BACKLIGHT MODULE AND DISPLAY DEVICE

Abstract

The present application relates to a backlight module and a display device, the backlight module (1) comprising a back plate (11) and a reflector (12) disposed on the back plate (11), and further comprising a brightness enhancing film (13), a magneto-optical medium film (14) and a magnetic member (15), the magnetic member (15) being located between the back plate (11) and the reflector (12), the magneto-optical medium film (14) being located between the magnetic member (15) and the brightness enhancing film (13), the brightness enhancing film (13) being a second The backlight module is used to transmit linearly polarized light in one direction and reflect linearly polarized light in a second direction, the magnetic member generates a magnetic field parallel to a first direction (X) to rotate the polarization direction of linearly polarized light in a second direction (Y) after it passes through a magneto-optical medium film (14) located in the magnetic field, the reflector (12) is used to reflect the rotated linearly polarized light, the first direction (X) is the light output direction of the backlight module (1), and the second direction (Y) is perpendicular to the first direction (X). The backlight module can greatly improve the polarization efficiency of the brightness enhancement film (13), reduce the light wasted by the absorption of each film layer, and improve the utilization rate of the backlight.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims priority to Chinese patent application No. 202210533173.4, entitled "Backlight Module and Display Device," filed on May 12, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the technical field of displays, and in particular to backlight modules and display devices. [Background technology]

[0003] A display device generally includes a liquid crystal display panel (abbreviated as LCD) and a backlight module. The backlight module is disposed on the backlight side of the LCD and is used to provide a light source to the LCD to display an image.

[0004] The backlight transmittance of LCD is often only about 5%, and when the contrast is increased, the transmittance is often lower, in which case a brighter backlight is required. Currently, LCDs use polarizing brightness enhancement films (abbreviated as DBEF), which allow the component of the natural light emitted by the backlight module in the same direction as the transmission axis of the lower polarizer of the LCD to pass through, while the perpendicular component returns to the backlight, and the returned light energy is reflected and refracted multiple times to become natural light again, so that a part of it can pass through the DBEF, and this part of the energy can be recovered and used. However, the polarized light reflected and returned by the DBEF must be reflected and refracted multiple times before some of the energy can be converted to the target polarization direction, and during that time the energy is repeatedly absorbed by each layer of film, resulting in a lot of waste, which limits the ability of DBEF to improve the utilization rate of the backlight. Summary of the Invention [Problem to be solved by the invention]

[0005] The present application aims to provide a backlight module and a display device that can significantly improve the polarization efficiency of a brightness enhancement film, reduce the waste of light due to absorption by each film layer, and improve the utilization rate of the backlight. [Means for solving the problem]

[0006] According to a first aspect, an embodiment of the present application proposes a backlight module comprising a back panel and a reflector disposed on the back panel, further comprising a brightness enhancement film, a magneto-optical medium film and a magnetic member, the magnetic member being located between the back panel and the reflector, the magneto-optical medium film being located between the magnetic member and the brightness enhancement film, the brightness enhancement film being used to transmit linearly polarized light in a first direction and reflect linearly polarized light in a second direction, the magnetic member being used to generate a magnetic field parallel to the first direction, thereby rotating the polarization direction of the linearly polarized light in the second direction after it passes through the magneto-optical medium film located in the magnetic field, the reflector being used to reflect the linearly polarized light after being rotated, the first direction being the light output direction of the backlight module, and the second direction being perpendicular to the first direction.

[0007] According to a second aspect, an embodiment of the present application further proposes a display device including a liquid crystal display panel, and the backlight module, which is provided on a backlight surface side of the liquid crystal display panel, for supplying a light source to the liquid crystal display panel. Effect of the Invention

[0008] According to the backlight module and display device of the embodiment of the present application, the backlight module has a magnetic member between a rear panel and a reflector, and a magneto-optical medium film between the magnetic member and the brightness enhancement film, so that the brightness enhancement film can transmit linearly polarized light in a first direction and reflect linearly polarized light in a second direction. The magnetic member generates a magnetic field parallel to the first direction, so that the polarization direction of the linearly polarized light in the second direction can be rotated after the linearly polarized light in the second direction passes through the magneto-optical medium film located in the magnetic field. The reflector is used to reflect the rotated linearly polarized light, so that most of the linearly polarized light in the second direction reflected by the brightness enhancement film can be converted into linearly polarized light in the first direction that can pass through the brightness enhancement film, which greatly improves the polarization efficiency of the brightness enhancement film, reduces the waste caused by the light absorption by each film layer, and improves the utilization rate of the backlight.

[0009] Hereinafter, the features, advantages and technical effects of the exemplary embodiments of the present application will be described with reference to the drawings. In the drawings, the same elements are designated by the same reference numerals. The drawings are not drawn to scale, but are merely used to illustrate the relative positional relationship. The layer thicknesses of some parts are exaggerated for easy understanding, and the layer thicknesses in the drawings do not represent the scale relationship of the actual layer thicknesses. [Brief description of the drawings]

[0010] [Figure 1] 1 shows a structural schematic diagram of a backlight module according to a first embodiment of the present application and a display device including the backlight module; [Diagram 2] 1 is a schematic diagram of an optical path of a backlight module according to a first embodiment of the present application; [Diagram 3] 1 shows a structural schematic diagram of a backlight module according to a second embodiment of the present invention and a display device including the backlight module; [Figure 4] 13 is a structural schematic diagram of a backlight module according to a third embodiment of the present application and a display device including the backlight module; [Diagram 5]13 is a structural schematic diagram of a backlight module according to a fourth embodiment of the present invention and a display device including the backlight module; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The features and exemplary embodiments of each aspect of the present application will be described in detail below. In the following detailed description, many details are proposed to fully understand the present application. However, it is obvious to those skilled in the art that the present application can be implemented without the need for some of these specific details. The following description of the embodiments is merely for the purpose of better understanding the present application by showing examples of the present application. In the drawings and the following description, at least some of well-known structures and techniques are not shown in order to avoid unnecessarily obscuring the present application, and the sizes of regions and structures may be exaggerated for clarity. In addition, the features, structures, or characteristics described below can be appropriately combined in one or more embodiments.

