KR100730396B1 - Transreflective liquid crystal display and fabricating method the same - Google Patents

Abstract

A transflective type LCD(Liquid Crystal Display) and a method for manufacturing the same are provided to make it possible to form the same cell gap in a transmissive part and a reflective part within a pixel region, by forming the tilting angles of slit patterns of electrodes differently from each other. An LCD comprises a thin film transistor substrate(20), a color filter substrate(30), a liquid crystal layer(40) between the thin film transistor substrate and the color filter substrate, and lower and upper polarizing plates(51,52) respectively formed on outsides of the thin film transistor substrate and the color filter substrate. A pixel region is divided into a transmissive part and a reflective part. The lower and upper polarizing plates have the same polarizing axis. In the transmissive part of the pixel region, at least one of a pixel electrode(400) and a common electrode(650) has a slit pattern forming a first angle with the polarizing axis. In the reflective part of the pixel region, at least one of the pixel electrode and the common electrode has a slit pattern forming a second angle forming a second angle with the polarizing axis, wherein the second angle is different from the first angle.

Description

Transflective liquid crystal display device and method for manufacturing the same {TRANSREFLECTIVE LIQUID CRYSTAL DISPLAY AND FABRICATING METHOD THE SAME}

1 is a view showing a vertically aligned vertical liquid crystal display device of normally black according to the first embodiment of the present invention.

FIG. 2 is a view showing one pixel area of a normally black vertical alignment liquid crystal display device according to a first embodiment of the present invention.

3 is a cross-sectional view taken along line III-III 'of FIG. 2;

FIG. 4 is a view showing reflection characteristics according to reflecting electrode angles in a vertically aligned liquid crystal display device of normally black according to the first embodiment of the present invention.

FIG. 5 is a view showing transmission characteristics according to a transmission electrode angle in a vertically aligned liquid crystal display device of normally black according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating reflection and transmission characteristics according to voltage application in a normally black vertical alignment liquid crystal display device according to a first embodiment of the present invention.

FIG. 7 is a view illustrating reflection and transmission characteristics according to angles of a reflection electrode and a transmission electrode in a vertically aligned liquid crystal display of normally black according to the first embodiment of the present invention.

8A to 8F are views illustrating a manufacturing process of a normally black vertically oriented thin film transistor substrate according to the first embodiment of the present invention.

9 is a view showing a vertically aligned vertical liquid crystal display device of normally white according to the second embodiment of the present invention.

FIG. 10 is a view showing reflection and transmission characteristics according to voltage application in a normally white vertical alignment liquid crystal display according to a second exemplary embodiment of the present invention.

11 is a view showing a normally black fringe field type liquid crystal display device according to a third embodiment of the present invention.

12 is a schematic diagram of electrodes of a thin film transistor substrate of a normally black fringe field type liquid crystal display device according to a third embodiment of the present invention;

13 is a view showing a normally white fringe field type liquid crystal display device according to a fourth embodiment of the present invention.

<Code Description of Main Parts of Drawing>

10 liquid crystal display device 20 thin film transistor substrate

30 color filter substrate 40 liquid crystal

51: lower polarizing plate 52: upper polarizing plate

61: first phase plate 62: second phase plate

100: insulated substrate 150: gate line

160: gate electrode 200: gate insulating film

250: active layer 260: ohmic contact layer

300: data line 310: source electrode

320: drain electrode 350: organic insulating film

360: contact hole 400: pixel electrode

410: transmission electrode 412, 652: slit pattern

420: reflective electrode 500: black matrix

550 color filter 600 overcoat layer

650 common electrode

The present invention relates to a transflective liquid crystal display device and a manufacturing method thereof, and more particularly, to a transflective liquid crystal display device having the same cell gap and a method of manufacturing the same.

In general, a liquid crystal display device arranges two substrates on which the field generating electrodes are formed so that the surfaces on which the two electrodes are formed face each other, injects a liquid crystal between the two substrates, and then applies a voltage to the two electrodes. By moving the liquid crystal by the, it is a device for expressing the image by adjusting the light transmittance that varies accordingly.

However, the liquid crystal display does not emit light by itself and thus requires a separate light source. The liquid crystal display may be classified into a transmission type and a reflection type according to a light source to be used.

