JPS62148926A - Color liquid crystal display element - Google Patents

Abstract

PURPOSE:To adjust the color balance of display colors by using the difference of spectral transmission characteristic due to the difference of filter film thickness to change the film thickness of at least one of color filters. CONSTITUTION:In this liquid crystal display element, the thickness of a blue filter BF1 is made relatively thinner than that of a red filter RF1 and a green filter GF1. Consequently, the quantity of absorbed light in the filter BF1 is smaller and the quantity of transmitted light in the filter BF1 is larger in comparison with the case where the thickness of the filter BF1 is equal to that of filters RF1 and GF1. Therefore, the display of blue due to the filter BF1 is brighter. Since the filter BF1 is thinner, the voltage drop for voltage application is smaller than that of thicker filters RF1 and GF1, and a practical voltage applied to only a liquid crystal material LC in a part corresponding to the filter BF1 is higher than that applied to the material LC in parts corresponding to filters RF1 and GF1, and the quantity of light transmitted the material LC in the part corresponding to the filter BF1 is increased. Thus, the color balance is adjusted easily and the color reproducibility is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a color imager in which one pixel is formed by three dots equipped with red, green, and blue color filters, and a plurality of these pixels are arranged. The present invention relates to improvements in liquid crystal display elements, and particularly relates to a color liquid crystal display element in which the film thickness of each of the color filters is changed according to the spectral transmission characteristics of the color filters themselves.

[Prior Art] Recently, the uses of liquid crystal display elements have been expanded, and there is a demand for practical use of liquid crystal display elements that display color. In response to this trend, dot matrix type color liquid crystal display elements for displaying television images, for example, are being put into practical use.

A dot matrix type color liquid crystal display element.

It is configured as follows. A substrate on which a plurality of scanning electrodes are formed and a substrate on which a plurality of signal electrodes are formed are arranged to face each other so that the scanning electrodes and the signal electrodes are perpendicular to each other.

A liquid crystal material is filled between these substrates. Furthermore, three primary color filters of red, green, and blue are sequentially formed in correspondence with the signal electrodes of the substrate on which the plurality of signal electrodes are formed. Such a color liquid crystal display element is a so-called simple matrix type. In the color liquid crystal display element, a voltage is applied between the scanning electrode and the selected signal electrode to control the transmission of light through the portion (dot) where these electrodes face each other. By fully controlling the transmitted light of the dots corresponding to these color filters, the intensity of the light transmitted through each color filter is adjusted, and the three primary colors or intermediate colors appear for each pixel. The color liquid crystal display element forms a full color image using these large numbers of pixels.

However, such color liquid crystal display elements are red.

It uses the three primary colors of green and blue and attempts to express a large number of colors through additive color mixing. In this case, it is necessary that when a predetermined voltage is applied between the scanning electrode and the signal electrode corresponding to each color dot of each pixel, those pixels can visually express white.

That is, the color balance must be good. When this color balance is disrupted, the displayed color image appears to have a different color temperature. For example, if the intensity of light transmitted through a blue filter is weak, the color temperature will appear low and the image will have a yellowish tinge, and if the intensity of light transmitted through a red filter is weak, the image will appear blue-green. This will result in severe damage.

Various factors can be considered to disrupt such color balance.

First, there is a problem caused by the spectral transmission characteristics of the liquid crystal element itself. Color imbalance occurs because liquid crystal elements have different transmittances for light of the wavelengths of each of the three primary colors. A means to solve all of these problems is, for example, published in Japanese Patent Application Laid-Open No. 1983-1989. 15
No. 9823, JP-A-60-159830, Inko-159
831' and Japanese Patent Application Laid-Open No. 159827/1983.

Among the above-mentioned publications, No. 60-159823.

60-159830 and 60-159831 are constructed as follows. A common electrode is formed on a pair of opposing substrates. Red, green, and blue filters are sequentially formed on the other of the pair of substrates. Furthermore, signal electrodes are formed on each color filter. A liquid crystal is sealed between the pair of substrates. Here, the thickness of the liquid crystal layer corresponding to each color filter is different. That is, by changing the thickness of each color filter or the thickness of the insulating layer, the thickness of the liquid crystal layer in the part corresponding to the blue filter is made the thinnest, and then the thickness of the liquid crystal layer in the part corresponding to the green filter is made thinnest. The thickness of the liquid crystal layer is the thickest in the area corresponding to the red filter.

The reason for this configuration is as follows.

