A diffuser sheet and its backlight module

Abstract

This utility model belongs to liquid crystal display technology, and particularly relates to a diffuser sheet and its backlight module. A diffuser sheet includes: a substrate layer for maintaining a flat shape and supporting a prism structure layer and an attached matte layer; a prism structure layer located on the front side of the substrate layer, the prism structure layer being formed by UV adhesive curing and multi-blade engraving using at least two different angled tool paths to form a pyramidal prism array, used to change the light propagation path; and a matte layer located on the back side of the substrate layer for light scattering and homogenization.

Description

Technical Field

[0001] This utility model belongs to the field of liquid crystal display technology, and particularly relates to a diffuser sheet and its backlight module. Background Technology

[0002] Traditional diffuser technology primarily achieves light diffusion through physical doping or surface microstructures, but there is a significant contradiction between its optical performance and processing technology. For example, the tool-carving die core process disclosed in CN104626528A, which involves carving wavy grooves on a metal roller surface and imprinting them onto a substrate, can achieve a haze value of 60%-80%, but the single waveform structure restricts the direction of light diffusion, resulting in insufficient positive brightness gain (<1.2 times). Furthermore, CN106154367B proposes filling the microstructured grooves with silica diffusion particles to increase haze to over 85% through a composite refraction effect. However, uneven particle distribution leads to local transmittance fluctuations of ±15%, and the filling process requires precise control of particle concentration (error <0.5wt%), resulting in a mass production yield of less than 70%. This type of technology generally suffers from the defect of single function - the diffuser only undertakes the passive scattering function. In order to compensate for the brightness loss, the backlight module has to be superimposed with a brightness enhancement film (BEF) and a reflective polarizing film (DBEF), which increases the module thickness to 3.2-4.5mm, making it difficult to meet the stringent requirements of automotive displays for thinness (<2.5mm) and high luminous efficiency (>1.8 times gain).

[0003] To address the performance limitations of traditional diffusers, recent research has attempted to integrate diffusion and brightness enhancement functions through composite microstructure design. CN109177134A proposes alternating prism arrays and matte areas on the surface of a PET substrate. The prisms concentrate light to enhance positive brightness, while the matte areas suppress moiré patterns. However, the prism unit height tolerance in this scheme is ±5μm (standard requirement ±2μm), resulting in a brightness uniformity of only 82%-86%. CN207867063U further improves this by using a pit-prism hybrid structure. This structure forms pits by randomly embedding scattering beads within the UV adhesive layer, combining them with a prism array to achieve dual-function integration. However, the random distribution of the scattering beads results in an effective optical control area of ​​less than 40%, and the matching error (>8%) between the pit depth and prism height leads to interfacial light scattering loss. More importantly, existing composite structures rely on multi-process processing (such as CN207867063U, which requires coating a beaded layer before imprinting a prism), increasing production costs by 35%-50% due to process complexity, and the reflection at the interface of the multi-layer structure causes a cumulative loss of 12%-15% in light efficiency.

[0004] The precision of the microstructure processing of diffuser sheets directly affects optical performance, but existing processes struggle to balance high precision with low cost. While the tool-grinding process, exemplified by CN104626528A, can engrave prism structures on the mold core surface using diamond tools (pitch accuracy ±1.5μm), the single-tool, unidirectional scribing mode results in a prism apex angle deviation of ±3°, and the engraving speed is limited (<10m / min), failing to meet the large-scale mass production requirements of automotive display films. Furthermore, existing processes lack compatibility with composite structures—for example, the groove filling process of CN106154367B and the pit imprinting process of CN207867063U are difficult to integrate on the same production line, leaving the functional layer stacking problem unresolved. Therefore, developing an innovative solution that can simultaneously achieve high-precision composite microstructure processing, low-cost mass production, and compatibility with existing roll forming processes is a key path to overcome the performance bottlenecks of automotive backlight modules. Utility Model Content

[0005] The purpose of this invention is to address the above-mentioned shortcomings by providing a diffuser sheet and its backlight module.

[0006] Firstly, a diffusion sheet employs the following technical solution: A diffusion sheet, comprising: The substrate layer is used to maintain the flatness of the shape and to support the prism structure layer and the attached matte layer; The prism structure layer located on the front side of the substrate layer is formed by UV adhesive curing and multi-blade engraving through at least two different angle tool paths to form a pyramidal prism array, which is used to change the propagation path of light. The matte layer located on the back of the substrate layer is used for light scattering and homogenization.

[0007] Furthermore, the apex angle of the cornerstone prism is less than 120°, the distance between two adjacent cornerstone prisms is 10μm~200μm, and the height of the cornerstone prism is 5μm~100μm.

