TW201337408A - Liquid crystal displayer - Google Patents

Abstract

A liquid crystal displayer is provided. The liquid crystal displayer includes a first polarizer, a second polarizer, a liquid crystal layer, a first alignment film, a second film, and a diffraction plate. The first polarizer has a first absorption axis. The second polarizer is disposed on the first polarizer and has a second absorption axis. An angle between the first absorption axis and the second absorption axis is substantially equal to 90 degrees. The liquid crystal layer is disposed between the first polarizer and the second polarizer. The first alignment film is disposed between the liquid crystal layer and the first polarizer, and has a first alignment direction. The second alignment film is disposed between the liquid crystal layer and the second polarizer, and has a second alignment direction. The diffraction plate is disposed on the first alignment film, and has at least one diffraction direction. An angle between the first absorption axis and the first alignment direction is in the range of -45 degrees to -25 degrees, 25 degrees to 55 degrees, and 125 degrees to 135 degrees.

Description

LCD Monitor

The present disclosure relates to a liquid crystal display, and more particularly to a twisted nematic liquid crystal display having a liquid crystal display with better sub-view image quality.

With the rapid advancement of thin film transistor manufacturing technology, liquid crystal display devices are widely used in televisions, personal digital assistants, notebook computers, digital cameras, and video recordings because of their advantages of thinness, power saving, and no radiation. In various electronic products such as video cameras and mobile phones. However, since the liquid crystal display device is a non-self-luminous display, it is generally required to use a backlight to generate light and penetrate the optical film layer such as a diffusion film or a brightness enhancement film to form a uniform planar light incident. The liquid crystal display panel is used to present an image. Twisted Nematic (TN) or Super Twisted Nematic (STN) is one of the commonly used liquid crystal displays. Although such a liquid crystal display has a price advantage, the image quality of the lower viewing angle is often inferior to that of the left and right viewing angles. This is because the user mostly views the liquid crystal display with a positive viewing angle and a left and right viewing angle. Therefore, the designer of the liquid crystal display often designs the portion with poor optical characteristics of the liquid crystal display as the lower viewing angle of the liquid crystal display.

Please refer to Figure 1, which shows the twisted nematic (Twisted) Nematic; TN) Schematic diagram of the liquid crystal layer 12 of the liquid crystal display 10. The TN liquid crystal display 10 includes a liquid crystal layer 12, an upper alignment plate 14 and a lower alignment plate 16, wherein the lower alignment plate 16 is closer to the backlight. The liquid crystal layer 12 includes a top liquid crystal molecule 12a and an underlying liquid crystal molecule 12b. The upper alignment plate 14 and the lower alignment plate 16 are used to align liquid crystal molecules in the liquid crystal layer 12 to configure the top liquid crystal molecules 12a and the underlying liquid crystal molecules 12b into a twisted structure and have a pretilt angle thereof, wherein The liquid crystal molecules of the dip angle away from one end of the alignment plate may be referred to as a head end, and the other end may be referred to as a tail end. For example, the upper alignment plate 14 aligns the upper liquid crystal molecules 12a to have a pretilt angle. For another example, the lower alignment plate 16 aligns the underlying liquid crystal molecules 12b to have a pretilt angle. The alignment directions of the alignment plates 14 and 16 are not parallel to each other, so that the liquid crystal molecules located therebetween are continuously twisted to form a torsional liquid crystal structure, wherein the twist angle of the liquid crystal can be defined as continuous from the head end of the underlying liquid crystal molecules via the interlayer liquid crystal. The ground is twisted to the angle of the end of the upper liquid crystal molecule.

For a general twisted-type (TN) liquid crystal display, the tip end of the underlying liquid crystal molecule 12b is continuously twisted to the trailing end of the upper liquid crystal molecule via the intermediate layer liquid crystal, and the optical characteristics of the viewing angle range are not good. The use is often defined as the observer's lower viewing direction.

In the case of a TN liquid crystal display without any viewing angle compensation mechanism, generally, the image observed from the lower viewing angle of the liquid crystal display has a problem that the contrast is severely lowered, and the degree of grayscale inversion and color shift are severely affected. Here, in order to facilitate the description of the image quality problem of the view image under the display, the direction in which the light is emitted is expressed by the zenith angle θ and the azimuth angle 球 in the spherical coordinate system. For example, the light exiting the surface of the display is X-Y flat. The direction of the positive Z-axis extends from the light exit surface toward the viewer (the normal direction of the light exit surface), so the viewing angle of the display can be expressed as (θ, ψ). Taking the right view and the left view as an example, they can be represented by (α, 0) and (β, 180), respectively, where 0 degrees ≦ α, β ≦ 90 degrees. Similarly, the upper and lower viewing angles can be expressed as (γ, 90) and (δ, 270), respectively, where 0 degrees ≦ γ, δ ≦ 90 degrees.

Please also refer to the figures 1a, 1b, and 1c, which are diagrams showing the gray scale distribution of the brightness of the conventional liquid crystal display at different angles θ, ,, wherein the absorption axis of the polarizing plate above the liquid crystal display is - 45 degrees, and the absorption axis of the lower polarizer is 45 degrees, the vertical axis is the normalized brightness, the horizontal axis is the gray level, and the ψ is 225 degrees, 275 degrees and 315 degrees, respectively, and θ is 0 degrees, 30 degrees, 45 degrees. With 60 degrees. Please refer to Figure 1a first. When θ is 60 degrees, when the gray level is increased to about 50, the brightness does not increase, but decreases. This is called gray scale inversion. The 1st and 1c pictures also have gray-scale reversal, which seriously affects image quality.

In order to solve the problem of the viewing angle of the TN liquid crystal display, a compensation film can be added to improve the quality of the side viewing angle image. For example, the Fuji wide view film (WV film) developed by Fujifilm is the current one. A commonly used TN compensation film. However, most of today's wide viewing angle display compensation film technology is mostly used to improve contrast and reduce color shift, and the improvement of severe grayscale inversion of TN liquid crystal display is still insufficient. As shown in Fig. 1d, when ψ is 270 degrees and θ is 60 degrees, the display still has severe grayscale inversion.

Therefore, there is a need for a new liquid crystal display that provides the user with excellent low viewing angle image quality.

One aspect of the present invention is to provide a liquid crystal display that is optically diffractive to improve the quality of viewing angle of the liquid crystal display.

According to an embodiment of the invention, the liquid crystal display comprises a first polarizing plate, a second polarizing plate, a liquid crystal layer, a first alignment film, a second alignment film, and a diffraction sheet. The first polarizing plate has a first absorption axis. The second polarizing plate is disposed opposite to the first polarizing plate and has a second absorption axis, wherein an angle between the second absorption axis and the first absorption axis is substantially 90 degrees. The liquid crystal layer is disposed between the first polarizing plate and the second polarizing plate. The first alignment film is disposed between the liquid crystal layer and the first polarizer and has a first liquid crystal alignment direction. The second alignment film is disposed between the liquid crystal layer and the second polarizing plate and has a second liquid crystal alignment direction. The diffractive film is disposed on the first alignment film and has at least one diffraction direction. When the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees, the angle between the first absorption axis and the first liquid crystal alignment direction is between -45 degrees and -25 degrees, 25 degrees to 55 degrees, and Within the range of 125 degrees to 135 degrees. When the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially -90 degrees, the angle between the first absorption axis and the first liquid crystal alignment direction is 45 degrees to 25 degrees, -25 degrees to -55. Degrees are in the range of -125 degrees to -135 degrees.

