TW201441677A - Optical compensation film, polarizing plate and liquid crystal display apparatus - Google Patents

Abstract

A polarizer including a long side and a short side perpendicular to the long side is provided. The optical compensating film is disposed on an emitting side of the polarizer and consists of a first diffracting grating and a second diffracting grating. The included angle between the direction of the connecting line of the wave peaks in the first diffracting grating and the long side of polarizer is from 0 to -35 degrees. The included angle between the direction of the connecting line of the wave peaks in the second diffracting grating and the short side of polarizer is from 0 to 35 degrees. The included angle between the direction of the connecting line of the wave peaks in the first diffracting grating and that of the second diffracting grating is from 0 to 70 degrees.

Description

Optical compensation film, polarizing plate and liquid crystal display device

The present invention relates to an optical compensation film, a polarizing plate and a liquid crystal display device, and more particularly to a twisted nematic liquid crystal display device having a better image quality of a lower viewing angle.

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 device, 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 beam. Enter the LCD panel to present the image.

Twisted Nematic (TN) or Super Twisted Nematic (STN) is one of the commonly used liquid crystal display devices. Although such a liquid crystal display device has a price advantage, in the case of a TN liquid crystal display device without any viewing angle compensation mechanism, usually, a lower view from the liquid crystal display device The image observed by the corner has problems such as grayscale inversion and severely reduced contrast (falling below 10).

Therefore, there is a need for a display device that can simultaneously improve image quality problems such as contrast, grayscale inversion, and the like.

The present invention relates to a polarizing plate and a display device, which can simultaneously improve the image quality such as gray scale inversion and contrast.

An object of the present invention is to provide a polarizing plate and a liquid crystal display device having a long side and a short side, the short side being perpendicular to the long side, and comprising a polarizing layer having a transmission axis and an optical compensation film. The optical compensation film is disposed on the light exiting side of the polarizing plate, and is composed of a first diffraction grating, a second diffraction grating and a non-grating region, and the diffraction grating includes a plurality of peak structures. The angle between the peak connecting line of the first diffraction grating and the long side of the polarizing plate is between 0 and -35 degrees, and the angle between the peak connecting line of the second diffraction grating and the long side of the polarizing plate is between 0 and 35 degrees. And the angle between the direction of the peak connection of the first diffraction grating and the direction of the peak connection of the second diffraction grating is between 0 and 70 degrees.

In order to provide a better understanding of the above and other aspects of the present invention, the following detailed description of the embodiments and the accompanying drawings

2, 32, 33, 62, 62', 63, 72, 82, 92, 92', 92", 95, 96, 97, 98, 99, 100, 402, 1093, 1094‧ ‧ optical compensation film

10‧‧‧ display device

43, 53, 93, 103, 113, 272, 277, 278, 279, 287, 287', 289, 289', 291, 292, 293, 293', 293" ‧‧ ‧ grating area

44, 54, 94, 104, 114, 114', 275, 276, 298, 299, 300, 301 ‧ ‧ diffraction grating

411‧‧‧Backlight module

415, 425‧‧ ‧ polarizing plate

416‧‧‧Film Optoelectronic Substrate

417, 419‧‧ ‧ alignment film

418‧‧‧Liquid layer

421‧‧‧Color filter substrate

427‧‧‧LCD panel

445, 455‧‧‧ polarized direction

P‧‧‧ spacing

The closest distance between the grating regions of S1, S2, S4, S5, S12, S13, S15‧‧ from

W3, W4, W9, W10, W11, W13, W14, W15, W17, W18, W19‧‧ Width

The angle between the τ1, τ2, τ3, τ4, τ5, τ6‧‧ ‧ diffraction grating and the long side of the display device (parallel X axis)

ψ 1, ψ 1‧ ‧ azimuth

FIG. 1 is a perspective view of a display device according to an embodiment of the present invention.

2A, 2B, 4A~4C, 5A~5C, 6A~6D, 7A~7C, 8~10 A schematic diagram of an optical compensation film of an embodiment of the present invention.

FIG. 3 is a schematic diagram showing a grating region according to an embodiment of the present invention.

