JPS61100728A - Color liquid crystal panel - Google Patents

Abstract

PURPOSE:To reduce troubles such as disconnection remarkably by forming a metal wire on a glass substrate. CONSTITUTION:A stripe-like metal-wired pattern 61 e.g. is formed on a transparent substrate 21. The gap of the metal wire 61 is filled with a color filter 23 preferably so that the thickness of the color filer 23 almost coincides with that of the metal wire 61, and a transparent protection film 62 is formed on said structure. Conductive property is applied to a pat of the color filter 23 which is a thin insulating film or the protection film. Namely, the substrate obtained by forming the metal wire 61 on the glass substrate 21 and then forming the color filter 23 or the protection film 62 on the metal wire 61 is dipped into an electrolytic solution 71 and a voltage 74 is applied between the metal wire 61 to be used as a working pole and an opposite pole 72.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of industrial application] The present invention relates to a liquid crystal panel for multicolor or natural color display.

[Background of the invention]

In recent years, with the development of famous information devices such as combiators and televisions, the role of display devices as the output terminal for information has become increasingly important. L, - is going on.

Conventionally, this display device has been CR'r (infusumakatsu'#
) is the most widely used, but in recent years, the ratio of LCL) (i-crystal display #) has been rapidly increasing due to its thinness and low power consumption. On the other hand, since the display device has the characteristic of appealing to human vision, it goes without saying that color display is generally preferable. Therefore, the need for color LCIJ has become extremely large.

[Prior art and problems]

To date, various ideas have been made to realize color LCDs. These include, for example, the ECB (electrically controlled birefringence) method, the guest-host method, and the birefringent film-TN.
(twisted nematic) type, optically dispersive-cholesteric type cloud, but from the viewpoint of natural color display performance and structural reliability, liquid crystal is currently used as the optical shutter, and red (uniform) and green (Gl) clouds are used. , color LCI (combined with blue FB+ three primary color filters) is the most promising.

FIG. 1 is a conceptual diagram for explaining the operating principle of a color filter-type color LCD. White incident light 16 passes through a color filter 11, and after spectral components are selected, a light shutter α On the crystal panel 12 (
- The amount of transmitted light is adjusted, and the human eye 15 sees the output light 14 (in this case, R and G are transmitted and the color is yellow to yellow-green). Note that the relative position of the pupil 1 between the color filter 11 and the liquid crystal panel 12 with respect to the incident light 11 is
3Ij may be reversed.

Figure 2 shows the prior art and is a sectional view showing the formation location of color filters in a liquid crystal panel.
The color filter 26 is formed on the outside of the liquid crystal panel (called an external type), which is composed of glass plates 21 and 22 facing each other. (called intrinsic type).The main difference between the two is that the reliability decreases due to chemical interference with the pseudocrystalline layer of the color filter.1 [Phase]: The external type is superior in 5 points in that it has no color filter, and the internal type is superior in that the distance between the color filter and the liquid crystal shutter is small and unnecessary color mixing does not occur even when the display device is viewed from an oblique direction. Considering that the current goal of liquid crystal panels is high density and high definition, the problem of color mixing mentioned above must be said to be extremely serious. It is highly desirable to make color LCDs in molds.

From the above viewpoint, the internal type color LCD will be described below and its problems will be summarized.

Figure 3 is a cross-sectional view showing the positional relationship between the transparent electrode and the color filter in the internal type shown in Figure 2 (bl);
) The color filter 26 is formed on the transparent electrode 31 on the GX glass plate 21 (referred to as the upper filter structure), whereas in FIG. A transparent electrode 61 is formed on the top (referred to as a lower filter structure).The important difference between the upper filter structure and the lower filter structure appears in the driving of the liquid crystal.

