Backlight module and display apparatus

Abstract

A backlight module (100), comprising a light guide plate (11), light sources (12), a light control film (20), and a prismatic film (30). The prismatic film (30) comprises, in sequence away from the light control film (20) a first prismatic layer (31) and a second prismatic layer (32). The first prismatic layer (31) comprises multiple first prismatic strips (311) arranged side by side along a first direction (X), and the second prismatic layer (32) comprises multiple second prismatic strips (321) arranged side by side perpendicular to the first direction (X). The light control film (20) is configured to converge light incident on the light control film (20) to a main optical axis (M), and emit same toward the prismatic film (30), an included angle between the orthographic projection (M') of the light onto the plane in which the light control film (20) is located and the first direction (X) being within the range of 40° to 50°.

Description

Backlight module and display device

[0001] This application claims priority to Chinese Patent Application No. 202410692892.X, filed May 30, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of display, in particular to a backlight module and a display device. BACKGROUND

[0003] The backlight module generally includes a light source, a light guide plate for guiding the light emitted by the light source, and a prism film (also known as a light enhancement film) located on the light exit side of the light guide plate. The light emitted from the light guide plate exits along the normal direction of the display device including the backlight module, thereby improving the light brightness of the display device.

[0004] In the related art, most of the light rays that exit from the light guide plate and are incident on the prism film at different angles will be reflected in the prism film. After multiple reflections, this part of light rays will cause a loss of light energy. SUMMARY

[0005] Embodiments of the present application aim to solve the problem of large light energy loss when light rays are incident on the prism film in the related art.

[0006] In one aspect, an embodiment of the present application provides a backlight module, comprising a light guide plate, a light source, a light control film, and a prism film. The light source is located on the light entrance side of the light guide plate. The light control film is located on the light exit side of the light guide plate. The prism film is located on the side of the light control film away from the light guide plate. The prism film comprises a first prism layer and a second prism layer arranged in a direction away from the light control film. The first prism layer comprises a plurality of first prism strips arranged side by side in a first direction. Each first prism strip extends in a second direction. The first direction and the second direction are perpendicular to each other. The second prism layer comprises a plurality of second prism strips arranged side by side in the second direction. Each second prism strip extends in the first direction. The light control film is configured to converge light rays incident on the light control film on a main optical axis and exit towards the prism film. The angle between the normal projection of the light rays converged on the main optical axis on the plane where the light control film is located and the first direction is greater than or equal to 40° and less than or equal to 50°.

[0007] In some embodiments, the light control film is further configured to converge light rays incident on the light control film on a main optical axis and exit towards the prism film. The angle between the normal projection of the light rays exiting along the main optical axis on the plane where the light control film is located and the first direction is greater than or equal to 44° and less than or equal to 46°.

[0008] In some embodiments, the light control film includes a substrate layer and a plurality of light control elements on the substrate layer, each of the light control elements includes four side surfaces connected in sequence and end to end, and the four side surfaces collectively intersect at a vertex. The substrate layer is provided with recesses corresponding to the light control elements, the four side surfaces are fitted to the side walls of the recesses, and the vertex is fitted to the bottom of the recesses. Alternatively, the light control element further includes a first surface opposite the vertex, the four side surfaces are connected to the four edges of the first surface, and the first surface is fitted to the surface of the substrate layer.

[0009] In some embodiments, the light control film includes a substrate layer and a plurality of light control elements on the substrate layer, each of the light control elements includes a second surface and four side surfaces connected in sequence and end to end, and the four side surfaces are connected to the four edges of the second surface. The substrate layer is provided with recesses corresponding to the light control elements, the four side surfaces are fitted to the side walls of the recesses, and the second surface is fitted to the bottom of the recesses. Alternatively, the light control element further includes a third surface opposite the second surface, the area of the second surface is smaller than the area of the third surface, the four side surfaces are connected to the four edges of the third surface, and the third surface is fitted to the surface of the substrate layer.

[0010] In some embodiments, the plurality of light control elements are arranged on the side of the substrate layer away from the light guide plate, and the light control film further includes a third prism layer on the side of the substrate layer close to the light guide plate, and the third prism layer includes a plurality of third prism strips arranged side by side.

[0011] In some embodiments, the backlight module further includes a fourth prism layer arranged on the light guide plate and located on the light exit side of the light guide plate, and the fourth prism layer includes a plurality of fourth prism strips arranged side by side.

[0012] In some embodiments, the backlight module further includes a dimming element layer on the side of the light guide plate away from the light control film, and the dimming element layer is configured to reflect light incident on the dimming element layer towards the direction of the light control film.

[0013] In some embodiments, the dimming element layer includes a plurality of dimming elements configured to reflect light incident on the dimming elements towards the direction of the light control film; wherein the dimming element layer has a first region and a second region arranged in a direction away from the light source, and the density of the dimming elements in the first region is less than the density of the dimming elements in the second region.

[0014] In some embodiments, the light adjusting element layer comprises a plurality of light adjusting elements, each of the light adjusting elements comprises a curved surface and a first plane connected to each other, the first plane is arranged in contact with the light guide plate, and the curved surface is configured to reflect light rays toward the light control film.

[0015] In some embodiments, the curved surface is a spherical curved surface, the first plane is a circular plane, a depth of the light adjusting element is a maximum distance between the curved surface and the first plane, and a width of the light adjusting element is a diameter of the circular plane; a ratio of the depth to the width of the light adjusting element is greater than or equal to 0.04 and less than or equal to 0.08.

[0016] In some embodiments, the curved surface is a spherical curved surface, the first plane is a circular plane, a depth of the light adjusting element is a maximum distance between the curved surface and the first plane, and a width of the light adjusting element is a diameter of the circular plane; a plurality of the light adjusting elements comprises a first light adjusting element and a second light adjusting element arranged in a direction away from the light source, and a ratio of the depth to the width of the first light adjusting element is less than a ratio of the depth to the width of the second light adjusting element.

[0017] In some embodiments, the light adjusting element layer comprises a plurality of light adjusting elements, each of the light adjusting elements comprises a second plane, a transition surface and a third plane connected to each other in sequence, the second plane is arranged in contact with the light guide plate, and the third plane is configured to reflect light rays toward the light control film.

[0018] In some embodiments, the second plane and the third plane have a base angle therebetween, and the base angle is greater than or equal to 2° and less than or equal to 3°.

[0019] In some embodiments, the second plane and the third plane have a base angle therebetween, and a plurality of the light adjusting elements comprises a third light adjusting element and a fourth light adjusting element arranged in a direction away from the light source, and the base angle in the third light adjusting element is less than the base angle in the fourth light adjusting element.

