Reflective-transmissive type liquid crystal display device and method for fabricating the same

A reflective-transmissive type liquid crystal display device and a method for fabricating the reflective-transmissive type liquid crystal display device are provided. The reflective-transmissive type liquid crystal display device includes a pixel electrode having a transparent electrode for displaying information in a dark place where light is insufficiently provided, a reflective electrode for displaying information in a place where light is sufficiently provided, and an orientation film having an orientation groove provided on an upper surface of the pixel electrode, the direction of the orientation groove being varied depending on a shape of the reflective electrode. The reflective-transmissive type liquid crystal display device prevents the generation of an afterimage, which is generated when a response speed of liquid crystal is lowered due to the impurities or ions stacked at a boundary of the reflective electrode and the transparent electrode, thereby improving quality of display.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a reflective-transmissive type liquid crystal display device and a method for fabricating the same, and more particularly to a reflective-transmissive type liquid crystal display device and a method for fabricating the same, which can prevent afterimage from generating during a display process caused by ions and impurities remained in an orientation film when forming the orientation film, thereby improving quality of display.

2. Description of the Related Art

Liquid crystal display devices may be fabricated to have a slimmer, smaller and lighter structure regardless of a screen size thereof.

Such liquid crystal display devices are remarkably different from cathode ray tube (CRT) type display devices, in which thickness, volume and weight thereof increase proportional to a size thereof.

Different from the CRT type display devices, the liquid crystal display devices may reduce thickness, volume and weight thereof by filling liquid crystal therein. The liquid crystal has a thickness of few micrometers (μm), but controls quality of light.

The liquid crystal display devices further require light to display image information, since the liquid crystal does not generate light itself, but only controls quantity of light.

The liquid crystal display devices are classified as reflective type liquid crystal display devices, transmissive type liquid crystal display devices and reflective-transmissive type liquid crystal display devices depending on kinds of light sources as used.

The reflective type liquid crystal display devices display image information using external light, such as solar light, indoor illuminating light and outdoor illuminating light. The reflective type liquid crystal display devices display the image information with low power consumption because these devices consume power only in controlling the liquid crystal.

However, the reflective type liquid crystal display devices may not display image information if the external light is not provided or insufficiently provided thereto.

The transmissive type liquid crystal display devices obtain artificial light by using, for example, a cold cathode fluorescent type lamp (CCFL), and display image information by passing the artificial light through the liquid crystal. Therefore, the transmissive type liquid crystal display devices may display image information under any environmental conditions regardless of the external light.

However, the transmissive type liquid crystal display devices display image information at high power consumption because these devices generate light by consuming electric energy even when the external light is sufficiently provided thereto.

The reflective-transmissive type liquid crystal display devices have advantages of the reflective type and transmissive type liquid crystal display devices. The reflective-transmissive type liquid crystal display devices display image information using the artificial light where the external light is not provided or insufficiently provided. In addition, the reflective-transmissive type liquid crystal display devices display image information using the external light where the external light is sufficiently provided.

Accordingly, the reflective-transmissive type liquid crystal display devices may remarkably reduce power consumption as compared with the transmissive type liquid crystal display devices, while displaying image information regardless of environmental conditions thereof.

FIG. 1is a sectional view showing a conventional reflective-transmissive type liquid crystal display device.

Referring toFIG. 1, a conventional reflective-transmissive type liquid crystal display device100includes a TFT (Thin Film Transistor) substrate10, a color filter substrate20and a liquid crystal30.

In addition, the reflective-transmissive type liquid crystal display device100includes a driving module (not shown), which generates a driving signal to control the liquid crystal30to display an image.

The TFT substrate10includes a transparent substrate11, a thin film transistor12, an organic insulation layer13, a pixel electrode14and an orientation film15.

The thin film transistor12is arranged on the transparent substrate11in a matrix configuration. The thin film transistor12includes a gate electrode12a, a channel layer12b, a source electrode12cand a drain electrode12d.

The organic insulation layer13is disposed on an upper surface of the transparent substrate11in order to insulate the thin film transistor12. The organic insulation layer13is provided with a contact hole13afor exposing the drain electrode12dof the thin film transistor12.

The pixel electrode14is disposed on an upper surface of the organic insulation layer13. The pixel electrode14includes a transparent electrode14aand a reflective electrode14b.

