Back coating microlens structure and brightness enhancement film

Abstract

The invention 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 invention, the problem that the use effect is affected due to the fact that 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] The present invention relates to the field of display technology, and in particular to a back-coating microlens structure and a brightness enhancement film. Background Art

[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, multi-functionality, and low cost, which will require the optical effects of existing optical films to be continuously improved to meet market demand. The design of the back coating also has a significant impact on the shielding properties and brightness of the product.

[0003] There are many different methods for back-coating optical films, the most common of which are particle coating, sandblasting, mold transfer, or machining irregular surfaces. The common principle is to create an atomization effect through light scattering and refraction, while the presence of surface microstructures prevents adsorption to underlying optical components.

[0004] During use, different types of surface microstructures provide different optical gain effects. Among them, mechanically processed microstructures have better optical gain.

[0005] However, existing machined microstructures are all conventional structures that cannot achieve high haze, high shielding, high wear resistance, and high brightness, thus affecting the performance. Currently, no effective solutions have been proposed to address the above-mentioned problems. Summary of the Invention

[0006] Purpose of the invention: To provide a back-coated microlens structure and a brightness enhancement film to at least solve one of the problems existing in the above-mentioned prior art.

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

[0008] a semicircular convex hull; and

[0009] A conical concave portion is vertically extended inward along the center of the top of the semicircular convex hull;

[0010] Wherein, a conical concave portion is opened in a semicircular convex hull along a preset direction, and the semicircular convex hull and the conical concave portion are arranged concentrically to form a compound microlens structure with high shielding, high wear resistance and high brightness.

[0011] Preferably, the cross-sectional shape of the semicircular convex hull is a semicircular arc, and the cross-sectional shape of the conical concave portion is an inverted triangle;

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

[0013] Preferably, the cross-sectional shape of the conical recess is an isosceles triangle, the apex 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 hull is an ellipse or a semi-circle.

[0015] Preferably, the diameter of the circle in the front projection of the semi-circular convex hull is R, and the range of R is 10um ≤ R ≤ 100um.

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

[0017] wherein, r < R.

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

[0019] wherein, the transition portion is a sharp corner or a smooth surface.

[0020] To achieve the above object, according to another aspect of the present application, a backlight module is further provided.

[0021] The brightness enhancement film according to the present application includes the back-coated microlens structure described above;

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

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

[0024] Preferably, the number of the back-coated microlens structures is multiple, and the multiple compound microlens structures are arranged in a honeycomb shape continuously along a preset direction on the back surface of the substrate layer; or,

[0025] The multiple compound microlens structures are arranged in a rectangular array along a preset direction on the back surface of the substrate layer.

[0026] Preferably, the number of the back-coated microlens structures is multiple, and the multiple compound microlens structures are randomly and disorderly arranged on the back surface of the substrate layer.

[0027] Beneficial effect: In the embodiment of the present application, the microstructure is optimized by opening a conical recessed portion in a semicircular convex hull along a preset direction, and the semicircular convex hull and the conical recessed portion are arranged concentrically to form a compound microlens structure with high shielding, high wear resistance and high brightness, thereby achieving the purpose of multifunctional combination, thereby achieving the technical effect of obtaining a high shielding, high wear resistance and high brightness back coating, and further solving the technical problem that the existing mechanically processed microstructures are all conventional structures and cannot have the effects of high haze, high shielding, high wear resistance and high brightness, thereby affecting the use effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of the three-dimensional structure of the back coating microlens structure of the present invention;

[0029] Figure 2 is a cross-sectional view of the back-coated microlens structure of the present invention;

[0030] Figure 3 is a cross-sectional view of another back-coated microlens structure of the present invention;

[0031] Figure 4 2 is a schematic diagram of the planar structure of the back coating microlens structure of the present invention;

[0032] Figure 5 Schematic diagram of the back coating microlens structure of the present invention being continuously arranged in a honeycomb shape;

[0033] Figure 6 Schematic diagram of a rectangular array of back coating microlens structures of the present invention;

[0034] Figure 7 is a schematic diagram of a random and disordered arrangement of the back coating microlens structure of the present invention; and

[0035] Figure 8 The invention relates to a brightness enhancement film using the back coating microlens structure of the invention.

