KR20060001667A - Tiledl display device having large size - Google Patents

Abstract

The tiled liquid crystal display device of the present invention is to improve the image quality by forming different cell gaps inside the panel, and includes a panel frame, a plurality of liquid crystal panels attached to and bonded to the panel frame, and installed on the liquid crystal panel. It is composed of a lens that refracts the light of the liquid crystal panel boundary region, characterized in that the cell gap in the center region and the boundary region of the liquid crystal panel is different.

LCD, Tiled, Lens, Deep Development, Cell Gap

Description

Large Area Tiled Display {TILEDL DISPLAY DEVICE HAVING LARGE SIZE}

1 is a block diagram showing a conventional tiled liquid crystal display device.

2 is a partial cross-sectional view showing a structure of a liquid crystal panel boundary of a conventional tiled liquid crystal display device provided with a lens.

3 is a view showing a liquid crystal panel in which incident angles of light in different regions are different.

4 is a view showing a basic concept of the present invention by forming a separate layer on the liquid crystal panel to equalize the traveling distance of light.

5 is a graph showing a relationship between an incident angle and a phase delay difference.

6 is a partial cross-sectional view showing the structure of a tiled liquid crystal display device according to an embodiment of the present invention.

7A and 7B are partial cross-sectional views illustrating a structure of a tiled liquid crystal display device according to another exemplary embodiment of the present invention.

Explanation of symbols on main parts of drawing

200: liquid crystal panel 210,220: substrate

212: gate insulating layer 214: protective layer

216 pixel electrode 222 color filter layer

230: liquid crystal layer 240: intermediate layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tiled display device, and more particularly, to a tiled liquid crystal display device capable of preventing a seam phenomenon and improving image quality.

Recently, with the development of various portable electronic devices such as mobile phones, PDAs, and notebook computers, there is an increasing demand for flat panel display devices for light and thin applications. Such flat panel displays are being actively researched such as liquid crystal display (LCD), plasma display panel (PDP), field emission display (FED), and vacuum fluorescent display (VFD).

On the other hand, the display device is gradually expanding the range of application is demanding a screen of a large area, as well as everyday electronic devices. Therefore, in recent years, researches on flat panel display devices have been actively conducted to realize high-resolution screens of high quality, but it is currently impossible to manufacture flat panel display devices having a large area. Moreover, although a large area display device can be manufactured using the CRT, in this case, there is a problem that the volume of the display device becomes large and the image quality is low.

In order to solve this problem, recently proposed is a tiled display device in which a plurality of display panels are bonded. The tiled display element is a unitary display panel in which a plurality of panels are joined to each other, and the structure thereof is shown in FIG. In this case, the liquid crystal panel will be described as an example of the panel.

As shown in FIG. 1, the tiled liquid crystal display device 10 is provided with a plurality of liquid crystal panels 30a to 30d fixed to the frame 20. In this case, a backlight unit, a substrate, a liquid crystal layer, and a polarizing member are attached to each of the liquid crystal panels 30a to 30d to form one unit. The frame 20 includes an outer wall frame 20a that forms an outer wall, a partition frame 20b that isolates the panel from the panel, and a lower plate 20c on which the panels 30a to 30d are seated. In this case, each of the liquid crystal panels 30a to 30d is seated in the space partitioned by the partition wall frame 20b and the outer wall frame 20a and bonded to each other.

In the tiled liquid crystal display device having the above-described structure, when an external video signal is applied to the bonded liquid crystal panels 30a to 30d, independent screens are not separately displayed on the plurality of bonded liquid crystal panels, and the same information is displayed as a whole. It is displayed on one screen. However, the tiled liquid crystal display has the following problems. That is, between the bonded liquid crystal panels, that is, the partition frame 20b is an area where an image is not substantially displayed, and a seam phenomenon in which a boundary line is displayed in an area corresponding to the partition wall frame 20b when displaying an image is displayed. It happens.

Such image development is the most important factor for degrading the image quality of the tiled liquid crystal display device, and various methods for preventing such image development have been proposed. Among them, a lens is mounted on the liquid crystal panel 30a to 30d on which the most known method is bonded. It is installed to change the path of light to prevent deep phenomenon.

2 illustrates a basic concept of a liquid crystal display device capable of preventing a deep phenomenon by installing a lens. In this case, for convenience of description, only the portion between the liquid crystal panel and the liquid crystal panel, that is, near the partition wall frame 20b is shown.

