Photomask and method for using same to manufacture light-transmitting sheet based on total internal reflection

Abstract

A photomask (2), comprising a substrate (210) and a perforated array (220) provided on the substrate (210), wherein in the perforated array (220), the centers of two adjacent perforations (221) in the same column are separated by a first distance (Px), and the centers of two adjacent perforations (221) in the same row are separated by a second distance (Py). When the photomask (2) is used to manufacture a light-transmitting sheet (1) based on total internal reflection, by means of the configuration of the perforated array (220), and by moving the photomask (2) in the column direction and / or the row direction relative to an optical material (3) in different exposure stages, a closely stacked total internal reflection optical structure (112) can be formed on the optical material (3). When the light-transmitting sheet (1) is applied to a display apparatus, incident light rays can be reflected to the maximum extent, thereby improving the picture quality of the display apparatus.

Description

Photomask and method for manufacturing light-transmitting sheet based on total internal reflection using the same

[0001] Cross-references

[0002] This application refers to Chinese Patent Application No. 2023112912159, filed on October 7, 2023, entitled “Photomask and method for manufacturing a light-transmitting sheet based on total internal reflection using the same”, which is incorporated into this application in its entirety by reference. Technical Field

[0003] The present application relates to the field of display technology, and in particular to a photomask and a method for manufacturing a light-transmitting sheet based on total internal reflection using the same. Background Art

[0004] A conventional TIR-based display comprises a transparent front film and a rear support film. The outer surface of the transparent front film faces the viewer, and the inner surface is provided with a light-transmitting sheet with a high refractive index, which has a convex structure array (also called a lens array). In addition, a transparent front electrode is provided on the surface of the convex structure array, and a rear electrode is provided on the rear support portion. Moreover, a low-refractive-index fluid containing a plurality of light-absorbing electrophoretic mobile particles is filled between the front electrode and the rear electrode. When the electrophoretic mobile particles move to the transparent front electrode and enter the evanescent wave region, they may destroy the total internal reflection (TIR), allowing the incident light to enter the display. When the electrophoretic mobile particles move out of the evanescent wave region, the incident light may undergo total internal reflection at the interface between the dielectric layer surface on the convex structure array and the low-refractive-index fluid.

[0005] Among them, in order to maximize the light reflected from the array of raised structures, the raised structures in the raised structure array need to be placed as close to each other as possible. Typically, a photoresist is coated on a substrate through a photolithography process, and a photomask is placed above the photoresist coating. The photoresist coating is then exposed using a high-intensity light source. After exposure, the photoresist coating is developed, leaving the desired pattern on the substrate. However, when creating densely packed raised structures, the multiple patterns on the photomask need to be very close to each other. This poses a considerable challenge because during the exposure process, when light passes through these tightly packed patterns, it optically interferes with each other, resulting in a reduction in the light intensity reaching the photoresist, and there is not enough light intensity for these raised structures to form on the substrate.

[0006] Summary of the Invention

[0007] Various aspects of the present application provide a photomask and a method for using the same to manufacture a light-transmitting sheet based on total internal reflection, so as to solve the problem that a densely packed array of protruding structures cannot be formed on the light-transmitting sheet when the light-transmitting sheet is manufactured using a photolithography process.

[0008] An embodiment of the present application provides a photomask, comprising: a substrate and a perforation array arranged on the substrate, the perforation array comprising a plurality of perforations in m rows × n columns, wherein the radius of the perforations is R, R>0, m and n are respectively positive integers greater than 1, and the centers of two adjacent perforations in the same column are separated by a first distance, and the centers of two adjacent perforations in the same row are separated by a second distance, the first distance is 4R, and the second distance is between 2R and 4R.

[0009] In some embodiments, the second distance is between 2.5R and 3.5R.

[0010] In some embodiments, the second distance is 2R√3.

[0011] In some embodiments, the closest distance between two adjacent through-holes in the same row is 2R.

[0012] In some embodiments, the farthest distance between two adjacent through-holes in the same row is 6R.

