JPH028A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain the liquid crystal display element which can display a high-contrast image by specifying the ratio of the prescribed dielectric constant and elastic constant ratio of a liquid crystal. CONSTITUTION:The value of DELTAepsilon/epsilonrt. angle which is the ratio of the dielectric constant anisotropy DELTAE of the nematic liquid crystal sealed into the spacing between a lower substrate 1 and an upper substrate 4 and the dielectric constant epsilonrt. anglein the direction perpendicular to the molecular axes of the liquid crystal is specified to <=0.5. The value of K33/K11 expressed by the ratio of the spray elastic constant K11 and bending elastic constant K33 of the liquid crystal 8 is specified to <=0.8. The smaller values of the ratio DELTAepsilon/epsilonrt. angle of the dielectric constants and the elastic constant ratio K33/K11 are more preferable. More specifically, the DELTAepsilon/epsilonrt. angle is preferably 0.2-0.4 and the K33/K11<=0.75.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display element for time-division driving using a field-effect twisted nematic effect.

[Prior art and problems] Liquid crystal display device Fi having a plurality of pixels arranged in a matrix, display device for combiator terminal, television =)
! It is applied to image display devices such as in-line receivers. In recent years, image display device manufacturers have been particularly required to increase the size and improve the image quality, and therefore, it is desired to increase the number of pixels and improve contrast. A liquid crystal display device applied to such an image display device has a plurality of electrodes arranged on each inner surface of a pair of opposing substrates, and the opposing portions of these electrodes form a plurality of pixels arranged in a matrix. A simple matrix-type twisted structure configured to form a
Nematic liquid crystal display element (hereinafter referred to as matrix TN, L)
C, element]. This matrix T
N, LC, elements are driven in time division.

In such matrices TN, LC, and zero, if you try to increase the number of pixels in order to increase the resolution or increase the display area, you will inevitably have to increase the number of scanning lines and increase the number of time divisions. It becomes necessary to perform NWh.

However, in this case, as the number of time divisions increases, the difference in effective value voltage between the on electric field applied to the liquid crystal to turn on each pixel and the off electric field applied to the liquid crystal to turn off each pixel increases. As a result, the operating margin of the drive voltage becomes smaller, the contrast deteriorates, and the viewing angle characteristics also deteriorate.

The operating margin and contrast of a liquid crystal display element depend on the voltage-luminance characteristics.In other words, the steeper the change in transmittance in response to changes in the strength of the electric field applied to the liquid crystal, the larger the operating margin. and the contrast can be increased.The steepness of the voltage-luminance characteristic is
As shown in Figure 1, the voltage v at which the transmittance -lIE50% is
It is expressed as the ratio between so and the threshold voltage ve (hereinafter referred to as r value).

The closer the r value is to 1, the steeper the change in transmittance described above, the larger the operating margin, and the higher the contrast.

In addition, matrix display elements driven in a high time division,
Since the number of time divisions is large and one selection period is short, high-speed response is required.

As mentioned above, a matrix display element driven in a high time division has an 0 r characteristic close to 1.

■ Wide viewing angle.

0 Fast response speed.

is required.

The r characteristic has been studied by IL Sehadt et al. According to this research, it is known that the r value representing the steepness of the voltage-luminance characteristic is expressed by the following formula (I), and is in good agreement with the characteristic exhibited by an actual element.

・−・−(1) Here, v: Applied voltage when transmittance becomes 50− Vc: L threshold voltage K11: Spray elastic constant of liquid crystal K33: Bending elastic constant of liquid crystal Δε: Dielectric of liquid crystal Index anisotropy t1: Dielectric constant in the direction perpendicular to the liquid crystal molecular axis Δn: Refractive index anisotropy of liquid crystal 4: Liquid crystal layer thickness 1: Wavelength of light According to this formula (!) K, S rflt should be close to 1 It is clear that the first, second, and third terms of the open equation should each be close to 1. Therefore, in order to improve the r-value characteristics, (-) the ratio between the splay elastic constant K11 and the bending elastic constant K33 of the liquid crystal (hereinafter referred to as elastic constant ratio K11/K11) should be small.

佽) The ratio between the dielectric constant in the direction perpendicular to the molecular axis of the liquid crystal and the dielectric anisotropy Δε (hereinafter referred to as the dielectric constant ratio Δξ/ljL) is small.

(e) The value of the product Δnod of the refractive index anisotropy Δn of the liquid crystal and the liquid crystal layer thickness d is 1.1 (μm) when the wavelength of the incident light is 550 nm.

All you have to do is satisfy both of them at the same time.