[0008] Furthermore, the prism structure layer is specifically used to form a pyramidal prism array by multi-blade engraving through at least two tool paths with different angles, wherein the angle between the first tool path and the horizontal direction is 35°~55°, the angle between the second tool path and the horizontal direction is 125°~145°, and / or the angle between the first tool path and the first tool path or the second tool path is 0°~60°.

[0009] Furthermore, the surface of the cutting tool used in the multi-blade engraving is engraved with a continuous pyramidal structure or a wavy pyramidal structure, and the vertical cross-section of the pyramidal structure includes one of a convex pyramidal structure and a concave pyramidal structure with an arc.

[0010] Furthermore, the spacing of the tool path is 27μm~33μm, the vibration frequency of the tool is greater than 50μm, and the vibration amount is less than 50% of the height of the corner pyramid prism.

[0011] Furthermore, the substrate layer is made of either PET or PC, and the thickness of the substrate layer is 10μm to 300μm.

[0012] Furthermore, the haze value of the haze layer is 10% to 90%.

[0013] Furthermore, the cornerstone prism array comprises any of the following combinations: Array of conical prisms with curved angles; Array of pyramidal prisms; A periodic array of angular pyramidal prisms with varying curvature; An "S"-shaped pyramidal prism array formed by a nonlinear toolpath.

[0014] Secondly, a backlight module adopts the following technical solution: A backlight module includes the diffuser sheet described above; The backlight module is arranged from top to bottom as follows: a liquid crystal screen assembly, a brightness enhancement film, a diffuser sheet, a light guide plate, and a reflective sheet; the backlight module also includes a light source assembly, which is disposed on one side of the light guide plate. The LCD screen assembly is used to display images; The brightness enhancement film is used to enhance the directionality and brightness of light; The diffuser is used to maintain image uniformity while increasing brightness and eliminating bright spots and dark areas; The light guide plate is used to convert the side-incident light emitted by the light source assembly into a uniform surface light source and to control the light emission angle and distribution. The reflective sheet is used to reflect light that is not absorbed by the light guide plate and the diffuser, thereby reducing light loss; The light source assembly is used to provide an initial light source.

[0015] The beneficial effects of this utility model are: This invention provides a diffuser that integrates the optical functions of traditional multi-layer film stacking within a single-layer film through an integrated composite structure of a substrate layer, a prism structure layer, and a matte layer. This solves the inherent contradiction between optical efficiency and structural simplification in automotive backlight modules. The prism structure layer is formed by a pyramidal prism array using UV adhesive curing and multi-blade engraving. Through the synergistic effect of total internal reflection and refraction of incident light by the prism units, the 15%-30% light efficiency loss caused by passive scattering in traditional diffusers is converted into active light-gathering gain, increasing the forward brightness to 1.3-1.6 times that of traditional diffusers. At the same time, it eliminates the interface reflection loss caused by the physical separation of the brightness enhancement film (BEF) and the diffuser. The matte layer compensates for the excessively strong light-gathering directionality of the prism array through adjustable scattering, improving brightness uniformity to over 90% while maintaining 85%-92% haze. This effectively overcomes the moiré pattern phenomenon caused by the difference in thermal expansion coefficients between the diffuser and the brightness enhancement film in traditional solutions. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the diffuser sheet in the embodiment; Figure 2 This is a schematic diagram of the prism structure layer in the diffuser sheet in the embodiment; Figure 3 This is a schematic diagram of the frosted layer in the diffuser sheet in the embodiment; Figure 4 This is a schematic diagram of the first toolpath in the embodiment; Figure 5 This is a schematic diagram of the second toolpath in the embodiment; Figure 6 This is a schematic diagram of the backlight module in the embodiment; Explanation of reference numerals in the attached figures: 10. Diffuser; 11. Substrate layer; 12. Prism structure layer; 121. Pyramidal prism array; 13. Matte layer; 20. Backlight module; 21. LCD screen assembly; 22. Brightness enhancement film; 23. Light guide plate; 24. Reflective sheet; 25. Light source assembly. Detailed Implementation

[0017] The following detailed description, in conjunction with embodiments, provides a further specific account of the diffuser sheet and its backlight module according to this utility model. For the sake of simplicity, this document cannot exhaustively list all alternative technical features and implementation schemes included in this utility model. Therefore, those skilled in the art should understand that any technical feature and implementation scheme within this embodiment does not limit the scope of protection of this utility model, which includes all alternative technical features and implementation schemes adopted by those skilled in the art without inventive effort. Specifically, any implementation scheme obtained by replacing any technical feature in this utility model or combining any two or more technical features provided by this utility model should be within the scope of protection of this utility model.

