KR20050042592A - Transflective type liquid crystal display device - Google Patents

Abstract

In the present invention, in order to provide a single cell gap structure semi-transmissive liquid crystal display device having high brightness and high contrast characteristics, a slit and a hole (a slit) and a hole ( By constructing the reflecting portion of the pixel electrode having an open portion such as a hole), the phase difference between the reflecting portion and the transmitting portion can be different, so that the transmitting portion and the reflecting portion can be formed in the same cell gap, which simplifies the process, and the black / The brightness can be improved by matching the white driving voltage, which enables high brightness and high contrast of the product.

Description

Transflective type Liquid Crystal Display Device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a transflective liquid crystal display device having both a reflecting portion and a transmitting portion.

In general, 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, when the molecular arrangement direction of the liquid crystal is arbitrarily adjusted, the molecular arrangement of the liquid crystal is changed, and light is refracted in the molecular arrangement direction of the liquid crystal due to optical anisotropy to express image information.

Currently, an active matrix liquid crystal display device (hereinafter referred to as an active matrix LCD), in which a thin film transistor and pixel electrodes connected to the thin film transistor are arranged in a matrix manner, is attracting the most attention because of its excellent resolution and video performance.

BACKGROUND ART A commonly used liquid crystal display device has used a method of representing an image by a light source called a back light. However, since the amount of light actually seen through the liquid crystal display is about 7% of the light generated by the backlight, the brightness of the backlight should be bright in the high brightness liquid crystal display, and thus power consumption by the backlight is large.

Therefore, in order to supply sufficient backlight power, a battery having a large weight has been used by increasing the capacity of the power supply device. However, this also has a limitation in the use time.

In order to solve the above-mentioned problems, recently, transflective liquid crystal display devices that can combine natural light or artificial light and backlight light according to the use environment have been researched and developed.

The transflective liquid crystal display is free to switch to the reflective or transmissive mode according to the user's will.

1 is a cross-sectional view showing a cross section of a conventional single cell gap structure semi-transmissive liquid crystal display device. The single cell gap structure described above means a structure in which the cell gap, which can be defined by the thickness of the liquid crystal layer, is the same in both the reflection part and the transmission part.

As illustrated, the first and second substrates 10 and 30 are disposed to be spaced apart from each other and have a structure in which a liquid crystal layer 50 is interposed between the first and second substrates 10 and 30. have.

A transparent electrode 12 is formed on the first substrate 10, an insulating layer 14 is formed on the transparent electrode 12, and a portion of the transparent electrode 12 is formed on the insulating layer 14. A reflective layer 18 having an open portion 16 to be exposed is formed. Substantially, the insulating layer 14 constituting the lower layer is exposed in the open portion 16 region, and the transparent electrode positioned in the region corresponding to the open portion 16 due to light transmittance of the insulating layer 14. Reference numeral 12 can transmit the backlight light.

Although not shown in detail in the drawings, the reflective layer 18 may correspond to either a reflective electrode or a reflective plate having an island pattern structure. For example, the transparent electrode 12 including the reflective layer 18 may include a pixel electrode. Achieve.

In addition, the color filter layer 32 and the common electrode 34 are sequentially formed below the second substrate 30.

The region corresponding to the reflective layer 18 forms a reflector for implementing a screen using external light as a light source, and the region corresponding to the open portion 16 forms a transmissive portion using backlight light as a light source, and the reflector cell gap (g1) and the transmission cell gap g2 have values corresponding to each other.

Accordingly, when the incident light on the reflecting side passes through the liquid crystal layer twice, as shown in FIG. 2, when the same driving voltage is applied to the reflecting portion and the transmitting portion, the voltage / luminance characteristics of the reflecting portion and the transmitting portion are different. It has a problem that is difficult to achieve.

In more detail, in the transmission part, the light supplied from the backlight is directly transmitted to the outside through the liquid crystal layer, but in the case of the reflection part, the external light is reflected from the reflection layer through the liquid crystal layer and then transmitted to the outside through the liquid crystal layer. This is because the phase difference change in the liquid crystal layer and the reflective layer at the time of voltage application cannot be the same between the reflecting portion and the transmitting portion.

In order to solve the problem in the single cell gap structure, a dual cell-gap structure liquid crystal display device having a structure in which the transmission cell gap is larger than the reflection cell gap has been proposed.