In addition, regarding the dependence of contrast on the viewing direction (hereinafter referred to as viewing angle characteristics), please refer to Mr. G and Mr. B. UR.
Researched, Molecule erystala an
dllquldcrystals, Volume
63, Now 1 to 4 #1981 e[
The Influ@nc@ of Mat@rim
l and Device Paramster o
n the Optial Character
lgtiemof Llquld Crystal D
lgplaya JK reported. According to this report, the viewing angle characteristics depend on the liquid crystal layer thickness d of the liquid crystal display element and the refractive index anisotropy Δn of the liquid crystal. In other words, a liquid crystal display element with a large liquid crystal layer thickness d and a liquid crystal refractive index anisotropy Δn (Δnod (hereinafter referred to as Δnod)) has a large The viewing angle characteristics are poor because the rate of change in nod is large.On the other hand, liquid crystal display elements with a small Δnod have good viewing angle characteristics.
When comparing liquid crystal display elements having the same values, the smaller the refractive index anisotropy Δn of the liquid crystal, the better the viewing angle characteristics. Finally, good viewing angle characteristics mean that contrast changes little with changes in viewing direction. Therefore, in order to improve the viewing angle characteristics, it is necessary to (reduce Δnod).

(0) Reduce Δn.

All you have to do is satisfy.

Furthermore, regarding the response characteristics, the response time t when the liquid crystal display element is turned on. N, and response time t when turning off. 11 is the following logical formula (6).

It is expressed as [phase] and is known to show good agreement with actual measured values.

toN=da/(80ΔξE −xq)
−−−−−−−−(1) tOFF = Da/Kq 2
----------410 where mite viscosity ε0: dielectric constant in vacuum E: electric field strength K2. : Torsional elastic constant Equation (II) (According to DO, the response speed mainly depends on the viscosity Da and the electric field strength E. In other words, to increase the response speed, (f) reduce the viscosity Da to do.

(b) Increase the electric field strength.

All you have to do is satisfy.

Based on the above-mentioned technical background, the conventional matrix, so-called LC, element has been developed such that among the conditions (a) to (C) for making the r% property steep, the requirement regarding ln-dK is r.
Since the center of the wavelength band of visible light is approximately 550 nm, Δnod should be set to approximately 1.
．． 1 (fivm). In this case, the refractive index anisotropy Δn of the liquid crystal is generally in the range of 0.13 to 0.16, and the liquid crystal layer thickness (interelectrode gap) is 17.0.
~8.5Cμm].

Such a conventional liquid crystal display element has an in-d value of 1.1.
(so the contrast is relatively high)? show.

However, it is still not possible to obtain a sufficiently high contrast.

Furthermore, since the value of in-d is large, the viewing angle characteristics are poor, and the value of the thickness d of the C1 liquid crystal layer is also large, resulting in a slow response speed.

If the liquid crystal layer thickness d is made smaller in order to increase the response speed, the value f of Δnod must be increased to 0.147 or more in order to satisfy the Δnod condition for obtaining high contrast. However, in this case, since the value of Δn is large, the viewing angle characteristics further deteriorate. Furthermore, if the values of the liquid crystal layer thickness d and Δn are decreased in order to improve viewing angle characteristics and response speed, the value of Δnod will greatly differ from the optimum value of 1.1], resulting in a significant decrease in contrast. Therefore, high contrast, wide viewing angle, and high speed response cannot be fully satisfied.

As mentioned above, with conventional liquid crystal display elements, it is difficult to obtain image display with sufficiently high contrast. It was difficult to display images with sufficient display quality.

The present invention was made to solve the above-mentioned problems, and its purpose is to provide a liquid crystal display element capable of displaying a high contrast image. A further object of the present invention is to provide a liquid crystal display element that satisfies all the characteristics of high contrast, wide viewing angle, and high-speed response, and is suitable for high time division driving.

[Means for Solving the Problems] In order to achieve all of the above objects, the present invention provides a pair of opposing substrates; and a plurality of electrodes arranged and formed on opposing inner surfaces of the pair of substrates so as to face each other. and: an alignment film formed on each of the inner surfaces of the pair of substrates on which the plurality of electrodes are formed and oriented in a predetermined direction; and the dielectric constant ratio Δξ of 0.5 or less, which is expressed as the ratio of the dielectric anisotropy Δε and the dielectric constant in the direction perpendicular to the liquid crystal molecular axis direction.
/C soil, and a nematic liquid crystal having an elastic constant ratio K33/K11 of 0.8 or less expressed by the ratio of the splay elastic constant K11 to the bending elastic constant K33: arranged with the nematic liquid crystal in between. Provided is a liquid crystal display element having a pair of polarizing plates.

The liquid crystal display element of the present invention having the above-described configuration has a dielectric constant ratio Δξ/ξ and an elastic constant ratio K33/K as a liquid crystal.
11 both use extremely small nematic liquid crystals.

This dielectric constant ratio Δg/ξ1 and elastic constant ratio K33/K1
The value of 1 means that the conventional liquid crystal compositions have a value of Δξ/discharge=1.
0 or more, which is extremely small compared to K, s/K11 = about 1.2 to 1.3. The liquid crystal display element of the present invention obtained by interposing the liquid crystal composition having such extremely small dielectric constant ratio Δξ/ξ1 and elastic constant ratio K11/K11 C value between the electrodes has rI! ! Improved f properties and extremely high contrast.

Furthermore, the above-mentioned equation (1) expressing the r characteristic is not applied to the liquid crystal display element of the present invention. In other words, the requirements for optimizing the r characteristic derived from equation (1) (a) s (b) #
A very optimal r% property can be obtained under conditions different from those in (e).

