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

Abstract

The present invention relates to an optical film (100), an optical film set (600), a backlight module (200), and a display device (900). The optical film (100) 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) facing each other. The first prism structures (120) are disposed on the first optical surface (111). Each of the first prism structures (120) has a first extension direction (D1). The second prism structures (130) are disposed on the second optical surface (112). Each of the second prism structures (130) has a second extension direction (D2). The first extension direction (D1) is different from the second extension direction (D2) 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 that can generate a large exit viewing angle, an optical film set, and a backlight module and a display device using the optical film and the optical film set. [Background technology]

[0002] The European Union has established a viewing angle standard (Deutsches Flachdisplay Forum) for vehicle displays that takes into account the viewing angles of the driver and passenger seats, and all current in-vehicle product standards are designed with reference to this standard.

[0003] Prism sheets currently used in backlight modules are mainly used to concentrate light rays in the direction of the front viewing angle. However, vehicle displays are installed below the line of sight, and the center console (Center Informative Display, CID) needs to be designed so that it can be seen by both the driver and passenger. Therefore, the viewing angle standard is biased upward (upper viewing angle is within 20 degrees, lower viewing angle is within 15 degrees), and the left and right viewing angles are relatively widely distributed (left and right viewing angles are within 50 degrees), which is significantly different from the viewing angle requirements of general tablet computers and notebook computers.

[0004] In general, the viewing angle can be reduced by using an anti-spy sheet, but the energy loss of the anti-spy sheet is quite large. The expected value of brightness at a large viewing angle can be achieved by only increasing the overall brightness, but there is also a problem of power consumption. Therefore, the motivation of the present application is how to develop an optical film and apply it to a display device so as to achieve the purpose of power saving while adapting it to a specific viewing angle and brightness. Summary of the Invention

[0005] Therefore, one objective of the present disclosure is to provide an optical film and an optical film set, which can be applied in a backlight module and a display device to suit a specific viewing angle.

[0006] In accordance with the above objects of the present disclosure, there is provided an optical film, the optical film including a body having opposing first and second optical surfaces, a plurality of first prism structures disposed on the first optical surface, and a plurality of second prism structures disposed on the second optical surface, each of the first prism structures having a first extension direction, and each of the second prism structures having a second extension direction, wherein the first extension direction is different from the second extension direction.

[0007] According to an embodiment of the present disclosure, the first prism structures have an array density Y, and each first prism structure has a first side and a second side connected to each other, and an included angle X between the first side and the second side, where the array density Y and the included angle X are Y≧0.441+0.01249X−3.2875 * 10 -4 X 2 +1.95833 * 10 -6 X 3 The following relation is satisfied.

[0008] According to an embodiment of the present disclosure, there are gaps between the first prism structures, and the array density Y is calculated based on the function Y=(P1-W1) / P1, where P1 is the interval between any two adjacent first prism structures, and W1 is the width of each gap.

[0009] According to one embodiment of the present disclosure, each of the first prism structures is a stripe structure recessed or protruding into the first optical surface.

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

[0011] According to an embodiment of the present disclosure, after a light beam enters the body 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 beam is exited along a front viewing direction and another part of the light beam is exited along a side viewing direction. Output Brightness Emitted from the side viewing direction Output Brightness The ratio is greater than 0.4, including the end values.

[0012] According to one embodiment of the present disclosure, the front view direction is parallel to the exit normal of the optical film, and the included angle between the side view direction and the exit normal is greater than 40 degrees, including the end values.

[0013] According to the above object of the present disclosure, there is provided another backlight module, which includes a light guide plate having an incident surface and an exit surface, a light source adjacent to the incident surface, the above optical film disposed in front of the exit surface, and a film set between the optical film and the light guide plate.

[0014] According to the above objectives of the present disclosure, there is provided a backlight module, which includes a light source including a substrate and a plurality of light emitting units arranged on the substrate, and the above optical film disposed in front of the light source.

[0015] According to the above object of the present disclosure, there is provided a display device, which includes the above backlight module and a display panel disposed in front of the backlight module.

