Patent Publication Number: US-10761259-B2

Title: Light guide assembly, light collimation assembly, backlight module and display device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority of Chinese Patent Application No. 201811257793.X filed on Oct. 26, 2018, the disclosure of which is incorporated herein by reference in its entirety as part of the present application. 
     TECHNICAL FIELD 
     Embodiments of the present disclosure relate to a light guide assembly, a light collimation assembly, a backlight module and a display device. 
     BACKGROUND 
     A Light Guide Plate (LGP) is a functional element capable of changing a point light source or a line light source into a surface light source, and generally, some light guide structures are utilized to improve utilization efficiency of light. The LGP, for example, may be applied in fields of lighting, display and the like. 
     A light collimation element can change divergent light into collimated light. Generally speaking, light emerging from a light source is divergent, and thus, the divergent light may be collimated towards a certain direction by utilizing the light collimation element to change the divergent light into the collimated light propagated in parallel along a specific direction, so that utilization efficiency of the light can be improved. 
     SUMMARY 
     At least one embodiment of the present disclosure provides a light guide assembly, the light guide assembly comprises: a first prism sheet, a dielectric layer and a second prism sheet which are sequentially laminated along a first direction, a light refractive index of the dielectric layer is smaller than a light refractive index of the first prism sheet and a light refractive index of the second prism sheet; the first prism sheet includes a light incident side surface, and a first plane and a first prism surface which are opposite to each other, the first plane is closer to the dielectric layer with respect to the first prism surface, and the first prism surface includes a plurality of first prism portions extending along a second direction; the second prism sheet includes a second plane and a second prism surface which are opposite to each other, the second plane is closer to the dielectric layer with respect to the second prism surface, the second prism surface includes a plurality of second prism portions extending along the second direction, and the second prism portion has a reflection surface; the first prism sheet is configured to receive light being incident to the light incident side surface, totally reflect light with an included angle not smaller than a first angle with a surface of the dielectric layer by the first prism portion, and reduce an included angle between the light being totally reflected and the first direction; and the second prism sheet is configured to enable light incident to the second prism portion through the second plane to be reflected towards the first direction by the reflection surface of the second prism portion and emerge from the first prism surface, the second direction is parallel to the light incident side surface, and the first angle is a total reflection critical angle between the first prism sheet and the dielectric layer. 
     For example, in the light guide assembly provided by at least one embodiment of the present disclosure, the first prism portion includes a first prism portion surface positioned on a side of the first prism sheet, which is away from the dielectric layer, a first included angle between a tangent plane at each point in the first prism portion surface and the first plane is γ1, where 0°&lt;γ1≤10°, and a vertex of the first included angle is away from the light incident side surface. 
     For example, in the light guide assembly provided by at least one embodiment of the present disclosure, the first prism portion surface is an inclined plane or a curved surface; or the first prism portion plane includes a plurality of inclined plane portions, and two adjacent inclined plane portions in the plurality of inclined plane portions have different first included angle. 
     For example, in the light guide assembly provided by at least one embodiment of the present disclosure, the first prism portion further includes a second prism portion surface intersecting with the first prism portion surface, a second included angle between a tangent plane at each point in the second prism portion surface and the first plane is γ2, where 15°&lt;γ2≤90°, and a vertex of the second included angle is close to the light incident side surface. 
     For example, in the light guide assembly provided by at least one embodiment of the present disclosure, the first prism surface further includes a plurality of first plane portions, each of the plurality of first plane portions is positioned between the adjacent first prism portions. 
     For example, in the light guide assembly provided by at least one embodiment of the present disclosure, the first prism portion is of a block shape, and an arrangement density of the first prism portion is increased along a direction away from the light incident side surface. 
     For example, in the light guide assembly provided by at least one embodiment of the present disclosure, the first prism portion is of a strip shape, at least two first prism portions are different in width in a third direction, and/or, at least two first plane portions are different in width in the third direction, wherein the third direction is perpendicular to the second direction. 
     For example, in the light guide assembly provided by at least one embodiment of the present disclosure, a main cross-section of the first prism portion along the first direction is of a triangle shape. 
     For example, in the light guide assembly provided by at least one embodiment of the present disclosure, the first prism portion surface is a first sub prism surface, the first prism portion further includes a second sub prism surface, the second sub prism surface intersects with the first sub prism surface, and an included angle α 2  between a plane where the second sub prism surface is positioned and the first plane is 15°≤α 2 ≤90°. 
     For example, in the light guide assembly provided by at least one embodiment of the present disclosure, in a direction which is parallel to the third direction and is away from the light incident side surface, a width of the first prism portion is set to be gradually increased, and/or a width of the first plane portion is gradually decreased. 
     For example, in the light guide assembly provided by at least one embodiment of the present disclosure, the plurality of second prism portions are continuously disposed on the second prism surface. 
     For example, in the light guide assembly provided by at least one embodiment of the present disclosure, a main cross-section of the second prism portion is of a triangle shape. 
     For example, in the light guide assembly provided by at least one embodiment of the present disclosure, the second prism portion includes a third sub prism surface, the third sub prism surface is configured as the reflection surface, a vertex of an included angle α 3  between a plane where the third sub prism surface is positioned and the second plane is away from the light incident side surface, and the included angle α 3  is calculated by a formula below: 
               α   ⁢           ⁢   3     =       1   2     ⁢     arcsin   ⁡     [                 ⁢     n   ⁢           ⁢   1         n   ⁢           ⁢   3       ×     sin   ⁡     (       arcsin   ⁡     (       n   ⁢           ⁢   2       n   ⁢           ⁢   1       )       -     α   ⁢           ⁢   1       )         ]               
where n1 represents a refractive index of the first prism sheet, n2 represents a refractive index of the dielectric layer, and n3 represents a refractive index of the second prism sheet.
 
