JP2006126420A - Liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display element capable of producing a liquid crystal display element having excellent display quality while using an ultraviolet curable resin as a sealing material.
SOLUTION: 11 and 12 are glass substrates, and a color filter 13 is formed on the glass substrate 11. In the color filter 13, a plurality of pixels of a plurality of colors such as R, G, and B are arranged in the display area, and a black matrix 14 is provided at the boundary and the periphery of each pixel, so that color mixing and Prevents light leakage. The other glass substrate 11 is an array substrate on which TFTs and wirings 15 are formed. Recently, there is a type in which the color filter 13 is formed on the array substrate. An alignment film is formed on the glass substrates 11 and 12 so that the liquid crystal 16 is sandwiched between the glass substrates 11 and 12, and the gap between the outer edge serving as the peripheral edge of the black matrix 14 and the peripheral sealing material 17 is formed. The liquid crystal 16 is covered with the sealing material 17.
[Selection] Figure 1

Description

The present invention relates to a liquid crystal display element used in office automation equipment such as personal computers and monitors, handy terminal equipment, and portable information communication equipment.

In a conventional liquid crystal display element, a vacuum injection method is often used as a method for enclosing liquid crystal in a cell. FIG. 5 shows a liquid crystal injection process by this vacuum injection method. This will be briefly described. First, an alignment film is formed on the surface, and two glass substrates 11 and 12 are prepared by rubbing the alignment film as necessary. An adhesive (sealant) is applied thereon, and a spacer 18 is dispersed on one of the alignment films, and then the two glass substrates 11 and 12 are bonded to form an empty cell 20. Next, the pool 21 storing the empty cells 20 and the liquid crystal 16 is installed in a vacuum chamber 22 so that the vacuum chamber 22 has a certain degree of vacuum. Next, after immersing one inlet 23 of the empty cell 20 in the pool 21, the liquid crystal 16 is sucked into the empty cell 20 by capillary action by returning the pressure in the vacuum chamber 22 to atmospheric pressure. When the liquid crystal spreads over the entire surface of the empty cell 20, a sealing agent is applied to the injection port 23 to seal the cell. In general, a thermosetting resin or an ultraviolet curable resin is used as an adhesive (sealant) for the empty cell 20, and a curing process is performed after application. The above is the manufacturing process of the liquid crystal display element using the vacuum injection method. However, the manufacturing process of the liquid crystal display element has a drawback that it takes a long time to inject the liquid crystal 16. In particular, the larger the size of the empty cell 20, the longer it takes to make the pressure in the vacuum chamber 22 and the pressure in the empty cell 20 the same. Further, it takes about 24 hours to fill the entire surface of the empty cell 20 with the liquid crystal 16 and to reach a predetermined cell gap. Even when empty cells are batch-processed and injected, a plurality of devices are required, which results in poor workability.

In recent years, in order to increase the response speed of liquid crystal display elements, studies have been made to narrow the cell gap (gap (interval) between the two glass substrates 11 and 12) from the conventional 6 to 7 μm to 3 to 4 μm. The narrower the cell gap, the longer the time required to keep the pressure in the empty cell 20 constant and the time required to pull up the liquid crystal by capillary action. For this reason, the present situation is that it requires several times the work time of the prior art. Therefore, a dripping method shown in FIG. 6 has been proposed as a method for eliminating such a long liquid crystal injection operation.

