CN211786510U - Optical film, backlight module and display device - Google Patents

Abstract

The utility model relates to an optical film, a backlight module and a display device. The optical film includes a light incident side and a light exiting side opposite to the light incident side. The optical film is divided into a middle area and two side areas respectively located on both sides of the middle area along the direction of the X-axis, wherein a plurality of strip structures in a convex shape are arranged on the light exiting side of each side area, a plurality of the strip structures are arranged along the direction of the X-axis, and each of the strip structures extends along the direction of the Y-axis perpendicular to the X-axis, and each of the strip structures includes a repeatedly arranged high microstructure and a low microstructure whose height is lower than the high microstructure. Through the shape and arrangement of the strip structures on the optical film, light with an excessively large angle can be refracted again, thereby improving the problems of large-angle light field and large-angle light leakage, and further improving the contrast of large-angle viewing angle. The backlight module and the display device include the optical film.

Description

Optical film, backlight module and display device

technical field

The utility model relates to an optical element, in particular to an optical film, a backlight module and a display device which can improve large-angle light leakage and improve large-angle contrast.

Background technique

Since the liquid crystal display panel does not have the function of emitting light, a backlight module must be arranged below the liquid crystal display panel to provide a surface light source, so that the liquid crystal display panel can achieve the purpose of display.

Generally speaking, light source modules can be divided into direct-type light source modules and edge-type light source modules. Taking the direct light source module as an example, it usually includes a plurality of light-emitting elements, a reflective sheet for concentrating the light of the light-emitting element array to the forward direction, and for reducing the viewing angle of the light beam, increasing the forward luminance value, and Multilayer optical film set with light extraction efficiency. On the other hand, taking an edge-type light source module as an example, it generally includes a light guide plate, a reflective sheet located under the light guide plate, a light source located on the side of the light guide plate, and the aforementioned multilayer optical film set. After the light beam emitted by the light source enters the light guide plate from the light incident surface located on the side of the light guide plate, it will be guided into the entire light guide plate due to total reflection. The multiple dots on the bottom surface of the light guide plate will destroy the total reflection of light, so that the light beam will be emitted from the light-emitting surface of the light guide plate, and the forward brightness value and light output efficiency will be improved by the aforementioned multilayer optical film group, thus forming the required Area light source.

However, whether it is a direct-type light source module or an edge-type light source module, when the user is viewing the areas on both sides of the screen, the larger the screen is, the larger the user's viewing angle will become, resulting in the easier the viewing of the large viewing angle area of the screen. Light leakage occurs at the place, causing white fog, resulting in a decrease in the contrast between light and dark, which affects the quality of the picture.

Utility model content

Therefore, the purpose of the present invention is to provide an optical film that can improve the contrast between light and dark in the large viewing angle areas on both sides of the screen.

The optical film of the present invention includes a light incident side and a light exit side opposite to the light incident side. The optical film is divided into a middle area along the direction of the X-axis and two sides respectively located on both sides of the middle area. The side area, wherein the light-emitting side of each side area is arranged with a plurality of strip-shaped structures in a protruding shape, the plurality of strip-shaped structures are arranged along the direction of the X-axis, and each of the strip-shaped structures is arranged along the direction of the X-axis. Extending in the direction of the Y-axis perpendicular to the X-axis, each of the strip-like structures includes repeating high microstructures and low microstructures whose heights are lower than the high microstructures.

Another technical means of the present invention is that the ratio of the number of the high microstructures to the low microstructures is equal to 1 at the extreme end of each of the side regions away from the middle region along the X-axis.

Another technical means of the present invention is that a plurality of the strip-shaped structures in a protruding shape are arranged on the light-emitting side of the intermediate area of the optical film, and each strip-shaped structure in the intermediate area includes a repeating arrangement The high microstructure of and the low microstructure whose height is lower than the high microstructure.

Another technical means of the present invention is that the number ratio of the high microstructures and the low microstructures in the middle region is equal to the number ratio of the high microstructures and the low microstructures in each of the side regions, both of which are equal to 1.

Another technical means of the present invention is that the ratio of the number of the high microstructure to the low microstructure increases from the center of the middle region toward the side region along the direction of the X-axis.

Another technical means of the present invention is that the number of the high microstructures in each side region does not exceed the number of the low microstructures at most.

