Optical films, optical film sets, backlight modules, and display devices.

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] This disclosure relates to optical films and their applications, and more particularly to optical films that produce a large emission viewing angle, optical film sets, backlight modules and display devices that use the optical films and optical film sets. [Background technology]

[0002] Because the European Union defines vehicle displays based on a viewing angle standard (Deutsches Flachdisplay Forum) that takes into account the viewing angles of the driver and passenger seats, all current automotive product standards are designed with reference to this standard.

[0003] Currently, the prism sheets used in backlight modules are primarily used to concentrate light rays in the direction of the front viewing angle. However, vehicle displays are mounted below the driver's line of sight, and the center console (Center Informative Display, CID) must be designed so that both the driver and passenger can see it. Therefore, the viewing angle requirements are biased upwards (upper viewing angle is within 20 degrees, and lower viewing angle is within 15 degrees), and the left and right viewing angles are distributed relatively widely (left and right viewing angles are within 50 degrees), which is significantly different from the viewing angle requirements of typical tablet computers and laptops.

[0004] Generally, the viewing angle can be reduced by using a privacy screen, but the energy loss of such a screen is quite significant. While increasing only the overall brightness can achieve the desired brightness at wide viewing angles, this presents power consumption issues. Therefore, the motivation for this invention lies in developing an optical film that can be adapted to specific viewing angles and brightness levels while simultaneously achieving power savings when applied to display devices. [Overview of the Initiative]

[0005] Therefore, one object of this disclosure is to provide optical films and optical film sets that can be applied to backlight modules and display devices to suit a specific viewing angle.

[0006] To the purposes of this disclosure, an optical film is provided. This optical film includes a body having a first optical surface and a second optical surface facing each other, a plurality of first prism structures installed on the first optical surface, and a plurality of second prism structures installed on the second optical surface. Each first prism structure has a first extending direction. Each second prism structure has a second extending direction, where the first extending direction is different from the second extending direction.

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

[0008] According to one 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 distance 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 that is recessed or protruding from the first optical surface.

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

[0011] According to one embodiment of the present disclosure, a ray enters the body from one of the first optical surface and the second optical surface, and after being emitted from the other of the first optical surface and the second optical surface, some of the ray is emitted along the front viewing direction, and other parts of the ray are emitted along the side viewing direction. Here, the ray emitted from the front viewing direction Emitting Brightness Emitted from a side view direction relative to Emitting Brightness The ratio is greater than 0.4 and includes the endpoint value.

[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 angle between the side view direction and the exit normal is greater than 40 degrees, including the endpoint value.

[0013] To the purposes of the present disclosure, another backlight module is provided. The backlight module includes a light guide plate having an incident surface and an exit surface, a light source positioned close to the incident surface, the optical film placed in front of the exit surface, and a film set between the optical film and the light guide plate.

[0014] To the purposes of the present disclosure, a backlight module is provided. The backlight module includes a light source comprising a substrate and a plurality of light-emitting units arranged on the substrate, and the optical film placed in front of the light source.

[0015] For the purposes of this disclosure described above, a display device is provided. The display device includes the backlight module described above and a display panel installed in front of the backlight module.

[0016] According to the above object of the present disclosure, an optical film set is provided. This optical film set 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 installed on the first optical surface, and each first prism structure has a first extending direction. The first optical surface and the second optical surface face in opposite directions, the second prism structures are installed on the second optical surface, and each second prism structure has a second extending direction. Here, the first extending direction is different from the second extending direction.

[0017] According to an embodiment of the present disclosure, the above-mentioned first prism structure has an array density Y, and each first prism structure has a first side surface and a second side surface connected to each other. There is an included angle X between the first side surface and the second side surface, and the array density Y and the included angle X satisfy the relational expression Y≧0.441 + 0.01249X - 3.2875 * 10 -4 X 2 +1.95833 * 10 -6 X 3 and satisfy the above relational expression.

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

[0019] According to an embodiment of the present disclosure, each of the above-mentioned first prism structures is a stripe structure that is recessed or protruded on the first optical surface.

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

[0021] According to an embodiment of the present disclosure, light rays enter from one of the first optical surface and the second optical surface, and after being emitted from the other of the first optical surface and the second optical surface, some light rays are emitted along the front view direction, and the other part of the light rays are emitted along the side view direction. Here, the Emitting Brightness emitted from the side view direction with respect to the Emitting Brightness ratio is greater than 0.4, including the end point values.