     For example, in the light guide assembly provided by at least one embodiment of the present disclosure, the second prism portion further includes a fourth sub prism surface, the fourth sub prism surface intersects with the third sub prism surface, and an included angle α 4  between a plane where the fourth sub prism surface is positioned and the second plane is 30°≤α 4 ≤90°. 
     For example, in the light guide assembly provided by at least one embodiment of the present disclosure, a material of the dielectric layer includes an optical clear adhesive, and a refractive index the first prism sheet and a refractive index the second prism sheet are identical. 
     At least one embodiment of the present disclosure provides a light collimation assembly, the light collimation assembly comprises: the light guide assembly as mentioned above, and a collimation part, laminated with the light guide assembly along the first direction and arranged on a side of the light guide assembly where the first prism sheet is arranged, the collimation part is configured to receive light emerging from the first prism sheet of the light guide assembly, collimate a portion of the light, which is propagated along the second direction, towards the first direction and enable the collimated light to emerge. 
     For example, in the light collimation assembly provided by at least one embodiment of the present disclosure, the collimation part includes a grating layer, the grating layer includes a grating strip extending the third direction, and the grating layer is arranged on a side of the collimation part, which is close to the light guide assembly, or a side of the collimation part, which is away from the light guide assembly, wherein the third direction is perpendicular to the second direction. 
     For example, in the light collimation assembly provided by at least one embodiment of the present disclosure, a cross section of the grating strip along the second direction is of a trapezoid shape, and a side surface of the grating strip has a reflection layer; or, a cross section of the grating strip along the second direction is of a rectangle shape, and a material of the grating strip is a light absorption material. 
     For example, in the light collimation assembly provided by at least one embodiment of the present disclosure, 
     At least one embodiment of the present disclosure provides a backlight module, the backlight module comprises: the light guide assembly as mentioned above or the light collimation assembly as mentioned above; and a light source, which is arranged on a side of the first prism sheet where the light incident side surface is positioned. 
     At least one embodiment of the present disclosure provides a display device, the display device comprises the backlight module as mentioned above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to clearly illustrate the technical solution of the embodiments of the invention, the drawings of the embodiments will be briefly described in the following; it is obvious that the described drawings are only related to some embodiments of the invention and thus are not limitative of the invention. 
         FIG. 1  is a planar schematic diagram of a light guide assembly provided by an embodiment of the present disclosure; 
         FIG. 2  is a cross-sectional schematic diagram of the light guide assembly in  FIG. 1  along an A-A line; 
         FIG. 3  is a schematic diagram of carrying out light collimation by a light guide assembly provided by an embodiment of the present disclosure; 
         FIGS. 4A to 4C  are schematic diagrams of arrangement of a first prism portion and a first plane portion in a light guide assembly provided by an embodiment of the present disclosure; 
         FIG. 5A  is a schematic diagram of arrangement of a first prism portion in a light guide assembly provided by an embodiment of the present disclosure; 
         FIG. 5B  is a schematic diagram of a first prism portion in a light guide assembly provided by an embodiment of the present disclosure; 
         FIG. 6  is a planar schematic diagram of a light collimation assembly provided by an embodiment of the present disclosure; 
         FIG. 7A  is a cross-sectional schematic diagram of the light collimation assembly in  FIG. 6  along an A-A line; 
         FIG. 7B  is a cross-sectional schematic diagram of the light collimation assembly in  FIG. 6  along a B-B line; 
         FIG. 8A  and  FIG. 8B  are schematic diagrams of two types of grating strips provided by an embodiment of the present disclosure. 
         FIG. 9A  and  FIG. 9B  are test charts of light collimation effects of two types of light collimation assembly provided by an embodiment of the present disclosure; 
         FIG. 10  is a schematic diagram of a backlight module provided by an embodiment of the present disclosure; and 
         FIG. 11  is a schematic diagram of a display device provided by an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In order to make objects, technical details and advantages of the embodiments of the invention apparent, the technical solutions of the embodiment will be described in a clearly and fully understandable way in connection with the drawings related to the embodiments of the invention. It is obvious that the described embodiments are just a part but not all of the embodiments of the invention. Based on the described embodiments herein, those skilled in the art can obtain other embodiment(s), without any inventive work, which should be within the scope of the invention. 
     Unless otherwise defined, all the technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. The terms, such as “first,” “second,” or the like, which are used in the description and the claims of the present disclosure, are not intended to indicate any sequence, amount or importance, but for distinguishing various components. The terms, such as “comprise/comprising,” “include/including,” or the like are intended to specify that the elements or the objects stated before these terms encompass the elements or the objects and equivalents thereof listed after these terms, but not preclude other elements or objects. The terms, such as “connect/connecting/connected,” “couple/coupling/coupled” or the like, are not limited to a physical connection or mechanical connection, but may include an electrical connection/coupling, directly or indirectly. The terms, “on,” “under,” or the like are only used to indicate relative position relationship, and when the position of the object which is described is changed, the relative position relationship may be changed accordingly. 
     In application that an LGP changes a point light source or a line light source into a surface light source, due to reasons of limitation to an LGP structure and the like, brightness of light emerging from the LGP is limited and is not uniform enough. In addition, light emerging from a light emergent surface of the LGP is also divergent generally, and thus, a utilization rate of the light is also relatively low. By utilizing a light collimation element, the light can be collimated towards a certain direction to change a propagation direction of the light and meanwhile, the utilization rate of the light can be improved, but the existing light collimation element only may collimate incident light in one direction, and thus, the collimation effect is limited. 
     At least one embodiment of the present disclosure provides a light guide assembly. The light guide assembly includes: a first prism sheet, a dielectric layer and a second prism sheet which are sequentially laminated along a first direction, wherein a light refractive index of the dielectric layer is smaller than that of the first prism sheet and that of the second prism sheet; the first prism sheet includes a light incident side surface and a first plane and a first prism surface which are opposite to each other, the first plane is closer to the dielectric layer with respect to the first prism surface, and the first prism surface includes a plurality of first prism portions extending along a second direction; the second prism sheet includes a second plane and a second prism surface which are opposite to each other, the second plane is closer to the dielectric layer with respect to the second prism surface, the second prism surface includes a plurality of second prism portions extending along the second direction, and the second prism portion has a reflection surface; the first prism sheet is configured to receive light incident by the light incident side surface and by the first prism portion, totally reflect light with an included angle not smaller than a first angle with the surface of the dielectric layer and reduce an included angle between the light and the first direction; and the second prism sheet is configured to enable light incident to the second prism portion through the second plane to be reflected towards the first direction by the reflection surface of the second prism portion and emerge from the first prism surface, wherein the second direction is parallel to the light incident side surface, and the first angle is a total reflection critical angle between the first prism sheet and the dielectric layer. 
