Double-layer aspheric micro-lens array structure, lighting device and preparation method of double-layer aspheric micro-lens array structure

Abstract

The invention discloses a double-layer aspheric micro-lens array structure, a lighting device and a preparation method of the double-layer aspheric micro-lens array structure, the micro-lens array structure comprises a transparent substrate, a first aspheric micro-lens array and a second aspheric micro-lens array which are sequentially arranged, the transparent substrate is transparent and flat, the first aspheric micro-lens array is arranged on the transparent substrate, and the second aspheric micro-lens array is arranged on the second aspheric micro-lens array. A plurality of first concave parts arranged in an array are arranged on the surface of one side, far away from the transparent substrate, of the first aspheric micro lens array; a convex part matched with the first concave part of the first aspheric microlens array is arranged on one surface of the second aspheric microlens array, a plurality of second concave parts arranged in an array are arranged on the other opposite surface of the second aspheric microlens array, the caliber of the second concave parts is smaller than that of the first concave parts, and the bottom surfaces of the second concave parts and the first concave parts are aspheric surfaces; the second concave parts and the first concave parts are in one-to-one correspondence, and the centers of the second concave parts and the first concave parts are aligned; the refractive index of the first aspheric microlens array is smaller than that of the second aspheric microlens array.

Description

Technical Field

[0001] The present invention relates to the field of optical precision manufacturing for auxiliary LED display, and in particular to a double-layer aspherical microlens array structure, an illumination device and a preparation method thereof. Background Art

[0002] Optical lenses are widely used in the fields of optical engineering, LED display technology and optical precision manufacturing. In particular, Micro-LED, as a new display technology, has received widespread attention due to its advantages such as high brightness, high contrast and long life. Micro-LED is composed of tiny light-emitting diodes, and the size of each LED is in the micron level. Due to its small size, the light output angle of Micro-LED is large, and the light will scatter in all directions when it is emitted, resulting in low light output efficiency and uneven light spot, which limits its scope of application. Therefore, how to collimate the light emitted by Micro-LED and improve the accuracy of its light output angle has become an important issue in this field.

[0003] The existing solution mainly uses lenses to collimate the light emitted by Micro-LEDs. Covering the surface of Micro-LEDs with a microlens array, the light emitted by the LED is focused in a specific direction through the refraction of the microlens, thereby improving the collimation of the light. This method can effectively improve the uniformity of the light spot and the light output efficiency. For example, a single-layer lens or an aspherical lens can be used to converge and collimate the light, but there are defects such as large aberrations and limited collimation effects.

[0004] Some other collimation methods, such as optical phase arrays, nano-optical structures, etc., require high-precision manufacturing processes, which increases the difficulty and cost of manufacturing. Solving the problem of Micro-LED light collimation is a multifaceted challenge that requires optimization in many aspects such as materials, structural design, and manufacturing processes. Although some effective solutions have been proposed, there are still problems such as manufacturing complexity, light efficiency loss, spot uniformity, and high cost. The future research direction should be to further optimize these technologies, reduce manufacturing costs, improve light efficiency and spot uniformity, and thus promote the widespread application of Micro-LED display technology.

[0005] The disclosure of the above background technology content is only used to assist in understanding the concept and technical solution of the present application. It does not necessarily belong to the prior art of the present application, nor does it necessarily provide technical guidance. In the absence of clear evidence that the above content has been disclosed before the filing date of the present application, the above background technology should not be used to evaluate the novelty and creativity of the present application. Summary of the invention

[0006] The purpose of the present invention is to provide a double-layer aspheric microlens array structure for highly collimated light-emitting Micro-LEDs, so that the LED light beam first passes through an aspheric lens with a lower refractive index and then passes through an aspheric lens with a higher refractive index.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows: A double-layer aspheric microlens array structure, suitable for Micro-LED, the microlens array structure comprising a transparent substrate, a first aspheric microlens array and a second aspheric microlens array arranged in sequence, wherein the transparent substrate is transparent and flat, the first aspheric microlens array is arranged on the transparent substrate, and a surface of the first aspheric microlens array on one side away from the transparent substrate is provided with a plurality of first concave portions arranged in an array; A convex portion matched with the first concave portion of the first aspheric microlens array is provided on one surface of the second aspheric microlens array, and a plurality of second concave portions arranged in an array are provided on the other opposite surface, wherein the aperture of the second concave portion is smaller than the aperture of the first concave portion, and the bottom surfaces of the second concave portion and the first concave portion are both aspheric surfaces; The second concave portion corresponds to the first concave portion one by one, and the centers of the two are aligned; The refractive index of the first aspherical microlens array is smaller than the refractive index of the second aspherical microlens array.