The transparent electrode14ais formed by patterning indium tin oxide (ITO) or indium zinc oxide (IZO), having high light transmittance and conductivity, on the organic insulation layer13.

The transparent electrode14ais connected to the drain electrode12dof the thin film transistor12through the contact hole13aof the organic insulation layer13. First light (that is generated from an under portion of the transparent substrate11) passes through the transparent electrode14a. That is, the first light passes through the transparent electrode14ato display image information when external light is not provided or insufficiently provided to the device100.

The reflective electrode14bis disposed on an upper surface of the transparent electrode14a. The reflective electrode14bincludes a metal having high light reflectivity. The reflective electrode14breflects second light having a direction opposite to a direction of the first light in order to display image information.

An opening window14cis disposed at a center of the reflective electrode14bto partially expose the transparent electrode14a, so the reflective electrode14bhas an area smaller than that of the transparent electrode14a.

The first light passes through the opening window14cto display image information in a dark place where the external light is insufficiently provided.

The orientation film15is disposed over the entire area of an upper surface of the transparent substrate11with a shallow thickness after the pixel electrode14has been formed on the transparent substrate11.

The orientation film15prevents the liquid crystal30from being randomly aligned. That is, the liquid crystal30is aligned in a predetermined pattern by the orientation film15. To this end, an orientation groove (15ainFIGS. 2 to 4) is disposed on an upper surface of the orientation film15.

The orientation groove15ais regularly disposed on the orientation film15through a rubbing process. In order to form the orientation groove15a, a rubbing fabric having piles rotates and forwardly moves while making contact with the orientation film15.

The color filter substrate20is coupled to the TFT substrate10after the orientation film15has been formed on the TFT substrate10.

The color filter substrate20includes a transparent substrate21, a color filter22, and a common electrode23. The color filter22is disposed on the transparent substrate21in opposition to the pixel electrode14disposed on the TFT substrate10.

The common electrode23is disposed on an entire surface of the color filter22such that the color filter22covers the transparent substrate21.

The liquid crystal30is interposed between the color filter substrate20and the TFT substrate10.

However, the above-mentioned conventional reflective-transmissive type liquid crystal display device100generates an afterimage during a display process, thereby deteriorating quality of image information. The afterimage is generated due to an orientation of the pixel electrode14and the orientation groove15a.

FIG. 2is a schematic view of the conventional reflective-transmissive type liquid crystal display device having an orientation groove oriented in the 1 o'clock direction,FIG. 3is a schematic view of the conventional reflective-transmissive type liquid crystal display device having an orientation groove oriented in the 11 o'clock direction, andFIG. 4is a schematic view of the conventional reflective-transmissive type liquid crystal display device having an orientation groove oriented in the 6 o'clock direction.

Referring toFIG. 2, when the orientation groove15ais oriented in the 1 o'clock direction, the liquid crystal30is stably aligned without causing any problems at the reflective electrode14bof the pixel electrode14. However, a response speed of the liquid crystal30is deteriorated at an inner part of the opening window14c, so that the afterimage is generated in the inner part of the opening window14c. InFIG. 2, an afterimage region is shown as “A”. The afterimage region A is opposite to the orientation groove15a.

Referring toFIG. 3, when the orientation groove15ais oriented in the 11 o'clock direction, the liquid crystal30is stably aligned without causing any problems at the reflective electrode14bof the pixel electrode14. However, the response speed of the liquid crystal30is also deteriorated at the inner part of the opening window14c, so that the afterimage is generated in the inner part of the opening window14c. InFIG. 3, the afterimage region is shown as “B”. The afterimage region B is opposite to the orientation groove15a.

Referring toFIG. 4, when the orientation groove15ais oriented in the 6 o'clock direction, the liquid crystal30is stably aligned without causing any problems at the reflective electrode14bof the pixel electrode14. However, the response speed of the liquid crystal30is also deteriorated at the inner part of the opening window14c, so that the afterimage is generated in the inner part of the opening window14c. InFIG. 4, the afterimage region is shown as “C”. The afterimage region C is opposite to the orientation groove15a.

Referring toFIGS. 2 to 4, the afterimage regions A, B and C are commonly related to a position of the opening window14cdisposed in the reflective electrode14band a rubbing direction.

When performing a rubbing process, the ions or impurities attached to a pile of a rubbing fabric are outwardly moved due to a rotation of the rubbing fabric. The ions or impurities are not discharged out of the pixel electrode14, but stacked at a boundary between the transparent electrode14aand the reflective electrode14bbecause a step portion is disposed at the boundary between the transparent electrode14aand the reflective electrode14b.

