CN101413641A - Light guide plate and backlight module - Google Patents

Abstract

The invention relates to a light guide plate and a backlight module. The body is provided with a bottom surface, a light-emitting surface opposite to the bottom surface and a plurality of side surfaces connected between the bottom surface and the light-emitting surface, the light-emitting surface is provided with a central area and at least one peripheral area, and the peripheral area is positioned outside the central area. The prism microstructures are positioned on the light-emitting surface and the bottom surface, wherein the prism microstructures positioned on the light-emitting surface comprise a plurality of first prism microstructures and a plurality of second prism microstructures. The first prism microstructures are located in the central region, and the second prism microstructures are located in the peripheral region. Vertex angle theta of second prism microstructure₂Greater than the apex angle theta of the first prism microstructure₁. The backlight module is provided with the light guide plate. The invention is arranged on the light emergent surface of the light guide platePrism microstructures are formed on the light emitting surface and the bottom surface, and the prism microstructures on the light emitting surface have different vertex angles, so that high light emitting efficiency and a good visual angle effect are achieved.

Description

Light guide plate and backlight module

technical field

The invention relates to a light guide plate and a backlight module, in particular to a light guide plate with prism microstructures on both sides and a backlight module using the light guide plate.

Background technique

A liquid crystal display mainly includes two parts: a liquid crystal display panel and a backlight module. The liquid crystal display panel is used to provide the display function of the liquid crystal display, and the backlight module is used to provide the light source. The structure of the backlight module can be divided into two types: a direct-type backlight module and an edge-type backlight module. In an edge-lit backlight module, a light guide plate is usually used. The function of the light guide plate is to mix the light emitted by the side light source to form a uniform surface light source.

Most of the existing light guide plates are made by using screen printing to form the light diffusion structure, and there are also technologies that use laser dots or etching to form the light diffusion structure. Although the above method can provide a good viewing angle, it has the disadvantage of insufficient brightness.

In addition to the above-mentioned technologies for forming light diffusion structures, there is another technology for making light guide plates called double V technology (Double V). The so-called double V technology is to form microstructures with light diffusion effect on the light emitting surface and the bottom surface of the light guide plate respectively, so as to achieve the light mixing effect of the light guide plate. However, although the double-V technology can increase the light output brightness of the light guide plate and reduce the cost, its viewing angle is smaller than that of other light guide plates that use methods such as dot printing to form light diffusion structures.

Contents of the invention

The object of the present invention is to provide a light guide plate with better light extraction efficiency, less restriction of viewing angle and more uniform light mixing.

Another object of the present invention is to provide a backlight module, which uses the aforementioned light guide plate to provide better quality backlight.

The invention provides a light guide plate, which includes a body and a plurality of prism microstructures. The body has a bottom surface, a light-emitting surface opposite to the bottom surface, and multiple side surfaces connected between the bottom surface and the light-emitting surface. The light-emitting surface has a central area and at least one peripheral area, and the peripheral area is located outside the central area. The prism microstructures are located on the light exit surface and the bottom surface, wherein the prism microstructures on the light exit surface include a plurality of first prism microstructures and a plurality of second prism microstructures. Wherein, the first prism microstructure is located in the central area, and the second prism microstructure is located in the peripheral area, and the apex angle θ ₂ of the second prism microstructure is larger than the apex angle θ ₁ of the first prism microstructure.

The present invention also proposes a backlight module, comprising the above-mentioned light guide plate and a light source group, wherein the light source group is arranged beside at least one side of the body of the light guide plate, and is suitable for emitting a light, and the light enters the body from the side.

The beneficial technical effect of the present invention is that the present invention forms prism microstructures on both the light exit surface and the bottom surface of the light guide plate, and makes the prism microstructures on the light exit surface have different apex angles, so as to achieve higher light extraction efficiency and better perspective effect. In addition, the prism microstructure on the bottom of the light guide plate can be adjusted in height or depth according to different regions of the light-emitting surface, so that the problem of low light-extracting efficiency in some regions of the light-emitting surface with prism microstructures with large vertex angles can also be solved at the same time. compensate. The backlight module using the above-mentioned light guide plate can also provide better quality backlight, thereby improving the display quality of the liquid crystal display.

