TW202043882A - Backlight module - Google Patents

Abstract

A backlight module including a light guide plate, a light source, an optical film, a first prism sheet and a second prism sheet is provided. The light guide plate has a light incident surface and a light exiting surface connected to each other. The light source is disposed on a side of the light incident surface of the light guide plate. The optical film includes a substrate, a plurality of optical microstructures and a first diffusion structure layer. The substrate has a light incident side and a light exiting side and the light incident side faces to the light guide plate. The optical microstructures are disposed on the light incident side. An extending direction of the optical microstructures intersect with the light incident surface. The first diffusion structure layer is disposed on the light exiting side and is overlapped with the optical microstructures. The first prism sheet and the second prism sheet are overlapped with the optical film and are positioned on the light exiting side. An extending direction of a plurality of prism structures of the first prism sheet intersects with an extending direction of a plurality of prism structures of the second prism sheet.

Description

Backlight module

The present invention relates to an optical module, and particularly relates to a backlight module.

With the increasing application of non-self-luminous displays such as liquid crystal displays, the design of the backlight module also needs to be adjusted for different usage scenarios. In order to improve the light energy utilization rate of the light source, the backlight module equipped with Brightness Enhancement Film (BEF) has become one of the mainstreams in the market. Generally speaking, this type of backlight module is equipped with a laminated structure of two optical brightness enhancement films (for example, two optical films whose extending directions are orthogonal to each other), which can guide the light beam emitted from the light guide plate at a large angle to cover Within a specific angle range of the front viewing angle, the overall light intensity of the backlight module near the front viewing angle is improved. However, this type of double-layer BEF configuration has limitations on the thinning of the backlight module.

In order to improve the light-collecting performance of the backlight module and break through the above-mentioned limitation of thinning, a light-collecting type backlight module that uses a reversed sheet to replace two laminated optical brightness enhancement films has emerged. This type of backlight module can further improve the overall light output near the front viewing angle (that is, the light-gathering characteristic with a smaller angle range). In addition, since the number of stacks of optical film layers mounted on the light-concentrating backlight module is small, the overall thickness can be effectively reduced, which contributes to the thinning of the backlight module. However, from another point of view, when using this type of light-concentrating backlight module, when there are fine defects or tiny foreign objects (such as dust or lint brought in during assembly) between the various film layers of the backlight module, It is easy to be detected in the subsequent optical inspection process of quality control. In other words, this type of backlight module with excellent light collection performance is also poor in concealment of fine defects, resulting in a decrease in the overall assembly yield. Therefore, how to balance the light collection and concealment properties of the backlight module is one of the difficult problems faced by related manufacturers during design and development.

The invention provides a backlight module with high assembly yield and better light collection.

Other objectives and advantages of the present invention can be further understood from the technical features disclosed in the present invention.

In order to achieve one or part or all of the above objectives or other objectives, an embodiment of the present invention provides a backlight module. The backlight module includes a light guide plate, a light source, an optical film, a first optical film and a second optical film. The light guide plate has a light-emitting surface and a light-incident surface connected. The light source is arranged on one side of the light incident surface of the light guide plate. The optical film is overlapped and arranged on the light emitting surface of the light guide plate. The optical film includes a substrate, a plurality of optical microstructures, and a first diffusion structure layer. The substrate has opposite light-incoming sides and light-exiting sides, and the light-incoming side faces the light guide plate. A plurality of optical microstructures are arranged on the light incident side of the substrate, and the extension directions of these optical microstructures intersect the light incident surface of the light guide plate. The first diffusion structure layer is disposed on the light emitting side of the substrate and overlaps the plurality of optical microstructures. The first sheet and the second sheet are overlapped on the optical film, and each has a plurality of sheet structures. The first optical film and the second optical film are located on the light-emitting side of the substrate, and the first optical film is located between the optical film and the second optical film. The extension directions of the multiple ridge structures of the first ridge piece intersect with the extension directions of the multiple ridge pieces of the second ridge piece.

In an embodiment of the present invention, the extension direction of the multiple optical microstructures of the optical film of the aforementioned backlight module is perpendicular to the light incident surface of the light guide plate.