According to another embodiment of the present invention, the liquid crystal display comprises a first polarizing plate, a second polarizing plate, a liquid crystal layer, a first alignment film, a second alignment film, a first wide viewing angle compensation film, and a diffraction sheet. The first polarizing plate has a first absorption axis. The second polarizing plate is disposed on the first polarizing plate and has a second absorption axis, wherein an angle between the second absorption axis and the first absorption axis is substantially 90 degrees. The liquid crystal layer system is set in the first A polarizing plate and a second polarizing plate. The first alignment film is disposed between the liquid crystal layer and the first polarizer and has a first liquid crystal alignment direction. The second alignment film is disposed between the liquid crystal layer and the second polarizing plate and has a second liquid crystal alignment direction. The first wide viewing angle compensation film is disposed on the first polarizing plate and opposite to the other side of the first alignment film, wherein the first wide viewing angle compensation film has a first optical axis. The diffractive film is disposed on the first alignment film and has at least one diffraction direction. When the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees, the angle between the first optical axis and the first liquid crystal alignment direction is in the range of -22.5 degrees to 112.5 degrees. When the angle between the second liquid crystal alignment direction of the first liquid crystal alignment direction is substantially -90 degrees, the angle between the first optical axis and the first liquid crystal alignment direction is in the range of -22.5 degrees to 112.5 degrees.

According to still another embodiment of the present invention, the liquid crystal display comprises a first polarizing plate, a second polarizing plate, a liquid crystal layer, a first alignment film, a second alignment film, a first wide viewing angle compensation film, and a diffraction sheet. The first polarizing plate has a first absorption axis. The second polarizing plate is disposed on the first polarizing plate and has a second absorption axis, wherein an angle between the second absorption axis and the first absorption axis is substantially 90 degrees. The liquid crystal layer is disposed between the first polarizing plate and the second polarizing plate. The first alignment film is disposed between the liquid crystal layer and the first polarizer and has a first liquid crystal alignment direction. The second alignment film is disposed between the liquid crystal layer and the second polarizing plate and has a second liquid crystal alignment direction. The first wide viewing angle compensation film is disposed between the first polarizing plate and the liquid crystal layer and opposite to the other side of the first alignment film, wherein the first wide viewing angle compensation film has a first optical axis. The diffractive sheet is disposed on the first alignment film and has at least one diffraction direction. When the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees, the second optical axis and the first liquid crystal The angle of the alignment direction is in the range of 157.5 degrees to 292.5 degrees. When the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially -90 degrees, the angle between the second optical axis and the first liquid crystal alignment direction is in the range of 67.5 degrees to 202.5 degrees.

It can be seen from the above description that the liquid crystal display of the embodiment of the present invention improves the quality of the viewing angle image under the liquid crystal display by the arrangement relationship between the diffraction sheet and the polarizing plate.

10‧‧‧LCD display

12‧‧‧Liquid layer

12a‧‧‧Top liquid crystal molecules

12b‧‧‧ bottom liquid crystal molecules

14‧‧‧Upward alignment board

16‧‧‧Under the alignment board

100‧‧‧ display device

110‧‧‧ display

120‧‧‧Diamonds

300‧‧‧LCD display

310‧‧‧Backlight module

320‧‧‧low polarizer

321‧‧‧Absorption axis

330‧‧‧ under the alignment film

331‧‧‧Liquid alignment direction

340‧‧‧Liquid layer

350‧‧‧Upward alignment film

351‧‧‧Liquid alignment direction

360‧‧‧Upper polarizer

361‧‧‧Absorption axis

362, 364‧‧‧ absorption axis direction

366, 368‧‧‧ optical axis direction

370‧‧‧Diamonds

372A, 372B, 372C, 372D, 372E, 372F, 372G, 372H‧‧‧ diffraction area

410‧‧‧Upper viewing angle compensation film

420‧‧‧ Wide viewing angle compensation film

400‧‧‧LCD display

600‧‧‧LCD display

411, 421‧‧‧ optical axis

Min‧‧‧regional penetration rate minimum

500‧‧‧LCD display

I ₁ ‧ ‧ observation image

Max‧‧‧ regional penetration rate maximum

I ₃ ‧‧‧Viewing images

I ₂ ‧ ‧ observation images

D1, D2, N, T‧‧ cycle

I ₄ ‧ ‧ observation images

K1, K2, K3, K4, K5, K6, K7‧‧‧ diameter

M, M1, M2, M3, M4, M5, M6, M7, M8‧‧‧ distance

W‧‧‧Width

FIG. 1 is a schematic view showing the structure of a liquid crystal layer of a twisted-type (TN) liquid crystal display.

The 1a-1c diagram shows the luminance gray scale distribution obtained by measuring the azimuth and zenith angles of the conventional liquid crystal display at different angles.

Figure 1d is a diagram showing the gray scale distribution of the brightness measured by the zenith angle of the conventional liquid crystal display at different angles.

2 is a schematic structural view of a display device according to an embodiment of the invention.

Figure 2a is a schematic diagram showing the user viewing the display from a side perspective.

Figure 2b is a schematic view showing the user viewing the display device from a side view.

3 is a schematic structural view of a liquid crystal display according to an embodiment of the present invention.

Figure 3a is a schematic view showing the relationship between the absorption axis of the liquid crystal display and the alignment direction of the liquid crystal in the positive Z-axis direction according to an embodiment of the present invention.

3b-3d are diagrams showing a luminance gray scale distribution obtained by measuring azimuth and zenith angles of liquid crystal displays at different angles according to an embodiment of the present invention.

FIG. 3e is a schematic diagram showing the relationship between the viewing angle transmittance and the applied voltage of the liquid crystal display according to an embodiment of the invention.

FIG. 3f is a schematic diagram showing the relationship between the gray-scale inversion index of the viewing angle of the liquid crystal display and the absorption axis angle of the upper polarizing plate according to an embodiment of the invention.

The 3g graph is a schematic diagram showing the relationship between the dark state transmittance and the absorption axis angle of the upper polarizer.

Figure 3h is a diagram showing the liquid crystal alignment direction of the alignment film and the lower alignment film on the liquid crystal display according to the embodiment of the present invention.

4 is a schematic structural view of a liquid crystal display according to an embodiment of the present invention.

4A is a schematic diagram showing the relationship between the gray-scale inversion index obtained by the liquid crystal display of the embodiment of the present invention and the angle of the optical axis 411 in the case of a plurality of different lower optical axis angles (angles of the optical axis 421).

4b is a schematic diagram showing the relationship between the dark state transmittance of the liquid crystal display of the embodiment of the present invention and the angle of the optical axis 411 in the case of a plurality of different lower optical axis angles (angles of the optical axis 421). .

Figure 4c is a gamma curve showing the lower viewing angle of the liquid crystal display according to an embodiment of the present invention.

Figure 4d is a gamma curve of the lower viewing angle of the liquid crystal display after the absorption axis position is interchanged according to an embodiment of the present invention.

Figure 4e is a diagram showing the configuration of a liquid crystal display in an embodiment.

Figure 4f shows a diffraction sheet of an embodiment.

4g is a diagram showing the relationship between the normalized brightness of the lower viewing angle and the diffraction direction of the diffraction sheet of the liquid crystal display in the 224 gray scale in an embodiment.

Figure 4h shows a diffraction sheet of an embodiment.

4i is a diagram showing the relationship between the normalized luminance of the lower viewing angle and the diffraction direction of the diffraction fin of the liquid crystal display in the 224 gray scale in an embodiment.

Figure 4j shows the relationship between the normalized central contrast of the liquid crystal display at a positive viewing angle and the diffraction direction of the diffractive sheet.

Figure 4k shows a diffraction sheet of an embodiment.

Figure 4l is a diagram showing the relationship between the normalized brightness of the viewing angle of the liquid crystal display at 224 gray level and the diffraction direction of the diffraction sheet in an embodiment.

Figure 4m shows a diffraction sheet of an embodiment.

FIG. 4n is a diagram showing the relationship between the normalized brightness of the lower viewing angle and the diffraction direction of the diffraction sheet of the liquid crystal display in the 224 gray scale in an embodiment.

The 4th and 4th drawings respectively show the dark state improvement ratio of the left and right viewing angles of the liquid crystal display according to the embodiment of the present invention.

FIG. 5 is a schematic structural view of a liquid crystal display according to an embodiment of the invention.

5a-5c are diagrams showing luminance gray scale distributions of azimuth angles and zenith angles of liquid crystal displays at different angles according to an embodiment of the present invention.

FIG. 6 is a schematic structural view of a liquid crystal display according to an embodiment of the invention.

6a-6c are diagrams showing a luminance gray scale distribution obtained by measuring azimuth and zenith angles of liquid crystal displays at different angles according to an embodiment of the present invention.

