A light leakage prevention backlight module, an assembling method thereof and application thereof
By setting a light-absorbing functional sheet between the light guide plate and the white film, stray light in the gap is directly absorbed, solving the problem of light leakage in the gap of the backlight module. This achieves efficient and stable light leakage suppression and cost reduction, making it suitable for high-end display products.
Patent Information
- Application Number
- CN202611005677.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-07
- Publication Date
- 2026-11-06
AI Technical Summary
In existing technologies, it is difficult to effectively solve the problem of light leakage between the light guide plate and the optical film in the backlight module, resulting in edge light leakage. Furthermore, the traditional screen printing black edge solution is costly, has low yield and poor reliability, and cannot stably achieve the ND10 level anti-leakage standard for high-end displays.
A light-absorbing functional sheet is set between the light guide plate and the white film. The light-absorbing functional sheet directly absorbs stray light in the gap. Combined with the reflection and absorption structure of the white film, light leakage is suppressed from the source of the light path, eliminating the need for the screen printing black edge process. The light-absorbing functional sheet fills the gap and absorbs stray light.
It achieves efficient and stable ND10 level light leakage suppression, reduces production costs, improves production yield, avoids screen printing defects, ensures long-term reliability, is suitable for various backlight parts, and has both optical performance and cost advantages.
Smart Images
Figure CN123047159A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of LED display technology and relates to a structure for preventing light leakage from the gap between the light guide plate and the white film. Specifically, it is a backlight module with light leakage prevention, its assembly method and application. Background Technology
[0002] Liquid crystal displays (LCDs) rely on backlight modules to provide a uniform surface light source. Edge-lit backlight modules are widely used in various display terminals such as televisions, commercial displays, and professional monitors due to their advantages of being thin, light, and low-power. A typical edge-lit backlight module mainly consists of a frame, a bottom reflector, a side LED light source, a light guide plate, and multiple layers of optical films. The LED light source enters from the side of the light guide plate, and the light is scattered inside the light guide plate before being emitted upwards. The uniformity and brightness of the emitted light are optimized by multiple layers of optical films.
[0003] With the high-end development of the display industry, terminal products have placed stringent requirements on screen contrast and edge light leakage control standards. The industry generally requires that the overall darkroom light leakage reach an ND10 level with no visible light leakage. During the assembly of the backlight module, due to the influence of the processing tolerance of the board material and the cumulative tolerance of the component assembly, micron-level air gaps will form between the upper surface of the light guide plate and the optical film. The scattered light inside the light guide plate can easily escape from the gaps and undergo multiple reflections and scatterings within the gaps, eventually escaping outward from the side of the frame, forming visible edge light leakage. This seriously damages the picture quality and fails to meet the quality standards of high-end products.
[0004] Currently, the mainstream solution in the industry for this light leakage problem is to screen-print black ink on the edges of upper optical films such as diffusion films and brightness enhancement films to form a black border. This relies on the physical blocking of the upper layer of the film to prevent stray light from entering the visible area, thereby alleviating the edge light leakage defect. However, this traditional screen-printed black border solution has several inherent shortcomings that are difficult to avoid: First, screen printing requires specialized screen printing equipment and black opaque ink. It also adds independent processes such as ink printing, drying, and quality inspection, which increases the cost of materials, equipment, and labor management, resulting in higher production costs and hindering cost reduction through large-scale production.
[0005] Secondly, the screen printing process is prone to defects such as ink dust, uneven printing thickness, and misalignment of black edges. Furthermore, the adhesion between screen printing ink and optical film base film is unstable, which can easily lead to defects such as screen bright spots, surface foreign objects, and local light-blocking failure after assembly, directly reducing the production line yield and resulting in low production process yield.
[0006] Third, under environmental stresses such as storage and transportation, dropping of the whole machine, high and low temperature cycles, and long-term use, the ink layer of the screen-printed black edge is prone to adhesion decay and micro-particle shedding, forming hidden black spot defects. These defects are difficult to detect during factory inspection, and will cause a large number of customer complaints when they enter the end market, resulting in high repair and after-sales costs.
[0007] Fourth, the black edge of the screen printing is a back-end blocking solution for light leakage. It can only block stray light that has already diffused to the upper film. It cannot eliminate the scattered light path in the gap between the light guide plate and the white film from the source. When facing the extreme light leakage prevention requirement of ND10 level, it is difficult to stably and continuously meet the testing standards. Summary of the Invention
[0008] To address the technical problems existing in the background art, this invention proposes a backlight module with light leakage prevention, its assembly method, and its application. It can directly act on the light leakage gap between the light guide plate and the optical film, absorb stray light from the source of the light path, and has low cost, high yield, and high reliability, and can stably achieve top-level light leakage prevention performance.