That is, for a liquid crystal display element using a liquid crystal composition in which the dielectric constant ratio Δε/e is 0.5 or less and the elastic constant ratio K33/K11 is 0.8 or less, observation from approximately the front direction of the liquid crystal display element is possible. Contrast when
The value of n-d is from 0-50 (μm) to 0.70 (μm)
] exists within the range. Preferably the value of Δn-d is 0.5
4 to 0.70, more preferably 0.70.
It ranges from 54 to 0.65. As described above, in the liquid crystal display element of the present invention, the value of the dielectric constant ratio lξha± of the liquid crystal and the value of the elastic constant ratio K11/K11 are extremely small, so that Δ
High contrast can be obtained with a small value of nd. Also,
Since the liquid crystal layer thickness d can be made small, a high-speed response can be obtained, and since Δn and Δn−d are small, the viewing angle characteristics are also good.

Therefore, the electro-optical characteristics of a liquid crystal display element driven in a high time division manner are extremely improved.

In the present invention, it is desirable that the values of the elastic constant ratio K33/K, and the value of the dielectric constant ratio ΔC/# soil are each as small as possible. Specifically, the value of the dielectric constant ratio Δt/e is preferably in the range of 0.1 to 0.5, more preferably in the range of 0.2 to 0.4.

Also, elastic constant ratio K3. The value of /K, , is larger than the value that can be realized as a liquid crystal composition and is 0.8 or less, for example, 0.2 or Fi0.4 or more and 0.8 or less.

Furthermore, the liquid crystal layer thickness dFi is changed from 4.0 fim to 8
．． It is desirable to set it in the range of 0 μm, and the more desirable range F1 is from 4.0 μm to 7.0 μm.

When Δn@d is set in the range of 0.54 μm to 0.70 μm, the liquid crystal layer thickness d is 4.0 μm to 7.0 μm.
It is desirable to set the range to 6, more preferably 6.
It is less than μm. Moreover, the refractive index anisotropy Δn of the liquid crystal is 0
．． It is desirable to set the value in the range from 0.08 to 0.14, and more preferably, the value is less than 0.12.

[Example] Examples using the present invention will be described in detail below. First, regarding the matrix TN, LC, and element of the present invention,
This will be explained with reference to the drawings. In FIGS. 2 and 3, the top K of the lower substrate 1 made of a transparent glass plate or an optically isotropic glass plate is oriented in the vertical direction K in FIG. 3. The first electrode 2 ! ,−
... are arranged in plurality, and these first electrodes! , 2-
An alignment 1115 that has been subjected to alignment treatment is released covering the surface of the substrate on which the . . . are arranged. On the upper substrate 4 made of the same material as the lower substrate 1, a plurality of second electrodes 5, 5-, etc., which extend in the horizontal direction in FIG. 3, are arranged, and these second electrodes S, S- An alignment film 6 subjected to an alignment process is formed to cover the substrate surface on which the... are arranged. These lower substrate 1 and upper substrate 4 are placed facing each other with a predetermined gap maintained, with the surfaces on which the first electrodes 2, 2-... and second electrodes 5, 5-... are formed facing inside. It is bonded with a sealing material 1. In the gap between these lower substrate 1 and upper substrate 4,
A nematic liquid crystal 8, which will be described later, is sealed. This nematic liquid crystal 8 has a first electrode 2, a second electrode 5, 5...
・A liquid crystal layer with a thickness of d is formed between. A pair of polarizing plates 9 and 10 are disposed on the outer sides of the lower substrate 1 and the upper substrate 4, respectively.

Figure 4A and 4th Brl! J indicates the orientation treatment direction of the orientation films 3 and 6 and the direction of the polarization axes of the pair of polarizing plates 9 and 10. The orientation 1M3e6 formed on the electrode forming surfaces of the lower substrate 1 and the upper substrate 4 is as shown in FIG. 4A.
Has been rubbed. That is, the alignment film 3 of the lower substrate 1 is rubbed in the alignment treatment direction 11 shown by the broken line arrow, and the alignment film 6 of the upper substrate 4 is rubbed in the alignment treatment direction 11 shown by the solid line arrow that intersects with the alignment treatment direction 11 at approximately 90 degrees. Rubbing processing is performed in the orientation processing direction 12. In the nematic liquid crystal 8 sealed between the upper and lower substrates 1.4 which have been subjected to rubbing treatment in directions different from each other by approximately 9 G, the liquid crystal molecules are twisted by approximately 90 degrees. The polarizing axis of the pair of polarizing plates 9 and 100 is the fourth A
As shown in the figure, the polarizing axis 13 of the lower polarizing plate 9 (indicated by the broken line arrow) and the polarizing axis 14 of the upper polarizing plate 10 (indicated by the solid line arrow) are substantially parallel to each other, and are formed on the upper substrate 4. Orientation film 6
It is substantially parallel to the orientation processing direction 12 of. In addition, upper and lower polarizing plates 1
As shown in FIG. 48, the polarization axis at 0°9 is such that the polarization axis 13 of the lower polarizing plate 9 and the polarization axis 14 of the upper polarizing plate 10 are approximately ♀
The alignment direction 11 of the alignment film 3 formed on the lower substrate 1 may be substantially parallel to the alignment direction 11 of the alignment film 3 formed on the lower substrate 1.