[0013] In some embodiments, the perforations are circular or hexagonal.

[0014] In some embodiments, the through-holes are hexagonal, and the maximum width of the through-holes in the column direction is 2R, and the maximum length of the through-holes in the row direction is between R and 1.5R.

[0015] In some embodiments, the maximum length in the row direction is 2R / √3.

[0016] In some embodiments, the ratio of the first distance to the second distance is expressed by the following equation:

[0017] Wherein Px is the first distance, and Py is the second distance.

[0018] In some embodiments, the ratio of the first distance to the second distance is expressed by the following equation:

[0019] Wherein Px is the first distance, and Py is the second distance.

[0020] The present application also provides a method for manufacturing a light-transmitting sheet based on total internal reflection, comprising: providing an optical material coated with photoresist; providing a photomask as described in any of the above embodiments above the optical material; exposing the optical material through the perforated array of the photomask to form a first array of total internal reflection optical structures; moving the photomask in a forward direction along the column direction by a first predetermined distance, wherein the first predetermined distance is 2R; exposing the optical material through the perforated array to form a second array of the total internal reflection optical structures; moving the photomask in a reverse direction along the column direction by a second predetermined distance, and in a row direction by a third predetermined distance, wherein the second predetermined distance is R and the third predetermined distance is between 1.5R and 2R; exposing the optical material through the perforated array to form a third array of the total internal reflection optical structures; moving the photomask in a forward direction along the column direction by a fourth predetermined distance, wherein the fourth predetermined distance is 2R; and exposing the optical material through the perforated array to form a fourth array of the total internal reflection optical structures.

[0021] In some embodiments, the manufacturing method further includes: performing a developing and curing process on the total internal reflection optical structure to form an optical structure array on the optical material.

[0022] In some embodiments, the third predetermined distance is R√3.

[0023] In some embodiments, the manufacturing method further includes: performing heat treatment or photolithography patterning on the optical structure array to shape the total internal reflection optical structure into a lens structure with a curved surface.

[0024] In some embodiments, the diameter of the total internal reflection optical structure is in the range of 0.5-500 microns.

[0025] In some embodiments, the diameter of the total internal reflection optical structure is in the range of 0.5-20 microns.

[0026] In an embodiment of the present application, the perforation array of the photomask includes a plurality of perforations arranged in m rows by n columns. The centers of two adjacent perforations in the same column are separated by a first distance, and the centers of two adjacent perforations in the same row are separated by a second distance. The first and second distances correspond to the radius of the perforations, respectively. Therefore, when the photomask is used in the manufacture of a light-transmitting sheet based on total internal reflection, interference between adjacent perforations after the irradiating light passes through the perforation array can be avoided during the exposure step.

[0027] Furthermore, by moving the photomask an appropriate distance before performing the exposure process, the resulting total internal reflection optical structures can be brought closer together. In some embodiments, these structures can even touch each other, resulting in a light-transmitting sheet with a tightly packed array of optical structures. When used in a display device, this sheet can also partially or completely eliminate moiré patterns by overlapping with the black matrix of a color filter, improving image quality.

[0028] Furthermore, the manufacturing process of the light-transmitting sheet based on total internal reflection can be completed using existing photolithography technology, which not only eliminates the need for additional costs for process development and design, but also improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0030] FIG1 is a schematic plan view of a light-transmitting sheet based on total internal reflection according to an embodiment of the present application.

[0031] 2 and 3 are respectively plan views of photomasks according to embodiments of the present application.

[0032] FIG4 is a flow chart of a method for manufacturing a light-transmitting sheet based on total internal reflection according to an embodiment of the present application.

[0033] FIG5 is a plan view schematically showing a first array formed on an optical material according to an embodiment of the present application.

[0034] FIG6 is a plan view schematically showing a second array formed on an optical material according to an embodiment of the present application.

[0035] FIG. 7 is a plan view schematically showing a third array formed on an optical material according to an embodiment of the present application.