Figure 11 is a cross-sectional view showing a display device in accordance with an embodiment of the present invention.

FIG. 12 is a schematic view showing a polarizing plate according to an embodiment of the present invention.

Referring to FIG. 1, an optical compensation film 2 is disposed on the light-emitting side of the display device 10 for displaying images. In the present embodiment, the display device 10 is a liquid crystal display device and has a long side (parallel X axis) and a short side (parallel Y axis), and the long side and the short side are perpendicular to each other. However, the present invention is not limited thereto, and the display device 10 may be a plasma display device, an organic light emitting diode display device, an electronic paper display device, or other display device for displaying images. The optical compensation film 2 is, for example, an O film, and is disposed on the light outgoing side of the display device 10 that displays an image.

FIG. 1 is a perspective view of a display device according to an embodiment of the present invention. Here, in order to facilitate the description of the image quality problem of the viewing angle image of the display device, 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. The zenith angle θ is used to indicate the angle between a certain direction and the axis of the vertical display surface (i.e., the Z axis). The azimuth angle is used to indicate the angle between a direction and the long side (parallel X axis). For example, the light exit surface of the display device is an XY plane, and the direction of the positive Z axis extends from the light exit surface toward the observer (the normal direction of the light exit surface), so that the viewing angle of the display device 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.

2A, 2B, 4A to 4C, 5A to 5C, 6A to 6D, 7A to 7C, and 8 to 10 are schematic views showing an optical compensation film according to an embodiment of the present invention. FIG. 3 illustrates an embodiment of the present invention Schematic diagram of the grating area. Referring to FIG. 2A, in an embodiment, the optical compensation film 32 includes grating regions 43 and grating regions 53 that are separated from each other. The grating region 43 of the optical compensation film 32 and the "general region (or non-grating region)" other than the grating region 53 generate a region of a lower degree of diffraction. In detail, the grating region 43 and the grating region 53 can be The light penetrated in a specific direction causes a zero-order diffraction (injection direction is invariant and direct emission) and a non-zero-order diffraction (change in the direction of the exit). The sum of the light is less than a 100:1 high diffraction effect. (or non-grating region)" is a low-diffraction with a ratio of zero-order diffraction (direct exit) and non-zero-order diffraction (change in exit direction) to the transmitted light with an intensity ratio greater than 100:1. The effect is to enhance the amount of light transmitted. The grating region 43 and the grating region 53 are arranged in a plurality of courses, respectively. The staggered grating regions 43 and the grating regions 53 form a plurality of straight rows.

The grating region 43 and the grating region 53 each have a periodically fixed diffraction grating 44 and a diffraction grating 54. Referring to Fig. 3, the periodically fixed diffraction grating, i.e., the peak connection L (or the valley connection) of the diffraction grating structure, has a uniform pitch P. In the examples, it may be 0.5 μm to 1.5 μm, and most preferably 0.8 μm to 1.3 μm. In Fig. 2A, the diffraction grating 44 and the diffraction grating 54 have the same pitch P.

In the row formed by the staggered arrangement of the grating region 43 and the grating region 53, the closest distance between the grating region 43 and the grating region 53 can be adjusted to be fixed or variable depending on actual needs. For example, the closest distance S1, S2 between the grating region 43 and the grating region 53 may be between 1 μm and 15 μm, for example, 5 μm. In another embodiment, the closest distance between the grating region 43 and the grating region 53 may be 0 or even a negative number (ie, a region where the grating region 43 and the grating region 53 overlap each other).

In addition, the rows and columns formed by the grating region 43 and the grating region 53 respectively The closest distance between the closest distance between the grating regions 43 and the grating region 53 can be adjusted to be fixed or variably depending on actual needs, respectively. In one embodiment, the closest distance S4 between the grating regions 43 and the closest distance S5 between the grating regions 53 are between 1 μm and 15 μm, for example 5 μm. In another embodiment, the closest distance S4 between the grating region 43 and the closest distance S5 between the grating regions 53 may be 0 or even a negative number (ie, there is mutual intersection between the grating regions 43 or the grating regions 53). Stacked area).