To explain this, a circuit diagram of the upper filter structure is shown in FIG. That is, the capacitance component CCF 41 due to the color filter and the capacitance component CLc 42 due to the liquid crystal layer are coupled in series between the terminals 46.44 corresponding to the opposing transparent electrodes, and the voltage applied between the terminals 46.44 V and c, which are part of VA, do not contribute to liquid crystal driving. If you write this as a constant/purpose, VLC = VA, Ccp / (CLC + CCF)
-----(II) Due to the influence of this voltage drop, in the upper filter structure, the voltage for driving the apparently upper liquid crystal must be increased compared to the conventional liquid crystal panel, and the extent is usually 20% or more, and in extreme cases it can be 100% or more. - The operating voltage of the IC (integrated circuit) for driving the liquid crystal is determined by the characteristics of the latch amplifier, etc., but the margin is at best 20 to 30%, which makes it almost impossible to apply to the upper filter structure.Furthermore, even if the conditions can be met in terms of IC withstand voltage, the
Since Ct and c of equation 1 change somewhat depending on the voltage applied to the liquid crystal, the optical characteristics of the liquid crystal itself deteriorates in appearance,
The upper filter structure has better display performance than conventional LCD panels.
decreases. Furthermore, in order to reduce the problem of voltage drop caused by a single color filter layer, it is possible to reduce the thickness of the color filter, but in this case, the optical properties of the color filter itself as a filter will deteriorate and the color will normally be reduced. This leads to a decrease in the degree of In this way, if an attempt is made to realize the upper filter structure, various kinds of large voltage blindness are likely to occur, and the root cause of these problems can be said to be the voltage drop caused by the color filter. Therefore, from the perspective of a structure that is not affected by this voltage drop, Fig. 3 t
It is clear that the lower filter structure of b) is the preferred one.

As mentioned above, the lower filter structure is a color LCD structure that is optimal from the viewpoint of liquid crystal driving. FIG. 5 shows a cross-sectional view of the lower filter structure of the conventional structure and its forming means ++m.1-0 First, as shown in FIG.
Color filters 26 of 83 colors are formed, a transparent protective film 51 for separating the color filter and the liquid crystal layer is formed on the arrow as shown in FIG.
A transparent conductor is formed like C+, and the transparent conductor is patterned using a photo-IJ technique to form a transparent electrode 61. Here, the transparent protective film 51 is usually made of an organic polymer compound, and the transparent conductor is usually ITO.
(Indium-Tin-Oxide). The transparent electrode 61 often also serves as a wiring, but in some cases, the metal formed on the ITO or the transparent protective film may be patterned to form a wiring. Although the lower filter structure can be formed as described above, considering that color filters usually have organic compounds as their main component and that transparent protective films are also usually made of organic compounds, it is important to understand that these base layers Due to the vulnerability of the wires, it must be said that there is an extremely high risk of wire breakage.

[Purpose of the invention]

The present invention aims to provide a color LC1) 4 with a novel lower filter structure that is less likely to cause wiring breakage, etc., and has high reliability, in view of the fragility of the lower filter structure. That is.

[Embodiments of the invention]

FIG. 6 shows the method and structure of a color LCI with an internal type lower filter structure according to the present invention. Here, only one of the two sheets of Hideaki Motoga constituting the liquid crystal panel is shown. However, the other transparent substrate is a normal simple mah IJ
What is used in the pseudocrystalline panel (of Kusuando), i.e.
A transparent mask is formed on a glass substrate. However, other configurations of the other transparent substrate include those for active matrix driving in which two-terminal active elements of diode rods are arranged regularly on a transparent substrate such as glass. FIGS. 6(a) to 6 tel are cross-sectional views, and FIGS.

As shown in Figure 6, a striped wiring pattern 61, for example, is formed on the transparent substrate 21. The most common method for forming this pattern is to evaporate the metal and then etch it using photolithography.
There are problems in terms of economic efficiency and adhesion of the film when using a film with a thickness larger than that of the film.

- 10,000, lowering the resistance value of the metal wiring is advantageous in terms of the effectiveness of the liquid crystal panel, and from that point of view, the thickness of the metal wiring layer should be reduced by 1.
It is preferable to set it as more than a film. Therefore, when the thickness of the metal wiring is desired to be one layer or more, it is effective to use the Bakukin method in combination.

Figure 6 (bl, tgl k'j, The color filter 26 is used to fill in the spaces between the metal wiring lines 61 in the above structure, and preferably the thicknesses of the color filter 26 and the metal wiring lines 61 are approximately the same. However, It is not necessary to form a color filter on the non-display portion when used as a liquid crystal panel. Also, a part of the color filter 26 may cover part or all of the metal wiring 61.

Further, within the display area of the LCD, it is preferable that all parts other than the metal wiring 61 be filled with the color filter 26. The color filter 26 is formed in a mosaic shape or a stripe shape.
It is preferable that the filter has good uniformity in film thickness, and color filters made by dyeing gelatin 4 membranes, dyed resin color filters coated with a spinner, etc. exhibit good properties.

Next, in Figure 6 (C), thl is ・1.61
Transparent protective film 62 on the structure of XI tl)l, tgl
It forms one piece. The protective film 62 is required to have insulating properties as well as transparency, and is made of polyimide resin, acrylic resin,
Polymer films such as 7-recon resin, and inorganic films such as oxidized/recon, silicon nitride, and fermented aluminum are used.

