JPH0330127B2 - - Google Patents

Description

[Detailed description of the invention]

<Technical Field> The present invention relates to a color liquid crystal display device, and particularly to an electrode structure for color display. <Prior art> As a color liquid crystal display device that has a relatively simple liquid crystal panel structure, is capable of full-color display, and has good display quality with almost no color shift due to the thickness of the glass substrate used in the panel, liquid crystal Liquid crystal display devices in which multicolored color filter layers are arranged in an array inside the panel have already been commercialized. Among these, the panel structure of a typical color liquid crystal display device is shown in FIG. Two opposing glass substrates 1
A signal-side transparent electrode 2 and a scanning-side transparent electrode 2' constituting a matrix electrode are formed on opposing surfaces of the substrate, and an alignment layer 3 is coated thereon. Three primary color filter layers 4, 4', 4'' of red, green, and blue are superimposed on the transparent electrode 2 on the signal side, and a twisted nematic material is formed between the alignment layers 3 of both glass substrates 1. A liquid crystal 5 is interposed, and a color display is performed by an optical effect based on the orientation change of liquid crystal molecules in response to the application of an electric field.A polarizing plate 6 is provided outside the glass substrate 1 to visualize the orientation change of the liquid crystal molecules. are arranged with the polarization directions parallel. 7 is the polarization direction, 8 is a power supply connected to the transparent electrodes 2 and 2', and 9 is an incandescent lamp, fluorescent lamp, and EL lamp installed on the back side. 10 indicates an observer. In the panel structure shown in FIG. 2, color filter layers 4, 4', and 4'' are formed on the transparent electrode 2. As shown in the applied voltage vs. light transmittance characteristics, the color filter layer 4,
Due to the voltage drop at 4′, 4″, the characteristic curve changes from 1 ₁ to 1 ₂
There is a problem that the threshold voltage Vth increases as the voltage changes. Note that curve ₁₁ in the figure is the applied voltage versus light transmittance characteristic curve when there is no color filter layer, and curve ₁₂ is the applied voltage versus light transmittance characteristic curve when there is a color filter layer. In the XY matrix display device using liquid crystal,
In order to display a large amount of information, the number of electrodes inevitably increases. In this case, not only the signal side electrodes but also the scanning side electrodes are increased. Therefore, the operation period allocated to one scanning electrode within a certain frame frequency is shortened, and the display contrast is reduced. By the way, there are two ways to drive an XY matrix liquid crystal panel that can display a large amount of information.
Two typical driving methods can be considered. (1) Active matrix method in which a switching element is added at the intersection of each electrode crossed in the XY direction on one substrate surface (2) The ratio of the effective voltage applied to the liquid crystal (operating margin) ) is a voltage averaging method that optimizes the bias voltage to maximize . With method (1) above, substantial static drive is possible and sufficient voltage can be applied when turned on, so
Although good display contrast can be obtained, since thin film transistors are formed as switching elements at the intersections of XY electrodes, the process is extremely complicated compared to conventional liquid crystal panels, and it is difficult to produce switching elements with uniform characteristics. The problem is that it is difficult. On the other hand, in method (2), as the number of scanning electrodes N increases, the ratio of the effective voltage applied to the liquid crystal during on/off

[Polysiloxane with amino group]

[Diacid anhydride]

