KR100726254B1 - Liquid crystal display device having shielding layer for blocking light incident from side - Google Patents

Abstract

A liquid crystal display element of the present invention includes a first substrate and a second substrate including a plurality of pixels, a liquid crystal layer formed between the first substrate and the second substrate, and a liquid crystal layer formed between the pixels of the first substrate and the second substrate And blocking the light transmitted to the adjacent pixels. The blocking layer is disposed along the black matrix. The blocking layer is made of a photopolymer and reflects the side light to improve the front brightness of the liquid crystal display.

Blocking film, side light, reflection, light leakage, luminance, photopolymer

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a liquid crystal display (LCD)

1 is a plan view showing a structure of a conventional liquid crystal display element.

FIG. 2A is a sectional view taken along the line I-I 'of FIG. 1; FIG.

2B is a sectional view taken along the line II-II 'in FIG.

3 is a sectional view showing a structure of a liquid crystal display element according to a first embodiment of the present invention.

4 is a cross-sectional view showing a structure of a liquid crystal display element according to a second embodiment of the present invention.

Description of the Related Art [0002]

105, 205: common electrode 107, 207: pixel electrode

120, 130, 220, 230: substrate 122, 222: gate insulating layer

124,224: protective layer 132,232: black matrix

140, 240: liquid crystal layer 150, 250: backlight

160,260; Barrier

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display (LCD), and more particularly, to a liquid crystal display device capable of preventing a light leakage phenomenon and improving brightness by blocking light transmitted to adjacent pixels by providing a light blocking film.

2. Description of the Related Art Recently, various portable electronic devices such as a mobile phone, a PDA, and a notebook computer have been developed. Accordingly, there is a growing need for a flat panel display device for a light and small size. As such flat panel display devices, a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED) and a vacuum fluorescent display (VFD) have been actively studied. However, Because of its implementation, liquid crystal display devices (LCDs) are now spotlighted.

Although these liquid crystal display devices have various display modes depending on the arrangement of liquid crystal molecules, liquid crystal display devices of TN mode are mainly used because of their advantages of easy monochrome display, quick response speed and low driving voltage. In such a TN mode liquid crystal display element, liquid crystal molecules aligned horizontally with the substrate are oriented substantially perpendicular to the substrate when a voltage is applied. Therefore, there is a problem that the viewing angle is narrowed when the voltage is applied due to the refractive index anisotropy of the liquid crystal molecules.

In order to solve such a viewing angle problem, liquid crystal display devices of various modes having a wide viewing angle characteristic have been proposed. Among them, liquid crystal display devices of a transverse electric field mode (In Plane Switching Mode) . The IPS mode liquid crystal display element forms at least one pair of electrodes arranged in parallel in a pixel to form a transversal electric field substantially parallel to the substrate, thereby aligning the liquid crystal molecules in a plane.

1 is a view showing a structure of a conventional IPS mode liquid crystal display device. As shown in Fig. 1, the pixels of the liquid crystal panel 1 are defined by the gate line 3 and the data line 4 arranged vertically and horizontally. Although only the (n, m) -th pixel is shown in the figure, n and m of the gate line 3 and the data line 4 are arranged in the liquid crystal panel 1, N x m pixels are formed over the entire area. A thin film transistor 10 is formed in a crossing region of the gate line 3 and the data line 4 in the pixel. The thin film transistor 10 includes a gate electrode 11 to which a scanning signal is applied from a gate line 3 and a semiconductor layer which is formed on the gate electrode 11 and is activated by a scanning signal to form a channel layer And a source electrode 13 and a drain electrode 14 formed on the semiconductor layer 12 and applied with an image signal through the data line 4 to apply an image signal inputted from the outside to the liquid crystal layer do.

In the pixel, a plurality of common electrodes 5 and pixel electrodes 7 arranged substantially in parallel with the data lines 4 are arranged. A common line 16 connected to the common electrode 5 is disposed in the middle of the pixel and a pixel electrode line 18 connected to the pixel electrode 7 is disposed on the common line 16, And overlaps with the common line 16. A storage capacitance is formed in the transverse electric field mode liquid crystal display element by overlapping the common line 16 and the pixel electrode line 18. [

As described above, in the configured IPS mode liquid crystal display element, the liquid crystal molecules are oriented substantially parallel to the common electrode 5 and the pixel electrode 7. A horizontal electric field substantially parallel to the liquid crystal panel 1 is generated between the common electrode 5 and the pixel electrode 7 when the thin film transistor 10 is operated and a signal is applied to the pixel electrode 7. [ Since the liquid crystal molecules rotate on the same plane along the transverse electric field, the grayscale inversion due to the refractive index anisotropy of the liquid crystal molecules can be prevented.