FIG. 3 is a schematic cross-sectional view of a conventional dual cell gap structure semi-transmissive liquid crystal display device, and a description will be given based on a dual cell gap structure between a reflection part and a transmission part.

As shown in the figure, the first and second substrates 60 and 80 are disposed to be spaced apart from each other, and the first substrate 60 has a structure in which a liquid crystal layer is interposed between the first and second substrates. The transparent electrode 62 is formed on the upper surface, and the insulating layer 66 which has the 1st open part 64 which exposes the transparent electrode 62 partly is formed in the upper part of the transparent electrode 62. In addition, a reflective layer 70 having a second open portion 68 corresponding to the first open portion 64 is formed on the insulating layer 66.

Although not shown in detail in the drawings, the reflective layer 70 may correspond to either a reflective electrode serving as an electrode or a reflective plate having an island pattern structure.

A color filter layer 82 and a common electrode 84 are sequentially stacked below the second substrate 80, and a liquid crystal layer 90 is interposed between the first and second substrates 60 and 80. The thickness of the liquid crystal layer 90 is defined by the cell gaps G1 and G2.

Here, the substrate region corresponding to the reflective layer 70 forms a reflector, and the region of the transparent electrode 62 exposed in the section between the first and second open portions 64 and 68 forms a transmissive portion. In order to reduce the difference in the phase difference value of the light due to the difference between the travel distance L1 and the travel distance L2 of the light in the transmission part, the travel distance L1 of the light in the reflection part is the travel distance of the light in the transmission part ( In consideration of being twice as large as L2, the reflecting part cell gap G1 including the insulating layer 66 is the first open part of the insulating layer 66 by the thickness value of the insulating layer 66. Characterized in that it corresponds to 1/2 of the transmission cell gap (G2) having a (64).

In summary,

L1 = 2, L2

G1 = 1/2 G2

Since the relationship between is satisfied, the phase difference between the reflecting portion and the transmitting portion can be maintained at the same level, so that the luminance between the two modes can be maintained uniformly.

However, the dual cell gap structure transflective mode has the following problems.

First, in order to provide a cell gap difference between the reflecting unit and the transmitting unit, an organic insulating material having excellent step characteristics is mainly used. In the case of the organic insulating material, a separate process equipment is required and the material cost is high.

Secondly, depending on the step of the insulating layer, the process of varying the cell gap between the reflecting portion and the transmitting portion requires a substantially complicated process condition, and thus the process efficiency is lowered.

In order to solve the above problems, an object of the present invention is to provide a single cell gap structure transflective liquid crystal display device having high brightness and high contrast characteristics.

To this end, the present invention is to form a pattern structure that can weaken the intensity of the electric field in the reflecting region of the pixel electrode. For example, the reflective part of the pixel electrode having an open part such as a slit and a hole may be configured.

The above-described reflective part of the pixel electrode corresponds to a structure including a transparent electrode and a reflective layer, and as an example, an open portion is formed in the transparent electrode area corresponding to the reflective plate.

In order to achieve the above object, in the present invention, the gate wiring formed in the first direction on the first substrate; A data line formed in a second direction crossing the first direction; A common wiring formed to be spaced apart from the gate wiring in the first direction; A reflective electrode defined by the pixel area and connected to the common line and formed in the pixel area; A thin film transistor formed at an intersection point of the gate line and the data line; A transparent electrode connected to the thin film transistor in a pixel area, overlapping the reflective electrode with an insulator, and having an open part in the overlapping area; A second substrate disposed to face the first substrate; A common electrode formed on an inner surface of the second substrate; And a liquid crystal layer interposed between the first and second substrates, wherein the reflective electrode forming portion forms a reflecting portion, and the transparent electrode forming portion, which is located in correspondence with the reflecting electrode, forms a transmitting portion, and the thickness of the liquid crystal layer is a cell gap. The reflector cell gap and the transmission cell gap are defined at the same level, and when the voltage is applied, the intensity of the electric field in the open area is weaker than that in the other pixel areas.

The open part is formed of any one of a slit or a hole shape, a region in which the reflective electrode and the transparent electrode overlap with each other forms a storage capacitance, the common wire and the common electrode are applied with the same common voltage, and the transparent electrode has a pixel voltage. The transparent electrode and the reflective electrode are applied to form a pixel electrode.

