Backlight module, manufacturing method thereof and display device

Abstract

The invention discloses a backlight module, a manufacturing method thereof and a display device. The backlight module comprises: a first substrate (11); a light emitting diode (LED) chip (12) mounted on the first substrate (11), the LED chip (12) comprising a substrate (121) and a light emitting layer (122) located on one side of the substrate (121) and configured to emit white light; the polarization structure (13) is located on the light emitting side of the LED chip (12) and is configured to transmit first polarized light of the white light and reflect second polarized light of the white light, the polarization directions of the first polarized light and the second polarized light are different, and the backlight module is configured to emit the first polarized light.

Description

Backlight module, manufacturing method thereof and display device TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of display, and in particular, to a backlight module, a manufacturing method thereof and a display device. BACKGROUND

[0002] In a liquid crystal display (LCD), in order to realize dynamic light adjustment in a region, a direct type light emitting diode (LED) backlight source can be used to improve dynamic local light adjustment and contrast.

[0003] SUMMARY

[0004] According to an aspect of an embodiment of the present disclosure, a backlight module is provided, comprising: a first substrate; a light emitting diode (LED) chip mounted on the first substrate, the LED chip comprising a substrate and a light emitting layer configured to emit white light on one side of the substrate; and a polarization structure on an out-lighting side of the LED chip, configured to transmit first polarized light of the white light and reflect second polarized light of the white light, the polarization directions of the first polarized light and the second polarized light being different, wherein the backlight module is configured to emit the first polarized light.

[0005] In some embodiments, the backlight module further comprises a first reflective layer, wherein the LED chip is located between the first substrate and the first reflective layer.

[0006] In some embodiments, the polarization structure is located between the LED chip and the first substrate.

[0007] In some embodiments, the LED chip further comprises: a first semiconductor layer located on a side of the light emitting layer close to the substrate; a second semiconductor layer located on a side of the light emitting layer away from the substrate, wherein the conductivity type of the second semiconductor layer is different from that of the first semiconductor layer; a conductive layer located on a side of the second semiconductor layer away from the substrate; a first pad located on a side of the conductive layer away from the substrate and connected with the conductive layer; and a second pad located on a side of the first semiconductor layer away from the substrate and connected with the first semiconductor layer, wherein the polarization structure is located between the conductive layer and the first substrate.

[0008] In some embodiments, the LED chip further comprises: a second reflective layer located on a side of the substrate away from the light emitting layer, configured to reflect the white light from the light emitting layer and the second polarized light reflected by the polarization structure.

[0009] In some embodiments, the LED chip further comprises: a polarization conversion structure located on a side of the substrate distal to the light emitting layer, configured to convert the second polarized light reflected by the polarization structure into the first polarized light.

[0010] In some embodiments, the polarization conversion structure comprises a metasurface structure, a refractive index of the metasurface structure is greater than 1.8, and an aspect ratio of the metasurface structure is greater than 5.

[0011] In some embodiments, a thickness of the metasurface structure is greater than 500 nanometers, and a period of the metasurface structure is greater than 200 nanometers.

[0012] In some embodiments, the LED chip further comprises: a depolarization structure located on a side of the substrate distal to the light emitting layer, configured to change the second polarized light into non-polarized light.

[0013] In some embodiments, the LED chip further comprises: a second reflective layer located on a side of the substrate distal to the light emitting layer, configured to reflect the white light from the light emitting layer and the second polarized light reflected by the polarization structure; and the depolarization structure comprises: a random structure located on a side of the second reflective layer proximal to the substrate, and a filler material layer covering the random structure and located between the second reflective layer and the substrate.

[0014] In some embodiments, the depolarization structure comprises: a random structure located on a side of the substrate distal to the light emitting layer, the random structure being integrally arranged with the substrate; and a filler material layer covering the random structure.

[0015] In some embodiments, the depolarization structure comprises: a particle-doped adhesion layer located on a side of the substrate distal to the light emitting layer, wherein the particles comprise at least one of scattering particles and reflective particles.

[0016] In some embodiments, the backlight module further comprises: an encapsulation layer covering the LED chip; and a first reflective layer covering a surface of the encapsulation layer distal to the substrate, configured to reflect the white light from the LED chip to a light emitting side of the LED chip.

[0017] In some embodiments, the polarization structure comprises a metal wire grid, a period of the metal wire grid is 20 nanometers to 260 nanometers, a height of the metal wire grid is greater than 40 nanometers, and a duty cycle of the metal wire grid is 0.1 to 0.9.

[0018] According to another aspect of the embodiments of the present disclosure, a display device is provided, comprising: a display panel; and the backlight module according to any one of the above embodiments. The backlight module further comprises: a lens array disposed on a side of the first substrate away from the LED chip and configured to make the first polarized light emitted by the backlight module incident on an opening region of the display panel; and a planarization layer covering surfaces of the lenses in the lens array.

[0019] In some embodiments, the lens array is a microlens array, and an absolute value of a difference between a refractive index of the first substrate and a refractive index of the lens array is less than or equal to 0.15.

[0020] In some embodiments, the lens array is a microlens array, and a difference between a refractive index of the planarization layer and a refractive index of the one of the lens array closer to the first substrate is greater than 0.

[0021] In some embodiments, the difference is greater than or equal to 0.1.

[0022] In some embodiments, the lens array is a microlens array, an aperture of the lens in the lens array is less than 100 microns, and a sagittal height of the lens is less than 100 microns.

[0023] In some embodiments, at least one of the aperture and the sagittal height of the lens is less than 75 microns.

[0024] In some embodiments, the lens array is a microlens array, and the lens in the lens array is convex to the first substrate.

[0025] In some embodiments, the display panel comprises an array substrate and a color film substrate, and one of the array substrate and the color film substrate closer to the backlight module comprises a second substrate and a light shielding layer on a side of the second substrate away from the backlight module, the light shielding layer defining the opening region. The display device satisfies: n1 / T1+n2 / T2=1 / f, and f=R / 2(n4-n3); wherein n1 is a refractive index of the first substrate, T1 is a thickness of the first substrate, n2 is a refractive index of the second substrate, T2 is a thickness of the second substrate, f is a focal length of the lens in the lens array, R is an aperture of the lens, n4 is a refractive index of the one of the planarization layer and the lens array closer to the first substrate, and n3 is a refractive index of the other of the planarization layer and the lens array.

[0026] According to yet another aspect of the embodiments of the present disclosure, a manufacturing method of a backlight module is provided, including: providing an LED chip, the LED chip including a substrate and a light-emitting layer on one side of the substrate configured to emit white light; forming a polarization structure on a light-emitting side of the LED chip, the polarization structure configured to transmit first polarized light of the white light and reflect second polarized light of the white light, the polarization directions of the first polarized light and the second polarized light being different; and mounting the LED chip on a first substrate, wherein the backlight module is configured to emit the first polarized light.

[0027] In some embodiments, the polarization structure is located between the LED chip and the first substrate; the providing the LED chip includes: providing the substrate; depositing a second reflective layer on one side of the substrate; and after depositing the second reflective layer, forming the light-emitting layer on a side of the substrate away from the second reflective layer, wherein the second reflective layer is configured to reflect the white light from the light-emitting layer and reflect the second polarized light reflected by the polarization structure. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0029] The present disclosure can be more clearly understood with reference to the following detailed description when considered in conjunction with the following drawings, in which:

[0030] FIG. 1 is a schematic diagram illustrating a backlight module according to some embodiments of the present disclosure.

