JP2000021220A - Manufacture of light guide plate and light guide plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide manufacture of a light guide plate in which finish machining is dispensed with, or operational quantity of the finish machining is minimized, and to provide the light guide plate produced by the manufacture. SOLUTION: A cavity of a female die 6 has a rectangular shape having the size corresponding to that of a light guide plate part 1, and melted acrylic acid resin is injected into the cavity from approximately the center of a side surface on a long side of the cavity. A laser cutting machine 20 determines cutting positions according to the result obtained by scanning a worktable 25 by lasing for positioning from a head 21 and horizontally moving the head 21, and according to the preset cutting information. Then, the head 21 lases the determined cutting positions for machining, and cuts the boundary between the light guiding plate part 1 and a foot part 2.

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 plate used for a backlight of a liquid crystal display, and a light guide plate manufactured by the method.

[0002]

2. Description of the Related Art FIG. 10 is a schematic side sectional view showing a main part of a lighting device built in a liquid crystal display. In the drawing, reference numeral 31 denotes a rectangular light guide plate. FIG. 11 is a schematic perspective view of the light guide plate 31 shown in FIG. On one surface of the light guide plate 31 made of acrylic resin in a rectangular shape, wavy prism portions 35, 35,... Are provided at a required pitch perpendicular to the long sides of the light guide plate 31. The other surface of the light guide plate 31 is flat, and the other surface is covered with a reflection sheet.

On one side of one long side of the light guide plate 31, a reflector 40 having substantially the same length as the long side and having a U-shaped cross section is used to hold the edge of the light guide plate 31 at its opening. Are connected so that
A straight tube lamp 41 having substantially the same length as the long side of the light guide plate 31 is provided in the reflector 40 so as to face the side surface of the light guide plate 31.
The light emitted from the straight tube lamp 41 enters the light guide plate 31 directly or reflected by the reflector 40. The light incident on the light guide plate 31 propagates in the other long side direction of the light guide plate 31 and directly from the prism portions 35, 35,.
The light is reflected by the reflection sheet disposed opposite to 35, 35,... And is emitted from the prism portions 35, 35,.

[0004] Such a light guide plate 31 is manufactured by injection molding. FIG. 12 is a side sectional view showing a closed state of a pair of male and female molds used for injection molding, in which 56 is a female mold and 55 is a male mold. A plurality of grooves corresponding to the above-described prism portions are formed in a predetermined portion of the male mold 55 facing the female mold 56.
The male mold 55 has a through hole 50 penetrating the center thereof. Also, both ends of the through hole 50 are formed into required shapes, respectively, to provide a first concave portion 51 and a second concave portion 52. The molten acrylic resin is press-fitted from the first concave portion 51, and the acrylic resin is inserted into the through hole. It is designed to be poured into the second recess 50 and the second recess 52.

A portion of the female mold 56 facing the second concave portion 52 is provided with a third concave portion 53 corresponding to the second concave portion 52. The third concave portion 53, the second concave portion 52, and the Through hole
Gate 54 through which acrylic resin flows as described above by 50
Are formed. The gate 54 communicates with the center of one short side of a rectangular cavity 59 having a size corresponding to the size of the light guide plate, and injects acrylic resin into the cavity 59 from the gate 54 to form the light guide plate. Molding.

When the light guide plate is formed, the male mold 55 and the female mold 56 are formed.
Is opened, and the light guide plate from which the legs by the gate 54 protrude is taken out from the cavity 59. Then, the leg is cut from the light guide plate by cutting the leg with a hot nipper or the like, and then the cut portion is finished. In this way, by injecting the acrylic resin from one side of the short side of the rectangular cavity 59, the long side of the light guide plate, which is the light incident surface,
Defects such as gate marks were avoided.

[0007]

However, in the conventional method, since the legs are cut by the gate with a hot nipper or the like, the cut portion must be finished, which is a long process. There is a problem that time and a lot of costs are required. In addition, there is a possibility that dust generated when cutting the legs adheres to the front and back surfaces of the light guide plate and causes a defect.

[0008] By the way, notebook personal computers have been made thinner and larger screens. For this reason, the light guide plate is required to have a larger plane dimension and a smaller thickness.

In order to satisfy this requirement, the light guide plate must be formed using a mold having a cavity having a large planar dimension and a small depth. However, when acrylic resin is injected into such a cavity from one side of the short side of the cavity, it is difficult to uniformly inject the acrylic resin into the cavity. The thickness of the part on the opposite side is greater than the thickness of the part on the gate side where the light is emitted, so that a light guide plate with required dimensional accuracy cannot be manufactured.

