JPS61143725A - Colored liquid crystal panel - Google Patents

Abstract

PURPOSE:To depress a resistance of a metallic wire, thereby solving an increase of the resistance of an inside type filter structure part and its wire by connecting a transparent electrode covered with the colored filter to a metallic wire composed of a stripped film formed at a nondisplay area of the titled panel which does not form any image. CONSTITUTION:The stripped metallic wire 61 is formed at a nonimage part of the display P provided on a side of the glass substrate 21. The stripe is formed on the nondisplay parts lying on both sides interposing the display part. By making a thickness of the metallic wire 61 thin, the resistance of said wire depresses, and the color filter 23 is formed on the glass substrate 21 or the metallic wire 61 of the display part. The transparent protective film 51 is formed by coating the filter 23 and the wire 61 at the display part. The transparent electrode 31 is formed on the film 51. The electrode 31 is connected with the wire 61, thereby depressing the resistances of the inside type filter structure part and its wire.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a liquid crystal panel for displaying multicolored natural colors.

[Background of the invention]

In recent years, with the development of various information devices such as computers and televisions, the role of display devices as information output terminals has become increasingly limited.

Traditionally, Cl ('l' (liquid crystal display)) has been most widely used as this display device, but in recent years, LCL (liquid crystal display) has been widely used due to its thinness and low power consumption. The proportion of the population is rapidly increasing. On the other hand, it goes without saying that it is generally preferable for a display device to have a color display because it appeals to the human sense of sight (.Therefore, the need for color LCDs has become extremely large.

Prior Art and Problems] Various ideas have been made to realize color LCDs. Examples of these methods include the ECB (electrically controlled birefringence) method, the guest-host method, the birefringent film-TN (twisted nematic) method, and the optical rotation dispersion-cholesteric method, but from the viewpoint of natural color display performance and structural reliability. At present, liquid crystal is used as a light shutter, and color LC1, which is a combination of this and the three primary color filters of red (I), green (Gl), and blue (BL), is the most promising.

FIG. 1 is a conceptual diagram for explaining the general operating principle of a color filter type color LCL. White incident light 16 passes through a color filter 11, and after the spectral components are selected, the light The amount of transmitted light is adjusted on the liquid crystal panel 12, which is the shutter, and the human eye
5 is the output light 14 (R and G are transmitted here, and it is yellow ~
(yellow-green color) is observed. Note that the relative positional relationship between the color filter 11 and the liquid crystal panel 12 with respect to the incident light 16 may be reversed.

FIG. 2 shows the prior art, and is a cross-sectional view showing where color filters are formed in a liquid crystal panel.A color filter 26 is formed on a liquid crystal panel composed of opposing glass plates 21 and 22 and a liquid crystal layer 24. Figure 2 (a
1 is a type in which 26 color filters are formed on the outside of the liquid crystal panel (called an extrinsic type), and BL is a type in which color filters 26 are formed on the inside of the liquid crystal panel (called an internal type). The main differences between the two are that there is no need to take into account the reduction in reliability due to chemical interference with the liquid crystal layer of the color filter, and the external type is superior in terms of temperature and 5 points. The intrinsic 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 angle. Considering the trend toward higher density and higher definition, the problem of color mixing mentioned above must be said to be extremely serious, and it is strongly desirable to create color LCDs using an internal type in which color filters are formed inside the liquid crystal panel. It is rare.

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

FIG. 3 is a sectional view showing the positional relationship between the transparent electrode and the color filter in the internal type shown in FIG. 2(b).
3 (bl), the color filter 26 is formed on the transparent electrode 61 on the glass plate 21 (referred to as the upper filter structure), whereas in FIG. A transparent electrode 61 is formed on top of the structure (referred to as a lower filter structure).
In FIG. 3 (bl), 32 is a transparent electrode on the glass plate 22. An important difference between the upper filter structure and the lower filter structure appears in the liquid crystal drive. An equivalent circuit of the filter structure is shown in Fig. 4. That is, the terminals 43 corresponding to the opposing transparent electrodes
．． Capacitance component cara due to color filter between 440 and 440
1 and the capacitive component CLc42 due to the liquid crystal layer are coupled in series, and the voltage applied between the terminals 46 and 44 is
The VLe, which is a part of the LCD, does not contribute to driving the liquid crystal. Expressing this quantitatively, VLe:V, -Cc, /(CLc+Ce,)...-
--- (II) Due to the influence of this voltage drop, in the upper filter structure, the voltage for driving the upper liquid crystal must be increased compared to the conventional liquid crystal panel. , the degree is usually 20% or more, and it is extremely serious.
In some cases, it can reach 100% or more. On the other hand, I
The operating withstand voltage of C (integrated circuit) is determined by characteristics such as latch-up, but the margin is at most 20 to 30%, and it is hardly applicable to the upper filter structure.

