Backlight module and display device

Abstract

The backlight module comprises a first light guide plate, a first light source, a second light guide plate, a second light source and a first prismatic lens. The first light source and the second light source are respectively arranged on one side of the first light guide plate and the second light guide plate. The second light guide plate is arranged on one side of the first light-emitting surface of the first light guide plate. The first prismatic lens is arranged on one side of the second light-emitting surface of the second light guide plate. A plurality of first prism structures of the first prism sheet are arranged on the substrate surface, facing the second light emitting surface, of the first substrate and are arranged at intervals according to the interval width in the normal direction of the second light incident surface. Each first prism structure has a first structure width in the normal direction of the second light incident surface. The ratio of the interval width to the first structure width is less than 2. The backlight module provided by the utility model is relatively uniform in emergent light distribution in a sharing mode. The utility model also provides a display device comprising the backlight module. The display device provided by the utility model has better uniformity of display brightness in the sharing mode.

Description

Technical Field

[0001] The utility model relates to a backlight module and a display device, and in particular to a backlight module and a display device provided with a prism sheet. Background Art

[0002] Generally speaking, in order to allow multiple viewers to watch together, display devices usually have a wide viewing angle display effect. However, in some situations or occasions, such as browsing private web pages, confidential information or entering passwords in public, the wide viewing angle display effect can easily make the screen image be peeped by others, resulting in the leakage of confidential information. In order to achieve the anti-peeping effect, the general practice is to place a light control film (LCF) in front of the display panel to filter out large-angle light.

[0003] If the convenience of operation is taken into consideration, another approach is to add an electrically controlled diffuser to achieve an electrically switchable anti-peeping display. Another approach is to use an additional electrically controlled liquid crystal box and a polarizer to electrically filter the light on the anti-peeping axis. However, the additional electrically controlled liquid crystal box cannot completely filter out the display brightness at the anti-peeping viewing angle, which limits the anti-peeping effect of the display device. Therefore, how to develop a display device with extremely convenient viewing angle switching and excellent anti-peeping effect has become an important issue for relevant manufacturers.

[0004] The "background technology" section is only used to help understand the content of the utility model, so the content disclosed in the "background technology" section may contain some known technologies that are not known to technicians in the relevant technical field. The content disclosed in the "background technology" section does not mean that the content or the problems to be solved by one or more embodiments of the utility model have been known or recognized by technicians in the relevant technical field before the application of the utility model. Utility Model Content

[0005] The utility model provides a backlight module, the light distribution of which is more uniform in a sharing mode.

[0006] The utility model provides a display device, which has better uniformity of display brightness in a sharing mode.

[0007] Other purposes and advantages of the present invention can be further understood from the technical features disclosed in the present invention.

[0008] To achieve one or part or all of the above purposes or other purposes, one embodiment of the utility model provides a backlight module. The backlight module includes a first light guide plate, a first light source, a second light guide plate, a second light source and a first prism sheet. The first light guide plate has a first light incident surface and a first light exit surface connected to each other. The first light source is arranged on one side of the first light incident surface of the first light guide plate. The second light guide plate is arranged on one side of the first light exit surface of the first light guide plate and overlaps the first light exit surface. The second light guide plate has a second light incident surface and a second light exit surface connected to each other. The first light incident surface intersects with the second light incident surface. The second light source is arranged on one side of the second light incident surface of the second light guide plate. The first prism sheet is arranged on one side of the second light exit surface of the second light guide plate and includes a first substrate and a plurality of first prism structures. The first substrate has a substrate surface facing the second light exit surface. A plurality of first prism structures are arranged on the substrate surface and are arranged at intervals along the normal direction of the second light incident surface. In the normal direction of the second light incident surface, each first prism structure has a first structure width. There is an interval width between any two adjacent ones of these first prism structures. The ratio of the spacing width to the first structure width is less than 2.

