KR20080057652A - Viewing angle control film and liquid crystal display including of the same - Google Patents

Abstract

A viewing angle control film and an LCD(Liquid Crystal Display) including the same are provided to convert an angle of a beam inputted from a backlight assembly into a certain angle by using the viewing angle control film having a certain refractive index and emit the converted beam to control a viewing angle of the LCD narrowly. A viewing angle control film includes a base film(411), beam blocking layers(412), and beam reflecting layers(413). The beam blocking layers are formed on the base film in a uniform separation distance. The beam reflecting layers are disposed on the base film exposed by the beam blocking layers, and are formed as material having a certain refractive index. The beam reflecting layers reflect/refract the beam inputted from the outside at a uniform angle, and emit the beam in an actually vertical direction.

Description

Viewing angle control film and liquid crystal display including of the same}

1 is an exploded perspective view of a liquid crystal display including a viewing angle control film according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along lines II to II 'after the liquid crystal display of FIG. 1 is assembled.

3 is a cross-sectional view of the viewing angle control film of FIG. 1.

4 is a cross-sectional view of a viewing angle control film according to another embodiment of FIG. 3.

(Explanation of symbols for the main parts of the drawing)

100: backlight assembly 210: liquid crystal panel

410 and 420: viewing angle control film 411: base film

412: light blocking layer 413: light reflecting layer

414: air layer

The present invention relates to a viewing angle control film and a liquid crystal display including the same, and more particularly, to a viewing angle control film capable of controlling the viewing angle of a liquid crystal display and a liquid crystal display including the same.

In recent years, liquid crystal displays have been in the spotlight as display means.

The liquid crystal display may include a liquid crystal panel for displaying an image and a backlight assembly for supplying light to the liquid crystal panel. Due to the thinness, light weight, and low power consumption of the liquid crystal display, the liquid crystal display may include various fields, for example. For example, it is used for monitors, TVs, mobile phones, and PDAs.

Moreover, the liquid crystal display device advances in the wide viewing angle technology using the viewing mode control film and the orientation mode of a liquid crystal, and is used also for the use of the big screen TV etc.

In recent years, while the importance of personal information is being emphasized, the liquid crystal display manufactured by the above-mentioned wide viewing angle technology has raised the possibility of information leakage by third parties in various public places. For example, privacy protection may be a problem in personal information communication devices or bank ATMs.

Accordingly, there is a need for a liquid crystal display having a narrow viewing angle.

It is an object of the present invention to provide a viewing angle control film capable of controlling the viewing angle of a liquid crystal display device.

Another object of the present invention is to provide a liquid crystal display device including the viewing angle control film.

The technical problems of the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

Viewing angle control film according to an embodiment of the present invention for achieving the above technical problem, the base film, a light blocking layer formed at a uniform separation distance on the base film, and the base film exposed by the light blocking layer And a light reflection layer disposed of the material having a predetermined refractive index and reflecting / refracting light incident from the outside at a predetermined angle and exiting in a substantially vertical direction.

The liquid crystal display according to the exemplary embodiment of the present invention for achieving the another technical problem includes the viewing angle control film.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

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

1 is an exploded perspective view of a liquid crystal display including a viewing angle control film according to an exemplary embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along lines II to II 'of the liquid crystal display of FIG.

1 and 2, the liquid crystal display device 500 may largely include a liquid crystal panel 210, a backlight assembly 100, and viewing angle control films 410 and 420.

The liquid crystal panel 210 serves to display an image, and may include a first display panel 211, a second display panel 212, and a liquid crystal layer (not shown) formed between the two display panels 211 and 212. have.

Here, a plurality of gate lines and data lines may be formed on the first display panel 211, and pixel electrodes arranged in a matrix shape and a plurality of thin film transistors connected thereto may be formed. In addition, the second display panel 212 may be formed with a black matrix, an RGB color pattern for expressing a color color, and a common electrode formed at portions except the pixel area. The liquid crystal layer may be composed of liquid crystal molecules having optical anisotropy.

A printed circuit board (PCB) 240 may be electrically connected to one side of the liquid crystal panel 210 by tape carrier packages (TCP) 220 and 230. The printed circuit board 240 may generate driving and control signals of the liquid crystal panel 210, and the tape carrier packages 220 and 230 may provide the driving and control signals to the liquid crystal panel 210. Here, the printed circuit board 240 may be bent to the rear side of the lower storage container 160 to be attached / coupled to the lower storage container 160.

The backlight assembly 100 may include a lamp unit 130, a light guide plate 140, a reflective sheet 150, optical sheets 120, a mold frame 110, a lower housing 160, and the like. have.

