Backlight unit, light emitting substrate, and display device

Abstract

The application discloses a backlight unit, a light-emitting substrate and a display device, and aims to improve light emission uniformity. The backlight unit provided by the application comprises a first substrate, a first reflection layer, a light-emitting unit and a light guide layer. The first substrate comprises a first surface and a second surface opposite to each other, and a first groove on the first surface. The first reflection layer covers at least part of the bottom of the first groove. The light-emitting unit is located on the side of the first groove away from the second surface. The light guide layer comprises a first light guide layer and / or a second light guide layer. The first light guide layer is located on the second surface or on the side of the second surface away from the first surface, and the orthographic projection of the first light guide layer on the first substrate overlaps with the first groove. The second light guide layer is located on the bottom of the first groove, and the first reflection layer covers at least part of the second light guide layer.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to a backlight unit, a light-emitting substrate, and a display device. Background Technology

[0002] Passive light emission display devices mainly consist of a display panel and a backlight module. The display panel is located on the light-emitting side of the backlight module and is used to modulate the light emitted from the backlight module to achieve image display. Due to the trend of display devices becoming thinner, the thinning of the backlight module is a research hotspot in the industry. Summary of the Invention

[0003] This application provides a backlight unit, a light-emitting substrate, and a display device to improve light emission uniformity.

[0004] This application provides a backlight unit, which includes: a first substrate, a first reflective layer, a light-emitting unit, and a light guide layer;

[0005] The first substrate includes: a first surface and a second surface opposite to each other, and a first groove located on the first surface;

[0006] The first reflective layer covers at least a portion of the bottom area of ​​the first groove;

[0007] The light-emitting unit is located on the side of the first groove that faces away from the second surface;

[0008] The light guide layer includes a first light guide layer and / or a second light guide layer; the first light guide layer is located on the second surface or on the side of the second surface away from the first surface, and the orthographic projection of the first light guide layer on the first substrate overlaps with the first groove; the second light guide layer is located at the bottom of the first groove, and the first reflective layer covers at least part of the second light guide layer.

[0009] In some embodiments, the light guide layer includes a first light guide layer, and the first surface outside the first groove is a plane.

[0010] In some embodiments, the bottom of the first groove includes: a protrusion that protrudes toward one side of the first surface; and a first reflective layer covering the protrusion;

[0011] The protrusion includes a first part and a second part; the orthographic projection of the second part on the second surface surrounds the orthographic projection of the first part on the second surface;

[0012] The protrusion includes a third surface on the side opposite to the second surface;

[0013] At least a portion of the third surface is located on the first arc surface; the first arc surface includes: a first sub-arc surface corresponding to the first portion and a second sub-arc surface corresponding to the second portion;

[0014] The angle between the tangent of the first sub-arc surface and the second surface is greater than the angle between the tangent of the second sub-arc surface and the second surface.

[0015] The orthographic projection of the first light guide layer on the second surface overlaps with the orthographic projection of the area at the bottom of the first groove outside the first part and the protrusion on the second surface, and the orthographic projection of the first light guide layer on the second surface does not overlap with the orthographic projection of the second part on the second surface.

[0016] In some embodiments, the third surface is a first arc surface; the fourth surface is a second arc surface.

[0017] In some embodiments, the first light guide layer includes: a plurality of first light guide structures, wherein the first light guide structure is a protrusion structure or a groove structure;

[0018] The orthographic projection of the first light guide layer on the second surface includes: a first region, a second region surrounding the first region, and a third region surrounding the second region;

[0019] The first region and the second part coincide on the orthographic projection of the second surface, and the second region covers the orthographic projection of the first groove outside the protrusion on the second surface.

[0020] The first region, the second region, and the third region are not completely identical in one of the following: the density of the first light guide structure, the scattering angle or reflection angle of the first light guide structure, and the aspect ratio D / H of the first light guide structure; wherein, D is the maximum width of the first light guide structure in the direction parallel to the second surface, and H is the maximum thickness of the first light guide structure in the direction perpendicular to the second surface.

[0021] In some embodiments, the light guide layer includes a second light guide layer, the bottom of the first groove includes a protrusion, and at least the side of the protrusion facing away from the second surface includes the second light guide layer.

[0022] In some embodiments, the light guide layer further includes: a third light guide layer; the third light guide layer is located on the first surface or on the side of the first surface facing away from the second surface;

[0023] The orthographic projection of the third light guide layer on the second surface surrounds the orthographic projection of the first groove on the second surface.

[0024] In some embodiments, the bottom of the first groove includes: a protrusion and a connecting portion connected to the protrusion; the orthographic projection of the connecting portion on the second surface surrounds the orthographic projection of the protrusion on the second surface.

[0025] The orthographic projection of the first reflective layer on the second surface coincides with the orthographic projection of the protrusion and the connecting part on the second surface.

[0026] The backlight unit further includes: a second reflective layer located on the side of the first surface away from the second surface; the second reflective layer includes a first opening, the orthographic projection of the first opening on the second surface overlaps with the orthographic projection of the protrusion on the second surface, and the orthographic projection of the second reflective layer on the second surface covers the orthographic projection of the connecting portion on the second surface.

[0027] The width L1 of the orthographic projection of the connecting part onto the second surface in the direction parallel to the second surface satisfies:

[0028] L1≥R×tan(θc); R is the distance between the edge of the connecting part away from the protrusion and the second reflective layer in the direction perpendicular to the second surface.

[0029] In some embodiments, the surface of the connecting portion away from the second surface is a plane parallel to the second surface, or the angle between the surface of the connecting portion away from the second surface and the second surface is greater than 0°.

[0030] In some embodiments, the protrusion and the side of the connector facing away from the second surface include a second light guide layer.

[0031] In some embodiments, the light guide layer is located on one side of the first substrate, and the difference between the refractive index of the light guide layer located on one side of the first substrate and the refractive index of the first substrate is less than or equal to 0.2.

[0032] In some embodiments, the material of the first substrate includes at least one of the following: glass, polymethyl methacrylate, and polycarbonate;

[0033] The material of the light guide layer located on one side of the first substrate includes at least one of the following: polyvinyl chloride, polyvinyl alcohol, polylactic acid, polymethyl methacrylate, polyvinylpyrrolidone, polyethylene terephthalate, and polycarbonate.

[0034] In some embodiments, the light guide layer located on one side of the first substrate is bonded to the first substrate, and the distance between the edge of the light guide layer located on one side of the first substrate and the edge of the second surface is less than 0.03 mm.

[0035] This application provides a method for fabricating a backlight unit, comprising:

[0036] A first substrate is provided; and a first groove is formed on a first surface of the first substrate; the first substrate further includes: a second surface opposite to the first surface;

[0037] A first reflective layer is formed covering at least a portion of the bottom of the first groove;

[0038] A light-emitting unit is disposed on the side of the first reflective layer that faces away from the second surface;

[0039] The method further includes: forming a light guide layer; the light guide layer includes a first light guide layer and / or a second light guide layer; the first light guide layer is located on the second surface or on the side of the second surface opposite to the first surface, and the orthographic projection of the first light guide layer on the first substrate overlaps with the first groove; the second light guide layer is located at the bottom of the first groove, and the first reflective layer covers at least a portion of the second light guide layer.

[0040] In some embodiments, the light guide layer includes a first light guide layer, and forming the light guide layer includes:

[0041] Multiple first light-guiding structures are formed on the second surface;

[0042] Alternatively, a light guide layer is formed on the side of the second surface away from the first surface, and the light guide layer is patterned to form multiple first light guide structures;

[0043] Alternatively, a first light guide layer may be attached to the side of the second surface opposite to the first surface, the first light guide layer comprising a plurality of first light guide structures.

[0044] In some embodiments, the light guide layer includes a second light guide layer, and forming the light guide layer includes:

[0045] While forming the first groove, multiple second light guide structures are formed on the bottom surface of the first groove.

[0046] In some embodiments, before or after forming the second light guide layer, the method further includes:

[0047] A pattern of a second reflective layer is formed on the side of the first surface opposite to the second surface; the second reflective layer includes a first opening, the orthographic projection of the first opening on the second surface overlaps with the orthographic projection of the second light guide layer on the second surface, and the orthographic projection of the second reflective layer on the second surface overlaps with the orthographic projection of the first groove on the second surface.

[0048] In some embodiments, before forming the pattern of the second reflective layer on the side of the first surface opposite to the second surface, the method further includes:

[0049] A third light guide layer is formed on the first surface or on the side of the first surface opposite to the second surface; the orthographic projection of the third light guide layer on the second surface surrounds the orthographic projection of the first groove on the second surface.

[0050] This application provides a light-emitting substrate, which includes multiple backlight units provided in this application.

[0051] An embodiment of this application provides a display device, including a display panel and a light-emitting substrate provided in this application embodiment;

[0052] The display panel is located on the side of the second surface away from the light-emitting unit.

