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

Abstract

An optical film (100), an optical film group (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) has a first optical surface (111) and a second optical surface (112) that are opposite to each other. The first prism structure (120) is arranged on the first optical surface (111). Each first prism structure (120) has a first extension direction (D1). The second prism structure (130) is arranged 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 expand the viewing angle.

Description

Technical Field

[0001] The present disclosure relates to an optical film and its application, and in particular to an optical film and an optical film assembly capable of generating a larger light output viewing angle, and a backlight module and a display device using the optical film and the optical film assembly. Background Art

[0002] The European Union defines automotive displays, which take into account the viewing angles of the driver and co-driver, and therefore has set viewing angle specifications (Deutsches Flachdisplay Forum). Therefore, current automotive product specifications are designed with reference to this specification.

[0003] The prism used in the current backlight module is mainly used to focus the light in the direction of the normal viewing angle. However, since the car display is installed below the line of sight, and the center console (CID) needs to be designed to be visible to both the driver and the front passenger. Therefore, the viewing angle specification is biased upward (the upper viewing angle is within 20 degrees, and the lower viewing angle is within 15 degrees), and the left and right viewing angles are relatively wide (the left and right viewing angles are within 50 degrees), which is very different from the viewing angle requirements of general tablet computers or laptops.

[0004] Generally speaking, although the viewing angle can be reduced by using a privacy film, the energy consumption of the privacy film is quite large. If the brightness at a large viewing angle can only be achieved by increasing the overall brightness, there is a problem of power consumption. Therefore, how to develop an optical film that, when applied to a display device, meets the specific viewing angle and brightness and can achieve the purpose of power saving is the motivation for this application. Summary of the invention

[0005] Therefore, an object of the present disclosure is to provide an optical film and an optical film assembly, which can be used in a backlight module and a display device to meet a specific viewing angle.

[0006] According to the above-mentioned purpose of the present disclosure, an optical film is provided. The optical film comprises 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 structure is arranged on the first optical surface, wherein each of the first prism structures has a first extension direction. The second prism structure is arranged on the second optical surface, wherein each of the second prism structures has a second extension direction. The first extension direction is different from the second extension direction.

[0007] According to an embodiment of the present disclosure, the first prism structure has an arrangement density Y, and each first prism structure has a first side surface and a second side surface connected to each other, and an angle X is formed between the first side surface and the second side surface, wherein the arrangement density Y and the angle X satisfy a relationship, and the relationship is Y≥0.441+0.01249X-3.2875*10 -4 X 2 +1.95833*10 -6 X 3 .

[0008] According to an embodiment of the present disclosure, there are blank spaces between the 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 Among them, P 1 is the distance between any two adjacent first prism structures, W 1 The width of each blank space.

[0009] According to an embodiment of the present disclosure, each of the first prism structures is a strip-shaped structure that is concave or convex from the first optical surface.

[0010] According to an embodiment of the present disclosure, the angle between the first extension direction and the second extension direction is 90 degrees.

[0011] 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 after the light is emitted from the other of the first optical surface and the second optical surface, a portion of the light is emitted along the front view direction, and a portion of the light is emitted along the side view direction. The ratio of the light emission amount emitted from the side view direction to the light emission amount emitted from the front view direction is greater than 0.4, including the end value.

[0012] According to an embodiment of the present disclosure, the front viewing direction is parallel to the light emitting normal line of the optical film, and the angle between the side viewing direction and the light emitting normal line is greater than 40 degrees, including the end value.

[0013] According to the above-mentioned purpose of the present disclosure, a backlight module is also proposed. The backlight module includes a light guide plate, a light source, the above-mentioned optical film and a film group. The light guide plate has a light incident surface and a light emitting surface. The light source is adjacent to the light incident surface. The optical film is arranged in front of the light emitting surface. The film group is located between the optical film and the light guide plate.

[0014] According to the above-mentioned purpose of the present disclosure, a backlight module is provided. 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.

[0015] According to the above-mentioned purpose of the present disclosure, a display device is provided. The display device comprises the above-mentioned backlight module and a display panel. The display panel is arranged in front of the backlight module.