This dripping method comprises the following steps. First, an alignment film is formed, and two glass substrates 11 and 12 that are rubbed as necessary are prepared, and a sealing material 17 for bonding is screen printed on one glass substrate 12. A pattern is formed with a dispenser or the like, and an appropriate amount of liquid crystal 16 is further dropped. Further, a spacer 18 that does not move is provided on one of the substrates 11. When using a photo spacer, the spacer 18 is not necessary. Here, an ultraviolet curable resin is used as the sealing material 17. Next, both the glass substrates 11 and 12 are arrange | positioned in the vacuum tank 22, and when the inside of a tank reaches the optimal degree of vacuum, both the glass substrates 11 and 12 will be bonded together. And the sealing material 17 is hardened and the area | region used as the display area of a liquid crystal display element in a cell gap (gap between the glass substrates 11 and 12 bonded together) is completely sealed. Finally, the glass substrates 11 and 12 are cut while leaving portions of the glass substrates 11 and 12 to be liquid crystal display elements. In FIG. 6, only one element region (a portion to be a liquid crystal display element) is shown, but a plurality of element regions (portions to be a liquid crystal display element) are formed on a large-area substrate, and each glass substrate is cut into individual regions. It is also possible to obtain a plurality of elements in a lump by dividing the element region (the portion to be a liquid crystal display element). Such a dripping method does not require a long time to arrange the liquid crystal in the cell, so that the liquid crystal display element can be completed in a short time.

Further, even if the size of the liquid crystal display element to be manufactured is large or the cell gap is narrow, there is an advantage that the time required to complete the liquid crystal display element does not change at all. In addition, batch processing such as the vacuum injection method can be performed continuously in-line, and a plurality of elements can be manufactured in a lump and manufacturing cost can be reduced. In addition, it is preferable to use an ultraviolet curable resin as the sealing material 17 rather than a thermosetting resin. This is because in the case of a thermosetting resin, the resin is once softened (melted) during the curing process, and the softened (melted) resin is mixed into the liquid crystal to deteriorate the characteristics of the liquid crystal.

In Patent Document 1, which is a prior example, the sealant is formed by being separated from the edge of the black matrix of the color filter at a predetermined interval. The aim is to prevent the contamination of the liquid crystal due to. However, a narrow frame which is also a feature of the liquid crystal display element cannot be obtained by keeping a predetermined interval, and the commercial value is greatly questioned in modern notebook PCs, monitors, TVs and the like. In addition, glass substrates handled in the manufacture of liquid crystal display elements reduce costs by chamfering more, but the necessity of such a predetermined interval is fatal in manufacturing a liquid crystal panel. It becomes a problem.
JP 2003-75796 A

As described above, in the present invention, unlike the patent document 1, the narrow frame design, which is the original feature of the liquid crystal display element, is obtained by not taking a predetermined distance between the outer edge of the black matrix of the color filter and the sealing material. Obtainable.

By the way, in any of the above production methods (vacuum injection method, dropping method), an ultraviolet curable resin is used as a sealing material (in particular, an ultraviolet curable resin is preferably used in the dropping method). By the way, in the ultraviolet irradiation process to the cell for curing the ultraviolet curable resin, if the ultraviolet ray is insufficient, the cell is adversely affected. Generally, if the UV irradiation amount of UV curable resin is insufficient, the resin will not have enough reaction energy and unreacted components will remain. In addition, in the case of the dripping method, the liquid crystal material exists next to the sealing material in the cell when irradiated with ultraviolet rays, so the influence of the unreacted components of the seal on the liquid crystal material is often considered. The unreacted component of the seal becomes insufficient for the liquid crystal material, and a change occurs in the specific resistance and Tni of the liquid crystal material, so that normal display characteristics cannot be obtained. When a liquid crystal display element containing such impurities is subjected to a reliability test, many of them have significantly reduced current values and optical characteristics. Also, in the display quality, the area containing impurities causes unevenness. This unevenness may become brighter or darker than a stable region, and may appear more prominent when a voltage is applied or heated.

In recent years, liquid crystal display elements have begun to be installed in notebook PCs, monitors, and TVs, but thin and light points are pushed to the front in designs that make use of the features of liquid crystal display elements. The frame part outside the display area of the liquid crystal display element is further narrowed to provide functionality and a beautiful design. In this way, narrowing the frame of the liquid crystal display element greatly increases the commercial value as well as making the display quality beautiful.

As described above, it is necessary to obtain a beautiful design by reducing the frame width of the liquid crystal display element while suppressing the influence of the uncured component of the sealing material on the liquid crystal material. On the other hand, the demand for improvement in display quality from users is becoming stronger, which requires stable display quality from the center of the panel to the entire area around the seal.