[0009] The objective of this invention can be achieved through the following technical solutions: A backlight module for preventing light leakage includes: a frame and a light source, a light guide plate, a reflector, and a multilayer optical film fixedly installed in the frame. The light source is located on the side light-incident surface of the light guide plate, the reflector is attached to the bottom of the light guide plate, and the multilayer optical films are stacked sequentially on the top light-emitting surface of the light guide plate. A white film is covered on the light-emitting surface of the light guide plate near the light source. A light-absorbing functional sheet is arranged on the lower surface edge of the white film facing the light guide plate. The light-absorbing functional sheet is arranged corresponding to the assembly gap between the light guide plate and the white film to fill the gap and absorb stray light overflowing from the gap.
[0010] Furthermore, the white film includes: a reflective substrate layer and a double-sided adhesive layer adhered to one side of the reflective substrate layer, the lower surface of the reflective substrate layer covering the light guide plate, and the upper surface of the reflective substrate layer being adhered to the inner side of the frame through the double-sided adhesive layer.
[0011] Furthermore, the lower surface of the reflective substrate layer is set as a white reflective surface to reflect some of the light scattered upwards to the edge position back into the light guide plate for reuse, and the upper surface of the reflective substrate layer is set as a gray light-absorbing surface to absorb excess stray light scattered upwards to the inside of the frame.
[0012] Furthermore, the light-absorbing functional sheet is a single-sided light-absorbing tape, which is attached to the junction between the edge of the white film and the light guide plate, and completely covers the horizontal projection area of the assembly gap between the light guide plate and the white film.
[0013] Furthermore, the light-absorbing functional sheet includes: a light-absorbing substrate layer and a pressure-sensitive adhesive layer coated on one side of the light-absorbing substrate layer. The pressure-sensitive adhesive layer is bonded and fixed to the lower surface of the white film so that the exposed surface of the light-absorbing substrate layer faces the light guide plate.
[0014] Furthermore, the light-absorbing substrate layer is made of a black or dark gray polymer film with a visible light absorption rate greater than %, and the pressure-sensitive adhesive layer is made of a black light-blocking colloid.
[0015] Furthermore, a ring of light-shielding adhesive is coated between the edge of the uppermost optical film and the frame.
[0016] Furthermore, the assembly method of the backlight module includes the following steps: S1. Lay the reflective sheet flat at the bottom of the frame, covering the entire load-bearing area at the bottom of the frame; S2. The light guide plate, the light source and the multi-layer optical film are sequentially installed into the frame. The light guide plate is placed above the reflective sheet, the light source is arranged along the side of the light guide plate, and the multi-layer optical film is sequentially laid above the light guide plate. S3. Assemble and fix the white film with pre-made light absorption functional sheets on the edge between the frame and the light guide plate on the side where the light source is installed, so that the light absorption functional sheets on the lower surface of the white film are attached to the upper surface of the light guide plate, filling the assembly gap between the light guide plate and the white film. S4. Apply a layer of light-shielding adhesive between the edge of the top optical film and the frame to complete the encapsulation of the backlight module.
[0017] Furthermore, in step S3, the light-absorbing functional sheet is prefabricated on the surface edge of the white film using any one of the following methods: die-cut light-absorbing tape application, edge spraying, or adhesive curing.
[0018] A liquid crystal display device using the backlight module includes: a liquid crystal panel, and a backlight module disposed on the back of the liquid crystal panel to provide a uniform surface light source for the liquid crystal panel.
[0019] The beneficial effects of this invention: The backlight module with light leakage prevention, its assembly method, and its application provided by this invention, by setting a light-absorbing functional sheet on the edge of the white film facing the light guide plate, directly corresponds to the assembly gap between the light guide plate and the white film where light leakage occurs, absorbing stray light overflowing from the light source. This differs from the traditional method of blocking the back end of the optical film with black edges printed on the screen, fundamentally suppressing edge light leakage, stably meeting the stringent light leakage control standards of high-end displays, eliminating the entire screen printing process, avoiding process defects such as screen printing ink dust, uneven printing, and coating peeling, effectively improving production yield, and simplifying production. By controlling the process, the overall manufacturing cost is reduced. The light-absorbing functional sheet has a thin and light-reducing structure, which fills the gaps without causing secondary optical defects such as uneven brightness and Newton's rings. Combined with the double-sided partitioned reflective and light-absorbing structure of the white film, it takes into account both light energy utilization and stray light suppression. The light-absorbing functional sheet and the white film can be integrally molded. After vibration, drop and high and low temperature cycle tests, no hidden black spots or failures occurred. The overall structure is easy to assemble and can be flexibly adapted to various backlight parts that are prone to gaps and light leakage. It has strong versatility and has multiple advantages in optical performance, mass production cost and long-term reliability. Attached Figure Description
[0020] Figure 1 This is a three-dimensional schematic diagram of the backlight module of the present invention.