[0020] In some embodiments, the light adjusting element layer comprises a plurality of light adjusting elements, the light adjusting elements are configured to reflect light rays toward the light control film, and the light source comprises a plurality of light emitting units arranged side by side, along an arrangement direction of the plurality of light emitting units, lengths of the light adjusting elements are consistent with a length of the light guide plate, or the plurality of light adjusting elements are arranged at intervals.

[0021] On the other hand, embodiments of this application also provide a display device, which includes a backlight module. The backlight module includes a light guide plate, a light source, a light-controlling film, and a prism film. The light source is located on the light-incident side of the light guide plate, the light-controlling film is located on the light-emitting side of the light guide plate, and the prism film is located on the side of the light-controlling film away from the light guide plate. The prism film includes a first prism layer and a second prism layer disposed along a direction away from the light-controlling film. The first prism layer includes a plurality of first prism strips arranged side by side along a first direction, each... The first prism strip extends along a second direction, the first direction and the second direction are perpendicular to each other, the second prism layer includes a plurality of second prism strips arranged side by side along the second direction, each second prism strip extending along the first direction; wherein, the light-controlling film is configured to converge light incident on the light-controlling film onto a principal optical axis and emit towards the prism film, the angle between the orthographic projection of the light converged on the principal optical axis onto the plane of the light-controlling film and the first direction is greater than or equal to 40° and less than or equal to 50°.

[0022] In some embodiments, the light-controlling film is further configured to converge the light incident on the light-controlling film onto a principal optical axis and emit it toward the prism film, and the angle between the orthographic projection of the light emitted along the principal optical axis onto the plane where the light-controlling film is located and the first direction is greater than or equal to 44° and less than or equal to 46°.

[0023] In some embodiments, the light-controlling film includes a substrate layer and a plurality of light-controlling elements located on the substrate layer. Each light-controlling element includes four side surfaces connected end-to-end, which intersect at a vertex. The substrate layer has recesses corresponding to the light-controlling elements, with the four side surfaces abutting the sidewalls of the recesses and the vertex abutting the bottom of the recesses. Alternatively, the light-controlling element further includes a first surface disposed opposite to the vertex, with the four side surfaces connected to the four edges of the first surface, and the first surface abutting the surface of the substrate layer.

[0024] In some embodiments, the light-controlling film includes a substrate layer and a plurality of light-controlling elements located on the substrate layer. Each light-controlling element includes a second surface and four side surfaces connected end-to-end, with the four side surfaces connected to the four edges of the second surface. The substrate layer has recesses corresponding to the light-controlling elements, with the four side surfaces abutting the sidewalls of the recesses, and the second surface abutting the bottom of the recesses; alternatively, the light-controlling element further includes a third surface disposed opposite to the second surface, the area of ​​the second surface being smaller than the area of ​​the third surface, the four side surfaces connecting to the four edges of the third surface, and the third surface abutting the surface of the substrate layer.

[0025] In some embodiments, a plurality of light-controlling elements are disposed on the side of the substrate layer away from the light guide plate, and the light-controlling film further includes a third prism layer located on the side of the substrate layer close to the light guide plate, the third prism layer including a plurality of third prism strips arranged side by side. Beneficial effects

[0026] In the backlight module provided in the embodiments of this application, a light-controlling film can be used to converge the light emitted from the light-controlling film onto the main optical axis. The angle between the orthographic projection of the light converged onto the main optical axis onto the plane of the light-controlling film and the first direction is between 40° and 50°. This allows the light emitted from the light-controlling film to simultaneously adapt to the preferred incident angles corresponding to the first and second prism layers, thereby avoiding the situation where the light only matches one prism layer of the prism film. This results in most of the light being reflected and recycled when passing through the other prism layer, leading to significant light loss during the light cycle. Furthermore, using a light-controlling film also helps reduce the proportion of light that is not recycled after reflection, thus avoiding large-angle light leakage. Therefore, by using a light-controlling film to deflect the azimuth angle of the light, the light energy utilization rate and output brightness of the backlight module can be effectively improved. Attached Figure Description

[0027] Figure 1 is a schematic diagram of a backlight module according to some embodiments of this application;

[0028] Figure 2 is a schematic diagram of a light-controlling film according to some embodiments of this application;

[0029] Figure 3A is a perspective view of a light-controlling element according to some embodiments of this application;

[0030] Figure 3B is a perspective view of a light-controlling element according to some other embodiments of this application;

[0031] Figure 4 is a schematic diagram of a portion of the optical path of a backlight module according to some embodiments of this application;

[0032] Figure 5 is a schematic diagram of a portion of the optical path of a backlight module according to some other embodiments of this application;

[0033] Figure 6 is a schematic diagram of the distribution of dimming elements according to some embodiments of this application;

[0034] Figure 7 is a schematic diagram of the distribution of dimming elements according to some other embodiments of this application;

[0035] Figure 8 is a simulation diagram of the light intensity and viewing angle of the light guide plate corresponding to different dimming elements according to some embodiments of this application;

[0036] Figure 9 is a simulation diagram of the viewing angle of the light guide plate corresponding to different dimming elements according to some embodiments of this application;

[0037] Figure 10 is a simulation diagram of the backlight brightness and viewing angle of the light guide plate in the H direction corresponding to different dimming elements according to some embodiments of this application.

[0038] Figure 11 is a simulation diagram of the backlight brightness and viewing angle in the V direction of the light guide plate corresponding to different dimming elements according to some embodiments of this application.

[0039] Figure 12 is a schematic diagram of the distribution of dimming elements according to some other embodiments of this application;

[0040] Figure 13 is a schematic diagram of a dimming element according to some embodiments of this application;

[0041] Figure 14 is a schematic diagram of a dimming element according to some other embodiments of this application;

[0042] Figure 15 is a schematic diagram of a display device according to some embodiments of this application. Embodiments of the present invention

[0043] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings. The described technical solutions are for illustrative purposes only and should not be construed as limiting the scope of protection of this application.

[0044] In the description of this application, it should be understood that the terms "first," "second," and similar words do not indicate any order, quantity, or importance, but are merely used to distinguish different technical features. The terms "multiple" and similar words indicate two or more unless otherwise expressly defined. The term "perpendicular" includes absolute perpendicularity and approximate perpendicularity. For example, "A is perpendicular to B" or "A and B are mutually perpendicular" means that A and B have an angle between them, and that angle is greater than or equal to 85° and less than or equal to 95°. When the angle between A and B is 90°, A and B are absolutely perpendicular; when the angle between A and B is any degree between 85° and 95° that is not 90°, A and B are relatively perpendicular. Furthermore, the term "parallel" includes absolute parallelism and approximate parallelism. In the case of relative parallelism, the angle between the two relatively parallel elements is less than 5°.

[0045] "C and / or D" includes the following three combinations: C only, D only, and a combination of C and D.

