JPH0255333A - Display device - Google Patents

Abstract

PURPOSE:To uniformly maintain the thickness of a liquid crystal layer and to prevent the generation of unequal displays by providing a flow passage regulating bar having a rhombic shape near an aperture for injection to prevent the infiltration of a sealing material and to regulate the flow passage for the liquid crystal material, thereby uniformizing the inflow rate. CONSTITUTION:The liquid crystal introduced from an injection hole 4 into the cell for the display panel having a liquid crystal packed part 6 between a pair of transparent resin layers 1 and 2 which are provided with transparent electrodes and are subjected to an orientation treatment arrives at the flow passage regulating bar 4 having the rhombic shape, by which the inflow rate thereof is lowered and the liquid crystal is branched in two ways at the time of injecting the liquid crystal material into the above-mentioned cell by a reduced pressure injection method. The liquid crystal is packed into the cell nearly parallel with the injection side end face and at the uniform speed in this way. The injection hole 4 is thereafter sealed by using an epoxy resin of a cold setting type at the point of the time when the liquid crystal packed part 6 is kept slightly in the reduced pressure state to complete the liquid crystal panel. The liquid sealing material infilters the injection hole 4 in this sealing stage but the progression thereof is hindered by the regulating bar 5 and, therefore, the sealing material is prevented from arriving at the display part 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a display device that utilizes electro-optical changes in a liquid display material, and particularly to a display device that can realize a homogeneous display.

2. Description of the Related Art Conventionally, liquid crystal panels, electrophoretic panels, magnetic fluid panels, and the like are known as display devices using liquid display materials.

In recent years, display devices have been required not only to be thin, lightweight, and have low power consumption, but also to have larger display capacity, homogeneity, and excellent display quality.

In response to these demands, liquid crystals have attracted particular attention as the most excellent display material, and are currently the mainstream of flat panel display devices.

In a liquid crystal display device, a liquid crystal is sandwiched between a pair of transparent substrates having transparent electrodes, a voltage is applied between the pair of opposing electrodes, and the resulting optical change is extracted using a pair of polarizing plates. , is the display device to be used. In order to display a lot of information, a lot of pixels are required. For this reason, the mainstream display format is a matrix type that operates by high time division driving.

In order to obtain a display with high contrast and good visibility using high time-division driving, the electro-optic characteristics of the liquid crystal panel, that is, the voltage-luminance characteristics (dark value characteristics), must be steep, and the brightness level when the OFF voltage is applied must be high. It is important that it is sufficiently small.

In order to meet these demands, we created a panel structure in which the twist angle of the liquid crystal molecules was further expanded from the conventional 90 degrees, thereby significantly improving the dark value characteristics.At the same time, we created a two-layer structure for the liquid crystal layer to reduce the amount of light. By using a configuration that compensates for the reduction in optical rotational dispersion, measures are taken to reduce the coloring of the display and to reduce the brightness level when the display is off.

However, in display panels with these configurations, the twist angle of the liquid crystal molecules is further expanded than the conventional 90-degree twist, and the amount of decorative substance added increases accordingly, resulting in a smaller twist pinch. Due to these factors, it is more difficult to align the liquid crystal than in the past, and display unevenness is therefore likely to occur. Furthermore, in a configuration in which the twist angle of the liquid crystal molecules is expanded, birefringence of light is utilized, so even a slight difference in the thickness of the liquid crystal layer appears as color unevenness due to interference, that is, display unevenness. For this reason,
Control of the liquid crystal layer thickness is more strict than in the past, and the tolerance for variation must be kept within 5%.

Therefore, the panel structure must be able to solve these problems.

Next, the configuration of a conventional display device will be explained using FIG. 2.

Conventionally, in general, a liquid crystal display panel is manufactured using a sealant 3 provided with an injection opening 4 at one end of a liquid crystal material filling part 6.
A cell is formed by fixing two glass substrates 1.2 having transparent electrodes, and then liquid crystal material is injected through the opening 4 at the end of the substrate, and the injection part 4 is sealed to complete the process. .

