A backlight module and a display device

Abstract

The present invention relates to a backlight module, which includes an LED light bar, a reflective sheet, a light guide plate, and an optical film stack arranged in sequence. The light guide plate includes opposite first and second surfaces, and a first side surface connecting the first and second surfaces. The LED light bar is arranged parallel and opposite to one side of the first side surface of the light guide plate and has a plurality of light guide columns arranged in an array facing the first side surface. The optical film includes a first optical film and a second optical film stacked in sequence on the first surface of the light guide plate. The first optical film includes a first substrate layer and a first microstructure layer provided on the first surface of the first substrate layer. The second optical film includes a second substrate layer and a second microstructure layer provided on the first surface of the second substrate layer. The first microstructure layer and the second microstructure are arranged adjacent to each other. The structural design of this backlight module can control the light-emitting angle within the range of ±15° at the central viewing angle perpendicular to the second surface of the second optical film, achieving an anti-peeping effect.

Description

Technical Field

[0001] The present invention relates to the field of display technologies, and particularly to a backlight module and a display device. Background Art

[0002] The main function of a backlight source is to form a uniform surface light source from the line light source arranged by LEDs. The optical components therein include a light guide plate and various optical elements for adjusting and correcting the light emitted from the light guide plate. Traditional backlight structures are mainly composed of a light source, a light guide plate, a diffusion sheet, a lower brightness enhancement film, an upper brightness enhancement film, etc. The surface dot structure of the light guide plate will destroy the waveguide propagation of light. The horizontal / vertical light emission angles of the light emitted from the light guide plate are relatively large after passing through the diffusion film and the prism sheet, and the light utilization rate is low, resulting in insufficient frontal brightness.

[0003] For some display products with requirements for high brightness, low power consumption, and anti-peeking, a backlight source structure design that can adjust the light emission angle of the backlight source, improve the brightness of the backlight source, and meet the optical property requirements needs to be designed. Summary of the Invention

[0004] The main purpose of the present application is to provide a backlight module that can reduce the proportion of large-angle light, improve the light utilization rate, increase the light utilization rate, and achieve an anti-peeking effect.

[0005] To achieve the above purpose, the present application provides a backlight module, including an LED light bar, a reflective sheet, a light guide plate, and an optical film stack arranged in sequence. The light guide plate includes opposite first and second surfaces, and a first side surface connecting the first and second surfaces. The LED light bar is arranged parallel and opposite to one side of the first side surface of the light guide plate and has a plurality of light guide columns arranged in an array facing the first side surface. The optical film stack includes a first optical film and a second optical film stacked in sequence on the first surface of the light guide plate. The first optical film includes a first base layer and a first micro-structure layer provided on the first surface of the first base layer. The second optical film includes a second base layer and a second micro-structure layer provided on the first surface of the second base layer. The first micro-structure layer and the second micro-structure layer are arranged adjacent to each other.

[0006] As a further improvement of the present application, the first micro-structure layer includes a plurality of first strip-shaped structures, and the second micro-structure layer includes a plurality of second strip-shaped structures.

[0007] As a further improvement of the present application, the first micro-structure layer includes a plurality of first strip-shaped structures extending along the Y direction and arranged substantially along the X direction, and the second micro-structure layer includes a plurality of second strip-shaped structures extending substantially along the X direction and arranged along the Y direction.

[0008] As a further improvement of the present application, the first strip-shaped structure is a first convex arc-shaped column, and the numerical range of the height difference H1 from the wave crest of the first convex arc-shaped column to the first surface of the first substrate layer is 1 μm to 150 μm. The numerical range of the distance P1 between adjacent first convex arc-shaped columns along the X direction is 1 μm to 800 μm. The numerical range of the length L1 of the bottom edge of the cross-section of the first convex arc-shaped column is 1 μm to 400 μm.

[0009] As a further improvement of the present application, the first strip-shaped structure is a first convex prism, and the numerical range of the height difference H2 from the wave crest of the first convex prism to the first surface of the first substrate layer is 1 μm to 220 μm. The numerical range of the distance P2 between adjacent first convex prisms along the X direction is 1 μm to 800 μm. The numerical range of the length L2 of the bottom edge of the cross-section of the first convex prism is 1 μm to 200 μm.

