KR20100000799A

KR20100000799A - Method for fabricating a light guide plate of liquid crystal display device

Info

Publication number: KR20100000799A
Application number: KR1020080060428A
Authority: KR
Inventors: 박재현
Original assignee: 엘지디스플레이 주식회사
Priority date: 2008-06-25
Filing date: 2008-06-25
Publication date: 2010-01-06

Abstract

PURPOSE: A method for manufacturing a light guide plate of a liquid crystal display device is provided to mass-produce a wedge type light guide plate and a plate type light guide plate through an extrusion process, thereby reducing manufacturing costs. CONSTITUTION: A resin is inserted between the first polishing roll(165) and the second polishing roll(167) facing each other. The first polishing roll is transferred gradually upward about a successive unit time so that a plate of ununiform thickness is formed. The first polishing roll is transferred gradually downward at the speed which is the same as the upward movement speed during a predetermined time so that light guide plates of ununiform thickness are formed. The light guide plates are symmetrical. Or, the first polishing roll is gradually transferred downward at different speed from the upward transferring speed so that light guide plates of ununiform thickness are formed. The light guide plates are asymmetrical. The light guide plate is cut in a cutting unit so that the first and second light guide plates are formed.

Description

Manufacturing method of light guide plate of liquid crystal display device {METHOD FOR FABRICATING A LIGHT GUIDE PLATE OF LIQUID CRYSTAL DISPLAY DEVICE}

The present invention relates to a method of manufacturing a light guide plate of a liquid crystal display device, and more particularly, to a method of manufacturing a light guide plate of a liquid crystal display device capable of simultaneously forming a plate type light guide plate and a wedge type light guide plate through an extrusion process. Related.

Generally, a liquid crystal display device includes a liquid crystal panel including a thin film transistor array substrate and a color filter substrate facing each other, and a liquid crystal layer formed between the two substrates. And a driving unit for realizing an image on the liquid crystal panel and a backlight device for supplying light to the liquid crystal panel.

Here, the unit pixels are arranged in a matrix form on the array substrate. In this case, the unit pixel is defined by intersecting a plurality of data lines arranged on the array substrate at regular intervals in the longitudinal direction and a plurality of gate lines arranged at regular intervals in the lateral direction.

Sub-color filter layers of red (R), green (G), and blue (B) are formed on the color filter substrate to correspond to the pixels of the array substrate. In addition, a black matrix is further formed to prevent light leakage between the color filter layers and to prevent color interference of light passing through the pixels.

In addition, a common electrode and a pixel electrode are formed on the inner surfaces of the color filter substrate and the thin film transistor array substrate that are bonded to each other to apply an electric field to the liquid crystal layer. The pixel electrode is applied to each pixel on the thin film transistor array substrate. On the other hand, the common electrode is formed integrally with the entire surface of the color filter substrate.

Accordingly, by controlling the voltage applied to the pixel electrode in the state where the voltage is applied to the common electrode, the arrangement of the liquid crystal molecules formed in the liquid crystal layer may be changed, and as a result, the light transmittance of the pixels may be individually controlled.

On the other hand, the backlight device supplies light to the liquid crystal panel that does not emit light, unlike the self-luminous element. When the light provided from the backlight device passes through the liquid crystal layer, the light transmittance is determined by the arrangement state of the liquid crystals so that an image is displayed. .

The backlight device is classified into an edge type and a direct type according to the position of a lamp used as a light source. The edge method is a method in which a lamp is disposed on one side or both sides of the liquid crystal panel to guide light generated from the lamp to the entire screen of the liquid crystal panel by guiding the light generated by the light guide plate.

In addition, the direct method began to be developed mainly as the size of the liquid crystal panel began to be enlarged to 20 inches or more. A plurality of fluorescent lamps were arranged in a row on the lower surface of the diffuser plate to provide light to the entire surface of the liquid crystal panel. Investigate directly. Such a direct method is mainly used for a large screen liquid crystal display device requiring high luminance because the light utilization efficiency is higher than that of the edge method.

In this case, Cold Cathode Fluorescent Lamp (CCFL), Hot Cathode Fluorescent Lamp (HCFL), Electro Luminescence (EL), and Light Emitting Diode (LED) are used as light sources. Cold cathode fluorescent lamps and LED lamps with low power consumption have been widely used.

The edge method uses a wedge-shaped light guide plate in which the thickness of one side and the thickness of the other side are formed differently when the lamp is disposed only on one side of the liquid crystal panel, while the lamp is uniform on each other when the lamp is disposed on both sides of the liquid crystal panel. The plate-shaped light guide plate formed to a thickness is used.