In an embodiment of the present invention, the multiple optical microstructures of the optical film of the aforementioned backlight module include multiple diffusion particles.

In an embodiment of the present invention, the cross section of each of the multiple optical microstructures of the optical film of the backlight module is triangular, arc-shaped or polygonal.

In an embodiment of the present invention, the vertical projection of the extension path of the optical microstructure of the optical film of the aforementioned backlight module on the light exit surface of the light guide plate is wavy or folded.

In an embodiment of the present invention, the material of the first diffusion structure layer of the aforementioned backlight module includes a plurality of diffusion particles.

In an embodiment of the present invention, the surface of the first diffusion structure layer of the aforementioned backlight module has a microstructure.

In an embodiment of the present invention, the second diffusive sheet of the aforementioned backlight module further has a second diffusion structure layer, which is disposed on the side of the second diffusive sheet facing the first diffusive sheet.

In an embodiment of the present invention, the multiple ridge structures of the second ridge sheet of the backlight module include multiple diffusion particles.

In an embodiment of the present invention, the refractive index of the multiple ridge structures of the first and second ridges of the backlight module is between 1.62 and 1.75.

Based on the above, in the backlight module of an embodiment of the present invention, the optical film located between the light guide plate and the light guide plate has a plurality of optical microstructures arranged on the side of the light emitting surface of the light guide plate, and transmits the optical microstructures. The extension direction of the structure intersects the light incident surface of the light guide plate, which can increase the overall light output of the backlight module near the normal viewing angle (that is, the light collection of the backlight module can be improved). On the other hand, the diffusion structure layer is provided on the side far away from the optical microstructure through the optical film, which can improve the concealability of the backlight module, thereby improving the assembly yield of the backlight module. In other words, the process latitude of each component of the backlight module can also be increased.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail in conjunction with the accompanying drawings.

The foregoing and other technical content, features and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the drawings. The directional terms mentioned in the following embodiments, for example: up, down, left, right, front or back, etc., are only directions for referring to the attached drawings. Therefore, the directional terms used are used to illustrate but not to limit the present invention.

Fig. 1 is a schematic diagram of a backlight module according to a first embodiment of the present invention. FIG. 2 is a schematic side view of the backlight module of FIG. 1. FIG. 3 is a schematic top view of the backlight module of FIG. 1. Fig. 4 is a schematic cross-sectional view of the optical film of Fig. 1. In particular, for the sake of clarity, FIG. 3 only shows the light guide plate 100, the light source 110 and the optical microstructure 122 of FIG. 2.

1 and 2, the backlight module 50 includes a light guide plate 100, a light source 110 and an optical film 120. The light guide plate 100 has a light emitting surface 100a and a light incident surface 100b, and the light emitting surface 100a and the light incident surface 100b are connected. The optical film 120 is overlapped and arranged on the light-emitting surface 100 a of the light guide plate 100. The light source 110 is arranged on one side of the light incident surface 100 b of the light guide plate 100. That is, the backlight module 50 of this embodiment is an edge-type backlight module. However, the present invention is not limited to this. According to other embodiments, the backlight module may also be a direct backlit module. It should be noted that, in this embodiment, the number of light sources 110 is exemplified by taking five as an example, which does not mean that the present invention is limited by the content of the drawings. In other embodiments, the number of the light sources 110 can be adjusted according to the optical design of the backlight module.

Furthermore, the optical film 120 includes a substrate 121, a plurality of optical microstructures 122 and a first diffusion structure layer 123. The substrate 121 has opposite light incident sides 121a and light exit sides 121b, wherein the light incident side 121a faces the light guide plate 100, and the optical microstructures 122 are arranged on the light incident side 121a of the substrate 121, wherein the extension directions of the optical microstructures 122 intersect On the light incident surface 100 b of the light guide plate 100, and these optical microstructures 122 can selectively contact the light guide plate 100. In this embodiment, the material of the substrate 121 may include polyethylene terephthalate (PET) and polycarbonate (PC). The material of the optical microstructure 122 may include UV glue, or other suitable high molecular polymers.

