JP2001343661A - Horizontal electric field type color liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformize dispersion of cell gap spacers by maintaining uniformly an electrification charge of a layer of each RGB color of a color filter substrate for a horizontal electric field type to reduce defective display by dispersion ununiformity in a manufacturing process of a color liquid crystal display element of the horizontal electric field type. SOLUTION: In the color liquid crystal display panel of the horizontal electric field type, the resistivity of the layer of each of R, G and B colors at the color filter side is uniformized so that the conditional expression being the maximum resistivity/minimum resistivity<=6×102 may be satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color liquid crystal display device, and more particularly, to a lateral electric field (In-Plane-Switch).
The present invention relates to a color filter substrate in a color liquid crystal display device of the type (hereinafter, abbreviated as "ching", hereinafter referred to as IPS).

[0002]

2. Description of the Related Art Red (R), green (G), and blue (B) color layers are formed on a color filter (CF) substrate of a color liquid crystal display device. A technique has been established in which each of these color layers is formed by appropriately adding an additive such as a pigment and a dispersant to a transparent resin such as an acrylic resin in order to obtain a desired chromaticity. In addition, since the substrate surface on which the color layers are formed is required to be as flat as possible in order to realize a uniform cell gap, each color layer is formed to have the same thickness.

As described above, when the chromaticity and the film thickness of each color layer are to be satisfied with priority, the specific resistance of each color layer is largely different, and a variation of about 10 ⁷ to 10 ¹⁴ (Ω · cm) occurs. . In particular, it is known that the red layer has a much higher specific resistance than the green layer and the blue layer. It is also known that a large difference in the specific resistance results in a difference in the amount of charge, and when the dispersion of the spacer particles is performed by the dry dispersion method, the distribution of the spacers varies, thereby causing a problem of deteriorating the display performance.

In Japanese Patent Application Laid-Open No. 11-38420, as a means for solving such a problem, a light-shielding portion and a spacer are arranged so that the dispersed spacer particles are selectively sprayed only on a light-shielding portion such as a black matrix. Means for charging the particles to the opposite polarity is used.

On the other hand, Japanese Patent No. 3044788 does not cover the IPS system, but reduces the effect of voltage drop in the color layers by lowering the specific resistance of each color layer in a color filter for a liquid crystal display device. Suggest to do. For example, by dispersing ITO particles in each color layer, the specific resistance of the R, G, and B layers can be reduced by 10%.
It is disclosed to be ⁸ (Ω · cm) or less.

[0006]

However, if the specific resistance of each color layer is significantly reduced as in this patent publication,
Lateral electric field is not applied, IPS mode driving is not possible,
It cannot be applied to a horizontal electric field type color liquid crystal display device.

[0007] Accordingly, an object of the present invention is to ensure that the desired chromaticity can be satisfied as long as the specific resistance of each color layer is not excessively lowered, and that the spacer distribution becomes uniform even when the spacers are dry-sprayed. Another object of the present invention is to provide a color filter having a color layer.

According to the present invention, the specific resistance of each color layer is 10 ¹⁰ (Ω ·
cm) or more, and the combination of the respective color layers is selected so that the specific resistance ratio between the respective color layers is not more than 600, so that the chromaticity of each color layer is satisfied and the spacer distribution does not affect the display characteristics. What I can do is based on what I found through experiments.

SUMMARY OF THE INVENTION An object of the present invention is to provide a color liquid crystal display device of the IPS system, which is capable of reducing the dispersion unevenness of spacer particles due to uneven charging of the color layer.

[0010]

The IPS type color liquid crystal display device of the present invention is provided on a substrate and is provided with a red (Re)
d) a color layer constituting the three primary colors of green, green and blue, a black matrix provided on the substrate and filling at least the space between the color layers, and the color layer and the black matrix. A color filter substrate having a color filter substrate comprising an insulating film covering the surface of the substrate, wherein the relationship between the maximum value and the minimum value of the specific resistance of the color layer is such that the maximum value is the minimum value 6 × 10
^This is based on the finding that by setting it to twice or less, display unevenness due to spacer scattering unevenness hardly occurs.