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

[0023] According to the above object of the present disclosure, another backlight module is provided. The backlight module includes a light guide plate having an incident surface and an emission surface, a light source close to the incident surface, the above optical film set installed in front of the emission surface, and a film set between the optical film and the light guide plate.

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

[0025] According to the above object of the present disclosure, a display device is provided. The display device includes the above backlight module and a display panel installed 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 based on the function Y = (P1 - W1) / P1. Here, P1 is the interval between any two adjacent first prism structures, and W1 is the width of each blank portion.

[0027] As can be seen from the above, this disclosure makes it possible to change some orthogonal light to other viewing angle directions by designing a first prism structure and a second prism structure in an optical film or optical film set, thereby improving the overall viewing range and making it possible to adapt to a specific viewing angle without having to increase the current to increase the overall brightness. [Brief explanation of the drawing]

[0028] To better understand the examples and their advantages, please refer to the drawings and explain them as follows. [Figure 1] This is a schematic diagram illustrating the application of an optical film according to one embodiment of the present disclosure to a direct-lit backlight module. [Figure 2] This is a schematic diagram showing a part of an optical film according to one embodiment of the present disclosure. [Figure 3] This is a schematic diagram illustrating the known European Union's defined viewing angle standards for vehicle displays. [Figure 4] This is a curve diagram showing the relationship between the holding angle (X) and the array density (Y) of a first prism structure according to one embodiment of the present disclosure. [Figure 5] This is a schematic diagram of the ratio of side-view output brightness to front-view output brightness generated using optical films of a first prism structure having different angles and different array densities according to one embodiment of the present disclosure. [Figure 6A] This is a schematic simulation diagram of the emitted brightness of a known optical film at various viewing angles. [Figure 6B] This is a schematic simulation diagram of the output brightness at each viewing angle of an optical film with a first prism structure according to one embodiment of the present disclosure. [Figure 7] This is a relationship curve diagram between viewing angle and brightness, simulated using an optical film according to one embodiment of this disclosure and an optical film of a comparative example. [Figure 8] This is a schematic diagram illustrating the application of an optical film according to one embodiment of the present disclosure to a direct-lit backlight module. [Figure 9]This is a schematic diagram illustrating the application of an optical film according to one embodiment of the present disclosure to a side-in type backlight module. [Figure 10] A schematic diagram of a device showing a display device according to one embodiment of the present disclosure. [Figure 11] This is a schematic diagram illustrating the application of an optical film set according to one embodiment of the present disclosure to a direct-lit backlight module. [Figure 12] This is a schematic diagram showing a part of an optical film set according to one embodiment of the present disclosure. [Figure 13] This is a schematic diagram illustrating the application of an optical film set according to one embodiment of the present disclosure to a side-in type backlight module. [Figure 14] This is a schematic diagram of a device showing a display device according to another embodiment of the present disclosure. [Modes for carrying out the invention]

[0029] Referring to Figure 1, this is a schematic diagram illustrating the application of an optical film to a direct-lit backlight module according to one embodiment of the present disclosure. The optical film 100 of this embodiment can be applied mainly to direct-lit backlight modules 200 and 500 as shown in Figures 1 and 8, or to a side-in type backlight module 300 as shown in Figure 9, in order to increase the emission viewing angle of the backlight module 200 or backlight module 300. In the backlight module 200 as shown in Figure 1, the optical film 100 is placed in front of the light source 210, where the light source 210 includes a substrate 211 and a plurality of light-emitting units 212 arranged on the substrate 211. Thus, the light rays 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 Figure 1, the optical film 100 in this embodiment includes a main body 110 having a first optical surface 111 and a second optical surface 112, a plurality of first prism structures 120 installed on the first optical surface 111, and a plurality of second prism structures 130 installed on the second optical surface 112. As shown in Figure 1, the first prism structures 120 have a first extending direction D1, and the second prism structures 130 have a second extending direction D2, and the first extending direction D1 is different from the second extending direction D2. Therefore, after light rays enter the optical film 100 from the first optical surface 111, the first prism structures 120 can change some of the straight-ahead light rays into light rays in other directions, and further cause the directionally changed light rays to pass through the second prism structures 130 on the second optical surface 112 and be emitted. Specifically, as shown in Figure 1, after light rays act through the optical film 100, some of the light rays (e.g., ray L1) can pass through the gap S1 between the first prism structures 120 and exit along the front viewing direction, while other light rays (e.g., ray L2) can act through the first prism structures 120 and exit along the side viewing direction. Here, the front viewing direction refers to the direction in which the light rays are parallel to the normal direction of the optical film 100, and there is an angle θ between the side viewing direction and the front viewing direction. More specifically, the front viewing direction is parallel to the exit normal of the optical film 100, and the angle θ between the side viewing direction and the exit normal is greater than 40 degrees, including the endpoint value. In this way, the optical film 100 of this embodiment can further change some of the orthogonal light to other viewing angle directions, adjust the size of the horizontal viewing angle to expand the viewing angle, and adapt to a specific viewing angle and brightness without needing to increase the current to increase the overall brightness, while simultaneously achieving the objective of power saving.