Another technical means of the present invention is to define a center line perpendicular to the vertex of any one of the low microstructures and a tangent line passing through the vertex and tangent to the adjacent high microstructure, the center line and the The acute angle between the tangents is greater than or equal to 60 degrees.

Another technical means of the present invention is that a plurality of the strip structures are closely arranged.

Another object of the present invention is to provide a backlight module.

The backlight module of the present invention comprises a light source, an optical plate for receiving the light source, a film set on the optical plate, and the aforementioned optical film set on the film set.

Another object of the present invention is to provide a display device.

The display device of the present invention includes the aforementioned backlight module and a display panel disposed on the backlight module, wherein the X-axis is defined as the horizontal direction in which the user views the display panel, and the Y-axis is defined as the user's View the vertical orientation of the display panel.

The effect of the present invention is that, through the shape and arrangement of the strip-like structures on the optical film, light with an excessively large angle can be refracted again, thereby improving the problems of large-angle light field and large-angle light leakage, and further improving the Contrast at large viewing angles.

Description of drawings

1 is a schematic side view showing a preferred embodiment of the backlight module of the present invention;

FIG. 2 is a schematic perspective view illustrating the structure of the optical film in FIG. 1;

Fig. 3 is a side view schematic diagram to assist in explaining Fig. 2;

4 is a graph illustrating the change in the ratio of high microstructure to low microstructure in an optical film;

Fig. 5 is the partial enlarged schematic diagram illustrating the partial structure of high microstructure and low microstructure;

6 is a schematic side view showing a preferred embodiment of the display device of the present invention;

7 is a schematic diagram showing an angle when a user watches a screen and a schematic diagram showing that the viewing surface and the light-emitting surface are perpendicular to each other;

8 is a schematic diagram showing an angle when a user watches a screen and a schematic diagram showing that the viewing surface and the light-emitting surface have an included angle of 45 degrees;

为0度的情况下不同视角的辉度百分比的曲线图；Figure 9 is a diagram illustrating that when θ is 60 degrees,

The graph of the percentage of brightness of different viewing angles when it is 0 degrees;

为45度的情况下不同视角的辉度百分比的曲线图；Fig. 10 is an illustration of the case where θ is 60 degrees,

The graph of the percentage of brightness of different viewing angles under the condition of 45 degrees;

11 is a schematic perspective view illustrating another form of the optical film;

FIG. 12 is a schematic side view to assist in explaining FIG. 11; and

FIG. 13 is a graph illustrating a change in the ratio of high microstructure to low microstructure in the optical sheet of FIG. 11 .

Detailed ways

The features and technical contents of the relevant patent applications of the present invention will be clearly presented in the following detailed description of the preferred embodiments with reference to the accompanying drawings. Before going into detail, it should be noted that similar elements are denoted by the same reference numerals.

Referring to FIG. 1 , it is a preferred embodiment of the backlight module of the present invention, which includes a light source 2 , an optical plate 3 for receiving the light source 2 , a film group 4 disposed on the optical plate 3 , and a film group 4 disposed on the optical plate 3 . on the optical film 5. Wherein, the film set 4 may include a brightness enhancement film, a prism sheet and a diffusing sheet, but is not limited thereto. In this embodiment, the backlight module is a direct type backlight module, so the light source 2 includes a plurality of light emitting diodes (LEDs), which are arranged in an array under the bottom surface of the optical plate 3, and the optical plate 3 is a diffuser plate, The light emitted by the LEDs arranged in an array is diffused through the optical composite material of the diffuser plate itself, so as to generate a surface light source with uniform brightness distribution. In other embodiments, the backlight module can also be designed as an edge-type backlight module, so the light source 2 includes a plurality of light emitting diodes (LEDs), which are arranged at the side of the optical plate 3 in a linear manner, and the optical plate 3 It is a light guide plate, so that the light emitted by the LED enters the light guide plate through the side of the light guide plate, and then through the special structure of the light guide plate, the total reflection path of the light in the light guide plate is destroyed to produce a surface light source with uniform brightness distribution.