A conventional IPS mode liquid crystal display device having the above structure will be described in more detail with reference to FIGS. 2A and 2B.

As shown in FIG. 2A, a gate electrode 11 is formed on a first substrate 20, and a gate insulating layer 22 is formed over the entire surface of the first substrate 20. A semiconductor layer 12 is formed on the gate insulating layer 22 and a source electrode 13 and a drain electrode 14 are formed on the semiconductor layer 12 to form the thin film transistor 1. In addition, a passivation layer 24 is formed over the entire surface of the first substrate 20.

On the second substrate 30, a black matrix 32 and a color filter layer 34 are formed. The black matrix 32 serves to prevent light from leaking into a region where the liquid crystal molecules do not operate. As shown in the figure, the black matrix 32 is formed between the pixel region and the pixel (that is, the gate line and the data line Region). The color filter layer 34 is formed of R (Red), B (Blue), and G (Green) to realize actual colors. A liquid crystal layer 40 is formed between the first substrate 20 and the second substrate 30 to complete the liquid crystal panel 1.

A plurality of common electrodes 5 are formed on the first substrate 20 and a pixel electrode 7 and a data line 4 are formed on the gate insulating layer 22, A transverse electric field E is generated between the electrode 5 and the pixel electrode 7. Although not shown in the drawing, a polarizer is attached to the first substrate 20 and the second substrate 30 to transmit or block light in a specific direction transmitted through the liquid crystal layer 40. [ A backlight 50 is disposed under the first substrate 20 to supply light to the liquid crystal layer 40.

However, the following problems arise in the liquid crystal display device having such a structure. That is, the light emitted from the backlight 50 is emitted from the backlight 50 and is vertically incident on the liquid crystal layer 40 as well as incident at a predetermined angle. Generally, since different image signals are applied to each pixel, another electric field is applied to the liquid crystal layer of each pixel. Therefore, since the amount of light transmitted through the liquid crystal layer in each pixel is different, different images are displayed in each pixel.

When the light generated from the backlight 50 and incident on the liquid crystal layer 40 is incident on the liquid crystal layer 40 at a predetermined angle or more, the light transmitted through the pixel invades the adjacent pixel through the side surface of the pixel, In this case, since the light adjusted by the corresponding pixel is displayed on adjacent pixels (referred to as light leakage phenomenon), there is a problem that the image quality is deteriorated by displaying an unwanted image due to light leakage phenomenon in adjacent pixels.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a liquid crystal display device capable of preventing image quality deterioration due to light leakage phenomenon by blocking light penetrating adjacent pixels by providing a blocking film in a boundary region between pixels The purpose.

It is another object of the present invention to provide a liquid crystal display element capable of improving a front luminance of a pixel by providing a blocking film for reflecting light penetrating into adjacent pixels.

According to an aspect of the present invention, there is provided a liquid crystal display device including a first substrate and a second substrate including a plurality of pixels, a liquid crystal layer formed between the first substrate and the second substrate, And a blocking film formed between the pixels of the second substrate and shielding light transmitted to adjacent pixels.

The blocking layer is disposed along the black matrix. The blocking layer is made of a photopolymer and reflects the side light to improve the front brightness of the liquid crystal display.

The blocking layer may be formed on the first substrate or on the second substrate. The height of the blocking layer is determined according to the critical angle of light incident on the pixel. The critical angle is calculated based on the distance between the black matrixes, the cell gap, and the thickness of the first substrate and the layer formed on the second substrate. Meanwhile, the blocking layer may be formed at the same height as the cell gap to serve as a spacer for keeping the cell gap constant.

In the present invention, light transmitted through the liquid crystal layer generated in the backlight is prevented from penetrating into adjacent pixels, thereby preventing the image quality from deteriorating. In addition, according to the present invention, the light penetrating into the adjacent pixels is reflected to the corresponding pixel again, thereby preventing the deterioration of image quality and improving the luminance.

To this end, in the present invention, a blocking film for blocking the side light is provided between the pixel and the pixel, that is, the black matrix forming region where no image is displayed, thereby blocking light from penetrating into the adjacent pixel. The blocking layer is made of a photopolymer and shields incident side light and reflects the side light to the corresponding pixel.

The shielding film of the present invention is applicable to liquid crystal display devices of all possible display modes. Although the liquid crystal display element of the IPS mode is mainly described in the foregoing description and the following description, the liquid crystal display element of this mode is only an example of the present invention and is for convenience of explanation. Therefore, the present invention can be applied not only to the IPS mode but also to a TN (Twisted Nematic) mode or VA (Vertical Alignment) mode liquid crystal display device.