The transmissive liquid crystal display is a form in which light emitted from a backlight, which is a rear light source attached to the rear side of the liquid crystal display panel, is incident on the liquid crystal to display a color by adjusting the amount of light according to the arrangement of the liquid crystal. The light transmittance is adjusted according to the arrangement of liquid crystals by reflecting external natural or artificial light.

The transmissive liquid crystal display uses a rear light source to produce bright images even in a dark environment. However, the transmissive liquid crystal display has a drawback in that it consumes a lot of power. On the other hand, the reflective liquid crystal display has a structure that depends on external natural light or artificial light sources. As a result, although the power consumption is smaller than that of the transmissive liquid crystal display, it cannot be used in a dark place.

Accordingly, a semi-transmissive liquid crystal display device, which is a liquid crystal display device that combines reflection and transmission, has been proposed as a device capable of appropriately selecting and using two modes according to a necessary situation.

Such transflective liquid crystal displays generally have display characteristics as a principle of compensating gradation mismatches due to differences in optical paths in reflective and transmissive regions by varying cell gaps between the two regions.

However, if the cell gaps of the reflective and transmissive regions are formed differently, the process becomes complicated, and light leakage occurs due to undesired liquid crystal alignment at the interface where the step is generated, thereby degrading display quality.

In addition, since the display characteristics are different when the same voltage is applied to the reflective and transmissive regions due to the difference in cell gaps, the driving circuits of the reflective and transmissive regions must be formed differently in order to uniformize the characteristics when the voltage is applied. Problem occurs.

An object of the present invention is to provide a transflective liquid crystal display device having the same cell gap and a method of manufacturing the same.

In order to achieve the above object, the present invention includes a thin film transistor substrate and a color filter substrate, a liquid crystal therebetween, and a lower and upper polarizing plate formed outside the thin film transistor substrate and the color filter substrate. In the semi-transmissive liquid crystal display device, the polarization axes of the lower and upper polarizing plates are the same, and at least one of the pixel electrode and the common electrode of the transmission region has an angle of θt with respect to the polarization axis, At least one of the pixel electrode and the common electrode has an angle of θr with respect to the polarization axis, and θt and Θr are different angles.

The value of Δnd of the liquid crystal may have a value of λ / 2.

Further, further comprising a first or second phase plate for changing the phase of the light, Δnd of the first or second phase plate has a value of λ / 4, the first phase plate is formed on the thin film transistor substrate The second phase plate may be formed between the thin film transistor substrate and the lower polarizer plate.

The phase axes of the first and second phase plates may have an angle of 45 degrees with respect to the polarization axis.

The phase axis of the first phase plate may be the same as the polarization axis.

The pixel electrode of the transmissive region may be a transmissive electrode, the pixel electrode of the reflective region may be a reflective electrode, and the liquid crystal mode may be vertically aligned.

The common electrode of the transmissive region may be a transparent common electrode, the common electrode of the reflective region may be a reflective common electrode, and the liquid crystal mode may be a fringe field type.

The pixel electrode and the common electrode may include at least one of a slit pattern and a protrusion pattern forming a domain of the liquid crystal.

In addition, the dielectric constant of the liquid crystal may have a positive or negative value.

The cell gap of the transmission area and the cell gap of the reflection area may be the same.

At least one of the electrode patterns of the pixel electrode and the common electrode may be any one of a chevron electrode pattern, a stripe electrode pattern, and a cross electrode pattern.

In order to achieve the above object, the present invention provides a method of manufacturing a semi-transmissive liquid crystal display device, which divides a pixel region into a transmissive region and a reflective region, wherein the pixel electrode of the transmissive region is formed on a polarization axis of a polarizing plate for polarizing light to a polarization axis. The method of manufacturing a transflective liquid crystal display device having an angle of Θ t with respect to the pixel electrode of the reflective region having an angle of θ r with respect to the polarization axis, and forming the Θ t and the Θ r differently. to provide.

The method may further include forming a phase plate for changing the phase of the light.

In addition, the forming of the phase plate may be a step of forming the phase axis of the phase plate to form an angle of 0 degrees or 45 degrees with respect to the polarization axis.