Referring to FIG. 2 and FIG. 3 , the optical film 5 includes a light incident side 51 and a light exit side 52 opposite to the light incident side 51 . Since the optical film 5 is located above the optical plate 3 , the light-incident side 51 of the optical film 5 faces downward and faces the top surface (ie, the light-emitting surface) of the optical plate 3 , and the light-emitting side 52 of the optical film 5 faces upward. . The optical film 5 can be divided into a middle region 53 and two side regions 54 respectively located on both sides of the middle region 53 along the direction of the X-axis. Wherein, a plurality of strip-shaped structures 55 in a protruding shape are arranged on the light-emitting side 52 of each side region 54 . The plurality of strip-like structures 55 are arranged along the direction of the X-axis, and each of the strip-like structures 55 extends along the direction of the Y-axis perpendicular to the X-axis, and each The height of the low microstructures 552 is lower than that of the high microstructures 551 . It should be noted that the strip structures 55 are closely arranged with no gaps between them.

In addition, in this embodiment, the number of high microstructures 551 in each side region 54 will not exceed the number of low microstructures 552 at most, and the light-emitting side 52 of the middle region 53 of the optical film 5 is also arranged to protrude A plurality of strip-shaped structures 55 are formed in the middle region 53 , and the strip-shaped structures 55 in the middle region 53 include a small number of high microstructures 551 and a large number of low microstructures 552 arranged repeatedly. That is to say, no matter in the middle region 53 or the side region 54 , the number of the high microstructures 551 will not exceed the number of the low microstructures 552 at most.

It should be noted that, in this embodiment, the high microstructures 551 and the low microstructures 552 are both arc-shaped protruding strip-like structures, and the ratio of the number of the high microstructures 551 to the low microstructures 552 is along the center of the middle area 53 . The direction of the X-axis increases toward the side regions 54 on both sides. The ratio of the numbers of high microstructures 551 to low microstructures 552 is equal to 1 at the extreme end of each side region 54 away from the middle region 53 along the X-axis. That is to say, in the middle area 53, a plurality of low microstructures 552 are repeatedly arranged, and two high microstructures 551 are arranged on both sides of the low microstructures 552 respectively. 54 gradually decreased. Taking FIG. 2 and FIG. 3 as an example, at the center of the middle area 53, a plurality of low-microstructures 552 are repeatedly arranged, and then a high-microstructure 551 is arranged on both sides of the plurality of low-microstructures 552, and then continues to be arranged on both sides respectively. There are four low microstructures 552 and one high microstructure 551 , and three low microstructures 552 and one high microstructure 551 are arranged further toward the two sides respectively. The repeating number of the low microstructures 552 is from the middle area 53 to the side areas 54 on both sides. Gradually decrease until the repetitions of the high microstructure 551 and the low microstructure 552 are the same, so that the ratio between the two is equal to 1. Therefore, as shown in FIG. 4 , the ratio of the high microstructure 551 to the low microstructure 552 gradually increases from less than 1 to equal to 1.

Next, the level relationship between the high microstructure 551 and the low microstructure 552 will be described in detail. Referring to FIG. 5, define a center line L perpendicular to the vertex of any low microstructure 552 and a tangent T passing through the vertex and tangent to the adjacent high microstructure 551, the angle between the center line L and the tangent T For example, it is an acute angle of 60 degrees or more. In this embodiment, 60 degrees are taken as an example for description. Through the above structural design, when the light exits through the low microstructure 552, the light with a light exit angle greater than 60 degrees will be refracted again into the optical film 5 through the adjacent high microstructure 551, thereby reducing the chance of direct light exit, thereby reducing large The amount of light (brightness) emitted in the angular area. In other embodiments, the acute angle between the center line L and the tangent line T can be designed to be other angles, such as 70 degrees, so that the light with a light exit angle greater than 70 degrees when exiting through the low microstructure 552 can pass through the adjacent high The microstructures 551 are refracted into the optical film 5 again.

Referring to FIG. 3 and FIG. 5 , according to this preferred embodiment, when a small number of high microstructures 551 and a large number of low microstructures 552 are provided in each side region 54 , light can be emitted from a large angle through a part of the low microstructures 552 The light ray is refracted into the optical film 5 through the adjacent high microstructure 551 . Since the two side regions 54 are prone to light leakage, a low microstructure 552 and a high microstructure 551 are designed at the extreme end of the side region 54, that is, the ratio of the number of the high microstructures 551 to the low microstructures 552 is equal to 1. In this way, the light that exits at a large angle through each low microstructure 552 can be refracted into the optical film 5 to reduce the chance of direct exit. Therefore, the case where the ratio of the number of the high microstructures 551 to the low microstructures 552 is equal to 1 is most suitable for application in the two side regions 54 that are prone to light leakage.

