CN113296276A - Collimating film and preparation method thereof - Google Patents
Collimating film and preparation method thereof Download PDFInfo
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- CN113296276A CN113296276A CN202010111367.6A CN202010111367A CN113296276A CN 113296276 A CN113296276 A CN 113296276A CN 202010111367 A CN202010111367 A CN 202010111367A CN 113296276 A CN113296276 A CN 113296276A
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- G—PHYSICS
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Elements Other Than Lenses (AREA)
Abstract
The invention relates to a collimating film, in particular to a collimating film in the field of image recognition and a preparation method thereof. The invention provides a collimating film and a preparation method thereof, aiming at solving the problem that two layers of collimating diaphragms in a traditional rigid collimating film are difficult to align. The collimating film sequentially comprises a collimating lens layer, a flexible substrate layer and a collimating hole layer; the collimating lens layer comprises a microlens array and a thickness, and the collimating aperture layer comprises a collimating aperture array; the distribution of the collimation hole array and the micro-lens array is completely consistent; the micro-lens array of the collimating lens layer is orderly arranged. The collimating film provided by the invention only comprises one collimating aperture layer, and the problem that two layers of collimating diaphragms are difficult to align is solved. The collimating film can collimate and filter diffused light at a single-point pixel position of an image to a certain degree to form a normal small beam light signal, and transmits the normal small beam light signal to a corresponding photoelectric sensor, and is particularly suitable for large-size, ultrathin and even flexible image identification modules.
Description
Technical Field
The invention relates to a collimating film, in particular to a collimating film in the field of image recognition and a preparation method thereof.
Background
In the field of image recognition, a common image sensor such as a CMOS type or a photo-TFT type generally includes a collimator device in a sensor module to enhance a signal-to-noise ratio, improve a recognition rate, and reduce crosstalk. The collimating device (as shown in fig. 1) mainly collimates and filters diffused light at a single-point pixel of an image, and the formed normal collimated light or nearly collimated light (signal) can be smoothly transmitted to a corresponding photoelectric sensor, while light (noise) with a large angle deviating from the normal direction can only rarely or even cannot enter a non-corresponding photoelectric sensor, so that the signal-to-noise ratio is enhanced.
The collimating devices typically have a top collimating structure layer and a bottom collimating structure layer: first, the top and bottom double-layer collimating structures need to be aligned precisely, otherwise the intensity of the signal light is greatly reduced (as shown in fig. 2); secondly, the distance between the top (entrance) and bottom (exit) collimating structures needs to be increased, or/and the microstructure size needs to be reduced (as shown in fig. 3) to increase the overall aspect ratio, otherwise the transmission of crosstalk light will be increased.
The traditional collimating device is generally a rigid collimating sheet, such as an optical fiber bundle slice, or a Microlens (Microlens), a collimating diaphragm and the like formed on two sides of a glass substrate, and the rigid collimating sheet generally needs to keep higher thickness, on one hand, the rigid collimating sheet is used for keeping the length-diameter ratio, on the other hand, the rigid collimating sheet is used for keeping the mechanical property of the rigid collimating sheet and preventing the rigid collimating sheet from being broken in an application environment. However, even then, such rigid collimating sheet still cannot satisfy the application of large-sized image recognition module. In particular, applications requiring a reduced overall thickness (e.g., ultra-thin, large screen handsets) become more fragile, and less productive, both performance and cost. It is also apparent that such rigid collimating sheets are less likely to be in a flexible image recognition module.
Except for the optical fiber bundle type collimating sheets (the top layer collimating structure and the bottom layer collimating structure are aligned originally), most of the rigid collimating sheets need to complete the alignment of two layers of collimating structures (collimating diaphragms). However, the two-layer structure prepared in sequence needs to be aligned with high precision, which has considerable difficulty: firstly, very complex and expensive double-shaft positioning equipment is needed, the positioning process is complicated and time-consuming, if the collimation structure size is less than 50 micrometers (image precision DPI >508), the lattice scale can reach hundreds of millions of points per square meter, and the production efficiency is extremely low; secondly, the alignment method is not accurate in practice, and especially when the size of the collimating structure is reduced and the number of collimating structures is increased, the accumulated error becomes more obvious, which results in the decrease of signal light intensity, and frequent origin correction becomes more time-consuming.
In conclusion, the traditional rigid collimating sheet has the problems of high thickness, fragility and poor performance under the condition of low thickness, difficult alignment of two layers of collimating structures (collimating diaphragms), low yield and low productivity, and is difficult to apply to the field of large-size, ultrathin and flexible image recognition.
Disclosure of Invention
The invention provides a collimating film and a preparation method thereof, aiming at solving the problem that two layers of collimating diaphragms in a traditional rigid collimating film are difficult to align. The collimating film provided by the invention only comprises one collimating aperture layer, and the problem that two layers of collimating diaphragms are difficult to align is solved.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention provides a collimating film, which sequentially comprises a collimating lens layer, a flexible substrate layer and a collimating hole layer.