Therefore, it is conceivable to inject an acrylic resin into the cavity from one long side of the cavity to uniformly fill the cavity with the acrylic resin.
However, there is a problem that a long cutting time and a large cost are required for the finishing process because a cut mark of the leg is formed by the gate on the light incident surface or the surface facing the light incident surface.

The present invention has been made in view of the above circumstances, and a purpose thereof is to inject molten synthetic resin into a cavity from a gate opened in a mold to form a light guide plate portion and the light guide plate portion. From the gate to extend from
Provided is a method for manufacturing a light guide plate, which eliminates the need for finishing or minimizes the amount of operation for finishing by removing the gate from the light guide plate by laser light, and a light guide plate manufactured by the method. Is to do.

Another object is to use a mold in which a gate communicates with the long side of a rectangular plate-shaped cavity, and inject molten synthetic resin into the cavity from the gate opened in the mold to introduce the resin. By forming the light plate portion and the gate portion extending from the light guide plate portion, and removing the gate portion from the light guide plate portion by laser light, a light guide plate having a large planar area and a small thickness does not require finishing or An object of the present invention is to provide a method of manufacturing with a minimum amount of finishing operation, and a light guide plate manufactured by the method.

[0013]

According to a first aspect of the present invention, there is provided a method of manufacturing a light guide plate, wherein molten synthetic resin is injected into a cavity from a gate opened in a mold to project from the light guide plate portion and the light guide plate portion. In a method of manufacturing a light guide plate by forming a gate portion and removing the gate portion from the light guide plate portion, the removal of the gate portion is performed by an energy beam.

The method for manufacturing a light guide plate according to the second invention comprises the first method.
In the invention, a boundary between the light guide plate portion and the gate portion is cut by an energy beam.

[0015] The method for manufacturing a light guide plate according to the third aspect of the present invention comprises:
In the invention, the light guide plate is cut by an energy beam.

The method for manufacturing a light guide plate according to a fourth aspect of the present invention comprises the steps of:
In the present invention, the light guide plate is cut so as to form a convex portion at a predetermined position of the light guide plate.

According to a fifth aspect of the present invention, there is provided a light guide plate manufacturing method comprising:
In any one of the fourth to fourth inventions, an energy beam is applied to a position to be cut from one side and the other side of the light guide plate.

The method for manufacturing a light guide plate according to the sixth aspect of the present invention comprises the steps of:
In the present invention, the two energy beams irradiate the light guide plate obliquely.

According to a seventh aspect of the present invention, there is provided a method for manufacturing a light guide plate, comprising the steps of:
In any one of the sixth to sixth aspects, a laser beam is used as the energy beam.

The method for manufacturing a light guide plate according to the eighth invention comprises the following steps.
In any one of the seventh to seventh aspects, a mold is used in which a gate communicates with a long side of a rectangular plate-shaped cavity.

The method for manufacturing a light guide plate according to the ninth invention is the same as the eighth method.
The invention is characterized in that a mold in which a portion where the gate communicates with the cavity has a triangular shape is used.

A light guide plate according to a tenth aspect of the present invention is to form a light guide plate portion and a gate portion extending from the light guide plate portion by injecting molten synthetic resin into a cavity from a gate opened in a mold. A light guide plate obtained by removing a gate portion from a portion is manufactured by the method for manufacturing a light guide plate according to any one of the first to ninth aspects.

According to the first, seventh and ninth aspects of the present invention, the molten synthetic resin is injected from the gate into the cavity to form the light guide plate and the gate, and the molded member is taken out of the cavity and the energy beam is removed. The gate portion is heated and removed by (laser light). Since the portion heated and removed by the energy beam (laser beam) is smooth, diffuse reflection hardly occurs. Therefore, the finishing process is not required or the operation amount of the finishing process can be reduced as much as possible.
In addition, dust is not generated when the gate portion is removed by heating, and the generation of flaws on the light guide plate due to the dust is prevented.

According to the second, third, seventh and tenth aspects of the present invention, laser light is applied along the boundary between the light guide plate and the gate to cut the gate and remove the gate. Further, a portion near the boundary of the light guide plate is cut by irradiating an energy beam (laser light) from one end to the other end of the light guide plate in parallel with the boundary, and a part of the light guide plate and the gate are removed. I do. In the former case, the manufacturing time can be reduced as much as possible. In the latter case, although the cutting distance is longer than in the former case, the time required for cutting is shorter than in the case of cutting with a hot nipper or the like.