[0021] Figure 2 for Figure 1 A partially enlarged schematic diagram of the cross-section at point AA.
[0022] Figure 3 This is a schematic diagram of the structure of the white film of the present invention.
[0023] Figure 4 This is a schematic diagram of the structure of the light-absorbing functional chip of the present invention. Detailed Implementation
[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0025] like Figures 1-2As shown, this invention provides a backlight module with light leakage prevention, comprising: a frame 1, a light source 2, a light guide plate 3, a reflective sheet 4, and a multi-layer optical film 5. The frame 1 serves as the supporting skeleton of the entire backlight module, having a bottom supporting plane and surrounding side walls for fixing the light source 2, light guide plate 3, reflective sheet 4, and multi-layer optical film 5 within the frame 1. The light source 2 uses an LED strip, positioned on the side light-incident surface of the light guide plate 3, arranged along the side of the light guide plate 3, and positioned between the side wall of the frame 1 and the side of the light guide plate 3. Light emitted from the light source 2 enters the light guide plate 3 from the side, converting a point / line light source into a surface light source. The reflective sheet 2 is laid flat on the bottom supporting area of the frame 1 and adheres to the bottom of the light guide plate 3 to reflect and recover light leaking downwards from the light guide plate 3, improving light energy utilization. The multilayer optical film 5, consisting of diffusion films, brightness enhancement films, etc., is stacked sequentially on the top light-emitting surface of the light guide plate 3, and is confined by the perimeter of the frame 1. A ring of light-shielding adhesive layer 8 is coated between the edge of the uppermost optical film 5 and the frame 1. The light-shielding adhesive layer 8 serves as an encapsulation structure and also has a light-shielding function, blocking the light leaking out from the side and reducing the probability of light leakage from the side of the frame 1.
[0026] Among them, a white film 6 is covered on the light-emitting surface of the light guide plate 3 near the light source 4, such as Figure 3 As shown, the white film 6 includes: a reflective substrate layer 61 and a double-sided adhesive layer 62 adhered to one side of the reflective substrate layer 61. The lower surface of the reflective substrate layer 61 covers the light guide plate 3, and the upper surface of the reflective substrate layer 61 is adhered to the inner side of the frame 1 through the double-sided adhesive layer 62. Specifically, the thickness of the double-sided adhesive layer 62 ranges from 0.03mm to 0.15mm, and the thickness of the reflective substrate layer 61 ranges from 0.055mm to 0.25mm. The lower surface of the reflective substrate layer 61 is set as a white reflective surface to reflect some of the light scattered upwards to the edge position inside the light guide plate 3 back into the light guide plate 3 for reuse, thereby improving the overall light output brightness of the backlight assembly, reducing the power consumption of the light source, and optimizing the overall brightness uniformity to avoid local bright spots. The upper surface of the reflective substrate layer 61 is set as a gray light-absorbing surface to absorb excess stray light scattered upwards to the inner side of the frame 1, preventing stray light from repeatedly reflecting inside the frame 1 and then re-entering the visible area, thus aggravating edge light leakage.
[0027] Due to manufacturing tolerances and cumulative assembly tolerances, a micron-level air gap naturally exists between the light guide plate 3 and the white film 6. This gap is the core source of stray light scattering multiple times and escaping outward, forming visible light leakage at the edge. Therefore, a light-absorbing functional sheet 7 is set on the lower surface edge of the white film 6 facing the light guide plate 3. The light-absorbing functional sheet 7 is arranged corresponding to the assembly gap between the light guide plate 3 and the white film 5 to fill the gap and absorb stray light overflowing from the gap, thereby directly blocking the light leakage source. This is different from the traditional solution of simply screen printing black ink at the edge of the optical film to block light leakage. It suppresses light leakage at the source and avoids defects such as ink dust, uneven printing, film peeling, and hidden black spots caused by long-term use caused by screen printing. At the same time, it can stably achieve the high-end display standard of ND10 level with no visible light leakage in a dark room.
