A microlens structure and preparation method for Micro-LED chip pixel pattern conversion

Abstract

The present invention relates to the field of Micro-LED technology, and specifically discloses a microlens structure and a preparation method for pixel pattern conversion of Micro-LED chips. The microlens structure includes microlens units arranged in an array. Each microlens unit includes a light spot shaping section and a light spot homogenizing section. The light spot shaping section is provided with a circular light incident end face. A transfer cross-section is provided at one end of the light spot shaping section close to the light spot homogenizing section. An outgoing light end face is provided at one end of the light spot homogenizing section far from the light spot shaping section. The transfer cross-section and the outgoing light end face have the same shape and are both closely packed graphic structures. The central connection line between any two of the circular light incident end face, the transfer cross-section, and the outgoing light end face is perpendicular to the circular light incident end face. The microlens structure of the present invention realizes the light spot shaping of multi-light sources at the micron scale, effectively reduces the dark area between circular pixel units, the overall light illumination of the chip is more uniform, and the printing accuracy can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of Micro-LED, and particularly relates to a microlens structure for Micro-LED chip pixel pattern conversion and a preparation method thereof. Background Art

[0002] Micro Light Emitting Diode (abbreviated as Micro-LED) is a new type of device formed by an array of multiple light emitting diodes (abbreviated as LED) on the micron scale. Due to the advantages of high resolution, high brightness, energy conservation, environmental protection and good flexibility of Micro-LED, when Micro-LED is used as a light source in Three-Dimensional Printing (abbreviated as 3D printing), it can provide 3D printing results with high precision, high resolution and low energy consumption.

[0003] Among them, the Micro-LED with circular pixels has high brightness and contrast, can achieve full-color display, and at the same time, the design of the circular pixel Micro-LED is simple and easy to manufacture, so that the circular pixel Micro-LED is widely used in the market. However, due to its own shape and arrangement, the circular pixel Micro-LED generates dark areas, which have a great negative impact on 3D printing, mainly reflected in the following aspects: First, during the 3D printing process on the micron scale, due to the appearance of dark areas, the light intensity distribution is uneven, resulting in damage to the accuracy of the printed physical structure. Second, the dark areas will also cause uneven radiation energy, which will seriously damage the smoothness of the printed model, the surface topography of the physical object fluctuates, the surface of the model will bulge or sink, and the overall quality of the model is not high.

[0004] Because the dark areas of the circular pixel Micro-LED have defects in the application of 3D printing on the micron scale, when applying Micro-LED to 3D printing, it is necessary to improve the light distribution of Micro-LED and reduce the area of the dark areas. In order to reduce the area of the dark areas and improve the printing accuracy, the arrangement of the circular pixels can be changed and the distance between the pixel points can be reduced. However, due to the inherent defects of the circular pixels, their arrangement combinations cannot avoid the existence of dark areas.

[0005] Due to the controllability of the shape and side length of the square pixels, Micro-LED lighting without dark areas can be achieved. However, since Micro-LED is a Lambertian light source, the central light intensity is strong and the peripheral light intensity is weak, which easily causes uneven illuminance on the target surface. This requires the design of relevant optical lenses to improve the illuminance uniformity on the target surface.

[0006] Chinese Patent CN219085995U discloses a semiconductor light-emitting unit and a semiconductor light-emitting device. The semiconductor light-emitting unit includes: a substrate, a semiconductor chip disposed on the substrate, and a first lens covering the light-emitting surface of the semiconductor chip. The first lens has an outgoing light surface, and the outer edge of the outgoing light surface of the first lens is quasi-elliptical. The quasi-elliptical shape is defined by a preset square and a standard ellipse inscribed in the square. Specifically, the quasi-ellipse is composed of several arcs connected end to end. The arcs are located inside the preset square and outside the standard ellipse, and at least some of the arcs pass through the tangent points of the preset square and the standard ellipse. The first lens of the semiconductor light-emitting unit provided by this solution is more likely to form a light spot close to a square, and the illuminance change near the four corners of the square light spot is small. Although this lens design improves the illuminance uniformity of the target area to a certain extent, the accuracy requirement for the outer edge of the outgoing light surface of the lens is extremely high, and the lens size is much larger than the LED chip size. This results in that this lens structure can only be applied to a rectangular light spot formed by a single point light source, while Micro-LED is an array of LED light sources on the micron scale, and this lens structure is not suitable for the light spot shaping of multi-light sources on the micron scale.

