JP2003066461A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a spacer of a liquid crystal display device wherein static electricity generated in the manufacturing stage is suppressed and display quality associated with cell thickness uniformization is improved. SOLUTION: Electrodes 3 and 4, columnar spacers 5 and alignment layers are successively formed on a pair of plastic substrates 1 and 2. The spacer 5 are formed in block shapes on at least a sealing part in such a manner that the block shape has >=8,700 μm<2> total surface area per 1 mm<2> substrate surface, is parallel to a pixel and the bottom face of the block shape has <=10 μm shorter side and the longer side of the bottom face is shorter than the side of one pixel on the side parallel and opposed to the bottom face. The pair of plastic substrates are stuck to each other with a sealing material at the sealing part to manufacture the liquid crystal display element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device using a plastic substrate that prevents the influence of static electricity generated during manufacturing.

[0002]

2. Description of the Related Art In recent years, a liquid crystal display device is mounted on a multimedia device as a display, and a lightweight plastic plastic liquid crystal display device capable of simultaneously achieving high display quality is manufactured so that the device can be easily carried and used. Has been done.

In such a plastic liquid crystal display device, a plastic bead or a photosensitive columnar spacer formed on a transparent electrode is used as a spacer for equalizing the cell thickness of the facing liquid crystal display device substrate. .

FIG. 8 is a perspective view showing the structure of a conventional liquid crystal display device having columnar spacers. FIG. 9 is a cross-sectional view showing the structure of a conventional liquid crystal display device having a plastic bead spacer formed therein. FIG. 10 is a cross-sectional view showing the structure of a conventional liquid crystal display device having columnar spacers. As shown in FIG. 9, in order to control the cell thickness, the plastic beads are uniformly sprayed on one side of the substrate in the spraying process of bonding and sandwiched between the plastic substrates. At this time, the substrate supporting the spacers may be distorted and uneven cell thickness may occur. In order to solve this, it has been proposed to control the cell thickness by uniformly disposing a photosensitive columnar spacer in a non-pixel portion on one substrate as shown in FIG. The photosensitive columnar spacers are formed and arranged by a photolithography process after patterning one liquid crystal drive electrode (ITO), applying a photosensitive resin on the substrate with a spin coater or the like.

The photosensitive columnar spacer is provided on one substrate side in order to maintain the thickness of the liquid crystal layer, that is, the cell thickness.
Generally, it is formed in a columnar shape such as a columnar shape or a prismatic shape having a height of about 6 μm and a diameter of about 10 μm, which is approximately half the distance between pixels. This is because if it is larger than this, the alignment of the liquid crystal around the spacer is disturbed and a problem called a stripe domain occurs. After forming the columnar spacer, an alignment film is applied and a rubbing (RUB) process is performed. After that, a sealing material is printed on the substrate on the opposite side of the substrate on which the columnar spacers are formed, the upper and lower substrates are bonded, and liquid crystal is injected to complete the liquid crystal display device.

Further, Japanese Patent Laid-Open No. 6-337427 discloses that a liquid crystal display device is obtained by forming protrusions as columnar spacers on a plastic substrate.

Further, Japanese Patent Application Laid-Open No. 1-134336 discloses a liquid crystal display element in which photosensitive columnar spacers are formed on both of a pair of substrates with electrodes and facing spacers are in contact with each other. ing.

[0008]

In the liquid crystal display device provided with the columnar spacers as described above, the plastic substrate is different from the glass substrate in that static electricity is liable to accumulate static electricity, and when the alignment film is offset-printed or the sealing material is screen-printed. When doing so, the problem that the plastic substrate sticks to the printing plate occurs.

FIG. 11 is a sectional view showing a state in which the substrate is attached to the printing plate in the manufacturing process of the liquid crystal display element. Substrate 31 attached to sealant printing plate 30 and peeling pin 3
3 shows the position of the substrate 32 normally peeled off. The state in which the plastic substrate is attached to the printing plate by static electricity means the state in which the substrate is attached to the printing plate by static electricity as shown in FIG. 11 when the alignment film or the sealing material is printed, that is, the state where the substrate floats from the printing stage of the device. Is. In this state, even if the substrate attached to the printing plate is peeled by the peeling pin 33, the position of the substrate 32 that is normally peeled off is displaced from that in the case where the substrate 32 is not attached to the printing plate, and the next substrate is conveyed to the previous position. The contact with the substrate causes defects such as chipping of the substrate and defects on the substrate due to scratches remaining on the substrate. In particular, there is a problem that sticking of a counter substrate without a spacer to a printing plate due to static electricity and sticking of a sealing material to screen printing are conspicuous.