[0012] Hereinafter, specific structures of backlight modules and display devices including the backlight modules according to embodiments of the present application will be described with reference to the drawings.

[0013] First Example FIG. 1 shows a structural schematic diagram of a backlight module and a display device according to a first embodiment of the present application, and FIG. 2 shows a schematic diagram of an optical path of the backlight module according to the first embodiment of the present application.

[0014] A liquid crystal display device typically comprises a liquid crystal display panel 2 and a backlight module 1. The liquid crystal display panel 2 is a non-emissive light-receiving element. The backlight module 1 is provided on the backlight side of the liquid crystal display panel 2 and is used to supply a light source to the liquid crystal display panel 2 so as to display an image on the liquid crystal display panel 2.

[0015] The liquid crystal display panel 2 may be a single display panel, or a dual display panel that is laminated in the thickness direction. When the liquid crystal display panel 2 is a dual display panel, the display panel located at the lower layer is used for light control, and the display panel located at the upper layer is used for display, thus improving the contrast of the display device. For convenience of explanation, each embodiment of the present application will be explained taking as an example that the liquid crystal display panel 2 is a single display panel.

[0016] The liquid crystal display panel 2 includes an array substrate 22, a color filter substrate 23 facing the array substrate 22, and a liquid crystal layer between the array substrate 22 and the color filter substrate 23. The liquid crystal layer includes a large number of liquid crystal molecules, which are generally rod-shaped and can flow like a liquid, but also have certain crystalline characteristics. When the liquid crystal molecules are in an electric field, their alignment direction changes according to the change in the electric field. The liquid crystal display panel 2 applies a driving voltage to the array substrate 22 and the color filter substrate 23 to control the rotation of the liquid crystal molecules in the liquid crystal layer, thereby refracting the light provided by the backlight module 1 to generate a screen.

[0017] The display device further includes an upper polarizing plate 24 located on the light output surface side of the liquid crystal display panel 2, a lower polarizing plate 21 located on the backlight surface side of the liquid crystal display panel 2, and a cover plate (not shown) located on the side of the upper polarizing plate 24 away from the liquid crystal display panel 2. The lower polarizing plate 21 and the upper polarizing plate 24 polarize the light incident on the liquid crystal display panel 2, so that only light vibrating in one direction can be transmitted.

[0018] As shown in FIG. 1, the backlight module 1 according to the first embodiment of the present invention includes a back plate 11, a reflector 12 provided on the back plate 11, a brightness enhancing film 13, a magneto-optical medium film 14, and a magnetic member 15.

[0019] The magnetic member 15 is located between the back panel 11 and the reflector 12, the magneto-optical medium film 14 is located between the magnetic member 15 and the brightness enhancement film 13, the brightness enhancement film 13 is used to transmit linearly polarized light in a first direction X and reflect linearly polarized light in a second direction Y, the magnetic member 15 is used to generate a magnetic field parallel to the first direction X, so as to rotate the polarization direction of the linearly polarized light in the second direction Y after it passes through the magneto-optical medium film 14 located in the magnetic field, and the reflector 12 is used to reflect the rotated linearly polarized light, the first direction X is the light output direction of the backlight module 1, and the second direction Y is perpendicular to the first direction X.

[0020] The backlight module 1 further includes a light source 16, and the light emitted by the light source 16 is natural light. The brightness enhancement film 13 has a polarizing property and can pass only light components whose vibration direction is parallel to the polarized light transmission direction. Thus, the light energy in the same direction as the transmission axis of the lower polarizer 21 of the liquid crystal display panel 2 in natural light (i.e., the first direction X) passes through the brightness enhancement film 13 and is used for display on the liquid crystal display panel 2, while the light energy perpendicular to the transmission axis of the lower polarizer 21 in natural light (i.e., the second direction Y perpendicular to the paper surface) is reflected by the brightness enhancement film 13, so that the linearly polarized light in the second direction Y generates a magneto-optical effect when it passes through the magneto-optical medium film 14 in a magnetic field parallel to the first direction X generated by the magnetic member 15, and the magneto-optical effect is the Faraday rotation magneto-optical effect.

[0021] 2, the magnetic member 15 has an N pole and an S pole arranged opposite each other in the thickness direction, and a magnetic field direction parallel to the first direction X can be generated between the N pole and the S pole. When the N pole is located on the lower surface of the magnetic member 15 and the S pole is located on the upper surface of the magnetic member 15, the magnetic field direction may be a reverse magnetic field direction from bottom to top, and when the N pole is located on the upper surface of the magnetic member 15 and the S pole is located on the lower surface of the magnetic member 15, the magnetic field direction may be a forward magnetic field direction from top to bottom.

[0022] According to the Faraday rotation magneto-optical effect, the polarization direction of the linearly polarized light in the second direction Y that is not transmitted through the brightness enhancement film 13 rotates after passing through the magneto-optical medium film 14 located in the magnetic field. As shown in FIG. 2, the solid dots are the vibration direction of the linearly polarized light that is not transmitted through the polarized light, that is, the second direction Y perpendicular to the paper surface, and the hollow arrows are the rotation direction of the linearly polarized light. If the rotation angle is θ1, the linearly polarized light after rotation reaches the reflector 12 and is reflected, and the reflected linearly polarized light rotates after passing through the magneto-optical medium film 14 located in the magnetic field again, and the rotation angle is θ2. Optionally, the reflector 12 can be a specular reflector or a diffuse reflector.

