JP3847418B2 - Liquid crystal display panel manufacturing method and liquid crystal display panel - Google Patents

Description

【００４６】
この表１から明らかなように、比較例の場合、紫外線の照射によりイオン密度が大きく上昇し、電圧保持率が２．４％も低下した。電圧保持率が低下するとアクティブマトリクス駆動の液晶表示パネルでは次のデータ書き込み時間までの間に電圧が保持されずにリークしてしまい、表示むら（色抜け）が発生してしまうという不具合が発生する。一方、実施例１〜４の液晶表示パネルでは、電圧保持率の低下が０．３〜０．７％と小さく、液晶の光劣化が抑えられることがわかる。
【００４７】
（液晶表示パネルの点灯試験）
次に、滴下注入法により液晶表示パネルを形成し、長時間点灯したときの表示むらの有無を調べた。
すなわち、上述の電気特性の評価において使用した配向膜及び液晶を用いて滴下注入プロセスにより液晶表示パネルを製造した。ＴＦＴ基板及びＣＦ基板の表示領域には水平配向膜を塗布し、シール材を塗布する領域と表示領域との間には垂直配向膜を塗布して熱硬化を行った。
【００４８】
ＴＦＴ基板及びＣＦ基板の各配向膜をツイスト角が９０°となるようにラビングした後、一方の基板に紫外線硬化性樹脂（エポキシアクリレート樹脂：協立化学製）を枠状に塗布した。そして、２枚の基板を貼合わせたときに液晶が均等に拡散するように、一方の基板の表示領域上に液晶を多点滴下した。また、他方の基板にはギャップ材（接着スペーサ５μｍ：早川ゴム製）を散布した。その後、両基板を貼合わせ機にセットして、真空中にて貼り合わせを行った。
【００４９】
次いで、表示領域の縁部の近傍の画素電極と対向電極との間に交流電圧（ｆ＝３０ｋＨｚ，Ｖ＝１０Ｖ）を印加しつつ、シール材に紫外線を照射して硬化させた。これにより、図１０に示す液晶表示パネルが完成した。この図１０において、ハッチングで示す領域が表示領域である。この表示領域には水平配向膜が形成されており、表示領域の外側には垂直配向膜１３ｂ，２３ｂが形成されている。また、図中一点鎖線で示す位置よりも外側の画素電極と対向基板との間に電圧を印加した。なお、符号１５は、バスラインに接続された複数の端子が配列された端子領域であり、各端子には、駆動回路基板から駆動用電圧が供給される。
【００５０】
このようにして製造した液晶表示パネルをユニット化し、環境試験機を用いて５０℃の条件下で駆動試験を行った。その結果、５００時間経過した後でも樹脂部近傍で表示むらは発生しなかった。
一方、紫外線照射時に電圧を印加しないこと以外は上記と同様にして液晶表示パネルを形成した。そして、環境試験機を用いて、上記と同様の条件で駆動試験を行った。その結果、点灯初期からシール部近傍に電圧保持率低下による表示むらが発生し、時間の経過とともにその領域が広がっていった。このことから、本願発明が液晶表示パネルの信頼性の向上に極めて有用であることがわかる。
【００５１】
【発明の効果】
以上説明したように、本発明によれば、シール材又は封止材の硬化時や表示むらを防止するための紫外線照射時に、液晶分子のダイレクタ方向を紫外線の伝播方向に向け、又は偏光子を介して液晶分子の方位に対し垂直な方向の偏光成分のみの紫外線を照射するので、液晶の紫外線による劣化が抑制される。これにより、紫外線を用いたシール材又は封止材の硬化や、滴下注入プロセスでのシール硬化が信頼性よく行えるようになり、液晶表示パネルの製造歩留まりや生産性が大きく向上する。また、表示むらを防止するためにパネル全面に紫外線を照射する場合も、液晶の劣化が回避される。
【図面の簡単な説明】
【図１】液晶表示パネルの基板表面の液晶分子を示す模式図である。
【図２】本発明の第１の実施の形態の液晶表示パネルの製造方法を示す模式図（その１）である。
【図３】本発明の第１の実施の形態の液晶表示パネルの製造方法を示す模式図（その２）である。
【図４】本発明の第２の実施の形態の液晶表示パネルの製造方法を示す模式図である。
【図５】本発明の第３の実施の形態の液晶表示パネルの製造方法を示す模式図（その１）である。
【図６】本発明の第３の実施の形態の液晶表示パネルの製造方法を示す模式図（その２）である。
【図７】本発明の第４の実施の形態の液晶表示パネルの製造方法を示す模式図（その１）である。
【図８】本発明の第４の実施の形態の液晶表示パネルの製造方法を示す模式図（その２）である。
【図９】本発明の第５の実施の形態の液晶表示パネルの製造方法を示す模式図である。
【図１０】点灯試験に使用した液晶表示パネルを示す模式図である。
【図１１】従来の問題点を示す模式図である。
【符号の説明】
２ 液晶分子
３ 封止材
４ シール材
１１，２１ 基板
１２ 画素電極
１３，１３ａ，１３ｂ，２３，２３ａ，２３ｂ 配向膜
２２ 対向電極
３１ 遮光板
３２ 偏光子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a liquid crystal display panel that uses ultraviolet rays for curing a sealing material or a sealing material and preventing display unevenness.
