Reflector plate for backlight module, manufacturing equipment of reflector plate and backlight module
By designing corresponding protrusions and recesses on the reflective sheet, the problems of adhesion and scratches between the light guide plate and the reflective sheet are solved, improving display quality and assembly yield, and reducing manufacturing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- NICROTEK CO LTD
- Filing Date
- 2025-06-19
- Publication Date
- 2026-05-01
AI Technical Summary
In high-end backlight modules, adhesion and scratches can easily occur between the light guide plate and the reflective sheet, which cannot be effectively prevented by existing technologies, resulting in decreased display quality and low assembly yield.
The reflective sheet is designed with protrusions and recesses on the reflective and opposing surfaces, respectively. The protrusions and recesses correspond one-to-one and are formed by stamping. The protrusions provide support to prevent adhesion and maintain high reflectivity.
It effectively prevents adhesion and scratches between the light guide plate and the reflective sheet, improves display quality, saves materials, reduces manufacturing costs, and increases assembly yield.
Smart Images
Figure CN224190367U_ABST
Abstract
Description
Reflective sheets for backlight modules and their manufacturing equipment, backlight modules Technical Field
[0001] This application relates to the field of display technology, and in particular to a reflective sheet for a backlight module, its manufacturing equipment, and a backlight module. Background Technology
[0002] In LCD backlight modules, the reflector sheet's function is to reflect light leaking from the bottom surface of the light guide plate back to the light guide plate and then exit from the light-emitting surface of the backlight module. As a key component of the backlight module, its high reflectivity and surface quality are crucial for improving display brightness and luminous efficiency. However, in the backlight module, the reflector sheet is in direct contact with the light guide plate, making it prone to scratches or wear during assembly, affecting reflective performance and display quality. Furthermore, since both the reflective surface of the reflector sheet and the bottom surface of the light guide plate are flat and in direct contact, although the bottom surface of the light guide plate is usually machined with recessed or protruding light guide dots of a few micrometers, adhesion usually occurs between them after a period of use, especially when the protrusion height of the light guide dots is low, such as less than 2µm.
[0003] In existing technologies, there are generally two approaches to prevent adhesion or scratching between the light guide plate and the reflective sheet. One is to add an array of laser dots to the dotted surface of the light guide plate, utilizing the raised volcano-ring structure of the laser dots to prevent adhesion and scratching risks—a feature known in the industry as "anti-whitening." The second is to set the reflective surface of the reflective sheet to a matte finish, reducing the impact of adhesion and scratching on the optical performance and appearance of the backlight module. Both of these solutions are only suitable for conventional backlight modules. In some high-end applications, such as privacy backlight modules, the height of the light guide dots on the light guide plate is only 1-2µm, and the backlight module has strict requirements for the field of view. Neither of the above methods can meet the practical application requirements, resulting in extremely low assembly yields. This greatly limits the application of high-end backlight modules and high-end products. Therefore, a new technical solution is urgently needed to prevent adhesion and scratching between the light guide plate and the reflective sheet while ensuring high reflectivity (especially specular reflection). Summary of the Invention
[0004] In order to solve at least one of the above-mentioned technical problems, this application provides a reflective sheet for a backlight module, a manufacturing equipment thereof, and a backlight module.
[0005] Firstly, a reflective sheet for a backlight module is proposed, comprising:
[0006] The reflecting surfaces and opposing surfaces that are opposite each other in the thickness direction of the reflective sheet.
[0007] Multiple recesses recessed from the opposing surfaces, and
[0008] Multiple protrusions protruding from the reflective surface;
[0009] The plurality of protrusions and the plurality of recesses correspond one-to-one in the thickness direction.
[0010] In some possible implementations, the recess and the protrusion are formed by stamping the opposing surfaces to deform a portion of the reflective sheet toward the reflective surface side.
[0011] In some possible implementations, the recess does not extend into the protrusion in the thickness direction.
[0012] In some possible implementations, a substrate layer and a reflective layer stacked on the substrate layer are included, the reflective layer defining the reflective surface and the substrate layer defining the opposing surface.
[0013] In some possible implementations, the surface of the protrusion is dome-shaped.
[0014] In some possible implementations, the surface of the protrusion is part of a sphere.