[0023] Since the Faraday rotation magneto-optical effect is related only to the direction of the magnetic flux density, and has nothing to do with the forward or reverse magnetic flux density of the polarized light, according to the principle of reflection and co-rotation of the Faraday rotation magneto-optical effect, the rotation angles θ2 and θ1 of the polarization direction of the linearly polarized light are equal and the direction is continuous after the linearly polarized light passes twice through the magneto-optical medium film 14 located in the magnetic field. Thus, when the linearly polarized light reaches the brightness enhancement film 13 after rotating twice in the magnetic field, the polarization direction of the linearly polarized light has rotated twice as much as θ1 or twice as much as θ2.

[0024] At this time, the linearly polarized light energy is again divided into two parts, and the light energy in the same direction as the transmission axis of the lower polarizer 21 (i.e., the first direction X) is transmitted through the brightness enhancement film 13 and used for display on the LCD panel 2, while the light energy perpendicular to the transmission axis of the lower polarizer 21 (i.e., the second direction Y) is reflected again by the brightness enhancement film 13. After being reflected multiple times, most of the linearly polarized light in the second direction Y reflected back by the brightness enhancement film 13 can be converted into linearly polarized light in the first direction X that can transmit through the brightness enhancement film 13, reducing the waste of light caused by absorption by each film layer and improving the utilization rate of the backlight.

[0025] According to the backlight module 1 and the display device of the embodiment of the present application, the backlight module 1 includes a magnetic member 15 disposed between the rear plate 11 and the reflector 12, and a magneto-optical medium film 14 disposed between the magnetic member 15 and the brightness enhancement film 13, so that the brightness enhancement film 13 can transmit linearly polarized light in a first direction X and reflect linearly polarized light in a second direction Y. The magnetic member 15 generates a magnetic field parallel to the first direction X, so that the linearly polarized light in the second direction Y can be rotated after passing through the magneto-optical medium film 14 located in the magnetic field. The reflector 12 is used to reflect the rotated linearly polarized light, so that most of the linearly polarized light in the second direction Y reflected and returned by the brightness enhancement film 13 can be converted into linearly polarized light in the first direction X that can be transmitted through the brightness enhancement film 13. This greatly improves the polarization efficiency of the brightness enhancement film 13, reduces the waste of light absorbed by each film layer, and improves the utilization rate of the backlight.

[0026] In some embodiments, the linearly polarized light in the second direction Y is converted to linearly polarized light in the first direction X by being reflected N times between the brightness enhancement film 13 and the reflector 12, where N=π / (4×B×V×L), where L is the thickness of the magneto-optical media film 14, V is the Verdet constant of the magneto-optical media film 14, and B is the magnetic flux density of the magnetic field generated by the magnetic member 15 parallel to the first direction X.

[0027] Specifically, according to the operating principle of the Faraday rotation magneto-optical effect, the rotation angle of one rotation of linearly polarized light after it passes through the magneto-optical medium film 14 is θ=V×B×L. In this case, the rotation angle of the light beam reflected N times by the reflector 12 when it reaches the bottom surface of the brightness enhancement film 13 is 2×N×θ=2×N×V×B×L.

[0028] When 2×N×V×B×L≈π / 2, the linearly polarized light in the second direction Y reflected back by the brightness enhancement film 13 is completely converted into linearly polarized light in the first direction X and passes through the brightness enhancement film 13, at which time N=π / (4×V×B×L). By properly setting the value of B and properly selecting the magneto-optical medium film 14, the order of N can be effectively reduced, thereby minimizing the number of reflections, further reducing the light wasted by the absorption of each film layer, and improving the utilization rate of the backlight.

[0029] Ideally, when N=1, the linearly polarized light in the second direction Y reflected by the brightness enhancement film 13 can be converted into linearly polarized light in the first direction X by rotating its polarization direction by π / 2 after only one reflection by the reflector 12, and can also be reused by transmitting through the brightness enhancement film 13, thereby maximizing the utilization rate of the backlight.

[0030] In some embodiments, the magnetic member 15 is a planar magnet, and the material of the magnetic member 15 may include Neodymium Iron Boron magnet (NdFeB) to obtain high magnetic flux density.

[0031] Optionally, at least a part of the back panel 11 is a magnetic shielding material, which may include, for example, iron-aluminum alloy, and is manufactured by a process such as punching, to prevent external metal impurities from interfering with the magnetic field generated by the magnetic member 15, affecting the conversion efficiency of linearly polarized light, and further reducing the utilization rate of the backlight. The magnetic shielding material can also protect the backlight module 1 from being easily broken by the impact of external force. The part of the back panel 11 that does not use the magnetic shielding material is made of a plastic material, for example, polyimide, polycarbonate, polyethersulfone, polyethylene terephthalate, polyethylene, etc., and this part is used for bonding and mounting the magnetic member to other members such as magnets, etc.

[0032] In addition, the shape of the back panel 11 may be the same as the shape of the liquid crystal display panel 2 using the backlight module 1. For example, if the liquid crystal display panel 2 has a circular shape, the shape of the back panel 11 of the backlight module 1 used therewith is also circular. The shape of the back panel 11 can vary according to different embodiments.

[0033] In some embodiments, the magneto-optical medium film 14 includes a transparent substrate and a magneto-optical material disposed on a surface of the transparent substrate. The transparent substrate may be made of any one of polymethylmethacrylate (PMMA), polyethyleneterephthalate (PET), polycarbonate (PC), and glass. The magneto-optical material may be any one of yttrium iron garnet ferrite (YIG), yttrium iron garnet ferrite (YIG) doped with graphene aerogel (GA), and CdMgTe crystal.

