JP2006146263A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display whose display defects, especially the red color unevenness can be prevented, without complicating the manufacturing process of color filter. <P>SOLUTION: In the liquid crystal display of an IPS system or the like having a structure, wherein electrodes are not formed on a color filter side, electrostatic charge of a color layer is suppressed and generation of a display defect such as red color unevenness is prevented in advance, by limiting the concentration of a green pigment, such as a halogenated copper phthalocyanine pigment contained in the color layer, especially a green color layer, to be in a prescribed range and regulating a dielectric loss generated when an AC electric field is applied to the color layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and in particular, an IPS (In-Plane Switching) method for driving liquid crystal in a plane substantially parallel to a substrate by a voltage applied between a pixel electrode and a common electrode formed on a TFT substrate. The present invention relates to a liquid crystal display device having a structure having no electrode on the color filter substrate side.

  An active matrix type liquid crystal display device using a thin film transistor (hereinafter abbreviated as TFT) as a switching element of a pixel has a high quality image and is widely used as a monitor for a space-saving desktop computer. In general, the operation mode of a liquid crystal display device includes a twisted nematic (TN) system in which aligned liquid crystal molecules are rotated in a direction perpendicular to a transparent substrate, and a rotation in a direction parallel to the transparent substrate. There is an IPS method.

  The IPS liquid crystal display device alternately forms pixel electrodes and common electrodes having comb teeth parallel to each other on a transparent substrate on which TFTs are formed, and applies a voltage between them to generate an electric field parallel to the substrate surface. By forming it, the alignment direction of the liquid crystal is changed, and the transmitted light amount is controlled by this. Therefore, this display method has a feature that a liquid crystal molecule rotates in the substrate plane, so that a good image can be obtained from a very wide viewing angle.

  The structure of the conventional IPS liquid crystal display device will be described with reference to FIG. The IPS liquid crystal display device includes a first transparent substrate (TFT substrate) 1 on which TFTs are formed, a second transparent substrate (color filter substrate) 11 on which color filters are formed, and a liquid crystal 10 sandwiched therebetween. In the first transparent substrate 1, scanning lines and signal lines (not shown) are formed substantially orthogonal to each other, and TFTs (not shown) are arranged in a matrix at intersections between them. In each pixel, pixel electrodes 7 and common electrodes 3 which are parallel to each other are alternately formed. Further, on the second transparent substrate 11, a black matrix 12 for shielding excess light, a color layer 13 for performing RGB three-color display, and an overcoat layer 14 covering these are formed. .

  An alignment film 9 is applied to the surfaces of the first transparent substrate 1 and the second transparent substrate 11, and the liquid crystal is homogeneously aligned with a predetermined angle in the longitudinal direction of the pixel electrode 7 between the substrates. 10 is pinched. Further, polarizing plates 16a and 16b are attached to the outer sides of both substrates, the polarizing axes of both polarizing plates are orthogonal to each other, and one polarizing axis is set parallel to the alignment direction of the liquid crystal. Then, a potential is written to the pixel electrode 7 via the TFT, and a horizontal electric field is applied between the pixel electrode 7 and the common electrode 3, thereby controlling the display by twisting the liquid crystal 10 in a plane parallel to the substrate. ing.

  Conventionally, such liquid crystal display devices have been mainly used for monitors of notebook computers and desktop computers, but in recent years, they have been used for applications in the fields of television and multimedia. Accordingly, liquid crystal display devices are required not only to improve viewing angle characteristics but also to support a wide chromaticity range. Here, in television monitors and other devices used in the television field, image signal transmission methods including hues have been standardized, and NTSC (National, which is adopted by the United States, Japan, etc. as a representative example of this method. There are two types, the Television System Committee (European Broadcasting Union) method adopted by Europe, and in order to expand the liquid crystal display device to the television field, etc., the liquid crystal display device is manufactured to meet the above standards. There is a need to.

JP 2001-305332 A (page 3-14) JP 2000-186225 A (page 2-10)

  Conventionally, liquid crystal display devices have been manufactured to be compatible with the NTSC system with a chromaticity range of about 60%, but in order to be compatible with a wide EBU system with a chromaticity range of about 70%, It is necessary to improve the optical characteristics of the components of the apparatus, particularly the color filter, and for this purpose, it is necessary to use a color filter in which the type and composition of the pigment are adjusted.