The liquid crystal molecules constituting the liquid crystal layer are made of a positive liquid crystal having long axes arranged in a direction parallel to an electric field, wherein the reflecting portion and the transmitting portion have different phase difference values, and the reflecting portion and the transmitting portion are at the same level. It has a black / white driving voltage value of 1, the first and the second alignment layer is formed on the first and second substrate surface in contact with the liquid crystal layer, the first and second alignment layer is the initial arrangement of the liquid crystal molecules It is a horizontal alignment film to be parallel to the substrate surface, the liquid crystal display is characterized in that the NB mode (normally black mode).

On both rear surfaces of the first and second substrates, the first and second polarizing plates having the same polarization axis and the first and second polarizing plates and the second and second polarizing plates are respectively orthogonal to each other. And a first and second retardation plates for varying the phase difference of light by? / 4, wherein the liquid crystal layer is a liquid crystal layer for changing the phase difference of light by? / 2, and in the liquid crystal display device, When the voltage is applied, the phase difference value of the transmission part is converted from λ / 2 to 0 (zero), the phase difference value of the reflecting part has a value between 0 and λ / 2, and the first and second polarizing plates have a 0 ° polarization axis. The first retardation plate has a 135 ° angle, the second retardation plate has a 45 ° angle, the liquid crystal molecules have a 135 ° angle difference with the polarization axis, and the phase difference value of the reflector is λ / 4.

In addition, the liquid crystal display (NW) mode is a normally white mode, and first and second polarizing plates having the same polarization axis are positioned on both rear surfaces of the first and second substrates, and the transmission axes of the first and second polarizing plates are 0 °, the liquid crystal display has a phase difference value of the transmissive part converted from λ / 2 to 0 (zero) when voltage is applied, and a phase difference value of the reflective part has a value between 0 and λ / 2, and the reflection The negative phase difference value is λ / 4.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

First Embodiment

4A to 4C are diagrams illustrating a transflective liquid crystal display device according to a first embodiment of the present invention, and FIG. 4A is a plan view, and FIGS. 4B and 4C are cross-sectional views cut along the cutting line IVa-IVa of FIG. 4A. 4B is a view showing the arrangement characteristics of liquid crystal molecules in a voltage-off state and FIG. 4C in a voltage-on state.

4A, the gate wiring 112 is formed on the first substrate 110 in the first direction, the data wiring 120 is formed in the second direction crossing the first direction, and the gate wiring 112 is formed on the first substrate 110. ) And a thin film transistor T formed at an intersection point of the data line 120 and a pixel area P connected to the thin film transistor T and defined as an intersection area of the gate line 112 and the data line 120. ) Is formed with a transparent electrode 126. The common wiring 114 is formed to be spaced apart from the gate wiring 112 in the first direction, and the reflective electrode 116 is disposed to overlap the transparent electrode 126 in an insulated state in the common wiring 114. Is formed.

In the present embodiment, a slit 124 (slit) is formed in a region of the transparent electrode 126 overlapping the reflective electrode 116.

Although not shown in the drawings, in the present invention, a plurality of holes may be formed in addition to the slit 124 at a corresponding position.

The reflective electrode 116 and the transparent electrode 126 form a pixel electrode 128, and the region of the transparent electrode 126 overlapping the reflective electrode 116 has a storage capacitance C _ST with an insulator interposed therebetween. Achieve.

Hereinafter, referring to the cross-sectional structure of the transflective liquid crystal display device including the first substrate structure according to FIG. 4A, as shown in FIGS. 4B and 4C, the first and second substrates 110 and 130 face each other at a predetermined interval. It is disposed spaced apart from each other, and has a structure in which a liquid crystal layer 150 is interposed between the first and second substrates 110 and 130. Looking at the specific stacked structure of the inner surface of the first and second substrates 110 and 130, the reflective electrode 116 is formed on the first substrate 110 and the insulating layer is formed on the entire surface of the substrate covering the reflective electrode 116. 118 is formed, and a transparent electrode 126 is formed above the insulating layer 118 and has a slit 124 exposing a portion of the reflective electrode 116.

The reflective electrode 116 is a pattern branched from the common wire 114 shown in FIG. 4A, and receives a common voltage through the common wire 114, and the transparent electrode 126 receives a pixel voltage. Accordingly, the reflective electrode 116 and the transparent electrode 126 have different voltage magnitudes. In general, the common voltage has a constant voltage magnitude by applying a DC voltage, and the pixel voltage is higher than the common voltage. The difference is that an alternating voltage is applied alternately between a voltage and a low voltage.