However, the function of the protective film is to prevent impurities (especially ionic impurities) from entering the liquid crystal layer from the color filter. Therefore, it is more preferable to apply a polymeric substance and utilize its thixotropic properties.

Figure 6 (d+,
This is a step of imparting conductivity to a portion of the protective film 62.

The purpose of this step is to achieve electrical connection between the transparent electrode formed in the step described in FIG. 6 (e) and (jl) and the metal wiring 61. In the color filter or the retention rate 1l
It is obtained by growing an organic polymer semiconductor in ii4 by electrolytic polymerization. FIG. 7 shows a configuration for carrying out this electrolytic polymerization. In addition, technology to form organic polymer semiconductors on electrodes by electrolytic polymerization &! A, F. Diaz et al. (J.
c, s, Chem, Comm,.

635 (1979)), and the technique for forming an organic polymer semiconductor in an organic film on an electrode by electrolytic polymerization was described by Niwa et al. (Proceedings of the Society of Polymer Science, Vol. 33, No. 4).
2J04.2Jsu5 (1984)).

In FIG. 7, a substrate in which a metal wiring 61 and a color filter 26 or a protective film 62 are formed on a glass substrate 21 is immersed in an electrolyte solution 71, and the metal wiring 61 is used as a working electrode and is connected to a counter electrode 72. A voltage 74 is applied to. Moreover, more stable polymerization conditions can be obtained by keeping the value of the voltmeter 75 constant by using a reference electrode 76, which is one of the basic structures in ordinary electrochemistry.

Here, the electrolyte solution is an electrolytic solution mainly composed of an organic solvent with a high dielectric constant such as acetonitrile or nitromethane, and a liquid containing electrolyte such as tetraethylammonium perchlorate, tetrafluoroborate, tetramethylammonium, etc. Monomers constituting the organic polymer semiconductor, such as pyrrol, thiophene, and Franck-, are dissolved in this solution using a grade ammonium salt-based semi-decomposer.

A metal wiring 61 made of nickel, gold, etc. is used for the positive electrode side of the working electrode, a filter dyed with gelatin is used as the color filter 26, a polyimide resin or the like is used as the protective film 62, and a metal wiring such as platinum is used as the counter electrode 72. A metal may be used as the reference electrode 76 (an ecalomel electrode, a silver silver chloride electrode, or a silver electrode). In electrolytic polymerization, a threshold voltage exists, and the value measured by the voltmeter 75 is the threshold voltage 11.
Set to a voltage (usually several volts) K that is better than Ik. In the second electrolytic polymerization, it is necessary to wait a sufficiently long time to make the color filter and protective film on the metal wiring conductive, and at this time, the area where the organic polymer semiconductor is formed (Fig. d) and (i) 63) generally turn black. FIG. 8 shows the molecular structure of polypyrrole as an example of an organic polymer semiconductor.

Next, as shown in FIG. 6 (J), a transparent conductive layer is formed and patterned by etching to form a transparent electrode 61. In this case, ITO is usually selected as the transparent conductor layer, but here, since the color filter 26 or the protective film 62 has already been formed,
This must be formed at a low temperature of approximately 200°C or less. Methods for forming ITO at this low temperature include vapor deposition, sputtering, and ion blating.
It is possible to create either. As shown in FIGS. 6(e) and (j), the transparent electrode 61 and the metal wiring 61 are separated by a protective film 62.
The organic polymer semiconductor layer 66 grown in the color filter 26 electrically connects the organic polymer semiconductor layer 66 to the color filter 26 .

In this case, the size of the contact point between the transparent electrode 31 and the metal wiring 61 can be made extremely large, since it covers almost the entire metal wiring 61, as can be easily seen from FIG.
The accuracy of electrical connection will be high.

The substrate formed in the above manner is subjected to normal processes such as wiring, overlapping with a counter substrate, and liquid crystal injection to form a color liquid crystal panel.

Next, a process for implementing the present invention will be explained.

300λ of chromium and 5000λ of nickel on a glass substrate
It was formed by continuous λ vapor deposition, and was made into a striped metal wiring 61 by photophosphorography technology. This was heat-treated at 300° C. in a nitrogen atmosphere, and then a gelatin-stained color filter 26 was formed in a mosaic shape with a film thickness of 2 μm.

Next, a polyimide resin that can be cured at 200° C. or lower was applied to the color filter 23 at 5000A, and after heat treatment, electrolytic polymerization was performed. The conditions for the first electrolysis were set such that the metal wiring was used as the working electrode, the platinum mesh (55 ml) was used as the counter electrode, and the silver platelet reference electrode was set so that the working electrode side was +1.6 V with respect to the reference electrode. It took about 20 minutes.