The above-mentioned liquid crystal display element has a lower substrate 1 as shown in FIG.
Terminal 2 of the first electrode 2.2°... which protrudes at the end of the terminal 2.
m, 2*... is the lead i! i! Terminals 5&, 5 of the second electrodes 5, 5-... are connected to the drive circuit 16 via 15915... and extend to the end of the upper substrate 4.
m is connected to the drive circuit 16 via lead wires 11.1. In such a liquid crystal display element, the first electrodes 2, 2-, etc. formed on the lower substrate 1 constitute the column electrodes 18, and the second electrodes S, 2, etc. formed on the upper substrate constitute the column electrodes 18.
S, -- constitute the row electrodes 19. A portion where these column electrodes 18 and row electrodes 19 intersect with each other via a nematic liquid crystal forms one pixel. The row electrodes 19 are provided with respective second electrodes from the drive circuit 16.
A scanning signal is supplied to sequentially apply a voltage to the electrodes 5.5°, and the column electrodes 18K receive a data signal corresponding to image data in synchronization with the scanning signal to each of the first electrodes J, ill-... is supplied. In this way, the lighting state of each pixel is controlled by applying an electric field to the nematic liquid crystal at the intersection of the row electrode 19 and column electrode 18 and causing the liquid crystal molecules of the nematic liquid crystal to behave. That is, this liquid crystal display element is time-divisionally controlled.

The liquid crystal display element of the present invention is a nematic liquid crystal in which the ratio Δε/e between the dielectric anisotropy Δε and the dielectric constant ε in the direction perpendicular to the liquid crystal molecular axis is 0.5 or less, and the spray elasticity number K1
1 and the bending elastic constant K33, K33/IC.

A liquid crystal composition having a value of 0.8 or less is used. The value of the product Δnad of the liquid crystal layer thickness d and the refractive index anisotropy Δn is 0.5
It is 4 or more and 0.7 or less. In other words, in liquid crystal display elements where the dielectric constant ratio Δε/l of nematic liquid crystal is small, the dielectric constant changes little in response to changes in the alignment state of liquid crystal molecules, and the equivalent impedance of the liquid crystal changes little. Since the linearity of the electric field applied to the liquid crystal with respect to the voltage applied to the liquid crystal becomes better, the contrast is improved. In addition, the response speed of the liquid crystal display element is expressed by the above-mentioned formula (II), GO
), which can be transformed as . As is clear from these formulas (V) and (m), the liquid crystal display element of the present invention using the liquid crystal composition in which the spray elastic constant K11 of the nematic liquid crystal is increased and the elastic constant ratio K117K11f is decreased, has a startup time of 9. time tons
and the fall time is 9 hours t. Both FFs are small and respond at high speed. In this way, a liquid crystal display element using a nematic liquid crystal in which the dielectric constant ratio Δg/g is small and the elastic constant ratio K11/K11 is small is not subject to the above-mentioned CI), and high contrast can be obtained. In addition, this liquid crystal display element company, Δ
The best electro-optical properties are obtained in a certain range of values of n4 smaller than 1.1.

Therefore, since the value of Δnd is small, the viewing angle characteristics can be improved, and dt can be made small, so that the electric field strength applied to the liquid crystal can be increased to achieve a high-speed response.

A plurality of liquid crystal display elements of the present invention configured in this manner.
These electro-optical properties were measured. These liquid crystal display elements are some specific examples having different liquid crystal layer thicknesses di and using different liquid crystal compositions. The components and electro-optical characteristics of these examples are as follows:
It is shown in Table 1 below. In Table 1, the refractive index anisotropy Δn is a value measured at λ-589 nm. Contrast is the value Y of transmittance when on in the direction of viewing angle θ=10° when driven with a drive signal of 1/64 deity. N is the transmittance value Y when off. The value divided by 11 (YON/Y
OFF). The temperature at the time of measurement was 25° C. The threshold voltage, viewing angle characteristics, and response speed were measured values when driven with the lk[z static drive signal. Further, the threshold voltage vthFi is defined as the applied voltage at which the transmittance is 50%K. The response speed is % (Tr+TD)/ where the rising time from 10- to 90% is Tr, and the falling time from 90- to 10% is TD. It is defined as a value of 2. The viewing angle characteristics are
As shown in Fig. 5, two lines perpendicular to the substrate surface of the liquid crystal display
The threshold voltage is Vth (a = 1 o) when observed from the direction P tilted 1σ from the axis to the viewing angle direction, and the threshold voltage is observed from the direction Q tilted 10'' from the two axes to the opposite direction from the viewing angle direction. Threshold voltage t-vth (θ=-11'')
When the temperature is 25℃, V (θ=-10)
It is defined as the value /Vth(θ=1f]h. The closer the value is to 1, the better the viewing angle characteristic is. In other words, the viewing angle is wider.