As shown in FIG. 2, a lens 40 is disposed on the bonded liquid crystal panels 30a and 30b, and the lens 40 forms a curve having a curvature set near the barrier rib frame 20b. do. Therefore, the light propagating obliquely through the liquid crystal panels 30a and 30b is changed in the traveling direction by the curvature of the lens of the partition frame 20b to go straight to the front of the liquid crystal panels 30a and 30b. In this way, the lens 40 changes the traveling direction of the light passing through the liquid crystal panels 30a and 30b to output light in the front direction even near the partition frame 20b, and as a result, the boundary between the liquid crystal panels 30a and 30b. Deep imaging in the area can be prevented.

However, the tiled liquid crystal display device having the above structure has the following problems.

That is, while the light P1 outputting the center of the liquid crystal panels 30a and 30b passes through the liquid crystal panels 30a and 30b vertically, the partition frame 20b whose direction of travel is changed by the curve of the lens 40 is changed. The light P2 near) passes through the liquid crystal panels 30a and 30b at an angle. Therefore, due to the refractive anisotropy of the liquid crystal molecules, the phase delay difference is different between the light P1 in the center region of the liquid crystal panels 30a and 30b and the light P2 near the partition frame 20b, so that the light transmission characteristics are different. This may cause deterioration of the image quality of the display element.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned point, and by forming the cell gap between the center region inside the liquid crystal panel and the boundary region between the other liquid crystal panels to equalize the phase delay, the image quality degradation in the boundary region occurs. It is an object of the present invention to provide a tiled liquid crystal display device which can prevent the damage.

In order to achieve the above object, a tiled type liquid crystal display device according to the present invention includes a panel frame, a plurality of liquid crystal panels provided and bonded to the panel frame, and a light of a liquid crystal panel boundary region provided on the liquid crystal panel. And a cell gap in the center region and the boundary region of the liquid crystal panel. In this case, the cell gap of the liquid crystal panel decreases as it goes from the center region to the boundary region, and the difference in the cell gap is different from the thickness of the gate insulating layer or the protective layer formed on the first substrate or the thickness of the overcoat layer formed on the second substrate. This is done by forming differently.

In addition, the cell gap can be formed differently by forming an intermediate layer on the gate insulating layer or the protective layer, and the cell gap can be formed differently by forming an overcoat layer on the color filter layer of the boundary area. At this time, the difference (α) of the thickness of the layer between the center region and the outer region, or the thickness (α) of the layer formed in the boundary region,

Where d is the cell gap of the central region, Δn is the refractive index anisotropy of the liquid crystal molecules, and θ is the incident angle of light to the liquid crystal layer.

According to the present invention, there is provided a tiled liquid crystal display device having improved image quality by making light transmission characteristics equal in the center region of the liquid crystal panel and the boundary region between the liquid crystal panels. To this end, in the present invention, the cell gap in the center region and the boundary region of the liquid crystal panel is different so that the phase delay difference of the light passing through the liquid crystal layer in the corresponding region is the same.

In general, the liquid crystal panel is designed in consideration of the refractive index anisotropy (Δn) and the phase delay according to the cell gap (d). However, as shown in FIG. 3, the phase delay difference between the light P1 that vertically transmits the liquid crystal panel 100 and the light P2 that is transmitted obliquely varies. Although the distance through which the light P1 passing through the liquid crystal layer 130 formed between the first substrate 110 and the second substrate 120 passes vertically is the same as the cell gap d of the liquid crystal panel 100, The passing distance of the light P2 through which P2 obliquely penetrates the liquid crystal layer 130 is d / cosθ.

In addition, the refractive anisotropy of the liquid crystal layer 130 that the light feels also depends on the incident angle of the light. In general, the refractive index anisotropy (nΔ) of the light P1 incident vertically on the liquid crystal layer 130 is expressed by Equation 1, while the refractive index anisotropy (Δn (Θ)) of the light P2 incident at an angle of θ Is as shown in equation (2).

Where n _e is the refractive index at the long axis of the liquid crystal molecule, n _o is the refractive index at the short axis of the liquid crystal molecule, and n _e (θ) is the refractive index of the liquid crystal molecule at an angle of θ.

Therefore, since the refractive index anisotropy of the liquid crystal layer 130 and the distance between the liquid crystal layer 130 through which the light passes varies according to the angle through which light passes, the light P1 penetrating the liquid crystal layer 130 vertically and a predetermined angle. The phase delay difference of the light P2 transmitted by (θ) is changed, and as a result, the transmission characteristic is changed.

Therefore, in order to prevent the phase delay difference between the light P1 vertically transmitting the liquid crystal layer 130 and the light P2 obliquely passing through the liquid crystal layer 130 from being transmitted obliquely with the liquid crystal layer in the area A vertically transmitting. It is necessary to change the refractive index anisotropy of the liquid crystal layer of the region B or to change the transmission distance of the light of the liquid crystal layer of the region A to which light is transmitted vertically and the region B to be transmitted obliquely. Since it is impossible to substantially change the refractive index anisotropy of the liquid crystal layer, it is necessary to change the transmission delay of light to prevent the phase delay difference from changing.

