JPH1124083A - Spacer discharging method and lcd element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately arrange spacers and to improve display quality and productivity by discharging plural spacers in one discharge and arranging them at nearly constant spaces apart in a state with plural spacers aggregated. SOLUTION: In discharging granular spacers for adjusting substrate spaces of LCD elements on a substrate by means of an ink jet device, the plural spacers are designed to be discharged in one discharge and arranged nearly at constant spaces apart in a state where they are aggregated, namely, in an aggregated body 3. As a result, the discharging space of the spacers can be taken widely, enabling most spacers to be arranged in a non-display part other than the pixels used for display. Particularly, with 2-10 pieces of spacers arranged in the form of an aggregated body 3 on a light shielding film 2 on such substrate, almost no spacers are arranged in the pixels used for display and also the light is shielded in the part of the light shielding film 2; therefore, possibility of light leak is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a spacer discharging method for discharging a spacer onto a substrate using an ink jet device, and a liquid crystal display device manufactured using the same.

[0002]

2. Description of the Related Art In a display element such as a liquid crystal display element, a spherical or fibrous spacer is arranged between substrates in order to keep a constant gap between the substrates. Conventionally, this spacer is sprayed on a substrate by a spray method or the like using a spacer spraying device. This spacer is usually 5000 to 30000 pieces / cm
It is used after being sprayed about ^two times.

However, when such spraying is performed, the spacers tend to be unevenly distributed. In particular, when a large number of spacers are aggregated in a display pixel, such a problem is recognized that the display quality deteriorates. Also, TFT
When a substrate provided with active elements such as the above is used, there is a problem that if a spacer is provided at the protruding TFT portion, the TFT is easily damaged when a force is applied to the substrate.

For this reason, it is desired to designate a place where the spacer is to be arranged, to avoid the TFT part, or to arrange the spacer in the light shielding film part. In order to solve this, it has been proposed to arrange the spacers by printing, or to supply them to a specific position using a dispenser or an ink jet device.

[0005] In the printing method, the printing plate comes into direct contact with the surface subjected to the alignment treatment, which may adversely affect the alignment film. In addition, since such printing ink contains a high-viscosity solvent, the solvent is less likely to volatilize,
In some cases, the alignment state was adversely affected.

On the other hand, in the supply by the ink-jet method, granular spacers can be arranged one by one at almost accurate positions. If an ink-jet head having a large number of nozzles is used, a large number of spacers are simultaneously arranged at designated positions. It has the advantage of good productivity because it is possible.

[0007]

According to the method of dispersing the spacers, the dispersed spacers agglomerate, and if the agglomeration increases in the pixels used for display, light is scattered, resulting in a display defect. Be recognized. For this reason, it is preferable that the spacers be uniformly arranged.

For this reason, it is conceivable to arrange the spacers one by one at equal intervals in the supply of spacers by the ink jet method. However, since the required number of spacers is determined by the target liquid crystal display element, a large number of spacers are also arranged in the pixel region for displaying.

For this reason, it has been desired to manufacture a liquid crystal display element having a small display space and high display quality with high productivity in a pixel region for display. An object of the present invention is to solve these problems, to accurately arrange spacers by using an ink jet method, and to manufacture a liquid crystal display device having high display quality with high productivity.

[0010]

SUMMARY OF THE INVENTION According to the present invention, there is provided a spacer discharging method for discharging granular spacers onto a substrate by using an ink jet apparatus. A spacer discharging method characterized by being arranged at a substantially constant interval in an aggregated state, and a light shielding film is provided on a substrate so as to surround pixels, and the light shielding film is formed in a T-shape or cross shape. The present invention provides the above-described spacer discharging method of discharging a spacer at a portion intersecting in a shape, and the above-described spacer discharging method of discharging a spacer by scanning an inkjet head in a short side direction of a pixel.