[0031] FIG. 2A is a schematic diagram illustrating a positional relationship between an LED chip and a polarization structure according to some implementations of the present disclosure.

[0032] FIG. 2B is a schematic diagram illustrating a positional relationship between an LED chip and a polarization structure according to some other implementations of the present disclosure.

[0033] FIG. 2C is a schematic diagram illustrating a polarization degree in a case where a material of a metal wire grid is different.

[0034] FIG. 2D is a schematic diagram illustrating a transmittance of first polarized light in a case where a material of a metal wire grid is different.

[0035] FIG. 3A is a schematic diagram illustrating an LED chip according to some embodiments.

[0036] FIG. 3B is a schematic diagram illustrating a metasurface structure according to some implementations.

[0037] FIG. 4A is a schematic diagram illustrating an LED chip according to some other embodiments.

[0038] FIGS. 4B-4D are schematic diagrams illustrating a decentering structure according to different implementations.

[0039] FIG. 5 is a schematic diagram illustrating a backlight module according to some embodiments of the present disclosure.

[0040] FIGS. 6A and 6B are schematic diagrams illustrating a display device according to some embodiments of the present disclosure.

[0041] FIGS. 6C and 6D are schematic diagrams illustrating a display device according to some other embodiments of the present disclosure.

[0042] FIGS. 7A and 7B are schematic diagrams of light intensity after light rays pass through a normal micro-lens array and an inverted micro-lens array, respectively.

[0043] FIGS. 8A and 8B are schematic diagrams of light intensity distribution and luminance distribution, respectively, of a backlight module with a micro-lens array.

[0044] FIG. 9 is a schematic diagram illustrating an arrangement of LED chips according to some embodiments of the present disclosure.

[0045] FIGS. 10A and 10B are schematic diagrams illustrating light rays emitted by LED chips passing through a micro-lens array and then being incident on an opening region according to different embodiments of the present disclosure.

[0046] FIGS. 11A and 11B are schematic diagrams illustrating a display device according to yet some other embodiments of the present disclosure.

[0047] FIGS. 12A and 12B are schematic diagrams illustrating a display device according to still some other embodiments of the present disclosure.

[0048] FIG. 13 is a flowchart illustrating a method of manufacturing a backlight module according to some embodiments of the present disclosure.

[0049] FIG. 14 is a schematic diagram illustrating forming a micro-lens array according to some embodiments of the present disclosure.

[0050] It should be understood that the same or like reference numbers represent the same or like elements. DETAILED DESCRIPTION

[0051] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative in nature and is in no way intended to limit the disclosure, its application or uses. The disclosure can be implemented in numerous different forms, as will be apparent to one of ordinary skill in the art. The embodiments provided are in the nature of a best efforts formulation, and are provided for purposes of illustration and by way of example only. The relative arrangements of components and steps, the components of materials, numerical expressions, and numerical values set forth in these embodiments are to be interpreted as merely exemplary, and not as a limitation of the disclosure unless otherwise specifically stated.

[0052] The terms "first", "second", and similar terms in the present disclosure do not denote any order, quantity, or importance, but are used to distinguish different parts. The terms "comprise", "include" or "contain" and similar terms mean that the elements before the term encompass the elements listed after the term, and do not exclude the possibility of also encompassing other elements. "Up", "down", and the like are only used to indicate relative positional relationships, and when the absolute position of the described object changes, the relative positional relationship can also change accordingly.

[0053] In the present disclosure, when it is described that a specific component is located between a first component and a second component, there can be an intervening component between the specific component and the first component or the second component, or there can be no intervening component. When it is described that a specific component is connected to other components, the specific component can be directly connected to the other components without an intervening component, or can not be directly connected to the other components with an intervening component.

[0054] All the terms used in the present disclosure (including technical terms or scientific terms) have the same meaning as understood by those of ordinary skill in the art to which the present disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted to have meanings consistent with their meanings in the context of the relevant art, and should not be interpreted in an idealized or excessively formalized sense, unless specifically defined here.

[0055] Techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered part of the specification where appropriate.

[0056] The inventors have noticed that in the related art, the number of film layers in the backlight module and the number of film layers in the display panel are relatively large. For example, the backlight module includes a color conversion film, two diffusion sheets, and two prism sheets, and the two prism sheets are stacked between the two diffusion sheets. For another example, the display panel includes an upper polarizing sheet and a lower polarizing sheet. Due to the large number of film layers, the light transmittance is low, resulting in low light extraction efficiency of the backlight module and low brightness of the display panel.

[0057] In view of this, the embodiments of the present disclosure propose the following technical solutions, which help to improve the light extraction efficiency of the backlight module.

[0058] FIG. 1 is a schematic diagram of a backlight module according to some embodiments of the present disclosure. FIG. 2A is a schematic diagram of the positional relationship between an LED chip and a polarizing structure according to some implementations of the present disclosure. FIG. 2B is a schematic diagram of the positional relationship between an LED chip and a polarizing structure according to other implementations of the present disclosure.

[0059] Next, a backlight module according to some embodiments of the present disclosure is described in conjunction with FIG. 1, FIG. 2A and FIG. 2B.

[0060] As shown in FIG. 1, FIG. 2A and FIG. 2B, the backlight module includes a first substrate 11, an LED chip 12 mounted on the first substrate 11, and a polarization structure 13. It should be understood that the backlight module can include an array of LED chips 12 mounted on the first substrate 11.

[0061] The first substrate 11 is, for example, a printed circuit board (PCB), a polymethyl methacrylate (PMMA) substrate, or a glass substrate. In some embodiments, the higher the transmittance of the first substrate 11, the better, for example, the transmittance of the first substrate 11 to white light is greater than 92%. In some embodiments, the LED chip 12 can be mounted on the surface of the first substrate 11 using a surface mounting process.

[0062] Referring to FIG. 2A, the LED chip 12 includes a substrate 121 and a light-emitting layer 122 configured to emit white light on one side of the substrate 121. It should be understood that the LED chip 12 also includes a first semiconductor layer 123 and a second semiconductor layer 124 on both sides of the light-emitting layer 122, and the first semiconductor layer 123 and the second semiconductor layer 124 are of different conductivity types, that is, one is n-type and the other is p-type. For example, the first semiconductor layer 123 is a p-type semiconductor layer, and the second semiconductor layer 124 is an n-type semiconductor layer. The first semiconductor layer 123 is located on the side of the light-emitting layer 122 close to the substrate 121, and the second semiconductor layer 124 is located on the side of the light-emitting layer 122 away from the substrate 121. As some implementations, the material of at least one of the p-type semiconductor layer 123 and the n-type semiconductor layer 124 can include gallium nitride (GaN).

[0063] In some embodiments, the substrate 121 is a sapphire (Al2O3) substrate. However, the present disclosure is not limited thereto. For example, the substrate 121 can be a semiconductor substrate such as silicon, silicon carbide, etc. In some embodiments, the light-emitting layer 122 is a quantum well layer, for example, a multi-quantum well layer (MQW).

