KR100692689B1 - Transflective type liquid crystal display - Google Patents

Abstract

The present invention discloses a semi-transmissive liquid crystal display device which reduces the number of mask processes and improves the difference in color filter characteristics between the reflecting part and the transmitting part. The semi-transmissive liquid crystal display device of the present invention is a semi-transmissive liquid crystal display device having a reflective part for displaying an image with ambient light and a transmissive part for displaying an image with light of a backlight, having a reflective electrode, and having a lower substrate facing each other. Upper substrate; A thin film transistor formed in place on the lower substrate and including a gate electrode, a channel layer, and a source / drain electrode; A reflective electrode formed on the reflective portion of the lower substrate; A color filter resin film formed on the lower substrate such that thicknesses of the reflecting part and the transmitting part are different from each other; A pixel electrode formed to contact the thin film transistor on the curly filter resin film; A common electrode formed on the upper substrate; And a liquid crystal layer interposed between the lower substrate and the upper substrate, wherein the reflective electrode is formed together with a source / drain electrode, and the color filter resin film has a cell gap in the reflection part 3/2 times greater than a cell gap in the transmission part. Characterized in that the thickness to be large.

Description

Transflective type liquid crystal display

1 is a cross-sectional view showing a conventional transflective liquid crystal display device.

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

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

Explanation of symbols on the main parts of the drawings

1: lower substrate 2: gate electrode

3: gate insulating film 4: channel layer

5: ohmic contact layer 6: source electrode

7: drain electrode 8: protective film

9 pixel electrode 10 resin film

10a: color filter resin film 12, 12a: reflective electrode

14: upper substrate 16: common electrode

20: liquid crystal layer 30: slit

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 the number of mask processes is reduced and the color filter characteristic difference between the reflection part and the transmission part is improved.

The liquid crystal display may be classified into two types: a transmissive liquid crystal display using a backlight as a light source and a reflective liquid crystal display using natural light as a light source.

Since the transmissive liquid crystal display uses a backlight as a light source, it can implement a bright image even in a dark environment, but has a disadvantage in that power consumption is high by using a backlight. On the other hand, the reflective liquid crystal display device consumes a small amount of power because it uses natural light in the surrounding environment without using a backlight, but has a disadvantage in that it is impossible to use it in a dark environment.

Therefore, a semi-transmissive liquid crystal display device has been proposed to solve the above problems. Since the transflective liquid crystal display device can use both a reflection type and a transmissive type as needed, it has a relatively low power consumption and can be used even in a dark environment.

1 is a cross-sectional view of a conventional transflective liquid crystal display device, and as shown, the transflective liquid crystal display device is divided into a reflecting portion and a transmissive portion, and as a whole, the reflecting portion as compared with a conventional transmissive liquid crystal display device. Has a structure in which a process of forming a reflecting plate is added.

In the transflective liquid crystal display device, the reflecting portion and the transmissive portion are visually recognized by turning on / off the backlight, and the cell gap of the transmissive portion generally has a value approximately twice that of the cell gap of the reflective portion.

In Fig. 1, reference numeral 1 denotes a lower substrate, 2 a gate electrode, 3 a gate insulating film, 4 a channel layer (a-Si), 5 a ohmic contact layer (n + a-Si), and 6 a Source electrode, 7 drain electrode, 8 protective film, 9 pixel electrode, 10 resin film, 11 buffer film, 12 reflective electrode, 14 upper substrate, 15 color filter layer, 16 Denotes a common electrode, 20 denotes a liquid crystal layer, dr denotes a cell gap in a reflecting portion, and dt denotes a cell gap in a transmissive portion, respectively.

However, the above-mentioned conventional transflective liquid crystal display device has to undergo a 5-mask process, that is, a gate mask process, an active mask process, an S / D mask process, a via hole mask process, and an ITO mask process to form a transmissive portion. In addition, since the two-mask process for the resin film patterning process and the reflective electrode forming process must be additionally performed to form the reflecting part, approximately seven mask processes should be performed, and the mask process is a photosensitive film coating and exposure by itself. And the development process and the etching process, the overall process is very complicated, and the mask process is further performed as compared with the manufacturing method of the transmissive and reflective liquid crystal display device in which 5 or 6 mask processes are usually performed. There is a problem that the manufacturing cost and time-consuming.

In addition, since the light passes through the color filter layer twice in the reflection part, the conventional transflective liquid crystal display has a problem in that the color filter characteristic difference occurs between the reflection part and the transmission part.

In addition, the conventional transflective liquid crystal display device has a problem in that the driving is difficult because the cell gap difference between the reflecting unit and the transmitting unit is different.                         

Meanwhile, in the related art, COA (Color filter On Aray) technology is introduced to replace the conventional resin film with the color filter resin film, and attempts to solve the problem in which the color filter characteristic difference occurs.

However, this method is basically a structure that must adjust the cell gap of the reflecting part and the transmitting part, so it is not possible to replace the existing resin film with the color filter resin, and therefore, a problem that a separate color filter must be used separately for the reflecting part of the upper substrate. There is this.