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

Description of drawings

FIG. 1A is a schematic diagram of a light guide plate according to an embodiment of the present invention.

FIG. 1B is a top view of the light emitting surface of the light guide plate in FIG. 1A .

FIG. 2A is a schematic diagram of a light guide plate according to another embodiment of the present invention.

FIG. 2B is a top view of the light emitting surface of the light guide plate in FIG. 2A .

Fig. 3 is a schematic diagram of another embodiment along the line I-I' in Fig. 1A.

FIG. 4A is a schematic diagram of a light guide plate according to another embodiment of the present invention.

Fig. 4B is a sectional view of line II-II' in Fig. 4A.

5A and 5B are respectively two other forms of light guide plate bodies.

FIG. 6 is a schematic diagram of a backlight module according to an embodiment of the present invention.

FIG. 7 is a schematic diagram of a backlight module according to another embodiment of the present invention.

FIG. 8 is a schematic diagram of a backlight module according to yet another embodiment of the present invention.

FIG. 9 is a schematic diagram of a backlight module according to another embodiment of the present invention.

Wherein, the reference signs are explained as follows:

100, 200, 300a, 300b, 400a, 400b, 510, 610, 710, 810: light guide plate

110, 210, 310, 510a, 610a, 610b, 610c: main body

112, 212, 312, 513, 613: bottom surface

114, 214, 314, 512c, 612c: light-emitting surface

114a, 214a, 314a: central area

114b, 214b, 314b: peripheral area

116, 216, 316, 512a, 612a, 612b: side

120, 220, 320, 513a, 513b, 613a, 613b: Prism microstructure

120a: Triangular prism

122, 222: The first prism microstructure 124, 224: The second prism microstructure

128, 228: Fourth prism microstructure 214c: Buffer area

226: Third prism microstructure 320a: V-groove

500, 600, 700, 800: backlight module 520, 620, 720, 820: light source group

h ₁ , h ₂ : height v ₁ , v ₂ : depth

Detailed ways

FIG. 1A is a schematic diagram of a light guide plate according to an embodiment of the present invention. FIG. 1B is a top view of the light emitting surface of the light guide plate in FIG. 1A . Please refer to FIG. 1A , the light guide plate 100 of this embodiment includes a body 110 and a plurality of prism microstructures 120 . The body 110 has a bottom surface 112 , a light-emitting surface 114 opposite to the bottom surface 112 , and a plurality of side surfaces 116 connected between the bottom surface 112 and the light-emitting surface 114 . As shown in FIG. 1A , the prism microstructures 120 on the bottom surface 112 in this embodiment can be arranged at intervals, and can also be adjusted according to actual needs, for example, the prism microstructures 120 on the bottom surface 112 are arranged continuously. Referring to FIG. 1B , the light-emitting surface 114 has a central region 114 a and at least one peripheral region 114 b, and the peripheral region 114 b is located outside the central region 114 a. In this embodiment, two peripheral regions 114 b are shown, and the peripheral regions 114 b are defined to be located at the outermost edge of the light-emitting surface 114 . However, the central area 114a and the peripheral area 114b shown in this embodiment are only for example, and the present invention does not limit the shape of the central area 114a and the peripheral area 114b and their ratio on the main body 110 , actual position and quantity.

Please refer to FIG. 1A again, the prism microstructure 120 is located on the light exit surface 114 and the bottom surface 112, wherein the prism microstructure 120 located on the light exit surface 114 may include multiple first prism microstructures 122 and multiple The second prism microstructure 124 . The first prism microstructure 122 is located in the central region 114a, and the second prism microstructure 124 is located in the peripheral region 114b, and the apex angle θ ₂ of the second prism microstructure 124 is greater than the apex angle θ ₁ of the first prism microstructure 122 . In this embodiment, the width of the bottom of the first prism microstructure 122 is substantially equal to the width of the bottom of the second prism microstructure 124 . In other embodiments of the present invention, the height of the first prism microstructure 122 is substantially the same as the height of the second prism microstructure 124 . However, the first prism microstructures 122 and the second prism microstructures 124 shown in this embodiment are only examples, and the present invention does not limit the number, size ratio and distribution ratio of the prism microstructures on the light-emitting surface, etc. .