In the fourth, seventh and tenth aspects of the invention, in the latter case, the light guide plate is cut by an energy beam (laser light) so as to form a convex portion at a predetermined position of the light guide plate. By fixing the projection, the light guide plate can be pressed.

According to the fifth, seventh and tenth aspects of the present invention, since the energy beam (laser light) is irradiated to the positions to be cut from both surfaces of the light guide plate, the cut portion by the energy beam (laser light) Burrs can be prevented from being generated.

According to the sixth, seventh and tenth aspects of the present invention, both energy beams (laser beams) are obliquely irradiated onto the light guide plate at the position to be cut, so that the position in the direction orthogonal to the cutting direction is obtained. A cut surface view forms, for example, a triangular projection or depression. Thereby, the light collecting property of the light incident on the light guide plate is improved, and the generation of the bright line at the light emitting portion of the light guide plate is prevented.

In the eighth and tenth aspects of the present invention, even when the plane area of the cavity is large and the depth is small, the mold is used in which the gate communicates with the long side of the rectangular plate-shaped cavity. The entire region in the cavity can be uniformly filled with the molten synthetic resin, and a light guide plate having a large plane area and a small thickness can be manufactured with high dimensional accuracy. Then, the gate portion obtained by molding is cut by an energy beam (laser beam). by this,
As described above, the finishing operation is unnecessary or the operation amount of the finishing operation can be reduced as much as possible.

According to the ninth and tenth aspects of the present invention, a light guide plate having a large plane area and a small thickness can be obtained by using a mold in which a portion where a gate communicates with a cavity is formed in a triangular shape. It can be manufactured with dimensional accuracy.

[0030]

Embodiments of the present invention will be specifically described below with reference to the drawings. (Embodiment 1) FIG. 1 is an explanatory view for explaining the method of the present invention. A switchgear that opens and closes left and right as shown in FIG.
Acrylic resin is injection-molded by an injection molding apparatus 19 in which the female die 6 and the male die 5 are fixed to each other so as to face each other, and as shown in (b), the light guide plate portion 1 and the light guide plate A leg 2 protruding from the part 1 is obtained.

FIG. 2 is a plan view of the female mold 6 shown in FIG. 1. In FIG. 2, reference numeral 7 denotes a rectangular female mold main body. At four corners of the female body 7, fixing holes 8, 8, 8, 8 for fixing the female body 7 to the switch 18 shown in FIG. In the center, when the corresponding male mold 5 (see FIG. 1) is closed, a substantially L-shaped recess forming a gate is formed.
10 are provided.

One end of the concave portion 10 is connected to a through-hole penetrating the male mold 5 (see FIG. 1) in order to press-in the molten acrylic resin, and the other end of the concave portion 10 is connected to the acrylic resin. Is communicated with the cavity 9 for injecting the gas. The cavity 9 is formed in a rectangular shape having a size corresponding to the size of the light guide plate portion 1 (see FIG. 1), and the concave portion 10 communicates with substantially the center of a side portion on one long side of the cavity 9. And recess 10
The molten acrylic resin is injected into the cavity 9 from the inside.

As described above, by injecting the acrylic resin into the cavity 9 from substantially the center of the long side of the cavity 9 into the cavity 9, even if the cavity 9 has a large plane area and a small depth, the entire cavity 9 is formed. Can be substantially uniformly filled with an acrylic resin.

In the vicinity of the injection molding device 19, the cavity 9
A transfer device (not shown) for adsorbing and fixing the light guide plate portion 1 in the inside (see FIG. 2) is provided. After being taken out of the injection molding apparatus 19 and transferred to a predetermined position on the work table 25 of the laser cutting machine 20 as shown in FIG. 1 (c), the light guide plate 1 and the leg 2 are detached and removed. Worktable 25
Place on the upper predetermined position.

The laser cutting machine 20 has a head 21 for emitting a processing laser beam.
It is slidably supported by 22. The x-axis arm 22 is slidably supported by a y-axis arm 23 orthogonal to the x-axis arm 22, and the y-axis arm 23 is moved up and down by an elevator 24.

Then, the laser cutting machine 20 moves the head 21 onto a cutting position determined based on cutting information set in advance.
The laser beam for processing is emitted from the head 21 while moving the head, and the boundary between the light guide plate portion 1 and the leg portion 2 is cut as shown by the broken line in FIG. As a result, the light guide plate 1 has the leg 2
Since the light guide plate can be manufactured by cutting the legs 2 so that the cut surface of the light guide plate portion 1 is substantially flush with the surrounding surface without forming a projecting portion which is a trace of Finishing of the surface is not required.

