Backlight module and display device

Abstract

The present invention relates to a backlight module, which includes a backlight source and an optical structure disposed on the light-emitting side of the backlight source. The optical structure includes a prism layer, the prism layer includes a plurality of prisms extending along a first direction. The prism includes a bottom surface, and a ridge peak disposed on a side opposite to the bottom surface. The ridge peak includes a first connection surface and a second connection surface located on both sides of the vertex of the ridge peak. The connection line between one end of the first connection surface far from the vertex of the ridge peak and the vertex of the ridge peak is a first connection line, and the connection line between one end of the second connection surface far from the vertex of the ridge peak and the vertex of the ridge peak is a second connection line. The included angle between the first connection line and the second connection line is an obtuse angle.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid crystal product manufacturing, and particularly to a backlight module and a display device. Background Art

[0002] With the wide application of LCD display modules in fields such as education and smart home, while pursuing visual enjoyment, the demand for "eye protection" is increasing day by day. Research shows that brightness changes can cause eye fatigue. When the brightness is low, it is easy to cause excessive adjustment of rod cells, and the ciliary muscle remains in a tense state; when the brightness is too high, it is easy to cause the pupil sphincter to be in a contracted state, the pupil to shrink, and visual fatigue to occur; for a conventional LCD display screen, as the viewing angle changes, the brightness decays too fast (the brightness decays by 50% when the central angle deviates by 20 degrees), which is easy to cause regulatory visual fatigue of the human eye; maintaining a fixed posture (constant viewing angle) is easy to cause cervical diseases and myopia.

[0003] The full width at half maximum (FWHM) viewing angle Spec refers to the azimuth angle corresponding to when the brightness decays by half. The larger the viewing angle, the slower the brightness decay, which is more beneficial to eyesight protection. Currently, a conventional 4-films (a lower diffusion sheet, a lower prism sheet, an upper prism sheet, and an upper diffusion sheet stacked in sequence along the light-emitting direction of the backlight source) architecture BLU MDL (a backlight module using a stacked structure) can only achieve a half-width FWHM viewing angle of 25° in all directions. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a backlight module and a display device to solve the problem that the brightness of the backlight module decays too fast as the viewing angle increases.

[0005] To achieve the above object, the technical solution adopted in the embodiment of the present invention is: a backlight module, including a backlight source and an optical structure disposed on the light-emitting side of the backlight source, the optical structure including a prism layer, the prism layer including a plurality of prisms extending along a first direction, each prism including a bottom surface, and a ridge peak disposed on a side opposite to the bottom surface, the ridge peak including a first connection surface and a second connection surface located on both sides of the vertex of the ridge peak. In a cross-section of the prism along a direction perpendicular to the bottom surface, the line connecting one end of the first connection surface away from the vertex of the ridge peak and the vertex of the ridge peak is a first connection line, and the line connecting one end of the second connection surface away from the vertex of the ridge peak and the vertex of the ridge peak is a second connection line, and the included angle between the first connection line and the second connection line is an obtuse angle.

[0006] Optionally, the optical structure further includes a first diffusion layer on the backlight side of the prism layer, and / or a second diffusion layer on the light-emitting side of the prism layer. The haze of the first diffusion layer is 90%-95%, and the haze of the second diffusion layer is 90%-110% of that of the first diffusion layer.

[0007] Optionally, the optical structure further includes a brightness enhancement film located on the light-emitting side of the prism layer.

[0008] Optionally, along the direction away from the backlight source, the optical structure includes a first diffusion layer, a prism layer, a second diffusion layer, and a brightness enhancement film stacked in sequence.

[0009] Optionally, in a plane parallel to the first direction and parallel to the light-emitting direction of the backlight source, the brightness of the first viewing angle is half of the central brightness of the backlight module, the first viewing angle is greater than or equal to |45°|, and / or

[0010] In a plane perpendicular to the first direction and parallel to the light-emitting direction of the backlight source, the brightness of the second viewing angle is half of the central brightness of the backlight module, and the second viewing angle is greater than or equal to |40°|.

[0011] Optionally, the first connection surface is a curved surface, and the radius of curvature of the curved surface is 5 - 9 μm.

[0012] Optionally, the first connection surface is a plane, and the angle between the first connection surface and the second connection surface is 110° - 130°.

[0013] Optionally, the prism includes a first inclined surface and a second inclined surface located between the bottom surface and the ridge peak. The first inclined surface and the first connection surface are on the same side of the vertex of the ridge peak, and the angle between the first inclined surface and the first connection surface is an obtuse angle. The second inclined surface and the second connection surface are on the same side of the vertex of the ridge peak, and the angle between the second inclined surface and the second connection surface is an obtuse angle;

[0014] The angle formed by the extension and intersection of the first inclined surface and the second inclined surface is 80 - 100 degrees.

[0015] Optionally, the distance between adjacent two ridge peaks is 20 - 48 μm.

[0016] Optionally, the backlight source includes a light source, and the light source is a blue LED with a peak wavelength ≥ 460 μm.

[0017] Optionally, along a second direction perpendicular to the first direction, the prism layer includes a plurality of prism units arranged periodically, and the heights of the plurality of prisms in each prism unit in the light-emitting direction of the backlight source are different.