The present invention has been made in view of the above-described problems, and a liquid crystal display element with excellent display quality is manufactured by narrowing the frame of the liquid crystal display element while using an ultraviolet curable resin as a sealing material. An object of the present invention is to provide a liquid crystal display element capable of achieving the above.

In order to achieve the above object, the liquid crystal display element of the present invention is formed by applying an ultraviolet curable sealing material on the alignment film of one of two transparent substrates having an alignment film on the surface, A spacer for forming a cell gap is formed on one of the two transparent substrates, a liquid crystal material is dropped on the alignment film of one of the two transparent substrates, and the two transparent substrates In the liquid crystal display element in which the substrates are bonded via the seal so that the alignment films face each other, the outer edge of the black matrix of the color filter and the region of the sealing material are formed without gaps.

In the liquid crystal display element of the present invention, the liquid crystal display element is configured so as to give sufficient ultraviolet light to the sealing material in the curing process of the sealing material with the ultraviolet curable resin, and there is no shortage of ultraviolet irradiation to the sealing material. Thus, the liquid crystal panel having a narrow frame can be formed while maintaining an adverse effect on the display area.

Here, before the step of bonding the two transparent substrates, a liquid crystal material is dropped on the alignment film of either one of the two transparent substrates in advance, thereby liquid crystal in the gap between the two transparent substrates. When the liquid crystal display element is completed in a mode in which the material is disposed, the orientation of the liquid crystal material at the time of sealing is maintained in a uniform and stable state, and the gap between the two transparent substrates in the sealing material curing process. Since the liquid crystal material inside does not change the specific resistance or Tni point of the liquid crystal material, a liquid crystal display element with excellent display quality can be manufactured.

Next, in the liquid crystal display element of the present invention, an ultraviolet curable sealant is applied on the alignment film of one of the two transparent substrates having an alignment film on the surface, and the two transparent substrates A spacer for forming a cell gap is provided on one of the substrates, and a liquid crystal material is dropped on the alignment film of one of the two transparent substrates, and the two transparent substrates are aligned with each other. In the liquid crystal display element to which the film is bonded through the seal so as to face each other, the outer edge of the black matrix of the color filter is formed so as to overlap the sealing material, and the overlapping degree is 1 mm or less, and ultraviolet rays from the periphery The seal is cured by irradiation.

With this configuration, as described above, an unreacted component of the ultraviolet curable resin does not remain, and a liquid crystal display element is configured using a sealing material, and a liquid crystal material is filled in a gap between two transparent substrates. When the liquid crystal display element is completed by the above method, the alignment state of the liquid crystal material at the time of sealing becomes a desired preferable alignment state, and a liquid crystal display element having excellent display quality can be manufactured, and at the same time, the area other than the display is narrowed It becomes possible.

In the present invention, the liquid crystal display element according to claim 4 and claim 5 is characterized in that the shape of the four corners of the outer edge of the black matrix of the color filter is R or C.

With this configuration, in the process of bonding the two transparent substrates and curing the seal with ultraviolet light, uncured seal can be prevented in advance at the corner that is most likely to occur. In particular, at the time of forming the sealing material, it is difficult to make the corner portion at a right angle, which corresponds to these.

As described above, according to the liquid crystal display element of the present invention, the sealing material made of the ultraviolet curable resin can prevent the uncured state of the seal caused by the shortage of ultraviolet rays, and the liquid crystal material and orientation A stable liquid crystal display element performance can be obtained. If there is an abnormality in these, the user can confirm unevenness with a product called a display. Since the threshold value changes locally for unevenness, the screen becomes brighter or darker depending on the screen to be projected. For this reason, the uniformity of the screen is impaired, and the reproduction of correct display may be lost. However, when the present invention is used, such a quality problem does not occur.

As an effect of using the present invention, there is a narrow frame design. Due to the structural advantage that the liquid crystal display element is light and thin, the user is required to have a compact design in the design of the display as a finished product. Therefore, it is essential to make the area outside the display region of the liquid crystal display element as narrow as possible. By using the present invention, a narrow frame is possible.