  On the other hand, it is known that the liquid crystal display device has various display defects due to optical characteristics of constituent members, liquid crystal characteristics, etc., and a display defect called white unevenness as a display defect due to a color filter. There is. This white unevenness is a phenomenon in which when a black screen is displayed by applying a voltage to the electrodes, the uneven state is recognized because the transmittance of a part of the display area does not become zero, which is originally applied between the electrodes. It is considered that the reason why the generated voltage is to be maintained constant is that the presence of the ionic substance in the liquid crystal causes a current to flow through the ionic substance and the voltage between the electrodes drops.

  As a method for suppressing such white unevenness, for example, JP 2001-305332 A, JP 2000-186225 A, and the like disclose a method for suppressing display defects by paying attention to impurities contained in a color filter. ing. For example, in Japanese Patent Laid-Open No. 2001-305332, a resin member that constitutes a color filter that is in contact with a liquid crystal layer of a liquid crystal display device is considered to be one of the sources of ionic substances, and is transferred from the resin member into the liquid crystal layer. Focusing on the voltage holding ratio and residual DC of the liquid crystal that has been subjected to the impurity extraction process from the components constituting the resin member as a characteristic that correlates with display defects due to ionic substances, the impurities in the pigment and the resin composition are reduced. A method is disclosed.

  Although the ionic substance in the color filter can be reduced and white unevenness can be suppressed by the above method, display defects of the liquid crystal display device include a display defect called red unevenness in addition to the white unevenness. This red unevenness reduces the light transmitted through the green color layer among the color layers constituting the three RGB colors. As a result, the entire display screen appears reddish. This red unevenness is caused by ionic impurities. Therefore, the technique described in the above publication cannot prevent it.

  The present invention has been made in view of the above-mentioned problems, and its main object relates to a liquid crystal display device having a structure in which no electrode is formed on the side of a color filter substrate such as IPS, and the color filter manufacturing process is complicated. An object of the present invention is to provide a liquid crystal display device capable of preventing display defects of the liquid crystal display device, in particular, red unevenness, without being changed.

  In order to achieve the above object, according to the present invention, in a liquid crystal display device including a color filter substrate in which an electrode is not disposed on the liquid crystal holding surface side of the color layer, the green coloring composition constituting the color layer is copper. It contains a pigment having a phthalocyanine skeleton, and the weight ratio of the pigment to the green coloring composition is in the range of 19.9 to 27.0%.

  Further, the present invention provides a liquid crystal display device comprising a color filter substrate in which no electrode is disposed on the liquid crystal holding surface side of the color layer, and the green coloring composition constituting the color layer is a pigment having a copper phthalocyanine skeleton In a chromaticity range of 65% or more, the weight ratio of the pigment to the green coloring composition is in the range of 19.9 to 27.0%.

  Further, the present invention provides a liquid crystal display device comprising a color filter substrate in which no electrode is disposed on the liquid crystal holding surface side of the color layer, and the green coloring composition constituting the color layer is a pigment having a copper phthalocyanine skeleton The weight ratio of the pigment to the green coloring composition is in the range of 19.9 to 27.0%, and the dielectric loss factor of the color layer when an AC electric field of 100 Hz to 1 MHz is applied to the color layer However, the value of 100 Hz / minimum value of 100 Hz to 1 MHz <1.25 is satisfied.

  Further, the present invention provides a liquid crystal display device comprising a color filter substrate in which no electrode is disposed on the liquid crystal holding surface side of the color layer, and the green coloring composition constituting the color layer is a pigment having a copper phthalocyanine skeleton And the weight ratio of the pigment to the green coloring composition is in the range of 19.9 to 27.0%, and the dielectric loss factor of the color layer when applied to an alternating electric field of 1 MHz on the color layer is The value after applying a DC electric field to the color layer for at least 72 hours and applying electric field stress / value in initial state <1.6 is satisfied.