According to the present invention, a color filter substrate arranged so that each of the red, green, and blue layers is separated by a black matrix layer, and a color filter substrate facing the color filter substrate via a particulate spacer. An in-plane switching type color liquid crystal display device comprising: an electrode substrate having a pixel electrode disposed therein; and a liquid crystal layer sandwiched between the color filter substrate and the electrode substrate. A horizontal electric field type color liquid crystal display device characterized in that the ratio of the maximum value to the minimum value is 6 × 10 ² or less.

[0012] The present invention is also characterized in that the particulate spacer is dry-sprayed. Further, the color filter substrate is characterized in that the respective color layers and the black matrix layer are commonly covered by an overcoat layer. Further, an alignment film is formed on the overcoat layer. Further, each of the color layers has a composition in which a pigment and a dispersant are contained in a transparent resin.

Further, according to the present invention, a color filter substrate arranged so that each color layer of a red layer, a green layer and a blue layer is separated by a black matrix layer, and the color filter substrate via a particulate spacer And an active matrix substrate having a plurality of pixel electrodes and a common electrode connected to a plurality of switching elements, respectively, and a liquid crystal layer sandwiched between the color filter substrate and the active matrix substrate. A horizontal electric field color liquid crystal display device, wherein the ratio of the maximum value to the minimum value of the specific resistance of each color layer is 6 × 10 ² or less. Can be

In the present invention, the specific resistance of each color layer is 10 ¹⁰ (Ω · cm) or more, preferably 1 × 10 ¹¹ to 1 ×.
It is desirable to be within the range of 10 ¹⁶ (Ω · cm). More preferably, the red layer has a specific resistance of 1 × 10 ¹³ to 1 ×.
10 ¹⁴ (Ω · cm), and the specific resistance of the green layer and the blue layer is 1 × 10 ¹² to 1 × 10 ¹³ (Ω · cm).

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS.

The color filter substrate shown in FIG.
R layer (red layer) patterned on glass substrate 1
3, a G layer (green layer) 4 and a B layer (blue layer) 5. A black matrix 2 is formed at the overlapping portion of each color layer, and is configured to block transmitted light.

An overcoat layer 6 is formed on each color layer to cover them in common. Overcoat layer 6
Reduces the unevenness of the color layer and prevents elution of impurities from the color layer. Further, an alignment film 7 is formed on the overcoat layer 6.
Is formed.

Although not shown, the basic configuration of the in-plane switching type color liquid crystal display device is described in
As disclosed in Japanese Patent No. 38420, the color filter substrate has an active matrix substrate opposed to the color filter substrate via a spacer and a liquid crystal layer. Needless to say, the active matrix substrate for the horizontal electric field type is composed of a plurality of TFs in a matrix on a glass substrate or the like.
A switching element such as T is arranged, a pixel electrode is connected to each switching element, and a pixel region is formed between the switching element and a common electrode provided in parallel with each pixel electrode.

Before describing the embodiments of the present invention, the conventional problems will be described in detail with reference to FIG. 1 with a view to better understanding the present invention.

In the color filter substrate for IPS shown in FIG. 1A, since the conductive film cannot be provided on the inner surface side of the substrate due to the structure of the IPS, the inner surface side of the substrate is charged in the manufacturing process of the liquid crystal display element. For example, as shown in FIG. In this case, the specific resistance of the black matrix is generally about 10 ⁵ (Ω · cm), which is the lowest as compared with the color layer. A charge is induced.

At this time, if the difference between the specific resistances of the R, G, and B color layers is large, the injection of charges is biased, and the positive charges formed on the surfaces of the R layer 3, the G layer 4, and the B layer 5 are formed. Variations occur in the charge distribution of the charges (FIG. 1C).

On the other hand, dry spraying is generally used for spraying spacers for forming a cell gap. This technique is
This is a method of uniformly dispersing the spacer particles by charging and dispersing the individual spacer particles. As shown in FIG. 1C, if there is uneven charging in each pixel, it appears as uneven scattering of the spacer particles.

