JP2000310797A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain fast response and high contrast and to realize low driving voltage in an active matrix liquid crystal display device using a transverse electric field method. SOLUTION: In this liquid crystal display device, spacers are disposed in a nondisplay region, and the liquid crystal layer contains a structural component having a dielectric anisotropy Δε<=1 by >=40 wt.% and <100 wt.%. The direction of alignment control of liquid crystal molecules on the two interfaces between the liquid crystal layer and a pair of substrates is almost parallel to each other. The polarization axis of one polarizing plate is almost coincident with the direction of alignment control of the liquid crystal molecules on the interfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device, and more particularly to an active matrix type liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display device changes the alignment direction of liquid crystal molecules by applying an electric field to the liquid crystal molecules of a liquid crystal layer sandwiched between substrates, and utilizes the resulting change in the optical characteristics of the liquid crystal layer. Display. In a conventional active matrix type liquid crystal display device, a direction of an electric field applied to the liquid crystal is almost perpendicular to a substrate interface, as represented by a twisted nematic (TN) display method in which display is performed using the optical rotation of the liquid crystal. Direction was set. On the other hand, a method of performing a display using a birefringent property of a liquid crystal by using a comb-shaped electrode to make the direction of an electric field applied to the liquid crystal substantially parallel to the substrate (lateral electric field method) is, for example, a special method. Kosho 63-2190
7, and Japanese Patent Publication No. 5-505247. The horizontal electric field method has an advantage of a wider viewing angle than the conventional TN method, and is a promising technology as an active matrix liquid crystal display device.

As a liquid crystal material for an in-plane switching type active matrix type liquid crystal display device, a liquid crystal composition having a relatively low specific resistance (Japanese Patent Laid-Open Publication No. Hei 7-306417) is used to achieve both low driving voltage and high speed response. For that, 4-
A liquid crystal composition containing (cyclohexylcarbonyloxy) benzonitrile (Japanese Patent Application Laid-Open No. 9-125063),
Liquid crystal compositions containing compounds having fluorine as a polar group (JP-A-9-255596, JP-A-10-67)
988), a liquid crystal composition containing a component having a cyano group (Clement et al., SID International Symposium 98, 26.3 (International Sympos)
ium 98, 26.3)).

In the lateral electric field method, it is known that the response time and the driving voltage of the liquid crystal and the physical properties of the liquid crystal material have the relationship shown in the following [Equation 1] and [Equation 2] (Oe). Masato, Katsumi Kondo, Applied Physics Letters, 67, 3895-3897, 1995, Masato Oe, Katsumi Kondo, Applied Physics Letters,
69, 623-625, 1996).

[0005]

数 offoffγ1 × d ² / K22 (Equation 1)

[0006]

(Equation 2)

Here, Vth is the threshold voltage of the liquid crystal, K22
Is the twist elastic constant of the liquid crystal material, Δε is the dielectric anisotropy, L is the electrode spacing (FIG. 1), d is the thickness of the liquid crystal layer (FIG. 1), and τoff is the liquid crystal from when a voltage is applied to when no voltage is applied. , And γ1 represents the rotational viscosity coefficient of the liquid crystal. In order to keep d × Δn almost constant in order to maintain the optical characteristics,
[Equation 1] and [Equation 2] can be converted into [Equation 3] and [Equation 4], respectively.

[0008]

Τoff∝γ1 / (K22 × n ² ) (Expression 3)

[0009]

(Equation 4)

As can be seen from the above equation, the viscosity coefficient γ of the liquid crystal
The smaller the value of 1, the shorter the response time, and the larger the Δε, the lower the drive voltage. However, in many liquid crystal materials, the viscosity is approximately proportional to Δε, that is, a liquid crystal with a small Δε has a low viscosity, and a large Δε tends to have a high viscosity. This is because a material having a large Δε tends to have a high polarity, that is, a large dipole moment of a molecule, and a material having a large dipole moment has a strong interaction between molecules, resulting in an increase in the viscosity of the entire liquid crystal. There is a cause. Therefore, in the horizontal electric field method, there is a trade-off between the high-speed response of the liquid crystal and the low driving voltage. That is, if a large amount of a low-polarity component having a relatively low viscosity of Δε ≦ 1, that is, a so-called neutral component, is added, the viscosity decreases and a high-speed response is achieved, but at the same time, the driving voltage increases. Also, if a large amount of a high-polarity liquid crystal component having a large Δε is added, the driving voltage can be reduced, but the viscosity increases and the response of the liquid crystal becomes slow. Furthermore, no method has been proposed for controlling K22, which is another parameter governing the drive voltage and response time.

On the other hand, many techniques have been developed for arranging spacers in a non-pixel region for maintaining a constant interval between a pair of substrates in order to increase the contrast. For example, Japanese Patent Application Laid-Open Nos. Hei 10-170928, Hei 9-61828, Hei 6-250194, Hei 5-531
JP-A-21, JP-A-5-173147, JP-A-5-173147
Methods described in JP-A-160433, JP-A-8-292426, JP-A-7-325298 and the like have been proposed.

[0012]

As described above, in a conventional liquid crystal material for an in-plane switching type active matrix type liquid crystal display device, there is a trade-off between the response time of the liquid crystal and the driving voltage, that is, the neutral component of the liquid crystal. When the response time is shortened due to the decrease in viscosity due to the increase, the drive voltage increases, and when the drive voltage is reduced, the response time becomes longer. There is a problem that it is difficult to achieve both low driving voltage and low driving voltage. The control method of the twist elastic constant K22 of the liquid crystal has not been clarified so far.

Further, as a result of experiments, it has been found that in the lateral electric field type active matrix type liquid crystal display device, there is a trade-off between high-speed response and high contrast. This increases the content of neutral components in the liquid crystal layer,
When an attempt was made to increase the response speed by lowering the viscosity of the liquid crystal, a phenomenon occurred in which the contrast was reduced, and in particular, the luminance during black display was increased. In an in-plane switching mode active matrix type liquid crystal display device, a polarizing plate arranged so that polarization axes are substantially orthogonal to each other is generally used as an optical means for changing optical characteristics according to a molecular alignment state of a liquid crystal layer. In this case, a so-called normally closed mode in which the transmittance increases as the voltage applied to the liquid crystal layer is increased. In the case of this normally closed mode display method, light is emitted from the periphery of the spacer during black display because the orientation of the liquid crystal around the spacer to keep the substrate interval constant is different from the orientation control direction between the substrate and the liquid crystal layer. This results in leakage, an increase in black luminance, and a decrease in contrast. As a result of the investigation, it was found that when the content of the neutral component in the liquid crystal layer was increased, light leakage from the periphery of the spacer was increased, the luminance during black display was increased, and as a result, the contrast was lowered.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems of the prior art, and a first object of the present invention is to provide a lateral electric field type active matrix type liquid crystal display device which achieves both high-speed response and high contrast. It is in. A second object of the present invention is to provide an in-plane switching mode active matrix type liquid crystal display device which achieves both high-speed response and high contrast while achieving a low driving voltage.

[0015]

According to one embodiment of the liquid crystal display device of the present invention, there are provided a pair of substrates spaced by a spacer, a liquid crystal layer filled between the pair of substrates,
An electrode group formed on one of the pair of substrates to apply an electric field to the liquid crystal layer, and a pair of polarizing plates disposed with the liquid crystal layer interposed therebetween and having polarization axes substantially orthogonal to each other, and a spacer is provided. In the non-display area, the liquid crystal layer has a dielectric anisotropy Δε
≦ 1 is contained in an amount of 40% by weight or more and less than 100% by weight, the orientation control directions of liquid crystal molecules at two interfaces between the liquid crystal layer and the pair of substrates are substantially parallel, and the polarization axis of one polarizing plate is That is, the alignment control direction of the liquid crystal molecules at the interface is almost the same.

Another embodiment of the liquid crystal display device of the present application is as follows.
A pair of substrates having an interval defined by spacers, a liquid crystal layer filled between the pair of substrates, and an electrode group formed on one of the pair of substrates to apply an electric field to the liquid crystal layer. A pair of polarizing plates disposed with the liquid crystal layer interposed therebetween and having polarization axes substantially orthogonal to each other.
1 and the refractive index anisotropy Δn are 1 × 10 ³ mPa · s ≦ γ
1 / Δn ² ≦ 1.2 × 10 ⁴ mPa · s.

