Brightness enhancement film and backlight module

Abstract

According to the brightness enhancement film and the backlight module, a prism layer is composed of a high-haze atomization prism area and a common prism area, and the light distribution of the edge is improved by controlling the specific position, haze and other parameters of the prism layer, so that the light is more uniform; a roller type prism mold and a sand blasting treatment technology are adopted for manufacturing, a microstructure is formed on the mold through sand blasting treatment, and the shape and the pattern are copied to a prism layer of the brightness enhancement film through the mold by utilizing a transfer printing and photocuring technology, so that the performance and the quality of the brightness enhancement film are ensured, and meanwhile, efficient and accurate manufacturing of the brightness enhancement film is realized; according to the brightness enhancement film, the light uniformity of the display device can be improved, and the shielding performance, the firefly resisting effect and the sky side bright line eliminating capacity of a product are effectively enhanced.

Description

Technical Field

[0001] The present application relates to the technical field of optical films, and particularly to a brightness enhancement film and a backlight module. Background Art

[0002] Today, with the rapid development of display technology, as a key optical material for enhancing the brightness and uniformity of liquid crystal displays, brightness enhancement films have been widely used in various display devices. Existing brightness enhancement films and related optical film materials, while pursuing high brightness and uniformity, often neglect the problem of light leakage on the light source side, which to a certain extent affects the overall display effect of the display device. Specifically, traditional brightness enhancement film designs mainly focus on concentrating the light scattered by the light source towards the front through a micro-prism structure to enhance the overall brightness and uniformity, and diffusion films are used to control the light distribution to achieve a more uniform display effect. However, this design method does not fully consider the problem of light leakage on the light source side while enhancing brightness and uniformity, resulting in uneven bright and dark areas on the light incident side in actual applications, namely the so-called "lamp mouth firefly phenomenon".

[0003] To address this problem, although some solutions have been adopted in the prior art, such as using light-shielding tapes, diffusion film border screen printing, and small reflectors at the lamp mouth to reduce the adverse effects of the lamp mouth firefly phenomenon and tail bright lines. However, these solutions not only increase the complexity and manufacturing cost of the display device, but also are still difficult to achieve an ideal display effect in some specific scenarios. Therefore, it is necessary to effectively solve the problem of light leakage on the light source side by improving the structure and materials of optical films, while maintaining or even enhancing the brightness and uniformity of the display device. Related technical solutions can comprehensively consider multiple factors such as light leakage on the light source side, brightness enhancement, and uniformity control, so as to achieve a more efficient, economical, and high-quality display effect. Summary of the Utility Model

[0004] The purpose of the present application is to provide a brightness enhancement film, which can make the light at the light incident part of the display device more uniform and can improve the shielding property, anti-firefly, and anti-sky side bright line capabilities of the product. The above technical effects of the present application are achieved through the following technical solutions. The brightness enhancement film of the present application includes a prism layer provided on the light exit surface, and the prism layer includes a prism array;

[0005] In the direction perpendicular and / or horizontal to the prism arrangement direction in the prism array, the prism layer includes a first diffused prism area, a normal prism area, and a second diffused prism area arranged in sequence, and the prism surfaces in the first diffused prism area and the second diffused prism area have surface microstructures;

[0006] The haze of the first diffused prism area and the second diffused prism area is greater than the haze of the normal prism area.

[0007] In one embodiment, the spacing between adjacent prisms in the prism array is equal or varies periodically.

[0008] In one embodiment, the refractive index of the prism array material is 1.53 to 1.69.

[0009] In one embodiment, it further includes a substrate layer, and the thickness of the substrate layer is 25 to 300 μm.

[0010] In one embodiment, it further includes a back coating, the back coating is disposed on the surface of the substrate layer opposite to the prism layer, and the haze of the back coating is in the range of 2% to 20%.

[0011] In one embodiment, the haze of the first atomized prism region and the second atomized prism region is 90% to 100%.

[0012] In one embodiment, the haze in the first atomized prism region and the second atomized prism region is formed by a diffusion microstructure, and the density of the diffusion microstructure gradually decreases in the direction from the edge to the center.

[0013] To simplify the manufacturing of the brightness enhancement film defined in the present application, the present application also provides a method for manufacturing a brightness enhancement film, including:

[0014] Manufacturing a prism mold according to the shape of the prisms in the brightness enhancement film;

[0015] Performing sandblasting on the regions corresponding to the first atomized prism region and the second atomized prism region in the prism layer of the prism mold to obtain an atomized prism mold with an atomized region;

[0016] Using the sandblasted prism mold to transfer and photocure the material for making the prism layer, and simultaneously forming a prism layer including a first atomized prism region, a normal prism region, and a second atomized prism region.