[0036] FIG8 is a plan view schematically showing a fourth array formed on an optical material according to an embodiment of the present application. DETAILED DESCRIPTION

[0037] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the specific embodiments of this application and the corresponding drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0038] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0039] As shown in FIG1 , in an embodiment of the present application, an optical structure array 110 on a light-transmitting sheet 1 based on total internal reflection can be manufactured using a photolithography process. In certain embodiments, the total internal reflection optical structures 112 in the optical structure array 110 can be circular or hexagonal in shape. Furthermore, to maximize the reflected light and ultimately improve the brightness of the display, the total internal reflection optical structures 112 can be as close as possible (e.g., touching each other) to reduce unused space 114 around the total internal reflection optical structures 112.

[0040] Please refer to Figures 2 and 3. An embodiment of the present application provides a photomask 2 for producing a light-transmitting sheet 1 having a tightly packed total internal reflection optical structure 112 in a photolithography process. The photomask 2 may include a substrate 210 and a perforation array 220 consisting of a plurality of perforations 221 distributed on the substrate. The substrate 210 may be, but is not limited to, made of a material such as a polymer, glass, metal, or a combination thereof. The hole sizes of the plurality of perforations 221 and the spacing between adjacent holes are appropriate, and these perforations 221 respectively penetrate the two opposite sides of the substrate 210 to allow light to pass through. The hole sizes and spacing of the plurality of perforations 221 may be determined based on the final size of the desired total internal reflection optical structure and the spacing distance from the adjacent total internal reflection optical structure.

[0041] In an embodiment of the present application, a plurality of through-holes 221 are arranged on the substrate 210 in a pattern of m rows × n columns along the row direction y and the column direction x, respectively, where m and n are positive integers greater than 1, such as 2 rows × 2 columns or 2 rows × 3 columns, etc. The above is merely an example and is not intended to be limiting. In addition, in some embodiments of the present application, the through-holes 221 may be substantially circular (as shown in FIG. 2 ), with a radius R, where R>0. In other embodiments of the present application, the through-holes 221 may be hexagonal (as shown in FIG. 3 ), with a maximum width W (i.e., the distance between two opposite sides) in the column direction x being 2R, and a maximum length L (i.e., the distance between the two most distant vertices in the row direction) in the row direction y being between R and 1.5R, such as 2R / √3.

[0042] Please refer to Figure 2. It is worth noting that in the perforation array 220, the centers of two adjacent perforations 221 in the same column are separated by a first distance Px, and the centers of two adjacent perforations 221 in the same row are separated by a second distance Py, where the first distance Px is 4R and the second distance Py is between 2R and 4R. For example, in some embodiments of the present application, the second distance Py is between 2.5R and 3.5R. And, in other embodiments of the present application, the second distance is 2R√3. In addition, regarding the relative spatial positions of the plurality of perforations 221, the shortest distance Ps between the aperture edges of two adjacent perforations 221 in the same column is approximately 2R, or the longest distance Pl between the aperture edges of two adjacent perforations in the same column is approximately 6R. In some embodiments of the present application, a configuration can also be adopted in which both the shortest distance Ps is approximately 2R and the longest distance Pl is approximately 6R.

[0043] Please refer to Figures 1, 2, 4 to 8. The photomask provided in the embodiment of the present application can be applied to a photolithography process to produce a light-transmitting sheet with a tightly packed total internal reflection optical structure. The manufacturing method is as follows:

[0044] Step S101: Provide an optical material 3 coated with a photoresist. The optical material 3 may be glass, polymer, or a combination thereof. The photoresist forms an exposure area on the optical material 3.

[0045] In step S102 , the photomask 2 disclosed in the embodiment of the present application is provided and placed on top of the photoresist to above the optical material 3 , such that the positions of the photoresist corresponding to the plurality of through-holes 221 are exposed to the first exposure area.

[0046] In step S103, the optical material 3 is exposed through the perforation array 220 of the photomask 2 to form a first array 410 of total internal reflection optical structures 112. In this step, high-intensity light is irradiated onto the photomask 2, allowing the light to pass through the plurality of perforations 221 and reach the photoresist. This forms the first array 410 on the optical material 3, which matches the plurality of perforations 221 and includes a plurality of total internal reflection optical structures 112.

