CN101738786B - LCD panel - Google Patents

Abstract

The present invention provides a liquid crystal panel, comprising a color filter substrate and an array substrate arranged opposite to each other, wherein a first polarizing plate including a first base layer, a first compensation film and a first polarizing film is attached to the color filter substrate, A second polarizer including a second polarizing film, a second compensation film and a second base layer is attached on the array substrate, wherein: the alignment angle of the first base layer is larger or smaller than the alignment angle of the second base layer. It can be seen from the above technical scheme that the present invention makes the alignment angles of the base layers in the two polarizers different by adjusting the size of the alignment angle in the base layer connected to the compensation film, thereby improving the use of the wide viewing angle polarizer "WV- The inversion of the photoelectric characteristic curve in the dark state caused by EA" improves the color temperature of the dark state, improves the contrast of the liquid crystal display in the dark state, and improves the stability of the contrast.

Description

LCD panel

technical field

The invention relates to liquid crystal display technology using optical compensation means, in particular to a liquid crystal panel. the

Background technique

The market of liquid crystal display is growing rapidly, and the application fields are continuously expanding, especially the application of large-size liquid crystal TV, which requires the liquid crystal display to have a wide range of viewing angles. The main component of a liquid crystal display is a liquid crystal panel, which includes an array substrate and a color filter substrate in a pair of boxes, and a liquid crystal is arranged between them. The liquid crystal deflects under the action of voltage, and the degree of deflection of the liquid crystal can be controlled by controlling the magnitude of the voltage, so as to achieve the purpose of modulating the light transmittance, that is, the gray scale presented by the liquid crystal panel can be modulated. the

Due to the defect of narrow viewing angle in the existing liquid crystal display, various display modes have been proposed in the prior art to overcome the defect of narrow viewing angle, including 90° twisted nematic liquid crystal plus compensation film (Twisted Nematic+film; hereinafter referred to as: TN+film) Mode, Multi-domain Vertical Alignment (MVA) mode, Patterned Vertical Alignment (PVA) mode, In-Plane Switching (IPS) mode And a planar driving (Fringe Field Switching; hereinafter referred to as: FFS) mode using a fringe field, etc. the

Although the above-mentioned display modes have been proposed successively and gradually realized industrialization, actual use shows that the above-mentioned display modes still have corresponding defects. The MVA mode needs to manufacture a complex raised structure on the color filter substrate side, that is, the color filter, which increases the manufacturing cost; the PVA mode needs to make the pixel electrode into a complex slit structure, which affects the light utilization efficiency; and The IPS mode and the FFS mode require high process control precision, so the manufacturing process is difficult. the

The TN+film mode is simple and convenient, and the effect is obvious. It has gradually transitioned from the previous "WV-SA" mode to the current "WV-EA" mode. Adding a compensation film is to add a layer of compensation film on the polarizer. For example, Fig. 1 shows a structural schematic diagram of a wide viewing angle polarizer including a compensation film in the prior art. The polarizer can include a release film 10, an adhesive layer 20 , base layer 30 , compensation film 40 , polarizing film 50 , supporting film 60 and protective film 70 . Wherein, the polarizing film 50 can be made of polyvinyl alcohol (Polyvinyl Alcohol; PVA for short), the compensation film 40 can be made of a discotic liquid crystal layer (Discotic Liquid Crystal; hereinafter referred to as: DLC), and the base layer 30 is connected to the compensation film 40, which can It is made of triallyl cyanurate (TAC for short). The so-called compensation film, also known as the retardation film, changes the phase of the light transmitted through it with its unique material, thereby offsetting the retardation of the light phase by the liquid crystal molecules, reducing or eliminating the phase delay of the light emitted from the polarizer, and finally improving the viewing angle of the liquid crystal display. expand. The direction of the light transmission axis on the polarizing film, the compensation film and the base layer can be defined by the magnitude of the para-angle. The so-called alignment angle refers to the angle between the direction of the light transmission axis and the longitudinal symmetry axis of the plane where the liquid crystal panel is located. Taking the alignment angle of the base layer as an example, as shown in Figure 2, it is a schematic diagram of the alignment angle relationship of the base layer connected to the compensation film on the liquid crystal panel in the prior art, and the dotted line Y is the longitudinal axis of symmetry of the plane where the liquid crystal panel is located , the line R1 indicates the light transmission axis direction of the base layer on the upper polarizer, the angle α1 between the line R1 and the dotted line Y is the alignment angle of the base layer, and the line R2 indicates the base layer on the lower polarizer The light from the bottom layer passes through the axial direction, and the included angle α2 is the alignment angle of the bottom layer. Generally, the alignment angles of the polarizing film, the compensation film and the base layer on the same polarizer are all 45°, that is, the directions of the light transmission axes are consistent, and the directions of the light transmission axes of the upper and lower polarizers are perpendicular to each other, as shown in Figure 2. the