In order to increase the response speed of the liquid crystal element, the thickness d of the liquid crystal layer is
The smaller the better. Therefore, the minimum thickness d of the liquid crystal layer at which the dots can block light is determined by Δn=d (Δn is the refractive index anisotropy of the liquid crystal) in Figure 12, which shows the transmittance of each color of light against Δn-d. It will be around 0.5.

In this case, if Δn k is 0.1, d is 5
It is μm. However, in the vicinity of Δnod of 0.5, the transmittance of each color filter differs significantly due to optical rotational dispersion of the liquid crystal element.

Therefore, if the thickness of the liquid crystal layer corresponding to each color filter is made equal, achromatic colors that appear colored cannot be expressed because the transmittance of each color filter is different. This phenomenon occurs when displaying a blank screen in which no electric field is fully applied to the liquid crystal. If the color balance is disrupted in the initial state where no electric field is applied, it will not be possible to express all achromatic colors even when an electric field is applied. In other words, it appears to have a certain color tone.

Therefore, in the prior art, the value of Δn4 (α1, α2, α6 in FIG. 12 is calculated, and based on this Δ・nd , the thickness of the liquid crystal layer corresponding to each color filter is set.For example, in the prior art described above, the thickness of the liquid crystal layer corresponding to the red filter is 5.4 μm, and the thickness of the liquid crystal layer corresponding to the green filter is set. The thickness of is 4.8 μm,
Moreover, the thickness of the liquid crystal layer corresponding to the blue filter is 3.7 μm.
It is.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, the thickness of the liquid crystal layer corresponding to each color filter is 1 g because it differs greatly.

If the voltage supplied between each electrode for applying an electric field to the crystal layer is the same, the electric field will differ greatly for each corresponding liquid crystal layer of each color filter. Therefore, in order to drive such a liquid crystal element, it is necessary to apply different voltages between each electrode, and a plurality of power sources are required.

Unfortunately, the above-mentioned Japanese Patent Application Laid-Open No. 159827/1983 is constructed as follows in order to completely prevent the color balance from being disrupted due to optical rotation dispersion, as in the prior art described above. A common electrode is formed on one of the pair of opposing substrates. A signal electrode is formed on the other of the pair of substrates. These signal electrodes correspond to red, green, and blue filters, respectively. Further, a dielectric layer consisting of an insulating layer or a filter layer is formed on the signal electrode. A liquid crystal is sealed between the pair of substrates. The dielectric layer is
The thickness of each color dot corresponding to each color filter is different. That is, the thickness of the dielectric layer corresponding to the red dot on which the red filter is provided is the thickest, followed by the thickness of the dielectric layer corresponding to the green dot, and the thickness of the dielectric layer corresponding to the blue dot is the thickest. It's getting thinner.

First, this prior art also solves the problem of color balance caused by optical rotation dispersion, which was detailed in the prior art described above. Therefore, by changing the thickness of the dielectric layer formed on the electrode corresponding to each color dot and fully adjusting the electric field applied to the liquid crystal layer, the deviation in color balance due to optical rotation dispersion is corrected using the electric field.

Next, there is the problem of balance in the spectral transmission characteristics of each color filter itself. This is due to the fact that it is difficult to set the hue of each color filter itself and the intensity of transmitted light to a ratio that visually represents white. The color filters used in this liquid crystal display device are produced using a dyeing method in which a layer to be dyed is formed and this layer is dyed with a dye, an electrodeposition method in which the colored material is entirely deposited on the electrode, or a coloring method in which the colored material is deposited as desired. It is formed by a printing method or the like that prints on the electrode.

Color liquid crystal display elements equipped with color filters formed by these manufacturing methods express a large number of colors by color mixing of the light that passes through each color filter dyed in red, green, and blue. There is.

It is known that among these three primary colors, blue, which is displayed by light transmitted through a blue color filter, is perceived by humans as having lower brightness and being darker than other colors. For this reason, if the physical intensities of the three primary colors PjfJ are made equal, it is not possible to achieve a color balance between red, green, and blue displayed by a color filter. For example, if the blue color is dark like this, when white is displayed by combining the light that has passed through each of the three primary color filters, the color temperature will be low and people will perceive the color as having a yellowish tinge. Therefore, an image with disrupted color balance is displayed.

By the way, a color liquid crystal display element manufactured by the dyeing method has the following configuration. That is, a liquid crystal material is filled between a substrate on which a plurality of scan electrodes are formed and a substrate on which signal electrodes are formed orthogonally to the scan electrodes. Furthermore, layers to be dyed are formed corresponding to the signal electrodes of one of the substrates, and each of these layers to be dyed is sequentially and alternately dyed in red and red, respectively, using a dye.
It is equipped with color filters dyed in the three primary colors of green and blue.