[0031] In this embodiment, each first prism structure 120 is a stripe structure that protrudes into the first optical surface 111. In other embodiments, the first prism structure 120 may be a stripe structure that is recessed into the first optical surface 111. In some embodiments, the angle between the first extending direction D1 and the second extending direction D2 is 90 degrees. Referring to Figure 2, Figure 2 is a schematic diagram showing a part of an optical film according to one 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, with an angle X between the first side surface 121 and the second side surface 122. The first prism structures 120 have an array density, and there is a gap P1 between any two adjacent first prism structures 120, and the blank area S1 has a width W1. Here, the array density is calculated based on the function Y = (P1 - W1) / P1.

[0032] In this embodiment, after the light ray acts through the optical film 100, the light ray L1 emitted from the front viewing direction Emitting Brightness The light ray L2 emitted from the side view direction relative to Emitting Brightness If the ratio to is 0.4 or greater, that is, the front view of the optical film 100 Emitting Brightness A side view of Emitting Brightness If the ratio needs to be 40% or more, the design of the first prism structure 120 is Y≧0.441+0.01249X-3.2875 * 10 -4 X 2 +1.95833 * 10 -6 X 3 The following relationship must be satisfied.

[0033] Referring to Figure 3 and Table 1, Figure 3 is a schematic diagram showing the known European Union-defined viewing angle standard for vehicle displays. In the European Union-defined viewing angle standard for vehicle displays (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 areas A+, A and B in Figure 3, the light rays emitted from the front viewing direction of the vehicle display are considered. Emitting Brightness(That is, the brightness of region A+) Typically, this refers to the lowest brightness within ±10 degrees. Light rays emitted from the side view direction relative to ) Emitting Brightness (That is, the brightness of region B) Typically, this refers to the lowest brightness within ±50 degrees. The ratio of ) is stipulated to be at least greater than 37.5%. However, in this embodiment, a higher standard than the viewing angle standard for vehicle displays as defined by the European Union is adopted, and the light rays emitted from the forward viewing direction Emitting Brightness Light rays emitted from a side view direction relative to the object Emitting Brightness The ratio is required to be at least 40% (i.e., greater than 37.5%), and therefore, designing the optical film 100 using the relational formula of this embodiment can expand the output viewing angle and comply with the European Union's regulations regarding the brightness of vehicle displays.

[0034] Figure 3 shows the field of view range for each region and the European Union's field of view standards. [Table 1]

[0035] Referring to Figures 4 and 5, Figure 4 is a curve diagram showing the relationship between the included angle (X) and the array density (Y) of a first prism structure according to one embodiment of the present disclosure, and Figure 5 is a front view generated using optical films of the first prism structure having different angles and different array densities according to one embodiment of the present disclosure. Emitting Brightness A side view of Emitting Brightness This is a schematic diagram of the proportions. As can be seen from Figures 4 and 5, the front view of the optical film 100 Emitting Brightness A side view of Emitting Brightness If the ratio needs to be 40%, the angle X of the first prism structure 120 can be set to 40 degrees and the array density to 54% to meet the requirements for a specific output field of view, or the angle X of the first prism structure 120 can be set to 60 degrees and the array density to 43%, or the angle X of the first prism structure 120 can be set to 90 degrees and the array density to 33%, or the angle X of the first prism structure 120 can be set to 120 degrees and the array density to 59%.

