KR100989262B1 - Liquid Crystal Display Device and the fabrication method thereof - Google Patents

Abstract

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having a color filter substrate having improved flatness and a method of manufacturing the same.

The present invention can form a stable alignment by improving the flatness by forming the overcoat layer using the back exposure to the step generated when the black matrix is formed in the color filter substrate of the liquid crystal display device, the light leakage in the black state of the liquid crystal panel This does not occur and implements a good picture quality.

In addition, since the present invention uses a resin black matrix as a photo mask, the overcoat layer can be accurately patterned, and the back exposure machine for pattern formation does not require an expensive mask alignment function, thereby reducing costs. .

Black Matrix, Back Exposure, Overcoat Layer

Description

Liquid crystal display device and manufacturing method thereof

1 is a three-dimensional view of a partial region of a general liquid crystal display.

2 is a schematic view of a portion of a color filter substrate of a conventional liquid crystal display;

3A to 3F illustrate a color filter substrate for a liquid crystal display according to the present invention.

<Description of Signs of Major Parts of Drawings>

300: substrate 310: black matrix

320: overcoat layer 330: common electrode

340: alignment film 350: rubbing cloth

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having a color filter substrate having improved flatness and a method of manufacturing the same.

Recently, with the development of the electronics industry, display devices, which have been limitedly used for TV CRTs, have been widely used in personal computers, notebooks, wireless terminals, automobile dashboards, electronic displays, etc., and can transmit large amounts of image information with the development of information and communication technology. As a result, the importance of the next generation display device that can process and implement this is increasing.

Such next-generation display devices should be able to realize light and small, high brightness, large screen, low power consumption, and low cost. In response, recently, liquid crystal display devices (LCDs), plasma display panels (PDPs), and electro luminescent displays (ELDs) have been developed. And various flat panel display devices such as a vacuum fluorescent display (VFD) have been studied, and one of them has recently attracted attention.

The liquid crystal display device is superior in resolution to other flat panel display devices, and exhibits characteristics such that the response speed is faster than that of a CRT when a moving image is realized.

In addition, the liquid crystal display device has excellent characteristics such as high brightness, high contrast, low power consumption, and so is used in a wide range of fields such as a desktop computer monitor, a notebook computer monitor, a TV receiver, a vehicle-mounted TV receiver, and navigation.

In general, a liquid crystal display device is formed by arranging two substrates having electrodes formed on one side thereof so that the surfaces on which the two electrodes are formed face each other, injecting a liquid crystal material between the two substrates, and then applying voltage to the two electrodes. By moving the liquid crystal molecules by the electric field is a device that represents the image by the transmittance of light that varies accordingly.                         

Such a liquid crystal display device may be broadly divided into a liquid crystal panel displaying an image and a driving unit for applying a driving signal to the liquid crystal panel, wherein the liquid crystal panel includes first and second substrates bonded to each other with a predetermined space; It consists of a liquid crystal layer injected between the two substrates.

Usually, the liquid crystal panel has a structure in which a liquid crystal is filled between two glass substrates or a transparent plastic substrate. A transparent electrode (common electrode, pixel electrode) is formed on the substrate so that voltage can be applied to the liquid crystal. The transparent electrode serves to control the on / off by applying a voltage to the liquid crystal.

That is, the light transmission amount of the liquid crystal display device is controlled by the voltage applied to the transparent electrode, and displays characters / images by the optical shutter effect.

Among such liquid crystal display devices, an active matrix liquid crystal display device having a switching element capable of controlling voltage on / off for each pixel is attracting the most attention due to its excellent resolution and ability to implement video.

FIG. 1 is a three-dimensional view of a portion of a general liquid crystal display, and is shown centering on an active region defined as a region in which a liquid crystal is driven.

As shown, the upper and lower substrates 110 and 130 are spaced apart from each other by a predetermined distance, and the liquid crystal layer 150 is interposed between the upper and lower substrates 110 and 130.

A plurality of gates and data lines 132 and 134 cross each other on the lower substrate 130, and a thin film transistor T is formed at a point where the gates and data lines 132 and 134 cross each other. The pixel electrode 146 connected to the thin film transistor T is formed in the pixel area P defined as an area where the gate and the data lines 132 and 134 intersect.