[0018] This embodiment provides a diffuser sheet 10, see reference. Figures 1-3 ,include: The substrate layer 11 is used to maintain the flatness of the shape and to support the prism structure layer 12 and the attached matte layer 13. The prism structure layer 12 located on the front of the substrate layer 11 is formed by UV adhesive curing and multi-blade engraving through at least two different angle tool paths to form a pyramidal prism array 121, which is used to change the propagation path of light. The matte layer 13 located on the back of the substrate layer 11 is used for light scattering and homogenization.

[0019] The diffuser 10 provided in this embodiment optimizes the light propagation path while maintaining optical diffusion function, exhibiting significant advantages in optical performance, structural stability, and manufacturing process. The core structure of the diffuser 10 consists of three parts: a substrate layer 11, a prism structure layer 12, and a matte layer 13. Each layer plays a crucial role in light transmission and diffusion, collectively achieving efficient optical gain and homogenization. The main function of the substrate layer 11 is to provide mechanical support, ensuring the diffuser 10 maintains a stable shape during production and application. Its material is typically PET or PC, which has high light transmittance and excellent mechanical properties. This not only ensures the optical transparency of the diffuser 10 but also guarantees its weather resistance and deformation resistance, making it suitable for the long-term operation environment of the backlight module 20. Furthermore, the substrate layer 11 provides a stable adhesion surface for the prism structure layer 12 and the matte layer 13, ensuring the overall structural integrity and durability.

[0020] The prism structure layer 12 is cured with UV adhesive and processed using a multi-blade engraving method to form a pyramidal prism array 121, thereby changing the light propagation path. While diffusers primarily rely on random scattering of microstructures or physical doping to achieve light diffusion, this invention employs a high-precision prism structure design, causing light to undergo a combination of refraction, total internal reflection, and rerefraction after entering the diffuser 10. This effectively improves the forward light transmission efficiency while reducing lateral light loss, thus achieving both diffusion and optical brightening effects. Furthermore, this prism structure is not a single form but is processed using multi-blade engraving with at least two blades at different angles, allowing the peak angle, spacing, and arrangement of the pyramidal prisms to be flexibly adjusted according to different application requirements. The advantages of this structure are: Enhanced brightness: By precisely controlling the angle and spacing of the prism structure, the forward light gain can reach 1.3 to 1.6 times, which significantly improves its optical utilization compared to diffusers.

[0021] Optimized uniformity: Although traditional brightness enhancement films (BEF) can improve brightness, their strong directionality can easily lead to bright spots and dark areas. This prism array design, by adjusting its distribution mode, enables the diffuser 10 to maintain a uniform distribution of light while enhancing brightness, improving brightness uniformity to over 90%.

[0022] Reduced interface light loss: The diffuser 10 of this invention can directly replace the traditional combination scheme of BEF + diffuser 10, which reduces the light reflection loss at the interface of different film layers, improves the light transmission efficiency, and reduces the overall thickness of the backlight module 20 by more than 20%, meeting the requirements of automotive, mobile devices and other applications for thinness and lightness.

[0023] The matte layer 13 is located on the back of the substrate layer 11. Its main function is to further optimize the light diffusion effect, making it more uniform and soft, thereby eliminating potential bright spots or dark areas. This layer achieves different optical characteristics in different application scenarios by reasonably adjusting the haze value (10%~90%). For example, in automotive displays that require high brightness, a lower haze value can be selected to maintain high luminous flux; while in scenarios such as medical displays where light uniformity is extremely important, a higher haze value can be selected to ensure good visual consistency. In addition, the presence of the matte layer 13 can also effectively reduce moiré patterns and enhance the visibility of the display.

[0024] The multi-layered structure design of this diffuser sheet 10 breaks the contradiction between the "passive scattering" of the diffuser sheet and the "unidirectional focusing" of the brightness enhancement film. While maintaining light uniformity, it achieves active brightness enhancement, significantly improving optical efficiency. Simultaneously, the UV adhesive curing + multi-blade engraving processing method employed in this invention ensures high-precision replication of the microstructure. Furthermore, this process boasts high compatibility, adapting to existing roll forming production lines to achieve low-cost, high-efficiency mass production. Therefore, this diffuser sheet 10 not only has broad application prospects in consumer electronics displays such as automotive, laptop, and tablet displays, but also possesses significant market value in high-end fields such as industrial displays and medical imaging.

[0025] In some embodiments, the apex angle of the cornerstone prism is less than 120°, the distance between two adjacent cornerstone prisms is 10μm to 200μm, and the height of the cornerstone prism is 5μm to 100μm.

[0026] In the design of the diffuser 10 of this invention, the setting of the apex angle, spacing, and height of the corner cube prisms is crucial for optimizing optical performance. The apex angle of the corner cube prisms is less than 120°, the spacing between adjacent corner cube prisms is between 10μm and 200μm, and the height is between 5μm and 100μm. The optimization of these parameters directly determines the focusing, diffusion, and brightening effects of light, and achieves breakthrough improvements in optical efficiency, brightness uniformity, and visual comfort.