According to still another embodiment of the liquid crystal display device of the present invention, a pair of substrates having an interval defined by a spacer, a liquid crystal layer filled between the pair of substrates, and an electric field applied to the liquid crystal layer. An electrode group formed on one of the pair of substrates, and a pair of polarizing plates that are disposed with a liquid crystal layer interposed therebetween and whose polarization axes are substantially orthogonal to each other, and the spacer is disposed in a non-display area. The liquid crystal layer has a dielectric anisotropy Δε ≦ 1
Containing 40% by weight or more and less than 100% by weight of
The rotational viscosity coefficient γ1 and the refractive index anisotropy Δn of the liquid crystal layer are 1 × 10 ³ mPa · s ≦ γ1 / Δn ² ≦ 1.2 × 10 ⁴
mPas, and the alignment control directions of the liquid crystal molecules at two interfaces between the liquid crystal layer and the pair of substrates are substantially parallel, and the polarization axis of one polarizing plate and the alignment control direction of the liquid crystal molecules at the interface are substantially equal. They are in agreement.

The content of the neutral component is preferably 40% by weight or more and 90% by weight or less.

In still another embodiment of the liquid crystal display device of the present application, the liquid crystal layer of the liquid crystal display device contains a compound having a structure represented by the following chemical formula in a molecule.

[0020]

Embedded image

(Wherein X1 and X2 represent H or F) Further, in the liquid crystal layer, a low-polarity component having a dielectric anisotropy Δε ≦ 1 and a high-polarity component represented by the above formula are provided. Characterized by containing a component of medium polarity. The medium-polarity liquid crystal component may be a liquid crystal component having a structure selected from the group consisting of the following formula.

[0022]

Embedded image

[0023]

Embedded image

(Wherein X1 and X2 represent H or F. A represents a benzene ring or a cyclohexane ring)

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the principle of operation of a lateral electric field system as a premise of the present invention will be described with reference to an example of FIG. FIG.
7A and 7B are diagrams showing the operation of the liquid crystal in the liquid crystal panel of the horizontal electric field type, wherein FIGS. 7A and 7B are side sectional views, and FIGS. 7C and 7D are plan views. In the whole display element, a plurality of pixels are formed by forming stripe-shaped electrodes in a matrix.
Shows a part of one pixel. FIG.
The angle Φ formed by the polarizing plate transmission axis direction 112 with respect to the direction 1
The definition of p and the angle ΦLC formed by the orientation direction 111 of the long axis (optical axis) of the liquid crystal molecules near the substrate interface will be described.

FIG. 1A shows a state of the liquid crystal when no voltage is applied, and FIG. 1C shows a plan view at that time. A striped electrode 10 is provided inside a pair of transparent substrates 101 and 101 '.
2, 103 are formed, and an orientation control film 108 is formed thereon. A liquid crystal composition layer is sandwiched between the two substrates. The distance between the substrates is held by a spacer (not shown). The rod-shaped liquid crystal molecules 106 are oriented in the orientation direction 111 indicated by the arrow by the orientation control film 108 so that 45 degrees ≦ | ΦLC | <90 degrees when no electric field is applied. Note that the dielectric anisotropy of the liquid crystal is assumed to be positive. Φ
LC is not 90 degrees because the direction in which the liquid crystal molecules move with respect to the electric field is defined in one direction. That is, in FIG.
This is for setting so that the liquid crystal molecules 106 always move from the common electrode 102 to the pixel electrode 103 with respect to the electric field direction 113. If ΦLC = 90 degrees, liquid crystal molecule 1
This is because 06 moves in either direction counterclockwise or clockwise (clockwise) in the figure, resulting in a domain and display failure.

Next, as shown in FIGS. 1B and 1D,
When an electric field 113 is applied to the electrodes 102 and 103, the liquid crystal molecules 106 change their directions clockwise. At this time, the optical properties of the present liquid crystal element change due to the refractive index anisotropy of the liquid crystal composition layer and the action of the polarizing plates 109, 109 ', and display is performed by the change.

The liquid crystal display of the present invention is a horizontal electric field type liquid crystal display having a pair of polarizing plates, wherein the polarizing axes of the pair of polarizing plates are substantially orthogonal to each other, and The orientation control directions of the liquid crystal molecules at the two interfaces with the pair of substrates are substantially parallel, and the polarization axis of one polarizing plate and the orientation control direction of the liquid crystal molecules substantially match.
FIG. 3 shows the arrangement. With this arrangement, a so-called normally-closed display device in which black display is performed at low voltage and white display is performed at high voltage, that is, the luminance increases with an increase in voltage, is obtained. With this arrangement, it is possible to obtain a liquid crystal display device with lower black display luminance and higher contrast. On the other hand, the polarization axes of a pair of polarizing plates,
When the alignment control directions of the liquid crystal molecules are all parallel, display is possible, but black luminance is high and contrast is low.

Although the liquid crystal 106 shown in FIG. 1 has a positive dielectric anisotropy, the liquid crystal 106 may have a negative dielectric anisotropy. In this case, the initial alignment state is set to 0 degree ≦ | ΦLC | <45 from the vertical direction of the stripe electrode.
It is good to be oriented at a time.

FIG. 4 is a diagram showing a planar structure of various electrodes in a unit pixel and a cross section thereof in the liquid crystal display device according to the first embodiment of the present invention. The glass substrate 401, the common electrode 402, the scanning signal electrode 414, the insulating film 404 on these electrodes, the video signal electrode 410, the pixel electrode 403, and the thin film transistor 415 (TFT: Thin F) as an active element composed of amorphous silicon 416.
ilm Transistor) and an insulating layer 404 thereover. In addition, a thin film diode can be used as the active element, but it is preferable to use a TFT having better operation characteristics as a switching element.

Further, when the common electrode or the pixel electrode is made of a transparent material, as shown in FIGS. FIG.
Here, (a) and (b) are side sectional views, and (c) and (d) are plan views. 1 and 2, the liquid crystal molecules 506 change their directions by an electric field, and display is performed by changing optical characteristics. Figures 6 and 7
FIG. 3 is a diagram showing a planar structure of various electrodes and a cross section thereof in a unit pixel of a liquid crystal display device according to the second and third embodiments of the present invention. The difference from the configuration shown in FIG. 3 is that the common electrode and the pixel electrode are transparent electrodes that transmit visible light, for example, indium-tin-oxide (ITO).

In the liquid crystal display device of the present invention, a component having dielectric anisotropy Δε ≦ 1 is contained in the liquid crystal layer to be used in an amount of 40% by weight or more and less than 100% by weight. This is to reduce the viscosity of the liquid crystal layer by adding a large amount of neutral components,
This is to achieve a high-speed response which is one of the objects of the present invention. The neutral component can essentially lower the viscosity of the liquid crystal layer. This is because the component of Δε ≦ 1 has a small dipole moment and therefore a small intermolecular force. For example, 4-methyl- (4-cyanophenyl) cyclohexane and 4-methyl- (4-cyano-3,5-di), which are compounds having large dielectric anisotropy, calculated by molecular orbital calculation MOPAC93 (AM1). The dipole moments of fluorine (phenyl) cyclohexane are 3.93 Debye and 5.43 Debye, respectively, whereas the dipole moments of bis (4-methylcyclohexane) and bis (4-methylbenzene) satisfying Δε ≦ 1 Are very small, 0.035 debyes and 0.027 debyes, respectively. That is, from the calculation results, it can be explained that a compound having Δε ≦ 1 has a small dipole moment, and therefore has a small intermolecular interaction, and thus can be reduced in viscosity.