As a result, the response speed of the liquid crystal30shown inFIG. 1is deteriorated due to the impurities or ions stacked at the boundary between the transparent electrode14aand the reflective electrode14b. If the response speed of the liquid crystal30is slower than a standard speed, the afterimage is generated, thereby deteriorating quality of image information.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a reflective-transmissive type liquid crystal display device capable of preventing an afterimage from generating when a response speed of liquid crystal is deteriorated due to the impurities or ions stacked at a boundary of a reflective electrode and a transparent electrode and a rubbing manner of an orientation groove.

The present invention provides a method for fabricating a reflective-transmissive type liquid crystal display device capable of preventing an afterimage from generating when a response speed of liquid crystal is lowered due to the impurities or ions stacked at a boundary of a reflective electrode and a transparent electrode and a rubbing manner of an orientation groove.

In one aspect of the invention, there is provided a reflective-transmissive type liquid crystal display device comprising: a first substrate, including a thin film transistor disposed on a first transparent substrate, an organic insulation layer disposed on the first transparent substrate to insulate the thin film transistor, the organic insulation layer having a contact hole for exposing an output terminal of the thin film transistor, a pixel electrode having a transparent electrode connected to the output terminal of the thin film transistor through the contact hole formed on the organic insulation layer and a reflective electrode disposed on a first region of the transparent electrode, a second region of the transparent electrode being exposed without being covered by the reflective electrode, and an orientation film coated on an upper surface of the pixel electrode and having an orientation groove rubbed in a first direction, the orientation groove preventing the impurity from being stacked at a boundary between the first and second regions of the transparent electrode; a second substrate, including a color filter disposed on a second transparent substrate in opposition to the pixel electrode and a common electrode disposed on an upper surface of the color filter and facing the pixel electrode; and a liquid crystal interposed between the first and second substrates.

In another aspect, there is provided a method for fabricating a reflective-transmissive type liquid crystal display device, the method comprising: forming a thin film transistor on a first transparent substrate; depositing an organic insulation layer on the first transparent substrate to insulate the thin film transistor, the organic insulation layer having a contact hole for exposing an output terminal of the thin film transistor; forming a pixel electrode on the organic insulation layer, the pixel electrode having a transparent electrode connected to the output terminal of the thin film transistor through the contact hole and a reflective electrode formed on a first region of the transparent electrode, a second region of the transparent electrode being exposed without covering by the reflective electrode; coating an orientation film on an upper surface of the pixel electrode; rubbing the orientation film in a first direction to form an orientation groove on the orientation film, the orientation groove preventing impurity from being stacked at a boundary formed between the first and second regions of the transparent electrode; forming a color filter on a second transparent substrate in opposition to the pixel electrode; forming a common electrode formed on an upper surface of the color filter, the common electrode facing the pixel electrode; and interposing a liquid crystal between the common electrode and the pixel electrode on which the orientation film and the orientation groove are formed.

The reflective-transmissive type liquid crystal display device of the present invention may include various structures of the pixel electrode and change the rubbing direction of the orientation groove. The reflective-transmissive type liquid crystal display device may prevent afterimage from being generated due to the impurities or ions stacked at the boundary between the transparent electrode and the reflective electrode, thereby increasing display quality of image information.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 5is a sectional view of a reflective-transmissive type liquid crystal display device according to an embodiment of the present invention.

Referring toFIG. 5, a reflective-transmissive type liquid crystal display device500includes a TFT substrate200, a liquid crystal300and a color filter substrate400.

The TFT substrate200has a first transparent substrate210, a thin film transistor220, an organic insulation layer230, a pixel electrode240and an orientation film250.

FIG. 6is a sectional view showing the thin film transistor ofFIG. 5.

The thin film transistor220is arranged in the first transparent substrate210in a matrix configuration. The thin film transistor220includes an insulation layer221, a gate electrode224, a channel layer223, a source electrode227and a drain electrode229.

In order to form the thin film transistor220, the gate electrode224is firstly formed on the first transparent substrate210.

The gate electrode224is formed by patterning a gate metal through a photolithography process after depositing the gate metal, such as an aluminum alloy, on an entire surface of the first transparent substrate210.

The gate electrode224is arranged in a matrix configuration and gate electrodes belonging to the same row are connected to each other in parallel through one gate line (not shown).