[0016] According to the above-mentioned 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 structure is arranged on the first optical surface, and each first prism structure has a first extension 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 face opposite directions respectively, the second prism structure is arranged on the second optical surface, and each second prism structure has a second extension direction. The first extension direction is different from the second extension direction.

[0017] According to an embodiment of the present disclosure, the first prism structure has an arrangement density Y, and each first prism structure has a first side surface and a second side surface connected to each other, and an angle X is formed between the first side surface and the second side surface, wherein the arrangement density Y and the angle X satisfy a relationship, which is Y≥0.441+0.01249X-3.2875*10 -4 X 2 +1.95833*10 -6 X 3 .

[0018] 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, W 1 The width of each blank space.

[0019] According to an embodiment of the present disclosure, each of the first prism structures is a strip-shaped structure that is concave or convex from the first optical surface.

[0020] According to an embodiment of the present disclosure, the angle between the first extension direction and the second extension direction is 90 degrees.

[0021] According to one embodiment of the present disclosure, when 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 portion of the light exits along the front viewing direction and a portion of the light exits along the side viewing direction, wherein the ratio of the light output from the side viewing direction to the light output from the front viewing direction is greater than 0.4, including an endpoint value.

[0022] According to an embodiment of the present disclosure, the front-view direction is parallel to the light-emitting normal line of the optical film set, and the angle between the side-view direction and the light-emitting normal line is greater than 40 degrees, including the end value.

[0023] According to the above-mentioned purpose of the present disclosure, a backlight module is also proposed. The backlight module includes a light guide plate, a light source, the above-mentioned optical film group and a film group. The light guide plate has a light incident surface and a light emitting 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 film group is located between the optical film and the light guide plate.

[0024] According to the above-mentioned purpose of the present disclosure, a backlight module is provided. The backlight module includes a light source and the above-mentioned optical film set. 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.

[0025] According to the above-mentioned purpose of the present disclosure, a display device is provided. The display device comprises the above-mentioned backlight module and a display panel. The display panel is arranged in front of the backlight module.

[0026] 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, W 1 The width of each blank space.

[0027] As can be seen from the above, the present disclosure mainly uses the first prism structure and the second prism structure design on the optical film or the optical film group to convert part of the straight light into other viewing directions, thereby improving the overall field of view, and does not need to increase the current to improve the overall brightness to meet the specific field of view angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] For a more complete understanding of the embodiments and their advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0029] Figure 1 is a schematic diagram illustrating an optical film applied to a direct-lit backlight module according to an embodiment of the present disclosure;

[0030] Figure 2 is a partial schematic diagram illustrating an optical film according to an embodiment of the present disclosure;

[0031] Figure 3 is a schematic diagram illustrating the conventional viewing angle specification of a vehicle display defined by the European Union;

[0032] Figure 4is a graph showing the relationship between the angle (X) and the arrangement density (Y) of a first prism structure according to one embodiment of the present disclosure;

[0033] Figure 5 A schematic diagram showing the ratio of the side-view light output amount to the front-view light output amount generated by an optical film having first prism structures with different angles and different arrangement densities according to one embodiment of the present disclosure;

[0034] Fig. 6A A schematic diagram of the light output brightness simulation at various viewing angles of a conventional optical film;

[0035] Figure 6B A schematic diagram of light output brightness simulation at various viewing angles of an optical film with a first prism structure according to an embodiment of the present disclosure;

[0036] Figure 7 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 according to a comparative example;

[0037] Figure 8 is a schematic diagram illustrating an optical film applied to a direct-lit backlight module according to an embodiment of the present disclosure;

[0038] Fig. 9 is a schematic diagram illustrating an optical film applied to an edge-lit backlight module according to an embodiment of the present disclosure;

[0039] Fig.10 is a schematic diagram of a display device according to an embodiment of the present disclosure;

[0040] Fig.11 is a schematic diagram illustrating an optical film assembly applied to a direct-lit backlight module according to an embodiment of the present disclosure;