[0002]
[Prior art]
Liquid crystal display devices have the advantages of being thin and lightweight, being able to be driven at a low voltage and consuming little power, and in recent years have come to be widely used in personal computer displays and televisions.
In general, a display panel constituting a liquid crystal display device has a structure in which liquid crystal is sealed between two transparent glass substrates. A black matrix, a color filter, a counter electrode, an alignment film, and the like are formed on one surface side of the two surfaces (facing surfaces) facing each other of the glass substrates, and TFTs, A pixel electrode, an alignment film, and the like are formed. Furthermore, a polarizing plate is attached to the surface opposite to the facing surface of each glass substrate. These two polarizing plates are, for example, arranged so that the polarizing axes of the polarizing plates are orthogonal to each other, and according to this, a mode that transmits light when no electric field is applied and shields light when an electric field is applied, That is, the normally white mode is set. When the polarization axes of the two polarizing plates are parallel, the light is blocked when no electric field is applied, and the mode is a normally black mode in which light is transmitted when an electric field is applied.
[0003]
In the following description, of the two substrates constituting the liquid crystal display panel, a substrate on which a TFT or the like is formed is referred to as a TFT substrate, and a substrate on which a color filter or the like is formed is referred to as a CF substrate.
Hereinafter, a method called a dip injection method will be described as an example of a method for manufacturing a liquid crystal display panel.
[0004]
First, a black matrix, a color filter, a counter electrode, an alignment film, and the like are formed on a first transparent substrate to form a CF substrate, and a TFT, a pixel electrode, an alignment film, and the like are formed on a second transparent substrate. And Thereafter, a sealing material (ultraviolet curable resin) is applied in a substantially frame shape so as to surround the display region (the region where the pixel electrode or the color filter is formed) on either the TFT substrate or the CF substrate. At this time, a sealing material is not applied to a portion which becomes a liquid crystal injection port for injecting liquid crystal between the panels in a later process. Thereafter, the TFT substrate and the CF substrate are overlapped with a spacer for maintaining a constant interval between the substrates, and the TFT substrate and the CF substrate are temporarily bonded with a sealing material.
[0005]
Next, a light shielding plate that covers the display area is disposed on one substrate, and then the sealing material is cured by irradiating ultraviolet rays from the side where the light shielding plate is disposed.
Next, after sufficiently exhausting the space between the substrates by a vacuum device, the liquid crystal injection port is immersed in the liquid crystal to return to atmospheric pressure, and the liquid crystal is injected between the substrates by the pressure difference.
Next, the liquid crystal inlet is filled with a sealing material (ultraviolet curable resin), the display area is covered with a light shielding plate, and ultraviolet rays are irradiated to cure the sealing material. Thereby, a liquid crystal display panel is completed.
[0006]
As another method for manufacturing a liquid crystal display panel, there is a method called a dropping injection method. In this method, first, a sealing material is applied outside the display area of one of the TFT substrate and the CF substrate so as to completely surround the display area. Then, liquid crystal is dropped on the substrate, and the other substrate is overlapped with a spacer interposed therebetween. After that, a light shielding plate that covers the display region is disposed on the substrate, and the sealing material is cured by irradiating ultraviolet rays. Thereby, a liquid crystal display panel is completed.
[0007]
By the way, if impurity ions are contained in the liquid crystal sealed in the liquid crystal display panel, the electric field retention ratio is greatly reduced, display unevenness such as color loss occurs, and display quality deteriorates. In order to avoid such problems, conventionally, a pair of ion trap electrodes is provided in the vicinity of the liquid crystal injection port, and when the liquid crystal is injected, an AC voltage having a DC offset component is applied between the electrodes to apply the ion trap electrode. It has been proposed to adsorb impurity ions (Japanese Patent Laid-Open No. 6-331995). It has also been proposed to form an alignment film having higher ion adsorption capacity than the alignment film on the pixel electrode around the pixel electrode, and to adsorb impurity ions with this alignment film (Japanese Patent Laid-Open No. 7-110479). ).