Further, in the present invention, it is used for manufacturing a liquid crystal display element by a dropping method, and the dropping method is generally spreading, but even in a large liquid crystal display element, the injection time of liquid crystal is remarkably fast, and the productivity is excellent. An in-line production line is also possible with cells. In addition, the amount of liquid crystal material used can be efficiently reduced, and the number of workers can be reduced compared to the conventional vacuum injection method.

Furthermore, as described above, a stable display quality and an excellent design can be obtained by using the present invention.

As is apparent from the above description, the requirements of the present invention are extremely effective configurations on the liquid crystal display element, and it is also clear that there are no restrictions on the design of the liquid crystal display element.

Hereinafter, representative embodiments of the present invention will be described.

Regarding Example 1, FIG. 1 is a cross-sectional view of a liquid crystal display device according to the present invention. In FIG. 1, reference numerals 11 and 12 denote glass substrates, and a color filter 13 is formed on the glass substrate 11. In the color filter 13, a plurality of pixels of a plurality of colors such as R, G, and B are arranged in the display area, and a black matrix 14 is provided at the boundary and the periphery of each pixel, so that color mixing and Prevents light leakage. The other glass substrate 11 is an array substrate on which TFTs and wirings 15 are formed. Recently, there is a type in which the color filter 13 is formed on the array substrate. An alignment film is formed on the glass substrates 11 and 12, and the liquid crystal 16 is sandwiched between the glass substrates 11 and 12, and the gap between the outer edge serving as the peripheral edge of the black matrix 14 and the peripheral sealing material 17. The liquid crystal 16 is covered with the sealing material 17.

In the present invention, as shown in FIG. 1 which is a cross-sectional view of a liquid crystal display element, the sealing material 17 and the black matrix 14 of the color filter 13 are formed so as to coincide with each other, and there is no gap. Further, the liquid crystal 16 is adjacent to the sealing material 17 so as to be adjacent. If the sealing material 17 is not cured, as can be seen from FIG. 1, the liquid crystal 16 melts the uncured components of the sealing material 17 and the liquid crystal 16 is mixed with impurities, resulting in unevenness when displayed. The physical properties of the liquid crystal change.

The sealing material 17 used in the present invention is made of an ultraviolet curable resin, and an ultraviolet irradiation process is required to cure the sealing material 17. If the amount of ultraviolet irradiation is small, an abnormality such as unevenness occurs around the sealing material 17 of the liquid crystal panel.

FIG. 2 is a manufacturing flowchart of the present embodiment, and this flowchart shows a flow of a general dripping method. That is, this embodiment is a manufacturing process of a liquid crystal display element using a dropping method.

The manufacturing process of the liquid crystal display element will be described below based on these drawings.

First, an alignment film is formed on the surface, and two glass substrates 11 and 12 are prepared by rubbing the alignment film, and a sealing material 17 made of an ultraviolet curable resin is provided on one substrate (glass substrate 12). May be applied, and spacers may be dispersed and fixed onto the alignment film of the other substrate (glass substrate 11). Recently, without these spacers, in advance either on the substrate, forming a projection made of a resin using a photolithography process, a method of forming an alignment film thereon. Further, the liquid crystal 16 is dropped on the substrate on which the sealing material 17 is applied in an amount that forms a gap. Then, both glass substrates 11 and 12 are placed in a vacuum chamber, and when the inside of the chamber reaches an optimum degree of vacuum, both glass substrates 11 and 12 are bonded together to form a liquid crystal cell.

Next, an ultraviolet irradiation method will be described. As shown in FIG. 3, the sealing material 17 is cured by irradiating ultraviolet rays 18 from either one of the glass substrates 11 and 12 toward the sealing material 17. Here, the irradiated ultraviolet rays may be scattered rather than parallel rays. The type of lamp is determined by the absorption wavelength and energy amount required for the sealing material 17, the lamp shape may be general, and an optical lens may be used to control the light beam region. Since ultraviolet rays are scattered to some extent in this way, light energy can be given to the sealing material 17 even if there is no gap between the sealing material 17 and the black matrix 14 due to the wraparound of the irradiated ultraviolet rays. On the other hand, in the conventional technique, a shading mask is used to prevent the influence of ultraviolet rays on the alignment film and the transistor. However, in recent years, the destruction of the transistor and the decomposition of the liquid crystal material have not been a problem.