  Thus, the present invention provides a green pigment such as a copper halide phthalocyanine pigment contained in a color layer, particularly a green color layer, in a liquid crystal display device having a structure in which no electrode is formed on the color filter side as in the IPS system. By limiting the density of the light to a predetermined range, charging of the color layer can be suppressed and display defects such as red unevenness can be prevented.

  According to the liquid crystal display device of the present invention, in an IPS liquid crystal display device having no electrode on the surface of the color filter substrate, it is possible to prevent the occurrence of display defects such as red unevenness.

  The reason is that in an IPS type liquid crystal display device, since there is no electrode on the color filter substrate side, the lateral electric field that drives the liquid crystal penetrates the color filter, and in particular in the wide chromaticity color filter, the color layer is charged and displayed. This is because the influence of charging can be suppressed by setting the concentration of the G pigment to a predetermined value in the present invention.

  Red unevenness, which is one of the display defects of a liquid crystal display device, appears remarkably in an IPS mode liquid crystal display device having no electrode on the color filter side. Therefore, the present inventor diligently studied this problem, and there is no transparent electrode such as ITO on the surface of the color filter holding surface of the color filter substrate on which the color filter is formed. As a result, it was clarified that a horizontal electric field was applied to the color layer as a result of penetrating the substrate, and the color layer was charged to cause display defects.

  That is, the colored composition constituting the color layer contains a photoconductive phthalocyanine pigment, and when a lateral electric field driven by liquid crystal penetrates the color filter, a photo charge is generated in the color layer. A part of this photo charge deviates from the inside of the color layer through the black matrix, but the rest recombines or accumulates inside the color layer. It is considered that this accumulated charge disturbs the horizontal electric field for driving the liquid crystal and causes display defects.

  As described above, the red unevenness is caused by charging of the color layer, and thus cannot be suppressed even by using a coloring composition with few impurities as shown in the prior art. Therefore, the present inventor has found that red unevenness can be effectively prevented by using a physical property value correlated with the concentration of the pigment contained in the color layer and charging of the color layer. In particular, there is a correlation between the halogenated copper phthalocyanine pigment contained in the green coloring composition and the charge of the color layer. By limiting the concentration range of this pigment, the occurrence of red unevenness can be prevented and the complexity of the color layer can be prevented. It has been found that by measuring the dielectric constant, it is possible to evaluate the level of red unevenness that changes over time.

  Specifically, in order to prevent red unevenness, the green color layer (hereinafter abbreviated as G layer) needs to have no charge, and the copper halide contained in the green coloring composition of the G layer. The weight ratio of the phthalocyanine pigment (hereinafter referred to as G pigment) is 27% or less, and the dielectric loss factor of the G layer is flat in the low frequency region in the initial state (there is no lifting in the low frequency region) The increase rate of the dielectric loss factor is within a predetermined range even when a long-term electric field stress is applied. By satisfying these conditions, it is possible to provide a liquid crystal display device that does not generate an electric field that disturbs liquid crystal driving and has excellent display quality.

  Hereinafter, a specific description will be given with reference to FIGS. 1A and 1B are diagrams illustrating the structure of an IPS liquid crystal display device, in which FIG. 1A is a plan view of one pixel, and FIG. 1B is a cross-sectional view taken along line AA ′ in FIG. FIG. 2 is a diagram showing the correlation between the weight ratio of the G pigment and the level of occurrence of red unevenness, and FIGS. 3 to 6 are diagrams showing the frequency characteristics of the dielectric constant and dielectric loss factor of the G layer and their changes over time. It is. FIG. 7 is a diagram showing the correlation between the change in dielectric loss factor with time and the red unevenness level, and FIG. 8 is a diagram showing the correlation between the shape of the frequency characteristic of the dielectric loss factor and the red unevenness level.

