WO2021169722A1 - 一种准直膜及其制备方法 - Google Patents

一种准直膜及其制备方法 Download PDF

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WO2021169722A1
WO2021169722A1 PCT/CN2021/074161 CN2021074161W WO2021169722A1 WO 2021169722 A1 WO2021169722 A1 WO 2021169722A1 CN 2021074161 W CN2021074161 W CN 2021074161W WO 2021169722 A1 WO2021169722 A1 WO 2021169722A1
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collimating
layer
hole
array
light
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PCT/CN2021/074161
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English (en)
French (fr)
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李刚
夏寅
付坤
高斌基
王小凯
陈建文
唐海江
张彦
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宁波激智科技股份有限公司
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Publication of WO2021169722A1 publication Critical patent/WO2021169722A1/zh

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/30—Collimators
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/0006—Arrays
    • G02B3/0037—Arrays characterized by the distribution or form of lenses

Definitions

  • the invention relates to a collimating film, in particular to a collimating film in the field of image recognition and a preparation method thereof.
  • collimating devices In the field of image recognition, commonly used image sensors such as CMOS type or photo-TFT type, sensor modules generally contain collimating devices to enhance the signal-to-noise ratio, improve the recognition rate, and reduce crosstalk.
  • the function of the collimating device is mainly to collimate and filter the diffused light at a single point pixel of the image, and the normal collimated light or light (signal) that is close to collimation can be smoothly transmitted to At the corresponding photoelectric sensor, the large-angle light (noise) that deviates from the normal direction can only seldom or even not enter the non-corresponding photoelectric sensor, so the signal-to-noise ratio is enhanced.
  • Collimation devices usually have a top collimation structure layer and a bottom collimation structure layer:
  • the top and bottom double-layer collimation structures need to be accurately aligned, otherwise the signal light intensity will be greatly reduced (as shown in Figure 2);
  • Traditional collimating devices are generally rigid collimating plates, such as optical fiber bundle slices, or microlens and collimating diaphragms formed on both sides of the glass substrate.
  • Such rigid collimating plates generally need to be kept high. Thickness, on the one hand, is used to maintain the aspect ratio, on the other hand, it is used to maintain its mechanical properties and prevent breakage in the application environment.
  • this type of rigid collimator still cannot meet the application of large-size image recognition modules.
  • the overall thickness needs to be compressed such as ultra-thin large-screen mobile phones
  • it will become more brittle, more fragile, and lower production yield. Both performance and cost cannot meet the demand.
  • It is also obvious that such rigid collimating sheets are even less likely to be used in flexible image recognition modules.
  • the traditional rigid collimating sheet has high thickness, fragile and poor performance in the case of low thickness, the two-layer collimating structure (collimating diaphragm) is difficult to align, low yield, and low productivity. Large-size, ultra-thin, flexible image recognition applications.
  • the present invention provides a collimating film and a preparation method thereof.
  • the collimating film provided by the present invention only includes one layer of collimating holes, which solves the problem of difficult alignment of two layers of collimating diaphragms.
  • the present invention adopts the following technical solutions:
  • the present invention provides a collimating film, which in turn includes a collimating lens layer, a flexible substrate layer and a collimating hole layer.
  • the collimating hole layer is a collimating diaphragm.
  • the collimating film provided by the present invention only includes one layer of collimating diaphragm.
  • the collimation film provided by the present invention only includes a layer of collimation holes.
  • the collimating film sequentially includes a collimating lens layer, a flexible substrate layer and a layer of collimating holes.
  • the collimating lens layer is placed on the upper surface of the flexible substrate, and the collimating hole layer is placed on the lower surface of the flexible substrate.
  • the collimating lens layer includes a microlens array and is thick.
  • the collimating hole layer includes an array of collimating holes.
  • the collimating hole layer includes a light-shielding medium layer and a collimating hole array.
  • the collimating hole layer includes a light-shielding medium and a collimating hole array formed by hollowing out the medium.
  • each collimating hole is on the main optical axis of the corresponding microlens. Further, the center of each collimating hole is on the main optical axis of the corresponding micro lens.
  • the collimating film is perforated by the micro-focusing method, the distribution of the collimating hole array and the micro lens array are exactly the same, the center of any collimating hole is on the main optical axis of the corresponding micro lens, one-to-one high-precision alignment , Alignment deviation ⁇ 1 ⁇ m.
  • the thickness T of the flexible base layer is selected from 10-50 ⁇ m, preferably 25-38 ⁇ m.
  • micro lens arrays of the collimating lens layer are arranged in an orderly manner.
  • the microlens array of the collimating lens layer and the collimating hole array of the collimating hole layer are arranged in an orderly manner.
  • One collimating hole in the collimating hole array corresponds to a position of a micro lens in the micro lens array, and the main optical axis of the micro lens coincides with the center of the collimating hole or the deviation is less than 1 ⁇ m.
  • a micro lens corresponding to the position of a collimating hole is called the corresponding micro lens of the collimating hole.
  • the coordinates of the main optical axis of three adjacent microlenses are connected to form a regular triangle (composed of the main optical axis coordinates of three overlapping microlenses), or the main optical axis of four adjacent microlenses
  • the coordinates of are connected to form a square (connected by the coordinates of the main optical axis of four overlapping microlenses).
  • microlenses in the microlens array are closely arranged. That is, adjacent microlenses are in contact with each other or overlap each other.
  • the collimating lens array and the collimating hole array of the collimating film are both equilateral triangles (connected by the main optical axis coordinates of three overlapping microlenses) closely arranged, or square (comprised of four overlapping The main optical axis coordinates of the microlenses are connected) closely arranged.
  • the distance P between the main optical axes of adjacent microlenses is 10-50 ⁇ m
  • the radius R of the microlenses is 6.1 ⁇ m-30.2 ⁇ m
  • the height H of the collimating lens layer is 1.1 ⁇ m.
  • the refractive index n1 of the collimating lens layer material is 1.4 to 1.6; in the flexible base layer, the thickness T of the flexible base layer is 10-50 ⁇ m, and the refractive index n2 of the flexible base layer material is 1.5 to 1.65; In the collimating hole layer, the thickness t of the collimating hole layer is 0.5-7 ⁇ m, and the diameter ⁇ of the collimating hole in the collimating hole array is 1-10 ⁇ m.
  • the main optical axis pitches P of the microlenses are all the same, and P is selected from 10 to 50 ⁇ m, preferably 15 to 30 ⁇ m, and more preferably 18 to 25 ⁇ m.
  • the microlenses of the collimating film focus the vertically incident light to form a light spot with a diameter of D on the lower surface of the flexible base layer.
  • D is selected from 0.1 to 7.8 ⁇ m, preferably 0.5 to 4.9 ⁇ m, and more preferably 1 to 2 ⁇ m.
  • the spot diameter D consists of the radius of curvature R (spherical radius R) of the microlens, the refractive index n1, the thickness of the collimating lens layer H (the vertical distance from the apex of the microlens to the upper surface of the substrate) and the refractive index n2 of the flexible substrate layer. T is jointly determined.
  • the radius of curvature R of the microlens is selected from 6.1 to 30.2 ⁇ m, and the thickness H of the collimating lens layer is selected from 1.1 to 27.4 ⁇ m.
  • R and H are not preferred, and adaptation is performed according to other parameters.
  • the refractive index n1 of the collimating lens layer (ie, the microlens layer) is selected from 1.4 to 1.6, preferably 1.5.
  • the refractive index n2 of the flexible base layer is selected from 1.5 to 1.65, which varies according to the material, and is not preferred, and ⁇ 0.02 errors caused by the same material and different processes are allowed.
  • the microlens array of the collimating film is made of the same thick material, and the material is all transparent polymer.
  • the transparent polymer of the microlens layer is selected from AR (Acrylic resin, acrylic resin or modified acrylic modified resin), PC (polycarbonate), PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PI (polyimide), PS (polystyrene), SR (Silicon Resin), FEP (perfluoroethylene propylene copolymer) or EVA (ethylene- Vinyl acetate copolymer). Further, it is preferably one of PMMA (polymethyl methacrylate), PC, or PS.
  • the flexible base layer of the collimating film is selected from transparent polymer films.
  • the flexible base layer can be bent.
  • the material of the transparent polymer film of the flexible base layer is selected from PET, PEN, PI, PC, PMMA (polymethyl methacrylate), PP (polypropylene), PO (polyolefin), SR or COP (Cyclic olefin copolymer). Further, it is preferably one of PET, PI, PC, or PMMA.
  • the light-shielding medium of the collimating hole layer of the collimating film is selected from one or a combination of at least two of organic coatings and inorganic coatings.
  • the organic coating of the light-shielding medium is selected from an opaque polymer ink system.
  • the opaque polymer ink system of the light-shielding medium includes a light-absorbing substance and a polymer curing system.
  • the light-absorbing material is selected from carbon (such as carbon black, carbon fiber, graphite, etc.), carbides (such as chromium carbide, titanium carbide, boron carbide, etc.), carbonitrides (such as titanium carbonitride, carbonitride, etc.) One or a combination of at least two of boron, etc.) and sulfides (such as ferrous sulfide, molybdenum disulfide, cobalt disulfide, nickel sulfide, etc.).
  • carbon such as carbon black, carbon fiber, graphite, etc.
  • carbides such as chromium carbide, titanium carbide, boron carbide, etc.
  • carbonitrides such as titanium carbonitride, carbonitride, etc.
  • sulfides such as ferrous sulfide, molybdenum disulfide, cobalt disulfide, nickel sulfide, etc.
  • the polymer curing system of the shading medium can be selected from acrylic system (AR), polyurethane system (PU), silicone resin system (SR), epoxy resin system (EP), melamine resin system (MF), One or a combination of at least two of phenolic resin system (PF), urea-formaldehyde resin system (UF), or thermoplastic elastomer (for example: ethylene-vinyl acetate copolymer, thermoplastic elastomer TPE or thermoplastic polyurethane elastomer TPU).
  • AR acrylic system
  • PU polyurethane system
  • SR silicone resin system
  • EP epoxy resin system
  • MF melamine resin system
  • PF phenolic resin system
  • UF urea-formaldehyde resin system
  • thermoplastic elastomer for example: ethylene-vinyl acetate copolymer, thermoplastic elastomer TPE or thermoplastic polyurethane elastomer TPU.
  • the polymer curing system may be selected from one or a combination of at least two of acrylic resin systems, polyurethane systems, silicone systems, epoxy resin systems, or thermoplastic elastic materials.
  • the inorganic coating of the light-shielding medium is selected from one or a combination of at least two of carbon element, carbide, carbonitride, and sulfide.
  • the thickness t of the collimating hole layer of the collimating film is selected from 0.5 to 7 ⁇ m, preferably 1 to 5 ⁇ m, and more preferably 2 to 3 ⁇ m.
  • the collimating hole diameter ⁇ of the collimating hole layer of the collimating film is selected from 1 to 10 ⁇ m, more preferably 3 to 5 ⁇ m.
  • the thickness T of the flexible base layer may be 10 ⁇ m-50 ⁇ m, for example, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 38 ⁇ m or 50 ⁇ m.
