KR20050020482A - Bistable Chiral-Splay- Nematic Liquid Crystal Display device - Google Patents

Abstract

PURPOSE: A bistable chiral splay nematic LCD is provided to carry out vertical switching and horizontal switching by inducing vertical electric fields between first and second electrodes and horizontal electric fields between the second and third electrodes, when voltage differences are generated among the electrodes by different driving voltages. CONSTITUTION: A bistable chiral splay nematic LCD includes upper and lower substrates(50,52), and first and second transparent electrodes(54,58) respectively formed of transparent conductive metal such as ITO on the upper and lower substrates, wherein first and second orientation films(56,64) are respectively formed on the upper and lower substrates. A protecting film(60) is formed of silicon compound or an insulating material such as BCB on the lower substrate. At least one or more third transparent electrodes(62) are formed of the transparent conductive metal on the lower substrate having the protecting film. Bistable chiral splay nematic LC(66) is initially oriented by the first and second orientation film and in the splay state or 180° twist state according to driving voltages applied to the first to third transparent electrodes.

Description

Bistable chiral-splay-nematic liquid crystal display device

The present invention relates to a liquid crystal display device, and more particularly, to a bistable chiral splay nematic liquid crystal display device capable of enhancing the applicability of a bistable chiral splay nematic liquid crystal.

Recently, as the information society has progressed rapidly, a display field for processing and displaying a large amount of information has been developed. Until modern times, cathode ray tube (CRT) has become the mainstream of display devices and has been developing. However, in recent years, the need for a flat panel display has emerged in order to meet the era of thinning, light weight, and low power consumption. Accordingly, a thin film transistor-liquid crystal display device having excellent color reproducibility has been developed.

The driving principle of the liquid crystal display device uses the optical anisotropy and polarization of the liquid crystal. Since the liquid crystal is thin and long in structure, the liquid crystal has directivity in the arrangement of molecules, and the direction of the molecular arrangement can be controlled by artificially applying an electric field to the liquid crystal.

Accordingly, if the molecular arrangement direction of the liquid crystal is arbitrarily adjusted, the molecular arrangement of the liquid crystal is changed, and the refractive index of light is changed according to the molecular arrangement direction of the liquid crystal due to optical anisotropy, thereby representing image information.

In general, the structure of a liquid crystal panel, which is a basic component of a liquid crystal display, will be described.

1 is a cross-sectional view showing a cross section of a general liquid crystal panel.

In the liquid crystal panel 20, two substrates 2 and 4 having various kinds of elements are formed to correspond to each other, and the liquid crystal layer 10 is interposed between the two substrates 2 and 4. have.

The liquid crystal panel 20 includes an upper substrate 4 having a color filter representing a color and a lower substrate 2 having a switching circuit capable of converting a molecular arrangement direction of the liquid crystal layer 10.

The upper substrate 4 includes a color filter layer 8 for implementing colors and a common electrode 12 covering the color filter layer 8. The common electrode 12 serves as one electrode for applying a voltage to the liquid crystal 10. The lower substrate 2 has a thin film transistor S serving as a switching function and a pixel electrode 14 serving as an electrode for receiving a signal from the thin film transistor S and applying a voltage to the liquid crystal 10. It is composed of In order to prevent leakage of the liquid crystal 10 injected between the upper substrate 4 and the lower substrate 2, sealants 6 may be formed at edges of the upper substrate 4 and the lower substrate 2. It is sealed with).

As described above, liquid crystals most applied in the field of display include nematic, smectic, and cholesteric types.

2A to 2C are diagrams showing molecular arrangements of the liquid crystal. Here, the arrow direction indicates the liquid crystal array direction.

FIG. 2A shows a molecular arrangement of nematic liquid crystals, and is arranged in a plurality of thin threads. Here, the molecular arrangement of the nematic liquid crystal has parallelism, there is no regularity of position, and the whole molecule side is directed in one direction.

