JP2015058642A - Light guide plate and metallic mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve suppression of the luminance unevenness of a light guide plate.SOLUTION: A light guide plate 20 of the present invention includes: a runner part 25 extending in a first direction X; a light guide plate forming part 29 of platy shape having a width wider than the runner part in plane view; and a gate part 27 which connects the end 25b on the light guide plate forming part side, of the runner part and the lateral face 29a of the light guide plate forming part with each other, and has a width that becomes wider as it approaches the lateral face in plane view. The shape of the gate part in plane view has: a first side 27a connecting to the end of the runner part and extending in the direction that intersects with the first direction; and a second side 27b whose angle β formed between the first direction is closer to a right-angle than the angle α formed between the first direction by the first side, and connecting to the end 27aon the light guide plate forming part side of the first side.

Description

  The present invention relates to a light guide plate and a mold.

  A liquid crystal display device having a backlight unit has been developed as a thin and light display device. The backlight unit includes a plate-shaped light guide plate and a light emitting diode disposed on an end surface of the light guide plate.

  As a method for manufacturing such a light guide plate, so-called injection molding is known. For example, Patent Document 1 discloses a method of injecting resin into a mold having a portion where a main body of a light guide plate is formed and an injection port for injecting resin into the portion. The resin is spread from the outside to the entire molded product forming part by being injected into the mold through the injection port under pressure. Thereafter, the light guide plate is formed by removing the cured resin from the mold.

JP 2009-198670 A

  With the recent increase in size of the light guide plate and the molded product forming part of the mold, it is necessary to inject resin into the mold at a high speed, so there is a sink (dent) at the boundary between the injection port and the molded product forming part. It tends to occur. Further, if the injection port is enlarged in order to suppress the occurrence of sink marks, the pressure of the injection of the resin into the molded product forming portion is required because the volume of the injection port increases. For this reason, it becomes easy to generate | occur | produce a shaping | molding nonuniformity in a molded article formation part. As a result, luminance unevenness of the light guide plate is likely to occur.

  This invention is made | formed in view of such a situation, Comprising: It aims at implement | achieving suppression of the brightness nonuniformity of a light-guide plate.

Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  (1) The light guide plate of the present invention includes a runner portion extending in a first direction, a plate-shaped light guide plate forming portion having a width wider than the runner portion in plan view, and the light guide plate of the runner portion. Connecting the end portion on the forming portion side and one side surface of the light guide plate forming portion, and having a gate portion whose width becomes wider as approaching the one side surface in plan view, and the plan view shape of the gate portion is The first side connected to the end of the runner portion and extending in a direction intersecting the first direction and the angle formed with the first direction are such that the first side is the first direction. And a second side connected to the end of the first side on the light guide plate forming part side, extending in a direction closer to a right angle than the angle formed by the first side.

  (2) In the light guide plate of the present invention, in (1), even if the width of the side surface of the gate portion connected to the one side surface of the light guide plate forming portion is the same as the width of the one side surface in plan view. Good.

  (3) The mold of the present invention includes a cylindrical runner extending in a first direction, a hollow light guide plate molding portion having a width wider than the runner in plan view, and the light guide plate of the runner. And connecting the end portion on the molding portion side with one side surface of the light guide plate molding portion, and a hollow gate whose width increases as the side surface approaches the one side surface, and the plan view shape of the gate is The first side connected to the end of the runner and extending in a direction intersecting the first direction, and the angle formed with the first direction is such that the first side is the first direction. And a second side connected to an end portion of the first side on the light guide plate molding part side, extending in a direction closer to a right angle than an angle formed.

  According to the present invention, since the occurrence of sink marks in the light guide plate forming portion is suppressed, it is possible to suppress uneven brightness in the light guide plate forming portion.

It is a schematic perspective view of the metal mold | die which concerns on one Embodiment of this invention. 2 is a schematic cross-sectional view taken along the line II-II of the mold shown in FIG. FIG. 3 is an enlarged schematic plan view of a region III of the mold shown in FIG. It is a schematic perspective view of the light-guide plate which concerns on one Embodiment of this invention.

  Hereinafter, the metal mold | die 1 which concerns on this embodiment is demonstrated based on drawing. Note that the drawings referred to in the following description may show the features that are enlarged for convenience in order to make the features easier to understand, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent. In addition, the materials and the like exemplified in the following description are examples, and each component may be different from them, and can be changed and implemented without changing the gist thereof.

  FIG. 1 is a schematic perspective view of a mold 1 according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view taken along the line II-II of the mold 1 shown in FIG. The mold 1 is made of metal, for example, and has a cavity 1a and a core 1b. The mold 1 includes a sprue 3, a runner 5, a gate 7, and a light guide plate molding portion 9, and the sprue 3, the runner 5, and the gate 7 are formed by combining the cavity 1 a and the core 1 b. And the light-guide plate shaping | molding part 9 comprises the space part for forming the light-guide plate mentioned later.

  The sprue 3 is a path for allowing the molten resin injected from a nozzle (not shown) to flow into the runner 5. The sprue 3 has a hollow cylindrical structure provided in the cavity 1a. For example, the sprue 3 has an inner periphery 3a that spreads from the nozzle side toward the runner 5 side.

