KR20110062371A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: A liquid crystal display device is provided to efficiently implement a specific function without adding an ECB mode including cholesteric liquid crystal. CONSTITUTION: A liquid crystal cell(100) includes a liquid crystal layer which is formed between a lower substrate and an upper substrate. A multilayer structure(300) consists of a plurality of layers and is formed in one side of the liquid crystal cell. The multilayer structure comprises a second laminate(330) having a first laminate(320).

Description

[0001] The present invention relates to a liquid crystal display device,

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device suitable for use in a particular use, such as for protecting information from a person in the side seat in a moving means.

Liquid crystal display devices have a wide range of applications from mobile phones, notebook computers, monitors, spacecrafts, aircrafts, etc. to the advantages of low power consumption and low power consumption.

The liquid crystal display device includes a lower substrate, an upper substrate, and a liquid crystal layer formed between the two substrates, and the arrangement of the liquid crystal layers is adjusted according to whether an electric field is applied, and thus the light transmittance is adjusted to display an image. .

On the other hand, recently, liquid crystal display devices with specific functions have been developed to meet various demands of consumers.

For example, a liquid crystal display device applied to a mobile phone or the like has been developed such that a specific color can be displayed while the power is turned off. In other words, the black color is generally displayed when the LCD is turned off, but recently, a mobile phone targeting a young consumer group has the same color as the exterior case of the cellular phone when the power is turned off. Liquid crystal displays for displaying are being developed.

In the conventional liquid crystal display device in which a specific color is displayed while the power is turned off, an additional cell including a cholesteric liquid crystal is additionally configured to transmit external light through the cholesteric liquid crystal. It is designed to selectively reflect colors to achieve a specific wavelength color.

However, the conventional liquid crystal display device in which a separate cell including such a cholesteric liquid crystal is added, it is difficult to implement a variety of colors, and the desired specific color is well displayed on the front side, but the color fluctuations are severe depending on the viewing angle. In particular, there is a disadvantage in that a specific color desired is not displayed well, and in addition, an additional cell including a cholesteric liquid crystal is added, thereby increasing costs and a complicated manufacturing process.

In addition, in the case of using a laptop or a mobile phone in a means of transportation such as a train or an airplane, a liquid crystal display device having an adjustable viewing angle has been developed to protect information from the person next to the seat. In other words, liquid crystal displays have been developed to realize wide viewing angles, so that images can be viewed not only from the front side but also from the left and right sides. However, in order to protect privacy, images cannot be seen from the left and right sides and only from the front side. A liquid crystal display device having a function of adding the same has been developed.

As such, the conventional liquid crystal display device having a function of allowing an image to be viewed only from the front side additionally configures an electrostatically controlled birefringenence (ECB) mode in addition to the existing mode in the pixel, thereby adjusting the viewing angle when the ECB mode is operated. It is designed to see the image only from the front.

However, the conventional liquid crystal display device in which the ECB mode is added has a monotonous problem in that the color seen from the left and right sides when the ECB mode is operated is limited to white color only, and the cost is increased due to the addition of the ECB mode. There are disadvantages.

As described above, in order to meet various demands of consumers in recent years, a liquid crystal display device having a specific function has been developed, but in the case of the conventional method of additionally configuring a separate cell or ECB mode including cholesteric liquid crystal There is a disadvantage in that the cost is increased, and there is also a problem in efficiently implementing a desired function in each use.

The present invention has been devised to solve the above-mentioned conventional problems, and the present invention does not additionally constitute a separate cell or ECB mode including a cholesteric liquid crystal as in a conventional liquid crystal display device having a specific function. An object of the present invention is to provide a liquid crystal display device which can effectively implement a desired specific function even if it is desired.

The present invention provides a liquid crystal cell including a lower substrate, an upper substrate, and a liquid crystal layer formed between the lower substrate and the upper substrate to achieve the above object; And a multilayer structure formed on one surface of the liquid crystal cell, the multilayer structure including a plurality of layers, wherein the multilayer structure includes a first stack having a predetermined refractive index and a second stack having a different refractive index than that of the first stack. Provided is a liquid crystal display device comprising water.

Each of the first stack and the second stack may be made of a transparent oxide. In particular, the first stack may be made of TiO ₂ , and the second stack may be made of SiO ₂ .

The multilayer structure may be formed by alternately stacking the first stack and the second stack. At this time, the thickness of each of the first stack and the second stack is in the range of 10 ~ 800nm, the total number of stacks of the first stack and the second stack may be in the range of 2 to 50 layers.