The collimation hole layer is a collimation diaphragm.
The collimating film provided by the invention only comprises one layer of collimating diaphragm. The collimating film provided by the invention only comprises one collimating hole layer.
The collimating film sequentially comprises a collimating lens layer, a flexible substrate layer and a collimating hole layer.
The collimating lens layer is arranged on the upper surface of the flexible substrate, and the collimating hole layer is arranged on the lower surface of the flexible substrate.
The collimating lens layer includes a microlens array and a thickness.
The collimating aperture layer comprises an array of collimating apertures.
The collimation hole layer comprises a shading medium layer and a collimation hole array.
The collimation hole layer comprises a shading medium and a collimation hole array formed after the medium is hollowed out.
The distribution of the collimation hole array and the micro-lens array is completely consistent. Each collimating aperture is on the primary optical axis of the corresponding microlens. Furthermore, the center of each collimating hole is on the main optical axis of the corresponding microlens.
The collimating film is punched by adopting a micro-focusing method, the distribution of the collimating hole array is completely consistent with that of the micro-lens array, the circle centers of any collimating hole are all positioned on the main optical axis of the corresponding micro-lens, one-to-one high-precision alignment is carried out, and the alignment deviation delta is less than 1 mu m. The thickness T of the flexible substrate layer is 10-50 μm, preferably 25-38 μm.
The micro-lens array of the collimating lens layer is orderly arranged.
The micro-lens array of the collimation lens layer and the collimation hole array of the collimation hole layer are arranged in sequence.
One collimating hole in the collimating hole array corresponds to the position of one microlens in the microlens array, and the main optical axis of the microlens coincides with the center of the collimating hole or the deviation of the main optical axis and the center of the collimating hole is less than 1 μm. One microlens corresponding to one alignment hole position is referred to as a corresponding microlens of this alignment hole. The coordinates of the main optical axes of three adjacent microlenses are connected to form a regular triangle (formed by connecting the coordinates of the main optical axes of three mutually overlapped microlenses), or the coordinates of the main optical axes of four adjacent microlenses are connected to form a square (formed by connecting the coordinates of the main optical axes of four mutually overlapped microlenses).
The microlenses in the microlens array are closely arranged. I.e., 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 in regular triangle (formed by connecting the coordinates of the main optical axes of three mutually overlapped micro lenses) close arrangement or square (formed by connecting the coordinates of the main optical axes of four mutually overlapped micro lenses) close arrangement.
Furthermore, in the collimating lens layer, the distance P between the main optical axes of the adjacent micro lenses is 10-50 μm, the radius R of the micro lenses is 6.1-30.2 μm, the height H of the collimating lens layer is 1.1-27.4 μm, and the refractive index n1 of the collimating lens layer material is 1.4-1.6; in the flexible substrate layer, the thickness T of the flexible substrate layer is 10-50 mu m, and the refractive index n2 of the flexible substrate layer material is 1.5-1.65; in the collimation hole layer, the thickness t of the collimation hole layer is 0.5-7 μm, and the diameter phi of collimation holes in the collimation hole array is 1-10 μm.
The pitches P of the main optical axes of the micro lenses are the same, and P is selected from 10-50 μm, preferably 15-30 μm, and more preferably 18-25 μm.
The micro lens of the collimating film focuses vertically incident light rays, and light spots with the diameter D are formed on the lower surface of the flexible substrate layer, wherein D is selected from 0.1-7.8 micrometers, preferably 0.5-4.9 micrometers, and further preferably 1-2 micrometers.
The spot diameter D is determined by the curvature radius R (spherical radius R) of the microlens, the refractive index n1, the collimating lens layer thickness H (vertical distance from the apex of the microlens to the upper surface of the substrate), and the refractive index n2 and the thickness T of the flexible substrate layer.
The curvature radius R of the micro lens is selected from 6.1-30.2 mu m, the thickness H of the collimating lens layer is selected from 1.1-27.4 mu m, R and H are not preferred, and the micro lens is adapted according to other parameters.
The refractive index n1 of the collimating lens layer (i.e. the micro lens layer) is selected from 1.4-1.6, and preferably 1.5.
The refractive index n2 of the flexible substrate layer is selected from 1.5-1.65, and is different according to materials, is not preferred, and allows errors caused by different processes of plus or minus 0.02 same materials.
The micro-lens array of the collimating film is made of the same material as the thick meat, and the material is transparent polymer.
Further, the transparent polymer of the microlens layer is selected from one of AR (Acrylic Resin, Acrylic Resin or modified Acrylic 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 preferable that the material is one of PMMA (polymethyl methacrylate), PC, or PS.
The flexible matrix layer of the collimating film is selected from transparent polymer films. The flexible substrate layer may be bendable.
