KR101268255B1 - Fringe-field swiching mode liquid crystal display improved transmittance using chiral dopant - Google Patents

Abstract

The present invention is a fringe field switching (FFS) mode liquid crystal display device having an improved transmittance using a chiral dopant, the upper substrate and the lower substrate facing each other, formed on the inner surface of the upper substrate and the lower substrate, respectively, And an alignment layer, a counter electrode and a pixel electrode formed between the lower substrate and the alignment layer, interposed between the upper substrate and the lower substrate, and having a liquid crystal compound and a pitch value arranged along a rubbing axis of the alignment layer. Or a liquid crystal layer including a chiral dopant of + 4um to + 20um, wherein any one of the counter electrode and the pixel electrode has a slit shape.
When the liquid crystal is twisted in the lateral direction by the chiral dopant, the difference in the twist angle of each position of the electrode center portion, the edge portion, and the space portion is stabilized, thereby compensating the decrease in transmittance of each position, thereby improving the overall transmittance. It can maintain high electrode transmittance while maintaining electrode structure and fast response speed.

Description

Fringe field switching mode liquid crystal display with improved transmittance using chiral dopant {FRINGE-FIELD SWICHING MODE LIQUID CRYSTAL DISPLAY IMPROVED TRANSMITTANCE USING CHIRAL DOPANT}

The present invention relates to a fringe field switching (FFS) mode liquid crystal display device, and more particularly, by adding a chiral dopant having a predetermined pitch value to a liquid crystal layer formed between substrates of a liquid crystal display device of a horizontal electric field method. A fringe field switching (FFS) mode liquid crystal display device for improving transmittance.

With the rapid development of information and communication technology, the demand for displays is steadily increasing. In particular, research on liquid crystal displays (LCDs) having a wide viewing angle, fast response speed, and high transmittance is constantly being conducted.

The liquid crystal display is classified according to the initial state in which no voltage is applied, which is designed to allow light to pass through when no voltage is applied and light to pass through when no voltage is applied. A mode LCD is designed to allow light to pass through when no voltage is applied and to pass light when a voltage is applied, and is called a normally black mode LCD.

In addition, liquid crystal displays currently manufactured and used are classified into TN (Twist Nematic), IPS (In-Plane Switching), FFS (Fringe-Field Switching), and VA (Vertical alignment) modes.

Conventional TN type liquid crystal display device has a problem that the viewing angle is narrow due to large color inversion depending on the angle of viewing the liquid crystal panel. In order to solve this problem, the development of a liquid crystal display device having a wide viewing angle has been required, and a horizontal electric field type liquid crystal display device (IPS, FFS) has been developed. Such a horizontal electric field method is known as a technique excellent in viewing angle and side visibility by forming the direction of an electric field in parallel with a liquid crystal layer using a horizontally oriented liquid crystal.

However, in the horizontal electric field method, since the liquid crystals positioned on the electrodes stand in the electric field direction, loss of light transmittance on the electrodes occurs. The light transmittance at this time is known to be only about 65% compared to the conventional TN method.

This loss in transmittance is due to the structure of the FFS mode liquid crystal display device. In a normally electric black mode LCD (horizontal electric field system including FFS), twisted liquid crystals of two TN modes are twisted in reverse when voltage is applied. It becomes form (inverse twist structure). This is because in a normally black mode LCD, because the rubbing direction of the upper and lower substrates is the same, the rotation of the liquid crystal starting from the lower substrate returns to the upper substrate due to the electric field of the lower substrate.

In the FFS type liquid crystal display, the electric field distribution varies according to the position of the electrode. Specifically, since only a vertical electric field exists in the center portion of the electrode and the space portion, but no horizontal electric field exists, the liquid crystal in the center portion is twisted only by a twisting force induced from the electrode edge portion where the horizontal electric field exists. Therefore, different electro-optic properties are exhibited at the center portion of the electrode, the space portion, and the electrode edge portion.