  • the main optical axis pitch P between adjacent microlenses of the collimating lens layer may be 10 ⁇ m-50 ⁇ m, for example, 10 ⁇ m, 15 ⁇ m, 18 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m or 50 ⁇ m.
  • the microlens curvature radius R of the collimating lens layer may be 6.1 ⁇ m-30.2 ⁇ m, for example, 6.1 ⁇ m, 6.9 ⁇ m, 7.9 ⁇ m, 9.4 ⁇ m, 11.2 ⁇ m, 11.3 ⁇ m, 12 ⁇ m, 12.1 ⁇ m, 12.6 ⁇ m, 12.8 ⁇ m, 13.3 ⁇ m, 13.6 ⁇ m, 14 ⁇ m, 14.3 ⁇ m, 14.3 ⁇ m, 14.8 ⁇ m, 15 ⁇ m, 15.1 ⁇ m, 15.7 ⁇ m, 15.9 ⁇ m, 16 ⁇ m, 16.1 ⁇ m, 16.7 ⁇ m, 17 ⁇ m, 17.2 ⁇ m, 17.3 ⁇ m, 18 ⁇ m, 18.1 ⁇ m, 18.3 ⁇ m, 18.8 ⁇ m, 19.3 ⁇ m, 19.4 ⁇ m, 19.6 ⁇ m, 19.8 ⁇ m, 20 ⁇ m, 20.6 ⁇ m, 20.8 ⁇ m, 21.6 ⁇ m, 22.5 ⁇ m, 25.6 ⁇ m, or 30.2 ⁇ m.
  • the thickness H of the collimating lens layer may be 1.1 ⁇ m-27.4 ⁇ m, such as 1.1 ⁇ m, 2.4 ⁇ m, 2.5 ⁇ m, 3.0 ⁇ m, 3.1 ⁇ m, 3.2 ⁇ m, 3.5 ⁇ m, 3.8 ⁇ m, 4.1 ⁇ m, 5.0 ⁇ m, 5.8 ⁇ m, 6.0 ⁇ m, 6.2 ⁇ m, 6.8 ⁇ m, 7.2 ⁇ m, 7.8 ⁇ m, 8.5 ⁇ m, 8.6 ⁇ m, 8.7 ⁇ m, 9.2 ⁇ m, 10.4 ⁇ m, 10.7 ⁇ m, 10.8 ⁇ m, 11 ⁇ m, 11.1 ⁇ m, 11.4 ⁇ m, 11.5 ⁇ m, 12.9 ⁇ m, 13.6 ⁇ m, 14.1 ⁇ m, 14.6 ⁇ m, 15.0 ⁇ m, 15.4 ⁇ m, 16.3 ⁇ m, 17.3 ⁇ m, 18.1 ⁇ m, 19.8 ⁇ m, 20.5 ⁇ m, 21.3 ⁇ m, 22.2 ⁇ m, 22.7 ⁇ m, 25 ⁇ m, or 27.4 ⁇ m.
  • the spot diameter D formed by the microlens on the lower surface of the flexible substrate layer may be 0.1 ⁇ m-7.8 ⁇ m, for example, 0.1 ⁇ m, 0.3 ⁇ m, 0.4 ⁇ m, 0.5 ⁇ m, 0.6 ⁇ m, 0.7 ⁇ m, 0.8 ⁇ m, 1.0 ⁇ m.
  • the thickness t of the collimating hole layer may be 0.5-7 ⁇ m, for example, 0.5 ⁇ m, 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, or 7 ⁇ m.
  • the collimating hole diameter ⁇ may be 1-10 ⁇ m, 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 8 ⁇ m, or 10 ⁇ m.
  • the refractive index n1 of the collimating lens layer may be 1.34-1.7, for example, 1.34, 1.4, 1.47, 1.48, 1.5, 1.59, 1.6, 1.65, 1.66, or 1.7.
  • the refractive index n2 of the flexible substrate layer may be 1.48-1.7, such as 1.48, 1.49, 1.5, 1.6, 1.65, 1.66 or 1.7.
  • the collimating film provided by the present invention includes a collimating lens layer (41), a flexible substrate layer (42) (referred to as a substrate for short), and a collimating hole layer (43).
  • the collimating lens layer is placed on the upper surface of the substrate.
  • the collimating hole layer is placed on the lower surface of the substrate, the collimating lens layer (41) includes a microlens array (41A) and the thickness (41B), and the collimating hole layer (43) includes a light-shielding medium (43A) And a collimating hole array formed by hollowing out the medium (consisting of a certain number of collimating holes (43B)).
  • the collimating lens array and the collimating hole array in the collimating film are all arranged in equilateral triangles
  • the material of the collimating lens layer (41) is PMMA
  • the flexible substrate layer (42 The material of) is PET
  • the light-shielding medium (43A) of the collimating hole layer (43) is an inorganic coating titanium carbide
  • the collimating film uses a microlens perforating method to punch the collimating hole (43B).
  • P is 10-30 ⁇ m, R is 9.4 ⁇ m-20.6 ⁇ m, H is 3 ⁇ m-27.4 ⁇ m, and n1 is 1.5;
  • T 25 ⁇ m
  • n2 1.65
  • D 0.3 ⁇ 4.0 ⁇ m
  • t 2.0 ⁇ m and ⁇ is 4.0 ⁇ m. Further, the deviation ⁇ is 0.18-0.90 ⁇ m.
  • the collimating lens array and the collimating hole array in the collimating film are all arranged in equilateral triangles
  • the material of the collimating lens layer (41) is PMMA
  • the flexible substrate layer (42) The material of is PET
  • the light-shielding medium (43A) of the collimating hole layer (43) is an inorganic coating titanium carbide
  • the collimating film uses a microlens perforation method to punch the collimating hole (43B)
  • the other parameters are as follows :
  • P is 10-25 ⁇ m, R is 6.1 ⁇ m-19.8 ⁇ m, H is 2.5 ⁇ m-10.7 ⁇ m, and n1 is 1.5;
  • T 10-50 ⁇ m, n2 is 1.65, D is 0.6 ⁇ 3.9 ⁇ m;
  • t 1.0-3.0 ⁇ m
  • ⁇ 2.0-5.0 ⁇ m
  • the deviation ⁇ is 0.26-0.49 ⁇ m.
  • the collimating lens array and the collimating hole array of the collimating film are all arranged closely in a regular triangle
  • the material of the collimating lens layer (41) is PMMA
  • the flexible substrate layer (42) The material of is PET
  • the light-shielding medium (43A) of the collimating hole layer (43) is an inorganic coating titanium carbide
  • the collimating film uses a microlens perforation method to punch the collimating hole (43B)
  • P is 10-50 ⁇ m, R is 16 ⁇ m-30.2 ⁇ m, H is 1.1 ⁇ m-21.3 ⁇ m, and n1 is 1.5;
  • T is 50 ⁇ m, n2 is 1.65, D is 0.1 ⁇ 7.8 ⁇ m;
  • t is 0.5 ⁇ m
  • ⁇ is 1.0-8.0 ⁇ m
  • the deviation ⁇ is 0.21-0.88 ⁇ m.
  • the collimating lens array and the collimating hole array of the collimating film are all arranged closely in a regular triangle
  • the material of the collimating lens layer (41) is PMMA
  • the flexible substrate layer (42) The material of is PET
  • the light-shielding medium (43A) of the collimating hole layer (43) is an inorganic coating titanium carbide
  • the collimating film uses a microlens perforation method to punch the collimating hole (43B)
  • P is 30 ⁇ m, R is 19.3 ⁇ m, H is 10.8 ⁇ m, and n1 is 1.5;
  • T 38 ⁇ m
  • n2 1.65
  • D 3.6 ⁇ m
  • t 0.5-7 ⁇ m, and ⁇ is 5.0-10.0 ⁇ m. Further, the deviation ⁇ is 0.46-0.99 ⁇ m.
  • the collimating lens array and the collimating hole array of the collimating film are all arranged closely in a regular triangle, the material of the collimating lens layer (41) is PMMA, and further, it is cured by light Acrylic resin is polymerized, and the refractive index n1 is adjustable from 1.4 to 1.6.
  • the light-shielding medium (43A) of the collimating hole layer (43) is an inorganic coating titanium carbide, and the collimating film uses a microlens perforating method to punch the collimating hole (43B), and other parameters are as follows:
  • P is 20-25 ⁇ m, R is 15.9-22.5 ⁇ m, H is 3.2-9.2 ⁇ m, n1 is 1.4-1.6;
  • T 38-50 ⁇ m
  • n2 1.5-1.65
  • D is 0.5-3.6 ⁇ m
  • t 2.0 ⁇ m and ⁇ is 4.0 ⁇ m. Further, the deviation ⁇ is 0.25-0.66 ⁇ m.
  • Example 58 the collimating lens array and the collimating hole array of the collimating film are both square and closely arranged (as shown in FIG. 7), and the material of the collimating lens layer (41) is PMMA, a flexible substrate
  • the material of the layer (42) is PET
  • the light-shielding medium (43A) of the collimating hole layer (43) is an inorganic coating titanium carbide
  • the collimating film uses a microlens perforation method to punch the collimating hole (43B), and other items
  • the parameters are as follows:
  • P is 25 ⁇ m, R is 19.6 ⁇ m, H is 11.1 ⁇ m, and n1 is 1.5;
  • T 38 ⁇ m
  • n2 1.65
  • D 3.9 ⁇ m
  • t 2.0 ⁇ m and ⁇ is 4.0 ⁇ m. Furthermore, the deviation ⁇ is 0.69 ⁇ m.
  • the present invention also provides a method for preparing the collimating film, and the collimating holes of the collimating film are perforated by a micro-focusing method.
  • the laser is vertically irradiated to the collimating lens layer, the laser is focused through the microlenses of the collimating lens layer, and the focused light spot falls on the collimating hole layer to make a collimating hole.
  • the distribution of the collimating hole array and the microlens array are completely consistent, and the center of any collimating hole is on the main optical axis of the corresponding microlens.
  • preparation method includes the following steps:
  • the collimating lens layer is formed on the upper surface of the flexible substrate layer (light curing, thermal curing, hot pressing, etc. can be used) to form a lens array (convex);
  • a large-area flat-top laser (parallel laser after Gaussian beam shaping) is used to irradiate the microlens array vertically with appropriate low energy, and after each microlens, it is focused on the light-shielding medium (ie micro-focusing method) and shot Corresponding to the collimating holes, an array of collimating holes with the same distribution is generated to form a collimating hole layer.
  • micro-focusing method includes the following features:
  • the flat-top laser after beam shaping is used as the laser source. After shaping, the irradiated area becomes larger and the energy density decreases;
  • the micro-focusing spot should be small enough within a reasonable range, and the focal position should be designed on the lower surface of the PET or deeper, so that the energy is concentrated on the light-shielding layer (light-shielding medium);
  • the process of the micro-focusing method (as shown in Figure 4) is divided into four basic steps: (a) Flat-top laser (5) with appropriate energy (too high hole is too large, even burned to the substrate, over Low, no perforation), hit the collimating lens layer (41) of the semi-finished collimating film, the micro lens (41A) realizes micro-focusing, the flesh thickness (41B) realizes the pre-shrinking of the spot area, and finally the laser passes through the substrate layer ( 42), the light-shielding medium (43A) is focused into a very small spot to achieve a high concentration of energy; (b) due to the absorption of light by the light-shielding medium, the instantaneous accumulation of energy causes the light-shielding medium at the spot position to be burned through instantly and produce Some ash content, in fact, the first two steps only need microsecond level, which is very fast; (c) After the ash content is removed, the collimating holes (43B) are exposed.