[0009] To achieve one or part or all of the above purposes or other purposes, one embodiment of the utility model provides a display device. The display device includes a backlight module and a display panel. The backlight module includes a first light guide plate, a first light source, a second light guide plate, a second light source and a first prism sheet. The first light guide plate has a first light incident surface and a first light exit surface connected to each other. The first light source is arranged on one side of the first light incident surface of the first light guide plate. The second light guide plate is arranged on one side of the first light exit surface of the first light guide plate and overlaps the first light exit surface. The second light guide plate has a second light incident surface and a second light exit surface connected to each other. The first light incident surface intersects with the second light incident surface. The second light source is arranged on one side of the second light incident surface of the second light guide plate. The first prism sheet is arranged on one side of the second light exit surface of the second light guide plate and includes a first substrate and a plurality of first prism structures. The first substrate has a substrate surface facing the second light exit surface. A plurality of first prism structures are arranged on the substrate surface and are arranged at intervals along the normal direction of the second light incident surface. In the normal direction of the second light incident surface, each first prism structure has a first structure width. There is a spacing width between any two adjacent first prism structures, and the ratio of the spacing width to the first structure width is less than 2. The display panel is disposed on one side of the second light emitting surface of the second light guide plate and overlaps the second light emitting surface.

[0010] Based on the above, in a backlight module and a display device of one embodiment of the utility model, a second light guide plate is provided on one side of the first light emitting surface of the first light guide plate. The second light emitting surface of the second light guide plate is arranged opposite to the first light guide plate, and is provided with a first prism sheet. The first substrate of the first prism sheet is provided with a plurality of first prism structures on the substrate surface facing the second light guide plate. These first prism structures are arranged at intervals according to the spacing width along the normal direction of the second light incident surface of the second light guide plate. Through the provision of these first prism structures, the light collection property of the display device in the anti-peeping axis direction when operating in the anti-peeping mode can be effectively improved. By designing the ratio of the aforementioned spacing width to the structural width of the first prism structure in the normal direction of the second light incident surface to be less than 2, the light output distribution of the backlight module in the anti-peeping axis direction can be more uniform and continuous when the display device is operated in the sharing mode, which helps to improve the visual quality of the display device at various viewing angles.

[0011] In order to make the above features and advantages of the present invention more obvious and easy to understand, embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a side view schematic diagram of a display device according to a first embodiment of the utility model.

[0013] Figure 2 yes Figure 1 A three-dimensional schematic diagram of a backlight module.

[0014] Figure 3A yes Figure 2 A cross-sectional schematic diagram of a first prism sheet.

[0015] Figure 3B yes Figure 3A A cross-sectional schematic diagram of another modified embodiment of the first prism sheet.

[0016] Figure 4 4 is a schematic cross-sectional view of a first prism sheet of a comparative example.

[0017] Figure 5A and Figure 5B Yes Figure 4 Light distribution diagram of the backlight module of the first prism sheet in the comparative example when operating in the anti-peeping mode and the sharing mode respectively.

[0018] Fig. 6A and Figure 6B yes Figure 2 The light distribution diagram of the backlight module when operating in anti-peep mode and sharing mode respectively.

[0019] Figure 7 4 is a cross-sectional schematic diagram of a first prism sheet according to a second embodiment of the present utility model.

[0020] Figure 8 It is a cross-sectional schematic diagram of a first prism sheet according to a third embodiment of the utility model.

[0021] Fig. 9 It is a cross-sectional schematic diagram of a first prism sheet according to a fourth embodiment of the utility model.

[0022] Fig.10 It is a cross-sectional schematic diagram of a first prism sheet according to a fifth embodiment of the utility model.

[0023] Description of reference numerals:

[0024] 10: Display device

[0025] 100: Backlight module

[0026] 110, 110A, 110B, 110C, 110CE, 110D, 110E: first prism

[0027] 111, 111C: First prism structure

[0028] 112: Second prism structure

[0029] 113: The Third Prism Structure

[0030] 115: First substrate

[0031] 115s 1, 115s 2: Substrate surface

[0032] 118: Diffusion layer

[0033] 120: Second prism

[0034] 121: Prism structure

[0035] 125: Second substrate

[0036] 150: Diffuser

[0037] 200: Display panel

[0038] 300: Electronically controlled viewing angle switcher

[0039] D1, D2, D3: Direction

[0040] ES1: First light emitting surface

[0041] ES2: Second light emitting surface

[0042] h1: first height

[0043] h2: Second height

[0044] h3: third height

[0045] IS1: First light incident surface

[0046] IS2: Second light incident surface

[0047] L1, L2: light

[0048] LGP1: First light guide plate

[0049] LGP2: Second light guide plate

[0050] LS1: First Light Source

[0051] LS2: Second light source

[0052] OS1, OS2: Optical surface

[0053] W1: First structure width

[0054] W2: Second structure width

[0055] W3: Third structure width

[0056] Wf: plane width

[0057] Ws: interval width

[0058] β: Vertex angle

[0059] θ, θ1, θ2: angle. DETAILED DESCRIPTION

[0060] The above-mentioned and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the accompanying drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front or back, etc., are only the directions with reference to the accompanying drawings. Therefore, the directional terms used are used to illustrate and not to limit the present invention.