[0041] Fig.12 is a partial schematic diagram illustrating an optical film assembly according to an embodiment of the present disclosure;

[0042] Fig.13 is a schematic diagram illustrating an optical film assembly applied to an edge-lit backlight module according to an embodiment of the present disclosure; and

[0043] Fig.14 FIG. 4 is a schematic diagram of a display device according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0044] Please refer to Figure 1 , which is a schematic diagram showing an optical film according to an embodiment of the present disclosure being applied to a direct-lit backlight module. The optical film 100 of this embodiment can be mainly applied to Figure 1 and Figure 8 The direct-lit backlight modules 200 and 500 shown in the figure, or applied to Fig. 9 In the edge-type backlight module 300 shown, the light output viewing angle of the backlight module 200 or the backlight module 300 is increased. Figure 1 In the backlight module 200 shown, the optical film 100 is disposed in front of the light source 210. The light source 210 includes a substrate 211 and a plurality of light emitting units 212 arrayed on the substrate 211. Thus, the light provided by the light source 210 can directly pass through the optical film 100 and emit light from the optical film 100.

[0045] like Figure 1 As shown, 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. 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. Figure 1 As shown, the first prism structure 120 has a first extension direction D1, and the second prism structure 130 has a second extension direction D2, wherein the first extension direction D1 is different from the second extension direction D2. Thus, when light enters the optical film 100 from the first optical surface 111, the first prism structure 120 can convert part of the straight light into light in other directions, and then the converted light is emitted through the second prism structure 130 on the second optical surface 112. Specifically, Figure 1 As shown, after the light passes through the optical film 100, a part of the light (such as the light L1) can pass through the blank portion S1 between the first prism structure 120 and emit light in the front view direction, and a part of the light (such as the light L2) can pass through the first prism structure 120 and emit light in 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 100, 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 line of the optical film 100, and the angle θ between the side view direction and the light emitting normal line is greater than 40 degrees, including the endpoint value. In this way, the optical film 100 of this embodiment can further convert part of the straight light into other viewing directions, adjust the size of the horizontal viewing angle, so as to expand the viewing angle, and can meet the specific viewing angle and brightness without increasing the current to improve the overall brightness, while achieving the purpose of power saving.

[0046] In this embodiment, each first prism structure 120 is a strip-shaped structure protruding from the first optical surface 111. In other embodiments, the first prism structure 120 may also be a strip-shaped structure recessed into the first optical surface 111. In some embodiments, the angle between the first extension direction D1 and the second extension direction D2 is 90 degrees. Figure 2 , Figure 2 1 is a partial schematic diagram of an optical film according to an embodiment of the present disclosure. In one embodiment, each first prism structure 120 has a first side surface 121 and a second side surface 122 connected to each other, and an angle X is formed between the first side surface 121 and the second side surface 122. The first prism structures 120 have an arrangement density, and a spacing P is formed between any two adjacent first prism structures 120. 1 , and the blank portion S1 has a width W 1 The arrangement density is calculated according to the function, where the function is expressed as follows: Y = (P 1 -W 1 ) / P 1 .

[0047] 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, when the ratio of the light output of the optical film 100 from the side view to the light output from the front view is required to be greater than 40%, the design of the first prism structure 120 must satisfy a relationship: This relationship is Y≥0.441+0.01249X-3.2875*10 -4 X 2 +1.95833*10 -6 X 3 .

[0048] Please refer to Figure 3 With Table 1, Figure 3 FIG. 1 is a diagram showing a conventional European Union-defined viewing angle specification for automotive displays. In a European Union-defined viewing angle specification for automotive displays (Deutsches Flachdisplay Forum), the viewing angles of the front and rear passenger seats are taken into consideration, for example Figure 3The region A+, region A and region B shown in the figure stipulate that the ratio of the light output from the side view direction (i.e., the brightness of region B) to the light output from the front view direction (i.e., the brightness of region A+) of the vehicle display should be at least greater than 37.5%. However, this embodiment adopts a higher standard than the viewing angle specification of the vehicle display defined by the European Union, requiring that the ratio of the light output from the side view direction to the light output from the front view direction be greater than or equal to 40% (i.e., greater than 37.5%), so the optical film 100 designed using the relationship of this embodiment can expand the light output viewing angle and meet the brightness regulations of the vehicle display defined by the European Union.