In a liquid crystal display device in which a pair of alignment-treated substrates are opposed to each other and a liquid crystal and a granular spacer are sandwiched between the substrates, the spacers are supplied by an ink jet method, and non-display portions other than pixels used for display are provided. A liquid crystal display element characterized in that 2 to 10 spacers are arranged at substantially constant intervals in an aggregated state, and a light-shielding film is provided on at least one substrate so as to surround the pixel, The present invention provides the above-mentioned liquid crystal display device, wherein the spacer is arranged in a state where the light-shielding film intersects in a T shape or a cross shape in a state where the spacer is aggregated.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a plurality of spacers are ejected by one ejection when ejecting a granular spacer for adjusting a substrate gap of a liquid crystal display element onto a substrate by using an ink jet apparatus. The plurality of spacers are arranged at substantially constant intervals in an aggregated state. Thereby, the discharge interval of the spacers can be widened, and most of the spacers can be arranged in non-display portions other than pixels used for display.

In particular, the light-shielding film portion on the substrate has
By arranging the individual spacers in an aggregated state, the spacers are hardly arranged in the pixels used for display, and the light is shielded at the light shielding film portion, so that there is no fear of light leakage.

FIG. 1 is a plan view of a substrate on which the spacer of the present invention has been discharged, and FIG. 2 is a partially enlarged view thereof. 1 and 2, 1, 1A, 1B, 1C, and 1D are pixels, 2
Denotes a light shielding film, 3 denotes a spacer aggregate, 4A, 4B and 4C denote individual spacers of the spacer aggregate.

FIG. 3 is a front view of a typical example of the spacer discharge device used in the present invention. 3, reference numeral 11 denotes an ink jet head, 12 denotes a guide rail on which the ink jet head 11 moves, 13 denotes a substrate, 14 denotes a slide table on which the substrate 13 is mounted, and 15 denotes a base on which the slide table is mounted.

In the apparatus shown in FIG. 1, the ink jet head 11 moves on the guide rail 12. That is, the spacer is discharged while moving in the left-right direction in the figure. On the other hand, the slide table 14 moves in the depth direction in the figure. Thereby, the spacer can be discharged to an arbitrary position on the substrate. The positioning of the ejection position is not limited to this example, and the inkjet head itself may be movable in two directions, left, right, and depth, and the slide table itself may be movable in two directions, left, right, and depth. Good.

Although this spacer discharge device is used for various purposes, it is particularly preferable to use it for a spacer discharge device of a liquid crystal display element. In a liquid crystal display device, a spacer is arranged between two substrates in order to keep a constant gap between the two substrates. This is used regardless of whether it is an STN type liquid crystal display element or a TFT type liquid crystal display element.

Since the spacers are recognized as light leakage or black spots of the liquid crystal display element when agglomerated, they are preferably arranged as dispersed as possible. However, by aggregating the spacers as in the present invention and disposing the aggregates of the spacers in the non-display area other than the pixels used for display, the display quality of the pixel area is increased, and the productivity is improved. can do.

The ink jet head used in the present invention may have a known structure such as a head driven by a piezoelectric element or a head driven by evaporating a solution by heating. In the present invention, unlike a normal colored ink, a large-diameter spacer, that is, a type driven by a piezoelectric element is preferably used in order to discharge a solid substance.

The number of nozzles of the ink jet head may be one, or several tens or more nozzles may be used. Since the discharge from each nozzle can be controlled in the ink jet head, it is usually preferable to arrange the spacers using an ink jet head having a large number of nozzles from the viewpoint of productivity.

As the spacer used in the present invention, any spacer can be used as long as the spacer can be discharged from the nozzle of the ink jet head. Although the diameter of the spacer varies depending on the purpose of use, it is usually about 2 to 20 μm for a liquid crystal display element. The material of the spacer is typically made of plastic, but glass or ceramic can be used as long as it is granular. As the spacer in the present invention, a spherical spacer, a cylindrical spacer having substantially the same diameter and height, and the like can be used.

In the present invention, two to ten spacers are ejected in one ejection. Thereby, the plurality of spacers are in an aggregated state. In the aggregate of the spacers, 2 to 10 spacers are aggregated. However, most of the aggregates are arranged in a non-display portion other than the pixel used for display, so that the display quality is hardly reduced.