[0064] In some embodiments, referring to FIG. 2A, the LED chip 12 further includes a conductive layer 125, a first pad P1 and a second pad P2. The conductive layer 125 is located on the side of the second semiconductor layer 124 away from the substrate 121, and is, for example, an indium tin oxide (ITO) layer. The first pad P1 is located on the side of the conductive layer 125 away from the substrate 121 and is connected with the conductive layer 125. For example, the first pad P1 can be in contact with the conductive layer 125 to be connected with the n-type semiconductor layer 124. The second pad P2 is located on the side of the first semiconductor layer 123 away from the substrate 121 and is connected with the first semiconductor layer 123, for example, in contact with the first semiconductor layer 123.

[0065] In some embodiments, referring to FIG. 2A, the LED chip 12 further includes a protective layer 126 on the side of the substrate 121 distal to the light emitting layer 122. As some implementations, the material of the protective layer 126 can include silicon nitride, silicon oxide, photoresist (PR gel), or other insulating material. In some embodiments, the LED chip 12 further includes a reflective layer RL on the side of the LED chip. In some embodiments, the LED chip 12 further includes an insulating layer IL between the reflective layer RL and the side of the LED chip. It can be appreciated that the insulating layer IL can not be necessary in the case that the reflective layer RL is not electrically conductive.

[0066] The polarizing structure 13 is on the light exit side of the LED chip 12.

[0067] As some implementations, referring to FIG. 2A, the polarizing structure 13 is between the LED chip 12 and the first substrate 11. In some embodiments, the polarizing structure 13 is between the electrically conductive layer 125 and the first substrate 11. For example, the polarizing structure 13 is between the buffer layer BF and the first substrate 11, the buffer layer BF is between the electrically conductive layer 125 and the polarizing structure 13. As some implementations, the material of the buffer layer BF can include silicon nitride or PR gel, or other insulating material.

[0068] As other implementations, referring to FIG. 2B, the polarizing structure 13 is on the side of the first substrate 11 distal to the LED chip 12.

[0069] The polarizing structure 13 is configured to transmit a first polarized light of the white light and reflect a second polarized light of the white light. Here, the polarization directions of the first and second polarized lights are different. As some implementations, the first polarized light is p light and the second polarized light is s light; as other implementations, the first polarized light is s light and the second polarized light is p light.

[0070] The backlight module 10 is configured to emit the first polarized light of the white light. It can be appreciated that which component of the backlight module 10 the first polarized light of the backlight module 10 eventually emits from depends on the position of the polarizing structure 13. For example, in the case shown in FIG. 2A, the first polarized light from the polarizing structure 13, after passing through the first substrate 11 (and in some cases also passing through the lens array 16 and the planarization layer 17), is the first polarized light that the backlight module 10 eventually emits. As another example, in the case shown in FIG. 2B, the white light from the LED chip 12, after passing through the first substrate 11 (and in some cases also passing through the lens array 16 and the planarization layer 17), is incident on the polarizing structure 13, and the first polarized light emitted from the polarizing structure 13 is the first polarized light that the backlight module 10 eventually emits.

[0071] In the above embodiments, the backlight module 10 includes the LED chip 12 emitting white light and the polarization structure 13 transmitting the first polarized light of the white light, and the backlight module 10 finally emits the first polarized light of the white light. In such a structure, the backlight module 10 does not need to additionally set a color conversion film to convert the light emitted by the LED chip 12 into white light, thereby reducing the number of film layers in the backlight module 10 and helping to improve the light extraction efficiency of the backlight module 10. In addition, since the backlight module 10 emits polarized light, the display panel of the display device using such a backlight module 10 also does not need to additionally set a polarizing sheet, thereby helping to improve the display brightness of the display device.

[0072] It can be understood that the reduction of the number of film layers in the backlight module 10 also helps to reduce power consumption and cost, thereby expanding the application field of the backlight module 10.

[0073] In some embodiments, the backlight module 10 further includes a first reflective layer 15, and the LED chip 12 is located between the first substrate 11 and the first reflective layer 15.

[0074] In some embodiments, the polarization structure 13 includes a metal wire grid. The inventors have found that, in the case of the LED chip 12 emitting white light, by adjusting the period, height, duty cycle and other parameters of the metal wire grid, the light extraction efficiency of the backlight module 10 can be further improved.

[0075] As some implementations, the period of the metal wire grid is 20-260 nm, for example, 40-200 nm, for example, 80 nm, 100 nm, 150 nm, etc. In this way, the light extraction efficiency of the backlight module 10 can be further improved.

[0076] As other implementations, the height of the metal wire grid is greater than 40 nm, for example, greater than 50 nm, for example, 80 nm, 100 nm, 120 nm, etc. In this way, the light extraction efficiency of the backlight module 10 can be further improved.

[0077] As yet other implementations, the duty cycle of the metal wire grid is 0.1-0.9, for example, 0.3-0.6, for example, 0.4, 0.5, etc. In this way, the light extraction efficiency of the backlight module 10 can be further improved.

[0078] In some embodiments, the parameter ranges of different parameters of the metal wire grid can be superimposed on each other, thereby further improving the light extraction efficiency of the backlight module 10.

[0079] In some implementations, the height of the metal wire grid is greater than 50 nm, and the duty cycle of the metal wire grid is 0.3-0.6. In this way, the light extraction efficiency of the backlight module 10 can be further improved.

[0080] In some implementations, the period of the metal wire grid is 40 nm to 200 nm, the height of the metal wire grid is greater than 50 nm, and the duty cycle of the metal wire grid is 0.3 to 0.6. In this way, the light extraction efficiency of the backlight module 10 can be further improved.

[0081] In some embodiments, the material of the metal wire grid is aluminum (Al), silver (Ag), gold (Au), copper (Cu), or titanium (Ti).

[0082] FIG. 2C is a schematic diagram showing the degree of polarization when the material of the metal wire grid is different. FIG. 2D is a schematic diagram showing the transmittance of the first polarized light when the material of the metal wire grid is different.

[0083] In FIG. 2C, L1 represents the curve of the degree of polarization when the material of the metal wire grid is aluminum, L2 represents the curve of the degree of polarization when the material of the metal wire grid is titanium, L3 represents the curve of the degree of polarization when the material of the metal wire grid is silver, L4 represents the curve of the degree of polarization when the material of the metal wire grid is gold, and L5 represents the curve of the degree of polarization when the material of the metal wire grid is copper.

[0084] In FIG. 2D, L1 represents the curve of the transmittance of the first polarized light when the material of the metal wire grid is aluminum, L2 represents the curve of the transmittance of the first polarized light when the material of the metal wire grid is titanium, L3 represents the curve of the transmittance of the first polarized light when the material of the metal wire grid is silver, L4 represents the curve of the transmittance of the first polarized light when the material of the metal wire grid is gold, and L5 represents the curve of the transmittance of the first polarized light when the material of the metal wire grid is copper.

[0085] As can be seen from FIGS. 2C and 2D, when the material of the metal wire grid is aluminum, both the degree of polarization and the transmittance of the first polarized light are relatively high. In this way, the light extraction efficiency of the backlight module 10 can be further improved.