The lamp unit 130 may be disposed on at least one side of the light guide plate 140 and may include a light source 132 and a light source cover 131. The light source 132 of the lamp unit 130 may be, for example, a line light source such as a Cold Cathode Fluorescent Lamp (CCFL) or a Hot Cathode Fluorescent Lamp (HCFL). Point light sources, such as Light Emitting Diode (LED), can also be used. In this embodiment, an example using a cold cathode light source will be described.

The light guide plate 140 guides light emitted from the lamp unit 130 toward the upper side of the backlight assembly 100, that is, the liquid crystal panel 210. The light guide plate 140 may be formed of a material having good refractive index and good transmittance.

The reflective sheet 150 may be disposed under the light guide plate 140. The reflective sheet 150 is positioned between the light guide plate 140 and the lower storage container 160 to reflect the light leaking through the rear surface of the light guide plate 140 to the upper side of the light guide plate 140. As the reflective sheet 150, a material having good elasticity, excellent light reflection, and thinness may be used.

The optical sheets 120 may be disposed on the light guide plate 140. The optical sheets 120 may uniformly radiate the light guided by the light guide plate 140 to the upper side of the backlight assembly 100. The optical sheets 120 may be formed of a transparent resin such as an acrylic resin, a polyurethane resin, or a silicone resin.

The mold frame 110 may be combined with the lower storage container 160 to accommodate / fix the lamp unit 130, the light guide plate 140, the reflective sheet 150, and the optical sheets 120 as described above. In addition, the mold frame 110 may further include a protrusion 115 overlapping a predetermined width along an edge of the upper surface of the light guide plate 140, and the liquid crystal panel 210 is seated on the top surface of the protrusion 115. Can be stored. Here, as the mold frame 110, a synthetic resin having insulating properties may be used.

The lower storage container 160 may have a predetermined storage space formed therein to accommodate the mold frame 110, the reflective sheet 150, the light guide plate 140, the lamp unit 130, and the optical sheets 120. . The lower storage container 160 may be made of a metal material such as aluminum or aluminum alloy.

The upper receiving container 300 may be combined with the lower receiving container 160 to accommodate the liquid crystal panel 210 and the backlight assembly 100 therein and define an effective display area of the liquid crystal panel 210. The upper accommodating container 300 may be made of the same material as the lower accommodating container 160. In addition, the combination of the upper storage container 300 and the lower storage container 160 is obvious that all known coupling means can be used.

The viewing angle control films 410 and 420 may be located on at least one side of the liquid crystal panel 210, for example, between the backlight assembly 100 and the liquid crystal panel 210 and / or on the upper surface of the liquid crystal panel 210. have. In the present exemplary embodiment, the viewing angle control films 410 and 420 are disposed on both surfaces of the liquid crystal panel 210 as an example, but the present invention is not limited thereto. That is, the viewing angle control films 410 and 420 may be disposed on at least one surface of the liquid crystal panel 210. In other words, the viewing angle control films 410 and 420 may include the lower viewing angle control film 410 disposed between the first display panel 211 and the backlight assembly 100 of the liquid crystal panel 210 and the liquid crystal panel 210. The upper viewing angle control film 420 may be disposed on the upper surface of the second display panel 212.

In addition, the viewing angle control films 410 and 420 convert the light emitted from the backlight assembly 100 into a predetermined angle, for example, reflect or refracting the light, such that the light is substantially perpendicular to or below the liquid crystal panel 210. Can be incident. Therefore, the liquid crystal display 500 may have a narrow viewing angle.

The viewing angle control films 410 and 420 may be made of a material having a predetermined refractive index, and may be formed of a single layer or multiple layers. Such viewing angle control films 410 and 420 will be described in detail later with reference to FIGS. 3 to 5.

Polarizers 251 and 252 may be disposed between the liquid crystal panel 210 and the viewing angle control films 410 and 420, respectively. Here, the polarizing plates 251 and 252 selectively transmit only the light strongly vibrating in a specific direction from the light emitted from the backlight assembly 100. The polarizing plates 251 and 252 are disposed between the first display panel 211 of the liquid crystal panel 210 and the lower viewing angle control film 410 and the second display panel 212 of the liquid crystal panel 210. And an upper polarizing plate 251 disposed between the upper viewing angle control film 420.

Hereinafter, the viewing angle control film shown in FIG. 1 will be described in detail with reference to FIGS. 3 to 5. In the present embodiments, for convenience of description, the lower viewing angle control film, that is, the lower viewing angle control film disposed between the first display panel and the backlight assembly of the liquid crystal panel will be described as an example.