1 舊 Yabuko Iro Peek ■-Delivery■■1 Above Example 1
Examples 9 to 9 each have extremely high contrasts of 17 or more. Among these Examples, Example 1tj:, Δ
The value of nod is 1.12, which is almost the same as that of conventional liquid crystal display elements.
It is. However, the values of the dielectric constant ratio Δξ/ξ1 and the elastic constant ratio K11/K, , are 0.35 and 0.35, respectively.
The contrast is extremely small, 80 or less, so Example 1 exhibits an extremely high contrast.

Further, in Examples 2 to 9, the viewing angle characteristic is 1.07 or less, which means that the viewing angle is wide, and the response speed is about 30 smoke or less, which enables high-speed response. Therefore, these Examples 2 to 5111 all satisfy the above three characteristics, which were conventionally said to be contradictory characteristics. especially,
In Examples 2 to 4, since the liquid crystal layer thickness d is 6 μm or less, the response speed is extremely fast, and they are most suitable for liquid crystal display elements that display moving images such as television screen images. Moreover, the values of Examples 2 to 4Fi, Δnod, and elastic constant ratio K117K11 are completely equal. In this case, the contrast is improved in the example in which the value of the dielectric constant ratio ΔC/discharge is smaller.

Therefore, it is desirable that the dielectric constant ratio Δ1c1#i be smaller.

Example 51t, dielectric constant ratio Δξ/ξ1 and elastic constant ratio 3
This is an example in which the value of 3/K11 is particularly small, and the contrast and viewing angle characteristics are extremely good. Therefore, in order to improve the contrast and viewing angle characteristics, it is desirable that the values of the dielectric constant ratio Δεc1 and the elastic constant ratio K11 be as small as possible.

The liquid crystal display elements shown in Examples 1 to 9 each exhibit excellent characteristics, but as shown in Example 9, even when the same liquid crystal composition as in Example 4 is used, the response speed decreases as Δn-d decreases. Although the viewing angle characteristics are improved, the contrast is reduced. Furthermore, as shown in Example 7, when the value of Δnod exceeds 0.7, the response speed and viewing angle characteristics tend to deteriorate. Therefore, in order to obtain fast response and wide viewing angle, the Δn-jo value should be set to 0.5.
It is desirable to set it in a range of 4 or more and 0.70 or less.

In this case, as the refractive index anisotropy Δn increases, the viewing angle characteristics deteriorate, so in order to obtain a liquid crystal display element with a wide viewing angle, the refractive index anisotropy Δn must It is desirable that Δnij is 0.14 or less. Also,
Using the same liquid crystal composition, the liquid crystal layer thickness d was 7.0 μm and 8.0 μm.
As shown in Example 6.8K where the liquid crystal layer thickness was set to 0 μm, the response speed was as slow as 30 mse and the viewing angle characteristics also tended to deteriorate because the liquid crystal layer thickness d of Example 8#'i was as large as 8 μm. . Therefore, in order to obtain a response speed of 30 m5ec necessary for displaying moving images such as television images, it is desirable that the liquid crystal layer thickness be 7.0 μm or less.

Examples 1 to 9 described above are extremely excellent in various electro-optical characteristics, but have relatively high threshold voltages. This means that in order to make the dielectric constant ratio Δε/ξ1 less than 0.5, the value of C of commonly used liquid crystallized metals must be 3 to 3.
5, the value of Δξ of the composition can only be increased to about 3 at most. However, as expressed by equation (IV), when Δε is small, the threshold voltage V becomes high. A high threshold voltage vc increases the voltage of a drive signal for driving the liquid crystal display element. However, this drive signal can be arbitrarily set by the drive circuit. For example, when driving with the optimum bias using a drive signal of 1/64 deity, the threshold voltage is 4.5% as in the second embodiment. In the case of Ov, the voltage of the Fi drive signal i24
V, the threshold voltage is 4.5V as in Example 4.6.8.
In this case, the voltage of the expansion drive signal is set to 27V, and when the threshold voltage is 5V as in Example 7, the voltage of the drive signal is set to 30V, and further, when the threshold voltage is 5.5V as in Example 3. The drive signal voltage i may be set to 33V.As mentioned above, the value of the dielectric anisotropy Δε is preferably smaller than 33 and in the range of 1.5 from O, S, and more preferably the value of Δξ is less than 33. It is in the range of 0.8 to 1.2.