[0034] In some embodiments, the magneto-optical medium film 14 comprises a transparent substrate and multiple layers of magneto-optical material disposed within the transparent substrate. The transparent substrate may be made of any one of polymethylmethacrylate (PMMA), polyethyleneterephthalate (PET), polycarbonate (PC), and glass. The magneto-optical material may be any one of yttrium iron garnet ferrite (YIG), yttrium iron garnet ferrite (YIG) doped with graphene aerogel (GA), and CdMgTe crystals. The multiple layers of magneto-optical material are layered within the transparent substrate.

[0035] In some embodiments, the brightness enhancement film 13 comprises a core layer and a coating layer, and the coating layer can be obtained by mixing diffusing particles and an adhesive, and the brightness enhancement film 13 can be obtained by simply uniformly applying the coating layer to the core layer and then baking it.

[0036] In some embodiments, the light source 16 is located on the side of the magnetic member 15 away from the back plate 11, the light source 16 is a light board, the light board includes a circuit board and a plurality of light emitting elements arranged in an array on the circuit board, the reflector 12 has grooves corresponding to the light emitting elements, the magneto-optical medium film 14 is located on the side of the reflector 12 away from the magnetic member 15, and a support post 17 is provided between the reflector 12 and the magneto-optical medium film 14.

[0037] In some embodiments, the light emitting element may be either a micro light emitting diode (Micro-LED) or a submillimeter light emitting diode (Mini-LED). A Micro-LED is an LED chip with a particle size of 100 microns or less, and a Mini-LED is an LED chip with a particle size of about 100 to 300 microns. In other embodiments, the light emitting element may be a light emitting diode (LED) of a general size, and an LED, Mini-LED, or Micro-LED can be a self-emitting light emitting element for display, and has advantages such as low power consumption, high brightness, high resolution, high color saturation, fast response, long life, and high efficiency.

[0038] As shown in FIG. 1, the backlight module 1 is a direct-type backlight module, and the backlight module 1 further includes an optical control assembly 10, which is located on the side away from the back plate 11 of the light-emitting elements, and the orthogonal projection of the optical control assembly 10 on the back plate 11 covers the orthogonal projection of the multiple light-emitting elements on the back plate 11.

[0039] The magnetic optical medium film 14 is used to support the brightness enhancement film 13 and other optical control assembly 10. The optical control assembly 10 is an entire optical film layer processed based on the brightness enhancement film 13, integrating optical processing functions such as reflection, refraction, scattering, and focusing, and may also include a diffusion plate and an optical film located on the side of the diffusion plate away from the back plate 11. The diffusion plate and the optical film are fixedly connected by a transparent optical adhesive to prevent relative displacement between the diffusion plate and the optical film from impairing the light output effect of the backlight module 1.

[0040] The diffusion plate is used to diffuse the light emitted by the light emitting elements to uniform the brightness of the entire backlight module 1. The optical film may include, for example, a prism film and a protective film, and the prism film is used to control the propagation direction of the light diffused by the diffusion plate so that it is perpendicular to the liquid crystal display panel 2. The protective film is used to protect the prisms of the prism film from scratches, etc. The protective film can also be used to expand the viewing angle that is narrowed by the prism film.

[0041] The reflector 12 has grooves corresponding to the light emitting elements, and the grooves can prevent the reflector 12 from blocking the light emitted from the light emitting elements. Optionally, the reflector 12 can be made of a ductile material, such as polyethylene terephthalate (PET), polycarbonate (PC), and polystyrene (PS). The reflector 12 can further include a high reflection coating, such as titanium dioxide TiO2, applied on the ductile material, thereby increasing the light reflection coefficient. The reflector 12 can reflect the light reflected from the optical control assembly 10 between the back plate 11 back to the optical control assembly 10, improving the light output efficiency of the backlight module 1, and finally enhancing the backlight brightness of the backlight module 1.

[0042] Furthermore, the support column 17 is an elastic column that can expand and contract in its axial direction, and one axial end of the support column 17 is connected to the reflector plate 12 and the other end abuts against the magneto-optical medium film 14.

[0043] Optionally, the support pillar 17 is an elastic ejector pin with a spring inside, which can expand and contract according to the change of the optical distance. There are a plurality of support pillars 17, and the ends of the plurality of support pillars 17 far from the reflector 12 abut against the magneto-optical medium film 14, respectively, to prevent the central position of the optical control assembly 10 from being depressed inward due to its own gravity, which would impair the light output effect. This backlight module 1 having a plurality of support pillars 17 is particularly applicable to a large display device, for example, 67 inches or more.

[0044] Since the support column 17 is installed in the optical cavity of the backlight module 1, it will absorb the light emitted by the light emitting element and impair the optical quality. Since the support column 17 is installed between the reflector 12 and the magneto-optical medium film 14, it may press and damage the reflector 12. Furthermore, if the support column 17 falls off during use, it will remain in the optical cavity, generating abnormal noise and impairing the optical display effect. Therefore, in small display devices of 32 inches or less, the support column 17 can generally be omitted.

[0045] Second Example FIG. 3 is a structural schematic diagram of a backlight module according to a second embodiment of the present invention and a display device including the backlight module.

[0046] As shown in FIG. 3, the second embodiment of the present application further provides a backlight module 1 and a display device equipped with the backlight module 1, which has the same structure as the first embodiment and the backlight module 1 shown in FIG. 1, except that the distance between the magneto-optical medium film 14 and the magnetic member 15 of the direct-type backlight module 1 is closer, the magnetic flux density is larger, and the magnetic field uniformity is relatively higher.

[0047] According to the rotation angle θ=V×B×L of the Faraday magneto-optical rotation effect, as the magnetic flux density increases, the rotation angle of the linearly polarized light after passing through the magneto-optical medium film 14 can be increased, thereby reducing the number of times the linearly polarized light is reflected by the brightness enhancement film 13 and the reflector 12, and further reducing the loss of light caused by the absorption of each film layer, thereby improving the utilization rate of the backlight.