The gate electrode224is insulated by means of the insulation layer221and the channel layer223is formed on an upper surface of the insulation layer221corresponding to an upper surface of the gate electrode224.

The channel layer223is formed by patterning an amorphous silicon thin film and an n+ amorphous silicon thin film using a photolithography process, which are formed on the upper surface of the insulation layer221.

Reference numeral222represents an amorphous silicon pattern and reference numeral225represents an n+ amorphous silicon pattern.

In addition, a source/drain metal thin film is deposited on an entire surface of the first transparent substrate210. The source/drain metal thin film is patterned through the photolithography process so that the source electrode227and the drain electrode229are formed on the upper surface of the n+ amorphous silicon pattern225. The source and drain electrodes227and229are insulated from each other.

A data line is formed when forming the source electrode227. The data line is connected to source electrodes belonging to the same column in parallel.

FIG. 7is a sectional view showing the organic insulation layer ofFIG. 5.

Referring toFIG. 7, the organic insulation layer230is formed on an upper surface of the first transparent substrate210in order to insulate the thin film transistor220. A contact hole232for exposing the drain electrode229of the thin film transistor220is formed in the organic insulation layer230through the photolithography process.

FIG. 8is a sectional view showing the pixel electrode ofFIG. 5.

Referring toFIG. 8, the pixel electrode240is formed on an upper surface of the organic insulation layer230. The pixel electrode240includes a transparent electrode242and a reflective electrode244.

The transparent electrode242has a rectangular shape and is formed by depositing and patterning indium tin oxide (ITO) or indium zinc oxide (IZO) having high light transmittance and conductivity, on the organic insulation layer230, through the photolithography process.

The transparent electrode242is connected to the drain electrode229of the thin film transistor220through the contact hole232of the organic insulation layer230.

First light is generated from an under portion of the first transparent substrate210and passes through the transparent electrode242to display the image information when external light is not provided or insufficiently provided.

The reflective electrode244is formed on the upper surface of the transparent electrode242. The reflective electrode244includes a metal having superior light reflectance. Second light having a direction opposite to a direction of the first light is reflected from the reflective electrode244.

FIG. 9is a schematic view showing a method for forming an orientation groove in the orientation film ofFIG. 5, according to one embodiment of the present invention.

Referring toFIG. 9, the orientation film250is formed on an entire surface of the first transparent substrate210to allow the pixel electrode240to cover the organic insulation layer230.

The orientation film250prevents the liquid crystal300from being randomly aligned. The orientation film250aligns the liquid crystal300in a predetermined pattern. To this end, an orientation groove252is formed on the orientation film250.

Since the orientation film250has a thin thickness, it has the profile same to those of the transparent electrode242and the reflective electrode244. Accordingly, the profile of the orientation film250varies at a boundary region (shown inFIG. 9as a circle “D”) between the transparent electrode242and the reflective electrode244.

The orientation film250having the profile corresponding to the profiles of the transparent and reflective electrodes242and244is formed with the orientation groove252, which is regularly aligned through a rubbing process.

In order to form the orientation groove252, as shown inFIG. 9, piles254of a rubbing fabric255wound around an orientation roller257rotate and forwardly move while making contact with the orientation film250.

FIG. 10is a plan view showing a rubbing direction of the orientation groove disposed on a pixel electrode ofFIG. 5, according to one embodiment of the present invention.

Referring toFIG. 10, the reflective electrode244formed on the upper surface of the transparent electrode242has an area smaller than that of the transparent electrode242. The reflective electrode244having the smaller area is formed such that a first boundary244ais formed between the reflective electrode244and the transparent electrode242. The first boundary244amay have a linear shape in a layout of the pixel electrode240.

As shown inFIG. 10, a first region (shown inFIG. 10as hatching lines) of the transparent electrode242, on which the reflective electrode244is disposed, meets with a second region of the transparent electrode242, which is not covered by the reflective electrode244, at the first boundary244a.

The rubbing direction of the orientation groove252in the pixel electrode240is very important. If the orientation groove252is improperly oriented, the ions and impurities attached to the piles254remain in the first boundary244adisposed between the reflective electrode244and the transparent electrode242having different profiles from each other.

Due to the ions and impurities remained in the first boundary244a, a response speed of the liquid crystal300is lowered as compared with a required response speed of the liquid crystal300. If the response speed of the liquid crystal300is lower than the required response speed, an afterimage is generated, thereby affecting a bad influence on image information to be displayed.

