TWM535330U - Light guide plate, backlight module and display apparatus - Google Patents

Abstract

A light guide plate including a light guide main body and an index matching layer is provided. The light guide main body has a light emitting surface and a bottom surface opposite to the light emitting surface. The index matching layer is disposed adjacent to the bottom surface, wherein a refraction index of the light guide main body is n1, and a refraction index of the index matching layer is n2. 1.07*n2 ≤ n1 ≤ 1.7*n2, and 0.1 ≤ (n1-n2) ≤ 0.7. A thickness of the index matching layer is larger than 500nm. A backlight module and a display apparatus are also provided.

Description

Light guide plate, backlight module and display device

The present invention relates to an optical component, an optical module, and an electronic device, and more particularly to a light guide plate, a backlight module, and a display device.

In general, the backlight module can be divided into a direct type backlight module and a side-in type backlight module. The side-entry backlight module generally includes a light source and a light guide plate, wherein the light source is disposed at a side of the light guide plate. The light beam emitted from the light source enters the light guide plate from the side of the light guide plate, and is transmitted to the light guide plate via total reflection. Compared with the direct type backlight module, the side-in type backlight module can reduce the usage of the light-emitting elements in the light source, thereby having the advantage of low power consumption. However, the current side-entry backlight module still has problems such as color shift or insufficient structural strength of the light guide plate, and all of the above may have a negative impact on the illumination quality of the backlight module, thereby affecting the display of the application side-lit backlight module. The display quality of the device.

The novel creation provides a light guide plate that contributes to the formation of total reflection or Helps increase structural strength.

The novel creation provides a backlight module with good illumination quality.

The novel creation provides a display device that has good display quality.

A light guide plate of an embodiment of the present invention includes a light guiding body and an index matching layer. The light guiding body has a light emitting surface and a bottom surface opposite to the light emitting surface. The index matching layer is disposed adjacent to the bottom surface, wherein the refractive index of the light guiding body is n1, and the refractive index of the index matching layer is n2. 1.07*n2≦n1≦1.7*n2, and 0.1≦(n1-n2)≦0.7. The thickness of the index matching layer is greater than 500 nm.

A backlight module of an embodiment of the present invention includes a light guide plate, a light source, and a reflective sheet. The light guide plate includes a light guiding body and an index matching layer. The light guiding body has a light emitting surface, a bottom surface opposite to the light emitting surface, and a light incident surface that connects the light emitting surface and the bottom surface. The index matching layer is disposed adjacent to the bottom surface, and the index matching layer is located between the reflective sheet and the light guiding body, wherein the refractive index of the light guiding body is n1, and the refractive index of the index matching layer is n2. 1.07*n2≦n1≦ 1.7*n2, and 0.1≦(n1-n2)≦0.7. The thickness of the index matching layer is greater than 500 nm. The light source is placed beside the entrance surface.

A display device according to an embodiment of the present invention includes the backlight module and the display panel, wherein the display panel is disposed adjacent to the light emitting surface.

Based on the above, the embodiments of the present novel creation have at least one of the following advantages or effects. In the light guide plate of the embodiment of the present invention, the refractive index difference between the light guiding body and the index matching layer is matched with the thickness of the index matching layer to contribute to the formation of total reflection. In an embodiment, the index matching layer can be used to support the light guiding body, thereby enhancing the structural strength of the light guiding plate. In addition, the backlight of the embodiment of the novel creation The module can have good illumination quality by applying the above-mentioned light guide plate. The display device of the embodiment of the present invention can have good display quality by applying the backlight module described above.

The above described features and advantages of the present invention will become more apparent and understood from the following description.

