WO2023115764A1

WO2023115764A1 - Optical film, optical film set, backlight module, and display device

Info

Publication number: WO2023115764A1
Application number: PCT/CN2022/087502
Authority: WO
Inventors: 陈蔚轩; 戴忠勇; 吴俊毅
Original assignee: 瑞仪(广州)光电子器件有限公司; 瑞仪光电股份有限公司
Priority date: 2021-12-21
Filing date: 2022-04-18
Publication date: 2023-06-29
Also published as: TWI804286B; TW202326028A; TW202331378A; TWI830653B

Abstract

An optical film (100), an optical film set (600), a backlight module (200), and a display device (900). The optical film (100) comprises a body (110), a plurality of first prism structures (120), and a plurality of second prism structures (130). The body (110) is provided with a first optical surface (111) and a second optical surface (112) opposite to each other. The first prism structures (120) are disposed on the first optical surface (111). Each first prism structure (120) has a first extension direction (D1). The second prism structures (130) are disposed on the second optical surface (112). Each second prism structure (130) has a second extension direction (D2). The first extension direction (D1) is different from the second extension direction (D2) so as to increase the viewing angle.

Description

Optical film, optical film group, backlight module and display device

technical field

The present disclosure relates to an optical film and its application, and in particular to an optical film, an optical film group, a backlight module using the optical film and an optical film group, and a display device.

Background technique

The vehicle display defined by the European Union has a viewing angle specification (Deutsches Flachdisplay Forum) in consideration of the viewing angles of the driver and co-driver. Therefore, the current vehicle product specifications are designed with reference to this specification.

At present, the prism sheet used in the backlight module is mainly used to concentrate the light in the direction of the normal viewing angle. However, since the vehicle display is installed below the line of sight, and the center console (Center Informative Display, CID) needs to be designed so that both the driver and the co-driver can watch it. Therefore, the viewing angle specification is on the upper side (upper viewing angle is within 20 degrees, and lower viewing angle is within 15 degrees), and the distribution of left and right viewing angles is relatively wide (left and right viewing angles are within 50 degrees), which is different from ordinary tablet computers or notebook computers. The field of view angle requirements are very different.

Generally speaking, although the viewing angle can be narrowed by using the privacy protection film, the energy loss of the privacy protection film is quite large. If only by increasing the overall luminance, the luminance at large viewing angles can reach the desired value, but there is also the problem of power consumption. Therefore, how to develop an optical film that meets a specific viewing angle and luminance when applied to a display device and can also achieve the purpose of saving power is the motivation of this application.

Contents of the invention

Therefore, an object of the present disclosure is to provide an optical film and an optical film set, which can be used in a backlight module and a display device to meet a specific viewing angle.

According to the above purpose of the present disclosure, an optical film is proposed. The optical film includes a body, a plurality of first prism structures and a plurality of second prism structures. The body has a first optical surface and a second optical surface opposite to each other. The first prism structures are disposed on the first optical surface, wherein each first prism structure has a first extension direction. The second prism structures are disposed on the second optical surface, wherein each second prism structure has a second extending direction. Wherein, the first extending direction is different from the second extending direction.

According to an embodiment of the present disclosure, the above-mentioned first prism structures have an arrangement density Y, and each first prism structure has a first side and a second side connected to each other, and an included angle X exists between the first side and the second side. , wherein the arrangement density Y and the included angle X satisfy a relational expression, the relational expression is Y≥0.441+0.01249X-3.2875*10 ^-4 X ² +1.95833*10 ^-6 X ³ .

According to an embodiment of the present disclosure, there is a blank portion between the above-mentioned first prism structures, and the arrangement density Y is calculated according to a function, wherein the function is Y=(P ₁ −W ₁ )/P ₁ . Wherein, P ₁ is the distance between any two adjacent first prism structures, and W ₁ is the width of each blank portion.

According to an embodiment of the present disclosure, each of the above-mentioned first prism structures is a strip structure concave or convex on the first optical surface.

According to an embodiment of the present disclosure, the included angle between the above-mentioned first extending direction and the second extending direction is 90 degrees.

