JP7354040B2 - Manufacturing method of liquid crystal display panel - Google Patents

Description

The present invention relates to a method for manufacturing a liquid crystal display panel.

The following manufacturing methods are known as methods for manufacturing liquid crystal display panels. First, a pixel electrode is formed on one of two mother substrates so that a plurality of image display areas are formed, an alignment film is formed on the pixel electrode, and each image display area is formed on the other mother substrate. After forming a common electrode corresponding to the common electrode and forming an alignment film on the common electrode, spacers are sprinkled on the alignment film of one mother substrate to ensure a gap for injecting liquid crystal. Furthermore, after providing a sealing material to surround each image display area, both motherboards are aligned and bonded together, and then both motherboards are divided into individual image display areas, resulting in multiple hollow interiors. Fabricate a liquid crystal display panel. Next, liquid crystal is injected through a liquid crystal injection port formed in a part of the sealing material of each liquid crystal display panel, and the liquid crystal injection port is sealed to complete a liquid crystal display panel with liquid crystal sealed inside.

FIG. 2 is (a) a top view and (b) a sectional view taken along the line AA, showing a state in which two motherboards are bonded together. In the state shown in FIG. 2, ITO electrodes 7 for applying voltage to the liquid crystal are formed on the opposing surfaces of the mother substrate 2 configured as a lower substrate and the mother substrate 3 configured as an upper substrate, and An alignment film 4 for aligning the liquid crystal is formed on the ITO electrode 7, and the mother substrate 2 and the mother substrate 3 are bonded to a plurality of peripheral sealing materials 5 provided so as to surround each image display area. and are fixed to each other through a predetermined gap (GAP) 6. A plurality of spacers 1 are arranged in a predetermined gap (GAP) 6 in order to maintain the gap (GAP) 6. The spacers 1 are scattered over the entire surface of the alignment film 4 of either the mother substrate 2 or the mother substrate 3 before the mother substrates 2 and 3 are bonded together. As a method for dispersing the spacers 1, dry dispersion (dry dispersion) is generally used (see, for example, Patent Document 1).

The motherboard 2 and the motherboard 3 are bonded together via the peripheral sealant 5 with the spacers 1 sprinkled thereon, and after the peripheral sealant 5 is cured, the motherboard 2 and the motherboard 3 are separated along the dividing line 8. After dividing the panel into a single liquid crystal display panel with a hollow interior, liquid crystal is injected into the gap (GAP) 6 through the liquid crystal injection port 9.

Japanese Patent Application Publication No. 5-127170

In the prior art, spacers are sprayed onto one substrate by dry spraying, but it is technically difficult to stably spray spacers at a constant spray amount. Although it depends on the size of the liquid crystal display panel, for example, in a case where the in-plane distribution is required to be sprayed at 500 pcs/mm ² , it may be sprayed at 1000 pcs/mm ² . This is because one of the substrates is placed in the scattering device, spacers are scattered from above, and only the amount that falls onto the substrate constitutes the scattering density, making it extremely difficult to control the scattering density. In a liquid crystal display panel assembled with a high scattering density, the spacers will appear as small white bright spots on the image. Particularly when the amount of in-plane dispersion is large, these bright spots become conspicuous, causing optical problems such as a decrease in contrast. If the amount of spacers sprinkled on the substrate is small, it is possible to increase the amount uniformly by repeating the spraying again, but if the amount of spacers sprinkled on the substrate is large. In this case, it is difficult to uniformly remove the spacers that have already been sprayed from the substrate, and therefore the amount of spacers that have been sprayed cannot be uniformly reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a liquid crystal display panel that allows spacers scattered on a substrate to be uniformly removed.

A method for manufacturing a liquid crystal display panel, the method comprising: spraying spacers on a substrate by dry spraying; and dropping a liquid onto the substrate while rotating the substrate on which the spacers have been sprayed, and causing the substrate to rotate. The method of manufacturing a liquid crystal display panel includes a removing step of removing a part of the spacer from a defined area on the substrate by the accompanying movement of the liquid.

The liquid crystal display panel manufacturing method may include dropping the liquid near the rotation center of the substrate in the removing step.

The method for manufacturing a liquid crystal display panel may be such that, in the removing step, the liquid is dropped in a region where the spacer is dispersed at a relatively high density.

According to the present invention, even if more than a specified number of spacers are scattered on a substrate, the excess spacers can be uniformly removed from the substrate.