  The effect of the present invention can be obtained with a liquid crystal display device having a structure without an electrode on the color filter substrate side, and a representative example is an IPS system. As shown in FIG. 1, the IPS type active matrix liquid crystal display device includes a signal line 6, a scanning line 2, a TFT 5 disposed at an intersection of the signal line 6 and the TFT 5 on the first transparent substrate 1, and connected thereto. The pixel electrode 7, the common electrode wiring, and the common electrode 3 connected thereto are arranged. The pixel electrode 7 and the common electrode 3 have a longitudinal direction in a direction parallel to the signal line 6, and by applying a potential difference therebetween, an electric field substantially parallel to the substrate can be applied in a direction perpendicular thereto. it can.

  In addition, each color layer 13 of RGB is formed on the second transparent substrate 11 in an array form such as a delta arrangement or a mosaic arrangement in a region facing each pixel formed on the first transparent substrate 1. The adjacent pixels are covered with a black matrix 12. An overcoat layer made of resin is formed on the color layer 13 and the black matrix 12.

  An alignment film 9 is applied to the surfaces of both substrates, and a liquid crystal layer 10 is disposed between the substrates. The liquid crystal layer 10 is homogeneously oriented in a direction that forms a predetermined angle with respect to the longitudinal direction of the pixel electrode 7. Further, polarizing plates 16a and 16b are attached to the outer sides of both substrates, the polarizing axes of both polarizing plates are orthogonal to each other, and one polarizing axis is set parallel to the alignment direction of the liquid crystal. A constant common potential is supplied to all the common electrodes 3 through the common electrode wiring, and the potential is written to the pixel electrode 7 through the TFT 5, and the liquid crystal 10 is twist-deformed by applying a lateral electric field, thereby controlling the display. To do.

  As described above, in the IPS system, the driving electric field of the liquid crystal 10 is formed by the pixel electrode 7 and the common electrode 3 on the first transparent substrate 1 side, so that the counter electrode as in the TN system is formed on the surface of the second transparent substrate 11. The lateral electric field that drives the liquid crystal 10 penetrates the color layer 13.

  The color layer 13 is composed of a coloring composition in which a pigment is dispersed in a resin, and the green coloring composition used in the G layer is mainly formed of green and yellow pigments and a resin. As the green pigment (G pigment), halogenated copper phthalocyanine (substituted halogen is chlorine or bromine) is widely used, and this G pigment is polarized by application of an electric field to generate charges. The ease of flow of positive charges and negative charges therein is different, and the resistance of the color layer 13 and the black matrix 12 is high, so that the generated charges are easily accumulated in the color layer 13. In addition, the phenomenon that the positive charge generated in the color layer 13 and the ease of flow of the negative charge are different has been confirmed by the knowledge of the present inventor.

  Then, when the color layer 13 is charged, an electric field is generated between the TFT substrate, the distribution of the horizontal electric field formed by the pixel electrode 7 and the common electrode 3 is disturbed, and the orientation direction of the liquid crystal 10 near the color layer 13 changes. To do. As a result, the transmittance of the liquid crystal 10 is reduced, the green wavelength component is reduced, and red unevenness occurs in which the entire display screen is reddish. The phenomenon that the color layer 13 is charged occurs not only in the G layer but also in the color layers 13 of other colors, but appears particularly prominent in the G layer.

  Therefore, in order to verify the correlation between the charging of the G layer and the red unevenness, the present inventor has created a color filter in which the weight ratio of the G pigment (halogenated copper phthalocyanine pigment) to the green coloring composition is changed. The occurrence level of red unevenness was examined. This red unevenness level is qualitatively determined by visual recognition, and is classified into five levels shown in Table 1 according to the finger press marks remaining when the liquid crystal display device displays white and the display surface is pressed with a finger. A range where the red unevenness level is less than 2 is set as an allowable range.

  As samples, four types (samples A to D) in which the concentration of the G pigment in the green coloring composition was changed from 19.9% to 28.4% were prepared, and the level of red unevenness was certified by the method described above. did. The results are shown in Table 2 and FIG.