According to an embodiment of the present disclosure, when a light enters the body from one of the first optical surface and the second optical surface, and the other one of the first optical surface and the second optical surface exits, a part of the light Light is emitted along the front view direction, and part of the light is emitted along the side view direction. Wherein, the ratio of the light output from the side view direction to the light output from the front view direction is greater than 0.4, including the endpoint value.

According to an embodiment of the present disclosure, the above-mentioned front viewing direction is parallel to the light emitting normal of the optical film, and the angle between the side viewing direction and the light emitting normal is greater than 40 degrees, including the endpoint values.

According to the above purpose of the present disclosure, another backlight module is provided. The backlight module includes a light guide plate, a light source, the aforementioned optical film and a film group. The light guide plate has a light incident surface and a light output surface. The light source is adjacent to the light incident surface. The optical film is arranged in front of the light emitting surface. The diaphragm group is located between the optical diaphragm and the light guide plate.

According to the above purpose of the present disclosure, a backlight module is proposed. The backlight module includes a light source and the above-mentioned optical film. The light source includes a substrate and a plurality of light emitting units arranged on the substrate. The optical film is arranged in front of the light source.

According to the above purpose of the present disclosure, a display device is proposed. The display device includes the above-mentioned backlight module and a display panel. The display panel is arranged in front of the backlight module.

According to the above purpose of the present disclosure, an optical film set is proposed. The optical film set includes a first film and a second film. The first film has a first optical surface and a plurality of first prism structures, wherein the first prism structures are disposed on the first optical surface, and each first prism structure has a first extending direction. The second film has a second optical surface and a plurality of second prism structures, wherein the first optical surface and the second optical surface respectively face opposite directions, the second prism structure is arranged on the second optical surface, and each second The prism structure has a second extension direction. Wherein the first extending direction is different from the second extending direction.

According to an embodiment of the present disclosure, there is a blank portion between any two adjacent first prism structures, and the arrangement density Y is calculated according to a function, wherein the function is Y=(P ₁ −W ₁ )/ P ₁ , where P ₁ is the distance between any two adjacent first prism structures, and W ₁ is the width of each blank portion.

According to an embodiment of the present disclosure, when the light enters from one of the first optical surface and the second optical surface and exits from the other of the first optical surface and the second optical surface, a part of the light passes along the Light is emitted in the front view direction, and part of the light is emitted in the side view direction, wherein the ratio of the light output from the side view direction to the light output from the front view direction is greater than 0.4, including the endpoint value.

According to an embodiment of the present disclosure, the front viewing direction is parallel to the light emitting normal of the optical film set, and the angle between the side viewing direction and the light emitting normal is greater than 40 degrees, inclusive.

According to the above purpose of the present disclosure, another backlight module is provided. The backlight module includes a light guide plate, a light source, the above-mentioned optical film set and the film set. The light guide plate has a light incident surface and a light output surface. The light source is adjacent to the light incident surface. The optical film group is arranged in front of the light-emitting surface. The diaphragm group is located between the optical diaphragm and the light guide plate.

According to the above purpose of the present disclosure, a backlight module is proposed. The backlight module includes a light source and the above-mentioned optical film group. The light source includes a substrate and a plurality of light emitting units arranged on the substrate. The optical film is arranged in front of the light source.

From the above, it can be seen that the present disclosure is mainly through the design of the first prism structure and the second prism structure on the optical film or the optical film group, which can convert part of the direct light to other viewing angle directions, so as to improve the overall field of view, without It is necessary to increase the current to increase the overall luminance to meet a specific viewing angle.