In such conventional color liquid crystal display elements, the thickness of the dyed layer constituting each color filter is the same, and in order to maintain the color balance of the three primary colors by displaying the color filter, it is necessary to form the color filter. At this time, the brightness of the color displayed by the color filter is adjusted by fully controlling the degree to which the layer to be dyed formed on the electrode surface is dyed with the dye.

In this case, it is necessary to fully control the dyeing speed by selecting the type of dye and dyeing conditions.

For example, when dyeing a blue filter, if the blue dye saturates the layer to be dyed in a trench, the brightness will drop significantly. Therefore, in order to achieve color balance by fully adjusting the brightness of the three primary color filters, the dyeing of the dyed layer of the blue filter is limited so as not to reach saturation. However, in this case, it is difficult to adjust the degree of dyeing of the layer to be dyed, and uneven dyeing occurs for each individual blue filter or for each liquid crystal display element, resulting in uneven color display. In order to avoid such uneven staining, the degree of staining of the red filter and the green filter is adjusted to ff1M using the method described above, and the brightness of red and green is lowered to match the brightness of all blue, so that the color parameter is equal to 10- If an attempt is made to adjust the contrast, the entire image on the color liquid crystal display element becomes dark and the contrast deteriorates. On the contrary, if the degree of dyeing of the blue filter is made shallower and dyed lightly, the color purity will be reduced, and the color balance will also be deteriorated.

The display colors of a color liquid crystal display device provided with color filters of equal thickness in this manner are shown on a chromaticity diagram as shown in FIG. In the figure, the points indicated by X marks are the hues of the filter itself, and the range surrounded by the dashed line represents the hues that can be displayed by this filter. The solid and broken lines indicate the display colors when equal voltages are applied between the electrodes corresponding to the dots of each color. The display color range shown by the solid line is when a voltage of 2.3V is applied between the electrodes, and the display color range shown by the broken line is when a voltage of 2.3V is applied between the electrodes. This is the case when a voltage of Ov is applied. Note that the point indicated by a ■ mark in the center is the case where no voltage is applied.

As shown in the figure, when the thickness of each color filter is uniform, the point displayed as Va- is closer to the center, the blue light is weak, and the whole has a yellowish tinge.

Furthermore, as in the prior art described above, when the thickness of each color filter is changed in order to correct the spectral transmission characteristics due to optical rotation dispersion that the liquid crystal cell itself has, The dyeing layer must be dyed with a dye to obtain predetermined spectral transmission characteristics. Therefore, it is more difficult to control the staining conditions in this case.

An object of the present invention is to eliminate the above-mentioned drawbacks and provide a color liquid crystal display element with excellent color reproducibility.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the color liquid crystal display device of the present invention includes: a pair of opposing substrates; a second electrode disposed on the inner surface of the other of the pair of substrates so as to face the first electrode; at least one of the first electrode and the second electrode; a plurality of color filters formed on the electrodes, each having different spectral transmission characteristics and having a different thickness depending on the spectral transmission characteristics; a liquid crystal substance sealed between the pair of substrates; , 2.

[Operation] This invention adjusts the color balance of displayed colors by changing the thickness of at least one of the color filters, taking advantage of differences in spectral transmission characteristics due to differences in filter thickness. be.

Therefore, the relationship between the spectral transmission characteristics of each color filter and the film thickness of the filter will be explained with reference to FIGS. 8 to 10.

Among these spectral transmission characteristics, FIG. 8 shows the red filter, filter thickness QA: 0.6 μm,
B: 0.9 μm, C: 1.4 μm, D: 1.
7 ttm, E: This is the spectral transmission characteristic of the filter alone when the thickness is 2.1 μm. Figure 9 shows the thickness of the red filter: F: 0.55 μm, G:
0.85 μm, H: 1.4/jm, I: 1,55
μm%J: This is the spectral transmission characteristic of the filter alone when the filter is set to 1.9. Figure 10 shows the blue filter.
The thickness of the filter is K: 0.6 μm%L: 0
．． 9 μm, M: 1.3 μm, N: 1.6
μm, O: This is the spectral transmission characteristic of the filter alone when it is set to 1.65 μm.

As is clear from these characteristic diagrams, in the red filter, as the filter film thickness becomes thinner, the maximum value of the spectral transmittance decreases to 1.
The value does not change, but the minimum value becomes higher. With the green filter,
As the film thickness of the filter becomes thinner, both the maximum value and the minimum value of the spectral transmittance become higher.

As for the back filter, as the film thickness of the filter becomes thinner, the maximum value of the spectral transmission characteristic increases, but the minimum value hardly changes. In this way, when the film thickness of each color filter changes, the spectral transmission characteristics of each filter itself change in various ways.

