JP3859184B2 - Color liquid crystal panel and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal panel having a color image display function and a manufacturing method thereof.
[0002]
[Prior art]
With recent advances in microfabrication technology, liquid crystal material technology, mounting technology, etc., television images and various image displays that are practically unaffected by 5 to 50 cm diagonal liquid crystal panels are provided on a commercial basis. In addition, color display is easily realized by forming an RGB colored layer on one of the two glass substrates constituting the liquid crystal panel. In particular, an active matrix type liquid crystal panel in which a switching element is built in for each pixel guarantees an image with little crosstalk, a high-speed response, and a high contrast ratio. The matrix configuration of such a liquid crystal panel is generally about 100 to 1000 scanning lines and about 200 to 2000 signal lines, but recently, large screens and high definition have progressed simultaneously.
[0003]
FIG. 6 is a conceptual diagram showing a schematic structure of the liquid crystal panel. An electrode terminal group 6 for scanning lines is formed on one transparent insulating substrate constituting the liquid crystal panel 1, for example, a glass substrate 2. There is also a COG (Chip-On-Glass) system in which a semiconductor integrated circuit chip 3 that generates an operation signal from a drive signal is mounted on a glass substrate 2. Although both mounting methods are shown in FIG. 6, one of the methods is actually selected.
[0004]
As for the signal electrodes, a signal line terminal group 5 is formed on the glass substrate 2, and for example, a connection film 4 in which a copper wire and a gold plating terminal are formed on a base of a polyimide-based resin thin film is connected to a signal line terminal via a conductive adhesive. Connected to group 5 and fixed (TCP method). The above-mentioned COG method can also be adopted for this signal electrode. In this way, the scanning signal and the display data signal are supplied to the image display unit. In FIG. 6, wiring paths 7 and 8 connecting the image display unit of the liquid crystal panel 1 and the electrode terminal groups 5 and 6 of the signal lines and the scanning lines are not necessarily formed of the same material as the electrode terminal groups 5 and 6. do not have to.
[0005]
The glass substrate 9 which is a transparent insulating substrate arranged in parallel with the glass substrate 2 has a transparent conductive counter electrode common to all liquid crystal cells. The two glass substrates 2 and 9 constituting the liquid crystal panel 1 are arranged in parallel at a distance of about several μm by a spacer material such as resin fiber or bead, and the gap (gap) is smaller glass. In the peripheral part of the board | substrate 9, it seals with the sealing material and sealing material which consist of organic resins, and a closed space is formed. This closed space is filled with liquid crystal.
[0006]
In a liquid crystal display panel that performs color display, an organic thin film having a thickness of about 1 to 2 μm including one or both of a dye and a pigment is formed on the closed space side of the glass substrate 9. This organic thin film is called a colored layer, and the glass substrate 9 including the colored layer is called a color filter substrate. Depending on the type (property) of the liquid crystal material, a polarizing plate is attached to one or both of the upper surface of the glass substrate 9 and the lower surface of the glass substrate 2.
[0007]
FIG. 7 is an equivalent circuit diagram of an active matrix liquid crystal panel in which insulated gate thin film transistors (hereinafter referred to as TFTs) as switching elements are arranged for each pixel. Elements and wirings drawn with solid lines are arranged on one glass substrate (active matrix substrate) 2, and elements and wirings drawn with broken lines are formed on the other glass substrate (color filter substrate) 9. . The TFT 10 is formed on the active matrix substrate 2 using, for example, amorphous silicon as a semiconductor layer and a silicon nitride layer as a gate insulating layer. At the same time, the scanning lines 11 and the signal lines 12 are also formed on the active matrix substrate 2.
