Microprism reflective film integrated with three triangular pyramid combinations and manufacturing method of mold of microprism reflective film

Abstract

The invention relates to a microprism reflective film integrated with three types of triangular pyramid combinations and a manufacturing method of a mold of the microprism reflective film, which are characterized in that the surface of the microprism reflective film is formed by the same parallelogram unit array, and each parallelogram unit consists of four same triangular pyramids A, two mixed triangular pyramids B and two mixed triangular pyramids C, the bottom surfaces of the triangular pyramids A, the mixed triangular pyramids B and the mixed triangular pyramids C are the same equilateral triangles, the inclination angles of the three pyramid surfaces of each triangular pyramid A are alpha / 2, the inclination angles of the pyramid surfaces of the mixed triangular pyramids B are alpha / 2, alpha / 2 and beta L, and the inclination angles of the three pyramid surfaces of the mixed triangular pyramids C are alpha / 2, alpha / 2 and beta R; according to the method, the performance under different application conditions can be reasonably optimized, so that wide-angle performance improvement and optimization and balance of overall comprehensive performance can be realized.

Description

Technical Field

[0001] The present invention relates to a manufacturing method of a microprism retroreflective film integrating a combination of three triangular pyramids and a mold thereof. Background Art

[0002] Design of a microprism retroreflective film based on a triangular pyramid unit structure: A tool is used to machine three pyramid surfaces of a triangular pyramid, and the inclination angles (angles with the vertical plane) of the three pyramid reflecting surfaces are the same, as Figure 1 shown. Such a design of the microprism retroreflective film is mainly used for Class III and Class IV retroreflective films with relatively low performance requirements. When used for Class V retroreflective films, under the conditions of large viewing angles and large incident angles, the retroreflective coefficient cannot meet the standard requirements. In order to obtain the performance requirements of Class V retroreflective films, different design or manufacturing solutions have been proposed at home and abroad. The 3M Company in the United States has proposed an optical design of a retroreflective film using a full prism structure. However, this design has a complex structure, high requirements for the manufacturing accuracy of the mold, and a large impact of manufacturing errors on the performance of the retroreflective film, which limits its popularization and application in China.

[0003] Specifically, there is only one optical design variable for the microprism retroreflective film in the above Figure 1 , and it is difficult to simultaneously improve the retroreflective performance at different incident angles and viewing angles (especially wide angles), that is, different azimuth angles, and to balance the retroreflective performance between different incident angles and viewing angles (especially wide angles and small incident angles), and the balance of retroreflective performance between different azimuth angles (such as 0 degrees, 90 degrees, 180 degrees).

[0004] In the prior art, in order to obtain the isotropy of the retroreflective performance of the retroreflective film at different azimuth angles, nickel molds for four types of retroreflective films are usually manufactured into a roller master mold by mechanically splicing two nickel molds of the retroreflective film with different orientations of 0 degrees and 90 degrees; by slightly adjusting an angle to deviate from the standard pyramid reflector structure, the regulation of the retroreflective performance of the retroreflective film is realized (such as improving the wide-angle performance), but the above method is very cumbersome to manufacture and there are mechanical splicing errors, making it difficult to achieve the expected effect.

[0005] Although the microprism retroreflective film using a full prism (3M in the United States) has a 50% higher retroreflective performance than the microprism retroreflective film using a triangular pyramid (or the effective reflection area of the triangular pyramid retroreflective film is 66.67% of the effective reflection area of the full prism retroreflective film), the mold structure of the full prism retroreflective film (such as Chinese Patent Nos. 2015107772604 and 201811202555.9) is very complex, the manufacturing difficulty is very high, and due to the manufacturing errors of the mold, the reflective performance is much lower than expected, thus limiting its popularization and application.

[0006] In view of the above deficiencies, the applicant applied for "Retroreflective Microprism Array Structure and Its Manufacturing Method" (Publication No. CN 117930406 A) in March 2024 and "Manufacturing Method of Microprism Reflective Film with Double Triangular Pyramid Composite Structure and Its Mold" (Publication No. CN118759624B) in September 2024 respectively.

[0007] Among them, although the "Retroreflective Microprism Array Structure and Its Manufacturing Method" is more convenient for manufacturing compared with patents 2015107772604 and 201811202555.9, it avoids the difficulty of secondary clamping and machining of special-shaped surfaces and ensures the quality of the finished product. However, when making through holes on the second substrate in the processing procedure, it is necessary to drill holes one by one first and then process them by wire cutting. The processing procedure is still relatively cumbersome. Moreover, each pyramid formed by its processing is a regular triangular pyramid, and the inclination angles of the pyramid surfaces are all the same. There is only one optical design variable for the microprism reflective film obtained, and it is difficult to obtain different incident angles and observation angles. That is, such a microprism reflective film design can meet the performance requirements of Class IV reflective films. When used for Class V reflective films, under the conditions of large observation angles and large incident angles, the retroreflective coefficient cannot meet the standard requirements. Among them, the "Manufacturing Method of Microprism Reflective Film with Double Triangular Pyramid Composite Structure and Its Mold" proposes to use two kinds of tools with tool design angles of α and β to process a microprism reflective film with a double triangular pyramid composite structure on the same mold substrate. After using the first kind of tool with a tool angle of α to process the large triangular pyramid, then use the second kind of tool with a tool angle of β to process. According to the design requirements, adjust the orientation of the tool so that the inclination angles of the three pyramid surfaces of the central triangular pyramid are all β / 2. At this time, the inclination angles of the two pyramid surfaces of the corner triangular pyramid are α / 2, and the inclination angle of the third pyramid surface in the middle is β / 2. Although the wide-angle performance of the reflective film can be optimized to a certain extent by adjusting the angle variable of the triangular pyramid located in the center, or a certain degree of optimization of the 0-degree and 90-degree performance of the reflective film can be obtained, the microprism reflective film obtained still has the disadvantage of insufficient freedom in optical design optimization. Summary of the Invention