[0015] In some possible implementations, the height of the protrusion is more than 5 μm and less than 15 μm, and the diameter of the orthographic projection of the protrusion onto the reflective surface is more than 200 μm and less than 300 μm.
[0016] In some possible implementations, the height of the protrusion is 10 μm, and the radius of curvature of the sphere is greater than 500 μm and less than 1130 μm.
[0017] In some possible implementations, the diameter of the orthographic projection of the protrusion on the reflective surface is 250 μm, and the distance between adjacent protrusions is more than 1.1 mm and less than 1.5 mm.
[0018] Secondly, a backlight module is proposed, including:
[0019] A light guide plate includes a light-emitting surface and a bottom surface that are opposite to each other in the thickness direction of the light guide plate, and a light-guiding microstructure is formed on the bottom surface;
[0020] The reflective sheet as described in the first aspect is stacked on the bottom side of the light guide plate, and the reflective surface faces the bottom surface.
[0021] Thirdly, a manufacturing apparatus is proposed for manufacturing a reflective sheet as described in the first aspect, the manufacturing apparatus comprising a first mold and a second mold that are selectively moved away from or close to each other under the drive of a power device, the first mold comprising a plurality of recesses, and the second mold comprising a plurality of protrusions respectively corresponding to the shape and position of the plurality of recesses;
[0022] The reflective sheet is obtained by bringing the first mold and the second mold close together to compress the sheet-like workpiece located between them.
[0023] The reflective sheet for a backlight module provided in this application includes a reflective surface and an opposing surface that are opposite each other in the thickness direction of the reflective sheet, a plurality of recesses recessed from the opposing surfaces, and a plurality of protrusions protruding from the reflective surfaces, wherein the plurality of protrusions and the plurality of recesses correspond one-to-one in the thickness direction. Therefore, when the reflective sheet is applied to a backlight module, these protrusions form a support between the reflective sheet and the light guide plate, thereby suppressing the adhesion between the reflective surface of the reflective sheet and the bottom surface of the light guide plate, thus suppressing display defects in the display device equipped with the backlight module, and saving material of the reflective sheet without significantly reducing the strength of the reflective sheet at the protrusion positions. Attached Figure Description
[0024] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of this application, and are not intended to limit this application.
[0025] Figure 1 is a side view of a portion of the backlight module provided in an embodiment of this application.
[0026] Figure 2 is a schematic diagram of the result of the reflector in Figure 1.
[0027] Figure 3 is a schematic diagram of the result of the reflector in Figure 1.
[0028] Figure 4 is a process diagram demonstrating the manufacturing of reflective sheets using manufacturing equipment.
[0029] Figure 5 is a flowchart of the process for manufacturing the reflective sheet.
[0030] Explanation of reference numerals in the attached figures:
[0031] 1-Light source;
[0032] 2-Light guide plate, 2a-Incident surface, 2b-Bottom surface, 2c-Emitting surface;
[0033] 3-Reflective sheet, 31-Reflective layer, 32-Substrate layer, 31a-Reflective surface, 31b-Protrusion, 32a-Opposing surface, 32b-Recess;
[0034] 4-first mold, 4a-recess;
[0035] 5-Second mold, 5a-Protrusion. Detailed Implementation
[0036] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the described embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. It is understood that, without conflict, some technical means of the various embodiments described herein can be substituted for or combined with each other.
[0037] In the description of this application, the terms "first," "second," etc., are used only to distinguish the described objects and have no sequential or technical meaning. Therefore, objects specified with "first," "second," etc., may explicitly or implicitly include one or more of those objects, and, for example, the term "first element" itself does not imply the existence of a "second element," nor does the term "second element" itself imply the existence of a "first element." Furthermore, words such as "a" or "one" do not indicate a quantity limitation, but rather indicate the presence of at least one, while "multiple" indicates not less than two.
[0038] In the description of this application, the terms "comprising" or "having" indicate the presence of the said features, numbers, operations, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, numbers, operations, elements, and / or combinations thereof.
[0039] In the description of this application, references to "one embodiment" or "some embodiments" mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized.
