KR20070043473A - Reflective-transmissive type display substrate, and liquid crystal display having the same - Google Patents

Abstract

 A reflection-transmissive display substrate and a liquid crystal display panel having the same for improving display quality are disclosed. The pixel portion has a transmission region that transmits the first light and a reflection region that reflects the second light. The switching element is formed in the pixel portion and connected to the gate wiring and the source wiring. The transparent electrode is electrically connected to the switching element and formed in the pixel portion. The reflective electrode is formed on the transparent electrode corresponding to the reflective region. The protective film is formed of an insulating material on the reflective electrode, so that the potentials of the reflective and transmissive regions are different. Accordingly, by forming a protective film in the reflective region, a double electrode structure may be implemented to simplify the manufacturing process, and may have optical characteristics similar to those of the double cell gap structure while having a single cell gap structure.

Protective film, reflective electrode, AMO, reflector, transmissive part, VA mode, double electrode

Description

REFLECTIVE-TRANSMISSIVE TYPE DISPLAY SUBSTRATE, AND LIQUID CRYSTAL DISPLAY HAVING THE SAME}

1 is a cross-sectional view of a conventional double-electrode reflection-transmissive liquid crystal display device.

2 is a plan view illustrating a reflection-transmissive liquid crystal display panel according to an exemplary embodiment of the present invention.

3 is a cross-sectional view taken along the line II ′ of FIG. 2.

4A to 4C are process diagrams for describing a method of manufacturing the opposing substrate illustrated in FIG. 3.

5A through 5C are process diagrams for describing a method of manufacturing the display substrate illustrated in FIG. 3.

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

100 display substrate 104 organic film

155, 165: first and second switching elements 156: contact hole

157 and 167: first and second transmission electrodes 158 and 168: first and second reflection electrodes

159: protective film 200: opposing substrate

220: color filter layer 240: common electrode

300: liquid crystal layer LH: light hole

RA: reflection area TA: transmission area

The present invention relates to a reflective-transmissive display substrate and a liquid crystal display panel having the same, and more particularly, to a display substrate and a liquid crystal display panel for optimizing light efficiency and simplifying a manufacturing process.

In general, the reflection-transmissive liquid crystal display is a transmission mode for displaying in a dark place where an indoor or external light source does not exist, using a built-in light source of the display device itself, and reflecting and displaying external incident light in an outdoor high-light environment. Has a mode.

The voltage-transmittance (V-T) curve corresponding to the transmission mode and the voltage-reflectance (V-R) curve corresponding to the reflection mode are different from each other. Accordingly, a double-cell gap reflection-transmissive liquid crystal display device having a cell gap in the reflective region and a cell gap in the transmissive region to prevent light loss in the transmissive mode has been developed. However, such a double cell gap method is difficult to ensure uniformity of the cell gap, and shortage of the opposing substrate and the lower substrate may occur in the reflective region having a low cell gap which is about half of the cell gap of the transmission region. .

1 is a cross-sectional view of a conventional double-electrode reflection-transmissive liquid crystal display device.

Referring to FIG. 1, a dual-electrode reflection-transmissive liquid crystal display device includes a lower substrate 10, an opposite substrate 50 provided to face the lower substrate 10, and a lower substrate 10 and an opposite substrate ( And a liquid crystal layer 40 interposed therebetween.

The lower substrate 10 includes a gate insulating layer 14, an organic insulating layer 26, a transmissive electrode 30, and a reflective electrode 32 on the first substrate 11.

A plurality of thin film transistors (not shown) are provided on the first substrate 11. The gate insulating layer 14 is formed on the first substrate 11 as one of the components forming the thin film transistor.

Transmissive electrodes 30 and reflective electrodes 32 electrically connected to the thin film transistors are sequentially stacked on the organic insulating layer 26 through via holes (not shown) passing through the organic insulating layer 26.

The reflective electrode 32 is formed with a transmission window exposing a portion of the transmission electrode 30 on the transmission electrode 30. Therefore, the reflection-transmissive liquid crystal display device is divided into a reflection area RA provided with the reflection electrode 32 and a transmission area TA formed with the transmission window.