  • collimating holes are on the main optical axis of the microlens (40B). ), so it is highly aligned with the micro lens (41A), avoiding the time-consuming alignment process.
  • the collimating film (4) of the present invention is already a finished product, including a complete structure—the collimating lens layer (41), The base layer (42), the collimation hole layer (43); (d) the collimation film (4) has met the normal or close to normal collimation light transmission at this time, and can be tested with ordinary strength during on-line production
  • the light source such as white light, green light, three-wave lamp
  • the light source is irradiated from the surface of the microlens, and the light will pass through the collimating hole, so that the image of the light-transmitting hole array can be observed on the back side, and the transmitted light intensity can be quantified for inspection
  • the quality of punching can be easily detected automatically on the assembly line in this process, and the images captured by sampling at specific locations can also be analyzed digital
  • the traditional drilling method has greater limitations (as shown in Figure 5): (a) Gaussian laser (7), which is focused by the lens group of the laser head, The back side of the semi-finished product is hit on the light-shielding medium (43A); (b) the light-shielding layer is sequentially burned through at different positions, and some ash is generated; (c) when the ash is removed, the collimating hole is exposed.
  • Gaussian laser (7) which is focused by the lens group of the laser head, The back side of the semi-finished product is hit on the light-shielding medium (43A);
  • the light-shielding layer is sequentially burned through at different positions, and some ash is generated; (c) when the ash is removed, the collimating hole is exposed.
  • the entire alignment process needs to locate the origin O (or Mark point), the front CCD (Charge Coupled Device) high-definition camera is aligned with the optical center of the lens, and the laser head on the back will be linked with the front CCD lens to find To the corresponding collimation hole position, the initial displacement (vector or coordinate difference) between the first point and the position is calculated.
  • This initial positioning process is very time-consuming and complicated, and requires high equipment; then, based on the initial The displacement amount and the displacement amount between the points can be calculated to locate all the point positions, and 2 ⁇ n points can be printed in sequence.
  • the galvanometer group can be used to shorten the time in this process, n cannot be set too large, otherwise the cumulative error will inevitably exceed 1 ⁇ m , Will be even larger, especially the galvanometer will cause the angle to tilt, the spot becomes larger and deformed, and the error accumulates faster and faster; finally, when the error accumulates to be unacceptable, you need to return to the origin O and search for the first point again. That is, the initial positioning process is repeated.
  • the galvanometer group is used to shorten the time, since n cannot be too large, the initial positioning process needs to be performed frequently, which makes this method extremely time-consuming, complicated and dependent on equipment.
  • the punching process is not only costly but also low precision. .
  • the limitations of the traditional perforating method are more than this: the above-mentioned process of locating the first point and calculating the points from 2 to n requires a prerequisite, that is, the spacing of the microlenses is completely accurate; in fact, on the one hand , The micro lens mold is also prepared by laser drilling, there will be errors, so the alignment error of the traditional method will be further increased, especially when the mold accuracy is not so high; on the other hand, some special molds are prepared In the irregular microlens layer, the arrangement precision and shape precision of the microlenses are poor, or the designed pitch is uneven or even disordered.
  • the mold precision and preparation cost of the microlens layer are increased in disguise, resulting in a very high cost of the entire collimating film, not to mention the realization of the alignment and perforation of the irregular microlens layer (and the microfocusing method of the present invention) Can be easily achieved).
  • the molding method of the microlens array should be selected according to the type of transparent polymer and the application, and the present invention is not preferred; the coating method of the shading medium should be selected according to the type of the shading medium, and the wet coating method should be selected for the organic coating , Inorganic coating needs to choose dry coating (that is, physical vapor deposition) method.
  • the method for preparing the collimating film provided by the present invention is suitable for the production of sheets and also for the production of coils.
  • the collimating film can be used as a flexible collimating device for image sensor modules.
  • the collimating film can collimate and filter the diffuse light at a single point of the image to a certain extent, form a normal beamlet light signal, and transmit it to the corresponding photoelectric sensor. It is especially suitable for large-size, ultra-thin, Even in the flexible image recognition module.
  • the collimating film provided by the present invention uses a polymer film with a thickness of 10-50 ⁇ m as the flexible base layer, which realizes the flexibility, ultra-thinness and large-size of the collimating device, and is particularly suitable for large-scale applications. In image recognition modules of size, ultra-thin, and even flexibility.
  • the collimating film provided by the present invention adopts the micro-focus method to perforate.
  • the distribution of the collimating hole array and the microlens array are exactly the same, and the center of each collimating hole is at the center of the corresponding microlens.
  • one-to-one high-precision alignment, alignment deviation ⁇ 1 ⁇ m not only greatly improves the transmission of signal light, but also allows the collimation structure to be further reduced (such as the simultaneous reduction of microlenses and collimation holes) to reduce crosstalk and improve
  • the signal-to-noise ratio of the collimating film is improved, and the production efficiency is greatly improved, and the cost is reduced.
  • the collimating film provided by the present invention only includes one collimating hole layer, which fundamentally solves the problem of difficulty in alignment between the two collimating diaphragms, and has low thickness, good toughness, Not fragile, the center of the collimating hole prepared by the micro-focusing method is on the main optical axis of the corresponding micro lens, and the collimating hole and the corresponding micro lens are aligned accurately.
  • the preparation method of the collimating film provided by the present invention is easy to operate, can be mass-produced, and improves the production yield.
  • the collimating film provided by the present invention has excellent performance and can pass collimated light and filter diffused light.
  • the collimating film provided by the present invention can be applied to large-size, ultra-thin image recognition modules, so that the mass production of large-size, ultra-thin, and even flexible image recognition modules is greatly improved.
  • the collimating film of the present invention has obvious advantages.
  • Figure 1 is a schematic diagram of the basic principle of a collimator device
  • Figure 2 shows the impact of the alignment accuracy of the collimation structure on the signal strength; the higher the alignment accuracy, the greater the signal strength;
  • Figure 3 shows the influence of the aspect ratio of the collimating structure on the crosstalk intensity; the higher the aspect ratio, the smaller the crosstalk intensity;
  • Figure 4 shows the drilling principle of the micro-focus method
  • Figure 5 shows the accumulation process of alignment errors of traditional punching
  • Figure 6 is a schematic cross-sectional view of a collimating film provided by the present invention.
  • Fig. 7 is a three-dimensional schematic diagram of the collimating film provided by the present invention (square arrangement);
  • Fig. 8 is a three-dimensional schematic diagram of the collimating film provided by the present invention (arranged in equilateral triangle);
  • Figure 9 is a schematic cross-sectional view of a collimating film (collimating sheet) provided by a comparative example
  • FIG. 10 is a test process of the light blocking performance (minimum light blocking angle) of the collimating film provided by the present invention.
  • Figure 9 shows a collimating film for comparison, including a collimating lens layer 41, a flexible substrate layer (abbreviated as the substrate) 42 and a collimating hole layer 43.
  • the collimating lens layer is placed on the upper surface of the substrate and collimating The hole layer is placed on the bottom surface of the substrate.
  • the collimating lens layer 41 includes a microlens array 41A and a thickness 41B.
  • the collimating hole layer 43 includes a light-shielding medium 43A and a collimating hole array formed by hollowing out the medium.
  • the number of collimating holes 43B is constituted); the thickness T of the flexible base layer is 25 ⁇ m.
  • the collimating lens array and the collimating hole array of the collimating film are all closely arranged in equilateral triangles (as shown in FIG. 8).
  • the minimum pitch P of the main optical axis of the microlens is 18 ⁇ m
  • the radius of curvature R is 12.6 ⁇ m
  • the thickness of the collimating lens layer H (the vertical distance from the apex of the microlens to the upper surface of the substrate) is 8.5 ⁇ m
  • the thickness of the collimating hole layer t is 2 ⁇ m
  • the collimating hole diameter ⁇ is 4 ⁇ m.
  • the microlens array and the thickness of the collimating lens layer are made of transparent polymer PMMA, and the refractive index n1 is 1.5.
  • the material of the flexible base layer is transparent polymer film PET, and the refractive index n2 is 1.65.
  • the light-shielding medium 43A of the collimating hole layer 43 is an inorganic plating layer of titanium carbide.
  • the collimating film uses a traditional laser drilling method (as shown in FIG. 5) to drill collimating holes 43B.
  • the main optical axis 40 of the microlens and the center of the collimating hole 43B have alignment deviations.
  • the alignment deviation of the first hole is ⁇ 1
  • the alignment deviation of the n-th hole is ⁇ n
  • ⁇ n-1 ⁇ n (n is a natural number greater than 2)
  • n is a natural number greater than 2
  • the bit deviation ⁇ exceeds 1 ⁇ m or even more.
  • the light transmittance coefficient k is easy to drop, even lower than 0.6, reaching the "poor" evaluation level.
  • the collimating film provided by the present invention includes a collimating lens layer 41, a flexible base layer 42, and a collimating hole layer 43.
  • the collimating lens layer is placed on the upper surface of the base, and the collimating hole layer is placed on the base.
  • the collimating lens layer 41 includes a microlens array 41A and a thickness 41B, and the collimating hole layer 43 includes a light-shielding medium 43A and a collimating hole array formed by hollowing out the medium (a certain number of collimating holes 43B Composition);
  • the thickness T of the flexible base layer is 25 ⁇ m.
  • the collimating lens array and the collimating hole array of the collimating film are all closely arranged in equilateral triangles (as shown in FIG. 8).
  • the minimum distance P of the main optical axis of the microlens is 18 ⁇ m
  • the radius of curvature R is 12.6 ⁇ m
  • the thickness H of the collimating lens layer is 8.5 ⁇ m
  • the thickness t of the collimating hole layer is 2 ⁇ m
  • the collimating hole diameter ⁇ is 4 ⁇ m .
  • the microlens array and the thickness of the collimating lens layer are made of transparent polymer PMMA, and the refractive index n1 is 1.5.
  • the material of the flexible base layer is transparent polymer film PET, and the refractive index n2 is 1.65.
  • the light-shielding medium 43A of the collimating hole layer is an inorganic plating layer of titanium carbide.
  • the collimating film adopts the micro-focus method (as shown in Figure 4) to punch collimating holes 43B.
  • the distribution of the collimating hole array and the microlens array are exactly the same, and the center of any collimating hole is in the main lens of the corresponding microlens.
  • the alignment deviation ⁇ between the center of the collimating hole and the main optical axis of the corresponding microlens is 0.47 ⁇ m, ⁇ 1 ⁇ m.
  • the laser is precisely focused on the lower surface of the PET, the spot diameter D is 1.7 ⁇ m, the minimum light blocking angle ⁇ is 7.5°, and the light transmission coefficient k is 0.98. Overall, the performance advantage of Comparative Example 1 is obvious.
