KR20120070217A - Liquid crystal display - Google Patents

Abstract

PURPOSE: A liquid crystal display device is provided to prevent damage and light leakage of a liquid crystal panel. CONSTITUTION: A liquid crystal layer(180) is located on a lower substrate(110). An upper substrate(150) is located on the liquid crystal layer. A lower polarizing plate(190b) is located on a lower surface of the lower substrate. An upper polarizing plate(190a) is located on an upper side of the upper substrate. A line pad is located on at least one of the upper substrate and the lower substrate.

Description

Liquid Crystal Display {LIQUID CRYSTAL DISPLAY}

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device that can prevent the panel from warping.

With the development of various portable electronic devices such as mobile phones, PDAs, notebooks, and the like, there is an increasing demand for a lightweight thin flat panel display device that can be applied thereto. Liquid crystal display (LCD), plasma display panel (PDP), organic light emitting diode (OLED), etc. are being actively researched as such flat panel display devices. BACKGROUND ART Liquid crystal display devices, which are easy to drive and easily implement high image quality, have been in the spotlight.

The liquid crystal display classified into a light receiving display device may include a backlight unit disposed below the liquid crystal panel to provide light to the liquid crystal panel in addition to the liquid crystal panel displaying an image.

Recently, the liquid crystal display has been studied to reduce the thickness and weight. In particular, in order to slim down and lighten the liquid crystal display device, the thickness of the liquid crystal panel including the thin film transistor substrate and the color filter substrate is gradually decreasing. However, when the thickness of the liquid crystal panel glass is reduced in order to reduce the thickness of the liquid crystal panel as described above, the phenomenon in which the liquid crystal panel is bent is remarkably generated.

There are many factors causing such a phenomenon that the liquid crystal panel is bent. In particular, the contracting force of the upper plate of the polarizing plate attached to the upper substrate and the contracting force of the lower plate of the polarizing plate attached to the lower substrate are opposed to each other. At this time, the polarizing plate upper plate tends to bend the long axis while the lower polarizing plate tends to bend the short axis due to the direction in which it is stretched.

FIG. 1 is a view illustrating a process of forming a polarizing plate on a substrate, FIG. 2 is a diagram illustrating a warpage phenomenon of a substrate appearing in a liquid crystal panel, and FIG. 3 is a diagram illustrating a substrate in which a substrate is bent.

1 to 3, in the process of attaching the polarizing plate on a glass, the stretching process of the polarizing plate is necessarily accompanied. Later, due to the high temperature conditions in the process, the polarizing plate generates residual stress in the direction opposite to the stretching direction, causing the substrate to shrink.

Therefore, as shown in FIG. 2, since the upper plate of the polarizer attached to the upper part of the liquid crystal panel shrinks along the long axis of the polarizer, the short side portion of the liquid crystal panel generates a V-shaped warp toward the upper side. In addition, since the lower plate of the polarizer attached to the lower portion of the liquid crystal panel shrinks due to the shortening of the polarizing plate, the long side portion of the liquid crystal panel generates a V-shaped warp toward the lower side.

Referring to FIG. 3, the non-parallel between the hardness of the glass substrate and the contraction force of the polarizing plate induces a bending force by moment M, and is divided into stretching and compression about a neutral axis. The measure of warping, ie the value of θ, is proportional to the amount of warping. The value of θ is proportional to the deformation of C and A against the M value and the deformation of D and B. Here, the thickness and tension of the glass substrate are not sufficient to counter the bending moment M, so that bending occurs.

FIG. 4 is a diagram illustrating a liquid crystal panel in which warpage occurs in the liquid crystal display, and FIG. 5 is a diagram illustrating light leakage due to the warpage of the liquid crystal panel.

4 and 5, after the high temperature reliability test of the liquid crystal panel to which the polarizers are attached, light leakage occurs at short sides of the liquid crystal panel. In more detail, the liquid crystal panel mounted in the liquid crystal display device may have a V-shaped warp at the short side and a V-shaped warp at the long side, resulting in damage due to contact with the top case.

When warpage occurs at the short side of the liquid crystal panel, light leakage occurs as shown in FIG. 5 (a). When warp occurs at the long side of the liquid crystal panel, light leakage occurs as shown in FIG. In addition, when warpage occurs in both the short side portion and the long side portion of the liquid crystal panel, light leakage as shown in (c) of FIG. 5 occurs.

Therefore, a liquid crystal display device having a liquid crystal panel in which warpage occurs has a problem in that light leakage and damage to the liquid crystal panel occur.

