KR100793577B1 - Transflective type liquid crystal display device - Google Patents

Abstract

A transflective type LCD is provided to uniformly and stably align liquid crystal molecules by independently forming a pixel including a transmissive area and a pixel including a reflective area. A plurality of gate lines(112b) and data lines(115c) are arranged so as to intersect each other on a first substrate. A plurality of thin film transistors(T) are connected to the gate lines and the data lines. A plurality of pixel electrodes(119) are connected to the thin film transistors and formed in pixel regions defined by the gate lines and the data lines, respectively. A reflective electrode(117) are formed so as to overlap some of the pixel electrodes. A second substrate is disposed so as to face the first substrate. A common electrode is formed on the second substrate. A liquid crystal layer is injected between the first and second substrates.

Description

Transflective type liquid crystal display device

1 is a layout for explaining a conventional transflective liquid crystal display device.

FIG. 2 is a cross-sectional view taken along the line X1-X2 of FIG. 1; FIG.

3 is a layout for explaining a transflective liquid crystal display device according to a first embodiment of the present invention.

4 is a cross-sectional view taken along the line X11-X12 of FIG.

5 is a layout diagram illustrating a transflective liquid crystal display device according to a second exemplary embodiment of the present invention.

6 is a cross-sectional view for describing a transflective liquid crystal display according to a third exemplary embodiment of the present invention.

7 is a circuit diagram for explaining a transflective liquid crystal display device according to the present invention.

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

11, 111, and 211: lower substrates 12a, 112a, and 212a: gate electrodes

12b and 112b: gate lines 13, 113 and 213: gate insulating layer

14, 114, and 214: semiconductor layers 15a, 115a, and 215a: source electrodes

15b, 115b, 215b: drain electrodes 15c, 115c, 215c: data line

16, 116, 216: insulating layer 17, 117, 217: reflective electrode

18, 118, 218: protective layer 19, 119, 219: pixel electrode

31, 131, 231: upper substrate 32, 132, 232: color filter

33, 133, 233: common electrode 40, 140, 240: liquid crystal layer

The present invention relates to a semi-transmissive liquid crystal display device, and more particularly, to a semi-transmissive liquid crystal display device in which alignment disorder of liquid crystal molecules can be prevented.

Liquid crystal displays that display images or characters using the electro-optical properties of liquid crystals are widely used due to their excellent color reproducibility, low power consumption, and thinness.

Liquid crystal display devices are generally classified into a passive matrix method and an active matrix method, and an active matrix liquid crystal display device having an excellent resolution and a video rendering ability is mainly used.

An active matrix liquid crystal display (TFT-LCD) including a thin film transistor (TFT-LCD) is one of the most commonly used flat panel display devices, and the liquid crystal is injected between two substrates. It is composed of a back light (located at the rear side) and a driver IC for driving a display panel used as a light source.

As described above, a transmissive liquid crystal display device in which light is artificially provided from the backlight and color is displayed by adjusting the amount of light according to the arrangement of the liquid crystal uses the backlight as a light source. However, due to the use of a light source, power consumption is high, and there is a disadvantage in that it is not suitable for a portable display device operated by a battery or the like.

In order to overcome the shortcomings of the transmissive type, which consumes a lot of power, a reflection type liquid crystal display device using an external natural light or an artificial light source has been proposed.However, in a dark environment, the recognition of the image is reduced due to the reduction of the amount of light. In difficult and cloudy weather, there is a restriction that external light cannot be used.

Accordingly, a transflective type liquid crystal display device having low power consumption and being usable in a dark environment by adopting only the advantages of the reflective type and the transmissive type has been proposed.

FIG. 1 is a layout for explaining a conventional transflective liquid crystal display, and FIG. 2 is a cross-sectional view taken along line X1-X2 of FIG. 1, and a pixel region includes a transmissive portion A and a reflective portion B. As shown in FIG.

1 and 2, a plurality of gate lines 12b and data lines 15c are arranged in a matrix form on the lower substrate 11, and gate lines 12b and data lines 15c intersecting with each other. The pixel is defined by A thin film transistor T for controlling a signal supplied to each pixel is formed at a portion where the gate line 12b and the data line 15c intersect, and a drain electrode 15b and an upper portion including the thin film transistor T. Connected and reflective electrodes 17 made of opaque metal are formed. In addition, a pixel electrode 19 made of a transparent electrode material is formed on the pixel area including the reflective electrode 17. The transmissive portion A is defined by the pixel electrode 19, and the reflective portion B is defined by the reflective electrode 17.

Referring to FIG. 2, a conventional transflective liquid crystal display is described in more detail as follows.