In the present invention, the direction of the grating region of the optical compensation film (i.e., the direction of the diffraction grating) is the direction of the peak line L of the diffraction grating structure (refer to FIG. 3), and the direction of the diffraction grating and the polarizing plate The angle between the long side (parallel X axis) is the angle between the direction of the peak line L of the diffraction grating and the long side of the polarizing plate (parallel X axis), that is, the azimuth angle of the diffraction grating. However, the direction of the diffraction grating is not limited to the direction of the peak connection L of the diffraction grating structure, and the direction of the valley connection (not shown) of the diffraction grating structure may be the direction of the diffraction grating. In an embodiment, the azimuth angle of the diffraction grating is also equal to the angle between the direction of the diffraction grating and the long side (parallel X axis) of the display device 10, and is also the direction and display device of the peak connection L of the diffraction grating. The angle between the long side of 10 (parallel X axis). The angle between the diffraction grating and the long side (parallel X axis) of the display device 10 may be +35 degrees to -35 degrees. In some embodiments, the diffraction grating and the long side of the display device 10 (parallel X axis) The angle can be between -10~-35 degrees or +10~+35 degrees. The angle between the two directions is expressed in the counterclockwise direction and the clockwise angle is negative. One direction rotates counterclockwise until the angle coincident with a second direction is positive, and the angle formed by clockwise rotation from the first direction to coincide with the second direction is negative.

It should be noted, however, that although the embodiment of the present invention is based on the angle between the direction of the diffraction grating and the long side (parallel X axis) of the polarizing plate (that is, the peak connection of the diffraction grating) The angle between the direction of L and the long side of the polarizing plate is the azimuth angle of the diffraction grating, but the present invention is not limited thereto. In contrast, in the present invention, the angle between the direction of the diffraction grating and the reference edge of one of the polarizing plates is the azimuth angle of the diffraction grating, and the reference edge is selected from one of the long side and the short side of the polarizing plate.

In addition, the display device, the polarizing plate and the optical compensation film disclosed in the present invention have a parallel X-axis, and the short side of the display device, the polarizing plate and the optical compensation film are parallel Y-axis. That is, the azimuth angle of the diffraction grating may be an angle between the direction of the diffraction grating and the reference edge of any of the display device, the polarizing plate, and the optical compensation film.

For example, in the embodiment illustrated in FIG. 2A, the angle τ1 of the diffraction grating 44 and the long side (parallel X axis) of the polarizing plate (or the display device 10 and the optical compensation film 32) is -35 The angle τ2 between the diffraction grating 54 and the long side (parallel X axis) of the polarizing plate (or the display device 10 and the optical compensation film 32) is +35 degrees. However, the angle τ1 between the diffraction grating 44 and the long side (parallel X axis) of the polarizing plate (or the display device 10 and the optical compensation film 32) may be between 0 and 35 degrees, and the diffraction grating 54 is not limited thereto. The angle τ2 between the long side (parallel X axis) of the polarizing plate (or the display device 10 and the optical compensation film 32) may be between 0 and +35 degrees, that is, the direction of the peak connecting the diffraction grating 44. The angle with the direction of the peak connecting the diffraction grating 54 may be between 0 and 70 degrees. In another embodiment, the angle τ1 between the diffraction grating 44 and the long side (parallel X axis) of the polarizing plate (or the display device 10 and the optical compensation film 32) may be between -10 and -35 degrees, and the diffraction The angle τ2 between the grating 54 and the long side (parallel X axis) of the polarizing plate (or the display device 10 and the optical compensation film 32) may be between +10 and +35 degrees, that is, the peak of the diffraction grating 44 The angle between the direction of the line and the direction of the peak of the diffraction grating 54 may be between 20 and 70 degrees.