In this case, the basic characteristics of each color filter, such as the light absorption wavelength band, do not change because they are unique to each colored material. However, the transmittance varies greatly depending on the film thickness of the filter.

Therefore, the present invention adjusts the color balance of display colors by setting the film thickness of each color filter, paying attention to changes in transmittance due to differences in filter film thickness.

Furthermore, in the color liquid crystal display element of the present invention, filters for each color are formed on the electrodes formed on the substrate. For this reason, if the thickness of the filter film for each color is different, the thickness of the dielectric layer formed on the electrode will also be different, so the thinner the dielectric layer is, the lower the voltage drop due to the dielectric layer, so the liquid crystal The voltage substantially applied to becomes higher. FIG. 11 shows the relationship between the film thickness of such a color filter and the threshold voltage vth applied between opposing electrodes that sandwich this filter and liquid crystal. This threshold voltage vth
is the voltage at which the liquid crystal cell reaches a predetermined transmittance when a voltage is applied between opposing electrodes. As is clear from FIG. 11, the thinner the filter, the lower the vth of the liquid crystal cell. This means that when the same total voltage is applied between the electrodes corresponding to each dot for displaying each color, the thinner the filter film is, the more the amount of light transmitted through the liquid crystal cell itself is controlled. That's true.

Therefore, in the present invention, by adjusting the film thickness of each color filter, the transmittance of the spectral transmission characteristic of the filter itself changes as described above, and the transmittance changes by changing the voltage substantially applied to the liquid crystal layer. The color balance of the display colors of the color liquid crystal display element can be adjusted appropriately by utilizing both the effect of the change and the change in color.

When the color liquid crystal display element of the present invention uses each color filter having the spectral transmission characteristics shown in FIGS. 8 to 10,
For example, the thickness of each filter is 1.2 μm for the red filter, 1.2 μm for the green filter,
It is also preferable that the film thickness of the blue filter is 1.0 μm. Alternatively, it is preferable that the thickness of the red filter is 0.9 μm, the thickness of the green filter is 0.9 μm, and the thickness of the blue filter is 0.7 μm. Further, good results were also obtained when the thickness of the red filter was about 0.9 μm, the thickness of the green filter was about 0.7 μm1, and the thickness of the blue filter was about 0.5 μm.

[Embodiment] A first embodiment in which the color liquid crystal display element of the present invention is applied to a color television will be described below with reference to FIGS. 1 to 3.

In a color liquid crystal display element, light on the short wavelength side is absorbed by the glass substrate and polarizing plate used in the display element, so that the transmitted blue light becomes weak. As a result, the displayed color appears yellowish. In this first embodiment, in order to solve the above problem, the display colors are balanced by increasing the transmitted blue light.

The color liquid crystal display element of this invention is constructed as follows.

In Figures 1 and 2, 1, 2? This is a pair of upper and lower transparent substrates made of glass plates.The pair of substrates 1 and 2 are bonded to each other via a frame-shaped sealing material 3 at the periphery.For example, the inner surface of the upper substrate 1 A large number, for example, 108 transparent scanning electrodes are formed on the (lower surface).A large number, for example, 450 transparent signal electrodes are formed on the inner surface (upper surface) of the lower substrate 2, orthogonal to the scanning electrodes. ing.

4.4... are transparent scanning electrodes formed on the inner surface of the upper substrate 1. The scanning electrodes 4, 4, . . . are formed parallel to each other in the width direction of the substrate 1. Each scanning electrode 4,
4... One end is the drive circuit connection terminal 43, 41...
and are connected via leads 4b, 4b, .

A plurality of drive circuit connection terminals 4a, 4a are arranged in a terminal arrangement section 1a formed by extending one end edge of the upper substrate 1 outward from the sealing material 3. Note that these drive circuit connection terminals 4a, 4a... and leads 4b,
4b... are formed integrally with the scanning electrodes 4.4... from a transparent conductive material such as indium oxide.

Also, 5R, 57%..., 5G, 5G..., 5B
.

5B... are transparent signal electrodes formed on the inner surface of the lower substrate 2 so as to be perpendicular to the #f marking scanning electrodes 44....

Each of the signal electrodes is made of indium oxide or the like and has a thickness of 500 to 600 mm. The signal electrodes are arranged alternately in the order of 5R, 5G, and 5B.

Also, in Fig. 1, RF, , RF,...#
GF.

CF,..., BFl, BF,... are each of the signal electrodes 5R.