[0049] Table 1 Figure 3 The viewing angle range of each area in the EU viewing angle specification

[0050]

[0051] Please also refer to Figure 4 and Figure 5 ,in Figure 4 is a graph showing the relationship between the angle (X) and the arrangement density (Y) of a first prism structure according to one embodiment of the present disclosure, Figure 5 Schematic diagram of the ratio of the side-view light output to the front-view light output generated by an optical film having first prism structures of different angles and different arrangement densities according to one embodiment of the present disclosure. Figure 4 and Figure 5 It can be seen 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 can be 54%, or the angle X of the first prism structure 120 can be set to 60 degrees and the arrangement density can be 43%, or the angle X of the first prism structure 120 can be set to 90 degrees and the arrangement density can be 33%, or the angle X of the first prism structure 120 can be set to 120 degrees and the arrangement density can be 59%, so as to produce a specific light output viewing angle requirement.

[0052] Please also refer to Fig. 6A and Figure 6B , Fig. 6A is a schematic diagram of the light output brightness simulation at various viewing angles of a conventional optical film, Figure 6B FIG. 1 is a schematic diagram of the light output brightness simulation at each viewing angle of an optical film with a first prism structure according to an embodiment of the present disclosure. Fig. 6A The conventional brightness simulation diagram of the optical film can clearly show Figure 6BThe dark area of ​​the embodiment is separated into two areas, the brightness of the light at the front angle is reduced to reduce the energy loss of the light at the front angle, and the brightness of the side angles of the front and front passenger seats is improved. As for the general prism sheet or the film comparison example that does not meet the relationship, the dark area cannot be separated into two areas, and the purpose of this application cannot be achieved.

[0053] It should be noted that the present disclosure is not limited to the above angles and arrangement densities, and the relationship of the present disclosure can be used to calculate the corresponding angle X and arrangement density of the first prism structure 120 according to the ratio requirement of the light output. For example, Figure 4 The curve in represents the relationship curve 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 angle X of the first prism structure 120 and the arrangement density corresponding to a higher ratio of the side view light output to the front view light output. Taking the point where the angle X is 90 degrees as an example, when the 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 the side view light output to the front view light output is required, the purpose of increasing the ratio of the side view light output to the front view light output can be achieved by increasing the arrangement density of the first prism structure 120 under the same condition that the angle X of the first prism structure 120 is 90 degrees, for example, by setting the arrangement density to be greater than 33%.

[0054] See also Figure 7 , Figure 7 1 is a graph showing the relationship between viewing angle and brightness simulated by using the optical film 100 of one embodiment of the present disclosure and the optical film of the comparative example. The optical film of the comparative example is a general single-sided prism sheet. Figure 7 It can be seen that when light is emitted through a general single-sided prism, the light emission viewing angle range is between -40 degrees and +40 degrees, and the light emission through the optical film 100 of the disclosed embodiment has a higher light emission amount. Although the brightness of the light emitted from the optical film 100 in the positive viewing angle range between -30 degrees and +30 degrees is lower than the brightness of the light emitted from the optical film of the comparative example, the light emission amount at the viewing angle position beyond the range of -40 degrees to +40 degrees is significantly improved, for example, the relative brightness of the viewing angle range between -50 degrees and +50 degrees increases from 0.3 to 0.5. This means that the optical film 100 of the present embodiment can reduce the brightness of the light emitted at the positive viewing angle to reduce the energy loss of the light emitted at the positive viewing angle, and improve the side viewing angle brightness of the front and front passenger seats to meet the use requirements of the vehicle display.

[0055] See also Figure 8 , Figure 81 is a schematic diagram showing 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. Figure 8 In the backlight module 500 shown, 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. Thus, 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 the optical film 100 can be used to form a wide-angle light output.