Here, as the sealant 3, a thermosetting resin or a photocuring resin that is cured by ultraviolet irradiation is used. In addition, as a spacer to maintain the thickness of the liquid crystal layer,
Glass fiber or resin beads are used,
While it is mixed into the sealing resin, it is also used dispersed in the liquid crystal filling area in large panels.

Conventionally, the liquid crystal injection part of a liquid crystal panel with such a structure has a structure in which a part of the seal part forming the liquid crystal filling part is simply removed and the part is used as the injection hole 4 (for example, Publication No. 62-206525, Japanese Unexamined Patent Publication No. 62-2319
Publication No. 39, etc.).

Problems to be Solved by the Invention The conventional structure of the liquid crystal injection part in such a liquid crystal panel has the following fatal problem regarding display quality.

That is, the first problem is a problem caused by the flow of the liquid crystal when injecting the liquid crystal material.

Usually, liquid crystal is injected by a vacuum decompression method. In this method, the injection hole of the liquid crystal cell is first immersed in the liquid crystal material in a vacuum container under reduced pressure, and then the inside of the vacuum container is leaked and the inside of the container is returned to atmospheric pressure.

At this time, since the inside of the liquid crystal cell is still under reduced pressure, liquid crystal is injected due to the difference in pressure between the inside and outside of the cell.

Here, it is necessary to reduce the pressure inside the liquid crystal cell to about 10-" Torr in order to prevent air bubbles from remaining in the liquid crystal filling area. Therefore, this pressure difference causes the liquid crystal to be injected near the injection hole. The inflow speed is fast, and on the injection hole side of the display surface, the inflow speed is different between the vicinity of the injection hole and the area away from the injection hole, which causes disturbance in liquid crystal alignment, resulting in display unevenness.

The second problem is the thickness of the liquid crystal layer and the infiltration of the sealant.

In a liquid crystal panel configured with dispersed spacers as described above, in order to maintain a uniform liquid crystal layer thickness, when sealing the injection part after liquid crystal injection, it is necessary to make sure that the liquid crystal filled part is still slightly under pressure. It is desirable to seal it. However, in a conventional injection part structure in which a part of the seal part is simply missing, the uncured sealant may infiltrate the liquid crystal filled part and reach the display part. Furthermore, if the opening of the injection hole is large, the thickness of the liquid crystal layer near the injection part becomes thinner, resulting in display unevenness.

On the other hand, this phenomenon can be avoided if the liquid crystal filled part is sealed after it returns to atmospheric pressure, but in this case, it is difficult to maintain a uniform liquid crystal layer thickness, resulting in uneven display.

In this way, the liquid crystal panel of the conventional structure has a fatal drawback of not being able to provide a display with good visibility.Means for Solving the ProblemThe present invention aims to solve the above problem by providing a liquid display material. After fixing two transparent substrates having transparent electrodes through a sealant having an injection opening provided at one end of the filling part, and injecting a liquid display material through the opening provided at the end of the substrate, An edge injection type liquid display device in which the opening is sealed with a sealant, which prevents the sealant from entering the vicinity of the injection opening, corrects the flow rate of the liquid display material, and This configuration includes a diamond-shaped flow path regulating bar for regulating the flow path.

Effect of the present invention With the above-described configuration, when liquid crystal is injected by the reduced pressure injection method, the flow rate of the liquid crystal that has passed through the injection hole 4 is moderated by the rhombic flow path regulating bar 5, and
The flow is divided to the left and right, and is injected at a diagonal speed while maintaining a state parallel to the end face on the injection side. Furthermore, even in the case of an injection hole with a large opening, the defect in the seal frame is compensated for by the flow path regulating bar 5, so that the thickness of the liquid crystal layer near the injection hole can be kept constant. Therefore, the alignment state of the liquid crystal is extremely uniform and stable, and the thickness of the liquid crystal layer is kept constant.