First embodiment

Please refer to FIG. 2 , which is a schematic structural diagram of a display device 100 according to an embodiment of the invention. The display device 100 includes a display 110 and a diffractive sheet 120 (diffractive optical element). The display 110 is a TN or STN liquid crystal display, and the diffractive sheet 120 can be a diaphragm provided with a grating (for example, a phase grating) placed on the light emitting surface of the display 110 for diffracting the light emitted by the display 110.

In the present embodiment, the direction in which the light is emitted is expressed by the zenith angle θ and the azimuth angle 中 in the spherical coordinate system. For example, the surface of the diffraction sheet 120 is an X-Y plane, and the direction of the positive Z-axis extends from the diffraction sheet 120 toward the observer, so that the viewing angle of the display device 100 can be expressed as (θ, ψ). Taking the right view and the left view as an example, they can be represented by (α, 0) and (β, 180), respectively, where 0 degrees ≦ α, β ≦ 90 degrees. Similarly, the upper and lower viewing angles can be expressed as (γ, 90) and (δ, 270), respectively, where 0 degrees ≦ γ, δ ≦ 90 degrees.

In addition, the diffraction direction (or the diffraction angle) of the present embodiment is defined by the direction of the peak (valley) connection of the grating structure of the diffraction fin 120.

Please refer to FIG. 2a and FIG. 2b simultaneously. FIG. 2a is a schematic diagram showing the user viewing the display 110 from a side view, and FIG. 2b is a schematic diagram showing the user viewing the display device 100 from a side view. In the present embodiment, the display 110 is a liquid crystal display. Assuming that the front view of the display 110 is 0 degrees and the maximum range of the oblique view is 90 degrees, the range of viewing angles in which the image quality of the display 110 changes with respect to the positive viewing angle is zenith angle θ between 90 and 10 degrees. This means that when the user observes the display 110 at a side angle of more than 10 degrees, the image of the display 110 may be found to have problems such as contrast reduction, grayscale inversion, gamma curve variation or color shift. Of course, the comparison benchmark is not necessarily based on the positive view image, for example, the angle of the image optimization in the original design can be used as a benchmark.

In the following description, only the image quality of the 30-degree left viewing angle is improved. For example, the observed image obtained by the user in a certain range (for example, the car in the figure) observed by the positive angle of view (0 degree angle of view) is I ₁ (also referred to as a front view image I ₁ ), and the left angle of view is 30 degrees. Observing the observed image obtained by the specific range is I ₂ (also referred to as side view image I ₂ ), and the phase retardation caused by the light source passing through the liquid crystal layer is different, so that the front view image I ₁ and the side view image I _{In 2} , the hue, saturation, or brightness of the pixels located at the same position are significantly different, resulting in deterioration of the viewing angle uniformity of the display 110. Therefore, in the present embodiment, the diffracting sheet 120 is used to diffract the light constituting the positive-view image I ₁ to the left viewing angle of 30 degrees to compensate the side-view image I ₂ by using the partial components of the positive-view image I ₁ .

As shown in FIG. 2b, when the user observes the display device 100 at a left angle of view of 30 degrees, the observed image I4 (also referred to as a side view image I4) observed by the user is equal to the side view image I ₂ is not wrapped. The component of the shot is added to the component of the right-view image I ₁ at a 30-degree left angle of view, i.e., I4 = JI ₂ + kI ₁ , where J, k is a positive number less than one. At the same time, since the light constituting the front view image I ₁ is diffracted to the side view, the front view image I ₁ is converted into the positive view image I ₃ having a small brightness.

For the side view image I ₄ , if the component of the side view image I ₁ is sufficiently strong in the side view angle (ie, kI ₁ ), the contribution of the image JI ₂ that is not diffracted by the side view angle to the side view image I ₄ is relatively When it is small, the image difference between the front view image I ₃ and the side view image I ₄ can be reduced, so that the image quality of the side view image I ₄ is improved. It should be noted that the aforementioned image difference refers to the difference in hue, chroma and brightness of two pixels at the same position in the images I ₃ and I ₄ , and the difference in image size means that the viewing angle uniformity of the display device is improved. .

It is worth mentioning that the positive viewing angle of this embodiment is not limited to only the viewing angle of 0 degrees. Since the angle of view is around 0 degrees, the user can observe the good A good image, so the aforementioned positive viewing angle can also be defined as a viewing angle range of 0 ± 10 degrees, so the compensated viewing angle is not only a 30 degree side viewing angle.

In addition, if the diffraction sheet 120 is appropriately rotated such that the diffraction direction of the diffraction sheet 120 is between 225 degrees and 315 degrees, the diffraction pattern 120 can be used to compensate the lower angle image of the display 110.

Second embodiment

Please refer to FIG. 3 , which is a schematic structural diagram of a liquid crystal display 300 according to an embodiment of the invention. The liquid crystal display 300 includes a backlight module 310, a lower polarizing plate 320, a lower alignment film 330, a liquid crystal layer 340, an upper alignment film 350, an upper polarizing plate 360, and a diffraction sheet 370, wherein the function of the diffraction sheet 370 is similar to diffraction A sheet 120 is used to compensate for the image quality of certain viewing angles, such as the lower viewing angle. The foregoing upper polarizing plate 360 and lower polarizing plate 320 include a polarizing layer such as polyvinyl alcohol (PVA), or include a polarizing layer and such as Triacetyl Cellulose (TAC). The substrate of the layer is not limited to this. The lower polarizing plate 320 is disposed on the backlight module 310 and has an absorption axis 321 . The lower alignment film 330 is disposed on the lower polarizing plate 320 and has a liquid crystal alignment direction 331. The liquid crystal layer 340 is disposed on the lower alignment film 330 and contains liquid crystal molecules (not shown). The upper alignment film 350 is provided on the liquid crystal layer 340 and has a liquid crystal alignment direction 351. The upper alignment film 350 and the lower alignment film 330 sandwich the liquid crystal layer 340 therein to twist the liquid crystal molecules in the liquid crystal layer 340 according to the liquid crystal alignment directions 331 and 351. In this embodiment, the liquid crystal display 300 is a 90 degree twisted TN liquid crystal display, but the present invention The embodiments are not limited thereto. The upper polarizing plate 360 is disposed on the upper alignment film 350 and has an absorption axis 361. The absorption axis 361 is substantially perpendicular to the absorption axis 321 of the lower polarizer 320. The diffraction sheet 370 is disposed on the upper alignment film 350 and has at least one diffraction direction.

It should be noted that although the third drawing shows that the diffraction sheet 370 is disposed above the upper polarizing plate 360, the embodiment of the present invention is not limited thereto. In other embodiments of the present invention, the diffraction sheet 370 may also be disposed between the upper polarizing plate 360 and the upper alignment film 350.

Please refer to FIG. 3 a, which is a schematic view showing the relationship between the absorption axis 321 of the liquid crystal display 300, the absorption axis 361 and the liquid crystal alignment directions 331 and 351 along the positive Z-axis direction, wherein the positive X-axis direction is set as the liquid crystal display. The right viewing angle of 300, the negative X-axis direction is set to the left viewing angle of the liquid crystal display 300, the positive Y-axis direction is set to the upper viewing angle of the liquid crystal display 300, and the negative Y-axis direction is set to the lower viewing angle of the liquid crystal display 300.

As shown in Fig. 3a, in the present embodiment, the absorption axis 321 of the lower polarizing plate 320 is parallel to the Y axis (for example, the absorption axis direction in the positive direction of the Y axis is 90 degrees, and the negative direction is 270 degrees), and the lower alignment The liquid crystal alignment direction 331 of the film 330 is 45 degrees, and the absorption axis 361 of the upper polarizing plate 360 is parallel to the X axis (for example, the absorption axis direction is 0 degree in the positive X-axis direction and the negative direction is 180 degrees), and the upper alignment film 350 is provided. The liquid crystal alignment direction 351 is 45 degrees. Thus, the angle between the absorption axis 321 and the liquid crystal alignment direction 331 is substantially equal to -45 degrees, and the angle between the absorption axis 361 and the liquid crystal alignment direction 351 is substantially equal to -45 degrees (based on the liquid crystal alignment direction 351). In addition, in order to make up To compensate the image quality of the viewing angle, the diffraction direction of the diffraction sheet 370 is in the range of 225 degrees to 315 degrees, that is, the angle between the diffraction direction of the diffraction sheet 370 and the liquid crystal alignment direction 351 is between 180 degrees and 270 degrees. between.

