JP2004145084A - Liquid crystal panel and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal panel of which the manufacturing cost is prevented from increasing and in which a large fluctuation in the interval between substrates (cell gap) is prevented against external pressure, the occurrence of of interference fringes, a fluctuation in a color tone and a fluctuation in driving voltage characteristics are avoided and to provide its manufacturing method. <P>SOLUTION: A spacer 26 is formed on one substrate 20 using a photoresist. The spacer 26 has a circular cross section and a depression 26a at its top part. The depth of the depression 26a is specified to be ≤ 50% of the height of the spacer 26 and the length from the edge of the depression 26a to the outer periphery of the spacer 26 is specified to be 10 to 30% of the diameter of the spacer 26. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal panel configured by sealing liquid crystal between a pair of substrates and a method of manufacturing the same, and more particularly to a liquid crystal panel in which a distance between a pair of substrates is kept constant by columnar spacers and a method of manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art Liquid crystal panels have advantages of being thin, lightweight, and having low power consumption, and are used for displays such as calculators, household appliances, and office automation (OA) equipment. Further, the liquid crystal panel is also used as an input device of an optical information processing system and a computer generated hologram as a spatial light modulator (Spatial Light Modulator).
[0003]
A liquid crystal panel used for a display of OA equipment usually has a structure in which liquid crystal is sealed between a pair of substrates. On one substrate, a thin film transistor (TFT) and a pixel electrode are formed for each pixel, and on the other substrate, a common electrode common to each pixel is formed. Hereinafter, the substrate provided with the pixel electrodes and the TFTs is referred to as a TFT substrate, and the substrate disposed to face the TFT substrate is referred to as a counter substrate.
[0004]
The distance (cell gap) between the TFT substrate and the counter substrate is usually kept constant by spherical beads made of resin or ceramic. These beads are scattered on one of the TFT substrate and the opposing substrate when the TFT substrate and the opposing substrate are joined with a sealant.
[0005]
However, in the method of scattering beads on a substrate, beads are not always uniformly distributed over the entire substrate. If the beads are not uniformly distributed over the entire substrate, in-plane variations of the cell gap occur, which causes a reduction in display quality. In addition, since liquid crystal molecules have a property of being aligned along the surface of the beads, if beads exist in the pixel region, an alignment abnormality occurs and display quality is deteriorated.
[0006]
JP-A-8-220546 (Patent Document 1), JP-A-2001-83517 (Patent Document 2), and JP-A-2001-201750 (Patent Document 3) disclose pixel regions using a photoresist. It has been proposed to form a columnar spacer between them (for example, where a data bus line and a gate bus line intersect).
[0007]
However, the spacer formed by the photoresist method has a disadvantage that the impact resistance is low because the top has a dome shape and the contact area with the substrate is small. That is, as shown in FIG. 12, when an external pressure is applied to the point A between the spacers 51 and one of the pair of substrates 50 and 60 is deformed, the cell gap around the point A greatly changes, Interference fringes occur, color tone variation, drive voltage characteristic variation, and the like.
[0008]
In order to avoid such a problem, it is conceivable that the spacer is bonded to both of the pair of substrates by applying pressure while the spacer is softened by heat, and then the spacer is cured. However, in this case, since the height of the spacer changes when it is bonded to the substrate, it is difficult to set the cell gap to a desired value.
[0009]
Japanese Patent Application Laid-Open No. 2000-155321 (Patent Document 4) discloses a method in which beads made of a material that is not deformed by heat are mixed into a photosensitive material, and a columnar spacer containing beads is formed using a film of the photosensitive material. It has been proposed to make the cell gap a predetermined value. However, according to this method, beads having a uniform particle size are expensive, but beads in the film other than a portion serving as a spacer are discarded, so that the beads are wasted and the manufacturing cost increases.
[0010]
In addition, in this method, beads are not always present in each spacer, and it is difficult to maintain a uniform cell gap over the entire panel. To reduce the proportion of spacers without beads, it is conceivable to increase the amount of beads mixed into the photosensitive material.However, the beads act as fillers, and the film of the photosensitive material has a uniform thickness. It cannot be formed, and as a result, the height of the spacer varies.
[0011]
Japanese Patent Application Laid-Open No. H8-110524 (Patent Document 5) discloses that a gap control material that is not deformed by heating and a gap control material that melts or softens by heating are sprayed on a substrate to keep a distance between a pair of substrates constant. There is disclosed a liquid crystal panel (optical switch element) joined while being joined. However, this method cannot make the distribution of the spacers uniform.
[0012]
In order to improve the impact resistance, it has been proposed to increase the effective contact area between the spacer and the substrate. For example, Japanese Patent Application Laid-Open No. 2001-33790 (Patent Document 6) describes that a recess is provided at the top of a spacer in order to increase an effective contact area between a columnar spacer and a substrate. Thereby, the effective contact area between the spacer and the substrate is increased as compared with the case where the top of the spacer is dome-shaped, and the impact resistance is improved.