[0008]
[Problems to be solved by the invention]
However, even if impurity ions in the liquid crystal are adsorbed to the ion trap electrode at the time of liquid crystal injection, when the voltage application is stopped thereafter, the ions adsorbed to the ion trap electrode are dissociated again and diffused into the liquid crystal due to thermal motion, It causes uneven display. Further, as shown in FIG. 11, when ultraviolet rays are irradiated to cure the ultraviolet curable resin 33, ultraviolet rays enter the liquid crystal from the edge of the light shielding plate 31, and liquid crystal molecules are decomposed to generate ions. As a result, there is a problem that display quality is deteriorated. Even in the method of adsorbing impurity ions with an alignment film having a high ion adsorbing ability, it cannot be avoided that liquid crystal molecules are decomposed when the ultraviolet curable resin is cured.
[0009]
Furthermore, in recent years, it has been proposed to irradiate the entire surface of the liquid crystal display panel with ultraviolet rays in order to suppress uneven display contrast (Japanese Patent Laid-Open No. 7-152034). In this case, the decomposition of the liquid crystal molecules by ultraviolet rays cannot be prevented.
The objective of this invention is providing the manufacturing method of the liquid crystal display panel which can suppress decomposition | disassembly of a liquid crystal molecule, when irradiating an ultraviolet-ray for hardening of an ultraviolet curable resin, and suppression of display nonuniformity.
[0010]
[Means for Solving the Problems]
  The above issues areLiquid crystal is sealed between a pair of substrates, a sealing material made of a photocurable resin is applied to the outside of the display area, and the director direction of the liquid crystal molecules in the vicinity of the sealing material is made parallel to the light propagation direction and irradiated with light. , Cure the sealing materialThis is solved by a method for manufacturing a liquid crystal display panel.
[0011]
  As a means for making the director direction of the liquid crystal molecules parallel to the light propagation direction, a vertical alignment film may be formed in the vicinity of the sealing material.
[0012]
  As a means for making the director direction of the liquid crystal molecules parallel to the light propagation direction, an electric field may be generated in a direction perpendicular to the substrate surface.
[0013]
  The above issues areLiquid crystal is sealed between a pair of substrates, a sealing material made of a photocurable resin is applied to the outside of the display area, the director direction of the liquid crystal molecules in the vicinity of the sealing material is aligned, and the amplitude surface is relative to the director direction of the liquid crystal molecules. Irradiating perpendicular light to cure the sealing materialThis is solved by a method for manufacturing a liquid crystal display panel.
[0014]
  As a means for aligning the director direction of the liquid crystal molecules, an electric field may be generated in a direction parallel or oblique to the substrate surface.
[0015]
  The above issues areA liquid crystal display panel in which liquid crystal is sealed by a dropping injection method between a pair of substrates, wherein the sealing material is manufactured by being cured by the above method.To solve.
[0016]
The operation of the present invention will be described below.
FIG. 1 is a schematic diagram showing liquid crystal molecules on the substrate surface of a liquid crystal display panel. The liquid crystal molecules are rod-like molecules having many unsaturated bonds in the structure, rise at an angle determined by an alignment film (not shown) on the surface of the substrate, and are aligned in a certain direction. The major axis direction n of the liquid crystal molecules is referred to as the director direction, the rising angle ψ of the liquid crystal molecules is referred to as the tilt angle, and the angle Φ between the projection line of the major axis of the liquid crystal molecules onto the substrate surface and the x-axis direction of the substrate is referred to as the azimuth angle.
[0017]
  When the director direction of the liquid crystal molecules in the liquid crystal is not uniform, or when the liquid crystal molecules are aligned in a twisted state so that the azimuth angle gradually changes from one substrate side to the other substrate side, the absorption of ultraviolet rays is large. In particular, a liquid crystal having a highly reactive atomic group (> C═O or the like) is more activated by ultraviolet rays and generates many ions. On the other hand, when the director direction of the liquid crystal molecules coincides with the light propagation direction, the light absorption is remarkably reduced as compared with the case where the director direction of the liquid crystal molecules is perpendicular to the ultraviolet light propagation direction. Therefore,Invention of the present applicationThen, the director direction of the liquid crystal molecules is made substantially the same as the light propagation direction by applying a vertical alignment film or voltage. For example, in the case of a TN (twisted nematic) liquid crystal display panel, liquid crystal molecules between substrates are aligned in a direction perpendicular to the substrate surface by forming a vertical alignment film outside the display region. Therefore, even when ultraviolet rays enter the liquid crystal from the edge of the light shielding film when the sealing material or the sealing material is cured, decomposition of the liquid crystal molecules by the ultraviolet rays is suppressed. In addition, when an electric field is applied in a direction perpendicular to the substrate surface so that the director direction of the liquid crystal molecules is aligned in a direction perpendicular to the substrate surface, the liquid crystal molecules The absorption of ultraviolet rays by the liquid crystal is suppressed, and the decomposition of the liquid crystal molecules is suppressed.