In other words, in this embodiment, the first prism microstructure 122 and the second prism microstructure 124 with different apex angles are formed on the light-emitting surface 114 of the light guide plate 100, wherein the first prism microstructure 122 with a smaller apex angle can provide a higher Excellent light extraction efficiency, and the second prism microstructure 124 with a larger vertex angle can achieve a wider viewing angle effect. Therefore, in this embodiment, the first prism microstructure 122 is selected to be disposed in the central region 114 a of the light-emitting surface 114 , so as to effectively improve the overall light-emitting efficiency of the light guide plate 100 . In addition, because the peripheral region 114b of the light-emitting surface 114 is more prone to viewing angle problems, the second prism microstructure 124 that can achieve a wider viewing angle effect is disposed in the peripheral region 114b. In this way, the light guide plate 100 of this embodiment mixes two kinds of prism microstructures 122 and 124 with different properties, which can provide good light extraction efficiency and viewing angle effect.

In practice, the apex angle _θ1 of the first prism microstructure 122 is preferably between 85 degrees and 105 degrees. In addition, the prism microstructure 120 on the light emitting surface 114 is, for example, a plurality of parallel triangular prisms, and the prism microstructure 120 on the bottom surface 112 may also be a plurality of parallel triangular prisms. In a preferred embodiment, the triangular prism on the light-emitting surface 114 is substantially orthogonal to the triangular prism on the bottom surface 112 .

In addition to the above-mentioned embodiments, the present invention can also perform other designs on the change of the vertex angle or the arrangement and combination of the prism microstructures on the light-emitting surface, which are further described as follows.

FIG. 2A is a schematic diagram of a light guide plate according to another embodiment of the present invention. FIG. 2B is a top view of the light emitting surface of the light guide plate in FIG. 2A . Please refer to FIG. 2A, the light guide plate 200 of this embodiment is similar in structure to the light guide plate 100 of the above-mentioned embodiment, and the main difference between the two is that the light guide plate 200 of this embodiment is on the light exit surface 214, and can be further There is a buffer area 214c. Referring to FIG. 2B, the buffer region 214c is between the central region 214a and the peripheral region 214b, the buffer region 214c has a plurality of third prism microstructures 226, and the apex angles of the third prism microstructures 226 are between the first prism microstructures 222. Between the vertex angle θ ₁ of the second prism microstructure 224 and the vertex angle θ ₂ of the second prism microstructure 224. As shown in FIG. 2A , in this embodiment, the bottom width of the first prism microstructure 222 , the bottom width of the second prism microstructure 224 , and the bottom width of the third prism microstructure 226 are substantially equal. In another embodiment of the present invention, the height of the first prism microstructure 222 , the height of the second prism microstructure 224 and the height of the third prism microstructure 226 are substantially equal. The first prism microstructures 122 , the second prism microstructures 124 and the third prism microstructures 226 are just examples, and the present invention does not limit the number, size ratio and distribution ratio of the prism microstructures on the light-emitting surface.

In this embodiment, a buffer region 214c is added between the central region 214a and the peripheral region 214b to ease the boundary effect between the central region 214a and the peripheral region 214b, so that the light output from the light guide plate 200 is more uniform.

In addition, the prism microstructures in the buffer region 214c may also be composed of third prism microstructures 226 with different apex angles. That is to say, the third prism microstructure 226 can have various apex angles. For example, in addition to the prism microstructure 226 with an apex angle of _θ3 , multiple prism microstructures with an apex angle of _θ4 can be further arranged in the buffer region 214c. a third prism microstructure 226, and θ ₄ is greater than θ ₃ .

In addition, in the present embodiment, the distribution density of the third prism microstructures 226 in the buffer region 214c may also vary according to the difference of the apex angles thereof. For example, the distribution density of the third prism microstructures 226 with an apex angle of _θ4 in the buffer region 214c gradually increases from the central region 214a toward the peripheral region 214b.

