A double-layer light guide plate backlight module for partitioned light control of a side-in backlight display

Abstract

The utility model relates to backlight module technical field discloses a kind of double-layer light guide plate backlight module for side-in backlight display zoning light control, including membrane piece assembly, first light guide plate, second light guide plate, reflecting sheet, backplate and the LED light source component of the side edge of first light guide plate and / or second light guide plate are sequentially arranged from top to bottom;Wherein, the bottom surface or surface of first light guide plate and second light guide plate is provided with dot structure for light guide and light emission, and the dot design pattern on first light guide plate and second light guide plate is same;When first light guide plate and second light guide plate are stacked and assembled, first light guide plate is set relative to second light guide plate horizontal rotation 180 °.The utility model effectively solves the problem of low contrast and impure black display caused by the fact that traditional side-in backlight cannot realize effective zoning light control, while maintaining the lightweight structure of backlight module.

Description

Technical Field

[0001] This utility model relates to the field of backlight module technology, and in particular to a double-layer light guide plate backlight module for side-lit backlight display with zoned light control. Background Technology

[0002] In liquid crystal display devices, the backlight module is a key component providing the light source. Edge-lit backlight technology places LED (light-emitting diode) light strips on the side of a light guide plate (LGP). Light enters from the side, is reflected and scattered within the LGP, and then exits uniformly from the front. This design allows the backlight module, and even the entire display device, to be made very thin, and is therefore widely used in consumer electronics products such as televisions, monitors, and laptops where thickness is a constraint.

[0003] However, traditional edge-lit backlighting typically uses a single light guide plate and a single LED strip that emits light throughout, resulting in uniform backlight output that cannot be locally adjusted. This means that the entire backlit area is illuminated regardless of the content being displayed. Even when displaying dark or black scenes, the backlight remains, leading to impure blacks, low contrast, and difficulty in achieving high-quality high dynamic range (HDR) display effects.

[0004] To improve contrast and image quality, local dimming technology was developed. This technology divides the backlight into multiple independently controllable zones and dynamically adjusts the brightness of the corresponding zones according to the content displayed, achieving the effect of "bright when it should be bright, dark when it should be dark." Currently, the mainstream solution for implementing local dimming is direct-lit backlighting, which arranges the LED array directly below the diffuser. By independently controlling the LED groups in different positions, precise local dimming can be achieved, significantly improving contrast. However, the disadvantage of direct-lit backlighting is that a certain optical distance needs to be reserved between the LCD panel and the LED array, resulting in an increase in the thickness and size of the display device, which contradicts the trend of thinner and lighter consumer electronics devices.

[0005] Therefore, the industry has been committed to achieving effective local dimming while maintaining the slim and lightweight advantages of edge-lit backlighting. Existing attempts, such as designing complex dot patterns on a single-layer light guide plate or combining additional optical films with side-lit LEDs for local dimming, often face significant technical challenges. These challenges include, but are not limited to: obvious bright-dark boundaries (halo effect) between adjacent dimming zones; uncontrollable light leakage in non-target areas when a zone is lit; decreased overall optical uniformity; and brightness loss or vignetting due to complex light control. Designing a structure that, within an edge-lit backlighting architecture, can achieve independent dimming across multiple zones while ensuring excellent light uniformity, high contrast, and maintaining the module's slim profile has become a pressing technical problem to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a double-layer light guide plate backlight module for side-lit backlight display with local dimming, which aims to solve the problems of low contrast and impure black display caused by the inability of traditional side-lit backlight to achieve effective local dimming, while maintaining the thin and light structure of the backlight module, thereby achieving high contrast and uniform display effect without increasing the thickness of the module.

[0007] To achieve the above objectives, the following technical solution is adopted: A double-layer light guide plate backlight module for side-lit backlight display with local dimming includes, from top to bottom, a film assembly, a first light guide plate, a second light guide plate, a reflective sheet, a back plate, and an LED light source assembly disposed on the side of the first light guide plate and / or the second light guide plate; wherein, the bottom or surface of the first light guide plate and the second light guide plate are provided with a dotted structure for guiding and emitting light, and the dotted design pattern on the first light guide plate and the second light guide plate is the same; when the first light guide plate and the second light guide plate are stacked and assembled, the first light guide plate is horizontally rotated 180° relative to the second light guide plate.