[0008] Further, based on any one of the technical solutions or a combination of multiple technical solutions mentioned above, the radius of curvature of the center of the first concave portion is smaller than the radius of curvature of the center of the second concave portion.

[0009] Further, based on any one of the above technical solutions or a combination of multiple technical solutions, the material of the second aspherical microlens array is uniform, and its refractive index ranges from 1.6 to 1.8; The material of the first aspherical microlens array is uniform, and its refractive index ranges from 1.3 to 1.5; And / or, the material of the second aspherical microlens array and the first aspherical microlens array is photoresist.

[0010] Further, based on any one of the above technical solutions or a combination of multiple technical solutions, the diameter of the first concave portion is between 20 and 50 μm, and the diameter of the second concave portion is between 5 and 20 μm; And / or, a distance from a center of the second concave portion to a center of a corresponding first concave portion is greater than a thickness of the first aspherical microlens array.

[0011] According to another aspect of the present invention, the present invention provides a lighting device, comprising a plurality of Micro-LEDs and the double-layer aspherical microlens array structure as described above, wherein the Micro-LEDs are respectively arranged in each second concave portion of the microlens array structure, and the light-emitting surface of the Micro-LED faces the center of the second concave portion.

[0012] According to another aspect of the present invention, the present invention provides a method for preparing a double-layer aspherical microlens array structure, comprising the following steps: Coating a photoresist having a first refractive index on a planar transparent substrate, and curing the substrate to obtain a low-refractive-index photoresist layer having a uniform thickness; Glue is dripped on the low-refractive-index photoresist layer to obtain a first glue layer, and a first template is transferred to the first glue layer by nanoimprinting technology, wherein a first aspheric protrusion array is provided on the first template, so that a plurality of first concave portions arranged in an array are formed on the first glue layer, wherein the first glue layer has the first refractive index; Separating the first adhesive layer from the first template, coating the transferred first adhesive layer with a photoresist having a second refractive index, and curing the photoresist to obtain a high-refractive-index photoresist layer, wherein the second refractive index is greater than the first refractive index; A second glue layer is obtained by dripping glue on the high-refractive-index photoresist layer, and a second template is transferred to the second glue layer by nanoimprinting technology, wherein a second aspheric protrusion array is provided on the second template, so that a plurality of second concave portions arranged in an array are formed on the second glue layer; the second concave portions correspond to the first concave portions one by one, and the centers of the two are aligned, the aperture of the second concave portions is smaller than the aperture of the first concave portions, and the bottom surfaces of the second concave portions and the first concave portions are both aspheric; wherein the second glue layer has the second refractive index; The second adhesive layer is separated from the second template to obtain a double-layer aspherical microlens array structure.

[0013] Further, based on any one of the above-mentioned technical solutions or a combination of multiple technical solutions, before transferring the second template to the second adhesive layer, the method further includes: Based on the target set on the second template, the imprint position of the second template is determined.

[0014] Further, based on any one of the above-mentioned technical solutions or a combination of multiple technical solutions, the first template is made of UV glue material, which is obtained by the following method: Manufacturing a first master of a first aspheric microlens array by laser grayscale direct writing lithography, wherein a first aspheric protrusion array is provided on the first master, and the first master is made of photoresist material; Transferring the first master to obtain a first sample by nanoimprinting technology, so that the imprinted surface of the first sample forms a first aspheric concave array that matches the first aspheric convex array; The first template is obtained by transferring the first sample through nanoimprinting technology, so that the first aspheric convex array that is compatible with the first aspheric concave array is formed on the first template.

[0015] Further, based on any one of the above-mentioned technical solutions or a combination of multiple technical solutions, the second template is made of UV glue material, which is obtained by the following method: Manufacturing a second master of a second aspherical microlens array by laser grayscale direct writing lithography, wherein a second aspherical protrusion array is provided on the second master, and the second master is made of photoresist material; Transferring the second master plate to obtain a second template by nanoimprinting technology, so that the imprinted surface of the second template forms a second aspheric concave array that matches the second aspheric convex array; The second template is obtained by transferring the second sample through nanoimprinting technology, so that the second aspheric convex array that is compatible with the second aspheric concave array is formed on the second template.

