KR101476447B1 - Liquid Crystal Display - Google Patents

Abstract

The present invention provides a light emitting device comprising: a light source; A lower polarizer disposed on the light source; A liquid crystal panel disposed on the lower polarizer plate and including liquid crystal molecules aligned in an IPS mode (In-Plane Switching Mode); A compensating film A on the liquid crystal panel; A Composition C compensation film located on the Composition A compensation film; And a top polarizer disposed on the C-state property compensating film, wherein the A and C compensating films have a negative phase difference with respect to a wavelength of light emitted from the light source.

Liquid crystal display, IPS, compensation film

Description

[0001] Liquid crystal display [0002]

The present invention relates to a liquid crystal display device.

2. Description of the Related Art In recent years, active matrix liquid crystal display devices have been used extensively in flat panel TVs, portable computers, monitors, and the like as their performance rapidly develops.

Conventionally, a twisted nematic (TN) liquid crystal display device is mainly used as an active matrix liquid crystal display device. In the twisted nematic mode, electrodes are arranged on two substrates, liquid crystal directors are twisted by 90 degrees , And applying a voltage to the electrode to drive the liquid crystal director.

Although a twisted nematic liquid crystal display device is widely spotlighted for providing excellent contrast and color reproducibility, it has a problem of a narrow viewing angle.

In order to solve the viewing angle problem of the TN mode, an IPS mode (In-Plane Switching Mode) has been introduced in which two electrodes are formed on one substrate and the director of the liquid crystal is adjusted by a transverse electric field generated between the two electrodes.

The IPS mode is a structure for orienting liquid crystal molecules on a plane, and can realize optical viewing angle characteristics by making the optical characteristics according to the viewing angle uniform. The IPS mode having a planar electrode structure serves as a display module for converting incident polarized light sources by 90 ° by inducing a 45 ° twist relative to the initial alignment by application of an electric field.

However, in the case of the conventional IPS mode, although the liquid crystal display device exhibits a wide viewing angle characteristic, the contrast ratio is reduced by the light source in the oblique viewing angle, thereby reducing the visibility of the display quality. Such a light source is a fundamental limitation of the polarizing plate. Even if the two polarizing plates form an angle of 90 ° at the front, the angle formed by the two polarizing plates in the oblique viewing angle direction becomes 90 ° or more.

Therefore, a method for solving the problem of light spots in the oblique viewing angle direction of the conventional IPS mode should be provided.

It is an object of the present invention to solve the problems of the background art described above and to solve the problem that a light source is generated in a diagonal direction in a diagonal direction when a liquid crystal panel including liquid crystal molecules aligned in an IPS mode is in a black state, And to provide a liquid crystal display device capable of compensating for luminance.

According to the present invention, A lower polarizer disposed on the light source; A liquid crystal panel disposed on the lower polarizer plate and including liquid crystal molecules aligned in an IPS mode; A compensating film A on the liquid crystal panel; A Composition C compensation film located on the Composition A compensation film; And a top polarizer disposed on the C-state property compensating film, wherein the A and C compensating films have a negative phase difference with respect to a wavelength of light emitted from the light source.

According to another aspect of the present invention, there is provided a light source device comprising: a light source; A lower polarizer disposed on the light source; A liquid crystal panel disposed on the lower polarizer plate and including liquid crystal molecules aligned in an IPS mode; A Composition compensation film on the liquid crystal panel; A compensating film A located on the compensating film; And an upper polarizer disposed on the A-axis compensation film, wherein the A-axis and C-axis compensation films have a negative phase difference with respect to a wavelength of light emitted from the light source.

When the wavelength of the light emitted from the light source is 550 nm, the compensating film A has a retardation of -100 nm to -160 nm with respect to the wavelength of the light and the retardation compensating film has a retardation of -80 nm to -120 nm And may have a phase difference.

When the wavelength of the light emitted from the light source is 550 nm, the Composition C compensation film has a retardation of -90 nm to -130 nm with respect to the wavelength of light, and the compensating film of the Composition A has a retardation of -110 nm to -130 nm And may have a phase difference.

The lower polarizer plate may include an absorption axis perpendicular to the liquid crystal panel, and the upper polarizer plate may include an absorption axis in the same direction as the liquid crystal panel.

The lower polarizer plate may include an absorption axis perpendicular to the liquid crystal panel, and the upper polarizer plate may include an absorption axis in the same direction as the liquid crystal panel.

The optical axis of the film A compensation film may be parallel to the optical axis of the absorption axis included in the upper polarizer plate.

The optical axis of the film A compensation film may be parallel to the optical axis of the absorption axis included in the lower polarizer plate.