The diffraction optical compensation film 62 of FIG. 4A and the optical compensation film 32 of FIG. 2A The difference is that the optical compensation film 62 includes three different directions of grating regions 93, 103 and 113, which are respectively composed of diffraction gratings 94, 104 and 114 having different azimuth angles. In the embodiment, the angle between the direction of the peak connection of the diffraction grating 114 and the direction of the line connecting the peaks of the diffraction grating 94, and the direction of the peak connection of the diffraction grating 114 are connected with the peak of the diffraction grating 104. The angle of the direction may be between 0 and 35 degrees, preferably between 10 and 35 degrees. For example, the angle τ3 of the diffraction grating 94 and the long side (parallel X axis) of the polarizing plate is -35 degrees, and the angle τ4 of the diffraction grating 104 and the long side (parallel X axis) of the polarizing plate is +35 degrees, the angle between the diffraction grating 114 and the long side (parallel X axis) of the polarizing plate is 0 degree (that is, parallel to the long side of the polarizing plate).

In an embodiment, the angle between the diffraction grating 114 and the long side (parallel X axis) of the polarizing plate may be between -15 and +15 degrees.

In the above embodiment, each of the diffraction gratings has the same pitch P as an example, but as shown in FIG. 4B, the pitch P of the diffraction gratings 94, 104 and 114' of the optical compensation film 62' may also be mutually Different, for example, the pitch of the diffraction gratings 94, 104 is greater than the pitch of the diffraction grating 114'. Further, the absolute values of the angles between the diffraction gratings 94, 104 and the long sides (parallel X axes) of the display device 10 may be different from each other. For example, the angle τ3 of the diffraction grating 94 and the long side (parallel X axis) of the display device 10 may be -20 degrees, and the diffraction grating 104 and the long side (parallel X axis) of the display device 10 are sandwiched. The angle τ4 can be +15 degrees.

The grating area is also not limited to the circular outlines as shown in Figs. 2A, 4A and 4B. In some embodiments, the grating region of the optical compensation film may be an elongated grating region, and the first grating region and the second grating region may overlap or be spaced apart from each other. The aforementioned intervals form a general region (non-grating region). The width of the grating region (perpendicular to the peak connection of the diffraction grating structure) may be 20 to 46 μm, preferably 22 to 30 μm. Width of the non-grating region (perpendicular to the diffraction grating junction The peak of the structure is greater than 0 and less than 6 μm.

As shown in FIG. 2B, the optical compensation film 72 includes an elongated grating region 272 and a grating region 274. The angle τ5 between the direction of the peak connection of the diffraction grating 275 of the grating region 272 and the long side (parallel X axis) of the polarizing plate is -35 degrees. The angle τ6 between the direction of the peak connection of the diffraction grating 276 of the grating region 274 and the long side (parallel X axis) of the polarizing plate is +35 degrees. In one embodiment, the longitudinal (Y-direction) width W3 of the grating region 272 and the longitudinal (Y-direction) width W4 of the grating region 274 may be between 20 and 46 μm, preferably 22 to 30 μm, and the grating region 272 and the grating region 274. The closest distance (pitch) S15 between the longitudinal direction (Y direction) may be between -2 and 6 μm (negative, that is, a region where the grating region 272 and the adjacent grating region 274 overlap each other).

In an embodiment, the grating region and the adjacent grating region may have overlapping regions. For example, as shown in FIG. 5A, the first diffraction grating and the second diffraction grating overlap each other. The optical compensation film 92 includes grating regions 287 and 289, and the longitudinal (Y-direction) width W9 of the grating region 287 and the longitudinal (Y-direction) width W11 of the grating region 289 may be respectively 20 to 46 μm, preferably 22 to 30 μm. The longitudinal (Y-direction) width W10 of the overlapping portion of the grating region 287 and the grating region 289 may be between 6 and 17 μm. The closest distance S12 between the grating region 287 and another unoverlapping grating region 289 may be between -2 and 6 μm, that is, the width of the non-grating region (perpendicular to the peak of the diffraction grating structure) is greater than 0 and less than 6 μm.

In addition, as shown in FIG. 5B, in an embodiment, the angle between the grating region 287' of the optical compensation film 92' and the long side (parallel X-axis) of the polarizing plate may be 0 degrees, as shown in FIG. 5C. In another embodiment, the angle between the optical compensation film 92" grating region 289' and the long side (parallel X axis) of the polarizing plate may be 0 degrees.

In some embodiments, as such, the optical compensation film may also include three types of An elongated grating area of the same azimuth. Referring to FIG. 4C, the optical compensation film 82 includes grating regions 277, 278, and 279. The azimuth angles of the grating regions 277, 278, and 279 can be, for example, -35 degrees, +35 degrees, and 0 degrees.