Next, the response time will be described. In the liquid crystal display device of the present invention, by controlling the alignment state of the liquid crystal by the voltage, the luminance is adjusted and various displays are performed. The response time refers to a time required to reach a desired luminance when switching from one voltage to the next voltage. Since the display is rewritten every frame period, at least one
Unless the response of the liquid crystal is completed within the frame period, the desired brightness is not reached. In particular, when a moving image is displayed, the image is blurred due to the response delay of the liquid crystal.
Here, one frame period means that the scanning frequency of the scanning circuit is 6
In the case of 0 Hz, 1/60 second = about 17 ms. FIG. 8 shows the relationship between the content of the neutral component and the response time in the liquid crystal display device of the present invention obtained as a result of the experiment. In the liquid crystal display device of the present invention, when the content of the neutral component is 40% by weight or more and the frame frequency is 60 Hz,
It was found that the response time was about 17 ms or less for the frame time. Therefore, in the liquid crystal display device of the present invention, the content of the neutral component is set to 40% by weight or more. However, when the neutral component is 100%, Δε = 0, and the liquid crystal cannot be driven by the electric field. Therefore, in order to drive the liquid crystal, the content of the neutral component needs to be less than 100%, and the content of the neutral component is preferably 90% by weight or less in practical use.

Further, in the liquid crystal display device of the present invention, the response time depends on not only the viscosity of the liquid crystal but also the cell gap, that is, Δn of the liquid crystal, as shown in Expressions 1 and 3. FIG. 9 shows the relationship between the response time between the voltages giving the minimum luminance and the maximum luminance and γ1 / Δn ² in the liquid crystal display device of the present invention. From this figure, it was found that γ1 / Δn ² ≦ 1.2 × 10 ⁴ mPa · s is sufficient to achieve a response time of 17 ms or less. At this time, the temperature at the time of measuring γ1 and Δn is 25 ° C. Further, on the liquid crystal screen, not only the display of the lowest luminance and the highest luminance but also a large number of halftone images are displayed therebetween. Therefore, the halftone response time is also important. In the horizontal electric field method used in the liquid crystal display of the present invention, the response time between halftones is about twice as long as the response time between minimum and maximum luminance. Therefore, in order to make the response time between the halftones 17 ms or less, the response time between the minimum and the maximum brightness may be 8 ms, in which case γ1 / Δn ² ≦
It turned out that it is sufficient if it is 6.0 × 10 ³ mPa · s.

Next, the content of the neutral component and γ1 /
The correlation of Δn ² was studied. FIG. 10 shows the result. It was found that γ1 / Δn ² ≦ 1.2 × 10 ⁴ mPa · s can be achieved by setting the neutral component of the liquid crystal layer to 40% by weight or more.

In the liquid crystal display device of the present invention, the refractive index anisotropy Δn of the liquid crystal layer and the parameter d · Δ
n is set as 0.2 μm <d · Δn <0.4 μm. In a birefringence mode display method such as a horizontal electric field method, the transmitted light intensity observed with a liquid crystal interposed between polarizing plates whose polarization axes are orthogonal to each other is proportional to sin (πd (Δn / λ). Here, λ is the wavelength of light. In order to maximize the transmitted light intensity, d · Δn should be λ / 2, 3λ / 2, 5λ /
However, in order to obtain white transmitted light while suppressing the wavelength dependence of the transmitted light, λ / 2 is desirably set. That is, considering light of 550 nm having high visibility, d ·
Δn = 0.275 μm. This d · Δn may be practically at least in the range of 0.2 μm to 0.4 μm.

The liquid crystal display device of the present invention is a liquid crystal display device of a horizontal electric field type having a spacer sandwiched between a pair of substrates, wherein the spacer sandwiched between the pair of substrates is:
It is characterized by being in a non-display area. Hereinafter, this operation will be described.

As described above, when the content of the component satisfying Δε ≦ 1 in the liquid crystal layer is increased, the viscosity of the liquid crystal layer is reduced, and high-speed response is possible. However, it was found that the contrast decreased with an increase in the neutral component content. As a result of a detailed study, it has been found that the amount of light leakage around the spacer during black display increases with an increase in the content of the constituent components of Δε ≦ 1. In the in-plane switching mode liquid crystal display device of the present invention, as described above, the alignment control direction of the polarizing plate and the liquid crystal is arranged so that black display is performed at a low voltage, that is, so-called normally closed. When a spacer is present in the liquid crystal layer, the alignment direction of the liquid crystal is not uniform at the spacer-liquid crystal interface, and is different from the alignment control direction of the liquid crystal molecules at the liquid crystal-substrate interface. In addition, light leaks from the periphery of the spacer, and the luminance of black display increases, that is, the contrast decreases.
This decrease in contrast due to light leakage from around the spacer is particularly remarkable in a normally closed liquid crystal display device. In the present invention, when the content of the neutral component was set to 40% by weight or more, the contrast was significantly reduced. As a result of a detailed study, it was found that the remarkable decrease in contrast was caused by a remarkable increase in light leakage from the periphery of the spacer. Therefore, in order to clarify the cause of light leakage from around the spacer, FIG.
The measurement cell shown in FIG. This measuring cell is provided between the liquid crystal layer 11 and the glass substrate with the spacer 1104 interposed therebetween.
05. A polyimide alignment film 1108 is formed on the glass substrate 1101, and the rubbing directions thereof are antiparallel to each other. (1) Neutral components: PCH302 (1- (4-ethoxyphenyl) -4-propylcyclohexane) and P
Equivalent mixture of CH304 (1- (4-butoxyphenyl) -4-propylcyclohexane) (Δε = about 0) (2) Large component of Δε: ZLI-1083 manufactured by Merck & Co.
(Δε = about 10 in a ternary mixture of cyanoPCH (note that
PCH means phenylcyclohexane)) A mixed liquid crystal having a different composition ratio is injected, and under the crossed Nicols of the polarizing plate, the rubbing direction of the cell and the polarizing axis of one of the polarizing plates are made to coincide with each other. The orientation of the liquid crystal in the periphery was observed. The reason why the equivalent mixture of PCH302 and PCH304 in the above (1) is used is that, as described above, it is effective to use at least 40% by weight or more of the liquid crystal of Δε ≦ 1 in a liquid crystal display device of an in-plane switching mode. That is, the liquid crystal of (1) was used as an example of the liquid crystal of Δε ≦ 1.

As a result, 50% by weight of the liquid crystal of (1)
In the case of the mixed liquid crystal of 50% by weight of the liquid crystal of (2), FIG.
As shown in (a), a bright portion 1201 was observed annularly around the spacer 1204, and the outside of the bright portion 1201 was a dark portion. In the bright part 1201, dark part lines 1202 and 1203 were observed crosswise in the direction coinciding with the polarization axis of the polarizing plate. When observed in detail using a polarizing microscope,
As shown in FIG. 13A, it was presumed that the liquid crystal molecules 1301 were oriented around the spacer 1302. FIG.
12A shows only one molecule around the spacer 1302, but in reality, a plurality of molecules substantially corresponding to the length in the radial direction of the bright portion 1201 in FIG. ing. In the dark part outside the bright part 1201, the liquid crystal molecules are aligned parallel to the rubbing direction. For this reason, outside the bright portion 1201, the light cannot pass through the orthogonally polarizing plates, and is therefore a dark portion. As shown in FIG. 13A, only the portion where the liquid crystal molecules 1301 around the spacer 1302 are aligned is the portion where the alignment direction of the liquid crystal molecules 1301 and the polarization axis of the polarizing plate coincide with each other. ) Are observed as dark lines 1202 and 1203. Liquid crystal molecule 1
In the portion where the orientation direction of 301 is inclined with respect to the polarization axis of the polarizing plate, a polarized light component that passes through the polarizing plate is generated.
It is observed as a bright portion 1201 in (a).

In the case of the mixed liquid crystal of (1) 45% by weight of the liquid crystal and (2) the liquid crystal of 55% by weight, and in the case of (1) the liquid crystal 40%
FIGS. 12 (b) and 12 (c) show the surroundings of the spacer in the case of the mixed liquid crystal of 60% by weight of the liquid crystal of (2). In these cases, 50% by weight of the liquid crystal of (1) and 5% of the liquid crystal of (2)
Unlike the case of 0% by weight of the mixed liquid crystal, the dark portion line 1201 is included in the bright portion 1201 in a direction different from the polarization axis direction of the polarizing plate.
5,1205 has newly appeared. As a result of a detailed study, it was inferred that the liquid crystal molecules 1301 were oriented on the surface of the spacer 1302 as shown in FIGS. 13B and 13C.