[0008] Preferably, in the above-mentioned double-layer light guide plate backlight module for side-lit backlight display with local dimming, the first light guide plate is the upper light guide plate close to the film assembly, and the second light guide plate is the lower light guide plate close to the reflector.

[0009] Preferably, in the above-mentioned double-layer light guide plate backlight module for side-lit backlight display with zoned light control, the LED light source assembly includes a plurality of LED light strips arranged along one side of the first light guide plate and the second light guide plate, and the plurality of LED light strips are divided into at least four light-controlling sections that can be independently lit or turned off in the extension direction along the side.

[0010] Preferably, in the above-mentioned double-layer light guide plate backlight module for side-lit backlight display with zoned light control, the dot structure on the first light guide plate and the second light guide plate is configured such that: when the first light-controlling section of the plurality of LED light strips is lit and the other sections are off, the first display area corresponding to the first light-controlling section in the light-emitting surface of the backlight module is lit; when the second light-controlling section is lit and the other sections are off, the second display area corresponding to the second light-controlling section in the light-emitting surface is lit.

[0011] Preferably, in the above-mentioned double-layer light guide plate backlight module for side-lit backlight display with local dimming, the first light guide plate and the second light guide plate have the same or different thicknesses.

[0012] Preferably, in the above-mentioned double-layer light guide plate backlight module for side-lit backlight display with local dimming, the reflective sheet is attached to the bottom surface of the second light guide plate, and the back plate supports and fixes the reflective sheet, the second light guide plate, the first light guide plate and the film assembly.

[0013] Preferably, in the above-mentioned double-layer light guide plate backlight module for side-lit backlight display with zoned light control, the at least four independently controllable light control sections, in conjunction with the dot structure of the first and second light guide plates, realize the division of the display screen into at least four independent light control zones in the direction parallel to the LED light strip arrangement.

[0014] The beneficial effects of this utility model are: This invention achieves precise zoned light control of the displayed image by employing a double-layer light guide plate structure, designing both light guide plates with the same dot pattern and assembling them by rotating them horizontally by 180°, combined with multiple independently illuminating LED light strip zones on the side. This structure ensures that when a designated LED zone is illuminated, light is precisely guided to the corresponding display area, significantly suppressing light leakage in non-target areas, thereby greatly improving image contrast and black purity. Simultaneously, the collaborative light path design of the double-layer light guide plates effectively optimizes light distribution, overcoming the uneven brightness and vignetting defects that easily occur with single-layer light guide plates in zoned light control, ensuring highly uniform brightness across the entire light-emitting surface. Furthermore, this module is entirely based on a side-lit backlight architecture, eliminating the need for additional light mixing distance, resulting in a compact overall structure that facilitates the design and manufacturing of thinner and lighter display devices. Attached Figure Description

[0015] Figure 1 A schematic diagram of a double-layer light guide plate backlight module for zoned light control in a side-lit backlight display, according to an embodiment of the present invention, is shown.

[0016] Figure 2The diagram shows a single-zone illumination state of a double-layer light guide plate backlight module for side-lit backlight display with zoned light control according to an embodiment of the present invention, wherein (a)-(d) represent schematic diagrams of different zone illumination states.

[0017] Figure 3 The diagram shows multiple lighting states of a double-layer light guide plate backlight module for side-lit backlight display with zoned light control according to an embodiment of the present invention, wherein (a)-(c) represent schematic diagrams of different lighting states of the zones.

[0018] Figure 4 The diagram shows an optical test curve of a double-layer light guide plate backlight module for side-lit backlight display with local dimming, according to an embodiment of the present invention.

[0019] Figure 5 The diagram shows the actual light emission effect of a double-layer light guide plate backlight module for zoned light control in a side-lit backlight display according to an embodiment of the present invention.