In this regard, Figure 1 is a view showing a light guide plate manufacturing method through injection molding, Figure 2 is a view showing a post-process of the wedge-shaped and plate-shaped light guide plate formed by the injection molding of FIG.

As illustrated in FIG. 1, the injection apparatus includes a cavity in which a light guide plate is formed, and a molten resin injection unit for introducing molten resin into the cavity. The cavity is composed of a first mold part 10 and a second mold part 20 for forming a pattern on the upper and lower surfaces of the light guide plate. The molten resin injection unit is composed of an injection cylinder 31 for introducing the thermoplastic resin 30 into the cavity, a screw 33 for controlling the flow of the resin 30, and the like.

In this case, in the general injection molding method, after molding the first and second mold parts 10 and 20, molten resin is introduced into the cavity, and after injection molding, the transparent resin in the cavity is cooled and solidified. The mold of the mold part and the second mold part 10, 20 is opened to separate the light guide plate from the mold assembly, for example, and then injection is completed.

As shown in FIG. 2, the plate-type (FIG. 2 (a) and the wedge-shaped light guide plate (FIG. 2 (b)) separated from the mold assembly generate burrs 40 and the like into which the thermoplastic resin is introduced into the cavity. The burr 40 is finally removed through post-processing such as cutting and grinding to complete a complete plate and wedge light guide plate.

Usually, such injection molding changes shape in the mold part according to the optical design, and it is possible to form a wedge type and a plate type light guide plate.

3 is a flowchart illustrating a mold manufacturing process of FIG. 1.

As shown in FIG. 3, the mold fabrication is basically divided into 1) main core fabrication (FIG. 3 (a)) and 2) stamper pattern fabrication (FIG. 3 (B)). The mold making of the core determines the shape of the light guide plate, that is, the wedge shape or the plate shape, and the production of the stamper pattern determines the scattering pattern density of the upper surface of the light guide plate.

As shown in Fig. 3 (a), the main core is basically manufactured in the order of the main body, that is, the main core (S01) ⇒ main core (surface) plating (S13) ⇒ main core side polishing (S15) (wedge type). As shown in (b) of FIG. 3, the stamper pattern fabrication is performed in the order of pattern fabrication bite fabrication (S20) ⇒ stamper pattern processing (S21) ⇒ stamper (pattern) plating film formation (S23).

As such, after the production of the main core and the stamper is completed, the mold for manufacturing the light guide plate is finally completed through the mold assembly (S30).

However, since the mold process is injection molding one light guide plate discontinuously through one mold core, mass production of the light guide plate is impossible.

In addition, as can be seen in the mold manufacturing process, mold making requires a lot of time, manpower, and cost. In addition, the production efficiency is extremely low even when manufacturing such a mold, and as a result, the schedule for developing a product is delayed.

In addition, it is difficult to ensure accuracy and reproducibility in the pattern production.

In addition, in order to obtain a light guide plate that satisfies the quality during injection, manufacturing factors such as molten resin inflow rate and pressure, cooling rate, and injection pin position, which are conditions of an injection molding machine, must be considered. Through this, stable injection conditions can be derived.

Of course, the above thermoplastic resin can be used in injection molding as described above, but can also be used in the extrusion process. Currently, the diffusion plate among the optical components of the LCD backlight is manufactured through an extrusion process, and thus it is well understood from this.

FIG. 4 is a schematic diagram of a conventional extrusion process equipment, and FIG. 5 is a view of the stationary polishing roll of FIG. 4.

As shown in Figures 4 and 5, the conventional extrusion process is largely made in the order of resin melting and transfer ⇒ disc thickness control and primary cooling ⇒ extruded disc secondary cooling and transfer ⇒ extruded disk forced transfer.

However, this extrusion process equipment is a trend that is used only to produce a plate-like plate, such as a diffusion plate having a substantially uniform thickness because the use of a stationary polishing roll.

For example, the fixed polishing roll is a plate-type having a predetermined thickness by injecting the transferred resin between the first polishing roll 65 and the second polishing roll 67 fixed at a specific interval when the molten resin is transferred. The plate 70 is produced, which has many advantages over injection molding, but is limited to forming a plate of plate type.

As a result, optical components such as wedge-shaped light guide plates of LCD backlights are inevitably formed only by injection molding, and thus, wedge-type light guide plates have increased costs, which in turn leads to an increase in manufacturing cost of liquid crystal display devices.