[0008] In view of the above problems, the purpose of the present invention is to propose a manufacturing method of a microprism reflective film integrating three triangular pyramid combinations and its mold. The manufacturing method of the microprism reflective film integrating three triangular pyramid combinations and its mold is reasonably designed, can further increase the freedom of optical design, is beneficial to optimization design, and obtains better performance indicators under different application conditions.

[0009] The technical solution of the present invention is as follows: The present invention integrates a microprism retroreflective film with a combination structure of three triangular pyramids, which is characterized in that: the surface of the microprism retroreflective film is formed by an array of identical parallelogram unit cells, and each parallelogram unit cell is composed of four identical triangular pyramids A, two hybrid triangular pyramids B, and two hybrid triangular pyramids C. The bases of the triangular pyramid A, the hybrid triangular pyramid B, and the hybrid triangular pyramid C are all identical equilateral triangles. The inclination angles of the three pyramidal faces of each triangular pyramid A are all α / 2, the inclination angles of the pyramidal faces of the hybrid triangular pyramid B are α / 2, α / 2, and βL, and the inclination angles of the three pyramidal faces of the hybrid triangular pyramid C are α / 2, α / 2, and βR respectively; the triangular pyramids A are respectively triangular pyramid A1, triangular pyramid A2, triangular pyramid A3, and triangular pyramid A4, the hybrid triangular pyramids B are respectively triangular pyramid B1 and triangular pyramid B2, and the hybrid triangular pyramids C are respectively triangular pyramid C1 and triangular pyramid C2. The first row of the parallelogram unit cell is sequentially arranged with triangular pyramid A3, triangular pyramid A4, triangular pyramid C2, and triangular pyramid B2, and the second row of the parallelogram unit cell is sequentially arranged with triangular pyramid C1, triangular pyramid B1, triangular pyramid A1, and triangular pyramid A2. The orientations of adjacent triangular pyramids are 180 degrees to each other.

[0010] Preferably, the pyramidal face C101 of the triangular pyramid C1 and the pyramidal face A101 of the triangular pyramid A1 are coplanar, the pyramidal face A401 of the triangular pyramid A4 and the pyramidal face B201 of the triangular pyramid B2 are coplanar, the pyramidal face C102 of the triangular pyramid C1 and the pyramidal face A301 of the triangular pyramid A3 are coplanar, the pyramidal face A201 of the triangular pyramid A2 and the pyramidal face B202 of the triangular pyramid B2 are coplanar, the pyramidal face A102 of the triangular pyramid A1 and the pyramidal face A302 of the triangular pyramid A3 are coplanar, the pyramidal face A202 of the triangular pyramid A2 and the pyramidal face A402 of the triangular pyramid A4 are coplanar, the pyramidal face A303 of the triangular pyramid A3 and the pyramidal face C201 of the triangular pyramid C2 are coplanar, the pyramidal face B101 of the triangular pyramid B1 and the pyramidal face A203 of the triangular pyramid A2 are coplanar, the pyramidal face B102 of the triangular pyramid B1 and the pyramidal face A403 of the triangular pyramid A4 are coplanar, and the pyramidal face A103 of the triangular pyramid A1 and the pyramidal face C202 of the triangular pyramid C2 are coplanar.

[0011] Preferably, α = 70.55 degrees, β = 70.15 degrees, βL = 35.15°, and βR = 35.00°.

[0012] Preferably, the array intercept of the microprism retroreflective film is 0.433 mm, and each parallelogram unit cell in the microprism retroreflective film contains 8 triangular pyramids with a base side length of 250 μm.