Accordingly, an object of the present invention is to provide a semi-transmissive liquid crystal display device, which has been devised to solve the conventional problems as described above, which reduces manufacturing cost and time by reducing the number of mask processes.

In addition, another object of the present invention is to provide a transflective liquid crystal display device in which the difference in color filter characteristics between the reflecting unit and the transmitting unit is improved.

In order to achieve the above object, the present invention is a semi-transmissive liquid crystal display device having a reflecting electrode having a reflecting electrode for displaying an image with ambient light and a transmissive portion for displaying an image with light of a backlight, wherein A substrate and an upper substrate; A thin film transistor formed in place on the lower substrate and including a gate electrode, a channel layer, and a source / drain electrode; A reflective electrode formed on the reflective portion of the lower substrate; A color filter resin film formed on the lower substrate such that thicknesses of the reflecting part and the transmitting part are different from each other; A pixel electrode formed to contact the thin film transistor on the curly filter resin film; A common electrode formed on the upper substrate; And a liquid crystal layer interposed between the lower substrate and the upper substrate, wherein the reflective electrode is formed together with a source / drain electrode, and the color filter resin film has a cell gap in the reflection part 3/2 times greater than a cell gap in the transmission part. Provided is a transflective liquid crystal display device, characterized in that it is formed to a thickness to be large.

In addition, the transflective liquid crystal display device of the present invention may include slits alternately on a vertical line such that the pixel electrode and the common electrode implement a wide viewing angle VA mode.

(Example)

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

2 is a cross-sectional view illustrating a transflective liquid crystal display device according to an exemplary embodiment of the present invention. Here, the same parts as in Fig. 1 are designated by the same reference numerals.

As shown, the semi-transmissive liquid crystal display according to the present invention is not arranged in which the reflective electrode 12a of the reflector is disposed on the top of the lower substrate 1, but is disposed on the same layer as the source / drain electrodes 6 and 7. It is a structure.

In addition, the transflective liquid crystal display device of the present invention has a COA structure in which the color filter is formed on the lower substrate 1 instead of the upper substrate 14, and the color filter resin film 10a is optimized for the cell gap between the reflecting portion and the transmitting portion. And different thicknesses to eliminate color filter characteristic differences. Preferably, the color filter resin film 10a is formed to a thickness such that the cell gap dr of the reflecting part has a value 3/2 times larger than the cell gap dt of the transmissive part by adjusting the exposure amount when forming the color filter resin film 10a.

According to the semi-transmissive liquid crystal display device of the present invention, since the reflective electrode 12a is formed together when the source / drain electrodes 6 and 7 are formed, one mask process for forming the reflective electrode 12a is performed. In addition, since the color filter resin process replaces the conventional resin process, one mask process may be further omitted. Accordingly, by omitting a total of two mask processes, the process can be simplified as much as the corresponding process and the manufacturing cost can be reduced.

In addition, since the transflective liquid crystal display device of the present invention has a color filter, that is, a COA structure in which the color filter resin film 10a is disposed on the lower substrate 1 instead of the upper substrate 14, the transmissive portion as well as the reflective portion In this case, the thickness of light passing through the color filter resin film 10a may be the same, and thus, the difference in color filter characteristics between the reflecting portion and the transmitting portion does not occur.

In addition, the transflective liquid crystal display device of the present invention forms the color filter resin film 10a with a thickness such that the cell gap dr in the reflecting portion has a value 3/2 times larger than the cell gap dt in the transmissive portion. Accordingly, the light passing through the liquid crystal layer 20 may be optimized by optimizing the phase delay of the reflector and the phase delay of the transmissive part, thereby improving the difference in characteristics between the reflecting part and the transmissive part. It can be solved and has an advantage in terms of driving.

In detail, the light passing through the liquid crystal layer 20 in the transmissive portion reflects the external light passing through the liquid crystal layer 20 in the reflecting portion if the pass length is dt and has a phase delay (Δn * d) of λ / 2. The light reflected by the positive electrode 12a and again passing through the liquid crystal layer 20 passes through the liquid crystal layer 20 and has a length of 2dr, that is, 3dt, and has a phase delay of 3λ / 2. Therefore, the phase difference between the light reflected by the reflecting portion and passing through the liquid crystal layer 20 and the light passing through the liquid crystal layer 20 of the transmitting portion is 3λ / 2-λ / 2 = λ. In the above, the light passing through the liquid crystal layer 20 of the reflecting portion and the light passing through the liquid crystal layer 20 of the transmitting portion have a phase difference of λ indicates the same phase. Therefore, the light passing through each of the reflecting portion and the transmitting portion has the same phase delay, so that the phase delay difference does not appear between the light passing through the reflecting portion and the transmitting portion, respectively .

Hereinafter, a method of manufacturing the transflective liquid crystal display according to the present invention described above will be described with reference to FIG. 2.