[0056] See also Fig. 9 , Fig. 9 1 is a schematic diagram illustrating an optical film applied to an edge-entry backlight module according to an embodiment of the present disclosure. The optical film 100 of this embodiment can also be applied to an edge-entry backlight module 300. The backlight module 300 includes a light source 310, a light guide plate 320, a film group 330 and an optical film 100. The light source 310 is disposed adjacent to a light incident surface 321 of the light guide plate 320, and the optical film 100 is disposed in front of a light emitting 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. Thus, 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 group 330 and enter the optical film 100, and form a wide-viewing angle light through the action of the optical film 100.

[0057] See also Fig.10 , which is a schematic diagram of a display device according to an embodiment of the present disclosure. The display device 400 of this embodiment includes Figure 1 The backlight module 200 and the display panel 410 are shown. The display panel 410 is arranged in front of the backlight module 200. Thus, the display device 400 can achieve the purpose of reducing the amount of light emitted from the front view and increasing the amount of light emitted from the side view through the design of the optical film 100 in the backlight module 200, so it will not be repeated here. Figure 1 The backlight module 200 shown in the display device 400 is used for demonstration purposes only and is not intended to limit the present disclosure. Fig. 9 The backlight module 300 shown in the figure can be applied to a display device to produce the same effect of expanding the viewing angle.

[0058] Please refer to Fig.11 , which is a schematic diagram illustrating an optical film set according to an embodiment of the present disclosure applied to a direct-lit backlight module. The optical film set 600 of this embodiment can be mainly applied to Fig.11The direct-type backlight module 700 shown in FIG. Fig.13 In the edge-type backlight module 800 shown, the light output viewing angle of the backlight module 700 or the backlight module 800 is increased. Fig.11 In the backlight module 700 shown, the optical film set 600 is disposed in front of the light source 710. The light source 710 includes a substrate 711 and a plurality of light emitting units 712 arrayed on the substrate 711. Thus, the light provided by the light source 710 can directly pass through the optical film set 600 and emit light from the optical film set 600.

[0059] like Fig.11 As shown, the optical film set 600 of this embodiment includes a first film 610 and a second film 620. The first film 610 has a first optical surface 612 and a plurality of first prism structures 611, and the second film 620 has a second optical surface 622 and a plurality of second prism structures 621. The first prism structure 611 is disposed on the first optical surface 612, and the second prism structure 621 is disposed on the second optical surface 622. Fig.11 As shown, 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. Thus, when light enters the optical film assembly 600 from the first optical surface 612, the first prism structure 611 can convert part of the straight light into light in other directions, and then the converted light is emitted through the second prism structure 621 on the second optical surface 622. Specifically, Fig.11 As shown, after the light passes through the optical film 600, a part of the light (such as the light L1) can pass through the blank portion S2 between the first prism structure 611 and emit light in the front view direction, and a part of the light (such as the light L2) can pass through the first prism structure 611 and emit light in 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 line of the optical film group 600, and the angle θ between the side view direction and the light emitting normal line is greater than 40 degrees, including the endpoint value. In this way, the optical film group 600 of this embodiment can further convert part of the straight light into other viewing directions, adjust the size of the horizontal viewing angle, so as to expand the viewing angle, and can meet the specific viewing angle and brightness without increasing the current to improve the overall brightness, while achieving the purpose of power saving.

[0060] In this embodiment, each first prism structure 611 is a strip-shaped structure protruding from the first optical surface 612. In other embodiments, the first prism structure 611 may also be a strip-shaped structure recessed into the first optical surface 612. In some embodiments, the angle between the first extension direction D1 and the second extension direction D2 is 90 degrees. Fig.12 , Fig.12 FIG. 6 is a partial schematic diagram of an optical film assembly according to an embodiment of the present disclosure. In one embodiment, each first prism structure 611 has a first side surface 611a and a second side surface 611b connected to each other, and an angle X is formed between the first side surface 611a and the second side surface 611b. The first prism structures 611 have an arrangement density Y, and there is a spacing P between any two adjacent first prism structures 611. 1 , and the blank portion S2 has a width W 1 The arrangement density is calculated according to the function, where the function is expressed as follows: Y = (P 1 -W 1 ) / P 1 .