However, the currently used polarizers with wide viewing angles cause the photoelectric characteristic curve of the liquid crystal display to be reversed in the dark state, as shown in FIG. 3 , which is a graph showing the transmittance of the existing liquid crystal panel and the applied voltage. The so-called photoelectric characteristic curve is the relationship curve between the transmittance of liquid crystal molecules to light and the voltage applied on both sides of the liquid crystal molecules. When the light transmittance of liquid crystal molecules decreases to a certain extent, the light transmittance of liquid crystal molecules increases instead. the

The effect of the inversion of the photoelectric characteristic curve is to increase the brightness of the liquid crystal display in the dark state, and the increase in the brightness of the dark state will lead to a decrease in the contrast ratio in the dark state. Contrast refers to the ratio of the maximum brightness to the minimum brightness that the display device can achieve, that is, the ratio of the brightness of the bright state to the brightness of the dark state. At present, the most effective way to improve the contrast ratio is to reduce the brightness of the dark state. Therefore, the inversion characteristic of the photoelectric characteristic curve greatly affects the stability of the contrast ratio. At present, the contrast value of liquid crystal displays for mainstream computers is generally 800-1000:1, and the demand for liquid crystal displays above 1000:1 is increasing. It is difficult to meet the market demand if the contrast ratio and its stability cannot be effectively improved. In the prior art, it is generally possible to adjust the friction angle of the alignment film in the production process to change the twist angle of the liquid crystal in the liquid crystal panel to improve the photoelectric characteristic curve, but this will increase the power consumption of driving the rotation of the liquid crystal molecules, and also make the dark state The color temperature and TCO'03 (Swedish Confederation of Professional Employees, The Swedish Confederation of Professional Employees; hereinafter referred to as: TCO) have a tendency to degrade the uniformity of brightness with the change of viewing angle, as shown in Figure 4 for a liquid crystal panel in the prior art The comparison chart of the photoelectric characteristic curve, as the twist angle becomes smaller, the inversion of the photoelectric characteristic curve is improved, but as shown in Figure 5, the brightness of the liquid crystal panel changes with the twist angle when the friction angle of the alignment film is changed in the prior art. Schematic diagram of numerical simulation calculation, the axis of abscissa is the twist angle, and the axis of ordinate is the change percentage of brightness uniformity with viewing angle specified in TCO'03. It can be seen that as the twist angle becomes smaller, the brightness that changes with viewing angle Uniformity has a tendency to deteriorate and has a greater effect on the percent change in brightness uniformity. the

Contents of the invention

The object of the present invention is to provide a liquid crystal panel to improve the inversion characteristic of the photoelectric characteristic curve in the dark state of the liquid crystal display and improve the stability of the contrast of the liquid crystal display. the

In order to achieve the above object, the present invention provides a liquid crystal panel, comprising a color filter substrate and an array substrate arranged opposite to each other, wherein the color filter substrate is attached with a first base layer, a first compensation film and a first polarizer. The first polarizing plate of the film, the second polarizing plate comprising the second polarizing film, the second compensation film and the second base layer is attached on the array substrate, wherein: the alignment angle of the first base layer is larger than that of the second base layer Parallel angle of the bottom layer, the light transmission axes on the first polarizing film and the second polarizing film are perpendicular to each other;

The alignment angle of the first base layer is larger than the alignment angle of the first polarizing film, and the alignment angle of the second base layer is equal to the alignment angle of the second polarizing film. the

Preferably, the alignment angle of the first base layer can be greater than 45° and less than or equal to 50°, and the alignment angle of the second base layer is 45°. the

More preferably, when the alignment angle of the first polarizing film and the second polarization film is 45°, the alignment angle of the first base layer is 47°, and the alignment angle of the second base layer is 45°. the

Alternatively, the alignment angles of the first base layer and the second base layer may also be set oppositely. the

It can be seen from the above technical scheme that the present invention makes the alignment angles of the base layers connected to the compensation film in the two polarizers different in size by adjusting the size of the alignment angle of the base layer connected to the compensation film, thereby improving the use of wide-viewing angle polarizers. The inversion of the photoelectric characteristic curve in the dark state caused by the film "WV-EA" improves the color temperature of the dark state, improves the contrast of the liquid crystal display in the dark state, and improves the stability of the contrast. the

Description of drawings

Fig. 1 is a kind of wide viewing angle polarizer structure schematic diagram that comprises compensation film in the prior art;

Fig. 2 is the schematic diagram of the para-angle relationship of the base layer connected with the compensation film on the liquid crystal panel in the prior art;