Description of drawings

For a more complete understanding of the embodiments and advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram illustrating an application of an optical film in a direct-lit backlight module according to an embodiment of the present disclosure;

FIG. 2 is a partial schematic diagram illustrating an optical film according to an embodiment of the present disclosure;

FIG. 3 is a schematic diagram illustrating the viewing angle specification of a conventional EU-defined vehicle display;

4 is a graph showing the relationship between the included angle (X) and the arrangement density (Y) of a first prism structure according to an embodiment of the present disclosure;

5 is a schematic diagram of the ratio of the side-view light output to the front-view light output produced by optical films with different angles and different arrangement densities of the first prism structure according to an embodiment of the present disclosure;

FIG. 6A is a schematic diagram of a simulation of light output brightness at various viewing angles of a conventional optical film;

FIG. 6B is a schematic diagram of simulated light output brightness at various viewing angles of the optical film of the first prism structure according to an embodiment of the present disclosure;

7 is a graph showing the relationship between viewing angle and brightness simulated by using an optical film according to an embodiment of the present disclosure and an optical film of a comparative example;

FIG. 8 is a schematic diagram illustrating an application of an optical film in a direct-lit backlight module according to an embodiment of the present disclosure;

FIG. 9 is a schematic diagram illustrating an application of an optical film in an edge-lit backlight module according to an embodiment of the present disclosure;

FIG. 10 is a device schematic diagram illustrating a display device according to an embodiment of the present disclosure;

FIG. 11 is a schematic diagram illustrating an optical film set applied to a direct-lit backlight module according to an embodiment of the present disclosure;

12 is a partial schematic diagram illustrating an optical film set according to an embodiment of the present disclosure;

13 is a schematic diagram illustrating an optical film set applied to an edge-lit backlight module according to an embodiment of the present disclosure; and

FIG. 14 is a device schematic diagram illustrating a display device according to another embodiment of the present disclosure.

Detailed ways

Please refer to FIG. 1 , which is a schematic diagram illustrating an application of an optical film in a direct-lit backlight module according to an embodiment of the present disclosure. The optical film 100 of this embodiment can be mainly applied to the direct

type backlight modules

200 and 500 as shown in FIG. 1 and FIG. 8 , or to the side type backlight module 300 as shown in FIG. 9 . To increase the light output viewing angle of the backlight module 200 or the backlight module 300 . In the backlight module 200 shown in FIG. 1 , the optical film 100 is disposed in front of the light source 210 . Wherein, the light source 210 includes a substrate 211 and a plurality of light emitting units 212 arrayed on the substrate 211 . In this way, the light provided by the light source 210 can directly pass through the optical film 100 , and then exit the optical film 100 .

As shown in FIG. 1 , the optical film 100 of this embodiment includes a body 110 , a plurality of first prism structures 120 and a plurality of second prism structures 130 . Wherein, the body 110 has a first optical surface 111 and a second optical surface 112 , the first prism structure 120 is disposed on the first optical surface 111 , and the second prism structure 130 is disposed on the second optical surface 112 . As shown in FIG. 1 , the first prism structure 120 has a first extending direction D1, and the second prism structure 130 has a second extending direction D2, wherein the first extending direction D1 is different from the second extending direction D2. In this way, when light enters the optical film 100 from the first optical surface 111, the first prism structure 120 can turn part of the straight light into light in other directions, and then make the light after turning pass through the light on the second optical surface 112. The second prism structure 130 emits light. Specifically, as shown in FIG. 1, after the light is acted on by the optical film 100, part of the light (such as light L1) can pass through the blank portion S1 between the first prism structures 120 and emit light along the direction of the front view, and part of the light The light (such as the light L2 ) can pass through the action of the first prism structure 120 and emit light along the side view direction. Wherein, the front view direction referred to here refers to the normal direction of light parallel to the optical film 100 , and there is an angle θ between the side view direction and the front view direction, wherein. More specifically, the front viewing direction is parallel to a light emitting normal of the optical film 100 , and the angle θ between the side viewing direction and the light emitting normal is greater than 40 degrees, inclusive. In this way, the optical film 100 of this embodiment can further convert part of the straight light to other viewing directions, adjust the size of the viewing angle in the horizontal direction to expand the viewing angle, and increase the overall brightness without increasing the current. It can meet the specific viewing angle and brightness, and achieve the purpose of saving power at the same time.