[0018]
In the case of a so-called narrow frame liquid crystal display panel in which the distance between the display area and the panel edge is narrow, the distance between the sealing material or the sealing material and the display area is narrow, and the liquid crystal in the display area is caused by ultraviolet light entering from the edge of the light shielding plate. May break down. However, by applying a voltage in a direction perpendicular to the substrate surface during ultraviolet irradiation as described above, deterioration of liquid crystal molecules during curing of the sealing material is avoided.
[0019]
  Also, the liquid crystal has birefringence due to its molecular structure, and when the director direction of the liquid crystal molecules is the same and is horizontal or tilted with respect to the substrate surface, the incident light amplitude plane and the azimuth angle of the liquid crystal molecules If the angle formed between and is perpendicular, the collision ratio between the liquid crystal molecules and the light is minimized, and when the angle is parallel, it is maximized. Therefore, this applicationOther inventionsThen, an ultraviolet-ray is irradiated to a liquid crystal panel through a polarizer. In this case, the director directions of the liquid crystal molecules are aligned, and the polarizer is arranged so that the azimuth angle of the liquid crystal molecules and the light amplitude plane are perpendicular to each other. Thereby, the absorption of the ultraviolet rays of the liquid crystal molecules is greatly reduced, and the deterioration of the liquid crystal molecules in the curing step of the sealing material or the sealing material or the ultraviolet irradiation step for preventing display unevenness is prevented.
[0020]
In order to align the director direction of the liquid crystal molecules horizontally with the substrate surface, for example, in a TN liquid crystal display panel, an alternating voltage is applied between adjacent pixel electrodes (drive electrodes) on the TFT substrate to generate a lateral electric field. Let Thereby, the director direction of the liquid crystal can be aligned horizontally and in the same direction on the substrate surface. In the case of an IPS (in-plane switching) type liquid crystal display panel in which both a drive electrode and a counter electrode are formed on one of a pair of substrates, a voltage is applied to the drive electrode and the counter electrode during ultraviolet irradiation. By applying, the director direction of the liquid crystal molecules can be aligned in the horizontal direction with respect to the substrate surface.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
(First embodiment)
2 and 3 are schematic views showing a method of manufacturing the liquid crystal display panel according to the first embodiment of the present invention. This embodiment is an example of manufacturing a TN liquid crystal display panel by a dip injection method.
[0022]
First, a pixel electrode 12 made of ITO (indium tin oxide), a TFT (not shown), and a bus line (not shown) are formed in a display region on the transparent substrate 11 serving as a TFT substrate. A horizontal alignment film 13a is formed so as to cover the TFT. In addition, the vertical alignment film 13 b is formed outside the display area on the substrate 11. Thereafter, the surfaces of the alignment films 13a and 13b are rubbed.
[0023]
On the other hand, a color filter (not shown) and a black matrix (not shown) for shielding light between pixels are formed in the display area of the transparent substrate 21 serving as a CF substrate, and a counter electrode 22 made of ITO is formed thereon. . Then, a horizontal alignment film 23a is formed on the display area of the transparent substrate 21, and a vertical alignment film 23b is formed outside the display area. Thereafter, the surfaces of the alignment films 23a and 23b are rubbed.
[0024]
Next, the alignment film forming surfaces of the substrates 11 and 21 are opposed to each other, spacers (not shown) are scattered between the substrates 11 and 21, and bonded with a sealing material (ultraviolet curable resin) to form a panel. .
Next, liquid crystal is injected between the substrates 11 and 21, and a sealing material (ultraviolet curable resin) 3 is filled in the liquid crystal injection port. Thereafter, a light shielding plate 31 covering the display area is overlaid on the substrate 21, and the sealing material 3 is cured by irradiating ultraviolet rays from the substrate 21 side. Thereby, a liquid crystal display panel is completed.
[0025]
In this case, in this embodiment, since the vertical alignment films 13b and 23b are formed outside the display region, as shown in FIGS. 2 and 3, the liquid crystal molecules 2 outside the display region are the substrate 11, 21 are arranged in a vertical direction. The ultraviolet rays propagate in the direction of the director of the liquid crystal molecules 2.
In this way, when the director direction of the liquid crystal molecules 2 is aligned with the propagation direction of the ultraviolet rays, the ultraviolet absorption rate in the liquid crystal molecules 2 becomes extremely small. Thereby, the amount of ultraviolet rays absorbed by the liquid crystal molecules 2 is significantly reduced, and the deterioration of the liquid crystal molecules 2 is avoided. Although the director direction of the liquid crystal molecules 2 in the display area is not perpendicular to the substrate surface, the display area is covered with the light-shielding plate 31, so that the deterioration of the liquid crystal molecules 2 in the display area is also avoided.
[0026]
(Second Embodiment)
FIG. 4 is a schematic view showing a method for manufacturing a liquid crystal display panel according to the second embodiment of the present invention. Note that this embodiment is an example of a manufacturing method suitable for manufacturing a so-called narrow frame liquid crystal display panel in which the distance between the display region and the panel edge is short.