In this embodiment, the optical microstructures 122 of the optical film 120 may be arranged on the substrate 121 along the direction X and extend in the direction Y. For example, the cross-sectional profile of the optical microstructure 122 on a plane (ie XZ plane) perpendicular to the extension direction (ie, direction Y) may be triangular. That is, the optical microstructure 122 of this embodiment may be a triangular stripe, but the present invention is not limited to this. In other embodiments, the cross-sectional profile of the optical microstructure 122 on the XZ plane may also be based on actual Light type needs (or light splitting effect) and adjusted. More specifically, referring to FIG. 2, each of these optical microstructures 122 has a first inclined surface 122s1 and a second inclined surface 122s2 opposite to each other, and the junction of the first inclined surface 122s1 and the second inclined surface 122s2 defines a portion of the optical microstructure 122 Ridge RL. In this embodiment, the optical microstructure 122 has an apex angle θ between the first inclined surface 122s1 and the second inclined surface 122s2, and the apex angle θ may be between 50 degrees and 90 degrees, but the present invention does not take this as limit. In other embodiments, the apex angle θ of the optical microstructure can also be 90 degrees, between 90 degrees and 130 degrees, or between 30 degrees and 150 degrees.

3, in this embodiment, the extension direction (ie direction Y) of the vertical projection of the ridge line RL (ie extension path) of the optical microstructure 122 on the light emitting surface 100a of the light guide plate 100 can be selectively perpendicular to the guide plate 100 The light incident surface 100b of the light plate 100. However, the present invention is not limited to this. According to other embodiments, the extension direction of the vertical projection of the ridge line RL of the optical microstructure 122 on the light guide plate 100 may not be perpendicular to the light incident surface 100 b of the light guide plate 100. For example, the angle between the extension direction of the vertical projection of the ridge line RL of the optical microstructure 122 on the light guide plate 100 and the light incident surface 100b of the light guide plate 100 may be between 45 degrees and 90 degrees. Accordingly, the overall light output of the backlight module near the front viewing angle can be increased.

1 and 4, the first diffusion structure layer 123 of the optical film 120 is disposed on the light-exit side 121b of the substrate 121, and overlaps in the normal direction (ie direction Z) of the light-emitting surface 100a of the light guide plate 100. One optical microstructure 122. For example, the first diffusion structure layer 123 of the optical film 120 may optionally include a photosensitive adhesive layer 1231 and a plurality of diffusion particles 1232, wherein the diffusion particles 1232 are covered by the photosensitive adhesive layer 1231 (as shown in FIG. 4 ). In this embodiment, the material of the photosensitive glue layer 1231 is, for example, UV glue or other suitable transparent photosensitive glue. The material of the diffusion particles 1232 may include polymethyl methacrylate (PMMA), polystyrene (PS), or a copolymer of the foregoing materials. On the other hand, in this embodiment, the plurality of diffusion particles 1232 of the first diffusion structure layer 123 may be spherical and have various particle sizes, but the present invention is not limited thereto. In other embodiments, the plurality of diffusion particles 1232 may also have substantially the same particle size.

It is worth mentioning that the transparent optical film 120 is provided with a first diffusion structure layer 123 on the light exit side 121b, so that the optical film 120 can have a specific haze value. For example, the haze value of the first diffusion structure layer 123 (or the optical film 120) may be between 20% and 90%. Accordingly, the concealment of the backlight module can be improved, thereby increasing the assembly yield of the backlight module. In other words, the process latitude of each component of the backlight module can also be increased. On the other hand, since the first diffusion structure layer 123 (or the optical film 120) has a specific haze value, the number of diffusers of the backlight module 50 can be further reduced, which helps reduce production costs.

In particular, to meet specific concealment requirements, in order to maximize the overall light output of the backlight module near the front viewing angle, the apex angle θ of the optical microstructure 122 can be adjusted according to the haze value of the first diffusion structure layer 123 Adjustment. For example, in one embodiment, the haze value of the first diffusion structure layer 123 is 20%, and the apex angle θ of the optical microstructure is 90 degrees; in another embodiment, the haze value of the first diffusion structure layer 123 The haze value is 50%, and in order to obtain the same degree of forward brightness (brightness), the apex angle θ of the optical microstructure needs to be designed to be less than 70 degrees.