[0028] In one embodiment of this application, the light-absorbing functional sheet 7 uses single-sided light-absorbing tape. The tape is attached to the junction between the edge of the white film 6 and the light guide plate 3, completely covering the horizontal projection area of the assembly gap between the light guide plate 3 and the white film 6. The width of the light-absorbing functional sheet 7 is set to 0.3mm to 1.5mm, preferably 0.8mm. This size can completely block the gap projection within the entire tolerance range without excessively occupying the effective reflective area of the white film 6 and increasing material costs. The thickness of the light-absorbing functional sheet 7 is controlled between 0.01mm and 0.05mm, preferably 0.011mm. This ultra-thin thickness can fill micron-level air gaps while avoiding secondary optical defects such as Newton's rings and uneven local brightness caused by film stacking and compression. Specifically, as... Figure 4 As shown, the light-absorbing functional sheet 7 includes: a light-absorbing substrate layer 71 and a pressure-sensitive adhesive layer 72 coated on one side of the light-absorbing substrate layer 71. The pressure-sensitive adhesive layer 72 is bonded and fixed to the lower surface of the white film 6 so that the exposed surface of the light-absorbing substrate layer 71 faces the light guide plate 3. The light-absorbing substrate layer 71 is made of a black or dark gray polymer film with a visible light absorption rate greater than 90%. The optional material is black PET or polyimide film, which is resistant to high temperatures, thermal cycling, and is not prone to powder shedding. The pressure-sensitive adhesive layer 72 uses a black light-shielding adhesive to form a complete light-absorbing path without any blind spots in the entire light-absorbing functional sheet 7. During operation, after the light source 2 enters the light guide plate 3 and completes the light homogenization, some scattered light overflows upwards from the upper surface of the light guide plate 3. Stray light directly contacts the light-absorbing substrate layer 71 and the black pressure-sensitive adhesive layer 72 and is quickly absorbed and significantly attenuated, preventing multiple scattering within the gap air layer and completely blocking the path of stray light to the sides and the visible area of the liquid crystal.
[0029] In other alternative embodiments, the light-absorbing functional sheet 7 is not limited to single-sided light-absorbing tape; it can also be integrally formed with a black light-absorbing coating on the lower surface edge of the white film 6 through spraying or dispensing curing, achieving the same gap-filling and stray light absorption effects. Furthermore, this arrangement of the light-absorbing functional sheet 7 can be reused in other locations prone to light leakage, such as the gap between the light guide plate 3 and the frame 1, and the gaps between the layers of the multi-layer optical films 5, adapting to different product structures.
[0030] The present invention also provides an assembly method for the backlight module, comprising the following steps: S1. Lay the reflector 4 flat at the bottom of the frame 1, covering the bottom bearing area of the frame 1; the reflector 4 can recover the light leaking downward from the light guide plate 3, further improving the light energy utilization rate.
[0031] S2. The light guide plate 3, the light source 2 and the multi-layer optical film 5 are sequentially installed into the frame 1. The light guide plate 3 is placed above the reflector 4. The light source 2 is arranged along the side of the light guide plate 3. The multi-layer optical film 5 is sequentially laid on top of the light guide plate 3. The multi-layer optical film 5 includes diffusion film, brightness enhancement film and other film materials, which are used to uniform light output and enhance brightness.
[0032] S3. The white film 6 with the pre-made light absorption functional sheet 7 on the edge is assembled and fixed between the frame 1 and the light guide plate 3 on the side where the light source 2 is installed, so that the light absorption functional sheet 7 on the lower surface of the white film 6 is attached to the upper surface of the light guide plate 3, filling the assembly gap between the light guide plate 3 and the white film 6; the ultra-thin thickness of the light absorption functional sheet 7 ensures the flatness of the film stack and eliminates the gap scattering light path.
[0033] S4. Apply a layer of light-shielding adhesive 8 between the edge of the uppermost optical film 5 and the frame 1 to complete the encapsulation of the backlight module.
[0034] In step S3, the light-absorbing functional sheet is prefabricated on the surface edge of the white film using any one of the following methods: die-cut light-absorbing tape application, edge spraying, or adhesive curing. This eliminates the traditional black edge printing process for optical films, saving on screen printing equipment, special inks, and associated process control. The overall production cost is reduced by approximately 15% compared to traditional screen printing solutions. It also completely eliminates process defects such as ink dust, printing misalignment, and film peeling caused by screen printing, significantly improving production yield. After high and low temperature cycling, machine vibration, and drop reliability tests, the light-absorbing functional sheet shows no peeling, no powder shedding, and no hidden black spots, significantly reducing the risk of customer returns and after-sales complaints.