[0018] Optionally, in a direction perpendicular to the first direction, the vertex of the ridge peak of each prism is offset toward the side close to the first connection surface, or the vertex of the ridge peak of each prism is offset toward the side close to the second connection surface.

[0019] Optionally, in a direction perpendicular to the first direction, the prism layer has a first center line, the vertex of the ridge peak of each prism is offset toward the side close to the first center line, and the farther away from the first center line, the smaller the offset of the vertex of the ridge peak.

[0020] Optionally, in a direction perpendicular to the first direction, the heights of the multiple prisms gradually decrease from the middle to both sides in the direction parallel to the light-emitting direction of the backlight source.

[0021] An embodiment of the present invention further provides a display device, including the above-mentioned backlight module and a display panel, and the display panel is disposed on the light-emitting side of the backlight module.

[0022] Optionally, the display device further includes a polarizer on the backlight side of the display panel;

[0023] Along the direction away from the backlight source, the optical structure includes a first diffusion layer, a prism layer, and a second diffusion layer stacked in sequence;

[0024] A brightness enhancement film is integrally provided on the polarizer.

[0025] Optionally, along the direction away from the display panel, the polarizer includes a polarizing film layer and a base layer stacked in sequence, and the brightness enhancement film is disposed between the polarizing film layer and the base layer, or the brightness enhancement film is disposed on the side of the polarizing film layer away from the base layer.

[0026] The beneficial effects of the present invention are as follows: The optical structure in the embodiment of the present invention includes a prism layer. The prism layer includes multiple prisms extending along a first direction. Each prism includes a bottom surface and a ridge peak disposed on the side opposite to the bottom surface. The ridge peak includes a first connection surface and a second connection surface on both sides of the vertex of the ridge peak. The connection line between one end of the first connection surface away from the vertex of the ridge peak and the vertex of the ridge peak is a first connection line, and the connection line between one end of the second connection surface away from the vertex of the ridge peak and the vertex of the ridge peak is a second connection line. The included angle between the first connection line and the second connection line is an obtuse angle, which increases the viewing angle when the brightness attenuation is general, and at the same time keeps the brightness at the center point at a relatively high level. Description of the Drawings

[0027] Figure 1 It represents a schematic diagram of the light-emitting orientation of the backlight module in the embodiment of the present invention;

[0028] Figure 2 Schematic diagram of the light-emitting viewing angle of the backlight module in the embodiment of the present invention

[0029] Figure 3 Schematic diagram of the prism structure in the embodiment of the present invention Figure 1 ;

[0030] Figure 4 Schematic diagram of the prism structure in the embodiment of the present invention Figure 2 ;

[0031] Figure 5 Schematic diagram of the structure of the prism layer in the embodiment of the present invention Figure 1

[0032] Figure 6 Schematic diagram of the structure of the prism layer in the embodiment of the present invention Figure 2 ;

[0033] Figure 7 Schematic diagram of a partial structure of the prism layer in the embodiment of the present invention;

[0034] Figure 8 Schematic diagram of the light field distribution with a peak radius of zero of the prism in the embodiment of the present invention;

[0035] Figure 9 Schematic diagram of the light field distribution with a peak radius of 1 of the prism in the embodiment of the present invention;

[0036] Figure 10 Schematic diagram of the light field distribution with a peak radius of 2 of the prism in the embodiment of the present invention;

[0037] Figure 11 Schematic diagram of the light efficiency of the prism in the embodiment of the present invention;

[0038] Figure 12 Schematic diagram of the azimuth viewing angle trend in the embodiment of the present invention Figure 1 ;

[0039] Figure 13 Schematic diagram of the light field distribution using a diffusion layer in the embodiment of the present invention;

[0040] Figure 14 Schematic diagram of the light field distribution using a single-layer prism layer in the embodiment of the present invention Figure 1 ;

[0041] Figure 15 Schematic diagram of the light field distribution using a single-layer prism layer in the embodiment of the present invention Figure 2 ;

[0042] Figure 16 Schematic diagram of the structure of the prism layer in the embodiment of the present invention Figure 3 ;

[0043] Figure 17 Schematic diagram of the prism layer in the embodiment of the present invention Figure 4 ;

[0044] Figure 18 Schematic diagram of the prism layer in the embodiment of the present invention Figure 5 ;

[0045] Figure 19 Indicating the azimuth viewing angle trend in the embodiment of the present invention Figure 2 ;

[0046] Figure 20 Schematic diagram of the structure of the display device in the embodiment of the present invention Detailed implementation manners

[0047] For the purpose of making the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention fall within the scope of protection of the present invention

[0048] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, specific orientation structure and operation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance

[0049] A solution involved in the related art is to adopt a multi-diffusion solution. For example, 3 diffusions replace the conventional 4-films architecture to meet the high-standard half-height width viewing angle requirement. The advantages of this solution are that the half-height width viewing angle ≥ 50° can be achieved in all directions, but the brightness loss will exceed 30%, resulting in too low brightness or too high power consumption at the same brightness