     At least one embodiment of the present disclosure provides a light collimation assembly, including the above-mentioned light guide assembly and further including a collimation part. The collimation part is laminated with the light guide assembly along the first direction and is arranged on a side of the light guide assembly where the first prism sheet is arranged, wherein the collimation part is configured to receive light emerging from the first prism sheet of the light guide assembly, collimate a portion of the light, which is propagated along the second direction, towards the first direction and enable the collimated light to emerge. 
     At least one embodiment of the present disclosure provides a backlight module, including the above-mentioned light guide assembly or the above-mentioned light collimation assembly, and further including a light source which is arranged on a side of the first prism sheet, where the light incident side surface is positioned. 
     At least one embodiment of the present disclosure provides a display device, including the above-mentioned backlight module. 
     The light guide assembly, the light collimation assembly, the backlight module and the display device which are provided by the present disclosure will be illustrated by several specific embodiments. 
     At least one embodiment of the present disclosure provides a light guide assembly,  FIG. 1  is a planar schematic diagram of the light guide assembly provided by this embodiment, and  FIG. 2  is a cross-sectional schematic diagram of the light guide assembly in  FIG. 1  along an A-A line. As shown in  FIG. 1  and  FIG. 2 , the light guide assembly  10  includes a first prism sheet  101 , a dielectric layer  102  and a second prism sheet  103  which are sequentially laminated along a first direction, and for example, the light guide assembly  10  includes a first prism sheet  101 , a dielectric layer  102  and a second prism sheet  103  which are sequentially attached by taking the first direction as a normal direction; and a light refractive index of the dielectric layer  102  is smaller than that of the first prism sheet  101  and that of the second prism sheet  103 . 
     The first prism sheet  101  includes a light incident side surface  1013  and a first plane  1012  and a first prism surface  1011  which are opposite to each other, the first plane  1012  is closer to the dielectric layer  102  with respect to the first prism surface  1011 , i.e., the first plane  1012  and the dielectric layer  102  are adjacently arranged, the first prism surface  1011  includes a plurality of first prism portions  1011 A extending along a second direction, the second direction is parallel to the light incident side surface. For example, the plurality of first prism portions  1011 A are arranged in parallel side by side along a third direction, and the third direction is perpendicular to the second direction. In this embodiment, an extension direction (the second direction shown in the drawings) of the first prism portion  1011 A refers to a direction perpendicular to a main cross-section of the first prism portion  1011 A. 
     For example, a light source may be arranged on the light incident side surface  1013 , so that light emitted by the light source can be incident into the first prism sheet  101  from the light incident side surface  1013 . The first prism sheet  101  may reflect the light incident to the first prism surface  1011  at a certain angle to the dielectric layer  102  due to a total reflection effect, and enable light which is reflected by the second prism sheet  103  and meets a certain angle condition to emerge. For example, a total reflection critical angle between the first prism sheet  101  and the dielectric layer  102  is a first angle, the first prism sheet  101  may receive light incident by the light incident side surface  1013  and may totally reflect, by the first prism portion  1011 A, light with an included angle not smaller than the first angle with the surface of the dielectric layer  102  and reduce an included angle between the totally reflected light and the first direction. (It will be illustrated in detail below) 
     The second prism sheet  103  includes a second plane  1032  and a second prism surface  1031  which are opposite to each other, the second plane  1032  is closer to the dielectric layer  102  with respect to the second prism surface  1031 , i.e., the second plane  1032  and the dielectric layer  102  are adjacently arranged, the second prism surface  1031  includes a plurality of second prism portions  1031 A extending along the second direction, and the second prism portion  1031 A has a reflection surface; for example, the plurality of second prism portions  1031 A are arranged in parallel side by side along the third direction. For example, the second prism sheet  103  is configured to enable light which is irradiated to the surface of the dielectric layer  102  at a second angle smaller than the first angle and incident to the second prism portion  1031 A through the dielectric layer  102  to be reflected towards the first direction by the reflection surface of the second prism portion  1031 A and emerge from the first prism surface  1011 , so that the light emerging from the light guide assembly  10  is basically propagated along the first direction; for example, an included angle between an emergent direction of the light and the first direction is within a range of 0° to 10°, and further for example, within a range of 0° to 5°. 
     For example, the first prism portion includes a first prism portion surface positioned on a side of the first prism sheet, which is away from the dielectric layer, e.g., a first sub prism surface  1011 A 1  in  FIG. 3 , a first included angle between a tangent plane at each point in the first prism portion surface and the first plane is γ1, where 0°&lt;γ1≤10°, and a vertex of the first included angle is away from the light incident side surface, i.e., two edges of the first included angle are close to the light incident side surface, but the vertex of the first included angle is close to a side opposite to the light incident side surface with respect to the two edges. 
     For example, the first prism portion surface may be an inclined plane or a curved surface; or the first prism portion surface includes a plurality of sections of inclined plane portions, and two adjacent sections in the plurality of sections of inclined plane portions have different first included angles. 
     For example, the first included angle at each point in the curved surface meets the conditions above, the inclined plane has a consistent first included angle, and a tangent plane at each point in the inclined plane is just the inclined plane; or the first included angle of each section of the inclined plane meets the conditions above. 
     In this way, the first prism portion meeting the conditions above can enable the light totally reflected on the first plane to be still totally reflected after being incident to the first prism portion surface of the first prism portion, and can reduce the included angle between the totally reflected light and the first direction. 
     For example, the first prism portion further includes a second prism portion surface intersecting with the first prism portion surface, e.g., a first sub prism surface  1011 A 2  in  FIG. 3 , a second included angle between a tangent plane at each point in the second prism portion surface and the first plane is γ2, where 15°&lt;γ2≤90°, and a vertex of the second included angle is close to the light incident side surface. 