In some embodiments, an optical compensation film having three grating regions at the same time, the grating regions thereof may partially overlap each other to form various different embodiments. For example, FIGS. 6A-6D, FIGS. 7A-7C, and FIG. 8 illustrate a grating region 291 having a diffraction grating having an azimuth angle of -35 degrees, a grating region 292 having a diffraction grating having an azimuth angle of +35 degrees, and having The grating regions 293 of the diffraction grating having an azimuth angle of 0 degrees, the grating regions 291 to 293 may partially overlap each other to form various different embodiments.

In an embodiment, the grating region of the optical compensation film may have three or more grating regions of different grating directions. The grating region may have only one partial overlapping region, and the two grating regions overlap each other, for example, wherein the second grating region and the third grating region may overlap each other, and the first grating region and the second or third grating region are not overlapped. Overlapping each other, as shown in Figures 6A~6D. The grating region may have only two partial overlapping regions, which are two sets of overlapping regions, and each of the overlapping regions is overlapped by two grating regions, for example, the first grating region and the second grating region may overlap each other. The first grating region and the third grating region overlap each other, and the second grating region and the third grating region do not overlap each other, as shown in FIGS. 7A-7C. The aforementioned grating region may also have three partial overlapping regions, as shown in FIG.

In addition, the longitudinal (Y direction) width of the grating region may be between 22 and 30 μm, and the partial overlap region may be between 6 and 17 μm. The width of the non-grating region (perpendicular to the peak of the diffraction grating structure) is greater than 0 and less than 6 μm.

As shown in FIGS. 6A and 6B, the grating region 291 and the grating region 292 are in two types. The different ways overlap, and the grating regions 291, 292 and the grating regions 293 do not overlap each other at all, thus forming optical compensation films 1093, 1094, respectively. As shown in FIGS. 6C and 6D, the grating regions 293 partially overlap the grating regions 291, 292, respectively, and the grating regions 291, 292 do not overlap each other at all, thereby forming the optical compensation films 95, 96.

Figures 7A-7C show two partial overlap regions in the optical compensation film. As shown in FIG. 7A, the grating region 293 in the optical compensation film 97 partially overlaps the grating region 291, the grating region 293, and the grating region 292, thereby forming diffraction gratings 298, 299, respectively, and diffraction gratings 298, 299. The closest distance S13 between may be between -2 and 6 μm. When S13 is greater than 0, a non-grating region is formed between the diffraction gratings 298, 299, and the width of the non-grating region (peripheral to the peak of the diffraction grating structure) is greater than 0 and less than 6 μm. As shown in FIG. 7B, one side of the grating region 293 of the optical compensation film 98 partially overlaps the grating region 291, and the other side of the grating region 293 partially overlaps the grating region 292.

As shown in FIG. 7C, in an embodiment, the longitudinal (Y-direction) width W13 of the grating region 293' of the optical compensation film 99 may be smaller than the longitudinal (Y-direction) width W14 of the grating region 291 and the longitudinal direction of the grating region 292. (Y direction) width W15. Since the longitudinal (Y-direction) width W13 of the grating region 293' is smaller than the longitudinal (Y-direction) width W14 of the grating region 291 and the longitudinal (Y-direction) width W15 of the grating region 292, the grating region 293' can completely overlap the grating region. 291 and grating region 292, and diffraction gratings 300 and 301 are formed, respectively. Further, neither of the grating regions 293' may overlap the grating region 291 and the grating region 292 to form the diffraction grating 303, and the diffraction gratings 300, 301, and 303 do not overlap each other.

Figure 8 shows three partial overlap regions in the optical compensation film. In an embodiment, the longitudinal (Y-direction) width W17 of the grating region 293" of the optical compensation film 100 may be greater than The longitudinal (Y-direction) width W18 of the grating region 291 and the longitudinal (Y-direction) width W19 of the grating region 292. As shown in Fig. 18, the grating region 291 partially overlaps the grating region 292 and then completely overlaps the grating region 293".