The multilayer structure may be formed on the liquid crystal cell. In this case, an upper polarizing plate is formed on the liquid crystal cell, and the multilayer structure may be formed between the liquid crystal cell and the upper polarizing plate or may be formed on the upper polarizing plate. When the multilayer structure is formed on the upper polarizer, the multilayer structure may be formed on a substrate made of glass or transparent plastic, and the substrate may be attached to the upper polarizer.

The liquid crystal cell includes a first pixel and a second element having different modes from each other, and the first pixel is formed on the lower substrate and the upper electrode on the lower substrate to form a vertical electric field. An electrode may be included, and the second pixel may include a pixel electrode and a common electrode formed on the lower substrate to form a horizontal electric field or a fringe field.

According to the present invention as described above has the following effects.

According to the present invention, by applying a multilayer structure in which a first stack and a second stack having different refractive indices are stacked, the reflection wavelength of external light is appropriately adjusted even when the power supply of the liquid crystal display is turned off. The color of the area can be displayed.

In addition, the present invention can properly adjust the reflection wavelength of the external light by applying a multilayer structure in which the first laminate and the second laminate having different refractive indices are stacked so that the image is displayed as it is in the front direction when the image is displayed. In the lateral direction, a specific color is displayed so that an image cannot be seen, and thus it may be usefully used in a liquid crystal display device for information protection.

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

1 is a schematic cross-sectional view of a liquid crystal display according to an exemplary embodiment of the present invention.

As can be seen in FIG. 1, the liquid crystal display according to the exemplary embodiment includes a liquid crystal cell 100, an upper polarizer 200, a lower polarizer 250, and a multilayer structure 300.

The liquid crystal cell 100 includes a lower substrate 10, an upper substrate 30, and a liquid crystal layer 50 formed between the lower substrate 10 and the upper substrate 30. The liquid crystal cell 100 may be modified in various forms, which will be described later.

The upper polarizer 200 is formed on the upper surface of the liquid crystal cell 100 and is formed to have a predetermined optical axis to transmit only light of a specific optical axis.

The lower polarizer 250 is formed on the lower surface of the liquid crystal cell 100 and is formed to have a predetermined optical axis to transmit only light of a specific optical axis.

The upper polarizer 200 and the lower polarizer 250 are configured such that optical axes are perpendicular to each other, so that the transmittance of light may be adjusted as the arrangement state of the liquid crystal layer 50 of the liquid crystal cell 100 is changed. have.

The multilayer structure 300 is formed on an upper surface of the upper polarizer 200.

As shown in the enlarged view of FIG. 1, the multilayer structure 300 may be configured by alternately stacking the first stack 320 and the second stack 330 on the substrate 310. That is, after alternately stacking the first stack 320 and the second stack 330 on a substrate 310 made of glass or transparent plastic, the substrate 310 is stacked on the upper polarizer 200. I can attach it. However, the present invention is not necessarily limited thereto, and the first stack 320 and the second stack 330 are alternately stacked on the upper surface of the upper polarizing plate 200 without applying the substrate 310. The multilayer structure 300 may be configured.

The multilayer structure 300 is applied to perform a specific function in the liquid crystal display.

As an example, when the liquid crystal display according to the present invention is applied to a mobile phone or the like so that a specific color can be displayed while the power is turned off, the multilayer structure 300 reflects external light. Perform a function to display a specific color. This will be described in detail below.

As can be seen in FIG. 2, the multilayer structure 300 includes the first stack 320 and the second stack 330. In this case, the first stack 320 and the second stack 330 is made of a material having different refractive indices, and thus the first stack 320 and the second stack 330 having different refractive indices from each other. The layers are alternately stacked to form the multilayer structure 300.

When external light is incident on the multilayer structure 300 at a predetermined incident angle θ, the external light is reflected inside the multilayer structure 300. In this case, the reflected wavelength of the reflected light reflected in the multilayer structure 300 is expressed as Equation 1 below.

[Equation 1]

In Equation 1,? Denotes a reflection wavelength of reflected light, m denotes the total number of stacked layers of the first stack 320 and the second stack 330, and p is the first stack. It means the sum of the thickness d1 of the stack 320 and the thickness d2 of the second stack 330.

는 하기 식2와 같이 표시된다. In addition, in Formula 1

Is expressed as in Equation 2 below.

[Equation 2]

In Formula 2, n ₁ represents a refractive index of the first stack 320 and n ₂ represents a refractive index of the second stack 330.