100, 200, 300, 400, 500, 600, 700‧‧‧ backlight modules

110, 110A, 110B‧‧‧ light guide plate

112, 112A‧‧‧Lighting body

114, 114A, 114B‧‧‧ index matching layer

120‧‧‧Light source

130‧‧‧reflector

140‧‧‧Optical diaphragm

AD1, AD2‧‧‧ adhesive layer

D‧‧‧ Extension direction

H112, H114, HAD2, HI1, HI2‧‧‧ thickness

HS‧‧‧shell

I1‧‧‧First refractive index layer

I2‧‧‧second refractive index layer

N1‧‧‧Nano columnar void

N2‧‧‧Nami Hole

N3‧‧‧Surface Nano Hole

SB‧‧‧ bottom

SE‧‧‧Glossy

SI‧‧‧Into the glossy surface

SR‧‧‧Side reflector

SS‧‧‧ side

1 is a cross-sectional view of a backlight module in accordance with a first embodiment of the present invention.

2A to 2C are respectively a first to third partial enlarged schematic views of the index matching layer of Fig. 1.

3 and 4 are graphs showing the relationship between the thickness of the index matching layer and the reflectance of visible light at different refractive index differences, respectively.

5 to 8 are schematic cross-sectional views of a backlight module according to second to fifth embodiments of the present invention.

9 and 10 respectively show simulation results of the reflectance of the backlight module in which only the refractive index matching layer and the refractive index matching layer, the first refractive index layer, and the second refractive index layer are provided.

11 and 12 are schematic top views of a backlight module according to a sixth embodiment and a seventh embodiment of the present invention, respectively.

1 is a cross-sectional view of a backlight module in accordance with a first embodiment of the present invention. 2A to 2C are respectively a first to third partial enlarged schematic views of the index matching layer of Fig. 1.

Referring first to FIG. 1 , the backlight module 100 includes a light guide plate 110 , a light source 120 , and a reflective sheet 130 . The light guide plate 110 includes a light guiding body 112 and an index matching layer 114. The light guiding body 112 has a light emitting surface SE, a bottom surface SB, and a light incident surface SI. The bottom surface SB is opposite to the light emitting surface SE, and the light incident surface SI is connected to the light surface SE and the bottom surface SB. A plurality of light guiding microstructures or a plurality of dots may be formed on at least one of the light emitting surface SE and the bottom surface SB of the light guiding body 112, but not limited thereto.

The index matching layer 114 is disposed adjacent to the bottom surface SB, and the index matching layer 114 is located between the reflective sheet 130 and the light guiding body 112. In the present embodiment, the index matching layer 114 is formed on the bottom surface SB of the light guiding body 112 such that the bottom surface SB is located between the index matching layer 114 and the light emitting surface SE.

The material of the index matching layer 114 may include an insulating material or an oxidized metal. When the material of the index matching layer 114 is selected from an inorganic insulating material (such as yttrium oxide) or an oxidized metal (such as indium tin oxide), the index matching layer 114 can be formed on the bottom surface SB by a coating film, and the index matching layer 114 may have a plurality of nano-columnar voids N1. Referring to FIG. 1 to FIG. 2B, the nano-columnar voids N1 are distributed in the index matching layer 114, wherein each of the nano-columnar voids N1 may extend outward from the bottom surface SB of the light guiding body 112, and each nano-column The extending direction D of the void N1 may be perpendicular to the bottom surface SB (as shown in FIG. 2A) or inclined to the bottom surface SB (as shown in FIG. 2B). Fold of the index matching layer 114 The rate of incidence is related to parameters such as the inclination angle, width, hole ratio, and arrangement of the nano-columnar void N1. In FIGS. 2A and 2B, the nano-columnar voids N1 are equally spaced, but the novel creation is not limited thereto.

When the material of the index matching layer 114 is selected from an organic insulating material (such as a polymer material), the index matching layer 114 may be formed on the bottom surface SB by coating, and the index matching layer 114 may have a plurality of nanoparticles. Hole N2. Referring to FIGS. 1 and 2C, the nanopore N2 is dispersedly distributed in the polymer material, and the refractive index of the index matching layer 114 is related to parameters such as the size, distribution, and porosity of the nanopore N2. In addition, the index matching layer 114 may also be formed directly from a material having a refractive index smaller than that of the light guiding body 112, such as magnesium fluoride (MgF ₂ ), polytetrafluoroethene (Teflon), or low refractive index optics. Glue, etc.