In the above-mentioned 6A to 6D, 7A to 7C, and 8 diagrams, the longitudinal (Y-direction) widths of the grating regions 291 to 293 may be respectively 22 to 30 μm, and the partial overlapping regions may be 6 to 17 μm.

Further, the shape and azimuth angle of the two grating regions having the overlapping portions are not limited to the above embodiments. The shape of the two grating regions having the overlapping portions of the embodiment of the present invention may be circular as shown in Figs. As shown in Fig. 9, the difference between the optical compensation film 33 and the optical compensation film 32 of Fig. 2 is that the grating regions 43, 53 may partially overlap. As shown in Fig. 10, the difference between the optical compensation film 63 and the optical compensation film 62 of Fig. 4 is that the grating regions 113 can partially overlap the grating regions 93, 103, respectively.

Figure 11 is a cross-sectional view showing a display device in accordance with an embodiment of the present invention. The display device 10 is exemplified by a liquid crystal display device, and includes a backlight module 411, a liquid crystal panel 427, and polarizing plates 415 and 425. The liquid crystal panel 427 is disposed on the backlight module 411 and includes, for example, a thin film transistor substrate 416, a liquid crystal layer 418, a color filter substrate 421, and alignment films 417 and 419. The alignment film 419 can be disposed on the color filter substrate 421. The alignment film 417 may be disposed on the thin film transistor substrate 416. The liquid crystal layer 418 can be disposed between the alignment films 417 and 419. The polarizing plate 415 can be disposed between the thin film transistor substrate 416 and the backlight module 411 (the light incident side of the liquid crystal panel 427). The polarizing plate 425 can be disposed on the color filter substrate 421 (the light exiting side of the liquid crystal panel 427).

The optical compensation film 402 may be disposed on the light-emitting side of the liquid crystal panel 427 , for example, on the light-emitting side of the polarizing plate 425 , or may be disposed between the liquid crystal panel 427 and the polarizing plate 425 . The configuration of the optical compensation film 402 is not limited to facing the peak structure to the polarizing plate 425, and may also be back-biased. Light board 425. The optical compensation film 402 can also be stacked with other accessories having different functions (for example, an anti-reflection layer, a scratch-resistant layer, etc.). It is to be noted that the optical compensation film 402 can be as various optical compensation films as described above, including a plurality of grating regions of different configurations.

Further, the polarizing plate has a polarizing layer whose polarizing direction is equal to the direction of the transmission axis of the polarizing layer in the polarizing plate. As shown in FIGS. 2A, 2B, and 12, the azimuth angle 4451 of the polarizing direction 445 of the light-emitting plate 425 on the light-emitting side is 135 degrees (or expressed by -45 degrees), that is, the polarizing layer is worn in the polarizing plate 425. The azimuth of the through-axis is 135 degrees (-45 degrees), and the azimuth angle of the absorption axis is 45 degrees (225 degrees). The azimuth angle 4552 of the polarizing direction 455 of the polarizing plate 415 adjacent to the backlight module is 45 degrees, that is, the transmission axis azimuth angle of the polarizing plate is 45 degrees, and the absorption axis azimuth angle is 135 degrees. However, it is not limited to this.

In the embodiment, the experimental method is to measure the 96V SAGAW50510237 liquid crystal display device (pixel 1366*768) equipped with the display device 10 of FIG. 1 by Konica Minolta CS-2000, and the optical compensation as shown in FIG. The film 32, the diffraction grating 44 (τ1) with different azimuth angles and the diffraction grating 54 (τ2) of different azimuth angles, measure the bright state and the dark state of the display device every 5 degrees, and calculate the contrast value (bright state (255 Grayscale) Luminance/Dark State (0 Grayscale) Luminance, and the user's perception of the grayscale inversion at 45 degrees in the lower viewing angle, as shown in Table 1.