[0061] In this embodiment, when 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, when the ratio of the side view light output to the front view light output of the optical film group 600 is required to be greater than 40%, the design of the first prism structure 611 must satisfy a relationship: This relationship is Y≥0.441+0.01249X-3.2875*10 -4 X 2 +1.95833*10 -6 X 3 .

[0062] See also Fig.13 , Fig.13 1 is a schematic diagram illustrating an optical film group applied to an edge-entry backlight module according to an embodiment of the present disclosure. The optical film group 600 of this embodiment can also be applied to an edge-entry backlight module 800. The backlight module 800 includes a light source 810, a light guide plate 820, a film group 830 and an optical film group 600. The light source 810 is disposed adjacent to a light incident surface 821 of the light guide plate 820, and the optical film 600 is disposed in front of a light emitting 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. Thus, 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 group 830 and enter the optical film group 600, and form a wide-angle light output through the action of the optical film group 600.

[0063] See also Fig.14, which is a schematic diagram of a display device according to another embodiment of the present disclosure. The display device 900 of this embodiment includes Fig.11 The backlight module 700 and the display panel 910 are shown. The display panel 910 is arranged in front of the backlight module 700. Thus, the display device 900 can achieve the purpose of reducing the amount of light emitted from the front view and increasing the amount of light emitted from the side view through the design of the optical film group 600 in the backlight module 700, so it will not be repeated here. Fig.11 The backlight module 700 shown in the display device 900 is used for demonstration purposes only and is not intended to limit the present disclosure. Fig.13 The backlight module 800 shown in the figure can be applied to a display device to produce the same effect of expanding the viewing angle.

[0064] From the above-mentioned embodiments of the present disclosure, it can be known that the present disclosure mainly uses the first prism structure and the second prism structure design on the optical film or the optical film group to convert part of the straight light into other viewing directions, thereby improving the overall field of view, and does not need to increase the current to improve the overall brightness to meet the 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 to meet the viewing angle requirements of different vehicle-mounted display devices.

[0065] [Description of Reference Numerals]