[0053] The backlight unit, its fabrication method, light-emitting substrate, and display device provided in this application embodiment include a first light guide layer and / or a second light guide layer. The first light guide layer is located on a second surface or on the side of the second surface facing away from the first surface, i.e., the first light guide layer is disposed on the light-emitting side of the backlight unit. Furthermore, the area where the first light guide layer is disposed overlaps with the area where the first groove is disposed, meaning that the area corresponding to the first groove can also be modulated by the first light guide layer, improving the light emission uniformity of the area corresponding to the first groove, thereby improving the light emission uniformity of different areas of the backlight unit. The second light guide layer is located at the bottom of the first groove, so that at least a portion of the area corresponding to the bottom of the first groove can also be modulated by the second light guide layer, improving the light emission uniformity of the area corresponding to the first groove, thereby improving the light emission uniformity of different areas of the backlight unit. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 A schematic diagram of the structure of a backlight unit provided for related technologies;

[0056] Figure 2 This is a schematic diagram of the structure of a backlight unit provided in an embodiment of the present disclosure;

[0057] Figure 3 This is a schematic diagram of another backlight unit provided in an embodiment of the present disclosure;

[0058] Figure 4 This is a schematic diagram of the structure of another backlight unit provided in an embodiment of the present disclosure;

[0059] Figure 5 This is a schematic diagram of the structure of another backlight unit provided in an embodiment of the present disclosure;

[0060] Figure 6 This is a schematic diagram of the structure of another backlight unit provided in an embodiment of the present disclosure;

[0061] Figure 7 This is a schematic diagram of the structure of another backlight unit provided in an embodiment of the present disclosure;

[0062] Figure 8 This is a schematic diagram of the structure of another backlight unit provided in an embodiment of the present disclosure;

[0063] Figure 9 This is a schematic diagram of the structure of another light-emitting substrate provided in an embodiment of the present disclosure;

[0064] Figure 10 This is a schematic diagram of the structure of another backlight unit provided in an embodiment of the present disclosure;

[0065] Figure 11 This is a schematic diagram of the structure of another backlight unit provided in an embodiment of the present disclosure;

[0066] Figure 12 This is a schematic diagram of the structure of another backlight unit provided in an embodiment of the present disclosure;

[0067] Figure 13 This is a schematic diagram of the structure of another backlight unit provided in an embodiment of the present disclosure;

[0068] Figure 14 This is a schematic diagram of the structure of another backlight unit provided in an embodiment of the present disclosure;

[0069] Figure 15 This is a schematic diagram of the structure of another backlight unit provided in an embodiment of the present disclosure;

[0070] Figure 16 A spectral diagram of different regions of a backlight unit is provided for related technologies;

[0071] Figure 17 A density distribution diagram of the first light guide structure in different regions of a backlight unit provided in an embodiment of this disclosure;

[0072] Figure 18 A brightness diagram of different regions of a backlight unit provided in an embodiment of this disclosure;

[0073] Figure 19 This is a schematic diagram of the structure of another backlight unit provided in an embodiment of the present disclosure;

[0074] Figure 20 This is a schematic diagram of the structure of another backlight unit provided in an embodiment of the present disclosure;

[0075] Figure 21 This is a schematic diagram of the structure of another backlight unit provided in an embodiment of the present disclosure;

[0076] Figure 22 This is a schematic diagram of the structure of another backlight unit provided in an embodiment of the present disclosure;

[0077] Figure 23 A schematic flowchart illustrating a method for fabricating a backlight unit according to an embodiment of this disclosure;

[0078] Figure 24 A schematic flowchart illustrating another method for fabricating a backlight unit according to an embodiment of this disclosure;

[0079] Figure 25A schematic flowchart illustrating another method for fabricating a backlight unit according to an embodiment of this disclosure;

[0080] Figure 26 A schematic flowchart illustrating another method for fabricating a backlight unit according to an embodiment of this disclosure;

[0081] Figure 27 This is a schematic diagram of the structure of a display device provided in an embodiment of the present disclosure. Detailed Implementation

[0082] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Furthermore, the embodiments and features in the embodiments of this application can be combined with each other without conflict. All other embodiments obtained by those skilled in the art based on the described embodiments of this application without creative effort are within the scope of protection of this application.

[0083] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0084] It should be noted that the dimensions and shapes of the figures in the accompanying drawings do not reflect actual proportions and are intended only to illustrate the content of this application. Furthermore, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0085] In related technologies, such as Figure 1As shown, the backlight module's light-emitting substrate includes a glass substrate 15, a second reflective layer 5, a light-transmitting filling portion 6, a third reflective layer 13, a color conversion structure 4, dot matrix 14, and a light-emitting unit 3. The glass substrate 15 has a groove, the third reflective layer 13 covers the protrusion of the groove as a reflective bowl, the light-transmitting filling portion 6 fills the groove, the second reflective layer 5 has an opening, and the area outside the opening covers the light-transmitting filling portion 6 and the glass substrate 15. The color conversion structure 4 is located at least between the light-transmitting filling portion 6 and the light-emitting unit 3 in the opening area of ​​the second reflective layer 5. Thus, the light emitted by the light-emitting unit 3 passes through the color conversion structure 4 and then exits from the side of the glass substrate 15 away from the groove. This eliminates the need for an additional quantum dot film outside the light-emitting structure for color conversion, reducing the thickness of the backlight module. However, as... Figure 1 As shown, based on the light emission pattern, the light-emitting substrate is divided into a dot-matrix uniform light area B3, a direct light emission area B1, a reflector bowl platform area B2, and a reflector bowl curved area B4. A1 is a normal waveguide light, captured by dot 14. The brightness is uniform through dot 14 adjustment; that is, light reaching dot 14 in the dot-matrix uniform light area B3 can be emitted uniformly. A2 is the light directly emitted from the direct light emission area B1, with brightness varying with the viewing angle. A3 is the light emitted directly after reflection by the reflector bowl and then by the roof reflection formed by the second reflective layer 5; its brightness also varies with the viewing angle. This is the light emitted directly from the groove area corresponding to the direct light emission area B1, and its brightness varies with the viewing angle. A4 is the light reaching the reflector bowl platform area B2, affected by waveguide light from other adjacent periods. Because the reflector bowl platform area B2 is smooth, it has no light-capturing capability. A5 is the light reaching the reflector bowl curved area B4; affected by the slope of the curved surface, different light-capturing angles result in significant brightness differences at different viewing angles. Because the light-shielding area, the reflector plateau area, and the reflector arc area lack dot matrix for light homogenization, the reflection spectra of these areas are inconsistent, resulting in poor uniformity of the emitted light brightness from the light-emitting substrate.

[0086] This application provides a backlight unit, such as... Figure 2 , Figure 3 As shown, the backlight unit includes: a first substrate 1, a first reflective layer 2, a light-emitting unit 3, and a light guide layer 10;

[0087] The first substrate 1 includes: a first surface S1 and a second surface S2 opposite to each other, and a first groove 101 located on the first surface S1;

[0088] The first reflective layer 2 covers at least a portion of the bottom area of ​​the first groove 101;

[0089] The light-emitting unit 3 is located on the side of the first groove 101 that is away from the second surface S2;

[0090] The light guide layer 10 includes a first light guide layer 1001 and / or a second light guide layer 1002; the first light guide layer 1001 is located on the second surface S2 or on the side of the second surface S2 away from the first surface S1, and the first light guide layer 1001 overlaps with the first groove 101 in the orthographic projection of the first substrate 1; the second light guide layer 1002 is located at the bottom of the first groove 101, and the first reflective layer 2 covers at least part of the second light guide layer 1002.

[0091] The backlight unit provided in this application embodiment includes a first light guide layer and / or a second light guide layer. The first light guide layer is located on the second surface or on the side of the second surface away from the first surface, that is, the first light guide layer is disposed on the light-emitting side of the backlight unit. Furthermore, the area where the first light guide layer is disposed overlaps with the area where the first groove is disposed, meaning that the area corresponding to the first groove can also be modulated by the first light guide layer, improving the light emission uniformity of the area corresponding to the first groove, thereby improving the light emission uniformity of different areas of the backlight unit. The second light guide layer is located at the bottom of the first groove, so that at least a portion of the area corresponding to the bottom of the first groove can also be modulated by the second light guide layer, improving the light emission uniformity of the area corresponding to the first groove, thereby improving the light emission uniformity of different areas of the backlight unit.

[0092] In some embodiments, such as Figure 2 As shown, the light-emitting unit 3 covers the first groove 101 in the orthographic projection of the first substrate 1.

[0093] In practical implementation, the light-emitting unit is used to provide a backlight source. The light-emitting unit 3 can be a light-emitting diode (LED), a mini light-emitting diode (Mini LED), or a micro light-emitting diode (Micro LED), etc. The main difference between LEDs, Mini LEDs, and Micro LEDs lies in their size. LEDs typically have a planar dimension greater than 200 micrometers (μm), Mini LEDs typically have a planar dimension between 50 μm and 200 μm, and Micro LEDs typically have a planar dimension less than 50 μm. The light-emitting unit 3 can also be an organic light-emitting diode (OLED), etc., without limitation.

[0094] In some embodiments, the first substrate is used to support other structures disposed thereon. The shape and size of the first substrate are adapted to the shape and size of the display device to which it is applied. Generally, the shape of the first substrate can be square, rectangular, etc. When applied to irregularly shaped display devices, the shape of the first substrate can also be circular or other irregular shapes, without limitation. The first substrate can be made of transparent substrate materials commonly used in the display technology field. The transparent substrate material can be glass; or, the transparent substrate material can be poly(methyl methacrylate) (PMMA), also known as acrylic or plexiglass; the transparent substrate material can also be polycarbonate (PC), also known as PC plastic.

[0095] In some embodiments, the first reflective layer is used to reflect light around the first groove to achieve a uniform light effect.

[0096] In some embodiments, such as Figure 2 , Figure 3 As shown, the bottom of the first groove 101 includes a protrusion 1011 that protrudes toward the first surface S1; the first reflective layer 2 covers the protrusion 1011.