[0020] Figure label: 1. Diaphragm assembly; 2. First light guide plate; 3. Second light guide plate; 4. Reflective sheet; 5. Back plate; 6. LED light source assembly; 601. LED light strip; 6-1. First LED module; 6-2. Second LED module; 6-3. Third LED module; 6-4. Fourth LED module; 7. Light emitting surface of backlight module. Detailed Implementation

[0021] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0022] The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples.

[0023] This utility model embodiment provides a double-layer light guide plate backlight module for local dimming in side-lit backlight displays, such as... Figure 1As shown, the double-layer light guide plate backlight module for side-lit backlight display with local dimming includes, from top to bottom, a film assembly 1, a first light guide plate 2, a second light guide plate 3, a reflective sheet 4, a back plate 5, and an LED light source assembly 6 disposed on the side of the first light guide plate 2 and / or the second light guide plate 3; wherein, the bottom or surface of the first light guide plate 2 and the second light guide plate 3 are provided with a dotted structure for guiding and emitting light, and the dotted design pattern on the first light guide plate 2 and the second light guide plate 3 is the same; when the first light guide plate 2 and the second light guide plate 3 are stacked and assembled, the first light guide plate 2 is horizontally rotated 180° relative to the second light guide plate 3.

[0024] In this embodiment of the invention, the diaphragm assembly 1 typically includes optical films such as a brightness enhancement film and a diffusion film arranged from top to bottom. Their function is to further diffuse, focus, and homogenize the light emitted from the light guide plate, thereby improving frontal brightness and viewing angle, and enhancing the optical uniformity of the image. The first light guide plate 2 and the second light guide plate 3 are core light guide components, typically made of optical-grade transparent polymers, such as polymethyl methacrylate or polycarbonate. The double-layered light guide plates, with identical dot patterns but rotated 180 degrees, primarily achieve finer control and redistribution of side-incident light through the spatial interlacing and complementarity of the two dot structures. This structure effectively breaks the optical symmetry of the dot distribution of a single light guide plate. When a certain LED zone is lit, it is more conducive to constraining and guiding the light to the target display area, while significantly suppressing the lateral diffusion of light to non-target areas, thereby improving the optical isolation between zones and reducing light leakage.

[0025] The reflector 4 is attached to the bottom surface of the second light guide plate 3. Its function is to reflect the light that leaks downward through the light guide plate back into the light guide plate for reuse, thereby significantly improving the light energy utilization rate. The back plate 5 is usually made of metal or high-rigidity plastic. Its function is to provide mechanical support and protection for the entire backlight module, and to integrate and fix all the above-mentioned optical components and LED light source assembly 6 together to ensure the stability of the structure.

[0026] The LED light source assembly 6 includes at least one LED strip, which is mounted on at least one side light-incident surface of the first light guide plate 2 and / or the second light guide plate 3. The LED strip extends along the side of the light guide plate and is divided into multiple independently driveable segments, each segment corresponding to control one or more display zones. By independently controlling the on / off state and brightness of the LEDs in different segments, the switching and dimming of the corresponding backlight areas can be achieved, thereby achieving the purpose of zoned light control.

[0027] As some exemplary embodiments, the thickness of both the first light guide plate 2 and the second light guide plate 3 can be from 0.5 mm to 3.0 mm, for example, 1.0 mm. Their dot matrix structure can be micron-sized circular, elliptical, or polygonal concave or convex dots, formed by laser engraving or injection molding. The density and / or size of the dots on the surface of the light guide plate can be gradually designed according to the brightness requirements of the target area. The LED light source assembly 6 can specifically include an LED strip mounted on the same side of the double-layer light guide plate, which is divided into four independent light-controlling segments along its length, controlling the four corresponding zones of the displayed image in the horizontal direction. Alternatively, the LED light source assembly 6 can also include LED strips mounted on both sides of the light guide plate to achieve more complex two-dimensional zone control.

[0028] It should be understood that the above-described specific details regarding materials, thickness, dot shape, number of LED zones, and arrangement are merely examples provided to facilitate understanding of this utility model and are not intended to limit the scope of protection of this utility model. In practical applications, those skilled in the art can adaptively adjust and change the number of layers, thickness, dot design parameters, LED arrangement, and zoning logic of the light guide plate according to specific display size, number of zones, brightness, and uniformity requirements. Such variations and improvements based on the core concept of this utility model should all fall within the scope of protection of this utility model.