In this embodiment, each first prism structure 120 is a strip structure protruding from the first optical surface 111 . In other embodiments, the first prism structure 120 can also be a strip structure concave into the first optical surface 111 . In some embodiments, the included angle between the first extending direction D1 and the second extending direction D2 is 90 degrees. Please also refer to FIG. 2 , which is a partial schematic view of an optical film according to an embodiment of the present disclosure. In one embodiment, each first prism structure 120 has a first side 121 and a second side 122 connected to each other, and an angle X is formed between the first side 121 and the second side 122 . The first prism structures 120 have an arrangement density, and there is a pitch P ₁ between any two adjacent first prism structures 120 , and the blank portion S1 has a width W ₁ . Wherein, the arrangement density is calculated according to the function, wherein the function is expressed as follows: Y=(P ₁ −W ₁ )/P ₁ .

In this embodiment, when the light passes through the optical film 100, the ratio of the light output of the light L2 emitted from the side view direction to the light output of the light L1 emitted from the front view direction is greater than or equal to 0.4, that is, the optical film is required When the ratio of the side view light output to the front view light output of 100 is more than 40%, the design of the first prism structure 120 must satisfy a relational expression: this relational expression is Y≥0.441+0.01249X-3.2875*10 ^-4 X ² +1.95833*10 ^-6 X ³ .

Please refer to FIG. 3 and Table 1. FIG. 3 is a schematic diagram illustrating the viewing angle specification of a conventional EU-defined vehicle display. In an EU-defined viewing angle specification for vehicle displays (Deutsches Flachdisplay Forum), in order to take into account the viewing angles of the front and passenger seats at the same time, such as the area A+, area A, and area B shown in Figure 3, the vehicle display is specified from the side The ratio of the amount of light emitted from the viewing direction (that is, the brightness of area B) to the amount of light emitted from the front viewing direction (that is, the brightness of area A+) should be at least greater than 37.5%. However, this embodiment adopts a higher standard than the standard for the viewing angle of vehicle displays defined by the European Union, requiring that the ratio of the amount of light emitted from the side-view direction to the amount of light emitted from the front-view direction be greater than or equal to 40% (that is, greater than 37.5 %), so the optical film 100 can be designed by using the relational expression of this embodiment to expand the light-emitting viewing angle and comply with the luminance regulations of automotive displays defined by the European Union.

Table 1. Field of view ranges and EU viewing angle specifications for each area in Figure 3

Please also refer to FIG. 4 and FIG. 5 together, wherein FIG. 4 is a graph showing the relationship between the included angle (X) and the arrangement density (Y) of a first prism structure according to an embodiment of the present disclosure, and FIG. 5 It is a schematic diagram of the ratio of side-view light output and front-view light output produced by using optical films with different angles and different arrangement densities of the first prism structure according to an embodiment of the present disclosure. It can be seen from Fig. 4 and Fig. 5 that when the ratio of the side view light output to the front view light output of the optical film 100 is required to be 40%, the angle X of the first prism structure 120 can be set to 40 degrees and the arrangement density is 54 %, or set the angle X of the first prism structure 120 to be 60 degrees and the arrangement density to be 43%, or set the angle X of the first prism structure 120 to be 90 degrees and the arrangement density to be 33%, or set the first prism structure 120 to have an arrangement density of 33%. The included angle X of a prism structure 120 is 120 degrees and the arrangement density is 59%, so as to generate a specific light-emitting viewing angle requirement.

Please refer to FIG. 6A and FIG. 6B at the same time. FIG. 6A is a schematic diagram of the light output brightness simulation at each viewing angle of a conventional optical film, and FIG. 6B is a light output at each viewing angle of an optical film with a first prism structure according to an embodiment of the present disclosure. Schematic diagram of brightness simulation. Compared with the brightness simulation schematic diagram of the conventional optical film in FIG. 6A, it can be clearly seen that the dark area of the embodiment in FIG. To improve the brightness of the side viewing angle of the front and passenger seats, as for the general prism sheet or the film comparison example that does not meet the relational formula, it is impossible to separate the dark area into two areas, and the purpose of this application cannot be achieved.