Further, these liquid crystals were injected into the liquid crystal display device shown in FIG. 1 and the contrast ratio was measured.
(1) liquid crystal: (2) liquid crystal = 40% by weight: 60% by weight,
(1) liquid crystal: (2) liquid crystal = 45% by weight: 55% by weight,
(1) Liquid crystal: (2) Liquid crystal = 50% by weight: 50% by weight, and the contrast ratio is 200: 1, 160: 1, 10
0: 1. That is, (1) a liquid crystal satisfying Δε ≦ 1 (1) The contrast was lowered as the content of the liquid crystal was increased. In particular, when the neutral component is 50% by weight or more, light leakage is large and contrast is greatly reduced. This is because, when the content of the neutral component is large, the liquid crystal molecules on the spacer surface as described above are in an alignment state as shown in FIG. It can be explained that this is because the light leakage at the point becomes large. That is, there is a trade-off between increasing the content of the liquid crystal component satisfying Δε ≦ 1 to achieve high-speed response and high contrast.

Therefore, in order to avoid the trade-off and achieve both low driving voltage and high contrast, in the present invention, the spacer is arranged outside the display area (pixel area). As a result, even if light leakage increases around the spacer due to an increase in the content of the neutral component in the liquid crystal layer, the black luminance does not increase because there is no spacer in the display area. That is, high contrast can be realized. The non-display area in which the spacer is arranged is a non-light-transmitting area on the electrode substrate, for example, on the common electrode 102, the pixel electrode 103, and the video signal electrode 110 in FIG. On the substrate on which the color filter is formed, a region above the black matrix 1410 (FIG. 14), which is a light shielding portion, is a non-light-transmitting region.
As a method of disposing the spacer in the non-pixel region, a method of selectively disposing a spherical spacer in the non-pixel region, a method of forming a columnar spacer in the non-pixel region, or the like is used. As a method of forming the columnar spacer, the spacer can be more easily formed at a desired place by a photosensitive material and a photolithography process, and the method of forming the columnar spacer is more preferable. FIG. 14 shows an example of a liquid crystal display device using the columnar spacer of the present invention. This liquid crystal display device is an example in which a planarizing film 1407 and a columnar spacer 1412 on a color filter 1405 are simultaneously formed using a photosensitive resin. Thus, in the present invention, the content of the neutral component in the liquid crystal layer is reduced to 40% by weight.
As described above, by arranging the spacers in the non-display area, a high-speed response in which the response time is equal to or less than one frame period, and a high contrast in which a rise in luminance during black display is suppressed are realized.

Further, in the present invention, such a component having Δε ≦ 1 is a compound having two cyclic structures in a molecule, and a compound in which the cyclic structure is a combination of a benzene ring and a cyclohexane ring. . A typical structure of a compound having such a structure is shown in (Formula 8).

[0044]

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(Wherein, R1 and R2 are the same or different and are each an alkyl group, alkenyl group, or alkoxyl group having 12 or less carbon atoms. X is an alkylene group, an alkenylene group, a carbon-carbon triple bond, Either an ether group or an ester group.) Specific examples of the compounds are shown in (Formula 9).

[0046]

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As described above, since the compound having such a structure has a small dipole moment, which is almost zero, the intermolecular interaction is small, and thus the viscosity can be reduced.

Further, the present invention is characterized in that a compound having only one cyclic structure in the molecule and having a single ring structure is used as a component satisfying Δε ≦ 1. The specific compound is shown in (Formula 10).

[0049]

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Compounds having a single ring structure have a lower viscosity than bicyclic compounds, and can achieve a higher response speed. As the monocyclic structure, a structure having only a benzene ring or a cyclohexane ring is more preferable. Further, it is preferable that an alkyl group, an alkenyl group, or an alkoxyl group is bonded to these rings. Such a monocyclic compound is particularly effective in reducing the viscosity, and is advantageous in increasing the response speed. Further, since the ring is a single ring, the refractive index anisotropy Δn can be reduced, and the chromaticity change due to the viewing angle peculiar to the horizontal electric field method can be reduced. This is because the visual chromaticity change in the horizontal electric field method changes the cell gap and Δn of the liquid crystal depending on the angle. Therefore, if Δn is originally small, the change amount is also small, and the chromaticity change due to vision is reduced.

In the liquid crystal display of the present invention, Δ
Containing at least 40% by weight of a component satisfying ε ≦ 1. Therefore, Δε decreases and the driving voltage increases. Therefore, in the present invention, in order to achieve both high-speed response and high contrast and to achieve a low driving voltage, the second object is
Cyano-3-fluorophenyl, 4-cyano-3,5-
A compound having a difluorophenyl structure in the molecule is contained in the liquid crystal layer. Particularly desirable is 4-cyano-3,5.
A compound having a difluorophenyl structure in the molecule. As described above, these compounds have a high polarity and a large dipole moment, but also have a large Δε. For example, a compound having a fluorophenyl or difluorophenyl structure has a very large Δε of about 20 to about 60. It is possible to increase Δε of the entire liquid crystal layer by adding a small amount. Examples of such compounds are shown in (Formula 11).

[0052]

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In the liquid crystal display device of the present invention, when a drive voltage was reduced by using a liquid crystal composition of the above-mentioned high-polarity liquid crystal component and a neutral component, a new problem occurred. It is a problem with the compatibility of liquid crystals. In the combination of the high-polarity liquid crystal component and the neutral component,
The compatibility, that is, the stability of the liquid crystal phase was remarkably reduced, and there was a problem that crystals were precipitated, especially at low temperatures.

The problem of compatibility in such a liquid crystal formulation is described in ID W. '97 Prosedings, pp. 41-44 (Y. Tanaka and S. Naemura ID).
W'97 Proceedings p.41-44)
It is considered as a problem of dissolving the ideal solution, and suppression of deposition of the liquid crystal component at a low temperature has been studied. However, as a result of similar attempts, handling ideal solutions
It turned out that the actual low temperature stability could not be reproduced. In particular, in the case of a combination of a neutral component and a highly polar component as in the present invention, the above-mentioned handling could not solve the compatibility problem. Therefore, in the present invention, the solubility parameter of the liquid crystal component is introduced in order to sufficiently consider the intermolecular interaction of the liquid crystal component and solve the compatibility problem. Specifically, Polymer Engineering Science, 1974, No. 1
4, 147 (RFFedors, Polym. Eng. Sci., 1974,
Vol. 14, 147), a method for calculating a solubility parameter was used. As a result, the low-temperature stability predicted by calculation and the low-temperature stability of the actual liquid crystal composition were in good agreement, and more useful findings could be obtained.

That is, the influence of intermolecular interaction on the compatibility of the liquid crystal can be estimated by using the solubility parameter. Therefore, the low-temperature stability of the liquid crystal composition is improved by considering the solubility parameter of the liquid crystal component. I was able to get the guideline.

Therefore, a medium-polarity liquid crystal between a low-polarity neutral component and a high-polarity component having a 4-cyano-3-fluorophenyl or 4-cyano-3,5-difluorophenyl structure in the molecule. It has been found that the low-temperature stability can be significantly improved by adding the components.

Specifically, the solubility parameter of Compound A, which is a neutral component (Formula 9), was determined to be about 8.3. In addition, the solubility parameter of Compound B of Chemical Formula 10, which is a highly polar component, was determined to be about 11.8. Therefore, during that time, a compound having a solubility parameter of 8.4 to 11.7 may be added. In addition, other neutral components
The solubility parameter is generally 9.2 or less, and the high polarity component used in the present invention has a solubility parameter of 10.8 or more. Therefore, as a medium polarity component, a component having a solubility parameter of 9.3 to 10.7 is used. Is preferred. As a result, it becomes possible to contain more highly polar components.

It is more desirable for the medium polarity component to satisfy Δε> 0. As a result, the liquid crystal composition has a larger Δε, and a lower driving voltage is possible. Specifically, compounds having a monofluorine benzene, difluorene benzene, trifluorobenzene, monofluorine cyclohexyl, difluorine cyclohexyl, trifluorine cyclohexyl, cyanobenzene, or cyanocyclohexyl structure in the molecule can be used.

