KR20110004702A - Reflective liquid cristal display device and trans-reflective liquid cristal display device - Google Patents

Abstract

PURPOSE: A reflective liquid crystal display device and a trans-reflective liquid crystal display device are provided to have excellent display quality. CONSTITUTION: A first substrate(101) defines plural pixel by letting a gate line cross a data line. A thin film transistor(104) is formed at a region at which the gate line crosses the data line in each pixel. A reflective electrode(105) is formed at each pixel to be connected to the thin film transistor. A second substrate(111) is distanced from the first substrate at a certain interval.

Description

Reflective liquid crystal display and reflective transparent liquid crystal display {REFLECTIVE LIQUID CRISTAL DISPLAY DEVICE AND TRANS-REFLECTIVE LIQUID CRISTAL DISPLAY DEVICE}

The present invention relates to a reflective liquid crystal display device and a reflective transmissive liquid crystal display device. In particular, a sufficient bonding margin between the first substrate and the second substrate is ensured, so that even if an error occurs in the alignment of the first substrate and the second substrate, the reflectance fluctuates. And a reflection type liquid crystal display device and a reflection type liquid crystal display device having improved color quality due to no change in color gamut.

BACKGROUND ART In general, liquid crystal display devices have tended to be gradually widened due to their light weight, thinness, and low power consumption. Accordingly, the liquid crystal display device is widely used as a means for displaying a screen in portable computers, mobile phones, office automation equipment and the like.

In general, a liquid crystal display device displays a desired image on a screen by adjusting the amount of light transmitted according to image signals applied to a plurality of control switching elements arranged in a matrix.

The liquid crystal display includes a liquid crystal panel in which a color filter substrate as an upper substrate and a thin film transistor array substrate as a lower substrate are opposed to each other and a liquid crystal layer is formed between the two substrates, and a scan signal and image information are supplied to the liquid crystal panel. It comprises a drive unit for operating the liquid crystal panel.

The LCD may be classified into two types according to the type of light source. That is, it is classified into a transmissive liquid crystal display device using a light source provided inside the liquid crystal display device and a reflective liquid crystal display device using an external light source (for example, sunlight).

Since the transmissive liquid crystal display uses an internal light source that uses a portable battery as a power source, high power consumption is required. Therefore, when the transmissive liquid crystal display is applied to a portable electronic device, the usage time may be long due to the limitation of the portable battery capacity. There is a problem that does not exhibit the advantages of portability.

However, since the reflective liquid crystal display device minimizes power consumption by using external light such as sunlight, such a reflective liquid crystal display device can be carried for a long time when it is applied to portable electronic devices. Consumers' interest in devices is increasing, and interests in reflection-transmitting liquid crystal display devices combining reflection type and transmission type are also increasing.

Hereinafter, a conventional reflective liquid crystal display device will be described with reference to the accompanying drawings.

In FIG. 1, the first substrate 1 is illustrated, and in FIG. 2, the color filter layer of the second substrate 11 is illustrated, but the reflective electrode 5 is also illustrated for convenience of description, and in FIGS. 3 and 4. 1 is a cross-sectional view taken along lines II ′ and II ′ of FIG. 1.

1 to 4, a conventional reflective liquid crystal display device is formed on the first substrate 1 and the second substrate 11 and on the first substrate 1 so as to cross each other longitudinally and horizontally. A thin film transistor 4 formed in a region where a gate line 2 and a data line 3 defining a pixel of the pixel and an intersection of the gate line 2 and the data line 3 in each pixel of the first substrate 1 intersect. ), A reflective electrode 5 formed for each pixel so as to be connected to the thin film transistor 4, a liquid crystal layer (not shown) formed between the first substrate 1 and the second substrate 11, and the first electrode. A color filter layer formed of a plurality of sub color filters 12 formed on the second substrate 11 so as to correspond to each pixel of the first substrate 1, and formed on the color filter layer and the reflective electrode 5; It is composed of a common electrode 13 for driving the liquid crystal layer by forming a vertical electric field together.

In each of the sub color filters 12, a transmission hole 12a is formed at the center of the sub color filter 12 so as to minimize a problem in which external light is lost while passing through the sub color filter 12 twice.