[0017] In one embodiment, the prism mold is of a roller type.

[0018] In addition, the present application also provides a backlight module, including the aforementioned brightness enhancement film, a light guide plate, and a light source.

[0019] Compared with the prior art, the present application has the following beneficial effects: The brightness enhancement film of the present application improves the light uniformity, product shielding property, anti-firefly and anti-side bright line capabilities by setting regions with higher haze in the prism layer; in terms of the manufacturing method, the present application provides a simple and efficient method for manufacturing a brightness enhancement film, including manufacturing a prism mold and performing sandblasting on specific regions of the mold to obtain an atomized prism mold. The method of the present application not only simplifies the production process but also can be adjusted as needed to ensure the high-quality production of the brightness enhancement film. Description of the Drawings

[0020] Figure 1 is a schematic structural diagram of a brightness enhancement film in an embodiment of the present application;

[0021] Figure 2 is Figure 1 a top - view structural diagram of the brightness enhancement film in

[0022] Figure 3 a top - view structural diagram of the brightness enhancement film in another embodiment of the present application;

[0023] Figure 4 is a schematic structural diagram of a prism mold in the manufacturing method of the brightness enhancement film of the present application;

[0024] Figure 5 is a schematic structural diagram of a backlight module applying the brightness enhancement film of the present application.

[0025] Explanation of reference numerals: 100, prism layer; 110, first atomized prism area; 120, ordinary prism area; 130, second atomized prism area; 200, substrate layer; 300, back coating; 400, prism mold; 500, light guide plate; 600, light source. Detailed Description of the Embodiment

[0026] To make the above - mentioned objects, features, and advantages of the present application more obvious and understandable, the following will, with reference to the accompanying drawings, give a detailed description of the specific embodiments of the present application. It can be understood that the specific embodiments described herein are only for explaining the present application and not for limiting the present application. Additionally, it should be noted that for the convenience of description, only parts related to the present application rather than all structures are shown in the accompanying drawings. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.

[0027] The terms "including" and "having" and any variations thereof in the present application are intended to cover non - exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products, or devices.

[0028] Referring to "embodiments" herein means that specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0029] As an indispensable core component of the display panel, the improvement of the performance of the backlight module is directly related to the image quality performance of the display device. Especially under the requirements of pursuing delicate image quality, vivid colors, and visual comfort, how to effectively optimize the backlight module, improve the light utilization efficiency, and reduce unnecessary visual interference has become the focus of the industry. As one of the key components in the backlight module, the brightness enhancement film directly affects the overall display effect of the display device. Although traditional brightness enhancement films can improve the brightness to a certain extent, they still have deficiencies in terms of light uniformity, light shielding, anti-firefly, and anti-sidelight leakage. To solve these problems, this application proposes a new design scheme for the brightness enhancement film, aiming to achieve better light shielding, anti-firefly, and anti-sidelight leakage capabilities through structural and material selection, while also reducing the manufacturing difficulty and process stability. Please refer to Figures 1 to 3 As shown, in the brightness enhancement film of a preferred embodiment of this application, the brightness enhancement film includes a prism layer 100 disposed on the light-emitting surface. The prism layer 100 includes a prism array, and the prism array can effectively refract and focus the light from the light homogenizing plate, so that the light can be emitted forward more concentratedly, thereby enhancing the brightness of the display device. The light is more orderly during the propagation process, reducing the scattering and loss of light, and thus improving the light utilization efficiency.

[0030] In the direction perpendicular and / or horizontal to the prism arrangement direction in the prism array, the prism layer 100 includes a first diffused prism area 110, a normal prism area 120, and a second diffused prism area 130 arranged in sequence. The prism surfaces in the first diffused prism area 110 and the second diffused prism area 130 have surface microstructures, which can be formed by transfer printing with a mold having a microstructured surface. The surface microstructures cause the prisms to generate haze. The haze of the first diffused prism area 110 and the second diffused prism area 130 is greater than that of the normal prism area 120, which means they can absorb and scatter more light. In a specific direction of the prism array, by reasonably setting these two diffused prism areas, the light can become more uniform during the propagation process, avoiding bright spots and dark areas caused by overly concentrated light. Specifically, through the high-haze design in the lamp area and the tail area, the blurriness of the images in these two areas is effectively improved, and further significantly reduces the "firefly" phenomenon at the edge of the light-emitting surface, making the uniformity of the overall image reach a new level. Due to the adoption of the high-haze design, the need for relying on additional light-shielding tapes or black frame printing means is reduced, simplifying the production process and reducing the material cost.