Due to the difference between the reverse twist structure and the electric field distribution, a weak twist is formed at the center of the electrode having a weak transverse electric field and the space portion, and a strong twist is formed at the rest of the electrode including the strong edge of the transverse electric field. Since the twist angles are formed differently for each electrode position, the transverse field has a weak transmittance at the center of the electrode and the space portion, and the remaining portions including the relatively strong electrode edges have a strong twist, resulting in an over-twist, resulting in a decrease in transmittance. do.

As described above, the lowering of the transmittance causes a problem of lowering the brightness that determines the quality of the LCD by darkening the overall brightness of the screen. In addition, due to the emergence of large LCDs, many researches and developments are being made on technologies for increasing luminance at low power consumption. Also, as outdoor performances increase, interest in LCDs having high outdoor visibility is increasing. The raising technique is expected to have a significant meaning.

In order to solve the problem of lowering the transmittance, a method of improving transmittance, such as expanding an opening, changing an electrode structure, and adjusting a cell gap, has been developed.However, the conventional transmittance improving method is difficult to control due to a narrow error range when the opening is expanded. There are limitations in changing the electrode structure, and there is a problem in that the response speed increases when the cell gap is adjusted.

Therefore, research and development for overcoming the decrease in transmittance of the conventional FFS type liquid crystal display is required. In particular, studies to overcome the problems of the conventional transmittance improvement method have been made.

The present invention is to solve the above problems, when the liquid crystal is twisted in the transverse direction by adding a chiral dopant having a short pitch value with a small concentration of dopant to the liquid crystal in order to minimize the transmission loss in the conventional FFS mode, An object of the present invention is to improve the overall transmittance by stabilizing a difference in twist between positions of the electrode center portion, the edge portion, the space portion, and the center portion of the space portion, thereby compensating for the decrease in transmittance.

In addition, the conventional method of improving the transmittance narrows the error range of the process when opening the opening is difficult to control, there is a limit in changing the electrode structure, the response speed increases when adjusting the cell gap, but the present invention, the opening and the electrode The purpose is to maintain the structure and maintain a high transmittance while having a fast response speed.

In addition, the purpose of the present invention is to increase the luminance of the LCD by improving the transmittance, thereby making the brightness of the screen brighter even at a lower power consumption, thereby increasing energy efficiency.

In addition, it aims to provide various applications of LCD by realizing high brightness to improve outdoor visibility of LCD used outdoors in modern society.

In order to achieve the above object, a fringe field switching (FFS) mode liquid crystal display device having an improved transmittance using a chiral dopant according to the present invention includes an upper substrate and a lower substrate, the upper substrate, and the lower substrate installed to face each other. A liquid crystal compound formed on an inner surface of the alignment layer having a rubbing axis, interposed between the counter and pixel electrodes formed between the lower substrate and the alignment layer, interposed between the upper substrate and the lower substrate, and arranged along the rubbing axis of the alignment layer; And a liquid crystal layer including a chiral dopant having a pitch value of −20 μm to −4 μm or +4 μm to +20 μm, wherein one of the counter electrode and the pixel electrode is in a slit form.

Here, the rubbing axis is characterized in that it has an angle of preferably 3 ° to 35 ° with respect to the slit direction.

The chiral dopant has a negative pitch value with respect to the liquid crystal that rotates in a clockwise direction when driving the liquid crystal, and is preferably -20um to -4um.

In addition, the chiral dopant is characterized in that it comprises at least one of the formula 1-1 to 1-4.

≪ Formula 1-1 >

(1-2)

<Formula 1-3>

<Formula 1-4>

On the other hand, the chiral dopant has a positive pitch value for the liquid crystal that rotates in the counterclockwise direction when driving the liquid crystal, preferably characterized in that + 4um to + 20um.

In addition, the chiral dopant is characterized in that it comprises at least one of the formulas 2-1 to 2-5.