[0050] Referring to Figures 1 - 7 , in view of the above problems, this embodiment provides a backlight module, including a backlight source and an optical structure disposed on the light-emitting side of the backlight source. The optical structure includes a prism layer, and the prism layer includes a plurality of along the first direction (referring to Figure 5A prism 1 extending in the X direction, the prism 1 includes a bottom surface 11, and a ridge peak disposed on the side opposite to the bottom surface 11. The ridge peak includes a first connecting surface 14 and a second connecting surface 15 on both sides of the vertex of the ridge peak. In a cross-section of the prism along a direction perpendicular to the bottom surface of the prism, the line connecting the end of the first connecting surface 14 away from the vertex of the ridge peak and the vertex of the ridge peak is the first connecting line 100, and the line connecting the end of the second connecting surface 15 away from the vertex of the ridge peak and the vertex of the ridge peak is the second connecting line 200. The included angle a between the first connecting line 100 and the second connecting line 200 is an obtuse angle.

[0051] It should be noted that the vertex of the above ridge peak, the end of the first connecting surface 14 away from the vertex of the ridge peak, and the end of the second connecting surface 15 away from the vertex of the ridge peak are coplanar, that is, they are all located in a cross-section perpendicular to the bottom surface of the prism.

[0052] In this embodiment, a third connecting surface is further included between the first connecting surface and the bottom surface. The third connecting surface can be extended in one direction or formed by connecting connecting surfaces extended in multiple directions. Similarly, a fourth connecting surface is further included between the second connecting surface and the bottom surface. The fourth connecting surface can be extended in one direction or formed by connecting connecting surfaces extended in multiple directions.

[0053] Figure 1 It is an azimuth diagram of the backlight module. Among them, the first plane formed by azimuth angles of 0 degrees and 180 degrees is parallel to the extension direction of the prism, that is, the first direction, and perpendicular to the light-emitting direction of the backlight module. The included angle between the second plane formed by azimuth angles of 45 degrees and 225 degrees and the first plane is 45 degrees. The included angle between the third plane formed by azimuth angles of 90 degrees and 270 degrees and the first plane is 90 degrees. The included angle between the fourth plane formed by azimuth angles of 135 degrees and 315 degrees and the first plane is 135 degrees. Figure 2 It is a viewing angle definition diagram. Figure 2 It shows the θ angles (θ1 and θ2) corresponding to half of the brightness of the center point's positive viewing angle in the first plane.

[0054] The prism can achieve viewing angle convergence and thus improve the positive viewing angle brightness through the principles of total reflection and refraction. In this embodiment, the prism structure is improved, that is, the line connecting the end of the first connecting surface 14 away from the vertex of the ridge peak and the vertex of the ridge peak is the first connecting line, and the line connecting the end of the second connecting surface 15 away from the vertex of the ridge peak and the vertex of the ridge peak is the second connecting line. The included angle between the first connecting line and the second connecting line is an obtuse angle. Refer to Figure 3 and Figure 4 In this embodiment, the ridge peak includes a first connecting surface 14 and a second connecting surface 15, andFigure 3 and Figure 4 In Figure 4 , the dashed lines on the sides of the first connecting surface 14 and the second connecting surface 15 away from the bottom surface 11 represent the ridge peaks of a conventional prism. In comparison, the structure of the ridge peaks is changed, and the distance between adjacent two prisms remains unchanged. For example, it can be the distance between adjacent prisms in the prior art. Figure 5 shows a schematic structural diagram of a prism layer including a plurality of prisms 1. Figure 5 The position marked by the dashed circle in Figure 5 is the ridge peak. Figure 5 shows the distance between adjacent two prisms (which can be the distance between adjacent two ridge peaks or the distance between the center points of adjacent two bottom surfaces), and the prism angle Angle of the ridge peak. By using the prism in this embodiment, the UsefulLight (effective light in the front view direction) is reduced, and the High Angle Light (light with a large viewing angle) is increased to achieve the viewing angle Target, that is, to achieve slow brightness attenuation at a large viewing angle while maintaining a high level of brightness at the center point.

[0055] It should be noted that in this embodiment, optionally, the first connecting surface 14 and the second connecting surface 15 have the same shape. For example, the first connecting surface 14 and the second connecting surface 15 are both curved surfaces, or the first connecting surface 14 and the second connecting surface 15 are both flat surfaces. Optionally, the first connecting surface 14 and the second connecting surface 15 are symmetrically arranged, which can not only achieve uniform divergence of light but also be simpler in the process preparation.

[0056] Exemplarily in this embodiment, the first connecting surface 14 is a curved surface, and the radius of curvature of the curved surface is 5 - 9 um.

[0057] Exemplarily in this embodiment, the first connecting surface 14 is a flat surface, and the included angle between the first connecting surface 14 and the second connecting surface 15 is 110° - 130°.

[0058] Taking the first connecting surface 14 and the second connecting surface 15 both being curved surfaces as an example, the optical structure including the prism of this embodiment will be specifically introduced below.

