JP2000028980A - Production of liquid crystal display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a liquid crystal display panel which makes the gap between substrates of the panel more uniform than conventional. SOLUTION: In this method for producing a liquid crystal display panel, a substrate 12 is arranged on a fixed surface of a stage 19, to which a plastic plate 22 having plural suction holes 15 is attached, and the sucking force from plural suction holes 15 is used to temporarily fix the substrate 12 to this fixed surface when two substrates 11 and 12 for liquid crystal display will be stuck to each other with a certain gap kept between them.

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 liquid crystal display panel.

[0002]

2. Description of the Related Art Recently, personal computers, word processors, car navigation systems,
2. Description of the Related Art For display devices such as monitors, those using liquid crystal displays as screen displays are often used. The modes of the TN type alignment and the STN type alignment are most often used as modes of the liquid crystal panel used for these liquid crystal displays.

A liquid crystal display panel used in the above-mentioned TN type or STN type alignment mode has a certain gap (2 to 5 microns) between two substrates, aligns the liquid crystal, and optically aligns the liquid crystal. Is used in a mode in which optical rotation and birefringence are used.

Recently, the screen size of the liquid crystal display panel has been increasing. Particularly, as a liquid crystal display panel for a monitor, a diagonal line is 13 to 15 inches or more, and the number of pixels is 102 pixels wide.
A panel having a size of 4 × 768 or more and a pixel density of 10 to 30 pixels per square mm is being manufactured.

The narrow viewing angle, which has been one of the conventional disadvantages of the liquid crystal, is due to the use of a film having a wide viewing angle and an IP.
S (in-plane switching) mode technology is being overcome, so-called wide viewing angle (widening viewing angle)
Is at the stage of being planned. However, in order to achieve a more uniform wide viewing angle, it is necessary to maintain the variation in the gap between the two substrates into which the liquid crystal is inserted at ± 0.1 μm or less over the display area.

In general, the gap between the substrates into which the liquid crystal is inserted is approximately 2
Microns to 5 microns are typically used; for example, if a 5 micron gap is to be kept, approximately 100 beads per square millimeter in particle size are dispersed to maintain this gap.

Here, such a conventional manufacturing method will be described with reference to the drawings.

FIG. 4 is a schematic cross-sectional view showing a conventional method of bonding two substrates 31 and 32 while holding fixed gaps D31 and D32.

As shown in FIG. 4, one of the two substrates 31 and 32 is placed on a stage 39.

The stage 39 is provided with several to several tens of suction holes 36 for sucking the substrate 32. The suction holes 36 are connected to the vacuum pump 30 and are evacuated. One of the substrates 32 is fixed on the stage 39 by suction. In the figure, the direction of the arrow denoted by reference numeral 38 indicates the flow of air when the vacuum pump 30 operates. Reference numeral 40 denotes a valve.

In this way, the sealing resin 34 is applied on the substrate 32 fixed by suction on the stage 39, and the other substrate 31 is overlapped with high accuracy, so that the two substrates 31, 32 can be bonded together. Can be attached. 45
Indicates a liquid crystal panel bonded in this manner.

According to such a conventional manufacturing method, the gap D between the two substrates 31 and 32 is defined by beads having a particle diameter substantially equal to D, but when the gap D is about several microns, it is adsorbed. A gap D31 near the hole 36 (reference numeral 35 in the figure)
) And a gap D32 near the non-sucking hole (indicated by reference numeral 37 in the figure) has a difference of 0.1 μm or more.

In the case of a liquid crystal display panel for a monitor, a screen size of about 13 to 15 inches in a diagonal line is being used in many cases. However, in order to prevent display unevenness due to the above-mentioned gap, the above-mentioned screen size is required. Therefore, it is necessary to take a measure to keep the variation of the gap constant (0.1 μm or less) over such a large area.

As a method considered for that purpose, in order to reduce the variation in the gap, 200 pieces / m 2
In this method, beads of a number of m to about 300 / mm2 were dispersed.

[0015]

However, such a conventional method has a problem that the cost is increased because a large amount of beads are used. Furthermore, since the number of beads used is large, the beads are not uniformly dispersed but tend to be aggregated, resulting in display unevenness due to uneven gaps and reduction in transmittance due to bead particles.

As described above, the present inventor changed the viewpoint from the viewpoint of the prior art, and the above-mentioned unevenness of the gap has been generated in the situation where only the consideration of the countermeasure by enclosing the beads has been focused on. I thought about investigating the root cause.

The inventor of the present application has clarified that the technical or mechanical reason that such gap unevenness occurs is as follows.

That is, the two substrates 31 and 32 shown in FIG.
Is mainly made of glass plate, the thickness of which is 0.7m
m or 1.1 mm is often used.
Further, when a substrate having a thickness of 13 to 15 or more as described above is vacuum-adsorbed by several to several tens of suction holes, the following phenomenon occurs. For example, even if 5 micron bead particles are sealed in the gap between the substrates, the suction force generated by vacuuming causes the substrate gap D3 in the vicinity of the suction hole.
1 becomes relatively large. On the other hand, since it is difficult to receive the attraction force in a place away from the attraction point, the gap D
32 becomes relatively small, resulting in a difference in the gap between the substrates.