FIG. 2B is a diagram showing the molecular arrangement of the smectic liquid crystal and has the same sticky property as mucus. The regularity of molecular alignment is stronger than that of the smetic-type nematic liquid crystal and the cholesteric liquid crystal. In addition, as shown in FIG. 2B, a plurality of layers are formed, and each layer is arranged in parallel with each other.

FIG. 2C is a diagram showing the molecular arrangement of the cholesteric liquid crystal, in which the axis of the molecule is twisted in one direction. The cholesteric liquid crystal is arranged in a plurality of layers like the smectic liquid crystal, and takes a parallel arrangement inside each layer like the nematic liquid crystal.

Among the liquid crystals described above, nematic liquid crystals having the property of scattering the light most strongly when the arrangement is disturbed have the most application range in the display field. In this case, when the light proceeds to the nematic liquid crystal, the traveling light is deflected in the direction of the molecular axis.

As described above, the liquid crystal applied in the display field needs the following conditions.

That is, 1) It should be able to show the liquid crystal phase in the temperature range from low temperature to high temperature and use it in the wide temperature range. 2) Excellent chemical and optical stability and long lifespan. 3) Low viscosity and fast response speed. 4) High molecular order and suitable for increasing display contrast. 5) Dielectric anisotropy is large and suitable for low voltage operation. Liquid crystals satisfying such conditions are those that can be used in the display field.

The electro-optic effect of liquid crystal refers to the phenomenon that light modulation occurs due to the change of the optical properties of the liquid crystal cell in response to an electrical signal. Due to

Among the liquid crystals applied to the current display, the nematic liquid crystals described above are the most common. In the display using the nematic liquid crystal, a twisted nematic (TN) type and a super twisted nematic (STN) type in which the display is arranged are mainly used in view of the molecular arrangement being continuously changed when an electric field is applied to the nematic liquid crystal. The TN effect is composed of a cell having a 90 ° angle on two transparent electrodes oriented so as to be parallel to the electrode surface of the molecular length axis of the liquid crystal, and when a nematic liquid crystal is injected thereinto, It is an arrangement state twisted 90 degrees continuously in the longitudinal axis direction of the molecule toward the electrode surface. The STN effect refers to the angle of twist continuously compared to the TN effect. However, the device is highly integrated and requires a fast processing speed, and thus a new mode of liquid crystal display device having a superior performance such as securing a viewing angle of a liquid crystal display device, a high response speed and a high contrast ratio is required. For the same reason, a new mode of liquid crystal display such as BTN-LCD (Bistable Twisted Nematic-LCD) is required. The BTN (hereinafter referred to as bistable) liquid crystal cell refers to a liquid crystal cell in which a chiral material is added to a general nematic liquid crystal. The bistable liquid crystal display of the prior art is a new mode liquid crystal having excellent performance such as wide viewing angle characteristics, high speed response characteristics, and high contrast ratio, compared to conventional simple matrix addressing liquid crystal display devices such as STN-LCD. The principle of operation as the display element is as follows.

3A is a flowchart showing a conventional switching operation. When a reset voltage VR is applied to a bistable liquid crystal cell arranged in an initial 180 ° twisted state, the bistable liquid crystal cell in an initial splay state is The vertical arrangement is achieved.

When the selection voltage V is applied to the bistable liquid crystal cell in which the vertically arranged state is formed by the reset voltage VR, the transition to the 360 ° twisted state or the 0 ° twisted metastable state depends on the magnitude of the selection voltage.

Figure 3b is a view showing the operation of the liquid crystal according to the switching of the present invention when the voltage is applied to the initial splay-oriented liquid crystal perpendicular to the transition to the bend state and then switched to the 180 ° twisted state remains stable. At this time, if the voltage is applied horizontally, it returns to the initial 0 ° splay state from the 180 ° twist state.

Thus, since the conventional bistable liquid crystal cell is switched only by the transition of the torsion angle, the liquid crystal display device having excellent viewing angle characteristics and excellent response characteristics and contrast compared to TN-LCD or STN-LCD, and operates only by simple matrix driving. This has a possible advantage.

