the copper plating 3 applied to the surface of the roller 1 so as to have a mirror-finished surface with no irregularities.

Next, as shown in FIG. 2C, a predetermined pattern is formed on the mirror-finished surface of the copper plating 3 by an engraving machine that performs engraving using a needle made of a hard material such as diamond. The recess 4 is formed by engraving.

Examples of the engraving machine used here include Balcas engraving machine manufactured by Dainippon Screen Co., Ltd., Helio manufactured by Heidelberg, and Ohio U.S.A. engraving machine.

The engraving involves excavating the roller surface with the needle of the engraving machine while rotating the roller. The engraving machine controls the movement of the needle back and forth and the rotation of the roller in accordance with a pre-programmed pattern. Then, a groove or a hole-shaped recess 4 having a desired depth and length is formed on the surface of the first layer copper plating 3.

The shape of the recess 4 is a hole, a groove, a dot,
Various shapes such as trapezoidal shapes and curved shapes can be excavated according to the target pattern, but the depth is usually about 20 mm.
It is possible to dig up to about 60 μm.

As shown in FIG. 2D, a release agent is applied to the surface of the copper plating 3 of the first layer of the roller in which the concave portions 4 having the predetermined pattern are formed, and then a chromium, nickel, etc. Is applied to the surface.

Further, as shown in FIG. 2 (E), after the metal film 5 on the surface of the first layer copper plating 3 is applied, a second layer copper plating 6 is applied.

The thickness of the copper plating 6 of the second layer is arbitrary, but if it is too thick, it may hinder the subsequent peeling operation and the like.
Up to a degree is preferred.

As shown in FIG. 2F, after the plating is completed, the second upper layer copper plating 6 is peeled off together with the metal film 5, and the second layer copper plating 6 is formed inside the first layer copper plating. The concave portion 4 engraved with respect to the copper plating 3 is transferred to the convex portion 7 to form a copper plated sheet 8 formed.

If the copper plated sheet 8 obtained by peeling the copper plating 6 of the second layer is used as a mold for manufacturing a light guide, a highly accurate uneven surface of the light guide can be obtained.

By repeating the operations shown in FIGS. 2D to 2F for the roller 1 after the copper plating 6 of the second layer has been peeled off, a large number of molds having the same pattern and accuracy can be produced. can do.

In the above manufacturing method, since the excavation of the concave portion 4 shown in FIG. 2 (C) is a mechanical excavation using a diamond needle of an engraving machine, fine engraving can be performed with a precision of several μm. As shown in FIG. 3, if the concave portion 4 is finely formed on the concave portion 4 with a diamond needle 9 in micron units, the fine convex portion 7 of the mold obtained by this manufacturing method also has a fine concave and convex surface. Is done.

The cross section of the recess 4 is not limited to a rectangle as in the case of forming by etching, and the angle or depth can be freely changed by appropriately changing the engraving pattern of the engraving machine. Can be.

FIG. 4 shows a light guide 11 made of an acrylic plate in the form of a wedge, which is obtained by using the above-mentioned mold. This is an example in which light 13 from a linear light source such as a backlight is diffused throughout the liquid crystal screen.

According to the light guide 11, the concave and convex surface 14 to which the concave and convex surface 10 shown in FIG. 3 is transferred is formed on the bottom surface of the concave portion 12, and the pattern of such concave and convex surface 14 which cannot be obtained by etching. Thus, the diffusivity of the light 13 is improved, and the illuminance of the liquid crystal can be improved.

Further, the shape of the recess 12 can be determined freely and more accurately than the recess obtained by the mold formed by etching, and the accuracy is good, so that the light guide can easily exhibit the performance as set. Further, since the diffusivity of the light 13 can be finely controlled, uniform illuminance can be obtained over the entire liquid crystal screen.

Further, according to the manufacturing method of the present invention, a large mold for a light guide, which has been conventionally difficult to manufacture, can be easily obtained only by enlarging the rollers to be used. The liquid crystal screen can be made larger, and for example, it can be applied to a large display controlled by a personal computer or the like connected to a disk device, such as a large television for displaying a moving image used for outdoor advertising. .