[0007] Chinese Patent CN105465646B discloses an LED optical structure that can achieve the transformation between a circular light spot and a square light spot, including a first lens that can achieve a circular light spot. A detachable second lens is connected to the first lens, and the second lens is coaxially installed with the first lens; and the superposition effect of the first lens and the second lens can achieve a square light spot, and the transformation between the circular light spot and the square light spot is realized by detaching or installing the second lens. Although this solution can achieve the transformation from a circular light spot to a square light spot, it requires the application of a lens group with a complex structure, which is very difficult in the application of Micro-LED light spot shaping. Summary of the Invention

[0008] The purpose of the present invention is to provide a microlens structure and a preparation method for Micro-LED chip pixel pattern conversion in view of the existing technical status.

[0009] The microlens structure of the present invention converts the circular light spots of each circular pixel unit into light spots with uniform outgoing illuminance and a closely packed graphic structure through microlens units, realizes the light spot shaping of multi-light sources on the micron scale, effectively reduces the dark area between circular pixel units, and the overall light illuminance of the Micro-LED chip is more uniform. When applied to 3D printing on the micron scale, it can effectively improve the light reception uniformity of the printing material and improve the printing accuracy. The microlens units are integrally formed, without the need to use a complex lens group, and the overall structure of the microlens structure is simple and easier to manufacture.

[0010] To achieve the above object, the present invention adopts the following technical solutions:

[0011] The present invention provides a microlens structure for Micro-LED chip pixel pattern conversion, including microlens units arranged in an array. The microlens unit includes a light spot shaping section and a light spot homogenization section arranged in sequence along the direction away from the circular pixel unit. One end of the light spot shaping section close to the circular pixel unit is provided with a circular light incident end face, and the shape between the circular light incident end face and the light emitting surface of the circular pixel unit is the same. A transfer cross-section is provided at one end where the light spot shaping section and the light spot homogenization section are close to each other. One end of the light spot homogenization section away from the light spot shaping section is provided with a light emitting end face. The shape of the transfer cross-section is the same as that of the light emitting end face, and both are close-packed graphic structures. The central connection line between any two of the circular light incident end face, the transfer cross-section, and the light emitting end face is perpendicular to the circular light incident end face.

[0012] In some embodiments, the close-packed graphic structure is a regular polygon structure.

[0013] In some embodiments, the close-packed graphic structure is any one or a combination of a regular quadrilateral, a regular hexagon, a regular octagon, and a regular dodecagon.

[0014] In some embodiments, the close-packed graphic structure is a regular quadrilateral, and the ratio of the diameter of the circular light incident end face to the side length of the regular quadrilateral is 1:1.2 - 1.5.

[0015] In some embodiments, the height ratio between the light spot shaping section and the light spot homogenization section is 1:2 - 3.

[0016] In some embodiments, the light spot shaping section is provided with a transition cylinder for connecting the circular light incident end face and the transfer cross-section, and the developed shape of the side wall of the transition cylinder is a developed graphic obtained by lofting from the circular light incident end face to the transfer cross-section.

[0017] In some embodiments, a transparent connection layer for fixing the circular light incident end face on the circular pixel unit is provided on the circular light incident end face.

[0018] In some embodiments, the refractive index of the microlens unit is 1.5 - 1.7, and the material of the microlens unit is any one of transparent photosensitive resin, plexiglass, or silica gel.

[0019] The present invention also provides a preparation method for preparing the above-mentioned microlens structure for Micro-LED chip pixel pattern conversion, including:

[0020] Constructing a three-dimensional solid model of the microlens structure, and performing layer slicing and path planning on the three-dimensional solid model to form a data file recognizable by a 3D printer;

[0021] The 3D printer prints the microlens structure layer by layer according to the data file.