However, the bistable liquid crystal display of the prior art has the following problems.

The metastable state of the 360 ° twisted state is shorter in holding time than the splayed state, so there is a need for a method for extending the retention time of the 360 ° twisted state. There was a disadvantage in that the structure of the liquid crystal display device is insufficient.

The present invention is to solve the above problems, by vertically switching the bistable liquid crystal cell to which the chiral dopant is added to fix the 180 ° twisted state, the horizontal stable switching of the bi-stable liquid crystal cell of the 180 ° twisted state splay It is an object of the present invention to provide a bistable chiral splay nematic liquid crystal display device having high application state.

A bistable chiral splay nematic liquid crystal display device for achieving the above object includes an opposing upper substrate and a lower substrate, a first electrode formed on the upper substrate, a second electrode formed on the lower substrate and And a protective film formed on the lower substrate on which the second electrode is formed, a third electrode on which the protective film is formed, and a bistable chiral splay nematic liquid crystal formed between the upper substrate and the lower substrate.

In addition, another object of the present invention, the upper substrate and the lower substrate facing each other at a predetermined interval, the first transparent electrode formed of a transparent conductive metal on the upper substrate, and the upper substrate on which the first transparent electrode is formed A first alignment layer formed on the substrate, a second transparent electrode formed on the lower substrate, a protective film formed on the lower substrate on which the second transparent electrode is formed, and a third transparent electrode formed on the lower substrate on which the protective film is formed; And a second alignment layer formed on the lower substrate on which the third transparent electrode is formed and initially oriented by the first alignment layer and the second alignment layer and applied to the first transparent electrode, the second transparent electrode, and the third transparent electrode. A bistable chiral splay nematic liquid crystal display comprising a bistable liquid crystal having a splay state and a 180 [deg.] Twist state in accordance with a driving voltage.

Here, it is preferable that the bistable liquid crystal further includes a chiral dopant.

That is, in the initial splay state of the bistable liquid crystal containing a chiral dopant, the bistable 180 ° transition is performed by the vertical switching by applying the driving voltage of the first transparent electrode and the second transparent electrode, and the 180 ° transition is performed. Increase the holding time in the stable state of the bistable chiral splay nematic liquid crystal display by controlling the bistable liquid crystal in the twisted state to the splay state by using horizontal switching by the driving voltage of the second transparent electrode and the third transparent electrode. Applicability can be improved.

Hereinafter, a bistable chiral splay nematic liquid crystal display of the present invention will be described with reference to the accompanying drawings. Here, although the present invention describes a bistable chiral splay nematic liquid crystal display, the principles and construction of the present invention may be used in optical modulation.

4 is a schematic cross-sectional view of the bistable chiral splay nematic liquid crystal display device of the present invention.

As shown in FIG. 4, the bistable chiral splay nematic liquid crystal display device of the present invention has an upper substrate 50 and a lower substrate 52 facing each other at predetermined intervals, and on the lower substrate 52. A first transparent electrode 54 formed of a transparent conductive metal such as indium tin oxide (ITO), a first alignment layer 56 formed on the upper substrate 50 on which the first transparent electrode 54 is formed, and the A second transparent electrode 58 formed of a transparent conductive metal such as ITO on the lower substrate 52 and an insulating material such as a silicon compound or BCB on the lower substrate 52 on which the second transparent electrode 58 is formed A protective film 60 formed of a material, at least one third transparent electrode 62 formed of a transparent conductive metal such as ITO on the lower substrate 52 on which the protective film 60 is formed, and the third transparent electrode The first alignment layer 56 on the lower substrate 52 having the 62 formed thereon. Initially oriented by the second alignment layer 64 rubbed in the same direction, the first alignment layer 56 and the second alignment layer 64, and the first transparent electrode 54, the second transparent electrode 58, and the first alignment layer. And a bistable chiral splay nematic liquid crystal 66 having a splay state and a 180 ° twist state in accordance with the driving voltage applied to the three transparent electrodes 62.