The IPS mode liquid crystal display element is normally black, and spacers in pixels have the property of transmitting light. Therefore, the density of the spacers significantly lowers the display quality. As described above, the IPS color layer cannot be provided with a conductive film on the inner surface of the substrate. Therefore, an ITO film 8 which is a transparent conductive film is provided on the outer surface on the back surface side to prevent charging. The ITO film 8 is effective in preventing charging from the back surface in a manufacturing process such as transporting the substrate, but is not sufficiently effective in charging the inner surface of the substrate. For this reason, charge is injected into each color layer due to charging on the inner surface of the substrate, and if the specific resistance unique to each color layer varies greatly, bias of the charged charge occurs, leading to display failure. In addition, the charge injected into each color layer does not become uniform for more than one hour at room temperature even if the charge is removed by an ionizer or the like.

Based on such conventional problem recognition, the present invention reduces the above-mentioned display defects by combining the color layers so that the specific resistance difference between the R, G, and B color layers is kept within a certain range. is there. The specific resistance of each of the R, G, and B color layers is
Experiments have shown that by selecting a material that satisfies the following equation (Equation 1), it is possible to prevent bias of charge injection into each color layer and to achieve uniform spacer distribution.

Maximum specific resistance value / minimum specific resistance value ≦ 6 × 10 ² (Equation 1) FIG. 2 shows the display unevenness occurrence rate with respect to the maximum value / minimum value of the specific resistance of each color layer. FIG. 2 shows the case where the color filter substrate of the present invention is used for an IPS mode color liquid crystal display device based on data confirmed by experiments, where the value of the maximum specific resistance / minimum specific resistance is 6 ×. It was confirmed that when the value exceeds 10 ² , the number of display defects sharply increases.

It should be noted that Japanese Patent Laid-Open Publication No.
According to Japanese Patent Publication No. 1-38420, the resistivity (Ω · cm) of the red, green, and blue colored resins is 8.7 × 10 ¹⁵ and 1.1, respectively.
An example of × 10 ¹³ , 1.8 × 10 ¹³ is disclosed.
In this example, the specific resistance of the red colored resin is the largest and the specific resistance of the green colored resin is the smallest, so that the ratio is 7.9 ×
The 10 ^2. However, as shown in FIG. 2, since the value exceeds the value defined in the present invention, it is difficult to reduce the display unevenness occurrence rate to zero.

As described above, the IPS type color liquid crystal display device is characterized in that when the display unevenness occurrence ratio with respect to the specific resistance ratio exceeds a certain value, a steep change is exhibited. That is not seen with the device.

Further, Japanese Patent No. 30447 cited in the conventional example.
In Japanese Patent Publication No. 88, the specific resistances of the R, G and B layers are set to 10 ⁸ (Ω · cm), 10 ⁷ (Ω · cm) and 10
⁷ (Ω · cm) is disclosed, and the maximum / minimum ratio of the specific resistance is small. However, as described in the description of the conventional example, the specific resistance of each color layer is small, so that the IPS method is used. It is not suitable for application to a color liquid crystal display device.

According to the present invention, the maximum value and the minimum value of the specific resistance of each color layer are determined.
Not only does the ratio with the value satisfy the above equation (1), but also for each color.
The specific resistance of the layer is 10^Ten(Ω · cm) or more, preferably 1 ×
10 ¹¹~ 1 × 10¹⁶(Ω · cm)
By determining the combination of each color, IPS color
It can be applied to liquid crystal display elements.

Each color layer employed in the present invention is formed by dispersing a pigment in a transparent resin such as conventionally known acrylic resin, and the specific resistance of each color layer depends on the pigment concentration and additives such as a dispersant. Since the technology for determining the desired value has already been established, the details thereof are omitted here.

In order to control the specific resistance, for example,
There is a method of adjusting the components of the pigment or the components of the dispersant. As another method, a method of adjusting the pigment concentration is also possible, but in order to obtain a necessary chromaticity, the thickness of the color layer is simultaneously adjusted. Further, as another method, a method of adjusting the thickness of the color layer is also possible. This adjustment inevitably causes unevenness in the film thickness of each color layer, but the overcoat layer can reduce the unevenness, and there is no problem. It is also possible to selectively control the resistance by the pigment concentration, the dispersant concentration, and the like.

Further, as a method of controlling the specific resistance, a method in which two or more of the above methods are arbitrarily selected and combined may be used. Further, adjustment for obtaining the chromaticity required for the color layer is generally performed depending on the pigment and the pigment concentration other than the film thickness.