Hereinafter, a liquid crystal display device according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a cross-sectional view illustrating the structure of a liquid crystal display device according to a first embodiment of the present invention. As shown in the drawing, a plurality of common electrodes 105 are formed on a first substrate 120, and a gate insulating layer 122 is formed over the entire surface of the first substrate 120. A pixel electrode 107 is formed on the gate insulating layer 122 to form a transverse electric field with the common electrode 105 and a protective layer 124 is formed thereon.

The common electrode 105 is formed of a metal such as Al or an Al alloy or Cu, and the pixel electrode 107 is made of Cr, a Cr alloy, Mo, or the like. The common electrode 105 may be formed of a transparent conductive material such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide) and may be formed on the protective layer 124. The pixel electrode 107 may be formed of ITO or IZO And may be formed on the protective layer 124. The protective layer 124 may be formed of an inorganic material such as SiNx or SiOx, or an organic material such as BCB (Benzo Cyclo Butene) or photoacryl.

Although not shown, a gate electrode is formed on the first substrate 120, and a semiconductor layer and a source / drain electrode are disposed on the gate insulating layer 122 to form a thin film transistor.

The black matrix 132 is formed on the second substrate 130 in the image non-display region, for example, the thin film transistor arrangement region or the data line 104 and the upper region of the common electrode 105 disposed in the vicinity thereof. The reason that the common electrode 105 is disposed near the data line 104 is to shield the electric field generated by the data line 104 to prevent the transverse electric field from being distorted. The data line 104 serves as a reference for distinguishing a pixel from an adjacent pixel. As a result, the black matrix 132 is formed in a part of the pixel region (that is, the thin film transistor arrangement region and the common electrode arrangement region) and the boundary region between the pixel and the pixel.

The first substrate 120 and the second substrate 130 are bonded together by a sealing material and liquid crystal is injected between the first substrate 120 and the second substrate 130 to form a liquid crystal layer 140. A backlight 150 for generating light is disposed below the first substrate 120 to supply light to the liquid crystal layer 140.

Meanwhile, as shown in FIG. 3, a side light blocking layer 160 is formed on the protective layer 124 of the first substrate 120. The blocking layer 160 is formed between a pixel and a pixel, and blocks the light transmitted through the liquid crystal layer 140 of one pixel (light transmitted according to a signal of the pixel) from being transmitted to an adjacent pixel.

In addition, the blocking layer 160 is made of a material having a high reflectance such as a photo-polymer, and reflects light transmitted through the adjacent pixels to transmit the color filter layer 134 of the corresponding pixel.

Since the blocking layer 160 is formed in a region where the black matrix 132 is formed, the aperture ratio of the blocking layer 160 does not decrease. The light incident on the liquid crystal layer 140 of the pixel is transmitted through the color filter layer of the pixel and light incident at a predetermined angle is blocked by the black matrix 132 disposed at the boundary of the pixel. However, when light is incident on the corresponding pixel at a critical angle or less with respect to the surface of the first substrate 120, blocking can not be performed by the black matrix 132. Thus, by forming the blocking layer 160 as described above, Lt; / RTI >

Since the light incident on the pixel can block light incident at a critical angle? Or less, the height of the blocking layer 160 is determined according to the critical angle?. The critical angle is a distance from the first substrate 120 on which the common electrode 105 is formed to the black matrix 132 on which the size of one pixel (i.e., the distance between the black matrix of the pixel boundary) The height of the blocking film 160 (the height at which all the side light can be blocked) of the blocking film 160 is set to be a distance between black matrices of the pixel boundary (Or the end of the opposite outermost black matrix in the outermost light incidence region of the pixel) and the distance from the first substrate 120 to the black matrix 132 where the common electrode 105 is formed. The optimum height is a minimum height for blocking light. Therefore, if the blocking film is formed at an optimal height or more, side light can be effectively blocked.

By forming the blocking layer 160, it is possible to completely prevent light incident on one pixel from being transmitted to adjacent pixels. Accordingly, occurrence of a light leakage phenomenon in the adjacent pixels can be prevented. In addition, since the blocking layer 160 is formed of a photopolymer having a high reflectance, the light reflected by the blocking layer 160, that is, the light incident at a critical angle? Therefore, since the amount of light transmitted through the pixel is increased compared with the conventional one, the luminance (particularly the front luminance) is greatly improved.

Generally, the biggest drawback of a liquid crystal display device is that the luminance is low. This is because light generated from the backlight 150 is largely absorbed while passing through the polarizing plate, the liquid crystal layer, and the color filter layer. It is known that only about 33% of light generated from the backlight 150 is substantially output through the liquid crystal display element. In order to overcome such a low luminance, various studies have been made, such as increasing the lamp brightness of the backlight 150, but currently, satisfactory results have not been obtained. However, in the present invention, since the side light is reflected to improve the luminance, the problem of low luminance, which is the biggest disadvantage of the liquid crystal display element, can be easily solved.