The gate electrode 12a and the gate line 12b are formed on the lower substrate 11. A semiconductor layer 14 is insulated from the gate electrode 12a by the gate insulating layer 13 on the gate electrode 12a and provides source and drain regions. The source electrode 15a and the drain electrode 15b are formed on both sides of the semiconductor layer 14, and the data line 15c is formed to cross the gate line 12a. The insulating layer 16 is formed on the entire upper surface, and the reflective electrode 17 connected to the drain electrode 15b is formed on the insulating layer 16 of the reflector B through the contact hole. A protective layer 18 made of an organic insulator is formed on the reflective electrode 17, and a pixel electrode 19 connected to the drain electrode 15b is formed on the protective layer 18 through a contact hole. At this time, the pixel electrode 19 is formed in all the pixel regions including the reflecting portion B. FIG.

The upper substrate 31 on which the color filter 32 and the common electrode 33 are formed is disposed on the lower substrate 11, and the lower substrate 11 and the upper substrate 31 are predetermined by spacers (not shown). The liquid crystal layer 40 is injected between the lower substrate 11 and the upper substrate 31 while being spaced apart from each other.

In the transflective liquid crystal display device configured as described above, light provided from a backlight (not shown) installed on the rear surface of the lower substrate 11 is incident on the liquid crystal layer 40 through the transmission portion A, and the liquid crystal layer 40 Is light modulated by the liquid crystal oriented by the voltages applied to the pixel electrode 19 and the common electrode 33, and then exits through the upper substrate 31 to display characters or images (transmission mode).

In addition, the light incident from the outside through the upper substrate 31 is reflected by the reflective electrode 17 through the liquid crystal layer 40 and then incident again into the liquid crystal layer 40. 17) and light-modulated by the liquid crystal oriented by the voltage applied to the common electrode 33, and then emitted to the outside through the upper substrate 31 to display characters or images (reflection mode).

However, in the conventional transflective liquid crystal display device configured as described above, the transmissive portion A is different from the transmissive portion A and the reflecting portion B because the distances D1 and D2 between the lower substrate 11 and the upper substrate 31 are different from each other. ) And the alignment disturbance of the liquid crystal molecules occurs in the boundary region between the reflection portion B and the reflection portion B.

SUMMARY OF THE INVENTION An object of the present invention is to provide a transflective liquid crystal display device in which the alignment disturbance of liquid crystal molecules can be prevented.

A semi-transmissive liquid crystal display device according to an aspect of the present invention for achieving the above object is a first substrate; A plurality of gate lines and data lines arranged to cross each other on the first substrate; A plurality of thin film transistors respectively connected to the plurality of gate lines and data lines; A plurality of pixel electrodes connected to the plurality of thin film transistors, respectively, and formed in pixel areas defined by the plurality of gate lines and data lines; A reflective electrode formed to overlap with some pixel electrodes of the plurality of pixel electrodes; A second substrate disposed to face the first substrate; A common electrode formed on the second substrate; And a liquid crystal layer injected between the first substrate and the second substrate.

A semi-transmissive liquid crystal display device according to another aspect of the present invention for achieving the above object is a pixel region of one of two pixels defined by two gate lines in which the reflective electrode crosses one data line and is adjacent to each other. Characterized in that formed.

A semi-transmissive liquid crystal display according to another aspect of the present invention for achieving the above object is that two pixels defined by two gate lines intersecting one data line and adjacent to each other are used as one color pixel. It features.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided to those skilled in the art to fully understand the present invention, and may be modified in various forms, and the scope of the present invention is limited to the embodiments described below. no.

3 is a layout diagram illustrating a transflective liquid crystal display device according to a first exemplary embodiment of the present invention, and FIG. 4 is a cross-sectional view taken along the line X11-X12 of FIG. 3.

3 and 4, a plurality of gate lines 112b and data lines 115c are arranged in a matrix on a lower substrate 111 made of glass or the like, and the gate lines 112b and data cross each other. The pixel is defined by line 115c. A thin film transistor T for controlling a signal supplied to each pixel is formed at a portion where the gate line 112b and the data line 115c intersect, and a transparent electrode such as ITO is formed in the pixel region including the thin film transistor T. A pixel electrode 119 made of a material is formed. In addition, the pixel region of one of the two pixels defined by two gate lines 112b that intersect with one data line 115c and are adjacent to each other is connected to the drain electrode 115b of the thin film transistor T. A reflective electrode 117 made of opaque metal is formed. Therefore, the pixel region of the portion where the pixel electrode 119 is exposed is constituted by the transmissive portion A, and the pixel region of the portion where the reflective electrode 117 is formed is constituted by the reflective portion B.