[0010] As a further improvement of the present application, the refractive index of the first substrate layer is 1.30 to 3.00, and the light transmittance of the first substrate layer > 90%; the refractive index of the first micro-structure layer is 1.30 to 3.00, and the light transmittance of the first micro-structure layer > 90%.

[0011] As a further improvement of the present application, the refractive index of the first substrate layer is substantially the same as the refractive index of the first micro-structure layer.

[0012] As a further improvement of the present application, the second strip-shaped structure is a second convex prism, and the numerical range of the height difference H3 from the wave crest of the second convex prism to the first surface of the second substrate layer is 1 μm to 150 μm. The numerical range of the length L3 of the bottom edge of the cross-section of the second convex prism is 1 μm to 100 μm.

[0013] As a further improvement of the present application, a first light guide plate micro-structure is provided on the first surface of the light guide plate. The first light guide plate micro-structure includes an opposite top surface and a bottom surface, and a side surface connected between the top surface and the bottom surface. The bottom surface faces the first surface of the light guide plate. The positive projection of the side surface of the first light guide plate micro-structure on the first surface of the light guide plate presents an S-shaped curve. The distance between adjacent two light guide columns arranged along the X direction is w1. The maximum vertical distance between the S-shaped curve and the first side surface of the light guide plate is h1. The refractive index of the light guide plate is n1, then h1 satisfies the following conditions:

[0014]

[0015] As a further improvement of the present application, a dot area is provided on the first surface of the light guide plate, the dot area is adjacent to the first side surface of the light guide plate, and the orthographic projection of the dot area on the first surface of the light guide plate presents a plurality of U-shaped arc curves, the U-shaped arc curves are concave relative to the first side surface of the light guide plate, and the point where the vertical distance between the U-shaped arc curve and the first side surface of the light guide plate is the largest is directly opposite to the middle position of two adjacent light guide columns, the spacing between two adjacent light guide columns arranged along the X direction is w2, the maximum vertical distance between the U-shaped arc curve and the first side surface of the light guide plate is h2, and the refractive index of the light guide plate is n2, then h2 satisfies the following conditions:

[0016]

[0017] As a further improvement of the present application, the first light guide plate microstructure includes a plurality of concave or convex third strip structures extending along the Y direction and substantially arranged along the X direction.

[0018] As a further improvement of the present application, the third strip structure is a third concave prism, and the height difference H4 from the trough of the third concave prism to the first surface of the light guide plate has a numerical range of 1μm to 170μm, the distance P4 between adjacent third concave prisms along the X direction has a numerical range of 1μm to 500μm, and the length L4 of the bottom edge of the cross-section of the third concave prism has a numerical range of 1μm to 120μm.

[0019] As a further improvement of the present application, the third strip structure is a third convex arc-shaped column, and the height difference H5 from the crest of the third convex arc-shaped column to the first surface of the light guide plate has a numerical range of 1μm to 150μm, the distance P5 between adjacent third convex arc-shaped columns along the X direction has a numerical range of 1μm to 500μm, and the length L5 of the bottom edge of the cross-section of the third convex arc-shaped column has a numerical range of 1μm to 200μm.

[0020] As a further improvement of the present application, a first light guide plate dot structure is arranged on the second surface of the light guide plate, and the first light guide plate dot structure includes a plurality of concave or convex first dots arranged in an array or non-array, and the shape of the projection of the first dots on the light guide plate is circular, square, elliptical or rectangular.

[0021] As a further improvement of the present application, the first grid point is a convex pyramid, the projection of the convex pyramid on the ZY plane is a triangle, the value range of the base length L6 of the triangle is 5μm to 500μm, the value range of the height H6 of the triangle is 1μm to 150μm, and the value range of the spacing P6 between two adjacent triangles along the Y direction is P6<900μm.

[0022] As a further improvement of the present application, the first light guide point is a convex sphere, the projection of the convex sphere on the Z-Y plane is a semi-circular arc, the numerical range of the bottom side length L7 of the semi-circular arc is 5 μm to 500 μm, the numerical range of the maximum height H7 from the semi-circular arc to the second surface of the light guide plate is 1 μm to 220 μm, and the numerical range of the spacing P7 between two adjacent semi-circular arcs in the Y direction is P7 < 800 μm.