As described above, the liquid crystal display element of the present invention uses a liquid crystal composition having small values of elastic constant ratio K, s/K11, and Δξ/eL. Several examples of liquid crystal compositions having such characteristics are shown in Table 2 (composition weight -) where R and R represent an alkyl group. , among the liquid crystal compositions shown in Table 2, the liquid crystal compositions with corresponding numbers were used. In Example 8 and Example 9, liquid crystal compositions A6 and A4 shown in Table 2 were used, respectively. It is being

The liquid crystal composition shown in Table WE2 is Np with positive dielectric anisotropy.
Dielectric constant ratio Δ17a by reducing the blending ratio of liquid crystal compound
(By decreasing the value of 1) and increasing the blending ratio of a pyrimidine-based liquid crystal compound with a small elastic constant ratio K, 5/K, 1), the value of the elastic constant ratio K11/K11 of the liquid crystal composition can be increased. It's getting smaller. That is, these liquid crystal compositions,
In a mixture of Nn liquid crystal compounds with a negative electrical anisotropy Δε or almost 0, a liquid crystal compound with a positive electrical anisotropy Δ2 and a relatively large value, such as an Np liquid crystal having a cyano group at the terminal, is added. A small amount of the compound is present. As the Nn liquid crystal, a relatively large amount of a pyrimidine liquid crystal compound having a small elastic constant ratio K11/K11 is blended, and in addition to this, a low viscosity liquid crystal, a high temperature liquid crystal, etc. are blended. Each of the liquid crystal compositions prepared in this manner has a dielectric constant ratio Is/ξ of 0.5 or less, and an elastic constant ratio K33.
/K11 values are each 0.8 or less.

However, since these liquid crystal compositions shown in Table 1 contain a large amount of high-viscosity pyrimidine-based liquid crystal compounds, their viscosity is high (20 ep). Since the thickness d is relatively small, there is almost no decrease in response speed due to an increase in viscosity.

Table 3 below shows comparative examples for the examples of the present invention. The measurement conditions and definitions of each characteristic in this case are as described in the first section above.
Same as table.

l l 11$! I[*11111[11)g! I!
FIG. 6 shows the contrast values relative to the Δnod values for Examples 1 to 9 of the present invention and Comparative Examples a to f. In this Figure 6, the horizontal axis is the value of Δn''d, and the vertical axis is the value of fs contrast (CR).1Examples 1 to 9 and Comparative Examples a to f in Table 1 above are blotted, respectively. Here, the O mark indicates an example of the present invention), and the Δ mark indicates a comparative example.

As is clear from FIG. 6, the values of the dielectric constant ratio Δεc± and the elastic constant ratio K33/K11 are each 0.5 or less,
Examples 1 to 9tj of the present invention, in which the solera value was set to 0.8 or less, and Example 1, in which the Δn・d value was around 11, had extremely high funtorust compared to the comparative example with a large solera value. As is clear from a comparison of Comparative Example b1 and Example 3, in which the value of Δport·d is 0.6, and Comparative Examples, f, respectively, the contrast of the Example of the present invention is significantly high.

In addition, in the matrix display element of Comparative Example a%f shown in Table 3 above, the requirement (C) for reducing the r characteristic derived from the above-mentioned formula (1), that is, Δn-d
Comparative example bIIi, which satisfied −1 and 10, had a higher contrast amount than other comparative examples. However, the response speed is slow.

When the matrix display element is used to display the operation of all television receivers, etc., its response speed is 30 msec.
It is desirable that the response speed be less than or equal to c, and in order to obtain this response speed, according to the requirement ω for obtaining the response speed described above,
In order to increase the electric field strength, it is necessary to reduce the liquid crystal layer thickness d. For example, as in Comparative Examples a, c, and d in Table 4, the liquid crystal layer thickness d? High-speed response is obtained by setting the thickness to 745 μm or less. However, in this case, it is necessary to increase the refractive index anisotropy Δn of the liquid crystal), and the value of this refractive index anisotropy Δn is tiO, 147 or more.

On the other hand, among Comparative Examples a to d, Comparative Example a with the smallest 4n-d and Δn has better viewing angle characteristics, so the above-mentioned requirements for improving viewing angle characteristics (d) and (@) It is clear that the smaller Δnd and non are, the better. Therefore, a liquid crystal display element with a large Δn of 0.147 has poor viewing angle characteristics.

In order to improve the viewing angle characteristics and the response characteristics, Δn and Δn−d i− are reduced, and the comparison example in Table 3 is shown.

As shown in f, the viewing angle characteristics and response characteristics are improved, but the contrast is significantly reduced.

In this way, among the matrix display elements shown in Comparative Examples a%f, the comparative example with Δn-d = 1-1 (弽) exhibits the highest contrast, but its response characteristics are slow and there may be problems. Since Δn−d is also relatively large, viewing angle characteristics are poor. To improve this response characteristic, the liquid crystal layer thickness dt-
By reducing Δn to obtain good contrast,
′ft K must be increased by 0.147 or more, and Δn
Since this is large, the viewing angle characteristics are further deteriorated. In addition, in order to improve the viewing t-angle characteristics and response speed, as shown in Comparative Example .
Since the value of -d is significantly different from the optimum value 1, 1, the contrast strength is significantly reduced. Therefore, comparative examples a-f
lj High contrast, wide viewing angle, and fast response cannot all be satisfied at the same time.

The physical characteristics of the liquid crystal of Comparative Examples a to f in Table 3 described above are obtained by a liquid crystal composition in which the liquid crystal compounds shown in Table 4 are mixed at the respective compounding ratios. Comparative example a
-f, liquid crystal compositions with corresponding codes are used. In this Table 4, R, RIIFi represents an alkyl group, and R' represents an alkyl group and an alkoxy group.

