KR20100104380A - Liquid crystal display device having viewing angle controlling sheet - Google Patents

Abstract

PURPOSE: A liquid crystal display having a sheet controlling a view angle is provided to install sheet controlling a view angle, and omits at least one film among a film retarding a phase and a film protecting a polarizer. CONSTITUTION: A sheet controlling a viewing angle(300) has a optical transmission part and a plurality of external light absorbing parts(303). The external light absorbing parts includes a light absorbing substance. The sheet controlling a viewing angle is arranged to front side of a first polarizing plate(200). A plurality of grooves(302a) is formed to light transmission part. A plurality of external absorbing parts is arranged within the groove. A film retarding a phase is not arranged to at least one place among liquid crystal cell(100) and a first polarizer or between the liquid cell and a second polarizer plate(200').

Description

Liquid crystal display device having a viewing angle control sheet

A liquid crystal display device is disclosed. More specifically, a liquid crystal display device having a viewing angle control sheet is disclosed.

Recently, as a flat panel display device used in notebook computers, televisions, or mobile phones, which require thinning, miniaturization, and low power consumption, a plasma display panel (PDP), a field emission display device (field) An emission display device (FED), a thin film transistor liquid crystal display device (TFT-LCD), and the like have been developed, and among these, a liquid crystal display device having excellent color reproducibility and thinness is most actively studied.

It is often desirable that the liquid crystal display has a wide viewing angle so that the viewer can obtain a good image at any position. The viewing angle means an angle at which the image formed on the monitor of the liquid crystal display device can be visually confirmed. This viewing angle is different from the angle at which color distortion occurs and refers to the angle at which the eye can see the screen on the monitor regardless of whether the color looks or not. The angle at which color distortion occurs is usually much smaller than the viewing angle. For example, in a commercially available liquid crystal display device, the angle at which color distortion occurs in a device whose viewing angle is indicated by 170 ° may be only about 90 °. The degree to which color distortion does not occur is called color reproducibility, and to obtain a high quality image, the viewing angle and color reproducibility must be improved at the same time.

The present invention provides a liquid crystal display device in which at least one of the phase delay films and optionally at least one film of the protective film of the polarizing plate may be omitted by providing the viewing angle control sheet.

One aspect of the invention,

Liquid crystal cell;

A first polarizing plate and a second polarizing plate respectively disposed on the front and rear surfaces of the liquid crystal cell;

A viewing angle control sheet disposed on a front surface of the first polarizing plate and having a light transmitting portion having a plurality of grooves disposed to be spaced apart from each other, and a plurality of external light absorbing portions disposed in the grooves and including a light absorbing material; And

And a backlight unit disposed on the rear surface of the second polarizing plate,

Provided is a liquid crystal display device in which a phase delay film is not disposed between at least one of the liquid crystal cell and the first polarizing plate and between the liquid crystal cell and the second polarizing plate.

The first polarizing plate may include a polarizing film and a protective film disposed on a rear surface of the polarizing film, and the viewing angle control sheet may be disposed in close contact with the front surface of the polarizing film.

The refractive index of the external light absorbing part may be different from the refractive index of the light transmitting part.

The difference n ₃₀₂ -n ₃₀₃ between the refractive index n ₃₀₂ of the light transmitting part and the refractive index n ₃₀₃ of the external light absorbing part may be 0.001 to 0.500.

According to an embodiment of the present invention, the liquid crystal display device having a viewing angle control sheet may omit at least one of the phase delay film and the protective film of the polarizing plate, thereby simplifying the manufacturing process and reducing the manufacturing cost. Can be provided.

Hereinafter, an LCD according to various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

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

Referring to FIG. 1, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal cell 100, a phase delay film 150, a pair of polarizing plates 200 and 200 ′, a viewing angle control sheet 300, and anti-reflection The film 400 and the backlight unit 500 is provided.

The liquid crystal cell 100 controls the polarization direction of light by using the principle that the arrangement state of the liquid crystal is changed according to the magnitude of the voltage applied thereto. Although not shown here, a pair of electrodes formed thereon And a liquid crystal layer disposed between the substrates. The operation modes of the liquid crystal for forming an image in the liquid crystal display include a twisted nematic (TN) mode, an in plane switching (IPS) mode, and a vertical alignment (VA) mode.