[0036] Referring simultaneously to Figures 6A and 6B, Figure 6A is a schematic simulation of the emitted brightness at each viewing angle of a known optical film, and Figure 6B is a schematic simulation of the emitted brightness at each viewing angle of an optical film with a first prism structure according to one embodiment of the present disclosure. Compared to the schematic simulation of the brightness of a known optical film in Figure 6A, it is clear that the dark color region in the embodiment of Figure 6B is separated into two regions, reducing the emitted brightness at the front viewing angle to decrease the consumption of emitted energy at the front viewing angle, and improving the brightness at the side viewing angles of the driver's seat and passenger's seat. In the case of ordinary prism sheets and comparative examples of films that do not satisfy the relation, it is not possible to separate the dark color region into two regions, and therefore the objective of the present application cannot be achieved.

[0037] Furthermore, this disclosure is not limited to the above angles and array densities, but uses the relational formulas of this disclosure to... Emitting Brightness The angle X and array density of the corresponding first prism structure 120 can be calculated according to the proportion demand. For example, the curve in Figure 4 represents the front view of the optical film 100. Emitting Brightness A side view of Emitting Brightness When the ratio is equal to 40%, the relationship curve between the included angle X and the array density of the first prism structure 120 is shown. The range above this curve is high front view Emitting Brightness A side view of Emitting Brightness The ratio shows the relationship between the included angle X of the corresponding first prism structure 120 and the array density. 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 array density is 33%, and in this case, the front view Emitting Brightness A side view of Emitting Brightness The percentage is 40%. High frontal view Emitting Brightness A side view of Emitting Brightness If a certain ratio is required, under the same condition that the angle X of the first prism structure 120 is 90 degrees, by increasing the array density of the first prism structure 120, for example, by setting the array density to greater than 33%, the front view Emitting Brightness A side view of Emitting Brightness This can achieve the objective of increasing the proportion of [something].

[0038] Referring to Figure 7, Figure 7 is a curve diagram showing the relationship between viewing angle and brightness simulated using the optical film 100 according to one embodiment of this disclosure and the optical film of a comparative example. Here, the optical film of the comparative example is a normal single-sided prism sheet. As can be seen from Figure 7, after the light ray passes through the normal single-sided prism sheet and is emitted, the emission viewing angle range is high between -40 degrees and +40 degrees. Emitting Brightness Having the above characteristics, after light rays pass through the optical film 100 of the embodiment of this disclosure and are emitted, the brightness in the front viewing angle range from -30 degrees to +30 degrees emitted from the optical film 100 is lower than the brightness of the optical film of the comparative example in the front viewing angle range, but the brightness in viewing angle positions other than -40 degrees to +40 degrees is lower. Emitting Brightness This is significantly improved, for example, increasing the relative brightness in the viewing angle range of -50 degrees to +50 degrees from 0.3 to 0.5. As a result, the optical film 100 of this embodiment has a front viewing angle Emitting Brightness To reduce energy consumption, the output brightness at the front viewing angle can be lowered, while the brightness at the side viewing angles for the driver and passenger seats can be increased, thus meeting the usage requirements of vehicle displays.

[0039] Referring to Figure 8, which is a schematic diagram showing the application of an optical film to a direct-lit backlight module according to one 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 as shown in Figure 8, the optical film 100 is placed in front of the light source 210. The diffusion film 510 and the diffusion plate 520 are placed between the light source 210 and the optical film 100. Therefore, the light rays provided by the light source 210 pass through the diffusion film 510 and the diffusion plate 520, enter the optical film 100, and act through the optical film 100 to form a wide viewing angle emission.

[0040] Referring to Figure 9, Figure 9 is a schematic diagram showing the application of an optical film to a side-in type backlight module according to one embodiment of the present disclosure. 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 the optical film 100. Here, the light source 310 is positioned close to the incident surface 321 of the light guide plate 320, and the optical film 100 is placed in front of the exit surface 322 of the light guide plate 320. The film set 330 is placed between the light guide plate 320 and the optical film 100. Thus, the light rays provided by the light source 310 enter the light guide plate 320, form a surface light source and are emitted, then pass through the film set 330 and enter the optical film 100 again, and act through the optical film 100 to form a wide viewing angle emission.

[0041] Referring to Figure 10, this is a schematic diagram of a display device showing one 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 Figure 1. The display panel 410 is installed in front of the backlight module 200. Thus, the display device 400, by designing the optical film 100 in the backlight module 200, similarly has a front viewing angle Emitting Brightness Reduces the side viewing angle Emitting Brightness Since the objective of increasing [the viewing angle] can be achieved, the explanation is omitted here. Here, this embodiment is merely an example of applying the backlight module 200 shown in Figure 1 to the display device 400, and does not limit the disclosure. Any of the backlight modules of the other embodiments described above (for example, the backlight module 300 shown in Figure 9) can be applied to a display device to achieve a similar viewing angle expansion effect.

