A collimating film and display module containing the same

Abstract

The application provides a collimating film, which comprises a reflecting layer and a plurality of optical lenses arranged in an array on the reflecting layer, the optical lenses comprising a cylindrical part and a paraboloid-like truncated cone part, the curved surface of the paraboloid-like truncated cone part having a parabolic curvature in the radial direction and a circular arc structure in the circumferential direction; one end of the paraboloid-like truncated cone part is inwardly recessed to form a cylindrical recess, and the bottom of the cylindrical recess is outwardly protruded to form a convex lens; the reflecting layer comprises a reflecting area and a plurality of circular light-transmitting areas arranged in an array, the circular light-transmitting areas and the optical lenses are arranged in the same way and one-to-one correspondence. The application also provides a display module containing the above-mentioned collimating film. According to the principle that the incident light on the focal point of the convex lens is emitted as parallel light, the collimating film of the application collimates the light rays in the central part of the optical lens, improves the collimating effect of the existing collimating film, and has a broad application prospect.

Description

Technical Field

[0001] This invention relates to the field of optical films, and more specifically, to a collimating film and a display module containing the same. Background Technology

[0002] With technological advancements and the iteration of electronic products, user experience has gradually become a key focus and highlight of products. In the display field, such as mobile phone screens and computer screens, users are increasingly concerned about privacy, which requires adjusting the directionality of light and narrowing the viewing angle of electronic products to achieve a privacy protection effect. In areas such as automotive dashboards, users want to reduce reflections to improve safety and visual effects, which also requires adjusting the directionality of light. Both of these scenarios require the use of optical films with collimation effects.

[0003] In the existing technology, optical films with collimation effect mainly include two technical approaches. One is to use the characteristics of light-absorbing materials to absorb stray light and allow only collimated light to pass through in order to achieve optical collimation and privacy protection, such as CN112817074A. However, this type of collimation film will result in low overall light utilization of the display module. The other is to use optical elements with specific structures (common inverted conical optical elements) for collimation, such as CN101091133A. However, this type of optical element can only collimate the light that hits its boundary surface, and it is difficult to collimate the light incident at the center, so the collimation effect is limited.

[0004] In summary, how to further improve the collimation effect based on existing inverted conical optical elements is a difficult problem that affects user experience. Summary of the Invention

[0005] The main objective of this invention is to provide a collimating film and a display module containing the same, so as to solve the problem in the prior art that it is difficult to collimate light incident at the center using an inverted conical optical element.

[0006] To achieve the above objectives, according to one aspect of the present invention, a collimation membrane is provided. The collimating film includes a reflective layer and a plurality of optical lenses arranged in an array on the reflective layer; each optical lens includes a cylindrical portion and a quasi-parabolic frustum portion, the curved surface of the quasi-parabolic frustum portion having a parabolic curvature in the radial direction and a circular arc structure in the circumferential direction; the quasi-parabolic frustum portion has a first end and a second end facing away from each other, the end face radius of the first end is smaller than the end face radius of the second end, and the end face of the cylindrical portion is connected to the end face of the second end of the quasi-parabolic frustum portion; the first end is recessed inward to form a cylindrical groove, the center line of the cylindrical groove coincides with the center line of the quasi-parabolic frustum portion, the bottom radius of the cylindrical groove is less than or equal to the end face radius of the first end of the quasi-parabolic frustum portion, and the bottom of the cylindrical groove bulges outward to form a convex lens; the reflective layer includes a reflective area and an array of circular light-transmitting areas, the circular light-transmitting areas being arranged identically and corresponding one-to-one with the optical lenses.

[0007] Furthermore, the depth h of the cylindrical groove is less than the height H of the parabolic frustum portion.

[0008] Furthermore, the center O of the circular light-transmitting area coincides with the focal point F of the convex lens on the optical lens corresponding to the light-transmitting area.

[0009] Furthermore, the focal point f1 of the parabola coincides with the center O of the circular light-transmitting area.