[0046] The use of “configured to” in this application implies open and inclusive language, which does not preclude the applicability to or configuration of devices to perform additional tasks or steps. Furthermore, the use of “based on” implies openness and inclusivity, because processes, steps, calculations, or other actions “based on” one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0047] In this application, the term "exemplary" is used to mean "serving as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application.

[0048] "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.

[0049] The various embodiments of this application are similar, and features from different embodiments and / or different examples can be combined with each other.

[0050] With the development of display technology, there has always been a demand for high brightness and low power consumption in display screens, especially in the field of VR display, where the demand for backlight module brightness is even more significant.

[0051] A backlight module typically includes a light source, a light guide plate for guiding the light emitted by the light source, and a prism film located on the light-emitting side of the light guide plate. The light emitted from the light guide plate converges after being refracted and reflected by the prism film and is emitted along the front view direction of the display module, thereby improving the brightness of the light emitted by the display module.

[0052] However, for light rays emitted from the light guide plate and incident on the prism film at different angles, most of the light rays will be reflected in the prism film. Although this part of the light rays will continue to be reflected and recycled in the backlight module, this part of the light rays will also cause light energy loss after multiple reflections. Furthermore, after being reflected by the prism film and finally refracted, some light rays often cause large-angle light leakage in the backlight module due to the excessive exit angle.

[0053] Based on this, some embodiments of this disclosure provide a backlight module, as shown in FIG1. ​​The backlight module 100 includes a light guide plate 11, a light source 12, a light control film 20, and a prism film 30. The light guide plate 11 has an incident light side 111 and an emitted light side 112. The light source 12 is located on the incident light side 111 of the light guide plate 11, so that the light guide plate 11 can effectively receive light from the light source 12 and guide the light out.

[0054] The light-controlling film 20 is located on the light-emitting side 112 of the light guide plate 11, and the prism film 30 is located on the side of the light-controlling film 20 away from the light guide plate 11. The prism film 30 includes a first prism layer 31 and a second prism layer 32 arranged sequentially along the direction away from the light-controlling film 20 (i.e., the third direction Z). The first prism layer 31 includes a plurality of first prism strips 311 arranged side by side along the first direction X. Each first prism strip 311 extends along the second direction Y. The first direction X and the second direction Y are perpendicular to each other. The second prism layer 32 includes a plurality of second prism strips 321 arranged side by side along the second direction Y. Each second prism strip 321 extends along the first direction X.

[0055] By setting the extension directions of the prism strips in the first prism layer 31 and the second prism layer 32 to be perpendicular to each other, a better light enhancement effect can be achieved, and the light loss of the prism film 30 can be reduced, thereby improving the light output brightness of the backlight module 100.

[0056] As shown in Figure 2, the light control film 20 is configured to converge the light incident on the light control film 20 onto a principal optical axis M and emit it in the direction of the prism film 30. The light converged on the principal optical axis M has an angle K between the orthographic projection of the light on the plane where the light control film 20 is located and the first direction X, and the angle K is greater than or equal to 40° and less than or equal to 50°.

[0057] It should be noted that, through the light-regulating effect of the light-controlling film 20, some light rays are emitted along the principal optical axis M, while other light rays converge around the principal optical axis M. For the multiple light rays around the principal optical axis M, their emission positions after passing through the light-controlling film 20 are the same as those of the light rays along the principal optical axis M, the difference being the emission angle.

[0058] Figure 2 only shows the light rays emitted along the principal optical axis M and the orthographic projection M' of the light rays on the plane where the light-controlling film 20 is located. The angle between the orthographic projection M' and the first direction X is the angle at which the light rays have a high concentration (for simplicity, this angle will be referred to as the principal axis angle below). The orthographic projection of some of the light rays converging around the principal optical axis M on the plane where the light-controlling film 20 is located is further away from the first direction X (that is, the angle between the orthographic projection of this part of the light rays on the plane where the light-controlling film 20 is located and the first direction X is larger than the principal axis angle), while the orthographic projection of another part of the light rays converging around the principal optical axis M on the plane where the light-controlling film 20 is located is closer to the first direction X (that is, the angle between the orthographic projection of this part of the light rays on the plane where the light-controlling film 20 is located and the first direction X is smaller than the principal axis angle). In addition, the angle between the orthographic projection of all the above-mentioned light rays converging around the principal optical axis M on the plane where the light-controlling film 20 is located and the first direction X is always in the range of 40° to 50°. In other words, the light passing through the light-controlling film 20 can be focused and emitted within an azimuth angle of 40° to 50°.

[0059] Since the extension directions of the prism strips in the first prism layer 31 and the second prism layer 32 are perpendicular to each other, the preferred input angles (PIA) corresponding to the first prism layer 31 and the second prism layer 32 are perpendicular. By using the light-controlling film 20 to converge the light emitted from the light-controlling film 20 into an azimuth angle between 40° and 50°, the light emitted from the light-controlling film 20 can simultaneously adapt to the PIA corresponding to the first prism layer 31 and the second prism layer 32. This allows more light to be directly emitted after passing through the first prism layer 31 and the second prism layer 32, thereby improving the light energy utilization rate and brightness of the backlight module.

[0060] It should be noted that the preferred angle of incidence refers to the angle at which light rays are incident on the corresponding prism layer and can then exit directly from the prism layer without reflection. For example, when light rays emitted through the light-controlling film 20 are incident on the first prism layer 31, if the light rays are incident at the preferred angle of incidence corresponding to the first prism layer 31, then the light rays can be refracted directly from the first prism layer 31 without being reflected back by the first prism layer 31.

[0061] When the light incident on the prism diaphragm 30 is not converged within an azimuth angle of 40° to 50°, the light typically only matches one prism layer of the prism diaphragm 30. When the light passes through another prism layer, most of it is reflected and recycled, resulting in significant light loss. Furthermore, some of the reflected light is not recycled and exits at a large angle, easily leading to large-angle light leakage in the backlight module and affecting its light output performance. Therefore, the backlight module 100 provided in this application overcomes these problems by using a light-controlling diaphragm to converge the light incident on the prism diaphragm 30 within an azimuth angle of 40° to 50°, thus ensuring good light energy utilization and light output brightness.

[0062] In some embodiments, the angle between the orthographic projection M' of the light emitted along the principal optical axis M onto the plane of the light-controlling diaphragm 20 and the first direction X is greater than or equal to 44° and less than or equal to 46°. That is, the azimuth angle of the principal optical axis M of the light emitted through the light-controlling diaphragm 20 is in the range of 44° to 46°. This ensures that most of the light rays converging on the principal optical axis M are emitted at an azimuth angle of 40° to 50°, thereby effectively ensuring good light energy utilization and light output brightness of the backlight module 100.