  As described above, it is considered that red unevenness is caused by the fact that copper halide phthalocyanine, which is a material of G pigment, generates electric charges by an electric field. Therefore, as the concentration of G pigment increases, the amount of accumulated charges increases. It is considered that the level of red unevenness deteriorates in proportion to the concentration of the G pigment. However, referring to the experimental results in Table 2 and FIG. 2, the correlation between the G pigment concentration and the red unevenness level is not linear, and it can be seen that the occurrence of red unevenness is remarkably suppressed when the G pigment concentration falls below a certain threshold. . This is considered to be because the dispersion state of the pigment changes greatly when the concentration of the G pigment changes. From the above results, it can be seen that in order to suppress the red unevenness level to less than 2 which is a substantially allowable range, the concentration of the G pigment relative to the green coloring composition should be approximately 27% by weight or less.

  The weight ratio in the present invention is in a state where a colored film is formed on the color filter, does not include those that volatilize such as a solvent, and the effect of the present invention does not depend on the number and type of halogen substituents. In order to adjust the color tone, a yellow pigment may be added, but it is not particularly limited as long as it is a pigment usually used for a color filter, and a resin used for a color filter is usually used for a color filter. If it is resin made, it will not specifically limit.

  In the above experiment, the concentration range of the G pigment was determined in order to prevent the occurrence of red unevenness, but the ratio of the pigment contained in the colored composition is originally set by the material manufacturer, and its detailed Since the composition is not disclosed to the public, even if the liquid crystal display device is driven for a long time even if it does not generate red unevenness in the initial state, the red unevenness may occur over time or the red unevenness level may deteriorate.

  Such a change over time is difficult to predict, and conventionally, a method has been adopted in which electric field stress is applied to a color filter for a predetermined period, and a red unevenness level is determined from a finger press mark and defective products are excluded. However, it is difficult to determine a subtle level change in the method using finger press marks, and the liquid crystal display device may be damaged because the display screen is pressed with a finger. A proposal of a method that can evaluate long-term reliability is desired. Therefore, the present inventor conducted various experiments on the correlation between the time-dependent change in red unevenness and the physical properties of the color layer, and the change in red unevenness over time was determined by using the dielectric loss factor of the color layer as an index. It was found that it can be evaluated.

  That is, there is a dielectric constant as a physical property value that has a great influence on charging. Since the liquid crystal display device is driven by applying an AC voltage, it is expected that the dielectric constant cannot follow the frequency if charges are present in the color layer 13. From this, it is considered that the frequency characteristics of the dielectric constant have a correlation with red unevenness. Therefore, the level of occurrence of red unevenness was estimated by evaluating the shape of the complex dielectric constant, particularly the frequency characteristics of the dielectric loss factor, and the change with time. The technique of evaluating the red unevenness using the frequency characteristics of the dielectric loss factor and its change with time is a novel technique devised by the present inventor.

In order to confirm the effect of the above method, as in the experiment described above, four types of color filters having different concentrations of G pigment were prepared, and an aluminum electrode, a color layer, an overcoat layer, and an aluminum electrode were formed on the glass substrate in this order. Laminated sandwich cells were prepared, and a voltage of 5 V was applied to each sample. Then, in the initial state, after 24 hours, 48 hours, and 72 hours, an alternating electric field was applied, and the complex dielectric constant was measured with an LCR meter. As shown in Equation 1, the complex dielectric constant ε ^* is divided into a real part ε ′ and an imaginary part ε ″, ε ′ is called a dielectric constant, and ε ″ is called a dielectric loss factor.

ε ^* = ε′−iε ″ (1)

  The results of the above experiment are shown in FIGS. FIG. 3 to FIG. 6 are diagrams showing the frequency characteristics of the complex dielectric constant and the changes with time in the respective samples having different concentrations of G pigment, wherein (a) shows the dielectric constant ε ′, and (b) shows the dielectric loss factor ε. In the figure, the ◇ marker indicates the initial state, the Δ marker indicates the value after 24 hours, the □ marker indicates the value after 48 hours, and the ◯ marker indicates the value after 72 hours.

  As can be seen from FIGS. 3 to 6, the dielectric constant ε ′ gradually decreases as the frequency increases, but the tendency and value thereof do not vary greatly with the G pigment concentration, whereas the dielectric loss factor ε ″ is the frequency. There is a case where it gradually increases with an increase (for example, FIG. 3) and a case where it increases once after decreasing (for example, FIG. 6), and a low frequency region (near 100 Hz) and a high frequency region (near 1 MHz). In addition, both the dielectric constant ε ′ and the dielectric loss factor ε ″ change with time as the G pigment concentration increases, but the dielectric loss factor ε ″ has a larger amount of change. Therefore, it can be said that it is more preferable to use the dielectric loss factor ε ″ than the dielectric constant ε ′ in order to evaluate the frequency characteristics and the change with time.

