JP2003202424A - Method and apparatus for manufacturing light guide plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the quality of a light guide plate 12 while lowering the manufacturing cost. <P>SOLUTION: A light guide plate 12 is manufactured by arranging an electroformed replica plate 24 in a metal mold cavity 26. When the kind of the light guide plate 12 is changed, the replica plate 24 is only replaced and the metal mold itself need not be changed. The replica plate 24 has its thinnest part set to ≥0.8 mm thick, or thick, so a fitting surface 20a of a 2nd metal mold 20 where the replica plate 24 is fitted may be coarser than before. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide plate manufacturing method and a light guide plate manufacturing apparatus for forming an optical pattern using a replica plate.

[0002]

2. Description of the Related Art For backlights of liquid crystal display panels,
A surface illumination device that uniformly irradiates the display surface with light is used. This surface-type lighting device includes a light guide plate having a predetermined optical pattern (dot pattern, etc.) formed on a non-light emitting surface, and a light source is disposed in proximity to a light entering surface (end face in the width direction) of the light guiding plate. A reflection plate is arranged close to the light output surface (back surface), and a diffusion plate, a light guide lens, and the like are arranged on the light output surface (front surface) side.

The light guide plate used in such a surface lighting device is manufactured by injection molding of synthetic resin. As a method for forming a predetermined optical pattern on the non-light emitting surface,
(A) A method of machining a pattern corresponding to the optical pattern on the inner surface of the mold, and (b) an extremely thin replica plate of about 0.1 mm to 0.6 mm having the pattern corresponding to the optical pattern is used as the mold cavity. A method of mounting the device inside is generally known.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention Prior art (a) mentioned above
Then, since the pattern corresponding to the optical pattern was directly formed on the inner surface of the mold, when manufacturing a plurality of types of light guide plates, it is necessary to prepare as many molds as the number of types of light guide plates, There was a problem of high cost.

On the other hand, in the prior art (b), since an extremely thin replica plate which is easily deformed is used, the smoothness or the specularity of the mounting surface on which the replica plate is mounted must be set to an extremely high level. However, there is a problem that the cost becomes high. Further, since the replica plate is easily deformed even by a foreign substance sandwiched between the mounting surface of the mold and the replica plate, there is a problem that the quality (optical characteristics, etc.) of the light guide plate is not stable.

Therefore, a main object of the present invention is to provide a method and an apparatus for manufacturing a light guide plate which can reduce the manufacturing cost and improve the quality of the light guide plate.

[0007]

According to a first aspect of the present invention, a replica plate having a transferred pattern is formed by an electroforming method, the replica plate is placed in a mold cavity, and the replica plate is synthesized in the mold cavity. In the method for manufacturing a light guide plate, which obtains a light guide plate having an optical pattern corresponding to a pattern by injecting a resin, the thickness of the thinnest part of the replica plate is 0.8.
It is a method for manufacturing a light guide plate, which is characterized in that the thickness is not less than mm.

According to the second aspect of the present invention, a mold forming a mold cavity, a replica plate having a pattern and arranged in the mold cavity, and injection for injecting a synthetic resin into the mold cavity. A light guide plate having an optical pattern corresponding to the pattern by injecting a synthetic resin into a mold cavity, wherein the thinnest part of the replica plate has a thickness of 0.8 mm or more. It is a manufacturing apparatus of the light guide plate characterized by being.

According to the invention described in claim 3, in the invention described in claim 2, "a replica plate is arranged on each of the inner surfaces of the mold cavity facing each other, and a light guide plate having optical patterns on both surfaces is obtained. It is characterized by "

According to the invention described in claims 1 to 3, the replica plate formed by the electroforming method is arranged in the mold cavity to manufacture the light guide plate. When changing, it is only necessary to replace the replica plate and not the mold. In addition, the thickness of the replica plate is set to be 0.8 mm or more at the thinnest portion, which is thicker than in the conventional case, and thus the mounting surface of the mold on which the replica plate is mounted may be rougher than in the conventional case.

[0011]

According to the invention described in claims 1 to 3,
It is possible to manufacture a plurality of types of light guide plates by using the same mold only by selectively using different types of replica plates. Therefore, the manufacturing cost of the light guide plate can be reduced.

Further, since the thickness of the replica plate is set thicker than the conventional one, the strength of the replica plate itself can be increased. Therefore, even if the mounting surface is rough or foreign matter is attached to the mounting surface, the replica plate is less likely to be deformed, and the quality of the light guide plate can be stabilized. Furthermore, since the mounting surface may be rough, the processing cost of the mounting surface can be reduced.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a light guide plate manufacturing apparatus 10 to which the present invention is applied is for manufacturing a light guide plate 12 as shown in FIG.