[0023] As a further improvement of the present application, a second light guide plate dot structure is provided on the first side surface of the light guide plate. The second light guide plate dot structure includes a plurality of concave or convex second dots arranged in an array or non-array. The shape of the projection of the second dot on the light guide plate is circular, square, elliptical or rectangular.

[0024] As a further improvement of the present application, the second dot is a convex sphere, the projection of the convex sphere on the X-Y plane is a semi-circular arc, the numerical range of the bottom side length L8 of the semi-circular arc is 1 μm to 200 μm, the numerical range of the maximum height H8 from the semi-circular arc to the second surface of the light guide plate is 1 μm to 140 μm, and the numerical range of the spacing P8 between two adjacent semi-circular arcs in the X direction is 1 μm to 800 μm.

[0025] To achieve the above object, the present application further provides a display device, and the display device includes the above-mentioned backlight module.

[0026] The beneficial effect of the present application is that a backlight module is provided, which includes an LED light bar, a reflective sheet, a light guide plate and an optical film stack arranged in layers in sequence. The light guide plate includes a first surface and a second surface opposite to each other, and a first side surface connecting the first surface and the second surface. The LED light bar is arranged parallel and opposite to one side of the first side surface of the light guide plate and has a plurality of light guide columns arranged in an array facing the first side surface. The optical film includes a first optical film and a second optical film stacked in sequence on the first surface of the light guide plate. The first optical film includes a first substrate layer and a first micro-structure layer provided on the first surface of the first substrate layer. The second optical film includes a second substrate layer and a second micro-structure layer provided on the first surface of the second substrate layer. The first micro-structure layer and the second micro-structure layer are arranged adjacent to each other. The structural design of this backlight module can control the light-emitting angle within the range of ±15° of the central viewing angle perpendicular to the second surface of the second optical film, achieving an anti-peeping effect. Description of the Drawings

[0027] Figure 1 It is a three-dimensional structural schematic diagram of the backlight module;

[0028] Figure 2It is the front view of the backlight module in the Z-Y plane;

[0029] Figure 3 It is the schematic structural diagram of the state 1 of the first microstructure layer in the first optical film;

[0030] Figure 4 It is the schematic structural diagram of the state 2 of the first microstructure layer in the first optical film;

[0031] Figure 5 It is the schematic structural diagram of the state 1 of the second microstructure layer in the second optical film;

[0032] Figure 6 It is the schematic structural diagram of the state 1 of the first light guide plate microstructure provided on the light guide plate;

[0033] Figure 7 It is the schematic structural diagram of the dot area on the first surface of the light guide plate;

[0034] Figure 8 It is the schematic structural diagram of the state 1 of the first light guide plate microstructure provided on the first surface of the light guide plate;

[0035] Figure 9 It is the schematic structural diagram of the state 2 of the first light guide plate microstructure provided on the first surface of the light guide plate;

[0036] Figure 10 It is the schematic structural diagram of the state 1 of the first light guide plate dot structure provided on the second surface of the light guide plate;

[0037] Figure 11 It is the schematic structural diagram of the state 2 of the first light guide plate dot structure provided on the second surface of the light guide plate;

[0038] Figure 12 It is the schematic structural diagram of the state 1 of the second light guide plate dot structure provided on the first side surface of the light guide plate;

[0039] Figure 13 It is the vertical direction light intensity view angle distribution of the backlight module;

[0040] Figure 14 It is the horizontal direction light intensity view angle distribution of the backlight module;

[0041] In the figure: 1. LED light bar; 2. Reflective sheet; 3. Light guide plate; 4. First optical film; 5. Second optical film; 31. First side surface of the light guide plate; 311. Second light guide plate dot structure; 32. Second surface of the light guide plate; 33. First surface of the light guide plate; 331. First light guide plate microstructure; 332. Dot area; 321. First light guide plate dot structure; 41. First base layer; 42. First surface of the first base layer; 421. First microstructure layer; 51. Second base layer; 52. First surface of the second base layer; 521. Second microstructure layer. Detailed implementation manners

[0042] To make the objectives, technical solutions, and advantages of the present application clearer, the technical solutions of the present application will be clearly and completely described below in conjunction with specific embodiments of the present application and the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments, and are not used to limit the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present application.

