JP3261651B2 - Light guide plate mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for manufacturing a light guide plate which is a component of a liquid crystal panel used for a liquid crystal display (LCD).

[0002]

2. Description of the Related Art Display panels used in notebook personal computers are all liquid crystal displays. Currently, active matrix (TFT) type and simple matrix (ST) are used.
N) Two systems are in widespread use.

In order to make a liquid crystal module and panel, as shown in FIG.
0, about 30 components and materials such as a liquid crystal compound 41, an alignment film 42, an electrode substrate 43, a spacer 44, a deflection film 45, a color filter 46, and a backlight 47 are required.

Since the liquid crystal display itself does not emit light, some light source is required for display. LC
With the enlargement of D and the expansion to computer applications, transmission systems in which a dedicated illuminating device (backlight) is provided behind the liquid crystal panel as a light source have become mainstream, and a backlight is indispensable particularly in color display. ing.

The backlight 47 includes a light source, an optical system,
It consists of an inverter (lighting circuit). In most cases, the light source is a fluorescent lamp, particularly a cold cathode fluorescent lamp. There are two types of backlight structures: a direct type in which a light source is disposed directly below a liquid crystal panel, and an edge light type in which a light guide plate is disposed and a light source is disposed at the end thereof. An edge light system is mainly used in which a light source guides a light of a trend lamp to a liquid crystal panel surface by a light guide plate at an end of an LCD portion.

In this edge light system, as shown in FIG. 11, a material having good light transmission such as acrylic resin is used as the light guide plate 10, and a straight tube type fluorescent lamp 48 is provided on two or one side of the light guide plate. Has been arranged. Then, the diffusion sheet 50 and the prism sheet 5 are placed on the light guide plate 10 on the liquid crystal panel side.
1. The reflection sheet 52 is placed on the back side of the light guide plate. further,
Light other than the side surface of the light guide plate around the light source is wrapped with a lamp reflector 53 having a high reflectance, and light is introduced into the light guide plate 10 without waste.

The light is reflected upward by the reflection sheet 52 and enters the panel through the diffusion sheet 50. Light is scattered by printing countless white dots on the light guide plate surface for light scattering. The diffusion sheet 50 has minute irregularities and scatters light to make the luminance uniform. In addition, in order to condense the light scattered from the diffusion sheet on the LCD panel to improve the surface brightness, a low-cost lens sheet is often used instead of the prism sheet on the diffusion sheet.

In general, a wedge-shaped light guide plate is used as the light guide plate, the portion being further away from the fluorescent lamp, the surface of the wedge-shaped light guide plate being a dot-like ink containing white pigment or transparent beads reflecting light. A diffusely diffused film layer is provided by screen printing, whereby light incident inside the light guide plate is diffusely reflected, so that the light near the lamp is bright, and the brightness does not decrease as the distance from the lamp increases, so that the entire surface is uniformly illuminated. ing.

The reflection sheet is disposed on the lower surface and the side surface of the light guide plate, and has a function of reflecting the light that has traveled while reflecting inside the light guide plate so that the light can be used for the LCD panel without waste. The diffusion sheet is disposed on the upper surface of the light guide plate, and scatters light from the light guide plate to make the luminance uniform. Further, the lens sheet is disposed on the diffusion sheet, and has a function of condensing light emitted from the diffusion sheet for the purpose of increasing luminance.

[0010] Such components are now individually manufactured and assembled as backlight assemblies.

Under these circumstances, improvement of the material and shape of the light guide plate and review of the manufacturing method are being actively pursued in order to improve the light use efficiency, reduce the thickness, reduce the weight, and reduce the cost.

For example, improvements have been made to the ink material to be printed on the back surface of the light guide plate, and an injection molding method has been introduced instead of the conventional cutting-out method using a machine (see JP-A-9-131770).

In the injection molding method described in the above publication, a method is described in which, instead of dot printing, a stamper having an optical pattern formed on one or both sides of a mold member is attached and molded, and the mold is used. Further, this mold also discloses a configuration in which a groove or a hole is formed on the surface of a mold member on which the stamper is mounted, and the stamper is attracted to the mold member by vacuum suction from the groove or the hole.