The present invention provides a liquid crystal display device which can prevent warpage of a liquid crystal panel and prevent damage and light leakage of the liquid crystal panel.

In order to achieve the above object, a liquid crystal display according to an embodiment of the present invention is a lower substrate, a liquid crystal layer positioned on the lower substrate, an upper substrate positioned on the liquid crystal layer, the lower substrate is located The lower polarizer may include a lower polarizer, an upper polarizer positioned on an upper surface of the upper substrate, and a line pad positioned on at least one surface of the lower substrate and the upper substrate and positioned adjacent to at least one side of the lower substrate or the upper substrate.

The line pad may be positioned on one surface of the upper substrate and may be positioned around the upper polarizer.

The line pads may be positioned adjacent to opposite sides of the upper substrate, respectively.

Opposite sides of the upper substrate may be two long sides of the upper substrate.

The line pads may be positioned adjacent to two pairs of opposite sides of the upper substrate, respectively.

The line pad may be positioned on one surface of the lower substrate and may be positioned around the lower polarizer.

The line pads may be positioned adjacent to both sides of the lower substrate facing each other.

Opposite sides of the lower substrate may be two long sides of the lower substrate.

The line pad may be positioned adjacent to each of two pairs of opposite sides of the lower substrate.

The line pad may be made of glass or metal.

The liquid crystal display according to the exemplary embodiment of the present invention has an advantage of preventing the substrate from bending by attaching a line pad to the upper substrate or the lower substrate.

1 is a view showing a step of forming a polarizing plate on a substrate.
2 is a view showing the warpage of the substrate appearing in the liquid crystal panel.
3 is a view showing a schematic diagram of the substrate bent.
4 is a view illustrating a liquid crystal panel in which warpage occurs in the liquid crystal display device.
5 is a view showing the generation of light leakage due to the bending of the liquid crystal panel.
6 illustrates a liquid crystal display according to an exemplary embodiment of the present invention.
7A, 7B and 8 illustrate a liquid crystal display according to a first embodiment of the present invention.
9A, 9B, and 10 illustrate a liquid crystal display according to a second embodiment of the present invention.
11 illustrates a liquid crystal display according to a third embodiment of the present invention.
12 is a view showing a method of attaching a polarizing plate to an upper substrate of the present invention.
FIG. 13 shows a process for attaching a line pad to a glass substrate to prepare a sample. FIG.
14 shows a glass substrate sample with a line pad attached thereto, and FIG. 15 shows a method for measuring the amount of warpage of the glass substrate sample.
15 shows a method of measuring the amount of warpage of a substrate.

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

6 is a diagram illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 6, the liquid crystal display device 100 according to an exemplary embodiment of the present disclosure may face the lower substrate 110, the lower substrate 110, and the upper substrate 150 and the lower substrate 110 bonded to each other. And a liquid crystal layer 180 formed between the upper substrate 150.

The lower substrate 110 is formed between the thin film transistor TFT formed on the lower substrate 110, the pixel electrode 145 electrically connected to the thin film transistor TFT, and the thin film transistor TFT and the pixel electrode 145. The organic insulating layer 140 may be included.

The thin film transistor TFT is formed to face the gate electrode 115 connected to the gate line, the source electrode 135a connected to the data line, and the source electrode 135a, and the drain electrode 135b electrically connected to the pixel electrode 145. ), A gate insulating layer 120 that insulates the gate electrode 115, an active layer 125 and an ohmic contact layer 130 formed in a region corresponding to the gate electrode 115 with the gate insulating layer 120 interposed therebetween. Can be.

Accordingly, the thin film transistor TFT supplies the data voltage from the data line to the pixel electrode 145 in response to the gate on / off voltage from the gate line.

The pixel electrode 145 is formed of a transparent metal such as indium tin oxide (ITO), indium zinc oxide (IZO), or the like, and applies a data voltage to the liquid crystal layer 180 from the drain electrode 135b. Therefore, the pixel electrode 145 is electrically connected to the drain electrode 135b through the contact hole 141 penetrating the organic insulating layer 140.

The organic insulating layer 140 is formed to cover the thin film transistor TFT and is formed on the entire surface of the lower substrate 110. The organic insulating layer 140 protects the thin film transistor TFT and serves to form the pixel electrode 145 flat.

The upper substrate 150 includes an overcoat layer covering the black matrix 155 formed on the upper substrate 150 to prevent light leakage, the color filter 160 formed for color implementation, the black matrix 155 and the color filter 160. 165 and the common electrode 170 formed on the overcoat layer 165.