[0061] Figure 1 It is a side view schematic diagram of a display device according to a first embodiment of the utility model. Figure 2 yes Figure 1 A three-dimensional schematic diagram of a backlight module. Figure 3A yes Figure 2 A cross-sectional schematic diagram of a first prism sheet. Figure 3B yes Figure 3A A cross-sectional schematic diagram of another modified embodiment of the first prism sheet. Figure 4 4 is a schematic cross-sectional view of a first prism sheet of a comparative example.

[0062] Figure 5A and Figure 5B Yes Figure 4 Light distribution diagram of the backlight module of the first prism sheet in the comparative example when operating in the anti-peeping mode and the sharing mode respectively. Fig. 6Aand Figure 6B yes Figure 2 The light distribution diagram of the backlight module when operating in anti-peep mode and sharing mode respectively.

[0063] Please refer to Figure 1 and Figure 2 , the display device 10 includes a backlight module 100 and a display panel 200. In detail, the backlight module 100 includes a first light guide plate LGP1, a first light source LS1, a second light guide plate LGP2, a second light source LS2 and a first prism sheet 110. The first light guide plate LGP1 has a first light incident surface IS1 and a first light emitting surface ES1 connected to each other. The first light source LS1 is disposed on one side of the first light incident surface IS1 of the first light guide plate LGP1. The second light guide plate LGP2 is disposed on one side of the first light emitting surface ES1 of the first light guide plate LGP1, and overlaps with the first light emitting surface ES1 along a direction D3 (e.g., a direction parallel to the normal line of the first light emitting surface ES1).

[0064] The second light guide plate LGP2 has a second light incident surface IS2 and a second light emitting surface ES2 connected to each other. The second light source LS2 is arranged on one side of the second light incident surface IS2 of the second light guide plate LGP2. The first prism sheet 110 is arranged on one side of the second light emitting surface ES2 of the second light guide plate LGP2 and overlaps with the second light emitting surface ES2. Among them, the second light emitting surface ES2 of the second light guide plate LGP2 faces away from the first light guide plate LGP1. In other words, the second light guide plate LGP2 is arranged between the first light guide plate LGP1 and the first prism sheet 110. The display panel 200 is a non-self-luminous display panel, for example, a liquid crystal display panel. The display panel 200 is arranged on one side of the second light emitting surface ES2 of the second light guide plate LGP2 and overlaps with the second light emitting surface ES2.

[0065] It is particularly noted that the first light incident surface IS1 of the first light guide plate LGP1 is not parallel to the second light incident surface IS2 of the second light guide plate LGP2, for example, the angle between the first light incident surface IS1 and the second light incident surface IS2 is greater than or equal to 75 degrees and less than or equal to 105 degrees. For example, in the present embodiment, the normal direction of the first light incident surface IS1 (for example, direction D2) may be perpendicular to the normal direction of the second light incident surface IS2 (for example, direction D1).

[0066] First, it should be noted that in this embodiment, when the first light source LS1 is disabled and the second light source LS2 is enabled, the display device 10 is operated in the anti-peeping mode. At this time, the anti-peeping axis of the display device 10 is parallel to the direction D1. When both the first light source LS1 and the second light source LS2 are enabled, the display device 10 is operated in the sharing mode. In other words, the display device 10 of this embodiment achieves the switching between the sharing mode and the anti-peeping mode by switching different light sources.

[0067] Please refer to Figure 2 and Figure 3A , the first prism film 110 includes a first substrate 115 and a plurality of first prism structures 111. The first substrate 115 has a substrate surface 115s1 facing the second light-emitting surface ES2, and a plurality of first prism structures 111 are provided on the substrate surface 115s1. These first prism structures 111 are arranged at intervals along the normal direction (e.g., direction D1) of the second light-incident surface IS2, and extend in a direction (e.g., direction D2) parallel to the second light-incident surface IS2. That is to say, in the present embodiment, the configuration of the first prism structure 111 may be a strip, but is not limited thereto. In other embodiments, the configuration of the first prism structure may also be a column, and a plurality of first prism structures may be arranged in an array on the substrate surface 115s1 along the directions D1 and D2, respectively, so that the light-emitting distribution of light in multiple directions can be controlled.