The opposing substrate 50 includes a color filter layer 52, a first insulating layer 56, a common electrode 58, and a second insulating layer 60 on the second substrate 51.

The color filter layer 52 includes red (R), green (G), and blue (B) color pixels, and includes a light hole 54 exposing the second substrate 51 in the reflection area RA. Have

The first insulating layer 56 is formed to correspond to the transmission area TA, and the second insulating layer 60 is formed on the common electrode 58 corresponding to the reflection area RA. The first and second insulating layers 56 are formed of an organic layer and have the same thickness. Therefore, the liquid crystal layer 40 has the same cell gap in the reflection area RA and the transmission area TA.

In the above-described double-electrode reflection-transmissive liquid crystal display device, the first distance d1 between the reflective electrode 32 and the common electrode 58 is shared with the transmission electrode 30 by using the step of the common electrode 58. It is kept larger than the second distance d2 between the electrodes 58. Therefore, the liquid crystal layer provided in the reflection area RA and the liquid crystal layer provided in the transmission area TA have different potentials, thereby improving both reflectance and transmittance.

In the dual-electrode reflection-transmissive liquid crystal display, at least two photolithography processes are performed to form the first and second organic layers 56 and 60 on the opposing substrate 50 to form the step of the common electrode 58. The process is necessary. Accordingly, there is a problem that the manufacturing process of the reflection-transmissive liquid crystal display device becomes complicated.

Accordingly, the technical problem of the present invention is to solve this problem, and an object of the present invention is to provide a reflective-transmissive display substrate for simplifying the manufacturing process.

Another object of the present invention is to provide a liquid crystal display panel having the reflection-transmissive display substrate.

A display substrate according to an exemplary embodiment for realizing the object of the present invention includes a substrate, a pixel portion, a switching element, a transparent electrode, a reflective electrode, and a protective film. The pixel portion has a transmission region that transmits first light and a reflection region that reflects second light. The switching element is formed in the pixel portion and is connected to a gate line and a source line. The transparent electrode is electrically connected to the switching element and formed in the pixel portion. The reflective electrode is formed on the transparent electrode corresponding to the reflective region. The passivation layer is formed of an insulating material on the reflective electrode to change potentials of the reflective and transmissive regions.

A liquid crystal display panel according to an exemplary embodiment for realizing another object of the present invention includes a display substrate, an opposing substrate, and a liquid crystal layer. The display substrate may include a pixel portion having a transmission region that transmits first light and a reflection region that reflects second light, a switching element formed on the pixel portion, and a transparent portion electrically connected to the switching element. And a reflective electrode formed on an electrode, the reflective electrode corresponding to the reflective region, and a protective film formed of an insulating material on the reflective electrode. The opposing substrate is combined with the display substrate to accommodate the liquid crystal layer, and a common electrode is formed on a surface of the opposing substrate facing the transparent electrode and the reflective electrode.

According to the reflection-transmissive display substrate and the liquid crystal display panel having the same, the first potential of the reflective region and the second potential of the transmissive region applied to the liquid crystal layer by adjusting the thickness of the protective film formed by patterning the reflective electrode on the reflective electrode at the same time. By different from the can be implemented a double electrode structure. As a result, it is possible to have a simpler manufacturing process than a reflection-transmissive liquid crystal display having a conventional double electrode structure.

Hereinafter, with reference to the accompanying drawings, it will be described in detail the present invention.

2 is a plan view of a reflective-transmissive liquid crystal display panel according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the reflection-transmissive liquid crystal display panel includes a first pixel portion P1 and a second pixel portion P2 adjacent to each other.

The first pixel portion P1 is defined by the source lines DLm-1 and DLm and the gate lines GLn-1 and GLn adjacent to each other.