First, a pixel electrode 12 and a TFT (not shown) are formed in a display area on the transparent substrate 11 serving as a TFT substrate, and a horizontal alignment film 13 is formed so as to cover the pixel electrode 12 and the TFT. Thereafter, the surface of the alignment film 13 is rubbed.
[0027]
On the other hand, a color filter (not shown) and a black matrix (not shown) are formed in the display area of the transparent substrate 21 serving as a CF substrate, and a counter electrode 22 is formed thereon. Then, a horizontal alignment film 23 is formed on the counter electrode 22 and the surface of the alignment film 23 is rubbed.
Next, a sealing material (ultraviolet curable resin) 4 is applied on the substrate 11 so as to surround the display area. Moreover, after dripping a liquid crystal on the board | substrate 11, the board | substrates 11 and 21 are bonded together on both sides of a spacer. Thereafter, the light shielding plate 31 covering the display area is overlaid on the substrate 21, and the sealing material 4 is cured by irradiating the substrate 21 with ultraviolet rays while applying an AC voltage between the pixel electrode 12 and the counter electrode 22. . Thereby, a liquid crystal display panel is completed.
[0028]
In this case, in the present embodiment, since a voltage is applied between the pixel electrode 12 and the counter electrode 22 when irradiating ultraviolet rays, the liquid crystal molecules 2 are in a direction perpendicular to the substrate surface along the electric field, that is, Arrange in the direction of light propagation. Thereby, as in the first embodiment, the ultraviolet absorptance in the liquid crystal molecules 2 becomes extremely small, and deterioration of the liquid crystal molecules 2 is avoided.
[0029]
In this embodiment, since the liquid crystal molecules in the entire display region are arranged in the light propagation direction, deterioration of the liquid crystal molecules is avoided even when the entire panel is irradiated with ultraviolet rays in order to make the display unevenness uniform. . In this case, the vertical alignment film is formed outside the display region as in the first embodiment, so that the deterioration of the liquid crystal due to the ultraviolet rays at the panel edge can be prevented.
[0030]
(Third embodiment)
5 and 6 are schematic views showing a method of manufacturing a liquid crystal display panel according to the third embodiment of the present invention.
First, a pixel electrode 12 and a TFT (not shown) are formed in a display area on the transparent substrate 11 serving as a TFT substrate, and a horizontal alignment film 13 is formed so as to cover the pixel electrode 12 and the TFT. Thereafter, the surface of the alignment film 13 is rubbed.
[0031]
On the other hand, a color filter (not shown) and a black matrix (not shown) are formed in the display area of the transparent substrate 21 serving as a CF substrate, and a counter electrode 22 is formed thereon. Then, a horizontal alignment film 23 is formed on the counter electrode 22 and the surface of the alignment film 23 is rubbed.
And each alignment film formation surface side of the board | substrates 11 and 21 is made to oppose, a spacer (not shown) is sprayed between board | substrates 11 and 21, and both are joined by a sealing material (ultraviolet curable resin), and a panel is attached. To do. At this time, a liquid crystal injection port for injecting liquid crystal between the substrates 11 and 21 is formed in a later step.
[0032]
Next, liquid crystal is injected between the substrates 11 and 21, and a sealing material (ultraviolet curable resin) 3 is filled in the liquid crystal injection port. Thereafter, a light shielding plate 31 covering the display area is overlaid on the substrate 21, a polarizer 32 is disposed between the substrate 21 and the light source, and then the sealing material 3 is cured by irradiating ultraviolet rays. At this time, as shown in FIG. 6, the polarizer 32 is arranged between the ultraviolet light source and the light shielding plate 31 so that the amplitude plane of the light passing through the polarizer 32 is perpendicular to the azimuth angle of the liquid crystal 2. . Thus, a liquid crystal display panel is manufactured.
[0033]
In the TN liquid crystal display panel, the liquid crystal molecules 2 in the vicinity of the alignment films 13 and 23 are aligned in a direction determined by the alignment films 13 and 23 while being tilted at a certain angle. In the present embodiment, the polarizer 32 is used to enter only a linearly polarized light component whose ultraviolet amplitude plane is perpendicular to the azimuth angle of the liquid crystal molecules, and similarly to the first and second embodiments. The effect that the deterioration of liquid crystal molecules due to ultraviolet rays is prevented can be obtained.
[0034]
(Fourth embodiment)
7 and 8 are schematic views showing a method of manufacturing a liquid crystal display panel according to the fourth embodiment of the present invention.
First, a pixel electrode 12 and a TFT (not shown) are formed in a display area on the transparent substrate 11 serving as a TFT substrate, and a horizontal alignment film 13 is formed so as to cover the pixel electrode 12 and the TFT. Thereafter, the surface of the alignment film 13 is rubbed.