     It should be noted that in this embodiment, by taking the total reflection critical angle between the first prism sheet  101  and the dielectric layer  102  as the first angle, i.e., as a reference value, the second angle is selected, and structural parameters of the second prism portion  1031 A are configured on the basis of the second angle. For example, a range of a difference value Δ between the second angle smaller than the first angle and the first angle may be selected as 0&lt;Δ≤2α, and the α may be an included angle α1 between the first sub prism surface  1011 A 1  and the first plane  1012 . The second prism portion  1031 A configured by utilizing the reference value can reflect the light towards the first direction, which is irradiated to a surface of the dielectric layer  102  at the second angle smaller than the first angle and incident to the second prism portion  1031 A through the dielectric layer  102 . For example, in this embodiment, under the modulation of the first prism sheet  101 , the second angle is within a range slightly smaller than the first angle (which will be described in detail below). Therefore, the second angle can be basically equal to the total reflection critical angle, and for example, is determined within a range smaller than the total reflection critical angle by 0 to 5°. In view of the total reflection phenomenon, as long as a light incident angle is smaller than the critical angle, total reflection cannot occur; and thus, in one example, the second angle is selected to be smaller than and basically equal to the critical angle; at the moment, in order to facilitate calculation, the critical angle is selected to replace the second angle to carry out calculation, but it should be understood that in this example, the second angle is still smaller than the critical angle, or total reflection of the light will be generated. 
     For example, a main cross-section of the first prism portion  1011 A along the first direction, i.e., a cross-section cut along a surface perpendicular to the light incident side surface, may be in a shape of polygon such as a triangle, or a deformed shape of the polygon such as a triangle, for example, an angle of the triangle is formed into an inverted rounded angle and the like, the main cross-section also may be of a shape of sector, curved sector and the like, the embodiments of the present disclosure do not make any limit thereto, as long as the light with the included angle not smaller than the first angle with the surface of the dielectric layer can be totally reflected and the included angle between the light and the first direction can be reduced. 
     When the second angle is selected, the second prism portion  1031 A is configured to make the light which is irradiated to the surface of the dielectric layer  102  at the second angle and incident to the second prism portion  1031 A through the dielectric layer  102  to be reflected towards the first direction by the second prism portion  1031 A, i.e., the second angle is a reference value for designing a prism surface of the second prism portion  1031 A. Even though the incident light is incident to the second prism portion  1031 A at an incident angle slightly deviated from the second angle (for example, slightly greater than or slightly smaller than) through the dielectric layer  102 , the light reflected by the second prism portion  1031 A also may be slightly deviated from the first direction, but the second angle is only slightly smaller than the first angle, and thus, the deviation value is also relatively small, so that an effect of collimating the emergent light along the first direction is achieved. 
     For example, a main cross-section of the second prism portion  1031 A along the first direction, i.e., a section cut along a surface perpendicular to the light incident side surface, can be in a shape of polygon such as a triangle or a deformed shape of the same, for example, an angle of the triangle is formed into an inverted rounded angle and the like, and the main section also can be in a shape of sector, curved sector and the like. The embodiments of the present disclosure do not make any limit thereto, as long as the light which is incident to the second prism portion through the second plane can be reflected towards the first direction by the reflection surface of the second prism portion and emerge from the first prism surface. 
     In this embodiment, the second direction and the third direction are in a plane where the first prism sheet is positioned, correspondingly, also may be in a plane where the second prism sheet is positioned, and thus are perpendicular to the first direction. 
     For example, as shown in  FIG. 3 , the first prism portion  1011 A includes the first prism portion surface, e.g., the first sub prism surface  1011 A 1 , the included angle between the first sub prism surface  1011 A 1  and the first plane  1012  is α 1 , and for example, a range of α 1  is 0°&lt;α 1 ≤10°, e.g., 0°&lt;α 1 ≤3°, such as 1°, 2° or 3° and the like. For example, the included angle α 1  faces the light incident side surface  1013  of the first prism sheet  101 , i.e., the inside (a side facing the inside of the first prism portion  1011 A) of the first sub prism surface  1011 A 1  faces the light incident side surface  1013  of the first prism sheet  101 . Moreover, in this example, it is illustrated by taking a case that the second angle is smaller than and basically equal to the critical angle as an example. 
     For example, in this embodiment, the first prism portion  1011 A further includes a second prism portion surface, e.g., a second sub prism surface  1011 A 2 , the second sub prism surface  1011 A 2  intersects with the first sub prism surface  1011 A 1 , and for example, the inside (a side facing the inside of the second sub prism surface  1011 A 2 ) of the second sub prism surface  1011 A 2  is arranged facing away from the light incident side surface  1013  of the first prism sheet  101 . For example, an included angle between a plane where the second sub prism surface  1011 A 2  is located and the first plane  1012  is α 2 , for example, a range of α 2  is 15°≤α 2 ≤90°, e.g., 45°≤α 2 ≤90°, and for example, α 2  is 30°, 45°, 55°, 65°, 75°, 80°, 85° or 90° and the like. 
     For example, in this embodiment, the dielectric layer  102  is sandwiched between the first prism sheet  101  and the second prism sheet  102 , and may be made of an inorganic or organic transparent material. In one example, a material of the dielectric layer  102  includes an Optical Clear Adhesive (OCA) which may be used for adhering the first prism  101  and the second prism sheet  102  together. A refractive index of the OCA is smaller than that of the first prism sheet  101  and that of the second prism sheet  102 . For example, the refractive index of the OCA is about 1.2 to 1.4, e.g., 1.3 or 1.4 and the like. 
     For example, in this embodiment, the first prism sheet  101  and the second prism sheet  102  are the same in refractive index so as to facilitate angle design on the prism portions of the first prism sheet  101  and the second prism sheet  102 . For example, the first prism sheet  101  and the second prism sheet  102  are prepared from the same material, and thus have the same refractive index, and the material may be a material such as glass or resin and the like, with a refractive index of about 1.5 to 1.8, e.g., 1.6, 1.7 or 1.8 and the like. 
     For example, the second prism portion  1031 A includes a third prism portion surface, a third included angle between a tangent plane at each point in the third prism portion surface and the first plane is γ3, where 0°&lt;γ3≤10°, a vertex of the third included angle is away from the light incident side surface, and γ3 meets a formula (1): γ3=α 3 . 
     For example, in this embodiment, the second prism portion  1031 A includes the third prism portion surface, e.g., a third sub prism surface  1031 A 1 , at least the third sub prism surface  1031 A 1  is configured as a reflection surface, and for example, it can be implemented by plating a reflection layer (e.g., a metal aluminum thin layer) on the third sub prism surface  1031 A 1 . For example, an included angle between a plane where the third sub prism surface  1031 A 1  is positioned and the second plane  1032  is α3 and faces the light incident side surface  1013  of the first prism surface  101 , and at the moment, the inside (a side facing the inside of the second prism portion  1031 A) of the third sub prism surface  1031 A 1  faces the light incident side surface  1013  of the first prism sheet  101 . For example, the included angle α 3  between the plane where the third sub prism surface  1031 A 1  is positioned and the second plane  1032  may be calculated by a formula 1 below: 
     