[0029] In some embodiments, such as Figure 1 As shown, the first light guide plate 2 is positioned as the upper light guide plate close to the diaphragm assembly 1, while the second light guide plate 3 is positioned as the lower light guide plate close to the reflector 4, forming an optimized optical stacking sequence. This stacking relationship is crucial for achieving efficient local light control and excellent optical uniformity.

[0030] In this configuration, light incident from the LED light source assembly 6 first enters the second light guide plate 3 (lower layer). The dotted structure of the second light guide plate 3 initially guides, scatters, and partially emits the light. Some light that fails to exit directly from the front of the second light guide plate 3, or light reflected upwards by its bottom dotted structure, continues to enter the upper first light guide plate 2 (upper layer). After receiving light from the lower layer, the first light guide plate 2, through a 180-degree rotation and the same dotted structure as the lower layer, modulates and redistributes the light a second time. This dual-layer sequential light path design, with initial lower-layer modulation and secondary upper-layer fine-tuning, allows the light to undergo two independent dotted effects in the vertical direction, greatly enhancing the control over the light path direction. When the LEDs in a certain zone are lit, this coordinated modulation can more effectively focus the light on the vertical emission direction of the target zone, while more effectively suppressing crosstalk of light to non-target zones in the horizontal direction, thus achieving sharper zone boundaries and lower background light leakage.

[0031] As an exemplary implementation, the first light guide plate 2 and the second light guide plate 3 can be made of materials of the same thickness, such as 1.0 mm thick PMMA (polymethyl methacrylate), to ensure the consistency and predictability of light propagation characteristics between the two layers. In other examples, different thickness combinations can also be used, such as making the lower second light guide plate 3 slightly thicker than the upper first light guide plate 2 (e.g., the second light guide plate is 1.2 mm thick, and the first light guide plate is 0.8 mm thick). Such a design may be more conducive to the initial diffusion and mixing of light, while the upper layer focuses on fine-tuning the uniformity of the final light-emitting surface. The dots on the two light guide plates can be micro-conical conical dimples formed by laser engraving, with their diameter and depth gradually distributed according to the distance from the LED light source.

[0032] It should be noted that the above descriptions of the thickness relationship, specific materials, and dot shape of the upper and lower light guide plates are merely several specific examples to illustrate how the technical solution of this utility model is implemented. Defining the first light guide plate as the upper layer and the second light guide plate as the lower layer, and explaining their synergistic principle, is the core of this embodiment. Those skilled in the art should understand that, without departing from the core concept of rotating the double-layer light guide plates to achieve zoned light control, various adjustments and replacements can be made to the absolute thickness, relative thickness ratio, specific dot parameters, and optical materials used of the upper and lower light guide plates according to actual optical design goals (such as the number of zones, module thickness, target brightness, etc.). Any structural modifications based on the same working principle should be considered to fall within the protection scope of this utility model.

[0033] In some embodiments, such as Figure 1 As shown, the thicknesses of the first light guide plate 2 and the second light guide plate 3 are designed to be the same or different. This design freedom provides the double-layer light guide plate structure of this utility model with the flexibility to adapt to different optical performance requirements and product forms. The choice of thickness directly affects the propagation path, mixing degree, and final light output control precision of light within each light guide plate layer.

[0034] When the first light guide plate 2 and the second light guide plate 3 have the same thickness, for example, both are 1.0 mm, this symmetrical design facilitates the simplification and standardization of manufacturing and assembly processes. More importantly, it ensures that the optical path length of light traveling through the upper and lower layers is basically the same, which is beneficial for achieving a stable and predictable light distribution and superposition effect. This is a preferred solution for designs that pursue uniform light output and simplified optical simulation.