[0016] According to the above object of the present disclosure, there is provided an optical film set, which includes a first film having a first optical surface and a plurality of first prism structures, and a second film having a second optical surface and a plurality of second prism structures, the first prism structures are disposed on the first optical surface, and each of the first prism structures has a first extension direction, the first optical surface and the second optical surface face in opposite directions, and the second prism structures are disposed on the second optical surface, and each of the second prism structures has a second extension direction, where the first extension direction is different from the second extension direction.

[0017] According to an embodiment of the present disclosure, the first prism structures have an array density Y, and each first prism structure has a first side and a second side connected to each other, and an included angle X between the first side and the second side, and the array density Y and the included angle X are Y≧0.441+0.01249X−3.2875 * 10 -4 X 2 +1.95833 * 10 -6 X 3 The following relation is satisfied.

[0018] According to an embodiment of the present disclosure, there is a gap between any two adjacent first prism structures, and the array density Y is calculated based on a function Y=(P1-W1) / P1, where P1 is the interval between any two adjacent first prism structures, and W1 is the width of each gap.

[0019] According to one embodiment of the present disclosure, each of the first prism structures is a stripe structure recessed or protruding into the first optical surface.

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

[0021] According to an embodiment of the present disclosure, after a light beam enters one of the first optical surface and the second optical surface and exits the other of the first optical surface and the second optical surface, a part of the light beam is exited along the front viewing direction and another part of the light beam is exited along the side viewing direction. Output Brightness Emitted from the side viewing direction Output Brightness The ratio is greater than 0.4, including the end values.

[0022] According to one embodiment of the present disclosure, the front view direction is parallel to the exit normal of the optical film set, and the included angle between the side view direction and the exit normal is greater than 40 degrees, including the end values.

[0023] According to the above object of the present disclosure, there is provided another backlight module, which includes a light guide plate having an incident surface and an exit surface, a light source adjacent to the incident surface, the above optical film set disposed in front of the exit surface, and a film set disposed between the optical film and the light guide plate.

[0024] According to the above objectives of the present disclosure, there is provided a backlight module, which includes a light source including a substrate and a plurality of light emitting units arranged on the substrate, and the above optical film set disposed in front of the light source.

[0025] According to the above object of the present disclosure, there is provided a display device, which includes the above backlight module and a display panel disposed in front of the backlight module.

[0026] According to an embodiment of the present disclosure, there is a gap between any two adjacent first prism structures, and the array density Y is calculated based on a function Y=(P1-W1) / P1, where P1 is the interval between any two adjacent first prism structures, and W1 is the width of each gap.

[0027] As can be seen from the above, the present disclosure mainly relies on the design of the first prism structure and the second prism structure in the optical film or optical film set to redirect some of the perpendicular light to another viewing angle direction, thereby improving the overall viewing range and adapting to a specific viewing angle without the need to increase the current to increase the overall brightness. [Brief description of the drawings]

[0028] For a better understanding of the embodiments and their advantages, reference should be made to the following drawings, in which: [Figure 1] FIG. 2 is a schematic diagram illustrating an application of an optical film according to an embodiment of the present disclosure to a direct-type backlight module. [Diagram 2] FIG. 2 is a schematic diagram illustrating a portion of an optical film according to an embodiment of the present disclosure. [Diagram 3] FIG. 1 is a schematic diagram showing a viewing angle standard for vehicle displays defined by the known European Union. [Figure 4] FIG. 2 is a curve diagram 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. [Diagram 5] FIG. 2 is a schematic diagram showing the ratio of side-view output luminance to front-view output luminance generated using optical films with first prism structures having different angles and different arrangement densities according to an embodiment of the present disclosure. [Figure 6A] FIG. 1 is a schematic diagram showing a simulation of the exit luminance at each viewing angle of a known optical film. [Figure 6B] FIG. 2 is a schematic diagram illustrating a simulation of the exit luminance at each viewing angle of the optical film having a first prism structure according to an embodiment of the present disclosure. [Figure 7] FIG. 11 is a curve showing the relationship between viewing angle and brightness obtained by simulation using an optical film according to an embodiment of the present disclosure and an optical film of a comparative example. [Figure 8] FIG. 2 is a schematic diagram illustrating an application of an optical film according to an embodiment of the present disclosure to a direct-type backlight module. [Figure 9]FIG. 2 is a schematic diagram illustrating the application of an optical film according to an embodiment of the present disclosure to a side-in type backlight module. [Figure 10] 1 is a schematic diagram illustrating a display device according to an embodiment of the present disclosure. [Figure 11] FIG. 2 is a schematic diagram illustrating an application of an optical film set according to an embodiment of the present disclosure to a direct-type backlight module. [Figure 12] FIG. 2 is a schematic diagram illustrating a portion of an optical film set according to an embodiment of the present disclosure. [Figure 13] FIG. 2 is a schematic diagram illustrating an application of an optical film set according to an embodiment of the present disclosure to a side-in type backlight module. [Figure 14] FIG. 11 is a schematic diagram illustrating a display device according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Referring to FIG. 1, this is a schematic diagram illustrating the application of an optical film according to an embodiment of the present disclosure to a direct type backlight module. 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 can be applied to the side-in type backlight module 300 as shown in FIG. 9, so as to increase the output viewing angle of the backlight module 200 or the backlight module 300. In the backlight module 200 as shown in FIG. 1, the optical film 100 is disposed in front of the light source 210. Here, the light source 210 includes a substrate 211 and a plurality of light emitting units 212 arranged on the substrate 211. Thus, the light provided by the light source 210 can directly pass through the optical film 100 and be emitted from the optical film 100.