The difference in refractive index between the light guiding body 112 and the index matching layer 114 and the thickness H114 of the index matching layer 114 affect the reflectance of the backlight module 100 will be described below with reference to FIGS. 3 and 4. 3 and 4 are graphs showing the relationship between the thickness of the index matching layer and the reflectance of visible light at different refractive index differences, respectively. In FIG. 3, the refractive index difference between the light guiding body 112 and the index matching layer 114 is 0.14, and in FIG. 4, the refractive index difference between the light guiding body 112 and the index matching layer 114 is 0.32. It should also be noted that the reflectances in FIGS. 3 and 4 are simulation results when the incident angle is greater than the critical angle, respectively.

In the light guiding body 112, when the incident angle is larger than the critical angle, internal total reflection occurs, so theoretically, the reflectance of visible light (wavelength 400 nm to 700 nm) approaches 100%. However, in practice, when the index matching layer 114 is very thin, thinning may occur. Membrane interference, while thin film interference destroys total reflection. As shown in FIGS. 3 and 4, even when the incident angle is larger than the critical angle, if the thickness H114 of the index matching layer 114 is insufficient, the reflectance in the visible light band may vary greatly, causing a problem of color shift. Further, the shortage of the thickness H114 causes the light wave larger than the critical angle to decrease due to the total amount of total internal reflection, and cannot effectively conduct the light wave to the rear end of the light guiding body 112 away from the light incident surface SI.

3 and 4, the larger the refractive index difference between the light guiding body 112 and the index matching layer 114, the smaller the thickness H114 of the index matching layer 114 required for total reflection. In other words, the formation of total reflection is facilitated by modulating the refractive index difference of the light guiding body 112 and the index matching layer 114 in conjunction with the thickness H114 of the index matching layer 114. In detail, if the refractive index of the light guiding body 112 is n1 and the refractive index of the index matching layer 114 is n2, then it is 1.07*n2≦n1≦1.7*n2, and 0.1≦(n1-n2)≦0.7 The thickness H114 of the index matching layer 114 needs to be greater than 500 nm.

Under the architecture of FIG. 1, 1.5≦n1≦1.7, and 1.0<n2≦1.4, wherein the light guiding body 112 may be glass, polymethyl methacrylate (PMMA) or polycarbonate (PC), but not Limited. The index matching layer 114 can adopt the pattern shown in FIG. 2A to FIG. 2C, and the refractive index of the index matching layer 114 can be modulated by changing the hole ratio, but is not limited thereto. The refractive index range and the structural strength of the index matching layer 114 are considered, and the hole ratio of the index matching layer 114 is preferably 5% or more and 95% or less. As such, in addition to facilitating the formation of total reflection, the index matching layer 114 can also be used to support the light guiding body 112, thereby improving the structural strength of the light guiding plate 110, and The rainbow pattern phenomenon caused by the insufficient structural strength of the conventional large-size backlight module can be solved, and the backlight module 100 has good illumination quality. When the index matching layer 114 is a low refractive index optical adhesive (such as OCA) and the light guiding body 112 is glass, the light guiding body 112 is adhered to the reflective sheet 130 through the low refractive index optical adhesive to have an explosion-proof film-like effect. , thereby increasing the strength of the organization.

Referring again to FIG. 1, the light source 120 is disposed adjacent to the light incident surface SI, which is adapted to provide a light beam (not shown). The light beam enters the light guiding body 112 from the light incident surface SI and is transmitted to the light guiding body 112 by internal total reflection. A light guiding microstructure or dot (not shown) located on the bottom surface SB of the light guiding body 112 can scatter a portion of the light beam, thereby causing the light beam to be emitted from the light emitting surface SE of the light guiding body 112 and forming a surface light source required for illumination. The light source 120 may include a light tube or a plurality of light emitting diodes, wherein the extending direction of the light tubes or the arrangement direction of the light emitting diodes is parallel to the light incident surface SI (ie, perpendicular to the drawing surface).