[0097] In some embodiments, such as Figure 2 , Figure 3 As shown, the bottom of the first groove 101 protrudes upward to form a protrusion 1011, and the first reflective layer 2 covers the surface of the protrusion 1011 to improve the light uniformity effect. In specific implementations, the protrusion 1011 can be formed in various ways. In some embodiments, when etching the first substrate 1 to form the first groove 101, a portion of the first substrate 1 located in the central region of the first groove 101 can be retained to form the protrusion 1011. The bottom of the first groove 101 can also be a flat structure, a recessed structure, an uneven structure, or other structures, which are not limited here.

[0098] In some embodiments, such as Figure 2 , Figure 3 As shown, the protrusion 1011 includes a first part F1 and a second part F2; the orthographic projection of the second part F2 onto the second surface S2 surrounds the orthographic projection of the first part F1 onto the second surface S2.

[0099] The protrusion 1011 includes a third surface S3 on the side opposite to the second surface S2;

[0100] At least a portion of the third surface S3 is located on the first arc surface S4; the first arc surface S4 includes: a first sub-arc surface S401 corresponding to the first portion F1 and a second sub-arc surface S402 corresponding to the second portion F2.

[0101] The angle between the tangent of the first sub-arc surface S401 and the second surface S2 is greater than the angle between the tangent of the second sub-arc surface S402 and the second surface S2.

[0102] That is, the curvature of the second sub-arc surface is gentler than that of the first sub-arc surface. For example, the area corresponding to the second part is the reflector bowl platform area B2 in the related technology, that is, when the first light guide layer is not provided on the protrusion or one side of the second surface, the area corresponding to the second part is the area where the light from the waveguide in the first substrate cannot be extracted. The area corresponding to the first part is the reflector bowl arc area B4 in the related technology.

[0103] In some embodiments, such as Figure 2 , Figure 3 As shown, the surface of the first reflective layer 2 facing away from the second surface S2 is parallel to the third surface S3.

[0104] In some embodiments, such as Figure 2 As shown, if the third surface S3 does not include the second light guide layer, then the third surface S3 is the first arc surface S4.

[0105] In some embodiments, such as Figure 3 As shown, if the third surface S3 includes the second light guide layer 1002, a portion of the third surface S3 is located on the first arc surface S4.

[0106] In some embodiments, such as Figure 2 , Figure 3 As shown, the first arc surface S4 is symmetrical with respect to the cross section perpendicular to the second surface S2 and passing through the geometric center M1 of the orthographic projection of the protrusion 1011 onto the second surface S2. Both parts of the first arc surface S4 that are symmetrical with respect to the cross section perpendicular to the second surface S2 and passing through the geometric center of the orthographic projection of the protrusion 1011 onto the second surface S2 protrude toward the side of the second surface S2.

[0107] In some embodiments, the angle between the tangent of the second sub-arc surface and the second surface is a first included angle, and the first included angle θ1 satisfies:

[0108] 0°≤θ1<θc / 2; where θc is the critical angle of the first basis; n is the refractive index of the first substrate.

[0109] In some embodiments, when the material of the first substrate is glass, n is greater than or equal to 1.49 and less than or equal to 1.51; when the material of the first substrate is PMMA, n is greater than or equal to 1.47 and less than or equal to 1.49; when the material of the first substrate is PC, n is greater than or equal to 1.57 and less than or equal to 1.60.

[0110] In some embodiments, 39°≤θc≤43°.

[0111] Taking the refractive index of the first substrate as 1.5 as an example, and θc as 42°, then 0≤θ1<21°.

[0112] In some embodiments, such as Figure 2 , Figure 3 As shown, the light-emitting substrate also includes:

[0113] The light-transmitting filling portion 6 is located within the first groove 101 on the side of the protrusion 1011 opposite to the bottom of the first groove 101. That is, the light-transmitting filling portion 6 fills the first groove 101, improving flatness.

[0114] In some embodiments, the absolute value of the difference between the refractive index of the light-transmitting filling portion and the refractive index of the first substrate is less than or equal to 0.2. Having a refractive index similar to that of the first substrate helps to avoid a reduction in light efficiency. For example, the absolute value of the difference between the refractive index of the light-transmitting filling portion and the refractive index of the first substrate is 0.1, 0.15, or 0.2.

[0115] To further reduce light efficiency loss, in some embodiments, the absolute value of the difference between the refractive index of the light-transmitting filling portion and the refractive index of the first substrate is less than or equal to 0.05.

[0116] The backlight unit provided in this application embodiment has an absolute value of the difference between the refractive index of the light-transmitting filling portion and the refractive index of the first substrate that is less than or equal to 0.05, that is, the difference in refractive index between the two is small, thereby avoiding a large difference in refractive index between the two leading to a reduction in light efficiency.

[0117] In some embodiments, the material of the light-transmitting filling portion includes at least one of the following: polyvinyl chloride (PVC), polyvinyl alcohol (PVA), polylactic acid (PLA), PMMA, polyvinyl pyrrolidone (PVP), polyethylene glycol terephthalate (PET), and PC. That is, the light-transmitting filling portion is a highly transparent material. Based on this, the material of the first substrate includes at least one of the following: glass, polymethyl methacrylate, and polycarbonate. The refractive index difference between the two is small, thereby avoiding a large difference in refractive index that would lead to a decrease in light efficiency.

[0118] In some embodiments, such as Figure 2 , Figure 3 As shown, the surface of the light-transmitting filling portion 6 facing away from the second surface S2 is flush with the portion outside the first groove 101 of the first surface S1.

[0119] In some embodiments, such as Figure 2 , Figure 3 As shown, the light-emitting substrate also includes:

[0120] The color conversion structure 4 is located on the side of the first reflective layer 2 that is away from the first substrate 1.

[0121] In the backlight unit provided in this application embodiment, the color conversion structure is used to convert the color of the light emitted by the light-emitting unit to the desired color. The color conversion structure can be made of fluorescent material or quantum dot material, and is not limited thereto. For example, the light-emitting unit can be a blue LED, and the color conversion structure can be made of quantum dot material, converting the blue light emitted by the light-emitting unit into white light for backlighting. Alternatively, the light-emitting unit can be a white LED, which directly emits white light, and the color conversion structure can be made of transparent material, allowing white light to pass through directly. The color conversion structure can also be air, and is not limited thereto.

[0122] In some embodiments, such as Figure 2 , Figure 3 As shown, the orthographic projection of the light-transmitting filling part 6 on the second surface S2 covers the orthographic projection of the first groove 101 on the second surface S2; the light-transmitting filling part 6 covers the first reflective layer 2, and the light-transmitting filling part 6 fills the first groove 101.

[0123] The color conversion structure 4 is located on the side of the light-transmitting filling part 6 that is away from the second surface S2.

[0124] Alternatively, in some embodiments, such as Figure 4 As shown, the light-transmitting filling part 6 includes a second opening 601 that exposes a portion of the first reflective layer 2, that is, the orthographic projection of the second opening 601 on the second surface S2 is located within the orthographic projection of the first reflective layer 2 on the second surface S2.

[0125] The color conversion structure 4 is located at least within the second opening 601; that is, the color conversion structure 4 includes a portion located at least within the first groove 101, the color conversion structure 4 is in contact with the first reflective layer 2, and the orthographic projection of the color conversion structure 4 on the second surface S2 falls into the orthographic projection of the first reflective layer 2 on the second surface S2.

[0126] The backlight unit provided in this application embodiment includes a color conversion structure that includes at least a portion located within the first groove. This allows the color conversion structure to fully convert the color of light incident on the first substrate through the second opening, ensuring color accuracy and increasing luminous efficiency. Furthermore, the second opening exposes a portion of the first reflective layer; that is, the orthographic projection of the second opening onto the second surface lies within the orthographic projection of the first reflective layer onto the second surface. This prevents the color conversion structure from having a portion that does not cover the first reflective layer and instead emits light directly, thus avoiding direct light exposure that could affect brightness uniformity.

[0127] In some embodiments, such as Figures 2-4 As shown, the backlight unit also includes a second reflective layer 5 located on the side of the first surface S1 away from the second surface S2; the second reflective layer 5 includes a first opening 501, and the orthographic projection of the first opening 501 on the second surface S2 falls into the orthographic projection of the protrusion 1011 on the second surface S2.

[0128] The second reflective layer 5 overlaps with the first groove 101 in the orthographic projection of the first substrate 1.

[0129] In the backlight unit provided in this embodiment, the second reflective layer overlaps with the first groove in the orthographic projection of the first substrate. That is, the second reflective layer has a portion located above the first groove, forming an eaves structure relative to the first groove. This eaves structure can reflect light, improving light utilization. Furthermore, the light emitted from the light-emitting unit, after multiple reflections by the protrusion and the second reflective layer, exhibits a certain degree of diffusion and light uniformity, reducing the need for a diffusion film and further reducing the thickness of the light-emitting substrate, thus facilitating the thinning requirements of display devices.

[0130] In some embodiments, such as Figure 2 , Figure 5 As shown, the color conversion structure 4 also includes a portion located within the first opening 501.

[0131] In some embodiments, such as Figure 2 As shown, the color conversion structure 4 also includes a portion located outside the first opening 501 and on the side of the second reflective layer 5 away from the second surface S2, and the orthographic projection of the first opening 501 onto the second surface S2 falls within the orthographic projection of the color conversion structure 4 onto the second surface S2. Figure 2 The color conversion structure 4 includes a portion covering the second reflective layer 5 and a portion located within the first opening 501.

[0132] Alternatively, in some embodiments, such as Figure 5 As shown, the surface of the color conversion structure 4 facing away from the second surface S2 is flush with the surface of the second reflective layer 5 facing away from the second surface S2.