[0022] In some embodiments, it further includes:

[0023] Determine the center distance between adjacent circular light-incident end faces in the microlens structure according to the center distance between adjacent circular pixel units;

[0024] The center distance l between adjacent circular pixel units satisfies the following formula:

[0025]

[0026] In the formula, l is the center distance between adjacent circular pixel units, λ is the emission wavelength of the circular pixel unit, D is the aperture of the projection imaging objective lens in the 3D printing device applied to the Micro-LED chip, and f is the focal length of the projection imaging objective lens in the 3D printing device applied to the Micro-LED chip.

[0027] The beneficial effects of the present invention are as follows:

[0028] In the present invention, by providing a microlens unit composed of a light spot shaping section and a light spot homogenization section, the light emitted by the circular pixel unit enters the microlens unit through the circular light-incident end face of the light spot shaping section. The light undergoes total internal reflection inside the light spot shaping section and is transmitted to the transfer cross section at one end of the light spot shaping section close to the light spot homogenization section. Thus, the circular light spot of the circular pixel unit is converted into a tiled graphic structure consistent with the shape of the transfer cross section. Subsequently, the shaped light spot enters the light spot homogenization section. After the light enters the inside of the light spot homogenization section, total internal reflection occurs on the side wall of the light spot homogenization section, gradually adjusting the light distribution and supplementing the light in the edge corners. Thus, the light-emitting surface formed at the light-emitting end face is a tiled graphic structure with uniform light distribution. Compared with the circular light spot emission mode of the circular pixel unit, the microlens structure of the present invention converts the circular light spots of each circular pixel unit into light spots with uniform illumination and a tiled graphic structure through the microlens unit, realizing the light spot shaping of multiple light sources at the micron scale, effectively reducing the dark area between circular pixel units, making the overall light illumination of the Micro-LED chip more uniform. When applied to 3D printing at the micron scale, it can effectively improve the light reception uniformity of the printing material and improve the printing accuracy. The microlens unit is integrally formed, without the need to use a complex lens group, and the overall structure of the microlens structure is simple and easier to manufacture. Description of the Drawings

[0029] Figure 1 It is a schematic structural diagram of a Micro-LED chip.

[0030] Figure 2Schematic diagram of the structure of the microlens structure for Micro-LED chip pixel pattern conversion of the present invention mounted on a Micro-LED chip.

[0031] Figure 3 is Figure 2 cross-sectional view of.

[0032] Figure 4 Schematic diagram of the structure of the microlens unit of the present invention.

[0033] Figure 5 Side view of the microlens unit of the present invention.

[0034] Figure 6 Cross-sectional view of the microlens unit of the present invention.

[0035] Figure 7 Structure diagram of a Micro-LED chip under a digital microscope (the length scale in the figure is 20μm).

[0036] Figure 8 Optical software Lighttools simulation emission diagram of a Micro-LED chip (where the light source of the circular pixel unit is a Lambertian light source, the emission wavelength is 532nm, the full width at half maximum FHWM is 30nm, and the light output angle is 180°).

[0037] Figure 9 Emitted illuminance diagram of a single circular pixel unit of a Micro-LED chip.

[0038] Figure 10 Emitted illuminance diagram of a single circular pixel unit of a Micro-LED chip plus a single microlens unit for spot shaping.

[0039] Figure 11 Emission effect diagram of a Micro-LED chip after installing the microlens structure of the present invention.

[0040] Figure 12 Flow chart of the preparation method of the microlens structure for Micro-LED chip pixel pattern conversion of the present invention for preparing the above.

[0041] Figure 13 Diffraction spot diagram of adjacent circular pixel units of the Micro-LED chip of the present invention.

[0042] Figure 14 Diffraction spot diagram of spaced circular pixel units of the Micro-LED chip of the present invention. Detailed implementation manners

[0043] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below.