[0063] In some examples, the angle between the orthographic projection M' of the light emitted along the principal optical axis M onto the plane of the light-controlling diaphragm 20 and the first direction X can be 44°, 44.2°, 44.4°, 44.6°, 44.8°, 44.9°, 45°, 45.1°, 45.2°, 45.4°, 45.6°, 45.8°, 46°, etc., and this application does not impose any restrictions on it.

[0064] In some examples, the first prism layer 31 may further include a first prism substrate layer, with a plurality of first prism strips 311 arranged side by side on the first prism substrate layer. Exemplarily, the plurality of first prism strips 311 are located on the side of the first prism substrate layer away from the light-controlling film 20.

[0065] In some examples, the second prism layer 32 may further include a second prism substrate layer, with a plurality of second prism strips 321 arranged side by side on the second prism substrate layer. Exemplarily, the plurality of second prism strips 321 are located on the side of the second prism substrate layer away from the light-controlling film 20.

[0066] In other examples, the first prism layer 31 and the second prism layer 32 may share the same prism substrate layer. In this configuration, the plurality of first prism strips 311 and the plurality of second prism strips 321 are located on opposite sides of the prism substrate layer, respectively.

[0067] In some embodiments, as shown in FIG1, the light-controlling film 20 includes a substrate layer 21 and a plurality of light-controlling elements 22 located on the substrate layer 21.

[0068] As shown in Figures 3A and 3B, each light-controlling element 22 includes four side surfaces 222 connected end-to-end in sequence. Exemplarily, the four side surfaces 222 can be identical in shape and size. For example, as shown in Figure 3A, each side surface 222 is a triangle, and all sides of the triangle have the same length.

[0069] In some examples, as shown in Figures 3A and 4, the four sides 222 intersect at vertex P.

[0070] For example, as shown in FIG3A, the light control element 22 further includes a first surface 221 disposed opposite to the vertex P, and four side surfaces 222 connected to the four edges of the first surface 221. The first surface 221 is attached to the surface of the substrate layer 21. In this case, the light control element 22 protrudes from one side of the substrate layer 21, and each light control element 22 is in the shape of a regular square pyramid.

[0071] As another example, as shown in FIG4, the substrate layer 21 has a recess 211 corresponding to the light control element 22, the four sides 222 are attached to the sidewalls of the recess 211, and the vertex P is attached to the bottom of the recess 211. In this case, the light control element 22 is recessed in the recess 211 of the substrate layer 21, thereby playing the role of light control.

[0072] Since the light control element 22 is in the shape of a regular square pyramid, the light can converge in the range of azimuth angle between 40° and 50° after passing through the light control element 22. This allows the light to adapt to the PIA of the first prism layer 31 and the second prism layer 32 at the same time, thereby increasing the proportion of light directly emitted when passing through the first prism layer 31 and the second prism layer 32, and ultimately improving the light energy utilization and light output brightness of the backlight module 100.

[0073] In other examples, as shown in Figure 3B, each light control element 22 also includes a second surface 223, with four sides 222 connected to the four edges of the second surface 223.

[0074] For example, as shown in FIG3B, the light-controlling element 22 further includes a third surface 224 disposed opposite to the second surface 223. The area of ​​the second surface 223 is smaller than the area of ​​the third surface 224. The four sides 222 are connected to the four edges of the third surface 224, and the third surface 224 is attached to the surface of the substrate layer 21. In this case, the light-controlling element 22 protrudes from one side of the substrate layer 21, and each light-controlling element 22 is in the shape of a regular square frustum.

[0075] As another example, the substrate layer 21 has a recess 211 corresponding to the light-controlling element 22, the four sides 222 are attached to the sidewalls of the recess 211, and the second surface 223 is attached to the bottom of the recess 211. In this case, the light-controlling element 22 is recessed in the recess 211 of the substrate layer 21, thereby playing the role of light control.

[0076] Since the light control element 22 is in the shape of a regular square truncated pyramid, the light can be focused in the range of azimuth angle between 40° and 50° after passing through the light control element 22. This allows the light to adapt to the PIA of the first prism layer 31 and the second prism layer 32 at the same time, thereby increasing the proportion of light directly emitted when passing through the first prism layer 31 and the second prism layer 32, and ultimately improving the light energy utilization and light output brightness of the backlight module 100.

[0077] In some examples, multiple light-controlling elements 22 are arranged in an array on the substrate layer 21. This allows for good control of the light emitted from the light guide plate 11, thereby ultimately improving the light output performance of the backlight module 100.

[0078] In some examples, the light control element 22 can be integrally formed with the substrate layer 21.

[0079] In some embodiments, as shown in Figures 4 and 5, the light-controlling film 20 is further configured such that the exit angle of the light emitted through the light-controlling film 20 is α2, the first prism strip 311 includes a first prism surface 3111 and a second prism surface 3112 with the same shape and size, the apex angle between the first prism surface 3111 and the second prism surface 3112 is β1, and the refractive index of the first prism layer 31 is n1.

[0080] The exit angle of the light ray after exiting the first prism layer 31 is α1. According to the law of refraction, sinα1=n1×sinθ1, where θ1 is the angle between the light ray and the interface normal of the second prism surface 3112 when the light ray is incident on the second prism surface 3112.

[0081] When light enters the first prism layer 31 through the light-controlling film 20, the incident angle of the light entering the first prism layer 31 is the same as the exit angle α2 when the light exits through the light-controlling film 20. The angle of the light after entering the first prism layer 31 is θ2. According to the law of refraction, sinα2=n1×sinθ2.

[0082] Since the first prism surface 3111 and the second prism surface 3112 are identical, the cross-section of the first prism strip shown in Figure 4 is an isosceles triangle. By controlling the exit angle α2 of the light emitted through the light-controlling film 20, the light can be made to exit vertically through the first prism layer 31. Thus, by extending the light emitted vertically through the first prism layer 31 in the reverse direction, the following relationship can be obtained: 0.5×β1+α1=90°, α1=θ1+θ2. From this, the exit angle α2 can be calculated, thereby ensuring that the light ultimately exits vertically through the first prism layer 31.

[0083] In some embodiments, as shown in FIG1, a plurality of light control elements 22 are disposed on the side of the substrate layer 21 away from the light guide plate 11, and the light control film 20 further includes a third prism layer 23 located on the side of the substrate layer 21 close to the light guide plate 11, the third prism layer 23 including a plurality of third prism strips arranged side by side.

[0084] By setting a third prism layer, multiple third prism strips can be used to deflect and gather the light emitted from the light guide plate 11 in a vertical direction, thereby reducing the angle at which the light is emitted from the light control film 20. This allows more light to be emitted vertically from the prism film 30, reducing large-angle light leakage and reflected light entering the recycling process, and improving the light efficiency and brightness of the backlight module.