In addition, a black matrix, which is essentially formed in a general liquid crystal display, is not formed on the second substrate. As a result, a region where the left and right adjacent sub color filters 12 overlap each other (or a region in contact with each other) is a black matrix. It has a structure that is not hidden and exposed.

In the conventional general reflective liquid crystal display device, a plurality of subs forming the color filter layer when an error occurs in alignment when the first substrate 1 and the second substrate 11 are bonded to each other. In the color filter 12, some regions correspond to pixels to which they correspond, and the remaining regions correspond to pixels adjacent to the left or right side of the pixels to which they correspond, so that each color does not exhibit one color and is mixed. Since the color is expressed, the color reproducibility is lowered, the screen quality is lowered, and the reflectance fluctuates. The threshold at which such a mixed color problem and the reflectance fluctuation problem does not occur is called a coalescence margin.

As described above, in the reflection type liquid crystal display device in which the black matrix is not formed on the second substrate 11, the bonding margin is not sufficient, and there is even a slight error in the alignment of the first substrate 1 and the second substrate 11. In this case, the color reproducibility is lowered and the reflectance is lowered. Therefore, sufficient margin of adhesion is secured, so that the color reproducibility is not reduced due to mixed color, and the reflectance is not lowered.

The present invention is to solve the above problems, an object of the present invention is to ensure sufficient bonding margin of the first substrate and the second substrate, even if an error occurs in the alignment of the first substrate and the second substrate reflectance variation and color The present invention provides a reflection type liquid crystal display device and a reflection type liquid crystal display device having improved refresh rate because the refresh rate does not occur.

According to an aspect of the present invention, there is provided a reflective LCD including: a first substrate in which a plurality of pixels are defined by crossing a gate line and a data line vertically and horizontally; A thin film transistor formed in an area where the gate line and the data line intersect each pixel; A reflective electrode formed for each pixel to be connected to the thin film transistor; A second substrate disposed at a predetermined distance from the first substrate; And a color filter layer including a plurality of sub color filters formed on the second substrate so as to correspond to each pixel of the first substrate. And a control unit. In addition, the left and right adjacent sub color filters in the color filter layer are formed to be spaced apart by at least a region corresponding to the spaced space between the left and right adjacent reflective electrodes, and the sub color filter is disposed at the left and right ends thereof. Characterized in that the through-holes overlapping with the left and right ends of the reflective electrode is formed.

In the reflective transmissive liquid crystal display according to the preferred embodiment of the present invention, a plurality of pixels are defined by crossing a gate line and a data line vertically and horizontally, and each pixel is formed around a transmissive area and the transmissive area. A first substrate on which a reflective region of the substrate is defined; A thin film transistor formed in an area where the gate line and the data line intersect each pixel; A pixel electrode formed for each pixel to be connected to the thin film transistor; A reflective electrode formed in the reflective region of each pixel; A second substrate disposed at a predetermined distance from the first substrate; And a color filter layer including a plurality of sub color filters formed on the second substrate so as to correspond to each pixel of the first substrate. And a control unit. In addition, the left and right adjacent sub color filters in the color filter layer are formed to be spaced apart by at least a region corresponding to the spaced space between the left and right adjacent reflective electrodes, and the sub color filter is disposed at the left and right ends thereof. Characterized in that the through-holes overlapping with the left and right ends of the reflective electrode is formed.

In the reflective liquid crystal display and the reflective transmissive liquid crystal display according to the preferred embodiment of the present invention having the above-described configuration, the black matrix is not formed at the boundary between the sub color filters of different colors in the color filter layer. Transmissive holes overlapping the left and right ends of the reflective electrode are formed at the left and right ends of the color filter, so that an error occurs in the alignment of the first and second substrates so that the second substrate is left or right with respect to the first substrate. Even if a problem occurs in that the adhesion is performed in a state of being moved by a predetermined length, the sub-color filter does not cause a change in reflectance and does not cause mixed color in the pixel because some regions correspond to pixels adjacent to the left or right side of the pixel to which the sub color filter is to correspond. There is an advantage that a margin, that is, a sufficient margin of adhesion is secured.

