Back coating microlens structure and brightness enhancement film

Abstract

The utility model discloses a back coating microlens structure and a brightness enhancement film, and relates to the technical field of display. The back coating micro-lens structure comprises a semicircular convex hull, a plurality of micro-lenses and a plurality of micro-lenses, the conical concave part vertically extends towards the interior of the semicircular convex hull along the center of the top of the semicircular convex hull; wherein one conical concave part is arranged in one semicircular convex hull along a preset direction, and the semicircular convex hull and the conical concave part are concentrically arranged, so that the compound micro lens back coating structure with high shielding, high wear resistance and high brightness is formed. According to the utility model, the problem that the use effect is influenced because the existing conventional micro lens structure cannot have the effects of high haze, high shielding, high wear resistance and high brightness at the same time is solved.

Description

Technical Field

[0001] This utility model relates to the field of display technology, and in particular to a back-coated microlens structure and a brightness enhancement film. Background Technology

[0002] With the continuous emergence of new display technologies, brightness enhancement films will face more opportunities and challenges. Their technology will continue to develop towards high performance, multifunctionality, and low cost, requiring continuous improvement in the optical performance of existing optical films to meet market demands. Among these factors, the design of the back coating layer is also a crucial element affecting both shielding performance and product brightness.

[0003] There are many different forms of back coating for optical films, the most common being particle coating, sandblasting mold transfer, or machining of irregular surfaces. Their common principle is to provide a fogging effect through light scattering and refraction, while the presence of surface microstructures prevents adhesion to other underlying optical components.

[0004] During use, the different types of surface microstructures provide varying degrees of optical gain. Among them, mechanically processed microstructures exhibit better optical gain.

[0005] However, existing machined microstructures are all conventional structures, unable to simultaneously achieve high haze, high opacity, high wear resistance, and high gloss, thus affecting their performance. Currently, no effective solution has been proposed to address these issues. Utility Model Content

[0006] Purpose of the utility model: To provide a back-coated microlens structure and a brightness enhancement film, so as to at least solve one of the problems existing in the prior art.

[0007] Technical solution: A back-coated microlens structure, comprising:

[0008] A semi-circular convex hull; and

[0009] A conical recess extends vertically inward from the top center of the semi-circular convex bulge.

[0010] In this structure, a conical recess is formed within a semi-circular convex hull along a predetermined direction, and the semi-circular convex hull and the conical recess are arranged at the same center to form a compound microlens structure with high shielding, high wear resistance and high brightness.

[0011] Preferably, the cross-sectional shape of the semi-circular convex bulge is a semi-circular arc, and the cross-sectional shape of the conical recess is an inverted triangle;

[0012] The combination of a semicircular arc and an inverted triangle forms the cross-sectional shape of a compound microlens structure.

[0013] Preferably, the cross-sectional shape of the conical recess is an isosceles triangle, the vertex angle of the isosceles triangle is P, and the range of P is 60°≤P≤100°.

[0014] Preferably, the cross-sectional shape of the semi-circular convex bulge is elliptical or semi-circular.

[0015] Preferably, the diameter of the circle projected from the front of the semi-circular convex bulge is R, and the range of R is 10um≤R≤100um.

[0016] Preferably, the diameter of the circle projected from the front of the conical recess is r, and the range of r is 5um≤r≤50um;

[0017] Where, r <R。

[0018] Preferably, a transition portion is provided at the junction of the semi-circular convex bulge and the conical concave portion;

[0019] The transition portion is either a sharp corner or a rounded surface.

[0020] To achieve the above objectives, according to another aspect of this application, a backlight module is also provided.

[0021] The brightness enhancement film according to this application includes the aforementioned back-coated microlens structure;

[0022] It also includes: a substrate layer, wherein the back-coated microlens structure is disposed on the back side of the substrate layer; and

[0023] A prism structure is disposed on the substrate layer on the side away from the back coating microlens structure to form a single-layer brightness enhancement film.

[0024] Preferably, the number of the back-coated microlens structures is multiple, and the multiple composite microlens structures are continuously arranged in a honeycomb pattern on the back side of the substrate layer along a predetermined direction; or...

[0025] Multiple of the aforementioned complex microlens structures are arranged in a rectangular array along a predetermined direction on the back side of the substrate layer.

[0026] Preferably, the number of the back coating microlens structures is multiple, and the multiple composite microlens structures are randomly and disorderedly arranged on the back side of the substrate layer.