[0008]
The liquid crystal cell 13 is sandwiched between a transparent conductive pixel electrode 14 formed on the active matrix substrate 2, a transparent conductive counter electrode 15 formed on the color filter substrate 9, and two glass substrates 2 and 9. And a liquid crystal 16 that fills the closed space, and has a predetermined capacitance (pixel capacitance). There are several variations in the configuration of the storage capacitor (auxiliary capacitor) added to the pixel capacitor in order to increase the time constant of the liquid crystal cell 13. In the example of FIG. 7, the storage capacitor 17 is formed in a portion where the common electrode 18 common to all the pixels and each pixel electrode 14 face each other through an insulating layer such as a gate insulating layer of the TFT.
[0009]
In a recently developed IPS (In-Plain-Switching) type liquid crystal panel having a wide viewing angle, as shown in FIG. 8, the pixel electrode 42 and the counter electrode 41 constituting the liquid crystal cell are formed on the active matrix substrate 2. Are arranged at predetermined intervals. Usually, the pixel electrode 42 and the counter electrode 41 are formed in a pair of comb shapes. The pixel electrode 42 can be connected to the drain of the insulated gate transistor to form an active matrix, but details are omitted. 43 shows the alignment state of the liquid crystal molecules in the liquid crystal cell. FIG. 8A shows a state in which no voltage is applied between the pixel electrode 42 and the counter electrode 41, and FIG. Each state is shown.
[0010]
FIG. 9 is a cross-sectional view of the main part of a color display liquid crystal panel. The colored layer 19 made of dyed photosensitive gelatin or colored photosensitive resin or the like is arranged on the closed space side of the color filter substrate 9 according to a predetermined arrangement of RGB three primary colors so as to correspond to the pixel electrode 14. The counter electrode 15 common to all the pixel electrodes 14 is formed on the colored layer 19 in order to avoid voltage distribution loss in the liquid crystal cell due to the interposition of the colored layer 19. An alignment film 20 is formed on the two glass substrates 2 and 9 so as to be in contact with the liquid crystal 16. This is, for example, a polyimide resin layer having a thickness of about 0.1 μm, and has a function of aligning liquid crystal molecules in a predetermined direction. In addition, when a twisted nematic (TN) type liquid crystal 16 is used, two upper and lower polarizing plates 21 are required.
[0011]
An opaque film 22 called a black matrix (BM) that hardly reflects light is disposed at the boundary between the RGB colored layers 19. This black matrix 22 blocks the reflected light from the wiring layers such as the signal lines 12 on the active matrix substrate 2 to improve the contrast of the image, and prevents an increase in leakage current due to the external light of the TFT as a switching element. The liquid crystal panel can be operated even under strong external light.
[0012]
The black matrix has various configurations, but considering the generation of a step at the boundary between adjacent colored layers and the light transmittance, it is disadvantageous in terms of cost, but a Cr thin film having a thickness of about 0.1 μm is used. Is simple and reasonable.
[0013]
In FIG. 9, components such as TFTs, scanning lines, storage capacitors, back light sources, spacers, etc. are not shown. 23 is a conductive thin film for connecting the pixel electrode 14 and the drain of the TFT 10, and is usually formed of the same material as the signal line 12 at the same time and is called a drain wiring. The counter electrode 15 is connected to an appropriate conductive pattern on the active matrix substrate 2 via a conductive paste outside the image display portion, and is connected to one of the electrode terminal groups 5 and 6 in FIG.
[0014]
FIG. 10 is a plan view (viewed from the glass panel 2 side) around the edge of the scanning line at the periphery of the liquid crystal panel. FIG. 11 is a cross-sectional view corresponding to the line AA ′ in FIG. The active matrix substrate 2 and the color filter substrate 9 are sealed with an adhesive seal material (resin) 24. The width of the sealing material 24 is about 0.5 to 1.2 mm, and the height is several μm corresponding to the gap of the liquid crystal cell. Such a sealing material can be efficiently formed by screen printing in a small liquid crystal panel. Further, a large liquid crystal panel is formed using a seal drawing machine so that no foreign matter is transferred.