Here, a sealing material 17 using an ultraviolet curable resin will be described with reference to FIG. In the embodiment of the present invention, the sealing material 17 uses an ultraviolet curable resin for ODF manufactured by Kyoritsu Chemical. In addition, a liquid crystal material for VA manufactured by Merck is used for the liquid crystal. It is necessary to select a seal and a liquid crystal that are as difficult as possible even if they come into contact with each other. As the evaluation method, a liquid crystal panel can be produced and the boundary between the seal and the liquid crystal can be observed, or the liquid crystal and the seal can be crossed on a glass for comparative observation with a microscope.

As can be seen from FIG. 1, the edges of the sealing material 17 and the black matrix 14 are in contact with each other. Recently, liquid crystal display elements can be manufactured with high accuracy as shown in the figure. First, the line width of the seal 17 will be described. In the case of UV curable resins recently used, the volume shrinkage is determined from the physical properties of the composition depending on the material, and the volume change rate before and after UV irradiation depends on the variation in the mixing ratio of the composition. It can be said that there is no change. On the other hand, a dispenser is mainly used as an apparatus for applying a sealing material to a glass substrate, and a sensor for detecting an application amount of a seal and an application cross section with a magnifying glass is mounted on the tip of the dispenser. With such a technique, the application amount is monitored, the seal application amount is managed, and application variations are suppressed. Similarly, with respect to the application position accuracy, a magnifying glass and a position confirmation sensor are similarly mounted on the tip of the dispenser, and a liquid crystal display element is manufactured with high accuracy. It is also necessary to control the temperature of the sealing material 17 to be used in the workplace and to check the viscosity in advance. As described above, it is possible to manufacture the variation amount of the seal and the coating amount without variation depending on the volumetric shrinkage rate and the coating apparatus.

In order to take advantage of the characteristics of the liquid crystal display element in the present invention, the present invention has been devised to eliminate the seal and the black matrix so as to form a narrow frame and to commercialize the liquid crystal display with a beautiful design. On the other hand, as in Japanese Patent Application Laid-Open No. 2003-75796, in order for the sealing material to be formed at a predetermined distance from the edge of the black matrix of the color filter, ultraviolet rays are not shielded by the black matrix. The purpose of this invention is to prevent the contamination of the liquid crystal by a sealant that is not completely cured. However, in the present invention, a narrow frame that is also a characteristic of the liquid crystal display element is obtained without taking a predetermined interval. is there. In the seal and liquid crystal material handled in the present invention, there is no such contamination problem on the panel.

In the second embodiment, the case of actual production based on the manufacturing method of the first embodiment will be described. In the first embodiment, a liquid crystal material and a sealing material having good compatibility are used, and a manufacturing apparatus for producing a liquid crystal display element needs to have a high accuracy. On the other hand, since the frame is a narrow frame, as described in the first embodiment, it is optimal that there is no gap between the sealing material 17 and the black matrix 14. However, even if it is designed and mass-produced so that the gap between the sealing material and the black matrix is zero, it is necessary to consider the worst case due to problems in materials and equipment. Actually, the seal width and size are controlled by the seal material and process control. As for management of the seal width, the variation R value is about 0.05 to 0.4 mm for 1 mm. When the gap between the sealing material 17 and the black matrix 14 is maintained at zero, the 0.4 mm seal 17 and the black matrix 14 overlap in the worst case. However, even if there is such an overlap, the seal 17 can sufficiently absorb ultraviolet rays.