As can be seen from Equations 1 and 2, the reflected wavelength λ of the reflected light is the thickness d1 of the first stack 320, the thickness d2 of the second stack 330, and the first the refractive index of the multilayer body 320) and the second stack 330, the total stacking number, and the first laminate 320, a refractive index (n ₁₎ and said second stack (330) of the (n ₂₎ It can be seen that it can be determined by.

Accordingly, the first stack 320 having the predetermined refractive index n ₁ and the second stack 330 having the predetermined refractive index n ₂ are appropriately selected, and the selected stack of the first stack 320 is selected. When the thickness d1 and the thickness d2 of the second stack 330 are appropriately adjusted to be stacked in a predetermined number of layers, the desired reflection wavelength λ of the reflected light can be obtained, and eventually, the power supply of the liquid crystal display device. Even when this is off, the specific color desired can be displayed.

In consideration of the above, the first stack 320 and the second stack 330 may use a transparent oxide, and in particular, the first stack 320 may use TiO ₂ . SiO ₂ may be used as the second laminate 330. When the multilayer structure 300 is formed of such a transparent oxide, it may be easily formed at a pressure of 10 ⁻³ to 10 ⁻⁵ Torr and a temperature range of 20 to 80 ° C. through an e-beam or a sputter. Can be.

In addition, when the first stack 320 and the second stack 330 are alternately stacked, the thickness of each of the first stack 320 and the second stack 330 is 10 ~ 800nm. Stacking in a range, the total number of stacking of the first stack 320 and the second stack 330 may be stacked in the range of 2 to 50 layers.

As described above, when the first stack 320 and the second stack 330 are alternately stacked to form the multi-layer structure 300, the power supply of the liquid crystal display device is turned off. A specific color, for example, blue, gold, pink, green, or the like, which is a color applied to the exterior case of the mobile phone, may be displayed.

3 is a view illustrating a result of experiments of colors displayed when the power is turned off in a liquid crystal display device to which various multilayer structures 300 according to the present invention are applied.

In the experiment according to FIG. 3, the multilayer structure 300 was constructed by alternately stacking the first stack 320 using TiO ₂ and the second stack 330 using SiO ₂ .

As can be seen in FIG. 3, when the total number of stacks of the first stack 320 and the second stack 330 is 26 layers and the total thickness is set to 1.57 μm, blue color is turned off when the LCD is turned off. I could see it displayed. In addition, when the total number of stacks of the first stack 320 and the second stack 330 was 18 layers and the total thickness was set to 1.64 μm, gold was displayed when the LCD was turned off. In addition, when the total number of stacks of the first stack 320 and the second stack 330 is 21 layers and the total thickness is set to 1.64 μm, pink color may be displayed when the LCD is turned off. there was.

On the other hand, as another example, when the liquid crystal display device according to the present invention is for protecting information from the person in the side seat in the moving means, the multi-layer structure 300 does not see the image from the left and right sides, only the image from the front Performs a function to make it visible.

As can be seen from Equation 1, the reflected wavelength λ of the reflected light may be determined by the thickness d1 of the first stack 320 and the thickness d2 of the second stack 330. In this case, the total thickness of the multilayer structure 300 in the front direction and the total thickness of the multilayer structure 300 in the left and right side directions are different from each other.

Therefore, when the first stack 320 and the second stack 330 are properly stacked to form the multilayer structure 300, the colors displayed in the front direction and the colors displayed in the left and right side directions are different from each other. Can be configured to As a result, the multi-layer structure 300 may be formed such that the color displayed in the front direction becomes white and the color displayed in the left and right side directions becomes a specific color, in which case the liquid crystal cell 100 in the front direction. The image to be implemented may be displayed as it is, and the image to be implemented in the liquid crystal cell 100 is not displayed due to a specific color displayed in the multilayer structure 300 in the left and right side directions, thereby protecting the desired information. It can be used for purposes.

As described above, when the liquid crystal display device is used for information protection, when the first stack 320 and the second stack 330 are alternately stacked to form the multilayer structure 300, the first stack 320 is formed. The thickness of each of the first stack 320 and the second stack 330 is in the range of 10 ~ 800nm, and the total number of stacks of the first stack 320 and the second stack 330 is 2 It can be laminated in the range of ~ 50 layers.

4 is a view showing an experimental result that the color display is different according to the viewing angle in the liquid crystal display device to which the multilayer structure 300 according to the present invention is applied.