[0086] As some implementations, the material of the metal wire grid is aluminum, the period of the metal wire grid is 80 nm to 140 nm (e.g., 90 nm, 100 nm, 120 nm, etc.), the height of the metal wire grid is 80 nm to 120 nm (e.g., 90 nm, 100 nm, 110 nm, etc.), and the duty cycle of the metal wire grid is 0.4 to 0.6 (e.g., 0.5, 0.55, etc.). In this way, the light extraction efficiency of the backlight module 10 can be further improved.

[0087] The inventors have also noticed that by improving the structure of the LED chip 12, the light extraction efficiency of the backlight module 10 can be further improved. This will be described in connection with some embodiments.

[0088] In some embodiments, referring to FIG. 2A, the polarization structure 13 is located between the LED chip 12 and the first substrate 11, and the LED chip 12 further includes a second reflective layer 127. The second reflective layer 127 is located on a side of the substrate 121 away from the light-emitting layer 122. For example, in the case where the LED chip 12 includes a protective layer 126, the second reflective layer 127 can be located between the substrate 121 and the protective layer 126.

[0089] The second reflective layer 127 is configured to reflect white light from the light-emitting layer 122 and reflect the second polarized light reflected by the polarization structure 13. In this way, on the one hand, the first polarized light of the white light reflected by the second reflective layer 127 can still be transmitted out of the polarization structure 13 after the white light reflected by the second reflective layer 127 is incident on the polarization structure 13; on the other hand, the first polarized light of the light after the second polarized light reflected by the polarization structure 13 is reflected by the second reflective layer 127 can still be transmitted out of the polarization structure 13 after the light is depolarized during the process of being incident on the polarization structure 13 through the film layers in the LED chip 12. In this way, the light utilization rate is improved, and the light extraction efficiency of the backlight module 10 is further improved.

[0090] In some embodiments, the material of the second reflective layer 127 includes a metal material or an organic material. As some implementations, the reflectivity of the metal material can be greater than 95%, for example, the metal material can include silver or aluminum. As some implementations, the organic material can be white oil.

[0091] In some embodiments, the second reflective layer 127 is a metal material layer, and the thickness of the second reflective layer 127 is greater than 50 nanometers, for example, 70 nanometers, 90 nanometers, etc. In this way, the reflection effect of the second reflective layer 127 on light is further improved, and the light utilization rate is further improved, thereby further improving the light extraction efficiency of the backlight module 10.

[0092] As some implementations, the second reflective layer 127 is a silver layer, and the thickness of the second reflective layer 127 is 80 nanometers to 120 nanometers, for example, 90 nanometers, 100 nanometers, etc. In this way, the reflection effect of the second reflective layer 127 on light is further improved, and the light utilization rate is further improved, thereby further improving the light extraction efficiency of the backlight module 10.

[0093] FIG. 3A is a schematic diagram of an LED chip according to some embodiments.

[0094] In some embodiments, referring to FIG. 3A, the LED chip 12 further includes a polarization conversion structure 128. The polarization conversion structure 128 is located on the side of the substrate 121 away from the light-emitting layer 122. For example, in the case where the LED chip 12 includes a protective layer 126, the polarization conversion structure 128 can be located between the substrate 121 and the protective layer 126.

[0095] The polarization conversion structure 128 is configured to convert the second polarized light reflected by the polarization structure 13 into the first polarized light. In this way, the utilization of light is further improved, thereby further improving the light extraction efficiency of the backlight module 10.

[0096] In one or more embodiments, the polarization conversion structure 128 can include a metasurface structure. In this way, the conversion efficiency of converting the second polarized light into the first polarized light can be improved by using the metasurface structure, thereby further improving the light extraction efficiency of the backlight module 10.

[0097] For the LED chip emitting white light, the parameters of the metasurface structure in the following ranges help to further improve the light extraction efficiency of the backlight module 10. The following implementations are described next.

[0098] As some implementations, the refractive index of the metasurface structure is greater than 1.8, and the aspect ratio of the metasurface structure is greater than 5. For example, the refractive index of the metasurface structure is 2.1, 2.2, 2.3, etc.; for example, the aspect ratio of the metasurface structure is 8, 9, 10, etc.

[0099] As other implementations, the thickness of the metasurface structure is greater than 500 nanometers, and the period of the metasurface structure is greater than 200 nanometers. For example, the thickness of the metasurface structure is 700 nanometers, 800 nanometers, 900, etc.; for example, the period of the metasurface structure is 300 nanometers, 400 nanometers, 500 nanometers, etc.

[0100] As yet other implementations, the refractive index of the metasurface structure is greater than 1.8, the aspect ratio of the metasurface structure is greater than 5, the thickness of the metasurface structure is greater than 500 nanometers, and the pitch of the metasurface structure is greater than 200 nanometers. In this way, the light extraction efficiency of the backlight module 10 is further improved.

[0101] FIG. 3B is a schematic diagram illustrating a metasurface structure according to some implementations.

[0102] In FIG. 3B, the substrate BS has a nanopillar PR as a metasurface structure. In some embodiments, the material of the nanopillar PR is SiNx. FIG. 3B also shows the depth (i.e., thickness), width, and period of the nanopillar PR.

[0103] FIG. 4A is a schematic diagram illustrating an LED chip according to other embodiments.

[0104] As shown in FIG. 4A, the LED chip 12 further includes a depolarization structure 129. The depolarization structure 129 is located on the side of the substrate 121 away from the light-emitting layer 122. In some embodiments, in the case that the LED chip 12 includes the protective layer 126, the depolarization structure 129 can be located between the substrate 121 and the protective layer 126. For example, the depolarization structure 129 can be located between the substrate 121 and the second reflective layer 127.

[0105] The depolarization structure 129 is configured to change the second polarized light into non-polarized light. In this way, the first polarized light of the non-polarized light from the depolarization structure 129 can be transmitted by the polarization structure 13 again after being incident on the polarization structure 13, which improves the utilization of light and thus improves the light extraction efficiency of the backlight module 10.

[0106] FIGS. 4B-4D are schematic diagrams showing depolarization structures according to different implementations.

[0107] In the implementation shown in FIG. 4B, the LED chip 12 further includes the second reflective layer 127. It should be noted that, in the implementations shown in FIGS. 4B-4D, although the LED chip 12 is shown as including the second reflective layer 127, this is not limiting. For example, in the implementations shown in FIGS. 4B-4D, the LED chip 12 can also not include the second reflective layer 127.

[0108] As shown in FIGS. 4B and 4C, the depolarization structure 129 includes a random structure 1291 and a filling material layer 1292 covering the random structure 1291. In some embodiments, the filling material layer 1292 includes an organic material. It should be understood that the random structure 1291 mentioned herein can be a structure in which one or more parameters are randomly distributed. For example, the parameters can include one or more of size, arrangement, distribution density, etc. As some implementations, the size can include the size in different directions, such as height, width, etc. In other words, one or more of the size, shape, arrangement, and distribution density of the random structure 1291 can be randomly distributed.