[0014]

SUMMARY OF THE INVENTION In view of the foregoing, the present invention provides a light guide plate having improved positioning stability for forming a diffusely diffused reflection surface on a light guide plate itself and improved stability in forming the light guide plate. It is intended to provide a light plate mold.

[0015]

In order to achieve the above object, a light guide plate mold according to the present invention comprises a claw for positioning and attaching a stamper to the mirror surface plate, and a stamper protruding outside the cavity. A vacuum circuit for sucking a stamper to the mirror plate through a plurality of branched air passages and openings on the mirror plate facing the back surface of the portion, further comprising a vacuum circuit on a side close to the gate; The present invention is characterized in that a restricting means is provided for setting an air passage communicating with the opening of the air passage higher than the suction force of the other air passage.

[0016]

Embodiments of the present invention will be described with reference to the drawings. 1 and 2 show a front view and a side view of a light guide plate mold 1 according to the present invention. Also, FIG.
FIG. 4 is an enlarged partial sectional view showing a runner structure from a sprue to a gate of the light guide plate mold 1, and FIG. 4 is an enlarged partial sectional view showing an arrangement relationship between a cavity and a stamper.

The light guide plate mold 1 has a structure of a general injection mold, and is formed on a fixed mold 2, a movable mold 3, and a lower mirror plate 5 on the parting surface PL. The stamper 7 is disposed on the upper mirror plate 6 facing the cavity 4.

In the light-guiding plate mold 1, a locating ring 8 into which an injection nozzle (not shown) of a molding machine is inserted is mounted on a fixed-side mounting plate 9, and a sprue bush 28 fitted into the fixed mounting plate 9 is provided. The molten resin passes through the sprue hole 29, passes through the runner 35, goes to the gate G from the side, and is filled from the gate G into the cavity 4.

The stamper 7 has, on the surface on the cavity side, a diffusely diffused reflection surface of an optical pattern in which a large number of regular grooves and dots are formed. Then, the light guide plate mold 1 having the stamper 7 forms the light guide plate 10 in which the cavity is filled with the molten resin by injection molding and the diffusely diffused reflection surface of the stamper 7 is transferred.

Since the light guide plate 10 has a diffusely diffused reflection surface formed on its surface, the light guide plate 10 itself has a diffusion sheet,
A diffused diffuse reflection function such as a lens sheet and a reflection sheet can be provided.

In a preferred embodiment of the present invention shown in FIG. 4, the stamper 7 is attached to one of the mirror plates, here the upper mirror plate 6, by claws 11a to 11d as stamper retainers. It is also possible to arrange the stampers 7 on the face plates 6 and 5.

The cavity 4 formed in the lower mirror plate 5 has a wedge-shaped cross section. In FIGS. 2 and 4, the cavity 4 is formed so that its thickness decreases from the right side to the left side. I have. The gate G is provided in the thick part. This is because, when filling is performed from the thin portion, the molten resin flows first in the thicker direction, and the filling in the direction toward the thin portion from the gate position is the last, resulting in a short shot.

Further, the stamper 7 has the cavity 4
, Which protrudes outside the periphery of the product, and as described later, is close to four sides of the product end face,
A vacuum circuit 12 (see FIGS. 5 and 6) for adsorbing the stamper 7 to the upper mirror plate 6 is provided.

FIG. 5 schematically shows the arrangement of the vacuum circuit and the claws 11a to 11d for fixing the stamper 7, as viewed from the movable mounting plate at the bottom of the mold. Also,
FIG. 6 is a connection diagram showing a connection relationship between the air passage and the opening of the vacuum circuit 12.

The vacuum circuit 12 has a plurality of branched air passages 13 to 18 and openings 20 to 27 on the upper mirror plate 6 facing the back surface of the stamper portion projecting outside the cavity 4.

As shown in FIG. 5, these air passages are provided with one branched air passage 13 and 14 at the upper and lower positions of the product X (inside of the dashed line), and at the left and right positions of the product. 2 air passages 15, 16; 1 each
7, 18 are arranged. The air passages 13 and 14 at the upper and lower positions respectively have two openings 20, 21;
The air passages 15 to 18 at the left and right positions have one opening 24 to 28, respectively.