  • the combination of collimating lens structure parameters is not limited to the above embodiments: for the same collimating filter effect, various changes can be made according to the material of the collimating lens layer, the refractive index, the material of the flexible substrate layer, and the refractive index. For example, change P, R, H, ⁇ , t, etc. accordingly; for the shading effect of the collimating hole of the same thickness t, various changes can be made to the shading medium, such as changing the types and combinations of organic coatings and inorganic coatings. Even proportions and so on.
  • the performance of the collimating film provided by the present invention was evaluated in the following manner.
  • the final important performance index of the collimating film is the ability to block stray light, which is generally evaluated by the smallest angle that can block oblique light.
  • the minimum angle ⁇ that can completely block the oblique light can be obtained through conventional optical simulation software (Light tools, ZeMax, Tracepro, etc.) or theoretical calculations.
  • the minimum angle test process of the collimating film According to the size of ⁇ (accurate to 0.5°), the present invention divides the light blocking performance into 5 levels, and the corresponding relationship in turn is: excellent: 0° ⁇ ⁇ 5°, excellent: 5° ⁇ 7.5°, good: 7.5° ⁇ 10°, medium: 10° ⁇ 15°), poor: ⁇ 15°.
  • Another important performance index of the collimating film is the ability to transmit signal light.
  • the alignment accuracy between the collimating hole and the microlens can be checked: when the alignment degree is high enough, the light spot is always within the diameter of the collimating hole, and the light transmission performance is the best at this time, and the transmittance ( Transmittance) maximum (obtained by optical simulation or standard sample test under high-precision laser head conditions, generally around 90%); when the alignment error increases, the transmittance will continue to decay; due to the very large number of collimating holes, In this way, the transmittance changes can be tested under macro conditions to compare the degree of alignment.
  • the ratio of the measured transmittance to the highest transmittance (the highest transmittance refers to the light transmittance measured when the main optical axis of the microlens is completely coincident with the center line of the corresponding collimating hole) Defined as the transmittance coefficient k, which is 1 when the degree of alignment is sufficiently high.
  • the present invention divides the light transmittance performance into 5 grades, and the corresponding relationships are as follows: excellent: 1 ⁇ k>0.95, excellent: 0.95 ⁇ k>0.9, good: 0.9 ⁇ k>0.8, medium : 0.8 ⁇ k>0.6, difference: k ⁇ 0.6.
  • the collimating lens array and the collimating hole array in the collimating film are all arranged in equilateral triangles
  • the material of the collimating lens layer 41 is PMMA
  • the material of the flexible base layer 42 is PMMA.
  • the material is PET
  • the light-shielding medium 43A of the collimating hole layer 43 is an inorganic coating titanium carbide.
  • the collimating film uses a microlens perforation method to punch the collimating hole 43B. The other parameters are listed in Table 1.
  • P is the minimum distance between the main optical axis of the microlens, in ⁇ m; R is the radius of curvature of the microlens, in ⁇ m; H is the thickness of the collimating lens layer, in ⁇ m; n1 is the refractive index of the collimating lens layer, infinite Dimensional unit; T is the thickness of the flexible substrate layer, in ⁇ m; n2 is the refractive index of the flexible substrate layer, a dimensionless unit; D is the diameter of the spot formed on the lower surface of the flexible substrate layer after focusing by a microlens, in ⁇ m; t is The thickness of the collimating hole layer, in ⁇ m; ⁇ is the diameter of the collimating hole, in ⁇ m; ⁇ is the minimum oblique light angle that the collimating film can filter out, used to measure the collimating filter effect, in °; k is the standard The ratio of the actual transmittance of the straight film to the highest transmittance is used to measure the alignment accuracy
  • Table 1 it is a relatively preferred embodiment designed with different P values on a flexible base layer with a thickness of 25 ⁇ m.
  • the P value is 10, 15, 18, 20, 25, and 30 ⁇ m
  • the focal length becomes farther, the micro-focus spot on the light-shielding layer becomes larger, so it is necessary to cooperate with the increase of H to make the focus return to the light-shielding layer, the light spot is reduced, and the matching change of R and H can make the micro-focus spot diameter D Continuously shrinking, the minimum light blocking angle ⁇ is gradually reduced, and the light blocking performance is improved.
  • the spot diameter D is to the diameter ⁇ of the opening (collimation hole), the greater the impact of the alignment deviation ⁇ on the light transmittance, and a slight deviation will cause the loss of signal light, and D is relatively ⁇
  • the impact on the position deviation is small, and it is still in the hole no matter which direction it moves.
  • the embodiments 1-24 provided by the present invention all have a fixed opening diameter ⁇ of 4 ⁇ m. Except that D and ⁇ in the embodiments 21-23 are relatively close, the other embodiments maintain a certain difference, and the light transmission coefficient k is greater than 0.9. In general, most of the examples 1-24 can reach the level of double excellent in light blocking performance and light transmission performance, which is based on the better implementation effect of the 25 ⁇ m thick flexible substrate.
  • the collimating lens array and the collimating hole array in the collimating film are both equilateral triangular and closely arranged
  • the material of the collimating lens layer 41 is PMMA
  • the material of the flexible substrate layer 42 is PMMA.
  • It is PET
  • the light-shielding medium 43A of the collimating hole layer 43 is an inorganic coating titanium carbide.
  • the collimating film uses a microlens perforation method to punch the collimating hole 43B. The other parameters are listed in Table 2.
  • Examples 25-30 are Examples 25-30 with different flexible substrate thicknesses.
  • Another set of collimating films with T 25, 38, 50 ⁇ m.
  • the microlens structure When T keeps increasing, in order to maintain the micro-focusing effect (the focus always falls on the bottom surface of the substrate and the light-shielding layer and the spot is as small as possible), the microlens structure obviously needs to be shallow, that is, when the P value and the refractive index are fixed, R As the value increases, H becomes lower (compared to the difference in the embodiment in Table 1, the focal length design has been adapted as T increases, so H does not need to increase, but instead decreases). It can be found that when other conditions remain unchanged, the thickness T increases, which helps the structure become shallower, the light spot D is reduced, the minimum light blocking angle ⁇ is reduced, the light blocking performance is improved, and the light transmission coefficient is further improved.
  • T is selected from 10 to 50 ⁇ m, and more preferably 25 to 38 ⁇ m.
  • the collimating lens array and the collimating hole array of the collimating film are all arranged in equilateral triangles closely, the material of the collimating lens layer 41 is PMMA, and the material of the flexible substrate layer 42 is PMMA. It is PET, and the light-shielding medium 43A of the collimating hole layer 43 is an inorganic coating titanium carbide.
  • the collimating film uses a microlens perforation method to punch the collimating hole 43B. The other parameters are listed in Table 3.
  • the opening diameter ⁇ can be reduced by adjusting the laser energy, and it is not necessarily limited to a fixed value. It can be found that the opening diameter is reduced After that, the light blocking performance can be further improved, but the light transmission effect will be reduced.
  • the P value of Example 40 is 50 ⁇ m, and the corresponding R and H are both large.
  • the size of the microlens has reached the upper limit of the design, including the spot diameter D is also large (D is particularly small , Especially less than 0.5 ⁇ m is not good, it is easy to cause the single-point energy to be too high and burn the substrate), resulting in the opening diameter ⁇ reaching the upper limit of 8 ⁇ m, and the minimum light blocking angle ⁇ is 12 degrees, which is also large, and the light blocking performance is not considered That's great.
  • P is selected from 10 to 50 ⁇ m, preferably 15 to 30 ⁇ m, and more preferably 18 to 25 ⁇ m.
  • ⁇ is selected from 1 to 10 ⁇ m (10 ⁇ m from Example 47), and more preferably 3 to 5 ⁇ m.
  • D is selected from 0.1 to 7.8 ⁇ m, preferably 0.5 to 4.9 ⁇ m, and more preferably 1 to 2 ⁇ m.
  • the collimating lens array and the collimating hole array of the collimating film are all arranged in equilateral triangles closely, the material of the collimating lens layer 41 is PMMA, and the material of the flexible substrate layer 42 is PMMA. It is PET, and the light-shielding medium 43A of the collimating hole layer 43 is an inorganic coating titanium carbide.
  • the collimating film uses a microlens perforation method to punch the collimating hole 43B. The other parameters are listed in Table 4.
  • Examples 41 to 47 are Examples 41 to 47 with different collimating hole layer thickness t. Comparing the first group of Examples 41 to 44 or the second group of Examples 45 to 47, it can be seen that when other conditions remain unchanged, increasing t helps to improve the light blocking performance, and that t is too thin is not a preferred value. Since laser drilling generally forms a cavity with a smaller aspect ratio, the opening diameter is often larger than t. In fact, when t is too thick, the opening diameter will be too large (as in the second group of embodiments). Gradually reduce the light blocking performance. In the present invention, t is selected from 0.5 to 7 ⁇ m, preferably 1 to 5 ⁇ m, and more preferably 2 to 3 ⁇ m.
  • the collimating lens array and the collimating hole array of the collimating film are all arranged in equilateral triangles
  • the material of the collimating lens layer 41 is PMMA, and further, it is cured by light Acrylic resin is polymerized, and the refractive index n1 is adjustable from 1.4 to 1.6.
  • the light-shielding medium 43A of 43 is an inorganic coating titanium carbide, and the collimating film uses a microlens perforating method to make a collimating hole 43B.
  • Table 5 The other parameters are listed in Table 5.
  • n1 is selected from 1.4 to 1.6, preferably 1.5.
  • n2 is selected from 1.5 to 1.65, and it is not preferred depending on the material difference.
  • the collimating lens array and the collimating hole array of the collimating film are both square and tightly arranged (as shown in FIG. 7), and the material of the collimating lens layer 41 is PMMA, The material of the flexible base layer 42 is PET, the light-shielding medium 43A of the collimating hole layer 43 is an inorganic coating titanium carbide, and the collimating film uses a microlens perforation method to punch the collimating holes 43B.
  • the other parameters are shown in Table 6. Listed.
  • the collimating lens array and the collimating hole array of the collimating film are all arranged closely in a regular triangle, and the minimum distance P of the main optical axis of the microlenses of the collimating lens layer is 20 ⁇ m,
  • the radius of curvature R is 18.3 ⁇ m
  • the total thickness of the collimating lens layer is 4.1 ⁇ m
  • the thickness of the flexible substrate layer is 50 ⁇ m
  • the thickness of the collimating hole layer is 2 ⁇ m
  • the diameter of the collimating hole is 4 ⁇ m.
  • the alignment error ⁇ of the microlens and the collimating hole are all ⁇ 1 ⁇ m.
  • the light blocking angle ⁇ is less than 5°, the light blocking performance is excellent, the light transmission coefficient k is all greater than 0.95, and the light transmission performance is excellent.
  • the material of the collimating lens layer, the material of the flexible base layer, and the material of the light-shielding medium of the collimating hole layer are listed in Table 7.
  • the refractive index of the collimating lens layer n1 and the refractive index of the flexible base layer n2 vary depending on the material. , And allow ⁇ 0.02 errors caused by the same material and different processes, which are no longer listed in the table.