[0059] Figure 7 is a schematic diagram of a partial structure of the prism layer. Figure 7 In Figure 7 , the first connecting surface 14 and the second connecting surface 15 are both curved surfaces. At this time, the peak radius of the ridge peak is R. Figure 8 shows a schematic diagram of the light field distribution when R = 0. The brightness at the center point is high, reaching 613 nit, but the full width at half maximum viewing angle is relatively small, only about 20 degrees. Figure 9 shows a schematic diagram of the light field distribution when R = 1 um. The peak radius increases, the brightness at the center point decreases to 583 nit, and the full width at half maximum viewing angle increases to about 30.Figure 10 The light field distribution diagram when R=2um is shown. The peak radius is further increased, the brightness of the center point is 557nit, and the half-height width viewing angle is increased to about 35 degrees. Figure 11 This is a schematic diagram of the light effect of a prism. Figure 8 , Figure 9 and Figure 10 , as the peak radius R of the prism increases, the brightness of the center point decreases and the azimuth viewing angle increases; the reason is that the prism peak changes from a right angle (R=0) to an R angle (R≠0), and as R increases, the Useful Light will gradually decrease, but at the same time the High Angle Light will increase, so it can sacrifice brightness in exchange for an improved viewing angle. However, in this embodiment, what is changed is the peak radius of the prism peak, while the width of the bottom surface 11 in the direction perpendicular to the first direction is not changed (generally 20-48mm), so while expanding the viewing angle, the brightness that attenuates as the viewing angle increases is reduced, that is, the center point position is guaranteed to have a higher brightness.

[0060] In this embodiment, the prism includes a first inclined surface 12 and a second inclined surface 13 located between the bottom surface and the prism peak, the first inclined surface 12 and the first connecting surface 14 are located on the same side of the vertex of the prism peak, and the second inclined surface 13 and the second connecting surface 15 are located on the same side of the vertex of the prism peak;

[0061] The included angle formed by the extension and intersection of the first inclined surface 12 and the second inclined surface 13 is 80-100 degrees.

[0062] refer to Figure 3 and Figure 4 In this embodiment, the angle b formed by the extension and intersection of the first inclined surface 12 and the second inclined surface 13 is smaller than the angle a between the first connecting line 100 and the second connecting line 200 (when the first connecting surface 14 and the second connecting surface 15 are planes, the first connecting surface 14 coincides with the first connecting line 100, and the second connecting surface 14 coincides with the second connecting line 200), which effectively achieves the increase of viewing angle while ensuring brightness.

[0063] In this embodiment, one side of the prism is formed by connecting the first inclined surface 12 and the first connecting surface 14, and the other side of the prism is formed by connecting the second inclined surface 13 and the second connecting surface 15. Compared with the structure in which the side of the prism is formed by one surface along one extension direction, Figure 3 and Figure 4As shown by the dashed line in , the angle a is greater than the angle b, which is beneficial to increasing the viewing angle. If one side of the prism adopts a surface extending in one direction, when forming the angle a, the width of the bottom surface 11 in the direction perpendicular to the extending direction of the prism needs to be increased, then the arrangement density of multiple prisms in the prism layer decreases. Sparse prism arrangement will reduce the brightness of the light emitted by the backlight module.

[0064] In this embodiment, one side of the prism is formed by connecting the first inclined surface 12 and the first connecting surface 14, and the other side of the prism is formed by connecting the second inclined surface 13 and the second connecting surface 15. That is, compared with a conventional prism, only the prism peak of the prism is improved in this embodiment, and the bottom surface of the prism is not changed. The inclination angle of the side of the prism except for the part of the prism peak also remains unchanged. If the width of the bottom surface of the prism in the direction perpendicular to its extending direction remains unchanged, the prism peak remains unchanged, and only the included angle between the side of the prism and the bottom surface is reduced, that is, the inclination angle of the side of the prism is changed, so that the included angle between the two sides of the prism forms an obtuse angle. In this way, the viewing angle can also be increased, but the light output of the collimated light is reduced. In this embodiment, only the structure at the prism peak is changed, so that the included angle between the first connection line and the second connection line is an obtuse angle to increase the viewing angle. Relatively speaking, a small part of the light output in the collimated direction is lost, that is, the viewing angle is increased and the brightness of the center point is ensured.

[0065] Haze is used to characterize the cloudy appearance caused by light scattering inside or on the surface of a transparent or translucent specimen. The definition of haze is the percentage of transmitted light that deviates from the incident ray direction due to forward scattering when the light transmittance passes through the specimen.

[0066] Exemplarily in this embodiment, the optical structure 103 further includes a first diffusion layer 2 on the backlight side of the prism layer and / or a second diffusion layer 3 on the light-emitting side of the prism layer. The haze of the first diffusion layer 2 is 90%-95%, and the haze of the second diffusion layer 3 is 90%-110% of the haze of the first diffusion layer 2. Optionally, the haze of the first diffusion layer 2 is 90%-95%, and the haze of the second diffusion layer 3 is 90%-95%. Optionally, the haze of the first diffusion layer 2 and the second diffusion layer 3 are equal. For example, both are 90%, or 91%, 95%, etc. are not limited. Of course, the haze of the first diffusion layer 2 and the second diffusion layer 3 may also be different, but the haze range is 90%-95%. For example, the haze of the first diffusion layer 2 may be 90% and the haze of the second diffusion layer 3 may be 95%.