&Lt; Formula (2-1)

&Lt; Formula (2-2)

<Formula 2-3>

<Formula 2-4>

<Formula 2-5>

The chiral dopant has a d / p value of 0.16 to 0.95.

The chiral dopant may be 0.1 part by weight to 2 parts by weight in 100 parts by weight of the liquid crystal layer.

According to the liquid crystal display device to which the chiral dopant of the present invention is added, when the liquid crystal is twisted in the transverse direction when the chiral dopant having a short pitch value is added to the liquid crystal with a small concentration of dopant, the electrode center portion, the edge portion, and the space There is an advantage of improving the overall transmittance by stabilizing the twist difference of each position of the center portion and the space portion to compensate for the decrease in transmittance.

In addition, the conventional method of improving the transmittance narrows the error range of the process when opening the opening is difficult to control, there is a limit in changing the electrode structure, the response speed increases when adjusting the cell gap, but the present invention, the opening and the electrode Maintaining the structure and having a fast response speed has the advantage of maintaining a high transmittance.

In addition, by increasing the transmittance, the brightness of the LCD is increased, and thus, the brightness of the screen is brighter even with low power consumption, thereby increasing energy efficiency.

In addition, there is an advantage that can implement a variety of LCD by improving the outdoor visibility of the LCD that is used outdoors in modern society by implementing a high brightness.

1 is a cross-sectional view of a fringe field switching (FFS) mode liquid crystal display according to the present invention.
FIG. 2 is a graph showing a change in the twist angle of the center portion of the electrode when a chiral dopant having a pitch value of -20 μm or +20 μm is added to a liquid crystal rotating in a counterclockwise direction (in the horizontal axis z / d, d is Cell gap, z is the z-axis length)
3 is a graph showing a change in the twist angle of an electrode edge when a chiral dopant having a pitch value of -20 μm or +20 μm is added to a liquid crystal rotating in a counterclockwise direction, respectively.
4 is a graph showing a change in the twist angle of a space portion when chiral dopants having pitch values of −20 μm and +20 μm are respectively added to a liquid crystal rotating in a counterclockwise direction.
5 is a graph showing a change in the twist angle of the central portion of the space portion when chiral dopants having pitch values of -20 um and +20 um are respectively added to the liquid crystal rotating in the counterclockwise direction.
FIG. 6 is a graph showing a change in the twist angle of the center portion of an electrode when a chiral dopant having a pitch value of −20 μm or +20 μm is added to a liquid crystal rotating in a clockwise direction. FIG.
FIG. 7 is a graph showing a change in the twist angle of an electrode edge portion when chiral dopants having pitch values of −20 μm and +20 μm are added to a liquid crystal rotating in a clockwise direction.
8 is a graph showing a change in the twist angle of a space portion when a chiral dopant having a pitch value of -20 μm or +20 μm is added to a liquid crystal rotating in a clockwise direction, respectively.
9 is a graph showing a change in the twist angle of the central portion of the space portion when chiral dopants having pitch values of -20 μm and +20 μm are added to the liquid crystal rotating in the clockwise direction, respectively.
10 is a graph showing a change in transmittance when chiral dopants having pitch values of -40 um, -20 um, -10 um, -5 um, -4 um, and -3 um are respectively added to a liquid crystal rotating in a clockwise direction.
11 is an arrangement form of liquid crystal molecules when a chiral dopant having a pitch value of +3 um is added to a liquid crystal rotating in a counterclockwise direction
12 is an arrangement form of liquid crystal molecules when a chiral dopant having a pitch value of +5 m is added to a liquid crystal rotating in a counterclockwise direction

EMBODIMENT OF THE INVENTION Hereinafter, the fringe field switching (FFS) mode liquid crystal display device which added the chiral dopant which concerns on this invention is described in detail with reference to attached drawing.

Although not shown, the fringe field switching (FFS) mode liquid crystal display device according to the present invention is provided with the upper substrate and the lower substrate 10 facing each other, and is disposed on an inner surface between the upper substrate and the lower substrate 10. An alignment film 40 having a rubbing axis of and a liquid crystal layer 50 containing a liquid crystal compound rubbed at an angle to the alignment film.