[0013]
[Patent Document 1]
JP-A-8-220546 [Patent Document 2]
Japanese Patent Application Laid-Open No. 2001-83517 [Patent Document 3]
JP 2001-201750 A [Patent Document 4]
JP 2000-155321 A [Patent Document 5]
JP-A-8-110524 [Patent Document 6]
JP 2001-33790 A (FIGS. 7 and 8)
[0014]
[Problems to be solved by the invention]
However, experiments conducted by the inventors of the present application have revealed that merely providing a recess at the top of the spacer does not provide sufficient impact resistance. That is, when joining the pair of substrates with the spacer interposed therebetween, a large stress is applied to the spacer. At this time, when the cross section of the columnar spacer is rectangular as described in JP-A-2001-33790 (Patent Document 6), stress concentrates on a part of the spacer and the spacer buckles. There is.
[0015]
In view of the above, it is an object of the present invention to avoid an increase in manufacturing cost, a large fluctuation of a substrate interval (cell gap) with respect to an external pressure, a generation of interference fringes, a variation in color tone, and a variation in drive voltage characteristics. And a method of manufacturing the same.
[0016]
[Means for Solving the Problems]
The above object is achieved by providing a first substrate and a second substrate which are arranged to face each other, and a first substrate and a second substrate which are formed on the first substrate and come into contact with the second substrate. A spacer for maintaining a constant distance from the second substrate, a recess provided at the top of the spacer, and a liquid crystal sealed between the first substrate and the second substrate. Has a circular cross section, the depth of the recess is 50% or less of the height of the spacer, and the length from the edge of the recess to the outer periphery of the spacer is 10 to 30% of the diameter of the spacer. The problem is solved by a liquid crystal panel characterized by the above.
[0017]
In addition, the above-described problems are a step of preparing a first substrate and a second substrate, a step of forming a photosensitive resin film by applying a photosensitive resin on the first substrate, An exposure / development step of subjecting the film to exposure and development to form a spacer having a circular cross section and a recess at the top, and the first substrate and the second substrate sandwiching the spacer And sealing the liquid crystal in a space surrounded by the sealant, the first substrate, and the second substrate by joining the first substrate and the second substrate with a sealant. The problem is solved by a method of manufacturing a liquid crystal panel, comprising a sealing step.
[0018]
In order to improve the impact resistance of the liquid crystal panel, it is effective to increase the effective contact area between the spacer and the substrate. Therefore, in this embodiment, a depression is formed at the top of the spacer. However, for example, when the spacer has a rectangular cross section, stress is concentrated on a part of the spacer when the two substrates are joined with the spacer interposed therebetween, and the spacer may buckle.
[0019]
In the present invention, since the cross-sectional shape of the spacer is circular, the stress is dispersed without being concentrated on a part. Thereby, the impact resistance is improved as compared with the case where the cross-sectional shape is square.
[0020]
In this case, if the length from the edge of the depression to the outer periphery of the spacer is less than 10% of the diameter of the spacer, the strength of the spacer is insufficient and good impact resistance cannot be obtained. If the length from the edge of the recess to the outer periphery of the spacer exceeds 30% of the diameter of the spacer, the effect of providing the recess is small, and the effective contact area between the spacer and the substrate is reduced. Therefore, the length from the edge of the depression to the outer periphery of the spacer needs to be 10 to 30% of the diameter of the spacer.
[0021]
If the depth of the depression exceeds 50% of the height of the spacer, the strength of the spacer is insufficient. For this reason, the depth of the depression needs to be 50% or less of the height of the spacer.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0023]
(LCD panel)
FIG. 1 is a plan view showing one pixel of a liquid crystal panel according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II of FIG. This embodiment describes an example in which the present invention is applied to a transmission type liquid crystal display panel.
[0024]
As shown in FIG. 2, the liquid crystal display panel according to the present embodiment includes a TFT substrate 10 and a counter substrate 20 which are arranged to face each other, and a liquid crystal sealed between the TFT substrate 10 and the counter substrate 20. 30. Note that a polarizing plate is disposed below the TFT substrate 10 and above the opposing substrate 20, respectively. A light source (backlight) is disposed below the TFT substrate 10.
[0025]
As shown in FIGS. 1 and 2, the TFT substrate 10 includes a glass substrate 11, a gate bus line 12, a data bus line 14, a TFT 15, a pixel electrode 18, and the like formed on the glass substrate 11. The gate bus lines 12 extend in the horizontal direction, and the data bus lines 14 extend in the vertical direction. A gate insulating film 13 is formed between the gate bus line 12 and the data bus line 14, and the gate bus line 12 and the data bus line 14 are electrically separated by the gate insulating film 13. The areas defined by these gate bus lines 12 and data bus lines 14 are pixel areas. The pixel electrode 18 and the TFT 15 are formed one by one in each pixel region.
[0026]
In the present embodiment, as shown in FIG. 1, a part of the gate bus line 12 serves as a gate electrode of the TFT 15, and a source electrode 15s and a drain electrode of the TFT 15 are provided on both sides of the channel protective film 16 in the width direction. 15d are arranged. The source electrode 15s is electrically connected to the pixel electrode 18 via a contact hole 17a formed in the insulating film 17, and the drain electrode 15d is electrically connected to the data bus line 14. An alignment film 19 made of polyimide or the like is formed on the pixel electrode 18. The surface of the alignment film 19 is subjected to a rubbing process for determining the alignment direction of liquid crystal molecules when no electric field is applied.