Accordingly, when the first substrate and the second substrate are aligned and bonded within the sufficient bonding margin as described above, the reflectance variation and the color reproduction variation do not occur at all. There is an advantage that can provide a liquid crystal display device to a consumer.

Hereinafter, a reflective liquid crystal display device and a reflective transmissive liquid crystal display device according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

First, a reflective liquid crystal display according to an exemplary embodiment of the present invention will be described with reference to FIGS. 5 to 9.

5 illustrates a first substrate 101 of a reflective liquid crystal display according to a preferred embodiment of the present invention, and FIG. 6 illustrates a second substrate 111 of a reflective liquid crystal display according to a preferred embodiment of the present invention. For the sake of convenience, the reflective electrode 105 of the first substrate 101 is also illustrated, and FIG. 7 is a cross-sectional view taken along the line III-III ′ of FIG. 5. FIG. 8 is a cross-sectional view taken along line IV-IV ′ of FIG. 5, and FIG. 9 shows a result of measuring reflectance and color reproducibility while changing the area of the transmission hole 112a.

5 to 8, a reflective liquid crystal display according to an exemplary embodiment of the present invention includes a first substrate in which a plurality of pixels are defined by crossing a gate line 102 and a data line 103 vertically and horizontally. 101; A thin film transistor 104 formed in an area where the gate line 102 and the data line 103 intersect each pixel; A reflective electrode 105 formed for each pixel so as to be connected to the thin film transistor 104; A second substrate 111 disposed at a predetermined distance from the first substrate 101; And a color filter layer including a plurality of sub color filters 112 formed on the second substrate 111 to correspond to each pixel of the first substrate 101. . In the color filter layer, the left and right adjacent sub color filters 112 are spaced apart by at least a region corresponding to the spaced space between the left and right adjacent reflective electrodes 105, and the sub color filters 112 are spaced apart from each other. Transmitting holes 112a overlapping the left and right ends of the reflective electrode 105 are formed in the left and right ends.

Each component of the reflective liquid crystal display according to the preferred embodiment of the present invention having such a configuration will be described in detail as follows.

5 to 8, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal panel including a first substrate 101, which is a thin film transistor array substrate, and a second substrate 111, which is a color filter substrate. In addition, a liquid crystal layer (not shown) is formed between the first substrate 101 and the second substrate 111.

On the first substrate 101, a gate line 102 and a data line 103 are formed to cross each other longitudinally and horizontally so that a plurality of pixels are defined, and the gate line 102 and the data line 103 cross each other. The thin film transistor 104 connected to the gate line 102 and the data line 103 is formed in the region.

The thin film transistor 104 includes a gate electrode 104a formed on the first substrate 101, a gate insulating film 104b formed on the gate electrode 104a, and an active formed on the gate insulating film 104b. A layer 104c, and a source electrode 104d and a drain electrode 104e formed on the active layer 104c, and a protective film 106 is formed on the thin film transistor 104.

A plurality of irregularities may be formed on the surface of the passivation layer 106, and a part or the entire area of the reflective electrode 105 has a concave-convex shape, which will be described below.

On the passivation layer 106 of the first substrate 101, a reflective electrode 105 connected to the drain electrode 104e of the thin film transistor 104 through a contact hole is formed for each pixel.

The reflective electrode 105 receives a pixel voltage from a driver (not shown) through the data line 103 to form a vertical electric field together with the common voltage applied to the common electrode 113 on the second substrate 111. Drive the liquid crystal layer.

In addition, the reflective electrode 105 is formed of a material having excellent reflectivity and an opaque metal. As a result, light incident from the outside into the liquid crystal panel is reflected by the reflective electrode 105 and emitted to the outside of the liquid crystal panel. Therefore, the screen can be displayed without providing a light source inside the liquid crystal panel.

Since the reflective electrode 105 is formed on the protective film 106 having a plurality of irregularities formed on the surface thereof, a plurality of irregularities are formed in the region corresponding to the irregularities of the protective film 106 like the protective film 106. The reflectance of the electrode 105 becomes higher.

7 and 8 illustrate that a plurality of irregularities are formed on a part of the reflective electrode 105 on the protective layer 106 by forming a plurality of irregularities on the surface of the protective film 106, but the present invention is limited thereto. In other words, various changes may be made without departing from the gist of the present invention, such as unevenness or unevenness formed in the entire reflective electrode 105.