[0044] Referring to Figures 1 to 3 and Figure 6 as shown, the present invention provides a microlens structure for Micro-LED chip pixel pattern conversion, which includes microlens units 1 arranged in an array. The microlens unit 1 includes a light spot shaping section 11 and a light spot homogenizing section 12 sequentially arranged in a direction away from the circular pixel unit 2. A circular light incident end face 111 is provided at one end of the light spot shaping section 11 close to the circular pixel unit 2. The shape between the circular light incident end face 111 and the light emitting surface of the circular pixel unit 2 is the same. A transfer cross-section 112 is provided at one end of the light spot shaping section 11 and the light spot homogenizing section 12 close to each other. An outgoing light end face 121 is provided at one end of the light spot homogenizing section 12 away from the light spot shaping section 11. The shape of the transfer cross-section 112 and the outgoing light end face 121 is the same, and both are close-packed graphic structures. The central connection line between any two of the circular light incident end face 111, the transfer cross-section 112, and the outgoing light end face 121 is perpendicular to the circular light incident end face 111.

[0045] Among them, the close-packed graphic structure refers to a graphic that can be closely packed, that is, a graphic that can cover a two-dimensional plane without gaps and without overlapping belongs to the close-packed graphic structure. Close packing means using one or more congruent shapes (that is, exactly the same size and shape) of planar graphics for splicing, so that these graphics cover the entire plane area, leaving no gaps and not overlapping each other.

[0046] During use, the microlens structure is installed on the pixel layer of the Micro-LED chip. Specifically, referring to Figure 1 、 Figure 7As shown, the pixel layer is composed of circular pixel units 2 arranged in an array, and the microlens units 1 and the circular pixel units 2 on the microlens structure are arranged one by one in a corresponding manner, so that the circular light incident end surface 111 on each microlens unit 1 is coaxially arranged with the circular pixel unit 2 and fits tightly. Thus, the circular light incident end surface 111 constitutes a light incident surface, and the light emitted by the circular pixel unit 2 enters the interior of the microlens unit 1 through the circular light incident end surface 111, wherein the light first enters the interior of the light spot shaping section 11 through the circular light incident end surface 111, and the light is totally reflected inside the light spot shaping section 11 and transmitted to the transfer section 112, thereby converting the circular light spot of the circular pixel unit 2 into a light spot with the same shape as the transfer section 112. At this time, the overall outline of the light spot is a densely packed graphic structure. However, in this process, since the light is totally reflected at the edge of the light spot shaping section 11, the light is concentrated in the middle of the transfer section 112, and there is less light at the edge corners of the transfer section 112, especially the edge corners At this point, the illumination at the center is strong, while the illumination at the edge corners is weak. Therefore, at this stage, although the light spot can be transformed from a circular shape into a densely packed pattern structure, the light distribution of the light spot is uneven. Therefore, after the light is transmitted to the transfer section 112, the shaped light spot enters the light spot equalization section 12. After the light enters the light spot equalization section 12, it is totally reflected at the side wall of the light spot equalization section 12 and transmitted to the light output end face 121. Since the shape of the transfer section 112 is consistent with that of the light output end face 121, the light distribution can be gradually adjusted during the transmission within the light spot equalization section to supplement the light at the edge corners. As a result, the light output surface formed on the light output end face 121 is a densely packed pattern structure with uniform light distribution.

[0047] In the present invention, a microlens unit 1 is provided, which is composed of a light spot shaping section 11 and a light spot equalizing section 12. Light emitted by a circular pixel unit 2 enters the microlens unit 1 through the circular light incident end face 111 of the light spot shaping section 11. The light undergoes total internal reflection within the light spot shaping section 11 and is transmitted to the transition section 112 of the light spot shaping section 11 near one end of the light spot equalizing section 12. This converts the circular light spot of the circular pixel unit 2 into a densely packed pattern structure with the same shape as the transition section 112. Subsequently, the shaped light spot enters the light spot equalizing section 12. After entering the light spot equalizing section 12, the light undergoes total internal reflection from the sidewalls of the light spot equalizing section 12, gradually adjusting the light distribution and supplementing the light in the edge corners. As a result, the light output surface formed on the light output end face 121 is a densely packed pattern structure with uniform light distribution. Figures 8 to 11As shown, compared with the circular light spot emission mode of the circular pixel unit 2, the microlens structure of the present invention converts the circular light spots of each circular pixel unit 2 into light spots with uniform illumination and a closely packed graphic structure through the microlens unit 1, realizing the shaping of light spots of multiple light sources at the micron scale, effectively reducing the dark area between the circular pixel units 2, and making the overall light illumination of the Micro-LED chip more uniform. When applied to 3D printing at the micron scale, it can effectively improve the light reception uniformity of the printing material and enhance the printing accuracy. The microlens unit 1 is integrally formed, without the need to use a complex lens group. The overall structure of the microlens structure is simple and easier to manufacture.