[0030] As shown in FIG. 1, the optical film 100 in this embodiment includes a body 110 having a first optical surface 111 and a second optical surface 112, a plurality of first prism structures 120 disposed on the first optical surface 111, and a plurality of second prism structures 130 disposed on the second optical surface 112. As shown in FIG. 1, the first prism structure 120 has a first extension direction D1, and the second prism structure 130 has a second extension direction D2, and the first extension direction D1 is different from the second extension direction D2. Therefore, after the light beam enters the optical film 100 from the first optical surface 111, the first prism structure 120 can change some of the perpendicular light beams into light beams in other directions, and the light beams after the change in direction can be transmitted through the second prism structure 130 on the second optical surface 112 to be emitted. Specifically, as shown in FIG. 1, after the light beam is applied through the optical film 100, some of the light beams (e.g., light beam L1) can pass through the blanks S1 between the first prism structures 120 and exit along the front viewing direction, and other of the light beams (e.g., light beam L2) can be applied through the first prism structures 120 and exit along the side viewing direction. Here, the front viewing direction refers to the light beam being parallel to the normal direction of the optical film 100, and has an included angle θ between the side viewing direction and the front viewing direction. More specifically, the front viewing direction is parallel to the output normal of the optical film 100, and the included angle θ between the side viewing direction and the output normal is greater than 40 degrees, including the end value. In this way, the optical film 100 of this embodiment can further redirect some of the normal light to other viewing angle directions and adjust the size of the horizontal viewing angle to expand the viewing angle, and can be adapted to a specific viewing angle and brightness without needing to increase the current to increase the overall brightness, and can achieve the purpose of power saving at the same time.

[0031] In this embodiment, each of the first prism structures 120 is a stripe structure protruding on the first optical surface 111. In another embodiment, the first prism structure 120 may be a stripe structure recessed on 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. Also, referring to FIG. 2, FIG. 2 is a schematic diagram showing a part of an optical film according to an embodiment of the present disclosure. In one embodiment, each of the first prism structures 120 has a first side 121 and a second side 122 connected to each other, and has an included angle X between the first side 121 and the second side 122. The first prism structures 120 have an array density, and there is a spacing P1 between any two adjacent first prism structures 120, and the blank portion S1 has a width W1. Here, the array density is calculated based on a function Y=(P1-W1) / P1.

[0032] In this embodiment, after the light beam passes through the optical film 100, the light beam L1 is emitted from the front viewing direction. Output Brightness The light ray L2 emitted from the side viewing direction Output Brightness When the ratio is 0.4 or more, that is, when the optical film 100 is viewed from the front Output Brightness A side view of Output Brightness must be 40% or more, the first prism structure 120 is designed to satisfy Y≧0.441+0.01249X−3.2875 * 10 -4 X 2 +1.95833 * 10 -6 X 3 The following relation must be satisfied.