Making the distribution density of the third prism microstructures 226 with a larger vertex angle _θ4 in the buffer region 214c gradually increase from the central region 214a toward the peripheral region 214b will help to improve the obvious viewing angle problem of the peripheral region 214b, and avoid excessive It affects the light extraction efficiency of the central region 214a and can effectively improve the boundary problem. Of course, in other embodiments, the distribution density of the third prism microstructures 226 with a smaller vertex angle _θ3 can also be selected to adjust the overall light extraction efficiency and viewing angle effect of the light guide plate 200 .

In addition to the above-mentioned methods, other embodiments of the present invention can also change the apex angle of the third prism microstructure 226 in the buffer region 214c, so that the apex angle of the third prism microstructure 226 changes gradually with different positions, for example, making the third prism microstructure The vertex angle of 226 gradually increases from the central region 214a toward the peripheral region 214b, which can also achieve the effect of improving light extraction efficiency and viewing angle.

It is worth mentioning that the prism microstructures in the peripheral area of the light guide plate of the present invention may also be composed of prism microstructures with different apex angles. As for the foregoing embodiments, the prism microstructures in the peripheral region 114b of the light guide plate 100 in FIG. 1A or the peripheral region 214b of the light guide plate 200 in FIG. 2A may have different apex angles. In other words, in addition to the second prism microstructure 124 or 224 having an apex angle of _θ2 , the peripheral region 114b or 214b may also have a fourth prism microstructure 128 or 228 having an apex angle between _θ1 and _θ2 , for example. . Wherein, the vertex angle or distribution density located in the peripheral area 114b or 214b may also have the same changes as above according to the requirements of light extraction efficiency or viewing angle, and will not be repeated here.

In addition to the above-mentioned embodiments, the present invention can further design the prism microstructure on the bottom surface of the light guide plate so that it has a high (depth) degree or a change in distribution density. A number of embodiments are given below for further description.

Fig. 3 is a schematic diagram of another embodiment along the line I-I' in Fig. 1A. FIG. 4A is a schematic diagram of a light guide plate according to another embodiment of the present invention. Fig. 4B is a sectional view of line II-II' in Fig. 4A. The cross-sectional direction in FIG. 3 and FIG. 4B is parallel to the extension direction of the prism microstructures on the bottom surface of the light guide plate, and passes through the center of a prism microstructure on the bottom surface to clearly express the height variation of the prism microstructures on the bottom surface of the light guide plate. In order to simplify the drawings, FIG. 3 and FIG. 4B do not show in detail the many changes of the prism microstructures on the light-emitting surface, and for these contents, reference may be made to the descriptions of the foregoing embodiments.

Referring to FIG. 3 , the light guide plate 100a of this embodiment is structurally similar to the light guide plate 100 or 200 of the above-mentioned embodiments, so no more description will be given on these similarities or mutual substitutions. Likewise, the prism microstructures 120 on the bottom surface 112 of the light guide plate 100 a of this embodiment are triangular prisms parallel to each other as shown in the previous embodiments. A triangular prism 120a on the bottom surface 112 itself may have different heights. For example, each triangular prism 120a on the bottom surface 112 has a third corresponding to the central region 114a of the light-emitting surface 114 compared with the bottom surface 112. A height h ₁ and a second height h ₂ corresponding to the peripheral region 114 b of the light-emitting surface 114 , wherein the second height h ₂ is greater than the first height h ₁ .

In addition, please refer to FIG. 4A and FIG. 4B at the same time. The structure of the light guide plate 300 of this embodiment is similar to that of the light guide plate 100 or 200 of the above-mentioned embodiment, so no further description will be given on these similarities or mutual substitutions. It is worth noting that the prism microstructures 320 on the bottom surface 312 of the light guide plate 300 in this embodiment are V-shaped grooves 320a parallel to each other, and the V-shaped grooves 320a are substantially orthogonal to the light-emitting surface 314 formed by triangular prisms. Prism microstructure 320 . A V-shaped groove 320a on the bottom surface 312 itself may have different depths. For example, compared with the bottom surface 312, each V-shaped groove 320a has a first depth _v1 corresponding to the central region 314a of the light-emitting surface 314 and Corresponding to the second depth v ₂ of the peripheral region 314 b of the light-emitting surface 314 , and the second depth v ₂ is greater than the first depth v ₁ .

