Backlight module and display device

Abstract

A backlight module and a display device comprising the backlight module, wherein the backlight module comprises at least one optical film (2) and a backlight unit (3). The optical film (2) has a light incident side (21) and a light emitting side (22) opposite to the light incident side (21), and a plurality of light incident microstructures (24) are formed on the light incident side (21), wherein the light incident microstructures (24) are cone-shaped structures. The backlight unit (3) is arranged on the light incident side (21) of the optical film (2), and comprises a light source (31). Through the structural design of the light incident microstructure (24) of the optical film (2), the light field of the light source (31) can be further expanded, so as to achieve the purpose of emitting light at a specific angle.

Description

Technical Field

[0001] The invention relates to an optical element, and in particular to a backlight module and a display device with a special light angle. Background Art

[0002] With the expansion of liquid crystal displays (LCD) in applications such as mobile phones, car displays, personal digital assistants (PDAs) and televisions, higher requirements are placed on backlight technology based on light guide plates, such as high brightness, low cost, low energy consumption, and thinness.

[0003] Taking an in-vehicle display as an example, its viewing angle is required to be extremely wide in the horizontal direction, but the existing backlight module architecture cannot meet the special viewing angle requirements of the in-vehicle display. Summary of the invention

[0004] Therefore, an object of the present invention is to provide a backlight module that can expand the light field and generate a specific light angle.

[0005] The backlight module includes at least one optical film and a backlight unit. The optical film has a light incident side and a light exit side opposite to the light incident side, and a plurality of light incident microstructures are formed on the light incident side, and the light incident microstructures are cone-shaped structures. The backlight unit is arranged on the light incident side of the optical film and includes a light source.

[0006] Another technical means of the present invention is that each light-entering microstructure has multiple side surfaces, vertices and a center line, the center line is perpendicular to the light-entering side of the optical film, and the vertex is located on the center line, wherein the multiple side surfaces use the vertex as a joining point and adjacent edges are joined to each other to form a composite surface.

[0007] Another technical means of the present invention is to define the extension direction of the optical film to have an X-axis and a Y-axis perpendicular to the X-axis, the light-entering microstructure has a first optical surface and a second optical surface with the same slope and symmetrically arranged in the direction of the X-axis, and has a third optical surface and a fourth optical surface with the same slope and symmetrically arranged in the direction of the Y-axis, and the light-entering microstructure is in a symmetrical pyramid shape.

[0008] Another technical means of the present invention is that a plurality of light-emitting microstructures are formed on the light-emitting side of the optical film, and the light-emitting microstructures are convex.

[0009] Another technical means of the present invention is that the backlight unit also includes a diffusion plate for receiving light from the light source, the light source has a circuit board and a plurality of light-emitting diodes arranged on the circuit board, and the diffusion plate has a bottom surface and a light-emitting surface opposite to the bottom surface, the bottom surface faces the circuit board, and the light-emitting surface faces the optical film.

[0010] Another technical means of the present invention is that the backlight unit also includes a light guide plate for receiving light from the light source, the light source has a circuit board and a plurality of light-emitting diodes arranged on the circuit board, and the light guide plate has a side surface and a light-emitting surface connected to the side surface, the side surface faces the circuit board, and the light-emitting surface faces the optical film.

[0011] Another technical means of the present invention is that the optical film includes a substrate layer, a structural layer disposed on one side of the substrate layer, and a diffusion particle layer disposed on the other side of the substrate layer, and the light incident microstructure is formed on the structural layer.

[0012] Another technical means of the present invention is to define the extension direction of the optical film to have an X-axis and a Y-axis perpendicular to the X-axis, the light-entering microstructure has a first optical surface and a second optical surface with different slopes and asymmetrical arrangement in the direction of the X-axis, and has a third optical surface and a fourth optical surface with the same slope and symmetrical arrangement in the direction of the Y-axis, and the light-entering microstructure is an asymmetric pyramid.

[0013] Another technical means of the present invention is that the backlight module also includes a grating layer located on the light-emitting side of the optical film, the grating layer has a plurality of baffles and a plurality of light-transmitting portions arranged between adjacent baffles, the baffles are spaced and inclined along the direction of the X-axis, and extend along the direction of the Y-axis.