The black matrix 155 is formed of an opaque organic material or an opaque metal to prevent light from being transmitted through an area beyond the control of the liquid crystal layer 180. The color filter 160 may be formed of the red, green, and blue color filters 160 to implement color. In addition, the overcoat layer 165 may be formed of a transparent organic material to protect the color filter 160 and to provide good step coverage of the common electrode 170. The common electrode 170 is formed of a transparent metal such as indium tin oxide (ITO) or indium zinc oxide (IZO), and serves to apply a common voltage to the liquid crystal layer 180.

That is, the liquid crystal panel 200 may include a lower substrate 110, an upper substrate 150, and a liquid crystal layer 180 interposed between the lower substrate 110 and the upper substrate 150.

The upper polarizer 190a is positioned on one surface of the upper substrate 150, and the lower polarizer 190b is positioned on one surface of the lower substrate 110.

The upper polarizing plate 190a and the lower polarizing plate 190b exhibit polarization characteristics, and absorb any component of the white light in an unpolarized state by the conjugated structure of the oriented dichroic material or the oriented polymer chain itself, and are perpendicular thereto. Other components that serve to permeate. An iodine polarizing film may be used as the upper polarizing plate 190a and the lower polarizing plate 190b.

The iodine-based polarizing film exhibits polarization by being oriented by a polyvinyl alcohol (PVA) chain in which an iodine ion chain is oriented, and the dye-based polarizing film is also oriented by a PVA chain in which a dichroic dye is oriented. By doing so, polarization is exhibited. On the other hand, the polyene-based polarizing film exhibits polarization by forming polyenes by dehydration of PVA film or dehydrochlorination of PVC film.

The upper polarizer 190a and the lower polarizer 190b have an absorption axis and a polarization axis. The absorption axis is an axis in which iodine ion chains are stretched and oriented, and one of two vertical components of light vibrating in an arbitrary direction is a polarizer It is an axis that dissipates the light component in the process of interacting with the electron of light and converting the electrical energy of light into the energy of electron. The polarization axis is an axis perpendicular to the absorption axis and transmits light oscillating in the polarization axis direction. The thickness of the upper polarizer 190a and the lower polarizer 190b may be 15 to 30 μm, respectively.

7A to 8 illustrate a liquid crystal display according to a first embodiment of the present invention.

7A to 8, in the liquid crystal display of the present invention, the upper line pad 200 is positioned on one surface of the upper substrate 150. The upper line pad 200 serves to prevent bending of the upper substrate 150 and is positioned around the upper polarizer 190a attached to the upper substrate 150.

The upper line pad 200 is positioned on at least one side of the upper substrate 150 and is adjacent to the long side of the upper substrate 150. The upper line pad 200 is made of glass, which is the same material as that of the upper substrate 150. Alternatively, the upper line pad 200 may be made of metal.

The upper line pad 200 has a width of 2 to 10 mm. If the width of the upper line pad 200 is greater than or equal to 2 mm, the substrate can be prevented from bending, and if the width of the upper line pad 200 is less than or equal to 10 mm, it is difficult to adhere to the display area of the upper substrate. The problem can be prevented.

In addition, the upper line pad 200 has a rectangular cross-section (bar) shape, alternatively, may have a shape in which the thickness gradually decreases or gradually increases from one end to the other end. However, the shape of the upper line pad 200 is not limited thereto, and may be formed in various shapes.

In more detail, the upper line pad 200 is positioned adjacent to one long side of the upper substrate 150 as shown in FIG. 7B. In addition, two upper line pads 200 and 210 may be provided, and as shown in FIG. 7B, the upper line pads 200 and 210 may be positioned adjacent to opposite sides of the upper substrate 150. Here, both sides facing each other are two long sides of the upper substrate 150.

Referring to FIG. 8, the upper polarizing plate 190a attached to the upper substrate 150 generates a bending-induced stress ① that bends the long axis of the upper substrate 150 upwardly, depending on the direction in which the upper polarizing plate 190a is extended. At this time, the upper line pad 200 located on the long side of the upper substrate 150 generates a bending resistance force ② that resists in the opposite direction to the bending causing stress ①.

That is, since the upper polarizer 190a tries to bend the long axis of the upper substrate 150 upward, and the upper line pad 200 generates resistance to bend the long axis of the upper substrate 150 downward, the upper substrate It is possible to prevent the 150 from bending in any one direction.

Therefore, the at least one upper line pad 200 positioned adjacent the long side of the upper substrate 150 has an advantage of preventing the upper substrate 150 from being bent by the upper polarizer 190a.