[0067] Adding a diffusion layer on at least one side of the prism layer can further increase the viewing angle. The prism layer mainly increases the viewing angle in the first plane, and the setting of the diffusion layer can increase the viewing angle in other directions. For example,Figure 12 shows the perspective trend of the light emitted by the backlight module of the first diffusion layer 2 on the backlight side of the prism layer and the second diffusion layer 3 on the light-emitting side of the prism layer in each azimuth. The line with the reference numeral 20, and the perspective trend of the light emitted by the backlight module of the first diffusion layer 2 on the backlight side of the prism layer. The line with the reference numeral 10. It can be seen that the perspective in the direction perpendicular to the prism peak (the direction perpendicular to the first direction) can be increased by about 6°. Refer to Figure 12 the perspective corresponding to the azimuth angle of 90° or 270° in [reference], at the position indicated by the arrow. Adding a diffusion layer makes the light output more uniform.

[0068] In this embodiment, both the first diffusion layer 2 and the second diffusion layer 3 have a relatively high haze, and the haze difference between the two is small. In this way, the perspective can be effectively increased, that is, it can not only ensure more uniform light output, but also increase the perspective of the plane perpendicular to the prism extension direction (90 - 270 degrees plane).

[0069] Exemplarily in this embodiment, the optical structure 103 further includes a brightness enhancement film 4 located on the light-emitting side of the prism layer.

[0070] Figure 13 shows the schematic diagram of the light field distribution using a diffusion layer. The center point brightness is 500, and the half-width at half-maximum perspective is only about 20 degrees. Figure 8 shows the schematic diagram of the light field using the brightness enhancement film 4. The center point brightness reaches 700, and the half-width at half-maximum perspective is increased. Refer to Figure 13 and Figure 8 , by using the brightness enhancement film 4 instead of the diffusion layer, the brightness of the backlight module in the front view can be increased by about 36%, and the half-width at half-maximum perspective in each azimuth can be increased by about 4.

[0071] Exemplarily in this embodiment, the optical structure 103 includes at least one layer of the prism layer.

[0072] Figure 8 shows the schematic diagram of the light field distribution using two layers of the prism layer. The peak radius R of the prism is 0. Figure 14 and Figure 15 both show the schematic diagram using one layer of the prism layer. Figure 14 In [reference], the prisms in the prism layer extend in a direction perpendicular to the first direction, and the peak radius R of the prism is 0. Figure 15 In [reference], the prisms in the prism layer extend in the first direction, and the peak radius R of the prism is 0.

[0073] Comparing Figure 8 and Figure 14 , or comparing Figure 8 and Figure 15 , it can be obtained that Figure 14 andFigure 15 Compared with Figure 8 , the brightness of the center points all decreases. However, Figure 14 and Figure 15 in the backlight modules, the viewing angle in the direction parallel to the extension direction of the prism is increased by about 20° (mainly the brightness increase of light at large viewing angles & the decrease of the center brightness of the backlight module); the viewing angle in the direction perpendicular to the extension direction of the prism is increased by about 5° (mainly the decrease of the center brightness of the backlight module). It can be seen that the setting of a single prism layer is more suitable for the wide viewing angle scheme. Therefore, in a specific embodiment of the present embodiment, the optical structure 103 includes one layer of the prism layer, but it is not limited thereto, and it can also be two layers or multiple layers, which can be specifically set according to actual applications.

[0074] Preferably in this embodiment, along the direction away from the backlight source, the optical structure 103 includes a first diffusion layer 2, a prism layer, a second diffusion layer 3, and a brightness enhancement film 4 stacked in sequence.

[0075] In this embodiment, when the optical structure 103 includes a structure in which a first diffusion layer 2, a prism layer, a second diffusion layer 3, and a brightness enhancement film 4 are stacked in sequence along the direction away from the backlight source, the following objectives can be achieved: in a plane parallel to the first direction and parallel to the light exit direction of the backlight source, the brightness of the first viewing angle is half of the center brightness of the backlight module, and the first viewing angle is greater than or equal to |45°|, and / or

[0076] in a plane perpendicular to the first direction and parallel to the light exit direction of the backlight source, the brightness of the second viewing angle is half of the center brightness of the backlight module, and the second viewing angle is greater than or equal to |40°|.

[0077] It should be noted that the above |45°| and |40°| are defined with the viewing angle of the center point being 0. Refer to Figure 2 , when measuring the viewing angle, if the center point is 0 degrees, the position with an azimuth angle of 0 degrees in the measurement plane is set as +90 degrees, and the position with an azimuth angle of 180 degrees is set as -90 degrees, then θ1 is positive and θ2 is negative.