[0085] In some embodiments, as shown in FIG1, the light guide plate 11 further has a dimming side 113 disposed opposite to the light emitting side 112. The light emitting side 112 is located on the side of the light guide plate 11 closer to the light control film 20, while the dimming side 113 is located on the side of the light guide plate 11 away from the light control film 20.

[0086] In some examples, the material of the light guide plate 11 can be polycarbonate or polymethyl methacrylate, etc.

[0087] The light source 12 may include a plurality of light-emitting units arranged side by side along the second direction Y. For example, each light-emitting unit may be a light-emitting diode.

[0088] In some examples, multiple third prism strips can be arranged side by side along the second direction Y, with each third prism strip extending along the first direction X.

[0089] In some embodiments, as shown in FIG1, the backlight module 100 further includes a fourth prism layer 14 disposed on the light guide plate 11 and located on the light emitting side 112 of the light guide plate 11, the fourth prism layer 14 including a plurality of fourth prism strips arranged side by side.

[0090] By setting a fourth prism layer, multiple fourth prism strips can be used to deflect and gather the light emitted from the light guide plate 11 in a vertical direction, thereby reducing the angle at which the light enters the light control film 20. This allows more light to be emitted vertically from the prism film 30, reducing large-angle light leakage and the reflected light entering the recycling process, thus improving the light efficiency and brightness of the backlight module.

[0091] In some examples, multiple fourth prism strips can be arranged side by side along the second direction Y, with each fourth prism strip extending along the first direction X.

[0092] In some examples, the height of each prism strip (i.e., the distance between the vertex and the base of the prism strip) can be greater than or equal to 1 μm and less than or equal to 10 μm, and the width of each prism strip (i.e., the dimension of the prism strip along its extension direction) can be greater than or equal to 10 μm and less than or equal to 200 μm.

[0093] In some examples, the fourth prism strip can be a prism structure. In other examples, the fourth prism strip can also be a hemispherical structure.

[0094] In some embodiments, as shown in FIG1, the backlight module 100 further includes a dimming element layer 13 located on the side of the light guide plate 11 away from the light control film 20 (i.e., the dimming side 113 of the light guide plate 11), the dimming element layer 13 being configured to reflect light incident on the dimming element layer 13 toward the light control film 20.

[0095] By setting the dimming element layer 13, the light from the light source 12 directed towards the dimming element layer 13, as well as the light reflected from the light-emitting side 112 of the light guide plate 11 towards the dimming element layer 13, can be effectively reflected, causing it to exit from the light-emitting side 112 of the light guide plate 11 and enter the light-controlling film 20. This improves the light energy utilization rate, thereby enhancing the luminous efficiency and brightness of the backlight module 100.

[0096] In some embodiments, as shown in FIG4, the exit angle of the light rays after passing through the light guide plate 11 is α3, and the refractive index of the light-controlling film 20 is n2. When the incident angle when the light rays enter the light-controlling film 20 and the exit angle when they exit the light-controlling film 20 are the same and both are α2, sinα3 = n2 × sinα2. Since the magnitude of the angle α2 has been known above, the magnitude of the angle α3 can be calculated here.

[0097] For example, when n1 and n2 are the same and both are 1.63, when β1 = 90°, α3 = 65°. Therefore, by controlling the exit angle α3 of the light emitted through the light guide plate 11 to be 65°, the light can be emitted vertically from the prism diaphragm 30, thereby reducing large-angle light leakage and reflected light entering the recycling process. This improves the luminous efficiency and brightness of the backlight module 100 and reduces its power consumption, thus meeting the requirements of high luminous efficiency, high brightness, and low power consumption for the backlight module 100.

[0098] It should be noted that, as shown in Figure 4, the included angle between two opposite sides of the four sides of the light control element 22 is β2. When the light is emitted perpendicularly to one of the sides, β2 = 2 × (90° - α2).

[0099] In some examples, the refractive index of both the light guide plate 11 and the dimming element layer 13 is n3. When the light is reflected from the dimming element layer 13 to the light-emitting surface of the light guide plate 11, the angle between the light ray and the interface normal of the light-emitting surface is θ3. Therefore, during the light ray's emission from the light guide plate 11, according to the law of refraction, sinα3 = n3 × sinθ3. Thus, the angle θ3 between the light ray and the interface normal of the light-emitting side 112 can be calculated.

[0100] In some embodiments, as shown in FIG6, the dimming element layer 13 includes a plurality of dimming elements 131, each dimming element 131 being configured to reflect light passing through the dimming element 131 toward the light-controlling film 20. The dimming element layer 13 has a first region A1 and a second region A2 arranged sequentially in a direction away from the light source 12, wherein the density of dimming elements 131 in the first region A1 is less than the density of dimming elements 131 in the second region A2.

[0101] Since the brightness of the light guide plate 11 on the side closer to the light source 12 is greater than that on the side farther away from the light source 12, increasing the density of the dimming element 131 in the second region A2 helps to improve the brightness of the light guide plate 11 in the corresponding second region A2, thereby improving the brightness uniformity of the light guide plate 11.

[0102] It should be noted that the first region A1 and the second region A2 may partially overlap or not overlap.

[0103] In some embodiments, the density of dimming elements 131 in different regions gradually increases in the direction away from the light source 12, which is beneficial to further improve the brightness uniformity of the light guide plate 11.

[0104] In some embodiments, as shown in Figures 4 and 7, the dimming element layer 13 includes a plurality of dimming elements 131, each dimming element 131 including an interconnected curved surface 1311 and a first plane 1312, the first plane 1312 being attached to the light guide plate 11, and the curved surface 1311 being configured to reflect light incident on the curved surface 1311 toward the light control film 20.

[0105] With this configuration, the curved surface 1311 of the dimming element 131 is used as a reflective surface, which can effectively reflect light toward the light-controlling film 20, thereby improving the light energy utilization rate.

[0106] In some examples, the dimming element 131 may be disposed protruding relative to the light guide plate 11, in which case the curved surface of the dimming element 131 protrudes in a direction away from the light guide plate 11.

[0107] In some examples, the dimming element layer 13 can be integrally formed with the light guide plate 11. This facilitates the fabrication of the dimming element layer 13 and improves the connection stability between the dimming element layer 13 and the light guide plate 11.

[0108] In some embodiments, as shown in Figures 4 and 7, the curved surface 1311 is a spherical curved surface, the first plane 1312 is a circular plane, the depth b of the dimming element 131 is the maximum distance between the curved surface 1311 and the first plane 1312, and the width a of the dimming element 131 is the diameter of the circular plane.

[0109] In some examples, the ratio of depth b to width a of dimming element 131 is greater than or equal to 0.04 and less than or equal to 0.08.