9A through 10 illustrate a liquid crystal display according to a second exemplary embodiment of the present invention.

9A to 10, in the liquid crystal display of the present invention, the lower line pad 220 is positioned on one surface of the lower substrate 110. The lower line pad 220 serves to prevent bending of the lower substrate 110 and is positioned around the lower polarizer 190b attached to the lower substrate 110.

The lower line pad 220 is positioned on at least one side of the lower substrate 110 and is adjacent to the short side of the lower substrate 110. The lower line pad 220 is made of glass, which is the same material as the lower substrate 110. Alternatively, the lower line pad 220 may be made of metal.

The lower line pad 220 has a width of 2 to 10 mm. If the width of the lower line pad 220 is greater than or equal to 2 mm, the substrate can be prevented from bending, and if the width of the lower line pad 220 is less than or equal to 10 mm, it is difficult to adhere to the display area of the lower substrate. The problem can be prevented.

In addition, the lower line pad 220 is formed in the shape of a rectangular bar (bar) cross-section, on the contrary, may be formed in a shape that gradually decreases or gradually increases in thickness from one end to the other end. However, the shape of the lower line pad 220 is not limited thereto, and may be formed in various shapes.

In more detail, the lower line pad 220 is positioned adjacent to one short side of the lower substrate 110 as shown in FIG. 9B. In addition, two lower line pads 220 and 230 may be provided, and as shown in FIG. 9B (b), the lower line pads 220 and 230 may be positioned adjacent to opposite sides of the lower substrate 110. Here, both sides facing each other are two short sides of the lower substrate 110.

Referring to FIG. 10, the lower polarizing plate 190b attached to the lower substrate 110 generates a bending-induced stress ① that tries to bend the short axis of the lower substrate 150 upward due to the direction in which it is extended. . At this time, the lower line pad 220 positioned on the long side of the lower substrate 110 generates a bending resistance force ② that resists in the opposite direction to the bending induced stress ①.

That is, since the lower polarizer 190b tries to bend the short axis of the lower substrate 110 upward, and the lower line pad 220 generates resistance to bend the short axis of the lower substrate 110 downward, the lower substrate It is possible to prevent the 110 from bending in any one direction.

Accordingly, at least one lower line pad 220 positioned adjacent to a short side of the lower substrate 110 may prevent the lower substrate 110 from being bent by the lower polarizer 190b.

11 is a diagram illustrating a liquid crystal display according to a third exemplary embodiment of the present invention.

Referring to FIG. 11, in the liquid crystal display of the present invention, the lower line pads 220 and 230 are positioned on one surface of the lower substrate 110, and the upper line pads 200 and 210 are disposed on one surface of the upper substrate 150. )) Is located.

The lower line pads 220 and 230 serve to prevent bending of the lower substrate 110. The lower line pads 220 and 230 are positioned around the lower polarizer 190b attached to the lower substrate 110. Located adjacent.

The upper line pad 200 serves to prevent bending of the upper substrate 150. The upper line pad 200 is positioned around the upper polarizing plate 190a attached to the upper substrate 150, and is adjacent to the long side of the upper substrate 150. Located.

The liquid crystal display according to the third exemplary embodiment of the present invention has a structure including both the upper line pads 200 and 210 and the lower line pads 220 and 230 according to the first and second embodiments described above.

Accordingly, the upper line pads 200 and 210 may resist the stress of the upper polarizer 190a attached to the upper substrate 150 in a direction opposite to the bending of the long axis of the upper substrate 150, thereby preventing the upper substrate 150 from being formed. Prevents warping.

In addition, the lower line pads 220 and 230 may resist the stress in which the lower polarizer 190b attached to the lower substrate 110 is inclined to bend the short axis of the lower substrate 110, thereby preventing the lower substrate 110 of the lower substrate 110. Prevents warping.

12 is a view showing a method of attaching a polarizing plate to the upper substrate of the present invention.

Referring to FIG. 12, the upper line pad 200 is attached to the liquid crystal panel 250 to which the lower substrate 110 and the upper substrate 150 are bonded. The upper line pad 200 is made of the same material as the upper substrate 150, and may be made of metal.

The upper line pad 200 is first manufactured in the form of a long bar, and is attached to be adjacent to the long side of the upper substrate 150 using a UV resin. The UV resin is cured to attach the upper line pad 200 to the upper substrate 150 by irradiating UV.