[0040] Figure 1 shows a portion of the backlight module provided in an embodiment of this application, which includes a light source 1, a light guide plate 2, and a reflector 3.
[0041] The light guide plate 2 has an incident surface 2a, an emitting surface 2c, and a bottom surface 2b. The emitting surface 2c and the bottom surface 2b are two different main surfaces of the light guide plate 2, and they are opposite to each other in the thickness direction of the light guide plate 2. The incident surface 2a is a side surface of the light guide plate 2, which connects the emitting surface 2c and the bottom surface 2b at one edge of the light guide plate 2. Numerous light-guiding microstructures (not shown) are formed on the bottom surface 2b of the light guide plate 2. These light-guiding microstructures can be concave microstructures recessed into the bottom surface 2b or convex microstructures protruding from the bottom surface 2b. These light-guiding microstructures are used to guide the direction of light. By optimizing the shape and position of these light-guiding microstructures, the desired emitted light can be obtained at the emitting surface 2c of the light guide plate 2.
[0042] The light source 1 can be an LED, which is disposed on the light-incident surface 2a side of the light guide plate 2 to generate light rays that are incident on the light-incident surface 2a of the light guide plate 2. Therefore, the light source 1 is a side-incident light source 1.
[0043] The reflective sheet 3 is stacked on the bottom surface 2b side of the light guide plate 2 and has a reflective surface 31a and an opposing surface 32a that are opposite to each other in the thickness direction of the reflective sheet 3. The reflective surface 31a faces the bottom surface 2b of the light guide plate 2, and therefore the opposing surface 32a becomes the surface of the reflective sheet 3 opposite to the light guide plate 2.
[0044] The reflective sheet 3 includes a plurality of protrusions 31b extending from its reflective surface 31a. As a result, these protrusions 31b form a support between the reflective sheet 3 and the light guide plate 2, thereby suppressing the adhesion between the reflective surface 31a of the reflective sheet 3 and the bottom surface 2b of the light guide plate 2, and thus suppressing display defects in the display device equipped with the backlight module.
[0045] In addition, the reflective sheet 3 also includes a plurality of recesses 32b recessed from its opposing surface 32a, and these recesses 32b and the aforementioned protrusions 31b correspond one-to-one in the thickness direction of the reflective sheet 3. With this design, the material used in the reflective sheet 3 is saved without significantly reducing the strength of the reflective sheet 3 at the protrusions 31b.
[0046] More specifically, the recesses 32b and protrusions 31b on the reflective sheet 3 are formed by stamping the opposing surface 32a, causing a portion of the reflective sheet 3 to deform toward the reflective surface 31a. This method of forming a reflective sheet 3 with protrusions 31b on the reflective surface 31a avoids material removal or addition, resulting in a simple manufacturing method, high forming efficiency, low manufacturing cost, and ease of implementation.
[0047] In this embodiment, the recess 32b does not extend into the protrusion 31b in the thickness direction of the reflective sheet 3. Therefore, the protrusion 31b becomes a solid structure, thus possessing good strength and support capabilities, and is not easily collapsed or deformed.
[0048] Referring to Figure 2, the reflective sheet 3 includes a substrate layer 32 and a reflective layer 31 stacked on the substrate layer 32, wherein the reflective layer 31 defines a reflective surface 31a, and the substrate layer 32 defines an opposing surface 32a. Furthermore, the surface of the protrusion 31b is defined by the reflective layer 31, so the protrusion 31b can reflect light leaking from the bottom surface 2b of the light guide plate 2 back to the light guide plate 2.
[0049] The substrate layer 32 can be a PET (Polyethylene Terephthalate) layer, and the reflective layer 31 can be a metal layer such as a silver layer or an aluminum layer. The reflective layer 31 can include multiple reflective films. For example, the reflective layer 31 can use 3M's ESR (enhanced specular reflector). The ESR utilizes multilayer film technology to integrate more than 1,000 films within a thickness of more than 100 micrometers to form a reflective surface 31a with high reflectivity.
[0050] The surface of the protrusion 31b can be formed into a dome shape. The protrusion 31b with a dome-shaped surface not only has good supporting strength, but is also less likely to scratch the light guide plate 2. Specifically, the surface of the protrusion 31b can be part of a sphere, an ellipsoid, or a rugby ball.