In the experiment according to FIG. 4, the multilayer structure 300 was constructed by alternately stacking the first stack 320 using TiO ₂ and the second stack 330 using SiO ₂ , and the first stack. The total number of stacks 320 and the second stack 330 was 34 layers, and the total thickness was set to 0.45 µm.

As can be seen in Figure 4, a white color is displayed on the front side, it can be seen that a specific color, for example, cyan color is displayed on the left and right, when applying the multilayer structure 300 as described above to adjust the viewing angle characteristics It can also be easily used for the purpose of protecting information from the person next to the seat in the vehicle.

5 is a schematic cross-sectional view of a liquid crystal display according to another exemplary embodiment of the present invention.

The LCD according to another exemplary embodiment of the present invention illustrated in FIG. 5 is the same as the LCD according to FIG. 1 except that the formation position of the multilayer structure 300 is changed. Therefore, like reference numerals refer to like elements, and detailed descriptions of the same elements will be omitted.

In the above-described liquid crystal display according to FIG. 1, the multilayer structure 300 is formed on the upper surface of the upper polarizing plate 200, but in the liquid crystal display according to FIG. 5, the multilayer structure 300 is the upper polarizing plate 200 and the liquid crystal cell ( It is formed between 100).

Referring to FIG. 5, the multilayer structure 300 is more easily formed by stacking the first stack 320 and the second stack 330 on an upper surface of the upper substrate 30 constituting the liquid crystal cell 100. There is an advantage that can be formed.

In addition, when the liquid crystal display according to the present invention is applied to a mobile phone or the like and used for a purpose of displaying a specific color in a state in which the power is off, it is advantageous to have a small change in color shift depending on the viewing angle. In this regard, the LCD according to FIG. 5 may be more preferable than the LCD according to FIG. 1.

That is, the liquid crystal display according to FIG. 5 in which the multi-layer structure 300 is formed between the upper polarizing plate 200 and the liquid crystal cell 100, is shown in FIG. 1 in which the multi-layer structure 300 is formed on the upper surface of the upper polarizing plate 200. Compared with the liquid crystal display device, the color shift change is small.

FIG. 6A is a graph showing change in color shift for each viewing angle of the LCD according to the present invention shown in FIG. 1, and FIG. 6B is a graph showing change in color shift for each viewing angle of the LCD according to the present invention illustrated in FIG. 5. to be.

As shown in FIG. 6A, the LCD according to FIG. 1 having the multi-layer structure 300 formed on the upper polarizer 200 has some variation in color shift according to a viewing angle, but as shown in FIG. 6B. Likewise, in the liquid crystal display of FIG. 5 having the multi-layer structure 300 formed between the upper polarizer 200 and the liquid crystal cell 100, it can be seen that the color shift change according to the viewing angle is reduced.

7A to 7D are schematic cross-sectional views of the liquid crystal cell 100 according to various embodiments of the present disclosure. As shown in FIGS. 7A to 7D, the liquid crystal cell 100 includes a lower substrate 10, an upper substrate 30, and a liquid crystal layer 50 formed between the lower substrate 10 and the upper substrate 30. It is done by 7A to 7D illustrate only electrodes 60 and 80 for controlling the arrangement of the liquid crystal layer 50 in the liquid crystal cell 100, and a thin film transistor is formed on the lower substrate 10 as a switching element. The light blocking layer for preventing light leakage and the color filter layer for realizing color are formed on the upper substrate 30. Hereinafter, each will be described.

As shown in FIG. 7A, the liquid crystal cell 100 forms a pixel electrode 60 on the lower substrate 10 and a common electrode 80 on the upper substrate 30 to form the pixel electrode ( 60 may be configured to display an image by adjusting an arrangement state of the liquid crystal layer 50 through a vertical electric field between the common electrode 80. The liquid crystal cell 100 according to FIG. 7A corresponds to a twisted nematic (TN) mode, a vertical alignment (VA) mode, and the like.

As shown in FIG. 7B, the liquid crystal cell 100 alternately arranges the pixel electrode 60 and the common electrode 80 on the lower substrate 10 in parallel with each other so that the pixel electrode 60 and the common electrode are arranged in parallel. It may be configured to display an image by adjusting the arrangement of the liquid crystal layer 50 through a horizontal electric field between the electrodes (80). The liquid crystal cell 100 according to FIG. 7B corresponds to a so-called In-Plane Switching (IPS) mode.