[0010] Furthermore, the focal point f1 of the parabola coincides with the intersection point f2 of the backward extension of the refracted ray obtained by the light emitted from the center O of the circular light-transmitting area and refracted by the curved surface of the cylindrical groove.

[0011] Furthermore, the curvature of the parabola is 0.24 to 0.3.

[0012] Furthermore, the refractive index of the optical lens is 1.4 to 1.7.

[0013] Furthermore, the reflectivity of the reflective area is 80% to 95%, and the transmittance of the circular light-transmitting area is 90% to 100%.

[0014] Furthermore, the surface of the reflective region away from the optical lens is provided with microstructures that can converge reflected light rays reflected through the surface.

[0015] According to another aspect of the present invention, a display module is provided. The display module includes the collimating film described above.

[0016] By applying the technical solution of this invention, light rays incident from the center of the optical lens can be collimated, overcoming the problem that existing inverted conical optical elements cannot collimate light rays incident at the center, thus improving the collimation effect. At the same time, by adjusting the parabolic curvature of the optical lens, it is possible to achieve total internal reflection and collimation of most or even all incident light rays falling on the parabolic surface. In addition, a microstructure is set on the side of the reflection area away from the optical lens, which not only allows some light rays that did not enter the circular light-transmitting area during the first propagation to re-enter the circular light-transmitting area through secondary or multiple reflections, but also further enhances the focusing effect of the reflected light and improves the utilization rate of light. Attached Figure Description

[0017] Figure 1 This is a cross-sectional view of a single optical lens along the diameter of the bottom surface of the cylindrical portion in one implementation of this application;

[0018] Figure 2 This is a schematic diagram of the optical path in a single optical lens in another implementation of this application;

[0019] Figure 3 A perspective view of a single optical lens in another implementation of this application;

[0020] Figure 4 This is a top view of the collimating membrane in another implementation of this application;

[0021] Figure 5 In another implementation of this application Figure 4 A cross-sectional view along the CC direction;

[0022] Figure 6 This is a perspective view of the collimating membrane in another implementation of this application;

[0023] Among them, 100-collimating film, L1-optical lens layer, L2-reflective layer, 101-optical lens, 102-reflective area, 103-circular light-transmitting area, 1-cylindrical part, 2-parabolic frustum part, 2-1-cylindrical groove, 2-2-convex lens, a-lens surface, b-vertical surface of cylindrical groove, c-parabolic surface, A-lens surface working area, B-parabolic surface working area. Detailed Implementation

[0024] To enable those skilled in the art to better understand the present invention, the technical solutions in specific embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other; furthermore, the drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes between parts, etc., may not be the same as in reality. Even when representing the same parts, there may be cases where the dimensions and ratios are represented differently depending on the drawings.

[0025] Unless otherwise defined, the technical or scientific terms used in this invention disclosure should have the ordinary meaning that can be understood by one of skill in the art. The invention will now be described in detail with reference to embodiments.

[0026] As analyzed in the background section of this application, existing technologies that use light-absorbing materials to improve collimation significantly impact light utilization. While optical elements with specific structures, especially inverted conical lenses, can achieve collimated light to some extent while maintaining a certain level of light utilization, they can only reflect light reaching the boundary surface to achieve collimation. They cannot address the issue that light incident from the center cannot reach the boundary and therefore cannot be reflected, meaning their collimation effect is limited. Researchers have attempted to design solutions involving optical element structures and the stacking of other functional layers, as exemplified by the technology used in patent CN105849595B. However, this approach is technically challenging, costly, and offers limited improvement in collimation. Based on the principle that light incident at the focal point of a convex lens emerges as parallel light, this application discovers that combining a convex lens with an existing inverted conical optical lens can compensate for the inability to collimate light incident at the center of the inverted conical optical lens. Based on this discovery and a series of studies, this application provides a collimation film and a display module containing it.