The reflective sheet 130 is disposed on a side of the index matching layer 114 away from the light guiding body 112, and is adapted to reflect the light beam emitted from the bottom surface SB to the light guiding body 112, so that the light beam has a chance to return to the light guiding body 112 again, thereby enhancing the light. Utilization. For example, the reflective sheet 130 may be a metal reflective sheet or a white reflective sheet. The metal reflective sheet is, for example, a silver reflective sheet or an aluminum reflective sheet, but is not limited thereto. In this embodiment, the reflective sheet 130 may be formed on the surface of the index matching layer 114 away from the light guiding body 112 by coating or coating, but the novel creation is not limited thereto.

The backlight module 100 may further include other components according to different design requirements. For example, the backlight module 100 can further include at least one optical film 140. The optical film 140 is located above the light emitting surface SE of the light guiding body 112 and can be packaged At least one of the diffuser and the cymbal is included, but is not limited thereto.

Other embodiments of the backlight module are described below with reference to FIGS. 5 to 10, wherein the same or similar elements are designated by the same or similar reference numerals and will not be described again. 5 to 8 are schematic cross-sectional views of a backlight module according to second to fifth embodiments of the present invention. 9 and 10 respectively show simulation results of the reflectance of the backlight module in which only the refractive index matching layer and the refractive index matching layer, the first refractive index layer, and the second refractive index layer are provided. 11 and FIG. 12 are schematic top views of a backlight module according to a sixth embodiment and a seventh embodiment of the present invention, wherein FIG. 11 and FIG. 12 are omitted to illustrate the optical film 140 of FIG.

Referring to FIG. 5 , the backlight module 200 is similar to the backlight module 100 of FIG. 1 . The main difference between the two is the relative arrangement relationship between the index matching layer 114A and the light guiding body 112A in the light guiding plate 110A. In detail, the index matching layer 114A is composed of a plurality of surface nanoholes N3 recessed into the light guiding body 112A by the bottom surface SB. The surface nanohole N3 is formed, for example, by selectively etching the bottom surface SB of the light guiding body 112A, but is not limited thereto. Under this architecture, the light exiting surface SE of the light guiding body 112A can selectively form a plurality of light guiding microstructures, or the bottom surface SB of the light guiding body 112A can form a plurality of dots.

Referring to FIG. 6 , the backlight module 300 is similar to the backlight module 100 of FIG. 1 . The main difference between the two is that the backlight module 300 further includes an adhesive layer AD1 , and the reflective sheet 130 is bonded to the index matching layer 114 through the adhesive layer AD1 . . The adhesive layer AD1 and the light guiding body 112 may have the same or similar refractive index, but are not limited thereto. It should be noted that, in the embodiment of FIG. 5, the reflective sheet 130 can also pass through the adhesive layer AD1 and fold. The rate matching layer 114 is joined.

Referring to FIG. 7, the backlight module 400 is similar to the backlight module 300 of FIG. 6. The main difference between the two is that the index matching layer 114B is a glass having a surface nanohole N3. The surface nanohole N3 is formed, for example, by selectively etching a surface of the glass, but is not limited thereto. The refractive index of the index matching layer 114B may be 5% or more and 95% or less, and the refractive index of the index matching layer 114B falls within the range of 1.1 to 1.45, but is not limited thereto. The light guide plate 110B may further include an adhesive layer AD2, and the index matching layer 114B is bonded to the bottom surface SB through the adhesive layer AD2. The adhesive layers AD1, AD2, the glass of the index matching layer 114B, and the light guiding body 112 may have the same or similar refractive index, but are not limited thereto. Further, the thickness HAD2 of the adhesive layer AD2 and the thickness H114 of the index matching layer 114B may be smaller than the thickness H112 of the light guiding body 112.