[0015]
In FIGS. 10 and 11 showing the periphery of the portion where the sealing material at the periphery of the liquid crystal panel is disposed, the terminal electrode 6 of the scanning line 11 is a silicon nitride layer (SiNx) which is a gate insulating layer having a thickness of about 0.3 μm. The source / drain wirings 12 and 23 are formed in the opening 26 formed in 25. The terminal electrode 6 is exposed through an opening 28 formed in the passivation insulating layer 27 made of a silicon nitride layer having a thickness of about 0.3 μm. Further, around the image display portion, a colored layer 19 ′ and a black matrix 22 ′ having a predetermined number of arrangements or more are arranged so that unnecessary light from the back surface does not leak when the liquid crystal panel is viewed obliquely. ing.
[0016]
[Problems to be solved by the invention]
The latest LCD panels are often narrowed. In other words, the display device can be designed to be as small as possible outside the image display unit, thereby reducing the weight and size of the display device. Therefore, the sealing material 24 is disposed as close to the image display unit as possible. As a result, as shown in FIG. 11, the black matrix 22 ′ must be disposed on the sealing material 24.
[0017]
In addition, a large panel having a diagonal of 25 cm or more has been increased in definition to improve display capacity and display image quality, and it is required to ensure an aperture ratio. As a result, it has become important to reduce the width of the black matrix and improve the bonding accuracy of the two substrates 2 and 9 constituting the liquid crystal panel. That is, in the past, a bonding accuracy of about several μm was sufficient, but in order to increase the aperture ratio to 80% or higher, a high accuracy of 2 μm or less has been required.
[0018]
The bonding accuracy of the liquid crystal panel is determined by the sum of the processing accuracy of the active matrix substrate and the color filter substrate and the bonding accuracy of the two substrates in the bonding process. Accordingly, the larger the liquid crystal panel, that is, the larger the glass substrate, the greater the warp and undulation of the glass substrate, and the lower the accuracy.
[0019]
Keeping the bonding accuracy within 1 to 2 μm is not so difficult considering the mechanism and ability of a high-precision exposure machine for large substrates. However, due to the warping of the glass substrate in the curing process of the seal 24, the actual accuracy that can be secured in practice is reduced to several μm.
[0020]
Of particular importance in the curing process is temperature uniformity. Since the glass substrate has an expansion coefficient of several ppm per 1 ° C., for example, if there is a temperature difference of 10 ° C., an expansion / contraction difference of 10 to 20 μm is generated in the case of a glass substrate having a size of 30 cm. For this reason, although slow heating and slow cooling are indispensable for the heating and cooling in a hardening process, in order to improve productivity, it is necessary to shorten the time required for heating and cooling.
[0021]
Therefore, it has been studied to thermally cure the sealing material at a low temperature of about 100 ° C. However, generally, when the curing temperature is lowered, a decrease in hermeticity and adhesion is inevitable. In addition, the residual solvent in the sealing material is dissolved in the liquid crystal, the retention rate of the liquid crystal cell is lowered, and the display characteristics of the liquid crystal panel during high temperature operation and long time operation are unavoidable.
[0022]
On the other hand, when an ultraviolet curable sealing resin that does not require heating is employed, a black matrix 22 ′ having a light shielding property is interposed between the color filter substrate 9 and the sealing resin 24 as shown in FIGS. Therefore, the ultraviolet rays for curing the sealing resin 24 cannot be irradiated from the outer surface of the color filter substrate 9 and must be irradiated from the outer surface of the active matrix substrate 2.
[0023]
However, the scanning lines 11 and the signal lines 12 are partially interposed between the active matrix substrate 2 and the sealing resin 24. These electrode wires generally use a metal thin film to lower the resistance value, and are opaque to ultraviolet rays. Since the pattern width of the electrode line is at least 20 μm, it is impossible to completely cure the seal resin 24 in the part blocked by the electrode line even when taking into account that ultraviolet rays circulate from the periphery of the electrode line. In this case, even if the bonding accuracy is high, a liquid crystal panel with low seal reliability is obtained. On the other hand, when an ultraviolet curable seal resin and a thermosetting seal resin are used in combination, the reliability of the seal is increased, but the bonding accuracy is reduced by heating as in the conventional case.