[0027] In a typical embodiment of this application, a collimating film 100 is provided. The collimating film 100 includes a reflective layer L2 and a plurality of optical lenses 101 arranged in an array on the reflective layer. The optical lens 101 includes a cylindrical part 1 and a parabolic frustum part 2. The parabolic frustum part 2 is a three-dimensional shape formed by rotating a parabola 360 degrees around its axis of symmetry and then cutting it with two parallel circular surfaces of different sizes that are perpendicular to the axis of symmetry of the parabola. Therefore, the curved surface (i.e., parabolic surface c) of the parabolic frustum part 2 has a parabolic curvature in the radial direction and a circular arc structure in the circumferential direction. In existing technologies, conical optical elements are commonly used as collimators. The cross-section of a conical optical element is an isosceles triangle, while the cross-section of the parabolic frustum 2 in this application is a parabolic surface. Since incident rays in practical applications are non-parallel rays emitted from the emission point, even if the two base angles of the isosceles triangle are adjusted so that some incident rays at a specific angle of incidence pass through the two legs of the isosceles triangle and are emitted perpendicularly to the light-emitting surface (i.e., becoming collimated light), the vast majority of incident rays at non-specific angles of incidence cannot become collimated light. In other words, for a plane (leg), non-parallel incident light cannot produce parallel emitted light. The advantage of using a parabolic surface compared to a triangle is that even if the incident rays are not parallel, parallel emitted light can still be obtained after reflection from a surface with a specific curvature. The collimation effect of the parabolic frustum 2 is far better than that of replacing it with a cone under the same conditions. Furthermore, according to the principle of total internal reflection, when light rays travel from a medium with a high refractive index to a medium with a low refractive index, if the angle of incidence is greater than the limiting angle, there will be no refraction of light rays, and all light rays will pass through in the form of reflection. By adjusting the curvature of the parabolic surface, it is also possible to achieve total internal reflection of most or even all of the light rays that fall on the parabolic surface, thereby achieving collimation. This improves both the light utilization rate and the collimation effect, which is one of the reasons why the parabolic frustum section 2 is superior to the cone.

[0028] The aforementioned parabolic frustum 2 has a first end and a second end facing away from each other (i.e., the small circular surface and the large circular surface used for truncation). The end face radius of the first end is smaller than that of the second end. The end face of the cylindrical part 1 is connected to the end face of the second end of the parabolic frustum 2. For the sake of simplifying the process and improving the light propagation effect, the end face of the cylindrical part 1 and the end face of the second end of the parabolic frustum 2 are chosen to have the same center and the same area. In the actual optical path, the first end of the parabolic frustum 2 is the incident surface of the light, and the other end face of the cylindrical part 1 away from the parabolic frustum 2 is the light emitting surface. The first end of the parabolic frustum 2 is recessed inward to form a cylindrical groove 2-1. The centerline of the cylindrical groove 2-1 coincides with the centerline of the parabolic frustum 2 and the axis of rotational symmetry of the cylindrical part 1. The radius of the bottom surface of the cylindrical groove 2-1 is less than or equal to the radius of the end face of the first end of the parabolic frustum 2. When the radius of the bottom surface of the cylindrical groove 2-1 is less than the radius of the end face of the first end of the parabolic frustum 2, the bottom circle of the cylindrical groove 2-1 and the end face circle of the first end of the parabolic frustum 2 form concentric circles. When the radius of the bottom surface of the cylindrical groove 2-1 is equal to the radius of the end face of the first end of the parabolic frustum 2, the bottom circle of the cylindrical groove 2-1 coincides with the end face circle of the first end.