[0078]

[0079] Refer to the above table and Figure 19 , Figure 19In the figure, the optical structure 103 adopts the 6 structures 1#-6# in the table, and the azimuth viewing angle trend of the outgoing light of the backlight module is shown from bottom to top. Different optical structures 103 are tested. In some specific embodiments, in the above 6 structures, the brightness enhancement film 4 adopts DBEF5, the incremental effect is greater than 30%, the diffusion layer adopts B75VU-S, the haze is 93.79%, the transmittance is 85.83%, the prism is 4.20TJ, and the peak radius R is 0μm, 2μm, 5μm respectively. m, 7μm, 9μm, and tested without a prism layer, and the optical structure 103 is composed of three overlapping diffusion layers and a brightness enhancement film 4 located in the light-emitting layer of the three diffusion layers. From the comparison of the central normal viewing angle brightness of the structures in 6 in the above table, it can be seen that the prism adopts an R-type prism (that is, the angle between the first connecting line and the second connecting line is an obtuse angle). As the peak radius increases, the central normal viewing angle brightness decreases. Compared with the sixth structure, the central normal viewing angle brightness without a prism is only 366nit, and the brightness attenuation is too large.

[0080] Refer to the above table and Figure 19 , compared with the peak radius R of the prism being 0, when the peak radius R of the prism is 5μm, the central brightness of the backlight module decreases by 5.37%, and the brightness loss is within 10%; when the peak radius R of the prism is 7μm, the central brightness of the backlight module decreases by 7.68%, and the brightness loss is within 10%. In the related art, the prism layer is removed, and the optical structure 103 only uses 3 diffusion layers. Such a structure can achieve a half-height width viewing angle ≥ 50° in all directions, which greatly exceeds customer expectations, but the brightness loss will exceed 30%, which will cause the brightness to be too low or the power consumption to be too high at the same brightness; in contrast, the optical structure 103 in this embodiment adopts a structure setting along the direction away from the backlight source, and the optical structure 103 includes a first diffusion layer 2, a prism layer, a second diffusion layer 3 and a brightness enhancement film 4 stacked in sequence. The viewing angles in all directions meet customer needs, all of which are greater than or equal to 40 degrees, and the central brightness loss is within 10%, reducing power consumption.

[0081] In this exemplary embodiment, the backlight source includes a light source, and the light source is a blue light LED with a peak wavelength ≥ 460 um.

[0082] Low blue light LED reduces blue light damage and further reduces damage to human vision. The CG (cover plate) that has undergone AG treatment (atomization treatment) reduces surface glare and achieves "paper-like" technology.

[0083] In this embodiment, for example, the distance between two adjacent ridge peaks is 20-48 μm.

[0084] The distance between two adjacent ones of the ridge peaks is 20-48 μm. That is to say, in the direction perpendicular to the extending direction of the prism, the distance between the centers of the bottom surfaces of two adjacent prisms is 20-48 μm. The setting of this distance determines the density of the prism distribution. While the prism plays a role in expanding the viewing angle, it also has the effect of converging light. The greater the density of the prism distribution, the higher the brightness of the light. The smaller the density of the prism distribution, the greater the loss of light brightness. Therefore, in order to ensure the brightness of the light emitted by the backlight module, in one implementation manner of this embodiment, the distance between two adjacent ones of the ridge peaks is 20-48 μm, but it is not limited thereto.

[0085] Reference Figure 6 , in this embodiment, exemplarily, along a second direction perpendicular to the first direction, the prism layer includes a plurality of prism units 10 arranged periodically, and the heights of the plurality of prisms in each prism unit 10 in the light-emitting direction of the backlight source ( Figure 6 the Z direction therein) are different.

[0086] If the heights of the plurality of prisms in the light-emitting direction of the backlight source ( Figure 5 the Z direction therein) are the same, then after assembly, each prism is in contact with the film layer structure on the light-emitting side of the prism layer. In this embodiment, the heights of the plurality of prisms in each prism unit 10 in the light-emitting direction of the backlight source ( Figure 5 the Z direction therein) are different. That is, the prisms with lower heights in the light-emitting direction of the backlight source ( Figure 5 the Z direction therein) are not in contact with the film layer structure on the light-emitting side of the prism layer, reducing the contact area between the prism layer and the film layer structure on the light-emitting side of the prism layer and avoiding abnormal display.

[0087] Each of the plurality of prisms in each prism unit 10 may have only one first prism, and the height of the first prism is higher than that of the other prisms other than the first prism. The first prism may be located at the middle position of the corresponding prism unit 10, or near the edge position of other prism units 10. If the prism unit 10 is located at the edge of the prism layer, the first prism may also be located near the edge of the prism layer.

[0088] Each of the plurality of prisms in each prism unit 10 may have at least two of the first prisms, and the at least two first prisms may be arranged adjacent to each other or at intervals.

[0089] It should be noted that the number of the first prisms is less than the number of prisms in the corresponding prism unit. And in order to avoid abnormal display, in some implementation manners, the number of the first prisms is less than half of the number of prisms in the prism unit, but it is not limited thereto.

[0090] Exemplarily, in the embodiment, in a direction perpendicular to the first direction, the vertex of the ridge peak of each prism is offset toward the side close to the first connection surface 14, or the vertex of the ridge peak of each prism is offset toward the side close to the second connection surface 15.