[0036] The accompanying drawings are:

[0037] 10. Semicircular convex hull;

[0038] 20. Conical concave portion;

[0039] 30, transition part; 301, sharp corner; 302, smooth surface;

[0040] 40. Base material layer;

[0041] 50. Prism structure. DETAILED DESCRIPTION

[0042] To enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0043] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so as to implement the embodiments of this application described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0044] In addition, the terms "installed", "set", "provided with", "connected", "connected to", "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there can be internal communication between two devices, components or parts. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will detail this application with reference to the drawings and in conjunction with the embodiments.

[0046] As Figure 1-8 shown, this application relates to a back-coated microlens structure and a brightness enhancement film. As Figure 1-4 shown, the 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 base plane as a reference; the hemispherical structure simulates the surface of an ideal Lambertian body, and controls the diffusion angle of incident light through curvature. When light is incident perpendicularly, the hemispherical surface can achieve uniform distribution correction of the incident angle.

[0047] Preferably, the material of the semi-circular convex hull 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 refraction effect.

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

[0049] Among them, a conical recess 20 is opened in a semi-circular convex hull 10 along a preset direction, and the semi-circular convex hull 10 and the conical recess 20 are concentrically arranged to form a compound microlens structure with high shielding, high wear resistance, and high brightness. By vertically arranging a conical recess 20 in a semi-circular convex hull 10 and adopting a concentric structure, a compound microlens structure is formed. At the same time, the respective characteristics of different structures are taken to provide an additive product effect. Among them, the preset direction can be the vertical direction or the Y-axis direction in two coordinate systems.

[0050] Specifically, for the microlens array, its high shielding property and poor scratch resistance are taken. At the same time, the optical gain effect of the microlens array is also better than that of particle coating and sandblasting microstructures. Using the microlens array on the back coating can also have the effects of high-efficiency diffusion shielding and high brightness. In addition, combined with the concave cone structure, the optical effect of the cone shape is to converge light, with a light-gathering and brightness-enhancing function. And the concave tip of the concave cone applied to the back of the optical film can be protected within the microlens structure without affecting the wear resistance of the back coating.

[0051] High shielding property: The concave conical structure can block background stray light within a certain angle; effectively improve image contrast or projection light uniformity.

[0052] High wear resistance: The semi-circular convex hull 10 provides strength support; the conical recess can disperse the frictional force and improve the wear resistance life; the surface concavo-convex design can also reduce the contact area and reduce the possibility of scratches.

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

[0054] Thereby, a back coating with high shielding, high wear resistance, and high brightness can be obtained. When used in the form of a single-sheet brightness enhancement film or a laminated brightness enhancement film in combination with the front prism microstructure, a brightness enhancement film product with better shielding effect and higher optical brightness can be obtained.

[0055] From the above description, it can be seen that the following technical effects are achieved in this application:

[0056] In the embodiments of the present application, an optimized microstructure is adopted. By providing a conical recess 20 in a semi-circular convex protrusion 10 along a preset direction, and the semi-circular convex protrusion 10 and the conical recess 20 are concentrically arranged, a compound microlens structure with high shielding, high wear resistance and high brightness is formed, achieving the purpose of multi-functional combination, thereby realizing the technical effect of obtaining a back coating with high shielding, high wear resistance and high brightness, and further solving the technical problem that existing machined microstructures are all conventional structures and cannot have the effects of high haze, high shielding, high wear resistance and high brightness at the same time, thus affecting the use effect.

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

[0058] Among them, the combination of a semi-circular arc and an inverted triangle forms the cross-sectional shape of a compound microlens structure. It can be understood that for the semi-circular arc cross-section: the cross-section of the semi-circular convex protrusion 10 is a semi-circular arc, and its geometric properties satisfy the standard spherical optical formula, which can uniformly refract incident light. When an elliptical cross-section is adopted, the light distribution can be optimized for a specific viewing angle.

[0059] Inverted triangle recess: The apex angle P of the isosceles triangle cross-section of the conical recess directly affects the total reflection condition.

[0060] Adopting the cross-sectional shape of the above structure has both shielding / diffusing effects (semi-circular arc) and light condensing functions (inverted triangle).