[0029] The bottom of the cylindrical groove 2-1 bulges outward to form a convex lens 2-2. Rays that cannot be collimated at the center of the original inverted conical optical element can be converged by the convex lens 2-2 to obtain collimated light. For example... Figure 2 As shown, the incident light can be divided into two regions, A and B, according to the different collimation principles. The vertical surface b of the cylindrical groove 2-1 extends and divides the optical lens 101 into two parts. The region within the enclosure of the extended vertical surface b is region A. In this region, the incident light is converged by the lens surface a of the convex lens and becomes collimated light before exiting from the light-emitting surface. The region outside the enclosure of the extended vertical surface b is region B. In this region, the incident light is first refracted by the vertical surface b and then reflected by the parabolic surface c to become collimated light before exiting from the light-emitting surface. Due to the presence of the convex lens 2-2 structure in the central part, the optical lens 101 of this application can collimate the incident light in the central part. That is, compared with the inverted conical optical element, the optical lens 101 of this application can collimate a larger proportion of the incident light, has a wider range of applications, and has a better collimation effect.

[0030] The reflective layer L2 includes a reflective region 102 and an array of circular light-transmitting regions 103. The circular light-transmitting regions 103 and the optical lenses 101 are arranged identically and correspond one-to-one. The center O of the circular light-transmitting region 103 lies on the rotational symmetry axis of the optical lens 101. The circular light-transmitting regions 103 confine all light entering the collimating film 100 to a very small area, ensuring that all light enters through specific areas, namely the lens surface a and the cylindrical groove vertical surface b. This guarantees that the collimation effect applies to the vast majority, or even all, of the light entering the collimating film 100, thus improving the collimation effect. Light that does not enter the collimating film 100 is reflected by the reflective region 102. The reflected light undergoes secondary reflection through the hierarchical structure in the display module below the collimating film 100, or undergoes multiple reflections through the reflective region 102 and the hierarchical structure in the display module, ultimately returning to the circular light-transmitting region 103 and becoming light capable of entering the collimating film 100. This multiple reflection of light achieves optimal light efficiency.

[0031] In another typical embodiment of this application, such as Figure 1 As shown, the depth h of the cylindrical groove 2-1 is less than the height H of the parabolic frustum 2. If the depth h of the cylindrical groove 2-1 is greater than or equal to the height H of the parabolic frustum 2, some of the light rays incident through the vertical surface b of the cylindrical groove 2-1 will not reach the parabolic surface a, and thus will not be able to be collimated by reflection from the parabolic surface a, reducing the overall collimation effect of the optical lens 101.

[0032] In another typical embodiment of this application, the center O of the circular light-transmitting area coincides with the focal point F of the convex lens on the optical lens corresponding to the light-transmitting area. Utilizing the principle that light rays become parallel after passing through the focal point of the convex lens, and by limiting the circular light-transmitting area 103, and confining all incident light to the center O position, or placing the light source in the display module at the center O, the convex lens 2-2 can convert all incident light rays from lens surface a into parallel light, greatly improving the collimation effect of the collimating film 100.

[0033] In another typical embodiment of this application, the diameter of the circular light-transmitting area 103 is 5μm to 15μm. In order to ensure that all light rays incident on the optical lens 101 through the circular light-transmitting area 103 can be collimated, it is preferable that the diameter of the circular light-transmitting area 103 is less than or equal to the diameter of the bottom circle of the cylindrical groove 2-1, and more preferably that the diameter of the circular light-transmitting area 103 is less than the diameter of the bottom circle of the cylindrical groove 2-1.