[0027]
On the other hand, the counter substrate 20 includes a glass substrate 21, a black matrix 22, an insulating film 23, and a common electrode 24 formed on one surface side (the lower side in FIG. 2) of the glass substrate 21. The black matrix 22 is formed so as to cover a region between pixels and a TFT formation region. The insulating film 23 is formed below the glass substrate 21 so as to cover the black matrix 22. A common electrode 24 is formed below the insulating film 23, and an alignment film 25 made of polyimide or the like is formed below the common electrode 24. The surface of the alignment film 25 is also subjected to a rubbing process for determining the alignment direction of liquid crystal molecules when no electric field is applied.
[0028]
In addition, spacers 26 are formed on the opposing substrate 20 to keep the distance between the opposing substrate 20 and the TFT substrate 10 constant. The spacer 26 has a substantially cylindrical shape, and has a depression 26a at the top (the lower side in FIG. 2). As shown in FIG. 3, the depth d of the depression 26a is 50% or less of the height h of the spacer 26, and the length w (hereinafter, also referred to as the outer peripheral width) from the edge of the depression 26a to the outer periphery of the spacer 26 is The diameter is set to 10 to 30% of the diameter R of the spacer 26.
[0029]
The TFT substrate 10 and the counter substrate 20 are arranged with the surfaces on which the alignment films 19 and 25 are formed facing each other, and constitute a liquid crystal panel together with the liquid crystal 30 sealed between them.
[0030]
In the liquid crystal panel configured as described above, when displaying an image, a driving circuit (not shown) sequentially supplies a scanning signal to the gate bus lines 12 arranged in a vertical direction and displays the data on the data bus lines 14. Supply signal. The TFT 15 connected to the gate bus line 12 to which the scanning signal has been supplied is turned on, and a display signal is written to the pixel electrode 18 via the TFT 15. As a result, an electric field corresponding to the display signal is generated between the pixel electrode 18 and the common electrode 24 to change the direction of the liquid crystal molecules, and as a result, the amount of light transmitted through the pixel changes. By controlling the amount of transmitted light for each pixel, a desired image can be displayed on the liquid crystal panel.
[0031]
(Liquid crystal panel manufacturing method)
Hereinafter, a method for manufacturing a liquid crystal panel according to an embodiment of the present invention will be described.
[0032]
First, a TFT substrate 10 and a counter substrate 20 as shown in FIGS. 1 and 2 are manufactured.
[0033]
A method for manufacturing the TFT substrate 10 will be briefly described. First, a first metal film is formed on a glass substrate 11 by a PVD (Physical Vapor Deposition) method, and the first metal film is patterned by a photolithography method to form a gate bus line 12. Next, a gate insulating film 13 is formed on the entire upper surface of the glass substrate 11, and a first silicon film serving as an operation layer of the TFT 15 and a SiN film serving as a channel protection film 16 are formed thereon. After that, the SiN film is patterned by photolithography to form a channel protection film 16 in a predetermined region above the gate bus line 12.
[0034]
Next, a second silicon film in which an impurity to be an ohmic contact layer is introduced at a high concentration is formed on the entire upper surface of the glass substrate 11, and then a second metal film is formed on the second silicon film. I do. Then, the second metal film, the second silicon film, and the first silicon film are patterned by a photolithography method to determine the shape of the silicon film serving as the operation layer of the TFT 15, and to form the data bus line 14, the source electrode 15s and the drain electrode 15d are formed.
[0035]
Next, an insulating film 17 is formed on the entire upper surface of the glass substrate 11, and a contact hole 17a is formed at a predetermined position of the insulating film 17. Thereafter, a film made of a transparent conductor such as ITO (Indium-Tin Oxide) is formed on the entire upper surface of the glass substrate 11. The pixel electrode 18 electrically connected to the source electrode 15 s of the TFT 15 via the contact hole 17 a is formed by patterning the transparent conductor film. Thereafter, an alignment film 19 made of polyimide is formed on the entire upper surface of the glass substrate 11. Thus, the TFT substrate 10 is completed.
[0036]
Hereinafter, a method of manufacturing the counter substrate 20 will be briefly described. First, a metal film such as Cr is formed on a glass substrate 21, and the metal film is patterned to form a black matrix 22. After that, the insulating film 23 is formed on the glass substrate 21. In the case of manufacturing a color liquid crystal display panel, the insulating film 23 is formed of red (R), green (G), and blue (B) resins, and one of red, green, and blue is formed for each pixel. The color insulating film 23 is disposed.
[0037]
Next, a common electrode 24 is formed on the insulating film 23 using a transparent conductor such as ITO. After that, an alignment film 25 made of polyimide is formed on the common electrode 24. Thus, the counter substrate 20 is completed.
[0038]
Next, a columnar spacer 26 is formed on one of the TFT substrate 10 and the counter substrate 20. In the present embodiment, as described above, the spacer 26 is formed on the counter substrate 20 side.
[0039]
That is, as shown in FIG. 4A, a positive photoresist is applied to a thickness of about 2 μm on the counter substrate 20 by spin coating to form a resist film 35. Pre-bake for 1 minute at a temperature of ° C.
[0040]
Next, as shown in FIG. 4B, the resist film 35 is sufficiently exposed through an exposure mask 41 provided with a circular pattern that shields a portion serving as a spacer. Thereafter, as shown in FIG. 4C, the resist film 35 is exposed for a short time through an exposure mask 42 provided with a ring-shaped pattern for shielding the peripheral portion of the spacer from light. Next, when a developing process is performed, as shown in FIG. 4D, a columnar spacer 26 having a depression 26a at the top is formed. Thereafter, the surface of the counter substrate 20 is washed with pure water and then dried.