  The runner 5 is a path for guiding the molten resin flowing in from the sprue 3 to the gate 7. The runner 5 is hollow and has a cylindrical configuration. In the present embodiment, a configuration in which, for example, two runners 5 are connected to one sprue 3 is shown, but the number of runners 5 connected to the sprue 3 may be two or more.

  The runner 5 extends in the first direction (the X direction in the drawing in the present embodiment). The “first direction” in the present embodiment indicates the axial direction of the part 5 a connected to the gate 7 in the runner 5. For this reason, even if the runner 5 has a polygonal line shape and extends in a plurality of directions, the direction of the axis A of the portion 5a connected to the gate 7 becomes the “first direction”. The first direction (direction X) is perpendicular to the boundary B between the gate 7 and a light guide plate molding portion 9 described later.

  The gate 7 is a part for guiding the molten resin flowing from the runner 5 into the light guide plate molding part 9. The gate 7 is hollow and connects the end portion 5 b of the runner 5 on the light guide plate molding portion 9 side and one side surface 9 a of the light guide plate molding portion 9. In the present embodiment, the one side surface 9 a indicates a side surface on the runner 5 side among the plurality of side surfaces of the light guide plate molding part 9. The one side surface 9a extends along the boundary B.

3 is an enlarged schematic plan view of a region III of the mold 1 shown in FIG. The width of the gate 7 increases as it approaches the side surface 9a in plan view. The plan view shape of the gate 7 is connected to the end portion 5b of the runner 5 and has a first side 7a extending in a direction intersecting the axis A extending in the first direction X, and a light guide plate of the first side 7a. It has a second side 7b to be connected to the end portion 7a ₁ of the molded part 9 side.

  Assuming that the angle formed by the first side 7a and the first direction X (axis A) is an angle α, the angle β formed by the second side 7b and the first direction X (axis A) is perpendicular to the angle α. A value close to. That is, the second side 7b extends in a direction intersecting with the axis A at an angle β.

The gate 7, as long as its width increases as it approaches the one side surface 9a side in a plan view, the third side 7c is connected to an end portion 7b ₁ of the light guide plate molding portion 9 side of the second side 7b You may do it. Further, the side of the gate 7 is not limited to three and may be more than this.

The width d ₁ of the side surface 7d of the gate 7 connected to the one side surface 9a of the light guide plate molding portion 9 is preferably the same as the width d ₂ of the one side surface 9a of the light guide plate molding portion 9 in plan view. In the present embodiment, since the end portion 7c ₁ of the third side 7c is connected to the end portion 9a ₁ of the one side surface 9a of the light guide plate molding portion 9, the width d ₁ (end portion 7c _{1) of the} side surface 7d. The width between them is equal to the width d ₂ of one side surface 9a (the width between the end portions 9a ₁ ).

  Further, as shown in FIG. 2, the thickness of the gate 7 may be reduced from the end 5 b of the runner 5 to the boundary B.

  The light guide plate molding unit 9 is a hollow region for molding the filled molten resin into the light guide plate. The light guide plate molding part 9 has a width wider than the runner 5 in plan view, and the outer shape of the space has a plate-like configuration.

  As shown in FIGS. 2 and 3, for example, a hole-like air venting portion 9 b for venting air is provided at the end of the light guide plate molding portion 9 and at a portion overlapping the parting line 1 c of the cavity 1 a and the core 1 b. It is preferable that The location where the air vent 9b is provided is preferably as the distance from the boundary B of the gate 7 increases. Further, the air vent portion 9b may have a groove shape instead of a hole shape as long as the air vent portion 9b can be vented.

  Since the mold 1 has such a configuration, when molten resin as a light guide plate material is injected into the sprue 3 from a nozzle (not shown), the molten resin sequentially passes through the sprue 3, the runner 5, and the gate 7. It passes through and is filled in the light guide plate molding part 9. And the light guide plate 20 shown in FIG. 4 is formed by hardening | curing molten resin and taking out from the metal mold | die 1. FIG.

  FIG. 4 is a schematic perspective view of the light guide plate 20 according to an embodiment of the present invention. The outer shape of the light guide plate 20 is the same as that of the runner 5, the gate 7, and the light guide plate molding part 9. For this reason, the light guide plate 20 includes a sprue portion 23, a runner portion 25 extending in the first direction (X direction), and a plate-shaped light guide plate forming portion 29 having a width wider than the runner portion 25 in plan view. And the end portion 25b on the light guide plate forming portion 29 side of the runner portion 25 and one side surface 29a of the light guide plate forming portion 29 are connected, and the width of the gate portion 27 increases as it approaches the one side surface 29a in plan view. ,have.

Moreover, the planar view shape of the gate part 27 comprises the 1st edge | side 27a connected to the edge part 25b of the runner part 25, and the 1st direction 27 extended in the direction which cross | intersects a 1st direction (direction X). angle β is, the first side 27a extending in a direction nearly at right angles than the angle α formed by the first direction X, is connected to the end portion 27a ₁ of the light guide plate forming portion 29 side of the first side 27a 2 Side 27b.