As shown in FIG. 7C, the liquid crystal cell 100 arranges the pixel electrode 60 and the common electrode 80 with the insulating layer 70 therebetween on the lower substrate 10 to form the pixel electrode 60. ) May be configured to display an image by adjusting an arrangement state of the liquid crystal layer 50 through a fringe field between the common electrode 80 and the common electrode 80. The liquid crystal cell 100 according to FIG. 7C corresponds to a so-called FFS (Fringe Field Switching) mode.

As shown in FIG. 7D, the liquid crystal cell 100 may be configured to include a first pixel driven by a vertical electric field and a second pixel driven by a horizontal electric field. That is, in the first pixel, the pixel electrode 60 is formed on the lower substrate 10, the common electrode 80 is formed on the upper substrate 30, and in the second pixel, on the lower substrate 10. The pixel electrode 60 and the common electrode 80 may be alternately arranged in parallel to each other.

As described above, the liquid crystal cell 100 of FIG. 7D is applied to the so-called ECB (Electically Controlled Birefringenence) mode and IPS (In-Plane Switching) mode at the same time. This is particularly useful when a display device is applied.

Although not shown, the liquid crystal cell 100 includes a pixel driven by a vertical electric field and a pixel driven by a fringe field, so that the so-called ECB (Electically Controlled Birefringenence) and FFS (Fringe Field Switching) modes are simultaneously applied. In this case, it is also particularly useful when the liquid crystal display device is applied to protect the information from the person next to the seat in the moving means.

7A to 7D illustrate a liquid crystal cell 100 according to an embodiment of the present invention. The liquid crystal display device according to the present invention is not limited to the liquid crystal cell 100 as described above, but is driven in various modes. The liquid crystal cell 100 may include various forms.

1 is a schematic cross-sectional view of a liquid crystal display according to an exemplary embodiment of the present invention.

2 is a cross-sectional view of a multilayer structure according to one embodiment of the present invention.

3 is a view illustrating a result of experiments of colors displayed when a power is turned off in a liquid crystal display device having various multilayer structures according to the present invention.

4 is a view showing an experimental result that the color display is different according to the viewing angle in the liquid crystal display device to which the multilayer structure according to the present invention is applied.

5 is a schematic cross-sectional view of a liquid crystal display according to another exemplary embodiment of the present invention.

FIG. 6A is a graph showing change in color shift for each viewing angle of the LCD according to the present invention shown in FIG. 1, and FIG. 6B is a graph showing change in color shift for each viewing angle of the LCD according to the present invention illustrated in FIG. 5. to be.

7A to 7D are schematic cross-sectional views of liquid crystal cells according to various embodiments of the present disclosure.

<Description of the code | symbol about the structure of the principal part of drawing>

100: liquid crystal cell 200: upper polarizing plate

250: lower polarizer 300: multilayer structure

320: first stack 330: second stack

Claims (10)

A liquid crystal cell including a lower substrate, an upper substrate, and a liquid crystal layer formed between the lower substrate and the upper substrate; And Is formed on one surface of the liquid crystal cell, including a multi-layered structure consisting of a plurality of layers, And wherein the multi-layer structure comprises a first stack having a predetermined refractive index and a second stack having a different refractive index than the first stack. The method of claim 1, And each of the first stack and the second stack is made of a transparent oxide. The method of claim 2, The first stack is made of TiO ₂ , and the second stack is SiO ₂ . The method of claim 1, And wherein the multilayer structure is formed by alternately stacking the first stack and the second stack. 5. The method of claim 4, The thickness of each of the first stack and the second stack ranges from 10 to 800 nm, and the total number of stacks of the first stack and the second stack ranges from 2 to 50 layers. The method of claim 1, And the multilayer structure is formed on the liquid crystal cell. The method of claim 6, An upper polarizer is formed on the liquid crystal cell, and the multilayer structure is formed between the liquid crystal cell and the upper polarizer. The method of claim 6, An upper polarizer is formed on the liquid crystal cell, and the multilayer structure is formed on the upper polarizer. The method of claim 8, And the multilayer structure is formed on a substrate made of glass or transparent plastic, and the substrate is attached on the upper polarizing plate. The method of claim 1, The liquid crystal cell includes a first pixel and a second pixel which are different in mode from each other, The first pixel includes a pixel electrode formed on the lower substrate and a common electrode formed on the upper substrate to form a vertical electric field, and the second pixel is used to form a horizontal electric field or a fringe field. And a pixel electrode and a common electrode formed on the lower substrate.

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