Further, the material of the transparent polymer film of the flexible substrate layer is selected from one of PET, PEN, PI, PC, PMMA (polymethyl methacrylate), PP (polypropylene), PO (polyolefin), SR, or COP (cyclic olefin copolymer). Further, one of PET, PI, PC, and PMMA is preferable.
The shading medium of the collimation hole layer of the collimation film is selected from one or the combination of at least two of organic coating and inorganic plating. The organic coating of the opacifying medium is selected from opaque polymeric ink systems.
Further, the opaque polymer ink system of the light-screening medium comprises a light-absorbing substance and a polymer curing system.
Further, the light absorbing material is selected from one or a combination of at least two of carbon (such as carbon black, carbon fiber, graphite, etc.), carbide (such as chromium carbide, titanium carbide, boron carbide, etc.), carbonitride (such as titanium carbonitride, boron carbonitride, etc.), sulfide (such as ferrous sulfide, molybdenum disulfide, cobalt disulfide, nickel sulfide, etc.).
Further, the polymer curing system of the shading medium may be selected from one or a combination of at least two of an acrylic system (AR), a polyurethane system (PU), a silicone System (SR), an epoxy system (EP), a melamine resin system (MF), a phenolic resin system (PF), a urea-formaldehyde resin system (UF), or a thermoplastic elastomer material (e.g. ethylene-vinyl acetate copolymer, thermoplastic elastomer TPE or thermoplastic polyurethane elastomer TPU).
Further, the polymer curing system may be selected from one or a combination of at least two of an acrylic resin system, a polyurethane system, a silicone system, an epoxy resin system, or a thermoplastic elastomer.
The inorganic coating of the shading medium is selected from one or the combination of at least two of simple carbon, carbide, carbonitride and sulfide.
The thickness t of the collimation hole layer of the collimation film is selected from 0.5-7 μm, preferably 1-5 μm, and further preferably 2-3 μm.
The diameter phi of the collimation hole layer of the collimation film is selected from 1-10 mu m, and the preferred diameter phi is 3-5 mu m.
Further, the flexible matrix layer thickness T may be 10 μm to 50 μm, such as 10 μm, 15 μm, 20 μm, 25 μm, 38 μm or 50 μm.
Further, the chief optical axis pitch P of adjacent microlenses of the collimating lens layer may be 10 μm to 50 μm, such as 10 μm, 15 μm, 18 μm, 20 μm, 25 μm, 30 μm, or 50 μm.
Further, the radius of curvature R of the microlenses of the collimating lens layer can be 6.1 μm to 30.2 μm, such as 6.1 μm, 6.9 μm, 7.9 μm, 9.4 μm, 11.2 μm, 11.3 μm, 12 μm, 12.1 μm, 12.6 μm, 12.8 μm, 13.3 μm, 13.6 μm, 14 μm, 14.3 μm, 14.3 μm, 14.8 μm, 15 μm, 15.1 μm, 15.7 μm, 15.9 μm, 16 μm, 16.1 μm, 16.7 μm, 17 μm, 17.2 μm, 17.3 μm, 18 μm, 18.1 μm, 18.3 μm, 18.8 μm, 19.3 μm, 19.4 μm, 19.6 μm, 19.8 μm, 20.3 μm, 20.6 μm, 20.5 μm, 22.5 μm, or 22.6 μm.
Further, the collimating lens layer thickness H may be 1.1 μm to 27.4 μm, such as 1.1 μm, 2.4 μm, 2.5 μm, 3.0 μm, 3.1 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4.1 μm, 5.0 μm, 5.8 μm, 6.0 μm, 6.2 μm, 6.8 μm, 7.2 μm, 7.8 μm, 8.5 μm, 8.6 μm, 8.7 μm, 9.2 μm, 10.4 μm, 10.7 μm, 10.8 μm, 11 μm, 11.1 μm, 11.4 μm, 11.5 μm, 12.9 μm, 13.6 μm, 14.1 μm, 14.6 μm, 15.0 μm, 15.4 μm, 16.4 μm, 11.5 μm, 12.9 μm, 13.6 μm, 14.1 μm, 14.6 μm, 15.0 μm, 15.4 μm, 3.2 μm, 22.2 μm, 22.5 μm, 2 μm, or 22.2 μm.
Further, the diameter D of the light spot formed by the micro-lenses on the lower surface of the flexible substrate layer may be 0.1 μm to 7.8 μm, such as 0.1 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 2.0 μm, 2.2 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.8 μm, 3.1 μm, 3.4 μm, 3.6 μm, 3.7 μm, 3.9 μm, 4.0 μm, 4.9 μm, or 7.8 μm.
Further, the thickness t of the collimating aperture layer may be 0.5-7 μm, such as 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, or 7 μm.
Further, the diameter of the collimating aperture φ may be 1-10 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 8 μm, or 10 μm.
Further, the collimating lens layer may have a refractive index n1 of 1.34-1.7, such as 1.34, 1.4, 1.47, 1.48, 1.5, 1.59, 1.6, 1.65, 1.66, or 1.7.
