Total reflection liquid crystal screen and front full-lamination light guide plate

Abstract

The utility model relates to a total reflection liquid crystal screen and a front full-lamination light guide plate, the total reflection liquid crystal screen comprises a liquid crystal screen main body, a light guide plate and a cover plate, a first optical lamination adhesive layer is arranged between the light guide plate and the liquid crystal screen main body; a second optical fitting adhesive layer is arranged between one side, far away from the liquid crystal screen main body, of the light guide plate and the cover plate; and the second optical fitting adhesive layer is used for filling a light transmission area between the light guide plate and the cover plate. By arranging the second optical laminating adhesive layer, the whole-surface lamination of the light guide plate and the cover plate is realized, the possibility of existence of an air layer between the light guide plate and the cover plate is reduced, the possibility of mirror reflection of the total-reflection liquid crystal screen is reduced, the display definition of the total-reflection liquid crystal screen is improved, and the display effect of the total-reflection liquid crystal screen is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of liquid crystal display, in particular to a total reflection liquid crystal screen and a front fully laminated light guide plate. Background Art

[0002] As a new display technology, the fully reflective LCD screen has a significant difference in structure compared to the traditional transmissive LCD screen. The traditional transmissive LCD screen uses the backlight module to provide light so that the liquid crystal layer can display images. However, the fully reflective LCD screen has a reflective layer on the back, which makes the screen unable to transmit light, so the backlight module cannot be used. On the contrary, the fully reflective LCD screen relies on ambient light for reflection and display, achieving energy-saving and environmental protection effects.

[0003] However, there are still some technical difficulties in the actual application of fully reflective LCD screens. First, due to the existence of its reflective layer, the reflectivity of the fully reflective LCD screen is relatively low. In a dark environment or when the ambient light is not strong enough, the screen cannot display normally and cannot achieve an all-weather display effect, which limits the application of fully reflective LCD screens in various scenarios.

[0004] In order to solve this problem, the current solution is to attach a light guide plate to the fully reflective LCD screen. When the ambient light is insufficient, the light guide plate can supplement the light source so that the fully reflective LCD screen can display normally. However, the existing light guide plate and the cover plate are framed, so that there is an air layer between the cover plate and the light guide plate, adding two reflective surfaces, the upper surface of the light guide plate and the lower surface of the cover plate, reducing the contrast of the front light module of the fully reflective LCD screen and reducing the display clarity of the fully reflective LCD screen. Due to the existence of the air layer, if the cover plate is too thin and the thickness of the air layer between the cover plate and the light guide plate is inconsistent, it is easy to cause the appearance of Newtonian lines on the fully reflective LCD screen, affecting the display effect, and at the same time, it is impossible to design and use ultra-thin products. Utility Model Content

[0005] In order to reduce the possibility of mirror reflection of the total reflection liquid crystal screen, improve the display clarity of the total reflection liquid crystal screen, and improve the display effect of the total reflection liquid crystal screen, the present application provides a total reflection liquid crystal screen and a front fully laminated light guide plate.

[0006] In a first aspect, the present application provides a fully reflective liquid crystal screen, comprising a liquid crystal screen body, a light guide plate and a cover plate, wherein a first optical bonding adhesive layer is provided between the light guide plate and the liquid crystal screen body, and a second optical bonding adhesive layer is provided between a side of the light guide plate away from the liquid crystal screen body and the cover plate, and the second optical bonding adhesive layer fills the area between the light guide plate and the cover plate for light transmission.

[0007] The beneficial effects of the utility model are as follows: by setting the first optical bonding adhesive layer, the entire surface of the light guide plate and the main body of the liquid crystal screen are bonded. By setting the second optical bonding adhesive layer, the entire surface of the light guide plate and the cover plate are bonded, which reduces the possibility of an air layer between the light guide plate and the cover plate, thereby reducing the possibility of mirror reflection of the total reflection liquid crystal screen, improving the display clarity of the total reflection liquid crystal screen, and improving the display effect of the total reflection liquid crystal screen. Since there is no need to set an air layer between the light guide plate and the cover plate, there is no need to limit the thickness of the cover plate, which reduces the possibility of Newtonian lines on the total reflection liquid crystal screen, and can also realize the design and use of ultra-thin products.