First, a gate bus line (not shown) including the gate electrode 2 is formed on the lower substrate 1 made of a transparent insulating substrate such as a glass substrate by using a first mask process. Then, a gate insulating film 3, an a-Si film and an n + a-Si film are sequentially deposited on the entire surface of the lower substrate 1 so as to cover the gate electrode 2 and the gate bus line.

Next, the n + a-Si film and the a-Si film are patterned using a second mask process, thereby forming an active layer. Thereafter, a source / drain metal film is deposited on the substrate, and then the source / drain metal film is patterned using a third mask process to form a data bus line including the source / drain electrodes 6 and 7. In addition, the reflective electrode 12a is formed in the substrate region corresponding to the reflective portion. Subsequently, the n + a-Si film portion on the channel portion is etched through the transient etching to form the ohmic contact layer 5, and the channel layer 4 is formed thereunder, thereby forming a thin film transistor.

Here, in the related art, a separate mask process is performed to form the reflective electrode 12a, but the present invention is formed together when the source / drain electrodes 6 and 7 are formed, thereby reducing one mask process. In addition, the process can be simplified and the manufacturing cost can be reduced.

Subsequently, in a state in which the protective film 8 is formed on the substrate resultant, the protective film 8 is etched through a fourth mask process to form a via hole exposing the source electrode 6 of the thin film transistor. Then, after applying the color filter resin on the protective film 8, the color filter resin is exposed and developed to form a color filter resin film 10a having different thicknesses between the reflecting portion and the transmitting portion. At this time, the color filter resin film 10a has a thickness for optimizing the phase delay in the reflector and the phase delay in the transmissive part as described above, for example, a thickness such that the cell gap of the reflector is 3/2 times larger than the cell gap of the transmissive part. To form.

Here, the color filter resin film 10a replaces the conventional resin film, and the color filter resin process for forming the color filter resin film 10a is a mask that is usually used in the process of forming a color filter on the upper substrate. Since it is performed using as it is, a separate mask process is not added, and in particular, the color filter resin process can replace the conventional resin process, thereby reducing one mask process, thereby simplifying the corresponding process and reducing the manufacturing cost. Savings can be obtained.

 Next, after depositing an ITO film for the pixel electrode on the via hole and the color filter resin film 10a, the ITO film is patterned by using a fifth mask process to form the pixel electrode 9, and thereby, an array substrate. To complete the production.

Subsequently, the lower substrate 1 manufactured through the above-described process and the upper substrate 14 formed by forming only the common electrode 16 of the ITO without color filters are bonded to each other under the interposition of the liquid crystal layer 20. This completes the transflective liquid crystal display device of the present invention.

3 is a cross-sectional view of a transflective liquid crystal display according to another exemplary embodiment of the present invention. As illustrated, the transflective liquid crystal display according to the present embodiment includes a pixel electrode 9 and a common electrode 16. The slits 30 are staggered from each other in a vertical line on predetermined portions.

In this way, since the liquid crystal molecules are arranged in different directions with respect to the slit 30, multi-domains can be formed, and thus, a VA mode having a wide viewing angle, for example, PVA (Patterned) Modes such as vertical alignment (MVA) and multidomain vertical alignment (MVA) may be implemented to improve display characteristics of the liquid crystal display.

As described above, the present invention provides a process simplification by forming the reflective electrode together with the reflective part when forming the data bus line including the source / drain electrodes, and by replacing the conventional resin process with the color filter resin process. In addition, the manufacturing cost can be reduced by reducing the number of masks.

In addition, the present invention improves the difference in characteristics between the reflecting portion and the transmitting portion by allowing the cell gap of the reflecting portion to have a value 3/2 times larger than the cell gap of the transmitting portion so that the phase difference in the reflecting portion and the phase delay in the transmitting portion are the same. Accordingly, the characteristics and the reliability of the liquid crystal display may be improved.

As mentioned above, although the present invention has been illustrated and described with reference to specific embodiments, the present invention is not limited thereto, and the following claims are not limited to the scope of the present invention without departing from the spirit and scope of the present invention. It can be easily understood by those skilled in the art that can be modified and modified.

Claims (2)

A semi-transmissive liquid crystal display device having a reflecting unit including a reflecting electrode for displaying an image with ambient light and a transmitting unit for displaying an image with light of a backlight. A lower substrate and an upper substrate disposed to face each other; A thin film transistor formed in place on the lower substrate and including a gate electrode, a channel layer, and a source / drain electrode; A reflective electrode formed on the reflective portion of the lower substrate; A color filter resin film formed on the lower substrate such that thicknesses of the reflecting part and the transmitting part are different from each other; A pixel electrode formed to contact the thin film transistor on the color filter resin film; A common electrode formed on the upper substrate; And A liquid crystal layer interposed in a cell gap between the lower substrate and the upper substrate; The reflective electrode is formed together with the source / drain electrode, and the color filter resin layer is formed to have a thickness such that the cell gap at the reflecting part has a value 3/2 times larger than the cell gap at the transmitting part. LCD display device. The transflective liquid crystal display of claim 1, wherein the pixel electrode and the common electrode are provided with slits alternately on a vertical line to implement a VA mode of a wide viewing angle.

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