[0048] In this embodiment, the diameter of the circular pixel unit < 50μm, and more preferably, the diameter of the circular pixel unit < 30μm.

[0049] Among them, the closely packed graphic structure is a regular polygon structure. Using a regular polygon structure is beneficial to reducing the manufacturing difficulty of the microlens unit 1 and the complexity of the arrangement design.

[0050] Among them, preferably, the closely packed graphic structure is any one or a combination of a regular quadrilateral, a regular hexagon, a regular octagon, and a regular dodecagon.

[0051] More preferably, the closely packed graphic structure is a regular quadrilateral or a regular hexagon. A regular quadrilateral or a regular hexagon is a closely packed graphic structure that can be closely packed alone, which can further reduce the manufacturing difficulty of the microlens unit 1 and the complexity of the arrangement design.

[0052] See Figures 4 to 6 As shown, more preferably, the closely packed graphic structure is a regular quadrilateral. See Figures 8 to 11 As shown, by comparing the circular light spot illumination diagram before using the microlens structure with the square light spot illumination diagram after using the microlens structure, it can be clearly observed that the dark area has decreased significantly. When the closely packed graphic structure is a regular quadrilateral, the circular light spots emitted by the circular pixel unit 2 can be converted into square light spots, and the proportion of the dark area decreases from 59.93% to 13.78%, and the illumination uniformity on the surface of the microlens is increased to 95.5%. When applied to 3D printing at the micron scale, it effectively increases the light receiving surface and light receiving uniformity of the printing material and improves the 3D printing accuracy.

[0053] Among them, the closely packed graphic structure is a regular quadrilateral, and the ratio of the diameter of the circular light incident end face 111 to the side length of the regular quadrilateral is 1:1.2 - 1.5. Exemplarily, the ratio of the diameter of the circular light incident end face 111 to the side length of the regular quadrilateral is 1:1.2, 1:1.25, 1:1.3, 1:1.35, 1:1.4, 1:1.45, or 1:1.5, but not limited thereto. The side length of the regular quadrilateral should not be too large compared to the diameter of the circular light incident end face 111 to avoid increasing the difficulty of light spot uniformity.

[0054] Among them, the height ratio between the light spot shaping section 11 and the light spot homogenizing section 12 is 1:2 to 3. Exemplarily, the height ratio between the light spot shaping section 11 and the light spot homogenizing section 12 is 1:2, 1:2.2, 1:2.5, 1:2.8 or 1:3, but not limited thereto. The illumination uniformity of the light-emitting end face 121 is related to the height ratio between the light spot shaping section 11 and the light spot homogenizing section 12. Within this height ratio range, the illumination uniformity of the light-emitting end face 121 is higher than 95%, further improving the 3D printing accuracy.

[0055] Among them, the light spot shaping section 11 is provided with a transition cylinder 113 for connecting the circular light-incident end face 111 and the transition cross-section 112. The developed shape of the side wall of the transition cylinder 113 is a developed lofting graphic from the circular light-incident end face 111 to the transition cross-section 112. Thus, the light spot shaping section 11 can better transition from the circular light-incident end face 111 to the transition cross-section 112.