Further, 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.
Further, the collimating film provided by the invention comprises a collimating lens layer (41), a flexible substrate layer (42) (simply referred to as a substrate) and a collimating hole layer (43), wherein the collimating lens layer is arranged on the upper surface of the substrate, the collimating hole layer is arranged on the lower surface of the substrate, the collimating lens layer (41) comprises a micro-lens array (41A) and a thick-flesh layer (41B), and the collimating hole layer (43) comprises a light-shielding medium (43A) and a collimating hole array (formed by a certain number of collimating holes (43B)) formed after the medium is hollowed out.
In examples 1 to 24, the collimating lens array and the collimating aperture array in the collimating film are both arranged in a regular triangle, the collimating lens layer (41) is made of PMMA, the flexible substrate layer (42) is made of PET, the light-shielding medium (43A) of the collimating aperture layer (43) is inorganic plated titanium carbide, and the collimating film is perforated with collimating apertures (43B) in a microlens perforation manner. The other parameters are as follows:
p is 10-30 μm, R is 9.4-20.6 μm, H is 3-27.4 μm, and n1 is 1.5;
t is 25 μm, n2 is 1.65, and D is 0.3-4.0 μm;
t is 2.0 μm and phi is 4.0 μm. Further, the deviation Δ is 0.18 to 0.90 μm.
In embodiments 25 to 30, the collimating lens array and the collimating aperture array in the collimating film are both arranged in a regular triangle, the collimating lens layer (41) is made of PMMA, the flexible substrate layer (42) is made of PET, the light-shielding medium (43A) of the collimating aperture layer (43) is inorganic plated titanium carbide, the collimating film punches the collimating aperture (43B) in a microlens punching manner, and the other parameters are as follows:
p is 10-25 μm, R is 6.1-19.8 μm, H is 2.5-10.7 μm, n1 is 1.5;
t is 10-50 μm, n2 is 1.65, and D is 0.6-3.9 μm;
t is 1.0-3.0 μm, and phi is 2.0-5.0 μm. Further, the deviation Δ is 0.26 to 0.49 μm.
In embodiments 31 to 40, the collimating lens array and the collimating aperture array of the collimating film are both arranged in a regular triangle, the collimating lens layer (41) is made of PMMA, the flexible substrate layer (42) is made of PET, the light-shielding medium (43A) of the collimating aperture layer (43) is inorganic plated titanium carbide, the collimating film is perforated with collimating apertures (43B) by using a microlens perforation method, and other parameters are as follows:
p is 10-50 μm, R is 16-30.2 μm, H is 1.1-21.3 μm, and n1 is 1.5;
t is 50 μm, n2 is 1.65, D is 0.1-7.8 μm;
t is 0.5 μm and phi is 1.0-8.0 μm. Further, the deviation Δ is 0.21 to 0.88 μm.
In embodiments 41 to 47, the collimating lens array and the collimating aperture array of the collimating film are both arranged in a regular triangle, the collimating lens layer (41) is made of PMMA, the flexible substrate layer (42) is made of PET, the light-shielding medium (43A) of the collimating aperture layer (43) is inorganic plated titanium carbide, the collimating film is perforated with collimating apertures (43B) by using a microlens, and other parameters are as follows:
p is 30 μm, R is 19.3 μm, H is 10.8 μm, n1 is 1.5;
t is 38 μm, n2 is 1.65, D is 3.6 μm;
t is 0.5-7 μm and phi is 5.0-10.0 μm. Further, the deviation Δ is 0.46 to 0.99 μm.
In examples 48 to 57, the collimating lens array and the collimating hole array of the collimating film are both regularly triangular and closely arranged, the collimating lens layer (41) is made of PMMA, and further, is polymerized from a photo-curable acrylic resin, the refractive index n1 is adjustable from 1.4 to 1.6, when n2 is 1.65, the flexible substrate layer (42) is made of PET, when n2 is 1.5, the flexible substrate layer (42) is made of COP, the light-shielding medium (43A) of the collimating hole layer (43) is inorganic plated titanium carbide, the collimating film is perforated by microlenses to form collimating holes (43B), and other parameters are as follows:
p is 20-25 μm, R is 15.9-22.5 μm, H is 3.2-9.2 μm, n1 is 1.4-1.6;
t is 38-50 μm, n2 is 1.5-1.65, D is 0.5-3.6 μm;
t is 2.0 μm and phi is 4.0 μm. Further, the deviation Δ is 0.25 to 0.66 μm.
In example 58, the collimating lens array and the collimating aperture array of the collimating film are both arranged in a square shape (as shown in fig. 7), the collimating lens layer (41) is made of PMMA, the flexible substrate layer (42) is made of PET, the light-shielding medium (43A) of the collimating aperture layer (43) is inorganic plated titanium carbide, the collimating film is perforated with collimating apertures (43B) by using a microlens perforation method, and other parameters are as follows:
p is 25 μm, R is 19.6 μm, H is 11.1 μm, n1 is 1.5;
t is 38 μm, n2 is 1.65, D is 3.9 μm;
t is 2.0 μm and phi is 4.0 μm. Further, the deviation Δ was 0.69 μm.