In FIG. 4C, dotted lines displayed in the liquid crystal layer 150 correspond to an equipotential surface (ES), and although not shown in the drawing, an electric field is formed in a direction perpendicular to the equipotential surface (ES), and the liquid crystal layer 150 The liquid crystal molecules 152 in the X) are positive liquid crystals whose long axes are arranged parallel to the electric field, and have a structure in which the long axes of the liquid crystal molecules 152 are arranged orthogonal to the equipotential surface ES in the drawing.

Including the slit 124 portion of the transparent electrode 126, the region corresponding to the reflective electrode 116 forms a reflecting portion, the region of the transparent electrode 126 non-overlapping relationship with the reflecting portion forms a transmissive portion, The reflecting portion and the transmitting portion form an opening contributing to the opening ratio.

As the reflective part including the slit 124 is omitted, the transparent electrode 126 pattern is omitted, the intensity of the electric field is weakened compared to the transmissive part by the same voltage, and thus the transmissive part and the reflective part liquid crystal molecules at the time of voltage on / off The phase difference values of are also different from each other.

That is, the transmissive part and the reflecting part including the slit 124 have different phase difference values, and the phase difference value can be adjusted by changing the formation width or the arrangement structure of the slit 124. By forming the pixel electrode 128 in a pattern structure in which the driving voltages of which the transmittances are the maximum and the minimum are the same, the luminance characteristics of the reflecting portion and the transmitting portion can be improved with the same driving voltage in the single cell gap structure.

In addition, in the present invention, the strength of the electric field can be weakened in the selected region by the configuration of an open portion such as a slit or a hole.

Meanwhile, a common electrode 132 to which the same common voltage as the reflective electrode 116 is applied is formed below the second substrate 130. Although not shown in the drawings, alignment layers are formed on the surfaces of the first and second substrates 110 and 130 in contact with the liquid crystal layer 150, respectively. Hereinafter, a cell structure including a horizontal alignment layer for horizontally arranging initial alignment of liquid crystal molecules on a substrate surface will be described in detail with reference to the accompanying drawings.

Second Embodiment

This embodiment is an embodiment presenting a specific cell structure of the transflective liquid crystal display device according to the present invention. The liquid crystal layer changes the phase difference of light by λ / 2, perpendicular to the substrate surface without twisting the liquid crystal when voltage is applied. An arrayed electrically controlled birefigence (ECB) scheme is presented as an example.

FIG. 5 is a schematic cross-sectional view of a transflective liquid crystal display device according to a second exemplary embodiment of the present invention. FIG. 5 illustrates a phase difference change of liquid crystal molecules when voltage is turned on or off based on a normally black mode.

As shown, a liquid crystal panel comprising a first and a second substrate and a liquid crystal layer interposed between the first and second substrates, first and second polarizing plates respectively disposed on both rear surfaces of the liquid crystal panel, a liquid crystal panel and a first liquid crystal panel. And first and second retardation plates disposed in sections between the two polarizing plates, respectively.

The polarization axes of the first and second polarizing plates have the same polarization axis in the 0 ° direction, and the first and second retardation plates are phase retardation plates for changing the phase difference of light by λ / 4, and the first retardation plates are 135 ° and the second. The retarders are arranged at 45 ° angles and have an angle difference orthogonal to each other at 90 °. In addition, the liquid crystal molecules in the liquid crystal layer have one phase difference of λ / 2 and an angle difference of 135 ° with the polarizing plate as an example of the precondition.

Here, the first and second retardation plates have the same retardation and have an angle difference perpendicular to each other, so that the transmissive portion has a mutually canceling effect.

Table 1 is a table showing the brightness of the screen according to the polarization state of the light passing through each cell of the liquid crystal display according to FIG. 5 and the phase difference characteristics of the liquid crystal.

As described above, in the voltage-off state, black luminance is obtained, and in the voltage-on state, the luminance is white. In the voltage-on state, the phase difference value of the transmissive liquid crystal molecules is converted from λ / 2 to 0 (zero). Since the phase difference value of the molecule has a value between 0 and λ / 2, the phase difference value is 0% of the reflectance when the phase difference value is 0 or λ / 2. However, according to the conditions of the present embodiment, the luminance characteristic of the reflector can be improved.