5, 7, and 8, the reflective electrode 105 is formed to overlap the thin film transistor 104, and left and right ends thereof are formed such that a predetermined region overlaps the data line 103.

A color filter layer including a plurality of sub color filters 112 corresponding to each pixel of the first substrate 101 is formed on the second substrate 111 disposed at a predetermined distance from the first substrate 101.

In the color filter layer, the sub color filters 112 adjacent to the left and right sides having different colors are formed to be spaced apart from each other by at least a region corresponding to the spaced space between the reflective electrodes 105 adjacent to the left and right sides. Therefore, the sub color filters 112 having the same color as each other are integrally formed to be connected to each other so that the entire color filter layer has a stripe shape.

The left and right ends of the sub color filter 112 are formed with a through hole 112a overlapping with the left and right ends of the reflective electrode 105 formed on the corresponding pixel. Some of the light emitted to the outside after the incident light passes through the transmission hole 112a rather than the pigment of the sub color filter 112, thereby minimizing the loss of light.

FIG. 9 illustrates a result of measuring reflectance and color reproducibility while changing the area of the transmission hole 112a provided in the sub color filter 112 corresponding to each pixel of the first substrate 101. Referring to, it can be seen that as the ratio of the area of the transmission hole 112a to the area of the pixel increases, the reflectance increases, but the color reproduction rate decreases.

Therefore, the area of the transmissive hole 112a formed in the sub color filter 112 of the reflective liquid crystal display according to the preferred embodiment of the present invention is appropriately selected within the range in which the screen quality is not deteriorated in the reflectance and color reproducibility. It is desirable to be.

Referring to FIG. 9, the ratio of the area of the transmission hole 112a to the pixel area may be about 15 [%] at which an appropriate reflectance is secured and an appropriate color reproduction rate is also secured. However, since the reflectance curve and the color reproduction curve shown in FIG. 9 may be changed by not only a ratio of the area of the transmission hole 112a to the pixel area, but also a plurality of factors, the reflective liquid crystal display device according to the preferred embodiment of the present invention. The ratio of the area of the through hole 112a to the area of the pixel is not limited to about 15 [%] as mentioned above, and it is found that the ratio between the reflectance curve and the color reproduction curve is about.

In the reflective LCD according to the preferred embodiment of the present invention as described above, although the black matrix is not formed at the boundary of the sub color filter 112 of different colors in the color filter layer, the sub color filter 112 Transmissive holes 112a overlapping the left and right ends of the reflective electrode 105 are formed at the left and right ends of the second electrode, so that an error occurs in the alignment of the first and second substrates 101 and 111, resulting in a second error. In the case where a problem occurs in that the bonding is performed while the substrate 111 is moved to the left or the right with respect to the first substrate 101 by a predetermined length, the sub color filter 112 is moved to the left or the right side of the pixel to which the substrate 111 should correspond. Partial regions correspond to the pixels in contact with each other, thereby ensuring sufficient margin that does not cause a problem that causes color mixing in the pixels.

Hereinafter, a reflective transmissive liquid crystal display device according to an exemplary embodiment of the present invention will be described with reference to FIG. 10.

As shown in FIG. 10, in the transflective liquid crystal display according to the exemplary embodiment of the present invention, a gate line (not shown) and a data line 203 cross vertically and horizontally, and a plurality of pixels are defined, and each pixel is transmissive. A first substrate 201 defining a region and a reflection region outside the transmission region; A thin film transistor 204 formed in an area where the gate line and the data line 203 intersect each pixel; A pixel electrode 208 formed for each pixel so as to be connected to the thin film transistor 204; A reflection electrode 205 formed in the reflection area of each pixel; A second substrate 211 disposed at a predetermined distance from the first substrate 201; And a color filter layer including a plurality of sub color filters 212 formed on the second substrate 211 so as to correspond to each pixel of the first substrate 201; . In the color filter layer, the left and right adjacent sub color filters 212 are formed to be spaced apart by at least a region corresponding to the spaced space between the left and right adjacent reflective electrodes 205, and the sub color filter 212 is formed in the color filter layer. Transmitting holes 212a overlapping the left and right ends of the reflective electrode 205 are formed at the left and right ends.