Although not shown in the drawing, the thin film transistor T includes a gate electrode to which a gate voltage is applied, a source and drain electrode to which a data voltage is applied, and a channel for controlling voltage on / off by a difference between the gate voltage and the data voltage ( ch; channel).

In addition, the color filter layer 112 and the common electrode 116 are sequentially formed below the upper substrate 110.

Although not shown in detail in the drawing, the color filter layer 112 includes a color filter for transmitting only light of a specific wavelength band and a black matrix positioned at a boundary of the color filter to block light on an area where the arrangement of liquid crystals is not controlled.

In addition, upper and lower polarizers 152 and 154 are disposed on each outer surface of the upper and lower substrates 110 and 130 to transmit only light parallel to the polarization axis, and a backlight is provided under the lower polarizer 154 as a separate light source. light) is placed.

The liquid crystal display device uses a substrate that has undergone an array substrate manufacturing process for forming a switching element and a pixel electrode and a color filter substrate manufacturing process for forming a color filter and a common electrode, and a liquid crystal cell process that interposes liquid crystal between the two substrates. Completed through

The liquid crystal cell process may be characterized in that the process is relatively little compared to the array process or the color filter process. The whole process can be largely divided into an alignment layer forming process for forming the liquid crystal molecules, a cell gap forming process, a cell cutting process, and a liquid crystal injection process. After attaching the polarizing plates to the outside of the liquid crystal panel, the liquid crystal display device is completed by connecting the driving circuits.

On the other hand, there is a liquid crystal display of the FSC (Field Sequential Mode: FSC) mode that implements color without using a color filter pigment in the color filter substrate for a liquid crystal display device.

The liquid crystal display of the FSC mode is a driving method for forming an image by forming a light source frame in a backlight unit without a color filter pigment on a color filter substrate.

In the FSC mode liquid crystal display, only a black matrix and a common electrode are formed on the color filter substrate.

In this case, the black matrix used is formed by depositing chromium (Cr), which is a heavy metal, which is a metal material, and a chromium oxide layer, and using a material obtained by dispersing a black pigment such as carbon black in a photosensitive resin. There is a method of forming, and as a general black matrix material, a method of forming using chromium, which is a heavy metal, is used.

However, since chromium, which is a heavy metal, adversely affects the environment, the use regulations for it are being embodied, and a demand for a more environmentally friendly resin black matrix is proposed.

Since the resin black matrix does not use chromium, which is a heavy metal, it is advantageous for environmental pollution, but light absorption is lower than that of the black matrix using metal, and thus a thicker film than the metal black matrix should be formed.

Therefore, since the flatness of the substrate is deteriorated by the resin black matrix formed on the color filter layer, there is a difficulty in improving even when an overcoat layer is formed for planarization.

2 is a view schematically illustrating a part of a color filter substrate of a conventional liquid crystal display.

As shown in FIG. 2, the liquid crystal display does not form a color filter on the color filter substrate 200, and thus the overcoat layer 220 is formed after the black matrix 210 is formed.

In this case, when the common electrode 230 and the alignment layer 240 are formed on the overcoat layer 220, and the alignment process is performed, the rubbing cloth 250 may be used during the rubbing process due to the step of the black matrix 210. The orientation shaded portion is formed at the portion which is not touched.

Since the liquid crystal alignment is not performed in the alignment shadow part, light leakage occurs in a black state of the liquid crystal display panel.

According to the present invention, a flatness is improved by forming an overcoat layer using a back exposure of a step generated when a black matrix is formed in a color filter substrate of a liquid crystal display device having a separate light filter array for color filters to form a stable orientation. An object of the present invention is to provide a liquid crystal display device and a method for manufacturing the same.

In order to achieve the above object, a liquid crystal display device according to the present invention defines a plurality of pixel regions and includes a first substrate including a thin film transistor, a second substrate facing the first substrate, and a liquid crystal formed between the first and second substrates. A second substrate of a liquid crystal display comprising a layer, comprising: a black matrix pattern formed on the substrate; An overcoat layer patterned between the black matrix patterns; A common electrode formed on the black matrix and the overcoat layer; An alignment layer formed on the common electrode; And a light source array having first to third light sources irradiated onto the substrate and emitting red, green, and blue light, respectively.