 First, as shown in FIG. 1, an electrode 20 and a gate insulating layer 30 are formed on an upper portion of a lower substrate 10 and a lower portion of an alignment layer. The electrode 20 is a counter electrode for applying a common voltage to the liquid crystal cell, and a pixel electrode for applying a signal voltage applied through the TFT to the liquid crystal cell, and a gate bus line and a data bus line are arranged in cross-by-unit pixels. Each has a predetermined width and is formed spaced apart at regular intervals. In this case, the counter electrode and the pixel electrode may be made of ITO, which is a transparent electrical conductor, and a side formed adjacent to the liquid crystal layer among the counter electrode and the pixel electrode is formed in a slit shape. Accordingly, the slit type electrode may be a counter electrode or a pixel electrode depending on whether the applied voltage is a common voltage or a signal voltage. A TFT that applies and cuts off a signal voltage to the liquid crystal is disposed near the intersection of the gate bus line and the data bus line.

In addition, as shown in FIG. 1, the liquid crystal display includes a slit-shaped electrode center portion 21 and an edge portion 22, a space portion 23 on which electrodes exposed between the slits and slits are located, and a center portion 24 of the space portion. It is divided into

Next, the alignment layer 40 may be made of polyimide, and is formed to have a rubbing axis at a predetermined angle in order to align the liquid crystal in a predetermined direction. The rubbing axis is preferably formed at an angle between 3 ° and 35 ° with respect to the slit direction, more preferably 5 ° to 10 °, most preferably 7 °. When rubbing process conditions are established, the most basic thing is to set appropriate rubbing conditions, and rubbing less than 3 ° or more than 35 ° occurs when the phenomenon of locally different optical properties occurs.

The liquid crystal layer 50 is composed of a liquid crystal compound 51 and a chiral dopant 52 having a specific chiral pitch value.

Herein, the liquid crystal compound 51 is preferably a positive liquid crystal (p-type nematic liquid crystal) having a dielectric constant anisotropy (Δε), and more preferably a liquid crystal having a dielectric constant anisotropy of 4 ≦ Δε ≦ 15. Point to a compound. When the negative liquid crystal is used in the liquid crystal display device of the horizontal electric field type, the transmittance decreases, and as a result of the experiment, it is confirmed that the transmittance is further improved in the range of 4 ≦ Δε ≦ 15.

On the other hand, the chiral dopant 52 is characterized in that it has a negative pitch value for the liquid crystal that rotates in the clockwise direction when driving the liquid crystal, preferably has a pitch value of -20um to -4um, more preferably It is effective to use a chiral dopant having a pitch value of -10um to -4.5um and most preferably having a pitch value of -5um. In this case, it is preferable to use a chiral dopant including at least one of the following Chemical Formulas 1-1 to 1-4.

&Lt; Formula 1-1 >

(1-2)

<Formula 1-3>

<Formula 1-4>

Experimental results show that the liquid crystal rotating in the clockwise direction has a lower transmittance increase rate when a dopant having a pitch value of less than -20 μm is inserted compared to a dopant having a chiral pitch value of -20 μm or more. This is because the d / p value becomes smaller when the chiral pitch value is less than -20 μm, and the effect of decreasing transmittance due to the decrease in rotational force cancels the increase in transmittance due to the stabilization of the twist angle for each electrode position. In addition, when the dopant having a pitch value of more than -4um was put, it was measured that the transmittance was lower than that of the case where the dopant having a pitch value in the range of -4um or less was put. This is because the arrangement of the liquid crystal molecules of the liquid crystal layer collapses when the pitch value is greater than -4um.