The term “aggregation” means not only the case where a plurality of spacers are in contact with adjacent spacers, but also
It also means that it exists at intervals within the range of its diameter. In the example of FIG. 2, three spacers are shown close to each other. The spacers 4A and 4B and the spacers 4B and 4C are close to each other with an interval within the diameter thereof, and the spacers 4A and 4C are close to each other with an interval exceeding the diameter. In the present invention, this 3
The spacers are considered to be aggregated.

In the present invention, the spacer is basically arranged in a non-display portion other than the pixel used for display. this is,
This is because it is difficult to completely prevent some of the spacers from entering the pixels used for display because the spacers are ejected by the inkjet method and the line width of the light shielding film is narrow. It is most preferable that the spacers can be arranged only in non-display portions other than the pixels used for display. However, if 80% or more of the spacers are arranged in the non-display portions, the deterioration of display quality is small. .

The pixel used for the display means a portion where the electrodes face each other and the display is intentionally changed depending on the voltage application state. In the case of display using a normal dot matrix, pixels are rectangular and a non-display portion is formed so as to surround the periphery. If there is an active element such as a TFT, that part is also usually used as a non-display part. In some cases, spacers are not arranged in the active element part to prevent damage to the active element due to pressurization.In such a case, the spacer is arranged in the non-display part and in the part without the active element. Become.

This non-display portion is preferably covered with a light-shielding film in order to increase the display contrast ratio. In the present invention, since the spacers are arranged so as to be aggregated, it is preferable to provide a light-shielding film in the non-display portion because light leakage due to aggregation is not visible. In the following description, it is assumed that the non-display portion has a light shielding film.

Color STNLCD and color TFTLCD
In FIG. 1, as shown in FIG. 1 and FIG. 2, a large number of RGB three-color pixels are arranged surrounded by a light-shielding film. In the present invention, the spacer is ejected such that the spacer aggregate 3 is located on the light shielding film 2. This pixel is usually formed with a short side at a pitch of 50 to 150 μm. This is determined by the display area and the number of pixels arranged therein. In the case of RGB three-color pixels, generally, three rectangular pixels collectively constitute a substantially square display area.

For example, in the case of SVGA display at 12.1 inches, the pitch on the short side is about 102 μm, and the pitch on the long side is about 306 μm. A light-shielding film 2 is formed in a portion surrounding the pixel 1. The light-shielding film is patterned in consideration of the patterning accuracy of the electrodes and the positioning accuracy of the two substrates. If the accuracy is reduced, the width of the light-shielding film becomes wider, the aperture ratio of the pixels decreases, and the display becomes darker.
It is better that the width of the light-shielding film is as narrow as possible. Therefore, the width of the light shielding film is generally set to about 10 to 25 μm.

When no active element is provided in STNLCD,
The pitch on the short side is about 102 μm, and the pitch on the long side is about 3
06 μm and the width of the light shielding film is 20 μm,
The shape of each pixel is 82 × 286 μm, and the aperture ratio is about 7
5%. In the present invention, a spacer is discharged to a portion where the light shielding film is provided.

In this case, it is preferable to discharge a spacer at a portion where the light shielding film crosses in a T-shape or a cross shape. In the examples of FIGS. 1 and 2, rectangular pixels are repeatedly arranged vertically, horizontally, and horizontally. That is, the lines of the light-shielding film are provided in the form of a lattice in a straight line at the top, bottom, left and right. The portion where the light shielding film crosses in a cross shape is described with reference to FIG.
It is a portion where four ends of the pixels 1A, 1B, 1C, and 1D are gathered. That is, the light-shielding film connected vertically and the light-shielded film connected left and right intersect.

The portion where the light-shielding film intersects in a T-shape means, for example, a case where pixels are arranged with a shift of ピ ッ チ pitch. It is the part that intersects the character shape. FIG. 2 corresponds to the case where the pixel 1C and the pixel 1D are connected (there is a light-shielding film between the pixel 1A and the pixel 1B, but no light-shielding film between the pixel 1C and the pixel 1D).