[0056] Among them, a transparent connection layer (not shown) for fixing the circular light-incident end face 111 on the circular pixel unit 2 is provided on the circular light-incident end face 111. Exemplarily, the transparent connection layer is an optical adhesive or a transparent base film with an optical adhesive. For example, silicone OCA optical adhesive. Through the transparent connection layer, the circular light-incident end face 111 and the circular pixel unit 2 are closely fixed together one by one, ensuring that the light emitted from the light-emitting surface of the circular pixel unit 2 can enter the microlens unit 1 through the circular light-incident end face 111 for circular light spot conversion.

[0057] Among them, the refractive index of the microlens unit 1 is 1.5 to 1.7, and the material of the microlens unit 1 is any one of transparent photosensitive resin, plexiglass or silicone.

[0058] See Figure 12 As shown, the present invention also provides a preparation method for the microlens structure for Micro-LED chip pixel pattern conversion described above, including:

[0059] S10. Construct a three-dimensional solid model of the microlens structure, and perform layer slicing and path planning on the three-dimensional solid model to form a data file recognizable by a 3D printer;

[0060] S20. The 3D printer prints the microlens structure layer by layer according to the data file.

[0061] The present invention prints the microlens units 1 arranged in an array by a 3D printer, which can effectively improve the preparation efficiency of the microlens units 1.

[0062] Among them, the specific steps of step S10 include:

[0063] S101. Use 3D software Solidworks on a computer to establish a 3D solid model of a microlens array (microlens units 1 arranged in an array), and generate a model in STL (STereo Lithography) file format. The STL file format is a data format that approximates a curved surface with a large number of triangular facets to represent a 3D model.

[0064] S102. Use slicing software Autodesk Netfabb Ultimate to slice the 3D solid model along the height direction to obtain a two-dimensional data group S of the cross-sections of each layer of the 3D solid model n (n = 1, 2, ……, N), and import this two-dimensional data group into a 3D printer.

[0065] Among them, the specific steps of step S20 include:

[0066] S201. Add 0.1 ml of transparent photosensitive resin into the material tank of the 3D printer, set the printing layer thickness to 20 μm, the printing time for each layer to 20 s, the printing light machine power to 0.9 mW, and the number of printing layers to 150 layers.

[0067] S202. According to the data of the two-dimensional array group S n data, the computer reads the data sequentially starting from the lower layer S1. The light emitted by the Micro-LED light machine irradiates the cross-sectional shape of the first layer model. Due to the action of the photoinitiator, the prepolymer and the reactive monomer are polymerized and cured to produce a thin cured layer.

[0068] S203. After forming the cured layer of the first-layer cross-section, raise the workbench by a set height. Here, the set height is 20 μm. Coat another layer of liquid photosensitive resin on the surface of the cured layer, and perform exposure curing according to the data of the second-layer cross-section to form S2 layer. S1 layer and S2 layer are bonded together.

[0069] S204. Repeat the steps of S03 until it is cured to the S 150 layer, and a solid prototype of a three-dimensional microlens structure is obtained. Then take it out of the 3D printer and wash it with anhydrous ethanol.

[0070] Among them, referring to Figure 13 and Figure 14 as shown, step S10 also includes:

[0071] Determine the center distance between adjacent circular light-incident end faces 111 in the microlens structure according to the center distance between adjacent circular pixel units 2;

[0072] The center distance l between adjacent circular pixel units 2 satisfies the following formula:

[0073]

[0074] In the formula, l is the center distance between adjacent circular pixel units 2, λ is the emission wavelength of the circular pixel unit 2, D is the aperture of the projection imaging objective in the 3D printing device applied to the Micro-LED chip, and f is the focal length of the projection imaging objective in the 3D printing device applied to the Micro-LED chip.