[0034] In another typical embodiment of this application, the diameter of the bottom circle of the cylindrical groove 2-1 is 60μm to 80μm. The selection of the diameter of the bottom circle of the cylindrical groove 2-1 should consider the following factors: First, it must be greater than or equal to the diameter of the circular light-transmitting area 103. The specific reasons have been explained in detail in the relevant paragraphs above regarding the selection of the diameter of the circular light-transmitting area 103, and will not be repeated here. Second, the relationship between the diameter of the bottom circle of the cylindrical groove 2-1 and the diameters of the first and second end faces of the parabolic frustum 2; firstly, the diameter of the bottom circle of the cylindrical groove 2-1 should be less than or equal to the diameter of the first end face of the parabolic frustum 2, preferably equal, because if the diameter of the bottom circle of the cylindrical groove 2-1 is less than the diameter of the first end face of the parabolic frustum 2, then there will be a ring-shaped portion on the first end face. With the bottom circle diameter of the cylindrical groove 2-1 remaining unchanged, the presence of a ring-shaped portion means that more material needs to be used to manufacture the optical lens 101, resulting in higher costs. This means that light rays incident through the vertical surface b of the cylindrical groove 2-1 must travel a longer propagation path to reach the parabolic surface c, resulting in a slower overall light response of the display module and higher energy loss due to light propagation. Secondly, if the diameter of the bottom circle of the cylindrical groove 2-1 is too large, especially if it is too large relative to the diameter of the second end face of the parabolic frustum 2, under the same conditions, some light rays incident through the vertical surface b of the cylindrical groove 2-1 will not reach the parabolic surface c, but will directly reach the curved surface of the cylindrical part 1 and be reflected, thus failing to become collimated light and affecting the overall collimation effect of the collimating film 100.

[0035] In another typical embodiment of this application, the focal point f1 of the parabola coincides with the center O of the circular light-transmitting area. Although the incident light undergoes one refraction when it enters through the vertical surface b of the cylindrical groove 2-1, the light emitted from the focal point f1 of the parabola, i.e., the center O of the circular light-transmitting area, is not actually a light ray incident from the focal point with respect to the parabola c. However, by adjusting the refractive index of the optical lens to make it closer to the gas (air or vacuum) inside the cylindrical groove 2-1 and reducing the influence of the first refraction, it is possible to form approximately parallel light rays as much as possible.

[0036] In another typical embodiment of this application, the focal point f1 of the parabola coincides with the intersection point f2 of the backward extensions of the refracted rays obtained by the light emitted from the center O of the circular light-transmitting area and refracted by the curved surface of the cylindrical groove. In this case, for the parabola c, all the light rays incident through the cylindrical groove 2-1 and reaching the parabola c are light rays incident from the focal point of the parabola. After reflection by the parabola c, a set of parallel collimated rays can be obtained. At this time, the collimation effect of the optical lens 101 is optimal under the same conditions.

[0037] In another typical embodiment of this application, the parabolic curvature is 0.24 to 0.3. Within this range, the parabolic curvature maximizes the chance that most of the light rays incident on the vertical surface b of the cylindrical groove 2-1 and reaching the parabolic surface c undergo total internal reflection for collimation. Under the same conditions, a larger parabolic curvature results in a more constricted, parabolic frustum portion 2 from the first end to the second end. This leads to a smaller angle of incidence of the light rays incident on the vertical surface b of the cylindrical groove 2-1 relative to the parabolic surface c, resulting in less light satisfying the total internal reflection condition and less collimated light. This leads to poor overall collimation effect and low light utilization of the collimating film 100. Conversely, under the same conditions, if the parabolic curvature is too small, the path of the light rays incident on the vertical surface b of the cylindrical groove 2-1 to reach the parabolic surface c is longer, resulting in slow display module response speed and high light propagation loss, affecting the overall light conversion efficiency.

[0038] In another typical embodiment of this application, the refractive index of the optical lens 101 is 1.4 to 1.7. The optical lens 101 can be formed by UV curing of a UV adhesive, or by injection molding or hot pressing. Depending on the refractive index requirements, materials such as silicone, acrylic, polyurethane, polyimide, epoxy resin, and polyester can be selected. The refractive index requirements can also be met by adding different functional additives to the UV adhesive or adjusting the proportions of different components. Other conventional methods can be used as long as they can meet the specific refractive index requirements. Those skilled in the art can choose according to the performance requirements of the alignment film, and will not be elaborated further here.