Japanese Unexamined Patent Publication Nos. 6-337427 and 1-134336 do not mention such problems as sticking due to static electricity, but also show the size of columnar spacers. However, as described above, when the size is larger than the predetermined size, the problem of stripe domain may occur.

An object of the present invention is to provide a method for manufacturing a spacer for a liquid crystal display device, which significantly suppresses the generation of static electricity in the manufacturing process and improves the display quality due to the uniform cell thickness.

[0012]

According to the present invention, in a liquid crystal display device in which a pair of plastic substrates are bonded together by a sealant at a seal portion, each of the pair of plastic substrates is at least sequentially columnar spacer and alignment film. And the columnar spacers are block-shaped,
The total surface area per 1 mm ^{2 of the} substrate surface is 8700 μm ² or more and is parallel to the pixel and is provided at least in the seal part, and the short side of the bottom surface is 10 μm or less and the long side is parallel to the side of one pixel. It is a liquid crystal display element characterized by being shorter than the above.

According to the present invention, by providing the columnar spacers on the upper and lower plastic substrates, it is possible to prevent the substrates from sticking due to the influence of static electricity when forming the alignment film. In addition, the columnar spacer has a block shape, and the total surface area is at least 8700 μm per 1 mm ² on the substrate of the seal portion.
When the thickness is less than 8700 μm ² by providing m ² or more, it is possible to avoid the situation where the substrate is stuck to the printing plate under the influence of static electricity during the printing of the sticker for sticking. Therefore, it is particularly useful when screen printing having an opening in the sealing area is carried on a plastic substrate and screen printing is performed by printing the sealing material on the plastic substrate by squeegeeing a screen plate-shaped sealing resin. is there.

Further, since the short side of the bottom surface of the block-shaped spacer is 10 μm or less, even if the above-mentioned condition is satisfied, in the case of a prismatic column, a column, or a block-shaped spacer having a short side larger than 10 μm, the spacer is It is possible to prevent a stripe domain that is generated by disturbing the surrounding orientation. Further, since the long side is set shorter than the side of one pixel on the side facing in parallel, when it is longer than the side of one pixel,
Liquid crystal can be injected smoothly, which cannot be done smoothly. A liquid crystal display element with high display quality can be obtained by bonding the two substrates thus configured together.

In the present invention, the block-shaped spacer has a short side of 5 μm, a long side of 30 μm, and a height of 2 μm.
It is characterized in that it is μm to 4 μm.

According to the present invention, the block spacers formed on the upper and lower plastic substrates have a short side of 5 μm × long side of 30 μm and a height of 2 μm to 4 μm. Is small, that is, the surface area is small, so that the alignment of the liquid crystal around the spacer is good, and a very good display quality can be obtained.

Further, the present invention is characterized in that the block-shaped spacers provided on each substrate are formed by laminating a pair of substrates so that the long sides of their bottom surfaces are orthogonal to each other and face each other in a cross shape. To do.

According to the present invention, the block-shaped spacers of the upper and lower substrates are bonded so as to face each other so that the upper and bottom surfaces of the upper and lower substrates are located in a cross shape, so that the upper and lower substrates are bonded with respect to each other. Since there is a margin in the positional accuracy of the spacers, it is particularly effective when using a plastic substrate with large expansion and contraction, and stable production is possible. Further, the structure of facing each other in a cross shape is particularly effective in a matrix type liquid crystal display element in which striped electrodes formed on the upper and lower substrates are bonded so as to be orthogonal to each other, and the portions where the electrodes overlap are pixels. Can be applied. At this time, set the height of the spacer to 2 μm as described above.
If formed within the range of m to 4 μm, sticking of the plastic substrate to the printing plate due to static electricity, which occurs outside this range, and display quality defects such as uneven cell thickness and stripe domains can be prevented.

Further, the present invention is characterized in that the block-shaped spacer is provided in the display region as a spacer for keeping a gap between the pair of plastic substrates uniform.

According to the invention, the block-shaped spacer is also provided in the display region as a spacer for keeping the gap between the pair of plastic substrates uniform, so that the gap between the substrates is kept uniform and only the seal portion is provided. It is possible to obtain a liquid crystal display element capable of preventing sticking due to static electricity more than in the case of being provided in the above step without increasing the number of steps.