Table 4 t i Mixing ratio (weight 9G) 11
1+11111 These liquid crystal compositions have a Δε value of 1
0, and the viscosity is less than ij20cp (measurement temperature 20℃
]. Since the value of the galvanic rate ε of a liquid crystal compound is generally about 3 to 5, the value of Δε/e is 1 or more. In addition, liquid crystal compounds with a small elastic constant ratio K11/K (for example, pyrimidyl-based liquid crystal compounds) have high viscosity and poor compatibility, resulting in a total increase in the viscosity of the composition.
In addition, since the smectic phase is more likely to be exhibited, the proportion of the smectic phase is small in conventional liquid crystal compositions, and the elastic constant ratio K33/
The value of K11 is 1.2 to 1.3 or more.

As described above, the examples of the present invention exhibit superior characteristics in terms of contrast, viewing angle characteristics, and response speed, compared to the above-mentioned comparative examples. Among these examples,
In particular, Examples 2 to 7 have fast response speeds and are optimal for displaying moving images such as television images.

In the above-mentioned embodiment, a liquid crystal display element having a twist angle of approximately 906° has been shown. It can also be applied to liquid crystal display elements.

As mentioned above, the letters, numbers,
It can also be used in a display device for displaying all figures, etc. It can also be applied to display devices for television receivers. For example, red, blue, and green color filters are provided corresponding to the column electrodes shown in FIGS. 2 and 3.
One pixel is formed by the intersections of three column electrodes and row electrodes corresponding to three colors, and a color data signal t is applied to the column electrode for each color.
Apply. Accordingly, the present invention can be applied to a color liquid crystal display device in which each pixel is displayed in full color.

[Effects of the Invention] As detailed above, according to the present invention, a liquid crystal display element capable of displaying a high contrast image is provided. The liquid crystal display element of the present invention exhibits high contrast, wide viewing angle, and high-speed response, and is suitable for high time division driving.

[Brief explanation of the drawing]

Fig. 1 is a luminance-voltage characteristic diagram for defining the r@ property of a liquid crystal display element; Fig. 2 is a sectional view showing an embodiment of the present invention; Fig. 3:
An exploded perspective view showing a schematic structure of the liquid crystal display element of the present invention; Figures 4A and 48 show the direction of alignment treatment of the alignment film and the direction of the polarization axis of the polarizing plate in the liquid crystal display element K of the present invention. An explanatory diagram showing the relationship between: Figure 5 is a perspective view showing the definition of viewing and angle characteristics; Figure 6 is a perspective view showing the definition of viewing angle characteristics;
FIG. 3 is a chart showing the relationship of contrast to the value of Δnod for Examples and Comparative Examples of the present invention. 1.4... Substrate, 2.5... Electrode, J, 5-...
- Alignment film, 1... Seal material, 8... Nematic liquid crystal, 9.10... Polarizing plate. Applicant's representative Patent attorney Takehiko Suzue; Japan vCv50 (EFKGi pressure v) Figure 1 Figure 2, 4, 15

Claims (20)