[0041]
For example, the diameter of the spacer 26 is 10 μm, and the diameter of the depression 26 a is 6 μm. In this case, the length from the edge of the recess 26a to the outer periphery of the spacer 26 (outer peripheral width) is 2 μm. The depth of the depression 26a is set to 1 μm or less. Further, the spacer 26 is formed at a position corresponding to the intersection between the gate bus line 12 and the data bus line 14. For example, the horizontal and vertical pitches of the spacer 26 are both 100 μm.
[0042]
Next, a sealant is applied to one of the TFT substrate 10 and the counter substrate 20 so as to surround the display region. However, a sealant is not applied to a portion serving as a liquid crystal injection port. Thereafter, as shown in FIG. 5, the TFT substrate 10 and the counter substrate 20 are aligned and overlapped, and are heat-treated at a curing temperature (110 to 150 ° C.) of the sealant 36 while applying pressure in a heat treatment apparatus. Then, the sealing agent 36 is cured. Thus, the distance between the TFT substrate 10 and the counter substrate 20 has a value determined by the spacer 26. Note that the sealant 36 needs to be cured at such a temperature that the effect of the rubbing treatment applied to the alignment films 19 and 25 is not lost. Hereinafter, a structure formed by laminating the TFT substrate 10 and the counter substrate 20 (a panel before liquid crystal is enclosed) is referred to as an empty panel.
[0043]
Next, the liquid crystal 30 is injected between the TFT substrate 10 and the counter substrate 20 by a vacuum injection method. That is, the container containing the liquid crystal and the empty panel are placed in a vacuum chamber, and the vacuum chamber is evacuated to a vacuum state. Thereafter, the liquid crystal injection port of the empty panel is put into the liquid crystal, and the inside of the vacuum chamber is returned to the atmospheric pressure. Then, the liquid crystal enters the empty panel due to the difference between the pressure in the internal space of the empty panel and the atmospheric pressure, and the liquid crystal fills the internal space of the panel. Thereafter, excess liquid crystal is extruded by sandwiching the panel filled with liquid crystal between the two flat plates, and the liquid crystal injection port is sealed with a sealing resin. Thus, the liquid crystal panel according to the present embodiment is completed.
[0044]
In the above embodiment, two types of exposure masks having different patterns of the light-shielding portion are used. However, if an exposure mask provided with a pattern having different light transmittances at the peripheral portion and the central portion is used, one exposure is performed. Can form a cylindrical spacer having a depression. Further, in the above embodiment, the spacer 26 is formed of a positive photoresist, but the spacer 26 may be formed of a negative photoresist.
[0045]
In the present embodiment, since the depression 26a is provided at the top of the spacer 26 that comes into contact with the TFT substrate 10, the effective contact area between the TFT substrate 10 and the spacer 26 is large. Further, since the spacer 26 is cylindrical and the depth and size of the recess 26a are set in a predetermined range, the spacer 26 is unlikely to buckle even when a large external pressure is applied. As a result, the liquid crystal panel of the present embodiment has high impact resistance against external pressure and avoids generation of interference fringes, variations in color tone, and variations in drive voltage characteristics.
[0046]
The present invention relates to a twisted nematic (TN) type liquid crystal, a super twisted nematic (STN) type liquid crystal, a nematic cholesteric phase transition type liquid crystal, a polymer dispersed type liquid crystal, a ferroelectric liquid crystal, an antiferroelectric liquid crystal, and a twist grain boundary liquid crystal. Also, the present invention can be applied to a liquid crystal panel using a smectic A-phase liquid crystal exhibiting an electroclinic effect.
[0047]
Further, in the above-described embodiment, the case where the present invention is applied to the transmissive liquid crystal panel has been described, but the application range of the present invention is not limited to the transmissive liquid crystal panel. The present invention can be applied to a reflection type liquid crystal panel and a spatial light modulator in addition to the transmission type liquid crystal panel.
[0048]
Further, the material of the photoresist constituting the spacer in the present invention is not particularly limited. For example, the spacer is formed of a photoresist containing polyimide, polyamide, polyvinyl alcohol, polyacrylamide, cyclized rubber, novolak resin, polyester, polyurethane, acrylate resin or bisphenol resin as a main component, or a photoresist made of gelatin as a photosensitive resin. can do.
[0049]
Hereinafter, the result of actually manufacturing the liquid crystal panel according to the embodiment of the present invention and examining the display quality when an external pressure is applied will be described in comparison with a comparative example.
[0050]
(Example 1)
Two glass substrates having a length of 200 mm, a width of 100 mm, and a thickness of 1.1 mm were prepared. Then, an ITO film was formed on one surface of each of these glass substrates to form a transparent electrode.
[0051]
Next, using a spin coater, a polyimide solution having a concentration of 3 wt% is applied on the transparent electrode at a rotation speed of 2000 rpm to form a polyimide film, and the polyimide film is baked at a temperature of 200 ° C. for 30 minutes. An orientation film was obtained.
[0052]
A negative type photoresist (TLOR-N: manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied to one of the two glass substrates on which the transparent electrode and the alignment film are formed by using a spin coater, and has a thickness of 2.0 μm. A resist film was formed.