[0021]

FIG. 1 is a perspective view showing a partial configuration of a liquid crystal display element according to an embodiment of the present invention. FIG. 2 is a sectional view taken along the line I-I in FIG. FIG. 3 is a plan view taken along the section line II-II in FIG. 1. FIG. 4 is a plan view taken along the section line III-III in FIG. 1. The liquid crystal display element is a retardation plate type plastic STN (Super Twisted Nematic) type liquid crystal display element, and measures against static electricity are adopted in the manufacturing process thereof. Between the ITO electrodes 3 which are liquid crystal driving electrodes formed on the upper liquid crystal display element substrate 1 and between the ITO electrodes 4 which are liquid crystal driving electrodes formed on the lower liquid crystal display element substrate 2. And the photosensitive columnar spacers 5 formed on the
Are laminated so that the long sides of their bottom surfaces are orthogonal to each other and are positioned in a cross shape. As shown in FIGS. 3 and 4, the photosensitive columnar spacer 5 is a block-shaped spacer having a rectangular bottom surface, and is arranged between the pixels on the upper and lower substrates such that the long sides of the bottom surface are parallel to the pixels 7. It is located in the cross when it is formed and laminated. Further, also in the seal portion where the upper and lower substrates 1 and 2 are attached to each other by the seal material outside the illustrated display area, the photosensitive columnar spacers are formed in exactly the same manner as in the display area.

Upper and lower liquid crystal display element substrates 1, 2
Are both made of plastic or the like, and the photosensitive columnar spacer 5 is made of a photosensitive resin such as JNPC manufactured by JSR. An alignment film (not shown) is formed on the substrate on which the ITO electrodes 3 and 4 and the photosensitive columnar spacer 5 are formed.

FIG. 5 is a conceptual diagram for explaining the relationship between the surface area of the photosensitive columnar spacer 5 and the substrate area. In the photosensitive columnar spacers 5 formed on the lower liquid crystal display element substrate 2, the surface area of the photosensitive columnar spacers 5 is the area of the upper portion 12 in contact with the opposing upper liquid crystal display element substrate 1 and the four side surfaces 1.
3 is the sum of the areas. The same applies to the photosensitive columnar spacers 5 formed on the upper liquid crystal display element substrate 1. The photosensitive columnar spacer 5 is 1 mm ² on the substrate.
Is arranged so that the total surface area is 8700 μm ² or more, and the bottom surface, that is, the short side of the upper portion 12 is 10 μm.
When the length is m or less, the long side is set shorter than the side of one pixel of the pixels 7 arranged in parallel with the long side.

The manufacturing process flow of the liquid crystal display device having the above-mentioned structure is as follows: ITO electrode forming step, photolithography step, alignment film printing step, alignment film RUB processing step, sticker printing step for bonding, sticking of upper and lower substrates. It is carried out in the order of the matching process. That is, the cell thickness controlling spacers of the upper and lower substrates are formed in the process of spraying the cell thickness controlling spacers of the upper and lower substrates, which is performed after the sticking seal printing process in the normal liquid crystal display device manufacturing process flow. In the manufacturing process flow of this embodiment, IT
After forming the O electrodes, the photosensitive columnar spacers 5 are first formed in a photolithography process.

In the above manufacturing process flow, if static electricity is generated in the alignment film printing step and the sticking sticker printing step, the liquid crystal display element substrate may be stuck to the printing plate. In this embodiment, as described above, the shape of the photosensitive columnar spacers 5 and the arrangement on the substrate are devised so that this problem does not occur. That is, in the photosensitive columnar spacer 5, the short side of the upper portion 12 is 10 μm or less, and the long side thereof is set to be shorter than the side of one pixel of the pixels 7 arranged in parallel with the long side. The spacers are arranged at least in the seal portion so that the total surface area is 8700 μm ² or more per 1 mm ² of the substrate surface. The block spacers are formed between the pixels on the upper and lower substrates such that the long sides of the bottom surfaces thereof are parallel to the pixels 7. Further, they are laminated so that the long sides of their bottoms are orthogonal and are located in a cross shape.

The significance of this setting is as follows. First, since the columnar spacers formed on the substrates do not receive static electricity, it is necessary to form the columnar spacers on both substrates in order to prevent sticking of both substrates due to static electricity in the manufacturing process. At that time, the height of the spacer is divided and set with respect to the cell thickness.