       
         
           
             
               
                 
                   
                     α 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     3 
                   
                   = 
                   
                     
                       1 
                       2 
                     
                     ⁢ 
                     
                       arcsin 
                       ⁡ 
                       
                         [ 
                         
                           
                             
                               
                                   
                               
                               ⁢ 
                               
                                 n 
                                 ⁢ 
                                 
                                     
                                 
                                 ⁢ 
                                 1 
                               
                             
                             
                               n 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               3 
                             
                           
                           × 
                           
                             sin 
                             ⁡ 
                             
                               ( 
                               
                                 
                                   arcsin 
                                   ⁡ 
                                   
                                     ( 
                                     
                                       
                                         n 
                                         ⁢ 
                                         
                                             
                                         
                                         ⁢ 
                                         2 
                                       
                                       
                                         n 
                                         ⁢ 
                                         
                                             
                                         
                                         ⁢ 
                                         1 
                                       
                                     
                                     ) 
                                   
                                 
                                 - 
                                 
                                   α 
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   1 
                                 
                               
                               ) 
                             
                           
                         
                         ] 
                       
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     Where, n1 represents the refractive index of the first prism sheet, n2 represents the refractive index of the dielectric layer, and n3 represents the refractive index of the second prism sheet. 
     The included angle α 3  obtained by such formula can enable the light which is irradiated to the surface of the dielectric layer  102  at the second angle and incident to the second prism portion  1031 A through the dielectric layer  102  to be reflected towards the first direction by the second prism portion  1031 A, i.e., reflected vertically upward in the drawing. 
     For example, the second prism portion  1031 A includes a fourth prism portion surface, a fourth included angle between a tangent plane at each point in the fourth prism portion surface and the first plane is γ4, where 30°≤γ4≤90°, the vertex of the fourth included angle is close to the light incident side surface, γ4=α4, and γ4 meets descriptions about α 4  below. 
     For example, in this embodiment, the second prism portion  1031 A further includes the fourth sub prism surface  1031 A 2 , and the fourth sub prism surface  1031 A 2  intersects with the third sub prism surface  1031 A 1 . For example, the inside (a side facing the inside of the second prism portion  1031 A) of the fourth sub prism surface  1031 A 2  faces a side away from the light incident side surface  1013  of the first prism sheet  101 , an included angle between a plane where the fourth sub prism surface  1031 A 2  is positioned and the second plane  1032  is α 4 , for example, a range of α 4  is 30°≤α 4 ≤90°, e.g., 60°≤α 4 ≤90°, and for example, α 4  is 40°, 50°, 60°, 70°, 80°, 85° or 90° and the like. 
     For example, in one example of this embodiment, a cross-main section of the second prism portion  1031 A is in a shape of a right triangle, and a plane where a bevel edge of the right triangle is positioned is configured as the third sub prism surface  1031 A 1 . For example, the third sub prism surface  1031 A 1  is mainly used for collimating the light towards the first direction. 
     For example, in one example, α 1  is set as 2°, α 2  is set as 45°, α 3  is set as 27.5°, and α 4  is set as 70°. The setting not only can achieve a good collimation effect, but also is convenient for production of each portion of the light guide assembly. 
     For example, in this embodiment, as shown in  FIG. 2 , the surface of the second prism portion  1031 A further may have a protection layer  111  so as to prevent abrasion to the second prism portion  1031 A. For example, a material of the protection layer  111  is a resin material. 
     For example,  FIG. 3  further shows a schematic diagram of carrying out light collimation by the light guide assembly provided by this embodiment. As shown in  FIG. 3 , in this example, the refractive indexes of the first prism sheet  101  and the second prism sheet  103  are set to be the same, and the total reflection critical angle between the first prism sheet  101  and the dielectric layer  102  and the total reflection critical angle between the second prism sheet  103  and the dielectric layer  102  are θ (the first angle). The light incident side surface  1013  of the first prism sheet  101  is provided with the light source  110 , the light source  110 , for example, is a light-emitting structure such as a Light-Emitting Diode (LED) and the like, and the light-emitting structure, for example, is linearly arranged along the light incident side surface  1013 . For example, the light source  110  includes the LED and a reflection shell arranged around the LED so as to form a Lambert body light source, and may relatively uniformly emit light into the first prism sheet  101  at a preset angle (or in an angle range) through the light incident side surface  1013  of the first prism sheet  101  and enable the incident light to be totally reflected in the first prism sheet  101 , so that the light can be propagated from the light incident side surface to the other side opposite to the light incident side surface. 
     In the above-mentioned case, when a light beam (shown as arrows in the drawings) emitted by the light source  110  enters the first prism sheet  101  from the light incident side surface of the first prism sheet  101  and for example, is incident to a point A at an interface of the first prism sheet  101  and the dielectric layer  102 , if an included angle θ1 between the light and the first direction, i.e., a vertical direction in the drawings, is smaller than θ, i.e., θ1&lt;θ, the light can enter the second prism sheet  103  via the dielectric layer  102  and is reflected towards the first direction or a direction facing the first direction by the second prism sheet  103 , and the light, for example, is modulated into collimated light basically propagated along the first direction by the third sub prism surface  1031 A 1  (with reference to a collimation path of a point E). 
     In another aspect, if the included angle θ1 between the light and the first direction is greater than θ, i.e., θ1&gt;θ (the case shown in  FIG. 3 ), the light is totally reflected at the point A and returned to the first prism surface  1011  of the first prism sheet  101 , e.g., a point B on the first prism portion  1011 A, the first prism portion  1011 A of the first prism sheet  101  can reduce the included angle between the light and the first direction when reflecting the light, at the moment, after the light is totally reflected at the point B, the included angle between the light and the first direction is reduced to θ3, and θ3=θ1−2α 1 , i.e., a value by which the first prism portion  1011 A reduces the included angle between the light and the first direction is related to the included angle α 1  between the first sub prism surface  1011 A 1  facing the light incident side surface  1013  of the first prism sheet  101  and the first plane  1012 , and for example, the included angle is reduced by 2α 1  each time. When the angle θ3 is reduced to be smaller than θ, i.e., θ3&lt;θ, the light can enter the dielectric layer  102  from a point C and enter the second prism sheet  103  from a point D, and is finally modulated into the collimated light propagated along the first direction by the point E of the third sub prism surface  1031 A 1 ; and if the angle θ3 is still greater than θ after the light is reflected by the first prism sheet  101 , the light may be continuously totally reflected in the first prism sheet  101 , the included angle with the first direction is reduced again under the reflection action of the first prism portion  1011 A of the first prism sheet  101 , and finally, when θ3 is reduced to be smaller than θ, the light can enter the second prism sheet  103  and be modulated into the collimated light propagated along the first direction. 
     In another example of this embodiment, the second angle is selected to be smaller than the critical angle (i.e., the first angle) by α1, and then on the basis of a condition that the light which is irradiated to the surface of the dielectric layer at the second angle and incident to the second prism portion through the dielectric layer is reflected towards the first direction by the second prism portion, the included angle α 3  between the third sub prism surface  1031 A 1  and the second plane  1032  is calculated. In this example, the first prism sheet  101  and the second prism sheet  102  are the same in refractive index, and the second angle is smaller than the critical angle (i.e., the first angle) by α1, and thus, it may be obtained according to the formula 1 that: 
     
       
         
           
             