[0047] In step S104, the photomask 2 is moved forward along the column direction x by a first predetermined distance, which is 2R. Since the radius of the through-holes 221 is R, the distance between two adjacent through-holes 221 in the same column is 2R, and the distance between the centers of the two through-holes 221 is 4R, when the photomask 2 is shifted rightward along the column direction x by a distance of 2R, each through-hole 221 on the photomask 2 is precisely located between two adjacent total internal reflection optical structures 112 in the first array 410, exposing the locations on the photoresist corresponding to the plurality of through-holes 221 as the second exposure area.

[0048] In step S105, the optical material 3 is exposed through the perforation array 220 to form a second array of total internal reflection optical structures 112. In this step, high-intensity light is again irradiated for a second exposure, thereby forming a second array 420 on the optical material 3 that matches the plurality of perforations 221 and includes a plurality of total internal reflection optical structures 112, which are represented by circles filled with black dots.

[0049] In step S106, the photomask is shifted in the opposite direction along the column direction by a second predetermined distance and along the row direction by a third predetermined distance, where the second predetermined distance is R and the third predetermined distance is between 1.5R and 2R, for example, R√3. On the photomask 2, the radius of the perforations 221 is R, the distance between two adjacent perforations 221 in the same column is 2R, and the distance between the centers of the two perforations 221 is 4R; and the centers of two adjacent perforations 221 in the same row are spaced 2R to 4R apart. Therefore, when the photomask 2 is shifted to the left by a distance R along the column direction x, each perforation 221 is positioned precisely between the total internal reflection optical structures 112 of the first array 410 and the second array 420.

[0050] Next, when the photomask 2 moves up or down a distance of 2R to 4R along the column direction y, each through-hole 221 moves above or below the total internal reflection optical structures 112 of the first array 410 and the second array 420, and is located between the total internal reflection optical structures 112 of the first array 410 and the second array 420 in the row direction. At the same time, it is close to the edge of the total internal reflection optical structure 112, so that the positions corresponding to the multiple through-holes 221 on the photoresist are exposed as the third exposure area.

[0051] In step S107, the optical material is exposed through the perforated array to form a third array of total internal reflection optical structures. Similarly, high-intensity light can be used to illuminate the third exposure area and perform a third exposure process. This forms a third array 430 containing a plurality of total internal reflection optical structures 112 on the optical material, which is represented by a circle filled with diagonal lines.

[0052] In step S108, the photomask is moved forward along the column direction by a fourth predetermined distance, which is 2R. Similar to step S104, the photomask 2 is moved forward along the column direction x by a fourth predetermined distance, which is also 2R. Therefore, when the photomask 2 is shifted rightward along the column direction x by a distance of 2R, the through-holes 221 on the photomask 2 are precisely located between the total internal reflection optical structures 112 of the first array 410, the second array 420, and the third array 430, exposing the locations on the photoresist corresponding to the through-holes 221 as the fourth exposure area.

[0053] In step S109, the optical material is exposed through the perforated array to form a fourth array of total internal reflection optical structures. In this step, high-intensity light is irradiated for a fourth exposure, thereby forming a fourth array 440 on the optical material 3 that matches the plurality of perforations 221 and includes a plurality of total internal reflection optical structures 112, represented by circles filled with cross lines. This results in four arrays of total internal reflection optical structures 112, each of which is staggered, with adjacent total internal reflection optical structures 112 having a minimized distance between them, and arranged adjacently along the row direction y and the column direction x.

[0054] In step S110, the total internal reflection optical structure 112 is subjected to a development and curing process to form an optical structure array 110 on the optical material. After the development and curing process, the multiple total internal reflection optical structures 112 in the first array 410 to the fourth array 440 can be formed into an optical structure array 110 having a densely packed structure and staggered along the column direction x and the row direction y using a photolithography process. In addition, in some embodiments of the present application, the above-mentioned manufacturing method further includes: performing heat treatment or photolithographic patterning on the optical structure array 110 to shape the total internal reflection optical structure into a lens structure with a curved surface, so as to obtain the desired total internal reflection optical structure according to different requirements.