The method may further include forming a common electrode to which a common voltage is applied to form an electric field with the pixel electrode.

The method may include forming at least one of the pixel electrode and the common electrode as any one of a chevron electrode pattern, a stripe electrode pattern, and a cross electrode pattern.

The method may include forming a slit pattern or a projection pattern on at least one of the pixel electrode and the common electrode.

Next, a preferred embodiment of the present invention will be described with reference to the drawings.

1 is a view showing a vertically aligned vertical liquid crystal display device of normally black according to a first embodiment of the present invention.

The vertically-aligned liquid crystal display device 10 of normally black is divided into a transmissive region through which the back light is transmitted and a reflective region through which external light is reflected, and the thin film transistor substrate 20 and the color filter substrate 30 are provided. And the liquid crystal 40 therebetween.

The thin film transistor substrate 20 includes a pixel electrode 400 for applying a pixel voltage to the liquid crystal 40 on the insulating substrate 100 and a first phase plate 61 for changing the phase of light.

The pixel electrode 400 includes a transmission electrode formed in the transmission region and a reflection electrode formed in the reflection region. The transmissive electrode and the reflective electrode have angles of θt and θr with respect to the polarization axes of the lower and upper polarizing plates 51 and 52, respectively, and the angles of θt and θr are formed differently.

The first phase plate 61 is formed on the pixel electrode 400 and its phase axis has an angle of 45 degrees with respect to the polarization axes of the lower and upper polarizing plates 51 and 52. Δnd of the first phase plate 61 has a value of λ / 4.

The color filter substrate 30 includes a common electrode 650 to apply a common voltage to the liquid crystal 40 under the insulating substrate 100.

The common electrode 650 in the transmissive region and the common electrode 650 in the reflective region have angles of θt and θr with respect to the polarization axes of the lower and upper polarizing plates 51 and 52, respectively, and the angles of θt and θr are formed differently. . Here, θt, which is an angle between the common electrode 650 of the transmission region and the polarization axes of the lower and upper polarizing plates 51 and 52, and θt, which is an angle between the polarization axes of the transmission electrode and the lower and upper polarizing plates 51 and 52, are the same. . Further, θr, which is an angle formed between the common electrode 650 of the reflective region and the polarization axes of the lower and upper polarizing plates 51 and 52, and θr, which is an angle formed by the polarization axes of the reflective electrode and the lower and upper polarizing plates 51 and 52, are the same. .

The liquid crystal 40 is made of a material having dielectric anisotropy and is rotated by the difference between the pixel voltage and the common voltage to adjust the light transmittance. The liquid crystal 40 has negative dielectric anisotropy and is vertically oriented. Alternatively, the liquid crystal 40 may have positive dielectric anisotropy. The liquid crystal 40 has a Δnd of λ / 2 when a voltage is applied. In addition, the cell gap dt of the transmission region where the liquid crystal 40 is formed and the cell gap dr of the reflection region are the same.

Meanwhile, the normally black vertical alignment liquid crystal display device 10 further includes a second phase plate 62 for changing the phase of light and lower and upper polarizers 51 and 52 for polarizing the light in the polarization axis direction. have.

The second phase plate 62 is formed under the insulating substrate 100 of the thin film transistor substrate 20, and the phase axis is the same as the phase axis of the first phase plate 61. That is, the phase axis of the second phase plate 62 has an angle of 45 degrees with respect to the polarization axes of the lower and upper polarizing plates 51 and 52. Δnd of the second phase plate 62 has the same value of λ / 4 as Δnd of the first phase plate 61.

The lower polarizing plate 51 is formed under the second phase plate 62 and polarizes the back light in the polarization axis direction. The upper polarizing plate 52 is formed on the insulating substrate 100 of the color filter substrate 30 and polarizes the light passing through the liquid crystal 40 in the polarization axis direction or polarizes the incident external light in the polarization axis direction. In addition, the polarization axes of the lower and upper polarizing plates 51 and 52 have the same direction.

On the other hand, in the initial state where no voltage is applied, the back light passes once through the first and second phase plates 61 and 62 having the value of Δnd λ / 4, and the external light passes through the first phase plate 61. Since it passes twice, normally black is implemented.