Further, the photosensitive columnar spacer 5 is formed on the substrate surface 1
the total surface area per mm ² is provided in less than 8700μm ^2, under the influence of static electricity would have stuck a substrate for a liquid crystal display device in the printing plate at the time seal printing.

If the short side of the upper portion 12 of the block-shaped spacer is larger than 10 μm, the orientation around the spacer is disturbed and a stripe domain is generated. Further, when the long side of the upper portion 12 is larger than the side of one pixel parallel to it, liquid crystal cannot be injected smoothly.

Further, if such a block-shaped spacer is not arranged at least in the seal portion, it is impossible to suppress the generation of static electricity in the sticking sticker printing process in which static electricity is likely to occur.

To satisfy these requirements, for example, a short side of 5 μm × long side of 30 μm × height of 2 μm is formed on a substrate.
3 photosensitive block spacers per 1 mm ² of substrate surface
When 0 pieces are arranged, the total surface area of the block-shaped spacers formed on the substrate per 1 mm ² of the substrate surface is 8700 μm ² . The numerical significance of setting 30 per 1 mm ² is
It is as follows. The size of one general display pixel is 2
It is 50 μm × 100 μm. This is the pitch of one pixel when the pixel pattern is arranged in the display of about SVGA for the three pixels of RGB. 2 between lines between display pixels
It is about 0 μm. Therefore, the number of display pixels existing in 1 mm ² is about 30 pixels. If one block-shaped spacer is arranged for each display pixel, it will be about 30 in 1 mm ^2.
This corresponds to the arrangement of individual block spacers.

Further, since the plastic substrate easily expands and contracts due to heat or the like, when the upper and lower substrates having the columnar spacers formed on the both substrates are bonded together, the columnar spacers having a bottom surface diameter of about 10 μm, which are generally used, face each other. There is a possibility that the fitting accuracy with the spacer on the other side will shift and the fitting accuracy will decrease, resulting in uneven cell thickness. In order to prevent such misalignment, as shown in FIGS. 3 and 4, on the upper and lower substrates, the long sides of the bottom surface of the block-shaped spacer are located between the ITO electrodes 3 and 4 and the ITO electrodes 3 and 4. Block-shaped spacers are arranged so as to be parallel to (pixels) and to be located between adjacent pixels on the ITO electrodes 3 and 4 of one stripe. Then, when the upper and lower substrates are bonded together, the long sides of the bottom surfaces of the spacers of the upper and lower substrates are orthogonal and positioned in a cross shape, so that there is no misalignment with the spacers on the opposite side, cell thickness unevenness, stripe domain, etc. It is possible to avoid the occurrence of defective display quality.

Example 1 After forming an ITO electrode on a 300 cm × 420 cm square plastic substrate, the upper portion (bottom surface) of the spacer was 5 μm by photolithography.
m × 30 [mu] m, the photosensitive block-shaped spacer height 2.0 .mu.m, 30 pieces at a rate per substrate surface 1 mm ^2, as shown in FIGS. 3 and 4, stripes long sides of the bottom surface is a pixel Was formed between the ITO electrodes so as to be parallel to the ITO electrode, and the static electricity amount was measured at the time of printing the alignment film and at the time of printing the sticker for bonding.

(Example 2) The height of the spacer is 3.0 μm.
Except for the above, a block-shaped spacer was formed in the same manner as in Example 1, and the static electricity amount was measured at the time of printing the alignment film and at the time of printing the sticker for sticking.

(Embodiment 3) The height of the spacer is 4.0 μm.
Except for the above, a block-shaped spacer was formed in the same manner as in Example 1, and the static electricity amount was measured at the time of printing the alignment film and at the time of printing the sticker for sticking.

(Embodiment 4) The height of the spacer is 4.5 μm.
Except for the above, a block-shaped spacer was formed in the same manner as in Example 1, and the static electricity amount was measured at the time of printing the alignment film and at the time of printing the sticker for sticking.

(Embodiment 5) The height of the spacer is 6.0 μm.
Except for the above, a block-shaped spacer was formed in the same manner as in Example 1, and the static electricity amount was measured at the time of printing the alignment film and at the time of printing the sticker for sticking.

(Example 6) A block-shaped spacer was formed in the same manner as in Example 1 except that the upper portion (bottom surface) of the spacer was 5 μm × 50 μm and the height was 2 μm. And the static electricity amount was measured at the time of printing the sticker for laminating.