[0033] Referring to FIG. 3 and Table 1, FIG. 3 is a schematic diagram showing a viewing angle standard for a vehicle display defined by a known European Union. In the viewing angle standard for a vehicle display defined by the European Union (Deutsches Flachdisplay Forum), in order to simultaneously consider the viewing angles of the driver's seat and the passenger seat, for example, as shown in FIG. 3, the viewing angle standard for a vehicle display is divided into a range of light rays emitted from the front viewing direction of the vehicle display, such as area A+, area A, and area B. Output Brightness(That is, the brightness of area A+ , usually refers to the minimum brightness between ±10 degrees ) of the light emitted from the side viewing direction Output Brightness (That is, the brightness of area B , usually refers to the minimum brightness between ±50 degrees However, in this embodiment, a higher standard than the viewing angle standard for vehicle displays defined by the European Union is adopted, and the ratio of the light emitted from the front viewing direction is set to 37.5%. Output Brightness of light emitted from the side viewing direction Output Brightness must be at least 40% (i.e., greater than 37.5%), so that designing the optical film 100 using the relationship in this embodiment can increase the output viewing angle and comply with the European Union's regulations on vehicle display brightness.

[0034] Viewing angle ranges for each region in Figure 3 and European Union viewing angle standards [Table 1]

[0035] 4 and 5, FIG. 4 is a curve diagram showing the relationship between the included angle (X) and the arrangement density (Y) of the first prism structure according to one embodiment of the present disclosure, and FIG. 5 is a curve diagram showing the relationship between the included angle (X) and the arrangement density (Y) of the first prism structure according to one embodiment of the present disclosure, and FIG. Output Brightness A side view of Output Brightness 4 and 5, the optical film 100 is Output Brightness A side view of Output Brightness needs to be 40%, then, to meet the demand for a specific output viewing angle, the included angle X of the first prism structure 120 can be set to 40 degrees and the array density to 54%, or the included angle X of the first prism structure 120 can be set to 60 degrees and the array density to 43%, or the included angle X of the first prism structure 120 can be set to 90 degrees and the array density to 33%, or the included angle X of the first prism structure 120 can be set to 120 degrees and the array density to 59%.

[0036] 6A and 6B, FIG. 6A is a schematic diagram of the simulation of the output brightness at each viewing angle of a known optical film, and FIG. 6B is a schematic diagram of the simulation of the output brightness at each viewing angle of a first prism structure optical film according to an embodiment of the present disclosure. Compared with the schematic diagram of the simulation of the brightness of the known optical film in FIG. 6A, it is clear that the dark color area of ​​the embodiment in FIG. 6B is separated into two areas, and the output brightness of the front viewing angle is reduced so as to reduce the consumption of the output energy at the front viewing angle, and the brightness of the side viewing angles of the driver's seat and the passenger seat is improved. As for the comparative example of a normal prism sheet or a film that does not satisfy the relational expression, neither of them can separate the dark color area into two areas, and the purpose of the present application cannot be achieved.

[0037] In addition, the present disclosure is not limited to the above-mentioned angle and array density, and the following relational expression can be used to obtain the following: Output Brightness According to the ratio demand, the included angle X and the arrangement density of the corresponding first prism structures 120 can be calculated. For example, the curve in FIG. Output Brightness A side view of Output Brightness When the ratio is equal to 40%, the relationship curve between the included angle X of the first prism structure 120 and the array density is shown. Output Brightness A side view of Output Brightness The ratio of the included angle X of the first prism structure 120 corresponds to the relationship between the included angle X and the array density. Take the included angle X of the first prism structure 120 as an example, when the included angle X of the first prism structure 120 is 90 degrees, the array density is 33%. Output Brightness A side view of Output Brightness The proportion of people with high front vision is 40%. Output Brightness A side view of Output Brightness If the ratio is required, the array density of the first prism structures 120 can be increased under the same condition that the included angle X of the first prism structures 120 is 90 degrees, for example, by setting the array density to be greater than 33%, Output Brightness A side view of Output Brightness The objective of increasing the proportion of