In this embodiment, the surface nanohole N3 is located on the side of the index matching layer 114B away from the light guiding body 112, but is not limited thereto. In another embodiment, the surface nanohole N3 may be located on a side of the index matching layer 114B that is adjacent to the light guiding body 112. In addition, at least one of the bottom surface SB of the light guiding body 112, the light emitting surface SE, the surface of the index matching layer 114B close to the light guiding body 112, and the surface of the index matching layer 114B away from the light guiding body 112 can be selectively formed. Light guiding microstructure or multiple dots.

Referring to FIG. 8 , the backlight module 500 is similar to the backlight module 100 of FIG. 1 . The main difference between the two is that the backlight module 500 further includes at least one first refractive index layer I1 and at least one second refractive index layer I2 . Each of the second refractive index layers I2 has a high refractive index The at least one first refractive index layer I1 and the at least one second refractive index layer I2 are alternately disposed between the index matching layer 114 and the reflective sheet 130, and wherein the refractive index of each of the first refractive index layers I1 is between A second refractive index layer I2 is closer to the index matching layer 114 than the at least one first refractive index layer I1. Specifically, when the number of the first refractive index layer I1 and the second refractive index layer I2 is one, the second refractive index layer I2 is located between the first refractive index layer I1 and the index matching layer 114. When the numbers of the first refractive index layer I1 and the second refractive index layer I2 are respectively plural, the second refractive index layer I2 and the first refractive index layer I1 are sequentially stacked alternately in the direction in which the index matching layer 114 is directed to the reflective sheet 130. .

When the material of the index matching layer 114 is made of a viscous polymer material, the first refractive index layer I1 and the second refractive index layer I2 may be formed on the reflective sheet 130 first, and then transmitted through the index matching layer 114 and the light guiding layer. The body 112 is joined. Alternatively, the index matching layer 114, the second refractive index layer I2, the first refractive index layer I1 and the reflective sheet 130 may be sequentially formed on the light guiding body 112 (for example, by means of plating).

In the present embodiment, the index matching layer 114 may be an air layer, that is, n2 = 1.0, in addition to the types of FIGS. 2A to 2C and FIG. Under this architecture, the thickness H114 is the height of the air gap between the second refractive index layer I2 and the light guiding body 112.

By modulating the refractive indices and thicknesses HI1, HI2 of the first refractive index layer I1 and the second refractive index layer I2, in addition to compensating for differences in reflectance at different wavelengths, the reflectance can be further improved. The following is a description of how the light guide body 112 is provided with only the index matching layer 114 and the refractive index matching layer 114, the first refractive index layer I1, and the second refractive index layer I2 affect the reflectance of the backlight module, with reference to FIG. 9 and FIG. Simulation results. Figure 9 shows a simulation result of the reflectance of the backlight module under the configuration in which only the index matching layer 114 is provided on the bottom surface SB of the light guiding body 112. FIG. 10 shows a simulation result of the reflectance of the backlight module in a configuration in which the refractive index matching layer 114, the first refractive index layer I1, and the second refractive index layer I2 are provided on the bottom surface SB of the light guiding body 112. In FIGS. 9 and 10, when the incident angle in the light guiding body 112 is larger than the critical angle (for example, when the incident angle is 60 degrees or 70 degrees), the reflectance in the visible light range (400 nm to 700 nm) is almost 100%. When the incident angle in the light guiding body 112 is less than the critical angle (for example, when the incident angle is 0 degrees, 20 degrees, or 40 degrees), part of the light beam will be emitted from the bottom surface SB of the light guiding body 112, causing partial light energy to be lost. Therefore, the reflectance in the visible light range (400 nm to 700 nm) is less than 100%.