It can be seen from Table 1 that when the diffraction gratings 44 and 54 have a large azimuth angle (ie, τ1≦-40 degrees, τ2≧40), although the center contrast value is better, the gray scale inversion phenomenon is obviously felt. . The azimuth angle τ1 of the diffraction grating 44 is 0 to -35 degrees, and the azimuth angle τ2 of the diffraction grating 54 is 0 to +35 degrees, that is, the direction and the winding of the diffraction grating 44. The angle of the direction of the grating 54 is between 0 and 70 degrees, which not only can effectively improve the gray scale inversion phenomenon, but also maintain the center contrast value above 60%. In order to maintain a certain visual effect, it is better to maintain The contrast value of the heart is above 75%, so the azimuth angle τ1 of the diffraction grating 44 is between -10 and -35 degrees, and the azimuth angle τ2 of the diffraction grating 54 is between +10 and +35 degrees, that is, the diffraction grating The angle between the direction of 44 and the direction of the diffraction grating 54 is between 20 and 70 degrees.

In another embodiment, the experimental method is to measure a 96V SAGAW50510237 liquid crystal display device (pixel 1366*768) equipped with the display device 10 of FIG. 1 by Konica Minolta CS-2000, and as shown in FIG. The optical compensation film 62, the diffraction grating 114 has an azimuth angle of 0 degrees (ie, parallel to the long side of the display device 10), and a diffraction grating 94 (τ3) of different azimuth angles and a diffraction grating 104 of different azimuth angles (τ4) ), measuring the bright state and the dark state of the display device every 5 degrees, and calculating the contrast value (bright state (255 gray scale) brightness / dark state (0 gray scale) brightness), and the user viewing the display screen at a lower angle of view 45 degrees The degree of susceptibility to grayscale inversion is shown in Table 2.

It can be seen from Table 2 that when the diffraction gratings 94 and 104 have a large azimuth angle (ie, τ3≦-40 degrees, τ4≧40), although the center contrast value is better, the gray scale inversion phenomenon is obviously felt. . The azimuth angle τ3 of the diffraction grating 94 is 0 to -35 degrees, and the azimuth angle τ4 of the diffraction grating 104 is 0 to +35 degrees, that is, the direction and the winding of the diffraction grating 94. The angle of the direction of the grating grating 104 is between 0 and 70 degrees, and the angle between the diffraction grating 114 and the direction of the diffraction grating 94, and the angle between the diffraction grating 114 and the diffraction grating 104 may be between 0 and 35 degrees. Not only can it effectively improve the gray-scale reversal phenomenon, but also maintain the center contrast value above 60%. In order to maintain a certain visual effect, it is preferable to maintain the center contrast value at 75% or more, so the azimuth angle τ3 of the diffraction grating 94 is between -10 and -35 degrees, and the azimuth angle τ4 of the diffraction grating 104 is between +10 and +35 degrees, that is, the angle between the direction of the diffraction grating 94 and the direction of the diffraction grating 104 is between 20 and 70 degrees, and the direction of the peak connection of the diffraction grating 114 is connected to the peak of the diffraction grating 94. The angle between the directions of the directions, and the direction of the peak connection of the diffraction grating 114 and the direction of the peak of the diffraction grating 104 may be between 10 and 35 degrees.

In conclusion, the present invention has been disclosed in the above embodiments, but it is not intended to limit the present invention. A person skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

32‧‧‧Diffractive optical components

43, 53‧‧‧ raster area

44, 54‧‧‧Diffraction grating

445, 455‧‧‧ polarized direction

The closest distance between the S1, S2, S4, S5‧‧ ‧ raster regions

Τ1, τ2‧‧‧ angle of the direction of the diffraction grating

ψ 1, ψ 1‧ ‧ azimuth

Claims (13)