  Further, paying attention to the dielectric loss factor ε ″, the sample D (FIG. 6) having a high pigment concentration has an overall increase in the dielectric loss factor from the low frequency region to the high frequency region over time. It can be seen that the change over time in the high frequency region is large, so even if the pigment concentration is unknown, the change in the dielectric loss rate over time in the high frequency region (for example, 1 MHz) is measured and the rate of change is calculated. Unevenness level can be estimated.

  FIG. 7 shows a plot of the ratio of the initial value of the dielectric loss factor in FIG. 3 to FIG. 6 at 1 MHz to the value after 72 hours and the red unevenness level. From FIG. 7, the ratio of the value after 72 hours of the dielectric loss ratio / initial value, that is, the greater the amount of change, the higher the level of red unevenness. By referring to this amount of change, a liquid crystal display device that causes a display defect is selected. It becomes possible to do. As the amount of change in the dielectric loss factor, if the dielectric loss factor after 72 hours is approximately 1.6 times or less of the initial value, the red unevenness level can be suppressed to less than the allowable range of 2.

  Further, when observing the shape of the frequency characteristic of the dielectric loss factor shown in FIGS. 3 to 6, in the sample D (FIG. 6) having a high G pigment concentration, the dielectric is measured in the low frequency region (near 100 Hz) and the high frequency region (near 1 MHz). While the loss factor is large and has a concave shape that decreases in the intermediate frequency range (around 10 kHz), the dielectric loss shape is flat in the region from the low frequency range to the intermediate frequency range as the G pigment concentration decreases. You can see that

  The difference in shape is presumed to be due to the distribution of the G pigment in the color layer 13 and the interrelation between the color layer 13 and other structures. From this difference in shape, the concentration of the G pigment and the level of red unevenness with time If the characteristic of the shape of dielectric loss is flat from the low frequency range to the intermediate frequency range (that is, there is no increase in dielectric loss in the low frequency range) is used as an index, It is possible to extract and exclude samples that may cause unevenness.

  FIG. 8 shows a plot of the values of the dielectric loss factors in the vicinity of 100 Hz, the ratio of the minimum value in the range of 100 Hz to 1 MHz, and the red unevenness level in FIGS. From FIG. 8, the ratio of the dielectric loss factor at 100 Hz / the minimum value from 100 Hz to 1 MHz is larger, that is, the greater the depression in the intermediate frequency region, the higher the level of red unevenness. It becomes possible to sort out the liquid crystal display device. As this ratio, if the dielectric loss factor at 100 Hz is approximately 1.25 times or less the minimum value from 100 Hz to 1 MHz, the red unevenness level can be suppressed to less than 2 which is the allowable range.

  In the above experiment, the overcoat layer 14 that covers the color layer 13 is made of the same material. That is, when the dielectric constant of the overcoat layer 14 is increased, the overcoat layer is also easily charged, and it is expected that the charged G pigment is bound to the overcoat layer 14 and the frequency characteristics are changed. Actually, when the same experiment was performed using the overcoat layer 14 having a different dielectric constant, it was found that the sample using the overcoat layer 14 having a large dielectric constant was likely to cause red unevenness. The selection of the layer 14 is also important for suppressing the occurrence of red unevenness, and a confirmation test is currently being conducted on this.

  Note that the color filter may be manufactured by any method such as a printing method, a photoresist method, and an etching method. However, in consideration of high definition and controllability and reproducibility of spectral characteristics, the photoresist method is preferable. In the photoresist method, a colored composition in which a pigment is dispersed in an appropriate solvent together with a photoinitiator and a polymerization monomer in a transparent resin is coated on a transparent substrate, and then a color filter is subjected to pattern exposure and development. In this method, the process of forming a color filter of one color is repeated for each color to produce a color filter.