[0091] By adopting the above technical solution, in a direction perpendicular to the first direction (i.e., in a direction perpendicular to the extending direction of the prism), the viewing angle on the side of the backlight module close to the first connection surface 14 is larger than the viewing angle on the side of the backlight module away from the first connection surface 14, that is, in a direction perpendicular to the first direction, the viewing angle is biased toward the side of the backlight module close to the first connection surface 14. Or, the viewing angle on the side of the backlight module close to the second connection surface 15 is larger than the viewing angle on the side of the backlight module away from the second connection surface 15, that is, in a direction perpendicular to the first direction, the viewing angle is biased toward the side of the backlight module close to the second connection surface 15. Figure 17 In the embodiment, the orthographic projection of the vertex of the ridge peak of each prism on the bottom surface 11 is located on the right side of the center of the bottom surface (i.e., the center line in a direction perpendicular to the extending direction of the prism), that is to say, the vertex of the ridge peak of each prism is offset toward the side close to the second connection surface 15. The extending direction of the prism is generally the long side direction of the display screen. By adopting the above technical solution, the viewing angle on either side of the two sides in the short side direction of the display screen can be made larger, meeting the special requirements of customers.

[0092] Reference Figure 17 In the embodiment, exemplarily, in a direction perpendicular to the first direction, the prism layer has a first center line 101, and the vertex of the ridge peak of each prism is offset toward the side close to the first center line 101, and the farther the distance from the first center line 101, the smaller the offset amount of the vertex of the ridge peak, ensuring the brightness of the light with a large viewing angle.

[0093] The vertex of the ridge peak of each prism is offset toward the side close to the first center line 101. The side of the vertex close to the first center line converges light stronger, while the side of the vertex away from the first center line increases the viewing angle amplitude more. By adopting the above technical solution, the light intensity of the light emitted from the central position of the backlight module can be increased, and the light emitted at a large viewing angle can be increased (the side with a high slope is enhanced, and the viewing angle on the side with a small slope is increased).

[0094] Exemplarily, in the embodiment, in a direction perpendicular to the first direction, the heights of the multiple prisms in a direction parallel to the light-emitting direction of the backlight source gradually decrease from the middle to both sides. Reference Figure 18 .

[0095] By adopting the above technical solution, the brightness of the light emitted from the center position of the backlight module can be increased, and the viewing angle of the light emitted from both sides of the backlight module can be increased.

[0096] Reference Figure 20 , an embodiment of the present invention further provides a display device, including the above-mentioned backlight module and a display panel 101, and the display panel 101 is disposed on the light-emitting side of the backlight module.

[0097] It should be noted that in this embodiment, the light-emitting side is relative to the entire backlight module.

[0098] In this embodiment, the backlight module includes a light guide plate 104 and a light source 108. The light guide plate 104 includes a light-incident surface and a light-emitting surface, and the light source 108 is located on one side of the light-incident surface of the light guide plate 104. In some embodiments, the light-incident surface and the light-emitting surface are adjacent to each other (reference Figure 20 ), that is, the backlight module is a side-entry type backlight. In some embodiments, the light-incident surface and the light-emitting surface are opposite to each other, that is, the backlight module is a direct-lit type backlight.

[0099] The backlight module further includes a back plate 106 surrounding the periphery of the light guide plate 104. A reflective sheet 105 is disposed on the backlight side of the light guide plate 104. The back plate 106 includes a bottom plate, side plates connected to the bottom plate, and a top plate connected to the side plates. A reflective film layer 109 is disposed on one side of the top plate close to the bottom plate to prevent light leakage and increase the light utilization rate.

[0100] Exemplarily in this embodiment, the display device further includes a polarizer 102 on the backlight side of the display panel 101;

[0101] Along the direction away from the backlight source, the optical structure 103 includes a first diffusion layer 2, a prism layer 01, and a second diffusion layer 3 stacked in sequence;

[0102] The polarizer 102 is integrally provided with a brightness enhancement film 4.

[0103] When the brightness enhancement film 4 is integrated on the polarizer 102, along the light-emitting direction of the backlight module, the optical structure 103 includes a first diffusion layer 2, a prism layer 01, and a second diffusion layer 3 stacked in sequence. Compared with the optical structure 103 including a first diffusion layer 2, a prism layer 01, a second diffusion layer 3, and a brightness enhancement film 4 stacked in sequence, the positional relationship of the brightness enhancement film 4 is changed, but the effect of increasing the half-height width viewing angle and ensuring the center point brightness is also achieved.

[0104] Exemplarily, in this embodiment, along the direction away from the display panel 101, the polarizer 102 includes a polarizing film layer and a base layer stacked in sequence, the brightness enhancement film 4 is disposed between the polarizing film layer and the base layer, or the brightness enhancement film 4 is disposed on a side of the polarizing film layer away from the base layer.

[0105] Along the direction away from the display panel 101, the polarizing film layer is sequentially stacked with an APF film (reflective polarizing ultra-thin optical film), a first TAC film (triacetyl cellulose film), a PVA film (polyvinyl alcohol film), and a second TAC film. The APF film and the first TAC film are bonded by PSA (pressure-sensitive adhesive). A PSA pressure-sensitive adhesive is disposed on a side of the second TAC film away from the PVA film for bonding with the display panel 101. The brightness enhancement film 4 is located on a side of the APF film away from the first TAC film.

