JPH10142595A - Liquid crystal display element and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain elements which obviate the occurrence of light leakage or defective articles and have high quality and high reliability at a high yield by providing parts to be affixed by one sealing material with light shielding films. SOLUTION: The inside surface of the one insulative transparent substrate 2 of the sealing agent 7 part by which two sheets of the insulative transparent substrates 1, 2 are affixed is printed with black ink for light shielding and is provided with the light shielding film 12. Both insulative substrates 1, 2 are affixed by the sealing material 7 via this light shielding film 12. If spacers having elasticity like resin beads or hard materials like silica are used for the spacers included in the sealing material 7, the spacers of a shape, such as spherical shape, to allow the easy penetration of the spacers into the light shielding film 12 are used. One set each of plural pieces of the sheets formed with plural pieces of liquid crystal panels are heated while these sheets are pressurized under a specified pressure and the sealing materials 7 are cured without superposing many sets of these sheets, by which the affixation of two sheets of the insulative transparent substrates 1, 2 at specified intervals is made possible. The inner sides of the insulative transparent substrates 1, 2 are thus provided with the light shielding films.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative liquid crystal display device and a method for producing the same. More specifically, the present invention relates to a liquid crystal display device that prevents light from leaking from a sealant portion to which an insulating transparent substrate is attached, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a liquid crystal display device, two insulating transparent substrates each provided with a transparent electrode are adhered to each other with a sealant so as to have a certain gap, and a liquid crystal material is injected into the gap. Polarizing plates are provided on both outer surfaces, and display is performed by controlling the transmission and blocking of light using the optical rotation caused by the twisting of liquid crystal molecules due to the application and non-application of voltage and the direction of the transmission axis of the polarizing plate. ing.

When the transmission axes of the polarizing plates on both sides are set to the same direction and twisted nematic liquid crystal is used as a liquid crystal material, light is blocked when no voltage is applied, and light is transmitted when a voltage is applied. A negative display in which a desired display is displayed in white or color on a black background. Also,
By making the transmission axes of the polarizing plates on both sides perpendicular to each other, a positive display opposite to that described above can be performed. Since the liquid crystal material is not filled in the portion of the sealant for attaching the two insulating transparent substrates described above, there is no optical rotation due to liquid crystal molecules. for that reason,
When a negative display is performed, light leaks from a portion of the sealant around the black background, resulting in poor display quality. To solve this problem, as shown in FIG. 4, a light-shielding film is provided by printing light-shielding ink on a portion corresponding to the upper part of the sealant on the surface side of the polarizing plate, thereby blocking light leakage. .

In FIG. 4, (a) is an explanatory plan view of the liquid crystal panel, and (b) is an enlarged sectional explanatory view of a sealant portion at an end thereof. In FIG. 4, reference numerals 1 and 2 denote insulating transparent substrates made of glass or the like, and reference numerals 3 and 4 denote transparent electrodes provided on the respective insulating transparent substrates 1 and 2, reference numerals 5 and 6 denote alignment films for controlling alignment of liquid crystal molecules. Reference numeral 7 denotes a sealant for adhering the two insulating transparent substrates 1 and 2 around the periphery thereof, reference numeral 8 denotes a liquid crystal layer, and reference numerals 9 and 10 denote polarizing plates provided on the outer surfaces of the insulating transparent substrates 1 and 2. A light-shielding ink is printed on the outer peripheral portion of the surface of the polarizing plate 10 on the front side of the liquid crystal panel, and a light-shielding film 12 is provided. Since the light-shielding film 12 is provided at a position apart from the sealant 7 by the thickness of both the insulating transparent substrate 2 and the polarizing plate 10, light can be completely shielded at the same width as the sealant depending on the viewing angle. However, the width is wider than the width of the sealant 7.

[0005] As shown in FIG. 5, the light-shielding film 12 may be provided on the surface of the insulating transparent substrate 2, that is, between the insulating transparent substrate 2 and the polarizing plate 10. It is the same as the example of FIG. 5, the same parts as those in FIG. 4 are denoted by the same reference numerals, and the description thereof will be omitted.

[0006]

When printing the light-shielding ink on the surface of the above-mentioned polarizing plate, the polarizing plate is attached by forming a plurality of liquid crystal cells at once on a large insulating transparent substrate. Since it is performed after the liquid crystal material is injected by dividing the cells into individual cells, the printing of the light-shielding ink can be performed only in a single process after the division into the cells, and the productivity is extremely low. Moreover, since the protective film must be attached after printing and drying the light-shielding ink, there is a problem that the number of steps is increased and the cost is greatly increased.