3 is a cross-sectional view of the viewing angle control film of FIG. 1.

Referring to FIG. 3, the viewing angle control film 410 according to the exemplary embodiment of the present invention may include a base film 411, a light blocking layer 412, and a light reflecting layer 413.

The base film 411 may be made of an insulating material having a predetermined thickness. For example, an insulating material such as polyimide resin or polyester resin may be used as the base film 411, but is not limited thereto.

The light blocking layer 412 is formed at a uniform distance on the base film 411, and serves to block light provided from the bottom, for example, light provided from the backlight assembly. The light blocking layer 412 may be formed using a material substantially the same as that of the black matrix of the liquid crystal panel, for example, Cr, but is not limited thereto. In addition, the light blocking layer 412 may be formed by depositing Cr on the entire surface of the base film 411 and photographing / etching it, but is not limited thereto.

A plurality of light reflection layers 413 may be formed on the base film 411 exposed by the light blocking layer 412 in a predetermined thickness. The light reflection layer 413 may be formed of a material having a predetermined refractive index.

In addition, like the light blocking layer 412, the light reflection layer 413 is coated or deposited on the front surface of the base film 411 so that the light blocking layer 412 is covered, and then exposed / developed or photographed / etched. Can be formed.

Here, a layer having a refractive index different from that of the light reflection layer 413, for example, an air layer 414, may be formed between the pair of light reflection layers 413 adjacent to each other. The air layer 414 may have a lower refractive index than the light reflection layer 413.

Hereinafter, the operation of the viewing angle control film 410 formed with the above structure will be described in detail.

1 and 3, the viewing angle control film 410 as described above may be disposed between the backlight assembly 100 and the liquid crystal panel 210. The base film 411 of the viewing angle control film 410 may be disposed to be adjacent to the backlight assembly 100, and the light reflection layer 413 may be disposed to be adjacent to the liquid crystal panel 210.

In addition, the light reflecting layer 413 may be formed of a single layer of a material having a predetermined refractive index. 414 may be formed.

Looking at the operation of the viewing angle control film 410, first, the light emitted from the backlight assembly 100 except for the light blocking layer 412 of the viewing angle control film 410, that is, the lower portion of the light reflection layer 413 Can be incident on a plane. The light incident on the light reflection layer 413 may be refracted or reflected at a predetermined angle at the interface between the light reflection layer 413 and the air layer 414.

In this case, the critical angle Θ _c of the light reflection layer 413 may be derived by Equation 1 below. Here, the critical angle Θ _c refers to the incident angle when the refractive angle of the light is 90 ° due to the difference in refractive index of the medium. Also, when the incident angle of the incident light is smaller than the critical angle Θ _c of the medium, the incident light may be totally reflected. Here, the incident angle of light may refer to an angle derived from the normal direction of the medium.

Subsequently, the operation of the viewing angle control film 410 with respect to light having various incident angles Θ ₁ , Θ ₂ , Θ ₃ emitted from the backlight assembly 100 with reference to [Equation 1], FIGS. 1 and 3. Explain about.

First, (a) illustrated in FIG. 3 illustrates a case where light emitted from the backlight assembly 100 is incident perpendicularly to the light reflection layer 413 of the viewing angle control film 410, that is, with an incident angle of 0 °. . In this case, the light incident on the light reflection layer 413 of the viewing angle control film 410 may be straight and re-entered in a direction substantially perpendicular to the liquid crystal panel 210.

Subsequently, (b) indicates that light emitted from the backlight assembly 100 is incident on the light reflection layer 413 of the viewing angle control film 410 at a predetermined angle, for example, an angle Θ ₁ below a critical angle Θ _c . The case is shown. In this case, light incident on the light reflecting layer 413 of the viewing angle control film 410 is totally reflected inside the light reflecting layer 413 and is approximately 80, which is slightly smaller than 90 ° at a narrow angle, for example, 90 °. The light may be re-entered into the liquid crystal panel 210 at an angle of ˜90 °.

Subsequently, (c) is an angle Θ _{2 at} which light emitted from the backlight assembly 100 is substantially equal to a predetermined angle, for example, the critical angle Θ _c , to the light reflection layer 413 of the viewing angle control film 410. It indicates the case of incident. In this case, the light incident on the light reflecting layer 413 of the viewing angle control film 410 is refracted along the interface of the light reflecting layer 413, for example, the interface between the light reflecting layer 413 and the air layer 414. Can be re-entered. The angle at which the incident light is refracted at the interface of the light reflection layer 413 may be approximately 90 °, and thus the light may be re-incident in a direction substantially perpendicular to the liquid crystal panel 210.