[0110] By simulating the light intensity and viewing angle of the light guide plate 11 corresponding to the dimming element 131 with different aspect ratios (i.e., the ratio of depth to width), for example, by performing simulation using Lighttools optical simulation software, the curves shown in Figure 8 can be obtained. As can be seen from Figure 8, when the aspect ratio is in the range of 0.04 to 0.08, the viewing angle of the light guide plate 11 can be concentrated in the range of 50° to 80°. Therefore, by limiting the aspect ratio of the dimming element 131 within the above range, directional light emission from the light guide plate 11 can be achieved, concentrating its emission angle in the range of 50° to 80°. In some examples, when the dimming element layer 13 is provided, the emission angle of the light guide plate 11 is concentrated in the 30° angle range (e.g., the emission angle of the light guide plate is concentrated in the range of 50° to 80°).

[0111] In some examples, the plurality of dimming elements 131 include a first dimming element 1301 and a second dimming element 1302 arranged sequentially in a direction away from the light source 12, wherein the ratio of the depth to the width of the first dimming element 1301 is less than the ratio of the depth to the width of the second dimming element 1302.

[0112] As shown in Figure 8, within the aspect ratio range of 0.04 to 0.08, the smaller the aspect ratio, the larger the angle of concentration of the light guide plate. Therefore, by setting the aspect ratio of the first dimming element 1301 to be smaller than that of the second dimming element 1302, it is beneficial to make the light emission angle of the entire surface of the light guide plate more consistent, thereby improving the luminous efficiency and brightness of the light guide plate, and thus improving the light emission uniformity of the backlight module 100.

[0113] In some examples, the aspect ratio of the first dimming element 1301 is 0.04, and the aspect ratio of the second dimming element 1302 is 0.06.

[0114] For example, the second dimming element 1302 is provided with a first edge dimming element on the side away from the first dimming element 1301, and the aspect ratio of the first edge dimming element is 0.08.

[0115] In some examples, multiple second dimming elements 1302 are provided, and all of the multiple second dimming elements 1302 are located in the central region of the dimming element layer 13. For example, the central region refers to the middle 1 / 3 of the dimming element layer 13, that is, the area on the side of the dimming element layer 13 facing the light source 12 and the area on the side away from the light source 12 along the direction of the dimming element layer 13 towards or away from the light source 12 (i.e., the first direction X in FIG. 1) together constitute the aforementioned central region.

[0116] With this configuration, when the aspect ratio of the dimming element is 0.06, the viewing angle of the light emitted by the light guide plate 11 is concentrated at 65°. This controls most of the light to be concentrated at the emission angle α3 when it passes through the light guide plate 11, allowing the light guide plate 11 to emit light in a directional manner. This enables the light to be emitted vertically from the prism diaphragm 30, thereby reducing large-angle light leakage and reflected light entering the recycling process. This improves the luminous efficiency and brightness of the backlight module 100, while also reducing the power consumption of the backlight module 100.

[0117] In some examples, the ratio of the depth to the width of the dimming element 131 (i.e., the aspect ratio) gradually increases in the direction away from the light source 12, which helps to further improve the brightness uniformity of the light guide plate 11.

[0118] In some examples, the depth b of the dimming element 131 can be greater than or equal to 1 μm and less than or equal to 10 μm. The width a of the dimming element 131 can be greater than or equal to 1 μm and less than or equal to 100 μm, as long as the aspect ratio of the dimming element 131 is within the range of 0.04 to 0.08.

[0119] Experimental verification, as shown in Figures 9 to 11, shows that for the light guide plate in the embodiment of this application with a dimming element (optimized dots shown in the figure) having a dimming side with an aspect ratio of 0.06, compared to the light guide plate in related technologies with a conventional reflective dot structure (ordinary dots shown in the figure) on the back side, the light emission angle of the light guide plate can be compressed from 50° to 31°, and the light emission angle of the light guide plate is mainly concentrated in the range of 50° to 80° (as shown in Figure 9). In addition, as shown in Figures 10 and 11, the half-peak width of the backlight in the H direction (e.g., the H direction is consistent with the first direction X) and V direction (e.g., the V direction is consistent with the second direction Y) is compressed from 40° to 30°. Finally, the measured backlight brightness of the light guide plate in the embodiment of this application can be improved by approximately 44%. Therefore, the backlight module provided in the embodiments of this application significantly improves the backlight efficiency and brightness, effectively reduces backlight power consumption, and narrows the backlight viewing angle, thereby meeting the current needs of high-brightness and low-power display devices.

[0120] In some embodiments, as shown in FIG5 and FIG12, the dimming element layer 13 includes a plurality of dimming elements 131. Each dimming element 131 includes a second plane 1313, a transition surface 1314 and a third plane 1315 connected end to end in sequence. The second plane 1313 is attached to the light guide plate 11, and the third plane 1315 is configured to reflect the light incident on the third plane 1315 toward the light control film 20.

[0121] With this configuration, the third plane 1315 of the dimming element 131 is used as a reflective surface, which can effectively reflect light toward the light-controlling film 20, thereby improving the light energy utilization rate.

[0122] In some examples, the dimming element 131 may be disposed protruding relative to the light guide plate 11, in which case the third plane 1315 and the transition surface 1314 protrude in a direction away from the light guide plate 11.

[0123] In some examples, the dimming element layer 13 can be integrally formed with the light guide plate 11. This facilitates the fabrication of the dimming element layer 13 and improves the connection stability between the dimming element layer 13 and the light guide plate 11.

[0124] For example, the transition surface 1314 can be a plane, thus making the dimming element 131 form a triangular prism structure.

[0125] In some embodiments, as shown in Figures 5 and 12, a base angle β3 is formed between the second plane 1313 and the third plane 1315. The opening direction of the base angle β3 is towards the direction close to the light source 12.

[0126] In some examples, the base angle β3 is greater than or equal to 2° and less than or equal to 3°.

[0127] In this case, the viewing angle of the light guide plate 11 can be concentrated in the range of 50° to 80°. Therefore, by limiting the bottom angle β3 of the dimming element 131 within the above range, the light guide plate 11 can be directionally emitted, so that its emission angle is concentrated in the range of 50° to 80°.

[0128] In some examples, the plurality of dimming elements 131 include a third dimming element 1303 and a fourth dimming element 1304 arranged sequentially in a direction away from the light source 12, wherein the bottom angle β3 in the third dimming element 1303 is smaller than the bottom angle β3 in the fourth dimming element 1304.