[0048] Specifically, the backlight module 1 further includes a light source 16 and a support plate 19, the light source 16 being provided on the side of the magnetic member 15 away from the back plate 11, the light source 16 being a light board, the light board including a circuit board and a plurality of light-emitting elements arranged in an array on the circuit board, the magneto-optical medium film 14 being located on the side of the reflector 12 away from the magnetic member 15, the magneto-optical medium film 14 and the reflector 12 being in close contact with each other, the support plate 19 being provided between the magneto-optical medium film 14 and the brightness enhancement film 13, the magneto-optical medium film 14 being flush with the top surface of the light-emitting element, grooves being provided corresponding to the light-emitting elements, and support pillars 17 being provided between the reflector 12 and the support plate 19.

[0049] In some embodiments, the light emitting element may be either a micro light emitting diode (Micro-LED) or a submillimeter light emitting diode (Mini-LED). A Micro-LED is an LED chip with a particle size of 100 microns or less, and a Mini-LED is an LED chip with a particle size of about 100 to 300 microns. In other embodiments, the light emitting element may be a light emitting diode (LED) of a general size, and an LED, Mini-LED, or Micro-LED can be a self-emitting light emitting element for display, and has advantages such as low power consumption, high brightness, high resolution, high color saturation, fast response, long life, and high efficiency.

[0050] In one example, the light-emitting element is a Mini-LED or Micro-LED, the magneto-optical medium film 14 is flush with the top surface of the Mini-LED, and a groove is provided corresponding to the light-emitting element, so that the entire surface of the magneto-optical medium film 14 can cover the Mini-LED, thereby reducing the thickness size of the backlight module 1.

[0051] In another example, the light-emitting element is a Mini-LED or Micro-LED, the light board further includes a transparent encapsulating layer covering the multiple light-emitting elements, and the magneto-optical medium film 14 further includes a magneto-optical material doped in the transparent encapsulating layer, thereby eliminating the need for a transparent substrate of the separate magneto-optical medium film 14, further reducing the size of the backlight module 1 in the thickness direction, and achieving a more compact arrangement effect.

[0052] The support plate 19 may be an optical diffusion sheet, which is used to diffuse the light emitted by the light-emitting elements to uniform the brightness of the entire backlight module 1, and can also be used to support the brightness enhancement film 13 and the optical control assembly 10.

[0053] The reflector 12 and the magneto-optical medium film 14 are in close contact with each other and are close to the magnetic member 15. The reflector 12 and the magneto-optical medium film 14 are provided with grooves corresponding to the light emitting elements, respectively, and the grooves can prevent the reflector 12 and the magneto-optical medium film 14 from blocking the light emitted from the light emitting elements.

[0054] Furthermore, the support column 17 is an elastic column that is expandable and contractible in its axial direction, and one axial end of the support column 17 is connected to the reflector plate 12 and the other end abuts against the support plate 19.

[0055] Optionally, the support pillar 17 is an elastic ejector pin with a spring inside, which can expand and contract according to the change in the optical distance. There are a plurality of support pillars 17, and the ends of the plurality of support pillars 17 far from the reflector 12 abut against the support plate 19, respectively, to prevent the central positions of the support plate 19 and the optical control assembly 10 from being depressed inward due to their own gravity, which would impair the light output effect. This backlight module 1 having a plurality of support pillars 17 is particularly applicable to a large display device, for example, 67 inches or more.

[0056] Since the support column 17 is installed in the optical cavity of the backlight module 1, it will absorb the light emitted by the light emitting element and impair the optical quality. Since the support column 17 is installed between the reflector 12 and the support plate 19, it may press and damage the reflector 12. Furthermore, if the support column 17 falls off during use, it will remain in the optical cavity, generating abnormal noise and impairing the optical display effect. Therefore, in small display devices of 32 inches or less, the support column 17 can generally be omitted.

[0057] In the direct-type backlight module of this embodiment, the distance between the magneto-optical medium film 14 and the magnetic member 15 is short, so that the magnetic flux density of the magnetic field parallel to the first direction X generated by the magnetic member 15 is larger and the magnetic field uniformity is relatively high, which can increase the rotation angle of the linearly polarized light in the magnetic field and reduce the number of times the linearly polarized light is reflected by the brightness enhancement film 13 and the reflector 12, thereby reducing the waste of light caused by the absorption of each film layer, further improving the polarization efficiency of the brightness enhancement film 13, reducing the waste of light caused by the absorption of each film layer, and improving the utilization rate of the backlight.

[0058] Third Example FIG. 4 is a structural schematic diagram of a backlight module according to a third embodiment of the present invention and a display device including the backlight module.

[0059] As shown in Fig. 4, the third embodiment of the present application further provides a backlight module 1 and a display device including the backlight module 1, which has the same structure as the backlight module 1 in the first embodiment and shown in Fig. 1, except that the backlight module 1 is an edge-type backlight module, that is, the light source 16 is provided on the light-incoming side of the light guide plate 18. In this case, the thickness of the magneto-optical medium film 14 can be reduced, and the distance to the magnetic member 15 is closer, so that the magnetic flux density is larger and the magnetic field uniformity is relatively higher.

[0060] According to the rotation angle θ=V×B×L of the Faraday magneto-optical rotation effect, the larger the magnetic flux density, the more the rotation angle of the linearly polarized light after passing through the magneto-optical medium film 14 can be increased, thereby reducing the number of times the linearly polarized light is reflected by the brightness enhancement film 13 and the reflector 12, and further reducing the light wasted by the absorption of each film layer, improving the utilization rate of the backlight. In addition, compared with the direct type backlight module, the edge type backlight module is thinner.