[0038] Also, referring to FIG. 7, FIG. 7 is a curve diagram showing the relationship between viewing angle and brightness simulated using the optical film 100 according to an embodiment of the present disclosure and a comparative optical film. Here, the comparative optical film is a normal single-sided prism sheet. As can be seen from FIG. 7, after a light ray passes through the normal single-sided prism sheet and exits, the exit viewing angle range is high between -40 degrees and +40 degrees. Output Brightness After the light beam passes through the optical film 100 according to the embodiment of the present disclosure and is emitted, the luminance emitted from the optical film 100 in the front viewing angle range of -30 degrees to +30 degrees is lower than the luminance at the exit front viewing angle of the optical film of the comparative example, but the luminance at the viewing angle position in the range other than -40 degrees to +40 degrees is Output Brightness For example, the relative luminance in the viewing angle range of −50 degrees to +50 degrees is increased from 0.3 to 0.5. Output Brightness In order to reduce energy consumption, the output brightness at the front viewing angle can be reduced, and the brightness at the side viewing angles of the driver's seat and passenger seat can be improved, so as to meet the usage demands of vehicle displays.

[0039] Also, referring to FIG. 8, FIG. 8 is a schematic diagram showing an application of an optical film according to an embodiment of the present disclosure to a direct type backlight module. 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 as 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. Thus, the light provided by the light source 210 can enter the optical film 100 after passing through the diffusion film 510 and the diffusion plate 520, and can be acted on through the optical film 100 to form a wide viewing angle output.

[0040] Also, referring to FIG. 9, FIG. 9 is a schematic diagram showing an application of an optical film according to an embodiment of the present disclosure to a side-in type backlight module. The optical film 100 of this embodiment can also be applied to a side-in type backlight module 300. Here, the backlight module 300 includes a light source 310, a light guide plate 320, a film set 330, and an optical film 100. Here, the light source 310 is adjacent to an incident surface 321 of the light guide plate 320, and the optical film 100 is installed in front of an exit surface 322 of the light guide plate 320. The film set 330 is installed between the light guide plate 320 and the optical film 100. Thus, the light provided by the light source 310 enters the light guide plate 320 to form a surface light source and then exits, and then passes through the film set 330 and enters the optical film 100 again, and can be acted on through the optical film 100 to form a wide viewing angle exit.

[0041] Also, please refer to 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 a backlight module 200 and a display panel 410 as shown in FIG. 1. The display panel 410 is installed in front of the backlight module 200. Therefore, the display device 400 can also achieve a front viewing angle of 1000 mm by designing the optical film 100 in the backlight module 200. Output Brightness Reduces side viewing angles Output Brightness 9)。The purpose of increasing the viewing angle can be achieved, so the description thereof will be omitted here. Here, this embodiment is only described as an example in which the backlight module 200 as shown in FIG. 1 is applied to a display device 400, and is not intended to limit the present disclosure. The backlight modules of the other embodiments described above (for example, the backlight module 300 as shown in FIG. 9) can all be applied to a display device to achieve the same viewing angle widening effect.

[0042] Referring to FIG. 11, this is a schematic diagram illustrating the application of an optical film set according to an embodiment of the present disclosure to a direct type backlight module. The optical film set 600 of this embodiment can be mainly applied to a direct type backlight module 700 as shown in FIG. 11, or can be applied to a side-in type backlight module 800 as shown in FIG. 13, so as to increase the output viewing angle of the backlight module 700 or the backlight module 800. In the backlight module 700 as shown in FIG. 11, the optical film set 600 is installed in front of a light source 710. Here, the light source 710 includes a substrate 711 and a plurality of light emitting units 712 arranged on the substrate 711. Thus, the light provided by the light source 710 can directly pass through the optical film set 600 and be emitted from the optical film set 600.