[0061] Further, the cross-sectional shape of the conical recess 20 is an isosceles triangle, the apex angle of the isosceles triangle is P, and the range of P is 60° ≤ P ≤ 100°. It can be understood that the angle control is directly related to the opening size of the recess and the scattering angle, thus affecting the shielding property and the light scattering distribution. By having multiple numerical values available for selection, the effect of flexible use can be achieved.

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

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

[0064] Further, the cross-sectional shape of the semi-circular convex protrusion 10 is an ellipse or a semi-circle. It can be understood that the effect of having multiple shapes available for selection can be achieved, and at the same time, good optical performance can be ensured.

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

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

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

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

[0069] Among them, r < R. It can be understood that r is the diameter of the circle formed by 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 forms a central symmetry of the structure.

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

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

[0073] Among them, the transition part 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. [[ID=Z8]]

[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, on which the back-coated microlens structure is disposed on the back surface of the substrate layer 40; and

[0076] a prism structure 50, disposed 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 basic 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 can be understood that by providing a variety of materials for selection, the effect of flexible selection can be achieved, so as to meet a variety of usage requirements.

[0079] Enhance brightness, block stray light, improve the light emission angle distribution, enhance brightness, block stray light, improve the light emission angle distribution.

[0080] The prism structure 50 controls the light direction, further condenses the light or guides the light to the front direction.

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

[0082] Such as Figure 5-6 As shown, the number of the back-coated microlens structures is multiple, and multiple said compound microlens structures are arranged continuously in a honeycomb shape along a preset direction on the back surface of the substrate layer 40; or,

[0083] Multiple said compound microlens structures are arranged in a rectangular array along a preset direction on the back surface of the substrate layer 40. It can be understood that the honeycomb-shaped continuous arrangement, with hexagons closely arranged, has a high filling rate and strong light guiding uniformity; among them, the preset direction can be horizontal and / or vertical directions.

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

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

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

[0087] Such as Figure 7 As shown, the number of the back-coated microlens structures is multiple, and multiple said compound microlens structures are randomly and disorderly arranged on the back surface of the substrate layer. It can be understood that through the random and disorderly arrangement, the anti-interference performance can be achieved, reducing moiré patterns and glare, and it can be used for special optical requirements.

[0088] Specifically, it is further illustrated by the following embodiments:

[0089] Embodiment 1

[0090] A brightness enhancement film has a prism column with a bottom width of 70um on the front side and adopts the compound microlens structure of the present application on the back side.

[0091] At this time, after testing, the performance parameters of the back-coated microlens structure are: haze is 95%, abrasion resistance of the back coating is 3000 g, shielding property is excellent, and brightness ratio is 113%.

[0092] Comparative Example 1

[0093] The difference from Example 1 lies in that the back coating is made by particle coating.

[0094] At this time, after testing, the performance parameters of the back-coated microlens structure are: haze is 30%, abrasion resistance of the back coating is 2000 g, shielding property is average, and brightness ratio is 100%.

[0095] Comparative Example 2

[0096] The difference from Example 1 lies in that the back coating is made by sandblasting die stamping.

[0097] At this time, after testing, the performance parameters of the back-coated microlens structure are: haze is 30%, abrasion resistance of the back coating is 2500 g, shielding property is average, and brightness ratio is 107%.

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

[0099]

[0100]

[0101] It can be seen from the above test results that:

[0102] 1. From Example 1 and Comparative Examples 1 and 2, it can be seen that by using different back coating structures and combining with the front prism structure 50, single-sheet brightness enhancement film products are made, and various product indexes are measured;

[0103] The results show that using the compound microlens structure designed in the present invention as the back coating has the highest haze. While providing good shielding property and the best light homogenization effect, it also shows the highest optical gain effect, achieving the design purpose.

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

[0105] I. Mold preparation

[0106] 1.1 Master plate processing

[0107] Adopt including but not limited to: femtosecond laser engraving

[0108] Take a nickel metal plate (thickness 5 mm), and evenly coat a photoresist (thickness 15 μm) on its surface.

[0109] Use femtosecond laser (wavelength 1030 nm) to engrave point by point on the photoresist to form an array of semi-circular convex hulls (diameter 50 μm).