The gate portion 27, as long as its width increases as it approaches the one side surface 29a side in a plan view, the third side 27c to the end portion 27b ₁ of the light guide plate forming portion 29 side of the second side 27b is It may be connected. Moreover, the side which the gate part 27 has is not restricted to three, The number beyond this may be sufficient.

In the light guide plate 20 in the present embodiment, the width d ₁ of the side surface 27 d of the gate portion 27 is the same as the width d ₂ of the one side surface 29 a of the light guide plate forming portion 29 in plan view.

  The mold 1 of the present embodiment has a gate 7 having a first side 7a and a second side 7b extending at an angle closer to a right angle with respect to the axis A than the first side 7a. Even if the molten resin flows from the runner 5 to the gate 7 at a high speed, the molten resin is injected into the light guide plate molding portion 9 while spreading from the first side 7a to the second side 7b. This prevents the molten resin from being injected into the light guide plate molding unit 9 at a high speed. For this reason, even if the molten resin filled in the light guide plate molding portion 9 is cured, the occurrence of sink marks in the light guide plate 20 is suppressed, and luminance unevenness and chromaticity difference in each region of the light guide plate 20 are reduced. be able to.

  In the mold 1 of the present embodiment, the gate 7 has a first side 7a and a second side 7b extending with respect to the axis A at an angle closer to a right angle than the first side 7a. As a result, the volume of the gate 7 becomes smaller than that of a mold not having this configuration. For this reason, the pressure of the molten resin required to fill the molten resin into the light guide plate molding portion 9 through the gate 7 can be reduced. Thereby, the shaping | molding nonuniformity of the light-guide plate 20 is suppressed.

  Moreover, since molten resin is prevented from being injected into the light guide plate molding part 9 at a high temperature, the chromaticity difference in the surface of the light guide plate 20 can be reduced.

  Further, in the mold 1 of the present embodiment, the gate 7 has a smaller volume from the end 5b of the runner 5 to the boundary B, so that the volume of the gate 7 is smaller than that of the mold not having this configuration. Get smaller. For this reason, the pressure required for filling the entire inside of the gate 7 with the molten resin can be reduced, and uneven formation of the light guide plate 20 and uneven brightness can be suppressed.

Further, in the mold 1 of the present embodiment, the width d ₁ of the side surface 7d of the gate portion 7 is the same as the width d ₂ of the one side surface 9a of the light guide plate molding portion 9 in plan view. The pressure fluctuation at the boundary B when the resin is injected into the light guide plate molding portion 9 is suppressed. For this reason, the occurrence of sink marks in the light guide plate 20 is suppressed.

  Further, the mold 1 of the present embodiment is provided with the air vent part 9b, so that the air reservoir when the molten resin is filled in the light guide plate molding part 9 is compared with a mold that does not have this configuration. Can be prevented.

  As mentioned above, although embodiment of this invention was described, this invention is not restricted to embodiment mentioned above. For example, the configuration described in the above-described embodiment may be replaced by a configuration that has substantially the same configuration, a configuration that exhibits the same operational effects, or a configuration that can achieve the same purpose.

1 mold, 3 sprue, 5 runner, 5b end, 7 gate, 7a first side, 7a ₁ end, 7b second side, 7d side, 9 light guide plate molding part, 9a one side, 9b air vent 20 light guide plate, 25 runner portion, 25b end portion, 27 gate portion, 27a first side, 27a ₁ end portion, 27b second side, 27b ₁ end portion, 27d side surface, 29 light guide plate forming portion, 29a Side, A axis, B boundary, d ₁ , d ₂ width, X first direction, α, β angle.

Claims (3)

A runner portion extending in a first direction;
A plate-shaped light guide plate forming part having a width wider than the runner part in plan view;
Connecting the end portion on the light guide plate forming portion side of the runner portion and one side surface of the light guide plate forming portion, and a gate portion whose width becomes wider as approaching the one side surface in plan view;
With
The shape of the gate portion in plan view is
A first side connected to the end of the runner portion and extending in a direction intersecting the first direction;
The angle formed with the first direction extends in a direction closer to a right angle than the angle formed by the first side with the first direction, and is connected to the end of the first side on the light guide plate forming unit side A second side to
A light guide plate characterized by comprising: The light guide plate according to claim 1,
The width of the side surface of the gate portion connected to the one side surface of the light guide plate forming portion is the same as the width of the one side surface in plan view.
A light guide plate characterized by that. A cylindrical runner extending in a first direction;
A hollow light guide plate molding portion having a width wider than the runner in plan view,
The end of the runner on the light guide plate molding part side and one side surface of the light guide plate molding part are connected, and a hollow gate whose width becomes wider as it approaches the one side surface in plan view,
With
The shape of the gate in plan view is
A first side connected to the end of the runner and extending in a direction intersecting the first direction;
The angle formed with the first direction extends in a direction closer to a right angle than the angle formed by the first side with the first direction, and is connected to the end of the first side on the light guide plate molding unit side A second side to
A mold characterized by having.

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