[0027] Beneficial effects: In this embodiment, an optimized microstructure is adopted. By opening a conical recess in a predetermined direction within a semi-circular convex hull, and with the semi-circular convex hull and the conical recess co-centered, a compound microlens structure with high shielding, high wear resistance, and high brightness is formed. This achieves the purpose of multifunctional composite structure, thereby realizing the technical effect of obtaining a back coating with high shielding, high wear resistance, and high brightness. This solves the technical problem that existing mechanically processed microstructures are all conventional structures and cannot simultaneously achieve the effects of high haze, high shielding, high wear resistance, and high brightness, thus affecting the performance. Attached Figure Description

[0028] Figure 1 This is a three-dimensional structural diagram of the back-coated microlens structure of this utility model;

[0029] Figure 2 This is a cross-sectional view of the back-coated microlens structure of this utility model;

[0030] Figure 3 This is a cross-sectional view of another back-coated microlens structure of this utility model;

[0031] Figure 4 This is a schematic diagram of the planar structure of the back-coated microlens structure of this utility model;

[0032] Figure 5 This is a schematic diagram of the back-coated microlens structure of this utility model, which is arranged in a continuous honeycomb pattern.

[0033] Figure 6 This is a schematic diagram of the back-coated microlens structure of this utility model in the form of a rectangular array;

[0034] Figure 7 This is a schematic diagram of the random, disordered arrangement of the back-coated microlens structure of this utility model; and

[0035] Figure 8 It is a brightness enhancement film that utilizes the back-coated microlens structure of this utility model.

[0036] The attached figures are labeled as follows:

[0037] 10. Semicircular convex hull;

[0038] 20. Conical depression;

[0039] 30. Transition section; 301. Sharp corner; 302. Rounded surface;

[0040] 40. Substrate layer;

[0041] 50. Prism structure. Detailed Implementation

[0042] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0043] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0044] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this utility model based on the specific circumstances.

[0045] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0046] like Figure 1-8 As shown, this application relates to a back-coated microlens structure and a brightness enhancement film. For example... Figure 1-4 As shown, this back-coated microlens structure includes a semi-circular convex hull 10; the semi-circular convex hull 10 refers to a hemispherical protrusion constructed with the substrate plane as a reference; the hemispherical structure simulates the surface of an ideal Lambertian body, and the diffusion angle of the incident light is controlled by the curvature. When the light is incident perpendicularly, the hemispherical surface can achieve uniform distribution correction of the incident angle.

[0047] Preferably, the material of the semi-circular bulge 10 includes, but is not limited to, high refractive index polymers (such as PMMA, n=1.49 or polycarbonate, n=1.58) to enhance the refractive effect.

[0048] A conical recess 20 extends vertically inward from the top center of the semi-circular convex bulge 10. As a secondary optical structure, the inclination angle of its inner wall directly affects the total internal reflection condition. For example, when P = 90°, an inner wall inclination angle of 45° can achieve total internal reflection for light rays with an incident angle greater than 45°. Of course, this can be set according to actual usage requirements and is not limited in this application.

[0049] In this structure, a conical recess 20 is formed within a semi-circular protrusion 10 along a predetermined direction, and the semi-circular protrusion 10 and the conical recess 20 are co-centered to form a compound microlens structure with high shielding, high wear resistance, and high brightness. By vertically positioning the conical recess 20 within the semi-circular protrusion 10 and using a co-centered structure, a compound microlens structure is formed. Furthermore, the characteristics of different structures are combined to provide enhanced product effects. The predetermined direction can be a vertical direction or the Y-axis direction in a two-coordinate system.

[0050] Specifically, microlens arrays are chosen for their high shielding and scratch resistance. Furthermore, the optical gain of microlens arrays is superior to that of particle coatings and sandblasted microstructures. Using microlens arrays in the back coating also provides highly efficient diffusion shielding and high brightness. In addition, the concave conical structure, with its conical shape, concentrates light, enhancing brightness. Moreover, the concave tip of the concave cone applied to the back of the optical film is protected within the microlens structure, preserving the abrasion resistance of the back coating.

[0051] High shielding: The concave conical structure can block stray light from the background within a certain angle; effectively improving image contrast or uniformity of projected light.

[0052] High abrasion resistance: The semi-circular convex bump 10 provides strength support; the conical recess disperses friction and improves wear life; the uneven surface design also reduces the contact area and reduces the possibility of scratches.