Each component of the reflective liquid crystal display according to the preferred embodiment of the present invention having such a configuration will be described in detail as follows.

Referring to FIG. 10, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal panel including a first substrate 201, which is a thin film transistor array substrate, and a second substrate 211, which is a color filter substrate. A liquid crystal layer (not shown) is formed between the first substrate 201 and the second substrate 211.

On the first substrate 201, a gate line (not shown) and a data line 203 intersect with each other vertically and horizontally to define a plurality of pixels, and each pixel defines a transmission region and reflects the outside of the transmission region. The area is defined.

In each pixel, a thin film transistor 204 connected to the gate line and the data line 203 is formed in an area where the gate line and the data line 203 cross each other.

The thin film transistor 204 includes a gate electrode 204a formed on the first substrate 201, a gate insulating film 204b formed on the gate electrode 204a, and an active layer formed on the gate insulating film 204b. 204c and a source electrode 204d and a drain electrode 204e formed on the active layer 204c, and a first passivation film 206 is formed on the thin film transistor 204.

A plurality of irregularities may be formed on the surface of the first passivation layer 206, which is to allow a part or the entire area of the reflective electrode 205 to have an uneven shape, which will be described below.

The reflective electrode 205 is formed in the reflective region of each pixel on the first passivation layer 206 of the first substrate 201, and the first passivation layer 206 is formed in a region corresponding to a plurality of irregularities of the first passivation layer 206. A large number of irregularities are formed. The reflective electrode 205 is formed of a metal having excellent reflectivity and opaque metal.

Since the reflective electrode 205 is formed on the first passivation layer 206 having a plurality of irregularities formed on the surface thereof, a plurality of irregularities are formed in the region corresponding to the irregularities of the first passivation layer 206, like the first passivation layer 206. As a result, the reflectance of the reflective electrode 205 is further increased.

Referring to FIG. 10, the reflective electrode 205 is formed to overlap the thin film transistor 204, and the left and right ends thereof are formed such that a predetermined region overlaps the data line 203.

The second passivation layer 207 is formed on the reflective electrode 205.

10 illustrates that the second passivation layer 207 is formed on the reflective electrode 205. However, the present invention is not limited thereto, and the second passivation layer 207 is not formed or the second passivation layer 207 is formed. ) And at the same time a third passivation layer (not shown) is formed between the first passivation layer 206 and the reflective electrode 205, and various modifications may be made without departing from the gist of the present invention.

Each pixel of the first substrate 201 is formed with a pixel electrode 208 connected to the drain electrode 204e of the thin film transistor 204 through contact holes formed in the first and second passivation layers 206 and 207. .

The pixel electrode 208 receives a pixel voltage from a driver (not shown) through the data line 203 to form a vertical electric field together with the common voltage applied to the common electrode 213 on the second substrate 211. Drive the liquid crystal layer. The pixel electrode 208 is formed of a transparent conductive material.

A color filter layer including a plurality of sub color filters 212 corresponding to each pixel of the first substrate 201 is formed on the second substrate 211 disposed at a predetermined distance from the first substrate 201.

In the color filter layer, the sub color filters 212 having different colors adjacent to left and right sides are formed to be spaced apart from each other by at least a region corresponding to the space between the adjacent reflective electrodes 205. Thus, the sub color filters 212 having the same color as each other are integrally formed to be connected to each other so that the entire color filter layer has a stripe shape.

The left and right ends of the sub color filter 212 are formed with a through hole overlapping with the left and right ends of the reflective electrode 205 formed in the pixel corresponding to the sub color filter 212. Some of the light emitted to the outside passes through the transmission hole 212a, not the pigment of the sub color filter 212, thereby minimizing the loss of light.

In the reflective LCD according to the preferred embodiment of the present invention as described above, although the black matrix is not formed at the boundary of the sub color filter 212 of different colors in the color filter layer, the sub color filter 212 is used. Transmissive holes 212a overlapping the left and right ends of the reflective electrode 205 are formed at the left and right ends of the second electrode, so that an error occurs in the alignment of the first and second substrates 201 and 211. When the problem occurs that the substrate 211 is adhered to the first substrate 201 by a predetermined length to the left or the right, the sub color filter 212 is adjacent to the left or right side of the pixel to which the sub-color filter 212 should correspond. A sufficient margin, that is, a margin of adhesion, is secured without causing a problem in which a partial region corresponds to the pixel and causes color mixing in the pixel.