[0043] Figure 1 is a three-dimensional view of a backlight module according to an embodiment of the present disclosure. It should be noted that in this article, for convenience of description, a three-dimensional rectangular coordinate system XYZ is established, and the three coordinate axes are respectively defined as the X axis, the Y axis (perpendicular to the X axis), and the Z axis (perpendicular to both the X axis and the Y axis). Refer to Figure 1 and Figure 2 , the backlight module includes an LED light bar 1, a reflective sheet 2, a light guide plate 3, and an optical film stacked in sequence, where: the light guide plate 3 includes an opposite first surface and a second surface, and a first side surface connecting the first surface and the second surface. The LED light bar 1 is arranged parallel and opposite to one side of the first side surface 31 of the light guide plate and has a plurality of light guide columns arranged in an array facing the first side surface. For example, the first surface 33 and the second surface 32 of the light guide plate are parallel to the X-Y plane, the first side surface 31 of the light guide plate is parallel to the X-Z plane, and according to the three-dimensional rectangular coordinate system, the Y-Z plane is also included. It should be noted that the expressions such as the three-dimensional rectangular coordinate system XYZ, the X-Y plane, the X-Z plane, the Y-Z plane, the X direction, the Y direction, and the Z direction are only for convenience of describing the embodiments of the present disclosure and should not be construed as a limitation to the present disclosure.

[0044] In the embodiments of the present application, as Figure 1 and Figure 2As shown in the figure, the optical film includes a first optical film 4 and a second optical film 5 which are sequentially stacked on the first surface 33 of the light guide plate. The first optical film 4 includes a first base layer 41 and a first microstructure layer 421 provided on the first surface 42 of the first base layer. The second optical film 5 includes a second base layer 51 and a second microstructure layer 521 provided on the first surface 52 of the second base layer. The first microstructure layer 421 and the second microstructure layer 521 are arranged adjacent to each other. Further, the first microstructure layer 421 includes a plurality of first strip-shaped structures, and the second microstructure layer 521 includes a plurality of second strip-shaped structures. Still further, as Figure 3 and Figure 4 shown, the first microstructure layer 421 includes a plurality of first strip-shaped structures extending along the Y direction and arranged substantially along the X direction; as Figure 5 shown, the second microstructure layer 521 includes a plurality of second strip-shaped structures extending substantially along the X direction and arranged substantially along the Y direction.

[0045] As Figure 3 shown, in a specific embodiment of the present application, the first strip-shaped structure is a first convex arc-shaped column. The positive projection of the first convex arc-shaped column in the X-Z plane is an arc. The value range of the height difference H1 from the peak of the first convex arc-shaped column to the first surface 42 of the first base layer is 1 μm to 150 μm, that is, the value range of the vertical distance H1 from the points on the arc to the first surface of the first base material is 1 μm to 150 μm. The value range of the distance P1 between adjacent first convex arc-shaped columns along the X direction is 1 μm to 800 μm. Adjacent first convex arc-shaped columns can be closely arranged or spaced apart. The value range of the length L1 of the bottom edge of the cross section of the first convex arc-shaped column is 1 μm to 400 μm, that is, the value range of the length L1 of the straight line edge where the arc contacts the first surface of the first base material is 1 μm to 400 μm.

[0046] As Figure 4 shown, in another specific embodiment of the present application, the first strip-shaped structure is a first convex prism. The positive projection of the first convex prism in the X-Z plane is a first triangle. The value range of the height difference H2 from the peak of the first convex prism to the first surface 42 of the first base layer is 1 μm to 220 μm, that is, the value range of the height difference H2 from the vertex of the first triangle to the first surface 42 of the first base layer is 1 μm to 220 μm. The value range of the distance P2 between adjacent first convex prisms along the X direction is 1 μm to 800 μm. Adjacent first convex prisms can be closely arranged or spaced apart. The value range of the length L2 of the bottom edge of the cross section of the first convex prism is 1 μm to 200 μm, that is, the value range of the length L2 of the straight line edge where the first triangle contacts the first surface of the first base material is 1 μm to 200 μm.