Fig. 3 is a graph of the transmittance of the existing liquid crystal panel and the applied voltage;

Fig. 4 is the comparison diagram of the photoelectric characteristic curve of the liquid crystal panel in the prior art;

Fig. 5 is the numerical schematic diagram of the simulated calculation of the luminance uniformity of the liquid crystal panel changing with the twist angle when changing the rubbing angle of the alignment film in the prior art;

Fig. 6 is the schematic diagram of the para-angle relation of two base layers in the liquid crystal panel embodiment of the present invention;

Fig. 7 is the comparison diagram of the photoelectric characteristic curve of the liquid crystal panel of the present invention;

Fig. 8 is the numerical schematic diagram of the simulated calculation of the luminance uniformity of the liquid crystal panel of the present invention changing with the viewing angle;

Figure 9 is a comparison diagram of the upper and lower viewing angle characteristic curves of the liquid crystal panel of the present invention;

Fig. 10 is a comparative diagram of left and right viewing angle characteristic curves of the liquid crystal panel of the present invention. the

Detailed ways

The present invention will be described in further detail below through specific embodiments and in conjunction with the accompanying drawings. the

FIG. 6 is a schematic diagram of the relationship between the alignment angles of the two base layers in the embodiment of the liquid crystal panel of the present invention. In this embodiment, the liquid crystal panel mainly includes two upper and lower substrates, that is, a color filter substrate and an array substrate, and the liquid crystal layer is encapsulated in the two substrates. Wherein, a "WV-EA" polarizer is attached to the outer surface of the color filter substrate, that is, the first polarizer, and a lower "WV-EA" polarizer, that is, the second polarizer, is attached to the outer surface of the array substrate. The structure of the first polarizer includes a first peeling film, a first adhesive layer, a first base layer, a first compensation film, a first polarizer film, a first support film and a first protective film attached in sequence, and the second polarizer The structure includes a second release film, a second adhesive layer, a second base layer, a second compensation film, a second polarizing film, a second support film and a second protection film attached in sequence. Similar to the polarizer structure shown in Figure 1. Wherein, the light transmission axes on the first polarizing film and the second polarizing film are perpendicular to each other, and the alignment angles are both 45°. The light transmission axis direction of the first base layer connected to the first compensation film is approximately the same as the light transmission axis direction of the first polarizing film but has an offset angle. As shown in Figure 6, the alignment angle of the first base layer θ1 is 47°, which is larger than the alignment angle of the first polarizing film to which it is attached. The direction of the light transmission axis of the second base layer connected to the second compensation film is the same as the direction of the light transmission axis of the second polarizing film, that is, the para-angle θ2 of the second base layer is 45°, which is equal to the attached Alignment angle of the second polarizing film. the

In this embodiment, the alignment angle of the first base layer is changed so that the alignment angles of the base layers connected to the two compensation films are different. The unequal design of the alignment angles on the base layer connected to the two compensation films has a great influence on improving the optoelectronic properties of the liquid crystal panel. As shown in Figure 7, it is a comparison diagram of the photoelectric characteristic curves of the liquid crystal panel of the present invention, wherein the alignment angle of the second base layer is maintained at 45°, and the alignment angles corresponding to the first base layer of each curve are 43° to 50°. When the photoelectric characteristic curve. From the comparison of the graphs, it can be seen that with the increase of the first base layer paralocation angle, the dark state inversion part of the light characteristic curve of the liquid crystal panel is significantly improved, and the color temperature of the dark state is improved, which is conducive to improving the dark state. When the contrast of the liquid crystal display is maintained, the stability of the contrast of the liquid crystal display is maintained. Therefore, the design of the alignment angle of the base layer connected with the compensation film is preferably to set the alignment angle of the first base layer greater than the alignment angle of the attached first polarizing film, and the alignment angle of the second base layer is equal to The alignment angle of the attached second polarizing film. the

In a specific application, the design of the alignment angle of the base layer is also restricted by other parameters, and it must be ensured that the other parameters are not greatly affected on the premise of improving the photoelectric characteristic curve. Fig. 8 is a numerical schematic diagram of simulated calculation of brightness uniformity changing with viewing angle in the liquid crystal panel TCO'03 of the present invention, wherein the alignment angle of the second base layer is kept at 45°, and the axis of abscissa is the alignment of the first base layer Azimuth angle, the axis of ordinate is the percentage change of luminance uniformity with viewing angle as specified in TCO'03. As can be seen from FIG. 8 , with the increase of the alignment angle of the first base layer, the simulated calculation value of the brightness uniformity with the viewing angle will increase by nearly 0.035% for every degree increase, that is, the uniformity is deteriorated. Generally speaking, when the simulated value varies by more than 0.1%, the actual value will vary by nearly 3%. In order to ensure uniformity of brightness with viewing angle in TCO'03 and to optimize the photoelectric characteristic curve, it is preferable that when the alignment angles of the first polarizing film and the second polarizing film are both 45°, the opposite angle of the second base layer The angle is set to 45°, and the alignment angle of the first base layer is set to be greater than 45° and less than or equal to 50°, and the preferred value is that the alignment angle of the first base layer is 47°. the