When a spacer is discharged at a portion where such a light-shielding film intersects in a T-shape or a cross shape, even if the spacer is moved by landing, it can jump into a pixel used for display outside the light-shielding film. Is less effective.

[0033] If, when the substrate gap of the liquid crystal display element and 4 [mu] m, when discharges the spacer one by one, in the short side about 102μm pitch, since the long side is disposed approximately 306μm pitch, 1 cm ² per The number of spacers is 3
Only about 200. There is no problem if the substrate gap can be sufficiently controlled by the number of spacers. However, in the case of such a spacer diameter, the substrate gap cannot be sufficiently controlled unless 5000 or more spacers are provided per 1 cm ² .

The state in which the 3200 spacers are arranged is replaced with the spacer aggregate 3 in FIG.
The individual spacers are arranged. When arranging the spacers by the inkjet method, the inkjet head may be scanned in the horizontal direction or the vertical direction in FIG. 1 to discharge the spacers.

In order to increase the number of spacers, it is conceivable to further arrange spacers between the spacers on the short side of the pixel, but usually it is also conceivable to arrange further spacers between the spacers on the long side of the pixel. Can be This is because the distance between the spacers on the short side is 102 μm, while the distance between the spacers on the long side is 306 μm, and if one spacer is interposed, the distance between the spacers is 153 μm. If two spacers are arranged between them, the distance between the spacers becomes 102 .mu.m, and the pitch between the short sides and the arrangement becomes closer.

However, with this arrangement, the spacer is discharged to the narrow portion of the linear shape of the light-shielding film, and since the spacer is discharged with a liquid having a small solid content, it is easy to move after landing. The possibility that the spacer is arranged in the region increases. Further, in order to arrange two spacers between the long sides, the arrangement interval of the spacers is 102 μm
It is necessary to increase the pitch, the distance between the nozzles of the inkjet head to 102 μm, and increase the number of nozzles.

According to the present invention, instead of arranging the spacers one by one as described above, two to one spacers are ejected to one place at one time.
Arrange 0 spacers. Therefore, it is sufficient to dispose a spacer aggregate in which 2 to 10 spacers are aggregated only in a portion where the light shielding films cross in a cross shape as shown in FIG. In this case, if two spacers are coherently arranged at one location, 1c
m ² per spacer number is about 6400, if aggregation arranged three spacers in one place, the spacer per 1 cm ² is about 9600.

Even if such spacers are arranged, each spacer is almost agglomerated, and is present only in a portion where the light shielding film crosses in a cross shape. This is because a plurality of the spacers are ejected in one ejection, and since the solid content increases, the spacers hardly move after impact, so
This is because the spacers aggregate and it is difficult for the spacers to jump out of the light-shielding film portion into the pixel region.

Further, since the spacers are arranged as shown in FIG. 1, if the ink jet head scans in the horizontal direction in the figure, the nozzle pitch may be 306 μm.
Spacers can be arranged with a small number of nozzles, resulting in good productivity.
When the number of nozzles is small, the possibility of occurrence of ejection failure is reduced, and the yield is improved.

That is, an inkjet head having a nozzle pitch of 306 μm is used as an inkjet head, and the inkjet head can be scanned in the short side direction of the pixel, that is, in the left-right direction in FIG. 1 to discharge the spacer.

In this case, an ink jet head having a fixed nozzle pitch of 306 μm may be used as the ink jet head, and an ink jet head having a pitch longer than that may be used, and the ink jet head may be inclined with respect to the scanning direction. Scanning.

The discharge liquid used to discharge the spacer may be any discharge liquid that can be discharged from the ink jet head, and usually a mixture of the spacer and an organic solvent, an aqueous solvent or a mixed solvent thereof is used. The ratio between the spacer and the solution may be appropriately set within a range in which the liquid can be ejected from the nozzles of the inkjet head. This varies depending on the diameter of the spacer, but is usually about 0.05 to 5% by weight.

The solution mixed with the spacer contains, in addition to the spacer, the organic solvent and water, an adhesive used for bonding the spacer to the substrate surface, a dispersant for improving dispersibility, and the like. Is also good.