[0008] Furthermore, the light guide plate includes a base layer and a total reflection coating coated on the surface of the base layer, the refractive index of the total reflection coating is smaller than the refractive index of the base layer, and the light is totally reflected in the light guide plate by the total reflection coating; a light extraction grid point for destroying the transmission of light totally reflected in the light guide plate is provided on the side of the base layer close to the liquid crystal screen body.

[0009] The beneficial effect of adopting the above further scheme is: by coating the surface of the base with a total reflection coating having a refractive index less than that of the base, the light can be totally reflected in the light guide plate. The light extraction grid points are arranged on the surface of the base corresponding to the liquid crystal screen body, and are used to destroy the total reflection condition in the light guide plate. When the light propagates in the light guide plate to the light extraction grid points, the incident angle of the light will change due to the presence of the light extraction grid points, thereby no longer meeting the total reflection condition, so that the light can be emitted from the light guide plate and then transmitted to the liquid crystal screen body.

[0010] Furthermore, the total reflection coating includes a first coating layer connected to the first optical bonding adhesive layer and a second coating layer connected to the second optical bonding adhesive layer, and the light extraction points are arranged on the surface where the base layer is connected to the first optical bonding adhesive layer.

[0011] The beneficial effect of adopting the above further scheme is that the total reflection coating includes a first coating layer and a second coating layer coated on the two surfaces of the base layer, which can enhance the total reflection effect of light, improve the light transmission efficiency, optimize the light distribution, and simplify the manufacturing process, and has more practical application value in the total reflection liquid crystal screen.

[0012] Furthermore, the first coating layer and the second coating layer have the same refractive index.

[0013] The beneficial effect of adopting the above further scheme is that the consistency of refractive index helps the light to maintain a stable transmission path inside the light guide plate, so that the light can be more evenly distributed to various areas of the LCD screen body, which helps to improve the brightness and uniformity of the LCD screen body and improve the visual effect of the picture. The design of the total reflection coating allows the light to be fully reflected inside the light guide plate, and the consistency of the refractive index of the first coating layer and the second coating layer helps to enhance the reflection effect. When the light reaches the coating layer interface, it is easier to meet the conditions of total reflection, thereby increasing the number of reflections and transmission distance of the light in the light guide plate. .

[0014] Furthermore, the thickness of the first coating layer and the thickness of the second coating layer are both not less than 1 micrometer.

[0015] The beneficial effect of adopting the above further solution is that it can ensure the normal transmission of light.

[0016] Furthermore, the shape of the light-trapping dots is a shape that is convex from the base layer toward the liquid crystal panel body and / or a shape that is concave from the liquid crystal panel body toward the base layer.

[0017] The beneficial effect of adopting the above further solution is that the shape of the light-collecting dot can be designed and adjusted according to actual optical requirements and production processes, thereby improving the selectivity of the shape of the light-collecting dot.

[0018] In a second aspect, the present application provides a front fully-bonded light guide plate used in a fully-reflective liquid crystal screen according to any one of the first aspects, wherein a first optical bonding adhesive layer is provided between the light guide plate and the liquid crystal screen body, and a second optical bonding adhesive layer is provided between the side of the light guide plate away from the liquid crystal screen body and the cover plate, and the second optical bonding adhesive layer fills the area between the light guide plate and the cover plate for light transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of a fully reflective liquid crystal screen according to an embodiment of the present application;

[0020] Figure 2 A schematic diagram showing the structure of a light guide plate according to an embodiment of the present application;

[0021] Figure 3 A schematic diagram of total reflection light transmission according to an embodiment of the present application;

[0022] Figure 4 A schematic diagram showing the destruction of total reflection by light extraction points in an embodiment of the present application;

[0023] Figure 5 This is a schematic diagram of an embodiment of the present application in which the shape of the light-collecting grid point is a convex hemispherical shape;

[0024] Figure 6This is a schematic diagram showing that the shape of the light-collecting grid point in the embodiment of the present application is a concave hemispherical shape.