5R...$ 5Gs 5G...@5Bs5B...
A red color is formed on top of the corresponding signal electrode, respectively.
green.

It is a three-color blue color filter. These color filters RF1. RF,..., GF', # GF
,...e BF, *BF,... is the red filter R
F, , green filter GF1゜blue filter BF are arranged alternately in this order, and each signal electrode SB, 5R..., 5G
, 5G..., 5B, 5B...

Filters RF4 for each of these colors. RF,..., GF
,.

CF,..., BF, # BF,... are each signal electrode 5R, 5R...15 G #5 G..., 5B
, 5B... is coated with a protein substance such as casein to form a dyed layer RFa#RFa...#GFa#GFa
...* BFa* BF, ``Fully formed, this dyed layer BP, RF,...I GF', # GF
'a...#BF.

BF, . . . were dyed red, green, and blue using dyes of various colors (see Fig. 3).

Further, the red filters RF, RF, . . . and the green filters GF, GF, GF, . BF, ... are red filter RF
11 RFl... and green filter GF1. GF
The film thickness tBl (tBf>tRl=tGf) is smaller than the film thickness tR1°ta, which is a thickness of l.... Here, the film thickness tR1' tG of each color filter
l # tBl are 1.2 μm, 1.2 μm, and
1.0μm, or 0.9μm, 0.9μm, 0.7μm
It is.

In addition, the color filters RF', RF,...
・,GF,.

An alignment film 7 is formed on the surfaces of GFl..., BF, IBF, .

On the other hand, in FIGS. 1 and 2, 5aft.

5aR... are signal electrodes (hereinafter referred to as red signal electrodes) 5R, 5R... on which a red filter BFL is completely formed.

This is the drive circuit connection terminal. 5aG, 5aG, . . . are drive circuit connection terminals of signal electrodes (hereinafter referred to as green signal electrodes 5) 5G, 5G, which have a green filter GF formed on their upper surfaces. 5hB, 5af3, . . . are drive circuit connection terminals of signal electrodes (hereinafter referred to as blue display electrodes) 5B, 5B, .

Each of the signal electrodes 5R, 5R..., 5G, 5G...

5B, 5B... are each of these terminals 5aRs5
aR-..., 5hG s 5*G ・-, 5aB,
5aB- are connected by leads 5b, 5b, . . . .

Among the terminals, the terminals 5aR# 5aR of the red signal electrodes 5R, 5R, . The terminal array portions 2g and 2b are arranged in a line along the outer edge of the terminal array portion 2a. Green signal electrode 5Cr@5G... terminal 5aG, 5*G
. . are arranged in a line in the negative terminal arrangement portion 2&, located inside the terminal row of the red signal electrodes 5R, 5R, . In addition, the blue display electrode 5B
s 5 B... terminals 5a13, 5a13...
are arranged in a line in the other terminal arrangement section 2b.

Each of these terminals 5aR, 5aB-, 5*G t 5! LG
”-, 5aBa5aB... and leads 5b, 5b...
The signal electrodes 5R, 5R...tr 5 G @ s G...,
5B, 5B, and so on.

In addition, in FIG. 2, 6, 6 is the outermost signal electrode 5R.
, 5B is a disposable electrode with approximately the same length as the signal electrode. This sacrificial electrode 6.6 is formed of a transparent conductive material such as indium oxide at the same time as the signal electrode. This sacrificial electrode 6.6 is left as an electrode that is not connected to the drive circuit (there is no color filter above this sacrificial electrode 6, 6).

The reason why the sacrificial electrodes 6, 6 are provided outside the outermost signal electrodes 5R, 5B is that a transparent conductive material is deposited on the two surfaces of the substrate by sloping and then etched. Signal electrodes 5R, 5R..., sG,
This is because it is possible to prevent the widths of the outermost signal electrodes 5R and 5B from becoming narrower when all of the electrodes 5G, 5B, 5f3, and so on are formed.

In FIG. 1, reference numeral 7.7 indicates a liquid crystal alignment film provided on the inner surfaces of the upper substrate 1 and the lower substrate 2 (the electric fence forming surfaces). 8.8 is a polarizing plate provided on the outer surface of the upper substrate 1 and the lower substrate 2. The alignment films 7, 7 are formed by rubbing the surfaces of polyimide films in directions substantially perpendicular to each other. The liquid crystal material LC filled between the two substrates 1.2 is oriented by the alignment films 7, 7 so that the liquid crystal molecules are twisted at approximately 90 degrees between the side substrates. Further, the upper and lower polarizing plates 8.8 have their polarizing axes aligned with the orientation direction of liquid crystal molecules on one of the substrate surfaces (rubbing direction of the alignment film), and the polarizing axes of both polarizing plates 8.8 are aligned. They are arranged facing in the same direction, thereby forming a negative display type liquid crystal display element.