[0053] High brightness: The semi-circular convex hull can effectively focus light and increase the light intensity per unit area; the conical concave hull provides microstructure scattering, reduces light loss, and improves overall brightness; the combination of the two optimizes the emission angle and light flux distribution, and improves optical efficiency.

[0054] This allows for the creation of a back coating that offers high shielding, high wear resistance, and high brightness. When combined with a front prism microstructure and used as a single-sheet or laminated brightening film, a brightening film product with better shielding and higher optical brightness can be obtained.

[0055] As can be seen from the above description, this application achieves the following technical effects:

[0056] In this embodiment, an optimized microstructure is adopted. A conical recess 20 is formed within a semi-circular protrusion 10 along a preset direction, and the semi-circular protrusion 10 and the conical recess 20 are co-centered. This forms a compound microlens structure with high shielding, high wear resistance, and high brightness, achieving a multi-functional composite structure. This results in a high shielding, high wear resistance, and high brightness back coating, thus solving the technical problem that existing mechanically processed microstructures are all conventional structures and cannot simultaneously achieve high haze, high shielding, high wear resistance, and high brightness, thereby affecting the performance.

[0057] Furthermore, the cross-sectional shape of the semi-circular convex bulge 10 is a semi-circular arc, and the cross-sectional shape of the conical recess 20 is an inverted triangle.

[0058] The combination of a semicircular arc and an inverted triangle forms the cross-sectional shape of a compound microlens structure. It can be understood that the semicircular arc cross-section: the cross-section of the semicircular convex hull 10 is a semicircular arc, and its geometric properties satisfy the standard spherical optics formula, allowing for uniform refraction of incident light. When an elliptical cross-section is used, the light distribution can be optimized for a specific viewing angle.

[0059] Inverted triangular depression: The vertex angle P of the isosceles triangular section of the conical depression directly affects the total internal reflection condition.

[0060] The cross-sectional shape of the above structure has both a shielding / diffusing effect (semi-circular arc) and a light-focusing function (inverted triangle).

[0061] Furthermore, the conical recess 20 has a cross-sectional shape of an isosceles triangle, with the vertex angle being P, and P ranging from 60° to 100°. It is understood that angle control directly affects the opening size and scattering angle of the recess, thus influencing shielding effectiveness and light scattering distribution. Multiple selectable values ​​allow for flexible application.

[0062] Specifically, when P < 60°, the tip curvature radius is too small (< 0.1 μm), which easily leads to stress concentration and cracking.

[0063] When P>100°, the inner wall tilt angle is <40°, the total internal reflection condition fails, and the photon recovery efficiency decreases by >30%.

[0064] Furthermore, the cross-sectional shape of the semi-circular convex bulge 10 is elliptical or semi-circular. This allows for a variety of shapes to be chosen while ensuring good optical performance.

[0065] Further, the diameter of the circle in the front projection of the semi-circular convex hull 10 is R, and the range of R is 10 μm ≤ R ≤ 100 μm. It can be understood that R is the diameter of the circle in the front projection of the semi-circular convex hull 10, which controls the overall scale of the microlens.

[0066] Specifically, the lower limit of 10 μm is limited by the ultraviolet micro-nano imprint resolution (the minimum feature size ≈ 5 μm) to ensure the structural integrity.

[0067] The upper limit of 100 μm: To avoid the failure of optical path regulation (when R > 100 μm, the full width at half maximum expands to ±25°, losing the advantage of light concentration).

[0068] Further, the diameter of the circle in the front projection of the conical recess 20 is r, and the range of r is 5 μm ≤ r ≤ 50 μm;

[0069] Among them, r < R. It can be understood that r is the diameter of the circle in the front projection of the conical recess 20, which controls the size of the recessed area.

[0070] Adopting r < R can ensure that the recessed structure is completely surrounded by the convex hull structure and form a central symmetry of the structure.

[0071] Preferably, when r / R = 0.3, the edge of the cone cavity base is located in the region with the fastest change in the surface curvature of the convex hull, which can maximize the light regulation efficiency.

[0072] As Figure 2-3 shown, a transition portion 30 is provided at the junction of the semi-circular convex hull 10 and the conical recess 20;

[0073] Among them, the transition portion 30 is a sharp corner 301 or a smooth surface 302. It can be understood that the sharp corner 301 transition: a sharp boundary, which helps to form an obvious optical refraction boundary. The smooth transition provides a smoother structural transition, improving crack resistance, forming consistency, and wear resistance.