[0027] The peak angle of a pyramidal prism is less than 120°, a refined optimization based on the principles of optical refraction and total internal reflection. A smaller peak angle allows more light to be refracted and concentrated in the forward direction, improving the brightness gain of the display panel. However, if the peak angle is too small (e.g., less than 60°), while it enhances the light-gathering effect, it may lead to over-focusing of light, resulting in a strong contrast between bright and dark areas, reducing brightness uniformity, and even causing uneven light spots. When the peak angle is close to 120°, the refraction and scattering effects of the prism reach a good balance, allowing light to effectively improve forward brightness while also spreading appropriately in the horizontal direction, thus ensuring better light uniformity. Therefore, optimizing the peak angle within the range of less than 120°, maintaining it between 80° and 110°, is the best solution to ensure both light efficiency and uniformity.

[0028] The spacing between adjacent pyramidal prisms ranges from 10μm to 200μm, and its selection directly affects the light propagation path and the uniformity of the light field. A smaller prism spacing (close to 10μm) results in a higher prism density per unit area, allowing light to refract and scatter multiple times within the microstructure, creating a more uniform diffusion effect and effectively reducing the risk of moiré patterns. However, too small a spacing (e.g., <10μm) may cause severe internal reflection of light on the structural surface, reducing overall luminous efficiency. Conversely, when the prism spacing increases (close to 200μm), the refraction and focusing effect of light is enhanced, improving positive brightness, but excessive spacing can lead to decreased brightness uniformity. Therefore, the optimization of this parameter needs to be adjusted according to the application scenario. For example, in the field of automotive displays where high brightness is required, a spacing of 50μm to 150μm can be selected to optimize luminous efficiency and energy utilization; while in the field of medical displays where uniformity is extremely important, a spacing of 10μm to 50μm can be selected to minimize bright spots and dark areas.

[0029] The height of a pyramidal prism ranges from 5μm to 100μm, a parameter that primarily determines the degree of light refraction and transmission. Higher prisms (>50μm) can more strongly alter the direction of light propagation, concentrating light energy in the forward direction and thus increasing brightness gain. However, excessively high prism structures may cause some light to undergo total internal reflection, increasing energy loss and potentially leading to manufacturing errors in the prism structure. Lower prisms (<20μm), while ensuring light uniformity, may not provide sufficient brightness enhancement. Therefore, the optimal prism height needs to be balanced between 20μm and 80μm to ensure increased brightness without sacrificing uniformity. Furthermore, to further optimize the diffusion effect, a rounded angle design can be introduced at the top of the prism, making light smoother during incident and refraction, reducing localized over-focusing, and improving the visual comfort of the display screen.

[0030] In some embodiments, see Figures 4-5 The prism structure layer 12 is specifically used to form a pyramidal prism array 121 by multi-blade engraving through at least two tool paths with different angles. The angle between the first tool path and the horizontal direction is 35°~55°, the angle between the second tool path and the horizontal direction is 125°~145°, and / or the angle between the first tool path and the first tool path or the second tool path is 0°~60°.

[0031] In embodiments of this invention, the pyramidal prism array 121 of the prism structure layer 12 is formed by multi-blade engraving using at least two tool paths at different angles. The angle between the first tool path and the horizontal direction is set between 35° and 55°, the angle between the second tool path and the horizontal direction is set between 125° and 145°, and / or the angle between the first tool path and either the first or second tool path is 0° to 60°. Compared to traditional single-blade engraving or imprinting methods, this tool engraving method provides higher processing precision, more stable optical performance, and more flexible optical design space, enabling the diffuser 10 to improve brightness while ensuring display uniformity and visual comfort.

[0032] This toolpath allows the pyramidal prism array 121 to form a more precise geometric structure. The optical properties of a pyramidal prism mainly depend on its peak angle, prism height, and array spacing, and these parameters are easily affected by the toolpath angle during processing. In traditional single-tool engraving, the fixed toolpath limits the prism's processing accuracy, resulting in a large deviation in the peak angle (typically ±5°), thus affecting the refraction direction and focusing effect of light. This invention employs multi-tool engraving, using at least two toolpaths with different angles to interleave the engraving, making the peak angle of each pyramidal prism more stable, with the error controlled within ±1°, thereby ensuring uniform light distribution and directional adjustment.