Neutral component in the liquid crystal layer is 40% by weight.
Not less than 100% by weight, substantially 40% by weight to 90%
Therefore, by containing the medium-polarity component and the high-polarity component in a range of 60% by weight or less, substantially 10% by weight or more and 60% by weight or less, a low driving voltage and
It has become possible to significantly improve low-temperature stability.

In the present invention, furthermore, the electrode is made of an opaque material,
For example, when chromium or the like is used, the distance L between the pixel electrode and the common electrode and the refractive index anisotropy Δn and the dielectric anisotropy Δε of the liquid crystal layer are set such that LΔn / √Δε ≦ 0.55 μm. Then, LΔn / √Δε ≦ 0.4 μm is set. As can be seen from Equations 2 and 4, in the lateral electric field method, the drive voltage depends on the distance L between the pixel electrode and the common electrode, and Δn and Δε. Therefore, the driving voltage decreases as L decreases, but when an opaque material is used for the electrodes, the aperture ratio, that is, the luminance decreases at the same time. Therefore, it is necessary to increase L to some extent. Actually L is
It is about 20 μm to 5 μm. As a result of the experiment, in order to obtain a drive voltage that can be driven by the current drive driver, LΔn
/√Δε≦0.55 μm. It is more preferable that LΔn / √Δε ≦ 0.4 μm.

Further, in the present invention, the refractive index anisotropy Δn and the dielectric anisotropy Δε of the liquid crystal layer satisfy Δn / √Δε ≦ 5.
5 × 10 ^-2 , and Δn / √Δε ≦ 2.7 ×
Set to 10 ^-2 . Hereinafter, the operation will be described.

On the other hand, when a transparent material such as indium-tin-oxide is used for the electrode, even if L is reduced, the luminance hardly decreases and the driving voltage can be reduced. However, as a result of the experiment, it was found that the driving voltage cannot be set to 0 even when L = 0, that is, even when the pixel electrode and the common electrode are vertically stacked as shown in FIGS. Therefore, when L is small, it is necessary to review Equations 2 and 4. When confirmed experimentally, L
In the case of = 0, it was found that if Δn / √Δε ≦ 5.5 × 10 ⁻² , the voltage would be in a range that can be driven by the current driving driver.

Further, by setting Δε ≧ 7 and the twist elastic constant K22 ≦ 5.5 pN of the liquid crystal layer, the driving voltage can be reduced.

Hereinafter, embodiments of the present invention will be described specifically. Embodiment 1 First, a method for manufacturing an active matrix liquid crystal display device according to a first embodiment of the present invention will be described with reference to FIGS. Common electrode 40 on glass substrate 401
2 and the scanning signal electrode 414 are formed. An insulating film 404 is formed on these electrodes, and a video signal electrode 410, a pixel electrode 403, and a TFT 415 made of amorphous silicon 416 are formed thereon. In the first embodiment, the common electrode 402 and the pixel electrode 403 use chromium, which is an opaque material in the visible light region. The distance between the common electrode 402 and the pixel electrode 403 is 13 μm.
Further, an insulating layer 404 is formed thereover. Further, the pixel is divided into four by a common electrode 402 and a pixel electrode 403 which are parallel to the video signal electrode 410. Optmer AL3046 manufactured by JSR Corporation is placed on a substrate having this electrode group.
Is used to form an alignment film 408. After forming the alignment film, the film surface is subjected to an alignment treatment by a rubbing method.

Next, referring to FIG. 14, a color filter 1405 and a black matrix 141 are provided on a substrate 1401 ′ opposite to the substrate 1401 having the TFT 415.
Form one. A flattening film 1407 is formed over the color filter 1405. At this time, a photosensitive resin is used for the flattening film 1407, and a columnar spacer 1412 is formed on the black matrix 1411 simultaneously with the formation of the flattening film 1407 by a photolithography method. An alignment film 1408 was formed in the same manner as the substrate 1401, and a rubbing treatment was performed. The substrates 1401 and 1401 'were opposed to each other so that the rubbing directions were the same, and were bonded together with a sealant (not shown). The gap d between the substrates in this embodiment was about 3.1 μm. After injecting the liquid crystal between the substrates, the polarizing plates 1409, 140
9 'is attached to produce the liquid crystal element shown in FIG. The polarizing plate 1409 has its polarized light transmission axis substantially coincident with the rubbing direction, and the polarized light transmission axis of the other polarizing plate 1409 'substantially perpendicular to it. FIG. 3 shows the relationship. Thus, a so-called normally closed characteristic in which the transmittance increases with an increase in the voltage applied to the liquid crystal layer can be obtained.

Next, as shown in FIG. 15, a driving LSI is connected, a vertical scanning circuit 1501, a video signal driving circuit 1502, and a common electrode driving circuit 1503 are connected on a TFT substrate. A voltage, a video signal voltage, and a timing signal were supplied to manufacture an active matrix liquid crystal display device. In the figure, 150
5 is a common electrode wiring, 1506 is a video signal electrode wiring, 15
Reference numeral 07 denotes a scanning signal electrode wiring. The scanning frequency of the liquid crystal display device of this embodiment is 60 Hz.

FIG. 16 shows a liquid crystal display module 1 according to the present invention.
FIG. 601 is an exploded perspective view showing each component of the reference numeral 601. 1602
Is a frame-shaped shield case (metal frame) made of a metal plate, 1603 is a display window thereof, 1606 is a liquid crystal display panel, 1605 is a power supply circuit board, 1607 is a light diffusion plate,
608 is a light guide, 1609 is a reflection plate, 1610 is a backlight fluorescent tube, 1611 is a backlight case,
The modules 1601 are assembled by stacking the respective members in a vertical arrangement as shown in the drawing. An inverter circuit board 1612 is connected to the backlight fluorescent tube 1610, and serves as a power supply for the backlight fluorescent tube 1610. In the figure, reference numeral 1613 denotes a vertical scanning circuit (1 in FIG. 15).
501) and 1604 are video signal drive circuits (1 in FIG. 15).
502). The liquid crystal display panel 1606 of this embodiment includes:
It has a resolution of XGA (1024 × 768 × 3 dots) at a diagonal of 15.0 inches.

Next, as a comparative example, a liquid crystal display panel in which a spherical spacer instead of a columnar spacer was dispersed between substrates was manufactured. FIG. 17 shows a sectional view of the liquid crystal display panel. The method of manufacturing the substrate was the same as that of the liquid crystal display panel described above, but no columnar spacer was formed when the flattening film 1707 was manufactured. When bonding the substrates, spherical spacers 1711 were dispersed on the substrate. Other methods of manufacturing the device are the same as those of the above-described liquid crystal display device.

The liquid crystal material used in the present embodiment is a liquid crystal material satisfying Δε ≦ 1 of 15% by weight of a liquid crystal compound having a phenylcyclohexane skeleton and 25% by weight of a liquid crystal compound having a bicyclohexyl skeleton, for a total of 40% by weight, and a cyanophenyl group. 15% by weight of a liquid crystal compound having a 4-cyano-3,5-difluorophenyl group and 45% by weight of a liquid crystal compound having a 3,4,5-trifluorophenyl group (I) ). When the physical properties of the liquid crystal composition were measured (25 ° C.), γ1 = 88 mPa · s, Δn = 0.
094, Δε = 8.5, K22 = 5.5 pN. Therefore, in the liquid crystal display device of this embodiment, γ1 / Δn ² = 1.0.
× 10 ⁴ mPa · s, d · Δn is 0.291. LΔn / √Δε = 0.42 <0.55.

When this liquid crystal composition (I) was applied to the above-mentioned liquid crystal display device, the liquid crystal response time when switching from the voltage giving the minimum luminance to the voltage giving the maximum luminance was 1
It was 4 ms. Therefore, one frame period in this embodiment, that is, 1/60 = 16.7 ms or less.

The contrast ratio between the liquid crystal display device using the columnar spacer shown in FIG. 14 and the liquid crystal display device using the spherical spacer shown in FIG. 17 is 350: 1 and 20, respectively.
0: 1. When the liquid crystal alignment around the spacer of the liquid crystal display device using the spherical spacer was observed with a microscope, the alignment was almost the same as that in FIG.