Furthermore, the backlight module 50 further includes a first plate 130 and a second plate 140. The first sheet 130 and the second sheet 140 overlap the optical film 120 in the normal direction (ie direction Z) of the light-emitting surface 100a of the light guide plate 100, and are located on the light-emitting side 121b of the substrate 121 of the optical film 120 ( That is, the optical film 120 is provided on one side of the first diffusion structure layer 123). The first optical film 130 is located between the optical film 120 and the second optical film 140. Specifically, the first scallop sheet 130 has a substrate 131 and a plurality of scallop structures 132. These ridge structures 132 are arranged on the surface of the substrate 131 away from the optical film 120 along the direction Y, and extend in the direction X. Similarly, the second ridge sheet 140 has a substrate 141 and a plurality of ridge structures 142. The ridge structures 142 are arranged on the side surface of the substrate 141 away from the first ridge piece 130 along the direction X, and extend in the direction Y.

Continuing the above, in this embodiment, the extension direction (ie direction X) of the multiple ridge structures 132 of the first ridge piece 130 may be perpendicular to the extension direction (ie, direction) of the multiple ridge pieces 142 of the second ridge piece 140 Y), but the present invention is not limited to this. In other embodiments, the extension direction of the plurality of ridge structures 132 of the first ridge sheet 130 may not be perpendicular and not parallel to the extension direction of the plurality of ridge structures 142 of the second ridge sheet 140. That is, the angle between the extension direction of the plurality of ridge structures 132 of the first ridge sheet 130 and the extension direction of the plurality of ridge structures 142 of the second ridge sheet 140 may be greater than 0 degree and less than 90 degrees. In another embodiment, the extension direction of the multiple ridge structures 132 may be perpendicular to the extension direction of the multiple ridge structures 142, and the extension direction of the vertical projection of the ridgeline RL of the optical microstructure 122 on the light guide plate 100 may be perpendicular The angle between the extension direction of the plurality of ridge structures 132 and the vertical projection of the ridge line RL of the optical microstructure 122 on the light guide plate 100 and the light incident surface 100b of the light guide plate 100 may be 90 degrees, between 45 degrees to 135 degrees, or unlimited angles. In this embodiment, the refractive index of the multiple ridge structures 132 of the first ridge plate 130 and the multiple ridge structures 142 of the second platelet 140 may be between 1.62 and 1.75. In this way, the overall light output of the backlight module 50 near the normal viewing angle can be further increased.

Please continue to refer to FIG. 1, the backlight module 50 may also optionally include a diffusion sheet 150, but the invention is not limited to this. The diffusion sheet 150 is overlapped and arranged on the second ridge piece 140 and is located on the side of the second ridge piece 140 away from the first ridge piece 130. Furthermore, the backlight module 50 may further include a reflective sheet 160, the light guide plate 100 further has a bottom surface 100c opposite to the light emitting surface 100a, and the reflective sheet 160 is disposed on the side of the light guide plate 100 where the bottom surface 100c is provided. As part of the light beam emitted by the light source 110 is transmitted through the light guide plate 100, it will be emitted from the bottom surface 100c of the light guide plate 100, causing light energy loss. Therefore, through the arrangement of the reflective sheet 160, part of the light beam mentioned above can be reflected and transmitted back to the light guide plate 100, so as to improve the light energy utilization rate of the light source 110. However, the present invention is not limited to this, and in other embodiments, the backlight module may not have the reflective sheet 160.

Specifically, the backlight module (such as the backlight module 50) of the embodiment of the present invention is suitable for use with a non-self-luminous display panel, such as a liquid crystal display (LCD) panel or an electrophoretic display (EPD). ) Panels to be assembled into electronic devices (ie display devices) that can be used to display images. In other words, any display apparatus (display apparatus) that includes a non-self-luminous display panel and adopts the embodiments of the present invention still belongs to the applicable technical solution of the present disclosure, and does not depart from the scope of protection of the present disclosure. .