[0051] When the surface of the protrusion 31b is formed as part of a sphere, the height of the protrusion 31b can be 5 μm or more and 15 μm or less, more preferably 7.5 μm or more and 12.5 μm or less, and the diameter of the orthographic projection of the protrusion 31b onto the reflective surface 31a can be 200 μm or more and 300 μm or less. Thus, the protrusion 31b has a moderate size and good durability and anti-adhesion effect.
[0052] When the height of the protrusion 31b is 10 μm, the radius of curvature of the aforementioned spherical surface is preferably 500 μm or more and 1130 μm or less. Based on this relatively large radius of curvature, the protrusion 31b has a smaller effect on light deflection, thereby reducing the impact on the light output quality of the backlight module.
[0053] As shown in Figure 3, the protrusions 31b can be evenly arranged on the reflective surface 31a of the reflective sheet 3, and can be distributed in a matrix shape.
[0054] The protrusion 31b has a certain volume and area, which affects the reflection direction of light on the reflective surface 31a, and thus affects the center brightness of the backlight module. The inventors studied the influence of the average distance P (or period, pitch) between adjacent protrusions 31b on the center brightness of the backlight module when the diameter D of the orthographic projection of the protrusion 31b on the reflective surface 31a is 250 μm and the height H is 10 μm. The data obtained are shown in the table below.
[0055]
[0056] As shown in Table 1, when the period P of the protrusion 31b is greater than 0.9 mm, its impact on the center brightness of the backlight module can be controlled within 1%. When P is greater than 1.1 mm, its impact on the center brightness of the backlight module can be controlled within 0.5%. When P is greater than 3 mm, its impact on the brightness of the backlight module can be reduced to zero. Considering the anti-adhesion function: the higher the density, the more obvious the anti-adhesion effect. Therefore, the preferred range of P is between 1.1 and 1.5 mm, that is, the distance between adjacent protrusions 31b is preferably more than 1.1 mm and less than 1.5 mm. At this time, the area duty cycle of the protrusion 31b is between 4% and 2%.
[0057] Next, please refer to Figure 4. This application embodiment also provides a manufacturing equipment for manufacturing the above-mentioned reflective sheet 3. The manufacturing equipment includes a power unit and a stamping die driven by the power unit. For simplicity, Figure 4 only shows the stamping die of the manufacturing equipment.
[0058] The stamping die includes a first die 4 and a second die 5, which can be selectively moved away from each other (die opening) or closer together (die closing) under the drive of a power unit (not shown). In Figure 4, the first die is arranged on the lower side, while the second die 5 is arranged on the upper side; therefore, the first die 4 can be referred to as the lower die, and the second die 5 can be referred to as the upper die.
[0059] The first mold 4 includes an upper surface facing the second mold 5, and has a plurality of recesses 4a on the upper surface. The second mold 5 includes a lower surface facing the first mold 4, and has a plurality of protrusions 5a on the lower surface, the protrusions 5a corresponding to the shapes and positions of the recesses 4a respectively. The shapes of the protrusions 5a and the recesses 4a determine the shapes of the recesses 32b and protrusions 31b on the processed reflective sheet 3.
[0060] The first mold 4 and the second mold 5 are formed of high-hardness and high-wear-resistant materials, such as tool steel or cemented carbide, to ensure the durability and precision of the molds. Furthermore, the upper surface of the first mold 4 and the lower surface of the second mold 5 can be polished or coated to reduce friction and prevent the reflective sheet 3 from sticking to the mold and deforming during the stamping process.
[0061] Please continue to refer to Figure 4 and in conjunction with Figure 5. This application embodiment also provides a method for manufacturing a reflective sheet 3 using the above-described manufacturing equipment, the method comprising the following steps S1 to S4.
[0062] S1. Thin film positioning: The sheet-like workpiece with the protective film removed (i.e., the initial reflective sheet 3 with the protrusions 31b and recesses 32b not yet processed on both sides, thus having a complete flat main surface) is placed on the first mold 4, and the flat reflective surface 31a corresponding to the sheet-like workpiece faces the first mold 4, and the corresponding flat opposing surface 32a faces the second mold 5.