[0047] Further, in the first optical film 4, both the first base layer 41 and the first micro-structure layer 421 can be but are not limited to being prepared from optical resin materials. The refractive index of the first base layer 41 is 1.30 to 3.00, and the light transmittance of the first base layer 41 is > 90%. Preferably, the first base layer 41 can be at least one of PET and PC; the refractive index of the first micro-structure layer 421 is 1.30 to 3.00, and the light transmittance of the first micro-structure layer 421 is > 90%. Preferably, when the refractive index of the first base layer 41 is substantially the same as that of the first micro-structure layer 421, the light transmission effect in the first optical film 4 is optimal.

[0048] As Figure 5 shown, in a specific embodiment of the present application, the second strip-shaped structure is a second convex prism. The orthographic projection of the second convex prism on the Y-Z plane is a second triangle. The value range of the height difference H3 from the wave crest of the second convex prism to the first surface 52 of the second base layer is 1 μm to 150 μm, that is, the value range of the height difference H3 from the vertex of the second triangle to the first surface 52 of the second base layer is 1 μm to 150 μm. The value range of the length L3 of the bottom side of the cross-section of the second convex prism is 1 μm to 100 μm, that is, the value range of the length L3 of the straight line side where the second triangle contacts the first surface of the second base is 1 μm to 100 μm.

[0049] As Figure 6 shown, in a specific embodiment of the present application, a first light guide plate micro-structure 331 is provided on the first surface 33 of the light guide plate. The first light guide plate micro-structure 331 includes an opposite top surface and bottom surface, and side surfaces connected between the top surface and the bottom surface. The bottom surface faces the first surface 33 of the light guide plate. The orthographic projection of the side surface of the first light guide plate micro-structure 331 on the first surface 33 of the light guide plate presents an S-shaped curve. The distance between adjacent two light guide columns substantially arranged in the X direction is w1. The maximum vertical distance between the S-shaped curve and the first side surface 31 of the light guide plate is h1. The refractive index of the light guide plate 3 is n1, then h1 satisfies the following conditions:

[0050]

[0051] As Figure 7As shown, in a specific embodiment of the present application, a dot area 332 is provided on the first surface 33 of the light guide plate. The dot area 332 is adjacent to the first side surface 31 of the light guide plate. The orthographic projection of the dot area 332 on the first surface 33 of the light guide plate presents a number of U-shaped arc curves. The U-shaped arc curves are concave with respect to the first side surface 31 of the light guide plate. The point where the vertical distance from the U-shaped arc curve to the first side surface 31 of the light guide plate is the largest is opposite to the middle position between two adjacent light guide columns. The distance between two adjacent light guide columns arranged substantially along the X direction is w2, the maximum vertical distance between the U-shaped arc curve and the first side surface 31 of the light guide plate is h2, and the refractive index of the light guide plate 3 is n2. Then h2 satisfies the following conditions:

[0052]

[0053] Further, in a specific embodiment of the present application, a first light guide plate microstructure 331 is provided on the first surface 33 of the light guide plate, and the dot area 332 provided on the first surface 33 of the light guide plate can be designed separately or in a mixed way, and can be comprehensively considered according to the light utilization rate and the desired effect.

[0054] In a specific embodiment of the present application, as Figure 8 and Figure 9 shown, the first light guide plate microstructure 331 can be designed to include a number of third strip-shaped structures that extend substantially along the Y direction and are arranged substantially along the X direction and are concave or convex.

[0055] In a specific embodiment of the present application, as Figure 8 shown, the third strip-shaped structure is a third concave prism. The numerical range of the height difference H4 from the trough of the third concave prism to the first surface 33 of the light guide plate is 1 μm to 170 μm. The numerical range of the distance P4 between adjacent third concave prisms along the X direction is 1 μm to 500 μm. The numerical range of the length L4 of the bottom edge of the cross section of the third concave prism is 1 μm to 120 μm.

[0056] In a specific embodiment of the present application, as Figure 9 shown, the third strip-shaped structure is a third convex arc column. The numerical range of the height difference H5 from the peak of the third convex arc column to the first surface 33 of the light guide plate is 1 μm to 150 μm. The numerical range of the distance P5 between adjacent third convex arc columns along the X direction is 1 μm to 500 μm. The numerical range of the length L5 of the bottom edge of the cross section of the third convex arc column is 1 μm to 200 μm.