[0053]
Next, the glass substrate was placed on a hot plate, and the resist film was prebaked at a temperature of 100 ° C. for 1 minute. Thereafter, the resist film is exposed from the upper surface side of the substrate for 30 seconds using a first mask in which a ring-shaped pattern having an outer diameter of 10 μm and an inner diameter of 6 μm is formed at a pitch of 100 μm in the horizontal and vertical directions. The resist film was exposed from the back side of the substrate for 10 seconds using a second mask in which circular patterns of 10 μm were formed at a pitch of 100 μm in the horizontal and vertical directions.
[0054]
Next, the resist film was developed to form a columnar spacer having a recess at the top and having a diameter of 10 μm. The diameter of the depression is 6 μm and the depth is 1 μm. Thereafter, the surface of the glass substrate was washed with pure water, and then dried by heating at a temperature of 130 ° C. for 1 minute on a hot plate.
[0055]
Next, rubbing treatment was performed on the alignment films on the surfaces of both glass substrates. Thereafter, an epoxy resin was used as a sealant, and the sealant was applied on one glass substrate by a printing method. At this time, the sealant was applied in a frame shape along the edge of the glass substrate except for a portion serving as a liquid crystal injection port. In addition, the epoxy resin used as a sealing agent is cured at a temperature of 150 ° C. for one hour.
[0056]
Next, after bonding the pair of glass substrates so that the transparent electrodes face each other, the substrates were heated at a temperature of 150 ° C. for 1 hour to cure an epoxy resin as a sealant.
[0057]
Ferroelectric liquid crystal was injected by a vacuum injection method between a pair of substrates (empty panels) joined by the sealant in this way, and the liquid crystal injection port was sealed to obtain a ferroelectric liquid crystal display panel.
[0058]
Polarizing plates were arranged above and below the liquid crystal display panel, respectively. The polarizing plates were arranged so that the polarization axes were orthogonal (crossed Nichols).
[0059]
Thereafter, the center of the liquid crystal display panel was pressed with a pen load having a tip diameter of 0.8 mm and a pen load of 100 g. However, no change in display color was observed around the pen tip, and stress resistance was recognized against external force that reduced the cell gap.
[0060]
Further, the center of the liquid crystal display panel was supported, and a load of 300 g was applied to both ends, but no change in display color was observed over the entire screen.
[0061]
(Example 2)
A liquid crystal display panel was manufactured under the same conditions as in Example 1 except that the length (peripheral width) from the edge of the depression to the outer periphery of the spacer was 1 μm.
[0062]
As a result of testing this liquid crystal display panel in the same manner as in Example 1, it was confirmed that the liquid crystal display panel had good stress resistance as in Example 1.
[0063]
(Example 3)
A liquid crystal display panel was manufactured under the same conditions as in Example 1 except that the length (peripheral width) from the edge of the depression to the outer periphery of the spacer was 3 μm.
[0064]
As a result of testing this liquid crystal display panel in the same manner as in Example 1, it was confirmed that the liquid crystal display panel had good stress resistance as in Example 1.
[0065]
(Example 4)
A spacer was formed using a positive resist (S1818: manufactured by Shipley) and a positive exposure mask. In this case, first, the resist film other than the portion serving as the spacer was exposed from the front side of the substrate for 30 seconds, and then the portion serving as the depression from the front side of the substrate was exposed for 10 seconds. Other conditions are the same as in the first embodiment.
[0066]
The liquid crystal display panel thus manufactured was tested in the same manner as in Example 1, and as a result, it was confirmed that the liquid crystal display panel had good stress resistance as in Example 1.
[0067]
(Example 5)
As shown in FIG. 6, a liquid crystal display panel was manufactured under the same conditions as in Example 4, except that an exposure mask 43 whose light transmittance was reduced from the circular outer portion corresponding to the recess of the spacer to the center portion was used.
[0068]
As a result of testing this liquid crystal display panel in the same manner as in Example 1, it was confirmed that the liquid crystal display panel had good stress resistance as in Example 1. Further, in this case, a spacer having a depression at the top can be formed with one exposure mask, so that the manufacturing time can be reduced.
[0069]
(Example 6)
A liquid crystal display panel was manufactured under the same conditions as in Example 1 except that a twisted nematic liquid crystal was used as the liquid crystal sealed between the substrates, and the cell gap was set to 6 μm.
[0070]
As a result of testing this liquid crystal display panel in the same manner as in Example 1, it was confirmed that the liquid crystal display panel had good stress resistance characteristics as in Example 1.
[0071]
(Example 7)
A liquid crystal display panel was manufactured under the same conditions as in Example 1 except that a super twisted nematic liquid crystal was used as the liquid crystal sealed between the substrates and the cell gap was set to 6 μm.
[0072]
As a result of testing this liquid crystal display panel in the same manner as in Example 1, it was confirmed that the liquid crystal display panel had good stress resistance characteristics as in Example 1.
[0073]
(Example 8)
A liquid crystal display panel was manufactured under the same conditions as in Example 1 except that a nematic cholesteric phase transition type liquid crystal was used as the liquid crystal to be sealed between the substrates, and the cell gap was set to 6 μm.
[0074]
As a result of testing this liquid crystal display panel in the same manner as in Example 1, it was confirmed that the liquid crystal display panel had good stress resistance characteristics as in Example 1.
[0075]
(Example 9)
A liquid crystal display panel was manufactured under the same conditions as in Example 1 except that an antiferroelectric liquid crystal was used as the liquid crystal sealed between the substrates.