The light guide plate 12 is made of a light transmissive material such as acrylic resin, and the light incident surface 12 is formed on the opposite end faces thereof.
a is formed, and the light emitting surface 1 is formed on the surface (upper surface in FIG. 1).
2b is formed, and a non-light emitting surface 12c is formed on the back surface (lower surface in FIG. 1). Further, a predetermined optical pattern 14 is formed on the non-light emitting surface 12c. Optical pattern 14
Is configured as an aggregate of a plurality of dots 14a, and the distribution density and size of the dots 14a are set so that the light amount is uniform over the entire light emitting surface 12b. That is, in this embodiment, the central portion of the non-light emitting surface 12c has a high density and a large diameter, and the density becomes low and small toward the end portion. Each dot 14a may be either a protrusion or a hole.

The manufacturing apparatus 10 (FIG. 1) includes a first mold 18,
The second mold 20, the injection device 22, the replica plate 24 and the like are included.

The first mold 18 cooperates with the second mold 20 to form a mold cavity 26.
A sprue 18 a is formed on the side surface of 8, and a runner 18 b is formed from the sprue 18 a toward the mold cavity 26.

The second mold 20 cooperates with the first mold 18 to form a mold cavity 26.
On the inner surface of 0, the mounting surface 20 for mounting the replica plate 24
a is formed. The mounting surface 20a is finished to be smooth so that the replica plate 24 can be stably held while preventing the replica plate 24 from being deformed. Then, a screw hole (not shown) into which a mounting bolt (not shown) for mounting the replica plate 24 is screwed is formed in the peripheral portion of the mounting surface 20a.

The first mold 18 and the second mold 20 are fixed to a mold plate (not shown) and opened / closed by a hydraulic cylinder (not shown).

The injection device 22 is for injecting a synthetic resin material (acrylic resin or the like), which has been heated and melted, into the mold cavity 26, and is an injection nozzle 22 connected to the sprue 18.
Including a. As such an injection device 22, a device generally used in injection molding can be used as it is.

As shown in FIG. 3, the replica plate 24 includes a plate-shaped main body 24a made of nickel or the like.
A pattern 28 corresponding to the optical pattern 14 (FIG. 2) formed on the non-light emitting surface 12c of the light guide plate 12 is formed on the surface of the. That is, when each dot 14 a forming the optical pattern 14 is a protrusion, each dot 28 a forming the pattern 28 is formed as a hole, and the optical pattern 1
When the dots 14a forming the pattern 4 are holes, the dots 28a forming the pattern 28 are formed as protrusions.

From the viewpoint of preventing the replica plate 24 from being easily deformed, the thinnest portion is 0.8 mm.
It is preferable that the thickness is 15 mm or less from the viewpoint of time and cost required for manufacturing. And considering these balances, 1.5
The most preferable value is about mm.

When manufacturing the replica plate 24, first,
As shown in FIG. 4A, the pattern 2 of the replica plate 24
A master mold 32 having a plurality of patterns 30 corresponding to 8 formed on its surface is prepared. Then, as shown in FIG.
A nickel layer is grown on the surface of the mother die 32 by electroforming to form a nickel plate 34. When the thinnest portion of the nickel plate 34 has a thickness of about 0.8 mm to 15 mm, FIG.
As shown in (C), the nickel plate 34 is peeled off from the mother die 32. Then, as shown in FIG. 4D, the nickel plate 34 is cut into a predetermined size to obtain the replica plate 24.

Referring to FIG. 1, when manufacturing the light guide plate 12 (FIG. 2), first, on the mounting surface 20a of the second mold 20,
The replica plate 24 is attached with mounting bolts so that the pattern 28 (FIG. 3) is located inside. continue,
The first mold 18 and the second mold 20 are closed by a hydraulic cylinder (not shown) to form a cavity 26, and a spout 18a of the first mold 18 is provided with an injection nozzle 22a of an injection device 22.
Connect. Then, from the injection device 22 to the cavity 26
The molten resin is injected into the inside. When the molten resin is filled in the cavity 26, the molten resin is patterned 28 (FIG. 3).
And the optical pattern 14 having a shape opposite to the pattern 28 is formed. When the molten resin in the cavity 26 is cooled to a predetermined temperature, the first mold 18 and the second mold 20 are opened to release the light guide plate 12.

According to this embodiment, since the optical pattern 14 is formed by using the replica plate 24,
Different types of light guide plates 12 can be manufactured using the same mold by simply replacing the replica plate 24. Therefore, the manufacturing cost of the light guide plate 12 can be reduced.

Further, since the thickness of the thinnest part of the replica plate 24 is set to about 0.8 mm to 15 mm, the replica plate 24 itself can be provided with strength that is not easily deformed. Therefore, even if the mounting surface 20a is a rough surface or foreign matter is attached to the mounting surface 20a, the replica plate 24 can be prevented from being deformed and the quality of the light guide plate 12 can be stabilized.

Furthermore, since the mounting surface 20a may be a rough surface,
The mounting surface 20a does not need to be mirror-polished.
The processing cost can be reduced.