Based on the above, the embodiment shown in FIGS. 3 and 4B adjusts the height of the triangular prism 120a or the depth of the V-shaped groove 320a on the bottom surface 112, 312 according to the characteristics of the prism microstructure on the light-emitting surface 114, 314, Therefore, the problem of narrower viewing angles that may be caused by the prism microstructures with smaller apex angles on the central regions 114a and 314a can be improved, and the problem of lower light extraction efficiency that may be caused by the prism microstructures with larger apex angles on the peripheral regions 114b and 314b can be improved. problem, to achieve the effect of compensation.

The bodies 110 , 210 , 310 of the light guide plates 100 , 100 a , 200 , 300 shown in the foregoing embodiments are all parallel plates. However, in fact, the present invention can also use other different types of plates to make the light guide plates. 5A and 5B illustrate two other forms of light guide plate bodies 410a and 410b respectively, wherein the light guide plate body 410a in FIG. 5A is wedge-shaped, and the thickness of the light guide plate body 410b in FIG. 5B gradually decreases from the periphery to the center. In addition, the microprism structures disclosed in the foregoing or other embodiments can be fabricated on the light guide plate body 410 a of FIG. 5A and the light guide plate body 410 b of FIG. 5B . The description of the microprism structure will not be repeated here, and details can be found in relevant descriptions in this specification.

The present invention further proposes a backlight module using the aforementioned light guide plates. FIG. 6 is a schematic diagram of a backlight module according to an embodiment of the present invention. Please refer to FIG. 6 , the backlight module 500 of this embodiment includes a light guide plate 510 and a light source group 520 . The light guide plate 510 here can adopt the light guide plate 100 , 100 a , 200 , 300 described above or other possible structures of the light guide plate in the present invention, and these similarities or interchangeable parts will not be further described. In addition, a side surface 512a of the main body 510a of the light guide plate 510 is used as a light incident surface, and the light source group 520 is a strip light source disposed beside the side surface 512a. The light source group 520 is suitable for emitting a light, and the light enters the light guide plate 510 from the side 512a. In this embodiment, on a projection plane parallel to the light-emitting surface 512c, the extending direction of the light source group 520 is substantially perpendicular to the extending direction of the prism microstructure 513b on the light-emitting surface 512c, that is, the side 512a serving as the light-incident surface The extending direction of the normal line is substantially parallel to the extending direction of the prism microstructure 513b on the light emitting surface 512c.

FIG. 7 is a schematic diagram of a backlight module according to another embodiment of the present invention. Please refer to FIG. 7 , the backlight module 600 of this embodiment includes a light guide plate 610 and a light source group 620 . The light guide plate 610 here can also adopt the light guide plate 100 , 100 a , 200 , 300 described above or other possible structures of the light guide plate of the present invention, and these similar or interchangeable parts will not be further described. In addition, the two opposite sides 612a and 612b of the main body 610a of the light guide plate 610 are used as light incident surfaces, and the light source group 620 includes two strip light sources, which are respectively disposed beside the two sides 612a and 612b. The light source group 620 is suitable for emitting light into the light guide plate 610 from the side surfaces 612 a and 612 b. It should be noted that in this embodiment, on a projection plane parallel to the light-emitting surface 612c, the extension direction of the light source group 620 is substantially perpendicular to the extension direction of the prism microstructure 613b on the light-emitting surface 612c, that is, as the light-incident surface The extension direction of the normal line of the side surface 612a or 612b is substantially parallel to the extension direction of the prism microstructure 613b of the light-emitting surface 512b.

In the above-mentioned multiple embodiments, considering the light source attenuation problem that the light guide plate 510 or 610 is far away from the light source group 520 or 620, it can be designed so that the distribution density of the prism microstructures 513a or 613a on the bottom surface 513 or 613 is along the The prism microstructure 513a in FIG. 6 increases along a single direction, and the prism microstructure 613a in FIG. 7 is from the two light incident surfaces 612a and 612b toward the light guide plate 610 The center of the center increases gradually, so as to improve the light extraction efficiency farther away from the light source group 520 or 620 .