The first pixel portion P1 includes a first switching element 155 formed on a display substrate and a first transmission electrode 157 connected to the first switching element 155. In addition, a first reflective electrode 158 is formed in a partial region on the first transmission electrode 157, and the first pixel portion P1 is formed in the transmission region TA by the first reflection electrode 158. And a reflection area RA. A first passivation layer (not shown) is formed on the first reflective electrode 158 to improve reflectance. The first passivation layer is formed of an insulating material larger than the refractive index of the upper liquid crystal layer. Preferably, the insulating material includes titanium dioxide (TiO₂) and zirconium dioxide (ZrO₂). The first passivation layer is patterned and formed simultaneously with the first reflective electrode 158, and the first potential of the reflection region RA and the second potential of the transmission region TA are applied to the liquid crystal layer through the thickness of the first passivation layer. By adjusting the differently to implement a double electrode structure.

The second pixel portion P2 is defined by source lines DLm and DLm + 1 and gate lines GLn-1 and GLn adjacent to each other.

The second pixel portion P2 includes a second switching element 165 formed on the display substrate and a second transmission electrode 167 connected to the second switching element 165. In addition, a second reflective electrode 168 is formed on a portion of the second transmission electrode 167, and the second pixel portion P2 is formed by the second reflection electrode 168. It is defined as the reflection area RA. A second passivation layer (not shown) is formed on the second reflection electrode 168 to improve reflectance. The second passivation layer is formed of the same material as the first passivation layer.

The second passivation layer is formed at the same time as the second reflection electrode 168 and is formed, and the first potential of the reflection region RA of the second pixel portion P2 applied to the liquid crystal layer through the thickness of the second passivation layer. The second potential of the transmission area TA is adjusted differently to implement the double electrode structure.

The storage common wiring STL is commonly connected to the first and second pixel units P1 and P2. The storage common line STL is formed to cover the source lines DLm-1, DLm, and DLm + 1, respectively.

Light holes LH are formed in the reflective regions RA of the first and second pixel units P1 and P2. The light hole LH compensates for the luminance difference between the transmitted light and the reflected light by transmitting the light emitted from the rear surface as it is. That is, the external light incident on the reflective area RA is reflected by the first and second reflective electrodes 158 and 168 to pass through the color filter pattern several times, while the incident light is incident on the transmissive area TA. The internal light passes through the color filter pattern once. As a result, the light in the reflective area RA passes through the color filter pattern several times, and the luminance decreases, and the light hole LH compensates for the decreased luminance.

3 is a cross-sectional view taken along the line II ′ of FIG. 2.

2 and 3, the reflective-transmissive liquid crystal display panel includes a display substrate 100, an opposing substrate 200 facing the display substrate 100, and a gap between the display substrate and the opposing substrates 100 and 200. It includes a liquid crystal layer 300 interposed therein.

The display substrate 100 includes a first base substrate 101.

The gate electrodes 151 and 161 of the switching elements 155 and 165, the storage common line 170 and the gate line GLn are formed on the first base substrate 101 in a gate metal pattern. The storage common wiring 170 is formed to have a size enough to cover the source wirings DLm-1, DLm, and DLm + 1, and thus corresponds to the source wirings DLm-1, DLm, and DLm + 1. As a result, the light shielding pattern formed on the counter substrate 200 may not be formed.

A gate insulating layer 102 is formed on the gate metal pattern, and an amorphous silicon layer 152a and an in-situ doped n ⁺ amorphous silicon layer 152b are sequentially formed on the gate insulating layer 102. The channel layer 152 is formed. Although not shown, a channel layer of the second switching element is also formed.

A source metal pattern is formed on the channel layer 152. The source metal pattern includes source electrodes 153 and 163 of the switching elements 155 and 165, drain electrodes 154 and 164, and source wirings DLm-1, DLm, and DLm + 1. .

The passivation layer 103 is formed on the source metal pattern, and the organic layer 104 is sequentially formed on the passivation layer.

Contact holes 156 and 166 exposing partial regions of the drain electrodes 154 and 164 are formed in the organic layer 104, respectively.