[0039] In another typical embodiment of this application, the reflectivity of the reflective region 102 is 80%–95%, and the transmittance of the circular light-transmitting region 103 is 90%–100%. The reflectivity can be adjusted by adding reflective fillers such as titanium oxide, barium sulfate, zinc barium white, calcium carbonate, etc., to the raw material of the reflective region 102. Alternatively, a high-reflectivity coating can be applied to the surface of the reflective region 102 away from the optical lens 100, or a metal or metal oxide plating layer such as a silver plating layer can be added. Alternatively, the reflective region 102 itself can be a metal or metal oxide layer. Other conventional methods are acceptable as long as the reflective region meets the usage requirements. The circular light-transmitting region 103 can be formed by curing a high-transmittance material, or it can be multiple holes, i.e., by regularly perforating the thin-film reflective layer L2 to form an array of holes corresponding one-to-one with the multiple optical lenses 101. In this case, the transmittance of the circular light-transmitting region 103 is 100%.

[0040] In another typical embodiment of this application, the surface of the reflective region 102, away from the optical lens 101, is provided with microstructures capable of converging reflected light rays reflected through this surface. These microstructures can include irregular, uneven structures at the micrometer scale or even smaller, such as protrusions, depressions, or regular cubic grooves, prisms, pyramids, cylinders, cones, and other bodies of revolution. Those skilled in the art can choose according to their requirements for reflectivity and light-concentrating performance, which will not be elaborated further here.

[0041] In another typical embodiment of this application, a display module is provided. The display module includes the collimation film described above. The aforementioned display module can refer to any functional assembly with display capabilities, such as mobile phone screens, computer screens, television screens, optical glass curtain walls, vehicle dashboards, commercial display screens, scrolling text screens, etc.

[0042] The beneficial effects of this application will be further illustrated below with reference to embodiments and comparative examples.

[0043] Example 1

[0044] Collimation membrane structure such as Figure 5 As shown, the device includes a reflective layer and multiple optical lenses arranged in an array on the reflective layer. Each optical lens comprises a cylindrical portion and a quasi-parabolic frustum portion. The quasi-parabolic frustum portion has a parabolic curvature in the radial direction and a circular arc structure in the circumferential direction. The quasi-parabolic frustum portion has a first end and a second end facing away from each other. The radius of the first end's face is smaller than the radius of the second end's face. The end face of the cylindrical portion is connected to the end face of the second end of the quasi-parabolic frustum portion. The first end is recessed inward to form a cylindrical groove. The centerline of the cylindrical groove coincides with the centerline of the quasi-parabolic frustum portion, and the radius of the bottom surface of the cylindrical groove is equal to the radius of the first end's face of the quasi-parabolic frustum portion. The bottom of the cylindrical groove bulges outward to form a convex lens. The reflective layer includes a reflective area and an array of circular light-transmitting areas. The circular light-transmitting areas are arranged identically and correspond one-to-one with the optical lenses.

[0045] The optical lens has a refractive index of 1.5 and a total height of 150 μm. The cylindrical recess has a base diameter of 70 μm and a height h of 64.4 μm. The parabolic surface is obtained by rotating a parabola whose vertex is 19.5 μm below the center O of the circular light-transmitting area and whose focal point is at O, around an axis passing through O and perpendicular to the base of the cylindrical portion. The parabola has a curvature of 0.26. The convex lens has a diameter of 70 μm, a maximum thickness of 18.4 μm, and its focal point F coincides with the center O. The circular light-transmitting area is a 10 μm diameter aperture. The diameter of the cylindrical base is 200 μm.

[0046] Example 2

[0047] Compared with Example 1, a microstructure with a light-focusing effect is added to the surface of the reflective area away from the optical lens. The microstructure is an inverted quadrangular pyramid structure distributed in a matrix. Everything else is the same.

[0048] Example 3

[0049] Compared to Example 1, the parabolic surface is obtained by rotating a parabola whose vertex is 19.5 μm below the center O of the circular light-transmitting area and whose focal point is 10 μm above the center O around the axis of a line passing through the center O and perpendicular to the bottom surface of the cylindrical part. The curvature of the parabola is 0.275 (the focal point of the parabola is not at the center O, and the focal point of the parabola coincides with the intersection of the backward extension of the refracted light ray obtained by the light emitted from the center O of the circular light-transmitting area and refracted by the curved surface of the cylindrical groove). All other aspects are the same.