[0033] Precise control of the tool path angle (35°~55° for the first cut, 125°~145° for the second cut) can better optimize the propagation of light and achieve a highly efficient optical brightening effect. In the diffuser 10, the main function of the prism structure is to refract, reflect, and converge light, and different tool angles affect the direction of light entry, propagation, and exit. When the angle between the first tool path and the horizontal direction is controlled between 35° and 55°, the incident light can be partially refracted and guided in the positive direction under the action of the prism structure. When the angle of the second tool path is set between 125° and 145°, the light will undergo further total internal reflection and refraction, making the final outgoing light more concentrated in the positive direction, while also taking into account the lateral diffusion capability. Experimental data shows that this specific tool angle setting can increase the positive brightness of the diffuser 10 by 1.3 to 1.6 times. Compared with the traditional single-tool engraving solution, its optical efficiency is improved by 20% to 30%, and the brightness uniformity is improved to over 90%.

[0034] In the traditional BEF (Brightness Enhancer Film) + Diffuser 10 combination scheme, since the BEF mainly relies on a unidirectional prism structure for light collection, the reflection and scattering of light between interfaces leads to energy loss. Furthermore, due to the large number of optical film layers, periodic interference fringes (moiré patterns) are easily formed. However, the diffuser 10 of this invention, through a pyramidal prism array 121 formed by a knife path, not only integrates brightening and diffusion functions within a single film layer, reducing interface losses, but also reduces coherent interference in specific directions through multi-angle light adjustment, thereby effectively eliminating moiré patterns and resulting in a more stable and clearer display.

[0035] The tool engraving technology achieves high-precision machining through UV adhesive curing and precision engraving, and is compatible with existing roll forming production lines for efficient mass production. Compared to traditional single-tool engraving or embossing processes, this method can improve the machining accuracy per unit area at the same production cycle and allows for more complex microstructure designs (such as curved pyramids, nonlinear "S"-shaped prism paths, etc.), greatly expanding the application range of the diffuser 10. Experiments show that the diffuser 10 produced by this method exhibits excellent optical performance in automotive displays, medical imaging, industrial inspection, and high-end electronic displays, and is particularly suitable for the requirements of high brightness, high uniformity, and thin and light backlight modules 20.

[0036] In some embodiments, the surface of the cutting tool used in multi-blade engraving is engraved with a continuous pyramidal structure or a wavy pyramidal structure, and the vertical cross section of the pyramidal structure includes one of a convex pyramidal structure and a concave pyramidal structure with an arc.

[0037] The multi-blade engraving process utilizes a pyramidal structure inherent in the blade surface, with its vertical cross-section being either a convex pyramidal structure or a concave, curved pyramidal structure. This innovative engraving method enables the prism structure layer 12 of the diffuser 10 to possess more complex optical control capabilities, thereby improving optical gain and brightness uniformity while reducing light loss and moiré effects.

[0038] The convex pyramid structure is primarily used to enhance the directional control of light and improve forward brightness. Traditional prism structures typically employ a standard triangular prism array, whose optical properties rely on refraction and total internal reflection. However, due to limitations in engraving precision, a single prism shape often results in limited optical efficiency. This invention directly engraves a convex pyramid on the tool surface, causing light to refract and focus multiple times within the prism structure, thereby increasing the transmission ratio of forward light. Furthermore, because the prism structure is manufactured using a multi-blade engraving process, its peak angle and array spacing can be precisely controlled, making the incident and refraction angles of light more stable, thus improving display uniformity and effectively reducing local brightness fluctuations.

[0039] On the other hand, the introduction of the concave, curved pyramidal structure primarily aims to optimize light uniformity, thereby improving brightness distribution and visual comfort. In traditional optical diffusion technology, uniformity often relies on the random scattering characteristics of microstructures, but this approach can easily lead to transmittance loss and make it difficult to control the directionality of light. This invention, through a multi-blade engraving process combined with a curved pyramidal structure, allows light to undergo a more controllable scattering process within the diffuser 10. The smooth structure of the concave, curved pyramidal structure reduces sharp refraction of light, making the emitted light more uniform, thus effectively reducing the brightness difference between high-brightness and low-brightness areas. Furthermore, the nonlinear refractive characteristics of the curved pyramidal structure can reduce moiré patterns caused by the regular arrangement of the structure, resulting in a more stable and clearer image display.

[0040] In practical applications, convex pyramidal structures and concave curved pyramidal structures can be used separately or in combination in different backlight module 20 designs. For example, in automotive displays, convex pyramidal structures can be used to enhance forward brightness and improve daytime visibility, while in medical imaging displays, curved pyramidal structures can be selected to optimize brightness uniformity and reduce eye strain. Furthermore, convex pyramids and curved pyramidal structures can be arranged periodically on a single diffuser 10, alternating between them, to achieve a balance between optical gain and optical uniformity.

[0041] In some embodiments, the tool path spacing is 27μm~33μm, the tool vibration frequency is greater than 50μm, and the vibration amount is less than 50% of the height of the corner pyramid prism.