Here, when the voltage difference occurs between the two electrodes by applying the different driving voltages to the first transparent electrode 54 and the second transparent electrode 58, the first transparent electrode 54 and the second transparent electrode A vertical electric field is induced between 58 to vertically switch the bistable chiral splay nematic liquid crystal 66, and the driving voltages different from each other to the second transparent electrode 58 and the third transparent electrode 62 are different from each other. When a voltage difference is generated between the two electrodes by applying a voltage, a horizontal electric field is induced between the second transparent electrode 58 and the third transparent electrode 62 to horizontally switch the bistable chiral splay nematic liquid crystal 66. can do.

In addition, since the bistable chiral splay nematic liquid crystal 66 contains a chiral dopant of a predetermined concentration (e.g., d / p is less than about 0.25%), the bistable chiral splay nematic liquid crystal 66 Although the initial orientation is maintained in the splay state by the surface anchoring energy of the first alignment layer 56 and the second alignment layer 64, a predetermined voltage Vth is applied to the first transparent electrode 54 and the second transparent electrode 58. The bistable chiral splay nematic liquid crystal 66 has a bistable 180 ° twist state when the driving voltage is applied and the external voltage is removed, and the twist is caused by the action of the chiral dopant. Keep your status. In this case, the cell gap between the upper substrate 50 and the lower substrate 52 may be reduced to maintain the metastable 180 ° twist state for a longer period of time.

Accordingly, the bistable chiral splay nematic liquid crystal display of the present invention can obtain two stable states, a splay state due to the initial orientation and a twist state due to the chiral dopant.

In addition, when an external voltage is applied to the second transparent electrode 58 and the third transparent electrode 62 to generate a voltage difference, the bistable car in a 180 ° twisted state which is metastable by a horizontal electric field according to the voltage difference. The liquid crystal director of the irral splay nematic liquid crystal 66 is horizontally switched to a splay state of 0 °.

 In this case, when the driving voltage greater than or equal to the predetermined voltage Vth is applied to the first transparent electrode 54 and the second transparent electrode 58, the driving voltage is induced between the upper substrate 50 and the lower substrate 52. By the vertical electric field, the liquid crystal director of the bistable chiral splay nematic liquid crystal 66 is vertically switched to have a vertical bend state.

By using such vertical switching and horizontal switching, the voltage applied to each pixel can be driven either active or passively. The driving method of the bistable liquid crystal display device of the present invention can be described as follows. have.

5A to 5C are schematic cross-sectional views of pixels of the bistable chiral splay nematic liquid crystal display device of the present invention.

As shown in FIG. 5A, a first thin film transistor T1 driving the first transparent electrode 54 is formed on the upper substrate 50 on which the first transparent electrode 54 is formed, and the upper substrate 50 is formed. The second thin film transistor T2 for driving the third transparent electrode 62 is formed on the lower substrate 52 opposite to the second substrate, and the vertical and horizontal switching are performed using the second transparent electrode 58 as a common electrode. Actively control In this case, the vertical switching is controlled by the turn-on operation of the first thin film transistor T1, and the horizontal switching is controlled by the turn-on operation of the second thin film transistor T2. The turn-on operations of the first thin film transistor T1 and the second thin film transistor T2 are controlled exclusively from each other. On the other hand, although not shown, a first thin film transistor T1 for driving the first transparent electrode 54 is formed on the upper substrate 50 on which the first transparent electrode 54 is formed, and the upper substrate 50 is formed. A second thin film transistor T2 for driving the second transparent electrode 58 is formed on the lower substrate 52 opposite to the second substrate. The third transparent electrode 62 is used as a common electrode to enable vertical switching and horizontal switching. To control.