According to this method of manufacturing a mold, the light guide 1
The present invention is not limited to 1, and can be applied as a method for manufacturing a printing die having irregularities.

That is, when engraving the copper plating 3 surface of the first layer shown in FIG. 2C, characters, figures, and pictures for printing advertisements, posters, and the like are used instead of the uneven pattern of the light guide. If the concave portion 4 is formed and drawn with the needle of the engraving machine, the second
When the copper plating 6 of the layer is peeled off, a printing die having the engraved portion as the convex portion 7 is completed.

If the operations shown in FIGS. 2D to 2F are further repeated, it is possible to mass-produce dies having the same quality.

According to this method, the width and height of the mold obtained by the size of the roller 1, ie, the width of the roller 1 and the length of the outer periphery of the roller, are determined. A mold can be obtained. For example, even if it is a large signboard mold, the mold can be easily obtained by using the roller 1 suitable for the size of the signboard.

For example, if the width W of the roller 1 in FIG. 1 is about 2 m and the radius is 30 cm, the height and width are 2 m and 1.
A large printing die for a signboard having a length of 8 m can be easily formed.

[0040]

As described above, according to the first aspect of the present invention, since the pattern of the mold for manufacturing the light guide is performed by mechanical engraving on the roller, a precise and fine pattern can be formed. Irregularities are obtained with good reproducibility, and by controlling the pattern, the obtained mold has high accuracy. The light guide using this mold has a precise light scattering pattern in units of microns, As a result, the illuminance can be improved by the property, and the illuminance of the entire liquid crystal screen can be made uniform.

Since the size of the obtained mold is determined by the size of the roller, it is possible to easily cope with the enlargement of the light guide accompanying the recent increase in the size of the liquid crystal screen by increasing the size of the roller. Since local unevenness of accuracy does not occur unlike a die using an etching method, high accuracy can be maintained even when the size is increased.

Next, according to the second aspect of the present invention, if the upper layer of the copper plating is peeled off and the copper plating is performed again, a large number of molds having the same pattern and accuracy can be produced. Can be.

Further, according to the invention of claim 3, when used as a method for manufacturing various printing dies, precise and fine pattern irregularities can be obtained with good reproducibility as a die. It is a better mold than the mold.

In particular, since the width and height of the obtained mold are determined by the width of the roller and the length of the outer periphery of the roller, the larger the roller, the larger the printing mold becomes. Even a printing die for a large signboard, which has been difficult, can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a perspective view of a roller used in the manufacturing method of the present invention.

FIGS. 2A to 2F are enlarged cross-sectional views of a main part showing a manufacturing method of the present invention.

FIG. 3 is a partially enlarged cross-sectional view when a concave portion is formed in a first layer of a roller.

FIG. 4 is an enlarged sectional view of a main part of a light guide obtained by the manufacturing method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Roller 2 Iron 3 Copper plating (1st layer) 4 Concave part 5 Metal film 6 Copper plating (2nd layer) 7 Convex part 8 Copper plating sheet 9 Diamond needle 10 Irregular surface 11 Light guide 12 Concave 13 Light 14 Irregular surface

Claims (3)

[Claims] 1. A step of applying copper plating to a roller having a surface capable of plating copper, a step of engraving a predetermined pattern on the surface of the plated copper by an engraving machine, and applying a release agent to the surface of the copper. After the step of further copper plating, and a step of peeling the upper layer copper plating to obtain a copper plated sheet,
A method for manufacturing a light guide mold, comprising using the copper plated sheet as a light guide mold for a liquid crystal display device or the like. 2. A step of further applying copper plating to the roller after the copper plating sheet has been peeled off by the method of claim 1, and a step of peeling off the upper copper plating to obtain a copper plating sheet. A method for manufacturing a light guide mold. 3. A method for manufacturing a mold, comprising using the copper-plated sheet having a predetermined pattern obtained by the method according to claim 1 as a mold for various printings.