[0061] Specifically, the backlight module 1 includes a light source 16 and a light guide plate 18, the light source 16 being a light strip, the light guide plate 18 being disposed between the reflector 12 and the magneto-optical medium film 14, and the light strip being disposed on one side of the light guide plate 18. The light strip generally includes a number of light-emitting elements arranged in a row, and the light-emitting elements may be light-emitting diodes (LEDs) of a general size.

[0062] Optionally, the material of the light guide plate 18 may be a polymethyl methacrylate (PMMA) material with high light transmittance, a polymethacrylstyrene (MS) material with excellent heat resistance and moisture resistance, a light guide synthetic resin, etc. The light emitted from the light source 16 enters the main body from the light input side of the light guide plate 18, and then exits from the light output side of the main body to enter the liquid crystal display panel 2, thereby converting the point light source or line light source generated by the light source 16 into a surface light source, and illuminating the entire area of ​​the liquid crystal display panel 2 with approximately the same brightness.

[0063] In addition, the backlight module 1 further comprises a magneto-optical medium film 14 disposed on the light guide plate 18 , a brightness enhancement film 13 and an optical control assembly 10 .

[0064] In some embodiments, the magneto-optical medium film 14 includes a transparent substrate and a magneto-optical material disposed on a surface of the transparent substrate. The transparent substrate may be made of any one of polymethylmethacrylate (PMMA), polyethyleneterephthalate (PET), polycarbonate (PC), and glass. The magneto-optical material may be any one of yttrium iron garnet ferrite (YIG), yttrium iron garnet ferrite (YIG) doped with graphene aerogel (GA), and CdMgTe crystal.

[0065] In some embodiments, the magneto-optical medium film 14 comprises a transparent substrate and multiple layers of magneto-optical material disposed within the transparent substrate. The transparent substrate may be made of any one of polymethylmethacrylate (PMMA), polyethyleneterephthalate (PET), polycarbonate (PC), and glass. The magneto-optical material may be any one of yttrium iron garnet ferrite (YIG), yttrium iron garnet ferrite (YIG) doped with graphene aerogel (GA), and CdMgTe crystals. The multiple layers of magneto-optical material are layered within the transparent substrate.

[0066] In some embodiments, the brightness enhancement film 13 comprises a core layer and a coating layer, and the coating layer can be obtained by mixing diffusing particles and an adhesive, and the brightness enhancement film 13 can be obtained by simply uniformly applying the coating layer to the core layer and then baking it.

[0067] In some embodiments, the back panel 11 comprises a bottom panel and a curved portion, between which a U-shaped receiving cavity is formed, and the light strip and a portion of the light guide panel 18 are located within the U-shaped receiving cavity. The curved portion comprises a first support surface and a second support surface arranged crosswise, the light strip is located on the first support surface, and the second support surface is parallel to the bottom panel.

[0068] Furthermore, a light-shielding portion 101 is provided between the second supporting surface of the rear panel 11 and the array substrate 22 of the LCD panel 2, the light-shielding portion 101 is generally black and can be formed by adding a black masterbatch to plastic, or the light-shielding portion 101 is a black adhesive layer, etc., thereby preventing the light from the light strip from leaking through the gap between the light guide plate 18 and the rear panel 11 and causing light leakage at the edges.

[0069] The optical control assembly 10 comprises a lower diffusion film, a lower brightness enhancement film, an upper brightness enhancement film and an upper diffusion film, which are stacked from bottom to top, and a prism structure is provided on the light output surface of at least one of the lower brightness enhancement film and the upper brightness enhancement film, which generates a focusing effect of the light emitted from the light guide plate 18, thereby improving the brightness within a certain viewing angle range of the backlight module 1.

[0070] In the edge-type backlight module of this embodiment, the distance between the magneto-optical medium film 14 and the magnetic member 15 is short, so that the magnetic flux density of the magnetic field parallel to the light output direction generated by the magnetic member 15 is larger and the magnetic field uniformity is relatively high, which can increase the rotation angle of the linearly polarized light in the magnetic field and reduce the number of times the linearly polarized light is reflected by the brightness enhancement film 13 and the reflector 12, thereby reducing the loss of light absorbed by each film layer, further improving the polarization efficiency of the brightness enhancement film 13, reducing the loss of light absorbed by each film layer, and improving the utilization rate of the backlight. In addition, the thickness of the magneto-optical medium film 14 can be reduced, and the edge-type backlight module is thinner than the direct-type backlight module.

[0071] Fourth Example FIG. 5 is a structural schematic diagram of a backlight module and a display device according to a fourth embodiment of the present invention.

[0072] As shown in Fig. 5, the fourth embodiment of the present application further provides a backlight module 1 and a display device including the backlight module 1, which has the same structure as the backlight module 1 in the third embodiment and shown in Fig. 3, except that the position of the magneto-optical medium film 14 in the edge-type backlight module is different. Compared with the backlight module 1 in the third embodiment and shown in Fig. 3, the distance between the magneto-optical medium film 14 and the magnetic member 15 is closer, so that the magnetic flux density is larger and the uniformity of the magnetic field is relatively higher.

[0073] According to the rotation angle θ=V×B×L of the Faraday magneto-optical rotation effect, as the magnetic flux density increases, the rotation angle of the linearly polarized light after passing through the magneto-optical medium film 14 can be increased, thereby reducing the number of times the linearly polarized light is reflected by the brightness enhancement film 13 and the reflector 12, and further reducing the loss of light caused by the absorption of each film layer, thereby improving the utilization rate of the backlight.