[0016] Further, based on any one of the above technical solutions or a combination of multiple technical solutions, a first target is further provided on the first master, and the first target is a concave structure or a convex structure; The second master is also provided with a second target, and the second target is a concave structure or a convex structure; The first master and the second master satisfy that: when the first target is aligned with the second target, the first aspheric convex array on the first master is aligned with the second aspheric convex array on the second master.

[0017] Further, based on any one of the above technical solutions or a combination of multiple technical solutions, the convex surface shapes of the first aspheric convex array on the first master and the second aspheric convex array on the second master are characterized by an even-order high-order aspheric formula; The first aspheric convex array and the second aspheric convex array are arranged in a circular pattern, an annular pattern, a polygonal pattern or a cartoon character shape pattern; The outer diameter of the protrusions in the first aspheric protrusion array is greater than the outer diameter of the protrusions in the second aspheric protrusion array; The protrusion height of the protrusions in the first aspheric protrusion array is greater than the protrusion height of the protrusions in the second aspheric protrusion array.

[0018] According to another aspect of the present invention, the present invention provides a method for preparing a lighting device, comprising the following steps: The double-layer aspherical microlens array structure is obtained by the preparation method as described above; A light board is prepared, wherein the light board is made of an opaque material and is provided with a Micro-LED array, wherein the Micro-LED array is adapted to the double-layer aspheric microlens array structure, including: each Micro-LED is respectively arranged in each second concave portion formed on the second adhesive layer of the double-layer aspheric microlens array structure, and the light-emitting surface of the Micro-LED faces the center of the second concave portion.

[0019] The beneficial effects brought by the technical solution provided by the present invention are as follows: a. Use a double-layer lens array to provide a light-guiding path for Micro-LEDs, solving the problems of poor collimation and low luminous efficiency caused by single-layer lens arrays and other means; b. Using laser grayscale direct writing lithography to manufacture the master, ensuring a good high-order aspheric surface shape at the micro-nano scale, solving the problems of low component precision and no allowable error and high manufacturing cost at the micro-nano scale; c. The double-layer aspherical microlens array has a simple structure and a simple preparation method, which can effectively improve the light collimation of Micro-LED. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of the structure of a highly collimated light-emitting Micro-LED lighting device with a double-layer aspherical microlens array structure provided by an exemplary embodiment of the present invention; Figure 2 A schematic structural diagram of a first master plate / first template provided for an exemplary embodiment of the present invention; Figure 3 A schematic structural diagram of a second master plate / second template provided for an exemplary embodiment of the present invention; Figure 4 A schematic diagram of alignment of a first master and a second master provided for an exemplary embodiment of the present invention; Figure 5 A schematic diagram of a method for preparing a first master by laser grayscale direct writing lithography provided as an exemplary embodiment of the present invention; Figure 6A schematic diagram of a method for preparing a second master by laser grayscale direct writing lithography is provided as an exemplary embodiment of the present invention; Figure 7 A schematic diagram of a preparation process of a first master plate for primary transfer to obtain a first sample plate and a second transfer to obtain a first template provided by an exemplary embodiment of the present invention; Figure 8 A schematic diagram of a preparation process of obtaining a second template by primary transfer of a second master and obtaining a second template by secondary transfer provided as an exemplary embodiment of the present invention; Fig. 9 A schematic diagram of a preparation process of a double-layer aspherical microlens array structure for a highly collimated light emitting Micro-LED provided by an exemplary embodiment of the present invention; Fig.10 A flow chart of a method for preparing a double-layer aspherical microlens array structure is provided for an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0023] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, device, product or equipment that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0024] When the light emitted by many light-emitting chips needs to be collimated, most conventional methods use a single-layer microlens array to refract and collimate the light emitted by the light-emitting chip at the critical surface to achieve the collimation effect. This method has certain risks, and the collimation effect is affected by the lens processing accuracy and the large alignment error with the light-emitting chip. Other phase control methods, such as metasurface collimation, have problems such as high processing costs, which have a greater impact on mass production.