[0013] A manufacturing method for a mold of the microprism retroreflective film integrating a combination structure of three triangular pyramids, which is used to manufacture a mold of the microprism retroreflective film integrating a combination of three triangular pyramids. The mold base material is horizontally installed on the workbench. The workbench can drive the mold base material to move along the X-axis and Y-axis in the horizontal direction, and the B-axis turntable on the workbench can drive the mold base material to rotate around the normal B-axis of the mold base material. Above the mold base material, there is a main shaft parallel to the upper surface of the mold base material and a fly cutter disc fixedly connected to the main shaft. Knives are installed on the fly cutter disc, and the knives can rotate around the Y-axis driven by the main shaft. The specific manufacturing steps are as follows: Step 1: Rotate the mold base material on the B-axis turntable by an angle of 0 degrees, and use the first type of knife with a knife angle of α installed on the fly cutter disc to machine the two side conical surfaces of the parallelogram unit body, that is, the conical surface C101 of the triangular pyramid C1, the conical surface A101 of the triangular pyramid A1, the conical surface A401 of the triangular pyramid A4, and the conical surface B201 of the triangular pyramid B2. The inclination angle is α / 2. The first type of knife is a symmetric knife, and the inclination angles on both sides are the same; Step 2: Rotate the mold base material on the B-axis turntable by an angle of 120 degrees, and use the first type of knife with a knife angle of α installed on the fly cutter disc to machine the other two side conical surfaces of the parallelogram unit body, that is, the conical surface C102 of the triangular pyramid C1, the conical surface A301 of the triangular pyramid A3, the conical surface A201 of the triangular pyramid A2, and the conical surface B202 of the triangular pyramid B2. The inclination angle is also α / 2; Step 3: Rotate the mold base material on the B-axis turntable by an angle of 60 degrees, and use the first type of knife with a knife angle of α installed on the fly cutter disc to machine the conical surfaces at the two diagonals of the parallelogram unit body, that is, the conical surface A102 of the triangular pyramid A1, the conical surface A302 of the triangular pyramid A3, the conical surface A202 of the triangular pyramid A2, and the conical surface A402 of the triangular pyramid A4. The inclination angle is also α / 2; Step 4: On the basis of the structure processed in Step 3, rotate the mold base material to the 0-degree position, and use the first type of knife to machine and form the conical surface B101 of the triangular pyramid B1 and the conical surface A203 of the triangular pyramid A2. The inclination angle is α / 2; at the same time, form the conical surface A303 of the triangular pyramid A3 and the conical surface C201 of the triangular pyramid C2. The inclination angle is α / 2; Step 5: Rotate the mold base material to 120 degrees in sequence, and use the first type of knife to machine and form the conical surface B102 of the triangular pyramid B1 and the conical surface A403 of the triangular pyramid A4. The inclination angle is α / 2, and at the same time, form the conical surface A103 of the triangular pyramid A1 and the conical surface C202 of the triangular pyramid C2. The inclination angle is α / 2; Step 6: Replace and install the second type of asymmetric tool with a blade angle of β on the fly cutter disc, the left blade inclination angle of the second type of tool is βL, and the right blade inclination angle is βR, βL is not equal to βR, the inclination angle of the triangular pyramid reflective surface processed by the left blade is βL, and the inclination angle of the triangular pyramid reflective surface processed by the right blade is βR, and the mold substrate is rotated to 60 degrees in sequence, and the second type of tool adjusted above is used to process and form the pyramid surface B103 of the triangular pyramid B1 and the pyramid surface B203 of the triangular pyramid B2, and the inclination angle is βL; at the same time, the pyramid surface C103 of the triangular pyramid C1 and the pyramid surface C203 of the triangular pyramid C2 are formed, and the inclination angle is βR; At this point, the mold for the microprismatic reflective film composed of three different triangular pyramid structures, namely, triangular pyramids A with inclination angles of α / 2, mixed triangular pyramids B with inclination angles of α / 2, α / 2 and βL, and mixed triangular pyramids C with inclination angles of α / 2, α / 2 and βR, has been processed and formed.

[0014] Preferably, the first tool has a blade angle of α=70.55 degrees; the second tool is an asymmetric tool with a blade angle of β=70.15 degrees, and the left blade inclination angle is βL=35.15 degrees, and the right blade inclination angle is βR=35.00 degrees; during processing, the first tool is used first, and the array processing is performed according to the B-axis rotation angle of 0 degrees, 60 degrees, and 120 degrees, respectively, and the intercept is 0.433mm. The 1st to 3rd tools are processed to form a large triangular pyramid, and then the B-axis rotation angles are 60 degrees, 120 degrees, and the intercept is 0.433mm along the center of the edge of the large triangular pyramid. The 4th and 5th cuts are processed in an array along the connecting lines respectively; finally, the second cutter is replaced, and the 6th cut is processed in an array along the connecting lines of the centers of adjacent edge lines of the large triangular pyramid with an intercept of 0.433 mm according to the B-axis rotation angle of 60° to form a composite microprismatic reflective film composed of a parallelogram unit array, each parallelogram unit contains 8 triangular pyramids with a side length of 250 μm, among which the inclination angles of the reflection surfaces of 4 triangular pyramids are α / 2, the inclination angles of the reflection surfaces of 2 triangular pyramids are α / 2, α / 2 and βL respectively, and the inclination angles of the reflection surfaces of 2 triangular pyramids are α / 2, α / 2 and βR respectively.

[0015] The present invention has the following technical advantages.