FIG. 2 is a view showing one pixel area of a normally black vertical alignment liquid crystal display device according to a first embodiment of the present invention, and FIG. 3 is a cross-sectional view taken along line III-III 'of FIG.

2 and 3, one pixel area of a normally black vertical alignment liquid crystal display device 10 includes a thin film transistor substrate 20, a color filter substrate 30, and a liquid crystal 40 therebetween. do.

The thin film transistor substrate 20 includes a thin film transistor 70 connected to the gate line 150 and a data line 300 and a pixel electrode 400 connected to the drain electrode 320 of the thin film transistor 70. The first phase plate 61 which changes a phase is included.

The thin film transistor 70 applies the data voltage of the data line 300 to the pixel electrode 400 in response to the gate voltage of the gate line 150. To this end, the thin film transistor 70 includes a gate electrode 160 connected to the gate line 150, a source electrode 310 connected to the data line 300, and a drain electrode 320 connected to the pixel electrode 400. And an ohmic contact layer 260 and an active layer 250 formed between the gate insulating layer 200, the data line 300, and the source electrode 310 and the drain electrode 320.

The gate electrode 160 protrudes perpendicularly to the gate line 150 and receives a gate voltage of the gate line 150. The source electrode 310 protrudes perpendicularly to the data line 300 and receives a data voltage of the data line 300. The drain electrode 320 is formed to face the source electrode 310 based on the gate electrode 160, and receives a data voltage from the source electrode 310 through a channel of the thin film transistor 70.

The ohmic contact layer 260 has the same pattern as the data line 300, the source electrode 310, and the drain electrode 320, and the data line 300, the source electrode 310, the drain electrode 320, and the active layer 250. ) And decreases the off current of the thin film transistor 70. The active layer 250 overlaps the gate electrode 160 with the gate insulating layer 200 interposed therebetween to form a channel of the thin film transistor 70.

The pixel electrode 400 is formed in a pixel region defined by the intersection of the gate line 150 and the data line 300, and includes a reflective electrode 420 and a transmission electrode 410.

The reflective electrode 420 is formed on the transmission electrode 410 in contact with the transmission electrode 410. Since the reflective electrode 420 is an opaque metal, the region where the reflective electrode 420 is formed becomes a reflective region, and the remaining regions become transmissive regions. Meanwhile, a slit pattern or a protrusion pattern may be formed on the reflective electrode 420 as a domain restricting means.

The transmissive electrode 410 is formed in the transmissive region and the reflective region on the organic insulating layer 350 and is connected to the drain electrode 320 through the contact hole 360 formed in the organic insulating layer 350 to receive the pixel voltage.

The slit pattern 412 is formed in the transmissive electrode 410 as a domain restricting means. Alternatively, the projection pattern may be formed as domain regulating means. Due to the slit pattern 412, the pattern of the pixel electrode 400 has a chevron pattern. Here, the pattern of the pixel electrode 400 may have a stripe or cross pattern.

The slit pattern 412 of the transmissive electrode 410 and the slit pattern 652 of the common electrode 650 are formed in the same pattern as the slit pattern 412 of the transmissive electrode 410. It is formed to have a domain, thereby securing a wide viewing angle.

In particular, the angle θt of the transmissive electrode 410 of the transmissive region (or the slit pattern 412 of the transmissive electrode 410 of the transmissive region) and the polarization axis of the lower and upper polarizing plates 51 and 52 and the reflective region The angle θr of the reflective electrode 420 (or the slit pattern 412 of the transmissive electrode 410 in the reflective region) with the polarization axes of the lower and upper polarizing plates 51 and 52 is different.

As shown in FIG. 4, the angle θr of the reflective electrode 420 of the reflective region (or the slit pattern 412 of the transmissive electrode 410 of the reflective region) forms with the lower and upper polarizing plates 51 and 52. Depending on the reflection characteristics.

More specifically, when the reflective electrode 420 of the reflective region (or the slit pattern 412 of the transmissive electrode 410 of the reflective region) forms the lower and upper polarizing plates 51 and 52, the angle θr is 0 degrees. The reflectance becomes zero even when a voltage is applied. However, when the angle θr of the reflective electrode 420 of the reflective region (or the slit pattern 412 of the transmissive electrode 410 of the reflective region) with the lower and upper polarizing plates 51 and 52 increases, the reflectance increases. The reflectance is 22.5 degrees when the reflection electrode 420 of the reflection region (or the slit pattern 412 of the transmission electrode 410 of the reflection region) forms the lower and upper polarizing plates 51 and 52 at 22.5 degrees. It shows the best characteristics.