The liquid crystal panel includes a liquid crystal layer positioned between a first substrate and a second substrate facing the first substrate, a thin film transistor driven in accordance with a scan signal, a capacitor storing a data voltage, A pixel electrode, a common electrode, and a color filter for performing color conversion.

The present invention provides a liquid crystal display device capable of solving the problem of generation of light spots in the oblique viewing angle direction and compensating for black luminance when the liquid crystal panel including the liquid crystal molecules aligned in the IPS mode is in a black state of implementation It is effective.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic block diagram of a liquid crystal display device according to a first embodiment of the present invention.

As shown in FIG. 1, the liquid crystal display according to the first embodiment of the present invention may include a light source 110. In addition, the lower polarizer 120 may include a lower polarizer 120 positioned on the light source 110. Further, the liquid crystal panel 130 may include a liquid crystal molecule positioned on the lower polarizer 120 and oriented in an IPS mode. The compensation film 150 includes a compensating film 151 disposed on the liquid crystal panel 130 and a compensating film 152 disposed on the compensating film 151 can do. Further, it may include an upper polarizer plate 160 positioned on the first C-compensation film 152. The first and second compensation films 151 and 152 included in the compensation film 150 may have a negative phase difference with respect to the wavelength of the light emitted from the light source 110.

The light source 110 may be a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), an external electrode fluorescent lamp (EEFL), and a light emitting diode : LED), but it is not limited thereto.

In addition, the light source 110 may select any one of an edge type in which the lamp is located on one side of the side, a dual type in which the lamp is located on both sides, and a direct type in which the lamps are arranged in a straight line. The light source 110 may be connected to an inverter and emit light by receiving power.

The lower polarizer 120 may include an absorption axis perpendicular to the liquid crystal panel 130 and the upper polarizer 160 may include an absorption axis in the same direction as the liquid crystal panel 130.

The lower polarizer plate 120 and the upper polarizer plate 160 may be stretched films and may be formed of a multilayer film such as a TAC (triacetate cellulose) film, a PVA (polyvinyl alcohol) film, a protective film, or a release film. The lower polarizer plate 120 and the upper polarizer plate 160 may transmit only light having a vibration plane in a predetermined direction in natural light having a vibration plane of 360 ° in all directions and absorb the remaining light to provide polarized light.

The compensation film 150 compensates the light emitted from the liquid crystal panel 130 with the compensation film 151 and compensates with the compensating film 152 again. However, the optical axis of the A-axis compensation film 151 may be parallel to the optical axis of the absorption axis included in the upper polarizer 160.

Here, in the case of the anti-A film 151, the phase value can be obtained by stretching a low-cost acrylic resin (PMMA) film and a polystyrene film in a specific direction. In the case of the C-component compensation film 152, a plate type or a coating type may be used.

The description of the compensation film 150 described above will be described in more detail below.

2 is a schematic cross-sectional view of the liquid crystal panel shown in Fig. The structure of the common electrode 132 and the pixel electrode 138 in the cross section of FIG. 2 is only for the sake of explanation of the liquid crystal panel, but the present invention is not limited thereto.

Referring to FIG. 2, the liquid crystal panel 130 may include a second substrate 130b bonded to the first substrate 130a. A TFT (not shown), a pixel electrode 138, a common electrode 132, and the like may be disposed on the first substrate 130a in accordance with a scan signal. A black matrix BM, a color filter CF, and the like may be disposed on the second substrate 130b.

Hereinafter, the structure of the thin film transistor located on the first substrate 130a, the color filter CF located on the second substrate 130b, etc. will be described in more detail.

A gate 131 may be positioned on the first substrate 130a. The gate 131 may be formed of any one selected from the group consisting of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper Or an alloy thereof. The gate 131 may be formed of a material selected from the group consisting of Mo, Al, Cr, Au, Ti, Ni, Ne, And may be a multilayer composed of any one selected or an alloy thereof. Further, the gate 131 may be a double layer of molybdenum / aluminum-neodymium or molybdenum / aluminum.

The common electrode 132 may be positioned on the first substrate 130a. The common electrode 132 can receive a common voltage from the common voltage wiring.

The first insulating layer 133 may be positioned on the gate 131 and the common electrode 132. The first insulating layer 133 may be a silicon oxide layer (SiOx), a silicon nitride layer (SiNx), or a multilayer thereof, but is not limited thereto.

The active layer 134 and the data line 136 may be disposed on the first insulating layer 133. The active layer 134 may be formed of a-Si or p-Si or the like, and the ohmic contact layer may be positioned to reduce electrical contact resistance. The data line 136 may supply a data signal so that the capacitor can store the data voltage.