[0025] In one embodiment of the present invention, a double-layer aspherical microlens array structure is provided, which is suitable for Micro-LED, such as Figure 1 As shown, the microlens array structure includes a transparent substrate 300, a first aspheric microlens array 200, and a second aspheric microlens array 100 which are sequentially arranged, wherein the transparent substrate 300 is transparent and flat, the first aspheric microlens array 200 is arranged on the transparent substrate 300, and a surface of the first aspheric microlens array 200 which is away from the transparent substrate 300 is provided with a plurality of first concave portions 210 arranged in an array; A convex portion 110 matching the first concave portion 210 of the first aspheric microlens array 200 is provided on one surface of the second aspheric microlens array 100, and a plurality of second concave portions 120 arranged in an array are provided on the other opposite surface. The aperture of the second concave portion 120 is smaller than the aperture of the first concave portion 210, and the bottom surfaces of the second concave portion 120 and the first concave portion 210 are both aspheric surfaces. In one embodiment, the aperture of the first concave portion 210 is between 20 and 50 μm, for example, 30 μm; the aperture of the second concave portion 120 is between 5 and 20 μm, for example, 8 μm; Figure 1 As shown, the curvature radius of the center of the first concave portion 210 is smaller than the curvature radius of the center of the second concave portion 120 ; the distance from the center of the second concave portion 120 to the center of the corresponding first concave portion 210 is greater than the thickness of the first aspherical microlens array 200 .

[0026] The second concave portion 120 corresponds to the first concave portion 210 one by one, and the centers of the two are aligned; the double-layer aspherical microlens array structure of this embodiment can face the highly collimated light emitting Micro-LED, such as Figure 1 As shown, Micro-LED 400 is respectively arranged in each second concave portion 120 of the microlens array structure. Specifically, Micro-LED 400 can be distributed in an array on an opaque and light-proof (or light transmittance is less than 20%) lamp board 410. The lamp board 410 is covered on a double-layer aspherical microlens array structure, and the light-emitting surface of Micro-LED 400 faces the center of the second concave portion 120.

[0027] The refractive index of the first aspheric microlens array 200 is smaller than the refractive index of the second aspheric microlens array 100: the first aspheric microlens array 200 and the second aspheric microlens array 100 are both made of uniform material, and the refractive index of the first aspheric microlens array 200 ranges from 1.3 to 1.5, for example, it can be selected as 1.45; the refractive index of the second aspheric microlens array 100 ranges from 1.6 to 1.8, for example, it can be selected as 1.7.

[0028] The material of the second aspheric microlens array 100 and the first aspheric microlens array 200 is photoresist. The photoresist used in the two-layer aspheric microlens array adopted by the present invention has a refractive index difference. The aperture and sagittal height of the lenses of the upper and lower arrays are different, and the thickness of the photoresist used in each layer of the aspheric microlens array is greater than the sagittal height of the lens to ensure smooth emission of light.

[0029] In one embodiment of the present invention, a method for preparing a double-layer aspherical microlens array structure is provided, such as Fig. 9 and Fig.10 As shown, the preparation method comprises the following steps: S100: coating a photoresist having a first refractive index on a planar transparent substrate 300, and curing the photoresist to obtain a low-refractive-index photoresist layer 810 having a uniform thickness; S200: Glue is dripped on the low-refractive-index photoresist layer 810 to obtain a first glue layer, and a first template 710 (not shown) is formed by nanoimprinting technology. Fig. 9 ) is transferred to the first adhesive layer, see Figure 2 The first template 710 is provided with a first aspherical protrusion array. The first adhesive layer (not shown) is planar before embossing. After embossing, the first adhesive layer is formed into a Fig. 9 The plurality of first concave portions 210 are arranged in an array, wherein the first glue layer is made of a photoresist having a first refractive index; S300: separating the first adhesive layer from the first template 710, coating a photoresist having a second refractive index on the transferred first adhesive layer, and curing the photoresist to obtain a high-refractive-index photoresist layer 820, wherein the second refractive index is greater than the first refractive index; S400: dripping glue on the high refractive index photoresist layer 820 to obtain a second glue layer, the second glue layer has a second refractive index, and forming a second template 720 (not in Fig. 9 ) is transferred to the second adhesive layer, see Figure 3 The second template 720 is provided with a second aspherical protrusion array. The second adhesive layer (not shown) is planar before embossing. After embossing, the second adhesive layer is formed into a Fig. 9 The plurality of second concave portions 120 are arranged in an array as shown; the second concave portions 120 correspond to the first concave portions 210 one by one, and the centers of the two are aligned, the aperture of the second concave portion 120 is smaller than the aperture of the first concave portion 210, and the bottom surfaces of the second concave portion 120 and the first concave portion 210 are both aspherical surfaces; Finally, the second adhesive layer is separated from the second template 720 to obtain a double-layer aspherical microlens array structure.