[0016] From the perspective of optical design, an increase in the degree of freedom of optical design means that the optical system is expected to simultaneously meet the performance indicators of more different application conditions. For Class V retroreflective films with high performance requirements, improving their wide-angle performance at large viewing angles and large incident angles, as well as the performance in the 90-degree and 0-degree azimuth orientations and their optimization and balance, have always been the focus of the research and development of Class V retroreflective film technology. The retroreflective film of the present invention has three triangular pyramids: a triangular pyramid A with the inclination angles of the pyramid faces all being α / 2, a mixed triangular pyramid B with the inclination angles of the pyramid faces being α / 2, α / 2, and βL, and a mixed triangular pyramid C with the inclination angles of the three pyramid faces being α / 2, α / 2, and βR respectively. It achieves the design freedom of the three triangular pyramids. The bottom area ratios of the three triangular pyramids A, B, and C are 50%, 25%, and 25% respectively, which can reasonably optimize the performance under different application conditions, thereby obtaining a wide-angle performance improvement that cannot be achieved by the microprism retroreflective film with the traditional triangular pyramid unit structure or the double triangular pyramid combination structure, as well as the optimization and balance of the overall comprehensive performance. It can further improve the performance of the retroreflective film while maintaining the simplicity of the retroreflective film structure and effectively controlling the complexity of the manufacturing of the retroreflective film mold. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below with reference to the accompanying drawings; Figure 1 is the front view of the traditional triangular pyramid; Figure 2 is the three-dimensional structure diagram of the parallelogram unit body of the present invention; Figure 3 is Figure 2 the front view of Figure 4 is the three-dimensional structure diagram of the mold substrate placed on the workbench for processing; Figure 5 is the sectional structure diagram of the fly cutter tool for processing the mold substrate; Figure 6 is the three-dimensional structure diagram of the finished mold of the microprism retroreflective film of the present invention; Figure 7 is Figure 6 the front view of Figure 3 (for intuitive viewing, the reference numerals in the figure correspond one by one Figure 8 to the reference numerals of the retroreflective film in Figure 9 is Figure 8 the front view of Figure 10 is Figure 8 the front view of the mold substrate of Figure 11 is Figure 10 the front view of the mold substrate of after being processed in step 2; Figure 12 is Figure 11 The front view of the mold substrate after being processed in Step 3; Figure 13 is Figure 12 The perspective view of Figure 14 is Figure 12 The front view of the mold substrate after being processed in Step 4; Figure 15 is Figure 14 The schematic diagram of the three-dimensional structure of Figure 16 is Figure 14 The front view of the mold substrate after being processed in Step 5; Figure 17 is Figure 16 The schematic diagram of the three-dimensional structure of Figure 18 is Figure 16 The front view of the mold substrate after being processed in Step 6; Figure 19 is Figure 18 The schematic diagram of the three-dimensional structure (i.e., the schematic diagram of the three-dimensional structure of the mold finished product in this application). Detailed implementation manners

[0018] The present invention will be further described below in conjunction with the accompanying drawings and detailed implementation manners.

[0019] The surface of the microprism retroreflective film integrating three combinations of triangular pyramids of the present invention is formed by an array of the same parallelogram unit bodies 1. Each parallelogram unit body 1 is composed of four identical triangular pyramids A, two hybrid triangular pyramids B, and two hybrid triangular pyramids C. The bottom surfaces of the triangular pyramid A, the hybrid triangular pyramid B, and the hybrid triangular pyramid C are all the same equilateral triangle. The inclination angles of the three corner surfaces of each triangular pyramid A are all α / 2. The inclination angles of the corner surfaces of the hybrid triangular pyramid B are α / 2, α / 2, and βL. The inclination angles of the three corner surfaces of the hybrid triangular pyramid C are α / 2, α / 2, and βR respectively. The triangular pyramids A are respectively the triangular pyramid A1, the triangular pyramid A2, the triangular pyramid A3, and the triangular pyramid A4. The hybrid triangular pyramids B are respectively the triangular pyramid B1 and the triangular pyramid B2. The hybrid triangular pyramids C are respectively the triangular pyramid C1 and the triangular pyramid C2. The first row of the parallelogram unit body 1 is sequentially arranged as the triangular pyramid A3, the triangular pyramid A4, the triangular pyramid C2, and the triangular pyramid B2. The second row of the parallelogram unit body 1 is sequentially arranged as the triangular pyramid C1, the triangular pyramid B1, the triangular pyramid A1, and the triangular pyramid A2. The orientations of adjacent triangular pyramids are 180 degrees to each other.

[0020] One embodiment is that the array intercept of the microprism retroreflective film is 0.433 mm, and each parallelogram unit 1 in the microprism retroreflective film contains 8 triangular pyramids with a bottom side length of 250 μm; α = 70.55 degrees, β = 70.15 degrees, βL = 35.15°, βR = 35.00°.

[0021] The pyramid surface C101 of the triangular pyramid C1 is coplanar with the pyramid surface A101 of the triangular pyramid A1, the pyramid surface A401 of the triangular pyramid A4 is coplanar with the pyramid surface B201 of the triangular pyramid B2, the pyramid surface C102 of the triangular pyramid C1 is coplanar with the pyramid surface A301 of the triangular pyramid A3, the pyramid surface A201 of the triangular pyramid A2 is coplanar with the pyramid surface B202 of the triangular pyramid B2, the pyramid surface A102 of the triangular pyramid A1 is coplanar with the pyramid surface A302 of the triangular pyramid A3, the pyramid surface A202 of the triangular pyramid A2 is coplanar with the pyramid surface A402 of the triangular pyramid A4, the pyramid surface A303 of the triangular pyramid A3 is coplanar with the pyramid surface C201 of the triangular pyramid C2, the pyramid surface B101 of the triangular pyramid B1 is coplanar with the pyramid surface A203 of the triangular pyramid A2, the pyramid surface B102 of the triangular pyramid B1 is coplanar with the pyramid surface A403 of the triangular pyramid A4, and the pyramid surface A103 of the triangular pyramid A1 is coplanar with the pyramid surface C202 of the triangular pyramid C2.

[0022] The specific processing method of the mold for manufacturing the microprism retroreflective film integrating the combination of the three types of triangular pyramids is as follows.