[0014] Another technical means of the present invention is that the light source has a circuit board, a plurality of light-emitting diodes arranged on the circuit board, and a light-transmitting adhesive layer covering the light-emitting diodes, the light-emitting diodes are blue light sources, and the backlight module also includes a fluorescent film, which is used to cooperate with the light-emitting diodes to convert the blue light source into a white light source, wherein the backlight unit also includes a diffusion plate or a diffusion sheet for receiving light from the light source.

[0015] Another object of the present invention is to provide a display device, which includes the backlight module as mentioned above, and a display panel disposed on the backlight module.

[0016] The effect of the present invention is that, through the structural design of the light-incoming microstructure of the optical film, the light field of the light source is further expanded to achieve the purpose of emitting light at a specific angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1It is a schematic diagram of a first preferred embodiment of the backlight module of the present invention, wherein the light source is a direct-type light source.

[0018] Figure 2 is a schematic diagram of another form of the first preferred embodiment, wherein the light source is a side-entry light source;

[0019] Figure 3 is a schematic diagram of a preferred embodiment of the display device of the present invention;

[0020] Figure 4 is a schematic diagram illustrating that the light incident microstructure is a symmetrical pyramid shape;

[0021] Figure 5 is a curve diagram illustrating that the optical film of the present invention can reduce the brightness at the middle viewing angle and simultaneously improve the brightness at the large viewing angles on both sides;

[0022] Figure 6 is a schematic diagram of a second preferred embodiment of a backlight module of the present invention;

[0023] Figure 7 is a schematic diagram illustrating the structure of an optical film according to a second preferred embodiment;

[0024] Figure 8 is a schematic diagram of a third preferred embodiment of a backlight module of the present invention;

[0025] Fig. 9 is a schematic diagram illustrating the structure of an optical film according to a third preferred embodiment; and

[0026] Fig.10 FIG. 4 is a schematic diagram illustrating a light emission angle simulation of the third preferred embodiment. DETAILED DESCRIPTION

[0027] The features and technical contents of the related patent applications of the present invention will be clearly presented in the detailed description of the preferred embodiments with reference to the accompanying drawings. Before the detailed description, it should be noted that similar components are represented by the same numbers.

[0028] See also Figure 1 , which is the first preferred embodiment of the backlight module of the present invention, comprises an optical film 2 and a backlight unit 3. In some embodiments, the backlight unit 3 comprises a direct-type light source 31, a diffusion plate 32 for receiving light from the light source 31, a diffusion sheet 33 stacked on the diffusion plate 32, and a brightness enhancement film 34 located on the light-emitting side of the diffusion sheet 33. The light source 31 comprises a circuit board 311 and a plurality of light-emitting diodes 312 arranged on the circuit board 311, and the diffusion plate 32 comprises a bottom surface 321 and a light-emitting surface 322 opposite to the bottom surface 321, the bottom surface 321 faces the circuit board 311, and the light-emitting surface 322 faces the diffusion sheet 32. See Figure 2In another embodiment, the backlight unit 3 includes an edge-type light source 31, a light guide plate 35 for receiving light from the light source, a diffuser 33 stacked on the light guide plate 35, and a brightness enhancement film 34 located on the light-emitting side of the diffuser 33. The light guide plate 35 has a light-entering surface 351 facing the circuit board 311 and a light-emitting surface 352 connected to the light-entering surface 351, and the light-emitting surface 352 faces the diffuser 33. Figure 3 As shown, the display panel 36 is arranged on the light-emitting side of the brightness enhancement film 34, thus forming a display device. It should be noted that in order to clearly display the structure of each component, each component is separated from each other. In actual use, each component is closely stacked, and the same applies to the following embodiments.

[0029] See also Figure 1 and Figure 2 In the present embodiment, the optical film 2 is disposed between the diffuser 33 and the brightness enhancement film 34, and is a prism sheet with microstructures formed on both sides. In more detail, the optical film 2 has a light incident side 21 and a light emitting side 22 opposite to the light incident side 21, the light incident side 21 faces the diffuser 33, and the light emitting side 22 faces the brightness enhancement film 34. A plurality of light emitting microstructures 23 are formed on the light emitting side 22, and the light emitting microstructures 23 are convex. A plurality of light incident microstructures 24 are formed on the light incident side 21, wherein the light incident microstructure 24 is a cone-shaped structure. When the light of the light-emitting diode 312 enters the light incident microstructure 24 of the optical film 2, since the light incident microstructure 24 is a cone-shaped structure with multiple side surfaces, the light can be refracted outward through the multiple side surfaces of the light incident microstructure 24 in either the X-axis or Y-axis directions to produce a light splitting effect, thereby homogenizing the directional light source of the light-emitting diode 312. It should also be noted that the light incident microstructure 24 is a cone-shaped structure, which is not limited to a concave or convex structure, and can also make the light field of the light source 31 more expanded. In this embodiment, the cone-shaped structure adopts a concave design to avoid scratching the diffuser 33 stacked thereunder.