The backlight module of the present invention, together with the display panel 6 , forms the display device as shown in FIG. 6 .

在图7中，

为0度，而在图8中，

为45度，用以仿真用户实际观看屏幕的四个角落或其他边缘时的合理角度范围。图9及图10说明对应于图7及图8所检测到的辉度百分比，实线代表未使用本实用新型的光学膜片5，而虚线则代表使用了本实用新型的光学膜片5。Next, the influence of using the optical film 5 of the present invention on light emitted from a large angle will be described. Referring to FIG. 7 , the plane A represents the light-emitting surface of the display device, that is, the viewing surface of the user when using the display device, while the plane B is perpendicular to the plane A and is set to be when the user is facing the center C of the plane A. , the viewing angle θ of the eye viewing center C is 0 degrees. The X axis is defined as the horizontal direction in which the user views the display device, and the Y axis is defined as the vertical direction in which the user views the display device. In addition, the angle between the plane B and the horizontal plane is defined as

In Figure 7,

is 0 degrees, while in Figure 8,

It is 45 degrees, which is used to simulate the reasonable angle range when the user actually watches the four corners or other edges of the screen. 9 and FIG. 10 illustrate the luminance percentages detected corresponding to FIGS. 7 and 8 , the solid line represents the optical film 5 not using the present invention, and the dotted line represents the optical film 5 using the present invention.

为0度时及图10的

为45度时，在正60度与正90度之间以及负60度与负90度之间的两个视角的大角度区域中，可以观察到实线部分(未使用本实用新型的光学膜片5)存在着较明显的辉度区域(图9为30％-40％，图10为20％-30％)，这意味着视角在大角度时存在漏光现象，而虚线部分(使用了本实用新型的光学膜片5)将辉度下降到20％以下，这意味着视角在大角度时的漏光现象已经获得改善。It can be seen from the detection results shown in FIG. 9 and FIG. 10 that when the optical film 5 of the present invention is used, the light emitted from a large angle will be refracted by the adjacent high microstructures 551 (see FIG. 5 ). And reduce the chance of direct light emission, so it can reduce the brightness of the area with a viewing angle of more than 60 degrees, which can effectively reduce the light leakage of the area with a viewing angle of more than 60 degrees, thereby reducing the occurrence of white fog on both sides of the display device. Improves contrast in areas with viewing angles of 60 degrees or more. in Figure 9

is 0 degrees and the

When it is 45 degrees, in the large-angle area of the two viewing angles between plus 60 degrees and plus 90 degrees and between minus 60 degrees and minus 90 degrees, the solid line part (without using the optical film of the present invention) can be observed. Sheet 5) has a relatively obvious luminance area (30%-40% in Figure 9, 20%-30% in Figure 10), which means that the viewing angle has light leakage at large angles, and the dotted line part (using this The optical film 5) of the utility model reduces the brightness to less than 20%, which means that the light leakage phenomenon when the viewing angle is at a large angle has been improved.

Referring to FIG. 3 and FIG. 5 , according to the present preferred embodiment, when a small number of high microstructures 551 and a large number of low microstructures 552 are provided in each side region 54 , a part of the low microstructures 552 can emit light at a large angle The light can be refracted into the optical film 5 through the adjacent high microstructure 551 . Since the light leakage phenomenon in the two side areas 54 with larger viewing angles is more obvious than that in the middle area 53, the light emitted by the large angle of the side area 54 is likely to exceed the viewing range of the user, and the large angle of light emitted by the middle area 53 is likely to exceed the viewing range of the user. The light is still within the viewing range of the user, so the method adopted in this preferred embodiment allows a large angle of light in the middle area 53, which can minimize the number of high microstructures 551 in the middle area 53, and only need to solve the two sides For the problem of large-angle light emission from the edge region 54, the number of high microstructures 551 is gradually increased from the middle region 53 to the direction of the two side regions 54, so as to make the low microstructures 552 in the two side regions 54 larger. The angularly emitted light rays are refracted into the optical film 5 through the adjacent high microstructures 551 , thereby reducing the chance of direct emitting light.