On the other hand, it is applied when the angle θr of the reflective electrode 420 of the reflective region (or the slit pattern 412 of the transmissive electrode 410 of the reflective region) with the lower and upper polarizing plates 51 and 52 is 22.5 degrees or more. Reflectance begins to decrease between 2V and 3V.

In addition, as shown in FIG. 5, the angle of the transmission electrode 410 in the transmission region (or the slit pattern 412 of the transmission electrode 410 in the transmission region) with the lower and upper polarizing plates 51 and 52 ( As θ t) approaches 45 degrees, the transmittance increases. That is, the transmittance is 45 degrees when the transmission electrode 410 of the transmission region (or the slit pattern 412 of the transmission electrode 410 of the transmission region) forms the lower and upper polarizing plates 51 and 52 at 45 degrees. It is the maximum.

As shown in Fig. 6, since the reflection area and the transmission area have the same optical structure, they have the same threshold voltage and the maximum white voltage is also secured at the same driving voltage. However, the transmission and reflection characteristics of the intermediate gradation region appear slightly different. As shown in FIG. 7, the slit pattern 412 of the reflection electrode 420 of the reflection region (or the transmission electrode 410 of the reflection region) is shown. Can be solved by adjusting the angle θr of the lower and upper polarizing plates 51 and 52.

The first phase plate 61 is formed on the entire surface of the organic insulating film 350 and the pixel electrode 400. The phase axis of the first phase plate 61 has an angle of 45 degrees with respect to the polarization axes of the lower and upper polarizing plates 51 and 52, and Δnd has a value of λ / 4.

The color filter substrate 30 is formed on the black matrix 500 for blocking external light and preventing the light leakage current of the thin film transistor 70, the color filter 550 for implementing the color of the display, and the color filter 550. An overcoat layer 600 for flattening the surface and a common electrode 650 for applying a common voltage to the liquid crystal 40 are included.

The black matrix 500 is formed in a matrix form under the color filter substrate 30. The color filter 550 includes red, green, and blue pigments that implement color, and is formed in each matrix partitioned by the black matrix 500.

The overcoat layer 600 is formed of a transparent insulating film having photosensitivity under the color filter 550 and the black matrix 500. The common electrode 650 is formed under the overcoat layer 600, and the electrode pattern (or slit pattern 652) is the same as the pixel electrode 400 and is alternately formed with respect to the pixel electrode 400. That is, the common electrode 650 has the same slit pattern 652 as the pixel electrode 400 as a domain restricting means. Alternatively, the common electrode 650 may have a protrusion pattern as domain regulating means.

The liquid crystal 40 is rotated by the difference between the pixel voltage and the common voltage to adjust the amount of light.

One pixel area of the normally black vertical alignment liquid crystal display device 10 further includes a second phase plate 62 for changing the phase of light and lower and upper polarizers 51 and 52 for polarizing the light in the polarization axis direction. Doing.

The second phase plate 62 is formed under the insulating substrate 100 of the thin film transistor substrate 20, and the phase axis is the same as the phase axis of the first phase plate 61. That is, the phase axis of the second phase plate 62 has an angle of 45 degrees with respect to the polarization axes of the lower and upper polarizing plates 51 and 52. Δnd of the second phase plate 62 has the same value of λ / 4 as Δnd of the first phase plate 61.

The lower polarizing plate 51 is positioned below the second phase plate 62 to polarize the back light in the polarization axis direction. The upper polarizing plate 52 is formed on the insulating substrate 100 of the color filter substrate 30 and polarizes the light passing through the liquid crystal 40 in the polarization axis direction or polarizes the incident external light in the polarization axis direction. The polarization axes of the lower and upper polarizing plates 51 and 52 have the same direction.

Next, a manufacturing process of a normally black vertically oriented thin film transistor substrate according to the first embodiment of the present invention will be described with reference to FIGS. 8A to 8F.