A polarizing plate having a long side, a short side, and a polarizing layer having a transmission axis, the short side being perpendicular to the long side, wherein the polarizing plate has a reference edge selected from the long side and the short side In one of the above, the polarizing plate is characterized in that an optical compensation film is disposed on the light exiting side of the polarizing plate, and the optical compensation film is composed of a first diffraction grating, a second diffraction grating and a non-grating region. The first diffraction grating and the second diffraction grating comprise a plurality of peak structures; wherein an angle between a peak connection of the first diffraction grating and the reference edge is between 0 and -35 degrees, The angle between the direction of the peak connection of the second diffraction grating and the reference edge is between 0 and 35 degrees, and the direction of the peak connection of the first diffraction grating is connected with the peak of the second diffraction grating. The angle between 0 and 70 degrees. The polarizing plate of claim 1, wherein a direction of a peak connecting the first diffraction grating and an angle of the reference edge is between -10 and -35 degrees, and the peak of the second diffraction grating is connected. The angle between the direction of the line and the reference edge is between 10 and 35 degrees, and the angle between the direction of the peak of the first diffraction grating and the direction of the peak of the second diffraction grating is between 20 and 70 degrees. . The polarizing plate of claim 1, wherein the first diffraction grating and the second diffraction grating partially overlap. An optical compensation film having a long side and a short side perpendicular to the long side, wherein the optical compensation film has a reference edge selected from one of the long side and the short side, the optical compensation The film is characterized in that the optical compensation film comprises a first diffraction grating, a second diffraction grating, and a a third diffraction grating, the second diffraction grating and the third diffraction grating comprise a plurality of peak structures; wherein a direction of the peak connection of the first diffraction grating and the reference edge The angle between 0 and -35 degrees, the direction of the peak connection of the second diffraction grating and the reference edge is between 0 and 35 degrees, and the direction of the peak connection of the first diffraction grating and the first The angle between the directions of the peaks of the two diffraction gratings is between 0 and 70 degrees, the angle between the direction of the peak connection of the third diffraction grating and the direction of the line connecting the peaks of the first diffraction grating, and the first The angle between the direction of the peak connection of the three diffraction gratings and the direction of the peak connection of the second diffraction grating is 10 to 35 degrees, respectively. A polarizing plate having a long side and a short side perpendicular to the long side, wherein the polarizing plate has a reference edge selected from one of the long side and the short side, and the polarizing plate is characterized In an optical compensation film, the optical compensation film includes a first diffraction grating, a second diffraction grating, and a third diffraction grating, the first diffraction grating, the second diffraction grating, and the third The diffraction grating includes a plurality of peak structures; wherein an angle between a direction of the peak connection of the first diffraction grating and the reference edge is between 0 and -35 degrees, and a direction of the peak connection of the second diffraction grating The angle of the reference edge is between 0 and 35 degrees, and the angle between the direction of the peak connection of the first diffraction grating and the direction of the peak of the second diffraction grating is between 0 and 70 degrees, and the third winding An angle between a direction in which the peak of the grating grating is connected to a peak of the first diffraction grating, and a direction in which the peak of the third diffraction grating is connected to a peak of the second diffraction grating The angles are between 0 and 35 degrees. The polarizing plate of claim 5, wherein an angle between a direction of a peak connecting line of the third diffraction grating and a direction of a line connecting the peaks of the first diffraction grating, and a third diffraction grating The angle between the direction of the peak connection and the direction of the peak of the second diffraction grating is between 10 and 35 degrees, respectively. The polarizing plate of claim 5, wherein a direction of the peak connection of the third diffraction grating is between -15 and 15 degrees from the reference edge. The polarizing plate of claim 5, wherein the third diffraction grating partially overlaps one of the first diffraction grating and the second diffraction grating. The polarizing plate of claim 5, wherein the third diffraction grating partially overlaps the first diffraction grating and the second diffraction grating. The polarizing plate of claim 5, wherein the polarizing plate further comprises a non-grating region. A liquid crystal display device, comprising: the polarizing plate according to claim 5, wherein the liquid crystal display device further comprises: a second polarizing plate; and a liquid crystal panel between the polarizing plate and the second polarizing plate The polarizing plate is disposed on the light emitting side of the liquid crystal panel, and the optical compensation film is disposed on the light emitting side of the polarizing plate. A liquid crystal display device, comprising: the polarizing plate according to claim 5, wherein the liquid crystal display device further comprises: a second polarizing plate; and a liquid crystal panel between the polarizing plate and the second polarizing plate ; The polarizing plate is disposed on the light emitting side of the liquid crystal panel, and the optical compensation film is disposed between the polarizing plate and the liquid crystal panel. The liquid crystal display device of claim 11, wherein the polarization direction of the polarizing plate is 135 degrees, and the azimuth of the polarizing direction of the second polarizing plate is 45 degrees.