(Embodiment 7) The upper portion of the spacer is 5 μm ×
A block-shaped spacer was formed in exactly the same manner as in Example 1 except that the height was set to 50 μm and the height was set to 4 μm, and the static electricity amount was measured at the time of printing the alignment film and at the time of printing the sticker for sticking.

(Embodiment 8) The upper portion of the spacer is 10 μm
A block-shaped spacer was formed and the amount of static electricity was measured in the same manner as in Example 1 except that the height was × 30 μm and the height was 2 μm.

(Embodiment 9) The upper portion of the spacer is 10 μm.
A block spacer was formed in exactly the same manner as in Example 1 except that the thickness was × 30 μm and the height was 4 μm, and the amount of static electricity was measured during printing of the alignment film and during printing of the sticker for sticking.

(Comparative Example 1) Without using a photosensitive spacer,
According to the flow of the usual manufacturing process, after forming the ITO electrode on the plastic substrate, the static electricity amount was measured at the time of printing the alignment film and at the time of printing the sticker for bonding.

(Comparative Example 2) The upper portion of the spacer is 5 μm ×
A block spacer was formed in exactly the same manner as in Example 1 except that the height was set to 15 μm and the height was set to 2 μm, and the static electricity amount was measured at the time of printing the alignment film and at the time of printing the sticker for sticking.

(Comparative Example 3) The upper portion of the spacer is 5 μm ×
A block spacer was formed in exactly the same manner as in Example 1 except that the height was 4 μm and the thickness was 15 μm, and the amount of static electricity was measured during printing of the alignment film and during printing of the sticker for bonding.

(Comparative Example 4) The upper portion of the spacer is 10 μm.
A spacer was formed in the same manner as in Example 1 except that a prismatic spacer having a height of 6 μm and a size of 10 μm was formed, and the amount of static electricity was measured during printing of the alignment film and during printing of the sticker for sticking.

(Comparative Example 5) FIG. 6 is a plan view showing the arrangement of the cylindrical spacers 15 on the upper liquid crystal display element substrate 1. FIG. 7 is a plan view showing an arrangement state of the columnar spacers 15 on the lower liquid crystal display element substrate 2. As described above, the plastic substrate easily expands and contracts due to heat. Therefore, when the upper and lower substrates having the columnar spacers formed on the both substrates are bonded to each other, the columnar spacers having a bottom surface diameter of about 10 μm are commonly used. There is a possibility that the fitting accuracy with the spacer on the other side will shift and the fitting accuracy will decrease, resulting in uneven cell thickness. In order to prevent such fitting deviation, one columnar spacer having a height equal to the cell thickness is provided for two display pixels on the upper and lower substrates, as shown in FIGS. 6 and 7. As described above, 15 pieces are provided in a comb shape per 1 mm ² of the substrate surface. When bonding the upper and lower substrates, the columnar spacers formed on each substrate contact the opposing substrates,
Prevents misalignment.

After forming an ITO electrode on a plastic substrate, a photosensitive cylindrical spacer having a diameter of 10 μm and a height of 6 μm in the upper portion (bottom surface) of the spacer is formed by photolithography at a rate of 15 per 1 mm ² of the substrate surface. Then, Fig. 6
As shown in FIG. 7 and FIG. 7, the electrodes were formed between the ITO electrodes so as to be in contact with the opposing substrate, and the static electricity amount was measured at the time of printing the alignment film and at the time of printing the sticker for sticking.

(Comparative Example 6) The diameter of the upper portion of the spacer is set to 1
Cylindrical spacers were formed in exactly the same manner as in Comparative Example 5 except that the thickness was 5 μm, and the static electricity amount was measured at the time of printing the alignment film and at the time of printing the sticker for sticking.

(Comparative Example 7) The height of the spacer is 1.5 μm.
Except for the above, a block-shaped spacer was formed in exactly the same manner as in Example 1, and the static electricity amount was measured at the time of printing the alignment film and at the time of printing the sticker for sticking.

(Comparative Example 8) The upper portion of the spacer is 15 μm.
A block-like spacer was formed in exactly the same manner as in Example 1 except that the thickness was × 30 μm, and the static electricity amount was measured at the time of printing the alignment film and at the time of printing the sticker for sticking.

(Comparative Example 9) The upper portion of the spacer is 15 μm.
A block spacer was formed in exactly the same manner as in Example 1 except that the thickness was × 30 μm and the height was 4 μm, and the static electricity amount was measured at the time of printing the alignment film and at the time of printing the sticker for sticking.