5 to 8 are schematic cross-sectional views of optical films according to other embodiments of the present invention. In particular, any optical film of FIGS. 5 to 8 can replace the optical film 120 of FIG. 1 to form a backlight module of different implementations. Referring to FIG. 5, the main difference between the optical film 120A of this embodiment and the optical film 120 of FIG. 4 lies in the composition and structure of the first diffusion structure layer. In this embodiment, the first diffusion structure layer 123A of the optical film 120A does not have diffusion particles, and the surface 123s of the first diffusion structure layer 123A away from the substrate 121 has a microstructure. It should be noted that the microstructures here are exemplarily illustrated with irregular (or random number distribution) concave-convex structures, which does not mean that the present invention is limited by the content of the diagrams. In some embodiments, the microstructure of the first diffusion structure layer may also be a periodically distributed concave-convex structure, and the production of these concave-convex structures can be carried out by making a mold by photolithographic etching, or a photolithographic etching process can be used (Photolithography and etching process) The concave-convex structure is directly fabricated on the first diffusion structure layer 123A. That is, the material of the first diffusion structure layer 123A may include UV glue or photoresist. It is worth mentioning that the manufacturing method of these concave-convex structures is not limited to the above method. In other embodiments, sandblasting can be used on the mold to make the surface of the mold concave and convex, and then UV forming is performed to produce the first diffusion structure layer. .

6, the main difference between the optical film 120B of this embodiment and the optical film 120A of FIG. 5 lies in the composition of the optical microstructure and the first diffusion structure layer. In this embodiment, the optical microstructure 122A of the optical film 120B may include a plurality of diffusion particles 1222 (that is, the optical microstructure 122A may also have a specific haze value). On the other hand, a mold (such as a roller) with a random distribution of uneven microstructures can be used to form a random distribution of uneven microstructures on the UV-curable adhesive material provided on the light-emitting side 121b of the substrate 121 and then be hardened. To form the first diffusion structure layer 123B; or the method for forming the first diffusion structure layer 123B may include the step of using ultraviolet light or plasma on the surface of the light-emitting side 121b of the substrate 121 to roughen the surface, that is, the first diffusion structure The material of the layer 123B and the substrate 121 may be the same. For example, the haze value of the optical microstructure 122A may be smaller than the haze value of the first diffusion structure layer 123B. However, the present invention is not limited to this. In other embodiments, the relationship between the haze value of the optical microstructure 122A and the haze value of the first diffusion structure layer 123B can also be based on the overall haze requirement of the optical film 120B. Depends. In another embodiment, the first diffusion structure layer of the optical film may not have a microstructure or the optical film does not have the first diffusion structure layer, that is, the haze required by the optical film is composed of diffusion particles 1222. A plurality of optical microstructures 122A are provided.

7 and 8, the main difference between the optical film 120C of FIG. 7, the optical film 120D of FIG. 8 and the optical film 120A of FIG. 5 lies in the configuration of the optical microstructure. Specifically, the cross-sectional profile of the optical microstructure 122B of the optical film 120C is arc-shaped, and the cross-sectional profile of the optical microstructure 122C of the optical film 120D is polygonal (that is, the cross-sectional profile of the optical microstructure 122C With multiple polyline segments). However, the present invention is not limited to the above-mentioned embodiments. The above-mentioned different composition and structure of the first diffusion structure layer, composition and configuration of the optical microstructure, etc., can be combined and applied according to the overall haze requirements of the optical film. .

FIG. 9A is a schematic top view of the backlight module of the second embodiment of the present invention. FIG. 9B is a schematic top view of the backlight module of the third embodiment of the present invention. Please refer to FIG. 9A. The difference between the backlight module 50A of this embodiment and the backlight module 50 of FIG. 3 lies in the configuration of the optical microstructure. In this embodiment, the vertical projection of the ridge line RL-A (that is, the extension path) of the optical microstructure 122D of the optical film 120E on the light emitting surface 100a of the light guide plate 100 is a fold line shape. Specifically, although the extension path of the optical microstructure 122D is in the shape of a broken line, the vertical projection of the ridge line RL-A on the light guide plate 100 is still limited between two virtual straight lines IL.