[0035] When the thicknesses of the two light guide plates differ, more precise optical performance tuning can be achieved. As an example implementation, the second light guide plate 3 (lower layer), closer to the LED light source, can be thicker than the first light guide plate 2 (upper layer), farther from the light source; for example, the lower layer could be 1.5 mm thick while the upper layer is 0.8 mm thick. The thicker lower light guide plate provides more space for initial diffusion and mixing of side-incident light, helping to smooth out potential localized brightness unevenness caused by the LED point light source arrangement before the light reaches the upper layer, thus laying a more uniform light source foundation for zoned light control. Simultaneously, the relatively thinner upper light guide plate can more quickly and accurately perform final spatial modulation of the light from the lower layer, improving the sharpness of light control at zone boundaries. In another example, the upper light guide plate can also be slightly thicker than the lower layer, which may be useful in applications where the upper layer needs to perform more dominant light-directing functions.

[0036] It should be understood that the above descriptions of specific thickness values ​​(such as 1.0 mm, 1.5 mm, 0.8 mm) and relative thickness relationships are merely limited examples illustrating how the technical solution of this utility model can be specifically implemented. The thicknesses of the first and second light guide plates can be widely selected and combined according to the actual product size (such as the size of a television), the number of target zones, brightness requirements, and overall thickness limitations. For example, the thickness of each light guide plate can be independently selected within a range of 0.5 mm to 2.0 mm or even wider. The core of this utility model lies in achieving zoned light control through the collaborative work of two light guide plates with a specific rotational relationship. Their thickness relationship is one of the adaptable key parameters, rather than a fixed limiting condition. Any design that adaptively adjusts the thickness of the two light guide plates based on the concept of this utility model should be covered within the protection scope of this utility model.

[0037] In some embodiments, such as Figure 1 As shown, the reflector 4 is positioned to adhere to the bottom surface of the second light guide plate 3, while the back plate 5 is used to support and fix the reflector 4, the second light guide plate 3, the first light guide plate 2, and the diaphragm assembly 1 as a whole. This structural relationship constitutes the physical basis for the stable optical performance and reliable mechanical structure of the backlight module.

[0038] Specifically, the reflector 4 is tightly attached to the bottom surface of the second light guide plate 3, and its main function is to efficiently recover and utilize light. During the transmission and scattering of light within the double-layer light guide plate, some light inevitably leaks downwards. The reflector 4 can reflect almost all of the downward light back into the light guide plate, allowing it to re-participate in the upward light emission process, thereby significantly improving the optical efficiency (brightness) and uniformity of the backlight module. In the double-layer light guide plate architecture of this invention, this function of the reflector 4 is particularly important for ensuring sufficient and controlled light flux entering the upper light guide plate from the lower light guide plate, and is the fundamental guarantee for maintaining high brightness and achieving effective zoned light control.

[0039] The backplate 5 serves as the structural substrate and outer shell of the entire backlight module. Its core function is to provide a robust and flat support for all the precision optical films and light guide plate assemblies, and to ensure that each component maintains a precise relative position and tight fit after assembly. This prevents optical performance degradation (such as the formation of Newton's rings, dark spots, or uneven brightness) due to displacement, deformation, or separation during transportation or use. By sequentially stacking and fixing the reflector 4, the second light guide plate 3, the first light guide plate 2, and the film assembly 1 onto the backplate 5, an integrated optical engine is formed. Its structural stability is directly related to the long-term consistency and reliability of the local dimming effect.

[0040] As some exemplary embodiments, the reflective sheet 4 can be made of white, high-reflectivity PET (polyethylene terephthalate) substrate, and the surface can have a microbead or foam structure to enhance the diffuse reflection effect. The back plate 5 can be stamped from an aluminum alloy plate, with vertically bent sidewalls at its edges. The sidewalls can be designed with clips, studs, or adhesive grooves to fix it to the frame or front frame of the diaphragm assembly 1. During assembly, the reflective sheet 4 can be directly attached to the bottom plate of the back plate 5 using double-sided tape or pressure-sensitive adhesive, followed by the second light guide plate 3, the first light guide plate 2, and the diaphragm assembly 1 in sequence, and finally pressed and fixed by the frame or tape.