[0042] In some embodiments of this invention, the optical performance and processing stability of the diffuser 10 are further optimized through precise control of the tool path spacing, tool vibration frequency, and vibration magnitude. This optimization not only ensures the processing accuracy of the prism structure but also significantly improves the brightness gain and uniformity of the diffuser 10, while reducing interface light loss and increasing production efficiency.

[0043] The toolpath spacing is set between 27μm and 33μm, a parameter that directly affects the arrangement density and light control effect of the pyramidal prism array 121. In microstructure optical design, a smaller spacing (close to 27μm) means an increase in the number of prism units per unit area, allowing light to undergo more refraction and scattering during propagation, thereby improving brightness uniformity and reducing the formation of local bright spots. However, if the spacing is too small (<27μm), excessive internal reflection of light between prism units may occur, reducing forward transmittance and affecting overall light efficiency. On the other hand, a larger spacing (close to 33μm) can enhance the directional focusing effect of light, increase forward brightness gain, and make the light utilization rate of the backlight module 20 higher. However, if the spacing is too large (>33μm), it may exacerbate bright spot phenomena and affect display uniformity. Therefore, the optimal choice between 27μm and 33μm is the best solution to achieve a balance between brightness gain and uniformity.

[0044] The vibration frequency of the cutting tool is greater than 50 μm, primarily to optimize the microscopic consistency of the prism structure and prevent the accumulation of machining errors caused by unidirectional cutting. Traditional single-tool fixed-path engraving methods, when machining at the micrometer level, are prone to machining errors in the prism's apex structure (such as apex angle offset, uneven prism height, etc.) due to the accumulation of localized material stress, thus affecting optical performance. This invention introduces high-frequency vibration (>50 μm) during the engraving process, allowing the cutting tool to engrave with micro-amplitude oscillations while cutting along the main path, thereby reducing the impact of machining stress on the prism's shape. This method enables the prism structure to maintain high consistency at the nanometer level, avoiding the accumulation of errors caused by tool wear or material deformation in traditional processes. Furthermore, this vibration parameter also enhances the surface flatness of the microstructure, making the refraction of light on the prism array more uniform, further improving display quality.

[0045] Furthermore, the vibration amplitude is set to be less than 50% of the height of the pyramidal prism. This parameter provides further fine control over vibration machining to ensure the morphological integrity and stability of the prism unit. While tool vibration enhances machining accuracy, excessive amplitude can cause the prism peak's shape to deviate from the design value, or even lead to microstructural collapse or deformation, affecting optical performance. Therefore, this invention strictly controls the vibration amplitude, ensuring it does not exceed half (50%) of the prism height, to ensure the structural stability of the pyramidal prism while improving machining accuracy. For example, if the height of the pyramidal prism is 40 μm, the vibration amplitude is limited to <20 μm, thereby avoiding microstructural damage caused by excessive vibration.

[0046] This invention significantly improves the optical brightness, light uniformity, and production stability of the diffuser 10 by optimizing the control of tool path spacing (27μm~33μm), vibration frequency (>50μm), and vibration amount (<50% of prism height). This process improvement not only increases forward brightness but also reduces local bright spots. Therefore, this technical solution is not only suitable for high-end display applications such as automotive displays, medical imaging, and industrial inspection, but also has broad application potential in backlight modules 20 of consumer electronics products (such as smartphones, tablets, and laptops), providing a highly competitive solution for next-generation high-efficiency and thin-and-light display technology.

[0047] In some embodiments, the substrate layer 11 is made of either PET or PC, and the thickness of the substrate layer 11 is 10μm to 300μm.

[0048] In some embodiments, the haze value of the matte layer 13 is 10% to 90%.

[0049] In some embodiments, the cornerstone prism array 121 includes any combination of the following: 121 angular cone prism array with arcuate corners; 121-pole pyramidal prism array; A periodic array of angular pyramidal prisms with varying curvature; An "S"-shaped pyramidal prism array 121 formed by a nonlinear toolpath.

[0050] In embodiments of this invention, the structure of the cornerstone prism array 121 can be a curved cornerstone prism array 121, a cornerstone prism array 121, a periodic array of curved cornerstone prisms and cornerstone prisms spaced apart, or an "S"-shaped cornerstone prism array 121 formed by a nonlinear tool path. This optimized combination of parameters and structures enables the diffuser 10 to possess excellent optical uniformity, brightness gain, and visual comfort, while also meeting the needs of different application scenarios.

[0051] The various structural combinations of the pyramidal prism array 121 provide more flexible optical control capabilities, enabling the diffuser 10 to optimize the light propagation path while meeting the application requirements of different backlight modules 20: 121 Curved Corner Pyramid Prism Array: This structure reduces severe light refraction at the pyramid by introducing rounded corners (curved angles) at the prism peaks, avoiding over-focusing and thus improving optical uniformity and reducing visual fatigue. It is suitable for applications requiring extremely high color fidelity and brightness uniformity, such as high-end medical imaging displays and professional photographic monitors.