[0024]
The present invention has been made in view of the above-described conventional problems, and provides a color liquid crystal panel capable of improving the bonding accuracy for realizing a liquid crystal panel with a high aperture ratio and a method for manufacturing the color liquid crystal panel. With the goal.
[0025]
[Means for Solving the Problems]
According to a first configuration of the color liquid crystal panel of the present invention, a scanning line made of a plurality of metal thin films and a signal line made of a plurality of metal thin films intersecting the scanning lines via an insulating layer are provided on a transparent insulating substrate. An active matrix substrate provided with a switching element and a transparent pixel electrode at each intersection of the scanning line and the signal line, a color filter substrate having a transparent conductive layer and facing the active matrix substrate, and the active matrix substrate And a liquid crystal panel provided with a liquid crystal filled between the color filter substrate and a sealing material for sealing the liquid crystal, an electrode line made of a metal thin film including the scanning line and the signal line, It is formed continuously at the portion intersecting with the sealing material, and has an opening through which ultraviolet rays for curing the sealing material can pass. To. According to such a configuration, when the ultraviolet rays are irradiated from the outer surface of the active matrix substrate, the ultraviolet rays that pass through the openings provided in the electrode lines made of the light-shielding metal thin film that are continuously formed and the openings wrap around the openings. The sealing material at the portion intersecting with the electrode wire can be almost completely cured by the ultraviolet rays. Accordingly, it is possible to improve the bonding accuracy by lowering the temperature of the seal curing process.
[0028]
The above-described configuration, that is, the configuration in which the opening is provided in the electrode line made of the metal thin film continuously formed in the portion intersecting with the sealing material can be applied to an IPS (In-Plain-Switching) type liquid crystal panel.
[0029]
For the above-described configuration, a plurality of the openings are provided, the width of the portion of the electrode wire that intersects the sealing material is wider than the width of the other portions, and the sealing material is UV-cured. And a light-shielding film is provided between the color filter substrate and the sealing material. In addition, the method according to the present invention for manufacturing the liquid crystal panel having the above-described configuration is such that when the active matrix substrate and the color filter substrate are bonded together using a sealing material, ultraviolet rays are irradiated from the outer surface of the active matrix substrate. The sealing material is cured.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the structure of the liquid crystal panel according to the embodiment of the present invention will be described focusing on differences from the structure of the liquid crystal panel described in the related art.
[0031]
First, in the first embodiment shown in FIG. 1, the opening 30 is formed in the pattern of the scanning line 11 in a region where the scanning line 11 that is an electrode line intersects the seal resin 24. In this way, when viewed from the outer surface of the transparent glass substrate (active matrix substrate) 2, most of the region of the sealing resin 24 can be seen without being blocked by the pattern of the scanning lines 11. Therefore, when ultraviolet rays are irradiated from the outer surface of the active matrix substrate 2, the seal resin 24 is almost completely applied to the portions intersecting the scanning line pattern by the ultraviolet rays passing through the openings 30 and the ultraviolet rays circulated from the periphery of the openings 30. It can be cured.
[0032]
Similarly, at the portion where the signal line pattern and the seal resin 24 intersect, the seal resin 24 is almost completely cured by the ultraviolet rays irradiated from the outer surface of the active matrix substrate 2 by forming an opening in the signal line pattern. be able to.
[0033]
When an opening is provided in the electrode line pattern, the electrical resistance of the electrode line in that region increases. Therefore, sufficient consideration is required for the size of the opening. As shown in FIG. 1, an increase in electrical resistance can be avoided by providing a plurality of openings or increasing the pattern width of the portions. In addition, by setting the ultraviolet irradiation time long and effectively using the diffracted light from the periphery of the opening, the sealing resin 24 can be almost completely cured to compensate for the small opening.