[0030] like Figure 4 As shown, each light-entering microstructure 24 is a quadrangular pyramid structure, having four side surfaces 241, a vertex P, and a center line C, wherein the center line C is perpendicular to the light-entering side 21 of the optical film 2, and the vertex P is located on the center line C, wherein the four side surfaces 241 are joined with the vertex P and adjacent edges are joined to form a composite surface. In more detail, the extension direction of the optical film 2 is defined to have an X-axis and a Y-axis perpendicular to the X-axis, and the light-entering microstructure 24 has a first optical surface 241a and a second optical surface 241b with the same slope and symmetrical arrangement in the direction of the X-axis, and has a third optical surface 241c and a fourth optical surface 241d with the same slope and symmetrical arrangement in the direction of the Y-axis, so that the light-entering microstructure 24 is in a symmetrical pyramid shape.

[0031] Since each light incident microstructure 24 has first to fourth optical surfaces 241a-241d, when the light from the LED 312 enters the light incident microstructure 24 of the optical film 2, the light can be refracted outwards through the side surface 241 to produce a light splitting effect in both the X-axis direction and the Y-axis direction, thereby making the directional light source of the LED 312 uniform. Figure 5 As shown, compared with a general backlight module (as shown by the dotted line), the preferred embodiment (as shown by the solid line) uses an optical film 2 to slightly reduce the brightness of the middle viewing angle (that is, the area between the solid line and the dotted line is smaller when the viewing angle is between -40 degrees and +40 degrees), while greatly improving the brightness of the large viewing angles on both sides (that is, the area between the solid line and the dotted line is larger when the viewing angle is outside -40 degrees to +40 degrees), so that the distribution of the light field becomes wider, so as to be suitable for vehicle-mounted devices, and meet the special wide viewing angle requirements often required by vehicle-mounted models for the purpose of allowing the driver's seat and the passenger seat to watch at the same time.

[0032] See also Figure 6 , which is a second preferred embodiment of the backlight module of the present invention, comprises at least one optical film 4 and a backlight unit 5. The backlight unit 5 comprises a light source 51, a diffusion plate 52 for receiving light from the light source 51, a fluorescent film 53 located on the light-emitting side of the diffusion plate 52, and a plurality of brightness enhancement films 54 located on the light-emitting side of the fluorescent film 53. In this embodiment, two optical films 4 are stacked between the diffusion plate 52 and the fluorescent film 53. Among them, the light source 51 is a direct-type light source and has a circuit board 511, a plurality of light-emitting diodes 512 disposed on the circuit board 511, and a light-transmitting adhesive layer 513 covering the light-emitting diodes. The light-emitting diode 512 is a blue light source, and the fluorescent film 53 is used to cooperate with the light-emitting diode 512 to convert the blue light source into a white light source.

[0033] See also Figure 7 Each optical film 4 includes a substrate layer 41, a structural layer 42 disposed on one side of the substrate layer 41, and a diffusion particle layer 43 disposed on the other side of the substrate layer 41. A plurality of light-entering microstructures 44 are formed on the side of the structural layer 42 facing the diffusion plate 52. The light-entering microstructures 44 are cone-shaped structures. In this embodiment, the cone-shaped structures are convexly designed and are in the same symmetrical pyramid shape as the first preferred embodiment, which can also make the light field of the light source 31 more expanded.