Further, it was possible to apply a voltage sufficient to give the maximum luminance to the liquid crystal by the driving IC. Example 2 In a liquid crystal display device manufactured in the same manner as in Example 1, a total of 16% by weight of a liquid crystal compound having a phenylcyclohexane skeleton and 29% by weight of a liquid crystal compound having a bicyclohexyl skeleton as a liquid crystal material satisfying Δε ≦ 1. 45% by weight, 4-
Liquid crystal compound having cyano-3-fluorophenyl group and 4
A liquid crystal composition (II) containing 20% by weight of a liquid crystal compound having a -cyano-3,5-difluorophenyl group and 35% by weight of a liquid crystal compound having a 3,4,5-trifluorophenyl group;
Was injected. The physical property value of this liquid crystal composition was γ1 = 75 m
Pa · s, Δn = 0.096, Δε = 9.0. Therefore, in the liquid crystal display device of this embodiment, γ1 / Δn ² = 8.1.
4 × 10 ³ mPa · s, d · Δn is 0.298. LΔn / √Δε = 0.42 <0.55.

Further, in the liquid crystal display device of the present embodiment, the liquid crystal response time when switching from the voltage giving the lowest luminance to the voltage giving the maximum luminance was 13 ms.
Therefore, one frame period, that is, 1/60 = 16.7 m
s or less.

The contrast ratios of the liquid crystal display device using the columnar spacer and the liquid crystal display device using the spherical spacer were 340: 1 and 190: 1, respectively. When the liquid crystal alignment around the spacer of the liquid crystal display device using the spherical spacer was observed with a microscope, the alignment was almost the same as that in FIG. 12B.

Further, it was possible to apply a voltage sufficient to give the maximum luminance to the liquid crystal by the driving IC. Example 3 In a liquid crystal display device manufactured in the same manner as in Example 1, 10% by weight of a liquid crystal compound having a phenylcyclohexane skeleton, 30% by weight of a liquid crystal compound having a bicyclohexyl skeleton, and A liquid crystal compound having a bicyclohexane skeleton of 10% by weight for a total of 50% by weight;
25% by weight of a liquid crystal compound having a 4-cyano-3-fluorophenyl group and a liquid crystal compound having a 4-cyano-3,5-difluorophenyl group, and a liquid crystal compound having a 3,4,5-trifluorophenyl group. 25% by weight of the liquid crystal composition (I
II) was injected. The physical property value of this liquid crystal composition was γ1 =
70 mPa · s, Δn = 0.096, and Δε = 9.0. Therefore, in the liquid crystal display device of this embodiment, γ1 / Δn ²
= 7.6 × 10 ³ mPa · s, d · Δn is 0.298. LΔn / √Δε = 0.42 <0.55.

Further, in the liquid crystal display device of this embodiment, the liquid crystal response time when switching from the voltage giving the lowest luminance to the voltage giving the maximum luminance was 12 ms.
Therefore, one frame period, that is, 1/60 = 16.7 m
s or less.

The contrast ratios of the liquid crystal display device using the columnar spacer and the liquid crystal display device using the spherical spacer were 340: 1 and 150: 1. When the liquid crystal alignment around the spacer of the liquid crystal display device using the spherical spacer was observed with a microscope, the alignment was almost the same as that in FIG.

Further, it was possible to apply a voltage sufficient to give the maximum luminance to the liquid crystal by the driving IC. Example 4 A liquid crystal display device manufactured in the same manner as in Example 1 was charged with 20% by weight of a liquid crystal compound having a phenylcyclohexane skeleton and 10% by weight of a liquid crystal compound having a bicyclohexyl skeleton as a liquid crystal material of Δε ≦ 1, and A liquid crystal compound having a cyclohexane skeleton of 10% by weight, a dialkenyloxybenzene derivative of 10% by weight, a total of 50% by weight, a liquid crystal compound having a 4-cyano-3-fluorophenyl group,
25% by weight of a liquid crystal compound having a cyano-3,5-difluorophenyl group and 25% by weight of a liquid crystal compound having a 3,4,5-trifluorophenyl group were injected with the liquid crystal composition (IV). The physical property value of this liquid crystal composition was γ1 = 65 mP
a · s, Δn = 0.093, Δε = 8.5. Therefore, in the liquid crystal display device of this embodiment, γ1 / Δn ² = 7.5 ×
10 ³ mPa · s, d · Δn is 0.288. Also,
LΔn / √Δε = 0.41 <0.55.

Further, in the liquid crystal display device of this embodiment, the liquid crystal response time when switching from the voltage giving the lowest luminance to the voltage giving the highest luminance was 11 ms.
Therefore, one frame period, that is, 1/60 = 16.7 m
s or less.

The contrast ratio between the liquid crystal display device using the columnar spacer and the liquid crystal display device using the spherical spacer was 350: 1 and 150: 1. When the liquid crystal alignment around the spacer of the liquid crystal display device using the spherical spacer was observed with a microscope, the alignment was almost the same as that in FIG.

Further, it was possible to apply a voltage sufficient to give the maximum luminance to the liquid crystal by the driving IC. Example 5 A liquid crystal display device manufactured in the same manner as in Example 1 was provided with a phenylcyclohexane skeleton liquid crystal compound of 30% by weight and a bicyclohexyl skeleton liquid crystal compound of 20% by weight as a liquid crystal material of Δε ≦ 1. 20% by weight of a liquid crystal compound having a cyclohexane skeleton, 10% by weight of a dialkenyloxybenzene derivative, a total of 80% by weight, a liquid crystal compound having a 4-cyano-3,5-difluorophenyl group at 10% by weight, A 10% by weight liquid crystal composition (V) was injected with a liquid crystal compound having a 5-trifluorophenyl group. The physical property value of this liquid crystal composition was γ1 = 55 mPa ·
s, Δn = 0.096, Δε = 5.5. Therefore, in the liquid crystal display device of the present embodiment, γ1 / Δn ² = 6.0 × 10
³ mPa · s, d · Δn is 0.298. Also, LΔ
n / √Δε = 0.53 <0.55.

Further, in the liquid crystal display device of this embodiment, the liquid crystal response time when switching from the voltage giving the lowest luminance to the voltage giving the maximum luminance was 7 ms. Therefore, one frame period, that is, 1/60 = 16.7 ms
It was below. Furthermore, when the response time between halftones was measured, the response time was 16 ms even in the case of the slowest halftone response, which was less than one frame period.

The contrast ratio between the liquid crystal display device using the columnar spacer and the liquid crystal display device using the spherical spacer was 350: 1 and 140: 1. When the liquid crystal alignment around the spacer of the liquid crystal display device using the spherical spacer was observed with a microscope, the alignment was almost the same as that in FIG. Embodiment 6 Next, an active matrix type liquid crystal display device according to a second embodiment of the present invention will be described with reference to FIG. A major difference from the liquid crystal display device described in the first embodiment is that the material of the pixel electrode 703 and the common electrode 702 is a transparent conductive ITO.

A common electrode 702 and a scanning signal electrode 714 are formed on a glass substrate 701. Further, an insulating film 704 is formed on these electrodes, and a video signal electrode 710, a source electrode 717, an amorphous silicon
A TFT 715 made of 16 is formed. Further insulating layer 7
The pixel electrode 703 is formed on the layer 04 '. The source electrode and the pixel electrode 703 are electrically connected. On a substrate having this electrode group, Optmer AL3 manufactured by JSR Corporation
046, an alignment film 708 is formed. After forming the alignment film, the film surface is subjected to an alignment treatment by a rubbing method. Other manufacturing methods of the liquid crystal display device were the same as those in Example 1, and a liquid crystal display device using a columnar spacer and a liquid crystal display device using a spherical spacer as a comparative example were manufactured. The order of layers of each electrode in the direction perpendicular to the substrate surface is not limited to the order of layers in this embodiment.

The liquid crystal composition (V) described in Example 5 was injected into the manufactured liquid crystal display device. In this case, Δn / √Δ
ε = 4.2 × 10 ⁻² ≦ 5.5 × 10 ⁻²

In the liquid crystal display device of this embodiment, the liquid crystal response time when switching from the voltage giving the lowest luminance to the voltage giving the maximum luminance was 7 ms. Therefore, one frame period, that is, 1/60 = 16.7 ms or less. Further, when the response time between halftones was measured, it was 15 ms even in the case of the slowest halftone response, which was less than one frame period.