The upper polarizer 190a is attached to the upper substrate 150 on which the upper line pad 200 is formed using a roller. The process using a roller can prevent the upper polarizer 190a from twisting during the attachment by attaching the upper line pad 200 as a reference.

Although not shown, the lower polarizer 190b may be attached to one surface of the lower substrate 110 in the same manner as the upper polarizer 190a is attached.

Hereinafter, an experimental example of testing the warpage of the glass substrate according to an embodiment of the present invention. This experimental example is only one embodiment of the present invention is not limited thereto.

FIG. 13 is a view illustrating a process of manufacturing a sample by attaching a line pad to a glass substrate, FIG. 14 is a view illustrating a glass substrate sample with a line pad attached thereto, and FIG. 15 is a method of measuring a warping amount of a glass substrate sample. The figure shown.

Referring to FIG. 13, first, as shown in (a) and (b), three line pads having a width of 2 mm, 4 mm, and 10 mm were collected using a glass cutter. Subsequently, as shown in (c), a polarizing plate was attached to one side of the glass substrate, and (d) UV resin was applied to the three line pads previously collected. Next, after (e) the glass substrate support and the glass substrate were bonded together, line pads were attached to the glass substrates via UV exposure, respectively.

Therefore, as shown in FIG. 14, a sample having a 2 mm line pad attached to each side of the glass substrate (a), a sample having a 4 mm line pad attached thereto, and a sample having a 10 mm line pad attached thereto, respectively (c) was prepared.

The prepared samples (a) to (c) and a ref sample having only a polarizer attached to a glass substrate were subjected to a bending test, and are shown in Table 1 below.

In the bending test conditions, the initial warpage amount was measured at room temperature, and the warpage amount of the substrate was measured again after providing reliability conditions by injecting for 48 hours in a high-temperature chamber at 60 degrees. Here, the method of measuring the amount of warpage was measured by placing a glass substrate sample on the surface plate and a measurer in the center, as shown in FIG. 15.

Initial deflection Average deflection Deflection after Reliability Test Average deflection ref
Left side 4.0mm 4.1mm
12 mm 12 mm
Right side 4.2mm 11 mm Sample (a)
Left side 4.0mm 4.0mm
10 mm 10 mm
Right side 3.9 mm 10 mm Sample (b)
Left side 2.1mm 2.0mm
6 mm 5.9 mm
Right side 1.9mm 5.7 mm Sample (c)
Left side 1.0mm 1.0mm
5.9 mm 5.9 mm
Right side 0.9mm 5.8mm

Referring to Table 1, in the case of the ref sample without the line pad, the initial average warpage amount was 4.1 mm and the bending amount after the reliability test was 12 mm. On the other hand, in the case of samples (a) to (c) with line pads, the initial average warpage amount was 1 to 4 mm and the average warpage amount was 5.9 to 10 mm, so that the warpage amount was significantly higher than that of the ref sample without the line pad. It can be seen that the decrease.

As described above, the liquid crystal display according to the exemplary embodiment of the present invention has an advantage of preventing the substrate from bending by attaching a line pad to the upper substrate or the lower substrate.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. Therefore, the embodiments described above are to be understood as illustrative and not restrictive in all aspects. In addition, the scope of the present invention is shown by the claims below, rather than the above detailed description. Also, it is to be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention.

Claims (10)

A lower substrate;
A liquid crystal layer positioned on the lower substrate;
An upper substrate positioned on the liquid crystal layer;
A lower polarizer disposed on a lower surface of the lower substrate;
An upper polarizer disposed on an upper surface of the upper substrate; And
And a line pad disposed on at least one surface of the lower substrate and the upper substrate and positioned adjacent to at least one side of the lower substrate or the upper substrate.
The method of claim 1,
The line pad is positioned on one surface of the upper substrate and is positioned around the upper polarizer.
The method of claim 2,
And the line pads are adjacent to both sides of the upper substrate facing each other.
The method of claim 3, wherein
Both sides of the upper substrate facing each other are two long sides of the upper substrate.
The method of claim 2,
And the line pads are adjacent to each of two pairs of opposite sides of the upper substrate.
The method of claim 1,
The line pad is disposed on one surface of the lower substrate and is positioned around the lower polarizer.
The method according to claim 6,
And the line pads are adjacent to both sides of the lower substrate facing each other.
8. The method of claim 7,
Both sides of the lower substrate facing each other are two long sides of the lower substrate.
The method according to claim 6,
And the line pads are positioned adjacent to two pairs of opposite sides of the lower substrate, respectively.
The method of claim 1,
And the line pad is made of glass or metal.

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