Next, a method for manufacturing the color filter used in the first example will be explained with reference to FIG. Each of the signal electrodes 5
R, 5R...# 5G, 5G..., 5B.

Color filter RF1 of each color provided on the surface of 5B...
゜RFl...t GFl # GFl...* BF
l m BFl... is formed through the steps shown in FIG. 3, for example. First, signal electrodes 5R, 5R..., 5G
, 5G..., 5B, 5B... fully formed lower substrate 2
3(a)), a dyed layer material 9 made of protein is applied to the entire surface of the lower substrate 2 so as to cover each signal electrode (FIG. 3(b)). Next, mask 1
0f, the portion of the layer material 9 to be dyed located above the red signal electrodes SR, 5R, . After that, by performing a development process using hot water or the like, the layer material 10 to be dyed is
is removed except for the exposed portion. In this way, the red filter dyeing layer RFaI RFa... having a thickness tRl is completely formed on the surfaces of the red signal electrodes 5R, 5R... (FIG. 3(d)). This dyed layer RFa, RFa...
・By dyeing with red dye, red filter RF4. RF... completely formed (Fig. 3(e)
).

The dyed red filters RF, RF1, . . . are subjected to resist dyeing treatment using gold such as tannic acid (FIG. 3(f)).

Next, a layer material 9 to be dyed is applied onto the surface of the lower substrate 2 (FIG. 3(g)). As in the case of the red color filter, the exposure process (Fig. 3 (h)) and the development process (Fig. 3 (h)) are performed.
Figure (i))'e. In this way, the dyed layers RF, I are formed on the surfaces of the green signal electrodes 5G, 5G...
Same thickness t as RFa. The dyed layer GFaI GFa for the green filter in No. 1 is completely formed. Thereafter, the dyed layers CF, GF, . GF, . . . are formed (Fig. 3 (j)). This green filter GF1. G
F.

Apply anti-dyeing treatment to... (Figure 3(k)). moreover,
Coating the layer material 9 to be dyed on the surface of the lower substrate 2 (
Figure 3 (a)). After the exposure process (FIG. 3 (n)) and the development process (FIG. 3 (n)), the blue signal electrode 5B is
.

On the surface of 5B..., a dyed layer BF for a blue filter having a thickness tBl smaller than the dyed layers RF and GF.
, , BFIL... is formed. Then, the dyed layers BFILM BFa... are dyed with a blue dye to form blue filters BF1#BF,... (FIG. 3(0)), and the blue filters BF'4. BF,・
Apply anti-staining treatment to... (Figure 3 ω)). In this way, each color filter is formed one after another. Note that each color filter RF1. RFl...# GFl m GF,
..., BF1# BF, ..., the resist dyeing treatment performed after each dyeing process may be replaced by forming a protective layer on the entire surface.

In the color liquid crystal display element configured in this way, each signal electrode 5R, 5R, . . . , 5G is connected in accordance with the image signal.

A voltage is applied between 5G..., 5B, 5B... and the scanning electrodes 4, 4... arranged opposite to these, and the liquid crystal is displayed at the intersection of the selected signal electrode and the common electrode. substance L
Make C behave. Due to the behavior of this liquid crystal substance LC, signal electrodes 5R, 5R..., 5G, 5G...

Color filters RF of each color formed on 5B, 5B...
1 * RFl...# GFlm GFl...,
Color display is performed by controlling the intensity of light passing through BF, BF, BF, . . . .

However, in this liquid crystal display element, the red filter RF,
RF,... and green filter GF1. GFl...
The total thickness of the blue filters BF11, BF1, . . . is relatively small compared to . Therefore, the blue filter BF1. The thickness of BFl... is red and green filter RF1. Compared to the case where the thickness of the blue filter BF1 is the same as that of RFl..., GFl, GFl...
．． The amount of light absorbed in BFL... is small and the amount of transmitted light is large. For this reason, the blue color filter BF1#B
The blue display by Fl becomes brighter. Also, since the blue filter BF1゜BFl has a small thickness, the voltage at the time of voltage application is smaller than that of the red filter RF, * RF, ... and the green filter GF1 m GF, ..., which have a larger thickness. The drop is small. For this reason, the blue filter BF,.

BF,... are red filters RF, , RF,...
and green filter GF1. Compared to the liquid crystal material LC in the portion corresponding to GF1, the substantial voltage applied only to the liquid crystal material LC is higher, and the amount of light transmitted through the liquid crystal material LC increases. Therefore, the blue filters BF, BF,...
・The amount of transmitted light due to the lighting of the dot corresponding to .