[0025] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0026] 1. LCD screen body; 11. Polarizer; 12. Electrode glass; 13. Liquid crystal; 14. Reflective layer; 15. TFT electrode glass; 2. Light guide plate; 21. Base layer; 22. Light collection points; 23. First coating layer; 24. Second coating layer; 3. Cover plate; 4. Light source; 5. First optical bonding layer; 6. Second optical bonding layer. DETAILED DESCRIPTION

[0027] In this embodiment, Figure 1 As shown, a total reflection liquid crystal screen includes a liquid crystal screen body 1, a light guide plate 2, a cover plate 3 and a light source 4. The light guide plate 2 is located between the liquid crystal screen body 1 and the cover plate 3. The light source 4 is arranged on one side of the light guide plate 2. When the ambient light is insufficient, the light source 4 can emit light to the light guide plate 2, and the light is transmitted from the light guide plate 2 to the liquid crystal screen body 1, so that the total reflection liquid crystal screen can display normally. Exemplarily, the light source 4 can be an LED lamp.

[0028] like Figure 1 As shown, the LCD screen body 1 may specifically include a polarizer 11, an electrode glass 12, a liquid crystal 13, a reflective layer 14 and a TFT (thin film transistor) electrode glass 12. In a fully reflective LCD screen, the polarizer 11 is used to allow only light in a specific direction transmitted by the light guide plate 2 to pass through, thereby removing stray light in the light and improving the contrast of the image; the electrode glass 12 is a key component in the liquid crystal 13 display device, and is used to apply an electric field to control the arrangement of the liquid crystal 13; the reflective layer 14 is usually made of a material with high reflectivity, and is used to reflect light back to the liquid crystal 13 to achieve reflective display; the TFT electrode glass 1512 is an active driving element in the liquid crystal 13 display device, and is used to control the electric field of each pixel point, thereby controlling the arrangement of the liquid crystal 13 and achieving image display.

[0029] like Figure 2 As shown, in this embodiment, a first optical bonding adhesive layer 5 is provided between the light guide plate 2 and the liquid crystal screen body 1, and a second optical bonding adhesive layer 6 is provided between the surface of the light guide plate 2 away from the liquid crystal screen body 1 and the cover plate 3. The second optical bonding adhesive layer 6 can fill the area between the light guide plate 2 and the cover plate 3 for light transmission.

[0030] The optical bonding adhesive layer may be an optical bonding glue layer or an optical double-sided adhesive layer. By providing the first optical bonding adhesive layer 5, the entire surface bonding of the light guide plate 2 and the liquid crystal screen body 1 is achieved. By providing the second optical bonding adhesive layer 6, the entire surface bonding of the light guide plate 2 and the cover plate 3 is achieved, reducing the possibility of an air layer between the light guide plate 2 and the cover plate 3, thereby reducing the possibility of mirror reflection of the total reflection liquid crystal screen, improving the display clarity of the total reflection liquid crystal screen, and improving the display effect of the total reflection liquid crystal screen. Since there is no need to provide an air layer between the light guide plate 2 and the cover plate 3, there is no need to limit the thickness of the cover plate 3, reducing the possibility of Newtonian lines on the total reflection liquid crystal screen, and can also achieve the design and use of ultra-thin products.

[0031] like Figure 2 As shown, in this embodiment, the light guide plate 2 includes a base layer 21 and a total reflection coating coated on the surface of the base layer 21, the refractive index of the total reflection coating is smaller than the refractive index of the base layer 21, and the total reflection coating causes the light to be totally reflected in the light guide plate 2; the surface of the base layer 21 close to the side of the liquid crystal screen body 1 is provided with a light extraction network point 22 for destroying the transmission of the light totally reflected in the light guide plate 2.