[0023] Example 1, as Figure 4 、 5 shown, the mold base K1 is horizontally installed on the workbench K2. The workbench can drive the mold base to move along the X-axis and Y-axis in the horizontal direction, and the B-axis turntable on the workbench can drive the mold base to rotate around the normal B-axis of the mold base. Above the mold base, there is a main shaft K3 parallel to the upper surface of the mold base and a fly cutter head K4 fixedly connected to the main shaft. The main shaft K3 can be driven to rotate by existing machine tools. A tool K5 is installed on the fly cutter head, and the tool can rotate around the Y-axis driven by the main shaft. The specific manufacturing steps are as follows: Step 1: Rotate the mold base on the B-axis turntable by an angle of 0 degrees (or 180 degrees) (i.e., Figure 9 the state shown), and use the first type of tool with a tool angle of α to process the two side cone surfaces of the parallelogram unit (i.e., Figure 10 the upper and lower side cone surfaces, and the workbench drives the mold base to move along the X-axis direction during the processing), that is, the pyramid surface C101 of the triangular pyramid C1, the pyramid surface A101 of the triangular pyramid A1, the pyramid surface A401 of the triangular pyramid A4, and the pyramid surface B201 of the triangular pyramid B2. Its inclination angle is α / 2. The first type of tool is a symmetric tool, and the two side inclination angles are the same. In one embodiment, α = 70.55 degrees, and the two side inclination angles are both 35.275 degrees, as Figure 10 shown.

[0024] Step 2: Rotate the mold substrate on the B-axis turntable by an angle of 120 degrees (or 300 degrees) (i.e., rotate counterclockwise by 120 degrees (or 300 degrees) around the center in the state shown by Figure 9 ), and use the first type of tool with a tool angle of α installed on the fly cutter head to machine the other two tapered surfaces of the parallelogram unit body (i.e., Figure 11 the left and right tapered surfaces), and during the machining process, the workbench drives the mold substrate to move along the X-axis direction), that is, the tapered surface C102 of the triangular pyramid C1, the tapered surface A301 of the triangular pyramid A3, the tapered surface A201 of the triangular pyramid A2, and the tapered surface B202 of the triangular pyramid B2, and their inclination angles are also α / 2, as shown in Figure 11 .

[0025] Step 3: Rotate the mold substrate on the B-axis turntable by an angle of 60 degrees (or 240 degrees) (i.e., rotate counterclockwise by 60 degrees (or 240 degrees) around the center in the state shown by Figure 9 ), and use the first type of tool with a tool angle of α installed on the fly cutter head to machine the tapered surfaces at two opposite corners of the parallelogram unit body 1, that is, the tapered surface A102 of the triangular pyramid A1, the tapered surface A302 of the triangular pyramid A3, the tapered surface A202 of the triangular pyramid A2, and the tapered surface A402 of the triangular pyramid A4, and their inclination angles are also α / 2, as shown in Figure 12 , 13 .

[0026] Step 4: Based on the structure after machining in Step 3, rotate the mold substrate to the 0-degree position (i.e., the position shown by Figure 9 ), and use the first type of tool to machine and form the tapered surface B101 of the triangular pyramid B1 and the tapered surface A203 of the triangular pyramid A2, and their inclination angle is α / 2; at the same time, form the tapered surface A303 of the triangular pyramid A3 and the tapered surface C201 of the triangular pyramid C2, and their inclination angle is α / 2; as shown in Figure 14 , 15 .

[0027] Step 5: Sequentially rotate the mold substrate to the 120-degree position (i.e., rotate counterclockwise by 120 degrees around the center in the position shown by Figure 9 ), and use the first type of tool to machine and form the tapered surface B102 of the triangular pyramid B1 and the tapered surface A403 of the triangular pyramid A4, and their inclination angle is α / 2, and at the same time, form the tapered surface A103 of the triangular pyramid A1 and the tapered surface C202 of the triangular pyramid C2, and their inclination angle is α / 2, as shown in Figure 16 , 17 ; Step 6: Replace and install the second type of tool with an asymmetric structure and a tool angle of β on the fly cutter disk. The left blade inclination angle of the second type of tool is βL, and the right blade inclination angle is βR, where βL ≠ βR. The inclination angle of the triangular pyramid angle cone reflection surface machined by the left blade is βL, and the inclination angle of the triangular pyramid angle cone reflection surface machined by the right blade is βR. Then, rotate the mold substrate sequentially by 60 degrees (i.e., rotate counterclockwise by 60 degrees around the center at the position shown by Figure 9 ), and use the adjusted second type of tool to machine and form the pyramid surface B103 of triangular pyramid B1 and the pyramid surface B203 of triangular pyramid B2, with an inclination angle of βL; at the same time, form the pyramid surface C103 of triangular pyramid C1 and the pyramid surface C203 of triangular pyramid C2, with an inclination angle of βR; as shown in Figure 18 , 19 .

[0028] Figure 18 , 19 That is, the schematic diagram of the structure of the finished mold of this application, Figure 18 , 19 is the same as Figure 7 , 8 . They are all schematic diagrams of the structure of the mold for making the reflective film of this application. The shape and size of the mold obtained by the above method are the same as those of the reflective film formed by the subsequent production of this mold. For the convenience of intuitive viewing, therefore Figure 7 uses the same reference numerals as Figure 2 to reflect the one-to-one correspondence between the mold and the reflective film.

[0029] So far, the mold of the microprism reflective film composed of three different triangular pyramid structures, namely, triangular pyramid A with an inclination angle of α / 2 for each, mixed triangular pyramid B with inclination angles of α / 2, α / 2, and βL, and mixed triangular pyramid C with inclination angles of α / 2, α / 2, and βR, is machined and formed.