In order to prevent the afterimage caused by the rubbing direction of the orientation groove252, as shown inFIG. 10, the piles254of the rubbing fabric255(inFIG. 9) move from the reflective electrode244towards the transparent electrode242.

Since the transparent electrode242is rubbed after the reflective electrode244has been rubbed, the ions and impurities causing the afterimage may be reduced at the first boundary244adisposed between the reflective electrode244and the transparent electrode242.

The rubbing direction of the orientation groove252may be variously selected to prevent the afterimage from being generated.

Referring toFIG. 10, in order to prevent the afterimage from being generated at the first boundary244adisposed between the reflective electrode244and the transparent electrode242, the rubbing direction is formed from the 12 o'clock direction to the 6 o'clock direction, from the 12 o'clock direction to the 9 o'clock direction, or from the 12 o'clock direction to the 3 o'clock direction.

In addition, it is also possible to form the rubbing direction from the 3 o'clock direction to the 9 o'clock direction or from the 9 o'clock direction to the 3 o'clock direction in parallel to the first boundary244ato prevent the afterimage from being generated at the first boundary244adisposed between the reflective electrode244and the transparent electrode242.

If the rubbing process is carried out from the 6 o'clock direction to the 12, 9 or 3 o'clock direction, the rubbing direction faces the first boundary244adisposed between the reflective electrode244and the transparent electrode242, so that ions and impurities may be stacked at the first boundary244a.

FIG. 11is a sectional view showing a pixel electrode according to another embodiment of the present invention. In the following description, parts different from those of the embodiment shown inFIGS. 5 to 10are only described and the same parts described in the embodiment will be omitted to avoid a redundancy.

Referring toFIG. 11, the limitation for the rubbing direction may be solved by forming a slope surface244bat a sidewall of the reflective electrode244corresponding to the first boundary244adisposed between the first and second regions.

FIG. 12is a plan view showing a rubbing direction of an orientation groove disposed on a pixel electrode ofFIG. 5, according to another embodiment of the present invention.FIG. 12shows a method for varying the rubbing characteristic of the orientation groove by changing a shape of the reflective electrode of the pixel electrode ofFIG. 5.

Referring toFIG. 12, the reflective electrode244disposed on the upper surface of the transparent electrode242has an area smaller than an area of the transparent electrode242.

The orientation film250is formed over the entire area of the upper surface of the first transparent substrate210such that the pixel electrode240disposed on the organic insulation layer230is covered by the orientation film250.

The orientation film250prevents the liquid crystal300from being randomly aligned on the upper surface of the pixel electrode240. The liquid crystal300is aligned in a predetermined pattern by the orientation film250. To this end, the orientation groove252is formed in the orientation film250.

Since the orientation film250has a thin thickness, it has the profile same to those of the transparent electrode242and the reflective electrode244. Accordingly, the profile of the orientation film250varies at a second boundary244cdisposed between the transparent electrode242and the reflective electrode244.

The orientation film250having the various profiles corresponding to the profiles of the transparent electrode242and the reflective electrode244is formed with the orientation groove252, which is regularly aligned through a rubbing process.

The rubbing direction of the orientation groove252is very important. If the orientation groove252is improperly oriented, the ions and impurities attached to the rubbing fabric255remain in the second boundary244cof the orientation film250.

Due to the ions and impurities remained in the second boundary244cof the orientation film250, a response speed of the liquid crystal300is lowered as compared with a required response speed of the liquid crystal300. If the response speed of the liquid crystal300is lower than the required response speed, an afterimage is generated, thereby affecting a bad influence on image information to be displayed.

According to the present embodiment, in order to prevent the afterimage caused by the rubbing direction of the orientation groove252, the piles254of the rubbing fabric255(inFIG. 9) are forwarded towards a part of the transparent electrode242, which is exposed without being covered by the reflective electrode244as shown inFIG. 12.

When viewed from a top, the reflective electrode244is disposed on a first region (shown inFIG. 12as hatching lines) of the transparent electrode242, and thus a second region of the transparent electrode242is exposed without being covered by the reflective electrode244.

The second region includes the second boundary244cfor exposing two edges242aand242bof the transparent electrode242. The edges242aand242bexposed by the second boundary244care connected to each other. The second boundary244chas an L-shape to expose the two edges242aand242bof the transparent electrode242. Accordingly, the first region on which the reflective electrode244is formed also has the L-shape.