[0035]
On the other hand, a color filter (not shown) and a black matrix (not shown) are formed in the display area of the transparent substrate 21 serving as a CF substrate, and a counter electrode 22 is formed thereon. Then, a horizontal alignment film 23 is formed on the counter electrode 22 and the surface of the alignment film 23 is rubbed.
Next, the alignment film forming surfaces of the substrates 11 and 21 are opposed to each other, spacers (not shown) are scattered between the substrates 11 and 21, and both are bonded by a sealing material (ultraviolet curable resin). At this time, a liquid crystal injection port for injecting liquid crystal between the substrates 11 and 21 is formed in a later step.
[0036]
Next, liquid crystal is injected between the substrates 11 and 21, and a sealing material (ultraviolet curable resin) 3 is filled in the liquid crystal injection port. Thereafter, a light shielding plate 31 covering the display area is overlaid on the substrate 21, and a polarizer 32 is disposed between the substrate 21 and the light source. At this time, the amplitude plane of the light passing through the polarizer 32 is set to be perpendicular to the azimuth angle of the liquid crystal molecules 2. Then, as shown in FIG. 7, an alternating voltage is applied between adjacent pixel electrodes 12. By applying this voltage, a horizontal electric field is generated between adjacent pixel electrodes 12 with respect to the substrate surface, and the director direction of the liquid crystal molecules 2 is aligned in one direction parallel to the substrate surface as shown in FIG. In this way, after aligning the director direction of the liquid crystal molecules 2 in one direction, the sealing material 3 is cured by irradiating with ultraviolet rays. Thereby, a liquid crystal display panel is completed.
[0037]
Also in this embodiment, the same effect as the third embodiment can be obtained.
In the above example, the manufacturing method of the TN liquid crystal display panel has been described. However, in the IPS liquid crystal display panel, the drive electrode and the counter electrode are formed on the same substrate. By applying a voltage therebetween, the liquid crystal molecules are aligned in one direction horizontal to the substrate surface. In the IPS liquid crystal display panel, the same effect as in the above example can be obtained by irradiating ultraviolet rays while applying a voltage between the drive electrode and the counter electrode.
[0038]
(Fifth embodiment)
FIG. 9 is a schematic view showing a method for manufacturing a liquid crystal display panel according to the fifth embodiment of the present invention.
First, a pixel electrode 12 and a TFT (not shown) are formed in a display area on the transparent substrate 11 serving as a TFT substrate, and a horizontal alignment film 13 is formed so as to cover the pixel electrode 12 and the TFT. The surface of the alignment film 13 is rubbed.
[0039]
On the other hand, a color filter (not shown) and a black matrix (not shown) are formed in the display area of the transparent substrate 21 serving as a CF substrate, and a counter electrode 22 is formed thereon. Then, a horizontal alignment film 23 is formed on the counter electrode 22 and the surface of the alignment film 23 is rubbed.
Then, the alignment film forming surfaces of the substrates 11 and 21 are opposed to each other, spacers are scattered between the substrates 11 and 21, and both are bonded by a sealing material (ultraviolet curable resin). At this time, a liquid crystal injection port for injecting liquid crystal between the substrates 11 and 21 is formed in a later step.
[0040]
Next, liquid crystal is injected between the substrates 11 and 21, and a sealing material (ultraviolet curable) 3 is filled in the liquid crystal injection port. Thereafter, a light shielding plate 31 covering the display area is overlaid on the substrate 21, and a polarizer 32 is disposed between the substrate 21 and the light source. Then, a voltage is applied to the pixel electrode slightly inside the edge of the display area. As a result, as shown in FIG. 9, the director direction of the liquid crystal molecules 2 at the edge of the display region is aligned obliquely with respect to the substrate surface. After aligning the director direction of the liquid crystal molecules 2 in this manner, the sealing material 3 is cured by irradiating ultraviolet rays through the polarizer 32. In this case, it is necessary to arrange the polarizer 32 so that the amplitude plane of the light passing through the polarizer 32 is perpendicular to the orientation of the liquid crystal molecules 2. In this way, a liquid crystal display panel is completed.
[0041]
In the present embodiment, since the polarizer 32 is arranged so that the amplitude plane of the light passing through the polarizer 32 is perpendicular to the azimuth angle of the liquid crystal 2, the deterioration of the liquid crystal molecules due to ultraviolet rays is prevented.
In this embodiment, a voltage is applied between the pixel electrode in the vicinity of the edge of the display region and the counter substrate among the plurality of pixel electrodes to generate an electric field oblique to the substrate surface. However, in the case of a switching type liquid crystal display panel in which the upper and lower electrodes are arranged in an oblique direction and an oblique electric field is used for driving, the pixels in the oblique direction are left as they are. An AC voltage may be applied to the electrode.