[0109] In the implementation shown in FIG. 4B, the random structure 1291 is located on the side of the second reflective layer 127 close to the substrate 121; and the filling material layer 1292 covers the random structure 1291 and is located between the second reflective layer 127 and the substrate 121. For example, the random structure 1291 can be formed on the surface of the second reflective layer 127 close to the substrate 121 by an annealing process. It should be understood that the shape of the random structure 1291 shown in FIG. 4B is merely schematic.

[0110] In the implementation shown in FIG. 4C, the random structure 1291 is located on the side of the substrate 121 away from the light-emitting layer 122, and the random structure 1291 is integrally formed with the substrate 121. In some embodiments, the random structure 1291 can be formed on the surface of the substrate 121 away from the light-emitting layer 122 by a wet etching process or by embossing. For example, the substrate 121 is a semiconductor substrate such as a GaN substrate or a GaAs substrate. The random structure 1291 is formed by etching the semiconductor substrate or embossing the semiconductor substrate. In the implementation shown in FIG. 4C, the random structure 1291 can include protrusions and recesses with different shapes.

[0111] In the implementation shown in FIG. 4D, the depolarization structure 129 includes an adhesive layer 1294 doped with particles 1293. The adhesive layer 1294 is located on the side of the substrate 121 away from the light-emitting layer 122. In some embodiments, the adhesive layer 1294 is located between the substrate 121 and the second reflective layer 127. As some implementations, the adhesive layer 1294 is a glue layer.

[0112] The particles 1293 in the adhesive layer 1294 can include at least one of scattering particles and reflective particles. In some embodiments, the particles 1293 in the adhesive layer 1294 include scattering particles and reflective particles to more effectively change the second polarized light into non-polarized light. As some implementations, the particles 1293 include one or more of air particles and metal particles.

[0113] It should be noted that FIG. 4D only schematically shows that the shapes of the plurality of particles 1293 are circular or elliptical, however, this is not limiting. In other embodiments, the shapes of the particles 1293 can also be other shapes, for example, irregular shapes, etc.

[0114] FIG. 5 is a schematic diagram showing a backlight module according to some other embodiments of the present disclosure.

[0115] As shown in FIG. 5, the backlight module 10 further includes an encapsulation layer 14 covering the LED chip 12, and a first reflective layer 15 covering the surface of the encapsulation layer 14 away from the substrate 11. The first reflective layer 15 is configured to reflect the white light from the LED chip 12 to the light-emitting side of the LED chip 12. Here, the shape of the encapsulation layer 14 and the first reflective layer 15 constitute a reflective lens to reflect the white light from the LED chip 12 to the light-emitting side of the LED chip 12. For example, the surface of the encapsulation layer 14 is a curved surface, for example, a hemispherical surface, etc.

[0116] In some embodiments, the encapsulation layer 14 is a glue layer. In some embodiments, the material of the first reflective layer 15 is, for example, white oil.

[0117] In the above embodiments, the encapsulation layer 14 covering the LED chip 12 and the first reflective layer 15 covering the surface of the encapsulation layer 14 cooperate with each other to reflect the white light from the LED chip 12 to the light-out side of the LED chip 12. In this way, as many light rays as possible can be made to be incident to the light-out side of the LED chip 12, thereby further improving the light-out efficiency of the backlight module 10.

[0118] FIGS. 6A and 6B are schematic diagrams illustrating a display device according to some embodiments of the present disclosure. FIGS. 6C and 6D are schematic diagrams illustrating a display device according to some other embodiments of the present disclosure.

[0119] As shown in FIGS. 6A, 6B, 6C and 6D, the display device includes the backlight module 10 and the display panel 20. It should be understood that the display device further includes liquid crystal LC between the backlight module 10 and the display panel 20.

[0120] The display panel 20 includes an array substrate 21 and a color filter substrate 22. In some embodiments, referring to FIGS. 6A and 6B, the array substrate 21 is closer to the backlight module 10 than the color filter substrate 22. In some other embodiments, the color filter substrate 22 is closer to the backlight module 10 than the array substrate 21, i.e., the positions of the array substrate 21 and the color filter substrate 22 in FIGS. 6A and 6B are interchanged.

[0121] The one of the array substrate 21 and the color filter substrate 22 that is closer to the backlight module 10 includes a second substrate 211.

[0122] In some embodiments, referring to FIGS. 6A and 6B, the array substrate 21 includes the second substrate 211 and a pixel driving circuit 212 on a side of the second substrate 211 away from the backlight module 10, and the color filter substrate 22 includes a third substrate 221 and a color filter layer 222 on a side of the third substrate 221 close to the array substrate 21. As some implementations, the second substrate 211 and the third substrate 221 can both be glass substrates.

[0123] In some other embodiments, referring to FIGS. 6C and 6D, the color filter substrate 22 includes the second substrate 211 and the color filter layer 222 on a side of the second substrate 211 away from the backlight module 10, and the array substrate 21 includes the third substrate 221 and the pixel driving circuit 212 on a side of the third substrate 221 close to the color filter substrate 22.

[0124] The backlight module 10 in the display device can be the backlight module 10 of any of the above embodiments. Referring to FIGS. 6A and 6B, the backlight module 10 further includes a lens array 16 and a planarization layer 17. The lens array 16 is disposed on the side of the first substrate 11 distal to the LED chip 12, and the lens array 16 is configured such that the first polarized light emitted by the backlight module 10 is incident on the opening region of the display panel 20. The planarization layer 17 covers the surface of the lens 16a in the lens array 16. In some embodiments, the material of the planarization layer 17 can include a resin material or optical glue.

[0125] In the above embodiments, the backlight module 10 includes the lens array 16 configured such that the first polarized light emitted by the backlight module 10 is incident on the opening region of the display panel 20. In some embodiments, the backlight module 10 does not need to additionally provide a diffusion sheet and a prism sheet, has no optical distance, and also has no iron stand used in the direct type backlight module in the related art. Therefore, the light extraction efficiency of the backlight module is higher, and the weight is also smaller.

[0126] In some embodiments, the arrayed light spots emitted from the lens array 16 are one-to-one incident on the opening regions of the display panel 20, i.e., one light spot is incident on one opening region. It can be understood that the density of the light spots is related to the resolution of the display panel. The more the number of the lenses 16a corresponding to a single LED chip 12, the more the number of the light spots formed, and the higher the resolution of the corresponding display panel. The less the number of the lenses 16a corresponding to a single LED chip 12, the less the number of the light spots formed, and the lower the resolution of the corresponding display panel.

[0127] In some embodiments, the absolute value of the difference between the refractive index of the first substrate 11 and the refractive index of the lens array 16 is less than or equal to 0.15, for example, 0.12, 0.11, etc. In this way, the refractive index of the first substrate 11 and the refractive index of the lens array 16 are as close as possible, so that as many light rays as possible can pass through the lens array 16 from the first substrate 11.

[0128] In some embodiments, the difference between the refractive index of one of the planarization layer 17 and the lens array 16 closer to the first substrate 11 and the refractive index of the other is greater than 0. For example, referring to FIG. 6A, the planarization layer 17 is closer to the first substrate 11 than the lens array 16; in this case, the refractive index of the planarization layer 17 is greater than the refractive index of the lens array 16. For another example, referring to FIG. 6B, the lens array 16 is closer to the first substrate 11 than the planarization layer 17; in this case, the refractive index of the lens array 16 is greater than the refractive index of the planarization layer 17. In this way, the adverse effects of waveguide effect can be reduced, so that more light rays can be emitted from the lens array 16, thereby further improving the light extraction efficiency of the backlight module 10.