Flowchart showing an embodiment of a method for manufacturing a liquid crystal display panel according to the present invention (a) Top view and (b) AA cross-sectional view showing two motherboards bonded together

FIG. 1 is a flowchart showing an embodiment of a method for manufacturing a liquid crystal display panel according to the present invention. One embodiment of the present invention will be described below based on FIG. Note that the description will be made with reference to FIG. 2 as necessary.

In one embodiment of the present invention, first, a plurality of spacers 1 are sprayed by dry spraying onto the alignment film 4 formed on one mother substrate 3, which is the upper substrate. Furthermore, a sealing material 5 made of ultraviolet curing resin or the like is arranged on the other mother substrate 2, which is the lower substrate, so as to surround each image display area.

Since dry dispersion of the spacer 1 is a common technique, detailed explanation will be omitted here. After the spacers 1 are spread on the mother board 3, the density of the spacers 1 spread on the mother board 3 is measured. The dispersion density of the spacers 1 can be measured using a well-known particle counter or the like. As a result of this measurement, if the scattering density on the motherboard 3 is higher than the specified value, the excess spacers 1 are removed leaving only the required specified amount. As a method, first, the mother substrate 3 on which the spacers 1 are scattered in excess is set in a spinner device (substrate rotation device). Next, the mother substrate 3 set in the spinner device is rotated at a constant rotation speed, and a highly volatile liquid such as IPA is dropped onto the rotating mother substrate 3. When IPA is dropped onto the rotating motherboard 3, the IPA moves to the outer periphery of the motherboard 3 along with the excess spacers 1 due to centrifugal force, and the spacers 1 are scattered within a specified area on the motherboard 3. The dispersion density decreases.

The direction in which the mother board 3 is rotated is, for example, clockwise or counterclockwise around an axis perpendicular to the surface of the mother board 3 on which the spacers 1 are dispersed. The position where the liquid is dropped is preferably an area where the density of spacers 1 is relatively high (for example, the highest area) or near the center of rotation of the motherboard 3. The number of times the liquid is dropped is appropriately selected from one or more times. Although it is desirable that the spacer 1 is not mixed in advance with the liquid to be dropped, it may be mixed to some extent.

The amount of spacer 1 to be removed can be adjusted in any way depending on the rotational speed of the spinner device, the amount of liquid dropped, the position of dropping, and the like. Moreover, although IPA was used here as the liquid for removing the spacer 1 because it has high volatility and good drying properties, other liquids such as ethanol can also be used.

The results of one experiment conducted by the applicant of the present application show that by dropping 200 ml of IPA onto an 8-inch substrate on which spacers have been pre-dispersed at a dispersion density of 1000 pcs/mm ² while rotating at 3000 rpm, the dispersion density reaches 600 pcs/mm ² . I was able to lower it.

After reducing the spreading density of spacer 1, the spreading density is measured again. If the spreading density meets the specified value, proceed to the substrate bonding process, and if the spreading density exceeds the specified value, Spacer 1 is repeatedly removed until the dispersion density meets the specified value.

On the other hand, if the spraying density of the spacers 1 is lower than the specified value, the spacers 1 are sprayed again to increase the spraying density. After increasing the spreading density of spacer 1, measure the spreading density again. If the spreading density meets the specified value, proceed to the board bonding process. If the spreading density falls below the specified value, the spreading density Spraying of Spacer 1 is repeated until it meets the specified value.

In this embodiment, the spacers 1 are scattered on the wafer-shaped mother substrate 3, but for example, the spacers 1 may be scattered on individual substrates that are pre-divided into image display areas.

The present invention is not limited to the embodiments described above, and may take various other forms.

1 Spacer 2 Mother board (lower board)
3 Mother board (upper board)
4 Alignment film 5 Peripheral sealing material 6 Gap (GAP)
7 ITO electrode 8 Division line 9 Liquid crystal injection port

Claims (2)

A method for manufacturing a liquid crystal display panel, the method comprising:
a scattering process of dry scattering spacers on the substrate;
a removing step of dropping a liquid onto the substrate while rotating the substrate on which the spacers have been spread, and removing part of the spacers from a specified area on the substrate by movement of the liquid as the substrate rotates; , has
A method for manufacturing a liquid crystal display panel, characterized in that, in the removing step, the liquid is dropped in an area where the spacer is distributed at the highest density . a measuring step of measuring the scattering density of the spacers sprinkled on the substrate, and if the result of the measurement is that the scattering density is higher than a specified value, the removing step is performed, and the scattering density is increased. If the density is lower than a specified value, the dispersing step is performed, and the measuring step, the removing step, and the spreading step are repeated until the spreading density conforms to the specified value. The method for manufacturing the liquid crystal display panel described above.

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