[0133] Alternatively, in some embodiments, such as Figure 3 As shown, the light-transmitting filling part 6 also includes a part located in the first opening 501. The surface of the light-transmitting filling part 6 facing away from the second surface S2 and the surface of the second reflective layer 5 facing away from the second surface S2 are located on the same plane, that is, the light-transmitting filling part 6 fills the first groove 101 and the first opening 501.

[0134] The color conversion structure 4 is located on the side of the second reflective layer 5 and the light-transmitting filling part 6 that is away from the second surface S2;

[0135] The orthographic projection of the color conversion structure 4 onto the second surface S2 covers the orthographic projection of the first opening 501 onto the second surface S2.

[0136] In some embodiments, such as Figure 3 As shown, the color conversion structure 4 is in contact with the second reflective layer 5 and the light-transmitting filling part 6.

[0137] Alternatively, in some embodiments, such as Figure 6 As shown, the backlight unit also includes:

[0138] The planarization layer 25 is located between the color conversion structure 4 and the second reflective layer 5.

[0139] In some embodiments, such as Figure 4 As shown, when the light-transmitting filling portion 6 includes a second opening 601, the orthographic projection of the first opening 501 on the first substrate 1 coincides with the orthographic projection of the second opening 601 on the first substrate 1; the color conversion structure 4 includes a portion located within the first opening 501.

[0140] In some embodiments, such as Figure 3 , Figure 6 As shown, the backlight unit also includes an isolation dam 24. The isolation dam 24 is located between the second reflective layer 5 and the light-emitting unit 3. The isolation dam 24 forms an accommodating space around the first opening 501, and the color conversion structure 4 is disposed within the accommodating space. The isolation dam 24 can be used to define the position of the color conversion structure 4, that is, the isolation dam 24 surrounds the color conversion structure 4. In some embodiments, the isolation dam 24 can be made of a material with high reflectivity, thereby reflecting the light emitted from the color conversion structure 4 in all directions and improving the light utilization rate.

[0141] In some embodiments, such as Figure 3 , Figure 5 , Figure 6 As shown, the light-emitting substrate also includes:

[0142] The encapsulation planarization layer 9 is located on the side of the second reflective layer 5 and the color conversion structure 4 that is away from the first substrate 1; the orthographic projection of the encapsulation planarization layer 9 onto the first substrate 1 covers the orthographic projection of the second reflective layer 5 and the color conversion structure 4 onto the first substrate 1.

[0143] The backlight unit provided in this embodiment also includes a planarization layer. The planarization layer can protect the film layers such as the color conversion structure, thereby reducing the risk of failure of the color conversion structure due to water and oxygen erosion. The planarization layer can be a single-layer structure or a multi-layer structure, which is not limited here.

[0144] In some embodiments, such as Figure 5 As shown, the encapsulation planarization layer 9 covers the second reflective layer 5 and the color conversion structure 4.

[0145] Alternatively, in some embodiments, such as Figure 3 , Figure 6 As shown, the encapsulation planarization layer 9 covers the second reflective layer 5, the isolation dam 24, and the color conversion structure 4.

[0146] In some embodiments, such as Figures 2-6 As shown, the second reflective layer 5 is a single layer. This allows for a further reduction in the overall thickness of the light-emitting substrate.

[0147] In some embodiments, the material of the single-layer second reflective layer includes silver.

[0148] Alternatively, in some embodiments, such as Figure 7 As shown, the second reflective layer 5 includes: a first reflective sublayer 5-1 and a second reflective sublayer 5-2 located on the side of the first reflective sublayer 5-1 facing away from the first surface S1.

[0149] That is, by setting up a double-layered reflective sublayer to improve the support strength of the second reflective layer.

[0150] In some embodiments, the material of the first reflective sublayer includes silver, and the material of the second reflective sublayer includes molybdenum.

[0151] In some embodiments, such as Figure 7 , Figure 8 As shown, the first opening 501 penetrates the second reflective sublayer 5-2 and the first reflective sublayer 5-1.

[0152] In some embodiments, the first opening is circular or elliptical in shape. Of course, the first opening can also be other shapes.

[0153] In some embodiments, such as Figures 2-8 As shown, the backlight unit also includes a driving circuit layer 8. The driving circuit layer 8 is formed between the second reflective layer 5 and the light-emitting unit 3, or between the encapsulation planarization layer 9 and the light-emitting unit 3. A driving circuit is formed in the driving circuit layer 8 for driving the light-emitting unit 3 to emit light. The driving circuit layer 8 includes a first pad 801, and the light-emitting unit 3 includes a second pad 301. The second pad 301 of the light-emitting unit 3 is electrically connected to the circuit in the driving circuit layer 9 through the first pad 801.

[0154] In some embodiments, such as Figures 2-8 As shown, the backlight unit also includes a first encapsulation layer 7. The first encapsulation layer 7 is located on the side of the light-emitting unit 3 facing away from the first substrate 1. The first encapsulation layer 7 is disposed over its entire surface, thereby protecting the light-emitting unit 3 and other film layers. In specific implementations, the first encapsulation layer 7 can be made of materials with high reflectivity, such as white oil or white glue, so as to reflect light into the first opening and improve the utilization rate of light. No limitation is made here.

[0155] The backlight unit provided in this application embodiment may also include other structures necessary to achieve specific functions. These can be manufactured according to actual conditions during implementation and are not limited here. The structures of the above embodiments of this application can be arbitrarily combined without conflict, and the resulting structures will not be described in detail here.

[0156] In some embodiments, the light guide layer includes a matrix and a plurality of light guide structures disposed on the surface of the matrix. The light guide structures may be raised structures (such as...). Figure 11 (as shown) or groove structure (such as) Figure 2 , 4 As shown in Figures 5, 7, 19, and 21; the cross-sectional shape of the light guide structure in the direction perpendicular to the first / second surface can be at least one of a circle, a part of an ellipse, a triangle, a trapezoid, or a rectangle. The matrix material can also include transparent particulate materials with scattering function. By reasonably adjusting the concentration of the transparent particulate material, effective control of light output can be achieved, further realizing high uniformity of light output. Therefore, when light reaches the light guide structure of the light guide layer, it can be reflected and / or scattered, and the area where the light guide layer is set can improve the uniformity of light output brightness.

[0157] In some embodiments, the first light guide layer includes a first substrate and a plurality of first light guide structures disposed on the surface of the first substrate.

[0158] In some embodiments, such as Figure 2 , 4 As shown in Figures 5, 7, 19, and 21, the first substrate is the first base 1, or the first substrate 28 can form an integral structure with the first base 1; in other embodiments, such as Figures 9-11 As shown, the first substrate 28 is located on the second surface S2 of the first substrate 1.

[0159] In some embodiments, such as Figure 2 As shown, when the third surface S3 does not include the second light guide layer, the orthographic projection of the first light guide layer 1001 on the second surface S2 overlaps with the orthographic projection of the area at the bottom of the first groove 101 outside the first part F1 and the protrusion 1011 on the second surface S2, and the orthographic projection of the first light guide layer 1001 on the second surface S2 does not overlap with the orthographic projection of the second part F2 on the second surface S2.

[0160] The backlight unit provided in this application embodiment has an overlap between the orthographic projection of the first light guide layer on the second surface and the orthographic projection of the first portion on the second surface. This allows the light from the waveguide to be extracted in the area corresponding to the second portion, i.e., the reflector bowl platform area, while also ensuring the uniformity of light output in this area. The area at the bottom of the first groove outside the protrusion corresponds to the direct light emission area in related technologies. The overlap between the orthographic projection of the first light guide layer on the second surface and the orthographic projection of the area at the bottom of the first groove outside the protrusion on the second surface prevents the light from being directly emitted in this area, thus improving the uniformity of light output from various viewing angles in this area. Since the light from the waveguide can be extracted in the area corresponding to the first portion, i.e., the reflector bowl arc area, the light from the waveguide can be extracted throughout the entire area of ​​the first substrate.

[0161] It should be noted that, Figure 2 This illustration only shows the relationship between the orthographic projection of the first light guide layer 1001 on the second surface S2 and the orthographic projection of the second part F2 on the second surface S2. In the direction from the first part F1 to the second part F2, the ratio of the width of the orthographic projection of the second part F2 on the second surface S2 to the width of the first light guide structure 21 does not represent their actual ratio. That is, the number of first light guide structures 21 on the first light guide layer 1001 covered by the orthographic projection of the second part F2 on the second surface S2 does not represent the actual number. The width and number of first light guide structures 21 in the area covered by the orthographic projection of the second part F2 on the second surface S2 need to be set according to actual needs. For example, in the direction from the first part F1 to the second part F2, if the width of the orthographic projection of the second part F2 on the second surface S2 is less than or equal to 10 micrometers (μm), the width of the orthographic projection of the first light guide structure on the second surface is 4μm to 30μm. In the area covered by the orthographic projection of the second part F2 on the second surface S2, the width of the orthographic projection of the first light guide structure on the second surface can be set to 4μm to 10μm.

[0162] In some embodiments, such as Figure 2 , Figure 4 , Figure 5 , Figure 7 , Figures 9-11 As shown, the first light guide layer 1001 includes: a plurality of first light guide structures 21;

[0163] like Figure 11 As shown, the first light guide structure 21 is a raised structure, or as... Figure 2 , Figure 4 , Figure 5 , Figure 7 , Figures 9-10 As shown, the first light guide structure 21 is a groove structure.

[0164] in, Figure 2 , Figure 4 , Figure 5 , Figure 7 , Figure 9 Let's take an example where the cross-sectional shape of the groove structure is part of a circle. Figure 10 Let's take a triangular cross-sectional shape of the groove structure as an example for illustration. Figure 11 Taking a rectangular cross-sectional shape of the protruding structure as an example, the protruding structure can be, for instance, a scattering light guide structure. The cross-sectional shape of the protruding or recessed structure affects the emission angular spectrum of the light emitted from the first light guide layer. In practical implementation, the cross-sectional shape of the protruding or recessed structure can be selected to match the required emission angular spectrum type.