FIG. 9 and FIG. 10 are comparison diagrams of the characteristic curves of the liquid crystal panel of the present invention for the vertical viewing angle and the left and right viewing angle respectively. In FIGS. 9 and 10 , the axes of abscissas are the angles of view respectively, and the axes of ordinates are the simulated values of the contrast ratio of the liquid crystal panel. Similar to Figure 7, the curves correspond to the second base layer alignment angle of 45°, and the first base layer alignment angles are 43°, 44°, 45°, 46°, 47°, 48°, 49° ° and 50° curves. As can be seen from Figures 9 and 10, when the alignment angle of the first base layer is gradually changed and that of the second base layer is not equal, the change of the viewing angle characteristic curve is not large, and they are basically coincident. The unequal design of the angle of view basically has no effect on the viewing angle characteristics. the

From the above analysis, it can be seen that the liquid crystal panel of the present invention can effectively improve the inversion characteristics of the photoelectric characteristic curve of the liquid crystal panel in the dark state due to the use of polarizers with different alignment angles of the base layer connected to the compensation film, which is conducive to improving the dark state. State color temperature, improve the contrast of the LCD in the dark state and the stability of the overall contrast. the

As can be seen from the graphs shown in Fig. 8 and Fig. 5, the liquid crystal panel design method of the present invention with different alignment angles of the base layer, compared with the method of changing the friction to improve the photoelectric characteristic curve, makes TCO'03 The percentage change of brightness uniformity with viewing angle has a small range of change, which is of great benefit to the stability of production. the

In the liquid crystal panel of the present invention, the first polarizing film and the first compensation film and the first base layer connected thereto may be attached on the color filter substrate, and the second polarizing film and the second compensation film and the first base layer connected thereto may be attached to the color filter substrate. The second base layer can be attached on the array substrate, then the first polarizer can also be called the upper polarizer, and the second polarizer can also be called the lower polarizer. The alignment angle of the base layer connected to the compensation film on the upper polarizer is 47°, and the alignment angle of the base layer connected to the compensation film on the lower polarizer is 45°, which is a better technical solution. On the contrary, the alignment angle of the first base layer is set to be equal to the alignment angle of the first polarizing film, such as 45 °, and the alignment angle of the second base layer is set to be greater than the alignment angle of the second polarizing film, preferably It is greater than 45° and less than or equal to 50°, preferably set to 47°, which can also achieve the technical effect of improving the inversion characteristics of the dark-state photoelectric characteristic curve. the

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (6)

1. A liquid crystal panel, comprising a color filter substrate and an array substrate arranged in a box, wherein the color filter substrate is attached with a first polarizing plate comprising a first base layer, a first compensation film and a first polarizing film, A second polarizer comprising a second polarizing film, a second compensation film and a second base layer is attached to the array substrate, characterized in that: The alignment angle of the first base layer is greater than the alignment angle of the second base layer; The light transmission axes on the first polarizing film and the second polarizing film are perpendicular to each other; The alignment angle of the first base layer is larger than the alignment angle of the first polarizing film, and the alignment angle of the second base layer is equal to the alignment angle of the second polarizing film. 2. The liquid crystal panel according to claim 1, wherein the alignment angle of the first base layer is greater than 45° and less than or equal to 50°, and the alignment angle of the second base layer is 45°. 3. The liquid crystal panel according to claim 2, wherein the alignment angle of the first base layer is 47°. 4. A liquid crystal panel, comprising a color filter substrate and an array substrate arranged in a box, wherein the color filter substrate is attached with a first polarizing plate comprising a first base layer, a first compensation film and a first polarizing film, A second polarizer comprising a second polarizing film, a second compensation film and a second base layer is attached to the array substrate, characterized in that: The alignment angle of the first base layer is smaller than the alignment angle of the second base layer; The light transmission axes on the first polarizing film and the second polarizing film are perpendicular to each other; The alignment angle of the first base layer is equal to the alignment angle of the first polarizing film, and the alignment angle of the second base layer is larger than the alignment angle of the second polarizing film. 5. The liquid crystal panel according to claim 4, wherein the alignment angle of the first base layer is 45°, and the alignment angle of the second base layer is greater than 45° and less than or equal to 50°. 6. The liquid crystal panel according to claim 5, wherein the alignment angle of the second base layer is 47°.

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