[0076]
As a result of testing this liquid crystal display panel in the same manner as in Example 1, it was confirmed that the liquid crystal display panel had good stress resistance characteristics as in Example 1.
[0077]
(Example 10)
A liquid crystal display panel was manufactured under the same conditions as in Example 1 except that a twist-grain boundary liquid crystal was used as the liquid crystal sealed between the substrates, and the cell gap was set to 6 μm.
[0078]
As a result of testing this liquid crystal display panel in the same manner as in Example 1, it was confirmed that the liquid crystal display panel had good stress resistance characteristics as in Example 1.
[0079]
(Example 11)
A liquid crystal display panel was manufactured under the same conditions as in Example 1 except that a smectic A-phase liquid crystal was used as the liquid crystal sealed between the substrates and the cell gap was set to 6 μm.
[0080]
As a result of testing this liquid crystal display panel in the same manner as in Example 1, it was confirmed that the liquid crystal display panel had good stress resistance characteristics as in Example 1.
[0081]
(Example 12)
A liquid crystal display panel was manufactured under the same conditions as in Example 1 except that liquid crystal was injected between the substrates by the drop injection method. That is, as shown in FIG. 7, the sealant 36 was applied on the counter substrate 20 on which the spacer was formed so as to surround the display area. Thereafter, the ferroelectric liquid crystal 30 was dropped on the counter substrate 20 by a dispenser. In this case, the amount of the liquid crystal 30 dropped was determined according to the size of the panel and the cell gap, and was dispersed and dropped on the counter substrate 20. Thereafter, a TFT substrate (not shown) was overlaid on the opposing substrate 20, and the sealant 36 was cured by heating.
[0082]
The liquid crystal display panel thus manufactured was tested by the same method as in Example 1, and as a result, it was confirmed that the liquid crystal display panel had good stress resistance characteristics as in Example 1. In the twelfth embodiment, the liquid crystal was sealed between the substrates by the drop-injection method, so that the time required for manufacturing could be greatly reduced as compared with the first embodiment.
[0083]
(Comparative Example 1)
A liquid crystal display panel was manufactured under the same conditions as in Example 1 except that no depression was formed in the spacer.
[0084]
This liquid crystal display panel was tested in the same manner as in Example 1. As a result, when the center of the panel was pressed with a pen tip having a tip diameter of 0.8 mm and a pen load of 100 g, a display defect in which a change in display color was observed around the pen tip occurred.
[0085]
(Comparative Example 2)
A liquid crystal display panel was manufactured under the same conditions as in Example 1 except that the shape of the spacer was a square column of 10 μm × 10 μm. The size of the depression is 2 μm × 2 μm, and the depth of the depression is 1 μm.
[0086]
This liquid crystal display panel was tested in the same manner as in Example 1. As a result, when the center of the panel was pressed with a pen tip having a tip diameter of 0.8 mm and a pen load of 100 g, a display defect in which a change in display color was observed around the pen tip occurred.
[0087]
(Comparative Example 3)
A liquid crystal display panel was manufactured under the same conditions as in Example 1 except that the depth of the depression was 1.1 μm (55% of the height of the spacer).
[0088]
This liquid crystal display panel was tested in the same manner as in Example 1. As a result, the strength of the spacer was low, and the spacer was deformed when the two substrates were joined, and the cell gap could not be set to a predetermined value of 2 μm. Therefore, good display quality could not be obtained.
[0089]
(Comparative Example 4)
A liquid crystal display panel was manufactured under the same conditions as in Example 1 except that the length (peripheral width) from the edge of the depression to the outer periphery of the spacer was 0.8 μm (the outer peripheral width was 8%).
[0090]
This liquid crystal display panel was tested in the same manner as in Example 1. As a result, the strength of the spacer was low, and the spacer buckled when the two substrates were joined, and the cell gap could not be set to a predetermined value of 2 μm. Therefore, good display quality could not be obtained.
[0091]
(Comparative Example 5)
The liquid crystal display panel was manufactured under the same conditions as in Example 1 except that the length (peripheral width) from the edge of the depression to the outer periphery of the spacer was 3.5 μm (the outer peripheral width was 35%) by controlling the exposure mask and the exposure conditions. Was manufactured.
[0092]
This liquid crystal display panel was tested in the same manner as in Example 1. As a result, when the center of the panel was pressed with a pen tip having a tip diameter of 0.8 mm and a pen load of 100 g, a display defect in which a change in display color was observed around the pen tip occurred.
[0093]
(Comparative Example 6)
A liquid crystal display panel was manufactured under the same conditions as in Example 1 except that a negative type photoresist which cured when heated at a temperature of 190 ° C. for 1 hour was used as a spacer material, and was cured at a temperature of 190 ° C. for 1 hour. However, heat damage occurred to the alignment film, and the display quality was degraded.
[0094]
FIG. 8 shows the results obtained by manufacturing liquid crystal panels having different lengths (perimeter width) from the edge of the depression to the outer periphery of the spacer while keeping the diameter, height, and depth of the depression constant, and examining the impact resistance. FIG. As can be seen from FIG. 8, it was confirmed that when the outer peripheral width was 10 to 30% of the diameter of the spacer, good impact resistance could be obtained.
[0095]
FIG. 9 is a diagram showing the results of examining the impact resistance by manufacturing liquid crystal panels with different depths of the depressions while keeping the diameter, outer peripheral width and height of the spacers constant. As can be seen from FIG. 9, it was confirmed that good impact resistance could be obtained when the depth of the depression was 50% or less of the height of the spacer.