The phase delay film 150 is disposed between the liquid crystal cell 100 and the first polarizing plate 200 and has a slow axis and a fast axis, so that when the light passes, the fast phase light has a fast phase with respect to the light in the slow axis direction. For example, a stretched polymer film or a liquid crystal aligning film is used for the phase delay film 150. In the conventional liquid crystal display, such a phase delay film is used for each of the front and rear surfaces of the liquid crystal cell 100, but in the liquid crystal display of the present invention, the viewing angle control sheet 300 to be described later serves as the phase delay film 150. Since the phase delay film is not provided on the rear surface of the liquid crystal cell 100, the phase delay film 150 disposed on the front surface of the liquid crystal cell 100 may be omitted.

The first polarizer 200 is disposed on the front surface of the liquid crystal cell 100 and the front surface of the phase delay film 150 in FIG. 1, and only light that vibrates in a specific direction among the incident light while vibrating in various directions (ie, polarization) It performs the role of permeation. The first polarizing plate 200 includes a polarizing film 210 and a first protective film 211 and a second protective film 212 disposed on the front and rear surfaces of the polarizing film 210, respectively. In addition, the first protective film 211 may be omitted. In this case, for example, the polarizing film 210 and the viewing angle control sheet 300 are disposed to be in close contact with each other to form one of the viewing angle control sheets 300. A part, for example, the base film 301 takes the role of the first protective film 211. As used herein, "two components are arranged in close contact with each other" means that no component other than an adhesive layer (not shown) is interposed between the two components. The polarizing film 210 is, for example, after stretching a film of polyvinyl alcohol (polyvinyl alcohol (PVA), and then immersed the stretched film in a solution of iodine (I ₂ ) and dichroic dye, iodine molecules It can be prepared by arranging (I ₂ ) and dye molecules side by side in the stretching direction. The first protective film 211 and the second protective film 212 improve the durability by protecting the polarizing film 210 from moisture and preventing surface damage of the polarizing film 210, for example, cellulose tri acetate ( TAC).

The second polarizing plate 200 ′ is disposed in close contact with the rear surface of the liquid crystal cell 100, and the first protective film 211 ′ disposed on the front and rear surfaces of the polarizing film 210 ′ and the polarizing film 210 ′, respectively. ) And a second protective film 212 ′. Since the role and material of the second polarizing plate 200 ′ are the same as those of the first polarizing plate 200 described above, a detailed description thereof will be omitted.

The viewing angle control sheet 300 is disposed on the front surface of the first polarizing plate 200 to widen the viewing angle by refracting / reflecting light incident in a direction substantially perpendicular to the smooth surface thereof to spread a predetermined angle laterally with respect to the vertical direction. It plays a role to improve color reproducibility. The viewing angle control sheet 300 includes a light transmitting portion 302 having a plurality of grooves 302a disposed to be spaced apart from each other, and a plurality of external light absorbing portions 303 disposed in the grooves 302a and including a light absorbing material. ), Which may be disposed on the base film 301.

The base film 301 supports the light transmitting unit 302. The base film 301 may be, for example, polyethersulphone (PES), polyacrylate (PAR), polyetherimide (PEI), polyethylene naphthalate (PEN), Polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyallylate, polyimide, polycarbonate (PC), cellulose tri acetate (TAC), cellulose acetate propio It may be formed of one or more materials selected from the group consisting of cellulose acetate propionate (CAP). In addition, the base film 301 may be omitted as necessary.

The light transmission part 302 is a part which transmits light. The light transmitting portion 302 may be formed of a curable resin. The light transmitting portion 302 may be formed of, for example, an acrylate resin that is cured by ionizing radiation or thermal energy.

The external light absorbing unit 303 absorbs external environmental light, thereby improving the contrast ratio in the bright room condition. The external light absorbing part 303 may be formed of a material capable of absorbing light, for example, a black inorganic material, a black organic material, and / or a blackened metal. In the case of blackened metal, since the electrical resistance is low, the external light absorbing part 303 formed therefrom may perform an electromagnetic shielding function because the electrical resistance may be controlled by adjusting the content of the metal powder or the thickness of the metal thin film. . The external light absorbing part 303 may be formed of, for example, an ultraviolet curable resin containing carbon. The external light absorbing part 303 is configured to have a different refractive index than that of the light transmitting part 302, thereby refracting / reflecting light at an interface between the external light absorbing part 303 and the light transmitting part 302, thereby adopting a viewing angle of the liquid crystal display device. Increase and improve color reproducibility. The difference n ₃₀₂ -n ₃₀₃ between the refractive index n ₃₀₂ of the light transmitting part 302 and the refractive index n ₃₀₃ of the external light absorbing part 303 may be, for example, 0.001 to 0.500. If the difference in refractive index (n ₃₀₂ -n ₃₀₃ ) is less than 0.001, the total reflection effect is not implemented.