[0057] In a specific embodiment of the present application, as Figure 10 and Figure 11As shown, a first light guide plate dot structure 321 is provided on the second surface 32 of the light guide plate. The first light guide plate dot structure 321 includes a number of concave or convex first dots arranged in an array or non-array. The shape of the projection of the first dots on the light guide plate 3 is circular, square, oval or rectangular.

[0058] In a specific embodiment of the present application, as Figure 10 shown, the first dot is a convex pyramid. The projection of the convex pyramid on the Z-Y plane is a triangle. The numerical range of the base length L6 of the triangle is 5 μm to 500 μm, the numerical range of the height H6 of the triangle is 1 μm to 150 μm, and the numerical range of the distance P6 between two adjacent triangles in the Y direction is P6 < 900 μm.

[0059] In a specific embodiment of the present application, as Figure 11 shown, the first dot is a convex sphere. The projection of the convex sphere on the Z-Y plane is a semi-circular arc. The numerical range of the base length L7 of the semi-circular arc is 5 μm to 500 μm, the numerical range of the maximum height H7 from the semi-circular arc to the second surface 32 of the light guide plate is 1 μm to 220 μm, and the numerical range of the distance P7 between two adjacent semi-circular arcs in the Y direction is P7 < 800 μm.

[0060] In a specific embodiment of the present application, a second light guide plate dot structure 311 is provided on the first side surface 31 of the light guide plate. The second light guide plate dot structure 311 includes a number of concave or convex second dots arranged in an array or non-array. The shape of the projection of the second dots on the light guide plate 3 is circular, square, oval or rectangular. In a specific embodiment of the present application, as Figure 12 shown, the second dot is a convex sphere. The projection of the convex sphere on the X-Y plane is a semi-circular arc. The numerical range of the base length L8 of the semi-circular arc is 1 μm to 200 μm, the numerical range of the maximum height H8 from the semi-circular arc to the second surface 32 of the light guide plate is 1 μm to 140 μm, and the numerical range of the distance P8 between two adjacent semi-circular arcs in the X direction is 1 μm to 800 μm.

[0061] In some embodiments, the present application also conducts a test on the light intensity angular distribution of the backlight module. After testing, the light enters the backlight module through the first side surface 31 of the light guide plate and then exits through the second surface of the second optical film 5. The light intensity angular distribution in the vertical direction of the second surface of the second optical film 5 is as Figure 13 shown, and the light intensity angular distribution in the horizontal direction of the second surface of the second optical film 5 is as Figure 14 shown. The horizontal direction and the vertical direction in the present application are asFigure 1 The directions identified therein.

[0062] An embodiment of the present application further provides a display device, and the display device includes the above-mentioned backlight module.

[0063] In summary, the present application provides a backlight module, wherein: a first light guide plate dot structure 321 is provided on the second surface 32 of the light guide plate, a second light guide plate dot structure 311 is provided on the first side surface 31 of the light guide plate, and the first light guide plate dot structure 321 and / or the second light guide plate dot structure is a convex or concave microstructure, and the microstructure may be a cone, a hemisphere and other structures. Further, the included angle between the tangent of the surface of the first light guide plate dot structure 321 and the second surface 32 of the light guide plate is within 7°; the included angle between the tangent of the surface of the second light guide plate dot structure and the first side surface 31 of the light guide plate is within 7°. A first light guide plate microstructure 331 is provided on the first surface 33 of the light guide plate, and the first light guide plate microstructure 331 is a third strip structure, and the strip structure is designed to include a plurality of third strip structures that are substantially extended along the Y direction and substantially arranged along the X direction and are concave or convex. The structural design of the light guide plate 3 by the first light guide plate dot structure 321, the second light guide plate dot structure 311 and the first light guide plate microstructure 331 enables the light exit angle of the light guide plate 3 to be between 65° and 90°.