[0096]
FIG. 10 is a diagram showing the results of examining the impact resistance by manufacturing liquid crystal panels with different outer diameters of the spacers while keeping the outer peripheral width, height, and depth of the recesses of the spacers constant. As can be seen from FIG. 10, even if the diameter changes, it can be confirmed that good impact resistance can be obtained if the outer peripheral width is within the range of 10 to 30% of the diameter.
[0097]
FIG. 11 is a diagram showing the results of examining the impact resistance by manufacturing liquid crystal panels having different depths of the depressions while keeping the diameter, outer peripheral width and height of the spacers constant. As can be seen from FIG. 11, even when the height of the spacer changes, it is confirmed that good impact resistance can be obtained when the depth of the recess is 50% or less of the height of the spacer.
[0098]
(Supplementary Note 1) A first substrate and a second substrate, which are arranged to face each other, and which are formed on the first substrate and contact the second substrate to form the first substrate and the second substrate. A spacer for maintaining a constant distance from the substrate, a recess provided at the top of the spacer, and a liquid crystal sealed between the first substrate and the second substrate. The cross section is circular, the depth of the depression is 50% or less of the height of the spacer, and the length from the edge of the depression to the outer periphery of the spacer is 10 to 30% of the diameter of the spacer. A liquid crystal panel characterized by the following.
[0099]
(Supplementary Note 2) The liquid crystal panel according to supplementary note 1, wherein the spacer is formed of a photoresist.
[0100]
(Supplementary Note 3) The liquid crystal panel according to Supplementary Note 1, wherein the spacers are arranged at regular intervals.
[0101]
(Supplementary Note 4) The liquid crystal is a twisted nematic liquid crystal, a super twisted nematic liquid crystal, a nematic cholesteric phase transition liquid crystal, a polymer dispersed liquid crystal, a ferroelectric liquid crystal, an antiferroelectric liquid crystal, a twist grain boundary liquid crystal, and a smectic A. 2. The liquid crystal panel according to claim 1, wherein the liquid crystal panel is any one selected from the group consisting of phase liquid crystals.
[0102]
(Supplementary Note 5) A step of preparing a first substrate and a second substrate; a step of applying a photosensitive resin on the first substrate to form a photosensitive resin film; An exposure / development step of performing exposure and development processing to form a spacer having a circular cross-sectional shape and a recess at the top, and disposing the first substrate and the second substrate with the spacer interposed therebetween. A liquid crystal encapsulating step of joining the first substrate and the second substrate with a sealing agent, and enclosing a liquid crystal in a space surrounded by the sealing agent, the first substrate, and the second substrate; A method for manufacturing a liquid crystal panel, comprising:
[0103]
(Supplementary note 6) The method for producing a liquid crystal panel according to supplementary note 5, wherein a negative photoresist is used as the photosensitive resin.
[0104]
(Supplementary Note 7) In the exposing / developing step, the photosensitive resin film is exposed from above the first substrate through a first exposure mask having a ring-shaped pattern corresponding to the spacer. 7. The method for manufacturing a liquid crystal panel according to claim 6, wherein the photosensitive resin film is exposed from a back side of the substrate through a second exposure mask having a circular pattern corresponding to the spacer.
[0105]
(Supplementary Note 8) In the exposure / development step, an exposure mask having a size corresponding to the spacer and provided with a circular pattern having a lower light transmittance at a central portion than at a peripheral portion is used. 7. The method for manufacturing a liquid crystal panel according to supplementary note 6, wherein
[0106]
(Supplementary note 9) The method for producing a liquid crystal panel according to supplementary note 5, wherein a positive photoresist is used as the photosensitive resin.
[0107]
(Supplementary Note 10) In the exposing / developing step, a first exposing step of exposing a portion of the photosensitive resin film other than the portion serving as the spacer through a first exposing mask; And a second exposure step of exposing a portion of the photosensitive resin film corresponding to the depression with a lower energy than the first exposure step. Production method.
[0108]
(Supplementary Note 11) In the exposure / development step, an exposure mask having a size corresponding to the spacer and provided with a circular pattern having a higher light transmittance in a central portion than in a peripheral portion is used. 10. The method for manufacturing a liquid crystal panel according to supplementary note 9, wherein
[0109]
(Supplementary Note 12) The method for manufacturing a liquid crystal panel according to Supplementary Note 5, wherein the liquid crystal sealing step is performed by a vacuum injection method.
[0110]
(Supplementary Note 13) The method for manufacturing a liquid crystal panel according to Supplementary Note 5, wherein the liquid crystal sealing step is performed by a drop injection method.
[0111]
(Supplementary Note 14) As the liquid crystal, a twisted nematic liquid crystal, a super twisted nematic liquid crystal, a nematic cholesteric phase transition type liquid crystal, a polymer dispersed liquid crystal, a ferroelectric liquid crystal, an antiferroelectric liquid crystal, a twist grain boundary liquid crystal, and a smectic A 6. The method for manufacturing a liquid crystal panel according to supplementary note 5, wherein any one selected from the group consisting of phase liquid crystals is used.