[0129] As shown in Figure 5, when the bottom angle β3 increases, the angle θ3 between the interface normal of the light-emitting surface of the light guide plate 11 decreases, thus reducing the emission angle α3 of the light emitted from the light guide plate 11. Therefore, by setting the bottom angle β3 in the third dimming element 1303 to be smaller than the bottom angle β3 in the fourth dimming element 1304, it is beneficial to make the light emission angle of the entire surface of the light guide plate 11 more consistent, thereby improving the luminous efficiency and brightness of the light guide plate 11, and further improving the uniformity of light emission from the backlight module 100.

[0130] In some embodiments, as shown in FIG5, the critical angle of the light-emitting surface of the light guide plate 11 is θ4, and the refractive index of both the light guide plate 11 and the dimming element layer 13 is n3. According to the path of light propagation in the light guide plate 11 and the dimming element layer 13 in FIG5, sinα3 = n3sinθ3, and θ3 = θ4 - 2β3. When n3 = 1.58 and θ4 = 39.2°, β3 = 2.5° can be calculated. That is, when the bottom angle β3 between the second plane 1313 and the third plane 1315 in the dimming element layer 13 is 2.5°, the light can be vertically emitted from the prism diaphragm 30, thereby reducing large-angle light leakage and the reflected light entering the recycling, thus improving the luminous efficiency and brightness of the backlight module 100 and reducing the power consumption of the backlight module 100. This can meet the requirements of high luminous efficiency, high brightness and low power consumption of the backlight module 100.

[0131] In some examples, the bottom angle β3 in the third dimming element 1303 is 2°, and the bottom angle β3 in the fourth dimming element 1304 is 2.5°.

[0132] For example, the fourth dimming element 1304 is provided with a second side dimming element on the side away from the third dimming element 1303, and the bottom angle β3 of the second side dimming element is 3°.

[0133] In some examples, multiple fourth dimming elements 1304 are provided, and all of the multiple fourth dimming elements 1304 are located in the central region of the dimming element layer 13. For example, the central region refers to the middle 1 / 3 of the dimming element layer 13.

[0134] With this configuration, when the bottom angle β3 in the dimming element is 2.5°, the viewing angle of the light emitted by the light guide plate 11 is concentrated at 65°. This can control most of the light to be concentrated at the emission angle α3 when it passes through the light guide plate 11, so that the light guide plate 11 can emit light in a directional manner. This allows the light to be emitted vertically from the prism diaphragm 30, thereby reducing large-angle light leakage and reflected light entering the recycling process, thus improving the light efficiency and brightness of the backlight module 100, while also reducing the power consumption of the backlight module 100.

[0135] In some examples, the bottom angle β3 in the dimming element 131 gradually increases in the direction away from the light source 12, which helps to further improve the uniformity of the light output brightness of the light guide plate 11.

[0136] In some examples, as shown in Figure 12, the height f of the dimming element 131 (i.e., the distance between the boundary line of the transition surface 1314 and the third plane 1315 and the second plane 1313) can be greater than or equal to 1 μm and less than or equal to 50 μm. The width g of the dimming element 131 (i.e., the distance between the boundary line of the transition surface 1314 and the second plane 1313 and the boundary line of the third plane 1315 and the second plane 1313) can be greater than or equal to 10 μm and less than or equal to 150 μm.

[0137] In some examples, as shown in Figure 13, the length of the dimming element 131 is the same as the length of the light guide plate 11 along the arrangement direction of the multiple light-emitting units in the light source 12. For example, the length of the dimming element 131 may be less than or equal to the length of the light guide plate 11. In this case, there is only one dimming element 131 along the length direction of the light guide plate 11.

[0138] In other examples, as shown in Figure 14, multiple dimming elements 131 are spaced apart along the arrangement direction of the multiple light-emitting units in the light source 12. That is, the length of the dimming element 131 is less than the length of the light guide plate 11, and there are multiple dimming elements 131 along the length of the light guide plate 11. In some examples, the density of dimming elements 131 on the side closer to the light source 12 is smaller than the density of dimming elements 131 on the side farther from the light source 12 along the length of the light guide plate 11. Since the brightness of the side of the light guide plate 11 closer to the light source 12 is greater than the brightness of the side farther from the light source 12, increasing the density of dimming elements 131 on the side farther from the light source 12 helps to improve the brightness of the side of the light guide plate 11 away from the light source 12, thereby improving the brightness uniformity of the light guide plate 11.

[0139] In some embodiments, as shown in FIG1, the backlight module 100 further includes a reflective film 15 located on the side of the dimming element layer 13 away from the light guide plate 11. The reflective film 15 can reflect light that is not reflected by the dimming element layer 13 into the light guide plate 11 and out of the light guide plate 11, thereby further improving the light energy utilization of the backlight module 100.

[0140] Some embodiments of this application also provide a display device, as shown in FIG15, the display device 300 including the backlight module 100 described in any of the above embodiments.

[0141] Since it includes the backlight module 100, the display device 300 has all the technical effects of the backlight module 100 described above, which will not be repeated here.

[0142] In some examples, the display device 300 also includes a display panel 200 located on the light-emitting surface of the backlight module 100. This enables the display function of the display device 300.

[0143] In summary, although the present application discloses the preferred embodiments as described above, the above preferred embodiments are not intended to limit the present application. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application is based on the scope defined by the claims.

Claims

1. A backlight module, comprising: a light guide plate; a light source located at an incident light side of the light guide plate; a light control film located at an emergent light side of the light guide plate; and a prism film located at a side of the light control film away from the light guide plate, the prism film comprising a first prism layer and a second prism layer arranged in a direction away from the light control film, the first prism layer comprising a plurality of first prism strips arranged side by side in a first direction, each of the first prism strips extending in a second direction, the first direction and the second direction being perpendicular to each other, the second prism layer comprising a plurality of second prism strips arranged side by side in the second direction, each of the second prism strips extending in the first direction; wherein the light control film is configured to converge light rays incident on the light control film to a principal axis and emit the light rays toward the prism film, the light rays converged to the principal axis having an angle between a normal projection of the light control film and the first direction greater than or equal to 40° and less than or equal to 50°. The light control film is further configured to converge light rays incident on the light control film to a principal axis and emit the light rays toward the prism film, the light rays emitted along the principal axis having an angle between a normal projection of the light control film and the first direction greater than or equal to 44° and less than or equal to 46°.