  • the molding method is not limited to light curing, thermal curing, injection molding, hot pressing, etc.

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Abstract

一种准直膜（4）及其制备方法。准直膜（4）依次包括准直透镜层（41）、柔性基体层（42）和一层准直孔层（43）；准直透镜层（41）包含微透镜阵列（41A）和肉厚（41B），准直孔层（43）包含准直孔阵列；准直孔阵列与微透镜阵列（41A）的分布完全一致；准直透镜层（41）的微透镜阵列（41A）为有序排布。准直膜（4）只包括一层准直孔层（43），解决了两层准直光阑对位难的问题。能对图像单点像素处的漫射光进行一定程度的准直过滤，形成法向小波束光信号，并将其传输到相应光电感应器处，特别适用于大尺寸、超薄、甚至柔性的图像识别模组中。

Description

一种准直膜及其制备方法 技术领域
本发明涉及一种准直膜，尤其涉及一种图像识别领域的准直膜及其制备方法。
背景技术
在图像识别领域，常用的图像传感器如CMOS型或photo-TFT型，传感器模组中一般都含有准直器件，用以加强信噪比，提高识别率，减少串扰。准直器件的功能(如图1所示)主要是对图像单点像素处的漫射光进行准直过滤，形成的法向的准直光或接近准直的光(信号)，可以顺利传输到相应光电感应器处，而偏离法向的大角度光(噪音)只能极少地甚至无法进入非对应的光电感应器处，由此信噪比得以加强。
准直器件通常都具有顶部准直结构层和底部准直结构层：首先，顶层和底层双层准直结构需要精确对位，否则会大大降低信号光的强度(如图2所示)；其次，需增加顶层(入光)准直结构和底层(出光)准直结构之间距离，或/和缩小微结构尺寸(如图3所示)，以提高整体长径比，否则会增加串扰光的透过。
传统的准直器件一般为刚性的准直片，如光纤集束切片，或是玻璃基两侧形成的微透镜(Microlens)、准直光阑等，这类刚性准直片普遍需保持较高的厚度，一方面用以保持长径比，一方面用以保持其机械性能，防止在应用环境中破碎。然而即便如此，这类刚性准直片仍然无法满足大尺寸的图像识别模组的应用。特别是还需要压缩整体厚度的应用场合(如超薄大屏手机)，它将变得更脆，更易碎，生产良率更低，不论是性能，还是成本都无法满足需求。另外显而易见的是，此类刚性准直片更不可能在柔性图像识别模组中。
除了光纤集束类的准直片(顶层和底层准直结构本就对齐)，绝大多数刚性准直片均需要完成两层准直结构(准直光阑)的对位。然而，依次制备的两层结构要进行高精度对位，具有相当大的难度：首先，需要非常复杂、昂贵的双轴定位设备，定位过程繁琐、耗时，若准直结构尺度小于50μm(图像精度DPI>508)，点阵规模必会达到每平米上亿个点，生产效率极其低下；其次，这种对位方式实际上精度并不高，特别是准直结构的尺寸缩小，数量增加时，累积误差会变得愈发明显，导致信号光强度下降，而频繁地原点校正也将变得更加费时。
综上，传统刚性准直片存在厚度高，厚度低的情况下易碎、性能差，两层准直结构(准直光阑)的对位难、良率低、产能低的问题，难以在大尺寸、超薄、柔性的图像识别领域中应用。
发明内容
为了解决传统刚性准直片中两层准直光阑对位难的问题，本发明提供一种准直膜及其制备方法。本发明提供的准直膜只包括一层准直孔层，解决了两层准直光阑对位难的问题。
为了解决上述技术问题，本发明采用下述技术方案：
本发明提供一种准直膜，所述准直膜依次包括准直透镜层、柔性基体层和准直孔层。
所述准直孔层为准直光阑。
本发明提供的准直膜只包括一层准直光阑。本发明提供的准直膜只包括一层准直孔层。
所述准直膜依次包括准直透镜层、柔性基体层和一层准直孔层。
所述准直透镜层置于柔性基体的上表面，准直孔层置于柔性基体的下表面。
所述准直透镜层包含微透镜阵列和肉厚。
所述准直孔层包含准直孔阵列。
所述准直孔层包含遮光介质层和准直孔阵列。
所述准直孔层包含遮光介质和介质镂空后形成的准直孔阵列。
所述准直孔阵列与微透镜阵列的分布完全一致。每一个准直孔均在相对应微透镜的主光轴上。进一步的，每一个准直孔的圆心均在相对应微透镜的主光轴上。
所述准直膜采用微聚焦法打孔，所述准直孔阵列与微透镜阵列的分布完全一致，任意准直孔的圆心均在相应微透镜主光轴上，一对一高精度对位，对位偏差Δ<1μm。所述柔性基体层的厚度T选自10～50μm，优选为25～38μm。
所述准直透镜层的微透镜阵列为有序排布。
所述准直透镜层的微透镜阵列与所述准直孔层的准直孔阵列均为有序排布。
所述准直孔阵列中的一个准直孔与微透镜阵列中的一个微透镜的位置相对应，所述微透镜的主光轴与所述准直孔的中心相重合或其偏差小于1μm。与一个准直孔位置相对应的一个微透镜称为这个准直孔的相对应微透镜。相邻的三个微透镜的主光轴的坐标相连形成正三角形(由三个互相交叠的微透镜的主光轴坐标连接而成)，或者，相邻的四个微透镜的主光轴的坐标相连形成正方形(由四个互相交叠的微透镜的主光轴坐标连接而成)。
所述微透镜阵列中的微透镜紧密排列。即相邻的微透镜相互接触或相互交叠。
所述准直膜的准直透镜阵列与准直孔阵列均为正三角形(由三个互相交叠的微透镜的 主光轴坐标连接而成)紧密排列，或正方形(由四个互相交叠的微透镜的主光轴坐标连接而成)紧密排列。
进一步的，在所述准直透镜层中，相邻微透镜的主光轴的间距P为10～50μm，微透镜的半径R为6.1μm-30.2μm，准直透镜层的高度H为1.1μm-27.4μm，准直透镜层材质的折射率n1为1.4～1.6；在所述柔性基体层中，柔性基体层的厚度T为10～50μm，柔性基体层材质的折射率n2为1.5～1.65；在所述准直孔层中，准直孔层的厚度t为0.5～7μm，准直孔阵列中的准直孔的直径φ为1～10μm。
所述微透镜的主光轴间距P均相同，P选自10～50μm，优选为15～30μm，进一步优选为18～25μm。
所述准直膜的微透镜将垂直入射的光线聚焦，在柔性基体层下表面形成直径为D的光斑，D选自0.1～7.8μm，优选为0.5～4.9μm，进一步优选为1～2μm。
所述光斑直径D由微透镜的曲率半径R(球半径R)、折射率n1、准直透镜层厚度H(微透镜顶点至基体上表面的垂直距离)以及柔性基体层的折射率n2、厚度T共同确定。
所述微透镜的曲率半径R选自6.1～30.2μm，准直透镜层厚度H选自1.1～27.4μm，R和H不做优选，依据其他参数进行适配。
所述准直透镜层(即微透镜层)折射率n1选自1.4～1.6，优选为1.5。
所述柔性基体层的折射率n2,选自1.5～1.65，依材质而异，不做优选，允许±0.02同材质不同工艺造成的误差。
所述准直膜的微透镜阵列与肉厚材质相同，材质均为透明聚合物。
进一步的，所述微透镜层的透明聚合物选自AR(Acrylic resin，丙烯酸树脂或改性丙烯酸改性树脂)、PC(聚碳酸酯)、PET(聚对苯二甲酸乙二醇酯)、PEN(聚萘二甲酸乙二醇酯)、PI(聚酰亚胺)、PS(聚苯乙烯)、SR(Silicon Resin，硅树脂)、FEP(全氟乙烯丙烯共聚物)或EVA(乙烯-醋酸乙烯共聚物)中的一种。进一步的，优选为，PMMA(聚甲基丙烯酸甲酯)、PC、或PS中的一种。
所述准直膜的柔性基体层选自透明聚合物薄膜。所述柔性基体层可以弯曲。
进一步的，所述柔性基体层的透明聚合物薄膜的材质选自PET、PEN、PI、PC、PMMA(聚甲基丙烯酸甲酯)、PP(聚丙烯)、PO(聚烯烃)、SR或COP(环烯烃共聚物)中的一种。进一步的，优选为，PET、PI、PC、或PMMA中的一种。
所述准直膜的准直孔层的遮光介质选自有机涂料、无机镀层中的一种或至少两种的组合。所述遮光介质的有机涂料选自不透明聚合物油墨体系。
进一步的，所述遮光介质的不透明聚合物油墨体系包含吸光物质以及聚合物固化体系。
进一步的，所述吸光物质选自碳质(如碳黑、碳纤维、石墨等)、碳化物(如碳化铬、碳化钛、碳化硼等)、碳氮化物(如碳氮化钛、碳氮化硼等)、硫化物(如硫化亚铁、二硫化钼、二硫化钴、硫化镍等)中的一种或至少两种的组合。
进一步的，所述遮光介质的聚合物固化体系可选自丙烯酸体系(AR)、聚氨酯体系(PU)、硅树脂体系(SR)、环氧树脂体系(EP)、密胺树脂体系(MF)、酚醛树脂体系(PF)、脲醛树脂体系(UF)、或热塑性弹性材料(例如：乙烯-醋酸乙烯共聚物，热塑性弹性体TPE或热塑性聚氨酯弹性体TPU)中的一种或至少两种的组合。
进一步的，所述聚合物固化体系可选自丙烯酸树脂体系、聚氨酯体系、有机硅体系、环氧树脂体系、或热塑性弹性材料中的一种或至少两种的组合。
所述遮光介质的无机镀层选自碳单质、碳化物、碳氮化物、硫化物中的一种或至少两种的组合。
所述准直膜的准直孔层的厚度t选自0.5～7μm，优选为1～5μm，进一步优选为2～3μm。
所述准直膜的准直孔层的准直孔直径φ选自1～10μm，进一步优选为3～5μm。
进一步的，所述柔性基体层厚度T可以为10μm-50μm，例如10μm，15μm，20μm，25μm，38μm或50μm。
进一步的，所述准直透镜层的相邻微透镜主光轴间距P可以为10μm-50μm，例如10μm，15μm，18μm，20μm，25μm，30μm或50μm。
进一步的，所述准直透镜层的微透镜曲率半径R可以为6.1μm-30.2μm，例如6.1μm，6.9μm，7.9μm，9.4μm，11.2μm，11.3μm，12μm，12.1μm，12.6μm，12.8μm，13.3μm，13.6μm，14μm，14.3μm，14.3μm，14.8μm，15μm，15.1μm，15.7μm，15.9μm，16μm，16.1μm，16.7μm，17μm，17.2μm，17.3μm，18μm，18.1μm，18.3μm，18.8μm，19.3μm，19.4μm，19.6μm，19.8μm，20μm，20.6μm，20.8μm，21.6μm，22.5μm，25.6μm，或30.2μm。