[0032] The total internal reflection principle (also known as total internal reflection) in optics is an optical phenomenon. When light enters a transmission medium with a higher refractive index into a transmission medium with a lower refractive index, if the incident angle is greater than a certain critical angle θc (the light is far away from the normal), the refracted light will disappear, and all incident light will be reflected without refracting into the medium with a lower refractive index. It is easy to understand that total internal reflection can only occur when light enters a medium with a higher refractive index (also known as a denser medium) into a medium with a lower refractive index (also known as a sparser medium), such as when light enters from glass into air, but not when light enters from air into glass.

[0033] For example, Figure 3 As shown, light can enter the n2 medium with a lower refractive index from the n1 medium with a higher refractive index, as shown in Figure 3 The light transmission path shown by the dashed line in the middle, when the incident angle θ1 of the light is less than the critical angle θc, the light is refracted into the n2 medium and reflected into the n1 medium at the same time; Figure 3 In the light transmission path shown by the solid line, when the incident angle θ2>critical angle θc, the light refracted into the n2 medium disappears, and the light is reflected into the n1 medium, that is, total reflection occurs.

[0034] In this embodiment, by coating the surface of the base layer 21 with a total reflection coating having a refractive index less than that of the base layer 21, the light can be totally reflected in the light guide plate 2. The light extraction grid points 22 are arranged on the surface of the base layer 21 corresponding to the liquid crystal screen body 1, and are used to destroy the total reflection condition in the light guide plate 2. When the light propagates in the light guide plate 2 to the light extraction grid points 22, due to the existence of the light extraction grid points 22, the incident angle of the light will change, and the total reflection condition will no longer be satisfied, so that the light can be emitted from the light guide plate 2 and then transmitted to the liquid crystal screen body 1. By reasonably designing the shape, size and distribution of the light extraction grid points 22, the emission position and quantity of the light can be controlled to meet the display requirements of the liquid crystal screen 13. The light is transmitted downward to the total reflection liquid crystal screen through the total reflection principle of the light guide plate 2, and then emitted upward through the reflection of the total reflection liquid crystal screen to achieve the purpose of fill light display.

[0035] The light is totally reflected in the light guide plate 2, which can ensure that the light is transmitted over a long distance inside the light guide plate 2 without leaking out easily, thereby improving the utilization rate of the light and reducing the light loss. Secondly, through total reflection, the propagation path and distribution of the light can be controlled. In the design of the light guide plate 2, the propagation direction and the angle of emission of the light can be controlled by adjusting the shape, size and refractive index of the total reflection coating of the light guide plate 2 according to the display requirements of the total reflection liquid crystal screen, thereby achieving a more uniform and softer light distribution and improving the brightness and visual effect of the total reflection liquid crystal screen.

[0036] In this embodiment, the surface of the base layer 21 close to the LCD screen body 1 is provided with light collecting dots 22, while the surface of the base layer 21 away from the LCD screen body 1 is not provided with light collecting dots 22, so that the light in the base layer 21 can be transmitted to the LCD screen body 1, so that the LCD screen body 1 can display, reducing the possibility that the light is directly transmitted in the direction away from the LCD screen body 1, resulting in the LCD screen body 1 cannot display normally.

[0037] As an optional implementation of this embodiment, the total reflection coating includes multiple coating layers coated on various surfaces of the base layer 21.

[0038] As another optional implementation of this embodiment, since the light is emitted from the light guide plate 2 to the liquid crystal screen body 1 and then emitted from the liquid crystal screen body 1, as shown in FIG. Figure 2 and Figure 4 As shown, the total reflection coating may include a first coating layer 23 connected to the first optical bonding adhesive layer 5 and a second coating layer 24 connected to the second optical bonding adhesive layer 6, and the light extraction network points 22 are arranged on the surface where the base layer 21 is connected to the first optical bonding adhesive layer 5.

[0039] The total reflection coating includes a first coating layer 23 and a second coating layer 24 coated on both surfaces of the base layer 21, which can enhance the total reflection effect of light, improve light transmission efficiency, optimize light distribution, and simplify the manufacturing process, and has more practical application value in the total reflection liquid crystal screen.

[0040] In this embodiment, the first coating layer 23 and the second coating layer 24 have the same refractive index.