When printing light-shielding ink on the surface of an insulating transparent substrate before attaching a polarizing plate, the state of a sheet before dividing into cells (a plurality of cells are formed on a large insulating transparent substrate). Can be printed in the same state), so that a plurality of prints can be made at one time, and can be performed efficiently.
However, since the light-blocking ink is printed, the cells are divided into cells, and the liquid crystal material is injected, the polarizing plate is adhered. In some cases, scratches are made, handling is difficult in the manufacturing process, and scratches cannot be avoided, yield is reduced, and light leakage cannot be completely prevented.
Further, since a step is formed between the insulating transparent substrate and the polarizing plate, it is inevitable that a gap is formed and bubbles are formed. These bubbles expand as the ambient temperature increases,
When the liquid crystal panel is observed, the liquid crystal panel looks like a foreign substance, and the visibility is reduced. Further, due to the steps, the polarizing plate of the light shielding film portion is not completely adhered to the insulating transparent substrate, and the reliability of the polarizing plate is lowered due to the floating of the polarizing plate.

Further, in any of the above methods,
Unless the light-shielding film is provided wider than the width of the sealant, complete light-shielding cannot be obtained, and there is also a problem that the area of the effective display portion is reduced.

The present invention has been made in order to solve such a problem. While providing a light-shielding film for preventing light from leaking from a sealant portion, air bubbles may enter the polarizing plate side or the reliability of the polarizing plate may be reduced. Excellent display characteristics can be obtained without impairing the performance.
Moreover, it is an object of the present invention to provide a liquid crystal display element which is easy to handle in a manufacturing process and can be obtained with a high yield, and a method for manufacturing the same.

[0010]

According to the liquid crystal display device of the present invention, two insulating transparent substrates, each having a transparent electrode formed thereon, are adhered to each other with a sealing agent so as to have a constant gap. A liquid crystal display element in which a liquid crystal material is injected into a portion, wherein a light-shielding film is provided on at least one portion of the insulating transparent substrate which is adhered by the sealant.

The spacer mixed in the sealant is made of an elastic material, and a spacer made of a material having low elasticity is interposed in a fixed gap portion of the insulating transparent substrate without the sealant. Is preferred. By doing so, even when the thickness of the light-shielding film provided by screen printing varies or the surface has irregularities, when attaching two insulating transparent substrates, press firmly with a constant pressure. When the sealant is cured by heating while heating, the spacers are crushed and can be adhered at regular intervals.
At this time, it is preferable that a spacer having a low elasticity is interposed in a portion where no sealant is provided, so that the spacer in the sealant portion is not crushed too much and the interval is not too narrow. Further, even if the spacer in the sealant has a small elasticity, if the spacer is spherical, the spacer can sink into the light-shielding film and be adhered at a constant gap by firmly pressing the spacer with a constant pressure. Here, the elastic material refers to a material that can be deformed by an external force, such as resin beads, and the material having a low elasticity means a material that is not easily deformed by an external force, such as silica.

The method for producing the liquid crystal display element of the present invention comprises the steps of (a) 2
A transparent electrode is formed on each of the insulating transparent substrates,
(B) forming a light-shielding film on a portion of the insulating transparent substrate to which at least one sealant is attached; (c) forming an alignment film on each of the two insulating transparent substrates; Printing a sealant containing a spacer on one of the insulating transparent substrates and superimposing the two insulating transparent substrates,
(E) The sealant is cured by heating the two insulating transparent substrates while applying a predetermined pressure.

[0013]

Next, a liquid crystal display device of the present invention and a method for manufacturing the same will be described with reference to the drawings.

FIG. 1 is an explanatory sectional view of a liquid crystal panel of one embodiment of the liquid crystal display device of the present invention. In FIG. 1, the insulating transparent substrates 1 and 2 made of glass etc.
Transparent electrodes 3 and 4 made of O, tin oxide, indium oxide, and the like, and alignment films 5 and 6 made of polyimide and the like are provided, and are adhered to each other with a sealant 7 around a certain gap so as to face each other. A liquid crystal material is injected into the gap, a liquid crystal layer 8 is formed, and polarizing plates 9 and 10 are attached to both outer surfaces of the insulating transparent substrates 1 and 2. This structure is the same as that of a general liquid crystal panel. However, in the liquid crystal display device of the present invention, two insulating transparent substrates 1 and 2 are used.
One of the insulative transparent substrates 2 of the sealant 7 on which
A light-shielding black ink is printed on the inner surface (the surface in contact with the liquid crystal layer 8), and a light-shielding film 12 is provided.
2 is attached.