进一步的，所述准直透镜层厚度H可以为1.1μm-27.4μm，例如1.1μm，2.4μm，2.5μm，3.0μm，3.1μm，3.2μm，3.5μm，3.8μm，4.1μm，5.0μm，5.8μm，6.0μm，6.2μm，6.8μm，7.2μm，7.8μm，8.5μm，8.6μm，8.7μm，9.2μm，10.4μm，10.7μm，10.8μm，11μm，11.1μm，11.4μm，11.5μm，12.9μm，13.6μm，14.1μm，14.6μm，15.0μm，15.4μm，16.3μm，17.3μm，18.1μm，19.8μm，20.5μm，21.3μm，22.2μm，22.7μm，25μm，或27.4μm。
进一步的，所述微透镜在柔性基体层下表面形成的光斑直径D可以为0.1μm-7.8μm，例如0.1μm，0.3μm，0.4μm，0.5μm，0.6μm，0.7μm，0.8μm，1.0μm，1.1μm，1.2μm，1.4μm，1.5μm，1.6μm，1.7μm，1.8μm，2.0μm，2.2μm，2.4μm，2.5μm，2.6μm，2.8μm，3.1μm，3.4μm，3.6μm，3.7μm，3.9μm，4.0μm，4.9μm，或7.8μm。
进一步的，所述准直孔层的厚度t可以为0.5-7μm，例如0.5μm，1μm，2μm，3μm，4μm，5μm，或7μm。
进一步的，所述准直孔直径φ可以为1-10μm，1μm，2μm，3μm，4μm，5μm，6μm，8μm，或10μm。
进一步的，所述准直透镜层的折射率n1可以为1.34-1.7，例如1.34，1.4，1.47，1.48，1.5，1.59，1.6，1.65，1.66，或1.7。
进一步的，所述柔性基材层的折射率n2可以为1.48-1.7，例如1.48，1.49，1.5，1.6，1.65，1.66或1.7。
进一步的，本发明提供的准直膜，包括准直透镜层(41)、柔性基体层(42)(简称为基体)和准直孔层(43)，准直透镜层置于基体的上表面，准直孔层置于基体的下表面，所述准直透镜层(41)包含微透镜阵列(41A)和肉厚(41B)，所述准直孔层(43)包含遮光介质(43A)和介质镂空后形成的准直孔阵列(由一定数量准直孔(43B)构成)。
在实施例1-24中，所述准直膜中的准直透镜阵列与准直孔阵列均为正三角形紧密排列，所述准直透镜层(41)的材质为PMMA，柔性基体层(42)的材质为PET，准直孔层(43)的遮光介质(43A)为无机镀层碳化钛，所述准直膜采用微透镜打孔方式打出准直孔(43B)。其它各项参数如下：
P为10～30μm，R为9.4μm-20.6μm，H为3μm-27.4μm，n1为1.5；
T为25μm，n2为1.65，D为0.3～4.0μm；
t为2.0μm，φ为4.0μm。进一步的，偏差Δ为0.18-0.90μm。
在实施例25-30中，所述准直膜中准直透镜阵列与准直孔阵列均为正三角形紧密排列，所述准直透镜层(41)的材质为PMMA，柔性基体层(42)的材质为PET，准直孔层(43)的遮光介质(43A)为无机镀层碳化钛，所述准直膜采用微透镜打孔方式打出准直孔(43B)，所述其他各项参数如下：
P为10～25μm，R为6.1μm-19.8μm，H为2.5μm-10.7μm，n1为1.5；
T为10-50μm，n2为1.65，D为0.6～3.9μm；
t为1.0-3.0μm，φ为2.0-5.0μm。进一步的，偏差Δ为0.26-0.49μm。
在实施例31-40中，所述准直膜的准直透镜阵列与准直孔阵列均为正三角形紧密排列，所述准直透镜层(41)的材质为PMMA，柔性基体层(42)的材质为PET，准直孔层(43)的遮光介质(43A)为无机镀层碳化钛，所述准直膜采用微透镜打孔方式打出准直孔(43B)，其他各项参数如下：
P为10～50μm，R为16μm-30.2μm，H为1.1μm-21.3μm，n1为1.5；
T为50μm，n2为1.65，D为0.1～7.8μm；
t为0.5μm，φ为1.0-8.0μm。进一步的，偏差Δ为0.21-0.88μm。
在实施例41-47中，所述准直膜的准直透镜阵列与准直孔阵列均为正三角形紧密排列，所述准直透镜层(41)的材质为PMMA，柔性基体层(42)的材质为PET，准直孔层(43)的遮光介质(43A)为无机镀层碳化钛，所述准直膜采用微透镜打孔方式打出准直孔(43B)，其他各项参数如下：
P为30μm，R为19.3μm，H为10.8μm，n1为1.5；
T为38μm，n2为1.65，D为3.6μm；
t为0.5-7μm，φ为5.0-10.0μm。进一步的，偏差Δ为0.46-0.99μm。
在实施例48-57中，所述准直膜的准直透镜阵列与准直孔阵列均为正三角形紧密排列，所述准直透镜层(41)的材质为PMMA，进一步的，由光固化丙烯酸树脂聚合而成，折射率n1从1.4～1.6可调，当n2＝1.65时，柔性基体层(42)的材质为PET，当n2＝1.5时，柔性基体层(42)的材质为COP，准直孔层(43)的遮光介质(43A)为无机镀层碳化钛，所述准直膜采用微透镜打孔方式打出准直孔(43B)，其他各项参数如下：
P为20-25μm，R为15.9-22.5μm，H为3.2-9.2μm，n1为1.4-1.6；
T为38-50μm，n2为1.5-1.65，D为0.5-3.6μm；
t为2.0μm，φ为4.0μm。进一步的，偏差Δ为0.25-0.66μm。
在实施例58中，所述准直膜的准直透镜阵列与准直孔阵列均为正方形紧密排列(如图7所示)，所述准直透镜层(41)的材质为PMMA，柔性基体层(42)的材质为PET，准直孔层(43)的遮光介质(43A)为无机镀层碳化钛，所述准直膜采用微透镜打孔方式打出准直孔(43B)，其他各项参数如下：
P为25μm，R为19.6μm，H为11.1μm，n1为1.5；
T为38μm，n2为1.65，D为3.9μm；
t为2.0μm，φ为4.0μm。进一步的，偏差Δ为0.69μm。
本发明还提供所述准直膜的制备方法，所述准直膜的准直孔采用微聚焦法打孔。
进一步的，所述制备方法中，使激光垂直照射准直透镜层，激光通过准直透镜层的微透镜聚焦，聚焦形成的光斑落在准直孔层上打出准直孔。通过该法制备的准直膜中，所述准直孔阵列与微透镜阵列的分布完全一致，任意准直孔的圆心均在相应微透镜的主光轴上。
进一步的，所述制备方法包括下述步骤：
(1)采用透镜阵列(凹)模具，将准直透镜层在柔性基体层上表面成型(可采用光固化、热固化、热压成型等方式)，形成透镜阵列(凸)；
(2)采用湿法/干法涂布技术，在基体层下表面涂上/镀上遮光介质；
(3)采用大面积平顶激光(高斯波束整形后的平行激光)，以适当的低能量垂直照射微透镜阵列，通过每一个微透镜后均聚焦在遮光介质(即微聚焦法)，并打出相应准直孔，产生相同分布的准直孔阵列，形成准直孔层。
进一步的，所述微聚焦法包含以下特征：
(1)采用波束整形后的平顶激光作为激光源，整形后辐照面积变大，能量密度降低；
(2)必须从正面照射，较低能量密度，通过微透镜自身的微聚焦过程集中能量，实现高能量密度；
(3)微聚焦的光斑在合理范围内要足够小，焦点位置需设计在PET下表面或更深处，让能量集中于遮光层(遮光介质)；
(4)对微透镜层普适性高，不规整微透镜层，如透镜排列精度、形状精度较差、间距不均甚至无序时，同样适用。
进一步的，所述微聚焦法的过程(如图4所示)分为四个基本步骤：(a)平顶激光(5)以合适的能量(过高孔太大，甚至烧到基体，过低，打不穿孔)，打在准直膜半成品的准直透镜层(41)，微透镜(41A)实现微聚焦，肉厚(41B)实现光斑面积的预缩小，最终激光穿过基体层(42)，在遮光介质(43A)上聚焦成极小的光斑，实现能量的高度集中；(b)由于遮光介质对光线的吸收，能量瞬间累积导致光斑位置的遮光介质被瞬间烧穿，并产生一些灰分，实际上前两步的过程仅需要微秒级别，非常迅速；(c)灰分被抽走后，露出准直孔(43B)，这些准直孔本就在微透镜主光轴(40)上，因此和微透镜(41A)高度对齐，避免了费时的对位过程，此时本发明的准直膜(4)已经是成品，包含完整的结构——准直透镜层(41)、基体层(42)、准直孔层(43)；(d)准直膜(4)此时已满足法向或接近法向的准直光高透过，在线生产时可以用普通强度的检验光源(如白光、绿光、三波灯)从微透镜面照射，光会从准直孔透出，使背面可以观察到透光孔阵列图像，并可以量化透过的光强，以此来检验打孔的品质，该过程可以轻易地在流水线上实现自动检测，特定位置抽检捕捉得到地图像也可以进行数据化分析(孔的大小、间距、阵列形态等)。
相比本发明提供的微聚焦法打孔，传统的打孔方式会有较大的局限性(如图5所示)：(a)高斯激光(7)，通过激光头的透镜组聚焦，从半成品背面方向打在遮光介质(43A)上；(b)遮光层不同位置被依次烧穿，并产生一些灰分；(c)当灰分抽走，便露出了准直孔。可以看到，整个对位过程需定位原点O(或称Mark点)，正面的CCD(Charge Coupled Device电荷耦合器件)高清摄像头对准透镜光心，背面的激光头会与正面CCD镜头联动，寻找到相应准直孔位置，从而计算出第一点与位置的初始位移量(矢量或坐标差值)，这个初始 定位过程是非常耗时且复杂的，对设备要求也较高；然后，依据初始位移量和点间位移量即可计算定位出所有点位置，依次打出2～n个点，这个过程可以虽然可以利用振镜组缩短时间，然而n不可以设置太大，否则累积误差必然超过1μm，甚至会更大，特别是振镜会导致角度倾斜，光斑变大变形，误差累积越来越快；最后，当误差累积到不可接受时，需退回原点O，并重新寻找第一个点，即重复初始定位过程。纵观整个过程，虽然采用振镜组缩短时间，但由于n不可太大，需要频繁进行初始定位过程，因此导致该种方法极为耗时、复杂又依赖设备，打孔过程不仅成本高而且精度低。
进一步的，传统打孔方法的局限性还不止如此：上述定位第一个点，计算2～n的点的过程需要有一个前提条件，那就是微透镜的间距是完全准确的；事实上一方面，微透镜的模具也是通过激光打孔制备出来，必然会有误差，因此传统方式的对位误差会进一步增大，特别是模具精度并不那么高时；另一方面，有些特殊模具，所制备的不规整微透镜层，其微透镜的排列精度、形状精度较差，或设计的间距本就不均甚至无序。因此传统过程，变相又增加了微透镜层的模具精度和制备成本，导致整个准直膜成本非常高，更不用说来实现不规则微透镜层的对位打孔(而本发明的微聚焦法可以轻松实现)。