The invention also provides a preparation method of the collimating film, and the collimating holes of the collimating film are punched by adopting a micro-focusing method.
Furthermore, in the preparation method, laser is made to vertically irradiate the collimating lens layer, the laser is focused through the micro lens of the collimating lens layer, and a light spot formed by focusing falls on the collimating lens layer to form a collimating hole. In the collimation film prepared by the method, the distribution of the collimation hole array and the micro-lens array is completely consistent, and the circle center of any collimation hole is on the main optical axis of the corresponding micro-lens.
Further, the preparation method comprises the following steps:
(1) forming the collimating lens layer on the upper surface of the flexible substrate layer by adopting a lens array (concave) mould (light curing, heat curing, hot press forming and other modes can be adopted) to form a lens array (convex);
(2) coating/plating a shading medium on the lower surface of the substrate layer by adopting a wet method/dry method coating technology;
(3) the large-area flat-top laser (parallel laser after Gaussian beam shaping) is adopted, a micro-lens array is vertically irradiated with proper low energy, each micro-lens is focused on a shading medium (namely, a micro-focusing method) and corresponding collimating holes are punched, so that collimating hole arrays in the same distribution are generated, and a collimating hole layer is formed.
Further, the micro-focusing method comprises the following features:
(1) flat-top laser after beam shaping is adopted as a laser source, the irradiation area is enlarged after shaping, and the energy density is reduced;
(2) the front side is irradiated, the energy density is low, and the energy is concentrated through the micro-focusing process of the micro-lens per se, so that the high energy density is realized;
(3) the micro-focused light spot is small enough in a reasonable range, the focal point position needs to be designed on the lower surface of the PET or a deeper position, and energy is concentrated on the shading layer (shading medium);
(4) the micro-lens layer has high universality, and is applicable to irregular micro-lens layers, such as poor lens arrangement precision and shape precision, uneven spacing and even disorder.
Further, the process of the micro-focusing method (as shown in fig. 4) is divided into four basic steps: (a) flat-top laser (5) is applied to a collimating lens layer (41) of a collimating film semi-finished product with proper energy (too high hole is too large, even the hole is burnt to a substrate, too low, no hole is formed), micro focusing is realized by a micro lens (41A), pre-reduction of the area of a light spot is realized by a thick plate (41B), finally the laser penetrates through the substrate layer (42) and is focused into a very small light spot on a shading medium (43A), and high concentration of energy is realized; (b) due to the absorption of the light by the shading medium, the energy is instantaneously accumulated to cause the shading medium at the position of the light spot to be instantaneously burnt through and generate some ash, and actually, the process of the first two steps only needs microsecond level and is very quick; (c) after the ash is extracted, the alignment holes (43B) are exposed, and the alignment holes are basically positioned on the main optical axis (40) of the micro lens and are highly aligned with the micro lens (41A), so that the time-consuming alignment process is avoided, and at the moment, the alignment film (4) is a finished product and comprises a complete structure, namely an alignment lens layer (41), a base layer (42) and an alignment hole layer (43); (d) the collimating film (4) meets the normal direction or is high in collimated light transmission close to the normal direction at the moment, a testing light source (such as white light, green light and a three-wave lamp) with common intensity can be used for irradiating from the surface of the micro-lens during online production, light can be transmitted out from the collimating hole, a light hole array image can be observed on the back surface, transmitted light intensity can be quantized, and therefore punching quality can be tested.
Compared with the micro-focusing method for punching provided by the invention, the traditional punching method has larger limitation (as shown in fig. 5): (a) the Gaussian laser (7) is focused through a lens group of the laser head and is shot on the shading medium (43A) from the back direction of the semi-finished product; (b) the different positions of the light shielding layer are sequentially burnt through, and some ash is generated; (c) as the ash is drawn away, the collimating holes are exposed. It can be seen that, in the whole alignment process, an original point O (or called Mark point) needs to be located, a CCD (Charge Coupled Device) high definition camera on the front side aligns the optical center of a lens, a laser head on the back side can be linked with the CCD camera on the front side to find the position of a corresponding alignment hole, so as to calculate the initial displacement (vector or coordinate difference) between the first point and the position, the initial positioning process is very time-consuming and complex, and the requirement on equipment is high; then, all the point positions can be calculated and positioned according to the initial displacement and the point displacement, 2-n points are sequentially punched, although the time can be shortened by using a vibrating mirror group in the process, n cannot be set too large, otherwise, the accumulated error inevitably exceeds 1 micrometer and is even larger, especially, the vibrating mirror can cause the angle inclination, the light spot becomes larger and deforms, and the error is accumulated more and more quickly; finally, when the error is unacceptably accumulated, the origin O is returned and the first point is found again, i.e. the initial positioning process is repeated. Throughout the whole process, although the time is shortened by adopting the galvanometer group, the n can not be too large, and the initial positioning process needs to be frequently carried out, so that the method is time-consuming, complex and dependent on equipment, and the punching process is high in cost and low in precision.