The electrolyte solution at this time was an electrolytic solution containing 9 parts acetonitrile and 1 part water, to which 0.1 mal/l of perchlorine, butylammonium and pyrrole were each added. As a result, the color filter 26 and the polyimide resin protective film 62 on the metal wiring 61 became dark black. lastly,
11'0 film is deposited by vapor deposition without raising the substrate temperature.
The electrode was formed to have a thickness of 00λ, and was made into an elongated electrode pattern using photolithography. Thereafter, a color liquid crystal panel was formed through a normal liquid crystal alignment process. At this time, the transparent substrate on the opposite side is simply a glass substrate with ITO electrodes formed thereon.

The color LCD formed in this way has no color mixture when viewed from an oblique direction, which is seen with the above-mentioned external type panel, and there is no increase in liquid crystal driving voltage, which is seen with the above-mentioned upper filter structure, and is extremely stable. i: Exhibited constant display performance.

〔Effect of the invention〕

As described above, according to the present invention, by using metal wiring and forming the wiring on a glass substrate, it is possible to greatly reduce the anxiety of disconnection, and it is possible to use transparent electrodes formed on a fragile structure only as a construction material. By thoroughly separating the functions, the instability of the lower filter horizontally was significantly improved. It has fewer restrictions and is highly reliable.

In addition, in the case of a color LCD, in order to prevent color mixture 7 between each pixel and increase the saturation of the entire screen, it is necessary to use adjacent pixels.

It is preferable that pixels having color filters of different colors are separated by a black line, but according to the present invention, the metal wiring is formed in a non-pixel part of the product panel. , it has the advantage that it can also serve as the black division line. Furthermore, since the electrical connection between the metal wiring and the transparent electrode is made by growing an organic polymer semiconductor in an intermediate insulating film, it is necessary to perform a cumbersome and low-yield process such as drilling contact holes in the insulating film. In addition, due to the characteristics of the polymer semiconductor itself, problems such as stability as a conductor and contact resistance with metals are unlikely to occur (・. Also, as an advantage of the electrolytic polymerization method, the initial The polymer semiconductor layer is formed only on the metal wiring 61, and no patterning process is required.The metal wiring and the transparent electrode are formed in parallel over a long distance (several tens to hundreds of mm). Because of the size of the eastern part of the two, it has structural stability with high accuracy of electrical connection.Also, since the electrical resistance of the metal wiring itself is small, This is also advantageous for driving a liquid crystal panel.

According to the present invention, a color LCD with excellent display performance can be easily produced, and is very effective in terms of yield and mass production in terms of cost.

[Brief explanation of drawings]

Fig. 1 is a structural conceptual diagram for explaining the operating principle of a color LCD using one type of color filter; Fig. 2(a), Fig. 2ft)l, Fig. A cross-sectional view explaining the positional relationship between the filter and the liquid crystal panel, Figure 4 is an equivalent circuit diagram of the upper filter structure, and Figure 5 is an equivalent circuit diagram of the upper filter structure.
Figures (AJ to Figure 5) (CJ is a cross-sectional view explaining the conventional lower filter structure, Figure 6 shows a color LCD according to an embodiment of the present invention, Figure 6 1A to Figure 6 1A is a cross-sectional view, From Figure 6(f), Figure 6('') is 6 i:5 (
Plan view corresponding to each of FIG. 6(e) from J, No. 7
The figure is an explanatory diagram of a method for carrying out the electrolytic polymerization step of the present invention, and FIG. 8 shows the molecular structure of an organic polymer semiconductor according to an embodiment of the present invention. 11.23...Color filter, 12...
...Liquid crystal panel, 21...Transparent substrate, 61...Transparent electrode, 51.62...Transparent retention film, 61...Metal wiring, 66... Organic polymer semiconductor layer, 71...
- Electrolyte solution, 72...Counter electrode, 73...Reference electrode. Patent applicant Citizen Watch Co., Ltd. Figure 1 Figure 4 CCF CLC

Claims (2)

[Claims] (1) One of the two substrates constituting the liquid crystal panel has a collar formed by covering metal wiring formed on a transparent substrate and at least between the metal wiring in the display section of the liquid crystal panel. It consists of a transparent insulating film formed by covering a filter, the metal wiring, and the color filter, and a transparent electrode formed on the insulating film, and the metal wiring and the transparent electrode cover the color filter. A color liquid crystal panel characterized in that the panel is electrically connected by an organic polymer semiconductor formed in at least one of the insulating films. (2) The color liquid crystal panel according to claim 1, wherein the organic polymer semiconductor is formed by electrolytic polymerization.