[0068] More specifically, in the normal direction of the second light incident surface IS2, there is a spacing width Ws between any two adjacent ones of the multiple first prism structures 111 of this embodiment, and each first prism structure 111 has a first structure width W1. It is particularly noted that the ratio of the spacing width Ws to the first structure width W1 is less than 2. In one embodiment, the ratio of the spacing width Ws to the first structure width W1 is less than 2 and greater than or equal to 0.1. It should be noted first that such a design allows the display device 10 to operate in the sharing mode, and the light output distribution of its backlight module 100 in the anti-peeping axis is more uniform and continuous, which helps to improve the visual quality of the display device 10 at various viewing angles. It is particularly noted that if the ratio of the spacing width Ws to the first structure width W1 is greater than 2, the light collection property of the first prism sheet 110 will be reduced, thereby affecting the anti-peeping effect of the anti-peeping mode.

[0069] Figure 4 A first prism sheet 110CE of a comparative example is shown, wherein a plurality of first prism structures 111C are closely arranged along a direction D1 (i.e., the normal direction of the second light incident surface IS2) (i.e., adjacent first prism structures 111C are connected to each other). Therefore, the light L1 from the second light guide plate LGP2 (the light transmitted to the first prism structure 111C) will be deflected by the first prism structure 111C and directed to a specific area after passing through the first prism sheet 110CE. In other words, in the sharing mode, the light L1 will have a discontinuous light output angle range after passing through the first prism sheet 110CE.

[0070] Specifically, when the backlight module using the first prism sheet 110CE of the aforementioned comparative example operates in the anti-peeping mode (eg Figure 2When the first light source LS1 is disabled and the second light source LS2 is enabled), the configuration of the first prism sheet 110CE can enhance the light collection property after the light passes through, so as to achieve the anti-peeping effect. It is particularly noted that the light collection property of the first prism sheet 110CE will act in a direction perpendicular to the extension direction of the first prism structure 111C (for example, direction D1). Therefore, the anti-peeping axis will be perpendicular to the extension direction of the first prism structure 111C, that is, the anti-peeping axis is parallel to direction D1. Figure 5A As shown, the backlight module operating in the anti-peeping mode has light collection properties in the directions of azimuth angles of 0° and 180° (ie, direction D1 ), but does not have light collection properties in the directions of azimuth angles of 90° and 270°.

[0071] However, when the backlight module using the first prism sheet 110CE of the aforementioned comparative example operates in the sharing mode (eg Figure 2 When both the first light source LS1 and the second light source LS2 are enabled, the closely arranged design of the plurality of first prism structures 111C on the first prism sheet 110CE will cause the light distribution of the backlight module in the directions of azimuth angle 0° and azimuth angle 180° (i.e., direction D1) to be discontinuous (i.e., having an obvious dark area DKA), such as Figure 5B shown.

[0072] In order to solve this problem, in the present embodiment, the arrangement of the plurality of first prism structures 111 on the first prism sheet 110 is arranged in an interval manner (eg Figure 2 and Figure 3A As shown in FIG. 1 , and the ratio of the spacing width Ws to the first structure width W1 is less than 2. Since a portion of the substrate surface 115s1 can be exposed between the first prism structures 111, the portion of the surface will not significantly deflect the other light L2 (the light not transmitted to the first prism structure 111) from the second light guide plate LGP2, so the light L2 after passing through the first prism film 110 will not be limited to a specific light angle range, for example, it can be directed to the corresponding Figure 5B The light emission angle of DKA in the medium-dark area.

[0073] Therefore, when the backlight module 100 of the present embodiment operates in the sharing mode, its light distribution (eg Figure 6B ) in the direction of azimuth angle 0° and azimuth angle 180°, the light distribution of the backlight module of the aforementioned comparative example (as shown in FIG. Figure 5B ) is more continuous and has no obvious dark area DKA, which helps to improve the visual quality of the display device 10 at various viewing angles. When the backlight module 100 of this embodiment operates in the anti-peeping mode, its light distribution (as shown in FIG. Fig. 6A ) and the light distribution of the backlight module of the aforementioned comparative example (as shown in Figure 5A shown).