The light-shielding film 12 is provided with a thickness of about 2 μm by offset printing and drying the black ink. FIG. 2 is an exaggerated enlarged sectional view of the portion of the light-shielding film 12 and the sealant 7. As described above, it is conceivable that irregularities are formed on the surface and the thickness thereof also varies. On the other hand, the gap (gap) between the two insulating transparent substrates 1 and 2 of the liquid crystal panel affects the light transmittance characteristic, and this gap varies, causing display unevenness and deteriorating the display characteristic. Therefore, in the conventional liquid crystal panel, a columnar spacer made of hard glass or the like is mixed in the sealant 7,
Spacers made of elastic resin beads or the like are studded in places other than the sealant, and are adhered by the sealant 7 so that the distance between the insulating transparent substrates 1 and 2 is constant. The provision of a light-shielding film 12 or the like whose surface is uneven or whose thickness is not always constant has not been conventionally provided in the sealant 7 part because a constant gap cannot be obtained. However, as described above, when the light shielding film 12 is provided on the outer surface of the insulating transparent substrate 2 or the outer surface of the polarizing plate 6, the above-described problem occurs.

The inventor of the present invention has been able to provide the light-shielding film 12 with a small number of man-hours and has conducted intensive studies in order to obtain a high-quality liquid crystal display element without deteriorating display characteristics due to bubbles or the like. When a spacer included in the agent 7 is made of an elastic material such as resin beads containing divinylbenzene or the like as a main component, or a hard (low elasticity) material such as silica is used. Uses a spacer such as a sphere or the like that easily sinks into the light-shielding film 12 and heats the sheet on which a plurality of liquid crystal panels are formed while applying pressure at a constant pressure to each set without overlapping any number of sets. By curing 7, 2
It has been found that a plurality of insulating transparent substrates 1 and 2 can be adhered at regular intervals, and a light-shielding film can be provided inside the insulating transparent substrates 1 and 2 (on the liquid crystal layer side).

That is, as shown in FIG. 2, the ink for the light-shielding film 12 is printed on the portion to be adhered by the sealing agent 7, and even if the film thickness varies or irregularities occur, If the spacer 7a has elasticity, the two insulating transparent substrates 1 and 2 are pressurized by a constant pressure, so that when the spacer 7a hits a thick portion or a convex portion, the applied pressure is increased. As a result, the spacer 7a is crushed into an elliptical shape and adhered. Further, even when the spacer 7a has a small elasticity and is hard, the contact portion between the spacer 7a and the light shielding film 12 is in point contact with each other when the spacer 7a is pressurized by a constant pressure if it is spherical instead of cylindrical. The spacer 7a is sunk into the film 12 and is adhered while maintaining a constant gap. Therefore, the spacer 7a in the sealing agent 7 is made of an elastic material or a spherical material having a small elasticity, and is heated while being pressed at a constant pressure, so that the gap between the substrates 1 and 2 is reduced. It can be kept constant. When an elastic spacer is used as the spacer 7a in the sealing agent 7, it is necessary to include at least a part of the spacer having a low elasticity in the spacer to be scattered in the portion where the sealing agent is not provided. 2 is preferable in order to prevent the overall distance from becoming too narrow.

As a specific example of the type and size of the spacer actually used, the thickness of the light shielding film 12 is set to 2 μm.
In this case, as the spacer 7a in the sealant 7,
A resin bead having a diameter of about 3.8 to 4 μm mixed with 1 wt% by weight with respect to the sealant 7 is used, and a spacer between the two substrates 1 and 2 other than 7 parts of the sealant has a diameter of 5.2.
A mixture of resin beads having a size of about 5.3 μm and silica beads was sprayed at a rate of about 30 to 40 beads / mm ² . Under these conditions, 320 liquid crystal panels were produced. As a result, a constant gap was obtained between the substrates 1 and 2, and no display unevenness occurred. In the conventional specification, the light shielding film is not provided, and the spacer in the sealant 7 is 5.5.
It is a cylindrical glass spacer having a length of 20 to 60 μm and being mixed at a ratio of 3 wt% with respect to the sealant. The spacer other than the sealant has a width of 5.2 to 5.3 μm.
m of resin beads and spraying was performed at about 60 beads / mm ² .

FIG. 3 is a flowchart showing the steps of manufacturing the liquid crystal panel shown in FIG. First, an insulating transparent substrate such as a large glass
Wash each one to form a transparent electrode film such as ITO,
Patterning is performed to form a transparent electrode pattern for each cell (S1-2). Next, a black ink is offset-printed on a portion of one of the insulating transparent substrates to which the sealing agent of each cell is adhered, and dried to form a light-shielding film (S
3-4). Next, an alignment film made of polyimide or the like is applied by roll coating or the like and dried, and an alignment process such as a rubbing process is performed (S5 to S6).