On the active layer 134, the source 135a and the drain 135b may be located. The source 135a and the drain 135b may be formed of a single layer or a multilayer and may be formed of a single layer of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu). When the source 135a and the drain 135b are multilayered, they may be formed of a triple layer of molybdenum / aluminum-neodymium, molybdenum / aluminum / molybdenum or molybdenum / aluminum-neodymium / molybdenum.

A protective film 137 may be disposed on the source 135a and the drain 135b. The protective film 137 may be a silicon oxide film (SiOx), a silicon nitride film (SiNx), or a multilayer thereof, but is not limited thereto.

The pixel electrode 138 connected to the source 135a or the drain 135b may be located on the protective film 137. [ The pixel electrode 138 can form an electric field together with the common electrode 132.

On the other hand, a black matrix BM may be disposed on the second substrate 130b. The black matrix (BM) is made of a photosensitive organic material to which black pigment is added, and carbon black, titanium oxide, or the like can be used as the black pigment.

A color filter CF including red, green, and blue may be disposed between the black matrixes BM disposed on the second substrate 130b. The color filter CF may have other colors as well as red, green and blue.

The alignment films 139a and 139b may be positioned on the color filter CF which is the uppermost portion of the protective film 137 and the second substrate 130b which are the uppermost portions of the first substrate 130a.

The liquid crystal layer 140 may be positioned between the alignment layer 139a on the first substrate 130a and the alignment layer 139b on the second substrate 130b. The liquid crystal layer 140 includes liquid crystal molecules aligned in an IPS mode (In-Plane Switching Mode). Here, the alignment film 139 initially aligns the liquid crystal molecules contained in the liquid crystal layer 140.

In order to solve such a problem, the first embodiment of the present invention has an A-type compensation film 151 and a C-type compensation film 152 having a negative phase difference ) Between the liquid crystal panel 130 and the upper polarizer 160.

Hereinafter, this will be described in more detail with reference to Figs. 3 and 4. Fig.

3 is a view for explaining a compensation concept of a liquid crystal display according to a first embodiment of the present invention. FIG. 4 is a view for explaining a compensation optical path of a liquid crystal display according to a first embodiment of the present invention , And FIG. 5 is a view showing the azimuth angle of the panel plane and the angle of reagent angle from the vertical normal line.

Referring to FIGS. 3 and 4, the first embodiment of the present invention polarizes unpolarized light emitted from the light source 110 to the lower polarizer 120. The light emitted from the lower polarizing plate 120 is perpendicular to the absorption axis included in the lower polarizing plate 120 and does not coincide with the absorption axis "X" included in the upper polarizing plate 160. (See P1 region)

However, when the light emitted from the lower polarizer 120 passes through the two compensation films 150 of negative component having a negative phase difference, the light that is inconsistent with the absorption axis included in the upper polarizer 160 rotates, X "included in the absorption region 160 (refer to region P2)

Therefore, as shown in FIG. 4, the first embodiment of the present invention solves the problem that the mismatch area NM between the absorption axis of the lower polarizer and the absorption axis of the upper polarizer is generated, The light is absorbed in the absorption axis of the upper polarizer 160 to improve the light scattering phenomenon.

The present invention is characterized in that polarized light perpendicular to the lower absorption axis passing through the lower polarizer 120 through the compensation film 150 to compensate the light source of the oblique viewing angle of the polarizer is polarized The concept is to realize a high contrast ratio by minimizing the light source in black by changing the state.

Here, the A-axis compensation film 151 and the C-phase compensation film 152 included in the compensation film 150 are negative phase difference films in which negative refractive anisotropy is realized, and a negative A And a negative C-component compensation film 152 in which a phase difference in thickness exists between the film 151 and the compensation film 151 is used. Herein, the negative refractive index anisotropy is defined as negative when the refractive index in the direction of the optical axis is smaller than the refractive index in the other direction.

However, in order to exhibit the above-described effects, the compensation film 150 described above has the property that when the wavelength of the light emitted from the light source 110 is 550 nm, the A film having a retardation of -100 nm to -160 nm And a compensation film 151 and a retardation compensation film 152 having a retardation of -80 nm to -120 nm with respect to the wavelength of light.

The optical value for the phase difference between the A-axis compensation film 151 and the C-axis compensation film 152 included in the compensation film 150 is based on the case where the wavelength of the light emitted from the light source 110 is 550 nm The numerical values for the wavelength of light are merely presented, and the above-described optical numerical values can be applied to the case where the wavelength of the light is 550 nm or less or more.