The anti-reflection film 400 is disposed on the front of the viewing angle control sheet 300 to adjust the transmittance of visible light, thereby minimizing eye fatigue of an observer watching for a long time. By arranging the antireflection film 400 as described above to adjust the visible light transmittance of the liquid crystal display device, in addition to the selective absorption effect of the visible light, the secondary effect of improving the color reproducibility such as contrast ratio can be obtained. The antireflection film 400 may be a mixture of indium tin oxide (ITO) and silicon oxide (SiO ₃ ), a mixture of nickel chromate (NiCr) and silicon oxide (SiO ₂ ), titanium oxide or a special fluorine resin having a low refractive index. It can be prepared using. In addition, the anti-reflection film 400 may be omitted as necessary.

The backlight unit 500 is disposed on the rear surface of the second polarizer 200 ′ and serves to provide light L to the liquid crystal cell 100 through the second polarizer 200 ′. The light source of the backlight unit 500 includes a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), a light emitting diode (LED), and a flat fluorescent lamp (FFL).

2 is a schematic cross-sectional view of a liquid crystal display according to another exemplary embodiment of the present invention. In the following, the same reference numerals as in the above-described drawings indicate the same member or parts of the same member. However, reference numeral 212 in the drawing indicates a protective film.

2 is different from the liquid crystal display of FIG. 1 in that the phase delay film is not provided between the liquid crystal cell 100 and the first polarizing plate 200, and the first polarizing plate 200 is also polarized. There is no protective film on the front of the (210). Specifically, the polarizing film 210 of the first polarizing plate 200 and the base film 301 of the viewing angle control sheet 300 are disposed in close contact with each other. In addition, the base film 301 may be omitted. In this case, the polarizing film 210 and the light transmitting portion 302 of the viewing angle control sheet 300 are disposed to be in close contact with each other. When a part of the polarizing film 210 and the viewing angle control sheet 300 are disposed in close contact with each other, the viewing angle control sheet 300 takes the role of a protective film.

Components not described above among the components of the liquid crystal display of FIG. 2 are the same as those described in the liquid crystal display of FIG. 1, and thus, detailed descriptions of these components will be omitted.

In the liquid crystal display according to the exemplary embodiment of the present invention having the above configuration, at least one film of the phase delay film and the protective film of the polarizing plate may be omitted by providing the viewing angle control sheet, thereby simplifying the manufacturing process and manufacturing cost. This can be reduced.

Although the preferred embodiment according to the present invention has been described above with reference to the drawings, this is merely illustrative, and those skilled in the art can understand that various modifications and equivalent other embodiments are possible. There will be. Therefore, the protection scope of the present invention should be defined by the appended claims.

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

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

[Description of Symbols for Main Parts of Drawing]

100: liquid crystal cell 150: phase delay film

200, 200 ': polarizer 210, 210': polarizer

211, 211 ', 212, 212': Protective film 300: Viewing angle control sheet

301: base film 302: light transmitting unit

302a: groove 303: outside light absorbing portion

400: antireflection film 500: backlight unit

Claims (4)

Liquid crystal cell; A first polarizing plate and a second polarizing plate respectively disposed on the front and rear surfaces of the liquid crystal cell; A viewing angle control sheet disposed on a front surface of the first polarizing plate and having a light transmitting portion having a plurality of grooves disposed to be spaced apart from each other, and a plurality of external light absorbing portions disposed in the grooves and including a light absorbing material; And And a backlight unit disposed on the rear surface of the second polarizing plate, And a phase delay film is not disposed between at least one of the liquid crystal cell and the first polarizing plate and between the liquid crystal cell and the second polarizing plate. The method of claim 1, The first polarizing plate includes a polarizing film and a protective film disposed on a rear surface of the polarizing film, and the viewing angle control sheet is disposed in close contact with the front surface of the polarizing film. The method according to claim 1 or 2, The refractive index of the external light absorbing portion is different from the refractive index of the light transmitting portion. The method of claim 3, And a difference n ₃₀₂ -n ₃₀₃ between the refractive index n ₃₀₂ of the light transmitting part and the refractive index n ₃₀₃ of the external light absorbing part is 0.001 to 0.500.

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