[0064] In the backlight module, a first optical film is further placed on the first surface of the light guide plate 3. The first optical film 4 includes a first substrate layer 41 and a first microstructure layer 421 provided on the first surface 42 of the first substrate layer. The first microstructure layer 421 includes a plurality of first strip structures; a second optical film 5 is placed on the first surface of the first optical film 4. The first surface of the second optical film 5 is a side surface that is parallel to the first surface of the first optical film 4 and is close to the first surface of the first optical film 4, and a second strip structure is distributed on the first surface of the second optical film 5.

[0065] The above structural design of the backlight module is beneficial to reducing the large-angle light ratio, improving the light utilization rate, and increasing the display brightness; during use, the light exit angle passing through the backlight module is controlled within 15°, achieving an anti-peeping effect. The backlight module of the present application is applied to display fields requiring high brightness and anti-peeping, such as mobile phones, pads, notebooks and other products.

[0066] In the description of this specification, "substantially along the X direction" or "substantially along the Y direction" does not strictly limit it to be exactly the same as the X direction or the Y direction, and there may also be a deviation within ±5°. In the description of this specification, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, unless otherwise specified, the meaning of "a plurality" is two or more. In addition, the description with reference to terms such as "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0067] Although the embodiments of this application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of this application, and the scope of this application is defined by the claims and their equivalents.

Claims

1. A backlight module, comprising an LED light bar, a reflective sheet, a light guide plate and an optical film stacked in sequence. The light guide plate includes a first surface and a second surface opposite to each other, and a first side surface connecting the first surface and the second surface. The LED light bars are arranged in parallel and opposite to each other on one side of the first side surface of the light guide plate and have a plurality of light guide columns arranged in an array facing the first side surface, characterized in that, The optical film includes a first optical film and a second optical film that are sequentially stacked on the first surface of the light guide plate. The first optical film includes a first substrate layer and a first microstructure layer disposed on the first surface of the first substrate layer. The second optical film includes a second substrate layer and a second microstructure layer disposed on the first surface of the second substrate layer. The first microstructure layer and the second microstructure are disposed adjacent to each other. The refractive index of the first substrate layer is 1.30 to 3.00, and the refractive index of the first microstructure layer is 1.30 to 3.00; A first light guide plate microstructure is disposed on the first surface of the light guide plate. The first light guide plate microstructure includes an opposite top surface and bottom surface, and a side surface connecting between the top surface and the bottom surface. The bottom surface faces the first surface of the light guide plate. The positive projection of the side surface of the first light guide plate microstructure on the first surface of the light guide plate presents an S-shaped curve. The distance between two adjacent light guide columns disposed along the X direction is w1. The maximum vertical distance between the S-shaped curve and the first side surface of the light guide plate is h1. The refractive index of the light guide plate is n1. Then h1 satisfies the following conditions: 。 2. The backlight module according to claim 1, wherein, The first microstructure layer includes a plurality of first strip-shaped structures, and the second microstructure layer includes a plurality of second strip-shaped structures.

3. The backlight module according to claim 2, wherein The first microstructure layer includes a plurality of first strip-shaped structures that extend substantially along the Y direction and are arranged substantially along the X direction. The second microstructure layer includes a plurality of second strip-shaped structures that extend substantially along the X direction and are arranged substantially along the Y direction.

4. The backlight module according to claim 2 or 3, characterized in that, The first strip-shaped structure is a first convex arc-shaped column. The numerical range of the height difference H1 from the wave crest of the first convex arc-shaped column to the first surface of the first substrate layer is 1 μm to 150 μm. The numerical range of the distance P1 between adjacent first convex arc-shaped columns along the X direction is 1 μm to 800 μm. The numerical range of the length L1 of the bottom side of the cross section of the first convex arc-shaped column is 1 μm to 400 μm.

5. The backlight module according to claim 2 or 3, characterized in that, The first strip-shaped structure is a first convex prism. The numerical range of the height difference H2 from the wave crest of the first convex prism to the first surface of the first substrate layer is 1 μm to 220 μm. The numerical range of the distance P2 between adjacent first convex prisms along the X direction is 1 μm to 800 μm. The numerical range of the length L2 of the bottom side of the cross section of the first convex prism is 1 μm to 200 μm.

6. The backlight module according to claim 1, wherein, The light transmittance of the first substrate layer > 90%; the light transmittance of the first microstructure layer > 90%.