[0129] In some embodiments, the difference between the refractive index of one of the planarization layer 17 and the lens array 16 closer to the first substrate 11 and the refractive index of the other is greater than or equal to 0.1. In this way, the adverse effects of waveguide effect can be further reduced, so that more light can be emitted from the lens array 16, thereby further improving the light extraction efficiency of the backlight module 10.

[0130] FIG. 6A shows the aperture R and the sag H of the lens 16a in the lens array 16.

[0131] In some embodiments, the aperture R of the lens 16a in the lens array 16 is less than 100 microns, for example, 90 microns, 80 microns, 85 microns, etc. In this way, the impact on the polarization degree of the light emitted by the lens array 16 can be reduced, for example, the depolarization degree is less than 10%.

[0132] In some embodiments, the aperture R and the sag H of the lens 16a in the lens array 16 are both less than 100 microns, for example, 90 microns, 80 microns, 85 microns, etc. In this way, the impact on the polarization degree of the light emitted by the lens array 16 can be further reduced.

[0133] In some embodiments, at least one of the aperture R and the sag H of the lens 16a in the lens array 16 is less than 75 microns, for example, 60 microns, 55 microns, 50 microns, etc. As some implementations, the aperture R and the sag H of the lens 16a in the lens array 16 are both less than 75 microns. In this way, the impact on the polarization degree of the light emitted by the lens array 16 can be further reduced, for example, the depolarization degree is less than 0.5%.

[0134] According to different application scenarios, the lens array 16 can adopt different types of lens arrays.

[0135] In some embodiments, the lens array 16 is a meta-lens array. For example, in the case of a display device being a virtual reality (VR) head-mounted display device, or a wearable display device such as a watch, the lens array 16 can be a meta-lens array. In this way, it is helpful to realize the thinning of the display device.

[0136] In other embodiments, the lens array 16 is a micro-lens array. As some implementations, the micro-lens array can be a free-form surface micro-lens array. For example, it can be designed according to the opening area of the display panel. The light emitted by the LED chip converges into an array of light spots after passing through the free-form surface micro-lens array, which can realize a more free light spot size and shape, thereby improving the utilization rate of light.

[0137] For example, referring to FIG. 6A, the lens array 16 is an inverted microlens array. For another example, referring to FIG. 6B, the lens array 16 is a positive microlens array. For the inverted microlens array, the lenses 16a in the lens array are convex to the first substrate 11, i.e., protrude in the direction from the display panel 20 to the backlight module 10. For the positive microlens array, the lenses 16a in the lens array are convex to the display panel 20, i.e., protrude in the direction from the backlight module 10 to the display panel 20.

[0138] FIGS. 7A and 7B are schematic diagrams of light intensity after light rays pass through a positive microlens array and an inverted microlens array, respectively.

[0139] As can be seen from FIGS. 7A and 7B, the light paths of transmission and refraction of the light rays are different in the case of using the positive microlens array and the inverted microlens array, and the inverted microlens array can make more light rays exit. That is, in the case of the lens array 16 being an inverted microlens array, it is helpful to further improve the light extraction efficiency of the backlight module 10.

[0140] FIGS. 8A and 8B are schematic diagrams of light intensity distribution and luminance distribution in the case of the backlight module having a microlens array, respectively. The light intensity distribution and the luminance distribution are obtained by simulation based on the opening area corresponding to the resolution of 200 PPI of the display device in the case of using 4x4 LED chips.

[0141] As can be seen from FIG. 8A, the light passing through the opening area is dot-matrixed, which is consistent with the expected design.

[0142] As can be seen from FIG. 8B, the luminance remains substantially constant within the range of ±60° (i.e., within the range of 120°) and does not change greatly with the angle. In the case shown in FIG. 8B, the luminance uniformity is about 81.79%.

[0143] As can be seen from the simulation results of FIGS. 8A and 8B, in the case of using the backlight module having the LED chip emitting white light and the microlens array, the display device has high uniformity of luminance distribution.

[0144] FIG. 9 is a schematic diagram showing an arrangement of LED chips according to some embodiments of the present disclosure.

[0145] FIG. 9 shows three arrangements of the LED chip array. Px can be regarded as the distance between two adjacent LED chips 12 in a first direction, and Py can be regarded as the distance between two adjacent LED chips 12 in a second direction. Here, the second direction is perpendicular to the first direction. For example, the first direction is the horizontal direction, and the second direction is the vertical direction.

[0146] In some embodiments, Px and Py are determined with the same position of LED chip 12 as a reference. For example, Px is determined with the right edge of LED chip 12 as a reference; for another example, Px is determined with the center of the upper edge of LED chip 12 as a reference; for yet another example, Py is determined with the upper edge of LED chip 12 as a reference.

[0147] As shown in FIG. 9, the LED chip array composed of multiple LED chips 12 can be arranged in a square (Px = Py) as shown in FIG. 9a, an oblong (Px ≠ Py) as shown in FIG. 9b, or an equilateral triangle (Py = 0.866Px) as shown in FIG. 9c.

[0148] In some embodiments, the arrangement of LED chips 12 can be selected with the maximum uniformity of light intensity and brightness distribution as a reference. For example, in the case of a Lambertian light-emitting LED chip, the LED chips 12 can be arranged in an equilateral triangle with the maximum uniformity of brightness distribution as a reference.

[0149] FIGS. 10A and 10B are schematic diagrams showing the light rays emitted by the LED chips and incident on the opening region after passing through the microlens array according to different embodiments of the present disclosure.

[0150] In some embodiments, referring to FIGS. 6A, 6B and 10A, the array substrate 21 in the display panel 20 includes a second substrate 211 and a light shielding layer 213 located on the side of the second substrate 211 away from the backplate module 10. In this case, the light shielding layer 213 defines the opening region V. The pixel driving circuit 212 can be located on the side of the second substrate 211 and the light shielding layer 213 away from the backplate module 10. For example, the material of the light shielding layer 213 includes a metal material, such as a metal stack. In some embodiments, the metal stack is Mo / Al / Mo; in other embodiments, the metal stack is Mo / Cu / Mo.

[0151] In other embodiments, referring to FIGS. 6C, 6D and 10B, the color film substrate 22 in the display panel 20 includes a second substrate 211 and a light shielding layer 223 located on the side of the second substrate 211 away from the backplate module 10. In this case, the light shielding layer 223 defines the opening region V. The color film layer 222 can be located on the side of the second substrate 211 and the light shielding layer 223 away from the backplate module 10. In some embodiments, the material of the light shielding layer 223 is a black matrix.

[0152] The display panel 20 satisfies the following formula so that the first polarized light emitted by the back light module 10 is incident on the opening region V of the display panel 20:

[0153] n1 / T1+n2 / T2 = 1 / f; and

[0154] f = R / 2(n4-n3).