[0055] It is understood that in some embodiments of the present application, the steps of developing and curing the total internal reflection optical structure 112 can also be performed after the exposure step. In addition, in some embodiments, the total internal reflection optical structure 112 can be directly formed on the color filter through a photolithography process.

[0056] It is worth noting that in the aforementioned photolithography process, since the distance between the multiple perforations 221 on the photomask 2 is sufficiently large, artifacts due to optical interference are eliminated during the exposure step. Furthermore, the photolithography process using the photomask of the present embodiment can reduce the distance between adjacent total internal reflection optical structures 112 to zero. Therefore, when the light-transmitting sheet 1 based on total internal reflection is applied to a display device, it can maximize the light reflected from the optical structure array 110, improving display quality and enhancing the user experience.

[0057] In an exemplary embodiment, the optical structure array 110 formed by the above steps can be composed of a high-refractive-index polymer. In some embodiments, the total internal reflection optical structures can be hemispherical. In other embodiments, the total internal reflection optical structures can be arranged in a tightly packed manner and can be of any shape or size, or a combination of shapes and sizes. Furthermore, the total internal reflection optical structures can be elongated hemispherical, hexagonal, or a combination of the two.

[0058] Furthermore, the total internal reflection optical structure may have a refractive index of approximately 1.4 or higher. In one embodiment, the refractive index of the total internal reflection optical structure may be in the range of approximately 1.5-1.9. In some embodiments, the total internal reflection optical structure may comprise a material having a refractive index between approximately 1.5 and 2.2. In other embodiments, the high refractive index total internal reflection optical structure may be comprised of a material having a refractive index between approximately 1.6 and 1.9.

[0059] Furthermore, in terms of size, the diameter of the total internal reflection optical structure may be at least about 0.5 micrometers (μm). In other embodiments, the diameter of the total internal reflection optical structure may be at least about 2 micrometers. In certain embodiments, the diameter of the total internal reflection optical structure may be in the range of about 0.5-5000 micrometers. In other embodiments, the diameter of the total internal reflection optical structure may be in the range of about 0.5-500 micrometers, such as about 0.5-100 micrometers or about 0.5-20 micrometers. The height of the total internal reflection optical structure may be at least about 0.5 micrometers. In certain embodiments, the height of the total internal reflection optical structure may be in the range of about 0.5-5000 micrometers. In other embodiments, the height of the total internal reflection optical structure may be in the range of about 0.5-500 micrometers. In some embodiments, the height of the total internal reflection optical structure may be in the range of about 0.5-500 micrometers, such as about 0.5-15 micrometers.

[0060] Additionally, the high refractive index polymer used to form the total internal reflection optical structure may contain a high refractive index additive, such as a metal oxide, which may be, but is not limited to, one or more of SiO2, ZrO2, ZnO2, ZnO, or TiO2.

[0061] And in application, when the light-transmitting sheet with a tightly packed structure formed by the above steps is covered on a repeated pattern in a display, for example, on a black matrix for a color filter, due to the spatial frequency difference of the pattern in a specific direction between the light-transmitting sheet and the black matrix, the viewer may see a moiré pattern, which is a pattern caused by optical interference and may reduce the image quality. The photomask provided in the embodiment of the present application and the method for manufacturing a light-transmitting sheet based on total internal reflection using the same can control the spacing of the moiré pattern by adjusting the spacing of the pattern on the photomask in the column direction x and the row direction y to correspond to the spacing of the repeated pattern of the black matrix. By making the spacing of the moiré pattern an integer multiple of the repeated pattern in a specific direction, the spacing of the moiré pattern can be shortened and matched with the spacing of the repeated pattern. Therefore, the visibility of the moiré pattern will be greatly reduced, and the image quality of the display will be greatly improved.