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                           n 
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     Still with reference to  FIG. 3 , when the light beam (shown as the arrows in the drawing) emitted by the light source  110  enters the first prism sheet  101  from the light incident side surface of the first prism sheet  101  and for example, is incident to the point A at the interface of the first prism sheet  101  and the dielectric layer  102 , if the included angle θ1 between the light and the first direction, i.e., the vertical direction in the drawing, is smaller than θ, i.e., θ1&lt;θ, the light can enter the second prism sheet  103  via the dielectric layer  102  and is reflected towards the first direction or a direction facing the first direction by the second prism sheet  103 , and the light, for example, is modulated into the collimated light basically propagated along the first direction by the third sub prism surface  1031 A 1  (with reference to the collimation path of the point E). 
     In another aspect, if the included angle θ1 between the light and the first direction is greater than θ, i.e., θ1&gt;θ (the case shown in  FIG. 3 ), the light is totally reflected at the point A and returned to the first prism surface  1011  of the first prism sheet  101 , e.g., the point B on the first prism portion  1011 A, the first prism portion  1011 A of the first prism sheet  101  can reduce the included angle between the light and the first direction when reflecting the light, at the moment, after the light is totally reflected at the point B, the included angle between the light and the first direction is reduced into θ3, and θ3=θ1−2α 1 , i.e., the value by which the first prism portion  1011 A reduces the included angle between the light and the first direction is related to the included angle α 1  between the first sub prism surface  1011 A 1  facing the light incident side surface  1013  of the first prism sheet  101  and the first plane  1012 , and for example, the included angle is reduced by 2α 1  each time. When the angle θ3 is reduced to be smaller than θ, the light can enter the dielectric layer  102  from the point C and enter the second prism sheet  103  from the point D, and is finally modulated into the collimated light propagated along the first direction by the point E of the third sub prism surface  1031 A 1 ; and if the angle θ3 is still greater than θ after the light is reflected by the first prism sheet  101 , the light may be continuously totally reflected in the first prism sheet  101 , the included angle with the first direction is reduced again under the reflection action of the first prism portion  1011 A of the first prism sheet  101 , and finally, when θ3 is reduced to be smaller than θ, the light can enter the second prism sheet  103  and be modulated into the collimated light propagated along the first direction. In this example, the second angle is selected to be smaller than the first angle (i.e., θ) by α 1 , and thus, the angle θ3 is gradually reduced by a step length of 2α 1  to be smaller than the first angle θ, the light can enter the second prism sheet  103  via the dielectric layer  102 , and the included angle between the light reflected at the point E of the third sub prism surface  1031 A 1  of the second prism portion and the first direction is smaller than α 1 , which is helpful for improving the collimation degree of the obtained collimated light. 
     For example, in this embodiment, as shown in  FIG. 2 , the first prism surface  1011  further may include a plurality of first plane portions  1011 B, and the plurality of first plane portions  1011 B are respectively positioned between the adjacent first prism portions  1011 A. In this embodiment, the plurality of first prism portions  1011 A in the first prism surface  1011  are spaced with the first plane portions  1011 B, i.e., the plurality of first prism portions  1011 A in this embodiment adopt a discontinuous arrangement mode, and the first plane portions  1011 B cannot regulate an angle of the light incident to the first prism sheet  101 , and thus, the light can be continuously totally reflected in the first prism sheet  101 , the included angle with the first direction is reduced again under the reflection action of the first prism portion  1011 A of the first prism sheet  101  until after the light is modulated by the first prism portion  1011 A, the angle between the light and the first direction is reduced to be smaller than θ, and at the moment, the light can be incident to the second prism sheet  103  and emerge after being collimated by the second prism sheet  103 . Therefore, in this embodiment, uniformity of carrying out collimation on the light can be regulated by setting widths and spacing of the first prism portions  1011 A arranged at different positions or widths and spacing of the first plane portions  1011 B and the like. 
     For example, in this embodiment, when the first prism portion  1011 A is of a strip shape, at least two first prism portions  1011 A are different in width in the third direction; or, at least two first plane portions  1011 B are different in width in the third direction; or, at least two first prism portions  1011 A are different in width in the third direction, at least two first plane portions  1011 B are also different in width in the third direction. 
     For example, the light source  110  is arranged at the position of the light incident side surface  1013  of the first prism sheet  101 , at the moment, for example, as shown in  FIG. 4A , the first prism portion  1011 A closer to the light incident side surface  1013  has a smaller width d 1 , and the widths d 2  of the first plane portions  1011 B are all the same; or, as shown in  FIG. 4B , the first plane portion  1011 B closer to the light incident side surface  1013  has a greater width d 2 , and the widths d 1  of the first prism portions  1011 A are all the same; or, as shown in  FIG. 4C , when the first prism portion  1011 A closer to the light incident side surface  1013  has a smaller width d 1 , the first plane portion  1011 B closer to the light incident side surface  1013  has a greater width d 2 . 
     In this embodiment, the light is more sufficient at a position closer to the light source  110  and the light is more sparse at a position further away from the light source  110 , and thus, by disposing the first prism portions  1011 A arranged more sparsely at positions closer to the light source  110  and disposing the first prism portions  1011 A arranged more densely at positions further away from the light source  110 , the first prism portions  1011 A can reflect less light at the positions closer to the light source  110  and reflect more light at positions further away from the light source  110 , so that the second prism sheet collimates more light at the positions closer to the light source  110  and collimates less light at the positions further away from the light source  110 . Therefore, uniformity of the emergent light at different positions of the light guide assembly can be regulated, so as to improve brightness uniformity of the light guide assembly. 
     For example, values of the widths of the first prism portions  1011 A and the first plane portions  1011 B and the like may be optimized by applying optimal simulation software (e.g., Lighttools or the like), for example, the widths and the spacing of the first prism portions  1011 A and/or the first plane portions  1011 B are taken as variables, a target function of brightness uniformity is set, and optimized parameters of the values of the widths of the first prism portions  1011 A and the first plane portions  1011 B and the like are obtained by calculation, e.g., parameters are subjected to iterative optimization in the Lighttools by adopting a Backlight Pattern Optimization (BPO) module and finally, the optimized parameters are obtained, and under the parameter setting, emergent brightness of the light guide assembly is more uniform. 
     In this embodiment, in the case that the first prism portions  1011 A are spaced with the first plane portions  1011 B, as shown in  FIG. 3 , the light emerging from the light guide assembly may emerge from the first prism portions  1011 A and for example, emerge from a point G, and also may emerge from the first plane portions  1011 B and for example, emerge from a point F. When the light emerges from the first plane portion  1011 B, the emergent light is basically perpendicular to the first plane portion  1011 B, and thus, the first plane portion  1011 B basically cannot change a propagation direction of the emergent light; and moreover, when the light emerges from the first prism portion  1011 A, the included angle α1 between the first prism portion  1011 A and the first plane  1012  is relatively small and for example, 0°&lt;α 1 ≤3°, and thus, the angle of the light emerging from the first prism portion  1011 A is also changed a little, the changed angle is set as γ, and then:
 