  In order to confirm the effect of the present invention described above, a sample was prepared in the following manner, the change in dielectric loss over time (value after 72 hours / initial value, @ 1 MHz) and the degree of concave shape of frequency characteristics ( 100 Hz value / 100 Hz to 1 MHz minimum value).

(Color filter creation method)
A resin composition containing carbon particles is deposited on the second transparent substrate 12 to a thickness of about 1.3 μm to form a light shielding layer (black matrix 12). On this, the coloring composition of each color of RGB was applied using a spin coater, dried in an oven, exposed using a photomask, developed, washed with water, and post-baked. The G pigment in the G layer was 19.9%, and the thicknesses of the obtained colored layers were R2.0 μm, G2.1 μm, and B2.1 μm. RGB is adjusted to satisfy EBU chromaticity. Furthermore, the resin coating solution was applied to the entire surface using a spin coater and cured in an oven to form an overcoat layer 14. The film thickness of the obtained overcoat layer 14 was about 1.0 μm.

(TFT substrate creation method)
On the 1st transparent substrate 1, as a metal layer used as the scanning line 2, a common electrode wiring, and the common electrode 3, a Cr film | membrane is deposited with a film thickness of about 250 nm, and this is patterned. On top of this, a silicon nitride film, about 400 nm, an amorphous silicon film, about 300 nm, and an n-type amorphous silicon film, about 30 nm, are successively deposited as a gate insulating film. The crystalline silicon film is patterned into an island-like amorphous silicon shape. Next, after the interlayer insulating film 4 is deposited, a Cr film of about 250 nm is deposited as a metal layer to be the signal line 6 and the pixel electrode 7 and patterned. Further, a silicon nitride film is deposited to a thickness of about 200 nm as the passivation film 8, and the passivation film 8 is removed at the extraction terminal of the scanning line 2 and the extraction terminal of the signal line 6.

(Production of liquid crystal display panel)
An alignment film 9 is applied on the TFT substrate and the color filter substrate, and is rubbed in a direction that forms an angle of 15 degrees with the longitudinal direction of the pixel electrode 7. And after apply | coating a sealing material and spraying a spacer, both are bonded together and the liquid crystal 10 is inject | poured into this and it seals. Here, the cell gap of the liquid crystal layer is 4.5 μm, and the refractive index anisotropy Δn of the injected liquid crystal 10 is 0.070. The polarizing axis of the polarizing plate 16b is set in parallel with the rubbing direction, and the polarizing axis of the TFT side polarizing plate 16a is set in a direction perpendicular thereto.

  The liquid crystal display panel thus produced was continuously driven in a high temperature layer at 60 ° C. for 600 hours, but display unevenness (red unevenness) did not occur. The dielectric loss factor of the G layer used was 100 Hz / 100 Hz to 1 MHz minimum value of 1.25, and the ratio of the dielectric loss factor after initial application of electric field stress for 600 hours was 1.21. It was.

[Comparative Example 1]
As a comparative experiment, a sample in which the G pigment in the G layer was 28.4% was prepared. The color layer 13 was manufactured in the same manner as in the above-described example except that the thickness of the color layer 13 was R2.0 μm, G1.9 μm, and B2.1 μm. When this liquid crystal display panel was continuously driven at a high temperature layer of 60 ° C. for 600 hours, severe display unevenness (red unevenness) of level 4 occurred. As for the dielectric loss factor of the G layer used, the value of 100 Hz / the minimum value of 100 Hz to 1 MHz was 2.88, and the ratio of the dielectric loss factor after applying electric field stress for 600 hours was 2.05.

  From the results of the above examples and the results of the comparative examples, even when the concentration of the G pigment contained in the G layer is not known, the value of the dielectric loss factor of 100 Hz / 100 Hz to 1 MHz without determining the finger press mark. The level of red unevenness can be estimated by measuring the ratio specified by the minimum value of the dielectric loss and the ratio specified by the dielectric loss ratio after applying electric field stress for a predetermined time / the ratio specified by the dielectric loss ratio in the initial state. The long-term reliability of the liquid crystal display device can be confirmed by a simple method.