[0062] In the embodiment corresponding to FIG2 , the number of observed moiré patterns can be limited by adjusting the ratio of the first distance Px to the second distance Py between the plurality of perforations 221 on the photomask 2. The range of the ratio of the first distance Px to the second distance Py can be expressed by the following equation (1):

[0063] For example, Py / Px=0.866, 0.870, 0.909 or 1.0, wherein when Py / Px=1.0, the influence of moiré can be eliminated.

[0064] In the embodiment corresponding to FIG2 , the amount of observed moiré patterns can be limited by adjusting the ratio of the first distance Px to the second distance Py between the plurality of perforations 221 on the photomask 2. The range of the ratio of the first distance Px to the second distance Py can be expressed by the following equation (2):

[0065] For example, Py / Px=1.1547, 1.1585, 1.1976 or 1.28876, etc., wherein when Py / Px=1.28876, the influence of the moiré pattern can be eliminated.

[0066] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A photomask, characterized in that: include: A substrate and a perforation array arranged on the substrate, wherein the perforation array includes a plurality of perforations of m rows×n columns, wherein the radius of the perforation is R, R>0, m and n are positive integers greater than 1, respectively, and the centers of two adjacent perforations in the same column are separated by a first distance, and the centers of two adjacent perforations in the same row are separated by a second distance, the first distance is 4R, and the second distance is between 2R and 4R.

2. The photomask according to claim 1, wherein: The second distance is between 2.5R and 3.5R.

3. The photomask according to claim 1, wherein: The second distance is 2R√3.

4. The photomask according to claim 1, wherein: The shortest distance between the aperture edges of two adjacent through holes in the same row is 2R.

5. The photomask according to claim 1, wherein: The longest distance between the aperture edges of two adjacent through holes in the same row is 6R.

6. The photomask according to claim 1, wherein: The perforations are circular or hexagonal.

7. The photomask according to claim 6, wherein: The perforations are hexagonal, and the maximum width of the perforations in the column direction is 2R, and the maximum length of the perforations in the row direction is between R and 1.5R.

8. The photomask according to claim 7, wherein: The maximum length in the row direction is 2R / √3.

9. The photomask according to claim 1, wherein: The ratio of the first distance to the second distance is expressed by the following equation: Wherein Px is the first distance, and Py is the second distance.

10. The photomask according to claim 1, wherein: The ratio of the first distance to the second distance is expressed by the following equation: Wherein Px is the first distance, and Py is the second distance.

11. A method for manufacturing a light-transmitting sheet based on total internal reflection, characterized in that: include: providing an optical material coated with a photoresist; Providing a photomask as claimed in any one of claims 1 to 10 above the optical material; exposing the optical material through the perforated array of the photomask to form a first array of total internal reflection optical structures; Moving the photomask in a column direction by a first predetermined distance, wherein the first predetermined distance is 2R; exposing the optical material through the perforated array to form a second array of total internal reflection optical structures; Move the photomask in the opposite direction along the column direction by a second predetermined distance, and move it along the row direction by a third predetermined distance, wherein the second predetermined distance is R, and the third predetermined distance is between 1.5R and 2R; exposing the optical material through the perforated array to form a third array of total internal reflection optical structures; Moving the photomask in the column direction by a fourth predetermined distance, wherein the fourth predetermined distance is 2R; as well as The optical material is exposed through the perforated array to form a fourth array of total internal reflection optical structures.

12. The manufacturing method according to claim 11, characterized in that: Also includes: The total internal reflection optical structure is subjected to a developing and curing process to form an optical structure array on the optical material.

13. The manufacturing method according to claim 11, characterized in that: The third predetermined distance is R√3.

14. The manufacturing method according to claim 11, characterized in that: Also includes: The optical structure array is subjected to heat treatment or photolithography patterning to shape the total internal reflection optical structure into a lens structure with a curved surface.

15. The manufacturing method according to claim 11, characterized in that: The diameter of the total internal reflection optical structure is in the range of 0.5-500 microns.

16. The manufacturing method according to claim 15, characterized in that: The diameter of the total internal reflection optical structure is in the range of 0.5-20 microns.

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