This will be further described with reference to FIGS. 5 (a) and 5 (b).

FIG. 5A is a schematic diagram showing the state of the gap between the substrate and the substrate when no suction is performed, and the gap is kept substantially uniform. FIG. 5B is a schematic diagram showing a state of a gap between the substrate and the substrate when the suction is performed. Here, reference numeral 57 denotes beads sealed in the gap between the substrates.

As shown in FIG. 5B, the reason why the gap in the vicinity of the suction hole 36 is relatively larger than the gap in a place away from the suction hole is that the suction hole 36 in the substrate 32 on the suction side. This is because the contact portion bends toward the suction hole 36 by the force of suction. When a part of the substrate 32 bends as shown in the figure,
Peripheral beads gather near the adsorption hole 36. Once the beads 57 are aggregated in this way, even if the adsorption is released, the beads gathered in the vicinity of the adsorption holes 36 remain aggregated at that position. A place arises. In such a place where the beads are densely present, the gap is relatively large as compared with a place where the beads are coarse.

The difference caused by the location of the gap between the substrates of the liquid crystal display panel, which is generated as described above, has a drawback of causing display unevenness in the liquid crystal display panel as described above.
And, even if the number of beads to be enclosed is increased to solve the drawback, it does not solve the fundamental problem, but rather has the problem that another problem as described above occurs. There has been no effective measure for making the gap between the substrates of the display panel even more uniform than before.

The inventor of the present application has conceived of solving the above-described problem by focusing on the method of adsorbing the substrate based on the above-described root cause without increasing the amount of beads to be enclosed.

The present invention provides a method of manufacturing a liquid crystal display panel in which the gaps between substrates of the liquid crystal display panel can be made more uniform as compared with the related art, in consideration of such problems in the above-described conventional method of manufacturing a liquid crystal display panel. The purpose is to do.

[0025]

Means for Solving the Problems The first invention (claim 1)
When two liquid crystal display substrates are bonded to each other while maintaining a predetermined gap, one or both of the two substrates are connected to a plate-like member having a plurality of suction holes. A method for manufacturing a liquid crystal display panel, wherein the substrate is temporarily fixed to the fixing surface by using a suction force from the plurality of suction holes, disposed on a fixing surface of the fixing stage to which the fixing stage is attached.

According to a second aspect of the present invention (corresponding to the second aspect of the present invention), the plate-like member having the suction holes is a sheet-like member, and the density of the suction holes is limited to a pixel of the liquid crystal display panel. This is a method for manufacturing a liquid crystal display panel substantially corresponding to the density.

According to a third aspect of the present invention (corresponding to the third aspect of the present invention), in a step after the bonding step of bonding the two substrates, temporary fixing of the bonded substrates is performed. Therefore, there is provided a method of manufacturing a liquid crystal display panel using the fixing stage.

A fourth invention (corresponding to the invention of claim 4) is a method for manufacturing a liquid crystal display panel, wherein the sheet-like member is a metal sheet or a plastic sheet.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a liquid crystal display panel according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of a liquid crystal display panel and a device for manufacturing the liquid crystal display panel in the method of manufacturing a liquid crystal display panel according to the present embodiment.

The configuration of the liquid crystal panel 25 of the present embodiment is as follows.
The configuration is the same as that of the conventional liquid crystal panel 45 (see FIG. 4) except that the density of beads to be enclosed can be reduced.

As shown in FIG. 1, a groove 101 having a large number of slit holes 23 formed on the bottom surface is formed in the center of the upper surface of the stage 19. Groove depth is 0.1 ~ 0.3
mm. Regarding the size of the slit hole 23, the short side is about 0.1 to 0.3 mm, and the long side is 20 to 30 cm. Also, inside the stage 19, below the groove 101,
A space 102 serving as a passage for air sucked by the exhaust pump 30 is provided, and is connected to an end of the exhaust pipe 103. A plate-like member 22 having a large number of suction holes 15 is attached to the groove 101. The plate member 22 is made of stainless steel, aluminum, or plastic. The size of the plate-like member 22 is about 0.1 mm to 1.0 mm in thickness and about 20 cm × 3.
It is a thin plate with a size of about 0 cm. The diameter of the suction holes 15 is 0.1 to 0.3 mm, and the number of the suction holes 15 formed in the plate member 22 is about 30 when the number of pixels of the liquid crystal panel 25 is 30 per square mm. It is ideal and good to set the number to about one. However, even if the suction holes 15 are formed at a density of about one per square mm, a sufficiently uniform gap is maintained for the suction force.