In order to improve the above problems, the present invention provides a continuous polishing roll of the extrusion process equipment in order to form both plate and wedge light guide plates through an extrusion process. The present invention provides a method for manufacturing a light guide plate of a liquid crystal display device, which is configured to be movable, and through which the light guide plate of the liquid crystal display device can be efficiently manufactured.

A light guide plate manufacturing method of a liquid crystal display device according to the present invention for achieving the above object is at least two polishing rolls are continuously arranged at regular intervals by fixing or simultaneously fixing each axis, and one of the plurality of rolls In the polishing roll machine of the extrusion process comprising a position-moving hydraulic device coupled to the axis of the polishing roll of the roller to move the axis up and down, or to the left and right to reciprocate for a predetermined time, the first polishing that opposes each other Injecting a resin between the roll and the second polishing roll; Slowly moving the first polishing roll of the two polishing rolls opposite to each other for a continuous unit time to form a plate of non-uniform thickness; The first polishing roll is gradually moved downward at a speed equal to the upward movement speed to form a light guide plate having a non-uniform thickness that is symmetrical with each other, or the first polishing roll at a speed different from the upward movement speed. Slowly moving downward to form a light guide plate having a non-uniform thickness which is asymmetric with each other; And forming the first and second light guide plates by cutting the light guide plate having a non-uniform thickness by symmetrical or asymmetrical at a boundary portion, that is, a cutout portion.

As a result, the wedge type light guide plate of the liquid crystal display device can be mass-produced together with the plate type light guide plate through an extrusion process, thereby reducing manufacturing costs.

In addition, by only modifying the polishing roll unit portion of the existing extrusion process line will be able to save unnecessary investment costs following the design of the new extrusion process line.

Hereinafter, the configuration will be described in more detail with reference to the accompanying drawings.

6 is a view showing a polishing roll device according to a first embodiment of the present invention constituting a part of the extrusion process equipment.

Although not shown in detail in FIG. 6, the polishing roll apparatus according to the present invention includes at least two polishing rolls, for example, a first polishing roll 165 and continuously arranged at regular intervals by fixing or simultaneously fixing each axis separately. Positioning hydraulic device coupled to the second polishing roll 167 and one of the plurality of rolls, that is, the axis of the first polishing roll 165 to cause the shaft to be reciprocated vertically or horizontally for a predetermined time. (150, 151, 153). Here, the hydraulic devices 150, 151, 153 may include, for example, a hydraulic cylinder 151. At this time, the hydraulic cylinder 151 is fastened to the support 153 coupled to the shaft of the first polishing roll 165 to move up and down or reciprocate.

Further, in the present invention, the position movement hydraulic apparatus 150, 151, 153 is for controlling the position movement hydraulic apparatus 150, 151, 153 to start the vertical movement at a specific time interval after the operation of the equipment. An additional control device 150 may be additionally provided. The system of such a control device 150 will be performed by a separate programming process before the equipment operation.

FIG. 7 is a view illustrating in detail an operation process of the polishing roll apparatus of FIG. 6 for generating a wedge light guide plate, and FIG. 8 illustrates a mechanism of the operation process of FIG. 7.

7 and 8 together with FIG. 6, the polishing roll apparatus includes a plurality of polishing rolls, ie, a first polishing roll 165 and a second polishing roll 167, into which a resin is injected, the first The polishing roll 165 and the second polishing roll 167 are in the state of maintaining the first constant distance (FIG. 7 (a)), and the first polishing roll 165 and the second polishing roll are continuously made every unit time. One polishing roll 167, for example, in the present invention, the upper first polishing roll 165 gradually rises (FIG. 7 (b)), and gradually descends again (FIG. 7 (c)), wherein the first polishing The rise and fall times of the roll 165 become equal to each other.

When the polishing roll apparatus is raised every unit time as shown in FIG. 7, the light guide plate formed therein forms a step, that is, a stepped light guide plate, but the unit time is substantially changed continuously. As a result, a wedge-shaped light guide plate having a specific slope is formed.

To sum it up again, let us introduce a one-cycle process in which the polishing roll is moved upwards continuously over time and then returned to the initial position in a plate process extruded at a constant speed Pv. In this case, when the distance dh between the polishing rolls is increased, the height dh may be constantly increased based on the initial state, and a wedge light guide plate having asymmetrical heights may be manufactured.

If there is a time difference for each cycle, it is possible to secure a cutting portion or a cutting portion for cutting the continuously formed wedge light guide plate. In this case, if the rising time and the falling time of the first polishing roll are the same in one cycle, the cutting portion The wedge light guide plates on the left and right are symmetrical with each other, and when the rise time and the fall time of the first polishing roll are different from each other in one cycle, the wedge light guide plates on the left and right are asymmetric with respect to the cut portion.