Referring to FIG. 5, the compensation film 150 described in the first embodiment of the present invention, when deriving the optimum condition of the A-th compensation film 151 and the C-th compensation film 152, The lowest value of the black luminance can be used by referring to the angle φ at an azimuth angle of 45 ° and the viewing angle of 60 ° at the viewing angle angle θ from the vertical normal.

The numerical values of the wavelengths of light of the A-axis compensation film 151 and the C-axis compensation film 152 included in the compensation film 150 described in the first embodiment of the present invention will be described in more detail. Can be the same.

In the case of the film A compensation film 151, when the wavelength of the light is 550 nm, it may have a phase difference of -130 nm to -140 nm with respect to the wavelength of the light. In the case of the C-component compensation film 152, it may have a retardation of -80 nm to -90 nm with respect to the wavelength of light.

When the wavelength of light is 550 nm, the phase difference of the A-axis compensation film 151 is -130 nm to -140 nm, and the phase difference of the C-phase compensation film 152 is -80 nm to -90 nm, The non-polarized light emitted from the light source 110 can be rotated to be aligned with the absorption axis included in the upper polarizer 160.

Hereinafter, the second embodiment of the present invention will be described with reference to FIGS. 6 and 7, but the description of the first embodiment will be omitted in order to facilitate an understanding of the description.

FIG. 6 is a schematic structural view of a liquid crystal display device according to a second embodiment of the present invention, and FIG. 7 is a view for explaining a compensation optical path of a liquid crystal display device according to a second embodiment of the present invention.

As shown in FIG. 6, the liquid crystal display according to the second embodiment of the present invention may include a light source 210. In addition, the lower polarizer 220 may include a lower polarizer 220 positioned on the light source 210. In addition, the liquid crystal panel 230 may include a liquid crystal layer 230 disposed on the lower polarizer 220 and oriented in an IPS mode. Also included is a compensation film 250 comprising a Composition C Compensation Film 252 located on the liquid crystal panel 230 and a Composition A Compensation Film 251 located on the Composition C Compensation Film 252 can do. Further, it may include an upper polarizer 260 positioned on the A-axis compensation film 251. However, the first and second A-compensation films 252 and 251 included in the compensation film 250 may have a negative phase difference with respect to the wavelength of the light emitted from the light source 210.

The lower polarizer 220 may include an absorption axis perpendicular to the liquid crystal panel 230 and the upper polarizer 260 may include an absorption axis in the same direction as the liquid crystal panel 230.

The lower polarizer plate 220 and the upper polarizer plate 260 may be stretched type films and may be formed of a multilayer film such as a TAC (Triacetate Cellulose) film, a PVA (Poly Vinyl Alcohol) film, a protective film, or a release film. The lower polarizer plate 220 and the upper polarizer plate 260 may transmit only light having a vibration plane in a predetermined direction in natural light having a vibration plane of 360 ° in all directions and absorb the remaining light to provide polarized light.

The compensating film 250 compensates the light emitted from the liquid crystal panel 230 with the compensating film 252 and compensates the compensating film 251 with the compensating film 251 again. However, the optical axis of the A-axis compensation film 251 may be parallel to the optical axis of the absorption axis included in the lower polarizer 220.

Here, in the case of the film A compensation film 251, it is possible to obtain a phase value by stretching a low-priced acrylic resin (PMMA) -based film and a polystyrene-based film in a specific direction. In the case of the Composition C compensation film 252, a plate type or a coating type may be used.

7, the second embodiment of the present invention solves the problem that the inconsistency area NM between the absorption axis of the lower polarizer and the absorption axis of the upper polarizer is generated as in the first embodiment described above, The exiting unpolarized light is absorbed in the absorption axis of the upper polarizer 260 to improve the light scattering phenomenon.

The present invention is characterized in that polarized light perpendicular to a lower absorption axis passing through a lower polarizer (220) through a compensation film (250) in order to compensate a light source of a diagonal viewing angle of a polarizer is polarized The concept is to realize a high contrast ratio by minimizing the light source in black by changing the state.

The A-axis compensation film 251 and the C-axis compensation film 252 included in the compensation film 250 are composed of a negative C-compensation film 252 having a thickness phase difference and a negative C- A compensating film 251 of a negative component having a phase difference in a plane is used as the negative retardation film to be implemented. Herein, the negative refractive index anisotropy is defined as negative when the refractive index in the direction of the optical axis is smaller than the refractive index in the other direction.

In order to exhibit the above-described effects, the compensation film 250 described above has a C-shape having a phase difference of -90 nm to -130 nm with respect to the wavelength of light when the wavelength of the light emitted from the light source 210 is 550 nm And a compensation film 252 with a phase difference of -110 nm to -130 nm with respect to the wavelength of light.