Please refer to the figures 3b, 3c, and 3d, which is that the absorption axis of the upper polarizer is 0 degrees, and the absorption axis of the lower polarizer is 90 degrees, and when the diffraction direction of the diffraction sheet 370 is 270 degrees, at different angles θ And ψ measured the brightness gray scale distribution map, wherein the vertical axis is the normalized brightness, the horizontal axis is the gray level, and the ψ is 225 degrees, 270 degrees and 315 degrees, respectively, and θ is 0 degrees, 30 degrees, 45 degrees With 60 degrees. It can be seen from the figure that in the above measurement angles, as the gray scale increases, the brightness also increases, and there is no known gray scale increase but the brightness is lowered to cause gray scale inversion.

The following description is for explaining the arrangement relationship between the absorption axis of the polarizing plate and the display panel. For the sake of simplifying the experiment, the following simulation includes only the lower polarizing plate 320, the lower alignment film 330, the liquid crystal layer 340, the upper alignment film 350, and the upper polarizing. The plate 360 or the like is not added to the diffraction sheet 370. However, according to the measurement results of the 3b, 3c, and 3d graphs, the addition of the diffraction sheet 370 can make the optical of the side viewing angle (θ≠0) closer to the optical of the positive viewing angle (θ=0), and the display quality is improved. More improved.

Please refer to FIG. 3e and FIG. 3f simultaneously. FIG. 3e is a schematic diagram showing the relationship between the transmittance of the liquid crystal display 300 ((θ, ψ)=(45, 270)) and the applied voltage, and FIG. 3f is a schematic diagram A schematic diagram of the relationship between the gray-scale inversion index of the liquid crystal display 300 ((θ, ψ) = (45, 270)) and the absorption axis 361 of the upper polarizer 360, wherein the applied voltage is applied to the electrodes on both sides of the liquid crystal and used Controls the voltage at which the liquid crystal turns. In the embodiment of the present invention, the image quality of the lower viewing angle is reversed by gray scale The indicators are defined, and the gray-scale inversion index is defined by a conventional TN display (unwidened viewing angle compensation film) whose transmittance is schematically related to the applied voltage. For example, the absorption axes of the upper and lower polarizers are at -45 degrees and +45 degrees, respectively, and the relationship between the transmittance of the lower viewing angle ((θ, ψ) = (45, 270)) and the applied voltage is as shown in Fig. 3b. . The gray-scale inversion index is defined as the difference between the maximum regional penetration rate Max and the minimum regional penetration rate Min, the maximum regional penetration rate Max is about 0.079), and the minimum regional penetration rate Min is the minimum wear. The penetration rate is approximately 0.009, as shown in Figure 3e.

For the gray scale inversion index, it can be seen from Fig. 3f that when the angle of the absorption axis 361 of the upper polarizing plate 360 is 0 degrees, 90 degrees, and 180 degrees, the value of the gray scale inversion index is small. Since the absorption axis of the polarizing plate has a symmetrical relationship, when the angle of the absorption axis 361 of the upper polarizing plate 360 is 270 degrees and 360 degrees, the gray scale inversion index also has a small value. In addition, since the human eye does not feel the slight gray-scale inversion effect, if the gray-scale inversion index is less than about 0.07 (the difference between the regional penetration maximum value and the regional transmittance minimum value) is 25%. As a standard, it can be seen from Fig. 3f that when the angle of the absorption axis 361 is in the range of 0 to 20 degrees, 70 to 100 degrees, and 170 to 180 degrees (since the absorption axis of the polarizing plate is symmetrical, the angle here is 180 degrees). That is, 0 degrees), that is, when the angle between the absorption axis 361 and the liquid crystal alignment direction 351 is in the range of -45 degrees to -25 degrees, 25 degrees to 55 degrees, and 125 degrees to 135 degrees, the user has a lower angle of view on the display 300. The perceived gray-scale reversal is greatly reduced, and the phenomenon of gray-scale reversal is hardly noticeable.

Please refer to the 3g figure, which is a schematic diagram showing the relationship between the dark state transmittance of the lower viewing angle ((θ, ψ) = (45, 270)) and the absorption axis angle of the upper polarizer. In this embodiment The arrangement relationship of the diffractive sheet 370 and the polarizing plates 360, 320 can also contribute to the dark state performance of the liquid crystal display 300. As can be seen from the 3d figure, when the angle of the absorption axis 361 of the upper polarizing plate 360 is 0 degrees, 90 degrees, and 180 degrees, not only the lower viewing angle ((θ, ψ) = (45, 270)) has a smaller dark state transmittance. In general, the polarizing plate also has an optimum cutting utilization rate, so that the manufacturing cost of the polarizing plate can also be reduced. Since the absorption axis of the polarizing plate has a symmetrical relationship, when the absorption axis 361 of the upper polarizing plate 360 has an angle of 270 degrees and 360 degrees, the dark state transmittance also has a small value. In addition, since the human eye has a certain degree of light tolerance to the dark state, the embodiment of the present invention uses the lower angle of view ((θ, ψ) = (45, 270)) of the TN liquid crystal display of the conventional non-viewing compensation film. The penetration rate is used as a standard (the average dark state transmittance is the average value of the dark state transmittance of the conventional TN display at the operating voltage of 3.5 to 5 V, which is calculated to be approximately 0.05), and when the liquid crystal of this embodiment is When the angle of the absorption axis 361 of the display 300 is in the range of 0 to 20 degrees, 70 to 100 degrees, and 170 to 180 degrees, the dark state transmittance of the liquid crystal display 300 in the lower viewing angle is up to standard.

As can be seen from the above description, the display 300 of the present embodiment appropriately arranges the diffraction direction of the diffraction sheet 370 and the absorption axis direction of the polarizing plates 360 and 320 to improve the quality of the viewing angle image of the liquid crystal display 300, and the liquid crystal display 300 The dark state light leakage of the lower view image can also be improved at the same time.

In addition, in the embodiment of the present invention, the position of the absorption axis of the polarizing plate under the liquid crystal display 300 and the absorption axis of the upper polarizing plate can be arbitrarily interchanged, and the liquid crystal alignment direction of the upper alignment film and the liquid crystal alignment direction of the lower alignment film can be at other angles. To configure.

In addition, as shown in FIG. 3h, in other embodiments of the present invention, the liquid crystal alignment direction 331 and the liquid crystal alignment direction 351 of the liquid crystal display may be 135 degrees and 225 degrees, respectively, that is, the liquid crystal alignment direction 331 and the liquid crystal alignment direction 351. The angle is -90 degrees, and the angle between the at least one diffraction direction of the diffractive sheet and the liquid crystal alignment direction 331 is between 90 degrees and 180 degrees. In this case, when the angle between the absorption axis 361 and the liquid crystal alignment direction 351 is in the range of 45 degrees to 25 degrees, -25 degrees to -55 degrees, and -125 degrees to -135 degrees, the user has a lower angle of view on the display 300. The perceived gray-scale reversal is greatly reduced, and the phenomenon of gray-scale reversal is hardly noticeable.

Third embodiment

Please refer to FIG. 4 , which is a schematic structural diagram of a liquid crystal display 400 according to an embodiment of the invention. The liquid crystal display 400 is similar to the liquid crystal display 300, but the liquid crystal display 400 further includes two wide viewing angle compensation films 410 and 420. The upper viewing angle compensation film 410 is disposed between the upper polarizing plate 360 and the liquid crystal layer 340 and has an optical axis 411, and the lower wide viewing angle compensation film 420 is disposed between the liquid crystal layer 340 and the lower polarizing plate 320 and has an optical axis 421. . In the present embodiment, the wide viewing angle compensation films 410 and 420 are Fuji wide view film (WV film) developed by Fujifilm Co., Ltd., but the embodiment of the present invention is not limited thereto.