In addition, it can be known from the aforementioned implementation that the height and depth of the prism microstructures on the bottom surface 513 or 613 of the light guide plate 510 or 610 or the distribution density of the prism microstructures in other parts will also affect the light extraction efficiency, so it can also be based on the light source group 520 or 620 Configuration approach to design prism microstructures. For example, the height or depth of the prism microstructure 513a or 613a on the bottom surface 513 or 613 increases along the direction away from the light incident surface 512a, 612a or 612b, that is, the farther away from the light source, the more obvious the microstructure at the bottom of the light guide plate, and the prism The change of the microstructure is just an example and can be adjusted according to actual needs. In addition, the bar-shaped light source can be a fluorescent tube, an LED light bar or other similar light sources, but is not limited thereto, and its type can be adjusted according to actual needs.

FIG. 8 is a schematic diagram of a backlight module according to yet another embodiment of the present invention. FIG. 9 is a schematic diagram of a backlight module according to another embodiment of the present invention. Please refer to FIG. 8 and FIG. 9 at the same time. The backlight module 700 is structurally similar to the backlight module 600 in FIG. 7 , and the backlight module 800 is structurally similar to the backlight module 500 in FIG. 6 . Therefore, the same components are marked with the same reference numerals, and the biggest difference lies in the shape of the body of the backlight modules 700 , 800 . The thickness of the light guide plate body 610b of the backlight module 700 in FIG. 8 gradually decreases from the periphery to the center. The shape of the light guide plate body 610c of the backlight module 800 in FIG. 9 is a wedge.

In addition, similar to the backlight module 600 in FIG. 7 , the arrangement density of the prism microstructures 613a on the bottom surface 613 of the backlight module 700 in FIG. Incrementally, in addition, similar to the backlight module 500 in FIG. 6 , the arrangement density of the prism microstructures 613a on the bottom surface 613 of the backlight module 800 in FIG. 9 increases gradually toward the direction away from the light source. In this way, the arrangement of the above-mentioned microstructures is sparse and dense, so as to improve the light extraction efficiency farther away from the light source group 620 .

In summary, the present invention fabricates prism microstructures on the light guide plate, wherein the light emitting surface of the light guide plate has a variety of prism microstructures with different apex angles, and a buffer zone can be further designed to improve the light output efficiency of the light guide plate And the viewing angle problem is improved. In addition, the prism microstructure on the bottom of the light guide plate can be adjusted in height or depth according to different regions of the light-emitting surface, so that the problem of low light-extracting efficiency in some regions of the light-emitting surface with prism microstructures with large vertex angles can also be solved at the same time. compensate. In addition, for the backlight module with the above-mentioned light guide plate structure, the height, depth, or distribution density of the prism microstructures on the light guide plate will also change in accordance with the configuration of the light source. Compared with the backlight module using the existing light guide plate, its The light extraction efficiency is better, and the light mixing is more uniform.

Although the present invention has been disclosed above with embodiments, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined by the appended claims.

Claims (19)