It is to be noted that both the side surface of the light guide plate manufactured in this manner, in which the leg portion 2 is cut, and the side surface opposed thereto can be formed as the light incident surface.

FIG. 4 is an explanatory view for explaining another cutting position by the laser beam, and is adapted to cut the light guide plate portion 1. As shown by the broken line in FIG. 4, the side of the light guide plate 1 from which the legs 2 protrude is moved in the longitudinal direction and the direction perpendicular thereto so that the protrusions 3 are formed on both sides of the legs 2. Cutting by laser light for processing. In the light guide plate manufactured in this manner, the projections 3 and 3 can be fixed, and the light guide plate is prevented from floating.

(Embodiment 2) FIG. 5 is a plan view showing another female mold in which a communicating portion between a cavity 9 and a gate is formed in a triangular shape. In the figure, portions corresponding to the portions shown in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted.
As shown in FIG. 5, the concave portion 11 communicates with the side of one long side of the cavity 9, and the portion of the concave portion 11 communicating with the cavity 9 has the same bottom dimension as that of the long side of the cavity 9. It is shaped like a triangle. As the molten acrylic resin flows through the recess 11, the width dimension gradually increases,
It is injected into the cavity 9 from the entire region on one long side of the cavity 9. Thereby, even when the plane area of the cavity 9 is large and the depth is shallow, the acrylic resin can be uniformly injected into the entire region in the cavity 9. Therefore,
A light guide plate having a large plane area and a small thickness can be manufactured with high dimensional accuracy.

Then, as shown by a broken line in FIG. 6, the boundary between the light guide plate 1 and the leg 4 is cut. As a result, the leg 4 is cut such that the cut surface of the light guide plate 1 is substantially flush with the surrounding surface without forming a projection which is a trace of the leg 4 on the light guide plate 1. A light guide plate can be manufactured.

In the female mold 6 shown in FIG. 5, the portion of the concave portion 11 communicating with the cavity 9 is formed in a triangular shape whose bottom dimension is the same as the long dimension of the cavity 9. The present invention is not limited to this, and the portion communicating with the cavity 9 of the concave portion may be formed in a triangular shape whose bottom side is shorter than the long side of the cavity 9. by this,
The time required for cutting can be shortened. Also, as before, the side of the light guide plate 1 from which the legs 4 protrude may be cut by a processing laser beam in the longitudinal direction and in a direction perpendicular to the longitudinal direction so that a convex portion is formed. Not even.

FIG. 7 is an explanatory view for explaining another cutting position by the laser beam, in which a triangular portion of the leg 4 is cut. As shown by a broken line in FIG. 7, the triangular portion of the leg 2 is made to extend in the longitudinal direction and at right angles to the longitudinal direction so that two convex portions 3 and 3 are formed near the short side of the light guide plate 1. It is cut in the direction by the processing laser light. In the light guide plate manufactured in this manner, as before, the convex portions 3,
3 can be fixed, and the light guide plate is prevented from floating.

In the above-described embodiment, a case was described in which a mold in which a gate was connected to the long side of the rectangular plate-shaped cavity was used. However, the present invention is not limited to this. It is also possible to use a mold in which a gate communicates with the side of the short side of the cavity, and cut the legs formed by the gate with a laser beam. It goes without saying that either a mold having a cavity corresponding to the light guide plate provided with the above-described prism portion or a mold having a cavity corresponding to the flat light guide plate may be used. When a rectangular plate-shaped cavity corresponding to the light guide plate provided with the prism portion is used, and a mold having a gate communicating with the long side of the cavity is used, a light guide plate having high dimensional accuracy of the prism portion is formed. can do.

(Third Embodiment) FIGS. 8 and 9 are schematic partial side views showing a third embodiment, in which laser light is applied to positions to be cut from both the front and back surfaces of the light guide plate portion 1, respectively. Is shown. As shown in FIGS. 8 and 9, heads 21a, 21a are arranged at a predetermined distance from the front and back surfaces of the light guide plate portion 1 so as to be axially symmetrical. The laser light for processing is irradiated obliquely to the light guide plate portion 1 to form a convex portion 1a or a concave portion 1b having a triangular shape in a side view at a cut portion as shown by a broken line.

Thus, it is possible to prevent burrs from being generated in the portion cut by the laser beam. In addition, the light collecting property of light incident on the light guide plate is improved,
The generation of a bright line in the light emitting portion of the light guide plate is prevented.