In the present embodiment, the angle of the optical axis 411 of the upper viewing angle compensation film 410 is in the range of 22.5 to 157.5 degrees, and the angle of the optical axis 421 of the lower wide viewing angle compensation film 420 is in the range of 202.5 to 337.5 degrees. That is, the angle between the optical axis 411 and the liquid crystal alignment direction 351 of the upper alignment film 350 is in the range of -22.5 to 112.5 degrees, and the light The angle between the shaft 421 and the liquid crystal alignment direction 351 of the upper alignment film 350 is in the range of 157.5 to 292.5 degrees.

Referring to FIG. 4a, the relationship between the gray-scale inversion index obtained by the liquid crystal display 400 and the angle of the optical axis 411 in the lower viewing angle is shown in FIG. 4a, where the light is at a different angle of the optical axis (the angle of the optical axis 421). The angle between the shaft 421 and the liquid crystal alignment direction 351 is 202.5 to 337.5 degrees. As shown in FIG. 4a, for the gray scale inversion index of the liquid crystal display 400, when the angle of the optical axis 421 of the wide viewing angle compensation film 420 is within 202.5 to 337.5, the optical axis 411 of the upper viewing angle compensation film 410 is The angle is in the range of 22.5~157.5 degrees, and the phenomenon that the observer reverses the gray level in the lower view of the display 400 is relatively slight (the grayscale inversion index is less than 0.037).

Please refer to FIG. 4b, which is a schematic diagram showing the relationship between the dark state transmittance of the liquid crystal display 400 and the angle of the optical axis 411 obtained from the lower viewing angle in the case of a plurality of different lower optical axis angles (angles of the optical axes 421). The angle between the optical axis 421 and the liquid crystal alignment direction 351 is 202.5 to 337.5 degrees. As shown in FIG. 4b, for the dark state transmittance of the liquid crystal display 400, when the angle of the optical axis 421 of the wide viewing angle compensation film 420 is within 202.5 to 337.5, the optical axis 411 of the upper viewing angle compensation film 410 is The angle of the liquid crystal display 400 is within the range of 22.5~157.5 degrees, and the dark state effect of the liquid crystal display 400 is up to standard (less than 0.05).

In addition, in the embodiment of the present invention, the positions of the absorption axis 321 of the lower polarizing plate 320 and the absorption axis 361 of the upper polarizing plate 360 can be arbitrarily interchanged. Referring to FIG. 4c and FIG. 4d, FIG. 4c is a gamma curve of a lower viewing angle of the liquid crystal display 400 according to an embodiment of the present invention, and FIG. 4d is a diagram showing an embodiment according to the present invention. The gamma curve of the lower viewing angle of the liquid crystal display after the absorption axis position is interchanged. It can be seen from Fig. 4c and Fig. 4d that the positional shift of the absorption axis of the polarizing plate does not degrade the quality of the lower viewing angle image.

The diffraction direction of the diffraction sheet 370 can be configured according to actual needs.

For example, FIG. 4e illustrates a configuration design of the liquid crystal display in an embodiment, wherein the absorption axis direction 362 of the upper polarizing plate 360 is 0 degrees (parallel and facing the positive direction of the X axis), and the absorption axis of the lower polarizing plate 320 The direction 364 is 90 degrees (parallel and positive direction toward the Y-axis), the optical axis direction 366 of the upper wide viewing angle compensation film 410 is 90 degrees, and the optical axis direction 368 of the lower wide viewing angle compensation film 420 is 270 degrees (parallel and toward Y) The negative direction of the axis).

Figure 4f depicts an embodiment of a diffractive sheet 370 having a plurality of diffractive regions 372A. The period T of the diffraction region 372A is 124 μm, and the width W is 116 μm to 118 μm. The distance M between the diffraction regions 372A is 6 μm to 8 μm. The period N of the grating of the diffraction region 372A is 1 μm.

4g is a diagram showing the relationship between the normalized brightness of the lower viewing angle and the diffraction direction of the diffraction sheet 370 of the liquid crystal display in the 224 gray scale in an embodiment. The liquid crystal display uses the configuration shown in Fig. 4e and the diffraction sheet 370 shown in Fig. 4f. The normalized luminance is obtained by dividing the luminance measured in each diffraction direction by the maximum luminance. According to the curve of Fig. 4g, when the diffraction direction of the diffraction piece 370 is arranged at 225 to 315 degrees, the normalized brightness is 80% or more. More preferably, when the diffraction direction of the diffraction sheet 370 is arranged at 240 to 300 degrees, the normalized luminance is 90% or more.

FIG. 4h illustrates a diffraction sheet 370 of an embodiment having a plurality of windings The shot areas 372B, 372C. The period D1 of the grating of the diffraction region 372B is 1 μm. The period D2 of the grating of the diffraction region 372C is 1 μm. The diffraction direction of the grating of the diffraction region 372B is different from the diffraction direction of the grating of the diffraction region 372C. In one embodiment, the diffraction directions of the diffractive region 372B and the diffractive region 372C are perpendicular to each other. The diffraction area 372B and the diffraction area 372C have a circular outline, and the diameters K1 and K2 are 28 μm to 29 μm.

4i is a diagram showing the relationship between the normalized brightness of the lower viewing angle and the diffraction direction of the diffraction sheet 370 of the liquid crystal display in the 224 gray scale in an embodiment. The liquid crystal display uses the configuration shown in Fig. 4e and the diffraction sheet 370 shown in Fig. 4h. The diffraction direction of the diffraction piece 370 is based on the diffraction direction of the grating of the diffraction area 372C. According to the curve of Fig. 4i, regardless of the diffraction direction of the diffraction piece 370, the brightness of the lower viewing angle can be more than 80%. Figure 4j shows the relationship between the normalized central contrast of the liquid crystal display at a positive viewing angle and the diffraction direction of the diffractive sheet 370. The diffraction direction of the diffraction piece 370 is based on the diffraction direction of the grating of the diffraction area 372C. The normalized central contrast is obtained by dividing the central contrast measured in each diffraction direction by the central contrast when the diffraction direction is 270 degrees. According to the result of Fig. 4j, when the diffraction direction of the diffraction sheet 370 is arranged at 240 to 285 degrees, the normalized central contrast is 80% or more. More preferably, when the diffraction direction of the diffraction sheet 370 is arranged at 245 to 280 degrees, the normalized central contrast is more than 90%.

Figure 4k illustrates a diffractive sheet 370 of an embodiment having a plurality of diffractive regions 372D, 372E, 372F. The diffraction direction of the diffraction area 372E and the diffraction area 372F is 45 degrees in the opposite direction to the diffraction direction of the diffraction area 372D. Winding around The distance M1 between the shot region 372D and the diffraction region 372E is 5 μm. The distance M2 between the diffraction area 372D and the diffraction area 372F is 5 μm. The distance M3 between the diffraction regions 372D is 5 μm. The distance M4 between the diffraction regions 372E is 5 μm. The distance M5 between the diffraction regions 372F is 5 μm. The diffraction area 372D, the diffraction area 372E, and the diffraction area 372F have a circular outline, and the diameters K3, K4, and K5 are 40 μm.

Figure 4l is a diagram showing the relationship between the normalized brightness of the lower viewing angle and the diffraction direction of the diffraction sheet 370 of the liquid crystal display in the 224 gray scale in an embodiment. The liquid crystal display uses the configuration shown in Fig. 4e and the diffraction sheet 370 shown in Fig. 4k. The diffraction direction of the diffraction sheet 370 is based on the diffraction direction of the grating of the diffraction region 372D. According to the result of Fig. 4k, when the diffraction direction of the diffraction sheet 370 is arranged at 225 to 315 degrees, the normalized luminance is 80% or more. More preferably, when the diffraction direction of the diffraction sheet 370 is 245 to 305 degrees, the normalized luminance is 90% or more.

Figure 4m illustrates a diffractive sheet 370 of an embodiment having a plurality of diffractive regions 372G, 372H. The distance M6 between the diffraction area 372G and the diffraction area 372H is 5 μm. The distance M7 between the diffraction regions 372G is 5 μm. The distance M8 between the diffraction regions 372H is 5 μm. The diffraction area 372G and the diffraction area 372H have a circular outline, and the diameters K6 and K7 are 40 μm.