[0165] In some embodiments, such as Figure 12 As shown, the first light guide structure 21 has a dotted shape in its orthographic projection onto the second surface S2; the orthographic projections of multiple dotted first light guide structures 21 onto the second surface S2 surround the orthographic projection of the first portion F1 onto the second surface S2. The dotted first light guide structure 21 is characterized by a small dimensional difference in its orthographic projection onto the second surface S2 along various directions; for example, as... Figure 12 As shown, the shape of the orthographic projection of the first light-guiding structure 21 on the second surface S2 can be circular; or the shape of the orthographic projection of the groove structure on the second surface can be an approximately circular ellipse, square, or approximately square polygon, etc., without limitation. In specific implementations, the depth of the groove structure or the height of the protrusion structure can be set to 1 micrometer (μm) to 15 μm, without limitation. The maximum size of the orthographic projection of the first dot structure on the second surface can be set to 4 μm to 30 μm, without limitation. Specifically, the maximum size of the orthographic projection of the first dot structure on the second surface refers to the size of the orthographic projection of the groove structure or protrusion structure on the second surface in the direction of the largest aperture. For example, when the orthographic projection of the groove structure or protrusion structure on the second surface is circular, the maximum size refers to the diameter of the circle; when the orthographic projection of the groove structure or protrusion structure on the second surface is elliptical, the maximum size refers to the length of the major axis of the ellipse; when the orthographic projection of the groove structure or protrusion structure on the second surface is a square or other polygon, the maximum size refers to the length of the longest diagonal of the polygon; and so on when the orthographic projection of the groove structure or protrusion structure on the second surface is other shapes, without further explanation. In specific implementation, the distance between the orthographic projection of any first light guide structure on the second surface and the orthographic projection of the adjacent first light guide structure on the second surface can be set to 1μm to 10μm, and is not limited here.

[0166] Alternatively, in some embodiments, such as Figure 13As shown, the shape of the orthographic projection of the first light guide structure 21 on the second surface S2 is strip-shaped. The strip-shaped first light guide structure 21 is characterized in that its orthographic projection on the second surface S2 has the largest dimension along a certain direction and the smallest dimension perpendicular to that direction. For example, the shape of the orthographic projection of the first light guide structure 21 on the second surface S2 can be a rectangle or a polygon with a large difference between its length and width, or an ellipse or a shape with a large difference between its major axis length and minor axis length. No limitation is made here.

[0167] In some embodiments, such as Figure 14 As shown, the shape of the orthographic projection of the first light guide structure 21 onto the second surface S2 can be annular, and the orthographic projection of the first part F1 onto the second surface S2 is located within the annular shape formed by the orthographic projection of the first light guide structure 21 onto the second surface S2, without limitation.

[0168] In some embodiments, the shape of the orthographic projection of the first light guide structure onto the second surface can also be other shapes, which are not limited here.

[0169] In some embodiments, such as Figure 15 As shown, the orthographic projection of the first light guide layer 1001 onto the second surface S2 includes: a first region E1, a second region E2 surrounding the first region E1, and a third region E3 surrounding the second region E2.

[0170] The first region E1 and the second part F2 coincide in the orthographic projection of the second surface S2, and the second region E2 covers the orthographic projection of the first groove 101 outside the protrusion on the second surface S2.

[0171] The following are not completely identical in the first region E1, the second region E2, and the third region E3: the density of the first light guide structure 21, the scattering angle or reflection angle of the first light guide structure 21, and the aspect ratio D / H of the first light guide structure 21; wherein, D is the maximum width of the first light guide structure 21 in the direction parallel to the second surface S2, and H is the maximum thickness of the first light guide structure 21 in the direction perpendicular to the second surface S2.

[0172] The backlight unit provided in this application embodiment can adjust the output brightness of different regions by adjusting at least one of the density, scattering angle or reflection angle, and D / H of the first light guide structure in different regions, which is beneficial to improving the uniformity of output brightness in different regions of the backlight unit.

[0173] It should be noted that the morphology of the first light guide structure affects the emission angle of the light after it is modulated. Depending on the specific position of the first light guide structure, at least one of the following can be adjusted: density, scattering angle or reflection angle, and D / H, so that the emission angle spectrum of the light emitted by the backlight unit at that position meets the requirements.

[0174] In the actual design process, the density, scattering angle or reflection angle, and D / H of the first light guide structure in different areas can be dynamically adjusted according to the required brightness of different areas and the brightness of the surrounding areas, so as to make the difference in the output brightness of different areas of the final first substrate smaller.

[0175] It should be noted that when the first light guide structure is a protruding structure or a grooved structure that does not include transparent granular material, if the surface of the protruding structure facing away from the first surface or the surface of the grooved structure facing the first surface is planar (e.g., with a triangular or trapezoidal cross-section), then the light guide structure is called a directional light guide structure. If the surface of the protruding structure facing away from the first surface or the surface of the grooved structure facing the first surface is non-planar (e.g., curved), then the light guide structure is called a non-directional light guide structure. When the first light guide structure is a light guide structure including transparent granular material or a non-directional light guide structure, one of the following is not completely identical in the first region, the second region, and the third region: the density of the first light guide structure, the scattering angle of the first light guide structure, and the aspect ratio D / H of the first light guide structure. When the first light guide structure is a directional light guide structure, one of the following is not completely identical in the first region, the second region, and the third region: the density of the first light guide structure, the reflection angle of the first light guide structure, and the aspect ratio D / H of the first light guide structure. In practical implementation, at least one of the following can be adjusted according to the light emission angle spectrum of the first part of the protrusion: density, scattering angle or reflection angle, and D / H of the first light guide structure in different regions, so that the light emission angle spectrum of different regions of the backlight unit is approximately the same, thereby achieving uniform light emission brightness in different regions of the backlight unit.

[0176] It should be noted that, Figure 15 In this example, we will take the first light guide structure 21 in the first region E1, the second region E2 and the third region E3 as having different densities and the first light guide structure 21 being dot-shaped as an example for illustration.

[0177] In related technologies, such as Figure 1 The light emission angular spectra of regions B1, B2, B3, and B4 of the light-emitting substrate shown are as follows: Figure 16 As shown, the brightness uniformity of each region is poor. When the density of the first light guide structure in the first region E1, the second region E2, and the third region E3 is different, the density curves of the first light guide structure in different regions of the backlight unit provided in this application embodiment are as follows: Figure 17As shown, region E0 corresponds to the first part of the protrusion, and the density of the first light guide structure in region E0 is 0. In the direction away from region E0, the density of the first dots at different positions is not entirely the same. In the direction away from region E0, the density of the first light guide structure in the first region E1 gradually increases. In the direction away from region E0, the density of the first light guide structure in the second region E2 first increases and then decreases. The density change of the first light guide structure in the third region E3 is generally gradual. The embodiments provided in this application are as follows... Figure 2 The test results of the light output uniformity of the backlight unit are shown below. Figure 18 As shown, the size of the light-emitting unit is 0.12 mm × 0.12 mm, the depth of the first groove is 0.05 mm, and the total thickness of the first substrate is 0.3 mm; according to Figure 18 It can be seen that the brightness difference at each test location is small. By adjusting the density of the first light guide structure in different areas of the backlight unit, the uniformity of the emitted light brightness of the backlight unit can be improved.

[0178] In some embodiments, the distribution of the first light guide structures is centrally symmetrical with respect to the center of the first groove. That is, in regions at the same distance from the center of the first groove, the density, shape, and D / H of the first light guide structures are the same.

[0179] In some embodiments, when the light guide layer 10 includes a first light guide layer 1001, such as Figure 2 , Figure 4 , Figure 5 , Figure 7 As shown, the first light guide layer 1001 is located on the second surface S2; or, as... Figures 9-11 As shown, the first light guide layer 1001 is located on the side of the second surface S2 that faces away from the first surface S1. That is, the first light guide layer 1001 is set independently of the first substrate 1. In specific implementations, the first light guide layer can be attached to one side of the second surface, or the material of the first light guide layer can be coated on one side of the second surface and then a patterning process can be performed to form the first light guide layer.

[0180] In some embodiments, such as Figure 2 , Figure 4 , Figure 5 , Figure 7 , Figures 9-11 As shown, when the light guide layer 10 includes the first light guide layer 1001, the first surface S1 outside the first groove 101 is a plane.

[0181] The backlight unit provided in this application embodiment can improve the light emission uniformity by setting a first light guide layer on one side of the second surface. Therefore, the first surface outside the first groove does not need to be set with a light guide layer, which can avoid increasing the process and save costs. The interface between the second reflective layer and the first surface is a reflective surface.

[0182] In some embodiments, such as Figure 3 , Figure 19 As shown, the light guide layer 10 includes a second light guide layer 1002.

[0183] In some embodiments, such as Figure 3 , Figure 19 As shown, at least the surface of the protrusion 1011 facing away from the second surface S2, i.e., the third surface S3, includes a second light guide layer 1002; the second light guide layer 1002 includes a plurality of second light guide structures 22, which are protrusion structures or groove structures (not shown). Thus, when light reaches the second light guide structure of the second light guide layer, it can be reflected and / or scattered, and the area where the light guide layer is provided can improve the uniformity of the emitted light brightness.

[0184] In some embodiments, the second light guide layer further includes a second matrix. Figure 3 , Figure 19 The second substrate is the bottom of the first groove 101 of the first substrate 1.