In addition, the chiral dopant 52 is characterized by having a positive pitch value for the liquid crystal that rotates in the counterclockwise direction when driving the liquid crystal, preferably has a pitch value of + 4um to + 20um, more preferably Has a pitch value of + 4,5um to + 10um, and most preferably, it is effective to use a chiral dopant having a pitch value of + 5um. In this case, it is preferable to use a chiral dopant including at least one of Chemical Formulas 2-1 to 2-5.

&Lt; Formula (2-1)

&Lt; Formula (2-2)

<Formula 2-3>

<Formula 2-4>

<Formula 2-5>

As a result, in the case of the liquid crystal rotating in the counterclockwise direction, when the dopant having a pitch value of less than + 4um was added, the transmittance was lower than that of the case where the dopant having a pitch value of + 4um or more was inserted. This is because when the chiral pitch value is less than + 4um as shown in FIG. In addition, when the dopant having a pitch value of more than + 20um was added, it was measured that the transmittance increase rate was lower than that of the dopant having a pitch value of + 20um or less. This is because when the chiral pitch value is more than + 20um, the d / p value becomes small, so that the effect of decreasing transmittance due to the decrease in rotational force cancels the effect of increasing transmittance due to stabilization of the twist angle for each electrode position.

In the chiral dopant, the pitch direction is determined according to the position of the substituent. When the chiral dopant has a positive chiral pitch value, the liquid crystal is rotated in the left direction, that is, counterclockwise. When the chiral dopant has a negative chiral pitch value, the liquid crystal is moved to the right direction. That is, it rotates clockwise. Therefore, the pitch direction is mixed with the liquid crystal according to the direction of the rotating liquid crystal during driving.

On the other hand, the chiral dopant 52 preferably has a d / p value of 0.16 to 0.95, more preferably it is effective to use a chiral dopant of 0.64 to 0.76.

When the d / p value is 0.16 to 0.95, the transmittance is improved more than the range of less than 0.16 and more than 0.95. In particular, when the d / p value is 0.64 to 0.76 at the pitch value of +5 um, the transmittance is best.

The d / p value is defined as the ratio of the cell gap of the upper and lower substrates to the chiral pitch. Generally, the range of cell gaps used is 3.2um to 3.8um. In the same cell gap, the smaller the absolute value of the pitch, the larger the d / p value, and the larger the d / p value. The stronger the rotational force is, the higher the transmittance is.

In addition, the chiral dopant 52 is preferably formed in an amount of 0.1 parts by weight to 2 parts by weight, and more preferably 0.1 parts by weight to 0.2 parts by weight in 100 parts by weight of the entire liquid crystal layer 50. . If the amount of the dopant is less than 0.1 parts by weight, there is no sufficient effect, and in the range of more than 2 parts by weight, unwanted crystallization proceeds at low temperature, thereby causing a problem of losing the properties of the liquid crystal. Several experiments showed the best effect within the content ratio range.

Lastly, although not shown on the upper substrate, black matrix and liquid crystal are formed between the pixels of the polarizer and the color filter to block the light emitted from each pixel from interfering with each other and absorb the light from the outside. A color filter is formed which in turn causes the light passing through to have color, and an overcoat film used for flattening the color filter surface.

As described above, the present invention provides a fringe field switching (FFS) mode liquid crystal display using a horizontal electric field, wherein a chiral dopant having a predetermined chiral pitch value is added to a liquid crystal layer. By compensating for the portion where the twist angle of the liquid crystal for each position was not stabilized, it is possible to improve the overall transmittance.

Hereinafter, the experimental results of measuring the change in the twist angle and the transmittance of the liquid crystal display according to the present invention will be examined, and the effects of the present invention will be described.

< Experiment 1 >

Experiment to measure the change of twist angle according to the electrode position when positive chiral dopant or negative chiral dopant in liquid crystal mode rotating counterclockwise

Example  One

Liquid crystal display with a chiral dopant with? N = 0.1216,? Ε = 6.4, γ = 74 and chiral pitch values of -20um and + 20um in the liquid crystal mode rotating counterclockwise

Comparative example  One

Liquid crystal display without chiral dopant in liquid crystal mode rotating counterclockwise

The results are the same as those in FIGS. 2, 3, 4, and 5.