[0035] This invention also provides a liquid crystal display device using the aforementioned backlight module, comprising: a liquid crystal panel, and a backlight module disposed on the back of the liquid crystal panel to provide a uniform surface light source for the liquid crystal panel. This liquid crystal display device can be applied to high-end display products such as large-screen TVs, commercial displays, and professional monitors. The overall device achieves a stable ND10 level of light leakage (visually invisible) at all four edges during darkroom testing, significantly improving contrast and image visual quality.
[0036] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.
Claims
1. A backlight module for preventing light leakage, characterized in that, include: The frame (1) includes a light source (2), a light guide plate (3), a reflector (4), and a multi-layer optical film (5) fixedly installed inside the frame (1). The light source (2) is located on the side light-incident surface of the light guide plate (3). The reflector (2) is attached to the bottom of the light guide plate (3). The multi-layer optical film (5) is stacked in sequence on the top light-emitting surface of the light guide plate (3). A white film (6) is covered on the light-emitting surface of the light guide plate (3) near the light source (4). A light-absorbing functional sheet (7) is provided on the lower surface edge of the white film (6) towards the light guide plate (3). The light-absorbing functional sheet (7) is arranged corresponding to the assembly gap between the light guide plate (3) and the white film (5) to fill the gap and absorb stray light overflowing from the gap.
2. The backlight module according to claim 1, characterized in that, The white film (6) includes a reflective substrate layer (61) and a double-sided adhesive layer (62) pasted on one side of the reflective substrate layer (61). The lower surface of the reflective substrate layer (61) covers the light guide plate (3), and the upper surface of the reflective substrate layer (61) is attached to the inside of the frame (1) through the double-sided adhesive layer (62).
3. The backlight module according to claim 2, characterized in that, The lower surface of the reflective substrate layer (61) is set as a white reflective surface to reflect back some of the light scattered upward to the edge position inside the light guide plate (3) for secondary use. The upper surface of the reflective substrate layer (61) is set as a gray light-absorbing surface to absorb the excess stray light scattered upward to the inside of the frame (1).
4. The backlight module according to claim 1, characterized in that, The light-absorbing functional sheet (7) is a single-sided light-absorbing tape. The light-absorbing tape is attached to the junction between the edge of the white film (6) and the light guide plate (3), and completely covers the horizontal projection area of the assembly gap between the light guide plate (3) and the white film (6).
5. The backlight module according to claim 4, characterized in that, The light-absorbing functional sheet (7) includes: a light-absorbing substrate layer (71) and a pressure-sensitive adhesive layer (72) coated on one side of the light-absorbing substrate layer (71). The pressure-sensitive adhesive layer (72) is bonded and fixed to the lower surface of the white film (6) so that the exposed surface of the light-absorbing substrate layer (71) faces the light guide plate (3).
6. The backlight module according to claim 5, characterized in that, The light-absorbing substrate layer (71) is a black or dark gray polymer film with a visible light absorption rate of more than 90%, and the pressure-sensitive adhesive layer (72) is a black light-blocking colloid.
7. The backlight module according to claim 1, characterized in that, A ring of light-shielding adhesive layer (8) is coated between the edge of the uppermost optical film (5) and the frame (1).
8. A method for assembling a backlight module according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Lay the reflective sheet flat at the bottom of the frame, covering the entire load-bearing area at the bottom of the frame; S2. The light guide plate, the light source and the multi-layer optical film are sequentially installed into the frame. The light guide plate is placed above the reflective sheet, the light source is arranged along the side of the light guide plate, and the multi-layer optical film is sequentially laid above the light guide plate. S3. Assemble and fix the white film with pre-made light absorption functional sheets on the edge between the frame and the light guide plate on the side where the light source is installed, so that the light absorption functional sheets on the lower surface of the white film are attached to the upper surface of the light guide plate, filling the assembly gap between the light guide plate and the white film. S4. Apply a layer of light-shielding adhesive between the edge of the top optical film and the frame to complete the encapsulation of the backlight module.
9. The assembly method according to claim 8, characterized in that, In step S3, the light-absorbing functional sheet is prefabricated on the surface edge of the white film using any one of the following methods: die-cut light-absorbing tape application, edge spraying, or adhesive curing.
10. A liquid crystal display device using the backlight module according to any one of claims 1-7, characterized in that, include: The backlight module is located on the back of the LCD panel to provide a uniform surface light source for the LCD panel.