[0074] Further, in the present embodiment, the cross-sectional profile of the first prism structure 111 on the cross section perpendicular to the substrate surface 115s1 and the second light incident surface IS2 may be a triangle. For example, each first prism structure 111 may have a vertex angle β away from the first substrate 115, and the vertex angle β is preferably 60 degrees. However, the present invention is not limited thereto. In other embodiments, the cross-sectional profile of the first prism structure may also be a trapezoid or a polygon.

[0075] It is particularly noted that, in another embodiment, in order to improve the concealing property, the first prism sheet 110A may further be provided with a diffusion layer 118 (eg, Figure 3B However, the present invention is not limited thereto. In order to improve the visual quality, Figure 3B The diffusion layer 118 in the embodiment can also be replaced by an anti-glare layer, a microstructure layer or other functional film layers.

[0076] It is particularly noted that in order to increase the light uniformity of the backlight module 100 in the sharing mode, the backlight module 100 may further selectively set one or more optical films between the first light guide plate LGP1 and the second light guide plate LGP2. For example, in this embodiment, the second prism sheet 120 and the diffusion sheet 150 may be selectively set between the first light guide plate LGP1 and the second light guide plate LGP2. Figure 2 As shown, but the utility model is not limited to this. In other embodiments, the optical film may be a diffuser, two inverse prism films, or a combination of the above optical films or other suitable optical films. Further, the second prism film 120 may include a second substrate 125 and a plurality of prism structures 121 disposed on the second substrate 125. These prism structures 121 extend in the normal direction of the first light incident surface IS1 (for example, direction D2), and are arranged on the side of the second substrate 125 facing the second light guide plate LGP2 along the direction of the first light incident surface IS1 parallel to the first light guide plate LGP1 (for example, direction D1), but are not limited to this. In the present embodiment, the diffuser 150 may be disposed between the second prism film 120 and the first light guide plate LGP1, but is not limited to this. In other embodiments, the diffuser 150 may be disposed between the second prism film 120 and the second light guide plate LGP2.

[0077] In order to further improve the visual quality in the sharing mode, in another embodiment, the display device may be provided with another diffusion sheet (not shown) on the side of the first prism sheet 110 facing away from the second light guide plate LGP2, and the other diffusion sheet may be an anisotropic diffusion sheet whose scattering characteristics only act in a direction perpendicular to the anti-peeping axis.

[0078] It is particularly noted that in the present embodiment, the display device 10 is provided with a backlight module 100, and by selectively enabling or disabling the first light source LS1, the effect of switching to a sharing mode or an anti-peeping mode can be achieved. In order to further enhance the anti-peeping effect, the display device 10 may also selectively include an electrically controlled viewing angle switcher 300 disposed between the backlight module 100 and the display panel 200. For example, the electrically controlled viewing angle switcher 300 may be an electrically controlled liquid crystal box for reducing the amount of light emitted within a specific viewing angle range (for example, when the light beam passes through the electrically controlled viewing angle switcher 300, the local minimum value of the horizontal light output viewing angle distribution curve falls at 45 degrees and 135 degrees), but is not limited thereto.

[0079] Other embodiments will be listed below to explain the present disclosure in detail, wherein the same components will be marked with the same symbols, and the description of the same technical content will be omitted. For the omitted parts, please refer to the aforementioned embodiments and will not be repeated below.

[0080] Figure 7 is a cross-sectional schematic diagram of a first prism sheet according to the second embodiment of the present utility model. Figure 7 In this embodiment, the first prism sheet 110B and Figure 3A The difference between the first prism sheet 110 and the first prism sheet 110B of the present embodiment is that the first prism sheet 110B of the present embodiment further includes a plurality of second prism structures 112. The second prism structures 112 and the plurality of first prism structures 111 are alternately arranged along the normal direction (eg, direction D1) of the second light incident surface IS2.

[0081] It is particularly noted that, in the normal direction of the substrate surface 115s1 (e.g., direction D3), the first prism structure 111 and the second prism structure 112 have a first height h1 and a second height h2, respectively, and the second height h2 of the second prism structure 112 is smaller than the first height h1 of the first prism structure 111, for example, the ratio of the second height h2 to the first height h1 is less than or equal to 0.9 and greater than or equal to 0.1. On the other hand, in the normal direction of the second light incident surface IS2 (e.g., direction D1), the second prism structure 112 has a second structure width W2, and the second structure width W2 can be less than or equal to the first structure width W1 of the first prism structure 111.