Referring to FIGS. 11 and 12 , an optical film 5 with another form different from FIG. 2 is disclosed. The optical film 5 has a high microstructure 551 and a low microstructure 552 no matter in the middle area 53 or the side area 54 . The same number is staggered, that is, the staggered arrangement is repeated in a high and a low manner. If it is required that the light emitting from each low-microstructure 552 at a large angle can be refracted into the optical film 5, this design scheme of repeatedly arranging a low-microstructure 552 adjacent to a high-microstructure 551 can be adopted, that is, a high-microstructure The number of structures 551 is at most equal to the number of low microstructures 552 , and does not exceed the number of low microstructures 552 .

That is, as shown in FIG. 13 , the ratio of the numbers of the high microstructures 551 to the low microstructures 552 in the middle region 53 is equal to the number ratio of the high microstructures 551 to the low microstructures 552 in each side region 54 , both of which are equal to 1. In this way, in addition to the effect of refracting the light emitted from a large angle again, the optical film 5 is more convenient and more versatile when the optical film 5 is cut after fabrication.

To sum up, the present invention can refract light with an excessively large angle through the shape and arrangement of the strip-like structures 55 on the optical film 5, thereby improving the problems of large-angle light field and large-angle light leakage, This in turn improves the contrast at large viewing angles.

The above descriptions are only preferred embodiments of the present invention, which should not limit the scope of implementation of the present invention. That is, any simple equivalent changes and modifications made according to the scope of the claims of the present invention and the contents of the description are still within the scope of the patent of the present invention.

【List of reference numerals】

2 light sources

3 Optical board

4 Diaphragm set

5 Optical film

51 Light incident side

52 Light output side

53 Middle Zone

54 Side Area

55 strips

551 High microstructure

552 Low microstructure

6 Display panel

L center line

T Tangent

theta angle

角度。

angle.

Claims (10)

1. An optical film, characterized in that it comprises a light incident side and a light exit side opposite to the light incident side, the optical film is divided into a middle area along the direction of the X axis and is located in the middle area respectively Two side areas on both sides of the area, wherein, the light-emitting side of each side area is arranged with a plurality of strip-shaped structures in a protruding shape, and a plurality of the strip-shaped structures are arranged along the X-axis. direction, and each of the strip-like structures extends along the direction of the Y-axis perpendicular to the X-axis, and each of the strip-like structures includes a repeating arrangement of high microstructures and a height lower than the high microstructures. low microstructure. 2 . The optical film according to claim 1 , wherein the ratio of the number of the high microstructures to the low microstructures is away from the said side region along the X-axis. 3 . The extreme end of the middle zone is equal to 1. 3 . The optical film according to claim 2 , wherein a plurality of the strip-shaped structures in a protruding shape are arranged on the light-emitting side of the middle area of the optical film, and the middle area Each of the strip-like structures within includes the high microstructures which are repeatedly arranged and the low microstructures whose height is lower than that of the high microstructures. 4 . The optical film of claim 3 , wherein the ratio of the numbers of the high microstructures to the low microstructures located in the intermediate region is equal to the ratio of the high microstructures to the low microstructures in each The ratio of the quantities in the above-mentioned side regions, both of which are equal to 1. 5 . The optical film according to claim 3 , wherein the ratio of the number of the high microstructure to the low microstructure is from the center of the middle area to the side along the direction of the X-axis. 6 . area is increasing. 6 . The optical film of claim 1 , wherein the number of the high microstructures in each of the side regions does not exceed the number of the low microstructures at most. 7 . 7 . The optical film according to claim 1 , wherein a center line perpendicular to the vertex of any one of the low microstructures is defined, and a center line passing through the vertex and in phase with the adjacent high microstructures is defined. 8 . For the tangent of the cut, the acute angle between the center line and the tangent is greater than or equal to 60 degrees. 8 . The optical film of claim 1 , wherein a plurality of the strip-like structures are closely arranged. 9 . 9. A backlight module, characterized in that it comprises a light source, an optical plate for receiving the light source, a film set disposed on the optical plate, and a film set according to claim 1 disposed on the film set The optical film of any one of to 8. 10. A display device, characterized by comprising the backlight module according to claim 9 and a display panel disposed on the backlight module, wherein the X-axis is defined as the time when a user views the display panel. In the horizontal direction, the Y-axis is defined as the vertical direction in which the user views the display panel.

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