【formula】

[Formula] After coating, baking is performed at about 200° C. for 1 hour to obtain a protective film 11 as shown in FIG. 5(B). On this protective film 11, for example, indium oxide is deposited as a transparent conductive film 2 by ion plating as shown in FIG. 5(C). In this case, the deposition condition is the substrate temperature
200℃, vacuum degree 4×10 ^-4 torr (O ₂ leak) film thickness 2000
The settings were ~3000 Å, speed ~5 Å, and sheet resistance 20 Ω or less. This transparent conductive film is patterned through the following steps. That is, a photoresist 12, AZ1400-31 (manufactured by Shupley Co., Ltd.), is coated with a spinner as shown in FIG. 5(D). This photoresist is prebaked at 90° C. for 25 minutes and then exposed using a prescribed mask 13 as shown in FIG. 5(E). Next, development is performed using a developer having a ratio of AZ developer: water = 1:1 to obtain a resist electrode pattern 14 as shown in FIG. 5(F). Then 30 at 140℃
After post-baking for a minute, the transparent conductive film 2 is etched using an HCl-FeCl ₃ based etchant as shown in FIG. 5(G). After the etching of the transparent conductive film 2 is completed, the resist is peeled off by ultrasonic cleaning in an acetone solvent to form a transparent electrode that will become one electrode group of the matrix electrode structure as shown in FIG. 5(H). Get 2. The glass substrate 1 having the electrode structure obtained through the above steps is used as one liquid crystal panel substrate of a liquid crystal display device, and the other liquid crystal panel substrate is used as a glass substrate on which transparent electrodes 2' are formed as shown in FIG. ,
Transparent electrodes 2 and 2' are orthogonally arranged and both glass substrates 1 are opposed to each other. There is a second layer on the surface of the transparent electrodes 2 and 2'.
As in the figure, a liquid crystal molecule alignment layer 3 is layered and twisted nematically aligned liquid crystal 5 is sealed to form a liquid crystal panel. A matrix electrode structure is formed by the transparent electrodes 2 and 2' formed on both glass substrates 1, and red, red, and white electrodes correspond to each intersection of the matrix.
The green and blue color filter layers 4, 4', and 4'' are sequentially and regularly arranged. Therefore, by selecting the transparent electrodes 2 and 2' and applying a voltage, a matrix type full color display can be performed. In this case, the color filter layers 4, 4', 4'' are interposed between the transparent electrode 2 and the glass substrate 1, and the liquid crystal 5
Since it is located outside the electric field applied to the liquid crystal, the effective electric field strength applied to the liquid crystal does not decrease and the threshold characteristic does not increase. The orientation of the liquid crystal molecules in the portion of the liquid crystal 5 to which the electric field is applied is changed, and the optical effect based on this is made visible by a polarizing plate provided outside the liquid crystal panel. The protective film 11 between the color filters 4, 4', 4'' and the transparent electrode 2 is tightly adhered to the underlying layer without peeling off, and the color filter layers 4, 4',
The transparent electrode 2 formed thereon is easy to pattern and becomes a highly precise molded body. <Effects of the Invention> As explained in detail above, the upper part of the color filter layer is heated to about 200°C. By providing a polysilicone imide film that completely polyimideizes the film, and then applying a transparent conductive film on top of that film using an ion plating method to form patterned electrodes, the drop in voltage applied to the liquid crystal due to the color filter layer is eliminated. At the same time, it became possible to form transparent electrodes with low resistance required for high-duty driving, eliminating cracks and peeling of the color filter layer.With this electrode structure for color display, voltage can be efficiently applied to the liquid crystal layer. is applied, and uniform full-color display with excellent display contrast is performed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the main part of an electrode structure for explaining one embodiment of the present invention. FIG. 2 is a block diagram of a conventional color liquid crystal display device. FIG. 3 is a transmittance-voltage characteristic diagram showing that the threshold voltage is increased by providing a color filter layer. FIG. 4 is a sectional view illustrating an electrode structure in which a transparent electrode is provided on a color filter layer. FIG. 5 is a manufacturing process diagram of the color filter side substrate shown in FIG. 1. 1... Glass substrate, 2, 2'... Transparent electrode, 3
...Alignment layer, 4,4',4''...Color filter layer (red, green, blue), 5...Liquid crystal, 6...Polarizing plate,
7...Polarization direction, 8...Power supply, 9...Incandescent lamp, 1
0... Observer, 11... Protective film.

Claims (1)

[Claims] 1. A color filter layer is arranged on the inner surface of a substrate constituting a liquid crystal display panel, a polysilicone imide layer covering the color filter layer is provided as a protective layer, and an electrode layer of a transparent conductive film is formed on the protective layer. Characteristic liquid crystal display device.