As shown in FIG. 5B, a thin film transistor T driving the first transparent electrode 54 is formed on the upper substrate 50 on which the first transparent electrode 54 is formed. Actively driven, and the second transparent electrode 58 and the third transparent electrode 62 are driven manually by connecting to the data line and the scan line, respectively. In this case, during the turn-on operation of the thin film transistor T, the second transparent electrode 58 is connected to a common electrode to actively control vertical switching, and the second transparent electrode 58 and the third transparent electrode 62 are connected to the common electrode. Manually controls the horizontal switching by an applied driving voltage.

As shown in FIG. 5C, the first transparent electrode 54 formed on the upper substrate 50 is connected to the scan line, and the second transparent electrode formed on the lower substrate 52 facing the upper substrate 50 ( 58 is connected to a data line to manually control vertical switching, a third transparent electrode 62 is connected to the thin film transistor T formed on the lower substrate 52, and the thin film transistor T is turned on. At this time, the second transparent electrode 58 is used as a common electrode to actively control horizontal switching.

FIG. 6 is a view showing the domain image of FIG. 4. Referring to the state of the bistable chiral splay nematic liquid crystal 66 after horizontal switching using the second transparent electrode 58 and the third transparent electrode 62, FIG. It can be seen that two domains periodically appearing due to the pattern of the three transparent electrodes 62 are in the state of the bistable chiral splay nematic liquid crystal 66 having a 180 ° twist state and a splay state, respectively.

FIG. 7A illustrates a pulse of a drive voltage used to switch a bistable chiral splay nematic liquid crystal cell according to the present invention, and FIG. 7B is a transmission of the bistable chiral splay nematic liquid crystal cell as a function of time. The figure which shows.

Referring to FIG. 7A, 'Vst' and 'Vts' are vertical voltages for converting from 0 ° display state to metastable 180 ° twist state, respectively, and vice versa. The Vst and Vts are supplied to the bistable chiral splay nematic liquid crystal display at intervals of 5.5 seconds each. As shown in Fig. 7B, the Vst and Vts are switched to the 0 ° display state and the 180 ° twist state, respectively, at a driving voltage of about 20V. In addition, when the driving pulse width is 150 ms for Vst and 700 ms for Vts, the driving voltage becomes high when the driving pulse width is shortened, and the driving voltage becomes low when the driving pulse width is long.

  Meanwhile, in order to implement an optical compensation bend (hereinafter, referred to as OCB), the first and second alignment layers 64 are oriented so as to form symmetrically inclined bend alignment. More specifically, the surfaces of the first and second alignment films 64 are rubbed in parallel and in the same direction so that the pretilt angle is several degrees to about 10 degrees.

In this case, in the bend alignment, the liquid crystal molecules may be twisted in the plane of the X-Z axis at the central portion of the bistable chiral nematic liquid crystal 66 layer. In addition, a phase retardation plate is further provided outside the upper substrate 50 or the lower substrate 52 to optically compensate the orientation of the bistable chiral splay nematic liquid crystal 66.

Accordingly, the bistable chiral splay nematic liquid crystal display having the OCB mode bends between the first transparent electrode 54 and the second transparent electrode 58 formed on the upper substrate 50 and the lower substrate 52, respectively. If the alignment is formed, the change in the liquid crystal molecules with respect to the change in the applied driving voltage is fast, and thus the response speed is increased.

8 is a view schematically showing the structure of a transmissive bistable chiral splay nematic liquid crystal display device, wherein the transmissive bistable chiral splay nematic liquid crystal device of the present invention polarizes light introduced through a light source in a predetermined direction. A first phase retardation plate positioned on the transmission axis of the first polarizing plate and the first polarizing plate at an angle of 22.5 °, and having a phase delay value of λ / 2; and an optical axis direction on the transmission axis of the first polarizing plate. And a bistable chiral splay nematic liquid crystal 66 cell having a phase delay value of λ / 2 and positioned so as to have a transmission axis perpendicular to the transmission axis of the first polarizing plate. It consists of two polarizing plates.