As shown in FIG. 6, the air passages 13 and 15 near the gate G are arranged upstream of the suction side near the air suction pump source P. Further, the other air passages 14, 1
Nos. 6 to 18 are provided with air passages 13 and 18 by sequentially increasing the pipe distance or adding restricting means such as changing the cross-sectional area of the pipe.
It is connected so that the suction force is lower than 15.

Thus, the stamper 7 repeats expansion and contraction due to heat from the molten resin. Such a stamper 7
The suction force of the air passage near the gate was made stronger than the suction force of the air passage separated from the gate in order to absorb the displacement at the portion separated from the gate, which is downstream of the flow of the molten resin.

Further, in the embodiment of the present invention, in order for this restricting means to work more effectively, the air passages 15, 1
The throttle valve 30 and the air passages 14 and 1
A throttle valve 31 is provided upstream of the point 28 where the air flow branches to the points 7 and 18 on the intake side.
Is provided.

The throttle valves 30, 31 allow the air passages 13, 15 on the side close to the gate G to pass through the other air passages 14, 16, 17, 18 without being influenced by the piping distance or the like.
This is a limiting means that can easily be set higher than the suction force.

As described above, in the embodiment of the present invention, the branch air passage near the gate is provided on the upstream side of the air suction source.
Alternatively, a throttle valve is provided at the passage opening of the other branch air passage so that the suction force of the air can be controlled, so that the suction force of the air of the vacuum circuit is not uniform at each opening but the suction of the branch air passage near the gate is performed. Designed to enhance power.

As shown in FIGS. 7 and 8, which is a detailed view of the vicinity of the gate in FIG. 3, each air passage on the upper mirror plate has a depth of 0.3 mm and a cross section having a concave surface of R3. When the thickness of the stamper 7 is 0.285 mm,
The stamper storage height of the upper mirror plate 6 is 0.3 mm. As a result, a step C (see FIG. 8) of 0.015 mm occurs between the end face of the stamper and the surface of the mirror plate. The step C is for preventing the side surface of the stamper from receiving pressure in the flow direction of the resin by the molten resin passing through the runner 35 communicating with the gate G. , Lower than the runner.

Further, in FIG. 7, reference numeral 60 denotes a template, which is provided on the outer peripheral side surface of the mirror plate 5 to form a side wall of the cavity 4. A gap G2 is provided between the template 60 and the surface of the stamper 7 placed on the mirror plate 6 facing the template 60. Gap G2 forms parting of cavity 4,
Slipping accompanying the expansion and contraction of the stamper 7 is allowed to the extent that the molten resin does not leak to form burrs, and the gas and the like generated from the molten resin are separated from the vacuum circuit 12 and the gap G1 between the stamper 7 and the claw 11 by further parting. Release to the atmosphere through the surface PL.

That is, the stamper portion projecting outside the cavity has a gap in the vertical direction (the opening and closing direction of the mold) between the mold plate 60 and the claw 11 facing the parting surface of the cavity. Also, there is a lateral gap between the edge of the stamper and the pawl that does not contribute to the positioning of the stamper. In the present embodiment, the vertical gap G
1 and G2 are both 0.01 to 0.02 mm.

On the other hand, in the embodiment of the present invention, in addition to the vacuum circuit 12, claws 11a to 11d for securely fixing the stamper 7 to the upper mirror plate 6 are arranged on four sides of the stamper. These stamper holding claws 11a to 11d
A fastener (see FIG. 7) 32 such as a screw or a bolt is attached to the upper mirror plate 6 with one edge pressing one side of the stamper 7.
Is fixed by

As a result, it is possible to position the stamper 7 at a predetermined position on the upper mirror plate 6, and to prevent movement due to expansion and contraction due to the flow of the molten resin flowing from the gate shown in FIG. 5 and rotational displacement of the stamper. .

This claw is configured to also serve as a positioning block as shown in FIG. That is, in FIG. 9 (a), two claws located on opposite sides adjacent to the runner 35 of the product are used as positioning reference blocks 36, and in FIG. 9 (b), R-shaped projections engaging with the concave portions of the stamper are shown. The claw having the portion is configured as a reference block 37 for positioning. In FIG. 9C, one claw forming a reference block for positioning one side and a stamper holder fitted into one opening provided on the stamper are configured to function as a hole reference block 38. I have.