[0155] In the above formula, n1 is the refractive index of the first substrate 11, T1 is the thickness of the first substrate 11, n2 is the refractive index of the second substrate 211, T2 is the thickness of the second substrate 211, f is the focal length of the lens 16a in the lens array 16, R is the aperture of the lens 16a, n4 is the refractive index of the planarization layer 17 and one of the lens array 16 closer to the first substrate 11, and n3 is the refractive index of the other of the planarization layer 17 and the lens array 16. Note that FIG. 10 illustrates a case where n4 is the refractive index of the planarization layer 17 and n3 is the refractive index of the lens array 16.

[0156] It is understood that, according to the above formula, unknown parameters of some components can be determined according to known parameters of other components.

[0157] As an example, for a display device with a resolution of 400 PPI, if it is known that the refractive index n1 of the first substrate 11 and the refractive index n2 of the second substrate 211 are both 1.5, the thickness T1 of the first substrate 11 is 0.5 mm, the thickness T2 of the second substrate 211 is 0.2 mm, the refractive index of the lens 16a in the lens array 16 is 1.5, and the refractive index n4 of the planarization layer 17 is 1.4, then the aperture R of the lens 16a in the microlens array can be determined to be 63.5 um.

[0158] FIGS. 11A and 11B are schematic diagrams illustrating display devices according to yet other embodiments of the present disclosure. FIGS. 12A and 12B are schematic diagrams illustrating display devices according to still other embodiments of the present disclosure.

[0159] In FIGS. 11A, 11B, 12A, and 12B, the polarization structure 13 is located between the display panel 20 and the lens array 16.

[0160] In some embodiments, referring to FIGS. 11A and 12A, the polarization structure 13 is in contact with the second substrate 211 in the display panel 20 and in contact with the lens array 16.

[0161] In other embodiments, referring to FIGS. 11B and 12B, the polarization structure 13 is in contact with the second substrate 211 in the display panel 20 and in contact with the planarization layer 17.

[0162] In FIGS. 11A and 12A, the lens array 16 is an inverted microlens array. In FIGS. 11B and 12B, the lens array 16 is a normal microlens array.

[0163] The backlight module 10 shown in FIGS. 12A and 12B includes an encapsulation layer 14 covering the LED chip 12, and a first reflective layer 15 covering the surface of the encapsulation layer 14. The first reflective layer 15 is configured to reflect the white light from the LED chip 12 to the light exit side of the LED chip 12.

[0164] It should be noted that the backlight module 10 and the display device are introduced above in combination with different embodiments. The backlight modules 10 of different embodiments can be combined with each other, so that the light exit efficiency of the backlight module 10 can be further improved. The display devices of different embodiments can also be combined with each other, so that the brightness of the display device can be further improved.

[0165] FIG. 13 is a flow diagram illustrating a manufacturing method of a backlight module according to some embodiments of the present disclosure.

[0166] As shown in FIG. 13, the manufacturing method of the backlight module includes steps 1302-1306. The backlight module is configured to emit first polarized light of white light.

[0167] In step 1302, an LED chip is provided. Here, the LED chip can include a substrate, and a light emitting layer configured to emit white light on one side of the substrate. The related descriptions of the substrate and the light emitting layer can be referred to the above. The structure of various embodiments of the LED chip can also be referred to the description above.

[0168] In step 1304, a polarization structure is formed on the light exit side of the LED chip. Here, the polarization structure is configured to transmit first polarized light of the white light, and reflect second polarized light of the white light, the polarization directions of the first polarized light and the second polarized light being different. For example, the polarization structure is a metal wire grating structure.

[0169] In step 1306, the LED chip is mounted on the first substrate.

[0170] For example, the polarization structure shown in FIG. 2A can be formed first, and then the LED chip is mounted on the first substrate. In this case, the polarization structure is located between the LED chip and the first substrate.

[0171] For another example, the LED chip can be mounted on the first substrate first, and then the polarization structure shown in FIG. 2B is formed. In this case, the polarization structure is located on the side of the first substrate away from the LED chip. In some embodiments, the micro-lens array and the planarization layer covering the lenses of the micro-lens array can be formed on the side of the first substrate away from the LED chip first, and then the polarization structure is formed.

[0172] Next, some implementation manners of providing the LED chip are introduced.

[0173] First, a substrate is provided.

[0174] Then, a second reflective layer is deposited on one side of the substrate. For example, the second reflective layer introduced above is deposited on one side of the substrate.

[0175] After the second reflective layer is deposited, a light emitting layer is formed on the side of the substrate away from the second reflective layer. The second reflective layer is configured to reflect white light from the light emitting layer, and to reflect the second polarized light reflected by the polarizing structure.

[0176] For example, after the light emitting layer and other layers (e.g., semiconductor layers, etc.) of the LED chip are formed, the polarizing structure is formed.

[0177] In the above embodiments, the second reflective layer is first deposited on one side of the substrate, and then other layers of the LED chip are formed on the other side of the substrate. Compared with forming the second reflective layer by a mounting process at the end, this manner helps to reduce the adverse effects of the mounting process on the light emitting efficiency of the LED chip, thereby improving the light emitting efficiency of the LED chip.

[0178] Next, the manufacturing method of the microlens array is introduced in combination with some embodiments.

[0179] In some embodiments, the microlens array can be formed by imprinting. As some implementation manners, the microlens array can be formed by: first, coating a glue layer on a substrate; then, imprinting the microlens array on the glue layer by imprinting; next, curing the glue layer into the microlens array by temperature control or light control (e.g., using ultraviolet light); and then, forming a planarization layer to cover the microlens array. This manner can form an upright microlens array and an inverted microlens array.

[0180] In other embodiments, the microlens array can be formed by photolithography. This is explained below in combination with FIG. 14.

[0181] FIG. 14 is a schematic diagram showing the formation of a microlens array according to some embodiments of the present disclosure.

[0182] As shown in FIG. 14, the steps of forming the microlens array include steps S1-S4.

[0183] First, in step S1, a glue layer 16a is coated on a first substrate 11.

[0184] Next, in step S2, the glue layer 16a is patterned by a photolithography and etching process to form a glue layer array 16b.

[0185] Then, in step S3, the glue layer array 16b is softened by heating to form a microlens array 16.

[0186] Afterwards, in step S4, a planarization layer 17 is formed on the surface of the microlens array 16 to obtain a flat surface. For example, a glue layer can be filled as the planarization layer 17. It should be understood that the formed planarization layer 17 helps to improve the problem of uncontrollable light path due to surface wear of the lens, and the planarization layer 17 is more convenient for integration with the display panel.

[0187] The effective utilization rate of the light emitted by the backlight module according to some embodiments of the present disclosure is 59.2%. Compared with 10.8% in the related art, the backlight utilization rate of some embodiments of the present disclosure is 5.4 times that of the related art. For example, 100% of the white light emitted from the light-emitting layer of the LED chip has a transmittance of 46.6% after passing through the film layer in the LED chip, and the single-polarized light (i.e., the first polarized light) after the white light passes through the polarization structure is 46.6%*42%=19.572%, and the effective utilization rate of the light after the single-polarized light passes through the array substrate with a transmittance of 55.2% is: 19.572%*55.2%=10.80%.