In a preferred embodiment of the present invention, the specific resistances of the respective color layers are designed to be close to each other within a range where the specific resistance does not largely change from the standard specific resistance of the respective color layers which achieves a preferable chromaticity. That is, the specific resistance of the red layer is reduced within a range that satisfies the desired chromaticity, and the specific resistance of the green layer and the blue layer is increased within the range that satisfies the respective chromaticities. If the specific resistance is determined so as to satisfy the expression (1), the above effect can be achieved without largely deviating from the predetermined chromaticity.

As described above, the difference in the specific resistance of each color layer on the color filter substrate side for the IPS mode liquid crystal display element is 6 ×
By setting the value to 10 ² or less, the influence of charging in the manufacturing process of the IPS mode liquid crystal display element can be prevented. Thereby, it is possible to eliminate the density unevenness in the spacer application. The non-uniformity of the spacer distribution causes display defects such as brightness unevenness and color unevenness of the liquid crystal display element. In particular, in the case of the IPS mode liquid crystal display element, such a display error becomes remarkable. Display defects can be reduced by the combination of layers.

As a method of forming the spacer, in addition to the spraying method described in the above embodiment, a spacer is provided on the light shielding portion for improving the display quality as shown in the above-mentioned JP-A-11-38420 as a conventional example. Is selectively arranged. In this method, the spacer can be concentrated on the light-shielding portion by giving a charge having a polarity different from that of the spacer to the light-shielding portion. However, the present invention is also applicable to a method of manufacturing a liquid crystal display element using this method. By applying the combination configuration of the color layers according to the embodiment, it is possible to prevent the spacer scattering unevenness due to charging.

[0036]

As described above, by using the combination of the color layers of the present invention, the difference in the specific resistance value of each color layer in the color filter substrate for the IPS mode color liquid crystal display element can be reduced, thereby reducing the manufacturing process. In this case, the influence of electrification can be prevented, and density unevenness in spacer application can be eliminated. Accordingly, display defects such as luminance unevenness and color unevenness of the IPS mode color liquid crystal display element can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a state of charging on a color filter substrate side of a liquid crystal display element.

FIG. 2 is a graph showing the dependence of the display unevenness occurrence ratio on the ratio of the maximum specific resistance value / minimum specific resistance value of the color layer, which is the basis for obtaining the color layer on the color filter substrate according to the embodiment of the present invention. is there.

[Explanation of symbols]

 Reference Signs List 1 glass substrate 2 black matrix 3 R layer 4 G layer 5 B layer 6 overcoat layer 7 alignment film 8 ITO film

Claims (6)

[Claims] 1. A color filter substrate disposed so that each color layer of a red layer, a green layer, and a blue layer is separated by a black matrix layer, and a pixel disposed opposite to the color filter substrate via a particulate spacer. An in-plane switching type color liquid crystal display device comprising: an electrode substrate having electrodes; and a liquid crystal layer sandwiched between the color filter substrate and the electrode substrate, wherein a maximum value and a minimum value of the specific resistance of each color layer are provided. A lateral electric field type color liquid crystal display device, wherein the ratio of the value to the value is 6 × 10 ² or less. 2. The in-plane switching mode liquid crystal display device according to claim 1, wherein said particulate spacers are dry-sprayed. 3. The in-plane switching type color liquid crystal display device according to claim 1, wherein the respective color layers and the black matrix layer of the color filter substrate are commonly covered by an overcoat layer. 4. An in-plane switching mode color liquid crystal display device according to claim 3, wherein an alignment film is formed on said overcoat layer. 5. The in-plane switching type color liquid crystal display device according to claim 1, wherein each of the color layers has a composition in which a pigment and a dispersant are contained in a transparent resin. 6. A color filter substrate arranged so that each color layer of a red layer, a green layer, and a blue layer is separated by a black matrix layer; and a color filter substrate arranged to face the color filter substrate via a particulate spacer; A lateral electric field type color liquid crystal comprising: an active matrix substrate having a plurality of pixel electrodes and a common electrode respectively connected to a plurality of switching elements; and a liquid crystal layer sandwiched between the color filter substrate and the active matrix substrate. A display element, wherein a ratio between a maximum value and a minimum value of specific resistance of each color layer is 6 × 10 ² or less.