[0075] Due to the reduction in the size of the circular pixel unit 2 of the Micro-LED chip, the ratio of the surface area to the side area will decrease. Increasing the sidewall light emission will cause relatively large optical crosstalk, affecting the light emission intensity between its adjacent pixels and the pixel spacing. The image resolution scaled by the projection lens needs to meet the requirements of the pixel size in 3D printing and requirements such as high precision and low crosstalk. To meet the printing accuracy requirements and reduce the influence of optical crosstalk between pixels, the following requirements are imposed on the arrangement of the circular pixel units 2: First, the circular light spots emitted by adjacent circular pixel units 2 cannot be resolved exactly; Second, the circular light spots with a certain interval can be distributed exactly. When the center distance between adjacent circular pixel units 2 satisfies the above formula, the arrangement of the circular pixel units 2 can meet the above two requirements, effectively reducing optical crosstalk and further improving the 3D printing accuracy.

[0076] The above description is only a preferred embodiment of the present invention and does not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to it as equivalent embodiments with the same effect within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A microlens structure for Micro-LED chip pixel pattern conversion, comprising microlens units arranged in an array, characterized in that, The microlens unit includes a light spot shaping section and a light spot homogenizing section which are sequentially arranged in a direction away from the circular pixel unit. One end of the light spot shaping section close to the circular pixel unit is provided with a circular light incident end face, and the shape between the circular light incident end face and the light emitting surface of the circular pixel unit is the same. A transition section is provided at one end where the light spot shaping section and the light spot homogenizing section are close to each other. One end of the light spot homogenizing section away from the light spot shaping section is provided with a light emitting end face. The shape of the transition section is the same as that of the light emitting end face, and both are close-packed graphic structures. The center connection line between any two of the circular light incident end face, the transition section and the light emitting end face is perpendicular to the circular light incident end face; The height ratio between the light spot shaping section and the light spot homogenizing section is 1:2 to 3; Each of the microlens units is a solid structure formed integrally. During use, the microlens units are arranged in one-to-one correspondence with the circular pixel units, and the circular light incident end faces on each microlens unit are coaxially arranged with and in contact with the circular pixel units.

2. The microlens structure for Micro-LED chip pixel pattern conversion according to claim 1, characterized in that, The close-packed graphic structure is a regular polygon structure.

3. The microlens structure for Micro-LED chip pixel pattern conversion according to claim 2, characterized in that, The close-packed graphic structure is any one or a combination of a regular quadrilateral, a regular hexagon, a regular octagon and a regular dodecagon.

4. The microlens structure for Micro-LED chip pixel pattern conversion according to claim 3, wherein, The close-packed graphic structure is a regular quadrilateral, and the ratio of the diameter of the circular light incident end face to the side length of the regular quadrilateral is 1:1.2 to 1.

5.

5. The microlens structure for Micro-LED chip pixel pattern conversion according to claim 3, characterized in that, The light spot shaping section is provided with a transition cylinder for connecting the circular light incident end face and the transition section, and the developed shape of the side wall of the transition cylinder is a developed graphic obtained by lofting from the circular light incident end face to the transition section.

6. The microlens structure for Micro-LED chip pixel pattern conversion according to claim 1, wherein A transparent connection layer is provided on the circular light incident end face for fixing the circular light incident end face on the circular pixel unit.

7. A microlens structure for Micro-LED chip pixel pattern conversion according to claim 1, characterized in that The refractive index of the microlens unit is 1.5 to 1.7, and the material of the microlens unit is any one of transparent photosensitive resin, plexiglass or silica gel.

8. A method for preparing a microlens structure for Micro-LED chip pixel pattern conversion according to any one of claims 1 to 7, characterized in that, Including: Constructing a three-dimensional solid model of the microlens structure, and performing layer slicing and path planning on the three-dimensional solid model to form a data file recognizable by a 3D printer; The 3D printer prints the microlens structure layer by layer according to the data file.

9. The preparation method according to claim 8, characterized in that, Also including: Determining the center distance between adjacent circular light incident end faces in the microlens structure according to the center distance between adjacent circular pixel units; The center distance l between adjacent circular pixel units satisfies the following formula: In the formula, l is the center distance between adjacent circular pixel units, λ is the emission wavelength of the circular pixel unit, D is the aperture of the projection imaging objective in the 3D printing device applied to the Micro-LED chip, and f is the focal length of the projection imaging objective in the 3D printing device applied to the Micro-LED chip.

Images