FIG. 4n illustrates the relationship between the normalized brightness of the lower viewing angle and the diffraction direction of the diffraction sheet 370 of the liquid crystal display in the 224 gray scale in an embodiment. The liquid crystal display uses the configuration shown in Fig. 4e and the diffraction sheet 370 shown in Fig. 4m. The diffraction direction of the diffraction piece 370 is based on the average diffraction direction of the diffraction area 372G and the diffraction area 372H. In an embodiment, for example, when the diffraction area The diffraction direction of the field 372G is 285 degrees, and when the diffraction direction of the diffraction area 372H is 255 degrees, the average diffraction direction of the diffraction sheet 370 is 270 degrees. According to the result of the 4th figure, when the diffraction direction of the diffraction sheet 370 is arranged at 220 to 320 degrees, the normalized luminance is 80% or more. More preferably, when the diffraction direction of the diffraction sheet 370 is arranged at 235 to 295 degrees, the normalized luminance is 90% or more.

As apparent from the above description, the display 400 of the present embodiment appropriately aligns the diffraction directions of the diffraction sheets 370, the absorption axis directions of the polarizing plates 360 and 320, and the optical axis directions of the wide viewing angle compensation films 410 and 420 to improve the liquid crystal display. The quality of the viewing angle image under 400, and the dark state transmittance of the viewing angle image under the liquid crystal display 400 can also be improved at the same time.

Furthermore, the embodiment is not limited to the diffraction sheet 370 as described in the 4th, 4th, 4k, and 4m. The diffractive sheet 370 can be appropriately modulated according to the actual demand and the concept of the diffraction effect caused by the grating. For example, diffractive sheets 370 of different conditions may be used in whole or in part on one another. The diffraction regions of the diffractive sheet 370 having different diffraction directions or grating conditions may be completely or partially stacked on each other. The gratings in different directions can be stacked completely or partially on each other. The distance between the diffraction regions, the size of the diffraction region, and the shape of the diffraction region (for example, a strip shape, a square shape, a triangle shape, an arbitrary polygon shape) may be arbitrarily changed.

Please refer to FIG. 4o and FIG. 4p simultaneously, which respectively show the dark state improvement ratio of the left and right viewing angles of the liquid crystal display 400, wherein each curve in the 4th graph represents the right viewing angle dark state at different optical axis 421 angles. Improve the relationship between the ratio and the angle of the optical axis 411; the curves in the 4th figure represent the different optical axes 421 The left-view dark state of the angle improves the relationship between the ratio and the angle of the optical axis 411. As can be seen from FIG. 4o and FIG. 4p, the optical axis angles of the upper wide viewing angle compensation film 410 and the lower wide viewing angle compensation film 420 affect the dark state light leakage phenomenon of the left and right viewing angles of the display 400. The dark state improvement ratio is the average dark state transmittance of each optical axis angle of the third embodiment divided by the average dark state transmittance of the conventional polarized plate angles of the conventional TN display. For example, when the dark state improvement ratio is less than 100%, it can be seen from FIG. 4O that the optical axis 421 of the lower wide viewing angle compensation film 420 is in the range of 202.5 to 337.5 degrees, and the optical axis 411 of the upper wide viewing angle compensation film 410 is located at 22.5. In the range of ~90 degrees, the dark state light leakage phenomenon of the right viewing angle can be greatly improved. For example, when the dark state improvement ratio is less than 100%, it can be seen from FIG. 4p that the optical axis 421 of the lower wide viewing angle compensation film 420 is in the range of 202.5 to 337 degrees, and the optical axis 411 of the upper wide viewing angle compensation film 410 is located. In the range of 90 to 157.5 degrees, the dark state light leakage phenomenon of the left viewing angle can be greatly improved. Therefore, when the optical axis 411 of the upper wide viewing angle compensation film 410 is at 90 degrees, and the optical axis 421 of the lower wide viewing angle compensation film 420 is in the range of 202.5 to 337.5 degrees, better image quality can be obtained.

Therefore, for the liquid crystal display 400, when the dark state improvement ratio is less than 60%, the lower viewing angle and the left and right viewing angles can have more image quality. When the image quality of the lower viewing angle and the right viewing angle is to be good at the same time, the optical axis 411 of the upper viewing angle compensation film 410 should be at 90 degrees, and the optical axis 421 of the lower wide viewing angle compensation film 420 should be in the range of 202.5 to 292.5 degrees. If the image quality of the lower viewing angle and the left viewing angle is to be good at the same time, the optical axis 411 of the upper viewing angle compensation film 410 should be at 90 degrees, and the optical axis 421 of the lower wide viewing angle compensation film 420 should be in the range of 247.5 to 337.5 degrees. Inside; In order to have good image quality of the lower viewing angle and the left and right viewing angles, the optical axis 411 of the upper viewing angle compensation film 410 should be at 90 degrees, and the optical axis 421 of the lower wide viewing angle compensation film 420 should be in the range of 247.5 to 292.5 degrees. .

In summary, when the angle between the optical axis 411 and the liquid crystal alignment direction 351 is 45 degrees, and the angle between the optical axis 421 and the liquid crystal alignment direction 351 is in the range of 157.5 degrees to 247.5 degrees, the liquid crystal display 400 can have a good lower viewing angle at the same time. And the image quality of the right view. When the angle between the optical axis 411 and the liquid crystal alignment direction 351 is 45 degrees, and the angle between the optical axis 421 and the liquid crystal alignment direction 351 is in the range of 202.5 degrees to 292.5 degrees, the liquid crystal display 400 can have both a good viewing angle and a left viewing angle. Image quality. When the angle between the optical axis 411 and the liquid crystal alignment direction 351 is 45 degrees, and the angle between the optical axis 421 and the liquid crystal alignment direction 351 is in the range of 202.5 degrees to 247.5 degrees, the liquid crystal display 400 can have both a good viewing angle and a left and right viewing angle. Image quality.

In addition, it is to be noted that although the liquid crystal alignment direction 331 and the liquid crystal alignment direction 351 of the liquid crystal display of the present embodiment are respectively at 45 degrees and 315 degrees, embodiments of the present invention are not limited thereto. In other embodiments of the present invention, the liquid crystal alignment direction 331 and the liquid crystal alignment direction 351 of the liquid crystal display may be 135 degrees and 225 degrees, respectively, that is, the angle between the liquid crystal alignment direction 331 and the liquid crystal alignment direction 351 is -90 degrees. In this case, when the angle between the optical axis 411 and the liquid crystal alignment direction 351 is 45 degrees, that is, when the angle between the liquid crystal alignment direction 331 and the liquid crystal alignment direction 351 is substantially -90 degrees, and the optical axis 421 and the liquid crystal alignment direction When the angle of 351 is in the range of 67.5 degrees to 157.5 degrees, the liquid crystal display 400 can have good at the same time. Good image quality for the lower and right perspectives. When the angle between the optical axis 411 and the liquid crystal alignment direction 351 is -45 degrees, and the angle between the optical axis 421 and the liquid crystal alignment direction 351 is in the range of 112.5 degrees to 202.5 degrees, the liquid crystal display 400 can have both a good viewing angle and a left angle. Image quality of perspective. When the angle between the optical axis 411 and the liquid crystal alignment direction 351 is -45 degrees, and the angle between the optical axis 421 and the liquid crystal alignment direction 351 is in the range of 112.5 degrees to 157.5 degrees, the liquid crystal display 400 can have both a good viewing angle and left and right. Image quality of perspective.