9 to 10 are graphs showing simulation results and experimental results of a bistable liquid crystal display device having a bistable chiral splay nematic liquid crystal cell. Here, the horizontal axis is wavelength and the vertical axis is light transmittance.

As shown in Figs. 9 to 10, simulation results and experimental results of the bistable chiral splay nematic liquid crystal display show that the light transmittance is almost constant regardless of the wavelength. It can be seen that there is little. At this time, each upper graph shows the light transmittance in the bright state, the lower graph shows the light transmittance in the dark state. In addition, the simulation was conducted using a program called DIMOS, and the experiment was conducted using a spectrometer.

FIG. 11 is a view schematically showing the structure of a reflective bistable chiral splay nematic liquid crystal display, wherein the reflective bistable chiral splay nematic liquid crystal display of the present invention is directed to light in a constant direction. A first polarizing plate to be polarized, a phase retardation plate positioned at an angle of 15 ° to the transmission axis of the first polarizing plate, and having a phase delay value of λ / 2, and an optical axis direction to the transmission axis of the first polarizing plate A bistable chiral splay nematic liquid crystal 66 cell, positioned at an angle of 75 ° and having a phase retardation value of? / 4, and a reflecting plate for reflecting incident light.

12 to 13 are graphs showing simulation results and experimental results of a reflective bistable liquid crystal display device having a chiral splay liquid crystal cell, respectively. Here, the horizontal axis is wavelength and the vertical axis is light transmittance.

As shown in Figs. 12 to 13, simulation results and experimental results of the bistable chiral splay nematic liquid crystal display show that the light transmittance is almost constant regardless of the wavelength. It can be seen that there is little. At this time, each upper graph shows the light transmittance in the bright state, the lower graph shows the light transmittance in the dark state. In addition, the simulation was conducted using a program called DIMOS, and the experiment was conducted using a spectrometer.

The foregoing has outlined rather broadly the features and technical advantages of the present invention in order to better understand the claims of the invention which will be described later. Additional features and advantages constituting the claims of the present invention will be described below. It should be appreciated by those skilled in the art that the conception and specific embodiments of the invention disclosed may be readily used as a basis for designing or modifying other structures for carrying out similar purposes to the invention.

In addition, the inventive concepts and embodiments disclosed herein may be used by those skilled in the art as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. In addition, such modifications or altered equivalent structures by those skilled in the art may be variously changed, substituted and changed without departing from the spirit or scope of the invention described in the claims.

As described above, the bistable chiral splay nematic liquid crystal display device of the present invention has the following effects.

The bistable chiral nematic splay liquid crystal display of the present invention vertically switches a bistable liquid crystal cell containing a chiral dopant to fix a 180 ° twisted state, and horizontally switches the bistable liquid crystal cell of the 180 ° twisted state. To create a splay state to increase applicability.

1 is a cross-sectional view of a general liquid crystal display device.

2A to 2C show a structure of a general liquid crystal phase.

3A is a flowchart illustrating a method of driving a general bistable nematic liquid crystal cell.

Figure 3b is a view showing the operation of the liquid crystal according to the switching of the present invention.

4 is a schematic cross-sectional view of the bistable chiral splay nematic liquid crystal display device of the present invention.

5A to 5C are schematic cross-sectional views of pixels of the bistable chiral splay nematic liquid crystal display device of the present invention.

6 is a view showing a domain picture of FIG.

FIG. 7A illustrates a pulse of a drive voltage used to switch a bistable chiral splay nematic liquid crystal cell according to the present invention, and FIG. 7B is a transmission of the bistable chiral splay nematic liquid crystal cell as a function of time. The figure which shows.

FIG. 8 is a view schematically showing the structure of a transmissive bistable chiral splay nematic liquid crystal display.

9 to 10 are graphs showing simulation results and experimental results of a bistable liquid crystal display device having a bistable chiral splay nematic liquid crystal cell.

FIG. 11 is a view schematically showing the structure of a reflective bistable chiral splay nematic liquid crystal display. FIG.