[0043] As shown in Fig. 11, the optical film set 600 of this embodiment includes a first film 610 having a first optical surface 612 and a plurality of first prism structures 611, and a second film 620 having a second optical surface 622 and a plurality of second prism structures 621. Here, the first prism structures 611 are disposed on the first optical surface 612, and the second prism structures 621 are disposed on the second optical surface 622. As shown in Fig. 11, the first prism structures 611 have a first extension direction D1, and the second prism structures 621 have a second extension direction D2, where the first extension direction D1 is different from the second extension direction D2. Therefore, after the light beam enters the optical film set 600 through the first optical surface 612, the first prism structure 611 can change some of the perpendicular light beams into light beams in other directions, and the light beams after the change in direction can be transmitted through the second prism structure 621 on the second optical surface 622 to exit. Specifically, as shown in FIG. 11, after the light beam is acted on through the optical film 600, some of the light beams (e.g., light beam L1) can be transmitted through the blank portion S1 between the first prism structures 611 to exit along the front viewing direction, and the other part of the light beams (e.g., light beam L2) can be acted on through the first prism structure 611 to exit along the side viewing direction. Here, the front viewing direction refers to the light beam being parallel to the normal direction of the optical film set 600, and has an included angle θ between the side viewing direction and the front viewing direction. More specifically, the front viewing direction is parallel to the output normal of the optical film set 600, and the included angle θ between the side viewing direction and the output normal is greater than 40 degrees, including the end value. In this way, the optical film set 600 of this embodiment can further redirect some of the normal light to other viewing angle directions, adjust the horizontal viewing angle to expand the viewing angle, and can match a specific viewing angle and brightness without needing to increase the current to increase the overall brightness, while simultaneously achieving the purpose of power saving.

[0044] In this embodiment, each of the first prism structures 611 is a stripe structure that protrudes into the first optical surface 612. In another embodiment, the first prism structure 611 may be a stripe structure that is 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. Also, referring to FIG. 12, FIG. 12 is a schematic diagram showing a part of an optical film set according to an embodiment of the present disclosure. In one embodiment, each of the first prism structures 611 has a first side 611a and a second side 611b connected to each other, and has an included angle X between the first side 611a and the second side 611b. The first prism structures 611 have an array density Y, and there is a spacing P1 between any two adjacent first prism structures 611, and the blank portion S2 has a width W1. Here, the array density is calculated based on the function Y=(P1-W1) / P1.

[0045] In this embodiment, after the light beam is acted on through the optical film set 600, the light beam L1 emitted from the front viewing direction is Output Brightness The light ray L2 emitted from the side viewing direction Output Brightness When the ratio is 0.4 or more, that is, when the optical film set 600 is viewed from the front, Output Brightness A side view of Output Brightness must be 40% or more, the first prism structure 611 is designed to satisfy Y≧0.441+0.01249X−3.2875 * 10 -4 X 2 +1.95833 * 10 -6 X 3 The following relation must be satisfied.

[0046] Also, referring to FIG. 13, FIG. 13 is a schematic diagram showing an application of an optical film set according to an embodiment of the present disclosure to a side-in type backlight module. The optical film set 600 of this embodiment can also be applied to a side-in type backlight module 800. Here, the backlight module 800 includes a light source 810, a light guide plate 820, a film set 830, and an optical film set 600. Here, the light source 810 is adjacent to an incident surface 821 of the light guide plate 820, and the optical film 600 is installed in front of an exit surface 822 of the light guide plate 820. The film set 830 is installed between the light guide plate 820 and the optical film 600. Thus, the light provided by the light source 810 enters the light guide plate 820 to form a surface light source and then exits, and then passes through the film set 830 and enters the optical film set 600 again, and can be acted on through the optical film set 600 to form a wide viewing angle exit.

[0047] 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 a backlight module 700 and a display panel 910 as shown in FIG. 11. The display panel 910 is installed in front of the backlight module 700. Therefore, the display device 900 can also achieve a front viewing angle of 1000° by designing the optical film set 600 in the backlight module 700. Output Brightness Reduces side viewing angles Output Brightness 11 to a display device 900, and the description thereof will be omitted here. Here, this embodiment is only described as an example in which the backlight module 700 as shown in FIG. 11 is applied to a display device 900, and does not limit the present disclosure. Any of the backlight modules of the other embodiments described above (for example, the backlight module 800 as shown in FIG. 13) can be applied to a display device to achieve the same effect of widening the viewing angle.