[0034]
Next, a second embodiment of the present invention is shown in FIGS. 2 is a plan view seen from the outer surface of the active matrix substrate 2, and FIG. 3 is a cross-sectional view corresponding to the line AA 'in FIG. In this embodiment, in the region where the signal line 12 that is an electrode line intersects the sealing resin 24, prior to the formation of the signal line 12, the transparent conductive connection pattern 31 is formed on the transparent insulating layer 25 simultaneously with the formation of the pixel electrode. To form. Then, the divided signal line 12 is formed so as to be connected to both end portions of the connection pattern 31.
[0035]
Since the signal line in the region intersecting with the sealing resin 24 is formed by the transparent conductive connection pattern 31, when the ultraviolet ray is irradiated from the back surface of the active matrix substrate 2, the signal line is transmitted by the ultraviolet ray transmitted through the transparent connection pattern 31. The sealing resin can be almost completely cured even at the portion intersecting the line.
[0036]
Similarly, at the portion where the scanning line pattern and the sealing resin 24 intersect, the scanning line made of a light-shielding material is partially formed of a transparent conductive layer, so that the sealing is performed by ultraviolet rays irradiated from the outer surface of the active matrix substrate 2. The resin 24 can be cured almost completely. Of course, an opening is formed in the insulating layer 25 prior to the formation of the transparent conductive connection pattern, for example, similarly to the formation of the terminal electrode 6 so that the transparent conductive connection pattern and the scanning line are electrically connected. It is necessary to form and expose a part of the scanning line.
[0037]
Next, a third embodiment of the present invention is shown in FIGS. 4 is a plan view seen from the outer surface of the active matrix substrate 2, and FIG. 5 is a cross-sectional view corresponding to the line AA ′ of FIG. In this embodiment, in the region where the signal line 12 that is an electrode line intersects with the sealing resin 24, the transparent conductive connection pattern 31 is formed on the transparent base transparent simultaneously with the formation of the pixel electrode 14 prior to the formation of the signal line 12. Formed on the insulating layer 25. Thereafter, the signal line 12 having the opening 30 is formed so as to include the connection pattern 31.
[0038]
In the region intersecting with the sealing resin 24, the signal line 12 is laminated with the transparent conductive connection pattern 31 and the signal line 12 having the opening, and therefore transparent when irradiated with ultraviolet rays from the back surface of the active matrix substrate 2. The sealing resin can be almost completely cured even at the portion intersecting with the signal line by the ultraviolet light transmitted through the connection pattern 31, the ultraviolet light transmitted through the opening 30, and the ultraviolet light circulated from the periphery of the opening 30.
[0039]
Similarly, at the portion where the scanning line pattern and the sealing resin 24 intersect, similarly, an opening is provided in the scanning line made of a light-shielding material, and the transparent conductive layer is partially used together to irradiate from the outer surface of the active matrix substrate 2. The sealing resin can be completely cured by the applied ultraviolet light. This embodiment is suitable for a large-sized liquid crystal panel because an increase in electrical resistance caused by providing an opening in an electrode line can be compensated for by using (lamination) a transparent conductive connection pattern.
[0040]
As a fourth embodiment, the present invention can also be applied to an IPS (In-Plain-Switching) type color liquid crystal panel. As described above, in the IPS liquid crystal panel, the pixel electrode and the counter electrode constituting the liquid crystal cell are both formed on the active matrix substrate, and a transparent conductive layer is unnecessary. Therefore, applying the above-described second and third embodiments to an IPS liquid crystal panel adds a step of forming a transparent conductive layer, which is not desirable in terms of cost. However, as in the first embodiment described above, the configuration in which the opening is formed in the electrode line at the portion intersecting with the ultraviolet curable sealing resin can be easily applied to the IPS liquid crystal panel. In this case, the same effect can be obtained.
[0041]
In each of the above embodiments, the configuration or material of a switching element such as an insulated gate transistor and the configuration or material of a scanning line and a signal line that are electrode lines are not particularly limited. In Embodiment 2 or 3, the order of forming the transparent conductive layer and the electrode line may be reversed.