[0112]
【The invention's effect】
As described above, according to the present invention, the cross-sectional shape of the spacer is circular, the depth of the top recess is 50% or less of the height of the spacer, and the length from the edge of the recess to the outer periphery of the spacer is the spacer. 10 to 30% of the diameter of the substrate, the impact resistance is high, the fluctuation of the substrate interval (cell gap) with respect to the external pressure is avoided, and the occurrence of interference fringes, the variation of color tone, and the variation of the driving voltage characteristic are avoided. You.
[0113]
Further, according to the method of the present invention, a liquid crystal panel having high impact resistance can be manufactured by a relatively simple process. Thereby, the manufacturing cost of the liquid crystal panel is reduced.
[Brief description of the drawings]
FIG. 1 is a plan view showing one pixel of a liquid crystal panel according to an embodiment of the present invention.
FIG. 2 is a sectional view taken along line II of FIG. 1;
FIG. 3 is a schematic diagram showing the size of each part of a spacer.
FIGS. 4A to 4D are schematic diagrams illustrating a method of forming a spacer.
FIG. 5 is a schematic view showing a step of joining a TFT substrate and a counter substrate.
FIG. 6 is a schematic view showing an example of an exposure mask.
FIG. 7 is a schematic diagram showing a drop injection method.
FIG. 8 is a diagram showing a method for manufacturing a liquid crystal panel in which the length (outer width) from the edge of the recess to the outer periphery of the spacer is different while the diameter, height, and depth of the recess are constant; It is a figure which shows the result of having investigated.
FIG. 9 is a diagram showing the results of examining the impact resistance of a liquid crystal panel having different diameters, outer peripheral widths, and heights of the spacers and different recess depths.
FIG. 10 is a diagram showing results of examining impact resistance by manufacturing liquid crystal panels having different spacer diameters while keeping the outer peripheral width, height, and recess depth of the spacers constant.
FIG. 11 is a diagram showing a result of examining impact resistance by manufacturing liquid crystal panels having different diameters, outer peripheral widths, and heights of the spacers and different recess depths.
FIG. 12 is a schematic diagram showing a change in a cell gap when an external pressure is applied to a conventional liquid crystal panel.
[Explanation of symbols]
10 ... TFT substrate,
11, 21 ... glass substrate,
12 ... Gate bus line,
13 ... gate insulating film,
14 ... data bus line,
15 ... TFT,
16: channel protective film,
17, 23 ... insulating film,
18 ... pixel electrodes 19, 25 ... alignment film,
20: counter substrate,
22 Black matrix,
24 ... Common electrode,
26, 51 ... spacer,
26a ... hollow,
30 ... liquid crystal,
35 ... resist film,
36 ... Sealant 41, 42, 43 ... Exposure mask,
50, 60 ... substrate.

Claims (10)

A first substrate and a second substrate arranged to face each other;
A spacer formed on the first substrate and in contact with the second substrate to maintain a constant distance between the first substrate and the second substrate;
A depression provided at the top of the spacer,
Liquid crystal sealed between the first substrate and the second substrate,
The cross section of the spacer is circular, the depth of the depression is 50% or less of the height of the spacer, and the length from the edge of the depression to the outer periphery of the spacer is 10 to 30% of the diameter of the spacer. A liquid crystal panel characterized by the following. The liquid crystal panel according to claim 1, wherein the spacer is formed of a photoresist. 2. The liquid crystal panel according to claim 1, wherein the spacers are arranged at regular intervals. The liquid crystal comprises a twisted nematic liquid crystal, a super twisted nematic liquid crystal, a nematic cholesteric phase transition liquid crystal, a polymer dispersed liquid crystal, a ferroelectric liquid crystal, an antiferroelectric liquid crystal, a twist grain boundary liquid crystal, and a smectic A phase liquid crystal. 2. The liquid crystal panel according to claim 1, wherein the liquid crystal panel is any one selected from a group. Providing a first substrate and a second substrate;
Forming a photosensitive resin film by applying a photosensitive resin on the first substrate;
An exposure / development step of subjecting the photosensitive resin film to exposure and development to form a spacer having a circular cross section and a depression at the top;
The first substrate and the second substrate are arranged with the spacer interposed therebetween, and the first substrate and the second substrate are joined by a sealant, and the sealant, the first substrate, A liquid crystal sealing step of sealing liquid crystal in a space surrounded by the second substrate. The method according to claim 5, wherein a negative photoresist is used as the photosensitive resin. In the exposing / developing step, the photosensitive resin film is exposed from above the first substrate through a first exposure mask having a ring-shaped pattern corresponding to the spacer, and thereafter, a back surface of the first substrate is exposed. The method according to claim 6, wherein the photosensitive resin film is exposed from a side through a second exposure mask having a circular pattern corresponding to the spacer. 6. The method according to claim 5, wherein a positive photoresist is used as the photosensitive resin. In the exposing / developing step, a first exposing step of exposing a portion of the photosensitive resin film other than the portion serving as the spacer through a first exposing mask; 9. The method according to claim 8, further comprising: exposing a portion of the conductive resin film corresponding to the depression with lower energy than the first exposure step. 10. The liquid crystal includes a twisted nematic liquid crystal, a super twisted nematic liquid crystal, a nematic cholesteric phase transition liquid crystal, a polymer dispersed liquid crystal, a ferroelectric liquid crystal, an antiferroelectric liquid crystal, a twist grain boundary liquid crystal, and a smectic A phase liquid crystal. The method according to claim 5, wherein any one selected from the group is used.

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