More specifically, the vertical projections of the multiple bends of the ridgeline RL-A of the optical microstructure 122D on the light guide plate 100 are respectively aligned with two virtual straight lines IL, and the extension directions of the two virtual straight lines IL are respectively perpendicular to The light incident surface 100b of the light guide plate 100. That is to say, although the extension path of the optical microstructure 122D is in the shape of a broken line, its extension direction is still substantially perpendicular to the light incident surface 100b of the light guide plate 100 (ie, the direction Y). It is worth mentioning that the vertical projection of the light-emitting surface 100a of the light guide plate 100 through the optical microstructure 122D has a back and forth bending shape, which can effectively inhibit the optical film 120E and the two films (for example, the first film 130 and the first film 130). The phenomenon of bright and dark lines between the two 稜鏡 sheets (140) is called moiré pattern. In other words, the light output uniformity of the backlight module 50A can be improved.

Referring to FIG. 9B, the difference between the backlight module 50A-1 of this embodiment and the backlight module 50A of FIG. 9A lies in the configuration of the optical microstructure. In this embodiment, the two vertical projections of any two adjacent ridge lines RL-A of the optical microstructure 122D-1 of the optical film 120E-1 on the light guide plate 100 are presented in mirror images. According to this, the bright and dark lines generated between the optical film 120E-1 and the two slabs (for example, the first slab 130 and the second slab 140) can be further suppressed.

FIG. 10A is a schematic top view of a backlight module according to a fourth embodiment of the present invention. 10B is a schematic top view of the backlight module of the fifth embodiment of the present invention. 10A, the difference between the backlight module 50B of this embodiment and the backlight module 50A of FIG. 9A lies in the configuration of the optical microstructure. In this embodiment, the vertical projection of the ridge line RL-B (that is, the extension path) of the optical microstructure 122E of the optical film 120F on the light exit surface 100a of the light guide plate 100 is wavy. Similar to the optical microstructure 122D of the previous embodiment (as shown in FIG. 9A), in this embodiment, although the extension path of the optical microstructure 122E is wavy (for example, a sin/cosine curve), the extension direction thereof is substantially still It is perpendicular to the light incident surface 100b of the light guide plate 100 (that is, the direction Y). However, the present invention is not limited to this. According to other embodiments, the extension path of the optical microstructure may also be a bending curve with no periodicity. It is worth mentioning that the vertical projection of the light-emitting surface 100a of the light guide plate 100 through the optical microstructure 122E has a curved back and forth shape, which can effectively restrain the optical film 120F and the two ridges (as shown in the first edge of Figure 1). The phenomenon of bright and dark lines generated between the lens 130 and the second lens 140) is a moiré pattern. In other words, the light output uniformity of the backlight module 50B can be improved.

For example, the method of forming the optical microstructure 122E of the optical film 120F may include coating a UV-curing adhesive layer (or other suitable resin layer) on the substrate 121 and using a pre-prepared embossing pattern (such as wave A mold with a shape or a fold line pattern) is embossed on the above-mentioned ultraviolet light hardening adhesive layer, and at the same time, the ultraviolet light hardening adhesive layer located between the mold and the substrate 121 is cured by an ultraviolet light source. However, the present invention is not limited to this. In other embodiments, the method of forming the optical microstructure may also include sculpting the above-mentioned ultraviolet light hardening glue layer by using a cutter with a cutter head with a specific shape. Specifically, during the scribing process of the tool head on the UV-curable adhesive layer, the tool head and the substrate 121 will relatively move in a direction (ie direction X) perpendicular to the travel direction of the tool head (ie direction Y). Accordingly, the wave-like distribution period of the formed optical microstructure in the extending direction can be determined according to the period of the tool head moving back and forth. In another embodiment, when the cutter head is scribing on the UV-curable adhesive layer, the cutter head will move back and forth in the direction perpendicular to the substrate, and the degree of extrusion of the cutter head can produce gourd-like wave accumulation. The configuration is shown in the backlight module 50B-1 of FIG. 10B. That is, the two vertical projections of any two adjacent ridge lines RL-B of the optical microstructure 122E-1 of the optical film 120F-1 on the light guide plate 100 are presented in mirror images. Accordingly, it is possible to further suppress the bright and dark lines generated between the optical film 120F-1 and the two slabs (for example, the first slab 130 and the second slab 140).