[0030] from Fig. 9 It can be seen that, or compared Figure 2 and Figure 3, the protrusion height of the protrusions in the first aspheric protrusion array is greater than the protrusion height of the protrusions in the second aspheric protrusion array.

[0031] When transferring the second template 720 to the second adhesive layer, in order to achieve alignment between the center of the second concave portion 120 and the first concave portion 210 after transfer, requirements are put forward for the imprinting position of the second template 720; in this embodiment, alignment targets are provided on the first template 710 and the second template 720, and the imprinting position of the second template 720 is determined based on the alignment targets.

[0032] In one embodiment of the present invention, the first template 710 and the second template 720 are made of UV glue. Figure 7 Shown and Figure 8 As shown, the first template 710 and the second template 720 are obtained in the following manner: Step one: Make a master.

[0033] like Figure 5 As shown, the first master plate 510 of the first aspherical microlens array is manufactured by laser grayscale direct writing lithography. The first master plate 510 is made of photoresist material, such as Figure 2 As shown, a first aspherical protrusion array 512 is provided on the first master plate 510; like Figure 6 As shown, the second master plate 520 of the second aspherical microlens array is manufactured by laser grayscale direct writing lithography, and the second master plate 520 is made of photoresist material, such as Figure 3 As shown, a second aspherical protrusion array 522 is provided on the second master 520; The first master plate 510 is also provided with a first target, which is a concave structure or a convex structure. In one embodiment, the first target is divided into a first virtual target 5142; The second master plate 520 is also provided with a second target, which is a concave structure or a convex structure. In one embodiment, the second target is divided into a second real target 5241 and a second virtual target 5242; Figure 4 It is not intended to illustrate a specific structure, but to abstractly illustrate that the first master 510 and the second master 520 are aligned, including: the first real target 5141 is aligned with the second virtual target 5242, and when the first virtual target 5142 is aligned with the second real target 5241, the first aspheric convex array 512 on the first master 510 is aligned with the second aspheric convex array 522 on the second master 520: Figure 4 The center of the aspheric protrusion in the first aspheric protrusion array 512 coincides with the center of the corresponding aspheric protrusion in the second aspheric protrusion array 522, that is, the circles of the projections of the aspheric protrusions of the two form concentric circles.

[0034] like Figure 4As shown, the first aspheric convex array and the second aspheric convex array are arranged in a circular arrangement, an annular arrangement, a polygonal arrangement or a cartoon character shape arrangement. Figure 2 and Figure 3 For example, the first aspheric protrusion array and the second aspheric protrusion are arranged in a square; the outer diameter of the protrusions in the first aspheric protrusion array is greater than the outer diameter of the protrusions in the second aspheric protrusion array.

[0035] Step 2: Prepare the sample.

[0036] See also Figure 7 , transferring the first master 510 to obtain a first sample 610 by nanoimprinting technology, so that the imprinted surface of the first sample 610 forms a first aspheric concave array that matches the first aspheric convex array; See also Figure 8 The second master plate 520 is transferred by nanoimprinting technology to obtain a second template 620, so that the imprinted surface of the second template 620 forms a second aspheric concave array that is compatible with the second aspheric convex array 522.

[0037] Step 3: Prepare the template.

[0038] See also Figure 7 The first template 710 is obtained by transferring the first sample 610 through nanoimprinting technology, so that a first aspheric convex array that matches the first aspheric concave array is formed on the first template 710, that is, the lens surface shape of the first template 710 is consistent with that of the first master 510.

[0039] See also Figure 8 The second template 620 is transferred by nanoimprinting technology to obtain a second template 720, so that a second aspheric convex array that matches the second aspheric concave array is formed on the second template 720, that is, the lens surface shape of the second template 720 is consistent with that of the second master 520.

[0040] Since the first template 710 and the second template 720 are made of UV glue material, on the one hand, the bonding between the two aspherical microlens layers is achieved, and on the other hand, the optical element prepared by the UV glue material has better optical performance.

[0041] In this embodiment, the convex surface types of the first aspheric convex array on the first master 510 and the second aspheric convex array on the second master 520 are characterized by an even-order high-order aspheric surface formula: ;in, c =1 / r , r is the radius of curvature of the aspheric vertex, k is the cone coefficient, α 1. α 2.α 3. α 4 is the coefficient corresponding to the 2nd, 4th, 6th and 8th order terms of the even-order aspheric surface. The higher the order, the finer the corresponding lens surface shape and the higher the resolution. The coefficient of the aspheric surface formula is adjusted to achieve the desired effect. The coefficient of the aspheric surface shape processed in this embodiment reaches 8th order.