[0074] Specifically, the light source 16 is a light strip, the light guide plate 18 is disposed between the reflector plate 12 and the brightness enhancement film 13, the light strip is disposed on the light-incoming side of the light guide plate 18, and the magneto-optical medium film 14 is disposed between the magnetic member 15 and the reflector plate 12. The light strip generally comprises a number of light-emitting elements arranged in a row, and the light-emitting elements may be light-emitting diodes (LEDs) of a common size.

[0075] Optionally, the material of the light guide plate 18 may be a polymethyl methacrylate (PMMA) material with high light transmittance, a polymethacrylic styrene material with excellent heat resistance and moisture resistance, a light guide synthetic resin, etc. The light emitted from the light source 16 enters the main body from the light input side of the light guide plate 18, and then exits from the light output side of the main body to enter the liquid crystal display panel 2, thereby converting the point light source or line light source generated by the light source 16 into a surface light source, and illuminating the entire area of ​​the liquid crystal display panel 2 with approximately the same brightness.

[0076] In some embodiments, the back panel 11 comprises a bottom panel and a curved portion, between which a U-shaped receiving cavity is formed, and the light strip and a portion of the light guide panel 18 are located within the U-shaped receiving cavity. The curved portion comprises a first support surface and a second support surface arranged crosswise, the light strip is located on the first support surface, and the second support surface is parallel to the bottom panel.

[0077] Furthermore, a light-shielding portion 101 is provided between the second supporting surface of the rear panel 11 and the array substrate 22 of the LCD panel 2, the light-shielding portion 101 is generally black and can be formed by adding a black masterbatch to plastic, or the light-shielding portion 101 is a black adhesive layer, etc., thereby preventing the light from the light strip from leaking through the gap between the light guide plate 18 and the rear panel 11 and causing light leakage at the edges.

[0078] In the edge-type backlight module of this embodiment, the distance between the magneto-optical medium film 14 and the magnetic member 15 is short, so that the magnetic flux density of the magnetic field parallel to the light output direction generated by the magnetic member 15 is larger and the magnetic field uniformity is relatively high, thereby increasing the rotation angle of the linearly polarized light in the magnetic field, reducing the number of times the linearly polarized light is reflected by the brightness enhancement film 13 and the reflector 12, further reducing the loss of light absorbed by each film layer, further improving the polarization efficiency of the brightness enhancement film 13, reducing the loss of light absorbed by each film layer, and improving the utilization rate of the backlight. In addition, the thickness of the magneto-optical medium film 14 can be reduced, and compared with the direct type backlight module, the edge-type backlight module is thinner.

[0079] As can be understood, the technical solutions of the backlight module 1 according to the embodiments of the present application can be widely used in providing light sources to various liquid crystal display panels, such as TN (Twisted Nematic) display panels, IPS (In-Plane Switching) display panels, VA (Vertical Alignment) display panels, MVA (Multi-Domain Vertical Alignment) display panels, etc.

[0080] As can be easily understood, the terms "on," "above," and "on" in this application should be interpreted in the broadest possible way, whereby "on" not only means "directly on an object," but also includes the meaning of "on an object" and there being an intermediate feature or layer therebetween, and "on" or "on" not only means "above an object" or "on" but also includes the meaning of "above an object" or "on" and there being no intermediate feature or layer therebetween (i.e., directly on an object).

[0081] The term "layer" as used herein may be a portion of material that includes a region having a thickness. A layer may extend across an underlying or superstructure or may have an extent that is less than the extent of the underlying or superstructure. A layer may also be a region of a homogeneous or non-homogeneous continuous structure, with a thickness that is less than the thickness of the continuous structure. For example, a layer may be located between a top surface and a bottom surface of the continuous structure, or between any pair of lateral planes of the top and bottom surfaces. A layer may extend laterally, vertically, and / or along a conical surface. A base substrate may be a layer and may include one or more layers therein and / or have one or more layers located on, above, and / or below it. A layer may include multiple layers. For example, an interconnect layer may include one or more conductor and contact layers (in which contacts, interconnect lines, and / or vias are formed) and one or more dielectric layers.

[0082] It should be noted that the above embodiments are presented for the purpose of illustration, rather than for the purpose of limiting the technical solutions of the present application, and the present application has been described in detail with reference to the above embodiments. However, it should be understood that a person skilled in the art may modify the technical solutions described in the above embodiments, or make equivalent substitutions to some or all of the technical features thereof, and such modifications or substitutions will not cause the essence of the corresponding technical solutions to depart from the scope of the technical solutions of the embodiments of the present application. [Explanation of symbols]

[0083] 1 Backlight module 10 Optical Control Assembly 101 Light shielding part X 1st direction Y Second direction 11 Back plate 12 Reflector 13 Brightness enhancement film 14 Magneto-optical media film 15 Magnetic components 16 light source 17 Support pillar 18 Light guide plate 19 Support plate 2 LCD panel 21 Lower polarizing plate 22 Array Board 23 Color filter substrate 24 Upper polarizing plate

Claims

1. A backlight module comprising a rear panel and a reflector disposed on the rear panel, further comprising a brightness enhancement film, a magneto-optical medium film and a magnetic member, the magnetic member being located between the rear panel and the reflector, the magneto-optical medium film being located between the magnetic member and the brightness enhancement film, the brightness enhancement film being used to transmit linearly polarized light in a first direction and reflect linearly polarized light in a second direction, the magnetic member being used to generate a magnetic field parallel to the first direction, thereby rotating the polarization direction of the linearly polarized light in the second direction after it passes through the magneto-optical medium film located in the magnetic field, the reflector being used to reflect the linearly polarized light after rotation, the first direction being the light output direction of the backlight module, and the second direction being perpendicular to the first direction.

2. 2. The backlight module of claim 1, wherein the linearly polarized light in the second direction is reflected N times between the brightness enhancement film and the reflector to be converted into linearly polarized light in the first direction, where N=π / (4×V×B×L), where L is the thickness of the magneto-optical medium film, V is the Verdet constant of the magneto-optical medium film, and B is the magnetic flux density of the magnetic field parallel to the first direction generated by the magnetic member.