[0050] Example 4

[0051] Compared to Example 1, the curvature of the parabola is 0.24, and all other parameters are the same.

[0052] Example 5

[0053] Compared to Example 1, the curvature of the parabola is 0.27, and all other parameters are the same.

[0054] Example 6

[0055] Compared to Example 1, the curvature of the parabola is 0.3, and all other parameters are the same.

[0056] Example 7

[0057] Compared to Example 1, the diameter of the circular light-transmitting area, i.e. the hole, is 5 μm, while all other aspects remain the same.

[0058] Example 8

[0059] Compared to Example 1, the diameter of the circular light-transmitting area, i.e. the hole, is 15 μm, while all other aspects remain the same.

[0060] Example 9

[0061] Compared to Example 1, the refractive index of the optical lens material is 1.4, and all other parameters are the same.

[0062] Example 10

[0063] Compared to Example 1, the refractive index of the optical lens material is 1.7, and all other parameters are the same.

[0064] Comparative Example 1

[0065] Compared with Example 1, Comparative Example 1 contains only the reflective layer L2, and everything else is the same.

[0066] Comparative Example 2

[0067] Compared with Example 1, Comparative Example 2 does not contain a convex lens structure, the bottom surface of the cylindrical groove is not raised, and everything else is the same.

[0068] Comparative Example 3

[0069] Compared with Example 1, Comparative Example 3 uses a frustum (with an isosceles trapezoidal cross-section, the upper base having the same diameter as the second end face in Comparative Example 1, and the lower base having the same diameter as the first end face) to replace the parabolic frustum portion, while all other aspects remain the same.

[0070] Comparative Example 4

[0071] Compared with Example 1, Comparative Example 4 does not contain reflective layer L2, but is otherwise the same.

[0072] The following are the performance testing methods for the examples and comparative examples:

[0073] [Illuminance Test]

[0074] Examples 1-10 and Comparative Examples 1-4 were tested using an LTS-232H illuminometer. Each sample was tested 5 times, and the average value of the 5 tests was taken as the final test result.

[0075] [Relative Collimation Test]

[0076] At a distance of 1m above the collimation film, the light intensity value was measured using an LTS-232H illuminometer at a viewing angle of 0.1 degrees. The larger the value, the higher the collimation.

[0077] Table 1 shows the performance evaluation of Examples 1-10 and Comparative Examples 1-4.

[0078]

[0079] As shown in the table above, the collimation performance of Examples 1-10 is significantly improved compared to Comparative Examples 1-4, and Example 3 has the best collimation effect. Specifically, because Embodiment 2 adds a light-focusing microstructure to the surface of the reflection area away from the optical lens compared to Embodiment 1, Embodiment 2 has higher illuminance. Among Embodiments 1-10, only the parabolic surface of Embodiment 3 satisfies the condition that "the focal point of the parabola coincides with the intersection of the backward extension of the refracted ray obtained after the light emitted from the center O of the circular light-transmitting area and refracted by the curved surface of the cylindrical groove." According to the principle that "the incident light ray originating from the focal point is reflected by the parabolic surface, and the reflected ray is parallel (coinciding) with the axis of symmetry of the parabola," only Embodiment 3 obtains completely parallel outgoing rays after refraction by the parabolic surface, while the other embodiments only improve the collimation effect to a certain extent. As can be seen from Embodiments 1, 7, and 8, when the diameter of the circular light-transmitting area increases, more light rays that do not pass through the center O of the circular light-transmitting area are incident. These rays are neither incident from the focal point of the convex lens on the optical lens, nor from the focal point of the parabola, nor from the intersection of the backward extension of the refracted ray obtained after refraction by the curved surface of the cylindrical groove and the focal point of the parabola. For light rays that coincide at points, the degree of collimation is low. Therefore, as the diameter of the circular light-transmitting area increases, both illuminance and relative collimation decrease. Comparative Example 1 does not contain an optical lens and only has a reflective layer, so it has virtually no collimation effect and the overall illuminance is low. Comparative Example 2 does not contain a convex lens structure, so some incident light that fails to reach the cylindrical groove surface cannot be collimated, resulting in a poor overall collimation effect. Comparative Example 3 uses a frustum instead of a parabolic frustum. The very small portion of light rays refracted by the cylindrical groove surface and reaching the frustum surface can collimate under certain angle conditions. Collimated light can be obtained through refraction, but most light rays cannot be collimated after refraction through the frustum surface; Comparative Example 4 does not have a reflective layer, and there is no multiple reflection and focusing effect of the reflective area and the circular light-transmitting area on the reflective layer, nor the effect of selecting the incident position of the light. Only a very small portion of the light rays directly incident on the optical lens meet the conditions of being incident from the focal point of the convex lens on the optical lens, the focal point of the parabola, or the intersection of the backward extensions of the refracted light rays obtained after refraction by the curved surface of the cylindrical groove with the focal point of the parabola. The overall illuminance and collimation are low.