8 is a schematic diagram showing the relationship between the extrusion speed Pv and the roll moving speed Rv. Here, dL is the unit length of the roll contact portion, dh is the increase width of the roll gap relative to the initial position.

For example, if the roll interval is maintained by dh for unit time dt, then the width of the final sample, ie the dh height of the product, will be dL. As can be seen in Figure 8 (b), there is a time dt to maintain a constant roll interval dh, and the extrusion disc during the unit time progresses by dL in the horizontal direction, has a step-shaped shape. Since the contact area dL is a small area close to the point,

On the back, the stepped cross-sectional area (dh x dL) is changed from area to line, and thus a wedge-shaped light guide plate having a different initial height and final height is formed as shown in FIG. 8 (c). Since roll speed Rv = dh / dt and extrusion speed Pv = dL / dt, light guide plate inclination dh / dL = Rv · dt / Pv · dt = Rv / Pv is determined.

Therefore, the inclination is determined according to the extrusion speed Pv and the roll moving speed Rv, and the wedge-shaped light guide plate having the desired inclination can be manufactured. When moving to the initial starting position after the polishing roll movement, the shape of the light guide plate is asymmetrically formed on the opposite side of the extrusion as shown in FIG. 8 (c), and finally, as shown in FIG. The light guide plate 170 is manufactured.

9 is a flowchart illustrating an extrusion process of FIG. 6.

As already described above, the overall extrusion process is largely performed in the order of resin melting and conveying ⇒ disc thickness control and primary cooling ⇒ extruded disc secondary cooling and conveying ⇒ forced extruded disk.

At this time, the wedge-type light guide plate manufacturing method of the liquid crystal display using the polishing roll device according to the present invention is a step of transporting the molten resin after melting the resin (S101), and determining the initial gap (gap) between at least two polishing rolls (S102) and changing the moving speed of one polishing roll of the first polishing roll and the second polishing roll of the site where the first resin is injected (S103), and changing the moving speed of the polishing roll. And determining the extrusion speed (S104), continuously moving the rolls according to time (S105), and maintaining the initial interval between the first polishing roll and the second polishing roll (S106). .

Here, the resin melting and conveying step (S101) is a previous step for applying the resin to the polishing roll apparatus, and corresponds to the step of injecting the resin. Such molten resin is injected between at least two polishing rolls constituting the polishing roll apparatus, that is, the first polishing roll and the second polishing roll.

At this time, as a step (S102) of determining the initial interval of the polishing roll apparatus, the first polishing roll and the second polishing roll before the molten resin is first injected, to maintain a constant gap, that is, the first of the apparatus Will be determined at design time.

When the initial interval of the polishing roll apparatus is determined, the movement speed of the polishing roll is changed (S103) and the extrusion speed determination (S104) corresponding thereto is performed internally. This, as described above, determines the slope of the wedge-shaped light guide plate produced through the extrusion process, which of course also is determined by the system or programming during the initial design of the device.

In this way, the step (S105) of continuously moving the roll is made in accordance with the moving speed of the polishing roll. At this time, if at least two polishing rolls are arranged vertically or horizontally with each other, it is possible to move one of the polishing rolls of the two polishing rolls, but to move the first polishing roll located at the outermost part in the design structure of the apparatus. Seems desirable.

Of course, furthermore, if the wedge-shaped light guide plate as in the present invention is a double-sided liquid crystal display device, that is, a class of liquid crystal display device capable of realizing images on both sides of one backlight device, In order to form a wedge-shaped light guide plate symmetrically with respect to the center, that is, to have a constant inclination on both the upper side and the lower side of the light guide plate, the first and second polishing rolls into which the initial resin is injected may be designed to move slowly. There will be.

Subsequently, a step S106 is performed in which the one of the two polishing rolls moved to maintain the initial interval again. In this way, one side, that is, the lower side, is flat, and the upper side is a wedge-shaped light guide plate which is symmetrical with each other with respect to the cut portion.

At this time, the step of cooling the extruded wedge-shaped light guide plate is made.

In addition, as a subsequent step of the polishing roll apparatus, the unit wedge-type light guide plate can be manufactured by cutting along the cut portion of the cooled wedge-shaped light guide plate.

Therefore, in the present invention, if the mechanism factors inside the system, that is, the initial interval between the polishing rolls, the moving speed, the extrusion speed, and the like are pre-decided when designing the device, that is, the method of manufacturing a light guide plate of the liquid crystal display device according to the present invention. Injecting a resin between the first polishing roll and the second polishing roll facing each other, and the first polishing roll of the two opposing polishing rolls are gradually moved upwards for a predetermined time to the non-uniform thickness Forming a plate, forming a light guide plate having a non-uniform thickness that is symmetrical with each other by gradually moving the first polishing roll downward for a predetermined time, and forming a non-uniform thickness by forming the symmetry. And cutting the light guide plate having a boundary portion to form a first light guide plate and a second light guide plate.