(Comparative Example 10) The upper portion of the spacer is 20 μm.
A block-shaped spacer was formed in exactly the same manner as in Example 1 except that m × 30 μm was used, and the amount of static electricity was measured during printing of the alignment film and during printing of the sticker for sticking.

(Comparative Example 11) The upper portion of the spacer is 20 μm.
Block-shaped spacers were formed in exactly the same manner as in Example 1 except that m × 30 μm and height were 4 μm.
The amount of static electricity was measured at the time of printing the alignment film and at the time of printing the sticker for laminating.

(Comparative Example 12) A cylindrical spacer was formed in exactly the same manner as in Comparative Example 5 except that the diameter of the upper portion of the spacer was set to 20 μm, and the static electricity amount was adjusted during alignment film printing and sticking sticker printing. It was measured.

(Evaluation Method) Examples 1 to 9 and Comparative Example 1
Table 1 shows the evaluation results of the relationship between the height of the photosensitive columnar spacers, the total surface area, the amount of static electricity on the liquid crystal display element substrate, and the sticking to the substrate in the measurement of the amount of static electricity of No.
In the case of the block-shaped spacer, the surface area is the sum of the area of the upper portion 12 in contact with the facing substrate and the sum of the areas of the four side surfaces 13, as shown in FIG. The surface area of the cylindrical spacer is the sum of the upper partial area in contact with the facing substrate and the side surface area in the circumferential direction.

Further, Examples 1 to 3 and 6 to 9 and Comparative Example 8
Liquid crystal display elements were manufactured as shown in FIGS. 3, 4, 6 and 7 by using the plastic substrates that have been subjected to the static electricity amount measurement test in FIGS. The evaluation results are shown in Table 2. In addition,
The cell thickness of the liquid crystal display element was 6 μm for all the examples and comparative examples from the viewpoint of display quality and response speed.

[0056]

[Table 1]

[0057]

[Table 2]

(Evaluation Results) From Table 1, in Comparative Example 1 in which the static electricity amount is 1.3 kV or more when printing the alignment film and in Comparative Examples 1 to 7 in which the static electricity amount is 1.0 kV or more when the seal printing is performed, As shown in 11, it was confirmed that the liquid crystal display device substrate was attached to the printing plate. In the substrate of Comparative Example 1 manufactured by the process of the normal manufacturing flow in which the photosensitive spacer is not formed on the plastic substrate, the process of attaching the substrate to the alignment film printing plate due to static electricity caused a process defect. A photosensitive spacer with a diameter of 1 on a plastic substrate.
In Comparative Examples 5 and 6 formed in a columnar shape having a size of 5 μm or less, the substrate was attached to the sealing material printing plate. Block-shaped spacer on plastic substrate 1 mm ²
The total surface area per 1 is less than 8700 μm ² .
In No. 7, the substrate stuck to the sealant printing plate due to static electricity, resulting in a process defect.

From the above results, as in Examples 1 to 9,
Block-shaped spacers with a total surface area of 8700 μm ² or more have a static electricity amount of 1.3 kV or more when printing an alignment film and a static electricity amount of 1.0 kV or more when printing a sticker in the flow of process steps, and thus the printing plate is exposed to static electricity. It has been found that it is possible to prevent sticking of the substrate.

From Table 2, using two substrates of Comparative Example 12 in which the photosensitive spacers sandwiched between the plastic upper and lower substrates are formed in a cylindrical shape having a diameter of 20 μm as shown in FIGS. 6 and 7. In the produced liquid crystal display element, the substrate on the opposite side was distorted by the stress of the columnar spacer, and uneven cell thickness occurred. Photosensitive spacers sandwiched between the upper and lower plastic substrates were formed using the substrates of Comparative Examples 8 to 11 which were formed in a block shape having a short side length of 15 μm or more as shown in FIGS. 3 and 4. In the liquid crystal display element, the block-shaped spacer disturbs the alignment of the liquid crystal around the spacer, resulting in a decrease in contrast and generation of stripe domains. The liquid crystal display device in which the substrates of Examples 1 to 3 and 6 to 9 in which the photosensitive spacers are formed in a block shape on the plastic upper and lower substrates are laminated, the fitting accuracy of the spacers of the upper and lower substrates and the spacers of the substrates facing each other is high. Was excellent and had good display quality. The alignment state of the liquid crystal around the block spacer was better as the surface area of the spacer was smaller. Example 2
The setting with the combination of Example 4 and Example 4 and the combination with Example 3 had the best display state.