[0063] S2. Mold Closing and Pressure Holding: The second mold 5 is slowly pressed down to ensure that the initial reflective sheet 3 is evenly stressed, so as to avoid wrinkles or tears on it. When the second mold 5 slowly moves down and the protrusion 5a on it begins to contact the opposing surface 32a of the initial reflective sheet 3, a part of the initial reflective sheet 3 is deformed downward by the pressure of the protrusion 5a, thereby forming a downwardly protruding protrusion 31b on the reflective surface 31a, and the recess 4a on the first mold 4 provides clearance space for the protrusion 31b to enter.
[0064] In step S2, the downward pressure exerted by the second mold 5 on the reflector 3 can be determined based on the initial thickness of the reflector 3, typically ranging from 2 MPa to 8 MPa. A precision pressure control system (such as a hydraulic or pneumatic system) can be used to accurately control this pressure, ensuring uniform pressure distribution and preventing localized deformation or breakage of the reflector 3. Furthermore, after reaching the target pressure, it is maintained for a certain period (usually a few seconds to tens of seconds) to ensure that the protrusions 31b and recesses 32b of the reflector 3 are fully formed.
[0065] S3. Mold opening: The second mold 5 is slowly raised to avoid deformation of the reflective sheet 3 due to rapid mold opening.
[0066] S4. Remove the reflector 3 from the mold and perform necessary post-processing on the reflector 3, such as attaching a protective film to the reflective surface 31a.
[0067] As can be seen from the above, by bringing the first mold 4 and the second mold 5 close to each other to compress the sheet-like workpiece located between them, the aforementioned reflective sheet 3 with protrusions 31b and recesses 32b is obtained.
Claims
1. A reflective sheet for a backlight module, characterized in that, include: The reflective sheet has a reflective surface and an opposing surface that are opposite each other in the thickness direction, a plurality of recesses that are recessed from the opposing surface, and a plurality of protrusions that protrude from the reflective surface; wherein the plurality of protrusions and the plurality of recesses correspond one-to-one in the thickness direction.
2. The reflective sheet according to claim 1, characterized in that, The recess and the protrusion are formed by stamping the opposing surface, causing a portion of the reflective sheet to deform toward the reflective surface side.
3. The reflective sheet according to claim 1, characterized in that, In the thickness direction, the recess does not extend into the protrusion.
4. The reflective sheet according to claim 1, characterized in that, It includes a substrate layer and a reflective layer stacked on the substrate layer, the reflective layer defining the reflective surface and the substrate layer defining the opposing surface.
5. The reflective sheet according to any one of claims 1 to 4, characterized in that, The surface of the protrusion is dome-shaped.
6. The reflective sheet according to claim 5, characterized in that, The surface of the protrusion is part of a sphere.
7. The reflective sheet according to claim 6, characterized in that, The height of the protrusion is more than 5 μm and less than 15 μm, and the diameter of the orthographic projection of the protrusion on the reflective surface is more than 200 μm and less than 300 μm.
8. The reflective sheet according to claim 7, characterized in that, The height of the protrusion is 10 μm, and the radius of curvature of the sphere is greater than 500 μm and less than 1130 μm.
9. The reflective sheet according to claim 8, characterized in that, The diameter of the orthographic projection of the protrusion on the reflective surface is 250 μm, and the distance between adjacent protrusions is more than 1.1 mm and less than 1.5 mm.
10. A backlight module, characterized in that, include: A light guide plate includes a light-emitting surface and a bottom surface that are opposite to each other in the thickness direction of the light guide plate, and a light-guiding microstructure is formed on the bottom surface; The reflective sheet as described in any one of claims 1 to 9 is stacked on the bottom side of the light guide plate, and the reflective surface faces the bottom surface.
11. A manufacturing apparatus for manufacturing a reflective sheet as described in any one of claims 1 to 9, characterized in that, The manufacturing equipment includes a first mold and a second mold that are selectively moved away from or close to each other under the drive of a power unit. The first mold includes a plurality of recesses, and the second mold includes a plurality of protrusions that correspond to the shape and position of the plurality of recesses. The reflective sheet is obtained by pressing a sheet-like workpiece located between the first mold and the second mold close to each other.