[0082] In this embodiment, the interval width Ws between any two adjacent ones of the plurality of first prism structures 111 may be smaller than the first structure width W1, and the second structure width W2 may be equal to the interval width Ws. Figure 2The optical surface OS1 of the second light guide plate LGP2 is formed by a plurality of optical surfaces, and the angle θ between the optical surface OS1 and the substrate surface 115s1 is greater than or equal to 10 degrees and less than or equal to 45 degrees (for example, the vertex angle of the second prism structure 112 is greater than or equal to 90 degrees and less than or equal to 160 degrees). Accordingly, without affecting the anti-peeping performance, the light distribution of the backlight module using the first prism sheet 110B of this embodiment and operating in the sharing mode in the anti-peeping axis direction can be made more uniform and continuous.

[0083] Figure 8 is a cross-sectional schematic diagram of a first prism sheet according to the third embodiment of the present utility model. Figure 8 In this embodiment, the first prism sheet 110C and Figure 7 The difference between the first prism sheet 110B and the first prism sheet 110C is that the configuration of the multiple prism structures on the prism sheet is different. Specifically, in this embodiment, the second prism structure 112 does not completely occupy the spacing area between any two adjacent ones of the multiple first prism structures 111. In other words, in the first prism sheet 110C of this embodiment, a portion of the substrate surface 115s1 of the first substrate 115 is exposed.

[0084] More specifically, in the normal direction (e.g., direction D1) of the second light incident surface IS2, the portion of the substrate surface 115s1 between any two adjacent first prism structures 111 and not covered by the second prism structure 112 has a plane width Wf. It is particularly noted that the ratio of the plane width Wf to the spacing width Ws may be greater than or equal to 0.5. From another point of view, the spacing width Ws between any two adjacent ones of the plurality of first prism structures 111 may be smaller than the first structure width W1, and the ratio of the second structure width W2 to the spacing width Ws may be less than or equal to 0.5.

[0085] In the first prism film 110C of the present embodiment, the substrate surface 115s1 is not provided with a partial surface of the prism structure. In addition to further improving the uniformity of the light distribution of the backlight module operating in the sharing mode in the anti-peeping axis, it can also suppress the generation of stray light at a specific anti-peeping viewing angle when the backlight module operates in the anti-peeping mode.

[0086] Fig. 9 is a cross-sectional schematic diagram of a first prism sheet according to a fourth embodiment of the present utility model. Fig. 9 In this embodiment, the first prism sheet 110D and Figure 7 The difference between the first prism sheet 110B of the present embodiment is that the first prism sheet 110D of the present embodiment further includes a plurality of third prism structures 113. The plurality of first prism structures 111, the plurality of second prism structures 112 and the plurality of third prism structures 113 are alternately arranged along the normal direction (eg, direction D1) of the second light incident surface IS2.

[0087] In the normal direction (e.g., direction D3) of the substrate surface 115s1, the first prism structure 111, the second prism structure 112, and the third prism structure 113 have a first height h1, a second height h2, and a third height h3, respectively. It is particularly noted that the second height h2 of the second prism structure 112 is smaller than the first height h1 of the first prism structure 111, and the third height h3 of the third prism structure 113 is smaller than the second height h2 of the second prism structure 112.

[0088] On the other hand, in the normal direction (e.g., direction D1) of the second light incident surface IS2, the first prism structure 111, the second prism structure 112, and the third prism structure 113 have a first structure width W1, a second structure width W2, and a third structure width W3, respectively. It is particularly noted that the sum of the second structure width W2 and the third structure width W3 is less than or equal to the first structure width W1 of the first prism structure 111. In the present embodiment, the sum of the second structure width W2 and the third structure width W3 may be substantially equal to the spacing width Ws between any two adjacent ones of the plurality of first prism structures 111.

[0089] From another perspective, the second prism structure 112 and the third prism structure 113 have a Figure 2 The optical surface OS1 and the optical surface OS2 of the second light guide plate LGP2. It is particularly noted that the angle θ2 between the optical surface OS2 and the substrate surface 115s1 may be less than or equal to the angle θ1 between the optical surface OS1 and the substrate surface 115s1. Preferably, the angle θ1 and the angle θ2 may each be greater than or equal to 10 degrees and less than or equal to 45 degrees (for example, the vertex angle is greater than or equal to 90 degrees and less than or equal to 160 degrees). Accordingly, without affecting the anti-peeping performance, the backlight module using the first prism sheet 110D of this embodiment and operating in the sharing mode can have a more uniform and continuous light output distribution in the anti-peeping axis.