[0042] The preparation method of the double-layer aspheric microlens array structure provided in this embodiment and the double-layer aspheric microlens array structure provided in the above embodiment belong to the same inventive concept, and the other embodiments are incorporated into this embodiment by mutual reference to complement each other and will not be repeated here.

[0043] In another embodiment of the present invention, a method for preparing a lighting device is provided, comprising the following steps: A double-layer aspherical microlens array structure is obtained by the above preparation method; A light board is prepared, which is made of an opaque material. A Micro-LED array is arranged on the light board. The Micro-LED array is adapted to the double-layer aspherical microlens array structure, including: each Micro-LED is respectively arranged in each second concave portion formed on the second adhesive layer of the double-layer aspherical microlens array structure, and the light-emitting surface of the Micro-LED faces the center of the second concave portion.

[0044] Compared with other collimation methods, the double-layer aspheric microlens array structure provided by the present invention can better control the propagation direction of light and the divergence angle of the light beam, thereby improving the quality and brightness of the light beam. The lenses of the first aspheric microlens array and the lenses of the second aspheric microlens array work together to effectively collect and collimate the light emitted by Micro-LED, reduce light loss, and improve light extraction efficiency. This structure can be applied to occasions that require high-brightness, high-directivity light sources, such as projectors, laser displays, and LED lighting. By selecting different lens materials and adjusting lens parameters (such as refractive index, thickness, aperture, etc.), the optical path design can be optimized to meet different application requirements, with great flexibility.

[0045] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0046] The above is only a specific implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A double-layer aspherical microlens array structure, characterized in that: Applicable to Micro-LEDs, the microlens array structure comprising a transparent substrate (300), a first aspheric microlens array (200), and a second aspheric microlens array (100) which are arranged in sequence, wherein the transparent substrate (300) is transparent and flat, the first aspheric microlens array (200) is arranged on the transparent substrate (300), and a plurality of first concave portions (210) arranged in an array are provided on a surface of the first aspheric microlens array (200) on a side away from the transparent substrate (300); One surface of the second aspheric microlens array (100) is provided with a convex portion (110) adapted to the first concave portion (210) of the first aspheric microlens array (200), and the other opposite surface is provided with a plurality of second concave portions (120) arranged in an array, the aperture of the second concave portion (120) is smaller than the aperture of the first concave portion (210), and the bottom surfaces of the second concave portion (120) and the first concave portion (210) are both aspheric surfaces; The second concave portion (120) corresponds to the first concave portion (210) one-to-one, and the centers of the two are aligned; The refractive index of the first aspherical microlens array (200) is smaller than the refractive index of the second aspherical microlens array (100).

2. The double-layer aspherical microlens array structure according to claim 1, characterized in that: The radius of curvature of the center of the first concave portion (210) is smaller than the radius of curvature of the center of the second concave portion (120).

3. The double-layer aspheric microlens array structure according to claim 1, characterized in that: The material of the second aspherical microlens array (100) is uniform, and its refractive index ranges from 1.6 to 1.8; The material of the first aspherical microlens array (200) is uniform, and its refractive index ranges from 1.3 to 1.5; And / or, the material of the second aspherical microlens array (100) and the first aspherical microlens array (200) is photoresist.

4. The double-layer aspheric microlens array structure according to claim 1, characterized in that: The caliber of the first concave portion (210) is between 20 and 50 μm, and the caliber of the second concave portion (120) is between 5 and 20 μm; And / or, the distance from the center of the second concave portion (120) to the center of the corresponding first concave portion (210) is greater than the thickness of the first aspherical microlens array (200).

5. A lighting device, characterized in that: The invention comprises a plurality of Micro-LEDs (400) and a double-layer aspherical microlens array structure according to any one of claims 1 to 4, wherein the Micro-LEDs (400) are respectively arranged in respective second concave portions (120) of the microlens array structure, and the light-emitting surfaces of the Micro-LEDs (400) face the center of the second concave portions (120).