Using the stage 19 having such a structure,
As shown in FIG. 1, the process of fixing the substrate 12 on the stage 19 by vacuum suction and bonding the substrate 11 was performed for a sample number n = 50, and the variation of the gap was measured.

FIG. 2 is a diagram showing the measurement results. That is,
In FIG. 2, the vertical axis indicates the measurement dimension of the gap, and the horizontal axis indicates the measurement location.

As shown in FIG. 2, the gap between the substrates near the suction holes 15 and the gap between the substrates near the non-suction holes 16 are both 4.8 μm ± 0.12 μm. Is almost nonexistent.

As described above, the gap D11 between the substrates 17 corresponding to the suction holes 15 and the gap D12 between the substrates 18 corresponding to the non-suction holes 16 are fixed by vacuum suction of one of the substrates 12. It was found that there was almost no difference in the step of bonding the other substrate 11 later.

On the other hand, for comparison, an experiment similar to the above was conducted using a stage 39 having a conventional configuration (see FIG. 4). The experimental results are shown in FIG. In FIG. 3, the vertical axis indicates the measurement dimension of the gap, and the horizontal axis indicates the measurement location.

As shown in FIG. 3, the suction holes 36 (see FIG. 4)
The gap D31 between the nearby substrates is 4.9 μm ± 0.12 μm.
m, and the gap D32 between the substrates near the non-suction holes is 4.
8 μm ± 0.12 μm. Therefore, it can be seen that the gap between the substrates has a large difference of about 0.1 μm on average.

The plate-like member 2 used in the present embodiment
The two suction holes 15 can be manufactured by a photolithography process or the like.

Further, the plate member 22 is made of aluminum, titanium,
Other metal plates such as tantalum, and plastics such as silicone resin, embi resin, epoxy resin and acrylic can be used.

Incidentally, the main steps after the above-mentioned laminating step of manufacturing the liquid crystal display panel generally include the following steps.

That is, a bonding step, a liquid crystal injection step, an injection hole sealing step, a polarizing plate bonding step, and an LSI mounting step.

As described above, in the steps after the bonding step as well, it is necessary to accurately position and fix the liquid crystal display panel as in the case of the above step. for that reason,
Also in these steps, the gap between the substrates can be made uniform by fixing the panel on the stage 19 having the large number of suction holes 15 described above.

According to the present embodiment described above, the panel bonding step can be performed on a stage having a large number of suction holes, so that the suction force is uniformly applied to the entire panel and no difference is generated in the substrate gap. A uniform display panel can be manufactured. Further, since the present invention can be carried out also in the steps after bonding, a uniform display panel having no difference in the substrate gap can be manufactured. In addition, even if the amount of encapsulated beads is smaller than before,
This has the effect that the gap between the substrates can be made uniform.

[0045]

As apparent from the above description, the present invention has the advantage that the gap between the substrates of the liquid crystal display panel can be made more uniform than before.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a liquid crystal display panel and a device for manufacturing the liquid crystal display panel, for explaining a method of manufacturing a liquid crystal display panel of the present embodiment.

FIG. 2 is a diagram showing experimental results of the present embodiment.

FIG. 3 shows a result of a comparative experiment of the present embodiment.

FIG. 4 is a partial cross-sectional view of a liquid crystal display panel and a device for manufacturing the liquid crystal display panel for describing a conventional method of manufacturing a liquid crystal display panel.

FIG. 5A is a schematic diagram for explaining a mechanism in which a difference in a gap between substrates is generated by a conventional method of manufacturing a liquid crystal display panel, and is a diagram in a state where suction is not performed; FIG. 9 is a schematic diagram for explaining a mechanism in which a difference in a gap between substrates is generated according to a method of manufacturing a display panel, and a diagram illustrating a state in which suction is performed.

[Explanation of symbols]

 11, 12 Substrate 13 Gap D 14, 34 Seal resin 15 Many suction holes 18 Gap corresponding to non-suction holes 17 Gap corresponding to suction holes 19, 39 Stage 22 Plate member 23 Slit hole 25, 45 Liquid crystal panel 28 , 38 Air flow direction by evacuation 30 Exhaust pump 31, 32 Substrate 101 Groove 102 Space 103 Exhaust pipe

Claims (4)

[Claims] When bonding two substrates for liquid crystal display while maintaining a predetermined gap, one or both of the two substrates are attached to a plate-like member having a plurality of suction holes. A method of manufacturing a liquid crystal display panel, wherein the substrate is temporarily fixed to the fixing surface by using a suction force from the plurality of suction holes. 2. The plate-like member having the suction holes is a sheet-like member, and the density of the suction holes substantially corresponds to the pixel density of the liquid crystal display panel.
The manufacturing method of the liquid crystal display panel described in the above. 3. The fixing stage for temporarily fixing the bonded substrates in a step after the bonding step of bonding the two substrates. The manufacturing method of the liquid crystal display panel described in the above. 4. The sheet-shaped member is a metal sheet or a plastic sheet.
The manufacturing method of the liquid crystal display panel described in the above.