Further, the limitations of the conventional punching method are not limited to this: the process of locating the first point and calculating the 2-n points requires a precondition that the pitch of the microlenses is completely accurate; in fact, on one hand, the mold for the microlens is also prepared by laser drilling, and errors are inevitably generated, so that the alignment error of the traditional mode is further increased, especially when the mold precision is not so high; on the other hand, some special molds produce irregular microlens layers, which have poor arrangement precision and shape precision of the microlenses, or have non-uniform or even disordered designed spacing. Thus, the phase change of the conventional process increases the mold precision and manufacturing cost of the microlens layer, resulting in very high cost of the whole collimating film, not to mention the realization of the alignment punching of the irregular microlens layer (while the micro-focusing method of the present invention can be easily realized).
It should be noted that the microlens array forming method should be selected according to the kind and application of the transparent polymer, and the present invention is not preferred; the coating mode of the shading medium is selected according to the type of the shading medium, the organic coating needs to be selected from a wet coating mode, and the inorganic coating needs to be selected from a dry coating (namely physical vapor deposition) mode.
It should be noted that the method for preparing the collimating film provided by the invention is suitable for producing sheets and is also suitable for producing coiled materials.
The collimating film can be used as a flexible collimating device for an image sensor module. The collimating film can collimate and filter diffused light at a single-point pixel position of an image to a certain degree to form a normal small beam light signal, and transmits the normal small beam light signal to a corresponding photoelectric sensor, and is particularly suitable for large-size, ultrathin and even flexible image identification modules.
Compared with the prior art, the collimating film provided by the invention adopts the polymer film with the thickness of 10-50 μm as the flexible substrate layer, realizes the flexibility, ultrathin and large size of the collimating device, and is particularly suitable for large-size, ultrathin and even flexible image recognition modules.
Compared with the prior art, the collimating film provided by the invention adopts a micro-focusing method to punch, the distribution of the collimating hole array and the distribution of the micro-lens array are completely consistent, the circle center of each collimating hole is positioned on the main optical axis of the corresponding micro-lens, the collimating holes are aligned in a one-to-one high-precision mode, the alignment deviation is less than 1 mu m, the transmission of signal light is greatly improved, the collimating structure is allowed to be further reduced (such as the micro-lens and the collimating holes are synchronously reduced) to reduce crosstalk, the signal-to-noise ratio of the collimating film is improved, the production efficiency is greatly improved, and the cost is reduced.
Compared with the prior art, the collimating film provided by the invention only comprises one collimating aperture layer, the problem that two layers of collimating diaphragms are difficult to align with each other is fundamentally solved, the collimating film is low in thickness, good in toughness and not easy to break, the circle center of the collimating aperture prepared by adopting a micro-focusing method is on the main optical axis of the corresponding micro-lens, and the collimating aperture is accurately aligned with the corresponding micro-lens. The preparation method of the collimating film provided by the invention is easy to operate, can be used for mass production, and improves the production yield. The collimating film provided by the invention has excellent performance, and can filter diffused light by collimated light. The collimating film provided by the invention can be applied to large-size and ultrathin image identification modules, so that the mass production of the large-size, ultrathin and even flexible image identification modules is greatly improved, and when the collimating film is applied to a fingerprint unlocking scheme of consumer electronic products such as mobile phones (OLED screens), the collimating film has obvious advantages due to great market demands and higher pursuit on the characteristics such as ultrathin, large screens and flexibility.
Drawings
FIG. 1 is a schematic diagram of the basic principle of a collimating device;
FIG. 2 is a graph illustrating the effect of alignment accuracy of a collimated structure on signal strength; the higher the alignment precision is, the higher the signal intensity is;
FIG. 3 is a graph of the effect of the aspect ratio of the collimating structure on the crosstalk strength; the higher the length-diameter ratio, the smaller the crosstalk strength;
FIG. 4 illustrates a micro-focusing method of drilling;
FIG. 5 illustrates a conventional drilling alignment error accumulation process;
FIG. 6 is a schematic cross-sectional view of a collimating film provided by the present invention;
FIG. 7 is a schematic perspective view of a collimating film provided by the present invention (square arrangement);
FIG. 8 is a schematic perspective view of a collimating film provided by the present invention (regular triangle arrangement);
FIG. 9 is a schematic cross-sectional view of a collimating film (collimating sheet) provided in a comparative example;
fig. 10 shows the light blocking performance (minimum light blocking angle) test procedure of the collimating film provided by the present invention.