[0042]
Hereinafter, the results of forming an evaluation liquid crystal display panel by the method described in each of the above-described embodiments and examining the electrical characteristics thereof will be described.
(Electrical characteristics evaluation by single cell)
Conventional method (comparative example) using Nippon Synthetic Chemical polyimide (JALS-644) for the vertical alignment film, Nissan Chemical polyimide (SE-7792) for the horizontal alignment film, and Merck standard liquid crystal (ZLI-4792) for the liquid crystal First Embodiment (Example 1), Third Embodiment (Example 2), Fourth Embodiment (Example 3), and Fifth Embodiment (Example 4) A liquid crystal display panel for evaluation having a TN type single cell structure with a twist angle of 90 ° was prepared.
[0043]
These liquid crystal display panels for evaluation are formed by forming ITO electrode pads on one substrate side, etching them in a stripe shape with a pitch of 100 μm, and forming electrode pads on one side on the other substrate side. The structure is similar to a panel.
The UV curable resin is cured using an oak medium- and high-pressure mercury lamp, and 2000 mJ / cm from above the substrate surface.²Irradiation was performed under the condition of (I-line standard).
[0044]
When an alternating voltage was applied between the electrodes during the ultraviolet irradiation (Examples 2 to 4), a high frequency voltage having a frequency of 30 kHz was applied to prevent ion adsorption on the electrode surface. Further, in order to sufficiently align the liquid crystal molecules with an electric field, 10 V, which is about twice the saturation voltage of the liquid crystal, was applied between the electrodes.
Table 1 below shows the results of examining the ion density and voltage holding ratio of the liquid crystal display panels for evaluation manufactured according to the comparative examples and the examples.
[0045]
[Table 1]

[0046]
As is apparent from Table 1, in the case of the comparative example, the ion density greatly increased due to the irradiation of ultraviolet rays, and the voltage holding ratio decreased by 2.4%. If the voltage holding ratio decreases, the active matrix liquid crystal display panel leaks without being held until the next data writing time, resulting in display irregularities (color loss). . On the other hand, in the liquid crystal display panels of Examples 1 to 4, the decrease in the voltage holding ratio is as small as 0.3 to 0.7%, and it can be seen that the optical deterioration of the liquid crystal can be suppressed.
[0047]
(LCD panel lighting test)
Next, a liquid crystal display panel was formed by a dropping injection method, and the presence or absence of display unevenness when lit for a long time was examined.
That is, a liquid crystal display panel was manufactured by the dropping injection process using the alignment film and the liquid crystal used in the evaluation of the electrical characteristics described above. A horizontal alignment film was applied to the display area of the TFT substrate and the CF substrate, and a vertical alignment film was applied between the area where the sealing material was applied and the display area, and thermosetting was performed.
[0048]
Each alignment film of the TFT substrate and the CF substrate was rubbed so that the twist angle was 90 °, and then an ultraviolet curable resin (epoxy acrylate resin: manufactured by Kyoritsu Chemical Co., Ltd.) was applied in a frame shape to one of the substrates. Then, multiple points of liquid crystal were dropped on the display area of one substrate so that the liquid crystal was evenly diffused when the two substrates were bonded together. A gap material (adhesive spacer 5 μm: made by Hayakawa Rubber) was sprayed on the other substrate. Thereafter, both substrates were set in a laminating machine and bonded in a vacuum.
[0049]
Next, the sealing material was irradiated with ultraviolet rays and cured while applying an alternating voltage (f = 30 kHz, V = 10 V) between the pixel electrode in the vicinity of the edge of the display region and the counter electrode. Thereby, the liquid crystal display panel shown in FIG. 10 was completed. In FIG. 10, a hatched area is a display area. A horizontal alignment film is formed in the display area, and vertical alignment films 13b and 23b are formed outside the display area. In addition, a voltage was applied between the pixel electrode outside the position indicated by the alternate long and short dash line and the counter substrate. Reference numeral 15 denotes a terminal region in which a plurality of terminals connected to the bus line are arranged, and a driving voltage is supplied to each terminal from the driving circuit board.
[0050]
The liquid crystal display panel thus manufactured was unitized, and a drive test was performed under the condition of 50 ° C. using an environmental tester. As a result, even after 500 hours, display unevenness did not occur in the vicinity of the resin portion.
On the other hand, a liquid crystal display panel was formed in the same manner as described above except that no voltage was applied during ultraviolet irradiation. And the drive test was done on the conditions similar to the above using the environmental testing machine. As a result, display unevenness due to a decrease in the voltage holding ratio occurred in the vicinity of the seal portion from the beginning of lighting, and the region expanded with time. From this, it can be seen that the present invention is extremely useful for improving the reliability of the liquid crystal display panel.