2 and 5, when the chiral dopant having a -20 um pitch value is added in the center portion 21 and the center portion 24 of the electrode of the liquid crystal mode liquid crystal display rotating in the counterclockwise direction according to the present invention. Twist angle is reduced than without the chiral dopant, but the addition of the chiral dopant having a + 20um pitch value can be seen that increases than without the chiral dopant.

As shown in FIG. 3, when the chiral dopant having a -20 um pitch value is added to the electrode edge portion 22 of the liquid crystal mode liquid crystal display rotating in the counterclockwise direction according to the present invention, the twist angle does not include the chiral dopant. Although it is increased than the case, it can be seen that the addition of the chiral dopant having a + 20um pitch value decreases than without the chiral dopant.

As shown in FIG. 4, when the chiral dopant having a -20 um pitch value is added to the space portion 23 of the liquid crystal mode liquid crystal display rotating in the counterclockwise direction according to the present invention, the twist angle does not include the chiral dopant. In addition, it can be seen that when the chiral dopant having a + 20um pitch value is added, the chiral dopant is decreased rather than the chiral dopant.

< Experiment 2 >

Experiment to measure the change of twist angle according to the electrode position when positive chiral dopant or negative chiral dopant in clockwise rotation is added

Example  2

Liquid crystal display with a chiral dopant with? N = 0.1243,? Ε = 7.7, and? = 103 and a chiral pitch of -20um and + 20um in a liquid crystal mode rotating clockwise

Comparative example  2

Liquid crystal display without chiral dopant in liquid crystal mode rotating clockwise

The results are the same as in FIGS. 6, 7, 8, and 9.

6 and 9, when the chiral dopant having a +20 um pitch is added to the electrode center 21 and the space 24 of the liquid crystal mode liquid crystal display rotating in the clockwise direction according to the present invention, a twist is added. The angle is reduced than when the chiral dopant is not added, but when the chiral dopant having a -20 um pitch value is added, the chiral dopant is increased.

As shown in FIG. 7, when the chiral dopant having a + 20um pitch value is added to the electrode edge portion 22 of the liquid crystal mode liquid crystal display rotating in the clockwise direction according to the present invention, the twist angle does not include the chiral dopant. In addition, it can be seen that the addition of the chiral dopant having a -20um pitch value decreases when the chiral dopant is not added.

As shown in FIG. 8, when the chiral dopant having a +20 um pitch value is added to the space portion 23 of the liquid crystal display liquid crystal display which rotates in the clockwise direction according to the present invention, the twist angle of the liquid crystal mode liquid crystal display device is greater than that of the case where the chiral dopant is not added. In addition, it can be seen that when the chiral dopant having a -20um pitch value is added, the chiral dopant is decreased rather than the chiral dopant.

As described above, when the chiral dopant having a positive chiral pitch value is inserted when the liquid crystal rotates in the counterclockwise direction, the liquid crystal rotates further at the electrode center portion 21 and the center portion 24 of the space portion, and the electrode edge portion. (22) and the space portion 23 is less liquid crystal turns.

In addition, when the chiral dopant having a negative chiral pitch value is inserted when the liquid crystal rotates in the clockwise direction, the liquid crystal rotates further at the electrode center portion 21 and the center portion 24 of the space portion, and the electrode edge portion 22 And the space portion 23 is less liquid crystal is turned.

In this way, even if the same chiral dopant is applied, the center portion of the electrode 21 and the center portion 24 of the space portion can increase the twist angle, and the rest of the portion can decrease the twist angle. This is because the direction of up and down twist that is dominant in the horizontal electric field type liquid crystal display device is different for each position.