The transflective liquid crystal display according to the first embodiment of the present invention will be described in detail with reference to FIG. 4 as follows.

The gate electrode 112a and the gate line 112b are formed on the lower substrate 111. The semiconductor layer 114 is insulated from the gate electrode 112a by the gate insulating layer 113 on the gate electrode 112a and provides a source and a drain region. The source electrode 115a and the drain electrode 115b are formed on both sides of the semiconductor layer 114, and the data line 115c is formed to cross the gate line 112a. The insulating layer 116 is formed on the entire upper surface, and the reflective electrode 117 is formed on the insulating layer 116 of the reflector B to be connected to the drain electrode 115b through a contact hole. In this case, a portion of the reflective electrode 117 may be formed to overlap the transistor T. A protective layer 118 made of an organic insulator is formed on the reflective electrode 117, and a pixel electrode connected to the drain electrode 115b through a contact hole on the protective layer 118 of the transmissive part A and the reflective part B. 119 is formed.

The upper substrate 131 on which the color filter 132 and the common electrode 133 are formed is disposed on the lower substrate 111. The lower substrate 111 and the upper substrate 131 are bonded to each other by a sealing material (not shown) in a state where the lower substrate 111 and the upper substrate 131 are spaced at a predetermined interval by a spacer (not shown). The liquid crystal layer 140 is injected between the 111 and the upper substrate 131.

In the transflective liquid crystal display of the present invention configured as described above, the light provided from the backlight (not shown) installed on the rear surface of the lower substrate 111 is incident on the liquid crystal layer 140 through the transmission portion A, and the liquid crystal layer At 140, the light is modulated by the liquid crystal oriented by the voltage applied to the pixel electrode 119 and the common electrode 133, and then emitted to the outside through the upper substrate 131 to display a character or an image (transmission mode). ).

In addition, light incident from the outside through the upper substrate 131 of the reflector B is reflected by the reflective electrode 117 through the liquid crystal layer 140, and then incident again into the liquid crystal layer 140, and the liquid crystal layer ( At 140, the light is modulated by the liquid crystal oriented by the voltage applied to the reflective electrode 117 and the common electrode 133, and then emitted to the outside through the upper substrate 131 to display a character or an image (reflective mode). .

5 is a layout diagram illustrating a transflective liquid crystal display according to a second exemplary embodiment of the present invention.

In the transflective liquid crystal display of the first exemplary embodiment shown in FIG. 3, two pixels defined by two gate lines 112b that intersect with one data line 115c and are adjacent to each other are a transmission part A and a reflection part. (B), and the reflective electrode 117 is formed only in the pixel region of the pixels defined by one gate line 112b, so that the transmissive portion A and the reflective portion B are continuously arranged in the horizontal direction, respectively. Has a structure.

However, according to the second exemplary embodiment of the present invention, the transmissive portion A and the reflective portion B are mutually disposed by staggering the reflective electrodes 117 in the pixel areas of the pixels defined by two adjacent gate lines 112b. Provided are translucent liquid crystal display devices. In this case, the arrangement of the reflective electrode 117 may be realized in various forms according to the staggered structure as well as optical characteristics, and the size of the transmissive electrode 117 may be arbitrarily adjusted.

FIG. 6 is a cross-sectional view for describing a transflective liquid crystal display according to a third exemplary embodiment of the present invention, having the same layout as that of FIG. 3 or 5, but having a cross-sectional structure different from that of FIG. 4.

First, a protective layer 218 is formed of an organic insulator having a predetermined thickness on the lower substrate 211 of the reflector B. A gate electrode 212a and a gate line (not shown) are formed on the lower substrate 211 of the transmissive portion A and the protective layer 218 of the reflective portion B. FIG. The semiconductor layer 214 is insulated from the gate electrode 212a by the gate insulating layer 213 and provides a source and a drain region on the gate electrode 212a. The source electrode 215a and the drain electrode 215b are formed on both sides of the semiconductor layer 214, and a data line (not shown) is formed to cross the gate line 212a. The insulating layer 216 is formed on the entire upper surface, and the reflective electrode 217 connected to the drain electrode 215b through the contact hole is formed on the insulating film 216 of the reflector B. In this case, a portion of the reflective electrode 217 may be formed to overlap the transistor T. The pixel electrode 219 connected to the drain electrode 215b through the contact hole is formed on the insulating layer 216 of the transmissive portion A and the reflective electrode 217 of the reflective portion B.

In this embodiment, since the protective layer 218 is formed on the lower substrate 211, the thickness can be easily adjusted and the process can be easily performed.