4 is a view showing a structure of a liquid crystal display according to a second embodiment of the present invention. In the liquid crystal display device of the first embodiment, the side light blocking film 260 is formed on the second substrate 230 on the side where the side light blocking film is formed on the first substrate. Therefore, the liquid crystal display element of this embodiment and the liquid crystal display element of the first embodiment have the same structure except for the shielding film. Therefore, description of the same configuration as that of the first embodiment will be omitted, and mainly only the shielding film will be described.

As shown in FIG. 4, the side light blocking film 260 is disposed along the boundary of the pixel, that is, the black matrix 232. Although not shown in the drawing, an overcoat layer may be formed on the black matrix 232 and the color filter layer 234 to protect the color filter layer 234 and improve the flatness of the substrate. In this case, the blocking film 260 will be formed on the overcoat layer.

The shielding film 260 may be formed at an optimal height (i.e., a minimum height) as in the first embodiment, but may be formed to have the same height as the cell gap. (The shielding film 260 may be formed on the second substrate 230, The height may be more preferable in order to block light transmitted near the surface of the first substrate 220). When the shielding film 260 is formed at the same height as the cell gap, the shielding film 260 is made of a photopolymer. Thus, the spacers 260 for maintaining a constant cell gap between the first substrate 220 and the second substrate 230, it can serve as a spacer. That is, the shielding film 260 of the present invention not only shields the side light, but also maintains a constant cell gap of the liquid crystal display device. Therefore, a separate spacer (a ball spacer or a column spacer) is not required, and manufacturing cost can be reduced.

In view of this point of view, the present invention may be regarded as relating to a new column spacer. That is, it may be regarded as relating to the column spacer having the side light blocking function.

When the barrier layer 260 is formed to have the same height as the cell gap, the liquid crystal layer 240 may be formed by bonding the first and second substrates 220 and 230 to each other, Or may be formed by a dispensing method. That is, a shielding film 260 is formed on the second substrate 230, liquid crystal is directly dropped on the first substrate 220, and the first substrate 220 and the second substrate 230 are pressed to form the substrates 220 and 230, The liquid crystal layer 240 is formed by uniformly spreading the liquid crystal throughout.

As described above, in the present invention, by disposing the side light blocking film at the boundary of the pixels, the image quality can be prevented from being degraded and the luminance can be improved.

Although the IPS mode liquid crystal display device has been described with reference to the present invention, the present invention is not limited to the IPS mode liquid crystal display device, but may be applied to a TN mode or VA mode liquid crystal display device. In this case, only a pixel electrode and a common electrode are formed on the first substrate and the second substrate, respectively, instead of forming the common electrode and the pixel electrode on the same substrate, and a blocking film is formed at the boundary of pixels along the black matrix The basic features are the same in liquid crystal display elements of all display modes. Accordingly, the present invention is not limited to a specific display mode or a specific structure, but may be applicable to all possible display modes and structures.

 As described above, according to the present invention, it is possible to prevent light from entering adjacent pixels by forming a blocking film between the pixel and the pixel, thereby effectively preventing image quality degradation due to light leakage to adjacent pixels. In addition, according to the present invention, light incident at a critical angle or less is reflected by a shielding film to transmit the corresponding pixel, thereby improving brightness.

Claims (14)

A first substrate on which a plurality of gate lines and data lines defining a plurality of pixels are arranged; A second substrate on which a black matrix for blocking transmission of light to the image non-display area is formed; A liquid crystal layer formed between the first substrate and the second substrate; And And a blocking film formed between the pixels of the first substrate and the second substrate along the black matrix to shield and reflect light transmitted to adjacent pixels. delete delete The liquid crystal display device according to claim 1, wherein the blocking film is made of a photopolymer. delete The liquid crystal display element according to claim 1, further comprising a thin film transistor formed in each pixel and applying a signal to the pixel. The liquid crystal display element according to claim 1, wherein the blocking layer is formed on the first substrate. 8. The liquid crystal display of claim 7, wherein the height of the blocking layer is determined according to a critical angle of light incident on the pixel. The liquid crystal display according to claim 8, wherein the critical angle is calculated based on a distance between the black matrices, a cell gap, and a thickness of a layer formed on the first substrate and the second substrate. The liquid crystal display of claim 1, wherein the blocking layer is formed on the second substrate. The liquid crystal display device according to claim 10, wherein the height of the blocking layer is substantially the same as the cell gap. The liquid crystal display device according to claim 11, wherein the blocking film keeps a cell gap constant. The liquid crystal display device according to claim 1, further comprising at least a pair of electrodes disposed substantially parallel to the first substrate to form a transverse electric field. The method according to claim 1, A first electrode formed on the first substrate; And And a second electrode formed on the second substrate.

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