Next, ultraviolet irradiation will be described. First, as shown in FIG. 3, the ultraviolet ray 19 is irradiated from the outside of one of the glass substrates 11 and 12 toward the sealing material 17 to cure the sealing material 17. Here, the irradiated ultraviolet rays are not parallel rays but scattered rays. In this way, the ultraviolet rays are scattered to some extent, so that the irradiated ultraviolet rays wrap around. The wraparound by incident light from the side depends on the size of the cell gap, but if the value is 4 to 9 μm, the light beam spreads optically from 0.05 to 0.1 mm. In addition, if there is no light shielding structure, light wraps around, and a surface plate is generally provided on the opposite side of the incident light. Irradiate the element. If the surface of the surface plate is provided with reflection performance, light is reflected more. Actually, when the cured state of the seal is confirmed using the liquid crystal display element, the cured state is almost completely good up to 0.3 mm, and no defect is seen. Further, when a surface plate was provided on the opposite side, seal hardening data up to 1 mm was obtained. Therefore, when mass production is performed with the gap between the sealing material and the black matrix set to zero, the seal can be sufficiently cured even when the worst case overlap of 0.4 mm as described above occurs.

For Example 3, FIG. 4 is a pattern diagram of a corner portion of a black matrix of a color filter used in a liquid crystal display element according to another embodiment.

First, FIG. 4A represents the case where the corner shape of the black matrix is rounded, and FIG. 4B is a chamfer with the corners cut off obliquely, indicating C. FIG. The technical term “R or C” described here is as described in the publication “Mechanical Design Handbook” by Maruzen. When the seal material 17 is applied and formed by a dispenser or printing, the corner portion of the seal line is rounded, and when the seal material 17 is at a right angle like the black matrix of the conventional color filter, the corner material may be covered with the seal material 17. Occurring and irradiating with ultraviolet rays in this state, the seal material 17 at the corner becomes uncured. In the present invention, in order to solve this problem, the corner portion of the black matrix 14 is devised as shown in FIG.

Originally, the black matrix is for the purpose of shielding the backlight, but the light leakage of the backlight does not occur at the corner due to the housing design.

It is sectional drawing of the liquid crystal display element by the 1st Embodiment of this invention. It is a flowchart (flowchart of a general dripping method) which shows the manufacturing process of the liquid crystal display element by the 1st Embodiment of this invention. It is sectional drawing which shows the hardening process of the sealing material in the manufacturing process of the liquid crystal display element by the 2nd Embodiment of this invention. It is a pattern diagram of the black matrix of the color filter used for the liquid crystal display element by the 3rd Embodiment of this invention. It is the side view which showed the injection | pouring process of the liquid-crystal material into the cell by the vacuum injection method of a prior art example. It is the side view which showed the process of bonding the board | substrate after liquid crystal material dripping in the manufacturing process of the liquid crystal display element by the dripping method of a prior art example.

Explanation of symbols

11: glass substrate 12: glass substrate 13: color filter 14: black matrix 15: wiring 16: liquid crystal 17: seal 18: spacer 19: ultraviolet ray 20: empty cell 21: pool 22: vacuum chamber 23: injection port

Claims (5)

An ultraviolet curable sealant is applied on the alignment film of one of the two transparent substrates having an alignment film on the surface, and a cell gap is formed on one of the two transparent substrates. A liquid crystal material is dropped onto the alignment film of one of the two transparent substrates, and the two transparent substrates are placed through the seal so that the alignment films face each other. In the liquid crystal display element to be bonded, the outer edge of the black matrix of the color filter and the region of the sealing material are formed without a gap. An ultraviolet curable sealant is applied on the alignment film of one of the two transparent substrates having an alignment film on the surface, and a cell gap is formed on one of the two transparent substrates. A liquid crystal material is dropped onto the alignment film of one of the two transparent substrates, and the two transparent substrates are placed through the seal so that the alignment films face each other. A liquid crystal display element to be bonded, wherein the sealing material overlaps with an outer edge of a black matrix of a color filter. 3. The formation of the color filter according to claim 2, wherein the outer edge of the black matrix of the color filter and the sealing material overlap with each other so that the overlap is 1 mm or less and the seal is cured by ultraviolet irradiation from the periphery. The liquid crystal display element as described. 4. A liquid crystal display element, wherein the shape of the four corners of the outer edge of the black matrix of the color filter is R or C. The liquid crystal display element according to claim 1 or 2, wherein the shape of the four corners of the outer edge of the black matrix of the color filter is R or C.