应当注意，微透镜阵列成型方式应根据透明聚合物种类和应用场合进行选择，本发明不做优选；遮光介质的涂布方式应根据遮光介质的种类进行选择，有机涂料需选择湿法涂布方式，无机镀层需选择干法涂布(即物理气相沉积)方式。
应当注意，本发明提供的准直膜制备方法，适用于片材的生产，也适用于卷材的生产。
该准直膜可以作为柔性准直器件用于图像传感器模组。该准直膜能对图像单点像素处的漫射光进行一定程度的准直过滤，形成法向小波束光信号，并将其传输到相应光电感应器处，特别适用于大尺寸、超薄、甚至柔性的图像识别模组中。
与现有技术相比，本发明提供的准直膜，采用了厚度为10～50μm的聚合物薄膜作为柔性基体层，实现了准直器件的柔性、超薄、大尺寸化，特别适用于大尺寸、超薄、甚至柔性的图像识别模组中。
与现有技术相比，本发明提供的准直膜，采用微聚焦法打孔，所述准直孔阵列与微透镜阵列的分布完全一致，每一个准直孔的圆心均在相应微透镜的主光轴上，一对一高精度对准，对位偏差<1μm，不仅大大提高信号光的透过，允许准直结构进一步缩小(如微透镜和准直孔同步缩小)以减少串扰，提高了准直膜的信噪比，而且大大提高了生产效率，降低了成本。
与现有技术相比，本发明提供的准直膜只包括一层准直孔层，根本上解决了两层准直光阑相互之间对位难的问题，且，厚度低，韧性好、不易碎，采用微聚焦法制备得到的准 直孔的圆心在相应微透镜的主光轴上、准直孔与相应微透镜对位精确。本发明提供的准直膜的制备方法易于操作，能够大量生产，提高了生产良率。本发明提供的准直膜的性能优异，能通过准直光，过滤漫射光。本发明提供的准直膜可应用于大尺寸、超薄的图像识别模组中，使大尺寸、超薄、甚至柔性的图像识别模组的量产性大大提高，当应用于手机(OLED屏)等消费类电子产品的指纹解锁方案时，因其市场需求极大，且对超薄、大屏、柔性等特性有更高追求，本发明的准直膜优势明显。
附图说明
图1为准直器件的基本原理示意图；
图2为准直结构的对位精度对信号强度的影响；对位精度越高，信号强度越大；
图3为准直结构的长径比对串扰强度的影响；长径比越高，串扰强度越小；
图4为微聚焦法打孔原理；
图5为传统打孔的对位误差累积过程；
图6为本发明所提供的准直膜横截面示意图；
图7为本发明所提供的准直膜立体示意图(正方形排列)；
图8为本发明所提供的准直膜立体示意图(正三角形排列)；
图9为对比例所提供的准直膜(准直片)横截面示意图；
图10为本发明所提供的准直膜挡光性能(最小挡光角度)测试过程。
其中：
1：目标图像
11～17：目标图像7个连续像素点
2：准直器件
21：顶部(入光)准直结构层
22：底部(出光)准直结构层
3：光电感应芯片
31～37：7个连续像素点所对应的光电感应器
4：本发明所提供的准直膜
4’：对比例所提供的准直膜
40：准直结构的中轴(微透镜主光轴)
41：准直透镜层
41A：微透镜阵列
41B：肉厚
41C：微透镜顶点
42：基体层
43：准直孔层
43A：遮光介质
43B：准直孔
5：平顶波束激光
6：检验光源
7：高斯波束激光
O：激光器定位原点
具体实施方式
为了更易理解本发明的结构及所能达成的功能特征和优点，下文将本发明的较佳的实施例，并配合图式做详细说明如下。
对比例1
如图9所示为用于对比的一个准直膜，包括准直透镜层41、柔性基体层(简称基体)42和准直孔层43，准直透镜层置于基体的上表面，准直孔层置于基体的下表面，所述准直透镜层41包含微透镜阵列41A和肉厚41B，所述准直孔层43包含遮光介质43A和介质镂空后形成的准直孔阵列(由一定数量准直孔43B构成)；所述柔性基体层的厚度T为25μm。所述准直膜的准直透镜阵列与准直孔阵列均为正三角形紧密排列(如图8所示)。所述微透镜的主光轴最小间距P为18μm，曲率半径R为12.6μm，准直透镜层厚度H(微透镜顶点至基体上表面垂直距离)为8.5μm，所述准直孔层的厚度t为2μm，准直孔直径φ为4μm。所述准直透镜层的微透镜阵列与肉厚的材质均为透明聚合物PMMA，折射率n1为1.5，所述柔性基体层的材质为透明聚合物薄膜PET，折射率n2为1.65，所述准直孔层43的遮光介质43A为无机镀层碳化钛。所述准直膜采用传统激光打孔方式(如图5所示)打出一个个准直孔43B，微透镜主光轴40与准直孔43B中心位置存在对位偏差，从激光器定位原点O朝一个方向逐个打孔，第一个孔的对位偏差为Δ 1，第n个孔的对位偏差为Δ n，Δ n-1<Δ n(n为大于2的自然数)，存在n使对位偏差Δ超过1μm甚至更大。透光系数k很容易下降，甚至会低于0.6，达到“差”的评价水平。
实施例1
如图6所示为本发明提供的准直膜，包括准直透镜层41、柔性基体层42和准直孔层 43，准直透镜层置于基体的上表面，准直孔层置于基体的下表面，所述准直透镜层41包含微透镜阵列41A和肉厚41B，所述准直孔层43包含遮光介质43A和介质镂空后形成的准直孔阵列(由一定数量准直孔43B构成)；所述柔性基体层的厚度T为25μm。所述准直膜的准直透镜阵列与准直孔阵列均为正三角形紧密排列(如图8所示)。所述微透镜的主光轴最小间距P为18μm，曲率半径R为12.6μm，准直透镜层厚度H为8.5μm，所述准直孔层的厚度t为2μm,准直孔直径φ为4μm。所述准直透镜层的微透镜阵列与肉厚的材质均为透明聚合物PMMA，折射率n1为1.5，所述柔性基体层的材质为透明聚合物薄膜PET，折射率n2为1.65，所述准直孔层的遮光介质43A为无机镀层碳化钛。所述准直膜采用微聚焦法打孔方式(如图4所示)打出准直孔43B，准直孔阵列与微透镜阵列的分布完全一致，任意准直孔的圆心均在相应微透镜主光轴40上，一对一高精度对准，准直孔的圆心与相对应的微透镜的主光轴的对位偏差Δ为0.47μm，<1μm。打孔时激光恰恰微聚焦在PET下表面，光斑直径D为1.7μm，最小挡光角度θ为7.5°，透光系数k为0.98，整体上与对比例1性能优势明显。
实际上，准直透镜结构参数组合并非局限上述实施例：针对同样准直滤光效果，可以根据准直透镜层的材质、折射率、柔性基体层的材质、折射率做各种各样的改变，例如相应改变P、R、H、φ、t等；针对同样厚度t准直孔的遮光效果，可以对遮光介质做各种各样的改变，例如改变有机涂料、无机镀层的种类、组合、甚至比例等。
按照下述方式评价本发明提供的准直膜的性能。
(A)挡光性能
准直膜的最终重要的性能指标是挡住杂光的能力，一般用所能挡住斜射光的最小角度来评价。当准直膜各项参数确定时，可以通过常规光学模拟软件(Light tools、ZeMax、Tracepro等)，或是理论计算得出能完全遮挡住斜射光的最小角度θ。如图10所示准直膜最小角度测试过程，本发明根据θ的大小(精确到0.5°)，将挡光性能进行了5个等级的划分，依次对应关系为：极优：0°≤θ<5°、优：5°≤θ<7.5°、良：7.5°≤θ<10°、中：10°≤θ<15°)、差：θ≥15°。
(B)透光性能
准直膜另一重要的性能指标是透过信号光的能力。用垂直准直光源入射可以检验准直孔和微透镜之间的对位精度：当对齐程度足够高时，光斑始终在准直孔直径范围中，此时透光性能最好，透过率(透光率)最大(利用光学模拟或激光头高精度条件下的标准样测试得到，一般在90％附近)；当对位误差增加时透过率会不断衰减；由于准直孔数量非常大，用该方式可以在宏观条件下测试出透过率变化，以此来比较对齐程度。本发明将测试 所得的透过率与最高透过率(最高透过率指微透镜的主光轴与对应的准直孔的中心线完全重合的情况下测得的光透过率)的比值定义为透光系数k，对齐程度足够高时为1。本发明根据k的大小，将透光性能进行了5个等级的划分，依次对应关系为：极优：1≥k>0.95、优：0.95≥k>0.9、良：0.9≥k>0.8、中：0.8≥k>0.6、差：k≤0.6。
显然，上述两个性能对于准直膜都是至关重要的：k越大，信号越强；θ越小，噪音越少；两个参数都对加强图像识别信噪比(SNR)有极大的帮助。
实施例2-24
如实施例1提供的准直膜，所述准直膜中的准直透镜阵列与准直孔阵列均为正三角形紧密排列，所述准直透镜层41的材质为PMMA，柔性基体层42的材质为PET，准直孔层43的遮光介质43A为无机镀层碳化钛，所述准直膜采用微透镜打孔方式打出准直孔43B，所述其他各项参数如表1所列。
表1 实施例1～24的设计参数和光学性能
Figure PCTCN2021074161-appb-000001
Figure PCTCN2021074161-appb-000002
注1：P为微透镜的主光轴最小间距，单位μm；R为微透镜的曲率半径，单位μm；H为准直透镜层厚度，单位μm；n1为准直透镜层的折射率，无量纲单位；T为柔性基体层的厚度，单位μm；n2为柔性基体层的折射率，无量纲单位；D为经过微透镜聚焦后在柔性基体层下表面形成的光斑直径，单位μm；t为准直孔层的厚度，单位μm；φ为准直孔的直径，单位μm；θ为准直膜可以滤掉的最小斜射光角度，用以衡量准直滤光效果，单位°；k为准直膜实际透过率与最高透过率的比值，用以衡量准直孔与微透镜的对位精度。
如表1所示，为25μm厚度的柔性基底层上不同P值设计相对较优的实施例。当P值分别为10、15、18、20、25、30μm时，各有四个实施例对应。可以发现，当P值和其他条件不变时，增加R值时，会让透镜变浅(指肉厚层的高度增加；而透镜的拱高，即透镜顶点至肉厚层上表面的高度变小)，焦距变远，遮光层上微聚焦的光斑变大，因此还需配合H的增加，使焦点回归到遮光层上，光斑缩小，R、H的配合变化，可以让微聚焦光斑直径D不断缩小，最小挡光角θ逐渐降低，挡光性能提升。针对透光性能，光斑直径D越接近开孔(准直孔)直径φ时，对位偏差Δ对透光率影响越大，稍有偏离，就会产生信号光的损失，而D相对φ较小时，对位偏差的影响就小，无论向哪个方向移动都仍在孔内。本发明提供的实施例1-24都固定开孔直径φ为4μm，除了实施例21～23中D和φ比较接近外，其他实施例均保持一定的差异，透光系数k大于0.9。总体而言，实施例1-24绝大部分都可以达到挡光性能和透光性能双优以上的水准，是基于25μm厚度柔性基底的较优实施效果。
实施例25-30
如实施例1提供的准直膜，所述准直膜中准直透镜阵列与准直孔阵列均为正三角形紧密排列，所述准直透镜层41的材质为PMMA，柔性基体层42的材质为PET，准直孔层43的遮光介质43A为无机镀层碳化钛，所述准直膜采用微透镜打孔方式打出准直孔43B， 所述其他各项参数如表2所列。