[0042] Referring to Figure 11, this is a schematic diagram illustrating the application of an optical film set to a direct-lit backlight module according to one embodiment of the present disclosure. The optical film set 600 of this embodiment can be applied primarily to a direct-lit backlight module 700, as shown in Figure 11, or to a side-in backlight module 800, as shown in Figure 13, in order to increase the emission viewing angle of the backlight module 700 or backlight module 800. In the backlight module 700 as shown in Figure 11, the optical film set 600 is placed in front of the light source 710, where the light source 710 includes a substrate 711 and a plurality of light-emitting units 712 arranged on the substrate 711. Thus, the light rays 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 Figure 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 installed on the first optical surface 612, and the second prism structures 621 are installed on the second optical surface 622. As shown in Figure 11, the first prism structure 611 has a first extending direction D1, and the second prism structure 621 has a second extending direction D2, and the first extending direction D1 is different from the second extending direction D2. Therefore, after the light rays enter the optical film set 600 from the first optical surface 612, the first prism structure 611 can change some of the straight-ahead light rays to rays in other directions, and further transmit the changed-direction light rays through the second prism structure 621 of the second optical surface 622 and emit them. Specifically, as shown in Figure 11, after the light rays are acted upon through the optical film 600, some of the light rays (e.g., ray L1) can transmit through the gap S1 between the first prism structures 611 and emit along the front-view direction, while other light rays (e.g., ray L2) can be acted upon through the first prism structure 611 and emit along the side-view direction. Here, the front-view direction refers to the direction in which the light rays are parallel to the normal direction of the optical film set 600, and there is an angle θ between the side-view direction and the front-view direction. More specifically, the front view direction is parallel to the emission normal of the optical film set 600, and the angle θ between the side view direction and the emission normal is greater than 40 degrees, including the endpoint value. In this way, the optical film set 600 of this embodiment can further change some of the orthogonal light to other viewing angle directions, 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, while simultaneously achieving the objective of power saving.

[0044] In this embodiment, each first prism structure 611 is a stripe structure that protrudes into the first optical surface 612. In other embodiments, 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 extending direction D1 and the second extending direction D2 is 90 degrees. Referring to Figure 12, Figure 12 is a schematic diagram showing a part of an optical film set according to one 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, with an angle X between the first side surface 611a and the second side surface 611b. The first prism structures 611 have an array density Y, and there is a gap P1 between any two adjacent first prism structures 611, and the blank space 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 ray acts through the optical film set 600, the light ray L1 emitted from the front viewing direction Emitting Brightness The light ray L2 emitted from the side view direction relative to Emitting Brightness If the ratio is 0.4 or greater, that is, the front view of optical film set 600 Emitting Brightness A side view of Emitting Brightness If the ratio needs to be 40% or more, the design of the first prism structure 611 is Y≧0.441+0.01249X-3.2875 * 10 -4 X 2 +1.95833 * 10 -6 X 3 The following relationship must be satisfied.

[0046] Referring to Figure 13, which is a schematic diagram showing the application of an optical film set according to one 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 the optical film set 600. Here, the light source 810 is positioned close to the incident surface 821 of the light guide plate 820, and the optical film 600 is placed in front of the exit surface 822 of the light guide plate 820. The film set 830 is placed between the light guide plate 820 and the optical film 600. Thus, the light rays provided by the light source 810 enter the light guide plate 820, form a surface light source and are emitted, then pass through the film set 830 and enter the optical film set 600 again, and act through the optical film set 600 to form a wide viewing angle emission.

[0047] Referring to Figure 14, this is a schematic diagram of a device showing 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 Figure 11. The display panel 910 is installed in front of the backlight module 700. Thus, the display device 900, by design of the optical film set 600 in the backlight module 700, similarly has a front viewing angle Emitting Brightness Reduces the side viewing angle Emitting Brightness Since the objective of increasing [the viewing angle] can be achieved, the explanation is omitted here. Here, this embodiment is merely an example of applying the backlight module 700 shown in Figure 11 to the display device 900, and does not limit the disclosure. Any of the backlight modules of the other embodiments described above (for example, the backlight module 800 shown in Figure 13) can be applied to a display device to achieve a similar viewing angle expansion effect.