[Claims] (1) A pair of opposing substrates; A plurality of electrodes arranged and formed on opposing inner surfaces of the pair of substrates so as to face each other; Each of the inner surfaces of the pair of substrates on which the plurality of electrodes are formed. an alignment film that is formed on the substrate and is aligned in a predetermined direction; and an alignment film that is interposed between facing electrodes formed on the pair of opposing substrates, and that has a dielectric anisotropy Δε and a dielectric film that is perpendicular to the liquid crystal molecule axis direction. Ratio Δε of permittivity of 0.5 or less expressed as a ratio to
/Δε⊥, and a nematic liquid crystal having an elastic constant ratio K_3_3/K_1_1 of 0.8 or less expressed by the ratio of a splay elastic constant K_1_1 to a bending elastic constant K_3_3; A liquid crystal display element characterized by comprising a pair of polarizing plates. (2) The liquid crystal display element according to claim 1, wherein the nematic liquid crystal has a dielectric constant ratio Δε/ε⊥ of 0.1 to 0.5. (3) The liquid crystal display element according to claim 2, wherein the value of the dielectric constant ratio Δε/ε⊥ is 0.2 or more and 0.4 or less. (4) The nematic liquid crystal has a dielectric anisotropy Δ smaller than 3.
The liquid crystal display element according to claim 1, having a value of ε. (5) The value of the dielectric anisotropy Δε is 0.5 or more and 1.
5. The liquid crystal display element according to claim 4, wherein the number is 5 or less. (6) The liquid crystal display element according to claim 1, wherein the nematic liquid crystal has an elastic constant ratio K_3_3/K_1_1 of 0.75 or less. (7) a pair of opposing substrates; a plurality of electrodes arranged on opposing inner surfaces of the pair of substrates so as to face each other; and each inner surface of the pair of substrates on which the plurality of electrodes are formed. an alignment film that is formed on the substrate and is aligned in a predetermined direction; and an alignment film that is interposed between facing electrodes formed on the pair of opposing substrates, and that has a dielectric anisotropy Δε and a dielectric film that is perpendicular to the liquid crystal molecule axis direction. Ratio Δε of permittivity of 0.5 or less expressed as a ratio to
/ε⊥, the value of the elastic constant ratio K_3_3/K_1_1 of 0.8 or less expressed by the ratio of the splay elastic constant K_1_1 and the bending elastic constant K_3_3, and the product of the liquid crystal layer thickness d and the refractive index anisotropy Δn. A nematic liquid crystal having a liquid crystal layer thickness d and a refractive index anisotropy Δn such that the value of Δn・d is 0.5 (μm) or more and 0.7 (μm) or less; sandwiching the nematic liquid crystal; A liquid crystal display element comprising a pair of arranged polarizing plates. (8) The nematic liquid crystal has a product Δn・d of 0.54.
8. The liquid crystal display element according to claim 7, wherein the refractive index anisotropy Δn and the liquid crystal layer thickness d have a value of 0.7 or less. (9) The liquid crystal display element according to claim 8, wherein the value of the product Δn·d is 0.65 or less. (10) The nematic liquid crystal is 0.08 or more, 0.14
The liquid crystal display element according to claim 7, having the following value of refractive index anisotropy Δn. (11) The liquid crystal display element according to claim 10, wherein the value of the refractive index anisotropy Δn is smaller than 0.12. (12) The liquid crystal display element according to claim 7, wherein the nematic liquid crystal has a liquid crystal layer thickness d of 4 μm or more and 8 μm or less. (13) The liquid crystal display element according to claim 12, wherein the liquid crystal layer thickness d is 7.0 μm or less. (14) The pair of polarizing plates are arranged such that their polarization axes are parallel to each other and substantially perpendicular or parallel to the alignment direction of liquid crystal molecules adjacent to the alignment film formed on one substrate. The liquid crystal display element according to claim 7. (15) The alignment film is aligned in a direction substantially perpendicular to a first alignment film on one substrate that has been aligned in one direction and the direction of the alignment treatment of the first alignment film. and a second alignment film on the other substrate, whereby the liquid crystal molecules of the nematic liquid crystal interposed between the first and second alignment films are twisted at approximately 90° between the two substrates. The liquid crystal display element according to claim 7. (16) The plurality of electrodes include a plurality of first electrodes extending in the horizontal direction and arranged in parallel on the inner surface of one of the pair of substrates, and a plurality of first electrodes extending in the vertical direction and arranged in parallel on the inner surface of the other substrate. and a plurality of second electrodes arranged in
8. The liquid crystal display element according to claim 7, wherein the plurality of first electrodes and the plurality of second electrodes intersect with each other through the nematic liquid crystal to form a plurality of pixels arranged in a matrix. (17) connected to the plurality of first electrodes to supply a scanning signal to the first electrodes, and connected to the plurality of second electrodes to supply a data signal to the second electrodes; 17. The liquid crystal display element according to claim 16, further comprising driving means for time-divisionally driving the pixels. (18) A first substrate and a second substrate facing each other;
a plurality of first electrodes extending in one direction and arranged substantially in parallel on the inner surface of the substrate facing the first substrate; on the inner surface of the second substrate facing the first substrate; , a plurality of second electrodes extending in a direction intersecting the direction in which the first electrode is extended and arranged substantially in parallel; covering at least a surface of the first electrode on the first substrate; and a first alignment film that has been subjected to an alignment process in one direction; and a first alignment film that covers a surface of at least a second electrode on the second substrate and that is aligned in the direction of the alignment process of the first alignment film. a second alignment film that has been subjected to alignment treatment in a direction intersecting at approximately 90 degrees;
Spray elasticity is interposed between the second substrates, and the value of the dielectric constant ratio Δε/ε⊥ expressed as the ratio of the dielectric anisotropy Δε to the dielectric constant in the direction perpendicular to the liquid crystal molecule axis direction is 0.5 or less. Constant K_1
The value of the elastic constant ratio K_3_3/K_1_1 expressed as the ratio of the bending elastic constant K_3_3 to the bending elastic constant K_3_3 is 0.8 or less, and the product Δn・d of the liquid crystal layer thickness d and the refractive index anisotropy Δn
a nematic liquid crystal having a liquid crystal layer thickness d and a refractive index anisotropy Δn such that the value of is 0.5 (μm) or more and 0.7 (μm) or less; the nematic liquid crystal is placed between the pair of substrates; A liquid crystal display element comprising: a sealing member for sealing the nematic liquid crystal; and a pair of polarizing plates arranged with their respective polarization axes parallel to each other at positions sandwiching the nematic liquid crystal. (19) The nematic liquid crystal has a dielectric constant ratio Δε/ε⊥ of 0.1 or more and 0.5 or less, and a value of 0.54 or more and 0
．． 19. The liquid crystal display element according to claim 18, having a refractive index anisotropy Δn and a liquid crystal layer thickness d of 7 or less. (20) further comprising driving means connected to the first electrodes to supply scanning signals to the first electrodes and connected to the second electrodes to supply data signals to the second electrodes; The liquid crystal display element according to claim 18.