[0031] The haze of the first atomized prism region 110 and the second atomized prism region 130 is greater than that of the ordinary prism region 120. These two atomized prism regions can also effectively block the light from the edge of the backlight module, reducing the occurrence of lamp socket firefly phenomenon and side bright line, and further improving the visual comfort of the display device. By adjusting parameters such as the haze, size, and position of the first atomized prism region 110 and the second atomized prism region 130, the performance of the brightness enhancement film can be optimized according to specific application requirements. For example, in scenarios where higher brightness is required, the area of the atomized prism region can be appropriately reduced or its haze can be decreased, while in scenarios where better shielding is needed, the area of the atomized prism region can be increased or its haze can be increased. This flexibility enables the brightness enhancement film of the present application to meet the needs of different display devices and has a wide range of application prospects. The design of the high-haze shielding region further reduces the ineffective area around the screen, making the effective display area of the screen larger and providing users with a broader visual experience. By reducing the ineffective area and enhancing the picture uniformity, the design of the high-haze shielding region achieves a nearly borderless display effect.

[0032] In a further technical solution, in order to further control the light uniformity of the backlight module, the present application further defines the size and distribution of the prisms. The spacing between adjacent prisms in the prism array is equal or periodically changes. When there is no obvious difference in the light intensity in the light homogenizing plate, the same prism spacing is adopted. In some cases, there may be some differences in the light intensity in different regions of the light homogenizing plate. At this time, it can be adjusted by adjusting the size of the prisms. When adjusting the size of the prisms, the spacing between the prisms will change, and this change usually adopts a periodic change method. Specifically, prisms with larger size and spacing are selected in the region with lower light intensity to balance the light intensity difference through the adjustment of the prism size.

[0033] In order to optimize the light adjustment effect of the material, the present application further studies the refractive index of the prism array material and finds that in the film layer structure of the present application, when the refractive index of the prism array material is 1.53 - 1.69, better technical effects can be achieved. Within this refractive index range, the prisms can effectively refract and focus the light. Due to the specific selection of the refractive index, the light will be accurately guided when passing through the prism layer 100, thereby increasing the proportion of light emitted forward and effectively enhancing the brightness of the display device. The materials selected within this refractive index range usually have good optical stability and reliability.

[0034] In the brightening film structure, the selection and thickness design of the substrate layer 200 play a crucial role in the performance of the overall material. Based on the foregoing technical solutions of this application, the substrate layer 200 is further provided. The material of the substrate layer 200 is selected from one or more of the following materials: PET, PC, or PMMA. The thickness of the substrate layer 200 is 25 to 300 μm. By using the above materials and selecting an appropriate thickness range, sufficient mechanical strength is ensured, while also taking into account the lightweight and cost-effectiveness of the material, and it can be widely applied in various fields.

[0035] On the basis of the above content, a back coating 300 is further provided. The back coating 300 is disposed on the surface of the substrate layer 200 opposite to the prism layer 100. The haze of the back coating 300 is in the range of 2% to 20%. Through the selection of the haze, the optical performance can be further regulated, effectively controlling the propagation and distribution of light, achieving uniform distribution and gentle transition of light, further adjusting the light passing through the prism layer 100, improving the brightness and clarity of the display effect, thereby enhancing the optical performance of the backlight module. The design and optimization of the back coating 300 cooperate with other parts of the backlight module (such as the light guide plate 500, the reflector, etc.) to jointly enhance the overall performance of the backlight module.

[0036] In this application, the haze design of the prism layer 100 is crucial for the distribution and regulation of light. The haze of the first atomized prism area 110 and the second atomized prism area 130 is 90% to 100%. Due to the high haze of 90% to 100%, the first atomized prism area 110 and the second atomized prism area 130 can strongly scatter light. This scattering effect makes the light more evenly distributed throughout the backlight module, avoiding local over-bright or over-dark situations, and improving the uniformity of the display screen. The prism area with high haze can soften the light and reduce the firefly phenomenon at the edge of the light-emitting surface. The design of the prism area with high haze can also be customized according to the specific requirements of customers. The parameters such as the position, size, and haze of the atomized prism area can be adjusted according to the requirements of customers to meet personalized needs.