[0188] The display device provided by some embodiments of the present disclosure can be a liquid crystal display device sensitive to power consumption, with high demand for brightness, requirement for local dimming, or requirement for thickness. For example, the display device is a vehicle-mounted display device, a virtual reality (VR) device, an augmented reality (AR) device, a mixed reality (MR) device, an extended reality (XR), a mobile terminal (such as a mobile phone), a display, a notebook computer, a projector, a tablet computer, or an interactive whiteboard, etc.

[0189] So far, the embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein according to the above description.

[0190] Although some specific embodiments of the present disclosure have been described in detail through examples, those skilled in the art should understand that the above examples are only for illustration, not for limiting the scope of the present disclosure. Those skilled in the art should understand that the above embodiments can be modified or some technical features can be replaced equivalently without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A backlight module, comprising: a first substrate; a light emitting diode (LED) chip mounted on the first substrate, the LED chip comprising a substrate and a light emitting layer on a side of the substrate configured to emit white light; and a polarization structure on an emission side of the LED chip configured to transmit first polarized light of the white light and reflect second polarized light of the white light, the first polarized light and the second polarized light having different polarization directions, wherein the backlight module is configured to emit the first polarized light.

2. The backlight module of claim 1, further comprising: a first reflective layer, wherein the LED chip is between the first substrate and the first reflective layer. the polarization structure is between the LED chip and the first substrate.

3. The backlight module according to any one of claims 1-2, wherein, the LED chip further comprises:

4. The backlight module of claim 3, wherein, a first semiconductor layer on a side of the light emitting layer closer to the substrate; a second semiconductor layer on a side of the light emitting layer farther from the substrate, wherein the second semiconductor layer has a different conductivity type than the first semiconductor layer; a conductive layer on a side of the second semiconductor layer farther from the substrate; a first pad on a side of the conductive layer farther from the substrate and connected to the conductive layer; and a second pad on a side of the first semiconductor layer farther from the substrate and connected to the first semiconductor layer, wherein the polarization structure is between the conductive layer and the first substrate. the LED chip further comprises:

5. The backlight module of claim 3 or 4, wherein, a second reflective layer on a side of the substrate farther from the light emitting layer configured to reflect the white light from the light emitting layer and the second polarized light reflected by the polarization structure. the LED chip further comprises:

6. The backlight module of claim 3 or 4, wherein, a polarization conversion structure on a side of the substrate farther from the light emitting layer configured to convert the second polarized light reflected by the polarization structure into the first polarized light. the polarization conversion structure comprises a metasurface structure having a refractive index greater than 1.8 and a depth-to-width ratio greater than 5.

7. The backlight module of claim 6, wherein, the metasurface structure has a thickness greater than 500 nanometers and a pitch greater than 200 nanometers.

8. The backlight module of claim 7, wherein, the LED chip further comprises:

9. The backlight module of claim 3 or 4, wherein, a depolarization structure on a side of the substrate farther from the light emitting layer configured to change the second polarized light into unpolarized light.

10. The backlight module of claim 9, wherein: the LED chip further comprises a second reflective layer on a side of the substrate farther from the light emitting layer configured to reflect the white light from the light emitting layer and the second polarized light reflected by the polarization structure; and the depolarization structure comprises: a random structure on a side of the second reflective layer closer to the substrate, and a filler material layer covering the random structure and between the second reflective layer and the substrate. the depolarization structure comprises:

11. The backlight module of claim 9, wherein, a random structure on a side of the substrate farther from the light emitting layer, the random structure being integrally formed with the substrate; and a filler material layer covering the random structure. the depolarization structure comprises:

12. The backlight module of claim 9, wherein, ​ An adhesion layer doped with particles is located on a side of the substrate distal from the light emitting layer, wherein the particles include at least one of scattering particles and reflective particles.

13. The backlight module of any of claims 1-12, further comprising: an encapsulation layer covering the LED chip; and a first reflective layer covering a surface of the encapsulation layer distal from the substrate, configured to reflect the white light from the LED chip to a light exit side of the LED chip.

14. The backlight module of any of claims 1-13, wherein, The polarization structure includes a metal wire grid, wherein: a period of the metal wire grid is 20-260 nanometers; a height of the metal wire grid is greater than 40 nanometers; and a duty cycle of the metal wire grid is 0.1-0.

9.

15. A display device, comprising: a display panel; and the backlight module of any of claims 1-14, wherein the backlight module further comprises: a lens array disposed on a side of the first substrate distal from the LED chip, configured to cause the first polarized light exiting the backlight module to be incident to an opening region of the display panel, and a planarization layer covering a surface of a lens in the lens array.

16. The display device of claim 15, wherein, The lens array is a microlens array, and an absolute value of a difference between a refractive index of the first substrate and a refractive index of the lens array is less than or equal to 0.

15.

17. A display device according to claim 15 or 16, wherein, The lens array is a microlens array, and a difference between a refractive index of the planarization layer and a refractive index of the one of the lens array closer to the first substrate is greater than 0.

18. The display device of claim 17, wherein, The difference is greater than or equal to 0.

1.

19. A display device according to any one of claims 15 to 18, wherein, The lens array is a microlens array, a diameter of the lens in the lens array is less than 100 micrometers, and a sag of the lens is less than 100 micrometers.

20. The display of claim 19, wherein, At least one of the diameter and the sag of the lens is less than 75 micrometers.

21. A display device according to any one of claims 15 to 20, wherein, The lens array is a microlens array, and the lens in the lens array is convex to the first substrate.

22. A display device according to any one of claims 15 to 21, wherein, The display panel includes an array substrate and a color filter substrate, and the one of the array substrate and the color filter substrate closer to the backlight module includes a second substrate and a light blocking layer on a side of the second substrate distal from the backlight module, the light blocking layer defining the opening region, wherein the display device satisfies: n1 / T1+n2 / T2=1 / f, and f=R / 2(n4-n3); wherein n1 is a refractive index of the first substrate, T1 is a thickness of the first substrate, n2 is a refractive index of the second substrate, T2 is a thickness of the second substrate, f is a focal length of the lens in the lens array, R is a diameter of the lens, n4 is a refractive index of the one of the planarization layer and the lens array closer to the first substrate, and n3 is a refractive index of the other of the planarization layer and the lens array.

23. A method of manufacturing a backlight module, comprising: providing an LED chip including a substrate and a light emitting layer on a side of the substrate configured to emit white light; A polarization structure is formed on a light-emitting side of the LED chip, the polarization structure is configured to transmit first polarized light of the white light and reflect second polarized light of the white light, the polarization directions of the first polarized light and the second polarized light are different; And The LED chip is mounted on a first substrate, Wherein, the backlight module is configured to emit the first polarized light.

24. The manufacturing method of claim 23, wherein, The polarization structure is located between the LED chip and the first substrate, Wherein, the providing LED chip comprises: Providing the substrate; Depositing a second reflective layer on one side of the substrate; and After depositing the second reflective layer, forming the light-emitting layer on the side of the substrate away from the second reflective layer, Wherein, the second reflective layer is configured to reflect the white light from the light-emitting layer, and reflect the second polarized light reflected by the polarization structure.

Images