[0048] As can be seen from the embodiments of this disclosure described above, this disclosure primarily involves the design of a first prism structure and a second prism structure in an optical film or optical film set, which can change some orthogonal light to other viewing angle directions, thereby improving the overall viewing range and allowing it to be adapted to a specific viewing angle without the need to increase the current to enhance the overall brightness. Alternatively, the relationship of this disclosure can also be used to design the angular variation and array density of the first and second prism structures to suit the viewing angle requirements of different in-vehicle 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 Second Aspect 130 Second prism structure 200 backlight modules 210 Light source 211 circuit board 212 Light-emitting unit 300 backlight modules 310 light source 320 Light guide plate 321 Incidence plane 322 Ejection surface 330 Film Set 400 display device 410 Display Panel 500 backlight modules 510 Diffusion Film 520 Diffusion Plate 600 Optical Film Set 610 First film 611 First prism structure 611a First side 611b Second side 612 First optical surface 620 Second film 621 Second prism structure 622 Second optical surface 700 Backlight Modules 710 Light source 711 circuit board 712 Light-emitting unit 800 Backlight Modules 810 Light source 820 Light guide plate 821 Entrance plane 822 Ejection 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. It is an optical film, The first optical surface and, A second optical surface opposite the first optical surface, A plurality of first prism structures are installed on the first optical surface, each having a first extending direction, The second optical surface is provided with a plurality of second prism structures, each having a second direction of extension, The first direction of extension differs from the second direction of extension, 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 there is an angle X between the first side and the second side, and the array density Y and the angle X satisfy the following relationship: Y ≥ 0.441 + 0.01249X - 3.2875 * 10 - 4 X 2 + 1.95833 * 10 - 6 X 3 An optical film having gaps between any two adjacent first prism structures, and the array density Y is calculated based on the function Y = (P1 - W1) / P1, where P1 is the distance between any two adjacent first prism structures and W1 is the width of each of the gaps.

2. The optical film according to claim 1, wherein each of the plurality of first prism structures is a stripe structure that is recessed or protruding from the first optical surface.

3. The optical film according to claim 1, wherein the angle between the first extending direction and the second extending direction is 90 degrees.

4. The optical film according to claim 1, wherein light rays enter from one of the first optical surface and the second optical surface, and are emitted from the other of the first optical surface and the second optical surface, a portion of the light rays are emitted along the front viewing direction, the other portion of the light rays are emitted along the side viewing direction, and the ratio of the emitted brightness from the side viewing direction to the emitted brightness from the front viewing direction is 0.4 or more.

5. The optical film according to claim 1, wherein light rays enter from one of the first optical surface and the second optical surface, and after they exit from the other of the first optical surface and the second optical surface, a large number of the light rays exit along the front viewing direction and a small number of the light rays exit along the side viewing direction, the front viewing direction is parallel to the exit normal of the optical film, and the angle between the side viewing direction and the exit normal is 40 degrees or more.

6. It is a backlight module, A light guide plate having an incident surface and an exit surface, A light source adjacent to the incident surface, An optical film according to claim 1, installed in front of the emission surface, The film set located between the optical film and the light guide plate, A backlight module, including the backlight module.

7. It is a backlight module, A substrate and a light source including a plurality of light-emitting units arranged on the substrate, The optical film according to claim 1, which is installed in front of the light source, A backlight module, including the backlight module.

8. A display device, A backlight module according to claim 6 or 7, The display panel installed in front of the backlight module, A display device, including a display device.

9. An optical film set comprising at least two laminated optical films according to claim 1, The lowest optical film has a first optical surface and a plurality of first prism structures. An optical film set in which the uppermost optical film has a second optical surface and a plurality of second prism structures.

10. It is a backlight module, A light guide plate having an incident surface and an exit surface, A light source adjacent to the incident surface, An optical film set according to claim 9, installed in front of the emission surface, The optical film set and the film set located between the light guide plate, A backlight module, including the backlight module.

11. It is a backlight module, A substrate and a light source including a plurality of light-emitting units arranged on the substrate, The optical film set according to claim 9, which is installed in front of the light source, A backlight module, including the backlight module.

12. A display device, A backlight module according to claim 10 or 11, The display panel installed in front of the backlight module, A display device, including a display device.

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