<Experiment 3>

Experiment to measure the change of transmittance upon addition of different chiral pitch value to liquid crystal mode rotating clockwise

Example  3

Liquid crystal display with chiral dopant of -40um, -20um, -10um, -5um, -4um, -3um in chiral pitch value in clockwise rotation

Comparative example  3

Liquid crystal display without chiral dopant in liquid crystal mode rotating clockwise

As shown in Fig. 10, when comparing the transmittance between 4 ~ 5V, when the chiral dopant having a pitch value of -40um, -20um, -10um, -5um, -4um is added 0.41% compared to the chiral dopant not applied , 1.85%, 4.09%, 7.59%, and when the chiral dopant with pitch value of -3um was added, the transmittance was significantly decreased. (Based on voltage of 4.3V)

Here, when the chiral dopant having a pitch value of -5um is added, it can be seen that the transmittance is most improved.

On the other hand, when the chiral dopant having a pitch value of -3 um was added, the transmittance decreased sharply. This is because when the chiral pitch value is less than -4 um, the arrangement of the liquid crystal molecules in the liquid crystal layer collapses (see FIG. 11).

In addition, when the chiral dopant having a pitch value of −40 μm was added, the transmittance was increased than when the chiral dopant was not added, but the increase rate of the transmittance was decreased when adding the chiral dopant having a pitch value of −20 μm. This is because the transmittance reduction effect due to the decrease in the rotational force for rotating the liquid crystal molecules due to the small d / p value cancels out the increase effect of the transmittance due to the stabilization of the twist angle for each electrode position.

Although the preferred embodiments of the present invention have been described above, the present invention can be well understood by the above embodiments, and the above embodiments are for illustrative purposes of the present invention and are defined by the appended claims. It is not intended to limit the scope of protection.

10: lower substrate
20: Electrode
21: center electrode
22: electrode edge
23: space part
24: center part of the space part
30: gate insulating film
40: alignment film
50: liquid crystal layer
51: liquid crystal compound
52: chiral dopant

Claims (8)

An upper substrate and a lower substrate installed to face each other;
An alignment layer formed on inner surfaces of the upper substrate and the lower substrate and having a rubbing axis;
A counter electrode and a pixel electrode formed between the lower substrate and the alignment layer; And
A liquid crystal layer interposed between the upper substrate and the lower substrate and including a liquid crystal compound arranged along the rubbing axis of the alignment layer and a chiral dopant having a pitch value of −20 μm to −4 μm or +4 μm to +20 μm, ,
One of the counter electrode and the pixel electrode is in the form of a slit,
The chiral dopant is a fringe field switching (FFS) mode liquid crystal display, characterized in that the d / p value (distance ratio of the upper and lower substrate to chiral pitch) is 0.16 to 0.95 The method of claim 1,
Friction field switching (FFS) mode liquid crystal display device characterized in that the rubbing axis has an angle of 3 ° to 35 ° with respect to the slit direction The method of claim 1,
The chiral dopant is a fringe field switching (FFS) mode liquid crystal display, characterized in that the negative pitch value for the liquid crystal that rotates in the clockwise direction when driving the liquid crystal The method of claim 3,
The chiral dopant includes at least one of the following Chemical Formulas 1-1 to 1-4:
&Lt; Formula 1-1 >

(1-2)

<Formula 1-3>

<Formula 1-4>

The method of claim 1,
The chiral dopant has a fringe field switching (FFS) mode liquid crystal display, characterized in that it has a positive pitch value for the liquid crystal that rotates in the counterclockwise direction when the liquid crystal is driven. The method of claim 5,
The chiral dopant is a fringe field switching (FFS) mode liquid crystal display device comprising at least one of the following formulas 2-1 to 2-5
&Lt; Formula (2-1)

&Lt; Formula (2-2)

<Formula 2-3>

<Formula 2-4>

<Formula 2-5>

delete The method of claim 1,
The chiral dopant has a fringe field switching (FFS) mode liquid crystal display, characterized in that 0.1 parts to 2 parts by weight in 100 parts by weight of the liquid crystal layer.

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