γ=arcsin( n 1×sin α 1 )−α 1  
 
     Where, n1 represents the refractive indexes of the first prism sheet  101  and the second prism sheet  103 , and α1 represents the included angle between the first prism portion  1011 A and the first plane  1012 . The angle γ is relatively small, and thus, the emergent light also may be considered to be propagated basically along the first direction. 
     For example, in this embodiment, as shown in  FIG. 5A , the first prism portion  1011 A also may be of a block shape, and a set density of the first prism portion  1011 A is increased along a direction (i.e., a horizontal direction from left to right in the drawing) away from the light incident side surface  1013 . For example, portions on the first prism surface  1101  except for the first prism portions  1011 A are all the first plane portions  1011 B. In this embodiment, an arrangement mode of the first prism portions  1011 A may be a regular array arrangement mode and also may be an irregular arrangement mode, and the embodiment does not make any limit thereto. 
     For example,  FIG. 5B  shows a schematic diagram of the block-shaped first prism portion  1011 A in one example. For example,  FIG. 5B  sequentially includes a top view of the first prism portion  1011 A and a cross-section view of the top view along a B-B line and an A-A line from left to right. In this example, for example, lengths d 3  and d 4  of both two main edges of the first prism portion  1011 A are 45 μm, a cross-section along the B-B line is a main cross-section of the first prism portion  1011 A, the included angle α 1 , i.e., the included angle between the first sub prism surface of the first prism portion  1011 A and the first plane, is 2°, and the included angle α 2 , i.e., the included angle between the second sub prism surface and the first plane, is 45°. In the cross-section of the first prism portion  1011 A along A-A, an included angle α 5  is 45°. In other examples of this embodiment, each parameter of the block-shaped first prism portion  1011 A may be selected as required, and the embodiment does not make any limit thereto. 
     In this embodiment, a plurality of second prism portions  1031 A, for example, may be continuously arranged on the second prism surface  1031 , i.e., side surfaces of each two adjacent second prism portions intersect with each other, so that more light can be calibrated and a utilization rate of the light is improved. 
     The light guide assembly provided by the embodiment of the present disclosure can change the light into the emergent light collimated basically along the first direction in the third direction, and emergent uniformity of the light guide assembly can be regulated by optimization on the parameters of the prism portion, so that brightness of the light emerging by the light guide assembly is higher and more uniform. 
     At least one embodiment of the present disclosure provides a light collimation assembly;  FIG. 6  is a planar schematic diagram of the light collimation assembly provided by this embodiment;  FIG. 7A  is a cross-sectional schematic diagram of the light collimation assembly in  FIG. 6  along an A-A line; and  FIG. 7B  is a cross-sectional schematic diagram of the light collimation assembly in  FIG. 6  along a B-B line. 
     As shown in  FIG. 6  to  FIG. 7B , the light collimation assembly  20  includes any one light guide assembly  10  above and a collimation part  201 , and the collimation part  201  is laminated with the light guide assembly  10  along the first direction and is arranged on a side of the light guide assembly  10  where the first prism sheet is arranged; the light guide assembly  10  can collimate a portion of light, which is propagated in the third direction, along the first direction and enable the collimated light to emerge; and the collimation part  201  is configured to receive the light emerging from the first prism sheet of the light guide assembly  10 , collimate a portion of the light, which is propagated along the second direction, towards the first direction and enable the collimated light to emerge. 
     For example, in this embodiment, the collimation part  201  includes a grating layer  202 , and the grating layer  202  includes a grating strip  2021  extending the third direction. The grating strip  2021  can take a modulation effect on the light. 
     For example, in this embodiment, the grating layer  202  may be arranged on a side of the collimation part  201 , which is close to the light guide assembly, or a side of the collimation part  201 , which is away from the light guide assembly. For example,  FIG. 7B  shows a case that the grating layer  202  is arranged on a side of the collimation part  201 , which is away from the light guide assembly, and when the grating layer  202  is arranged on a side of the collimation part  201 , which is close to the light guide assembly, an arrangement mode as shown in  FIG. 8A  is adopted. 
     For example, a cross section of the grating strip  2021  along the second direction is of a trapezoid shape, and a side surface of the grating strip  2021  has a reflection layer. As shown in  FIG. 7B , the grating layer  202  is arranged on a side of the collimation part  201 , which is away from the light guide assembly, the side surface of the grating strip  2021  has the reflection layer (e.g., a plated metal aluminum thin layer), and the top and the bottom of the grating strip  2021  are light transmission layers. When light is irradiated into an inner surface of the grating strip  2021  (e.g., light on a left side in the drawing), the light can be repeatedly reflected by the reflection layer of the grating strip  2021  and finally irradiated into the light guide assembly  10 , and after being modulated by the light guide assembly  10 , the light is returned to the collimation part  201 . When light is irradiated into an outer surface of the grating strip  2021  (e.g., light on a right side in the drawing), the light is reflected by the grating strip  2021  with the trapezoid cross-section, and the reflection can collimate the light towards the first direction and for example, reduce an angle between the light and the first direction, and thus, the collimation degree of the light along the first direction can be improved. 
     For example, when the grating layer  202  is arranged on a side of the collimation part  201 , which is away from the light guide assembly, i.e., the grating layer  202  in  FIG. 7B  is replaced with a grating layer  202  in  FIG. 8A , the side surface of the grating strip  2021  has a reflection layer, and the top and the bottom of the grating strip  2021  are light transmission layers. At the moment, when light is irradiated into the outer surface of the grating strip  2021  (e.g., light on a left side in the drawing), the light can be repeatedly reflected on the side surface of the grating strip  2021 , then irradiated into the light guide assembly  10 , and returned to the collimation part  201  after being modulated by the light guide assembly  10 . When light is irradiated into the inner surface of the grating strip  2021  (e.g., light on the right side in the drawing), the light is reflected by the grating strip  2021  with the trapezoid cross-section, and the reflection can collimate the light towards the first direction and for example, reduce an angle between the light and the first direction, and thus, the collimation degree of the light along the first direction can be improved. 
     For example, in this embodiment, a cross section of the grating strip  2021  along the second direction also may be of a rectangle shape, and a material of the grating strip  2021  is a light absorption material. 
     For example, when the grating layer  202  in  FIG. 7B  is replaced with a grating layer  202  in  FIG. 8B , in this example, the grating strip  2021  with the rectangular cross-section has light absorption property, and thus, light (e.g., light on the left side in the drawing) irradiated into the surface of the grating strip  2021  can be absorbed by the grating strip  2021  without emerging; and light (e.g., light on the right side in the drawing) which is not irradiated into the grating strip  2021  can transmit the collimation part  201  to emerge, and thus, the light with a small included angle with the first direction may emerge, so that the collimated light along the first direction may be obtained. In this embodiment, a part of light is absorbed by the grating strip  2021 , and thus, light emerging by the collimation part  201  may be relatively low in brightness, and at the moment, increment may be carried out by increasing the prism sheets and other modes. When the cross-section of the grating strip  2021  is of a rectangle shape, no matter whether the grating layer  202  is arranged on a side of the collimation part  201 , which is away from the light guide assembly, or the grating layer  202  is arranged on a side of the collimation part  201 , which is close to the light guide assembly, the collimation principles of the grating strips  2021  are the same and thus are not respectively described. 