It should be noted that the present disclosure is not limited to the above-mentioned angle and arrangement density, and the corresponding included angle X and arrangement density of the first prism structure 120 can be calculated according to the ratio requirement of light output by using the relational formula of the present disclosure. For example, the curve in FIG. 4 represents the relationship between the angle X of the first prism structure 120 and the arrangement density when the ratio of the side-view light output to the front-view light output of the optical film 100 is equal to 40%. The range above this curve represents the relationship between the included angle X of the first prism structure 120 and the arrangement density corresponding to a higher ratio of side-view light output to front-view light output. Taking the point where the included angle X is 90 degrees as an example, when the included angle X of the first prism structure 120 is 90 degrees, the arrangement density is 33%, and the ratio of the side view light output to the front view light output is 40%. When a higher ratio of side-view light output to front-view light output is required, the arrangement density of the first prism structure 120 can be increased by increasing the arrangement density of the first prism structure 120 under the same condition that the included angle X of the first prism structure 120 is 90 degrees, for example Setting the arrangement density to be greater than 33% can achieve the purpose of increasing the ratio of the light output from the side view to the light output from the front view.

Please also refer to FIG. 7 , which is a graph showing the relationship between viewing angle and brightness simulated by using the optical film 100 of an embodiment of the present disclosure and the optical film of a comparative example respectively. Wherein, the optical film of the comparative example is a general single-sided prism film. It can be seen from FIG. 7 that when the light exits through a general single-sided prism sheet, the light exit angle ranges from -40 degrees to +40 degrees and has a relatively high light output; while the light exits through the optical film 100 of the embodiment of the present disclosure Finally, although the brightness from the optical film 100 at the front viewing angle range of -30 degrees to +30 is lower than that of the optical film of the comparative example, it is more than -40 degrees to +40 degrees. The amount of light output at viewing angle positions outside the range is significantly increased, for example, the relative brightness of the viewing angle range of -50 degrees and +50 degrees increases from 0.3 to 0.5. This means that the optical film 100 of this embodiment can reduce the brightness of the light output at the front viewing angle to reduce the energy consumption of the light output at the front viewing angle, and increase the brightness at the side viewing angle of the front and passenger seats to meet the use requirements of the vehicle display.

Please also refer to FIG. 8 . FIG. 8 is a schematic diagram illustrating an optical film applied to a direct-lit backlight module according to an embodiment of the present disclosure. The backlight module 500 of this embodiment includes a light source 210 , a diffusion film 510 , a diffusion plate 520 and an optical film 100 . In the backlight module 500 shown in FIG. 8 , the optical film 100 is disposed in front of the light source 210 . The diffusion film 510 and the diffusion plate 520 are disposed between the light source 210 and the optical film 100 . In this way, the light provided by the light source 210 can pass through the diffusion film 510 and the diffusion plate 520 , and then enter the optical film 100 , and form a wide viewing angle through the optical film 100 .

Please also refer to FIG. 9 . FIG. 9 is a schematic diagram illustrating an application of an optical film in an edge-lit backlight module according to an embodiment of the present disclosure. The optical film 100 of this embodiment can also be applied in the side-lit backlight module 300 . Wherein, the backlight module 300 includes a light source 310 , a light guide plate 320 , a film set 330 and an optical film 100 . Wherein, the light source 310 is disposed adjacent to the light incident surface 321 of the light guide plate 320 , and the optical film 100 is disposed in front of the light exit surface 322 of the light guide plate 320 . The film group 330 is disposed between the light guide plate 320 and the optical film 100 . In this way, the light provided by the light source 310 can enter the light guide plate 320 to form a surface light source, and then pass through the film set 330 and then enter the optical film 100 to form a wide viewing angle light output through the optical film 100 .

Please also refer to FIG. 10 , which is a device diagram illustrating a display device according to an embodiment of the present disclosure. The display device 400 of this embodiment includes a backlight module 200 and a display panel 410 as shown in FIG. 1 . The display panel 410 is disposed in front of the backlight module 200 . Thereby, through the design of the optical film 100 in the backlight module 200 , the display device 400 also achieves the purpose of reducing the light output at the front viewing angle and increasing the light output at the side viewing angle, so details will not be repeated here. Wherein, in this embodiment, the application of the backlight module 200 shown in FIG. 1 in the display device 400 is only used for demonstration purposes, and is not intended to limit the present disclosure. The backlight modules of other embodiments (for example, the backlight module 300 shown in FIG. 9 ) can be applied to a display device to produce the same effect of expanding the viewing angle.