[0185] In some embodiments, when the surface of the protrusion facing away from the second surface includes the second light guide layer, at least the second portion of the surface facing away from the second surface includes the second light guide layer.

[0186] The backlight unit provided in this application embodiment includes a second light guide layer on the surface of the second part facing away from the second surface, so that the light from the waveguide can also be extracted in the area corresponding to the second part, i.e., the reflector platform area, and the uniformity of light output in this area can also be guaranteed.

[0187] In some embodiments, when the surface of the protrusion facing away from the second surface includes a second light guide layer, both the first portion and the second portion of the surface facing away from the second surface include the second light guide layer. This can further improve the light emission uniformity of the region corresponding to the protrusion.

[0188] In some embodiments, such as Figure 19 As shown, the backlight unit may simultaneously include a first light guide layer 1001 and a second light guide layer 1002. Alternatively, in some embodiments, such as Figure 3 As shown, the backlight unit includes a second light guide layer 1002 but does not include a first light guide layer 1001.

[0189] When the backlight unit does not include the first light guide layer, in some embodiments, such as Figure 3 As shown, the light guide layer 10 further includes: a third light guide layer 1003; the third light guide layer 1003 is located on the first surface S1 or on the side of the first surface S1 away from the second surface S2;

[0190] The orthographic projection of the third light guide layer 1003 on the second surface S2 surrounds the orthographic projection of the first groove 101 on the second surface S2.

[0191] In some embodiments, such as Figure 3 As shown, the third light guide layer 1003 includes a plurality of third light guide structures 23; the third light guide structure 23 is a protrusion structure (not shown) or a groove structure.

[0192] In some embodiments, the third light guide layer further includes a third matrix. It should be noted that... Figure 3 Taking the third substrate as an example of the first substrate 1, the third light guide structure 23 is located on the first surface S1, so there is no need to set an additional third light guide layer on the first surface. This can reduce the front projection thickness of the light-emitting substrate. Furthermore, since the number of film layers between the first substrate and the second reflective layer is reduced, the loss of light during propagation can also be reduced, which is beneficial to improving the light efficiency.

[0193] The cross-sectional shape of the third light guide structure can be triangular, a portion of a circle, a portion of an ellipse, rectangular, trapezoidal, etc. Figure 3 The example illustrates this by using a portion of a circle as the cross-sectional shape of the third light guide structure 23. In practical implementation, the cross-sectional shape of the third light guide structure can be selected to match the required light emission spectral type.

[0194] In some embodiments, the orthographic projection of the third light guide structure onto the second surface is in the shape of a dot, a strip, or a ring. Of course, the orthographic projection of the third light guide structure onto the second surface can also be other shapes, which are not limited here.

[0195] In some embodiments, when the third light guide layer is located on the side of the first surface away from the second surface, the backlight unit further includes a cover portion disposed in the same layer as the third light guide layer and integrally connected thereto; the orthographic projection of the cover portion on the second surface coincides with the orthographic projection of the first groove on the second surface, that is, the cover portion covers the light-transmitting filling portion, so that the cover portion can play a planarization role.

[0196] In some embodiments, such as Figure 20 As shown, the bottom of the first groove 101 includes: a protrusion 1011 and a connecting portion 1102 connected to the protrusion 1011; the orthographic projection of the connecting portion 1102 on the second surface S2 surrounds the orthographic projection of the protrusion 1011 on the second surface S2.

[0197] The orthographic projection of the first reflective layer 2 on the second surface S2 coincides with the orthographic projection of the protrusion 1011 and the connecting portion 1102 on the second surface S2.

[0198] The orthographic projection of the second reflective layer 5 onto the second surface S2 covers the orthographic projection of the connecting part 1102 onto the second surface S2.

[0199] The width L1 of the orthographic projection of the connecting portion 1102 onto the second surface S2 in the direction parallel to the second surface S2 satisfies:

[0200] L1≥R×tan(θc); R is the distance between the edge of the connecting portion 1102 away from the protrusion 1011 and the second reflective layer 5 in the direction perpendicular to the second surface S2.

[0201] The backlight unit provided in this application embodiment has a first reflective layer that also covers the area at the bottom of the first groove outside the protrusion, i.e., the connecting part. The width L1 of the connecting part in the direction parallel to the second surface satisfies: L1≥R×tan(θc). Thus, light can undergo total internal reflection in the area corresponding to the connecting part within the first groove, which can prevent light from directly emitting from the area of ​​the first groove outside the protrusion. This avoids the problem of high brightness at a large viewing angle caused by direct light and can improve the uniformity of light output brightness in different areas of the backlight unit.

[0202] In some embodiments, such as Figure 20 As shown, the surface of the connecting portion 1102 facing away from the second surface S2 is a plane parallel to the second surface S2. Alternatively, in some embodiments, such as... Figure 21 As shown, the angle between the surface of the connecting part 1102 facing away from the second surface and the second surface is greater than 0°.

[0203] In some embodiments, such as Figure 20 , Figure 21 As shown, the connecting part 1102 does not include the second light guide layer.

[0204] Alternatively, in some embodiments, such as Figure 22 As shown, the protrusion 1101 and the connecting portion 1102 on the side away from the second surface S2 include a second light guide layer 1002.

[0205] It should be noted that when the connecting part also includes a second light guide layer, the line connecting the two ends of the connecting part is parallel to the second surface, or the angle between the line connecting the two ends of the connecting part and the second surface is greater than 0°.

[0206] In some embodiments, when both the protrusion and the connecting portion on the side facing away from the second surface include a second light guide layer, the second portion of the protrusion and the connecting portion on the side facing away from the second surface may both include a second light guide layer. This prevents light from directly escaping from the area of ​​the first groove outside the protrusion, while also allowing the light from the waveguide to be extracted from the area corresponding to the second portion, i.e., the reflector platform area, thereby improving the light output uniformity of the second portion and the area corresponding to the connecting portion.

[0207] Alternatively, in some embodiments, when both the protrusion and the connecting portion on the side facing away from the second surface include a second light guide layer, the first part and the second part of the protrusion, as well as the side of the connecting portion facing away from the second surface, may all include a second light guide layer. In this way, the light from the waveguide can be uniformly extracted in the areas corresponding to the connecting portion and the protrusion, improving the light output uniformity in the areas corresponding to the protrusion and the connecting portion.

[0208] In practical implementation, the density and size of the second light guide structure of the protrusion and the connecting part can be set according to the light output brightness requirements of the corresponding areas of the protrusion and the connecting part. The maximum height of the protrusion can also be adjusted to change the brightness of the backlight unit's light output side in the area corresponding to the protrusion, thereby improving the brightness uniformity of each area on the light output side of the backlight unit.

[0209] In some embodiments, the light guide layer is located on one side of the first substrate, that is, the matrix of the light guide layer is located on one side of the first substrate, and the difference between the refractive index of the light guide layer located on the first substrate and the refractive index of the first substrate is less than or equal to 0.2. This avoids the additional light guide layer affecting the light efficiency.

[0210] That is, when the light guide layer includes a first light guide layer, and the first substrate of the first light guide layer is located on the side of the second surface away from the first surface, the difference between the refractive index of the first substrate of the first light guide layer and the refractive index of the first substrate is less than or equal to 0.2. Alternatively, when the light guide layer includes a third light guide layer, and the third substrate of the third light guide layer is located on the side of the first surface away from the second surface, the difference between the refractive index of the third substrate of the third light guide layer and the refractive index of the first substrate is less than or equal to 0.2.

[0211] In some embodiments, the material of the first substrate includes at least one of the following: glass, polymethyl methacrylate, and polycarbonate;

[0212] The material of the light guide layer (first light guide layer or third light guide layer) located on one side of the first substrate includes at least one of the following: polyvinyl chloride, polyvinyl alcohol, polylactic acid, polymethyl methacrylate, polyvinylpyrrolidone, polyethylene terephthalate, and polycarbonate.

[0213] In some embodiments, the light guide layer (first light guide layer or third light guide layer) located on one side of the first substrate is bonded to the first substrate, and the distance between the edge of the light guide layer located on the first substrate and the edge of the second surface is less than 0.03 mm. This ensures accurate positioning of the light guide layer modulation and improves the light emission uniformity of the backlight unit.

[0214] This application provides a method for fabricating a backlight unit, such as... Figure 23 As shown, it includes:

[0215] S101, providing a first substrate; and forming a first groove on a first surface of the first substrate; the first substrate further includes a second surface opposite to the first surface;

[0216] S102, Form a first reflective layer covering at least a portion of the bottom of the first groove;

[0217] S103. A light-emitting unit is provided on the side of the first reflective layer that is away from the second surface;

[0218] It also includes: S104, forming a light guide layer; the light guide layer includes a first light guide layer and / or a second light guide layer; the first light guide layer is located on the second surface or on the side of the second surface away from the first surface, and the orthographic projection of the first light guide layer on the first substrate overlaps with the first groove; the second light guide layer is located at the bottom of the first groove, and the first reflective layer covers at least part of the second light guide layer.

[0219] The backlight unit fabrication method provided in this application embodiment forms a first light guide layer and / or a second light guide layer. The first light guide layer is located on a second surface or on the side of the second surface facing away from the first surface, i.e., the first light guide layer is disposed on the light-emitting side of the backlight unit. Furthermore, the area where the first light guide layer is disposed overlaps with the area where the first groove is disposed, meaning that the area corresponding to the first groove can also be modulated by the first light guide layer, improving the light emission uniformity of the area corresponding to the first groove, thereby improving the light emission uniformity of different areas of the backlight unit. The second light guide layer is located at the bottom of the first groove, so that at least a portion of the area corresponding to the bottom of the first groove can also be modulated by the second light guide layer, improving the light emission uniformity of the area corresponding to the first groove, thereby improving the light emission uniformity of different areas of the backlight unit.