7. The backlight module according to claim 1, characterized in that The refractive index of the first substrate layer is substantially consistent with the refractive index of the first microstructure layer.

8. The backlight module according to claim 2 or 3, characterized in that The second strip-shaped structure is a second convex prism. The numerical range of the height difference H3 from the wave crest of the second convex prism to the first surface of the second substrate layer is 1 μm to 150 μm. The numerical range of the length L3 of the bottom side of the cross section of the second convex prism is 1 μm to 100 μm.

9. The backlight module according to claim 1, wherein A dot area is provided on the first surface of the light guide plate, the dot area is adjacent to the first side surface of the light guide plate, the orthographic projection of the dot area on the first surface of the light guide plate presents a plurality of U-shaped arc curves, the U-shaped arc curves are concave relative to the first side surface of the light guide plate, the point where the vertical distance between the U-shaped arc curve and the first side surface of the light guide plate is the largest is directly opposite to the middle position of two adjacent light guide pillars, the spacing between two adjacent light guide pillars arranged along the X direction is w2, the maximum vertical distance between the U-shaped arc curve and the first side surface of the light guide plate is h2, the refractive index of the light guide plate is n2, then h2 satisfies the following conditions: 。 10. The backlight module according to claim 1, characterized in that, The first light guide plate microstructure includes a plurality of concave or convex third strip structures extending substantially along the Y direction and substantially arranged along the X direction.

11. The backlight module according to claim 10, wherein The third strip structure is a third concave prism, and the height difference H4 from the trough of the third concave prism to the first surface of the light guide plate has a numerical range of 1μm to 170μm, the distance P4 between the third concave prisms adjacent to each other along the X direction has a numerical range of 1μm to 500μm, and the length L4 of the bottom side of the cross section of the third concave prism has a numerical range of 1μm to 120μm.

12. The backlight module according to claim 10, wherein The third strip structure is a third convex arc-shaped column, and the height difference H5 from the crest of the third convex arc-shaped column to the first surface of the light guide plate has a numerical range of 1μm to 150μm, the distance P5 between adjacent third convex arc-shaped columns along the X direction has a numerical range of 1μm to 500μm, and the length L5 of the bottom edge of the cross-section of the third convex arc-shaped column has a numerical range of 1μm to 200μm.

13. The backlight module according to claim 1, characterized in that, A first light guide plate dot structure is arranged on the second surface of the light guide plate, and the first light guide plate dot structure includes a plurality of concave or convex first dots arranged in an array or non-array, and the projection shape of the first dots on the light guide plate is circular, square, elliptical or rectangular.

14. The backlight module according to claim 13, wherein The first grid point is a convex pyramid, and the projection of the convex pyramid on the ZY plane is a triangle. The value range of the base length L6 of the triangle is 5μm to 500μm, the value range of the height H6 of the triangle is 1μm to 150μm, and the value range of the spacing P6 between two adjacent triangles along the Y direction is P6<900μm.

15. The backlight module according to claim 13, wherein The first grid point is a convex sphere, and the projection of the convex sphere on the ZY plane is a semicircular arc. The numerical range of the base length L7 of the semicircular arc is 5μm to 500μm, the numerical range of the maximum height H7 from the semicircular arc to the second surface of the light guide plate is 1μm to 220μm, and the numerical range of the spacing P7 between two adjacent semicircular arcs along the Y direction is P7<800μm.

16. The backlight module according to claim 1, characterized in that, A second light guide plate dot structure is arranged on the first side of the light guide plate, and the second light guide plate dot structure includes a plurality of concave or convex second dots arranged in an array or non-array, and the projection of the second dots on the light guide plate is in the shape of a circle, square, ellipse or rectangle.

17. The backlight module according to claim 16, wherein The second dot is a convex sphere, and the projection of the convex sphere on the X-Y plane is a semi-circular arc. The numerical range of the bottom side length L8 of the semi-circular arc is 1 μm to 200 μm, the numerical range of the maximum height H8 from the semi-circular arc to the second surface of the light guide plate is 1 μm to 140 μm, and the numerical range of the spacing P8 between two adjacent semi-circular arcs along the X direction is 1 μm to 800 μm.

18. A display device, characterized in that, The display device includes the backlight module according to any one of claims 1-17.

Images