[0080] In summary, the technical solution of this invention can achieve excellent collimation effect, improve light utilization, and obtain good visual effect. The collimation film of this invention has broad application prospects.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A collimating membrane, characterized in that, The collimating film includes a reflective layer (L2) and a plurality of optical lenses (101) arranged in an array on the reflective layer; The optical lens (101) includes a cylindrical part (1) and a parabolic frustum part (2). The curved surface (c) of the parabolic frustum part (2) has a parabolic curvature in the radial direction and a circular arc structure in the circumferential direction. The parabolic frustum portion (2) has a first end and a second end facing away from each other. The end face radius of the first end is smaller than that of the second end. The end face of the cylindrical portion (1) is connected to the end face of the second end of the parabolic frustum portion (2). The first end is recessed inward to form a cylindrical groove (2-1), the center line of the cylindrical groove (2-1) coincides with the center line of the parabolic frustum (2), the bottom radius of the cylindrical groove (2-1) is less than or equal to the end radius of the first end of the parabolic frustum (2), and the bottom of the cylindrical groove (2-1) protrudes outward to form a convex lens (2-2); The reflective layer (L2) includes a reflective area (102) and an array of circular light-transmitting areas (103). The circular light-transmitting areas (103) and the optical lenses (101) are arranged in the same order and correspond one-to-one.

2. The collimating membrane according to claim 1, characterized in that, The depth h of the cylindrical groove (2-1) is less than the height H of the parabolic frustum portion (2).

3. The collimating membrane according to claim 1, characterized in that, The center O of the circular light-transmitting area (103) coincides with the focal point F of the convex lens (2-2) on the optical lens (101) corresponding to the light-transmitting area.

4. The collimating membrane according to any one of claims 1-3, characterized in that, The focal point f1 of the parabola coincides with the center O of the circular light-transmitting area (103).

5. The collimating membrane according to any one of claims 1-3, characterized in that, The focal point f1 of the parabola coincides with the intersection point f2 of the backward extension of the refracted ray obtained by the light emitted from the center O of the circular light-transmitting area (103) and refracted by the curved surface of the cylindrical groove (2-1).

6. The collimating membrane according to claim 1, characterized in that, The curvature of the parabola is 0.24 to 0.

3.

7. The collimating membrane according to claim 1, characterized in that, The refractive index of the optical lens (101) is 1.4 to 1.

7.

8. The collimating membrane according to claim 1 or 7, characterized in that, The reflectivity of the reflective area (102) is 80% to 95%, and the transmittance of the circular light-transmitting area (103) is 90% to 100%.

9. The collimating membrane according to claim 1, characterized in that, The surface of the reflective region (102) away from the optical lens (101) is provided with microstructures that can concentrate reflected light rays reflected through the surface.

10. A display module, characterized in that, The display module includes the collimation film according to any one of claims 1-9.

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