[0090] Fig.10 is a cross-sectional schematic diagram of a first prism sheet according to the fifth embodiment of the present utility model. Fig.10 In this embodiment, the first prism sheet 110E and Fig. 9 The difference between the first prism sheet 110D and the first prism sheet 110E is that the configuration of the multiple prism structures on the prism sheet is different. Specifically, in this embodiment, the second prism structure 112 and the third prism structure 113 do not completely occupy the spacing area between any two adjacent ones of the multiple first prism structures 111. In other words, in the first prism sheet 110E of this embodiment, a portion of the substrate surface 115s1 of the first substrate 115 is exposed.

[0091] More specifically, in the normal direction (e.g., direction D1) of the second light incident surface IS2, the substrate surface 115s1 has a plane width Wf on a portion of the surface that is located between any two adjacent first prism structures 111 and not covered by the second prism structure 112 and the third prism structure 113. It is particularly noted that in this embodiment, the sum of the second structure width W2, the third structure width W3, and the plane width Wf is less than or equal to the first structure width W1, and the plane width Wf is greater than or equal to the second structure width W2 and the third structure width W3.

[0092] In the first prism film 110E of the present embodiment, the substrate surface 115s1 is not provided with a partial surface of the prism structure. In addition to further improving the uniformity of the light distribution of the backlight module operating in the sharing mode in the anti-peeping axis, it can also suppress the generation of stray light at a specific anti-peeping viewing angle when the backlight module operates in the anti-peeping mode.

[0093] In summary, in a backlight module and a display device of one embodiment of the utility model, a second light guide plate is provided on one side of the first light emitting surface of the first light guide plate. The second light emitting surface of the second light guide plate is arranged opposite to the first light guide plate, and is provided with a first prism sheet. The first substrate of the first prism sheet is provided with a plurality of first prism structures on the substrate surface facing the second light guide plate. These first prism structures are arranged at intervals according to the spacing width along the normal direction of the second light incident surface of the second light guide plate. Through the arrangement of these first prism structures, the light collection property of the display device in the anti-peeping axis direction when operating in the anti-peeping mode can be effectively improved. By designing the ratio of the aforementioned spacing width to the structural width of the first prism structure in the normal direction of the second light incident surface to be less than 2, the light output distribution of the backlight module in the anti-peeping axis direction can be more uniform and continuous when the display device is operated in the sharing mode, which helps to improve the visual quality of the display device at various viewing angles.

[0094] However, what is described above is only the preferred embodiment of the utility model, and it cannot be used to limit the scope of implementation of the utility model. That is, all simple equivalent changes and modifications made according to the claims of the utility model and the content of the utility model are still within the scope of the patent of the utility model. In addition, any embodiment or claim of the utility model does not have to achieve all the purposes, advantages or features disclosed by the utility model. In addition, the abstract and title (utility model name) are only used to assist in the retrieval of patent documents, and are not used to limit the scope of rights of the utility model. In addition, the terms "first", "second", etc. mentioned in this specification or claims are only used to name the name of the element or distinguish different embodiments or scopes, and are not used to limit the upper or lower limit of the number of elements.

Claims

1. A backlight module, characterized in that: The backlight module includes a first light guide plate, a first light source, a second light guide plate, a second light source and a first prism sheet, wherein: The first light guide plate has a first light incident surface and a first light emitting surface connected to each other; The first light source is disposed on one side of the first light incident surface of the first light guide plate; The second light guide plate is disposed on one side of the first light emitting surface of the first light guide plate and overlaps the first light emitting surface, the second light guide plate having a second light incident surface and a second light emitting surface connected to each other, wherein the first light incident surface intersects with the second light incident surface; The second light source is disposed on one side of the second light incident surface of the second light guide plate; and The first prism sheet is disposed on one side of the second light emitting surface of the second light guide plate, and the first prism sheet includes a first substrate and a plurality of first prism structures, wherein: The first substrate has a substrate surface facing the second light emitting surface; and The multiple first prism structures are arranged on the surface of the substrate, and the multiple first prism structures are arranged at intervals along the normal direction of the second light incident surface, wherein in the normal direction of the second light incident surface, each of the multiple first prism structures has a first structure width, and there is a spacing width between any two adjacent ones of the multiple first prism structures, and the ratio of the spacing width to the first structure width is less than 2.