The contrast ratio between the liquid crystal display device using the columnar spacer and the liquid crystal display device using the spherical spacer was 350: 1 and 140: 1. Further, when the liquid crystal alignment around the spacer of the liquid crystal display device using the spherical spacer was observed with a microscope, the alignment was almost the same as that in FIG.

Further, it was possible to apply a voltage sufficient to give the maximum luminance to the liquid crystal by the driving IC. Example 7 A liquid crystal display device manufactured in the same manner as in Example 6 was provided with 25% by weight of a liquid crystal compound having a phenylcyclohexane skeleton and 20% by weight of a liquid crystal compound having a bicyclohexyl skeleton as a liquid crystal material of Δε ≦ 1, and Liquid crystal compound having a total of 85% by weight of 20% by weight of a liquid crystal compound having a cyclohexane skeleton, 10% by weight of a dialkenylcyclohexane derivative, and 10% by weight of a dialkenyloxybenzene derivative, and having a 4-cyano-3,5-difluorophenyl group. 1
A liquid crystal compound (VI) having a weight of 0% by weight and a liquid crystal compound having a 3,4,5-trifluorophenyl group was injected by 5% by weight.
The physical property value of this liquid crystal composition is γ1 = 45 mPa · s, Δ
n = 0.094 and Δε = 4.5. Therefore, in the liquid crystal display device of the present embodiment, γ1 / Δn ² = 5.1 × 10 ³ mP
a · s and d · Δn are 0.291. Also, Δn / √
Δε = 4.4 × 10 ⁻² ≦ 5.5 × 10 ⁻²

Further, in the liquid crystal display of this embodiment, the liquid crystal response time when switching from the voltage giving the lowest luminance to the voltage giving the maximum luminance was 5 ms. Therefore, one frame period, that is, 1/60 = 16.7 ms
It was below. Further, when the response time between halftones was measured, it was 11 ms even in the case of the slowest halftone response, which was less than one frame period.

The contrast ratios of the liquid crystal display device using the columnar spacer and the liquid crystal display device using the spherical spacer were 350: 1 and 135: 1. When the liquid crystal alignment around the spacer of the liquid crystal display device using the spherical spacer was observed with a microscope, the alignment was almost the same as that in FIG.

Further, it was possible to apply a voltage sufficient to give the maximum luminance to the liquid crystal by the driving IC.

According to the present invention, in a normally closed lateral electric field type liquid crystal display device, the component of dielectric anisotropy Δε ≦ 1 in the liquid crystal composition is adjusted to 4 by adjusting the liquid crystal composition.
By setting the weight to 0% by weight or more and less than 100% by weight, high-speed response with a response time of one frame period or less can be achieved. Further, by adjusting the liquid crystal composition, the rotational viscosity coefficient γ1 and the refractive index anisotropy Δn of the liquid crystal layer are set to 1 × 10 ³ mPa · s ≦ γ1 /
Even when Δn ² ≦ 1.2 × 10 ⁴ mPa · s, high-speed response with a response time of one frame period or less can be achieved.
Further, by arranging the spacer in the non-display area, high contrast can be achieved.

[0093]

As described above, it is possible to provide a liquid crystal display device capable of high-speed response and high contrast.

[Brief description of the drawings]

FIG. 1 is a schematic view showing the principle of operation of a liquid crystal in a liquid crystal display device of an in-plane switching mode according to the present invention.

FIG. 2 is a diagram showing angles formed by a liquid crystal molecule long axis alignment direction with respect to an electric field direction and a polarizing plate polarization transmission axis in the liquid crystal display device of the present invention.

FIG. 3 is a diagram showing the relationship between the alignment direction of liquid crystal molecules and the polarization transmission axis of a polarizing plate in the liquid crystal display device of the present invention.

FIG. 4 is a schematic diagram showing a plane and a cross section showing the arrangement of an electrode group, an insulating film, and an alignment film in a unit pixel portion of the liquid crystal display device of the present invention.

FIG. 5 is a schematic view showing the principle of operation of liquid crystal in the liquid crystal display device of the in-plane switching mode according to the present invention.

FIG. 6 is a schematic diagram showing a plane and a cross section showing an arrangement of an electrode group, an insulating film, and an alignment film in a unit pixel portion of the liquid crystal display device of the present invention.

FIG. 7 is a schematic view showing a plane and a cross section showing the arrangement of an electrode group, an insulating film, and an alignment film in a unit pixel portion of the liquid crystal display device of the present invention.

FIG. 8 shows a liquid crystal display device of an in-plane switching mode according to the present invention.
FIG. 4 is a graph showing a relationship between a content of a neutral component in a liquid crystal layer and a response time.

FIG. 9 shows a horizontal electric field type liquid crystal display device of the present invention.
FIG. 4 is a diagram illustrating a relationship between γ1 / Δn ² of a liquid crystal material and response time.

FIG. 10 shows γ1 / γ of the liquid crystal material used in the example of the present invention.
Diagram showing the relationship between the content of [Delta] n ² and neutral components.

FIG. 11 is a schematic cross-sectional view of a measurement cell for observing a liquid crystal alignment state around a spacer.

FIG. 12 shows Δε ≦ in a liquid crystal layer of the liquid crystal display device of the present invention.
FIG. 2 is a schematic diagram showing the amount of constituent components and light leakage around a spacer.

FIG. 13 is a schematic diagram illustrating an estimated alignment state of liquid crystal molecules around a spacer.

FIG. 14 is a schematic cross-sectional view of a pixel portion of a liquid crystal display device using a columnar spacer in an example of the present invention.

FIG. 15 illustrates an example of a circuit system configuration in the liquid crystal display device according to the first embodiment.

FIG. 16 is an exploded perspective view showing each component of the liquid crystal display device according to the first embodiment.

FIG. 17 is a schematic cross-sectional view of a pixel portion of a liquid crystal display device using a spherical spacer in an example of the present invention.

[Explanation of symbols]

101, 101 ', 401, 501, 501', 60
1,701,1101,1401,1701,170
1 ': substrate, 102, 402, 502, 602, 70
2, 1402, 1702 ... common electrode, 103, 403,
503, 603, 703, 1403 ... pixel electrode, 40
4,604,704,704 ', 1404,1704 ...
Insulating layer, 1405 ... Color filter, 106, 506
1406, 1706 ... liquid crystal molecules, 1407, 1707 ...
Flattening film, 108, 108 ', 408, 508, 60
8,708,1103,1408,1708 ... Alignment film,
109, 109 ', 509, 509', 1102, 14
09, 1709, 1709 ': polarizing plate, 110, 41
0, 510, 610, 710, 1410, 1710 ... video signal electrodes, 111, 201, 301, 301 '... orientation directions of liquid crystal, 202, 302, 302' ... polarization transmission axis directions of polarizing plates, 113, 203, 513 ... direction of electric field, 41
4,614,714 ... scanning signal electrodes, 415,615,
715: TFT element, 416, 616, 716: amorphous silicon, 717: source electrode, 1501, 16
13 vertical scanning circuit, 1502, 1604 video signal driving circuit, 1503 common electrode driving circuit, 1504 power supply circuit and controller, 1505 common electrode wiring, 15
06: video signal electrode wiring, 1507: scanning signal electrode wiring, 1104, 1204, 1711: spherical spacer, 1
105: liquid crystal layer, 1601: liquid crystal display module, 16
02 ... shield case, 1603 ... display window, 1606 ...
Liquid crystal display panel, 1607: light diffusion plate, 1608: light guide, 1609: reflection plate, 1610: backlight fluorescent tube, 1611: backlight case, 1612: inverter circuit board, 1605: power supply circuit board, 1201: clear part , 1202, 1203, 1205, 1206 ... dark line, 1412 ... columnar spacer, 1411, 1705 ... black matrix.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kotaro Aratani 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd.Hitachi Research Laboratory Co., Ltd. No. 1-1 Inside Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor Katsumi Kondo 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory Hitachi, Ltd.