6. A method for preparing a double-layer aspherical microlens array structure, characterized in that: The following steps are involved: Coating a photoresist having a first refractive index on a planar transparent substrate, and curing the substrate to obtain a low-refractive-index photoresist layer having a uniform thickness; Glue is dripped on the low-refractive-index photoresist layer to obtain a first glue layer, and a first template is transferred to the first glue layer by nanoimprinting technology, wherein a first aspheric protrusion array is provided on the first template, so that a plurality of first concave portions arranged in an array are formed on the first glue layer, wherein the first glue layer has the first refractive index; Separating the first adhesive layer from the first template, coating the transferred first adhesive layer with a photoresist having a second refractive index, and curing the photoresist to obtain a high-refractive-index photoresist layer, wherein the second refractive index is greater than the first refractive index; Glue is dripped onto the high-refractive-index photoresist layer to obtain a second glue layer, and a second template is transferred to the second glue layer by nanoimprinting technology, wherein a second aspheric protrusion array is provided on the second template, so that a plurality of second concave portions arranged in an array are formed on the second glue layer; the second concave portions (120) correspond to the first concave portions (210) one by one, and the centers of the two are aligned, the aperture of the second concave portion (120) is smaller than the aperture of the first concave portion (210), and the bottom surfaces of the second concave portion (120) and the first concave portion (210) are both aspheric surfaces; wherein the second glue layer has the second refractive index; The second adhesive layer is separated from the second template to obtain a double-layer aspherical microlens array structure.

7. The method for preparing a double-layer aspherical microlens array structure according to claim 6, characterized in that: Before transferring the second template to the second adhesive layer, the method further comprises: Based on the target set on the second template, the imprint position of the second template is determined.

8. The method for preparing a double-layer aspherical microlens array structure according to claim 6, characterized in that: The first template is made of UV glue and is obtained in the following way: Manufacturing a first master of a first aspheric microlens array by laser grayscale direct writing lithography, wherein a first aspheric protrusion array is provided on the first master, and the first master is made of photoresist material; Transferring the first master to obtain a first sample by nanoimprinting technology, so that the imprinted surface of the first sample forms a first aspheric concave array that matches the first aspheric convex array; The first template is obtained by transferring the first sample through nanoimprinting technology, so that the first aspheric convex array that is compatible with the first aspheric concave array is formed on the first template.

9. The method for preparing a double-layer aspherical microlens array structure according to claim 8, characterized in that: The second template is made of UV glue and is obtained in the following way: Manufacturing a second master of a second aspherical microlens array by laser grayscale direct writing lithography, wherein a second aspherical protrusion array is provided on the second master, and the second master is made of photoresist material; Transferring the second master plate to obtain a second template by nanoimprinting technology, so that the imprinted surface of the second template forms a second aspheric concave array that matches the second aspheric convex array; The second template is obtained by transferring the second sample through nanoimprinting technology, so that the second aspheric convex array that is compatible with the second aspheric concave array is formed on the second template.

10. The method for preparing a double-layer aspherical microlens array structure according to claim 9, characterized in that: The first master is also provided with a first target, and the first target is a concave structure or a convex structure; The second master is also provided with a second target, and the second target is a concave structure or a convex structure; The first master and the second master satisfy that: when the first target is aligned with the second target, the first aspheric convex array on the first master is aligned with the second aspheric convex array on the second master.

11. The method for preparing a double-layer aspherical microlens array structure according to claim 9, characterized in that: The convex surface shapes of the first aspheric convex array on the first master and the second aspheric convex array on the second master are characterized by an even-order high-order aspheric formula; The first aspheric convex array and the second aspheric convex array are arranged in a circular pattern, an annular pattern, a polygonal pattern or a cartoon character shape pattern; The outer diameter of the protrusions in the first aspheric protrusion array is greater than the outer diameter of the protrusions in the second aspheric protrusion array; The protrusion height of the protrusions in the first aspheric protrusion array is greater than the protrusion height of the protrusions in the second aspheric protrusion array.

12. A method for preparing a lighting device, characterized in that: The following steps are involved: The double-layer aspherical microlens array structure is obtained by the preparation method according to any one of claims 6 to 11; A light board is prepared, wherein the light board is made of an opaque material and is provided with a Micro-LED array, wherein the Micro-LED array is adapted to the double-layer aspheric microlens array structure, including: each Micro-LED is respectively arranged in each second concave portion formed on the second adhesive layer of the double-layer aspheric microlens array structure, and the light-emitting surface of the Micro-LED faces the center of the second concave portion.

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