Referring to FIG. 8A, a gate pattern including the gate line 150 and the gate electrode 160 is formed on the insulating substrate 100 through a first mask process.

More specifically, a gate metal layer such as Cr or Cr alloy, Al or Al alloy, Mo or Mo alloy is deposited on the insulating substrate 100 such as glass or plastic by sputtering or the like. Next, the gate metal layer is patterned through a photolithography process using a first mask to form a gate pattern in a single layer or multiple layers.

Referring to FIG. 8B, a data pattern including the gate insulating layer 200, the active layer 250, the ohmic contact layer 260, the data line 300, the source electrode 310, and the drain electrode 320 may be a second pattern. It is formed through a mask process.

More specifically, SiNx or SiOx, a-Si, n-doped a-Si is continuously deposited on the gate pattern by a method such as Plasma Enhanced Chemical Vapor Deposition (PECVD). Next, a data metal layer such as Cr or Cr alloy, Al or Al alloy, Mo or Mo alloy is deposited by sputtering. Next, the data metal layer is patterned through a photolithography process using a second mask to form a data pattern in a single layer or multiple layers.

Next, a channel of the thin film transistor 70 is formed through an ashing process and etching of the channel part. In this case, the gate insulating layer 200 may be slightly overetched. In addition, instead of using one photomask, two photomasks may be used to perform the second mask process.

Referring to FIG. 8C, an organic insulating film 350 is formed on the data pattern and the gate insulating film 200 through a third mask process.

More specifically, the organic insulating film 350 is deposited on the data pattern and the gate insulating film 200 by a spin coating method. As the organic insulating film 350, a photosensitive organic material such as acryl is used. Next, the contact hole 360 and the organic insulating film 350 are formed through a photolithography process using a third mask. Alternatively, the partial exposure mask may be used as the third mask so that the surface of the organic protective film 350 has an embossing pattern. Here, the partial exposure mask is a halftone mask or a diffraction exposure mask.

Referring to FIG. 8D, a transparent conductive pattern including a transmission electrode 410 is formed on the organic insulating layer 350 through a fourth mask process.

More specifically, a transparent conductive metal layer such as ITO or IZO is deposited on the organic insulating film 350. Next, a transparent conductive metal layer is patterned through a photolithography process using a fourth mask to form a transparent conductive pattern. In this case, the transmission electrode 410 is formed to have a slit pattern 412. Alternatively, the transmission electrode 410 may have a projection pattern.

In addition, the transmission electrode 410 (or the slit pattern 412) has a different angle between the polarization axes of the lower and upper polarizing plates 51 and 52 in the transmission region and the reflection region. That is, the angle θt and the reflection region of the transmission electrode 410 (or the slit pattern 412 of the transmission electrode 410 of the transmission region) formed in the transmission region and the polarization axes of the lower and upper polarizing plates 51 and 52. The angle θr of the transmissive electrode 410 (or the slit pattern 412 of the transmissive electrode 410 in the reflecting region) with the polarization axes of the lower and upper polarizing plates 51 and 52 is formed differently.

Referring to FIG. 8E, the reflective electrode 420 is formed on the transparent conductive pattern through a fifth mask process.

More specifically, a reflective electrode metal layer such as Al or Al alloy is deposited on the transparent conductive pattern by sputtering or the like. Next, the reflective electrode metal layer is patterned through a photolithography process using a fifth mask to form the reflective electrode in a single layer or multiple layers. In this case, the reflective electrode 420 is formed to be connected to the transparent electrode 410. In addition, the reflective electrode 420 may have a slit pattern or a protrusion pattern.

Referring to FIG. 8F, a first phase plate 61 is formed on the organic insulating film 350, the transparent conductive pattern, and the reflective electrode 420.

More specifically, the first phase plate 61 is formed by depositing a transparent organic or inorganic material having Δnd λ / 4 on the organic insulating film 350, the transparent conductive pattern, and the reflective electrode 420. At this time, the angle formed by the phase axis of the first phase plate 61 and the polarization axes of the lower and upper polarizing plates 51 and 52 is 45 degrees. Alternatively, an angle between the phase axis of the first phase plate 61 and the polarization axes of the lower and upper polarizers 51 and 52 may be 0 degrees.