[0066] 100: Optical film

[0067] 110: Ontology

[0068] 111: First optical surface

[0069] 112: Second optical surface

[0070] 120: First prism structure

[0071] 121: First side

[0072] 122: Second side

[0073] 130: Second prism structure

[0074] 200: Backlight module

[0075] 210: Light Source

[0076] 211: Substrate

[0077] 212: Light emitting unit

[0078] 300: Backlight module

[0079] 310: Light Source

[0080] 320: Light guide plate

[0081] 321: Light-entering surface

[0082] 322: Light emitting surface

[0083] 330: Diaphragm group

[0084] 400: Display device

[0085] 410: Display Panel

[0086] 500: Backlight module

[0087] 510: Diffuser

[0088] 520: Diffuser

[0089] 600: Optical film set

[0090] 610: First diaphragm

[0091] 611: First prism structure

[0092] 611a: First side

[0093] 611b: Second side

[0094] 612: First optical surface

[0095] 620: Second diaphragm

[0096] 621: Second prism structure

[0097] 622: Second optical surface

[0098] 700: Backlight module

[0099] 710: Light Source

[0100] 711: Substrate

[0101] 712: Light emitting unit

[0102] 800: Backlight module

[0103] 810: Light Source

[0104] 820: Light guide plate

[0105] 821: Light-entering surface

[0106] 822: Light emitting surface

[0107] 830: Diaphragm Group

[0108] 900: Display device

[0109] 910: Display Panel

[0110] A: Area

[0111] B: Area

[0112] A+: Region

[0113] D1: First extension direction

[0114] D2: Second extension direction

[0115] L1: Light

[0116] L2: Light

[0117] P 1 :spacing

[0118] S1: Blank area

[0119] S2: Blank area

[0120] W 1 :width

[0121] θ: Angle

[0122] X: Angle

Claims

1. An optical film, comprising: A body having 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 extension direction; and A plurality of second prism structures are disposed on the second optical surface, wherein each of the plurality of second prism structures has a second extension direction; wherein the first extension direction is different from the second extension direction, The plurality of first prism structures have an arrangement density Y, and each of the plurality of first prism structures has a first side surface and a second side surface connected to each other, and an angle X is formed between the first side surface and the second side surface, wherein the arrangement density Y and the angle X satisfy a relationship, which is: Y≥0.441+0.01249X-3.2875*10 -4 X 2 +1.95833*10 -6 X 3 , 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=(P1-W1) / P1, wherein P1 is the spacing between any two adjacent first prism structures, W1 is the width of each of the blank portions, When light enters the body from the first optical surface and exits from the second optical surface, part of the light exits along the front viewing direction, and part of the light exits along the side viewing direction. 2 . The optical film as claimed in claim 1 , wherein each of the plurality of first prism structures is a strip structure concave or convex from the first optical surface. 3 . The optical film as claimed in claim 1 , wherein an angle between the first extension direction and the second extension direction is 90 degrees. 4 . The optical film as claimed in claim 1 , wherein a ratio of the light output from the side viewing direction to the light output from the front viewing direction is greater than 0.4, including an end value. 5 . The optical film as claimed in claim 4 , wherein the front-view direction is parallel to a light-emitting normal line of the optical film, and an angle between the side-view direction and the light-emitting normal line is greater than 40 degrees, including an end value.

6. A backlight module, comprising: A light guide plate having a light incident surface and a light emitting surface; a light source disposed adjacent to the light incident surface; The optical film according to any one of claims 1 to 5, arranged in front of the light emitting surface; The film set is located between the optical film and the light guide plate.

7. A backlight module, comprising: A light source comprises 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 5, arranged in front of the light source.

8. A display device, comprising: The backlight module according to claim 6 or claim 7; and The display panel is arranged in front of the backlight module.

9. An optical film set, comprising a first film and a second film, 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 extension 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 face opposite directions respectively, the plurality of second prism structures are disposed on the second optical surface, and each of the plurality of second prism structures has a second extension direction; and wherein the first extension direction is different from the second extension direction, The plurality of first prism structures have an arrangement density Y, and each of the plurality of first prism structures has a first side surface and a second side surface connected to each other, and an angle X is formed between the first side surface and the second side surface, wherein the arrangement density Y and the angle X satisfy a relationship, which is: Y≥0.441+0.01249X-3.2875*10 -4 X 2 +1.95833*10 -6 X 3 , 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=(P1-W1) / P1, wherein P1 is the spacing between any two adjacent first prism structures, W1 is the width of each of the blank portions, When light enters from the first optical surface and exits from the second optical surface, part of the light exits along the front viewing direction, and part of the light exits along the side viewing direction. 10 . The optical film set as claimed in claim 9 , wherein each of the plurality of first prism structures is a strip structure concave or convex from the first optical surface. 11 . The optical film set as claimed in claim 9 , wherein an angle between the first extension direction and the second extension direction is 90 degrees. 12 . The optical film assembly as claimed in claim 9 , wherein a ratio of the light output from the side viewing direction to the light output from the front viewing direction is greater than 0.4, including an end value. 13 . The optical film set as claimed in claim 12 , wherein the front-view direction is parallel to a light-emitting normal line of the optical film set, and an angle between the side-view direction and the light-emitting normal line is greater than 40 degrees, including an end value.

14. A backlight module, comprising: A light guide plate having a light incident surface and a light emitting surface; a light source disposed adjacent to the light incident surface; The optical film assembly according to any one of claims 9 to 13, arranged in front of the light emitting surface; The film set is located between the optical film set and the light guide plate.

15. A backlight module, comprising: A light source comprises a substrate and a plurality of light-emitting units arranged on the substrate; and The optical film assembly according to any one of claims 9 to 13 is arranged in front of the light source.

16. A display device, comprising: The backlight module according to claim 14 or claim 15; and The display panel is arranged in front of the backlight module.

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