Fourth embodiment

Please refer to FIG. 5, which is a schematic structural diagram of a liquid crystal display 500 according to an embodiment of the invention. The liquid crystal display 500 is similar to the liquid crystal display 400, but the liquid crystal display 500 has one wide viewing angle compensation film 420. Referring to FIGS. 5a, 5b, and 5c, the absorption axis of the upper polarizing plate is 0 degrees, the absorption axis of the lower polarizing plate is 90 degrees, and the angle of the optical axis 411 of the wide viewing angle compensation film 410 is 90 degrees, and the diffraction sheet 370 When the diffraction direction is 270 degrees, the obtained gray scale distribution map is measured at different angles θ, where the vertical axis is the normalized brightness, the horizontal axis is the gray level, and the ψ is 225 degrees, 270 degrees and 315, respectively. Degree, and θ is 0 degrees, 30 degrees, 45 degrees and 60 degrees. It can be seen from the figure that in the above measurement angles, as the gray scale increases, the brightness also increases, and there is no known gray scale increase but the brightness is lowered to cause gray scale inversion. Therefore, although the liquid crystal display 500 of the present embodiment has one lower viewing angle compensation film 420 than the liquid crystal display 400, the image quality of the liquid crystal display 500 in the lower viewing angle can still reach the standard (the gray scale inversion index is less than 0.037).

The following description is for explaining the arrangement relationship between the absorption axis of the polarizing plate and the display panel. For the sake of simplifying the experiment, the following simulation includes only the lower polarizing plate 320, the lower alignment film 330, the liquid crystal layer 340, the upper alignment film 350, and the upper polarizing. The plate 360 or the like is not added to the diffraction sheet 370. However, according to the measurement results of the figures 5a, 5b, and 5c, it can be seen that the addition of the diffraction sheet 370 can make the optical of the side angle of view (θ≠0) closer to the optical of the positive angle of view (θ=0), and the display quality is improved. More improved.

As can be seen from the above description, when the angle of the optical axis 411 of the wide viewing angle compensation film 410 is 90 degrees, the image quality of the liquid crystal display 500 at the lower viewing angle can still reach the standard. In addition, it has been confirmed by experiments that even if the angle of the optical axis 411 of the wide viewing angle compensation film 410 falls within the range of 22.5 to 157.5 degrees, the image quality of the viewing angle of the liquid crystal display 500 is still within the standard. That is, when the angle between the optical axis 411 and the liquid crystal alignment direction 351 of the upper alignment film 350 is in the range of -22.5 to 112.5 degrees, the image quality of the liquid crystal display 500 can still be accepted by the human eye.

In addition, it is worth mentioning that since the liquid crystal display 500 is similar to the liquid crystal display 400, the absorption axis positions of the polarizing plates of the liquid crystal display 500 can be arbitrarily interchanged.

Furthermore, although the liquid crystal alignment direction 331 and the liquid crystal alignment direction 351 of the liquid crystal display of the present embodiment are respectively at 45 degrees and 315 degrees, embodiments of the present invention are not limited thereto. In other embodiments of the present invention, the liquid crystal alignment direction 331 and the liquid crystal alignment direction 351 of the liquid crystal display may be 135 degrees and 225 degrees, respectively, that is, the angle between the liquid crystal alignment direction 331 and the liquid crystal alignment direction 351 is -90 degrees.

Fifth embodiment

Please refer to FIG. 6 , which is a schematic structural diagram of a liquid crystal display 600 according to an embodiment of the invention. The liquid crystal display 600 is similar to the liquid crystal display 400, but the liquid crystal display 600 has one less wide viewing angle compensation film 410. Referring to FIGS. 6a, 6b, and 6c, the absorption axis of the upper polarizing plate is 0 degrees, the absorption axis of the lower polarizing plate is 90 degrees, and the angle of the optical axis 421 of the wide viewing angle compensation film 420 is 270 degrees, and the diffraction sheet 370 When the diffraction direction is 270 degrees, the obtained gray scale distribution map is measured at different angles θ, where the vertical axis is the normalized brightness, the horizontal axis is the gray level, and the ψ is 225 degrees, 270 degrees and 315, respectively. Degree, and θ is 0 degrees, 30 degrees, 45 degrees and 60 degrees. It can be seen from the figure that in the above measurement angles, as the gray scale increases, the brightness also increases, and there is no known gray scale increase but the brightness is lowered to cause gray scale inversion. Therefore, although the liquid crystal display 600 of the present embodiment has one upper viewing angle compensation film 410 than the liquid crystal display 400, the image quality of the liquid crystal display 600 in the lower viewing angle can still reach the standard (the gray scale inversion index is less than 0.037).

The following description is for explaining the arrangement relationship between the absorption axis of the polarizing plate and the display panel. For the sake of simplifying the experiment, the following simulation includes only the lower polarizing plate 320, the lower alignment film 330, the liquid crystal layer 340, the upper alignment film 350, and the upper polarizing. The plate 360 or the like is not added to the diffraction sheet 370. However, according to the measurement results of the 6a, 6b, and 6c, it is known that the addition of the diffraction sheet 370 can make the optical of the side angle of view (θ ≠ 0) closer to the optical of the positive angle of view (θ = 0), thereby making the display quality more For improvement.

As can be seen from the above description, when the angle of the optical axis 421 of the wide viewing angle compensation film 420 is 270 degrees, the image quality of the liquid crystal display 600 in the lower viewing angle can still be reached. To the standard. In addition, it can be proved by experiments that even if the angle of the optical axis 421 of the wide viewing angle compensation film 420 falls within the range of 202.5 to 337.5 degrees, the image quality of the viewing angle of the liquid crystal display 600 is still within the standard. That is, when the angle between the optical axis 421 and the liquid crystal alignment direction 351 of the upper alignment film 350 is in the range of 157.5 to 292.5 degrees, the image quality of the liquid crystal display 600 can still be accepted by the human eye. In addition, it is worth mentioning that since the liquid crystal display 600 is similar to the liquid crystal display 400, the absorption axis position of the polarizing plate of the liquid crystal display 600 can be arbitrarily interchanged.

In addition, it is to be noted that although the liquid crystal alignment direction 331 and the liquid crystal alignment direction 351 of the liquid crystal display of the present embodiment are respectively at 45 degrees and 315 degrees, embodiments of the present invention are not limited thereto. In other embodiments of the present invention, the liquid crystal alignment direction 331 and the liquid crystal alignment direction 351 of the liquid crystal display may be 135 degrees and 225 degrees, respectively, that is, the angle between the liquid crystal alignment direction 331 and the liquid crystal alignment direction 351 is -90 degrees. In this case, when the angle between the optical axis 421 and the liquid crystal alignment direction 351 of the upper alignment film 350 is in the range of 67.5 degrees to 202.5 degrees, the gray scale inversion experienced by the user in the lower viewing angle of the display is greatly reduced. The phenomenon of grayscale inversion is not noticed.

In addition to the wide viewing angle film, the present invention can further add an optical film, such as an optical film having diffusion or scattering characteristics, between the polarizing film and the observer.

While the invention has been described above in terms of several embodiments, it is not intended to limit the scope of the invention, and the invention may be practiced in various embodiments without departing from the spirit and scope of the invention. Change and retouch, because The scope of the present invention is defined by the scope of the appended claims.

300‧‧‧LCD display

310‧‧‧Backlight module

320‧‧‧low polarizer

321‧‧‧Absorption axis

330‧‧‧ under the alignment film

331‧‧‧Liquid alignment direction

340‧‧‧Liquid layer

350‧‧‧Upward alignment film

351‧‧‧Liquid alignment direction

361‧‧‧Absorption axis

360‧‧‧Upper polarizer

370‧‧‧Diamonds

Claims (18)