Wherein:
1: target image
11-17: 7 continuous pixel points of target image
2: collimating device
21: top (incident light) collimation structure layer
22: bottom (light-emitting) collimation structure layer
3: photoelectric sensing chip
31-37: photoelectric sensor corresponding to 7 continuous pixel points
4: the invention provides a collimating film
4': comparative example provided collimating film
40: middle axis of collimation structure (micro lens main optical axis)
41: collimating lens layer
41A: microlens array
41B: thickness of meat
41C: apex of microlens
42: substrate layer
43: collimating aperture layer
43A: light-screening medium
43B: collimation hole
5: flat-top beam laser
6: inspection light source
7: gaussian beam laser
O: laser positioning origin
Detailed Description
In order to make the structure and features of the invention easier to understand, preferred embodiments of the invention will be described in detail below with reference to the drawings.
Comparative example 1
Fig. 9 shows a collimating film for contrast, which includes a collimating lens layer 41, a flexible substrate layer (substrate for short) 42, and a collimating aperture layer 43, where the collimating lens layer is disposed on the upper surface of the substrate, the collimating aperture layer is disposed on the lower surface of the substrate, the collimating lens layer 41 includes a microlens array 41A and a thickness 41B, the collimating aperture layer 43 includes a light-shielding medium 43A and a collimating aperture array (composed of a certain number of collimating apertures 43B) formed by hollowing out the medium; the thickness T of the flexible substrate layer is 25 mu m. The collimating lens array and the collimating hole array of the collimating film are both in regular triangle close arrangement (as shown in fig. 8). The minimum distance P of the main optical axis of the micro lens is 18 mu m, the curvature radius R is 12.6 mu m, the thickness H of the collimating lens layer (the vertical distance from the top point of the micro lens to the upper surface of the substrate) is 8.5 mu m, the thickness t of the collimating hole layer is 2 mu m, and the diameter phi of the collimating hole is 4 mu m. The micro-lens array and the thick material of the collimating lens layer are both transparent polymer PMMA, the refractive index n1 is 1.5, the flexible substrate layer is made of transparent polymer film PET, the refractive index n2 is 1.65, and the shading medium 43A of the collimating lens layer 43 is inorganic coating titanium carbide. The collimating film is punched with collimating holes 43B by conventional laser punching (as shown in FIG. 5), the central positions of the main optical axis 40 and the collimating holes 43B have alignment deviation, and holes are punched one by one from the laser positioning origin O, and the alignment deviation of the first hole is Δ1The misalignment of the nth hole is Δn，Δn-1<Δn(n is a natural number greater than 2), the presence of n makes the misalignment Δ exceed 1 μm or even greater. The light transmission coefficient k is easily reduced, even to less than 0.6, and reaches the evaluation level of "poor".
Example 1
As shown in fig. 6, the collimating film provided by the present invention includes a collimating lens layer 41, a flexible substrate layer 42 and a collimating aperture layer 43, the collimating lens layer is disposed on the upper surface of the substrate, the collimating aperture layer is disposed on the lower surface of the substrate, the collimating lens layer 41 includes a micro lens array 41A and a thick flesh 41B, the collimating aperture layer 43 includes a light-shielding medium 43A and a collimating aperture array (composed of a certain number of collimating apertures 43B) formed after the medium is hollowed out; the thickness T of the flexible substrate layer is 25 mu m. The collimating lens array and the collimating hole array of the collimating film are both in regular triangle close arrangement (as shown in fig. 8). The micro-lens has a minimum distance P of a main optical axis of 18 μm, a curvature radius R of 12.6 μm, a thickness H of a collimating lens layer of 8.5 μm, a thickness t of a collimating hole layer of 2 μm, and a diameter phi of a collimating hole of 4 μm. The micro-lens array and the thick material of the collimating lens layer are both transparent polymer PMMA, the refractive index n1 is 1.5, the flexible substrate layer is made of transparent polymer film PET, the refractive index n2 is 1.65, and the shading medium 43A of the collimating lens layer is inorganic coating titanium carbide. The collimating film adopts a micro-focusing method punching mode (as shown in fig. 4) to punch a collimating hole 43B, the collimating hole array is completely consistent with the distribution of the micro-lens array, the circle centers of any collimating hole are all on the main optical axis 40 of the corresponding micro-lens, the collimating hole array and the micro-lens array are aligned in a one-to-one high-precision mode, and the alignment deviation delta between the circle centers of the collimating holes and the main optical axis of the corresponding micro-lens is 0.47 mu m and less than 1 mu m. When punching, the laser is just slightly focused on the lower surface of PET, the diameter D of a light spot is 1.7 mu m, the minimum light blocking angle theta is 7.5 degrees, the light transmission coefficient k is 0.98, and the performance advantage of the laser is obvious compared with that of comparative example 1 on the whole.