[0041] It must be pointed out that the above descriptions of the reflective sheet material (such as white PET) and the back plate material and fixing method (such as aluminum alloy stamping parts with buckles) are merely specific examples to explain how the structure of this utility model is realized. The scope of protection of this utility model is by no means limited to these examples. For example, the reflective sheet 4 can also be made of other highly reflective materials or composite structures; the back plate 5 can also be made of other metal materials, engineering plastics or composite materials, and fixed by various methods such as screw fastening and ultrasonic welding. Any technical solution that adopts the basic structural concept of "the reflective sheet is attached to the bottom surface of the lower light guide plate, and all optical layers are supported and fixed by the back plate" to achieve the purpose of supporting, fixing and improving light efficiency, regardless of how its specific materials and fixing details change, falls within the scope of protection of this utility model.

[0042] In some embodiments, such as Figure 2 As shown, the LED light source assembly 6 includes a plurality of LED light strips 601 arranged along one side of the first light guide plate 2 and the second light guide plate 3, and the plurality of LED light strips 601 are divided into at least four light-controlling sections that can be independently lit or turned off in the extending direction along the side.

[0043] The technical function of the above configuration is to divide the physically continuous LED light source into multiple independent light-emitting units in terms of electrical and control logic. Each independent light-controlling segment corresponds to an illumination area in the horizontal direction (X direction) of the backlight module's light-emitting surface 7. Through independent control of each light-controlling segment by an external driving circuit, the luminous flux output of different areas of the backlight module can be precisely controlled, mainly by controlling the on / off state of the corresponding LED light source components. For example, when a certain local area of ​​the display screen requires high brightness, only the LED segment corresponding to its backlight position is illuminated; while when another area of ​​the screen is black or dark, the LED segment corresponding to its backlight position is turned off, thereby achieving extremely high dynamic contrast and pure black performance. This zone control capability, combined with the aforementioned precise light guiding capability of the double-layer rotating light guide plate, jointly solves the problem of difficult-to-achieve efficient zone control in edge-lit backlights.

[0044] As an exemplary implementation, the plurality of LED light strips 601 can be specifically embodied as a physically continuous long strip-shaped LED module, which is divided into four electrically independent segments along its length by circuit design, for example, four segments of equal length, such as... Figure 1 As shown, the LED modules are positioned on both sides of the second light guide plate 3 and the first light guide plate 2, respectively, and are the first LED module 6-1, the second LED module 6-2, the third LED module 6-3, and the fourth LED module 6-4. Each segment contains several LED chips connected in series or parallel. These four segments are arranged from left to right and are responsible for driving the four backlight zones of the display screen from left to right. In another example, the multiple LED strips can also be physically separated short strip-shaped LED modules, which are arranged adjacent to each other on the side of the light guide plate. Each short strip-shaped module itself constitutes an independent light control segment, thus also realizing the zoning of the light source. The control logic can be expressed as follows: when the leftmost display zone needs to be lit, only the leftmost LED light control segment is driven; when the two middle display zones need to be lit, the two middle LED light control segments are driven.

[0045] In some embodiments, the dot structure on the first light guide plate 2 and the second light guide plate 3 is configured such that: when the first light-controlling section of the plurality of LED light strips is lit and the other sections are off, the first display area corresponding to the first light-controlling section in the light-emitting surface 7 of the backlight module is lit; when the second light-controlling section is lit and the other sections are off, the second display area corresponding to the second light-controlling section in the light-emitting surface is lit. At least four independently controllable light-controlling sections, in conjunction with the dot structure on the first light guide plate 2 and the second light guide plate 3, realize the division of the display screen into at least four independent light-controlling zones in the direction parallel to the LED light strip arrangement.

[0046] Specifically, the multiple LED light strips are designed as four LED modules: LED module 6-1, LED module 6-2, LED module 6-3, and LED module 6-4. Each LED module corresponds to illuminating a light-controlling segment on the light-emitting surface 7 of the backlight module, such as... Figure 2 As shown, the light control zones are divided into four areas: Zone 1, Zone 2, Zone 3, and Zone 4. Figure 2 As shown in (a), when the first LED module 6-1 is lit, and the second LED module 6-2, the third LED module 6-3, and the fourth LED module 6-4 are off, area 1 of the screen is lit; as shown in (a), when the first LED module 6-1 is lit, and the second LED module 6-2, the third LED module 6-3, and the fourth LED module 6-4 are off, area 1 of the screen is lit; Figure 2 As shown in (b), when the second LED module 6-2 is lit and the first LED module 6-1, the third LED module 6-3, and the fourth LED module 6-4 are off, area 3 of the screen is lit; Figure 2 As shown in (c), when the third LED module 6-3 is lit, and the first LED module 6-1, the second LED module 6-2, and the fourth LED module 6-4 are off, area 2 of the screen is lit; as shown Figure 2 As shown in (d), when the fourth LED module 6-4 is lit, the first LED module 6-1 is lit, and the second LED module 6-2 and the third LED module 6-3 are off, area 4 of the screen is lit.