[0042]
【The invention's effect】
As described above, according to the present invention, an ultraviolet curable resin is used as a sealing material for sealing the active matrix substrate and the color filter substrate, and sealing is performed by irradiating ultraviolet rays from the outer surface of the active matrix substrate. The material can be cured almost completely. As a result, it is possible to achieve both improvement in bonding accuracy and improvement in seal quality by lowering the temperature in the paneling process, and a liquid crystal panel having a high aperture ratio and high reliability can be obtained.
[Brief description of the drawings]
FIG. 1 is an arrangement diagram of electrode patterns on a scanning line side of an active matrix matrix substrate according to a first embodiment of the present invention. FIG. 2 is an electrode pattern on a signal line side of an active matrix substrate according to a second embodiment of the present invention. FIG. 3 is a cross-sectional view corresponding to the line AA ′ in FIG. 2. FIG. 4 is a layout diagram of electrode patterns on the signal line side of the active matrix substrate according to the third embodiment of the present invention. FIG. 6 is a perspective view showing a mounting state of a conventional liquid crystal panel. FIG. 7 is an equivalent circuit diagram of a conventional active matrix type liquid crystal panel. FIG. 9 is a cross-sectional view of a main part of a conventional active matrix type liquid crystal panel. FIG. 10 is an arrangement of electrode patterns on the scanning line side of an active matrix substrate using a conventional liquid crystal panel. FIG. 11 is a cross-sectional view corresponding to the line AA ′ in FIG.
2 active matrix substrate 9 color filter substrate 11 scanning line 12 signal line 24 sealing material 25 insulating layer 26 opening 27 formed in insulating layer passivation insulating layer 28 opening 30 formed in passivation insulating layer formed on electrode line Opening 31 Transparent conductive connection pattern partially constituting electrode wire

Claims (7)

A scan line comprising a plurality of metal thin film on a transparent insulating substrate, a signal line comprising a plurality of metal thin film which intersects the scanning lines via an insulating layer is provided, at intersections of the scanning lines and the signal lines An active matrix substrate provided with a switching element and a transparent pixel electrode;
A color filter substrate having a transparent conductive layer and facing the active matrix substrate;
And liquid crystal filled between the color filter substrate and the active matrix substrate,
In a liquid crystal panel provided with a sealing material for sealing the liquid crystal,
Before Kihashi査線and electrode line made of a metal thin film including the signal line, while being formed continuously at the intersection with the sealing material, has an opening capable of passing the ultraviolet curing the sealing material A color LCD panel. A scan line comprising a plurality of metal thin film on a transparent insulating substrate, a signal line comprising a plurality of metal thin film which intersects the scanning lines via an insulating layer is provided, at intersections of said scanning lines and said signal lines An active matrix substrate having a switching element, a pixel electrode and a counter electrode arranged at a predetermined interval;
A color filter substrate facing the active matrix substrate;
And liquid crystal filled between the color filter substrate and the active matrix substrate,
In a liquid crystal panel provided with a sealing material for sealing the liquid crystal,
Before Kihashi査線and electrode line made of a metal thin film including the signal line, while being formed continuously at the intersection with the sealing material, has an opening capable of passing the ultraviolet curing the sealing material A color LCD panel. The color liquid crystal panel according to claim 1, wherein a plurality of the openings are provided. The color liquid crystal panel according to any one of claims 1 to 3, wherein a width of a portion of the electrode line intersecting with the sealing material is wider than a width of the other portion. The color liquid crystal panel according to claim 1, wherein the sealing material is an ultraviolet curable resin. The color liquid crystal panel according to claim 1, wherein a light-shielding film is provided between the color filter substrate and the sealing material. A method of manufacturing a liquid crystal panel according to any one of claims 1 to 6, ultraviolet and the active matrix substrate and the color filter substrate when bonded with the sealing material, from the outer surface of the front Symbol active matrix substrate A method for manufacturing a liquid crystal panel, wherein the sealing material is cured by irradiation.

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