Transmissive electrodes 157 and 167 are formed on the organic layer 104. In general, each transmission electrode may be formed over one pixel area or may be formed in a partial area corresponding to the transmission area. The transparent electrode is a transparent electrode that transmits light, and indium tin oxide (ITO) and indium zinc oxide (IZO) materials are used.

Reflective electrodes 158 and 168 are formed on the transmissive electrodes 157 and 167. The reflective electrodes 158 and 168 are a kind of metal pattern that reflects light, and a silver-molybdenum alloy is used.

A passivation layer is formed on the reflective electrodes 158 and 168. The passivation layer 159 formed on the reflective electrode 158 is formed of an insulating material larger than the refractive index of the liquid crystal layer 300, and preferably includes titanium dioxide (TiO₂) and zirconium dioxide (ZrO₂). The protective layer is formed of a material which can be etched by phosphoric acid, nitric acid, acetic acid, oxalic acid, etc., which are etching liquids of the reflective electrode 158 to simultaneously pattern the reflective electrode.

Since the passivation layer 159 is formed of an insulating material, when the predetermined pixel voltage is applied to the pixel portion P1, the source layer DLm is separated between the reflective electrode 158 and the common electrode 240 by the passivation layer 159. A first potential V1 lower than the pixel voltage transferred to the second voltage is formed, and a second potential corresponding to the pixel voltage is formed between the transmission electrode 157 and the common electrode 240 of the transmission region. As a result, the first potential V1 of the reflection area is lower than the second potential of the transmission area. As described above, the thickness of the passivation layer 159 is designed such that the phase difference of the liquid crystal layer 300 in the reflection region becomes λ / 4 with respect to the phase difference λ / 2 in the liquid crystal layer 300 in the transmission region.

In addition, the surface of the organic film 104 is preferably an uneven pattern. The unevenness corresponding to the reflective region RA serves as a micro reflective lens for the reflective electrodes 158 and 168 to scatter external light. However, those skilled in the art may planarize the surface of the organic film described above.

The opposing substrate 200 includes a second base substrate 201. The light blocking layer 210 is formed on the second base substrate 201. The light blocking layer is generally formed in regions corresponding to the source wirings DLm-1, DLm, and DLm + 1 and the gate lines GLn-1 and GLn of the display substrate 100.

Here, as the storage common wiring 170 formed under the source wirings is formed to a size sufficient to sufficiently cover each of the source wirings DLm-1, DLm, and DLm + 1, the light blocking layer may be formed. It is formed corresponding to the gate wirings. Of course, the light blocking layer may be formed to correspond to the source wirings DLm-1, DLm, and DLm + 1.

The color filter layer 220 is formed on the second base substrate 201 on which the light blocking layer is formed. The color filter layer 220 includes red, green, and blue filter patterns corresponding to each pixel unit.

The color filter layer 220 is removed from a portion of the color filter layer 220, that is, a portion of the color filter layer 220 corresponding to the reflective region RA, to form a light hole LH.

The organic layer 230 is formed on the color filter layer 220, and the common electrode layer 240 is formed on the organic layer.

The liquid crystal layer 300 has an arrangement angle changed by an electric field formed between the display substrate 100 and the counter substrate 200, and displays an image by the luminance of light transmitted therethrough. The liquid crystal layer 300 preferably has a vertical alignment (VA) mode in which liquid crystal molecules are vertically aligned when the equipotential is formed on the display substrate 100 and the counter substrate 200.

[Table 1] is a table showing the relationship between the refractive index and the thickness of the protective film material.

    Example 1    Second example     formula  Wavelength of incident light     500 nm     500 nm     Refractive index     2.3     2.05  d = [λ / (2 * n2)]      thickness     1090Å    1220 yen

Referring to [Table 1], when the material of the protective film 159 is formed of titanium dioxide (TiO₂) having a refractive index of 2.3 as a first example, when the wavelength λ of the light incident on the reflective electrode is 500 nm, The thickness of the protective film is 1090 kPa by the formula shown in Table 1.