As a result, it becomes possible to display a uniform display with good visibility without display unevenness.

Furthermore, the rhomboid-shaped flow path regulating bar 5 prevents the sealant from penetrating into the display section, which occurs when the liquid crystal filling section 6 is sealed in a reduced pressure state.

EXAMPLE Hereinafter, an example of the liquid crystal display device of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view schematically showing the structure of a liquid crystal display device of the present invention.

A seal frame 3 is placed on the electrode side surface of one substrate 1 of a pair of transparent substrates 1.2 that are provided with transparent electrodes and subjected to alignment treatment.
is formed by screen printing method. Here, the seal frame 3 is formed by integrating a liquid crystal filling part 6, an injection opening 4 provided at one end thereof, and a diamond-shaped flow path regulating bar 5. As this sealing material, a thermosetting resin or a photocuring resin that is crosslinked and polymerized by ultraviolet irradiation is used, and in these resins, glass fiber resin beads or the like are added as spacers to maintain the desired liquid crystal layer thickness. Use by mixing.

After that, the spacers for keeping the desired liquid crystal layer thickness constant are uniformly dispersed on the substrate 1 on which the sealant 3 is formed, and then the other substrate 2 is bonded and the sealant is cured. It will stick.

A liquid crystal material is injected into the thus manufactured display panel cell by a reduced pressure injection method. At this time, injection hole 4
The liquid crystal introduced from the flow path reaches the diamond-shaped flow path regulating bar 4, where its inflow speed is weakened and the liquid crystal is branched into two directions. Therefore, it is filled almost parallel to the injection side end face and at a -like speed.

Thereafter, while the liquid crystal filling part 6 was maintained in a slightly reduced pressure state, the injection hole 4 was sealed using a room temperature curing epoxy resin to complete a liquid crystal panel.

In addition to these, photocurable resins are also suitable as the sealant used here.

In this sealing step, the liquid sealant infiltrates into the injection hole, but does not reach the display section 6 because its progress is blocked by the flow path regulating bar 5 . In addition, since the flow path regulating bar 5 is provided near the injection hole 4, the thickness of the liquid crystal layer in this area is kept constant.The liquid crystal panel filled with liquid crystal in this way is then
A liquid crystal display device is completed by disposing it between a pair of polarizing plates.

As a result of applying a driving voltage between each electrode of the thus completed display device and evaluating its display characteristics, a high-quality display with no display unevenness, homogeneity, and good visibility was obtained.

As described in detail, according to the display device of the present invention, when the liquid display material is injected, it is possible to make the inflow velocity uniform over the entire surface and to maintain the layer thickness uniform over the filling area. becomes possible.

Therefore, it is possible to display a high-quality display that is homogeneous and has good visibility without unevenness in density or color.

[Brief explanation of the drawing]

FIG. 1 is a plan view schematically showing the structure of an embodiment of the display device of the present invention, and FIG. 2 is a plan view showing the structure of a conventional display device. 1.2...Transparent substrate, 3...Sealant, 4...Injection hole, 5...Flow path regulation bar, 6...・Liquid material filling section. Name of agent: Patent attorney Shigetaka Awano 1 person\4 \4 injection tube

Claims (1)

[Claims] Two transparent substrates having transparent electrodes are fixed to each other through a sealant made of a thermosetting resin or a photocuring resin that is cured by ultraviolet irradiation, with an injection opening provided at one end of the liquid display material filling part, An edge injection type liquid display device in which a liquid display material is injected through the opening provided at the end of the substrate and then the opening is sealed with a sealant, which prevents the sealant from entering. and a diamond-shaped flow path regulating bar for regulating the flow path of the liquid display material and making its inflow speed uniform, the display device comprising: a diamond-shaped flow path regulating bar provided near the injection opening.