[0051]
【The invention's effect】
As described above, according to the present invention, the director direction of the liquid crystal molecules is directed to the propagation direction of the ultraviolet rays or the polarizer is set during the curing of the sealing material or the sealing material or the ultraviolet irradiation for preventing display unevenness. In this way, ultraviolet rays of only the polarization component in the direction perpendicular to the orientation of the liquid crystal molecules are irradiated, so that deterioration of the liquid crystal due to the ultraviolet rays is suppressed. Thereby, the curing of the sealing material or the sealing material using ultraviolet rays and the sealing curing in the dropping injection process can be performed with reliability, and the manufacturing yield and productivity of the liquid crystal display panel are greatly improved. In addition, when the entire panel surface is irradiated with ultraviolet rays to prevent display unevenness, deterioration of the liquid crystal is avoided.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing liquid crystal molecules on a substrate surface of a liquid crystal display panel.
FIG. 2 is a schematic diagram (part 1) illustrating the method for manufacturing the liquid crystal display panel according to the first embodiment of the present invention.
FIG. 3 is a schematic diagram (part 2) illustrating the method for manufacturing the liquid crystal display panel according to the first embodiment of the present invention.
FIG. 4 is a schematic view showing a method for manufacturing a liquid crystal display panel according to a second embodiment of the present invention.
FIG. 5 is a schematic diagram (part 1) illustrating the method for manufacturing the liquid crystal display panel according to the third embodiment of the present invention.
FIG. 6 is a schematic diagram (part 2) illustrating the method for manufacturing the liquid crystal display panel according to the third embodiment of the present invention.
FIG. 7 is a schematic diagram (part 1) illustrating the method for manufacturing the liquid crystal display panel according to the fourth embodiment of the present invention.
FIG. 8 is a schematic diagram (part 2) illustrating the method for manufacturing the liquid crystal display panel according to the fourth embodiment of the present invention;
FIG. 9 is a schematic view showing a method for manufacturing a liquid crystal display panel according to a fifth embodiment of the present invention.
FIG. 10 is a schematic view showing a liquid crystal display panel used in a lighting test.
FIG. 11 is a schematic diagram showing a conventional problem.
[Explanation of symbols]
2 Liquid crystal molecules
3 Sealing material
4 Sealing material
11, 21 substrate
12 pixel electrodes
13, 13a, 13b, 23, 23a, 23b Alignment film
22 Counter electrode
31 Shading plate
32 Polarizer

Claims (11)

  Liquid crystal is sealed between a pair of substrates, a sealing material made of a photocurable resin is applied to the outside of the display area, and the director direction of the liquid crystal molecules in the vicinity of the sealing material is made parallel to the light propagation direction and irradiated with light. A method of manufacturing a liquid crystal display panel, wherein the sealing material is cured.   2. The method of manufacturing a liquid crystal display panel according to claim 1, wherein a vertical alignment film is formed in the vicinity of the sealing material as means for making the director direction of the liquid crystal molecules parallel to the light propagation direction.   2. The method of manufacturing a liquid crystal display panel according to claim 1, wherein an electric field is generated in a direction perpendicular to the substrate surface as means for making the director direction of the liquid crystal molecules parallel to the light propagation direction.   The voltage is applied between the pixel electrode formed on one substrate and the counter electrode formed on the other substrate as means for generating an electric field in a direction perpendicular to the substrate surface. 4. A method for producing a liquid crystal display panel according to 3.   Liquid crystal is sealed between a pair of substrates, a sealing material made of a photocurable resin is applied to the outside of the display area, the director direction of the liquid crystal molecules in the vicinity of the sealing material is aligned, and the amplitude surface is relative to the director direction of the liquid crystal molecules. A method of manufacturing a liquid crystal display panel, wherein the sealing material is cured by irradiating perpendicular light.   6. The method of manufacturing a liquid crystal display panel according to claim 5, wherein as a means for aligning the director direction of the liquid crystal molecules, an electric field is generated in a direction parallel or oblique to the substrate surface.   7. The method of manufacturing a liquid crystal display panel according to claim 6, wherein a voltage is applied between adjacent pixel electrodes as means for generating an electric field in a direction parallel to the substrate surface.   7. A voltage is applied between a pixel electrode formed on one substrate and a counter electrode formed on the other substrate as means for generating an electric field oblique to the substrate surface. The manufacturing method of the liquid crystal display panel of description.   6. The method of manufacturing a liquid crystal display panel according to claim 5, wherein a polarizer is disposed between the substrate and the light source for light irradiation as means for irradiating light having a vertical amplitude surface.   The method for manufacturing a liquid crystal display panel according to claim 1, wherein the light is ultraviolet light.   6. A liquid crystal display panel manufactured by the method according to claim 1 or 5, wherein liquid crystal is sealed between the pair of substrates by a dropping injection method.

Images