  In the above description, the IPS liquid crystal display device has been described as an example. However, the present invention is not limited to the above-described embodiment and examples, and any electrode in which no electrode is formed on the surface of the color filter substrate. It can be applied to a liquid crystal display device having a structure. In the above description, the relationship between the G layer and the G pigment and the red unevenness is described. However, it is obvious that the present invention can be applied to the relationship between other color layers and pigments that generate electric charges due to an electric field and the display unevenness.

It is a figure which shows a structure to the liquid crystal display device based on this invention, (a) is a top view, (b) is sectional drawing in the AA 'line. It is a figure which shows the effect of this invention, and is a figure which shows the correlation of the density | concentration of G pigment contained in G layer, and red nonuniformity. It is a figure which shows the effect of this invention, and is a figure which shows the frequency characteristic of the complex dielectric constant of a sample with G pigment density | concentration of 19.9%, and its time-dependent change. It is a figure which shows the effect of this invention, and is a figure which shows the frequency characteristic of the complex dielectric constant of a sample with a G pigment density | concentration of 25.5%, and its time-dependent change. It is a figure which shows the effect of this invention, and is a figure which shows the frequency characteristic of the complex dielectric constant of a sample with G pigment concentration 27.0%, and its time-dependent change. It is a figure which shows the effect of this invention, and is a figure which shows the frequency characteristic of the complex dielectric constant of the sample of G pigment concentration 28.4%, and its time-dependent change. It is a figure which shows the effect of this invention, and is a figure which shows the correlation with a time-dependent change of a dielectric loss factor, and a red nonuniformity level. It is a figure which shows the effect of this invention, and is a figure which shows the correlation with the grade of the concave shape of the frequency characteristic of a dielectric loss factor, and a red nonuniformity level. It is a figure which shows the problem of the conventional liquid crystal display device.

Explanation of symbols

1 First transparent substrate 2 Scan line 3 Common electrode 4 Interlayer insulating film 5 TFT
6 Signal Line 7 Pixel Electrode 8 Passivation Film 9 Alignment Film 10 Liquid Crystal 11 Second Transparent Substrate 12 Black Matrix 13 Color Layer 14 Overcoat Layer 15 Conductive Layers 16a and 16b Polarizing Film 17 Electric Field Line

Claims (4)

In a liquid crystal display device comprising a color filter substrate in which electrodes are not disposed on the liquid crystal sandwiching surface side than the color layer,
The green coloring composition constituting the color layer contains a pigment having a copper phthalocyanine skeleton, and the weight ratio of the pigment to the green coloring composition is in the range of 19.9 to 27.0%. Display device. In a liquid crystal display device comprising a color filter substrate in which electrodes are not disposed on the liquid crystal sandwiching surface side than the color layer,
The green coloring composition constituting the color layer includes a pigment having a copper phthalocyanine skeleton, and the weight ratio of the pigment to the green coloring composition is in a range of 19.9 to 27.0% in a chromaticity range of 65% or more. A liquid crystal display device characterized by the above. In a liquid crystal display device comprising a color filter substrate in which electrodes are not disposed on the liquid crystal sandwiching surface side than the color layer,
The green coloring composition constituting the color layer contains a pigment having a copper phthalocyanine skeleton, and the weight ratio of the pigment to the green coloring composition is in the range of 19.9 to 27.0%,
The dielectric loss factor of the color layer when an AC electric field of 100 Hz to 1 MHz is applied to the color layer,
100 Hz value / 100 Hz to 1 MHz minimum value <1.25
A liquid crystal display device satisfying the following condition. In a liquid crystal display device comprising a color filter substrate in which electrodes are not disposed on the liquid crystal sandwiching surface side than the color layer,
The green coloring composition constituting the color layer contains a pigment having a copper phthalocyanine skeleton, and the weight ratio of the pigment to the green coloring composition is in the range of 19.9 to 27.0%,
When the color layer is applied to a 1 MHz AC electric field, the dielectric loss factor of the color layer is
Value after applying an electric field stress to the color layer for at least 72 hours / value in initial state <1.6
A liquid crystal display device satisfying the following condition.

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