[0052] Pyramidal prism array 121: This is a classic high-brightness gain solution. It uses a standard pyramidal prism structure to concentrate light in the forward direction after precise refraction and reflection, achieving maximum brightness enhancement. It is suitable for high-brightness applications such as smartphones, laptops, and automotive displays. Experiments show that this structure can increase forward brightness by 1.4 to 1.6 times, and improve light energy utilization by 20% to 30% compared to diffusers.

[0053] A periodic array of curved pyramidal prisms: This structure combines the uniformity of curved pyramids with the high brightness gain of standard pyramids. Through periodic spacing, it achieves both high brightness and optimized uniformity, reducing localized bright spots. It is suitable for high-end consumer electronics, automotive displays, professional monitors, and other applications requiring a balance between brightness and uniformity.

[0054] The "S"-shaped pyramidal prism array 121 formed by a non-linear toolpath: This structure carves prisms using a non-linear toolpath, arranging the pyramidal array in an "S" shape, thereby altering the light propagation pattern and enabling the diffuser 10 to exhibit superior light uniformity across multiple angle ranges. This solution is particularly suitable for large-size displays, HUDs (head-up displays), and AR / VR displays, effectively reducing brightness attenuation at specific angles, widening the viewing angle, eliminating moiré patterns, and improving visual comfort.

[0055] This invention, through the diversified design of the pyramidal prism array 121 structure, enables the diffuser 10 to achieve industry-leading levels in optical brightness enhancement, light uniformity, visual comfort, and adaptability to various applications. Furthermore, these structures can be mass-produced using a high-precision multi-blade engraving process combined with UV adhesive curing. Compared to traditional molding or doping diffusion technologies, this method not only ensures high-precision replication of the microstructure but also reduces production costs, giving it a stronger market competitiveness. Therefore, this technical solution provides a brand-new solution for next-generation high-performance backlight modules 20 and thinner display technologies, meeting the technological needs of the future high-end display industry.

[0056] This embodiment also includes a backlight module 20, see reference. Figure 6 This includes the aforementioned diffuser sheet 10; The backlight module is arranged from top to bottom as follows: LCD screen assembly 21, brightness enhancement film, diffuser sheet 10, light guide plate 23 and reflective sheet 24; the backlight module also includes a light source assembly 25, which is disposed on one side of the light guide plate 23. LCD panel assembly 21 is used to display images; Brightness enhancement film 22 is used to enhance the directionality and brightness of light; The diffuser 10 is used to maintain image uniformity while increasing brightness and eliminating bright spots and dark areas; The light guide plate 23 is used to convert the side-incident light emitted by the light source assembly 25 into a uniform surface light source and to control the light emission angle and distribution. The reflector 24 is used to reflect light that is not absorbed by the light guide plate 23 and the diffuser 10, thereby reducing light loss; The light source assembly 25 is used to provide an initial light source.

[0057] This invention provides a high-efficiency backlight module 20. Its core innovation lies in employing an optimized diffuser 10, combined with a brightness enhancement film (BEF), a light guide plate 23, a reflective sheet 24, and a light source assembly 25, achieving comprehensive optimization of optical gain, brightness uniformity, and optical utilization. The stacked structure of this backlight module 20, through precise control of the light propagation path, significantly improves brightness, energy utilization, light uniformity, and visual comfort compared to existing technologies.

[0058] The backlight module 20 in this embodiment includes, from bottom to top: a reflective sheet 24, a light guide plate 23, a diffuser sheet 10, a brightness enhancement film 22, and a liquid crystal display assembly 21. The various structural layers work together to achieve optimal control of light as it passes through the backlight system. Light source component 25: The core light source of the backlight module 20, which usually adopts a side-lit LED, and the emitted light first enters the light guide plate 23. In high-end applications (such as automotive HUDs, industrial inspection equipment, etc.), lasers or Mini-LEDs can also be used as light sources to further improve optical performance.

[0059] Using a pyramidal prism array 121, a high-precision microstructure is formed through a multi-blade engraving process, which can enhance the directionality of light while maintaining good optical uniformity.

[0060] The traditional combination of BEF and diffuser 10 results in light loss between layers (typically 15%~20%). This invention integrates brightening and diffusion functions through a single-layer structure, reducing light loss and improving the optical utilization of the system.

[0061] With adjustable haze (10%~90%) in the matte layer 13, the diffuser 10 can adapt to different application scenarios, ensuring uniformity of over 90% and significantly reducing bright spots and dark areas.

[0062] By combining a nonlinear “S”-shaped pyramidal prism array 121, the angular distribution of light is optimized, enabling the display to maintain stable brightness at different viewing angles, making it suitable for large-size LCD panels and automotive HUDs.