The light source array divides one frame section into at least three sub frame sections so that the first to third light sources are sequentially turned on in each sub frame section.

The black matrix is characterized in that the carbon black (carbon black) series.

The step of the black matrix is characterized in that 0.3 ~ 0.8 ㎛.

The overcoat layer is made of a photosensitive resin.

The overcoat layer is characterized in that it is patterned by a back exposure method.

In addition, in order to achieve the above object, a method of manufacturing a liquid crystal display device according to the present invention includes a first substrate including a plurality of pixel regions and including a thin film transistor, a second substrate facing the first substrate, and a first and a second substrate. A method of manufacturing a second substrate of a liquid crystal display device comprising a liquid crystal layer formed between substrates, the method comprising: forming a resin black matrix pattern on the substrate; Applying a photosensitive insulating material onto the black matrix; Exposing at the back side of the substrate; Developing the photosensitive insulating material to form a patterned overcoat layer; Forming a common electrode on the overcoat layer; Forming an alignment layer on the common electrode; And forming a light source array having first to third light sources irradiated onto the substrate and emitting red, green, and blue light, respectively.

The photosensitive insulating material is characterized in that it has a negative (negative) characteristics.

The black matrix is characterized in that the carbon black (carbon black) series.

The photosensitive insulating material is characterized in that the coating as the thickness of the black matrix.

Hereinafter, specific embodiments of the liquid crystal display according to the present invention will be described with reference to the accompanying drawings.

The liquid crystal display according to the present invention relates to a liquid crystal display of a field sequential mode (FSC) mode capable of realizing color without using color filter pigments.

The liquid crystal display of the FSC mode is a driving method in which an image is formed by forming a light source frame in a backlight unit without a color filter pigment on a color filter substrate.

The FSC driving method divides the entire frame on the panel into three subframes of red (R), green (G), and blue (B). Each of these subframes is divided into a data writing time, a liquid crystal response time, and a backlight emission time. As a result, the time for turning on the backlight according to each color is the time except for the data writing time and the liquid crystal response time.

Another FSC driving method is a method using split driving, in which an area of the entire panel displaying an image is divided into N in the horizontal direction and driven.

The backlight unit of the FSC liquid crystal display device basically includes a plurality of LEDs that generate red light, green light, and blue light as point light sources, and liquid crystal is injected between two substrates on the upper surface of the backlight unit to display an image. The panel is further provided.

In the FSC mode liquid crystal display, only a black matrix and a common electrode are formed on the color filter substrate.

3 is a view showing a color filter substrate for a liquid crystal display according to the present invention.

First, as shown in FIG. 3A, the black matrix 310 is patterned and formed on the transparent insulating substrate 300.

The black matrix 310 is formed in a predetermined pattern to shield light passing through a reverse tilt domain formed around the pixel electrode. The black matrix 310 is formed of a carbon-based organic material. Is used.

Subsequently, as shown in FIG. 3B, in order to improve the flatness of the substrate 300 on the substrate 300 on which the black matrix 310 is formed, the overcoat layer 320 is formed by using a photosensitive resin having insulating properties. Form.

In this case, the overcoat layer 320 may also generate a step due to the step generated by the black matrix 310.

As shown in FIG. 3C, the black matrix 310 is used as a photo mask to planarize the overcoat layer 320 which is a photosensitive resin coated on the substrate on which the black matrix 310 is formed. Back exposure is performed.

The back exposure as described above does not require expensive mask alignment equipment, so the equipment has a low cost and a simple process.

When the light is exposed from the back surface of the substrate on which the black matrix 310 is formed, the light passing through the transparent substrate 300 is absorbed at the position where the black matrix 310 is formed, and at the portion where the black matrix 310 is not formed. Passed as it is to pass through the photosensitive resin.

The photosensitive resin is cured by the irradiated light, and then the substrate is planarized through a developing process and a thermal curing process.