Furthermore, even if the conditions are met in terms of IC breakdown voltage, the optical characteristics of the liquid crystal itself will deteriorate in appearance because the (-LC of the il+ equation changes somewhat depending on the voltage applied to the liquid crystal. With the upper filter structure, the display performance is lower than that of conventional liquid crystal panels.Furthermore, in order to alleviate the problem of voltage drop due to one layer of color filters, it is possible to reduce the thickness of the color filters, but in this case The optical characteristics of the color filter itself as a filter deteriorates, which usually leads to a decrease in saturation.In this way, when trying to realize an upper filter structure, various serious problems tend to occur, and the root cause of these problems is likely to occur. can be said to be a voltage drop due to the color filter.Thus, from the perspective of a structure that is not affected by this voltage drop, the third
It is clear that the lower filter structure of Figure (bl) 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 conventional lower filter structure and its formation procedure in cross-section. First, the fifth
) (, G, 83 on the glass substrate 21 as shown in figure ta+)
A color filter 23 of color is formed, and then FIG.
An insulating transparent protective film 51 is formed to separate the color filter and the liquid crystal layer as shown in FIG.
A transparent conductor is formed as shown in C1, and the transparent conductor is patterned using photophosphorography technology to form a transparent electrode 31. Here, the transparent protective film 51 is usually made of an organic polymer compound. transparent conductor is usually I
Although it is TO (Indium-Tin-Oxide),
There is a color filter (・ is an IT
O must be formed at a much lower temperature than conventional conditions, which were approximately 300'C or higher. On the other hand, ITC formed at low temperature is 2 to 3 times thicker in terms of resistivity than ITO formed at high temperature (this means that low resistance cannot be achieved unless ITO is formed very thickly, but if ITO is formed thickly, it becomes transparent). There are problems such as the etching rate decreases, etching becomes difficult, internal stress increases, and cracks occur. Lowering the resistance value is extremely important in maintaining image quality, and even when using ITO formed at high temperatures, current efforts are being made to further lower the resistance by layering some metal wiring. It's a situation.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to solve the drawbacks of the prior art and to provide a new structure that solves the problem of increased resistance of electrodes and wiring in the internal filter structure.

[Embodiment of the Invention] FIG. 6 is for explaining a color LCD according to an embodiment of the present invention.
, (C1 is a cross-sectional view taken along A-A and B-B in FIG. The other transparent substrate is one used in ordinary simple matrix driven liquid crystal panels, that is, a glass substrate on which transparent electrodes are formed.

However, other configurations of the other transparent substrate include those for active matrix driving in which two-terminal active elements such as diodes are regularly arranged on a transparent substrate such as glass.

In the structure of the present invention, first, as shown in FIG. 6(a), a pattern is formed on a transparent substrate 21 in a non-display area when used as a liquid crystal panel to facilitate connection with an external circuit. In the display portion, a metal arrangement a61 forming a striped pattern running between pixels is formed. The method for forming the metal wiring 61 is to deposit metal, then
The most common method is to perform etching using photolithography technology, but this method reduces the thickness of the wiring layer to 1 μm.
On the other hand, there are problems in terms of economy and film adhesion when increasing the thickness of the metal wiring layer, since it is advantageous for driving the liquid crystal panel to lower the resistance value of the metal wiring layer.
It is preferable to set it to μ or more. Therefore, when the thickness of the metal wiring 61 is desired to be 1 μm or more, it is effective to use a plating method as well.

Next, a color filter 26 is formed in a region of the glass plate 21 that will become a display part when used as a liquid crystal panel. In this case, the IC is designed to fill the space between the metal wiring lines 61 with the color filter 23.2. metal wiring 6
There is no problem if the entire part of ℃ 1 is covered with the color letter 26.