[0047] like Figure 3 As shown in (a), when the first LED module 6-1 and the second LED module 6-2 are lit, and the third LED module 6-3 and the fourth LED module 6-4 are off, areas 1 and 3 of the screen are lit; Figure 3 As shown in (b), when the third LED module 6-3 and the fourth LED module 6-4 are lit, and the first LED module 6-1 and the second LED module 6-2 are off, areas 2 and 4 of the screen are lit; Figure 3 As shown in (4), when all four LED modules are lit, all four areas of the screen are fully lit, and the 80 test points in the x direction are all aligned >92% (excluding light leakage data). The screen transition is uniform and there is no problem of uneven brightness.

[0048] To verify the actual optical performance of this double-layer light guide plate backlight module, especially its light emission uniformity and local light control effect, specific optical tests were conducted. The test subject was a sample of the double-layer light guide plate backlight module manufactured according to this technical solution.

[0049] The test employed a standard optical performance testing system, including a photometer or imaging luminance meter. During testing, a series of test points were uniformly selected along the horizontal direction of the display area corresponding to the module's light-emitting surface. To accurately evaluate the performance of the core area, the test avoided the edges where optical leakage might occur. Two key variables were set in the test. First, the dot density configuration, employing two designs: a single density distribution and a distribution with localized density adjustments for different display zones. Second, the emission mode, simulating three operating states by controlling the LED light source components: all LED strips lit, only the LED strips in the first area of ​​the corresponding display screen lit, and only the LED strips in the third area of ​​the corresponding display screen lit.

[0050] The results obtained through the organization and analysis of test data are as follows: Figure 4 As shown.

[0051] First, the test results verified the effectiveness of the dot structure design. Under both single-density and zone-optimized density configurations, the module maintained good light distribution uniformity across the entire light-emitting surface. In particular, the configuration with zone-optimized density design exhibited less fluctuation and more stable light uniformity curves across various operating modes, demonstrating that optimizing the dot distribution of the double-layer light guide plate can effectively control the light path.

[0052] Secondly, the test results confirmed the accuracy of independent zoned light control. When only the LED strip corresponding to a single area was illuminated, the test curve clearly showed that the backlight module could produce concentrated and uniform brightness output in the target display area, while the brightness in non-target areas was very low. The brightness curve of the target area was smooth, without obvious dark corners or sudden drops in brightness. This indicates that the combination of LED zoned control and the light guide plate structure achieved precise local backlight illumination.

[0053] Furthermore, the test data quantifies the overall high uniformity performance of the module. In full-brightness mode with all LED strips lit simultaneously, the module achieved a peak light uniformity of 93% in the main test area. This quantitative result directly meets the requirements of high-specification displays for backlight uniformity.

[0054] Finally, the curves under different test conditions showed a stable overall trend with no abnormal fluctuations. This reflects the structural stability of the horizontally rotated and stacked double-layer light guide plate and the collaborative design of the light source partition and dot matrix, indicating that the module can maintain reliable optical performance under various working conditions.

[0055] Figure 5 The images show the actual light-emitting effect of the double-layer light guide plate backlight module in its working state, including three sub-images: (a), (b), and (c). Figure 5 These images were captured in a darkroom environment. During the test, the LED light source of the control module was in three different lighting states, and the actual light-emitting images of the corresponding light-emitting surfaces were recorded using a camera, resulting in the three sub-images mentioned above.