[0074] As Figure 5-7 shown, the present application also relates to a brightness enhancement film, including the back-coated microlens structure described above;

[0075] It further includes: a substrate layer 40, and the back-coated microlens structure is provided on the back surface of the substrate layer 40; and

[0076] A prism structure 50 is provided on the substrate layer 40 on the side away from the back-coated microlens structure to form a single brightness enhancement film.

[0077] Specifically, the substrate layer 40 refers to the base material or substrate to which the optical film or coating adheres, which can achieve good fixing and supporting effects; at the same time, it can also cooperate with other film layer structures to achieve various functional effects.

[0078] Furthermore, the substrate layer 40 is made of polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polyethylene, polyvinyl chloride, or polystyrene. It is understood that by providing a variety of materials to choose from, a flexible selection effect can be achieved, thereby meeting a variety of usage requirements.

[0079] It enhances brightness, blocks stray light, and improves the distribution of light emission angle.

[0080] Prism structure 50 controls the direction of light, further focuses light, or guides light forward.

[0081] Of course, the above-mentioned compound microlens structure can also be used on the back side of the lower prism layer of the laminated brightness enhancement film.

[0082] like Figure 5-6 As shown, the number of the back-coated microlens structures is multiple, and the multiple composite microlens structures are continuously arranged in a honeycomb pattern on the back side of the substrate layer 40 along a predetermined direction; or,

[0083] Multiple of the aforementioned complex microlens structures are arranged in a rectangular array along a predetermined direction on the back side of the substrate layer 40. It is understood that the honeycomb-like continuous arrangement and the tightly packed hexagonal structures result in a high fill rate and strong light-guiding uniformity; wherein, the predetermined direction can be horizontal and / or vertical.

[0084] Preferably, the crystal has a hexagonal lattice with a unit spacing P = 2Rsin(60°) ≈ 1.732R. The fill density reaches 90.7%, and the brightness uniformity is >95%.

[0085] The rectangular array arrangement is neat and tidy, which is conducive to batch processing and optical simulation.

[0086] Preferably, the X / Y axis spacing P x =P y =2R. Tilt the array 5°-10° to eliminate moiré fringes.

[0087] like Figure 7 As shown, the back-coated microlens structure is multiple, and these multiple compound microlens structures are randomly and disorderedly arranged on the back side of the substrate layer. It can be understood that this random and disordered arrangement achieves good anti-interference properties, reduces moiré patterns and glare, and can be used for special optical applications.

[0088] The following examples further illustrate this point:

[0089] Example 1

[0090] The brightening film has a prism pillar with a bottom width of 70µm on the front and a compound microlens structure on the back as described in this application.

[0091] At this point, the performance parameters of the back-coated microlens structure, as tested, are: haze of 95%, back coating abrasion resistance of 3000g, excellent shielding properties, and brightness ratio of 113%.

[0092] Comparative Example 1

[0093] The difference from Example 1 is that a particle coating method is used to create the back coating.

[0094] At this point, the performance parameters of the back-coated microlens structure, as tested, are: haze of 30%, back coating abrasion resistance of 2000g, moderate shading, and brightness ratio of 100%.

[0095] Comparative Example 2

[0096] The difference from Example 1 is that the back coating is made by sandblasting mold printing.

[0097] At this point, the performance parameters of the back-coated microlens structure, as tested, are: haze of 30%, back coating abrasion resistance of 2500g, moderate shading, and brightness ratio of 107%.

[0098] The results of each embodiment and comparative example are shown in Table 1:

[0099]

[0100]

[0101] The test results above show that:

[0102] 1. As can be seen from Example 1 and Comparative Examples 1 and 2, different back coating structures are used in combination with the front prism structure 50 to make a single brightening film product, and various product indicators are measured.

[0103] The results show that using the compound microlens structure designed in this invention as the back coating has the highest haze, provides good shielding and the best light uniformity, and also exhibits the highest optical gain, thus achieving the design objective.

[0104] The process flow of this application is as follows:

[0105] I. Mold Preparation

[0106] 1.1 Master plate processing

[0107] Employing methods including, but not limited to: femtosecond laser engraving

[0108] Take a nickel metal plate (5 mm thick) and coat its surface with photoresist (15 μm thick).

[0109] A semi-circular convex hull array (50 micrometers in diameter) is formed by etching point by point on the photoresist using a femtosecond laser (wavelength 1030 nanometers).