As a substrate of the liquid crystal display element, a substrate having only electrodes provided thereon, a substrate having an alignment film formed thereon,
A substrate on which a color filter or a light-shielding film is formed, a substrate on which an active element such as a TFT is formed, and a substrate formed by combining these members can be used.

In the case of a liquid crystal display element, a non-hydrophilic organic resin-based alignment film represented by polyimide is often used. In this case, it is preferable that the solution combined with the spacer contains as much water as possible with a high surface tension.

The liquid crystal display element is formed by stacking two substrates. For this reason, the spacer of the present invention is usually arranged on one substrate by an inkjet method. Then, a liquid crystal display element is manufactured by being overlapped with the other substrate. The substrate on which the spacer is discharged is preferably the substrate on the side on which the light-shielding film is formed, from the viewpoint of alignment.

[0047]

【Example】

"Example 1 (Example, Comparative Example)"
Using a device as shown in FIG.
A D camera and a fiberscope light source were provided. An ink jet head having a nozzle interval of 306 μm was prepared. As the spacer, a plastic spherical spacer having a diameter of 4 μm (trade name “Micropearl” manufactured by Sekisui Chemical Co., Ltd.) was used. The discharge liquid contains 0.1% by weight of the solid content of the spacer and 0.1% by weight.
2 wt%, 0.3 wt%, and 0.6 wt% were used, and the solvent composition used was water / ethylene glycol / ethylene glycol monobutyl ether = 90/8/2 (weight ratio).

A glass substrate having a polyimide alignment film formed on the surface of a color filter substrate with ITO was prepared.
Using this substrate, the liquid containing the spacer was discharged while scanning the ink jet head in the left-right direction of FIG.

The size of the color filter substrate is 1
A 2.1-inch SVGA manufactured by a pigment dispersion method was used. As shown in FIG. 1, the discharge position of the spacer was aimed at a portion where the light shielding film (line width: about 15 μm) crossed in a cross shape. This gap is shielded from light by a light-shielding film, and the gap has a depth of about 0.3 μm because there is no transparent electrode.

In the ejection of the spacer from the ink jet head, the average number of spacers was set to 1 to 6 per ejection by setting the solid content of the spacer to 0.1 to 0.6% by weight. A color STN-type liquid crystal display element was manufactured using each of the substrates, and color unevenness of display was observed.

As a result, the solid content of the spacer was reduced to 0.1% by weight.
In this case, the average number of spacers is almost one at the portion where the light shielding film crosses in a cross shape, and the spacer density is about 3
It became 300 pieces / cm ² . Similarly, when the solid content of the spacers is 0.2% by weight, 0.3% by weight, and 0.6% by weight, the average number of spacers is approximately 2 to 6 at the portions where the light-shielding films cross each other in a cross shape. And the spacer densities increased respectively. When a color STN type liquid crystal display device was manufactured using these substrates, almost no color unevenness was found.

Example 2 (Example, Comparative Example) Using the same substrate and the same ink-jet head as in Example 1, the interval (short side interval) for discharging the spacer on the short side of the pixel was 51 μm.
76.5 μm, 102 μm, 153 μm, 204 μm,
The ratio of the spacer within the range of the light-shielding film was measured by changing to 306 μm. For comparison, the measurement was carried out for both 0.1% by weight (approximately 1 discharge average spacer) and 0.6% by weight (approximately 6 discharge average spacers) of the solid content of the discharge liquid.

Table 1 shows the results. As is clear from Table 1, when the spacer is discharged to the place where the light shielding films cross in a cross shape (short side interval = 102 μm, 204 μm).
m, 306 μm), it was found that approximately 90% of the light-shielding film portions had spacers. When the short side interval is small, it has been confirmed that when the plurality of spacers are discharged by one discharge, the spacers are clearly often present in the light shielding film portion.

In order to obtain the number of spacers exceeding the number of spacers (5000 pieces / cm ² ) necessary for reducing color unevenness, when the solid content of the discharged liquid is 0.1% by weight, the following Table 1 is used. 51 μm or less is required at short side intervals. On the other hand, in the case of 0.6% by weight, the short side interval of 306 μm or less is satisfied.