Next, a normal white vertical alignment liquid crystal display device according to a second embodiment of the present invention will be described with reference to FIG.

Referring to FIG. 9, the normally white vertically aligned liquid crystal display 10 removes the second phase plate 62 from the normally black vertically aligned liquid crystal display 10 of FIG. 1. The phase axis of the phase plate 61 may be formed to be the same as the polarization axes of the lower and upper polarizing plates 51 and 52. Other components are the same as those in the first embodiment and are omitted.

As shown in FIG. 10, the angle at which the reflective electrode 420 of the reflective region (or the slit pattern 412 of the transmissive electrode 410 of the reflective region) forms the polarization axis of the lower and upper polarizing plates 51 and 52 ( (theta) r is 22.5 degrees, and the angle (theta) t which the transmission electrode 410 (or the transmission electrode 410 slit pattern 412 of a transmission region) makes with the polarization axis of the lower and upper polarizing plates 51 and 52 At 45 degrees, the reflection and transmission characteristics according to the applied voltage become similar.

Next, a normally black fringe field type liquid crystal display device according to a third embodiment of the present invention will be described with reference to FIGS. 11 and 12.

Referring to FIG. 11, the normally black fringe field type liquid crystal display device 10 according to the third embodiment of the present invention is divided into a transmissive region through which back light is transmitted and a reflective region through which external light is reflected, and a thin film transistor. A substrate 20 and a color filter substrate 30 and a liquid crystal 40 therebetween are provided.

The thin film transistor substrate 20 changes the phase of light and the pixel electrode 400 for applying a pixel voltage to the liquid crystal 40 and the common electrode 650 for applying a common voltage to the liquid crystal 40 on the insulating substrate 100. The first phase plate 61 to be included.

The pixel electrode 400 is formed on the first phase plate 61, and as shown in FIGS. 11 and 12, the pixel electrode 400 and the lower and upper polarizers 51 and 52 formed in the transmission region are formed. The angle [theta] t with the polarization axis and the angle [theta] r between the polarization axes of the pixel electrode 400 formed in the reflection region and the lower and upper polarizing plates 51 and 52 are different. In this case, the pixel electrode 400 formed in the transmission region and the reflection region has a chevron structure. Alternatively, the pixel electrode 400 may have a stripe or cross structure.

The common electrode 650 includes a transparent common electrode 654 formed in the transmission region and a reflective common electrode 656 formed in the reflection region. At this time, since the reflective common electrode 656 is formed of an opaque metal, the region where the reflective common electrode 656 is formed becomes a reflective region, and the remaining regions become transmissive regions.

The first phase plate 61 is formed on the common electrode 650 and its phase axis has an angle of 45 degrees with respect to the polarization axes of the lower and upper polarizing plates 51 and 52. Δnd of the first phase plate 61 has a value of λ / 4.

The color filter substrate contains red, green, and blue pigments, thereby realizing the color of the display.

The liquid crystal 40 is made of a material having dielectric anisotropy and is rotated by the difference between the pixel voltage and the common voltage to adjust the light transmittance. The liquid crystal 40 has positive or negative dielectric anisotropy. In addition, the liquid crystal 40 has a Δnd of λ / 2 when a voltage is applied, and the cell gap dt of the transmission region and the cell gap dr of the reflection region are the same.

Meanwhile, the normally black fringe field type liquid crystal display 10 further includes a second phase plate 62 for changing the phase of light and lower and upper polarizers 51 and 52 for polarizing the light in the polarization axis direction. .

The second phase plate 62 is positioned under the insulating substrate 100 of the thin film transistor substrate 20, and its phase axis is the same as that of the first phase plate 61. That is, the phase axis of the second phase plate 62 has an angle of 45 degrees with respect to the polarization axes of the lower and upper polarizing plates 51 and 52. Δnd of the second phase plate 62 has the same value of λ / 4 as Δnd of the first phase plate 61.

The lower polarizing plate 51 is formed under the second phase plate 62 to polarize the back light in the polarization axis direction. The upper polarizing plate 52 is formed on the insulating substrate 100 of the color filter substrate to polarize the light passing through the liquid crystal 40 in the polarization axis direction or to polarize the incident external light in the polarization axis direction. In addition, the polarization axes of the lower and upper polarizing plates 51 and 52 have the same direction.