In this embodiment, the heads 21a, 21a
The laser light for processing is radiated obliquely to the light guide plate 1 from a. However, the present invention is not limited to this, and the heads 21a, 21a
The laser beam for processing may be irradiated so as to be orthogonal to the light guide plate 1. Further, the processing laser light may be simultaneously emitted from the heads 21a, 21a.
After irradiating the laser beam for processing from the above and cutting approximately half of the light guide plate portion 1 in the thickness direction, the laser beam for processing is irradiated from the other head 21a to cut the remaining portion. Is also good.

[0047]

As described in detail above, the first, second, third,
According to the seventh and ninth aspects, the finishing operation is unnecessary or the operation amount of the finishing operation can be reduced as much as possible.
In addition, dust is not generated when the gate portion is removed by heating, and the generation of flaws on the light guide plate due to the dust is prevented.

According to the fourth, seventh and tenth aspects of the present invention, the light guide plate can be pressed by fixing the convex portion, and the light guide plate is prevented from floating.

According to the fifth, seventh and tenth aspects of the present invention, it is possible to prevent burrs from being generated at a portion cut by the laser beam.

According to the sixth, seventh and tenth aspects of the present invention, a projection or a depression having a triangular cross section in a direction perpendicular to the cutting direction can be formed at the position to be cut.
Thereby, the light collecting property of the light incident on the light guide plate is improved, and the generation of the bright line at the light emitting portion of the light guide plate is prevented.

According to the eighth and tenth aspects of the present invention, even when the plane area of the cavity is large and the depth is small, the entire region in the cavity can be uniformly filled with the molten synthetic resin. A light guide plate having a large plane area and a small thickness can be manufactured with high dimensional accuracy. And since the gate part obtained by shaping | molding is cut | disconnected by a laser beam, finishing processing is unnecessary or the operation amount of finishing processing can be reduced as much as possible.

According to the ninth and tenth aspects of the present invention, a light guide plate having a large plane area and a small thickness can be formed by using a mold in which a portion where a gate communicates with a cavity is formed in a triangular shape. The present invention has excellent effects, for example, it can be manufactured by using

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a method of the present invention.

FIG. 2 is a plan view of the female mold shown in FIG.

FIG. 3 is an explanatory diagram illustrating a cutting position by a laser beam.

FIG. 4 is an explanatory diagram for explaining another cutting position by a laser beam.

FIG. 5 is a plan view showing another female mold.

FIG. 6 is an explanatory diagram illustrating a cutting position by a laser beam.

FIG. 7 is an explanatory diagram illustrating another cutting position by a laser beam.

FIG. 8 is a schematic partial side view showing the third embodiment.

FIG. 9 is a schematic partial side view showing the third embodiment.

FIG. 10 is a schematic side sectional view showing a configuration of a main part of a lighting device built in a liquid crystal display.

FIG. 11 is a schematic perspective view of the light guide plate shown in FIG.

FIG. 12 is a side sectional view showing a closed state of a pair of male and female molds used for injection molding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light guide plate part 2 Leg part 3 Convex part 5 Male type 6 Female type 9 Cavity 10 Concave part 20 Laser cutting machine 21 Head

Claims (10)

[Claims] 1. A molten resin is injected into a cavity from a gate opened in a mold to form a light guide plate and a gate protruding from the light guide plate, and the gate is removed from the light guide plate. The method for manufacturing a light guide plate, wherein the gate portion is removed by an energy beam. 2. The method for manufacturing a light guide plate according to claim 1, wherein a boundary between the light guide plate portion and the gate portion is cut by an energy beam. 3. The method of manufacturing a light guide plate according to claim 1, wherein the light guide plate portion is cut by an energy beam. 4. The method of manufacturing a light guide plate according to claim 3, wherein the cutting of the light guide plate portion is performed such that a convex portion is formed at a predetermined position of the light guide plate. 5. The method of manufacturing a light guide plate according to claim 1, wherein an energy beam is applied to a position to be cut from one side and the other side of the light guide plate. 6. The method for manufacturing a light guide plate according to claim 5, wherein the two energy beams irradiate the light guide plate portion obliquely. 7. The method for manufacturing a light guide plate according to claim 1, wherein a laser beam is used as the energy beam. 8. The method for manufacturing a light guide plate according to claim 1, wherein a mold is used in which a gate communicates with the long side of the rectangular plate-shaped cavity. 9. The method for manufacturing a light guide plate according to claim 8, wherein a mold in which a portion of the gate communicating with the cavity has a triangular shape is used. 10. A synthetic resin melted into a cavity is injected from a gate opened in a mold to form a light guide plate portion and a gate portion extending from the light guide plate portion, and the gate portion is removed from the light guide plate portion. A light guide plate, comprising: a light guide plate manufactured by the method for manufacturing a light guide plate according to claim 1.