The upper substrate 231 on which the color filter 232 and the common electrode 233 are formed is disposed on the lower substrate 211. The lower substrate 211 and the upper substrate 231 are bonded to each other by a sealing material (not shown) in a state where the lower substrate 211 and the upper substrate 231 are spaced at predetermined intervals by a spacer (not shown). The liquid crystal layer 240 is injected between the 211 and the upper substrate 231.

In the transflective liquid crystal display of the present invention configured as described above, the light provided from the backlight (not shown) installed on the rear surface of the lower substrate 211 is incident to the liquid crystal layer 240 through the transmission portion A, the liquid crystal layer In 240, the light is modulated by the liquid crystal oriented by the voltage applied to the pixel electrode 219 and the common electrode 233, and then emitted to the outside through the upper substrate 231 to display a character or an image (transmission mode). ).

In addition, light incident from the outside through the upper substrate 231 of the reflector B is reflected by the reflective electrode 217 through the liquid crystal layer 240, and then incident again into the liquid crystal layer 240. Light is modulated by the liquid crystal oriented by the voltage applied to the reflective electrode 217 and the common electrode 233 at 240, and then emitted to the outside through the upper substrate 231 to display a character or an image (reflective mode). .

As described above, according to an exemplary embodiment of the present invention, a reflective electrode (see FIG. 3 or 5) is disposed in a pixel region of one of two pixels defined by two gate lines 112b that intersect with one data line 115c and are adjacent to each other. 117 is formed. Therefore, two pixels defined by two gate lines 112b intersecting with one data line 115c and adjacent to each other may be configured as one color pixel. In this case, two adjacent gates as shown in FIG. The two pixels may be driven simultaneously by connecting the lines S1 and S1 ', S2 and S2', ..., Sn and Sn 'in common. At this time, the pixel of the transmissive portion A to which the pixel electrode 119 is exposed is operated in the transmissive mode, and the pixel of the reflective portion B on which the reflective electrode 117 is formed is operated in the reflective mode.

For example, when one pixel includes red (R), green (G), and blue (B) color pixels, each of the color pixels includes two gate lines 112b adjacent to each other as shown in FIG. 3 or 5. It may be composed of two pixels defined by). That is, in the conventional transflective liquid crystal display, one pixel is composed of sub-pixels of red (R), green (G), and blue (B). The pixel consists of six sub-pixels.

As described above, the preferred embodiment of the present invention has been disclosed through the detailed description and the drawings. The terms are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the present invention has a structure in which a pixel composed of a transmissive portion and a pixel composed of a reflective portion are completely independent. Therefore, the distance D2 between the lower substrate and the upper substrate in the transmission portion and the distance D1 between the lower substrate and the upper substrate in the reflection portion are constant, and there is no boundary area between the transmission portion A and the reflection portion B. Therefore, the orientation disturbance of liquid crystal molecules does not occur. Therefore, as the liquid crystal molecules are uniformly and stably aligned, display quality may be improved.

Claims (10)

A first substrate; A plurality of gate lines and data lines arranged to cross each other on the first substrate; A plurality of thin film transistors respectively connected to the plurality of gate lines and data lines; A plurality of pixel electrodes connected to the plurality of thin film transistors, respectively, and formed in pixel areas defined by the plurality of gate lines and data lines; A reflective electrode formed to overlap with some pixel electrodes of the plurality of pixel electrodes; A second substrate disposed to face the first substrate; A common electrode formed on the second substrate; And A semi-transmissive liquid crystal display device comprising a liquid crystal layer injected between the first substrate and the second substrate. The transflective liquid crystal display of claim 1, wherein a portion of the pixel electrode overlaps the thin film transistor. The transflective liquid crystal display device of claim 1, wherein the reflective electrode is formed in a pixel area of one of two pixels defined by two gate lines that cross one data line and are adjacent to each other. 4. The transflective liquid crystal display of claim 3, wherein the reflective electrode is formed in a pixel region of pixels defined by one gate line of two adjacent gate lines. 4. The transflective liquid crystal display of claim 3, wherein the reflective electrodes are arranged to alternate with each other in a pixel area of pixels defined by the two adjacent gate lines. The transflective liquid crystal display of claim 3, wherein a portion of the reflective electrode overlaps the thin film transistor of the one pixel. 4. The transflective liquid crystal display of claim 3, wherein two pixels defined by two gate lines intersecting with the one data line and adjacent to each other are used as one color pixel. The transflective liquid crystal display of claim 3, wherein two adjacent gate lines are connected to each other in common. The transflective liquid crystal display of claim 1, wherein the pixel electrode is formed on the reflective electrode. The transflective liquid crystal display of claim 1, wherein the pixel electrode is formed of a transparent electrode material.

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