表2 实施例25～30的设计参数和光学性能
Figure PCTCN2021074161-appb-000003
注1同表1。
如表2所示，为不同柔性基体厚度的实施例25～30。实施例25～27分别为P＝10μm，其他参数不变的条件下，T＝10、15、20μm的一组准直膜，实施例28～30分别为P＝25μm，其他参数不变的条件下，T＝25、38、50μm的另一组准直膜。当T不断增加时，为保持微聚焦效果(焦点始终落在基体下表面与遮光层附近且光斑尽量缩小)，微透镜结构显然需要变浅，即固定P值和折射率搭配的情况下，R值增加，H变低(相比于表1实施例的差异，焦距设计已经随着T的增加进行适配，因而H不需要增加，反而是下降的)。可以发现，其他条件不变时，厚度T增加，有助于结构变浅，光斑D缩小，最小挡光角θ降低，挡光性能提升，且透光系数也进一步提升。因此，在厚度能允许的范围里(超薄应用越来越普遍，太厚也是不允许的)，用相对较厚的基体，对准直膜的性能提高是有帮助的，符合大长径比的准直膜性能更优的原理(如图3所示原理)。综合上述，本发明中T选自10～50μm，进一步优选为25～38μm。
实施例31-40
如实施例1提供的准直膜，所述准直膜的准直透镜阵列与准直孔阵列均为正三角形紧密排列，所述准直透镜层41的材质为PMMA，柔性基体层42的材质为PET，准直孔层43的遮光介质43A为无机镀层碳化钛，所述准直膜采用微透镜打孔方式打出准直孔43B，所述其他各项参数如表3所列。
表3 实施例31～40的设计参数和光学性能
Figure PCTCN2021074161-appb-000004
Figure PCTCN2021074161-appb-000005
注1同表1。
如表3所示，对比实施例31～36可以发现，当其他条件不变，P值不断增大，R值变大，若保持原深宽比，按照相似原则，焦距会变远，因而H变大。即便能控制焦距，但仍无法防止光斑半径D以及θ增加，相同开孔直径下，k也会因此下降。因此，总体而言，P值变大是不利于准直膜性能的，这也符合大长径比的准直膜性能更优的原理(如图3所示原理)。此外，对比实施例37与33，38与34，39与35，当光斑D足够小时，可以通过调整激光能量使开孔直径φ减小，并不一定局限一个固定值，可以发现开孔直径降低后可以进一步提高挡光性能，但透光效果会有所降低。实施例40的P值为50μm，相应的R和H都较大，整体而言对于本发明的准直膜而言，微透镜尺寸已经达到设计上限，包括光斑直径D也较大(D特别小，尤其是小于0.5μm也并不好，容易造成单点能量过高，烧伤基体)导致开孔直径φ达到上限8μm，同时最小挡光角θ为12度也较大，挡光性能并不算太好。综合上述，本发明中P选自10～50μm，优选为15～30μm，进一步优选为18～25μm。φ选自1～10μm(10μm来自实施例47)，进一步优选为3～5μm。D选自0.1～7.8μm，优选为0.5～4.9μm，进一步优选为1～2μm。
实施例41-47
如实施例1提供的准直膜，所述准直膜的准直透镜阵列与准直孔阵列均为正三角形紧密排列，所述准直透镜层41的材质为PMMA，柔性基体层42的材质为PET，准直孔层43的遮光介质43A为无机镀层碳化钛，所述准直膜采用微透镜打孔方式打出准直孔43B，所述其他各项参数如表4所列。
表4 实施例41～47的设计参数和光学性能
Figure PCTCN2021074161-appb-000006
Figure PCTCN2021074161-appb-000007
注1同表1。
如表4所示，为不同准直孔层厚度t的实施例41～47。对比第一组实施例41～44或对比第二组实施例45～47可知，在其他条件不变时，增加t有助于提高挡光性能，t太薄并非优选值。由于激光打孔一般会形成较小深宽比的空洞，因而开孔直径往往比t要大一些，因此实际上当t太厚时，会导致开孔直径过大(如第二组实施例)反而逐渐降低挡光性能。本发明中t选自0.5～7μm，优选为1～5μm，进一步优选为2～3μm。
实施例48-57
如实施例1提供的准直膜，所述准直膜的准直透镜阵列与准直孔阵列均为正三角形紧密排列，所述准直透镜层41的材质为PMMA，进一步的，由光固化丙烯酸树脂聚合而成，折射率n1从1.4～1.6可调，当n2＝1.65时，柔性基体层42的材质为PET，当n2＝1.5时，柔性基体层42的材质为COP，准直孔层43的遮光介质43A为无机镀层碳化钛，所述准直膜采用微透镜打孔方式打出准直孔43B，所述其他各项参数如表5所列。
表5 实施例48～57的设计参数和光学性能
Figure PCTCN2021074161-appb-000008
Figure PCTCN2021074161-appb-000009
注1同表1。
如表5所示，为不同折射率搭配的实施例48～57。对比第一组实施例48～52可知，在其他条件不变时：1.增加n1(对比实施例50、48、49或对比实施例51、52)有助于缩小光斑D，降低θ并提高挡光性能，n1＝1.6时最佳，n1＝1.4时最差；2.降低n2(实施例51、52与实施例48、49对比)同样有效。对比第二组实施例53～57，折射率影响的规律仍相同，然由于第二组结构较浅，性能本就足够优异，因此影响并没有那么大。对于n1而言，太高或太低折射率的成型材料选择面会比较窄，而对于n2而言，更多的是考虑柔性基体本身的物理性能和透光率等性能，而折射率仅用于准确设计结构而已。因此，本发明中n1选自1.4～1.6，优选为1.5。n2选自1.5～1.65，依据材料差异，不做优选。
实施例58
如实施例48提供的准直膜，所述准直膜的准直透镜阵列与准直孔阵列均为正方形紧密排列(如图7所示)，所述准直透镜层41的材质为PMMA，柔性基体层42的材质为PET，准直孔层43的遮光介质43A为无机镀层碳化钛，所述准直膜采用微透镜打孔方式打出准直孔43B，所述其他各项参数如表6所列。
表6 实施例48、58的设计参数和光学性能
Figure PCTCN2021074161-appb-000010
注1同表1。
从表6可知，当其他参数不变时，微透镜的分布方式从正三角形改为正方形，依然可以通过R、H的搭配设计，获得一款准直膜。但准直膜的性能相对于正三角形的分布稍差。主要原因是因为正方形分布没有正三角形致密，对角线与P之间的比值，正方形更大，因而相同P值，正方形排布的球冠显得更凸一些，从而导致光斑更散，D更大，同时θ上升，挡光效果变差，D变大又同时导致透光性能变差。当然，正方形排布并非不可取，为达到相同效果，需要设计更小的P值即可。本发明不再赘述更多正方形分布的实施例，正方形 分布始终在本发明的保护范围内。
实施例59-80
如实施例53～57提供的准直膜，所述准直膜的准直透镜阵列与准直孔阵列均为正三角形紧密排列，准直透镜层微透镜的主光轴最小间距P为20μm，曲率半径R为18.3μm，准直透镜层总厚4.1μm，柔性基体层厚度50μm，准直孔层厚度为2μm，准直孔直径φ为4μm，所述准直膜采用微透镜打孔方式打出准直孔43B，微透镜与准直孔对位误差Δ均<1μm。挡光角度θ均小于5°，挡光性能极优，透光系数k均大于0.95，透光性能极优。所述准直透镜层的材质、柔性基体层的材质以及准直孔层遮光介质的材质如表7所列，准直透镜层折射率n1和柔性基体层折射率n2依据材质，依材质而异，且允许±0.02同材质不同工艺造成的误差，表中不再列出。
表7 实施例59～80的设计参数和光学性能
Figure PCTCN2021074161-appb-000011
Figure PCTCN2021074161-appb-000012
注1同表1。
注2：对于准直透镜层同种材质，成型方式不限于光固化、热固化、注塑、热压等。
如表7所示，比较实施例59～80可知，改变材质前后，若材质的折射率相同或接近，对准直膜的性能影响不会太大。
应当注意，以上所述，仅为本发明的几种典型的实施例而已，并非用于限定本发明的保护范围。凡是根据本发明内容所做的均等变化与修饰，均涵盖在本发明的专利范围内。

Claims (10)

  1. 一种准直膜，其特征在于，所述准直膜依次包括准直透镜层、柔性基体层和准直孔层。
  2. 根据权利要求1所述的准直膜，其特征在于，所述准直膜依次包括准直透镜层、柔性基体层和一层准直孔层。
  3. 根据权利要求2所述的准直膜，其特征在于，所述准直透镜层包含微透镜阵列和肉厚，所述准直孔层包含准直孔阵列。
  4. 根据权利要求3所述的准直膜，其特征在于，所述准直孔层包含遮光介质层和准直孔阵列。
  5. 根据权利要求3所述的准直膜，其特征在于，所述准直孔阵列与微透镜阵列的分布完全一致。
  6. 根据权利要求5所述的准直膜，其特征在于，每一个准直孔均在相对应微透镜的主光轴上；所述准直透镜层的微透镜阵列为有序排布。
  7. 根据权利要求3所述的准直膜，其特征在于，所述准直透镜层的微透镜阵列与所述准直孔层的准直孔阵列均为有序排布。
  8. 根据权利要求3所述的准直膜，其特征在于，在所述准直透镜层的微透镜阵列中，相邻的三个微透镜的主光轴的坐标相连形成正三角形，或者，相邻的四个微透镜的主光轴的坐标相连形成正方形；所述微透镜阵列中的微透镜紧密排列。
  9. 根据权利要求3所述的准直膜，其特征在于，在所述准直透镜层中，相邻微透镜的主光轴的间距P为10～50μm，微透镜的半径R为6.1μm-30.2μm，准直透镜层的高度H为1.1μm-27.4μm，准直透镜层材质的折射率n1为1.34～1.7；
    在所述柔性基体层中，柔性基体层的厚度T为10～50μm，柔性基体层材质的折射率n2为1.48～1.7；
    在所述准直孔层中，准直孔层的厚度t为0.5～7μm，准直孔阵列中的准直孔的直径φ为1～10μm。
  10. 根据权利要求1-9中任一项所述的准直膜的制备方法，其特征在于，所述准直膜的准直孔采用微聚焦法打孔；在所述制备方法中，使激光垂直照射准直透镜层，激光通过准直透镜层的微透镜聚焦，聚焦形成的光斑落在准直孔层上打出准直孔。
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