Finally, (d) indicates that light emitted from the backlight assembly 100 is at an angle Θ ₃ greater than a predetermined angle, for example, the critical angle Θ _c , to the light reflection layer 413 of the viewing angle control film 410. The case of incidence is shown. In this case, light incident to the light reflection layer 413 of the viewing angle control film 410 may be incident to the adjacent air layer 414 through the light reflection layer 413 at a predetermined refractive angle. In addition, light incident to the air layer 414 may be re-incident to the liquid crystal panel 210.

When the light incident on the light reflection layer 413 is refracted by the air layer 414, the angle becomes narrower, for example, significantly narrower than the angle Θ _{3 at} which light is incident on the light reflection layer 413. Can lose. Therefore, the light incident on the air layer 414 may be incident on the liquid crystal panel 210 at an angle of approximately 90 to 100 degrees, which is slightly larger than 90 degrees.

As described above, the liquid crystal display device 500 having a narrow viewing angle is adjusted by adjusting the angle of light provided from the backlight assembly 100 to the liquid crystal panel 210 by the viewing angle control film 410 having a predetermined refractive index. Can provide. In the present embodiment, the viewing angle control film 410 has a predetermined refractive index and is formed by using a single layer, and an air layer 414 disposed adjacent thereto and having a lower refractive index than the light reflecting layer 413 has been described as an example. . However, the present invention is not limited thereto, and the light reflection layer 413 including at least two materials having different refractive indices may be arranged side by side on the same plane of the base film 411. In addition, the light reflection layer may be formed of a multi-layered material having different refractive indices.

Hereinafter, a viewing angle control film having a light reflection layer having a multilayer structure will be described in detail with reference to FIG. 4.

4 is a cross-sectional view of a viewing angle control film according to another embodiment of FIG. 3. In the present embodiment, for convenience of description, members having the same functions as the members shown in FIG. 3 are denoted by the same reference numerals, and thus description thereof is omitted.

1 and 4, in the viewing angle control film 410 ′ according to the present embodiment, at least two materials having different refractive indices may be formed in a multilayer structure.

Specifically, the viewing angle control film 410 ′ may include a base film 411, a light blocking layer 412, a first light reflecting layer 413, a second light reflecting layer 415, and the like.

Herein, the light blocking layer 412 is formed and disposed at a uniform distance from the base film 411, and may serve to block light provided from the backlight assembly 100.

In addition, the first and second light reflection layers 413 and 415 may be formed in a multi-layered structure with a predetermined thickness on the base film 411 exposed by the light blocking layer 412. The first light reflecting layer 413 formed adjacent to the base film 411 may have a lower refractive index than the second light reflecting layer 415.

As described above, the first light reflecting layer between the first and second light reflecting layers 413 and 415 stacked in a multi-layer structure, that is, between a pair of adjacently arranged first and second light reflecting layers 413 and 415. A material having a refractive index lower than 413, for example an air layer 414, may be formed. Accordingly, the viewing angle control film 410 'of the present embodiment derives the critical angles Θ _c1 and Θ _c2 with respect to the first and second light reflection layers 413 and 415 according to Equation 2 below. can do.

Where θ _c1 is the first critical angle θ _c1 derived by the first light reflecting layer 413 and the second light reflecting layer 415, and θ _c2 is derived by the second light reflecting layer 415 and the air layer 414. Second critical angle θ _c2 . In addition, as described above, the first and second critical angles θ _c1 and θ _c2 refer to incident angles when the refractive angle of the light is 90 ° due to the difference in refractive index of the medium, and the incident light angle is the first critical angle ( If the angle is smaller than θ _c1 or the second critical angle θ _c2 , the incident light is totally reflected. Herein, the incident angle of light may refer to an angle derived from a direction A of the medium.

Subsequently, the viewing angle control film 410 ′ with respect to light having various incident angles θ ₁ , θ2, θ3, and θ4 emitted from the backlight assembly 100 with reference to [Equation 2], FIGS. 1 and 4. Will be described.