With these structures, the claw or the positioning block formed integrally with the claw prevents the stamper from being displaced or rotated by the flow of the resin from the gate. . On the other hand, a claw not involved in the positioning is provided with a distance of 1 to 2 mm between the claw and the end face of the stamper, so that the mirror plate can be freely accommodated based on the claw positioned by the stamper.

In a preferred embodiment of the present invention, the stamper 7 is attached to the four claws 11a to 11d and the vacuum circuit 12
The pawls are used for positioning when attaching the stamper and for safety when the vacuum is cut.

Further, by using the vacuum circuit for holding the stamper, the influence of air on the back surface of the stamper can be reduced, and furthermore, the floating of the stamper from the mirror plate can be suppressed. As a result, the degree of adhesion of the stamper to the mirror plate is improved, and the heat from the molding material can be evenly transmitted to the entire mirror plate, thereby increasing the cooling effect. Then, the work of attaching and detaching the stamper can be easily performed.

[0041]

As described above, the light guide plate mold of the present invention reduces the number of components of the light guide member for the backlight by transferring the diffusely diffused reflection surface formed on the surface of the stamper to the light guide plate. be able to. In addition, the stamper is accurately positioned and fixed to the mirror plate using the vacuum circuit and the claw, and the movement of the stamper caused by molding conditions such as injection speed is stopped by the strength of the suction force of the vacuum circuit to achieve high accuracy. The light plate can be molded.

[Brief description of the drawings]

FIG. 1 is a front view of a light guide plate mold according to the present invention.

FIG. 2 is a side view of the light guide plate mold shown in FIG.

FIG. 3 is an enlarged partial cross-sectional view illustrating a runner structure of the light guide plate mold of FIG. 1;

FIG. 4 is a side view showing a structure around a cavity in FIG. 2;

FIG. 5 is a view showing an arrangement of a vacuum circuit and claws provided in a light guide plate mold according to the present invention.

FIG. 6 is a schematic configuration diagram of a vacuum circuit in FIG. 4;

FIG. 7 is an enlarged partial sectional view showing a sectional shape of an air passage and a claw according to the present invention.

FIG. 8 is an enlarged partial sectional view showing a relationship between a stamper and a runner at a gate position of a mold according to the present invention.

FIG. 9 is a modified example (a) to an arrangement of a positioning block integrated with a claw provided on a light guide plate mold according to the present invention.
It is a schematic block diagram which shows (c).

FIG. 10 is a schematic view showing the structure of a conventional liquid crystal panel.

FIG. 11 is a schematic view showing the structure of a conventional backlight component.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light guide plate mold 4 cavity 5, 6 mirror surface plate 7 stamper 10 light guide plate 11 a-11 b claw 12 vacuum circuit 13-18 air passage 20-27 opening 30, 31 throttle valve

Continuation of the front page (51) Int.Cl. ⁷ identification code FI B29L 31:34 G02F 1/1335 530 (58) Investigated field (Int.Cl. ⁷ , DB name) B29C 45/26-45/37 G02B 6 / 00 G02F 1/1335

Claims (4)

(57) [Claims] 1. A cavity for forming a light guide plate, and a mirror plate on at least one side of the cavity,
A light guide plate mold having a stamper for forming a diffusely diffused reflection surface on the light guide plate, a claw for positioning and attaching the stamper to the mirror surface plate, and a stamper portion projecting outside the cavity. On the mirror plate facing the back surface, a vacuum circuit that suctions a stamper to the mirror plate via a plurality of branched air passages and openings is further provided.The vacuum circuit further includes an air passage close to a gate.
A light-guiding plate mold provided with limiting means for setting the suction force higher than the suction force of another air passage. 2. The stamper is characterized in that the stamper has a step between the runner and the runner so that the edge is lower than the runner at an end face position of the stamper surface facing the runner leading to the gate. The light guide plate mold according to claim 1. 3. The light guide plate mold according to claim 1, wherein the restricting means includes a throttle valve arranged in an air passage located on a side remote from the gate. 4. A stamper portion projecting outside of the cavity has a vertical gap between a template and a claw facing each other along a parting surface of the cavity, and an edge of the stamper and a stamper. 2. The light guide plate mold according to claim 1, further comprising a gap in a lateral direction between the claw and the claw not involved in the positioning of the light guide plate.