[0063] In traditional backlight modules 20, the layering of the BEF and diffuser 10 can cause interface reflection, resulting in moiré patterns and light loss. This invention optimizes the internal structure of the diffuser 10 to reduce interlayer light reflection, improve overall optical efficiency, and enhance the energy utilization of the backlight module 20.

[0064] By using an array of curved and standard corner prisms spaced apart, the risk of moiré patterns is further reduced, making the image more stable.

[0065] The traditional BEF+diffuser 10 solution, due to its numerous layers, increases the overall thickness of the backlight module 20 to 3.5~4.5mm, making it difficult to meet the requirements for thinner and lighter designs. This invention, by optimizing the microstructure design of the diffuser 10, can directly replace the traditional combination of brightness enhancement film and diffuser 10, reducing the thickness of the backlight module 20 by more than 20%, offering significant advantages in mobile devices (such as tablets and laptops) and automotive displays.

[0066] The diffuser sheet 10 of this invention can be adapted to the Mini-LED backlight module 20, making the brightness distribution between its light-emitting units more uniform, thereby improving HDR (High Dynamic Range) performance. It is suitable for high-end display applications such as medical imaging, industrial monitoring, and aerospace instruments, ensuring high brightness while optimizing visual comfort.

[0067] The backlight module 20 of this invention achieves significant progress in optical gain, brightness uniformity, light loss control, and manufacturing feasibility through its innovative diffuser sheet 10 microstructure design. Furthermore, the manufacturing process of this backlight module 20 has been optimized for large-scale mass production, is compatible with continuous roll forming, and reduces manufacturing costs compared to traditional solutions, giving it a strong competitive edge in the market. This technical solution can not only be widely applied in the consumer electronics field but also provides strong technical support for the future development of high-end display technologies.

[0068] For those skilled in the art, other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, but obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this invention.

Claims

1. A diffusion sheet, characterized in that, include: The substrate layer is used to maintain the flatness of the shape and to support the prism structure layer and the attached matte layer; The prism structure layer located on the front side of the substrate layer is formed by UV adhesive curing and multi-blade engraving through at least two different angle tool paths to form a pyramidal prism array, which is used to change the propagation path of light. The matte layer located on the back of the substrate layer is used for light scattering and homogenization. Wherein, the apex angle of the cornerstone prism is less than 120°, the distance between two adjacent cornerstone prisms is 10μm~200μm, and the height of the cornerstone prism is 5μm~100μm; The prism structure layer is specifically used to form a pyramidal prism array by multi-blade engraving through at least two tool paths with different angles. The angle between the first tool path and the horizontal direction is 35°~55°, the angle between the second tool path and the horizontal direction is 125°~145°, and / or the angle between the first tool path and the first tool path or the second tool path is 0°~60°.

2. The diffusion sheet according to claim 1, characterized in that, The cutting tool used in the multi-blade carving has a continuous pyramidal structure or a wavy pyramidal structure carved on its surface. The vertical cross-section of the pyramidal structure includes either a convex pyramidal structure or a concave pyramidal structure with an arc.

3. The diffusion sheet according to claim 1, characterized in that, The spacing of the tool path is 27μm~33μm, the vibration frequency of the tool is greater than 50μm, and the vibration amount is less than 50% of the height of the corner pyramid prism.

4. The diffusion sheet according to claim 1, characterized in that, The substrate layer is made of either PET or PC, and its thickness is 10μm to 300μm.

5. A diffusion sheet according to claim 1, characterized in that, The haze value of the haze layer is 10%~90%.

6. A diffusion sheet according to claim 1, characterized in that, The pyramidal prism array includes any of the following combinations: Array of conical prisms with curved angles; Array of pyramidal prisms; A periodic array of angular pyramidal prisms with varying curvature; An "S"-shaped pyramidal prism array formed by a nonlinear toolpath.

7. A backlight module, characterized in that, Includes the diffusion sheet as described in any one of claims 1 to 6; The backlight module is arranged from top to bottom as follows: a liquid crystal screen assembly, a brightness enhancement film, a diffuser sheet, a light guide plate, and a reflective sheet; the backlight module also includes a light source assembly, which is disposed on one side of the light guide plate. The LCD screen assembly is used to display images; The brightness enhancement film is used to enhance the directionality and brightness of light; The diffuser is used to maintain image uniformity while increasing brightness and eliminating bright spots and dark areas; The light guide plate is used to convert the side-incident light emitted by the light source assembly into a uniform surface light source and to control the light emission angle and distribution. The reflective sheet is used to reflect light that is not absorbed by the light guide plate and the diffuser, thereby reducing light loss; The light source assembly is used to provide an initial light source.

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