The basic concept of the present invention is to prevent the deterioration of image quality due to the change of the phase delay in the tiled liquid crystal display device by changing the transmission distance of light.

4 is a diagram illustrating the basic concept of the present invention. As shown in FIG. 4, in the present invention, the structure of the first region A through which the light P1 vertically passes through the liquid crystal layer 130 and the second region B through which the light P2 is obliquely transmitted are It is formed differently so that the transmission distance of light is the same. That is, by forming a separate layer 140 in the second region B to reduce the cell gap, the transmission distance of the light P2 is reduced. Alternatively, the cell gap of the first region A may be increased to increase the transmission distance of the light P1. At this time, the decrease or increase α of the cell gap according to the incident angle is expressed by Equation 3 below.                     

The layer 140 for changing the cell gap d may be formed on the first substrate 110 or on the second substrate 120.

As described above, since the phase delay difference is always the same regardless of the incident angle of light by increasing or decreasing the liquid crystal layer 130, as shown in FIG. 5, the phase delay difference is always the same regardless of the incident angle.

According to the present invention, the above concept is applied to a tiled liquid crystal display device so that the phase delay difference in the center region of the liquid crystal panel and the region between the liquid crystal panels is the same. It is possible to prevent a defect due to variation of the transmission characteristics.

6 is a view showing an embodiment of a tiled liquid crystal display device according to the present invention. In this case, the drawing is an enlarged view of a region where two liquid crystal panels are bonded, and the actual tiled liquid crystal display device is formed by bonding a plurality of liquid crystal panels as shown in FIG. 1.

As illustrated in FIG. 6, the plurality of liquid crystal panels 200a and 200b are attached to the lower plate 207 in a state separated by the partition frame 205. Each of the liquid crystal panels 200a and 200b includes a first substrate 201a and 210b and a second substrate 220a and 220b made of a transparent material such as glass and liquid crystal layers 230a and 230b therebetween. Although not shown in the drawing, the first substrates 210a and 210b are thin film transistor array substrates, and switching devices such as thin film transistors are formed, and the second substrates 220a and 220b are color filter substrates.

Gate insulating layers 212a and 212b and protective layers 214a and 214b are formed on the first substrates 210a and 210b, respectively. In this case, the protective layers 214a and 214b have different thicknesses in the center region and the outer region (that is, the region adjacent to the partition frame 205). Strictly speaking, the protective layers 214a and 214b have a thicker thickness (or thinner from the outer region to the central region). In addition, pixel electrodes 216a and 216b formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO) are formed on the passivation layers 214a and 214b.

Color filter layers 222a and 222b are formed on the second substrates 220a and 220b to implement actual colors. Although not shown in the drawing, the second substrates 220a and 220b are formed with a black matrix and a common electrode made of ITO, IZO, etc. to block light from being transmitted to the image non-display area.

The lens 260 is provided on the liquid crystal panels 200a and 200b. The lens 260 is formed in a curve having a curvature set in a boundary region between the liquid crystal panels 200a and 200b (that is, near the partition frame 205), thereby refracting the light output from the liquid crystal panels 200a and 200b. This prevents the deep phenomenon occurring in the boundary area between the liquid crystal panels 200a and 200b.

As described above, in the tiled liquid crystal display device configured as described above, the thicknesses of the protective layers 214a and 214b formed in the liquid crystal panels 200a and 200b become larger toward the boundary region between the liquid crystal panels 200a and 200b. In other words, the cell gaps of the liquid crystal panels 200a and 200b become smaller toward the boundary regions of the liquid crystal panels 200a and 200b (d1> d2> d3). Meanwhile, the incident angles of the lights P1 and P2 incident on the liquid crystal layers 23a and 230b become larger toward the boundary region. In other words, the traveling distance of the lights P1 and P2 increases toward the boundary region.

Therefore, the cell gap decreases toward the boundary region between the liquid crystal panels 200a and 200b while the travel distance of the light increases (or the cell gap increases and the travel distance decreases toward the center region between the liquid crystal panels 200a and 200b). ) The advancing distance of the light in the liquid crystal layers 230a and 230b is the same, and eventually passes through the boundary area between the light P1 and the liquid crystal panels 200a and 200b that transmit the central region of the liquid crystal panels 200a and 200b. The phase delay difference of the light P2 refracted by the lens 260 becomes the same. Therefore, when the user views the screen from the front of the liquid crystal display device, it is possible to prevent the deterioration in image quality due to the difference in the light transmission characteristics in the central region and the outer region of the liquid crystal panels 200a and 200b. In this case, the thickness difference α between the protective layer 216 in the center region and the boundary region of the liquid crystal panels 200a and 200b is expressed by Equation 3 above.