In addition, as a second example, when the material of the protective film 159 is formed of zirconium dioxide (ZrO₂) having a refractive index of 2.05, the thickness of the protective film is shown in Table 1 when the wavelength λ of the light incident on the reflective electrode is 500 nm. It is 1220 ms by a calculation formula.

As described above, by adjusting the thickness of the passivation layer, the first potential V1 of the reflection region and the second potential V2 of the transmission region are different from each other, thereby maintaining the single cell gap structure, thereby realizing a double electrode structure.

Therefore, in the conventional double electrode structure, the mask process is additionally required twice to form an insulating film on the color filter substrate. However, the present invention can obtain the same effect by only the mask process 1 by forming a protective film on the display substrate. Therefore, the manufacturing process of the reflection-transmissive liquid crystal display device can be simplified.

4A to 4C are process diagrams for describing a manufacturing method of the counter substrate 200 illustrated in FIG. 3.

First, referring to FIGS. 3 and 4A, the opposing substrate 200 includes a second base substrate 201, and the second base substrate 201 is preferably a glass substrate made of a transparent material.

The black matrix pattern 210, which is the light blocking layer, is formed on an upper surface of the second base substrate 201. The black matrix pattern 210 may be formed of a chromium thin film, a chromium oxide thin film, and a black organic thin film having substantially the same light absorption as the chromium thin film.

The black matrix pattern 210 is formed by patterning a chromium thin film, a chromium oxide thin film and a black organic thin film by a photo-etch process. . The patterned black matrix pattern 210 defines an internal space corresponding to the pixel portion of the display substrate 100.

Next, referring to FIGS. 3 and 4B, the color filter layer 220 is formed on the second base substrate 201 in an inner space defined by the black matrix pattern 210. The color filter layer 220 includes a red filter pattern, a green filter pattern, and a blue filter pattern. In detail, the red filter pattern forms a red photoresist layer and is patterned to form a red filter pattern, followed by sequentially forming a green filter pattern and a blue filter pattern.

Subsequently, a portion of the color filter layer 220 corresponding to the reflective area RA of the display substrate 100 is removed to form a light hole LH, and the color filter layer 220 corresponding to the transmission area TA. The thickness of R is relatively thicker than the color filter layer 220 of the reflective area RA to compensate for the color reproducibility of the transmission area TA to substantially equal the color reproducibility of the transmission area TA and the reflection area RA. do.

Finally, referring to FIGS. 3 and 4C, an overcoat layer 230 is formed on the color filter layer 220. The common electrode layer 240 is formed by forming a transparent conductive material on the second base substrate 201 on which the overcoat layer 230 is formed. The transparent conductive material includes indium tin oxide (ITO) and indium zinc oxide (IZO) materials.

5A through 5C are process diagrams for describing a method of manufacturing the display substrate illustrated in FIG. 3.

3 and 5A, the display substrate 100 includes a first base substrate 101.

Source wires DLm-1, DLm, DLm + 1 and gate lines GLn-1, GLn, first and second switching elements 155 and 165 are disposed on the first base substrate 101. The storage common wiring 170 is formed, respectively.

Passivation is performed on the first base substrate 101 on which the source and drain electrodes 153, 154, 163, and 164 of the switching elements 155 and 165 and the source wirings DLm-1, DLm, and DLm + 1 are formed. Layer 103 is formed.

3 and 5B, after the organic layer 104 is formed on the first base substrate 101 on which the passivation layer 103 is formed, an organic layer (part of the drain electrodes 154 and 164) is formed. 104 is etched to form contact holes 156 and 166.

Thereafter, a transparent conductive material is formed and patterned on the organic layer 104 to form pixel electrodes 157 and 167. In general, each pixel electrode may be formed over an entire pixel area or in a partial area corresponding to the transmission area. The transparent conductive material includes indium tin oxide (ITO) and indium zinc oxide (IZO) materials.

3 and 5C, a reflective material is formed on the pixel electrodes 157 and 167 and patterned to form the reflective electrodes 158 and 168 in the reflective region. The reflective material is a kind of metal material that reflects light, and includes aluminum and aluminum-neodymium alloys.