The optical values for the phase difference between the Composition C compensation film 252 and the Composition A compensation film 251 included in the compensation film 250 are based on the case where the wavelength of the light emitted from the light source 210 is 550 nm The numerical values for the wavelength of light are merely presented, and the above-described optical numerical values can be applied to the case where the wavelength of the light is 550 nm or less or more.

The numerical values of the wavelengths of the C-type compensation film 252 and the A-type compensation film 251 included in the compensation film 250 described in the second embodiment of the present invention will be described in more detail. Can be the same.

In the case of the Composition C compensation film 252, when the wavelength of the light is 550 nm, it may have a phase difference of -90 nm to -120 nm with respect to the wavelength of the light. In the case of the A-axis compensation film 251, it may have a retardation of -110 nm to -120 nm with respect to the wavelength of light.

When the wavelength of light is 550 nm, the phase difference of the C-type compensation film 252 is -90 nm to -120 nm, and the phase difference of the C-type compensation film 251 is -110 nm to -120 nm. Polarized light emitted from the light source 210 can be rotated to match the absorption axis included in the upper polarizer 260. [

As described above, each embodiment of the present invention solves the problem that light scattering occurs in the oblique viewing angle direction when the liquid crystal panel including the liquid crystal molecules aligned in the IPS mode is in a black state, There is an effect of providing a device.

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. It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive. In addition, the scope of the present invention is indicated by the following claims rather than the detailed description. Also, all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

1 is a schematic configuration diagram of a liquid crystal display device according to a first embodiment of the present invention;

2 is a schematic sectional view of the liquid crystal panel shown in Fig.

3 is a view for explaining a compensation concept of a liquid crystal display device according to the first embodiment of the present invention.

4 is a view for explaining a compensation optical path of a liquid crystal display device according to a first embodiment of the present invention.

5 shows the azimuth angle of the panel plane and the angle of the reagent from the vertical normal.

6 is a schematic configuration diagram of a liquid crystal display device according to a second embodiment of the present invention;

7 is a view for explaining a compensation optical path of a liquid crystal display device according to a second embodiment of the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS

110, 210: light source 120, 220: lower polarizer plate

130, 230: liquid crystal panel 150, 250: compensation film

151, 251: A-compensation film 152, 252: C-compensation film

160, 260: upper polarizer

Claims (9)

Light source; A lower polarizer disposed on the light source; A liquid crystal panel disposed on the lower polarizer plate and including liquid crystal molecules aligned in an IPS mode (In-Plane Switching Mode); A compensating film A on the liquid crystal panel; A Composition C compensation film positioned on said Composition A compensation film; And And an upper polarizer disposed on the first C-compensation film, Wherein the compensating film (A) and the compensating film (C) have a negative phase difference with respect to a wavelength of light emitted from the light source, When the wavelength of the light emitted from the light source is 550 nm, The A-compensation film has a retardation of -100 nm to -160 nm with respect to the wavelength of the light And the phase-C compensation film has a retardation of -80 nm to -120 nm with respect to a wavelength of the light. Light source; A lower polarizer disposed on the light source; A liquid crystal panel disposed on the lower polarizer plate and including liquid crystal molecules aligned in an IPS mode; A compensation film on the liquid crystal panel; A first A compensation film positioned on said first C compensation film; And And an upper polarizer disposed on the A compensation film, Wherein the compensating film (A) and the compensating film (C) have a negative phase difference with respect to a wavelength of light emitted from the light source, When the wavelength of the light emitted from the light source is 550 nm, The first C-compensation film has a phase difference of -90 nm to -130 nm with respect to the wavelength of the light Wherein the compensating film (A) has a retardation of -110 nm to -130 nm with respect to a wavelength of the light. delete delete The method according to claim 1, Wherein the lower polarizer plate includes an absorption axis orthogonal to the optical axis of the liquid crystal panel Wherein the upper polarizer includes an absorption axis in the same direction as the optical axis of the liquid crystal panel. 3. The method of claim 2, Wherein the lower polarizer plate includes an absorption axis orthogonal to the optical axis of the liquid crystal panel Wherein the upper polarizer includes an absorption axis in the same direction as the optical axis of the liquid crystal panel. 6. The method of claim 5, Wherein the optical axis of the A-axis compensation film Wherein the upper polarizer is parallel to the optical axis of the absorption axis included in the upper polarizer. The method according to claim 6, Wherein the optical axis of the A-axis compensation film Wherein the polarizer is parallel to an optical axis of an absorption axis included in the lower polarizer plate. delete

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