[0056] Figure 5 Figure (a) shows the luminous effect of the module when only a single LED strip is lit. This state corresponds to the scenario where a single backlight zone works independently. As can be observed from the figure, after the light enters from the light source side, it undergoes multiple reflections and scatterings through the dotted structure inside and on the surface of the double-layer light guide plate, forming effective light diffusion within the target zone and achieving uniform illumination of the area. This visually demonstrates that the structure has excellent guiding and distribution capabilities for light.

[0057] Figure 5 Figure (b) shows the luminous effect of the module when multiple LED strips are lit in combination. This state simulates a scenario where multiple adjacent areas in the display screen need to be lit simultaneously. The figure shows that multiple zones are lit synchronously, and the brightness distribution within each zone is relatively uniform, with natural transitions between zones. This verifies that the LED zone control and the light guide plate dot pattern design have good matching and synergy.

[0058] Figure 5 Image (c) shows the luminous effect of the module with all LED strips lit. This state corresponds to the scenario with the backlight fully on. As can be seen in the image, the brightness of the entire light-emitting surface is uniform, with no obvious local dark areas or bright spots. This result directly confirms that the rotating and stacked double-layer light guide plates can achieve highly uniform surface light source output, which is consistent with the uniformity test data mentioned above.

[0059] The above embodiments are only used to illustrate the present utility model and are not intended to limit the present utility model. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present utility model. Therefore, all equivalent technical solutions also fall within the scope of the present utility model. The patent protection scope of the present utility model should be defined by the claims.

Claims

1. A double-layer light guide plate backlight module for local dimming in edge-lit backlight displays, characterized in that: The assembly includes, from top to bottom, a film assembly (1), a first light guide plate (2), a second light guide plate (3), a reflective sheet (4), a back plate (5), and an LED light source assembly (6) disposed on the side of the first light guide plate (2) and / or the second light guide plate (3); wherein, the bottom or surface of the first light guide plate (2) and the second light guide plate (3) are provided with a dot structure for guiding and emitting light, and the dot design pattern on the first light guide plate (2) and the second light guide plate (3) is the same; when the first light guide plate (2) and the second light guide plate (3) are stacked and assembled, the first light guide plate (2) is horizontally rotated 180° relative to the second light guide plate (3).

2. The double-layer light guide plate backlight module for side-lit backlight display with local dimming as described in claim 1, characterized in that, The first light guide plate (2) is the upper light guide plate close to the diaphragm assembly (1), and the second light guide plate (3) is the lower light guide plate close to the reflector (4).

3. The double-layer light guide plate backlight module for side-lit backlight display with local dimming as described in claim 2, characterized in that, The LED light source assembly (6) includes a plurality of LED light strips arranged along one side of the first light guide plate (2) and the second light guide plate (3), and the plurality of LED light strips are divided into at least four light control sections that can be independently lit or turned off in the extension direction along the side.

4. The double-layer light guide plate backlight module for side-lit backlight display with local dimming as described in claim 3, characterized in that, The dot structure on the first light guide plate (2) and the second light guide plate (3) is configured such that when the first light control section of the plurality of LED light strips is lit and the other sections are off, the first display area corresponding to the first light control section in the light-emitting surface of the backlight module is lit; when the second light control section is lit and the other sections are off, the second display area corresponding to the second light control section in the light-emitting surface is lit.

5. The double-layer light guide plate backlight module for side-lit backlight display with local dimming as described in claim 2, characterized in that, The first light guide plate (2) and the second light guide plate (3) may have the same or different thicknesses.

6. The double-layer light guide plate backlight module for side-lit backlight display with local dimming as described in claim 1, characterized in that, The reflective sheet (4) is attached to the bottom surface of the second light guide plate (3), and the back plate (5) supports and fixes the reflective sheet (4), the second light guide plate (3), the first light guide plate (2) and the diaphragm assembly (1).

7. The double-layer light guide plate backlight module for side-lit backlight display with local dimming as described in claim 3, characterized in that, The at least four independently controllable light control sections, in conjunction with the dot structure of the first light guide plate (2) and the second light guide plate (3), enable the display screen to be divided into at least four independent light control zones in the direction parallel to the LED light strip arrangement.

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