Of course, if the first polishing roll is moved downward at a different movement speed from an upward movement speed, a light guide plate having a non-uniform thickness that is asymmetric with each other may be formed. For example, if the inclination of the light guide plate formed on the right side is larger than the inclination of the light guide plate formed on the left side when viewed from the boundary, that is, the cutout portion, this means that the upward movement speed of the first polishing roll is formed when the light guide plate is formed on the right side. It indicates that the first polishing roll is faster than the downward movement speed.

On the other hand, the present invention further seems to be possible to simultaneously put the prism pattern on the flat lower side of the wedge-shaped light guide plate during the extrusion process.

10 is a view showing a polishing roll device according to a second embodiment of the present invention. Of course, the polishing roll apparatus according to the second embodiment of the present invention, as in the first embodiment, at least two polishing rolls continuously arranged at regular intervals by fixing or simultaneously fixing each axis separately, and the plurality of polishings. Positioning hydraulic device (260, 261, 263) coupled to the axis of one of the polishing rolls of the roll to move the axis up and down, or left and right reciprocating for a predetermined time, where the first resin is injected Among the two polishing rolls for determining the thickness, the first polishing roll 265 moving with a predetermined time and the patterned second polishing roll 267 fixed at regular intervals with the first polishing roll 265. Consists of.

As a result, the wedge-shaped light guide plate 270 can form a prism pattern on the lower surface thereof. However, in the present invention, the prism die pattern of the pattern-type second polishing roll 267 is not limited to the shape of the prism peak, but the lenticular, pyramidal shape, that is, polygonal shape such as triangular pyramid, etc. It may be formed.

Of course, in the second embodiment of the present invention, the position hydraulic pressure device 260, 261, 263 also uses the position hydraulic pressure device (260, 261, 263) to start the vertical movement at a specific time interval after the operation of the equipment. A separate control device 260 for controlling may be additionally provided. The system of such a control device will be performed by a separate programming process before the equipment is operated.

Except for this, other details will be replaced by the foregoing.

1 is a view showing a light guide plate manufacturing equipment through conventional injection molding

Figure 2 is a view showing a wedge-shaped and plate-shaped light guide plate formed through the subsequent process after the injection molding of Figure 1

3 is a view showing a mold manufacturing process of FIG.

Figure 4 is a schematic diagram of a conventional extrusion process equipment

FIG. 5 shows the stationary polishing roll of FIG. 4. FIG.

6 is a view showing a polishing roll device according to a first embodiment of the present invention constituting part of an extrusion process equipment;

7 is a view showing in detail the operation of the polishing roll device of Figure 6 for the production of wedge-shaped light guide plate

FIG. 8 illustrates a mechanism for the operation of FIG. 7.

9 is a flowchart illustrating an extrusion process of FIG. 6.

10 is a view showing a polishing roll device according to a second embodiment of the present invention.

Claims

Each axis is fixed or simultaneously fixed and coupled to the axis of at least two polishing rolls continuously arranged at regular intervals and one of the plurality of rolls, and the axis is reciprocated vertically or horizontally for a predetermined time. In a polishing roll machine of an extrusion process including a position movement hydraulic device for moving,

Injecting a resin between a first polishing roll and a second polishing roll facing each other;

Gradually moving a first polishing roll of the two polishing rolls opposite to each other for a continuous unit time to form a plate having a non-uniform thickness;

The first polishing roll is gradually moved downward at a speed equal to the upward movement speed to form a light guide plate having a non-uniform thickness that is symmetrical with each other, or the first polishing roll at a speed different from the upward movement speed. Slowly moving downward to form a light guide plate having a non-uniform thickness which is asymmetric with each other;

And forming a first and a second light guide plate by cutting the light guide plate having a non-uniform thickness by symmetrical or asymmetrical at a boundary portion, that is, a cutout portion.

The method of claim 1, wherein the second polishing roll may further form a pattern on an outer surface of the second polishing roll.

The method of claim 2, wherein the second polishing roll has at least one of a prism acid, a lenticular, and a pyramid shape on an outer surface of the second polishing roll.

The method of claim 2, wherein the cylindrical roll of the second polishing roll and a pattern formed at an outer portion of the second polishing roll may be integrally formed of the same material.