2. The backlight module according to claim 1, characterized in that: Each of the plurality of first prism structures has a vertex angle away from the first substrate, and the vertex angle is 60 degrees.

3. The backlight module according to claim 1, characterized in that: The first prism sheet also includes a plurality of second prism structures, and the plurality of first prism structures and the plurality of second prism structures are alternately arranged along a normal direction of the second light incident surface, and in the normal direction of the substrate surface, each of the plurality of first prism structures has a first height, and each of the plurality of second prism structures has a second height, and in the normal direction of the second light incident surface, each of the plurality of second prism structures has a second structure width, wherein the second height is less than the first height, and the second structure width is less than or equal to the first structure width.

4. The backlight module according to claim 3, characterized in that: The interval width is smaller than or equal to the first structure width, and the second structure width is smaller than the interval width.

5. The backlight module according to claim 4, characterized in that: A ratio of the second structure width to the interval width is less than or equal to 0.

5.

6. The backlight module according to claim 3, characterized in that: Each of the multiple first prism structures has a vertex angle away from the first substrate, and the angle of the vertex angle is 60 degrees. Each of the multiple second prism structures has an optical surface facing the second light guide plate, and the angle between the optical surface and the substrate surface is greater than or equal to 10 degrees and less than or equal to 45 degrees.

7. The backlight module according to claim 3, characterized in that: The first prism sheet also includes a plurality of third prism structures, and the plurality of third prism structures and the plurality of first prism structures are alternately arranged along a normal direction of the second light incident surface, wherein in the normal direction of the substrate surface, each of the plurality of third prism structures has a third height, and the third height is smaller than the second height.

8. The backlight module according to claim 7, characterized in that: The interval width is less than or equal to the first structure width.

9. The backlight module according to claim 7, characterized in that: Each of the multiple first prism structures has a vertex angle away from the first substrate, and the angle of the vertex angle is 60 degrees. Each of the multiple second prism structures has a first optical surface facing the second light guide plate, and a first angle is formed between the first optical surface and the surface of the substrate. Each of the multiple third prism structures has a second optical surface facing the second light guide plate, and a second angle is formed between the second optical surface and the surface of the substrate. The first angle and the second angle are each greater than or equal to 10 degrees and less than or equal to 45 degrees, and the second angle is less than or equal to the first angle.

10. The backlight module according to claim 1, characterized in that: The backlight module further includes a diffusion sheet and a second prism sheet, wherein: The diffusion sheet is disposed between the first light guide plate and the second light guide plate; and The second prism sheet is disposed between the first light guide plate and the second light guide plate, and includes a second substrate and a plurality of prism structures, wherein: The plurality of prism structures are disposed on a side of the second substrate facing the second light guide plate.

11. The backlight module according to claim 1, characterized in that: A diffusion layer is disposed on a side of the first substrate facing away from the plurality of first prism structures.

12. A display device, characterized in that: The display device comprises a backlight module and a display panel, wherein: The backlight module includes a first light guide plate, a first light source, a second light guide plate, a second light source and a first prism sheet, wherein: The first light guide plate has a first light incident surface and a first light emitting surface connected to each other; The first light source is disposed on one side of the first light incident surface of the first light guide plate; The second light guide plate is disposed on one side of the first light emitting surface of the first light guide plate and overlaps the first light emitting surface, the second light guide plate having a second light incident surface and a second light emitting surface connected to each other, wherein the first light incident surface intersects with the second light incident surface; The second light source is disposed on one side of the second light incident surface of the second light guide plate; and The first prism sheet is disposed on one side of the second light emitting surface of the second light guide plate, and the first prism sheet includes a first substrate and a plurality of first prism structures, wherein: The first substrate has a substrate surface facing the second light emitting surface; and The plurality of first prism structures are disposed on the surface of the substrate, and the plurality of first prism structures are arranged at intervals along a normal direction of the second light incident surface, wherein in the normal direction of the second light incident surface, each of the plurality of first prism structures has a first structure width, and there is an interval width between any two adjacent ones of the plurality of first prism structures, and a ratio of the interval width to the first structure width is less than 2; and The display panel is disposed on one side of the second light emitting surface of the second light guide plate and overlaps the second light emitting surface.

13. The display device according to claim 12, characterized in that: The display device further includes an electrically controlled viewing angle switcher, and the first prism sheet is arranged between the second light guide plate and the electrically controlled viewing angle switcher.

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