Please refer to FIG. 11 , which is a schematic diagram illustrating an optical film set applied to a direct-lit backlight module according to an embodiment of the present disclosure. The optical film set 600 of this embodiment can be mainly applied to the direct-type backlight module 700 as shown in FIG. 11 , or to the side-type backlight module 800 as shown in FIG. The light emitting angle of the group 700 or the backlight module 800 . In the backlight module 700 shown in FIG. 11 , the optical film set 600 is disposed in front of the light source 710 . Wherein, the light source 710 includes a substrate 711 and a plurality of light emitting units 712 arrayed on the substrate 711 . In this way, the light provided by the light source 710 can directly pass through the optical film set 600 , and then exit the optical film set 600 .

As shown in FIG. 11 , the optical film set 600 of this embodiment includes a first film 610 and a second film 620 . Wherein, the first film 610 has a first optical surface 612 and a plurality of first prism structures 611, the second film 620 has a second optical surface 622 and a plurality of second prism structures 621, and the first prism structures 611 are arranged at the second On an optical surface 612 , and the second prism structure 621 is disposed on the second optical surface 622 . As shown in FIG. 11 , the first prism structure 611 has a first extension direction D1, and the second prism structure 621 has a second extension direction D2, wherein the first extension direction D1 is different from the second extension direction D2. In this way, when light enters the optical film set 600 from the first optical surface 612, the first prism structure 611 can turn part of the straight light into light in other directions, and then make the light after turning pass through the second optical surface 622. The second prism structure 621 emits light. Specifically, as shown in FIG. 11 , after the light passes through the optical film 600, a part of the light (such as light L1) can pass through the blank portion S2 between the first prism structures 611 and emit light along the front view direction, and a part of the light The light (such as the light L2 ) can pass through the action of the first prism structure 611 and emit light along the side view direction. Wherein, the front view direction referred to here refers to the direction in which the light is parallel to the normal line of the optical film group 600 , and there is an angle θ between the side view direction and the front view direction, wherein. In more detail, the front view direction is parallel to a light emitting normal of the optical film set 600 , and the angle θ between the side viewing direction and the light emitting normal is greater than 40 degrees, inclusive. In this way, the optical film set 600 of this embodiment can further convert part of the straight light to other viewing directions, adjust the size of the viewing angle in the horizontal direction to expand the viewing angle, and increase the overall brightness without increasing the current. It can meet the specific viewing angle and luminance, and at the same time achieve the purpose of saving power.

In this embodiment, each first prism structure 611 is a strip structure protruding from the first optical surface 612 . In other embodiments, the first prism structure 611 can also be a strip structure concave into the first optical surface 612 . In some embodiments, the included angle between the first extending direction D1 and the second extending direction D2 is 90 degrees. Please also refer to FIG. 12 . FIG. 12 is a partial schematic view of an optical film set according to an embodiment of the present disclosure. In one embodiment, each first prism structure 611 has a first side 611 a and a second side 611 b connected to each other, and an angle X is formed between the first side 611 a and the second side 611 b. The first prism structures 611 have an arrangement density Y, and there is a pitch P ₁ between any two adjacent first prism structures 611 , and the blank portion S2 has a width W ₁ . Wherein, the arrangement density is calculated according to the function, wherein the function is expressed as follows: Y=(P ₁ −W ₁ )/P ₁ .

In this embodiment, after the light passes through the optical film group 600, the ratio of the light output of the light L2 emitted from the side view direction to the light output of the light L1 emitted from the front view direction is greater than or equal to 0.4, that is, the optical film is required. When the ratio of the side view light output to the front view light output of the sheet group 600 is more than 40%, the design of the first prism structure 611 must satisfy a relation: Y≥0.441+0.01249X-3.2875*10 ^-4 X ² +1.95833*10 ^-6 X ³ .