In the above-described embodiment, the cell gap is adjusted by varying the thicknesses of the protective layers 214a and 214b of the liquid crystal panels 200a and 200b in the center region and the outer region. However, the cell gap is varied by varying the thickness of the gate insulating layers 212a and 212b. You might be able to adjust it.

In addition, as shown in FIG. 7A, the cell gap may be adjusted by forming separate intermediate layers 340a and 340b in the outer regions of the liquid crystal panels 300a and 300b. In this case, the intermediate layers 340a and 340b may be made of metal or an insulating material, and may be formed on the first substrates 310a and 310b or on the gate insulating layers 312a and 312b or the protective layers 314a and 314b. It may be formed on).

As shown in FIG. 7B, a separate overcoat layer having a different thickness (of course, increasing in thickness toward the outer region) of the second substrates 320a and 320b of the liquid crystal panels 300a and 300b is provided. , 342b). In this case, the overcoat layers 342a and 342b may be formed on the second substrates 320a and 320b or may be formed on the color filter layers 322a and 322b. In addition, the overcoat layers 342a and 342b may not be formed over the entire second substrates 320a and 320b, but may be formed only in the outer region of the liquid crystal panels 300a and 300b.

In the above description, only the liquid crystal display device is described for convenience of description. However, the tiled display device of the present invention is not limited to the liquid crystal display device, but various types of flat panel such as PDP, FED, and VFD, which are in the spotlight in recent years. It may be applied to the display element. In addition, the liquid crystal display device may be applied to various driving modes and various structures such as twisted nematic (TN) mode, in plane switching (IPS) mode, and vertical alignment (VA) mode.

As described above, in the present invention, the cell gaps in the plurality of liquid crystal panels to be bonded are different from the center region and the outer region so that the optical characteristics of the light passing through the panel at different incidence angles are the same. Therefore, it is possible to effectively prevent the deterioration in image quality due to the difference in optical characteristics of light due to different incidence angles in the boundary region of the tiled display device in which a plurality of liquid crystal panels are bonded.

Claims (13)

Panel frame; A plurality of liquid crystal panels installed and bonded to the panel frame; And It is installed on the liquid crystal panel and consists of a lens that refracts the light of the liquid crystal panel boundary region, And a cell gap in a center region and a boundary region of the liquid crystal panel. The tiled liquid crystal display of claim 1, wherein the cell gap of the liquid crystal panel becomes smaller from the center region to the boundary region. The liquid crystal panel of claim 1, wherein A first substrate on which a switching element is formed; A gate insulating layer formed on the first substrate; A protective layer formed on the gate insulating layer; And A tiled liquid crystal display device comprising a second substrate having a color filter. 4. The tiled liquid crystal display device according to claim 3, wherein the thickness of the gate insulating layer increases from the central region to the boundary region. 4. The tiled liquid crystal display device according to claim 3, wherein the protective layer increases in thickness from the center region to the boundary region. The thickness difference (α) between the center region and the boundary region of the gate insulating layer and the protective layer is according to claim 4 or 5,

Wherein d is a cell gap of a central region, Δn is an index of refraction of liquid crystal molecules, and θ is an incident angle of light to the liquid crystal layer. 4. A tiled liquid crystal display device according to claim 3, further comprising an intermediate layer formed on the gate insulating layer of the liquid crystal panel boundary region. 4. A tiled liquid crystal display device according to claim 3, further comprising an intermediate layer formed on the protective layer of the liquid crystal panel boundary region. The thickness (α) of the intermediate layer according to claim 7 or 8,

Wherein d is a cell gap of a central region, Δn is an index of refraction of liquid crystal molecules, and θ is an incident angle of light to the liquid crystal layer. 4. The tiled liquid crystal display device according to claim 3, further comprising an overcoat layer formed on the color filter layer and increasing in thickness from the center area of the liquid crystal panel to the boundary area. The thickness difference α between the center region and the boundary region of the overcoat layer is

Wherein d is a cell gap of a central region, Δn is an index of refraction of liquid crystal molecules, and θ is an incident angle of light to the liquid crystal layer. 4. The tiled liquid crystal display device according to claim 3, further comprising an overcoat layer formed on the color filter layer of the liquid crystal panel boundary region. The method according to claim 12, wherein the thickness (α) of the overcoat layer,

Wherein d is a cell gap of a central region, Δn is an index of refraction of liquid crystal molecules, and θ is an incident angle of light to the liquid crystal layer.

Images