FIG. 6 is a schematic cross-sectional view of a transflective liquid crystal display device according to a second exemplary embodiment of the present invention. FIG. 6 illustrates a phase difference change of liquid crystal molecules when voltage is turned on or off based on a normally white mode.

As shown, the first and second substrates are disposed to be spaced apart from each other by a predetermined interval, and a liquid crystal layer is interposed between the first and second substrates, and the first and second substrates are disposed on the back of the first and second substrates. It has a structure in which a polarizing plate is located.

One example of the precondition is that the polarization axes of the first and second polarizing plates have the same polarization axis in the 0 ° direction, and the liquid crystal molecules in the liquid crystal layer have a phase difference of λ / 2.

Table 2 is a table showing the brightness of the screen according to the polarization state of the light passing through each cell of the liquid crystal display according to Figure 6 and the phase difference characteristics of the liquid crystal.

As described above, in the NW-mode semi-transmissive liquid crystal display according to the present embodiment, a compensation plate such as a separate phase difference plate may be omitted, and the phase difference value of the transmission part when the voltage is applied in the voltage-off state as in the above-described NB mode is λ. Since the phase shift value of the reflector is converted from λ / 2 to λ / 4, the luminance can be improved by matching the black / white driving voltage.

However, in the case of the NW mode, it is more difficult to set the black condition of the reflector than the NB mode, and therefore, it is preferable to apply to the structure having the smaller area of the reflector than the transmissive part.

7 is a diagram illustrating a simulation of a transflective liquid crystal display including a slit part according to the present invention, wherein a reflective electrode to which a common voltage is applied on a first substrate and a portion of the reflective electrode are exposed on the reflective electrode. A transparent electrode having a slit portion, to which the pixel voltage is applied, is formed, and a common electrode to which the same common voltage as the reflective electrode is applied is formed below the second substrate disposed to face the first substrate. When the transparent electrode forming part is defined as the first region VIIa and the slit region as the second region VIIb, the liquid crystal is formed by a vertical electric field formed between the common electrode and the transparent electrode in the first region VIIa when voltage is applied. Although the molecules are arranged vertically, in the second region VIIb, the transparent electrode does not exist on the region corresponding to the common electrode, and the common electrode and the reflective electrode to which the same common voltage is applied are located to correspond to each other. Since the equipotential surface is formed, the liquid crystal molecules are arranged horizontally in the second region VIIb, and the liquid crystal molecules are inclined at the boundary portions of the first and second regions VIIa and VIIb.

That is, in this embodiment, the reflective layer is formed of a reflective electrode to which a common voltage is applied, and the transparent electrode is formed of a pattern structure that partially exposes the reflective electrode, so that the phase difference between the reflective portion and the transparent portion can be selectively changed. The luminance can be improved by matching the black / white driving voltage of the reflector.

However, it is not limited to the said embodiment of this invention, It can implement in various changes within the range which does not deviate from the meaning of this invention.

As described above, according to the semi-transmissive liquid crystal display device according to the present invention, by forming an open portion that can weaken the electric field strength in the reflecting portion region and varying the phase difference values of the reflecting portion and the transmitting portion, the transmissive portion and the reflecting portion can be formed in the same cell gap. In this way, the process can be simplified, and the luminance can be improved by matching the black / white driving voltages of the transmissive part and the reflecting part, thereby enabling high brightness and high contrast of the product.

1 is a cross-sectional view showing a cross section of a conventional single cell gap structure semi-transmissive liquid crystal display device.

FIG. 2 is a graph illustrating voltage-luminance characteristics of a reflecting unit and a transmitting unit in a transflective liquid crystal display device; FIG.

3 is a schematic cross-sectional view of a conventional dual cell gap structure transflective liquid crystal display device.

4A to 4C are diagrams illustrating a transflective liquid crystal display device according to a first embodiment of the present invention, and FIG. 4A is a plan view, and FIGS. 4B and 4C are cross-sectional views cut along the cutting line IVa-IVa of FIG. 4A. 4B is a diagram illustrating the arrangement characteristics of liquid crystal molecules in a voltage-off state and FIG. 4C in a voltage-on state.

5 is a schematic cross-sectional view of a transflective liquid crystal display device according to a second embodiment of the present invention.

6 is a schematic cross-sectional view of a transflective liquid crystal display device according to a second embodiment of the present invention.