[0030] Specific processing example of Example 1: The tool angle α of the first type of tool is 70.55 degrees; the second type of tool is an asymmetric tool with a tool angle of β = 70.15°, the left blade inclination angle βL = 35.15°, and the right blade inclination angle βR = 35.00°; when processing, first use the first type of tool, and perform array processing according to the rotation angles of the B axis being 0 degrees, 60 degrees, and 120 degrees, and the intercept being 0.433 mm. The first to third cuts processed form a large triangular pyramid frustum (side length 500 microns, referring to the aforementioned steps 1-3 and Figures 9 - 13), and then, with the rotation angles of the B-axis being 60° and 120° respectively, and the intercept being 0.433 mm, the 4th to 5th cuts are respectively machined in an array along the center connection line of the edges of the large triangular pyramid frustum; finally, the second type of tool is replaced, and with the rotation angle of the B-axis being 60° and the intercept being 0.433 mm, the 6th cut is respectively machined in an array along the center connection line of the adjacent edges of the large triangular pyramid frustum to form a composite microprism reflective film composed of a parallelogram unit array (refer to the aforementioned steps 4-6 and Figures 14 - 19 ), each parallelogram unit contains 8 triangular pyramids with a side length of 250 μm, among which the reflection surface inclination angles of 4 triangular pyramids are all α / 2, the reflection surface inclination angles of 2 triangular pyramids are α / 2, α / 2 and βL respectively, and the reflection surface inclination angles of 2 triangular pyramids are α / 2, α / 2 and βR respectively.

[0031] To verify the significant advantages of the above embodiments of the present application, a comparative example is provided below: The tool cutting angle α = 70.55 degrees, the side length of the triangular pyramid is 250 μm, and with the rotation angles of the B-axis being 0 degrees (or 180 degrees), 60 degrees (or 240 degrees), and 120 degrees (or 300 degrees) respectively, and the intercept being 216.5 μm, a conventional triangular pyramid microprism reflective film composed of the same parallelogram unit array is machined and formed. Each parallelogram unit is composed of 2 identical triangular pyramids, and the reflection surface inclination angle of the triangular pyramid is α / 2. Technical advantage description: The comparative example is a conventional triangular pyramid microprism reflective film, whose retroreflective performance is mainly distributed at a small observation angle of 0.2 degrees, and it cannot meet the requirements of Class V (V class) standard under the test conditions of an incident angle of 30 degrees, observation angles of 0.5 degrees and 1 degree, and observation angles of 1 degree, incident angles of -4 degrees and 15 degrees; the microprism reflective film prepared by the present invention is composed of three different triangular pyramids, which optimizes and improves the retroreflective performance under the test conditions of large observation angles and large incident angles, so that the retroreflective performance under all test conditions meets the requirements of Class V standard.

[0033] To improve the processing efficiency, the first cut (step 1) and the fourth cut (step 4) in the above processing steps can be carried out together (the substrate is in the 0-degree position in both steps, that is, the B-axis does not need to be rotated, and only the Y-axis of the substrate needs to be moved), and the second cut (step 2) and the fifth cut (step 5) can be carried out together (the substrate is in the 120-degree position in both steps, that is, the B-axis does not need to be rotated, and only the Y-axis of the substrate needs to be moved).

[0034] The mold obtained by the above processing is further processed by existing conventional technical means to obtain a reflective film (which is prior art and will not be elaborated here).

[0035] "Manufacturing Method of Micro Prism Reflective Film with Double Triangular Pyramid Composite Structure and Its Mold" (Publication No. CN118759624B) After machining the large triangular pyramid with the first type of tool with a tool angle of α, then machining with the second type of tool with a tool angle of β (a total of 6 machining steps and 6 operations). Although the wide-angle performance of the reflective film can be optimized to a certain extent by adjusting the angle variable of the triangular pyramid located at the center, or a certain degree of optimization of the performance at 0 degrees and 90 degrees of the reflective film can be obtained, under the same machining steps (this application also has 6 machining steps and 6 operations), although the micro prism reflective film obtained by this patent has the design freedom of two types of triangular pyramids, there is still a lack of optical design optimization freedom.

[0036] This application has three triangular pyramids: triangular pyramid A with a pyramid surface inclination angle of α / 2, hybrid triangular pyramid B with pyramid surface inclination angles of α / 2, α / 2, and βL, and hybrid triangular pyramid C with three pyramid surface inclination angles of α / 2, α / 2, and βR; it achieves the design freedom of three types of triangular pyramids. The bottom area ratios of the three types of triangular pyramids A, triangular pyramid B, and triangular pyramid C are 50%, 25%, and 25% respectively, which can further reasonably optimize the performance under different application conditions, so as to obtain an improvement in wide-angle performance that cannot be achieved by the micro prism reflective film with the traditional triangular pyramid unit structure and double triangular pyramid composite structure, as well as the optimization and balance of the overall comprehensive performance.

[0037] As a special case, when βL = βR = β / 2, it becomes a conventional symmetric structure pyramid surface. Another special case is that the pyramid surface is a symmetric structure but has an angular offset △. 1. The included angle β of the asymmetric pyramid surface is composed of the left cone surface inclination angle βL and the right cone surface inclination angle βR, that is, β = βL + βR.

[0038] 2. The pyramid surface inclination angles βL and βR with an angular offset △ are equivalent to a specific asymmetric pyramid surface inclination angle: βL = β / 2 + △, βR = β / 2 - △.

[0039] 3. When △ = 0, βL = βR = β / 2. The left and right sides of the pyramid surface are symmetric structures.

[0040] When the reflective film mold of this embodiment is formed and machined, the second type of tool with a tool angle of β is a symmetric structure tool. By adjusting the specific tool angular offset Δ value, βL = β / 2 + Δ and βR = β / 2 - Δ are obtained; the selection of the tool angular offset △ during forming and machining is equivalent to using a specific asymmetric tool βL = β / 2 + △, βR = β / 2 - △; when the tool angular offset △ changes, the included angle β between two adjacent pyramid surfaces formed by the second type of tool remains unchanged; for a given tool angle β, once the angular offset △ is selected, βL is determined accordingly, and βR is also determined accordingly. βL and βR are not two completely independent cone angle design variables, but both depend on the tool angle β of the tool and its angular offset △.