1 is a plan view showing a first substrate of a conventional general reflective liquid crystal display device;

FIG. 2 is a plan view showing a color filter formed on a second substrate of a conventional reflective liquid crystal display device together with a reflective electrode for convenience of description; FIG.

3 is a cross-sectional view taken along the line II ′ of FIG. 1, illustrating a first substrate and a second substrate.

4 is a cross-sectional view taken along the line II-II ′ of FIG. 1, illustrating a first substrate and a second substrate.

5 is a plan view showing a first substrate of a reflective liquid crystal display device according to a preferred embodiment of the present invention.

6 is a plan view illustrating a color filter layer of a second substrate of a reflective liquid crystal display according to a preferred embodiment of the present invention, together with a reflective electrode for convenience of description;

FIG. 7 is a cross-sectional view taken along line III-III ′ of FIG. 5, showing a first substrate and a second substrate together.

FIG. 8 is a cross-sectional view taken along line IV-IV ′ of FIG. 5, showing a first substrate and a second substrate together.

9 is an experimental result showing the result of measuring the reflectance and color reproducibility while changing the area of the transmission hole in FIG.

10 is a cross-sectional view showing a transflective liquid crystal display device according to a preferred embodiment of the present invention.

** Description of the symbols for the main parts of the drawings **

101, 201: first substrate 102: gate line

103 and 203 data lines 104 and 204 thin film transistors

105, 205: reflective electrode 106: protective film

206: first protective film 207: second protective film

208 pixel electrode

111, 211: second substrate 112, 212: sub color filter

112a and 211a: through-holes 113 and 213: common electrode

Claims (7)

A first substrate in which a plurality of pixels are defined by crossing the gate line and the data line in a vertical direction; A thin film transistor formed in an area where the gate line and the data line intersect each pixel; A reflective electrode formed for each pixel to be connected to the thin film transistor; A second substrate disposed at a predetermined distance from the first substrate; And A color filter layer including a plurality of sub color filters formed on the second substrate so as to correspond to each pixel of the first substrate; It is configured to include, In the color filter layer, the left and right adjacent sub color filters are formed to be spaced apart by at least a region corresponding to the spaced space between the left and right adjacent reflective electrodes, and the sub color filters are formed on the left and right ends of the reflective electrodes. Reflective liquid crystal display device, characterized in that the through hole overlapping the left and right ends of the formed. The liquid crystal display of claim 1, wherein left and right ends of the reflective electrode overlap with adjacent data lines. The liquid crystal display device of claim 1, wherein the left and right adjacent sub color filters have different colors, and the up and down adjacent sub color filters have the same color. The reflective liquid crystal display of claim 3, wherein the color filter layer is formed such that upper and lower adjacent sub color filters are connected to each other to form a stripe shape. A plurality of pixels are defined by crossing the gate line and the data line vertically and horizontally, each pixel including a first substrate having a transmissive region and a reflective region outside the transmissive region; A thin film transistor formed in an area where the gate line and the data line intersect each pixel; A pixel electrode formed for each pixel to be connected to the thin film transistor; A reflective electrode formed in the reflective region of each pixel; A second substrate disposed at a predetermined distance from the first substrate; And A color filter layer including a plurality of sub color filters formed on the second substrate so as to correspond to each pixel of the first substrate; It is configured to include, In the color filter layer, the left and right adjacent sub color filters are formed to be spaced apart by at least a region corresponding to the spaced space between the left and right adjacent reflective electrodes, and the sub color filters are formed on the left and right ends of the reflective electrodes. And a transmissive hole overlapping the left and right ends of the reflective liquid crystal display. The liquid crystal display of claim 1, wherein the left and right adjacent sub color filters have different colors, and the up and down adjacent sub color filters have the same color. The liquid crystal display of claim 6, wherein the color filter layer is formed such that upper and lower adjacent sub color filters are connected to each other to form a stripe shape.

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