Since the transparent electrode242is sequentially rubbed after the reflective electrode244having the L-shape has been rubbed, the afterimage affecting a bad influence on image information to be displayed may be reduced.

The rubbing direction of the orientation groove252for preventing the afterimage from generating at the second boundary244cdisposed between the reflective electrode244and the transparent electrode242may be variously selected.

Referring toFIG. 12, the rubbing direction may be formed in the 2 o'clock direction, from the 6 o'clock direction to the 3 o'clock direction, from the 6 o'clock direction to the 12 o'clock direction, or from the 9 o'clock direction to the 3 o'clock direction in order to prevent the afterimage from being generated at the second boundary244c.

If the rubbing process is carried out from the 12 o'clock direction to the 6 o'clock direction or from the 3 o'clock direction to the 9 o'clock direction, ions and impurities may be stacked in the rubbing direction and at the second boundary244cdisposed between the reflective electrode244and the transparent electrode242.

FIG. 13is a plan view showing a rubbing direction of an orientation groove disposed on a pixel electrode ofFIG. 11, according to another embodiment of the present invention.FIG. 13shows a method for varying the rubbing characteristic of the orientation groove by changing a shape of the reflective electrode of the pixel electrode ofFIG. 11.

Referring toFIG. 13, the slope surface244bis formed at the sidewall of the reflective electrode244facing the second boundary244cdisposed between the first and second regions of the transparent electrode242in order to prevent ions and impurities from remaining in the second boundary244c. The limitation of rubbing directions may be reduced by means of the slope surface244bformed at the sidewall of the reflective electrode244.

FIG. 14is a plan view showing a rubbing direction of an orientation groove disposed on a pixel electrode ofFIG. 5, according to another embodiment of the present invention.FIG. 14shows a method for varying the rubbing characteristic of the orientation groove by changing a shape of the reflective electrode of the pixel electrode ofFIG. 5.

Referring toFIG. 14, the reflective electrode244disposed on the upper surface of the transparent electrode242has an area smaller than an area of the transparent electrode242.

A region of the transparent electrode242occupied by the reflective electrode244is defined as a first region (shown inFIG. 14as hatching lines), and a region of the transparent electrode242, which is not covered by the reflective electrode244, is defined as a second region as shown inFIG. 14. One edge242cof the transparent electrode242is exposed through a part of the second region. Accordingly, the first region has a U-shape and the reflective electrode244also has a U-shape.

Reference numeral244drepresents a third boundary disposed between the first and second regions of the transparent electrode242. The third boundary244dhas the U-shaped configuration.

The orientation film250is formed on a part of the organic insulation layer230, which is not covered by the pixel electrode240, and on the upper surface of the pixel electrode240.

The orientation film250prevents the liquid crystal300from being randomly aligned on the upper surface of the pixel electrode240. The liquid crystal300is aligned in a predetermined pattern by the orientation film250. To this end, the orientation groove252is formed in the orientation film250.

Since the orientation film250has a thin thickness, it has the profile same to profiles of the transparent electrode242and the reflective electrode244. Accordingly, the profile of the orientation film250varies at the third boundary244ddisposed between the transparent electrode242and the reflective electrode244.

The orientation film250having the profile varied corresponding to the profiles of the transparent electrode242and the reflective electrode244is formed with the orientation groove252, which is regularly aligned through a rubbing process.

In order to form the orientation groove252, the rubbing fabric255having the piles254(inFIG. 9) rotates and moves forwards while making contact with the orientation film250. The rubbing direction of the orientation groove252is very important. If the orientation groove252is improperly oriented, the ions and impurities attached to the rubbing fabric255remain in the third boundary244dbetween the transparent electrode242and the reflective electrode244.

Due to the ions and impurities remained in the third boundary244d, a response speed of the liquid crystal300is lowered as compared with a required response speed of the liquid crystal300. If the response speed of the liquid crystal300is lower than the required response speed, an afterimage is generated, thereby affecting a bad influence on image information to be displayed.

According to the present embodiment, in order to prevent the afterimage caused by a rubbing direction, the piles254of the rubbing fabric255(inFIG. 9) firstly rub the first region of the transparent electrode242and sequentially rub the second region of the transparent electrode242, which is exposed without being covered by the reflective electrode244, as shown inFIG. 14.