[0106] When the brightness enhancement film 4 is a part of the optical structure, the brightness enhancement film 4 cannot be directly disposed on the surface of the second diffusion layer. To ensure the flatness of the film layer, it needs to be disposed on a substrate and connected to the second diffusion layer through the substrate. In this embodiment, the brightness enhancement film 4 is integrally disposed on the polarizer, omitting the setting of the substrate, which can reduce the overall thickness of the display device.

[0107] The display device may be: a liquid crystal TV, a liquid crystal display, a digital photo frame, a mobile phone, a tablet computer, or any product or component with a display function. Among them, the display device further includes a flexible circuit board, a printed circuit board, and a backplane.

[0108] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principles of the present invention. However, the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims

1. A backlight module, characterized in that, It includes a backlight and an optical structure disposed on the light-emitting side of the backlight. The optical structure includes a prism layer. The prism layer includes a plurality of prisms extending along a first direction. Each prism includes a bottom surface and a ridge peak disposed on the side opposite to the bottom surface. The ridge peak includes a first connection surface and a second connection surface located on both sides of the vertex of the ridge peak. In a cross-section of the prism along a direction perpendicular to the bottom surface, the line connecting the end of the first connection surface far from the vertex of the ridge peak and the vertex of the ridge peak is a first connection line, and the line connecting the end of the second connection surface far from the vertex of the ridge peak and the vertex of the ridge peak is a second connection line. The included angle between the first connection line and the second connection line is an obtuse angle; The distance between adjacent two ridge peaks is 20 - 48 µm; In a direction perpendicular to the first direction, the prism layer has a first center line. The vertex of the ridge peak of each prism is offset toward the side close to the first center line, and the farther the distance from the first center line, the smaller the offset of the vertex of the ridge peak.

2. The backlight module according to claim 1, wherein The optical structure further includes a first diffusion layer on the backlight side of the prism layer and / or a second diffusion layer on the light-emitting side of the prism layer. The haze of the first diffusion layer is 90% - 95%, and the haze of the second diffusion layer is 90% - 110% of that of the first diffusion layer.

3. The backlight module according to claim 1 or 2, characterized in that, The optical structure further includes a brightness enhancement film on the light-emitting side of the prism layer.

4. The backlight module according to claim 2, wherein Along the direction away from the backlight, the optical structure includes a first diffusion layer, a prism layer, a second diffusion layer, and a brightness enhancement film stacked in sequence.

5. The backlight module according to claim 4, characterized in that, In a plane parallel to the first direction and parallel to the light-emitting direction of the backlight, the brightness at a first viewing angle is half of the central brightness of the backlight module, and the first viewing angle is greater than or equal to |45°|, and / or In a plane perpendicular to the first direction and parallel to the light-emitting direction of the backlight, the brightness at a second viewing angle is half of the central brightness of the backlight module, and the second viewing angle is greater than or equal to |40°|.

6. The backlight module according to claim 1, characterized in that The first connection surface is a plane, and the included angle between the first connection surface and the second connection surface is 110° - 130°.

7. The backlight module according to claim 6, wherein The prism includes a first inclined surface and a second inclined surface between the bottom surface and the ridge peak. The first inclined surface and the first connection surface are on the same side of the vertex of the ridge peak, and the included angle between the first inclined surface and the first connection surface is an obtuse angle. The second inclined surface and the second connection surface are on the same side of the vertex of the ridge peak, and the included angle between the second inclined surface and the second connection surface is an obtuse angle; The angle formed by the intersection of the extensions of the first inclined surface and the second inclined surface is 80 - 100 degrees.

8. The backlight module according to claim 1, wherein The backlight includes a light source, and the light source is a blue LED with a peak wavelength ≥ 460 µm.

9. The backlight module according to claim 1, wherein Along a second direction perpendicular to the first direction, the prism layer includes a plurality of prism units arranged periodically, and the heights of the plurality of prisms in each prism unit in the light-emitting direction of the backlight are different.

10. The backlight module according to claim 1, characterized in that, In a direction perpendicular to the first direction, the vertex of the ridge peak of each prism is offset toward the side close to the first connection surface, or the vertex of the ridge peak of each prism is offset toward the side close to the second connection surface.

11. The backlight module according to claim 1, wherein, In a direction perpendicular to the first direction, the height of the plurality of prisms in a direction parallel to the light-emitting direction of the backlight source gradually decreases from the middle to both sides.

12. A display device, characterized in that, Comprising the backlight module and the display panel according to any one of claims 1-11, the display panel is disposed on the light-emitting side of the backlight module.

13. The display device according to claim 12, characterized in that, The display device further includes a polarizer on the backlight side of the display panel; Along the direction away from the backlight source, the optical structure includes a first diffusion layer, a prism layer, and a second diffusion layer stacked in sequence; A brightness enhancement film is integrally provided on the polarizer.

14. The display device according to claim 13, wherein Along the direction away from the display panel, the polarizer includes a polarizing film layer and a base layer stacked in sequence, the brightness enhancement film is disposed between the polarizing film layer and the base layer, or the brightness enhancement film is disposed on a side of the polarizing film layer away from the base layer.

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