From the above results, in a liquid crystal display device manufactured by using a combination of plastic substrates so as to have a cell thickness of 6 μm, the total surface area is 8700 μm 2 as in Examples 1 to 3 and 6 to 9. It was found that the above block-shaped spacers formed on the upper and lower substrates so that the spacers face each other with the short side of the bottom surface of 10 μm or less and the long side of which is shorter than the side of one pixel have a good display quality. .

[0062]

According to the present invention, the columnar spacers provided on the upper and lower plastic substrates are block-shaped, and the total surface area 870 per 1 mm ² is at least on the substrate of the seal portion.
Since it is 0 μm ² or more, and the short side of the bottom surface is 10 μm or less and the long side is shorter than the side of one pixel on the side facing in parallel, the plastic substrate for liquid crystal display element is printed by the influence of static electricity in the process flow. There is an effect that it can be produced stably without being stuck on the plate. In particular, it is useful when applied to a liquid crystal display element in which the sealing material is formed by screen printing.

By reducing the size of the block-shaped spacer, the alignment of the liquid crystal is less adversely affected and the time required for the liquid crystal injection step can be shortened.

Further, when the block-shaped spacers are made to face each other so that their upper and lower surfaces are located in a cross shape when the upper and lower substrates are attached, cell thickness control is uniformly performed, and improvement in display quality is confirmed. Therefore, the plastic liquid crystal display device having improved uniformity of cell thickness control can obtain the effect of suppressing the occurrence of display unevenness in halftone display or optimum voltage display as much as possible.

Furthermore, by making the block-shaped spacer also serve as a spacer for keeping the gap uniform, it is possible to obtain a liquid crystal display element in the same process as the conventional process without increasing the number of steps.

[Brief description of drawings]

FIG. 1 is a perspective view showing a partial configuration of a liquid crystal display element according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the section line II of FIG.

FIG. 3 is a plan view taken along section line II-II in FIG.

FIG. 4 is a plan view taken along section line III-III in FIG.

FIG. 5 is a conceptual diagram for explaining the relationship between the surface area of photosensitive columnar spacers 5 and the substrate area.

FIG. 6 is a plan view showing an arrangement state of columnar spacers 15 on the upper liquid crystal display element substrate 1.

FIG. 7 is a plan view showing an arrangement state of columnar spacers 15 on the lower liquid crystal display element substrate 2.

FIG. 8 is a perspective view showing a configuration of a conventional liquid crystal display element in which columnar spacers are formed.

FIG. 9 is a cross-sectional view showing a configuration of a conventional liquid crystal display device in which a plastic bead spacer is formed.

FIG. 10 is a cross-sectional view showing a configuration of a conventional liquid crystal display element having columnar spacers formed thereon.

FIG. 11 is a cross-sectional view showing a state in which the substrate is attached to the printing plate in the manufacturing process of the liquid crystal display element.

[Explanation of symbols]

1 Upper liquid crystal display device substrate 2 Lower liquid crystal display device substrate 3,4 ITO electrode 5 Photosensitive column spacer 7 pixels 12 Upper part 13 sides

Claims (4)

[Claims] 1. A liquid crystal display device comprising a pair of plastic substrates bonded together at a sealing portion by a sealing material, wherein each of the pair of plastic substrates is provided with a columnar spacer and an alignment film at least sequentially. The spacer is block-shaped and has a total surface area of 8700 μm ² or more per 1 mm ² of the substrate surface and is provided at least in the seal portion in parallel with the pixel, and has a short side of the bottom surface of 10 μm or less and a long side in parallel. A liquid crystal display element characterized in that it is shorter than the side of one pixel on the side to be filled. 2. The block-shaped spacer has a short side of 5 μm.
2. The liquid crystal display element according to claim 1, wherein the liquid crystal display device has a length of m, a long side of 30 μm, and a height of 2 μm to 4 μm. 3. A pair of substrates are laminated so that the block-shaped spacers provided on each substrate face each other so that the long sides of their bottom surfaces are orthogonal and overlap each other in a cross shape. 3. The liquid crystal display device according to 1 or 2. 4. The block-shaped spacer is provided in the display area as a spacer for maintaining a uniform gap between the pair of plastic substrates. Liquid crystal display element.