[0037] In a further technical solution, the haze in the first atomizing prism area 110 and the second atomizing prism area 130 is formed by diffusion microstructures. The density of the diffusion microstructures gradually decreases from the edge to the center. The design of the diffusion microstructures enables light to be scattered within the prism layer 100. The gradual decrease in the density of the microstructures from the edge to the center means that the scattering of light is stronger at the edge of the prism layer 100 and relatively weaker in the central region, which helps to achieve uniform distribution of light across the entire prism layer 100. This is very effective in improving the edge vignetting phenomenon of the display screen, enabling the display screen to maintain a high brightness even at the edge part. Although the diffusion microstructures will cause a certain amount of light loss, since the microstructure density is lower in the central region, the degree of light loss is relatively reduced, meaning that more light can penetrate the prism layer 100, resulting in significant improvements in the light emission uniformity, edge brightness, and light efficiency of the backlight module.

[0038] In a further technical solution, the part of the substrate layer 200 corresponding to the positions of the first atomizing prism area 110 and the second atomizing prism area 130 includes a light diffusion unit. The light diffusion unit can further enhance the diffusion effect of light, enabling light to be more evenly distributed within the prism layer 100. Due to the presence of the light diffusion unit, especially at the positions corresponding to the edges of the first atomizing prism area 110 and the second atomizing prism area 130, the diffusion of light in the edge region is more significant, which helps to improve the brightness of the backlight module edge and reduce the edge vignetting phenomenon, enabling the display screen to maintain a high brightness even at the edge part. The light diffusion unit can be selected as a pattern or particles. Specifically, when the pattern is used as the light diffusion unit, it is locally roughened into a circular or dot shape through rough surface treatment. The light scattering pattern is formed to have a small diameter (for example, a diameter of 50 μm or less) that is hardly noticeable to the naked eye when viewed from the light exit surface side. When adding particles as the light diffusion unit, the substrate layer 200 is made of a general light guide plastic such as polymethyl methacrylate or polycarbonate, etc. Polymethyl methacrylate or melamine resin spherical particles with a particle size of 5 μm - 30 μm are mixed in the substrate layer 200. Through this setting method, the brightness uniformity is further optimized.

[0039] To produce a prism brightness enhancement film, a prism mold 400 is generally used for production. The main steps include the design and production of the prism mold 400, material selection and preparation, production of the prism layer 100, and curing and hardening. Specifically, it includes: according to the required prism shape and size, three-dimensional modeling is carried out to generate a design drawing that details parameters such as the shape of the prism's edges and corners, the number of edges and corners, and the size. The corresponding mold is processed. A suitable material is selected for making the prism layer 100. According to the optical performance requirements of the product, parameters such as specific transparency and refractive index are selected. The prism mold 400 is used to transfer the material for making the prism layer 100, usually achieved through roller transfer technology, so that the material can form a specific prism structure according to the shape of the mold. The transferred prism layer 100 is subjected to photocuring treatment. Through high-energy ultraviolet light irradiation, the fine structures in the prism layer 100 are hardened to ensure the stability and optical performance of the prism layer 100. The surface treatment and quality inspection of the made prism layer 100 are carried out.

[0040] To match the structure of the brightness enhancement film defined in this application, the manufacturing method of the corresponding brightness enhancement film is optimized. The main steps of improvement include:

[0041] The prism mold 400 is made according to the shape of the prism in the brightness enhancement film;

[0042] The areas of the prism mold 400 corresponding to the first atomized prism area 110 and the second atomized prism area 130 in the prism layer 100 are sandblasted to obtain an atomized prism mold 400 with corresponding atomized areas; by sandblasting specific areas of the prism mold 400, atomized prism areas (i.e., the first atomized prism area 110 and the second atomized prism area 130) are formed. The sandblasting process forms microstructures on the mold surface for forming the atomized areas. These microstructures will form an atomized effect on the corresponding prism surface during the transfer process. The relevant functions of these areas have been discussed in detail before, and it can make the light more evenly distributed within the prism layer 100.

[0043] The sandblasted prism mold 400 is used to transfer and photocure the material for making the prism layer 100, and at the same time, a prism layer 100 including the first atomized prism area 110, the ordinary prism area 120, and the second atomized prism area 130 is formed. The atomized areas are formed by imprinting with a mold having a micro-pattern. In this way, only by changing the process parameters of the sandblasting treatment, such as sand grain size, sandblasting pressure, distance, angle, moving speed, etc., the sandblasting mold can be determined.