[0220] In some embodiments, the first groove formed on the first surface of the first substrate includes a protrusion.

[0221] Alternatively, in some embodiments, the first groove formed on the first surface of the first substrate may further include a connecting portion.

[0222] In some embodiments, the light guide layer includes a first light guide layer, and forming the light guide layer 10 includes:

[0223] Multiple first light-guiding structures are formed on the second surface;

[0224] Alternatively, a light guide layer is formed on the side of the second surface away from the first surface, and the light guide layer is patterned to form multiple first light guide structures;

[0225] Alternatively, a first light guide layer may be attached to the side of the second surface opposite to the first surface, the first light guide layer comprising a plurality of first light guide structures.

[0226] In some embodiments, such as Figure 24As shown, in step S201, a first groove 101 is first formed on the first surface S1 of the first substrate 1; the first groove 101 includes a protrusion 1011.

[0227] S202, Form a first reflective layer 2 covering the protrusion 1011;

[0228] S203, then the first light guide layer 1001 is formed; Figure 24 Multiple first light-guiding structures 1001 are formed on the second surface S2.

[0229] Alternatively, in some embodiments, the first light guide layer may be formed first, followed by the formation of the first groove and the first reflective layer.

[0230] In some embodiments, before or after forming the first light guide layer, the method further includes:

[0231] The first groove is filled with a light-transmitting filling portion;

[0232] A pattern of a second reflective layer is formed on the side of the first surface opposite to the second surface; the second reflective layer includes a first opening, the orthographic projection of the first opening on the second surface overlaps with the orthographic projection of the protrusion on the second surface, and the orthographic projection of the second reflective layer on the second surface overlaps with the first groove and the orthographic projection of the first reflective layer on the second surface.

[0233] Forming a color conversion structure;

[0234] Forming a flattened encapsulation layer.

[0235] In some embodiments, forming a color conversion structure includes forming a pattern of a color conversion structure covering at least a portion of the second reflective layer and the first opening.

[0236] Alternatively, in some embodiments, after forming the pattern of the first opening, the step of forming a second opening in the light-transmitting filling portion is further included; then, a color conversion structure is formed in the first opening and the second opening.

[0237] In some embodiments, after forming the color conversion structure and before forming the encapsulation planarization layer, the method further includes:

[0238] The pattern forms an isolation dam; the isolation dam surrounds a color-changing structure.

[0239] Alternatively, in some embodiments, before or after forming the first light guide layer, the method further includes:

[0240] A pattern of a second reflective layer is formed on the side of the first surface opposite to the second surface; the second reflective layer includes a first opening, the orthographic projection of the first opening on the second surface overlaps with the orthographic projection of the protrusion on the second surface, and the orthographic projection of the second reflective layer on the second surface overlaps with the first groove and the orthographic projection of the first reflective layer on the second surface.

[0241] The first groove and the first opening are filled with a light-transmitting filling portion;

[0242] A color conversion structure is formed; the color conversion structure covers at least a portion of the second reflective layer and the light-transmitting filling portion within the first opening;

[0243] Forming a flattened encapsulation layer.

[0244] In some embodiments, after forming the color conversion structure and before forming the encapsulation planarization layer, the method further includes:

[0245] The pattern forms an isolation dam; the isolation dam surrounds a color-changing structure.

[0246] In some embodiments, the light guide layer includes a second light guide layer, and forming the light guide layer includes:

[0247] While forming the first groove, multiple second light guide structures are formed on the bottom surface of the first groove.

[0248] In some embodiments, before or after forming the second light guide layer, the method further includes:

[0249] A pattern of a second reflective layer is formed on the side of the first surface opposite to the second surface; the second reflective layer includes a first opening, the orthographic projection of the first opening on the second surface overlaps with the orthographic projection of the second light guide layer on the second surface, and the orthographic projection of the second reflective layer on the second surface overlaps with the orthographic projection of the first groove on the second surface.

[0250] It should be noted that if the second reflective layer comprises multiple layers, before forming the second light guide layer, a pattern of at least one layer of the second reflective layer is formed on the side of the first surface opposite to the second surface.

[0251] In some embodiments, before forming the pattern of the second reflective layer on the side of the first surface opposite to the second surface, the method further includes:

[0252] A third light guide layer is formed on the first surface; the orthographic projection of the third light guide layer on the second surface surrounds the orthographic projection of the first groove on the second surface.

[0253] Next, we will take the first sub-layer of the second reflective layer, which is formed before the second light guide layer, as an example for illustration. Figure 25 As shown, the backlight unit fabrication method includes:

[0254] S301, A third light guide layer 1003 is formed on the first surface S1.

[0255] S302, A pattern of a first sub-reflective layer 5-1 is formed on the side of the first surface S1 opposite to the second surface S2; the first sub-reflective layer 5-1 has a first sub-via 5011;

[0256] S303, Forming the first groove 101 and simultaneously forming the second light guide layer 1002;

[0257] S304, Form the first reflective layer 2;

[0258] S305, a pattern of a second sub-reflective layer 5-2 is formed on the side of the first sub-reflective layer 5-1 opposite to the second surface S2.

[0259] In some embodiments, the method further includes the following steps prior to forming the second sub-reflective layer:

[0260] The first groove is filled with a light-transmitting filling portion;

[0261] After the formation of the second sub-reflective layer, the following is also included:

[0262] Forming a color conversion structure;

[0263] Forming a flattened encapsulation layer.

[0264] In some embodiments, forming a color conversion structure includes forming a pattern of a color conversion structure covering at least a portion of the second reflective layer and the first opening.

[0265] Alternatively, in some embodiments, after forming the pattern of the first opening, the step of forming a second opening in the light-transmitting filling portion is further included; then, a color conversion structure is formed in the first opening and the second opening.

[0266] Alternatively, in some embodiments, after forming the second sub-reflective layer, the method further includes:

[0267] The first groove and the first opening are filled with a light-transmitting filling portion;

[0268] Forming a color conversion structure;

[0269] Forming a flattened encapsulation layer.

[0270] In some embodiments, after forming the color conversion structure and before forming the encapsulation planarization layer, the method further includes:

[0271] The pattern forms an isolation dam; the isolation dam surrounds a color-changing structure.

[0272] In some embodiments, after forming the color conversion structure and before forming the encapsulation planarization layer, the method further includes:

[0273] The pattern forms an isolation dam; the isolation dam surrounds a color-changing structure.

[0274] Next, we will take the formation of the second reflective layer after the formation of the second light guide layer as an example for illustration. Figure 26 As shown, the backlight unit fabrication method includes:

[0275] S401, a pattern of a shielding layer 25 is formed on the side of the first surface S1 opposite to the second surface S2; the shielding layer 25 includes an opening area 2501;

[0276] S402, the first groove 101 is formed and the second light guide layer 1002 is formed simultaneously; the orthographic projection of the opening area 2501 on the second surface S2 falls into the orthographic projection of the first groove 101 on the second surface S2;

[0277] S403, Form the first reflective layer 2;

[0278] S404. A light-transmitting filling portion 6 is formed in the first groove 101 and the opening area 2501;

[0279] S405, peel off the shielding layer 25;

[0280] S406, A third substrate 26 is formed, and the third substrate 26 is patterned to form a third light guide layer 1003 including a plurality of third light guide structures 23 and a cover portion 27; the orthographic projection of the cover portion 27 on the second surface S2 covers the orthographic projection of the first groove 101 on the second surface S2.

[0281] S407. A second reflective layer 5 is formed on the side of the third light guide layer 1003 away from the second surface S2.

[0282] In some embodiments, after the second reflective layer, the following is further included:

[0283] Forming a color conversion structure;

[0284] Forming a flattened encapsulation layer.

[0285] In some embodiments, forming a color conversion structure includes forming a pattern of a color conversion structure covering at least a portion of the second reflective layer and the first opening.

[0286] Alternatively, in some embodiments, after forming the pattern of the first opening, the step of forming a second opening in the light-transmitting filling portion is further included; then, a color conversion structure is formed in the first opening and the second opening.

[0287] In some embodiments, after forming the color conversion structure and before forming the encapsulation planarization layer, the method further includes:

[0288] The pattern forms an isolation dam; the isolation dam surrounds a color-changing structure.

[0289] The present application provides a light-emitting substrate, characterized in that the light-emitting substrate includes a plurality of backlight units provided in the present application.

[0290] In some embodiments, the first substrates of multiple backlight units are integrally connected; or, the multiple backlight units are independent components, and the first substrates of each backlight unit are spliced ​​together to form a backlight substrate as a whole.

[0291] This application provides a display device, such as... Figure 27 As shown, it includes a display panel 17 and a light-emitting substrate 16 provided in this embodiment of the application;

[0292] The display panel is located on the side of the second surface S2 away from the light-emitting unit 3.

[0293] In some embodiments, such as Figure 27 As shown, display panel 17 is a liquid crystal display panel; light-emitting substrate 16 is the backlight panel of display panel 17;

[0294] The liquid crystal display panel 17 is located on the side of the first substrate 1 of the light-emitting substrate that is away from the light-emitting unit 3.

[0295] The display module provided in this application embodiment has the same or similar technical effects as the light-emitting substrate provided in any of the foregoing embodiments when it is specifically implemented, and will not be described in detail here.

[0296] In some embodiments, such as Figure 27 As shown, the display panel 17 includes an array substrate 1701 and a counter substrate 1702 disposed opposite to each other, and a liquid crystal layer 1703 located between the array substrate 1701 and the counter substrate 1702.