A liquid crystal display comprising: a first polarizing plate having a first absorption axis; a second polarizing plate disposed opposite the first polarizing plate and having a second absorption axis, wherein the second absorption axis and the The angle of the first absorption axis is substantially 90 degrees; a liquid crystal layer is disposed between the first polarizing plate and the second polarizing plate; a first alignment film is disposed on the liquid crystal layer and the first polarizing plate And having a first liquid crystal alignment direction; a second alignment film disposed between the liquid crystal layer and the second polarizing plate and having a second liquid crystal alignment direction; and a diffraction sheet disposed on the liquid crystal a layer having at least one diffraction direction; wherein, when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees, the first absorption axis and the first liquid crystal alignment direction The angle is in the range of -45 degrees to -25 degrees, 25 degrees to 55 degrees, and 125 degrees to 135 degrees; when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially -90 degrees, Then clamping the first absorption axis and the first liquid crystal alignment direction Line in the range of 45 to 25 degrees, -25 degrees to -55 degrees and -125 degrees to -135 degrees. The liquid crystal display of claim 1, wherein the first absorption axis and the first liquid crystal alignment direction are when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees. The angle is substantially equal to -45 degrees, the angle between the second absorption axis and the second liquid crystal alignment direction is substantially equal to -45 degrees; and the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially - At 90 degrees, the angle between the first absorption axis and the first liquid crystal alignment direction is substantially equal to 45 degrees, and the angle between the second absorption axis and the second liquid crystal alignment direction is The mass is equal to 45 degrees. The liquid crystal display of claim 1, wherein the first absorption axis and the first liquid crystal alignment direction are when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees. The angle is substantially equal to 45 degrees, the angle between the second absorption axis and the second liquid crystal alignment direction is substantially equal to 45 degrees; and the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially -90 degrees The angle between the first absorption axis and the first liquid crystal alignment direction is substantially equal to -45 degrees, and the angle between the second absorption axis and the second liquid crystal alignment direction is substantially equal to -45 degrees. The liquid crystal display of claim 1, wherein the at least one diffraction direction of the diffractive sheet and the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction are substantially 90 degrees The angle of the first liquid crystal alignment direction is between 180 degrees and 270 degrees; and when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially -90 degrees, the at least one of the diffraction sheets The angle between the diffraction direction and the first liquid crystal alignment direction is between 90 degrees and 180 degrees. A liquid crystal display comprising: a first polarizing plate having a first absorption axis; a second polarizing plate disposed under the first polarizing plate and having a second absorption axis, wherein the second absorption axis The angle of the first absorption axis is substantially 90 degrees; a liquid crystal layer is disposed between the first polarizing plate and the second polarizing plate; a first alignment film is disposed on the liquid crystal layer and the first polarizing plate And having a first liquid crystal alignment direction; a second alignment film disposed between the liquid crystal layer and the second polarizing plate, and having a second liquid crystal alignment direction; a first wide viewing angle compensation film disposed between the first polarizing plate and the liquid crystal layer, wherein the first wide viewing angle compensation film has a first optical axis; and a diffraction piece, The first optical axis and the first The angle between the liquid crystal alignment directions is in the range of -22.5 degrees to 112.5 degrees; when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially -90 degrees, the first optical axis and the first The angle between the alignment directions of a liquid crystal is in the range of -112.5 degrees to 22.5 degrees. The liquid crystal display of claim 5, wherein when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees, the first absorption axis and the first liquid crystal alignment direction The angle is substantially equal to -45 degrees, the angle between the second absorption axis and the second liquid crystal alignment direction is substantially equal to -45 degrees; and the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially - At 90 degrees, the angle between the first absorption axis and the first liquid crystal alignment direction is substantially equal to 45 degrees, and the angle between the second absorption axis and the second liquid crystal alignment direction is substantially equal to 45 degrees. The liquid crystal display of claim 6, further comprising a second wide viewing angle compensation film disposed between the second polarizing plate and the liquid crystal layer, wherein the second wide viewing angle compensation film has a second light The axis, when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees, the angle between the second optical axis and the first liquid crystal alignment direction is in the range of 157.5 degrees to 292.5 degrees; And when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially -90 The angle between the second optical axis and the first liquid crystal alignment direction is in the range of 67.5 degrees to 202.5 degrees. The liquid crystal display of claim 5, wherein when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees, the first optical axis and the first liquid crystal alignment direction The angle is substantially equal to 45 degrees; and when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially -90 degrees, the angle between the first optical axis and the first liquid crystal alignment direction is substantially equal to - 45 degree. The liquid crystal display according to claim 8, wherein when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees, the second optical axis and the first liquid crystal alignment direction The angle is between 157.5 degrees and 247.5 degrees; and when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially -90 degrees, the second optical axis and the first liquid crystal alignment direction The angle is in the range of 67.5 degrees to 157.5 degrees. The liquid crystal display according to claim 8, wherein when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees, the second optical axis and the first liquid crystal alignment direction The angle is between 202.5 degrees and 292.5 degrees; and when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially -90 degrees, the second optical axis and the first liquid crystal alignment direction The angle is in the range of 112.5 degrees to 202.5 degrees. The liquid crystal display of claim 8, wherein an angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees. The angle between the second optical axis and the first liquid crystal alignment direction is in a range of 202.5 degrees to 247.5 degrees; and the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially -90 degrees. The angle between the second optical axis and the first liquid crystal alignment direction is in the range of 112.5 degrees to 157.5 degrees. The liquid crystal display of claim 5, wherein when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees, the first absorption axis and the first liquid crystal alignment direction The angle is substantially equal to 45 degrees, the angle between the second absorption axis and the second liquid crystal alignment direction is substantially equal to 45 degrees; and the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially -90 degrees The angle between the first absorption axis and the first liquid crystal alignment direction is substantially equal to -45 degrees, and the angle between the second absorption axis and the second liquid crystal alignment direction is substantially equal to -45 degrees. The liquid crystal display of claim 12, further comprising a second wide viewing angle compensation film disposed between the second polarizing plate and the liquid crystal layer, wherein the second wide viewing angle compensation film has a second light The axis, when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees, the angle between the second optical axis and the first liquid crystal alignment direction is in the range of 157.5 degrees to 292.5 degrees; And when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially −90 degrees, the angle between the second optical axis and the first liquid crystal alignment direction is in a range of 67.5 degrees to 202.5 degrees. The liquid crystal display of claim 5, wherein when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees, the at least one diffraction direction of the diffraction sheet is The angle between the first liquid crystal alignment directions Between 180 degrees and 270 degrees; and when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially -90 degrees, the at least one diffraction direction of the diffraction sheet and the first The angle between the alignment directions of the liquid crystal is between 90 degrees and 180 degrees. A liquid crystal display comprising: a first polarizing plate having a first absorption axis; a second polarizing plate disposed on the first polarizing plate and having a second absorption axis, wherein the second absorption axis The angle of the first absorption axis is substantially 90 degrees; a liquid crystal layer is disposed between the first polarizing plate and the second polarizing plate; a first alignment film is disposed on the liquid crystal layer and the first polarizing plate Between the first liquid crystal alignment direction, a second alignment film disposed between the liquid crystal layer and the second polarizing plate, and having a second liquid crystal alignment direction; a first wide viewing angle compensation film, Between the first polarizing plate and the liquid crystal layer, wherein the first wide viewing angle compensation film has a first optical axis; and a diffraction piece disposed on the first alignment film and having at least one diffraction direction Wherein, when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees, the angle between the first optical axis and the second liquid crystal alignment direction is in the range of 157.5 degrees to 292.5 degrees. And when the first liquid crystal alignment direction is When the angle of the second liquid crystal alignment direction substantially -90 degrees, the second angle between the optical axis of the alignment system of the first liquid in the range 67.5 degrees to 202.5 degrees. The liquid crystal display of claim 15, wherein the angle between the second absorption axis and the second liquid crystal alignment direction is substantially equal to -45 degrees, and the angle between the first absorption axis and the first liquid crystal alignment direction is Substantially equal to -45 degrees. The liquid crystal display according to claim 15, wherein when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially 90 degrees, the second absorption axis and the second liquid crystal alignment direction The angle is substantially equal to 45 degrees, the angle between the first absorption axis and the first liquid crystal alignment direction is substantially equal to 45 degrees; and the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially -90 degrees The angle between the first absorption axis and the first liquid crystal alignment direction is substantially equal to -45 degrees, and the angle between the second absorption axis and the second liquid crystal alignment direction is substantially equal to -45 degrees. The liquid crystal display of claim 15, wherein the at least one diffraction direction of the diffractive sheet and the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction are substantially 90 degrees The angle of the first liquid crystal alignment direction is between 180 degrees and 270 degrees; and when the angle between the first liquid crystal alignment direction and the second liquid crystal alignment direction is substantially -90 degrees, the at least one of the diffraction sheets The angle between the diffraction direction and the first liquid crystal alignment direction is between 90 degrees and 180 degrees.