[0044] Specifically, the prism mold 400 is of a roller type. The design of the roller-type prism mold 400 enables a continuous rolling production method to be adopted when manufacturing prism optical elements, thereby significantly improving production efficiency. Compared with traditional static molds, the roller-type mold can continuously process, reducing the time for mold replacement and adjustment, making the production process more efficient. The roller-type prism mold 400 can adapt to the processing requirements of prism optical elements with different shapes and sizes. By adjusting parameters such as the diameter, length, and surface structure of the roller, prism elements with different optical properties can be produced to meet diverse market demands.

[0045] In addition, the present application also provides a backlight module, including the foregoing brightness enhancement film, a light guide plate 500, and a light source 600.

[0046] Example 1

[0047] The backlight module forms a prism layer 100 using the prism structure array in the technical solution of the present application, and designs the LED light source proximal and remote fixed areas as atomized prisms.

[0048] Comparative Example 1

[0049] The backlight module uses a conventional prism structure array.

[0050] Testing the light-emitting surface effects of Example 1 and Comparative Example 1 found that the backlight module using the conventional prism structure array has firefly and sky-side bright line phenomena on the light-emitting surface, while the backlight module using the prism structure array with the first atomized prism area 110 and the second atomized prism area 130 does not have firefly and sky-side bright line phenomena.

[0051] As can be seen from the foregoing, the present application relates to a brightness enhancement film and its manufacturing method. By designing a prism layer 100 including a high-haze atomized prism area and a normal prism area 120, the light uniformity of the display device is improved, and the shielding property, anti-firefly ability, and elimination of sky-side bright line ability of the product are significantly enhanced. In particular, through the adoption of the roller-type prism mold 400 and sandblasting treatment technology, the high-efficiency and precise manufacturing of the brightness enhancement film is realized. In the manufacturing method, the roller-type prism mold 400 is used for continuous rolling production to improve production efficiency; the precise atomized prism area is formed on the mold through sandblasting treatment to ensure the performance and quality of the brightness enhancement film. Using transfer and photocuring technologies, the atomized prism area and the normal prism area 120 are precisely replicated onto the prism layer 100. The technical solution of the present application not only improves production efficiency, reduces production costs, but also ensures product quality and enhances adaptability, providing strong support for the development of the display field.

[0052] The above is only a specific implementation manner of the present application. Any improvement made on the premise of the present application's concept is regarded as the protection scope of the present application.

Claims

1. A brightness enhancement film, characterized in that: It comprises a prism layer (100) arranged on a light-emitting surface, wherein the prism layer (100) comprises a prism array; In a direction perpendicular to and / or horizontal to the direction in which the prisms in the prism array are arranged, the prism layer (100) comprises a first atomized prism area (110), a common prism area (120), and a second atomized prism area (130) arranged in sequence, and the surfaces of the prisms in the first atomized prism area (110) and the second atomized prism area (130) have surface microstructures; The haze of the first hazy prism area (110) and the second hazy prism area (130) is greater than the haze of the common prism area (120).

2. The brightness enhancement film according to claim 1, characterized in that: The spacings between adjacent prisms in the prism array are equal or vary periodically.

3. The brightness enhancement film according to claim 1, characterized in that: The material refractive index of the prism array is 1.53-1.

69.

4. The brightness enhancement film according to claim 1, characterized in that: It also includes a substrate layer (200), wherein the thickness of the substrate layer (200) is 25-300 μm.

5. The brightness enhancement film according to claim 4, characterized in that: It also includes a back coating layer (300), wherein the back coating layer (300) is disposed on a surface of the substrate layer (200) opposite to the prism layer (100), and the haze of the back coating layer (300) is in the range of 2% to 20%.

6. The brightness enhancement film according to claim 1, characterized in that: The haze of the first hazy prism area (110) and the second hazy prism area (130) is 90% to 100%.

7. The brightness enhancement film according to claim 1, characterized in that: The haze in the first haze prism area (110) and the second haze prism area (130) is formed by a diffusion microstructure, and the density of the diffusion microstructure gradually decreases from the edge to the center.

8. A backlight module, characterized in that: It comprises the brightness enhancement film according to any one of claims 1 to 7, a light guide plate (500) and a light source (600).

Images