[0048] As can be seen from the above embodiments of the present disclosure, the present disclosure mainly relies on the design of the first prism structure and the second prism structure in the optical film or the optical film set to redirect some of the perpendicular light to another viewing angle direction, thereby improving the overall viewing range and meeting a specific viewing angle without needing to increase the current to increase the overall brightness. Meanwhile, the relationship of 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 demands of different vehicle-mounted display devices. [Explanation of symbols]

[0049] 100 Optical Film 110 Main unit 111 First Optical Surface 112 Second Optical Surface 120 First Prism Structure 121 First Aspect 122 The Second Aspect 130 Second Prism Structure 200 Backlight Module 210 Light source 211 Substrate 212 Light Emitting Unit 300 Backlight Module 310 light source 320 Light guide plate 321 Incidence plane 322 Exit surface 330 Film Set 400 display device 410 Display Panel 500 Backlight Module 510 Diffusion Film 520 Diffusion Plate 600 Optical Film Set 610 First Film 611 First Prism Structure 611a First aspect 611b Second Aspect 612 First Optical Surface 620 Second Film 621 Second Prism Structure 622 Second Optical Surface 700 Backlight Module 710 Light source 711 Substrate 712 Light Emitting Unit 800 Backlight Module 810 Light source 820 Light guide plate 821 Entrance plane 822 Exit surface 830 Film Set 900 Display device 910 Display Panel Area A B area A+ area D1 First extension direction D2 Second extension direction L1 ray L2 ray P1 interval S1 Blank area S2 Blank area W1 width θ included angle X inclusion angle

Claims

1. An optical film, a first optical surface; and a second optical surface opposite the first optical surface; and a plurality of first prism structures disposed on the first optical surface, each having a first extension direction; a plurality of second prism structures disposed on the second optical surface, each having a second extension direction; The first extending direction is different from the second extending direction.

2. The plurality of first prism structures have an array density Y, and each of the plurality of first prism structures has a first side and a second side connected to each other, and an included angle X between the first side and the second side, and the array density Y and the included angle X are Y≧0.441+0.01249X−3.2875 ＊ 10 －４ X ２ +1.95833 ＊ 10 －６ X ３ The optical film according to claim 1 , which satisfies the following relational expression.

3. There is a gap between any two adjacent first prism structures, and the array density Y is expressed as Y=(P １ -W １ ) / P １ It is calculated based on the function P １ is the distance between any two adjacent first prism structures of the plurality of first prism structures, and W １ The optical film according to claim 2 , wherein x is the width of each of the plurality of blank portions.

4. The optical film of claim 1 , wherein each of the plurality of first prism structures is a stripe structure recessed or protruding into the first optical surface.

5. The optical film according to claim 1 , wherein the first extending direction and the second extending direction form an angle of 90 degrees.

6. 2. The optical film according to claim 1, wherein after a light ray 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 ray exits along a front viewing direction and another portion of the light ray exits along a side viewing direction, and a ratio of the exit luminance exiting from the side viewing direction to the exit luminance exiting from the front viewing direction is 0.4 or more.

7. The optical film of claim 1, wherein after light rays enter one of the first optical surface and the second optical surface and exit from the other of the first optical surface and the second optical surface, a majority of the light rays exit along a front viewing direction and a minority of the light rays exit along a side viewing direction, the front viewing direction is parallel to an exit normal of the optical film, and the included angle between the side viewing direction and the exit normal is 40 degrees or more.

8. A backlight module, comprising: a light guide plate having an entrance surface and an exit surface; a light source proximate the entrance surface; The optical film according to claim 1 , which is placed in front of the light exit surface; and a film set between the optical film and the light guide plate; A backlight module.

9. A backlight module, comprising: a light source including a substrate and a plurality of light emitting units arranged on the substrate; The optical film according to claim 1 , which is placed in front of the light source; and A backlight module.

10. A display device, comprising: A backlight module according to claim 8 or 9; A display panel disposed in front of the backlight module; A display device comprising:

11. An optical film set comprising at least two stacked optical films according to claim 1, the bottom optical film having a first optical surface and a plurality of first prism structures; The optical film set, wherein the top optical film has a second optical surface and a plurality of second prism structures.

12. A backlight module, comprising: a light guide plate having an entrance surface and an exit surface; a light source proximate the entrance surface; The optical film set according to claim 11 , which is placed in front of the exit surface; a film set between the optical film set and the light guide plate; A backlight module.

13. A backlight module, comprising: a light source including a substrate and a plurality of light emitting units arranged on the substrate; The optical film set according to claim 11 placed in front of the light source; A backlight module.

14. A display device, comprising: A backlight module according to claim 12 or 13; A display panel disposed in front of the backlight module; A display device comprising:

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