Example 3 (Example, Comparative Example) The same substrate as in Example 1 was used, and the ink jet head had a nozzle interval of 102.
The ink jet head was scanned in the vertical direction in FIG. The interval (long side interval) for discharging the spacer on the long side of the pixel is 102 μm and 153.
The ratio of the spacers within the range of the light-shielding film was measured while changing to μm, 204 μm, and 306 μm. For comparison,
The test was carried out for both the 0.1% by weight (approximately 1 discharge average spacer) and the 0.6% by weight (approximately 6 discharge average spacers) of the solid content of the discharged liquid.

Table 2 shows the results. As is clear from Table 2, except when the spacer is discharged to the place where the light-shielding film crosses in a cross shape (interval of long side = 306 μm).
It was found that only less than 80% of the spacers existed in the light-shielding film portion.

In order to obtain the number of spacers exceeding the number of spacers (5000 pieces / cm ² ) necessary to reduce color unevenness, when the solid content of the discharged liquid is 0.1% by weight, the following Table 2 is used. 102 μm or less is required for the long side interval. On the other hand, in the case of 0.6% by weight, the long side interval satisfies 306 μm or less.

Since the number of nozzles of the ink jet head was the same as in Examples 1 and 2, the drawing speed on the same substrate in Example 2 was reduced to 1/3, and the productivity was low.

[0059]

[Table 1]

[0060]

[Table 2]

[0061]

According to the spacer ejection method of the present invention, a plurality of spacers are ejected by one ejection in an ink jet apparatus, and the plurality of spacers are arranged at a substantially constant interval in an aggregated state. ing. Thereby, the discharge interval of the spacers can be widened, and most of the spacers can be arranged in non-display portions other than pixels used for display.
Thus, a decrease in the contrast ratio of the pixel region due to the spacer can be suppressed.

Further, 2 to 10
By arranging the individual spacers in an aggregated state, almost no spacers are arranged in the pixels used for display, and light is shielded at the light-shielding film portion, so that there is no fear of light leakage. In particular, by discharging the spacer to the portion where the light-shielding film is cross-shaped or T-shaped, the ratio of the spacer flowing out to the pixel region is reduced, and the reduction in the contrast ratio of the pixel region due to the spacer can be largely suppressed.

Further, since a plurality of spacers are ejected by one ejection, the nozzle interval of the ink jet head can be widened, the drawing speed on one substrate can be improved, and the productivity is high. The present invention can be applied to various applications within a range that does not impair the effects of the present invention.

[Brief description of the drawings]

FIG. 1 is a plan view of a substrate on which a spacer is discharged according to the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a front view of a representative example of a spacer discharge device used in the present invention.

[Explanation of symbols]

 1: Pixel 2: Light shielding film 3: Spacer aggregate 4: Spacer 11: Inkjet head 12: Guide rail 13: Substrate 14: Slide table 15: Base

Claims (5)

[Claims] In a spacer discharging method for discharging granular spacers onto a substrate by using an ink jet device, a plurality of spacers are discharged by one discharge, and the plurality of spacers are aggregated at substantially constant intervals. A spacer discharging method characterized by being arranged. 2. The spacer discharging method according to claim 1, wherein a light shielding film is provided on the substrate so as to surround the pixel, and the spacer is discharged at a portion where the light shielding film crosses in a T shape or a cross shape. 3. The spacer discharging method according to claim 1, wherein the spacer is discharged by scanning the inkjet head in the short side direction of the pixel. 4. A non-display portion other than pixels used for display in a liquid crystal display device in which a pair of alignment-treated substrates are opposed to each other and a liquid crystal and a granular spacer are sandwiched between the substrates. A liquid crystal display element, wherein 2 to 10 spacers are arranged at a substantially constant interval in a state of being aggregated. 5. A light-shielding film is provided on at least one of the substrates so as to surround pixels, and the light-shielding film is arranged in a state where the spacers are aggregated at a portion where the light-shielding film crosses in a T shape or a cross shape. Item 6. A liquid crystal display device according to item 4.