Claims (27)

[Claims] 1. A pair of substrates having an interval defined by a spacer, a liquid crystal layer filled between the pair of substrates, and one of the pair of substrates for applying an electric field to the liquid crystal layer. What is claimed is: 1. A liquid crystal display device comprising: an electrode group formed on a substrate; and a pair of polarizing plates disposed with the liquid crystal layer interposed therebetween and having polarization axes substantially orthogonal to each other. The layer contains a component having a dielectric anisotropy ΔΔ ≦ 1 of 40% by weight or more and less than 100% by weight. A liquid crystal display device in which the polarization axis of one of the polarizing plates and the alignment control direction of the liquid crystal molecules at the interface substantially coincide with each other. 2. A pair of substrates having an interval defined by a spacer, a liquid crystal layer filled between the pair of substrates, and one of the pair of substrates for applying an electric field to the liquid crystal layer. What is claimed is: 1. A liquid crystal display device comprising: an electrode group formed on a substrate; and a pair of polarizing plates disposed with the liquid crystal layer interposed therebetween and having polarization axes substantially orthogonal to each other, wherein the liquid crystal layer has a rotational viscosity coefficient γ1 and a refractive index difference. The anisotropy Δn is 1 × 10 ³ mPa · s ≦ γ1 / Δn ² ≦ 1.2 × 10 ⁴
Liquid crystal display device that satisfies mPa · s. 3. The liquid crystal display device according to claim 2, wherein the rotational viscosity coefficient γ1 and the refractive index anisotropy Δn of the liquid crystal layer are 1 × 10 ³ mPa · s ≦ γ1 / Δn ² ≦ 6 × 10 ³ m
Liquid crystal display device that satisfies Pa · s. 4. A pair of spacers whose intervals are defined by spacers
A substrate, a liquid crystal layer filled between the pair of substrates,
To apply an electric field to the liquid crystal layer.
An electrode group formed on one substrate and the liquid crystal layer interposed therebetween
A pair of polarizing plates that are arranged and whose polarization axes are almost orthogonal to each other
A liquid crystal display device, comprising: a spacer disposed in a non-display area;
% To less than 100% by weight, and the rotational viscosity of the liquid crystal layer is
Γ1 and refractive index anisotropy Δn are 1 × 10 ^ThreemPa
・ S ≦ γ1 / Δn^Two≦ 1.2 × 10^Foursatisfies mPa · s
At two interfaces between the liquid crystal layer and the pair of substrates.
The orientation control directions of the liquid crystal molecules are almost parallel.
Polarization axis of optical plate and method of controlling alignment of liquid crystal molecules at the interface
A liquid crystal display device whose orientation is almost the same. 5. The liquid crystal display device according to claim 4, wherein the rotational viscosity coefficient γ1 and the refractive index anisotropy Δn of the liquid crystal layer are 1 × 10 ³ mPa · s ≦ γ1 / Δn ² ≦ 6 × 10 ³ m
Liquid crystal display device that satisfies Pa · s. 6. The liquid crystal display device according to claim 1, wherein the electrode group includes a pixel electrode, a common electrode, and an active element. 7. The liquid crystal display device according to claim 6, wherein said active element is a thin film transistor. 8. The liquid crystal display device according to claim 6, wherein at least one of the pixel electrode and the common electrode comprises a transparent electrode. 9. The liquid crystal display device according to claim 1, wherein the liquid crystal layer has a refractive index anisotropy Δn and a thickness d of 0.2 μm.
A liquid crystal display device that satisfies m <d · Δn <0.4 μm. 10. The liquid crystal display device according to claim 1, wherein the spacer is a structure formed on one of the substrates. 11. The liquid crystal display device according to claim 1, wherein at least one of the components having a dielectric anisotropy Δε ≦ 1 contained in the liquid crystal layer has a cyclic structure having a molecular structure. A liquid crystal display device comprising two compounds therein, wherein the cyclic structure is a benzene ring or a cyclohexane ring. 12. The liquid crystal display device according to claim 1, wherein at least one of the components having a dielectric anisotropy Δε ≦ 1 contained in the liquid crystal layer has a cyclic structure having a molecular structure. A liquid crystal display device having only one compound therein and having a cyclic structure of a benzene ring or a cyclohexane ring. 13. The liquid crystal display device according to claim 12, wherein the compound having only one cyclic structure in the molecule contained in the liquid crystal layer has a structure represented by the following chemical formula. Embedded image (In the formula, ring A is 1,4-cyclohexylene or 1,
4-phenylene. B1 and B2 are -COO-,-
OOC-, -OCO-, -CX2-, = CX-, -CX
= Is a group selected from the group consisting of -O-, and X represents hydrogen or a halogen atom. R1 and R2 have 1 to 8 carbon atoms
May be substituted by a halogen atom with an alkyl group of the formula (I), or may contain a double bond in the carbon chain. ) 14. The liquid crystal display device according to claim 13, wherein in the compound having only one cyclic structure in the molecule, ring A is 1,4-cyclohexylene, and B1 and B2 are -CX2- , -CX =, -O-, wherein R1 and R2 are alkyl groups which may be substituted with a halogen atom, and whose carbon number is any of 2,4,6,8. A liquid crystal display device. 15. The liquid crystal display device according to claim 14, wherein R1 and R2 in the 1,4-cyclohexylene derivative are different from each other.
Is an alkyl chain having 4, 6, 8 carbon atoms which may be substituted by a halogen atom, and the n-th carbon and n
A liquid crystal display device having a double bond with + 1st (n = 2, 4, 6) carbon. 16. The liquid crystal display device according to claim 13, wherein in the compound having only one cyclic structure in the molecule, ring A is 1,4-phenylene, and B1 and B2 are -CX.
A group selected from the group consisting of 2-, -O-
2. A liquid crystal display device wherein 2 is an alkyl group which may be substituted by a halogen atom, and which has 2, 4, 6, or 8 carbon atoms. 17. The liquid crystal display device according to claim 16, wherein R1 and R2 in the 1,4-phenylene derivative have a carbon number of 4, which may be substituted with a halogen atom.
6,8 alkyl chains whose nth carbon and n + 1
A liquid crystal display device having a double bond with the (n = 2, 4, 6, 6) th carbon. 18. The liquid crystal display device according to claim 13, wherein in the compound having only one cyclic structure in the molecule contained in the liquid crystal layer, B1 is -OOC- and B2 is -OCO-.
Liquid crystal display device. 19. The liquid crystal display device according to claim 1, wherein a compound having a structure represented by the following chemical formula in a molecule is contained in the liquid crystal layer. Liquid crystal display. Embedded image (Wherein X1 and X2 represent H or F) 20. The liquid crystal display device according to claim 19, wherein the liquid crystal layer has a medium polarity between a low polarity component having a dielectric anisotropy ΔΔ ≦ 1 and a high polarity component represented by the above formula. A liquid crystal display device containing the following components. 21. The liquid crystal display device according to claim 20, wherein the medium-polarity liquid crystal component is a liquid crystal component having a structure selected from the group consisting of the following chemical formulas (3) and (4). Embedded image Embedded image (Wherein X1 and X2 represent H or F. A represents a benzene ring or a cyclohexane ring) 22. The liquid crystal display device according to claim 1, wherein the pixel electrode and the common electrode are made of an opaque material, and the distance between the pixel electrode and the common electrode is determined by the distance between the pixel electrode and the common electrode. The refractive index anisotropy Δn and the dielectric anisotropy Δε of the liquid crystal layer are LΔn /
A liquid crystal display device in which √Δε ≦ 0.55 μm. 23. The liquid crystal display device according to claim 22, wherein a distance L between the pixel electrode and the common electrode and a refractive index anisotropy Δn and a dielectric anisotropy Δε of the liquid crystal layer are LΔn / √. Δε ≦
A liquid crystal display device having a thickness of 0.4 μm. 24. The liquid crystal display device according to claim 8, wherein the liquid crystal layer has a refractive index anisotropy Δn and a dielectric anisotropy Δε of Δn / √Δε ≦ 5.5 × 10 ⁻² . Liquid crystal display. 25. The liquid crystal display device according to claim 6, wherein the liquid crystal layer has a dielectric anisotropy of 7 or more and a twist elastic constant K22 of 5.5 pN or less. 26. The liquid crystal display device according to claim 1, wherein a response time between the lowest luminance gradation and the maximum luminance gradation is one frame period or less. 27. The liquid crystal display device according to claim 1, wherein a response time between halftones is one frame period or less.