Thereafter, a passivation layer 159 is formed on the reflective electrodes 158 and 168. The passivation layer is formed of an insulating material larger than the refractive index of the upper liquid crystal layer (not shown), and the insulating material includes titanium dioxide (TiO₂) and zirconium dioxide (ZrO₂).

On the other hand, due to the insulating property of the protective film 159, the pixel voltage applied to the liquid crystal layer is different in the reflection region and the transmission region. By adjusting the thickness of the passivation layer 159, the phase difference of the liquid crystal layer 300 of the transmission area TA is designed such that the phase difference of the liquid crystal layer 300 of the reflection area RA becomes λ / 4 with respect to λ / 2. do.

The present invention may implement a double electrode structure while maintaining a single cell gap structure by varying the potential applied to the liquid crystal layers of the reflective and transmissive regions by adjusting the thickness of the protective layer 159.

Therefore, in the conventional double electrode structure, the mask process is additionally required twice to form an insulating film on the color filter substrate. However, the present invention can obtain the same effect by only the mask process 1 by forming a protective film on the display substrate. Therefore, the manufacturing process of the reflection-transmissive liquid crystal display device can be simplified.

In addition, while having a single cell gap structure, it is possible to improve the reflected light characteristics by providing optical characteristics similar to those of the double cell gap structure.

As described above, according to the present invention, a reflective-transmissive liquid crystal display device having a double electrode structure may be formed by forming a protective film 159 having a predetermined thickness as an insulating material on the reflective electrode 158 in the reflective-transmissive liquid crystal display panel. Can be.

 Accordingly, in the case of the existing double electrode structure, when the insulator is introduced into the color filter substrate, the mask process is additionally required twice, but the present invention can obtain the same effect by using only the mask process once by forming a protective film on the display substrate. Therefore, the manufacturing process of the reflection-transmissive liquid crystal display device can be simplified.

In addition, by using the relationship between the refractive index and the thickness of the protective film material, the liquid crystal layer provided in the reflective region RA and the liquid crystal layer provided in the transmission region TA have different potentials, thereby improving both reflectance and transmittance. Let's do it.

Although described above with reference to the embodiments, those skilled in the art can be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below. I can understand.

Claims (9)

A pixel portion having a transmission region for transmitting the first light and a reflection region for reflecting the second light; A switching element formed in the pixel portion and connected to a gate line and a source line; A transparent electrode electrically connected to the switching element and formed in the pixel portion; A reflective electrode formed on the transparent electrode corresponding to the reflective region; And And a passivation layer formed of an insulating material on the reflective electrode so as to have different potentials of the reflective and transmissive regions. The reflective-transmissive display substrate of claim 1, wherein the reflective electrode is formed of a silver-molybdenum alloy. The reflective-transmissive display substrate of claim 1, wherein the insulating material comprises TiO 2 and ZrO 2. A pixel portion having a transmission region that transmits first light and a reflection region that reflects second light, a switching element formed on the pixel portion, a transparent electrode electrically connected to the switching element, and the reflection portion formed on the pixel portion A display substrate including a reflective electrode formed on the transparent electrode corresponding to an area and a protective film formed of an insulating material on the reflective electrode; And And a counter substrate coupled to the display substrate to accommodate a liquid crystal layer and having a common electrode formed on a surface facing the transparent electrode and the reflective electrode. The liquid crystal display panel according to claim 4, wherein the liquid crystal layer is in VA mode. The reflection-transmissive liquid crystal display panel of claim 4, wherein a first potential difference between the reflective electrode of the reflective region and the common electrode and a second potential difference between the transparent electrode of the transparent region and the common electrode are different from each other. 7. The reflection-transmissive liquid crystal display panel of claim 6, wherein the second potential difference is greater than the first potential difference. The reflective-transmissive liquid crystal display panel of claim 4, wherein the reflective electrode is formed of silver-molybdenum alloy. The reflection-transmissive liquid crystal display panel of claim 4, wherein a refractive index of the passivation layer is larger than that of the liquid crystal layer.

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