1. A light guide plate, comprising: A body has a bottom surface, a light-emitting surface opposite to the bottom surface, and a plurality of side surfaces connected between the bottom surface and the light-emitting surface, the light-emitting surface has a central area and at least one peripheral area, and the peripheral area is located on the outside the central area; and A plurality of prism microstructures located on the light exit surface and the bottom surface, wherein the plurality of prism microstructures on the light exit surface include a plurality of first prism microstructures and a plurality of second prism microstructures, the plurality of The first prism microstructure is located in the central region, the plurality of second prism microstructures are located in the peripheral region, and the apex angle _θ of the plurality of second prism microstructures is greater than that of the plurality of first prism microstructures. The vertex angle θ ₁ of the structure. 2. The light guide plate according to claim 1, wherein the plurality of prism microstructures on the bottom surface are arranged at intervals. 3. The light guide plate as claimed in claim 1, wherein the apex angle _θ1 of the plurality of first prism microstructures is between 85° and 105°. 4. The light guide plate according to claim 1, wherein the light-emitting surface further has a buffer region, the buffer region is between the central region and the peripheral region, and the plurality of prism microstructures on the light-emitting surface It also includes a plurality of third prism microstructures, the plurality of third prism microstructures are located in the buffer region, and the apex angles of the plurality of third prism microstructures are between θ ₁ and θ ₂ . 5. The light guide plate as claimed in claim 4, wherein said plurality of third prism microstructures is composed of a plurality of prism microstructures with an apex angle of θ ₃ and a plurality of prism microstructures with an apex angle of θ ₄ , and θ ₄ is greater than θ ₃ . 6. The light guide plate as claimed in claim 5, wherein the distribution density of the plurality of prism microstructures with an apex angle of _θ4 in the buffer region gradually increases from the central region to the peripheral region. 7. The light guide plate as claimed in claim 4, wherein apex angles of the plurality of third prism microstructures gradually increase from the central area toward the peripheral area. 8. The light guide plate according to claim 1, wherein the plurality of prism microstructures on the light-emitting surface further comprise a plurality of fourth prism microstructures, and the plurality of fourth prism microstructures are located in the peripheral region, And the apex angles of the plurality of fourth prism microstructures are between _θ1 and _θ2 . 9. The light guide plate according to claim 1, wherein the plurality of prism microstructures on the light emitting surface comprise a plurality of triangular prisms, and the plurality of triangular prisms are parallel to each other. 10. The light guide plate according to claim 9, wherein the plurality of prism microstructures on the bottom surface comprise a plurality of triangular prisms, and the plurality of triangular prisms on the bottom surface are parallel to each other. 11. The light guide plate according to claim 10, wherein the plurality of triangular prisms on the light emitting surface are substantially perpendicular to the plurality of triangular prisms on the bottom surface. 12. The light guide plate according to claim 10, wherein, compared with the bottom surface, the plurality of triangular prisms on the bottom surface respectively have a first height corresponding to the central region and a first height corresponding to the peripheral region A second height, and the second height is greater than the first height. 13. The light guide plate according to claim 9, wherein the plurality of prism microstructures on the bottom surface comprise a plurality of V-shaped grooves, and the plurality of V-shaped grooves are parallel to each other. 14. The light guide plate according to claim 13, wherein the plurality of triangular prisms on the light emitting surface are substantially perpendicular to the plurality of V-shaped grooves on the bottom surface. 15. The light guide plate as claimed in claim 13, wherein, compared with the bottom surface, the plurality of V-shaped grooves on the bottom surface respectively have a first depth corresponding to the central region and a depth corresponding to the peripheral region a second depth, and the second depth is greater than the first depth. 16. The light guide plate according to claim 1, wherein at least one of the plurality of side surfaces serves as a light incident surface, and the distribution density of the plurality of prism microstructures on the bottom surface is along the direction away from the light incident surface. The direction of the face increases. 17. The light guide plate according to claim 1, wherein at least one of the plurality of side surfaces serves as a light incident surface, and the height or depth of the plurality of prism microstructures on the bottom surface is along the direction away from the incident surface. The direction of the glossy surface is incremented. 18. A backlight module, comprising: A light guide plate, comprising: A body has a bottom surface, a light-emitting surface opposite to the bottom surface, and a plurality of side surfaces connected between the bottom surface and the light-emitting surface. The light-emitting surface has a central area and at least one peripheral area, and the peripheral area is located in the central area. outside the area; and A plurality of prism microstructures located on the light exit surface and the bottom surface, wherein the plurality of prism microstructures on the light exit surface include a plurality of first prism microstructures and a plurality of second prism microstructures, the plurality of The first prism microstructure is located in the central region, the plurality of second prism microstructures are located in the peripheral region, and the apex angle _θ of the plurality of second prism microstructures is greater than that of the plurality of first prism microstructures. the apex angle θ ₁ of the structure; and A light source group is arranged beside at least one side of the main body, the light source group is suitable for emitting a light, and the light enters the main body from the at least one side. 19. The backlight module as claimed in claim 18, wherein on a projection plane parallel to the light-emitting surface, the extending direction of the light source group is substantially perpendicular to the extending direction of the plurality of prism microstructures on the light-emitting surface.

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