[0297] In some embodiments, the first substrate can be reused as the substrate of the array substrate, that is, the film structure of the array substrate can be directly fabricated on the surface of the first substrate, thereby facilitating a further reduction in the thickness of the display device. Alternatively, in some embodiments, the first substrate can also be reused as the substrate of the opposing substrate, that is, the film structure of the opposing substrate can be directly fabricated on the surface of the first substrate, without limitation.

[0298] The display device provided in this application embodiment includes any product or component with display function, such as a mobile phone, tablet computer, television, monitor, laptop computer, digital photo frame, and navigator. Other essential components of this display device are understood by those skilled in the art and will not be described in detail here, nor should they be construed as limiting this application. Implementation of this display device can refer to the embodiments of the light-emitting substrate and backlight unit described above; repeated details will not be repeated.

[0299] In summary, the backlight unit, its fabrication method, light-emitting substrate, and display device provided in this application include a first light guide layer and / or a second light guide layer. The first light guide layer is located on the second surface or on the side of the second surface away from the first surface, i.e., the first light guide layer is disposed on the light-emitting side of the backlight unit. Furthermore, the area where the first light guide layer is disposed overlaps with the area where the first groove is disposed, meaning that the area corresponding to the first groove can also be modulated by the first light guide layer, improving the light emission uniformity of the area corresponding to the first groove, thereby improving the light emission uniformity of different areas of the backlight unit. The second light guide layer is located at the bottom of the first groove, so that at least a portion of the area corresponding to the bottom of the first groove can also be modulated by the second light guide layer, improving the light emission uniformity of the area corresponding to the first groove, thereby improving the light emission uniformity of different areas of the backlight unit.

[0300] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0301] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A backlight unit, characterized in that, The backlight unit includes: a first substrate, a first reflective layer, a light-emitting unit, and a light guide layer; The first substrate includes: opposing first and second surfaces, and a first groove located on the first surface; The first reflective layer covers at least a portion of the bottom area of ​​the first groove; The light-emitting unit is located on the side of the first groove that faces away from the second surface; The light guide layer includes a first light guide layer and / or a second light guide layer; the first light guide layer is located on the second surface or on the side of the second surface opposite to the first surface, and the orthographic projection of the first light guide layer on the first substrate overlaps with the first groove; the second light guide layer is located at the bottom of the first groove, and the first reflective layer covers at least a portion of the second light guide layer.

2. The backlight unit according to claim 1, characterized in that, The light guide layer includes the first light guide layer, and the first surface outside the first groove is a plane.

3. The backlight unit according to claim 1, characterized in that, The bottom of the first groove includes a protrusion that protrudes toward one side of the first surface; the first reflective layer covers the protrusion. The protrusion includes a first portion and a second portion; the orthographic projection of the second portion onto the second surface surrounds the orthographic projection of the first portion onto the second surface; The protrusion includes a third surface on the side opposite to the second surface; At least a portion of the third surface is located on the first arc surface; the first arc surface includes: a first sub-arc surface corresponding to the first portion and a second sub-arc surface corresponding to the second portion; The angle between the tangent of the first sub-arc surface and the second surface is greater than the angle between the tangent of the second sub-arc surface and the second surface; The orthographic projection of the first light guide layer on the second surface overlaps with the orthographic projection of the area at the bottom of the first groove outside the first portion and the protrusion on the second surface, and the orthographic projection of the first light guide layer on the second surface does not overlap with the orthographic projection of the second portion on the second surface.

4. The backlight unit according to claim 3, characterized in that, The third surface is the first arc surface; the fourth surface is the second arc surface.

5. The backlight unit according to any one of claims 3 to 4, characterized in that, The first light guide layer includes: a plurality of first light guide structures, wherein the first light guide structure is a protrusion structure or a groove structure; The orthographic projection of the first light guide layer onto the second surface includes: a first region, a second region surrounding the first region, and a third region surrounding the second region; The first region coincides with the orthographic projection of the second portion onto the second surface, and the second region covers the orthographic projection of the first groove outside the protrusion onto the second surface; The first region, the second region, and the third region are not completely identical in one of the following: the density of the first light guide structure, the scattering angle or reflection angle of the first light guide structure, and the aspect ratio D / H of the first light guide structure; wherein, D is the maximum width of the first light guide structure in the direction parallel to the second surface, and H is the maximum thickness of the first light guide structure in the direction perpendicular to the second surface.

6. The backlight unit according to any one of claims 1 to 4, characterized in that, The light guide layer includes the second light guide layer, and the bottom of the first groove includes a protrusion, and at least the side of the protrusion facing away from the second surface includes the second light guide layer.

7. The backlight unit according to claim 6, characterized in that, The light guide layer further includes: a third light guide layer; the third light guide layer is located on the first surface or on the side of the first surface away from the second surface; The orthographic projection of the third light guide layer on the second surface surrounds the orthographic projection of the first groove on the second surface.

8. The backlight unit according to any one of claims 1 to 4, 7, characterized in that, The bottom of the first groove includes: a protrusion and a connecting portion connected to the protrusion; the orthographic projection of the connecting portion on the second surface surrounds the orthographic projection of the protrusion on the second surface; The orthographic projection of the first reflective layer onto the second surface coincides with the orthographic projections of the protrusion and the connecting portion onto the second surface; The backlight unit further includes: a second reflective layer located on the side of the first surface away from the second surface; the second reflective layer includes a first opening, the orthographic projection of the first opening on the second surface overlaps with the orthographic projection of the protrusion on the second surface, and the orthographic projection of the second reflective layer on the second surface covers the orthographic projection of the connecting portion on the second surface; The width L1 of the orthographic projection of the connecting portion onto the second surface in the direction parallel to the second surface satisfies: L1≥R×tan(θc); R is the distance between the edge of the connecting portion away from the protrusion and the second reflective layer in the direction perpendicular to the second surface.

9. The backlight unit according to claim 8, characterized in that, The surface of the connecting part away from the second surface is a plane parallel to the second surface, or the angle between the surface of the connecting part away from the second surface and the second surface is greater than 0°.

10. The backlight unit according to claim 8, characterized in that, The protrusion and the side of the connecting portion opposite to the second surface include the second light guide layer.

11. The backlight unit according to any one of claims 1 to 4, 7, 9, and 10, characterized in that, The light guide layer is located on one side of the first substrate, and the difference between the refractive index of the light guide layer located on one side of the first substrate and the refractive index of the first substrate is less than or equal to 0.

2.

12. The backlight unit according to claim 11, characterized in that, The material of the first substrate includes at least one of the following: glass, polymethyl methacrylate, and polycarbonate; The material of the light guide layer located on one side of the first substrate includes at least one of the following: polyvinyl chloride, polyvinyl alcohol, polylactic acid, polymethyl methacrylate, polyvinylpyrrolidone, polyethylene terephthalate, and polycarbonate.

13. The backlight unit according to any one of claims 1 to 4, 7, 9, 10, and 12, characterized in that, The light guide layer located on one side of the first substrate is bonded to the first substrate, and the distance between the edge of the light guide layer located on one side of the first substrate and the edge of the second surface is less than 0.03 mm.

14. A method for fabricating a backlight unit, characterized in that, The method includes: A first substrate is provided; and a first groove is formed on a first surface of the first substrate; the first substrate further includes: a second surface opposite to the first surface; A first reflective layer is formed covering at least a portion of the bottom of the first groove; A light-emitting unit is disposed on the side of the first reflective layer that is away from the second surface; The method further includes: forming a light guide layer; the light guide layer includes a first light guide layer and / or a second light guide layer; the first light guide layer is located on the second surface or on the side of the second surface opposite to the first surface, and the orthographic projection of the first light guide layer on the first substrate overlaps with the first groove; the second light guide layer is located at the bottom of the first groove, and the first reflective layer covers at least a portion of the second light guide layer.

15. The method according to claim 14, characterized in that, The light guide layer includes the first light guide layer, and forming the light guide layer includes: Multiple first light-guiding structures are formed on the second surface; Alternatively, a light guide layer is formed on the side of the second surface opposite to the first surface, and the light guide layer is patterned to form multiple first light guide structures; Alternatively, the first light guide layer may be attached to the side of the second surface opposite to the first surface, and the first light guide layer may include a plurality of first light guide structures.

16. The method according to claim 14 or 15, characterized in that, The light guide layer includes the second light guide layer, and forming the light guide layer includes: While forming the first groove, a plurality of second light guide structures are formed on the bottom surface of the first groove.

17. The method according to claim 16, characterized in that, Before or after forming the second light guide layer, the method further includes: A pattern of a second reflective layer is formed on the side of the first surface opposite to the second surface; the second reflective layer includes a first opening, the orthographic projection of the first opening on the second surface overlaps with the orthographic projection of the second light guide layer on the second surface, and the orthographic projection of the second reflective layer on the second surface overlaps with the orthographic projection of the first groove on the second surface.

18. The method according to claim 17, characterized in that, Before forming the pattern of the second reflective layer on the side of the first surface opposite to the second surface, the method further includes: A third light guide layer is formed on the first surface or on the side of the first surface opposite to the second surface; the orthographic projection of the third light guide layer on the second surface surrounds the orthographic projection of the first groove on the second surface.

19. A light-emitting substrate, characterized in that, The light-emitting substrate includes a plurality of backlight units according to any one of claims 1 to 13.

20. A display device, characterized in that, Includes a display panel and a light-emitting substrate according to claim 19; The display panel is located on the side of the second surface opposite to the light-emitting unit.

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