First, as illustrated in FIG. 4A, the light emitted from the backlight assembly 100 is perpendicular to the first light reflection layer 413 of the viewing angle control film 410 ′. That is, the case where the incident angle is incident at 0 ° is shown. In this case, light incident on the first light reflection layer 413 of the viewing angle control film 410 ′ is straight ahead and passes through the second light reflection layer 415, and the light is substantially perpendicular to the liquid crystal panel 210. Can be re-entered as

Subsequently, (b) indicates that the light emitted from the backlight assembly 100 has an angle greater than a predetermined angle, for example, the first critical angle θ _c1 , to the first light reflection layer 413 of the viewing angle control film 410 ′ ( The case of incident on θ ₁ ) is shown. In this case, the light incident on the first light reflecting layer 413 passes through the first light reflecting layer 413 at a predetermined refractive angle, and has a predetermined angle, for example, a second critical angle (2). may be incident at an angle θ _{2 that} is substantially the same as θ _c2 . Accordingly, the light incident on the second light reflecting layer 415, that is, the light incident at an angle θ ₂ substantially equal to the second critical angle θ _c2 , may be a boundary surface of the second light reflecting layer 415, for example, the second light reflecting layer 415. The light may be refracted in the direction A along the interface between the light reflection layer 415 and the air layer 414. The refracted light may be reincident in a direction substantially perpendicular to the liquid crystal panel 210.

Finally, (c) is an angle greater than the incident angle θ ₁ of the light emitted from the backlight assembly 100 into the first light reflecting layer 413 in the case of (b), that is, the first critical angle ( A case in which the first light reflection layer 413 is incident at an angle θ ₃ greater than θ _c1 is illustrated. In this case, light incident on the first light reflection layer 413 may pass through the first light reflection layer 413 at a predetermined refractive angle and be incident on the second light reflection layer 415 at a predetermined angle θ ₄ . have.

In addition, when the light incident on the second light reflection layer 415 has an angle θ ₄ greater than the second critical angle θ _c2 , the light incident on the second light reflection layer 415 may be refracted at a predetermined refractive angle once again. Can be. The light refracted by the second light reflection layer 415 may be incident to the adjacent air layer 414. Here, when the light incident on the second light reflection layer 415 is refracted by the air layer 414, the incident angle is remarkably narrower than the angle θ _{4 at} which light is incident on the second light reflection layer 415. do. Accordingly, the light incident on the air layer 414 may be reincident to the liquid crystal panel 210 at an angle of approximately 90 to 100 degrees, which is slightly larger than 90 degrees.

In this embodiment, the two materials having different refractive indices are described as an example in which a multi-layer is formed to form a viewing angle control film. However, the present invention is not limited thereto, and at least two materials having different refractive indices may be formed in a multi-layered structure, and one material having a step change in refractive index may be formed in a single layer structure.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

As described above, according to the viewing angle control film and the liquid crystal display including the same, the liquid crystal display is obtained by converting the light incident from the backlight assembly into a predetermined angle by using the viewing angle control film having a predetermined refractive index. It is possible to narrowly control the viewing angle of the device, thereby providing a liquid crystal display excellent in privacy.

Claims (8)

Base film; A light blocking layer formed on the base film at a uniform separation distance; And A light reflection layer disposed on the base film exposed by the light blocking layer and formed of a material having a predetermined refractive index and reflecting / refracting light incident from the outside at a predetermined angle to emit in a substantially vertical direction; Including viewing angle control film. According to claim 1, And an air layer formed on an upper portion of the light blocking layer between a pair of adjacent light reflecting layers and having a lower refractive index than the light reflecting layer. The method of claim 1, wherein the light reflecting layer has a predetermined critical angle, Light incident from the outside into the light reflection layer, When the light is incident at an angle of incidence below the critical angle, the light is totally reflected inside the light reflection layer, and is emitted at an angle of approximately 80 to 90 ° through the inside of the light reflection layer, When incident at the incident angle that is substantially equal to the critical angle, the light is refracted along the interface of the light reflecting layer and exits in a direction substantially perpendicular to the light reflecting layer, And the light is refracted at an angle of approximately 90 to 100 ° at an interface of the light reflection layer when the light is incident at the incident angle greater than the critical angle. According to claim 1, The light reflection layer, A first light reflecting layer having a first refractive index and formed to a predetermined thickness on the base film exposed by the light blocking layer; And A second light reflecting layer having a second refractive index and formed to a predetermined thickness on the first light reflecting layer to form a multilayer structure; And the first refractive index is smaller than the second refractive index. According to claim 1, The light reflecting layer is a viewing angle control film is formed thicker than the light blocking layer. A liquid crystal panel displaying an image; A backlight assembly disposed under the liquid crystal panel to supply light to the liquid crystal panel; And A viewing angle control film disposed between the liquid crystal panel and the backlight assembly and refracting / reflecting light provided from the backlight assembly at a predetermined angle, wherein the viewing angle control film according to any one of claims 1 to 5 is used. Liquid crystal display device comprising. The method of claim 6, The viewing angle control film is further disposed on the upper surface of the liquid crystal panel. The method of claim 6, And a polarizing plate disposed between the liquid crystal panel and the viewing angle control film.

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