[0110] Carry out secondary engraving on the conical depression at the top of the convex hull (diameter 15 μm, apex angle 80°), ensuring alignment with the center of the convex hull (deviation < 0.3 μm).

[0111] Surface polishing

[0112] Put the engraved master into a plasma polishing equipment and introduce a mixed gas of argon and oxygen.

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

[0114] 1.2 Electroforming replication mold

[0115] Immerse the master in nickel electroforming solution (nickel sulfamate solution) and energize for 8 hours to deposit a nickel layer (thickness 2 mm) on the surface.

[0116] Separate the nickel template and spray fluorosilane release agent to form a reusable imprint mold.

[0117] Directly coat the electroformed nickel plate on the surface of the roller mold body, and it can be used as a microstructure mold roller for roll-to-roll coating and imprinting;

[0118] II. Microstructure imprinting

[0119] As Figure 8 shown, perform UV imprinting on both the upper and lower surfaces of the PET to obtain a backside compound microlens structure and a front-side prism structure respectively. No post-treatment is required.

[0120] Use a PET base film with a chemical coating, and directly perform imprinting and curing on the upper and lower surfaces with a photocurable UV resin coating.

[0121] 2.1 Micro-lens structure imprinting

[0122] Use the microstructure mold coated with nickel plate, coat the UV glue on the surface of the PET, and irradiate with ultraviolet light at a strength of 600 mJ / cm 2 during imprinting to directly perform imprinting and curing to obtain a microlens layer.

[0123] 2.2 Prism structure imprinting

[0124] The process is the same as that of the backside microlens imprinting, except that a prism structure mold is used. The prism structure can be directly machined on the roller mold body and then directly used as a roll-to-roll coating and imprinting mold.

[0125] The preferred embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in 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 these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. Back-coated microlens structure, characterized in that, Comprising: A semi-circular convex hull (10); And A conical concave portion (20) vertically extending inward along the top center of the semi-circular convex hull (10); Wherein, a conical concave portion (20) is formed in a semi-circular convex hull (10) along a preset direction, and the semi-circular convex hull (10) and the conical concave portion (20) are concentrically arranged 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 hull (10) is a semi-circular arc, and the cross-sectional shape of the conical concave portion (20) is an inverted triangle; Wherein, a semi-circular arc and an inverted triangle are combined to form the cross-sectional shape of a compound microlens structure.

3. The back-coated microlens structure according to claim 1, characterized in that, The cross-sectional shape of the conical concave portion (20) is an isosceles triangle, and the apex angle of the isosceles triangle is P, and the range of P is 60° ≤ P ≤ 100°.

4. The back-coated microlens structure according to claim 1, characterized in that, The cross-sectional shape of the semi-circular convex hull (10) is an ellipse or a semi-circle.

5. The back-coated microlens structure according to claim 1, characterized in that, The circular diameter of the front projection of the semi-circular convex hull (10) is R, and the range of R is 10um ≤ R ≤ 100um.

6. The back-coated microlens structure according to claim 5, characterized in that, The circular diameter of the front projection of the conical concave portion (20) is r, and the range of r is 5um ≤ r ≤ 50um; Wherein, r < R.

7. The back-coated microlens structure according to claim 1, characterized in that, A transition portion (30) is provided at the junction of the semi-circular convex hull (10) and the conical concave portion (20); Wherein, the transition portion (30) is a sharp corner (301) or a smooth surface (302).

8. Brightening film, characterized in that, Comprising the back-coated microlens structure according to any one of claims 1-7; Further comprising: a substrate layer (40), the back-coated microlens structure is disposed on the back surface of the substrate layer (40); and A prism structure is disposed on the substrate layer (40) on the side away from the back-coated microlens structure to form a single-sheet brightness enhancement film.

9. The brightening film according to claim 8, wherein The number of the back-coated microlens structures is multiple, and multiple compound microlens structures are continuously arranged in a honeycomb shape along a preset direction on the back surface of the substrate layer (40); or, Multiple compound microlens structures are arranged in a rectangular array along a preset direction on the back surface of the substrate layer (40).

10. The brightening film according to claim 8, wherein, The number of the back-coated microlens structures is multiple, and multiple compound microlens structures are randomly and disorderly arranged on the back surface of the substrate layer (40).

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