[0041] In summary, the present invention has the following technical advantages.

[0042] From the perspective of optical design, an increase in the degree of freedom of optical design means that the optical system is expected to simultaneously meet the performance indicators of more different application conditions. For Class V retroreflective films with high performance requirements, improving their wide-angle performance at large viewing angles and large incident angles, as well as the performance in the 90-degree and 0-degree azimuth orientations and their optimization and balance, have always been the focus of the research and development of Class V retroreflective film technology. The retroreflective film of the present invention has a triangular pyramid A with a pyramid surface inclination angle of α / 2, a mixed triangular pyramid B with pyramid surface inclination angles of α / 2, α / 2, and βL, and a mixed triangular pyramid C with three pyramid surface inclination angles of α / 2, α / 2, and βR. It achieves the design freedom of three triangular pyramids. The bottom area ratios of the three triangular pyramids A, B, and C are 50%, 25%, and 25% respectively, which can reasonably optimize the performance under different application conditions, thereby obtaining an improvement in wide-angle performance that cannot be achieved by the microprism retroreflective film with the traditional triangular pyramid unit structure or the double triangular pyramid combination structure, as well as the optimization and balance of the overall comprehensive performance.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that it is still possible to modify the specific implementation manners of the present invention or perform equivalent replacements for some technical features without departing from the spirit of the technical solutions of the present invention, and they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A microprism retroreflective film integrating a combination of three triangular pyramids, characterized in that: The surface of the microprism retroreflective film is formed by an array of identical parallelogram unit cells (1). Each parallelogram unit cell (1) is composed of four identical triangular pyramids A, two hybrid triangular pyramids B, and two hybrid triangular pyramids C. The bases of the triangular pyramid A, the hybrid triangular pyramid B, and the hybrid triangular pyramid C are all identical equilateral triangles. The inclination angles of the three pyramidal faces of each triangular pyramid A are all α / 2. The inclination angles of the pyramidal faces of the hybrid triangular pyramid B are α / 2, α / 2, and βL. The inclination angles of the three pyramidal faces of the hybrid triangular pyramid C are α / 2, α / 2, and βR respectively, and βL is not equal to βR. The triangular pyramids A are respectively triangular pyramid A1, triangular pyramid A2, triangular pyramid A3, and triangular pyramid A4. The hybrid triangular pyramids B are respectively triangular pyramid B1 and triangular pyramid B2. The hybrid triangular pyramids C are respectively triangular pyramid C1 and triangular pyramid C2. In the first row of the parallelogram unit cell (1), they are arranged in sequence as triangular pyramid A3, triangular pyramid A4, triangular pyramid C2, and triangular pyramid B2. In the second row of the parallelogram unit cell (1), they are arranged in sequence as triangular pyramid C1, triangular pyramid B1, triangular pyramid A1, and triangular pyramid A2. The orientations of adjacent triangular pyramids are 180 degrees to each other.

2. The microprism retroreflective film integrating three combinations of triangular pyramids according to claim 1, wherein: The pyramidal face C101 of the triangular pyramid C1 is coplanar with the pyramidal face A101 of the triangular pyramid A1. The pyramidal face A401 of the triangular pyramid A4 is coplanar with the pyramidal face B201 of the triangular pyramid B2. The pyramidal face C102 of the triangular pyramid C1 is coplanar with the pyramidal face A301 of the triangular pyramid A3. The pyramidal face A201 of the triangular pyramid A2 is coplanar with the pyramidal face B202 of the triangular pyramid B2. The pyramidal face A102 of the triangular pyramid A1 is coplanar with the pyramidal face A302 of the triangular pyramid A3. The pyramidal face A202 of the triangular pyramid A2 is coplanar with the pyramidal face A402 of the triangular pyramid A4. The pyramidal face A303 of the triangular pyramid A3 is coplanar with the pyramidal face C201 of the triangular pyramid C2. The pyramidal face B101 of the triangular pyramid B1 is coplanar with the pyramidal face A203 of the triangular pyramid A2. The pyramidal face B102 of the triangular pyramid B1 is coplanar with the pyramidal face A403 of the triangular pyramid A4. The pyramidal face A103 of the triangular pyramid A1 is coplanar with the pyramidal face C202 of the triangular pyramid C2.

3. The microprism retroreflective film integrating three combinations of triangular pyramids according to claim 2, characterized in that: The proportion of the base areas of the triangular pyramid A, the hybrid triangular pyramid B, and the hybrid triangular pyramid C is 50%, 25%, and 25% respectively.

4. The microprism retroreflective film integrating three combinations of triangular pyramids according to claim 3, characterized in that: α = 70.55 degrees, β = 70.15 degrees, βL = 35.15°, βR = 35.00°.

5. The microprism retroreflective film integrating three combinations of triangular pyramids according to claim 4, characterized in that: The array intercept of the microprism retroreflective film is 0.433 mm. Each parallelogram unit cell (1) in the microprism retroreflective film contains 8 triangular pyramids with a base side length of 250 μm.