The car T-filter 26 is formed in a mosaic or stripe shape, but it is preferable that the film thickness of the filter A- is good, and it is preferable to use a color filter made of dyed gelatin thin film or a spinner-coated type. dyed resin color filters etc. show good properties. Furthermore, a color filter formed by printing or vapor deposition can also be used.

Continuation (・The color filter 23 is covered with a transparent protective film 5.
Cover with 1. The protective film 51 is preferably formed to exactly cover the entire color filter 23, and at the same time, the exposed portions of the metal wiring 61 in the display area are also covered. However, most of the metal wiring 610 is not exposed on the outside of the surface of the display area. Molecular membranes, silicon oxide,
Inorganic films such as organic silicon and aluminum oxide are used. However, the function of the protective film 51 is to prevent impurities (especially ionic impurities) from entering the liquid crystal layer from the color filter 26, and also to prevent impurities from entering the color filter 26.
Because it also has the purpose of flattening the uneven structure of
It is more preferable to apply a polymeric substance and take advantage of its thixotropic properties.

Finally, a transparent conductor layer is formed on the glass plate 21 and patterned by etching to form a transparent electrode 61. In this case, the transparent conductor layer is usually I
TU is selected, but in this case there is a color filter 26 (* means that the protective film 51 has already been formed (), so it must be formed at a low temperature of approximately 200° C. or less. Formation of ITO at this low temperature Methods include vapor deposition, splattering, ion blating, etc., and the transparent electrode 31 can be formed using any of these methods.In this way, the transparent electrode 31 is mainly formed in a stripe shape on the protective film 51, but the method of the present invention What is important in the structure is that the metal wiring 61 and the transparent electrode 61 are electrically connected in the non-display area immediately outside the display area.

This state is clear in FIG. 6(C), and such connection points are two points P and Q on both sides of the display portion.

FIG. 7 is a diagram for explaining another embodiment of the color LCD according to the present invention. This embodiment is the same as the embodiment shown in FIG. 6, but the biggest difference is that the metal wiring 61 in FIG. The reason is that the conductor wiring 71 is used to replace the bulk.In this case, since the wiring itself is transparent,
The area below the pixel can be used in the display area, and this situation is clearly seen in Figure 7 (al).The transparent conductor wiring 7
1 must be formed with relatively low resistance, usually 1000
An IT film with a thickness of A or more and heat treated at 300°C or more will be used. The subsequent formation procedure and contents are almost the same as those explained in Fig. 6, and as shown in Fig. 7 (C1), the out-of-plane !l! 1l (
At points P and Q), transparent conductor wiring 71 and transparent conductor 3
1 is electrically connected.

After the thus formed substrate shown in FIG. 6 or 7 is subjected to a normal alignment treatment, it is stacked on a counter substrate to form a liquid crystal cell. At this time, the counter substrate is generally a striped IT (Ji electrode) formed on a glass substrate, but it is also common to use an active substrate with regularly arranged two-terminal nonlinear elements such as diodes. A matrix substrate may also be used.

Next, one embodiment of the present invention will be described in more detail.

30OA of chromium and 5000OA of nickel on a glass substrate
After continuous vapor deposition in the order of
Wiring was formed on the patterned gold to directly mount the C1rcuit. Next, on the display area of the glass substrate, a thin film of noselatin is dyed to form a color filter with a thickness of 2μ in a mosaic pattern, and a polyimide-based transparent insulating film with a thickness of 1μ is coated just above this. A protective film was formed. This protective film is cured at temperatures below 200°C, and was actually heat treated at 180°C for 2 hours. Finally, without raising the substrate temperature, an I'r film with a thickness of 1000 A was formed using Subanotary/G, and a striped transparent electrode was formed using photolithography. At this time, the transparent electrode and the chromium/nickel metal wiring are selectively electrically connected to each other on the outside of the surface of the display area. After the above steps, the transparent electrode and the chromium/nickel metal wiring are subjected to a normal liquid crystal alignment process, and then the color One liquid crystal panel was formed, and the opposite substrate at this time was a glass substrate on which striped ITU electrodes were formed and aligned.