Meanwhile, in the initial state where no voltage is applied, the back light passes through the first and second phase plates 61 and 62 having the value of Δnd λ / 4, respectively, and the external light passes through the first phase plate 61. Since it passes twice, normally black is implemented.

Next, a normally white fringe field type liquid crystal display device according to a fourth embodiment of the present invention will be described with reference to FIG.

Referring to FIG. 13, the normally white fringe field type liquid crystal display 10 removes the second phase plate 62 from the normally black fringe field type liquid crystal display 10 of FIG. 11. The phase axis of the phase plate 61 may be formed to be the same as the polarization axes of the lower and upper polarizing plates 51 and 52. The other components are the same as in the third embodiment and thus will be omitted.

In the transflective liquid crystal display according to the present invention, the reflective electrode and the transmissive electrode are formed at different angles with respect to the polarization axis of the polarizer to form the same cell gap in the reflective and transmissive regions.

Due to the electrode structure, it is possible to secure the same all-optical characteristics in the reflective and transmissive regions and to operate each region using the same driving circuit.

In addition, by removing the phase plate formed outside the cell, it is possible to easily change the normally black mode to the normally white mode, and to provide a semi-transmissive liquid crystal display device applicable to both the vertical alignment type and the fringe field type.

In the detailed description of the present invention described above with reference to the preferred embodiment of the present invention, those skilled in the art or those skilled in the art having ordinary knowledge of the present invention described in the claims to be described later It will be understood that various modifications and variations can be made in the present invention without departing from the spirit and scope of the art.

Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (17)

A thin film transistor substrate, a color filter substrate formed to face the thin film transistor substrate and a liquid crystal interposed therebetween, an upper polarizing plate formed on the upper portion of the color filter substrate, and a lower portion formed under the thin film transistor substrate and having the same polarization axis as the upper polarizing plate. A semi-transmissive liquid crystal display comprising a polarizing plate and dividing a pixel region into a transmission region and a reflection region, At least one of the pixel electrode and the common electrode formed to face each other in the transmission region is inclined with the polarization axis, At least one of the pixel electrode and the common electrode formed to face each other in the reflective region is inclined with the polarization axis, And wherein the electrode inclined in the reflective region is formed at a different angle from the electrode inclined in the transmissive region. The method of claim 1, A transflective liquid crystal display device having a value of Δnd of the liquid crystal having a value of λ / 2. The method of claim 2, Further comprising a first or second phase plate for changing the phase of the light, Δnd of the first or second phase plate has a value of λ / 4, The first phase plate is formed on the pixel electrode or the common electrode of the thin film transistor substrate, The second phase plate is a transflective liquid crystal display device, characterized in that formed between the thin film transistor substrate and the lower polarizing plate. The method of claim 3, And the phase axes of the first and second phase plates have a 45 degree angle with respect to the polarization axis. The method of claim 3, The phase axis of the first phase plate is the same as the polarization axis, the transflective liquid crystal display device. The method of claim 1, The common electrode is formed on the color filter substrate, The pixel electrode is formed on the thin film transistor substrate, The pixel electrode of the transmission region is a transmission electrode, the pixel electrode of the reflection region is a reflection electrode, And said liquid crystal is in a vertical alignment mode. The method of claim 1, The thin film transistor substrate includes a common electrode and a pixel electrode thereon, The common electrode of the transmission region is a transparent common electrode, The common electrode of the reflective region is a reflective common electrode, And the liquid crystal is a fringe field mode. The method of claim 6, At least one of the pixel electrode and the common electrode includes at least one of a slit pattern and a projection pattern forming the domain of the liquid crystal. The method of claim 1, A semi-transmissive liquid crystal display device, characterized in that the dielectric constant of the liquid crystal has a positive or negative value. The method of claim 1, The cell gap of the transmissive region and the cell gap of the reflective region are the same. The method according to any one of claims 1 to 10, And at least one of the electrode pattern of the pixel electrode and the common electrode is any one of a chevron electrode pattern, a stripe electrode pattern, and a cross electrode pattern. delete delete delete delete delete delete

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