6. A manufacturing method of a mold for a microprism retroreflective film integrating three combinations of triangular pyramids, which is used to manufacture a mold for a microprism retroreflective film integrating three combinations of triangular pyramids as described in any one of claims 1 - 5, and is characterized in that: The mold substrate (K1) is horizontally installed on the workbench (K2). The workbench can drive the mold substrate to move along the X-axis and Y-axis in the horizontal direction, and the B-axis turntable on the workbench can drive the mold substrate to rotate around the normal B-axis of the mold substrate. Above the mold substrate, there is a main shaft (K3) parallel to the upper surface of the mold substrate and a fly cutter disk (K4) fixedly connected to the main shaft. A cutter (K5) is installed on the fly cutter disk, and the cutter can rotate around the Y-axis driven by the main shaft. The specific manufacturing steps are as follows: Step 1: Rotate the mold substrate on the B-axis turntable by an angle of 0 degrees, and use the first type of cutter with a cutter angle of α installed on the fly cutter disk to machine the two side conical surfaces of the parallelogram unit body, that is, the conical surface C101 of the triangular pyramid C1, the conical surface A101 of the triangular pyramid A1, the conical surface A401 of the triangular pyramid A4, and the conical surface B201 of the triangular pyramid B2. The inclination angle is α / 2. The first type of cutter is a symmetric cutter, and the inclination angles on both sides are the same; Step 2: Rotate the mold substrate on the B-axis turntable by an angle of 120 degrees, and use the first type of cutter with a cutter angle of α installed on the fly cutter disk to machine the other two side conical surfaces of the parallelogram unit body, that is, the conical surface C102 of the triangular pyramid C1, the conical surface A301 of the triangular pyramid A3, the conical surface A201 of the triangular pyramid A2, and the conical surface B202 of the triangular pyramid B2. The inclination angle is also α / 2; Step 3: Rotate the mold substrate on the B-axis turntable by an angle of 60 degrees, and use the first type of cutter with a cutter angle of α installed on the fly cutter disk to machine the conical surfaces at the two opposite corners of the parallelogram unit body (1), that is, the conical surface A102 of the triangular pyramid A1, the conical surface A302 of the triangular pyramid A3, the conical surface A202 of the triangular pyramid A2, and the conical surface A402 of the triangular pyramid A4. The inclination angle is also α / 2; Step 4: On the basis of the structure machined in Step 3, rotate the mold substrate to the 0-degree position, and use the first type of cutter to machine and form the conical surface B101 of the triangular pyramid B1 and the conical surface A203 of the triangular pyramid A2. The inclination angle is α / 2; at the same time, form the conical surface A303 of the triangular pyramid A3 and the conical surface C201 of the triangular pyramid C2. The inclination angle is α / 2; Step 5: Rotate the mold substrate to 120 degrees in sequence, and use the first type of cutter to machine and form the conical surface B102 of the triangular pyramid B1 and the conical surface A403 of the triangular pyramid A4. The inclination angle is α / 2, and at the same time, form the conical surface A103 of the triangular pyramid A1 and the conical surface C202 of the triangular pyramid C2. The inclination angle is α / 2; Step 6: Replace and install the second type of tool with an asymmetric structure and a tool angle of β on the fly cutter disk. The left blade inclination angle of the second type of tool is βL, and the right blade inclination angle is βR, where βL ≠ βR. The inclination angle of the triangular pyramid angle cone reflecting surface machined by the left blade is βL, and the inclination angle of the triangular pyramid angle cone reflecting surface machined by the right blade is βR. Then, rotate the mold substrate sequentially by 60 degrees, and use the adjusted second type of tool to machine and form the pyramid surface B103 of triangular pyramid B1 and the pyramid surface B203 of triangular pyramid B2, with an inclination angle of βL; at the same time, form the pyramid surface C103 of triangular pyramid C1 and the pyramid surface C203 of triangular pyramid C2, with an inclination angle of βR. So far, the mold of the microprism reflective film composed of three different triangular pyramid structures, namely triangular pyramids A with an inclination angle of α / 2, mixed triangular pyramids B with inclination angles of α / 2, α / 2, and βL, and mixed triangular pyramids C with inclination angles of α / 2, α / 2, and βR, is machined and formed.

7. The manufacturing method of the mold of the microprism reflective film integrating three triangular pyramid combinations according to claim 6, characterized in that: The tool angle of the first type of tool α = 70.55 degrees; the second type of tool is an asymmetric tool with a tool angle of β = 70.15°, the left blade inclination angle βL = 35.15°, and the right blade inclination angle βR = 35.00°. During machining, first use the first type of tool, and perform array machining according to the B-axis rotation angles of 0 degrees, 60 degrees, and 120 degrees, with an intercept of 0.433 mm. The first to third machining cuts form a large triangular pyramid frustum. Then, perform array machining of the fourth to fifth cuts along the center line connection of the large triangular pyramid frustum side lines according to the B-axis rotation angles of 0° and 120°, with an intercept of 0.433 mm. Finally, replace the second type of tool, and perform array machining of the sixth cut along the center line connection of the adjacent side lines of the large triangular pyramid frustum according to the B-axis rotation angle of 60° and an intercept of 0.433 mm to form a composite microprism reflective film composed of a parallelogram unit array. Each parallelogram unit contains 8 triangular pyramids with a side length of 250 μm. Among them, the reflection surface inclination angles of 4 triangular pyramids are all α / 2, the reflection surface inclination angles of 2 triangular pyramids are α / 2, α / 2, and βL respectively, and the reflection surface inclination angles of 2 triangular pyramids are α / 2, α / 2, and βR respectively.

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