Since the transparent electrode242is sequentially rubbed after the reflective electrode244has been rubbed, the afterimage generated at the third boundary244dcaused by the ions and impurities remained in the third boundary244dmay be reduced.

The rubbing direction of the orientation groove252for preventing the afterimage from being generated at the third boundary244ddisposed between the reflective electrode244and the transparent electrode242may be variously selected.

Referring toFIG. 14, the rubbing direction is formed from the 6 o'clock direction to the 12 o'clock direction to prevent the afterimage from being generated at the third boundary244ddisposed between the reflective electrode244and the transparent electrode242.

If the rubbing process is carried out from the 3 o'clock direction to the 9 o'clock direction, from the 9 o'clock direction to the 3 o'clock direction, or from the 12 o'clock direction to the 6 o'clock direction, the rubbing direction faces the third boundary244ddisposed between the reflective electrode244and the transparent electrode242, so that ions and impurities may be stacked at the third boundary244d.

FIG. 15is a plan view showing a rubbing direction of an orientation groove disposed on a pixel electrode ofFIG. 11, according to another embodiment of the present invention.FIG. 15also shows a method for varying the rubbing characteristic of the orientation groove by changing a shape of the reflective electrode of the pixel electrode ofFIG. 11.

Referring toFIG. 15, the slope surface244bis formed at the sidewall of the reflective electrode244corresponding to the third boundary244dbetween the first and second regions of the transparent electrode242, in order to prevent ions and impurities from remaining in the third boundary244d. That is, the ions and impurities scattered when performing the rubbing process may be prevented from being stacked at the third boundary244dby forming the slope surface244bat the sidewall of the reflective electrode244.

FIG. 16is a plan view showing a rubbing direction of an orientation groove disposed on a pixel electrode, according to further embodiment of the present invention.FIG. 16also provides a method for varying the rubbing characteristic of the orientation groove by changing a shape of the reflective electrode of the pixel electrode.

Referring toFIG. 16, a region of the transparent electrode242occupied by the reflective electrode244is defined as a first region, and a region of the transparent electrode242, which is not covered by the reflective electrode244, is defined as a second region.

As shown inFIG. 16, the second region is formed in the first region. The second region does not expose an edge of the transparent electrode242.

When forming the second region in the first region, impurities or ions are stacked at a fourth boundary244kbetween the first and second regions regardless of the rubbing direction, thereby generating the afterimage.

In order to prevent impurities or ions from being stacked at the fourth boundary244kbetween the reflective electrode244and the transparent electrode242, a slope portion244gis formed at the reflective electrode244adjacent to the fourth boundary244k.

The slope portion244gmay be formed in opposition to the rubbing direction or may be formed over the entire area of the fourth boundary244kas shown inFIG. 16.

The shape of the slope portion244gmay be variously selected as long as the ions and impurities introduced into the fourth boundary244kof the reflective electrode244and the transparent electrode242is discharged to an exterior through the slope portion244g.

Although not shown inFIG. 16, the transparent electrode242may include more than one the second region. In this case, the second region may include a circular shape or a rectangular shape.

Referring again toFIG. 5, the color filter substrate400is coupled to the TFT substrate200after the orientation groove252has been formed on the TFT substrate200.

The color filter substrate400includes a second transparent substrate410, a color filter420, and a common electrode430. The color filter420is formed on the second transparent substrate410in opposition to the pixel electrode240disposed on the TFT substrate200.

The color filter420includes a first tone at a region corresponding to a reflective electrode (seeFIG. 8) and a second tone at a region of a transparent electrode (seeFIG. 8) being exposed without being covered by the reflective electrode, which is different from the first tone.

The common electrode430is formed on an entire surface of the color filter420such that the color filter420covers the second transparent substrate410.

The liquid crystal300is interposed between the color filter substrate400and the TFT substrate200, thereby achieving the reflective-transmissive type liquid crystal display device500according to the present invention.

As described above, the reflective-transmissive type liquid crystal display device of the present invention may reduce the afterimage affecting a bad influence on an image to be displayed by varying the rubbing direction of the orientation groove and the shape of the reflective electrode, thereby achieving superior quality of display.

While the present invention has been described in detail with reference to the preferred embodiment thereof, it should be understood to those skilled in the art that various changes, substitutions and alterations can be made hereto without departing from the scope of the invention as defined by the appended claims.