[0041] The consistency of the refractive index helps the light maintain a stable transmission path inside the light guide plate 2, so that the light can be more evenly distributed to various areas of the LCD screen body 1, which helps to improve the brightness and uniformity of the LCD screen body 1 and improve the visual effect of the picture. The design of the total reflection coating allows the light to be totally reflected inside the light guide plate 2, and the consistency of the refractive index of the first coating layer 23 and the second coating layer 24 helps to enhance the reflection effect. When the light reaches the coating layer interface, it is easier to meet the conditions of total reflection, thereby increasing the number of reflections and transmission distance of the light in the light guide plate 2. Keeping the refractive index of the first coating layer 23 and the second coating layer 24 the same can simplify the design and manufacturing process of the light guide plate 2, eliminating the need to use materials with different refractive indices for different coating layers, reducing production costs and complexity.

[0042] The shape of the light-collecting dots 22 is a shape when it is convex from the base layer 21 to the side of the liquid crystal screen body 1 and / or a shape when it is concave from the liquid crystal screen body 1 to the side of the base layer 21. The shape of the light-collecting dots 22 can be a convex shape and / or a concave shape such as a semi-sphere, a cone and a cylinder. In the same base layer 21, there are multiple light-collecting dots 22, and the shapes of the multiple light-collecting dots 22 can be the same or different. In this embodiment, the shapes of the multiple light-collecting dots 22 are the same, such as Figure 5 As shown, the light extraction dots 22 may all be hemispherical and protrude from the base layer 21 toward the side of the liquid crystal panel body 1, such as Figure 6 As shown, the light extraction dots 22 may also be hemispherical and concave from the base layer 21 toward the side of the liquid crystal panel body 1. The design of the light extraction dots 22 may be adjusted according to actual optical requirements and production processes to meet the shape requirements for disrupting the transmission of total reflected light.

[0043] For example, Figure 4 As shown, the base layer 21 is composed of an optical material with a refractive index n1=1.6, the first coating layer 23 and the second coating layer 24 are composed of an optical material with a refractive index n2=1.3, and θc can be obtained by substituting n1 and n2 into the calculation formula of the critical angle of total reflection θc. The light-collecting grid point 22 uses a semi-spherical design.

[0044] Among them, the calculation formula of the total reflection critical angle θc can be expressed as:

[0045] θc=arcs in(n2 / n1)=arcs in(1.3 / 1.6)=54.34°.

[0046] The incident angle corresponding to the light reflected in the base layer 21 is 55° (i.e., greater than the critical angle θc). The total reflection condition is destroyed by the light-collecting grid point 22, so that the incident angle of the light at the light-collecting grid point 22 becomes 35° (i.e., smaller than the critical angle θc), so that the light can be refracted from the light-collecting grid point 22 and then emitted from the first coating layer 23, thereby meeting the requirements of the light guide plate 2 of the total reflection liquid crystal screen.

[0047] Since the maximum wavelength of visible light is generally 770nm, the thickness of the coating layer needs to exceed this wavelength to ensure normal transmission of light. In this embodiment, the thickness of the first coating layer 23 and the thickness of the second coating layer 24 are not less than 1 micron.

[0048] When the light extraction network dots 22 are concave from the base layer 21 to the side of the liquid crystal panel body 1, the thickness of the second coating layer 24 is not less than 1 micron, and the thickness of the first coating layer 23 includes the thickness between the vertex surface of the light extraction network dots 22 and the surface of the first coating layer 23 away from the base layer 21, and the thickness between the vertex surface of the light extraction network dots 22 and the surface of the first coating layer 23 away from the base layer 21 also needs to be not less than 1 micron. Figure 4 As shown, when the light extraction network dots 22 are convex from the base layer 21 to the side of the liquid crystal panel body 1, the thickness of the second coating layer 24 is not less than 1 micron, and the thickness of the first coating layer 23 includes the thickness from the vertex surface of the light extraction network dots 22 to the surface of the first coating layer 23 away from the base layer 21 (i.e. Figure 4 In h), the thickness from the vertex surface of the light extraction network point 22 to the surface of the first coating layer 23 away from the base layer 21 also needs to be no less than 1 micron.