     In a light collimation assembly provided by one embodiment of the present disclosure, the included angle α 1  between the first sub prism surface  1011 A 1  of the first prism sheet  101  of the light guide assembly and the first plane  1012  is 0.5°, and the included angle α 2  between the second sub prism surface  1011 A 2  and the first plane  1012  is 90°; the included angle α 3  between the third sub prism surface  1031 A 1  of the second prism sheet and the second plane  1032  is 57.5°, and the included angle α 4  between the fourth sub prism surface  1031 A 2  of the second prism sheet and the second plane  1032  is 90°; and the cross section of the collimation part  201  including the grating strip  2021  is of a trapezoid shape, a height of the trapezoid grating strip  2021  is 0.03 mm, a width of the trapezoid grating strip  2021  is 0.01 mm, a distance between the trapezoid grating strips  2021  is 0.02 mm, a base angle of the trapezoid grating strip  2021  is 80°, and the side surface of the grating strip  2021  has the reflection layer. Under the above-mentioned parameters and after testing, as shown in  FIG. 9A , in the third direction, a half-brightness angle of the emergent light collimated along the first direction after being modulated by the light collimation assembly is about ±10°, in the second direction, a half-brightness angle of the emergent light collimated along the first direction after being modulated by the light collimation assembly is about ±23°, the emergent light has a cut-off angle, and for example, the cut-off angles in the second direction and in the third direction are within a range of about ±50°. The half-brightness angle refers to an angle when light brightness is half of the highest brightness and may be used for evaluating the collimation degree of the light, and the smaller the half-brightness angle is, the higher the collimation degree of the light is. The cut-off angle refers to an angle when the light brightness is basically 0 or the light brightness is smaller than 5% of the highest brightness. 
     In a light collimation assembly provided by another embodiment of the present disclosure, parameters of the light guide assembly are the same with the above; i.e., the included angle cu between the first sub prism surface  1011 A 1  of the first prism sheet  101  of the light guide assembly and the first plane  1012  is 0.5°, and the included angle α 2  between the second sub prism surface  1011 A 2  and the first plane  1012  is 90°; the included angle α 3  between the third sub prism surface  1031 A 1  of the second prism sheet and the second plane  1032  is 57.5°, and the included angle α 4  between the fourth sub prism surface  1031 A 2  of the second prism sheet and the second plane  1032  is 90°; and different from the above, the cross section of the collimation part  201  including the grating strip  2021  is of a rectangle shape, at the moment, a height of the rectangular grating strip  2021  is 0.03 mm, a width of the rectangular grating strip  2021  is 0.01 mm, a distance between the rectangular grating strips  2021  is 0.02 mm, and the grating strip  2021  includes a light absorption material. Under the above-mentioned parameters and after testing, as shown in  FIG. 9B , in the third direction, a half-brightness angle of the emergent light collimated along the first direction after being modulated by the light collimation assembly is about ±9°, in the second direction, the half-brightness angle of the emergent light collimated along the first direction after being modulated by the light collimation assembly is about ±19°, the emergent light has a cut-off angle, and for example, the cut-off angles in the second direction and in the third direction are within a range of about ±40°. 
     It can be seen that the light collimation assembly provided by the embodiments of the present disclosure can simultaneously implement collimation on the light in the second direction and the third direction, i.e., can implement two-dimensional collimation on the light. In addition, by optimization on the parameters of each part in the light collimation assembly, when the light emerging from the light collimation assembly is collimated along the first direction, the brightness of the emergent light can be higher and more uniform. 
     In another aspect, conventional design generally adopts a plurality of reflection sheets to regulate the propagation path of the light, and thus, arrangement of the reflection sheets is complex and needs to be designed by a precise light path design, but the light collimation assembly provided by the embodiments of the present disclosure reduces use of the reflection sheets in the conventional design by design on a prism microstructure, so that the structure of the light collimation assembly is simpler. 
     At least one embodiment of the present disclosure provides a backlight module, and as shown in  FIG. 10 , the backlight module  100  includes any one light guide assembly  10  above or any one light collimation assembly  20  above. 
     For example, the backlight module provided by this embodiment further may include a light source  110 , and the light source  110  is arranged on the light incident side surface  1013  of the first prism sheet  101  in the light guide assembly  10 . The light source  110 , for example, includes a plurality of light-emitting structures such as LEDs and the like, which are arranged side by side, and the light-emitting structures, for example, are linearly arranged along the light incident side surface  1013 . The light source also may be a linear light source such as a Cold Cathode Fluorescent Lamp (CCFL) and the like. 
     For example, when the first prism portion  1011 A structurally is of a strip shape, the first prism portion  1011 A closer to the light source  110  has a smaller width; or, the first plane portion  1011 B closer to the light source  110  has a greater width; or, when the first prism portion  1011 A closer to the light source  110  has a smaller width, the first plane portion  1011 B closer to the light source  110  has a greater width. The design can regulate uniformity of the emergent light at different positions of the light guide assembly, so that the brightness uniformity of the backlight module can be improved. 
     Emergent light of the backlight module provided by the embodiments of the present disclosure is collimated light, and the backlight module is high in utilization rate for the light source  110 , and thus, energy consumption can be reduced. 
     At least one embodiment of the present disclosure provides a display device, and as shown in  FIG. 11 , the display device  200  includes any one backlight module  100  above. The display device  200  may be any product or part with a display function, such as a mobile phone, a tablet personal computer, a television, a display, a notebook computer, a digital photo frame, a navigator and the like. In this embodiment, the display device is relatively low in display energy consumption and uniform in light emergence. 
     For example, emergent light of the display device  200  has the collimation property, and thus, the display device  200  can implement intelligent display, for example, has the characteristics of preventing peep, displaying a High Dynamic Range (HDR) image and the like so as to meet functional demands of different types of display device, and for example, may be applied to a display device for Virtual Reality (VR) display, vehicle-mounted display, 3D display and the like, which have specific use distances and specific inclination angles. 
     The following points should be noted: 
     (1) The accompanying drawings in the embodiments of the present invention only involve structures relevant to the embodiments of the present invention, and other structures may refer to the prior art. 
     (2) For clarity, in the accompanying drawings of the embodiments of the present invention, the thickness and the size of layers or microstructures are enlarged. It should be understood that: when an element such as a layer, a film, a region or a substrate is referred to as being disposed “on” or “beneath” another element, the element may be “directly” disposed “on” or “beneath” another element, or an intermediate element may be provided. 
     (3) The characteristics in the same embodiment or different embodiments of the present invention may be mutually combined without conflict. 
     The foregoing detailed description of the disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. The described embodiments were chosen in order to best explain the principles of the disclosure and its practical application to thereby enable the skilled in the art to best utilize the disclosure in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the disclosure be defined by the claims appended hereto. 
     The application claims priority to the Chinese patent application No. 201811257793.X, filed Oct. 26, 2018, the disclosure of which is incorporated herein by reference as part of the application.