12 to 13 are graphs showing simulation results and experimental results of a reflective bistable liquid crystal display device having a chiral splay liquid crystal cell, respectively.

Explanation of symbols in the drawings

50: upper substrate 52: lower substrate

54: first transparent electrode 56: first alignment layer

58: second transparent electrode 60: protective film

62: third transparent electrode 64: second alignment layer

66: bistable chiral splay liquid crystal

Claims (17)

Opposing upper and lower substrates, A first electrode formed on the upper substrate; A second electrode formed on the lower substrate; A protective film formed on the lower substrate on which the second electrode is formed; A third electrode having the protective film formed thereon; A bistable chiral splay nematic liquid crystal display device comprising a bistable liquid crystal formed between the upper substrate and the lower substrate. An upper substrate and a lower substrate facing each other at a predetermined interval, A first transparent electrode formed of a transparent conductive metal on the upper substrate; A first alignment layer formed on the upper substrate on which the first transparent electrode is formed; A second transparent electrode formed on the lower substrate; A protective film formed on the lower substrate on which the second transparent electrode is formed; A third transparent electrode formed on the lower substrate on which the protective film is formed; A second alignment layer formed on the lower substrate on which the third transparent electrode is formed; A bistable liquid crystal initially oriented by the first alignment layer and the second alignment layer and having a splay state and a 180 ° twist state according to a driving voltage applied to the first transparent electrode, the second transparent electrode, and the third transparent electrode. A bistable chiral splay nematic liquid crystal display, characterized in that. The method of claim 2, A bistable chiral splay nematic liquid crystal display according to claim 1, wherein at least one of the first transparent electrode, the second transparent electrode, or the third transparent electrode is made of indium tin oxide (ITO). The method of claim 2, The liquid crystal cell further comprises a chiral additive bistable chiral splay nematic liquid crystal display device. The method of claim 2, The first transparent electrode and the second transparent electrode bistable chiral splay nematic liquid crystal display, characterized in that induce a vertical electric field when a voltage difference occurs. The method of claim 2, And a voltage difference between the second transparent electrode and the third transparent electrode to induce a horizontal electric field. The method of claim 2, And the first and second alignment layers are rubbing in the same direction. The method of claim 2, And a pretilt angle of each of the first and second alignment layers is in a range of 0 degrees to 20 degrees, respectively. The method of claim 2, The protective film is a bistable chiral splay nematic liquid crystal display, characterized in that made of a silicon compound or BCB. The method of claim 2, A bistable chiral splay nematic liquid crystal display further comprising active driving, including at least one thin film transistor formed on the upper substrate or the lower substrate, or including passive driving without including the thin film transistor. Device. The method of claim 10, A first thin film transistor for driving the first transparent electrode on the upper substrate; A bistable chiral splay nematic liquid crystal display further comprising a second thin film transistor for driving a second transparent electrode or a third transparent electrode on the lower substrate. The method of claim 11, wherein 2. A bistable chiral splay nematic liquid crystal display, characterized in that a second transparent electrode or a third transparent electrode not connected to the second thin film transistor is used as a common electrode. The method of claim 10, And the second transparent electrode and the third transparent electrode are connected to a scan line or a data line, respectively, when the first transparent electrode is connected to the thin film transistor. The method of claim 10, When the thin film transistor is connected to the third transparent electrode, the first transparent electrode and the second transparent electrode are connected to a scan line or a data line, respectively. The method of claim 2, A bistable chiral splay nematic liquid crystal display further comprising a phase retardation plate for optically compensating the orientation of the bistable liquid crystal on the outside of the upper substrate or the lower substrate. The method of claim 2, A bistable chiral splay nematic liquid crystal display device, which can apply a glass substrate and a plastic substrate as the upper substrate or the lower substrate. The method of claim 2, A bistable chiral splay nematic liquid crystal display device having a d / p of 0.25 or less by mixing a chiral additive of 2% or less with a liquid crystal.