[0110] The conical recess at the top of the convex hull (15 micrometers in diameter, 80-degree apex angle) is engraved a second time to ensure alignment with the center of the convex hull (deviation <0.3 micrometers).

[0111] Surface polishing

[0112] The engraved master copy is placed in a plasma polishing device, and a mixture of argon and oxygen is introduced.

[0113] Polish for 15 minutes to remove surface burrs and reduce roughness to below 5 nanometers.

[0114] 1.2 Electroforming Replication Mold

[0115] The master plate is immersed in nickel electroforming solution (nickel sulfamate solution) and electrified for 8 hours to deposit a nickel layer (2 mm thick) on the surface.

[0116] Separate the nickel template, spray with fluorosilane release agent to form a reusable embossing mold.

[0117] By directly covering the surface of the roller mold body with an electroformed nickel plate, it can be used as a microstructure mold roller for roll-to-roll coating and imprinting.

[0118] II. Microstructure Imprinting

[0119] like Figure 8 As shown, by performing UV embossing on both the top and bottom sides of the PET, a compound microlens structure on the back and a prism structure on the front can be obtained respectively. No post-processing is required.

[0120] Using a chemically coated PET base film, it is possible to directly press and cure the upper and lower surfaces with a light-curing UV resin coating.

[0121] 2.1 Microlens Structure Imprinting

[0122] Using a microstructured mold with nickel-coated plates, UV adhesive is applied to the PET surface, and during imprinting, 600 mJ / cm² is applied. 2 Intensive ultraviolet light irradiation can directly press-print and solidify the microlens layer.

[0123] 2.2 Prism Structure Imprinting

[0124] The process is the same as that of back-side microlens embossing, except that a prism structure mold is used instead. The prism structure can be directly cut from the main body of the roller mold and then used directly as a roll-to-roll coating embossing mold.

[0125] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and all such equivalent transformations fall within the protection scope of the present invention.

Claims

1. A back-coated microlens structure, characterized by, include: A semi-circular convex hull (10); and A conical recess (20) is provided, extending vertically inward from the top center of the semi-circular protrusion (10); In this structure, a conical recess (20) is formed in a semi-circular protrusion (10) along a predetermined direction, and the semi-circular protrusion (10) and the conical recess (20) are arranged at the same center to form a compound microlens structure with high shielding, high wear resistance and high brightness.

2. The back-coated microlens structure according to claim 1, characterized in that, The cross-sectional shape of the semi-circular convex bulge (10) is a semi-circular arc, and the cross-sectional shape of the conical recess (20) is an inverted triangle. The combination of a semicircular arc and an inverted triangle forms the cross-sectional shape of a compound microlens structure.

3. The back-coated microlens structure of claim 1, wherein, The conical recess (20) has a cross-sectional shape of an isosceles triangle with a vertex angle P, and the range of P is 60°≤P≤100°.

4. The back-coated microlens structure of claim 1, wherein, The cross-sectional shape of the semi-circular convex hull (10) is elliptical or semi-circular.

5. The back-coated microlens structure of claim 1, wherein, The diameter of the circle projected from the front of the semi-circular convex hull (10) is R, and the range of R is 10um≤R≤100um.

6. The back-coated microlens structure of claim 5, wherein, The diameter of the circle of the front projection of the conical recess (20) is r, and the range of r is 5um≤r≤50um; Where, r <R。 7. The back-coated microlens structure of claim 1, wherein, A transition portion (30) is provided at the junction of the semi-circular convex bulge (10) and the conical recess (20); The transition portion (30) is either a sharp corner (301) or a smooth surface (302).

8. Brightening film, characterized by Includes the back-coated microlens structure as described in any one of claims 1-7; It also includes: a substrate layer (40), wherein the back-coated microlens structure is disposed on the back side of the substrate layer (40); and A prism structure is disposed on the substrate layer (40) on the side away from the back coating microlens structure to form a single-sheet brightening film.

9. The brightening film according to claim 8, characterized in that, The number of the back-coated microlens structures is multiple, and the multiple composite microlens structures are continuously arranged in a honeycomb pattern on the back side of the substrate layer (40) along a preset direction; or, Multiple of the aforementioned complex microlens structures are arranged in a rectangular array along a predetermined direction on the back side of the substrate layer (40).

10. The brightness enhancement film of claim 8, wherein, The number of the back coating microlens structures is multiple, and the multiple composite microlens structures are randomly and disorderedly arranged on the back side of the substrate layer (40).

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