Comparing FIG. 9 and FIG. 10, in the structure in which the first refractive index layer I1 and the second refractive index layer I2 are not provided, the backlight module has a low reflectance in the short wavelength (400 nm to 550 nm). The reflectance is significantly lower than that of the long wavelength (550 nm to 700 nm), and thus a color shift occurs. In the structure in which the first refractive index layer I1 and the second refractive index layer I2 are disposed, the refractive index and the thicknesses HI1 and HI2 of the first refractive index layer I1 and the second refractive index layer I2 are modulated at a visible light wavelength (400 nm~). The uniform reflectance in the range of 700 nm), in addition to compensating for the difference in reflectance of different wavelengths, further improves the overall reflectance, thereby improving the color shift and improving the brightness of the backlight module 500. In the present embodiment, the refractive index of each of the first refractive index layers I1 falls within the range of 1.3 to 1.5, and the refractive index of each of the second refractive index layers I2 falls within the range of 1.8 to 2.5. Further, the thickness HI1 of each of the first refractive index layers I1 falls within a range of 50 nm to 100 nm, and the thickness HI2 of each of the second refractive index layers I2 falls at 30 nm to Within the range of 60 nm.

Referring to FIG. 9 , the backlight module 600 is similar to the backlight module 100 of FIG. 1 . The main difference between the two is that the backlight module 600 further includes a housing HS to accommodate the light guide plate 110 , the light source 120 , and the reflective sheet (not shown). ). In this embodiment, the housing HS can be made of a material having a high reflectivity to reflect the light beam (not shown) emitted from the side surface SS of the light guiding body 112 back into the light guiding body 112, thereby improving the light utilization efficiency. However, this new creation is not limited to this. As shown in FIG. 10, the backlight module 700 may further include a side reflection sheet SR to reflect the light beam emitted from the side surface SS of the light guide body 112 back into the light guide body 112. The side reflection sheet SR is located between the housing HS and the light guide plate 110. Thus, the material of the casing HS is not limited to a material having a high reflectance.

The backlight modules 100, 200, 300, 400, 500, 600, 700 of the above embodiments can be applied to a display device (not shown). Specifically, the display device may include one of the backlight modules 100, 200, 300, 400, 500, 600, 700 and a display panel (not shown), wherein the display panel is disposed adjacent to the light emitting surface SE, for example, the display panel is located at the light emitting surface. Above the face SE, and the optical film 140 is located between the light guiding body 112 and the display panel.

In summary, the embodiments of the present novel creation have at least one of the following advantages or effects. In the light guide plate of the embodiment of the present invention, the refractive index difference between the light guiding body and the index matching layer is matched with the thickness of the index matching layer to contribute to the formation of total reflection. In an embodiment, the index matching layer can be used to support the light guiding body, thereby enhancing the structural strength of the light guiding plate. In addition, the backlight module of the embodiment of the present invention can have good illumination quality by applying the above-mentioned light guide plate. The creation of this new type The display device of the embodiment can have good display quality by applying the backlight module described above. In an embodiment, the first refractive index layer and the second refractive index layer may be disposed between the index matching layer and the reflective sheet to compensate for the difference in reflectance of different wavelengths and enhance the reflectance, thereby improving the color shift and improving the backlight mode. The brightness of the group.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the novel creation, and any person skilled in the art can make some changes without departing from the spirit and scope of the novel creation. Retouching, the scope of protection of this new creation is subject to the definition of the scope of the patent application attached.