After that, the periphery of each cell of one of the insulating transparent substrates is formed in a ring shape except for the liquid crystal material injection port.
A sealant containing resin beads is provided by screen printing or the like. On the other insulating transparent substrate, silver dot printing for transferring the electrode terminals to the one insulating transparent substrate is performed by applying a silver paste or the like (S7-8).

Thereafter, a spacer in which the above-mentioned resin beads and silica beads are mixed is sprayed on one of the insulating transparent substrates at the above-mentioned ratio, and the two insulating transparent substrates are overlapped so that the respective transparent electrodes face each other. For example, 1 × 10 ^{5 to} 3 × 10 ⁵ P
90 to 12 while applying a pressure of about a to about 1 to 3 minutes.
The sealant is temporarily cured by heating to about 0 ° C. Further, dozens of sets are stacked and placed in an oven furnace, and heated at about 120 to 180 ° C. for about 120 to 180 minutes to be completely cured (press / curing S9 to S10). Then, the insulating transparent substrate is cut and divided into cells (S11), a liquid crystal material is injected, and polarizing plates are attached to both outer surfaces (S12 to S13), whereby the liquid crystal panel shown in FIG. 1 is formed. Is done.

In the case where a light-shielding film is provided on the surface of the above-described conventional polarizing plate, a step of printing and drying ink for the light-shielding film after S13 in the manufacturing process shown in FIG. Can be put in. Therefore, care must be taken so as not to damage the light-shielding film in the subsequent assembling process with a backlight, a circuit board, and the like, and the operation cannot be performed by an automatic machine. When a light-shielding film is provided between the insulating transparent substrate and the polarizing plate, a step of printing and drying ink for the light-shielding film is inserted between S10 and S11 in the manufacturing process shown in FIG. Will be. Therefore, in the case of a conventional liquid crystal display element having a light shielding film on the outside,
Although the manufacturing process after attaching the two insulating transparent substrates is different from the one without the light-shielding film, according to the present invention, the flow in the latter half is the same, and even if the model is changed, the work is performed. Can be leveled.

[0023]

According to the present invention, a liquid crystal display device of high quality and high reliability which is free from air bubbles on the display surface, leakage of light due to scratches or chipping of the light-shielding film, and occurrence of defective products can be achieved. Obtained in yield.

Further, since the surface on which the sealant and the light-shielding film are provided is the same, there is no parallax, and the size of the light-shielding film can be determined in consideration of the printing deviation, thereby facilitating the design.

Further, according to the manufacturing method of the present invention, since the spacer contained in the sealing agent has elasticity and is adhered while applying a constant pressure, a light-shielding film is provided inside the insulating transparent substrate. Thus, even if the surface is uneven, the distance between the two substrates can be kept constant. In addition, since the light-shielding film is provided inside the insulating transparent substrate, it is hardly exposed to the outside even during the manufacturing process, there is no risk of being damaged in the subsequent manufacturing process, and no defective products are generated and handling is performed. , And workability and productivity are greatly improved.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view of one embodiment of a liquid crystal display device of the present invention.

FIG. 2 is an exaggerated enlarged explanatory view of a light-shielding film portion of FIG. 1;

FIG. 3 is a flowchart showing a manufacturing process of the liquid crystal display device of FIG.

FIG. 4 is an explanatory diagram of an example in which a light-shielding film is provided in a conventional sealant portion.

FIG. 5 is an explanatory view of another example in which a light-shielding film is provided on a conventional sealant portion.

[Explanation of symbols]

 1, 2 Insulating transparent substrate 3, 4 Transparent electrode 7 Sealant 8 Liquid crystal layer 12 Light shielding film

Claims (3)

[Claims] 1. A liquid crystal display device in which two insulating transparent substrates each having a transparent electrode formed thereon are adhered to each other with a sealant so as to have a fixed gap, and a liquid crystal material is injected into the fixed gap. A liquid crystal display device comprising a light-shielding film provided on at least one portion of the insulating transparent substrate adhered by the sealant. 2. A spacer mixed in the sealant is made of an elastic material, and a spacer made of a material with low elasticity is interposed in a fixed gap portion of the insulating transparent substrate without the sealant. The liquid crystal display device according to claim 1, comprising: 3. A transparent electrode is formed on each of two insulating transparent substrates, and (b) a light shielding film is formed on at least one of the insulating transparent substrates to which a sealant is attached. (C) an alignment film is formed on each of the two insulating transparent substrates, and (d) a sealing agent containing a spacer is printed on one of the insulating transparent substrates to overlap the two insulating transparent substrates. (E) a method of manufacturing a liquid crystal display element, wherein the sealant is cured by heating the two insulating transparent substrates while applying a predetermined pressure.