[0034] See also Figure 6 and Figure 7In this embodiment, in addition to achieving the effect of spreading the light of the light source 51 more through the design of the light-entering microstructure 44 to meet the special wide viewing angle requirements often required by the vehicle-mounted machine for the purpose of allowing the driver's seat and the passenger seat to watch at the same time, the optical film 4 can also make the light passing through the structural layer 42 and the substrate layer 41 produce a better uniform light effect through the diffusion particle layer 43, so as to further uniformize the bright spot area directly above the light-emitting diode 512 and reduce the shadow area between the light-emitting diodes 512, thereby reducing the generation of hot spots. In addition, the two layers of optical film 4 stacked in this embodiment have a double effect. Since the optical film 4 can greatly improve the uniformity of light, the required light mixing distance between the light source 51 and the diffuser 52 can be shortened, which is conducive to the thinning of the overall structure. At the same time, since the filling material (such as polycarbonate, PC) often used on the light-transmitting adhesive layer 513 in the conventional technology to support the diffuser 52 and other optical films is eliminated, the material cost can be reduced, the stacking thickness of the filling material can be reduced, and the overall structure can be further thinned.

[0035] See also Figure 8 , which is a third preferred embodiment of the backlight module of the present invention, comprises an optical film 6, a backlight unit 7, and a grating layer 8. The backlight unit 7 comprises a light source 71, a diffuser 72 for receiving light from the light source 71, and a fluorescent film 73 located on the light-emitting side of the diffuser 72. The optical film 6 is disposed between the fluorescent film 73 and the grating layer 8. The fluorescent film 73 is also used to convert the blue light source into a white light source.

[0036] The optical film 6 has a light-entering side 61 and a light-emitting side 62 opposite to the light-entering side 61, the light-entering side 61 faces the fluorescent film 73, and the light-emitting side 62 faces the grating layer 8. A plurality of light-entering microstructures 63 are formed on the light-entering side 61, and the light-entering microstructures 63 are cone-shaped structures. In this embodiment, the cone-shaped structure is further designed in a concave shape to avoid scratching the fluorescent film 73 stacked thereunder. In more detail, as shown in FIG. Fig. 9 As shown, the extension direction of the optical film 6 is defined to have an X-axis and a Y-axis perpendicular to the X-axis. The light-entering microstructure 63 has a first optical surface 631a and a second optical surface 631b with different slopes and asymmetrical arrangement in the direction of the X-axis, and has a third optical surface 631c and a fourth optical surface 631d with the same slope and symmetrical arrangement in the direction of the Y-axis. Therefore, the light-entering microstructure 63 is an asymmetric pyramid. Fig. 9 In the embodiment, the light incident microstructures 63 are arranged continuously. In some embodiments, they may be arranged discontinuously. Adjacent light incident microstructures 63 are connected by a plane to avoid scratching the fluorescent film 73 stacked thereunder.

[0037] like Figure 8As shown, the grating layer 8 has a plurality of baffles 81 and a plurality of light-transmitting portions 82 disposed between adjacent baffles 81 . The baffles 81 are spaced and tilted along the X-axis and extend along the Y-axis.

[0038] When light passes through the optical film 6, in addition to the light splitting effect produced by the light incident microstructure 63, the asymmetric pyramid design can also deflect the light splitting in a specific direction, and combined with the setting of the grating layer 8, the light will be emitted from the light-transmitting portion 82 of the grating layer 8. Therefore, by simply adjusting the inclination angle of the baffle 81, the light emitting direction after passing through the grating layer 8 can be changed, thereby adjusting the distribution of the light field. Fig.10 As shown, by utilizing the design of this preferred embodiment, the light emission direction can be biased to one side.

[0039] Taking the application in the vehicle dashboard as an example, since there is a lot of information to be displayed on the dashboard, its display area is usually a horizontally extended rectangle rather than a square. Therefore, this embodiment uses the design of the optical film 6 and cooperates with the grating layer 8 to make the light deflect to a specific direction, such as providing driving information towards the driver's seat, to meet the asymmetric viewing angle requirements of the vehicle display device. At the same time, the slope of the optical surface 631a~631d and the tilt direction and angle of the baffle 81 of the grating layer 8 can be adjusted according to different usage environments to meet the requirements of various special viewing angles.

[0040] In summary, the present invention uses a symmetrical or asymmetrical pyramid-shaped structure design of the light-entering microstructure of the optical film, so that when light passes through the light-entering microstructure, the light can be refracted outward in both the X-axis and Y-axis directions to produce a splitting effect, and the directional light source is uniformed to meet the special wide viewing angle requirements often required by vehicle-mounted models for the purpose of allowing the driver's seat and the passenger seat to watch at the same time. The asymmetrical pyramid-shaped structure design can further deflect the light in a specific direction, such as providing driving information in the direction of the driver's seat, to meet the requirements of a special viewing angle, and can indeed achieve the purpose of the present invention.