The display colors of the above-mentioned color liquid crystal display element are shown in the chromaticity diagram of FIG. The points marked with an x in the figure are the hues of the filter itself, and the entire range of hues that can be displayed by the filter itself is indicated by a dashed line. The range of hues that can be displayed when a voltage of 2.3 V is applied between the electrodes corresponding to each dot for displaying each color is shown by a solid line. 240V between the electrodes
The range of hues that can be displayed when the full voltage is applied is shown by a broken line. Note that the point indicated by a ■ mark in the center is the case where no voltage is applied.

As shown in the figure, the lines connecting all the hues of each color filter alone are large and have no equilateral triangular engravings, so the color balance of the displayed colors is good and a large number of colors can be displayed. .

In comparison, the chromaticity diagram in Figure 5 shows the displayed color when the red and green filters have the same film thickness and the blue filter is extremely thin compared to the other filters. It is. That is, FIG. 11 shows the displayed colors when the film thickness of the red filter and the green filter is 1.2 μm, and the film thickness of the blue filter is 0.5 μm. As is clear from this figure, the range of hues that can be displayed is largely biased toward the dorsal side.

Therefore, if such a filter is formed, the displayed color will appear bluish and the color balance will be disrupted, resulting in
Ru.

From the above results, when making the blue filter thinner,
When the thickness of the red and green filters is about 1.2 μm, the thickness of the blue filter is preferably about 1.0 μm. Further, when the thickness of the red filter and the green filter is about 0.9 μm, it is preferable that the thickness of the blue filter is about 0.7 μm. In other words,
When the film thickness of the red filter and green filter is 1,
Good color balance can be obtained if the film thickness of the blue filter is 0.5 or more.

In addition, in the chromaticity diagram of Figure 4, the hue of the green filter is Yellow.
The range of owlsh green is the result of correcting the spectral transmission characteristics of the polarizing plate and the like.

Further, in this first embodiment, a liquid crystal mixture having a refractive index anisotropy Δn of 0.161 is used as the liquid crystal substance sealed between the substrates, and an alignment film on one substrate and an alignment film on the other substrate are used. A color liquid crystal display element was used in which the gap between alignment films was set to about 7.5 μm. Therefore, in this first embodiment, Δ
n4 is in the range of 1.1 to 1.2), Δ in Figure 12
nd is in the range of β to β2. Therefore, in the embodiment of the present invention, the problem of color balance being disrupted due to optical rotation dispersion, which was pointed out in the prior art mentioned above, is solved by setting the value of Δn-d such that the influence of optical rotation dispersion is reduced. There is.

As mentioned above, the blue filter BF1 * BF,...
The blue color indicated by . is the red filter RF4. RF,
. . . and green filters GF, #GFl . . . The brightness is raised to the same level as the brightness of red and green displayed by the green filters GF, #GFl . Therefore, the brightness of the three primary colors displayed by the color filters of each color is balanced among red, green, and blue. Then, since the blue display becomes brighter, each color filter RF, #RFl...*GFl
s GFl..., BF4. When white is displayed by lighting up all of BFL..., beautiful white can be displayed entirely. In this way, the image quality of color display can be improved.

In addition, since the thickness of the blue color filters BP, IBF, .・Since dyeing can be carried out until the paint is saturated and there is no need to limit the degree of dyeing, blue filters BF1a BF',...
There will be no variation in dyeing, and this will also prevent variation in the blue color display. Furthermore, since the blue display is brightened and the color balance of the three primary colors is balanced, the image on the entire screen of the liquid crystal display element is bright and has clear contrast.

Next, a second embodiment using the present invention will be explained with reference to FIG. In this second embodiment, the film thicknesses of the red filter RF2, the green filter GF2, and the blue filter BF2 are set to different thicknesses depending on the spectral transmission characteristics of each color filter itself.

In FIG. 6, the same parts as those shown in FIGS. 1 and 2 are designated by the same reference numerals, and their explanation will be omitted.

In Fig. 6, red filter RF2 #BF2...
・It is formed by membranous rice. The green filter GF2°GF2... has a film thickness t smaller than the film thickness tR2.

It is formed by 2. And blue filter BF2.

BF... is the film thickness t. Film thickness tB smaller than 2
It is formed by 2. That is, the film thicknesses of the respective color filters are in the relationship tR□>tG2>tB2.