As a method of mounting the replica plate 24 on the mounting surface 20a, for example, a method using vacuum suction or a method using a fixed frame may be adopted.

The optical pattern 14 of the light guide plate 12 is
For example, as shown in FIG. 5, it may be configured as a continuous pattern of concave stripes 14b and convex stripes 14c each having a wedge-shaped cross section. In this case, for example, as shown in FIG. 6, a replica plate 40 having an uneven pattern 36 corresponding to the optical pattern 14 is used, but the thickness of the thinnest portion thereof is 0 as in the replica plate 24 described above. 0.8 mm-1
It is set to about 5 mm.

Further, in the above-mentioned embodiment, the case where the light guide plate 12 having the optical pattern 14 on one surface is manufactured has been described. However, as shown in FIG. 7, for example, as shown in FIG. Replica plate 24
(Or 40) may be arranged to manufacture the light guide plate 12 having the optical patterns 14 on both surfaces. In this case, the mounting surface 20a is attached to the inner surface of the second mold 20.
And the mounting surface 18 is formed on the inner surface of the first mold 18.
c is formed, and the replica plate 24 (or 40) is attached to each of the mounting surface 20a and the mounting surface 18c with a mounting bolt (not shown).

Further, the wedge-shaped light guide plate 12 may be manufactured by using a wedge-shaped mold cavity 26 as shown in FIG. 8, for example. Even in this case, the optical pattern 14 can be formed on one side or both sides of the light guide plate 12 by disposing the replica plate 24 (or 40) in the mold cavity 26.

The inventors have changed the combination of the thickness t (mm) of the thinnest part and the arithmetic mean roughness h (Ra) of the mounting surface 20a for the 14-inch size replica plate 40 (FIG. 6). The quality of the manufactured light guide plate 12 was examined to determine whether or not the light guide plate 12 can be used. Table 1 is a summary of the results.

[0032]

[Table 1] From Table 1, it can be seen that the thickness t of the thinnest part of the replica plate 40 that can withstand practical use is 0.8 mm or more. That is,
When the thickness t is thinner than 0.8 mm, the roughness h of the mounting surface 20a must be 1.5 Ra or less, and therefore mirror polishing is required, which is not practical from the viewpoint of cost and time required for processing.

[Brief description of drawings]

FIG. 1 is an illustrative view showing a light guide plate manufacturing apparatus to which the present invention is applied.

FIG. 2 is a perspective view showing a light guide plate.

FIG. 3 is a perspective view showing a replica plate.

FIG. 4 is an illustrative view showing a method for manufacturing a replica plate.

FIG. 5 is a perspective view showing another light guide plate.

FIG. 6 is a perspective view showing a modified example of the replica plate.

FIG. 7 is an illustrative view showing another apparatus for manufacturing a light guide plate to which the invention is applied.

FIG. 8 is an illustrative view showing another apparatus for manufacturing a light guide plate to which the invention is applied.

[Explanation of symbols]

10 ... Light guide plate manufacturing apparatus 12 ... Light guide plate 14 ... Optical pattern 18 ... 1st mold 20 ... Second mold 20a ... Mounting surface 24 ... Replica board 28 ... Pattern

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hirozumi Taguchi             3-17 Nitta-cho, Niihama-shi, Ehime day             Inside this Chemtech Co., Ltd. (72) Inventor Nozomi Mito             3-17 Nitta-cho, Niihama-shi, Ehime day             Inside this Chemtech Co., Ltd. (72) Inventor Masaya Suzuki             3-17 Nitta-cho, Niihama-shi, Ehime day             Inside this Chemtech Co., Ltd. F-term (reference) 2H038 AA55 BA06                 2H091 FA23Z FC17 FC19 FC29                       LA12                 4F202 AA20 AG05 AH73 CA11 CB01                       CK27 CK43

Claims (3)

[Claims] 1. A pattern-transferred replica plate is formed by electroforming, the replica plate is placed in a mold cavity, and a synthetic resin is injected into the mold cavity to correspond to the pattern. A method for manufacturing a light guide plate for obtaining a light guide plate having an optical pattern, wherein the thinnest part of the replica plate has a thickness of 0.8 mm or more. 2. A mold comprising a mold cavity, a replica plate having a pattern and arranged in the mold cavity, and an injection device for injecting a synthetic resin into the mold cavity, In a light guide plate manufacturing apparatus for obtaining a light guide plate having an optical pattern corresponding to the pattern by injecting a synthetic resin into the mold cavity, the thinnest part of the replica plate has a thickness of 0.8 mm or more. An apparatus for manufacturing a light guide plate, which is characterized in that 3. The apparatus for manufacturing a light guide plate according to claim 2, wherein the replica plates are arranged on respective inner surfaces of the mold cavity that face each other, and light guide plates having the optical patterns on both surfaces are obtained. .