[0041] The above description is only a preferred embodiment of the present invention, and should not be used to limit the scope of the present invention. That is, any simple equivalent changes and modifications made according to the scope of the claims and the content of the specification of the present invention are still within the scope of the patent coverage of the present invention.

[0042] [List of Reference Numerals]

[0043] 2 Optical film

[0044] 21 Light incident side

[0045] 22 Light output side

[0046] 23 Light-emitting microstructure

[0047] 24 Light-entering microstructure

[0048] 241 Side

[0049] 241a First optical surface

[0050] 241b Second optical surface

[0051] 241c Third optical surface

[0052] 241d Fourth optical surface

[0053] 3 Backlight unit

[0054] 31 Light Source

[0055] 311 Circuit Board

[0056] 312 LED

[0057] 32 Diffuser Plate

[0058] 321 Bottom

[0059] 322 Light emitting surface

[0060] 33 Diffuser

[0061] 34 Brightness Enhancement Film

[0062] 35 Light guide plate

[0063] 351 Light-entering surface

[0064] 352 Light emitting surface

[0065] 36 Display Panel

[0066] 4 Optical film

[0067] 41 base material layer

[0068] 42 Structural Layer

[0069] 43 Diffusion particle layer

[0070] 44 Light-entering microstructure

[0071] 5 Backlight unit

[0072] 51 Light Source

[0073] 511 Circuit Board

[0074] 512 LED

[0075] 513 Translucent adhesive layer

[0076] 52 Diffuser Plate

[0077] 53 Fluorescent film

[0078] 54 Brightness Enhancement Film

[0079] 6 Optical film

[0080] 61 Light incident side

[0081] 62 Light output side

[0082] 63 Light-entering microstructure

[0083] 631a First optical surface

[0084] 631b Second optical surface

[0085] 631c Third optical surface

[0086] 631d Fourth optical surface

[0087] 7 Backlight unit

[0088] 71 Light Source

[0089] 72 Diffuser

[0090] 73 Fluorescent film

[0091] 8 Grating layer

[0092] 81 Baffle

[0093] 82 light-transmitting part

[0094] P Vertex

[0095] C Central Line

[0096] X, Y axis.

Claims

1. A backlight module, comprising: at least one optical film having a light incident side and a light emitting side opposite to the light incident side, wherein a plurality of light incident microstructures are formed on the light incident side, and the light incident microstructures are cone-shaped structures; and A backlight unit is disposed on the light incident side of the optical film and includes a light source. in, The optical film is defined to extend in an X-axis and a Y-axis perpendicular to the X-axis. The light-entering microstructure has a first optical surface and a second optical surface with different slopes and asymmetrical arrangement in the direction of the X-axis, and a third optical surface and a fourth optical surface with the same slope and symmetrical arrangement in the direction of the Y-axis. The light-entering microstructure is in an asymmetric pyramid shape to deflect light in a specific direction. The backlight module further comprises a grating layer located on the light-emitting side of the optical film, wherein the grating layer has a plurality of baffles and a plurality of light-transmitting portions arranged between adjacent baffles, wherein the baffles are spaced and inclined along the direction of the X-axis and extend along the direction of the Y-axis.

2. The backlight module according to claim 1, in, Each of the light-entering microstructures has multiple side surfaces, vertices, and a center line, wherein the center line is perpendicular to the light-entering side of the optical film, and the vertex is located on the center line, wherein the multiple side surfaces are joined with the vertex as a joint point and adjacent edges are joined to each other to form a composite surface.

3. The backlight module according to claim 1 or 2, in, The light source comprises a circuit board, a plurality of light emitting diodes arranged on the circuit board, and a light-transmitting adhesive layer covering the light emitting diodes. The light emitting diodes are blue light sources. The backlight unit further comprises a fluorescent film and a diffusion sheet for receiving light from the light source. The fluorescent film is used in conjunction with the light emitting diodes to convert the blue light source into a white light source.

4. A display device, include: The backlight module according to any one of claims 1 to 3; and The display panel is arranged on the backlight module.

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