FIG. 11 is a schematic diagram of a backlight module according to a sixth embodiment of the present invention. FIG. 12 is a schematic side view of the backlight module of FIG. 11. Fig. 13 is a schematic cross-sectional view of the second sheet of Fig. 11. Please refer to FIGS. 11 to 13, the difference between the backlight module 50C of this embodiment and the backlight module 50 of FIG. 1 lies in the configuration of the second sheet. In this embodiment, the second diffusive sheet 140A further has a second diffusion structure layer 143, which is disposed on the side of the second diffusive sheet 140A facing the first diffusive sheet 130, and overlaps the plurality of diffusive structures 142 in the direction Z .

For example, the second diffusion structure layer 143 of the second film 140A may optionally include a photosensitive adhesive layer 1431 and a plurality of diffusion particles 1432, wherein the diffusion particles 1432 are covered by the photosensitive adhesive layer 1431 (as shown in FIG. 13 Show). In this embodiment, the material of the photosensitive glue layer 1431 is, for example, UV glue or other suitable transparent photosensitive glue. The material of the diffusion particles 1432 may include polymethyl methacrylate (PMMA), polystyrene (PS), or a copolymer of the foregoing materials. On the other hand, in this embodiment, the plurality of diffusion particles 1432 of the second diffusion structure layer 143 may be spherical and have various particle sizes, but the present invention is not limited thereto. In other embodiments, the plurality of diffusion particles 1432 may also have substantially the same particle size. On the other hand, because the second diffusion structure layer 143 (or the second diffusive sheet 140A) has a specific haze value, the backlight module 50C may not be provided with the diffusing sheet 150 as shown in FIG. 1, which helps to reduce production costs. However, the implementation of the second diffusion structure layer of the present invention is not limited to the above-mentioned embodiments, and the second diffusion structure layer may not have diffusion particles, but be implemented in a manner with a microstructured surface.

Fig. 14 is a schematic cross-sectional view of a second scallop sheet according to another embodiment of the present invention. Please refer to FIG. 14, the main difference between the second scallop 140B of this embodiment and the second scallop 140A of FIG. 13 lies in the composition of the scallop structure and the configuration of the second scallop. In this embodiment, the ridge structure 142A of the second ridge piece 140B may include a plurality of diffusion particles 1422. That is, the haze structure 142A may have a specific haze value. On the other hand, the second diffusing structure layer 143 (as shown in FIG. 13) may not be provided on the side of the second diffusive sheet 140B away from the diffusive structure 142A. That is, the haze required by the second ridge sheet 140B is provided by a plurality of ridged structures 142A including diffusion particles 1422. However, the implementation of the second scallop sheet of the present invention is not limited to the above-mentioned embodiments, and the second scallop sheet can also include a second diffusion structure layer with a micro-structured surface and a scallop structure with diffusion particles.

To sum up, in the backlight module of an embodiment of the present invention, the optical film located between the light guide plate and the light guide plate has a plurality of optical microstructures arranged on one side of the light emitting surface of the light guide plate, and passes through it. The extension direction of the optical microstructure intersects the light incident surface of the light guide plate, which can increase the overall light output of the backlight module near the normal viewing angle (that is, it can improve the light collection of the backlight module). On the other hand, the diffusion structure layer is provided on the side far away from the optical microstructure through the optical film, which can improve the concealability of the backlight module, thereby improving the assembly yield of the backlight module. In other words, the process latitude of each component of the backlight module can also be increased.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present invention. The scope of protection of the present invention shall be determined by the scope of the attached patent application.