Here, since the present invention uses the resin black matrix 310 directly as a mask, an error due to miss-alignment of the mask does not occur.

Preferably, the thickness of the overcoat layer to be applied on the substrate is formed to be similar to the thickness of the black matrix, so that the overcoat layer remaining between the thickness of the black matrix 310 and the black matrix pattern after the planarization process using the back exposure ( The thickness of 320 is to be similar.

As described above, the photosensitive resin film, which is the overcoat layer 320, is cured only between the black matrix 310 patterns by the back exposure to planarize the substrate as shown in FIG. 3D.

Subsequently, as shown in FIG. 3E, the common electrode 330 is formed.

The common electrode 330 is made of a transparent conductive electrode, and formed of a material such as indium tin oxide (ITO), indium zinc oxide (IZO), or indium tin zinc oxide (ITZO).

3F, the alignment layer 340 is formed in the final process of the color filter substrate.

In this case, the alignment film 340 is formed by printing polyimide (PI), which is an alignment film raw material solution, on the upper surface of the substrate using an alignment film printing apparatus.

Next, high temperature heat is added to the alignment film raw material solution to dry and cure the solvent.

Subsequently, the alignment film rubbing process is performed by rubbing the surface of the baked alignment film 340 with the rubbing cloth 350 in a predetermined direction using a rubbing device to form a groove.                     

At this time, since the said color filter substrate is planarized by back exposure, the orientation shading part does not generate | occur | produce at the time of the orientation processing by the above-mentioned rubbing method, and uniform orientation is achieved.

Although the present invention has been described in detail through specific embodiments, this is for explaining the present invention in detail, and a liquid crystal display and a method of manufacturing the same according to the present invention are not limited thereto. It is apparent that modifications and improvements are possible by those skilled in the art.

According to the present invention, a liquid crystal display device having a light source array serving as a separate color filter is used to pattern an overcoat layer by using backside exposure to planarize the color filter substrate and stably and uniformly align the light leakage in the black state of the liquid crystal panel. There is an effect of achieving a good image quality does not occur.

In addition, since the present invention uses a resin black matrix as a photo mask, the overcoat layer can be accurately patterned, and the back exposure machine for pattern formation does not require an expensive mask align function, which is inexpensive and reduces costs. There is.

Claims (10)

A liquid crystal display device comprising: a first substrate including a plurality of pixel regions and including a thin film transistor; a second substrate opposing the second substrate; and a liquid crystal layer formed between the first and second substrates. A light source array irradiating the second substrate and having first to third light sources emitting red, green and blue light, respectively; A black matrix pattern formed on the second substrate; An overcoat layer patterned between the black matrix patterns; A common electrode formed on the black matrix and the overcoat layer; And And an alignment layer formed on the common electrode. The method of claim 1, The light source array divides one frame section into at least three sub frame sections so that the first to third light sources are sequentially turned on in each sub frame section. The method of claim 1, And wherein the black matrix is a carbon black series. The method of claim 1, And the step of the black matrix is 0.3 to 0.8 [mu] m. The method of claim 1, The overcoat layer is made of a photosensitive resin. The method of claim 1, The overcoat layer is patterned by a back exposure method. 1. A method of manufacturing a liquid crystal display device comprising a first substrate including a plurality of pixel regions and including a thin film transistor, an opposite second substrate, and a liquid crystal layer formed between the first and second substrates. Forming a light source array having first to third light sources irradiated to the second substrate and emitting red, green and blue light, respectively; Forming a resin black matrix pattern on the second substrate; Applying a photosensitive insulating material onto the black matrix; Performing exposure on the back side of the second substrate; Developing the photosensitive insulating material to form a patterned overcoat layer; Forming a common electrode on the overcoat layer; And Forming an alignment layer on the common electrode; and manufacturing a liquid crystal display device. The method of claim 7, wherein The photosensitive insulating material has a negative characteristic (negative) characterized in that the manufacturing method of the liquid crystal display device. The method of claim 7, wherein The black matrix is a method of manufacturing a liquid crystal display device, characterized in that the carbon black (carbon black) series. The method of claim 7, wherein And the photosensitive insulating material is coated by the thickness of the black matrix.

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