2. The backlight module of claim 1, wherein, The light control film comprises a substrate layer and a plurality of light control elements located on the substrate layer, each of the light control elements comprising four side surfaces sequentially and circularly connected, and four vertexes formed by the intersection of the four side surfaces, wherein 3. The backlight module of claim 1, wherein, the substrate layer is provided with recesses corresponding to the light control elements, the four side surfaces are attached to the side walls of the recesses, and the vertexes are attached to the bottoms of the recesses; or the light control elements further comprise a first surface located opposite to the vertexes, the four side surfaces are connected to the four edges of the first surface, and the first surface is attached to the surface of the substrate layer. The light control film comprises a substrate layer and a plurality of light control elements located on the substrate layer, each of the light control elements comprising a second surface and four side surfaces sequentially and circularly connected, and the four side surfaces being connected to the four edges of the second surface, wherein 4. The backlight module of claim 1, wherein, the substrate layer is provided with recesses corresponding to the light control elements, the four side surfaces are attached to the side walls of the recesses, and the second surface is attached to the bottoms of the recesses; or the light control elements further comprise a third surface located opposite to the second surface, the area of the second surface is smaller than that of the third surface, the four side surfaces are connected to the four edges of the third surface, and the third surface is attached to the surface of the substrate layer. The plurality of light control elements are located at a side of the substrate layer away from the light guide plate, and the light control film further comprises a third prism layer located at a side of the substrate layer close to the light guide plate, the third prism layer comprising a plurality of third prism strips arranged side by side.

5. The backlight module of claim 3 or 4, wherein, The backlight module further comprises a fourth prism layer arranged on the light guide plate and located at an emergent light side of the light guide plate, the fourth prism layer comprising a plurality of fourth prism strips arranged side by side.

6. The backlight module of claim 5, wherein, ​ 7. The backlight module of any of claims 1-4, wherein, The backlight module further comprises a light adjusting element layer located on a side of the light guide plate away from the light control film sheet, and the light adjusting element layer is configured to reflect light incident on the light adjusting element layer towards the direction of the light control film sheet.

8. The backlight module of claim 7, wherein, The light adjusting element layer comprises a plurality of light adjusting elements, and the light adjusting elements are configured to reflect light incident on the light adjusting elements towards the direction of the light control film sheet. The light adjusting element layer has a first region and a second region arranged in a direction away from the light source, and the density of the light adjusting elements in the first region is less than the density of the light adjusting elements in the second region.

9. The backlight module of claim 7, wherein, The light adjusting element layer comprises a plurality of light adjusting elements, and each light adjusting element comprises a curved surface and a first plane connected to each other, the first plane is arranged in close contact with the light guide plate, and the curved surface is configured to reflect light incident on the curved surface towards the direction of the light control film sheet.

10. The backlight module of claim 9, wherein, The curved surface is a spherical curved surface, the first plane is a circular plane, the depth of the light adjusting element is the maximum distance between the curved surface and the first plane, and the width of the light adjusting element is the diameter of the circular plane.

11. The backlight module of claim 9, wherein, The curved surface is a spherical curved surface, the first plane is a circular plane, the depth of the light adjusting element is the maximum distance between the curved surface and the first plane, and the width of the light adjusting element is the diameter of the circular plane. The plurality of light adjusting elements comprises a first light adjusting element and a second light adjusting element arranged in a direction away from the light source, and the ratio of the depth to the width of the first light adjusting element is less than the ratio of the depth to the width of the second light adjusting element.

12. The backlight module of claim 7, wherein, The light adjusting element layer comprises a plurality of light adjusting elements, and each light adjusting element comprises a second plane, a transition surface and a third plane connected to each other in sequence, the second plane is arranged in close contact with the light guide plate, and the third plane is configured to reflect light incident on the third plane towards the direction of the light control film sheet.

13. The backlight module of claim 12, wherein, The second plane and the third plane have a base angle therebetween, and the base angle is greater than or equal to 2° and less than or equal to 3°.

14. The backlight module of claim 12, wherein, The second plane and the third plane have a base angle therebetween, and the plurality of light adjusting elements comprises a third light adjusting element and a fourth light adjusting element arranged in a direction away from the light source, and the base angle in the third light adjusting element is less than the base angle in the fourth light adjusting element.

15. The backlight module of claim 7, wherein, The light adjusting element layer comprises a plurality of light adjusting elements, and the light adjusting elements are configured to reflect light passing through the light adjusting elements towards the direction of the light control film sheet, and the light source comprises a plurality of light emitting units arranged side by side, and along the arrangement direction of the plurality of light emitting units, the length of the light adjusting elements is consistent with the length of the light guide plate, or the plurality of light adjusting elements are arranged at intervals.

16. A display device comprising a backlight module, the backlight module comprising: a light guide plate; a light source located on the light incident side of the light guide plate; a light control film sheet located on the light exit side of the light guide plate; and ​ A prism film is located on a side of the light control film away from the light guide plate, the prism film comprises a first prism layer and a second prism layer arranged in a direction away from the light control film, the first prism layer comprises a plurality of first prism strips arranged side by side in a first direction, each of the first prism strips extends in a second direction, the first direction and the second direction are perpendicular to each other, the second prism layer comprises a plurality of second prism strips arranged side by side in the second direction, each of the second prism strips extends in the first direction; The light control film is configured to converge light rays incident on the light control film on a principal optical axis and emit toward the prism film, the angle between the normal projection of the light rays converged on the principal optical axis on the plane where the light control film is located and the first direction is greater than or equal to 40° and less than or equal to 50°.

17. The display device of claim 16, wherein, The light control film is further configured to converge light rays incident on the light control film on a principal optical axis and emit toward the prism film, and the angle between the normal projection of the light rays emitted along the principal optical axis on the plane where the light control film is located and the first direction is greater than or equal to 44° and less than or equal to 46°.

18. The display device of claim 16, wherein, The light control film comprises a substrate layer and a plurality of light control elements on the substrate layer, each of the light control elements comprises four side surfaces connected in sequence and end to end, and the four side surfaces intersect at a vertex. The substrate layer is provided with recesses corresponding to the light control elements, the four side surfaces are fitted to the side walls of the recesses, and the vertex is fitted to the bottom of the recess; or The light control element further comprises a first surface arranged opposite to the vertex, the four side surfaces are connected to the four edges of the first surface, and the first surface is fitted to the surface of the substrate layer.

19. The display device of claim 16, wherein, The light control film comprises a substrate layer and a plurality of light control elements on the substrate layer, each of the light control elements comprises a second surface and four side surfaces connected in sequence and end to end, and the four side surfaces are connected to the four edges of the second surface. The substrate layer is provided with recesses corresponding to the light control elements, the four side surfaces are fitted to the side walls of the recesses, and the second surface is fitted to the bottom of the recess; or The light control element further comprises a third surface arranged opposite to the second surface, the area of the second surface is smaller than the area of the third surface, the four side surfaces are connected to the four edges of the third surface, and the third surface is fitted to the surface of the substrate layer.

20. A display device according to claim 18 or 19, wherein, A plurality of the light control elements are arranged on a side of the substrate layer away from the light guide plate, and the light control film further comprises a third prism layer on a side of the substrate layer close to the light guide plate, the third prism layer comprises a plurality of third prism strips arranged side by side.

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