3. 2. The backlight module of claim 1, wherein the magneto-optical medium film comprises a magneto-optical material, the magneto-optical material comprising one of YIG, GA-doped YIG, and CdMgTe crystal.

4. 4. The backlight module of claim 3, wherein the magneto-optic medium film further comprises a transparent substrate, and the magneto-optic material is disposed on or layered within the transparent substrate.

5. The backlight module according to claim 4 , wherein the transparent substrate is made of any one of polymethyl methacrylate, polyethylene terephthalate, polycarbonate, and glass.

6. 2. The backlight module according to claim 1, wherein the magnetic member is a planar magnet, and at least a portion of the back plate is made of a magnetic shielding material.

7. 2. The backlight module of claim 1, further comprising a light board, the light board being provided on a side of the magnetic member away from the rear plate, the light board comprising a circuit board and a plurality of light-emitting elements arranged in an array on the circuit board, the reflector being provided with grooves corresponding to the light-emitting elements, the magneto-optical medium film being located on the side of the reflector away from the magnetic member, and a support pillar being provided between the reflector and the magneto-optical medium film.

8. 2. The backlight module of claim 1, further comprising a light board and a support plate, the light board being provided on a side of the magnetic member away from the rear plate, a circuit board and a plurality of light-emitting elements arranged in an array on the circuit board, the support plate being provided between the magneto-optical medium film and the brightness enhancement film, the magneto-optical medium film being provided in close contact with the reflector, the magneto-optical medium film being flush with the upper surface of the light-emitting element, grooves being provided corresponding to the light-emitting element, and support pillars being provided between the reflector and the support plate.

9. 9. The backlight module of claim 8, wherein the light board further comprises a transparent encapsulation layer covering the plurality of light emitting elements, and the magneto-optical medium film comprises a doped magneto-optical material in the transparent encapsulation layer, the magneto-optical material comprising any one of YIG, YIG doped with GA, and CdMgTe crystal.

10. 9. The backlight module according to claim 8, wherein the support plate is an optical diffusion sheet.

11. 9. The backlight module according to claim 7, wherein the support column is an elastic column that is expandable and contractable in its axial direction.

12. 9. The backlight module according to claim 7 or 8, wherein the light emitting element is a micro light emitting diode or a submillimeter light emitting diode, the light board further comprises a transparent encapsulation layer covering the light emitting element, and the magneto-optical medium film comprises a magneto-optical material doped in the transparent encapsulation layer.

13. 9. The backlight module of claim 7 or 8, further comprising an optical control assembly, the optical control assembly being located on a side of the light-emitting element away from the rear plate, and comprising a diffuser plate and an optical film located on a side of the diffuser plate away from the rear plate.

14. 2. The backlight module of claim 1, further comprising: a light strip; and a light guide plate, wherein the magneto-optical medium film is located on the side of the reflector away from the magnetic member, the light guide plate is disposed between the reflector and the magneto-optical medium film, and the light strip is disposed on the light input side of the light guide plate; and further comprising: a circuit board; and a plurality of light-emitting elements arranged in a row on the circuit board.

15. 2. The backlight module of claim 1, further comprising: a light strip; and a light guide plate, the reflector being located on a side of the magneto-optical medium film away from the magnetic member, the light guide plate being disposed between the reflector and the brightness enhancement film, the light strip being disposed on the light input side of the light guide plate, and comprising: a circuit board; and a plurality of light-emitting elements arranged in a row on the circuit board.

16. 16. The backlight module according to claim 14 or 15, further comprising an optical control assembly, the optical control assembly being located on a side of the light-emitting element away from the rear panel, and comprising a lower diffusion film, a lower brightness enhancement film, an upper brightness enhancement film and an upper diffusion film stacked from bottom to top, and a prism structure being provided on the light output surface of at least one of the lower brightness enhancement film and the upper brightness enhancement film.

17. The rear panel includes a bottom plate and a curved portion, and a U-shaped receiving cavity is formed between the bottom plate and the curved portion, and the light strip and a portion of the light guide plate are located within the U-shaped receiving cavity; 16. The backlight module according to claim 14 or 15, wherein the curved portion has a first support surface and a second support surface arranged crosswise, the light strip is located on the first support surface, and the second support surface is parallel to the bottom plate.

18. The backlight module according to claim 17 , further comprising a light-shielding portion provided between the second supporting surface of the rear plate and an array substrate of a liquid crystal display panel.

19. A display device, comprising: A liquid crystal display panel; a backlight module provided on a backlight side of the liquid crystal display panel for supplying a light source to the liquid crystal display panel, the backlight module comprising a rear panel and a reflector provided on the rear panel, and further comprising a brightness enhancement film, a magneto-optical medium film, and a magnetic member, the magnetic member being located between the rear panel and the reflector, the magneto-optical medium film being located between the magnetic member and the brightness enhancement film, the brightness enhancement film being used to transmit linearly polarized light in a first direction and reflect linearly polarized light in a second direction, the magnetic member being used to generate a magnetic field parallel to the first direction, thereby rotating the polarization direction of the linearly polarized light in the second direction after it passes through the magneto-optical medium film located in the magnetic field, the reflector being used to reflect the linearly polarized light after rotation, the first direction being the light output direction of the backlight module, and the second direction being perpendicular to the first direction.

20. 20. The display device of claim 19, further comprising: an upper polarizing plate positioned on the light output side of the liquid crystal display panel; a lower polarizing plate positioned on the backlight side of the liquid crystal display panel; and a cover plate positioned on the side of the upper polarizing plate away from the liquid crystal display panel.

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