7 is a diagram for a simulation of a transflective liquid crystal display device including a slit portion according to the present invention;

<Description of the symbols for the main parts of the drawings>

110: first substrate 112: gate wiring

114: common wiring 116: reflective electrode

120: data wiring 124: slit

126 transparent electrode 128 pixel electrode

P: pixel area T: thin film transistor

Claims (19)

A gate wiring formed on the first substrate in a first direction; A data line formed in a second direction crossing the first direction; A common wiring formed to be spaced apart from the gate wiring in the first direction; A reflective electrode defined by the pixel area and connected to the common line and formed in the pixel area; A thin film transistor formed at an intersection point of the gate line and the data line; A transparent electrode connected to the thin film transistor in a pixel area, overlapping the reflective electrode with an insulator, and having an open part in the overlapping area; A second substrate disposed to face the first substrate; A common electrode formed on an inner surface of the second substrate; Liquid crystal layer interposed between the first and second substrates Wherein the reflective electrode forming portion forms a reflecting portion, and the transparent electrode forming portion, which is located in correspondence with the reflecting electrode, forms a transmitting portion, the thickness of the liquid crystal layer is defined as a cell gap, and the reflecting cell gap and the transmitting cell gap are the same. And the strength of the electric field in the open area when the voltage is applied is weaker than that in the other pixel areas. The method of claim 1, The open portion of the transflective liquid crystal display of any one of a slit or a hole shape. The method of claim 1, And a region in which the reflective electrode and the transparent electrode overlap with each other to form a storage capacitance. The method of claim 1, The common line and the common electrode are applied with the same common voltage, and the transparent electrode is a transflective liquid crystal display device to which a pixel voltage is applied. The method of claim 1, The transparent electrode and the reflective electrode is a transflective liquid crystal display device forming a pixel electrode. The method of claim 1, The liquid crystal molecules constituting the liquid crystal layer is a semi-transmissive liquid crystal display device comprising a positive liquid crystal in which long axes are arranged in a direction parallel to an electric field. The method of claim 1, The transflective liquid crystal display device wherein the reflecting portion and the transmitting portion have different phase difference values. The method of claim 7, wherein The transflective liquid crystal display device of which the reflecting part and the transmissive part have black / white driving voltage values of the same level. The method of claim 1, The first and second alignment layers are formed on the first and second substrate surfaces in contact with the liquid crystal layer, and the first and second alignment layers are horizontal alignment layers that make the initial arrangement of liquid crystal molecules parallel to the substrate surface. The method of claim 9, The liquid crystal display device is a semi-transmissive liquid crystal display device of the NB mode (normally black mode). The method of claim 10, On both rear surfaces of the first and second substrates, the first and second polarizing plates having the same polarization axis and the first and second polarizing plates and the second and second polarizing plates are respectively orthogonal to each other. A semi-transmissive liquid crystal display device comprising a first and a second retardation plate having an angular difference, wherein the phase difference of light is changed by λ / 4, and the liquid crystal layer is a liquid crystal layer that changes the phase difference of light by λ / 2. The method of claim 11, In the liquid crystal display device, when the voltage is applied, the phase difference value of the transmissive part is converted from λ / 2 to 0 (zero), and the phase difference value of the reflecting part has a value between 0 and λ / 2. The method of claim 11, The first and second polarizers have a 0 ° polarization axis, the first retardation plate has a 135 ° angle, the second retardation plate has a 45 ° angle, and the liquid crystal molecules have a 135 ° angle difference with the polarization axis. . The method of claim 12, The transflective liquid crystal display device of which the phase difference value of the said reflection part is (lambda) / 4. The method of claim 1, The liquid crystal display device is a transflective liquid crystal display device in a normally white mode. The method of claim 15, A semi-transmissive liquid crystal display device wherein first and second polarizing plates having the same polarization axis are positioned on both rear surfaces of the first and second substrates. The method of claim 16, The transflective liquid crystal display device of which the transmission axis of the said 1st, 2nd polarizing plate is 0 degrees. The method of claim 17, The liquid crystal display of claim 1, wherein when the voltage is applied, the phase difference value of the transmissive part is converted from λ / 2 to 0 (zero), and the phase difference value of the reflecting part has a value between 0 and λ / 2. The method of claim 18, The transflective liquid crystal display device of which the phase difference value of the said reflection part is (lambda) / 4.