[0049] Based on the same technical concept, the present application also provides a front fully-bonded light guide plate used in a fully-reflective liquid crystal screen, wherein a first optical bonding adhesive layer is provided between the light guide plate and the liquid crystal screen body, and a second optical bonding adhesive layer is provided between the surface of the light guide plate away from the liquid crystal screen body and the cover plate, and the second optical bonding adhesive layer fills the area between the light guide plate and the cover plate for light transmission.

[0050] The light guide plate includes a base layer and a total reflection coating coated on the surface of the base layer, the refractive index of the total reflection coating is smaller than the refractive index of the base layer, and the total reflection coating causes light to be totally reflected in the light guide plate; the surface of the base layer close to the side of the liquid crystal screen body is provided with light extraction points for destroying the transmission of light totally reflected in the light guide plate.

[0051] The total reflection coating includes a first coating layer connected to the first optical bonding adhesive layer and a second coating layer connected to the second optical bonding adhesive layer, and the light extraction network points are arranged on the surface where the base layer is connected to the first optical bonding adhesive layer. The refractive index of the first coating layer and the second coating layer is the same. The minimum thickness of the first coating layer and the thickness of the second coating layer are not less than 1 micron. The shape of the light extraction network points is a shape when it is convex from the base layer to the side of the liquid crystal screen body and / or a shape when it is concave from the liquid crystal screen body to the base layer side.

[0052] The terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or also includes elements inherent to such process, method, article, or apparatus.

[0053] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0054] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0055] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A fully reflective liquid crystal screen, characterized in that: The invention comprises a liquid crystal screen body (1), a light guide plate (2) and a cover plate (3); a first optical bonding adhesive layer (5) is provided between the light guide plate (2) and the liquid crystal screen body (1); a second optical bonding adhesive layer (6) is provided between the side of the light guide plate (2) away from the liquid crystal screen body (1) and the cover plate (3); the second optical bonding adhesive layer (6) fills the area between the light guide plate (2) and the cover plate (3) for light transmission.

2. A total reflection liquid crystal screen according to claim 1, characterized in that: The light guide plate (2) comprises a base layer (21) and a total reflection coating coated on the surface of the base layer (21); the refractive index of the total reflection coating is smaller than the refractive index of the base layer (21); the total reflection coating causes light to be totally reflected in the light guide plate (2); and a light extraction grid point (22) for destroying the transmission of light totally reflected in the light guide plate (2) is arranged on a side of the base layer (21) close to the liquid crystal screen body (1).

3. A total reflection liquid crystal screen according to claim 2, characterized in that: The total reflection coating comprises a first coating layer (23) connected to the first optical bonding adhesive layer (5) and a second coating layer (24) connected to the second optical bonding adhesive layer (6), and the light extraction grid points (22) are arranged on the surface where the base layer (21) is connected to the first optical bonding adhesive layer (5).

4. A total reflection liquid crystal screen according to claim 3, characterized in that: The first coating layer (23) and the second coating layer (24) have the same refractive index.

5. A total reflection liquid crystal screen according to claim 3 or 4, characterized in that: The thickness of the first coating layer (23) and the thickness of the second coating layer (24) are both not less than 1 micrometer.

6. A total reflection liquid crystal screen according to claim 2, characterized in that: The shape of the light-collecting grid point (22) is a shape that is convex from the base layer (21) toward the liquid crystal screen body (1) and / or a shape that is concave from the liquid crystal screen body (1) toward the base layer (21).

7. A front fully laminated light guide plate used in a total reflection liquid crystal display according to any one of claims 1 to 6, characterized in that: A first optical bonding adhesive layer is provided between the light guide plate and the liquid crystal screen body, and a second optical bonding adhesive layer is provided between the side of the light guide plate away from the liquid crystal screen body and the cover plate, and the second optical bonding adhesive layer fills the area between the light guide plate and the cover plate for light transmission.

Images