In this case, the film thickness of each color filter depends on the spectral transmission characteristics of each color filter itself, for example, red filter RF2.
The film thickness of BF2... is about 0.9 μm, the film thickness of green filters GB, GB2... is about 0.7 μm, and the blue filters BF2. The film thickness of BF2... is approximately 0.5 μm
It is.

Note that the liquid crystal material used in this second embodiment and the gap between the alignment films of the opposing substrates are the same as in the first embodiment.

The color liquid crystal display element constructed in this manner can accurately adjust all display colors of dots of each color corresponding to each color filter, and has extremely good color reproducibility.

Furthermore, a third embodiment using the present invention will be described with full reference to FIG. In this third embodiment, the balance of displayed colors is adjusted by increasing the film thickness of the green filter, which is visually sensitive among the color filters, and lowering the original transmittance of green. In FIG. 7, the same parts as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and the explanation thereof will be omitted.

In FIG. 7, red filter R'F5 m BF3・
... and the blue filter BF5*BF5... are formed to have the same film thickness tR3°t. The green filter GF3# GF3... has the film thickness t83' tB5
It is formed to have a larger film thickness to3. That is, the film thickness of the above-mentioned color filter is tB3 '' tB 3 <
The relationship is t03.

In addition, in this third example as well, the liquid crystal material used,
The gap between the alignment films of the opposing substrates is the same as in the first embodiment.

The color liquid crystal display element constructed in this manner has good color reproducibility because the film thickness of the green filter is increased according to the spectral transmission characteristics of the green filter itself.

As described below, according to the present invention, the brightness of a colored filter can be adjusted by adjusting the film thickness of the filter. Therefore, the degree of freedom in selecting the substance that colors the filter is increased.

In the above-mentioned embodiment, an example was explained in which a color filter was formed by the entire dyeing method, but the present invention is not limited to this, and can be applied to a color liquid crystal display element equipped with a filter formed by an electrodeposition method or a printing method. can also be applied.

Further, the liquid crystal display element of the present invention is not limited to use in displaying television images, but can be widely applied to color display in other uses.

[Effects of the Invention] According to the color liquid crystal display element of the present invention, the color/glance of the displayed color by each color filter of red, green, and blue can be changed by changing the film thickness of each color filter, and the spectral transmission characteristics of each color filter itself can be changed. It can be adjusted by changing. Therefore, the color balance can be easily adjusted. Therefore, color reproducibility is improved.

Of the spectral transmission characteristics of the colored filter itself,
In particular, since the brightness can be varied depending on the film thickness of the filter, the range of selection of dyes, pigments, etc. for coloring the filter is widened. Therefore, dyes and the like having excellent light resistance can be used, and the life of the color liquid crystal display element can be extended.

[Brief explanation of drawings]

1 to 4 show a first embodiment of the present invention, in which FIG. 1 is a sectional view of a color liquid crystal display element taken along line I-I in FIG. 2, and FIG. 2 is a color liquid crystal display device. FIG. 3 is a plan view showing the electrode shape of the element, FIG. 3 is a manufacturing process diagram of color filters of each color, and FIG. 4 is a chromaticity diagram showing the display colors of the color liquid crystal display element. FIG. 5 is a chromaticity diagram showing an inappropriate example for comparing display colors by the color liquid crystal display element of the present invention. 6 and 7 are cross-sectional views of color liquid crystal display elements showing second and third embodiments of the present invention. FIG. 8 is a spectral transmission characteristic diagram of the red filter itself used in the present invention, FIG. 9 is a spectral transmission characteristic diagram of the green filter itself used in the present invention, and FIG. 10 is a diagram of the spectral transmission characteristic diagram of the blue filter itself used in the present invention. Spectral transmission characteristic diagram, Figure 11 shows
FIG. 12 is a transmission characteristic diagram showing the transmittance of each color of the liquid crystal element, and FIG. 13 is a chromaticity diagram showing all the original colors of a color liquid crystal display element according to the prior art. . 1.2...Substrate, LC...Liquid crystal, 4...Scanning electrode, 5R, 5G, 5B...Signal electrode, RF, RF
2. RF3...Red filter, GFl s GF2
# GFs...green filter, BFL, BF2.
RF5...Blue filter.

Claims (1)

[Scope of Claims] A pair of opposing substrates; a first electrode formed on the inner surface of one of the pair of substrates; a first electrode formed on the inner surface of the other substrate of the pair of substrates; a second electrode arranged to face the electrode; formed on at least one of the first electrode and the second electrode, each having different spectral transmission characteristics; A color liquid crystal display element comprising: a plurality of color filters having different thicknesses depending on spectral transmission characteristics; and a liquid crystal substance sealed between the pair of substrates.