For the color LCD completed in this way, the IC for the liquid crystal GA was fixed to the predetermined position of the chromium/nickel metal wiring using conductive paste, and then connected to the external control circuit system. , I checked the image. As a result, the resistance value of the input section or pixel section of the liquid crystal panel was high (・There was almost no display unevenness that sometimes occurs, and the display quality was good. Furthermore, since it is an internal filter, it No color mixing occurred when viewed from above.

〔Effect of the invention〕

According to the present invention, there is no color mixing when viewed from an oblique direction as seen in conventional color LCDs with external color filters, and there is no need to increase the liquid crystal driving voltage, which is a problem with the upper filter structure. Prevents deterioration in image quality. In addition, in panels with a lower filter structure, transparent electrodes must be created in a low-temperature process, which tends to increase wiring resistance and, in turn, lower image quality due to insufficient liquid crystal drive. According to the present invention, the connecting portion with the liquid crystal drive circuit is made of a low-resistance metal wiring or a low-resistance transparent conductor, and the metal or transparent conductor wiring is provided in parallel with the transparent electrode in the display area. It is also possible to reduce the resistance of the electrodes, and as a result, it is possible to sufficiently prevent deterioration in image quality.Metal wiring (* indicates transparent conductor wiring, which has high reliability) Although it is difficult to form at a low temperature, according to the present invention, since it is first formed on a glass substrate, there are no process restrictions and there is an advantage that the metal is formed at a low temperature. A structure using wiring has the secondary advantage that the metal wiring between pixels serves as a black line that separates adjacent color filters of different colors, which helps improve the saturation of color images. On the other hand, transparent conductor wiring can be formed under the pixel, which greatly increases the degree of freedom such as the thickness of the wiring, which is extremely advantageous in terms of process.Furthermore, transparent conductor wiring is usually made of oxide. Since it is formed from a semiconductor such as ITU, there is no problem of electrical connection failure due to surface oxidation in the case of metal wiring.

As described above, according to the present invention, a color LCL with good image quality can be easily produced with a high yield.

[Brief explanation of drawings]

Figure 1 is a structural conceptual diagram for explaining the operating principle of a color LCD using one type of color filter. A cross-sectional view explaining the positional relationship between the LCD panel and the LCD panel.
Figure 2 (ta) is the extrinsic type, Figure 2 (b) is the intrinsic type, Figure 3 (a) is the upper filter structure of the intrinsic type, 3g tb+ is the lower filter structure of the intrinsic type, and Figure 4 is the lower filter structure of the intrinsic type. 5 is an equivalent circuit diagram of the upper filter structure, FIG. Showing other examples,
6(a) and 6(b) respectively.
a), Fig. 7 (a) is a plan view, Fig. 6 (bl, Fig. 6 (
cl is shown in Figure 6 (A-A and B-B sectional view of al, 7th
Figure (bl, Figure 7 (C1 is Figure 7 (al) A-A and B
-B is a sectional view. 11.26...Color filter, 12...
... Liquid crystal panel, 21.22 ... Glass plate, 61.32 ... Transparent electrode, 51 ... Transparent protective film, 61 ... Metal wiring , 71...Transparent conductor wiring. Patent applicant Citizen Watch Co., Ltd. Figure 1 Figure 3 (b) Figure 4 1; + (CF CLC Figure 5 I (b) (C) (C)

Claims (2)

[Claims] (1) One of the two substrates constituting the liquid crystal panel is formed in a stripe shape in a non-pixel portion of the display area on the transparent substrate, and the stripe is located on both sides of the display area. a color filter formed on the transparent substrate or the metal wiring in the display area; and a color filter covering the color filter and the metal wiring in the display area. and a transparent electrode formed on the metal wiring and the transparent insulation film so as to be electrically connected to the metal wiring on each of the non-display areas. A color LCD panel characterized by: (2) One of the two substrates constituting the liquid crystal panel is formed in a stripe shape in the display area on the transparent substrate, and the stripe further extends to the non-display areas on both sides of the display area. a color filter formed on the transparent substrate or the transparent conductor wiring in the display area; and a color filter formed on the transparent conductor wiring in the display area; a transparent insulating film formed by covering the transparent conductive wiring and the transparent insulating film, and electrically connected to the transparent conductive wiring on each of the non-display areas. A color liquid crystal panel characterized by comprising a formed transparent electrode.