Please also refer to FIG. 13 . FIG. 13 is a schematic diagram illustrating an optical film set applied to an edge-lit backlight module according to an embodiment of the present disclosure. The optical film set 600 of this embodiment can also be applied in the side-lit backlight module 800 . Wherein, the backlight module 800 includes a light source 810 , a light guide plate 820 , a film set 830 and an optical film set 600 . Wherein, the light source 810 is disposed adjacent to the light incident surface 821 of the light guide plate 820 , and the optical film 600 is disposed in front of the light exit surface 822 of the light guide plate 820 . The film group 830 is disposed between the light guide plate 820 and the optical film 600 . In this way, the light provided by the light source 810 can enter the light guide plate 820 to form a surface light source, and then pass through the film set 830 and then enter the optical film set 600 to form a wide viewing angle light output through the optical film set 600 .

Please also refer to FIG. 14 , which is a device diagram illustrating a display device according to another embodiment of the present disclosure. The display device 900 of this embodiment includes a backlight module 700 and a display panel 910 as shown in FIG. 11 . The display panel 910 is disposed in front of the backlight module 700 . In this way, the design of the optical film set 600 in the backlight module 700 of the display device 900 also achieves the purpose of reducing the light output at the front viewing angle and increasing the light output at the side viewing angle, so details will not be repeated here. Wherein, in this embodiment, the application of the backlight module 700 shown in FIG. 11 in the display device 900 is only used for demonstration purposes, and is not intended to limit the present disclosure. The backlight modules of other embodiments mentioned above (for example, the backlight module 800 shown in FIG. 13 ) can be applied to a display device to produce the same effect of expanding the viewing angle.

It can be seen from the above embodiments of the present disclosure that the present disclosure is mainly through the design of the first prism structure and the second prism structure on the optical film or the optical film group, which can convert part of the direct light to other viewing angle directions, so as to improve the overall Field of view, no need to increase the current to improve the overall brightness, it can meet a specific viewing angle. On the other hand, the relationship formula disclosed in the present disclosure can also be used to design the angle change and arrangement density of the first prism structure and the second prism structure, so as to meet the viewing angle requirements of different vehicle-mounted display devices.

[Description of Reference Signs]

100: optical film

110: Ontology

111: first optical surface

112: second optical surface

120: The first prism structure

121: First Side

122: second side

130: Second prism structure

200: Backlight module

210: light source

211: Substrate

212: Lighting unit

300: backlight module

310: light source

320: light guide plate

321: light incident surface

322: light emitting surface

330: Diaphragm group

400: display device

410: display panel

500: backlight module

510: Diffusion film

520: Diffusion plate

600: Optical film set

610: First Diaphragm

611: The first prism structure

611a: first side

611b: second side

612: first optical surface

620: second diaphragm

621: Second prism structure

622: second optical surface

700: backlight module

710: light source

711: Substrate

712: Lighting unit

800: Backlight module

810: light source

820: light guide plate

821: light incident surface

822: light emitting surface

830: Diaphragm group

900: display device

910: display panel

A: area

B: area

A+: area

D1: first extension direction

D2: Second extension direction

L1: light

L2: light

P ₁ : Pitch

S1: Blank part

S2: Blank part

W ₁ : Width

θ: included angle

X: included angle

Claims

An optical film comprising:

The body has a first optical surface and a second optical surface opposite to each other;

a plurality of first prism structures disposed on the first optical surface, wherein each of the plurality of first prism structures has a first direction of extension; and

a plurality of second prism structures disposed on the second optical surface, wherein each of the plurality of second prism structures has a second extension direction;

Wherein the first extending direction is different from the second extending direction.
The optical film according to claim 1, wherein the plurality of first prism structures has an arrangement density Y, and each of the plurality of first prism structures has a first side and a second side connected to each other , there is an included angle X between the first side and the second side, wherein the arrangement density Y and the included angle X satisfy a relational expression, the relational expression is:

Y≥0.441+0.01249X−3.2875*10 −4 X 2 +1.95833*10 −6 X 3 .
The optical film according to claim 2, wherein there is a blank portion between any two adjacent first prism structures, and the arrangement density Y is calculated according to a function, wherein the function is Y= (P 1 −W 1 )/P 1 , wherein P 1 is the distance between any two adjacent first prism structures, and W 1 is the width of each of the plurality of blank portions.
The optical film as claimed in claim 1, wherein each of the plurality of first prism structures is a strip structure concave or convex on the first optical surface.
The optical film as claimed in claim 1, wherein an included angle between the first extending direction and the second extending direction is 90 degrees.
The optical film according to claim 1, wherein when the light enters the body from one of the first optical surface and the second optical surface, the light from one of the first optical surface and the second optical surface After the other emits light, part of the light emits along the front view direction, and part of the light emits along the side view direction, wherein the ratio of the light output from the side view direction to the light output from the front view direction is greater than 0.4 , containing the endpoint value.
The optical film according to claim 6, wherein the front view direction is parallel to the light exit normal of the optical film, and the angle between the side view direction and the light exit normal is greater than 40 degrees, inclusive.
A backlight module, comprising:

The light guide plate has a light incident surface and a light exit surface;

a light source adjacent to the light incident surface;

The optical film according to any one of claims 1 to 7, arranged in front of the light exit surface;

The film group is located between the optical film and the light guide plate.
A backlight module, comprising:

A light source, including a substrate and a plurality of light emitting units arranged on the substrate; and

The optical film according to any one of claims 1 to 7, arranged in front of the light source.
A display device comprising:

The backlight module according to claim 8 or claim 9; and

The display panel is arranged in front of the backlight module.
An optical diaphragm set, comprising a first diaphragm and a second diaphragm, wherein:

The first film has a first optical surface and a plurality of first prism structures, wherein the plurality of first prism structures are disposed on the first optical surface, and each of the plurality of first prism structures has a first direction of extension;

The second film has a second optical surface and a plurality of second prism structures, wherein the first optical surface and the second optical surface respectively face opposite directions, and the plurality of second prism structures are arranged on the second optical surface. and each of the plurality of second prism structures has a second extension direction; and

Wherein the first extending direction is different from the second extending direction.
The optical film set according to claim 11, wherein the plurality of first prism structures has an arrangement density Y, and each of the plurality of first prism structures has a first side and a second side connected to each other. Side, there is an included angle X between the first side and the second side, wherein the arrangement density Y and the included angle X satisfy a relational expression, the relational expression is:

Y≥0.441+0.01249X−3.2875*10 −4 X 2 +1.95833*10 −6 X 3 .
The optical film set according to claim 12, wherein there is a blank portion between any two adjacent first prism structures, and the arrangement density Y is calculated according to a function, wherein the function is Y =(P 1 −W 1 )/P 1 , where P 1 is the distance between any two adjacent first prism structures, and W 1 is the width of each of the blank portions.
The optical film set as claimed in claim 11, wherein each of the plurality of first prism structures is a strip structure concave or convex on the first optical surface.
The optical film set as claimed in claim 11, wherein an included angle between the first extending direction and the second extending direction is 90 degrees.
The optical film set according to claim 11, wherein when the light enters from one of the first optical surface and the second optical surface, the light enters from the other of the first optical surface and the second optical surface After the light is emitted, part of the light is emitted along the direction of the front view, and part of the light is emitted along the direction of the side view, wherein the ratio of the amount of light emitted from the side view direction to the amount of light emitted from the front view direction is greater than 0.4, including endpoint value.
The optical film set according to claim 16, wherein the front view direction is parallel to the light emitting normal of the optical film set, and the angle between the side view direction and the light emitting normal is greater than 40 degrees, inclusive.
A backlight module, comprising:

The light guide plate has a light incident surface and a light exit surface;

a light source adjacent to the light incident surface;

The optical film group according to any one of claims 11 to 17, arranged in front of the light exit surface;

The film group is located between the optical film group and the light guide plate.
A backlight module, comprising:

A light source, including a substrate and a plurality of light emitting units arranged on the substrate; and

The optical film group as claimed in any one of claims 11 to 17 is arranged in front of the light source.
A display device comprising:

A backlight module according to claim 18 or claim 19; and

The display panel is arranged in front of the backlight module.