50, 50A~50C: backlight module 100: light guide plate 100a: Glossy surface 100b: Light incident surface 100c: bottom surface 110: light source 120, 120A~120F: optical film 121, 131, 141: substrate 121a: Light incident side 121b: light emitting side 122, 122A~122E: Optical microstructure 122s1, 122s2: inclined plane 1222, 1232, 1422, 1432: diffuse particles 123, 123A, 123B: the first diffusion structure layer 123s: surface 1231, 1431: photosensitive layer 130: The First Snapshot 132, 142, 142A: 稜鏡 structure 140, 140A, 140B: the second slice 143: second diffusion structure layer 150: diffuser 160: reflective sheet IL: Virtual straight line RL, RL-A, RL-B: ridge X, Y, Z: direction: θ: vertex angle

Fig. 1 is a schematic diagram of a backlight module according to a first embodiment of the present invention. FIG. 2 is a schematic side view of the backlight module of FIG. 1. FIG. 3 is a schematic top view of the backlight module of FIG. 1. Fig. 4 is a schematic cross-sectional view of the optical film of Fig. 1. 5 to 8 are schematic cross-sectional views of optical films according to other embodiments of the present invention. FIG. 9A is a schematic top view of the backlight module of the second embodiment of the present invention. FIG. 9B is a schematic top view of the backlight module of the third embodiment of the present invention. FIG. 10A is a schematic top view of a backlight module according to a fourth embodiment of the present invention. 10B is a schematic top view of the backlight module of the fifth embodiment of the present invention. FIG. 11 is a schematic diagram of a backlight module according to a sixth embodiment of the present invention. FIG. 12 is a schematic side view of the backlight module of FIG. 11. Fig. 13 is a schematic cross-sectional view of the second sheet of Fig. 11. Fig. 14 is a schematic cross-sectional view of a second scallop sheet according to another embodiment of the present invention.

50: Backlight module

100: light guide plate

100a: Glossy surface

100b: Light incident surface

100c: bottom surface

110: light source

120: Optical diaphragm

121, 131, 141: substrate

121a: Light incident side

121b: light emitting side

122: Optical Microstructure

123: The first diffusion structure layer

130: The First Snapshot

132, 142: 稜鏡 structure

140: The second 稜鏡 piece

150: diffuser

160: reflective sheet

X, Y, Z: direction

Claims (10)

A backlight module includes: A light guide plate with a light-emitting surface and a light-incident surface connected; A light source arranged on one side of the light incident surface of the light guide plate; An optical film is overlapped and arranged on the light emitting surface of the light guide plate, and the optical film includes: A substrate having a light entrance side and a light exit side opposite to each other, wherein the light entrance side faces the light guide plate; A plurality of optical microstructures are arranged on the light incident side of the substrate, wherein the extending directions of the optical microstructures intersect the light incident surface of the light guide plate; and A first diffusion structure layer disposed on the light emitting side of the substrate and overlapping the optical microstructures; and A first optical film and a second optical film are overlapped and disposed on the optical film, and each has a plurality of optical film structures, the first optical film and the second optical film are located on the light emitting side of the substrate, and the The first ridge is located between the optical film and the second ridge, wherein the extension directions of the ridge structures of the first ridge piece intersect with the extension directions of the ridge structures of the second ridge plate. The backlight module according to the first item of the scope of patent application, wherein the extension direction of the optical microstructures of the optical film is perpendicular to the light incident surface of the light guide plate. The backlight module according to the first item of the scope of patent application, wherein the optical microstructures of the optical film include a plurality of diffusion particles. According to the backlight module described in item 1 of the scope of patent application, the cross section of each of the optical microstructures of the optical film is triangular, arc-shaped or polygonal. The backlight module according to the first item of the scope of patent application, wherein the vertical projection of the extension path of each optical microstructure of the optical film on the light emitting surface of the light guide plate is wavy or folded. According to the backlight module of claim 1, wherein the material of the first diffusion structure layer includes a plurality of diffusion particles. According to the backlight module described in claim 1, wherein a surface of the first diffusion structure layer has a microstructure. The backlight module according to the first item of the scope of patent application, wherein the second diffusive sheet further has a second diffusion structure layer disposed on the side of the second diffusive sheet facing the first diffusive sheet. The backlight module according to the first item of the scope of patent application, wherein the ridge structure of the second ridge sheet includes a plurality of diffusion particles. According to the backlight module described in claim 1, wherein the refractive index of the ridge structures of the first ridge sheet and the second ridge sheet is between 1.62 and 1.75.

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