100‧‧‧Backlight module

110‧‧‧Light guide plate

112‧‧‧Lighting body

114‧‧‧index matching layer

120‧‧‧Light source

130‧‧‧reflector

140‧‧‧Optical diaphragm

H114‧‧‧ thickness

SB‧‧‧ bottom

SE‧‧‧Glossy

SI‧‧‧Into the glossy surface

Claims (21)

A light guide plate comprising: a light guiding body having a light emitting surface and a bottom surface opposite to the light emitting surface; and an index matching layer disposed adjacent to the bottom surface, wherein the light guiding body has a refractive index n1, the refraction The refractive index of the rate matching layer is n2, 1.07*n2≦n1≦1.7*n2, and 0.1≦(n1-n2)≦0.7, and the thickness of the index matching layer is greater than 500 nm. The light guide plate of claim 1, wherein 1.5 ≦ n1 ≦ 1.7, and 1.0 < n 2 ≦ 1.4. The light guide plate of claim 1, wherein the bottom surface is located between the index matching layer and the light exiting surface, and the index matching layer has a plurality of nano-columnar voids or nanopores. The light guide plate of claim 3, wherein the material of the index matching layer comprises an insulating material or an oxidized metal. The light guide plate of claim 1, wherein the index matching layer is formed by a plurality of surface nanoholes recessed into the light guiding body by the bottom surface. The light guide plate of claim 1, wherein the refractive index matching layer has a porosity of 5% or more and 95% or less. The light guide plate of claim 1, wherein the index matching layer is a glass having a surface nano hole, the light guide plate further comprising an adhesive layer, the index matching layer passing through the adhesive layer and the bottom surface Engage. A backlight module includes: a light guide plate, comprising: a light guiding body having a light emitting surface, a bottom surface opposite to the light emitting surface; and a light incident surface connecting the light emitting surface and the bottom surface; and an index matching a layer disposed adjacent to the bottom surface, wherein the light guide body has a refractive index n1, and the refractive index matching layer has a refractive index of n2, 1.07*n2≦n1≦1.7*n2, and 0.1≦(n1-n2)≦0.7, The refractive index matching layer has a thickness greater than 500 nm; a light source disposed beside the light incident surface; and a reflective sheet, wherein the index matching layer is located between the reflective sheet and the light guiding body. The backlight module of claim 8, wherein 1.5 ≦ n1 ≦ 1.7, and 1.0 ≦ n 2 ≦ 1.4. The backlight module of claim 8, wherein the bottom surface is located between the index matching layer and the light exiting surface, and the index matching layer has a plurality of nano-columnar voids or nano-holes. The backlight module of claim 10, wherein the material of the index matching layer comprises an insulating material or an oxidized metal. The backlight module of claim 8, wherein the index matching layer is formed by a plurality of surface nanoholes recessed into the light guiding body by the bottom surface. The backlight module of claim 8, wherein the refractive index matching layer has a porosity of 5% or more and 95% or less. The backlight module of claim 8, further comprising an adhesive layer, the reflective sheet being bonded to the index matching layer through the adhesive layer. The backlight module of claim 8, wherein the index matching layer is a glass having a surface nano hole, the light guide plate further comprising an adhesive layer, and the index matching layer passes through the adhesive layer The bottom surface is joined. The backlight module of claim 8, further comprising at least one first refractive index layer and at least one second refractive index layer, each of the second refractive index layers having a higher refractive index than each of the first refractive indices a refractive index of the layer, the at least one first refractive index layer and the at least one second refractive index layer are alternately disposed between the index matching layer and the reflective sheet, and wherein a second refractive index layer is at least one A refractive index layer is closer to the index matching layer. The backlight module of claim 16, wherein the refractive index of each of the first refractive index layers falls within a range of 1.3 to 1.5, and the refractive index of each of the second refractive index layers falls between 1.8 and 2.5. In the range. The backlight module of claim 16, wherein the thickness of each of the first refractive index layers falls within a range of 50 nm to 100 nm, and the thickness of each of the second refractive index layers falls within a range of 30 nm to 60 nm. Inside. The backlight module of claim 8, further comprising a housing for housing the light guide plate, the light source and the reflective sheet. The backlight module of claim 19, further comprising a side reflection sheet located between the housing and the light guide plate. A display device comprising: the backlight module of claim 8; and a display panel, wherein the display panel is disposed adjacent to the light exiting surface.