In fact, the combination of the structural parameters of the collimating lens is not limited to the above embodiments: for the same collimating and filtering effect, various changes can be made according to the material and refractive index of the collimating lens layer, the material and refractive index of the flexible substrate layer, for example, P, R, H, phi, t, etc. are changed correspondingly; aiming at the light shielding effect of the collimating holes with the same thickness t, various changes can be made to the light shielding medium, such as changes of the types, combinations and even proportions of organic coatings and inorganic coatings.
The properties of the collimating films provided by the present invention were evaluated in the following manner.
(A) Light blocking Property
The final important performance index of a collimating film is the ability to block stray light, and is generally evaluated by the minimum angle at which oblique light can be blocked. When various parameters of the collimating film are determined, the minimum angle θ capable of completely blocking oblique Light can be obtained through conventional optical simulation software (Light tools, ZeMax, Tracepro, etc.) or theoretical calculation. As shown in fig. 10, in the process of testing the minimum angle of the collimating film, the light blocking performance is classified into 5 levels according to the size of θ (accurate to 0.5 °), and the corresponding relationship in sequence is as follows: excellent: theta is more than or equal to 0 degree and less than 5 degrees, and is superior: theta is more than or equal to 5 degrees and less than 7.5 degrees, good: theta is more than or equal to 7.5 degrees and less than 10 degrees, wherein: theta is more than or equal to 10 degrees and less than 15 degrees, difference: theta is more than or equal to 15 degrees.
(B) Light transmission performance
Another important performance criterion of collimating films is the ability to transmit signal light. The alignment precision between the collimating hole and the micro-lens can be checked by using a vertical collimating light source for incidence: when the alignment degree is high enough, the light spot is always in the diameter range of the collimation hole, the light transmittance is the best, and the transmittance (light transmittance) is the maximum (obtained by using optical simulation or standard sample test under the high-precision condition of a laser head, generally about 90%); when the alignment error increases, the transmittance will be attenuated continuously; since the number of collimating holes is very large, the degree of alignment can be compared by measuring the transmittance change under macroscopic conditions in this manner. The ratio of the transmittance obtained by the test to the highest transmittance (the highest transmittance refers to the transmittance measured under the condition that the main optical axis of the micro lens is completely coincided with the central line of the corresponding collimating hole) is defined as a transmittance k, and the transmittance k is 1 when the alignment degree is high enough. The invention divides the light transmission performance into 5 grades according to the size of k, and the corresponding relations are as follows: excellent: k is more than or equal to 1 and more than 0.95, preferably: 0.95 is more than or equal to k is more than 0.9, good: 0.9 is more than or equal to k is more than 0.8, wherein: 0.8 is more than or equal to k is more than 0.6, the difference is: k is less than or equal to 0.6.
Obviously, both of the above properties are crucial for the collimating film: the larger k, the stronger the signal; the smaller θ, the less noise; both parameters are of great help to enhance the image recognition signal-to-noise ratio (SNR).
Examples 2 to 24
In the collimating film provided in embodiment 1, the collimating lens arrays and the collimating hole arrays in the collimating film are both arranged in a regular triangle, the collimating lens layer 41 is made of PMMA, the flexible substrate layer 42 is made of PET, the light-shielding medium 43A of the collimating hole layer 43 is inorganic plated titanium carbide, the collimating film is perforated with the collimating holes 43B by using a microlens perforation method, and the other parameters are listed in table 1.
TABLE 1 design parameters and optical Properties of examples 1-24
Note 1: p is the minimum distance of the main optical axis of the micro lens and is in the unit of mum; r is the curvature radius of the micro lens and the unit is mum; h is the thickness of the collimating lens layer in μm; n1 is the refractive index of the collimating lens layer, dimensionless; t is the thickness of the flexible substrate layer and the unit of micrometer; n2 is the refractive index of the flexible matrix layer, dimensionless units; d is the diameter of a light spot formed on the lower surface of the flexible substrate layer after being focused by the micro lens, and the unit of the diameter is mum; t is the thickness of the collimation bore layer, unit μm; phi is the diameter of the collimating hole and the unit is mum; theta is the minimum oblique light angle which can be filtered by the collimating film and is used for measuring the collimating and filtering effect in unit degree; k is the ratio of the actual transmittance to the highest transmittance of the collimating film, and is used for measuring the alignment precision of the collimating holes and the micro lenses.
As shown in table 1, relatively good examples were designed for different P values on a flexible substrate layer of 25 μm thickness. When the P values are 10, 15, 18, 20, 25 and 30 μm, respectively, four examples correspond to each other. It can be found that when the P value and other conditions are not changed, and the R value is increased, the lens becomes shallow (the height of the thick lens layer is increased, and the height of the lens arch, i.e. the height from the top point of the lens to the upper surface of the thick lens layer, becomes smaller), the focal length becomes farther, and the light spot of the micro-focus on the light shielding layer becomes larger, so that the focal point returns to the light shielding layer by matching with the increase of H, the light spot is reduced, and the matching change of R, H can continuously reduce the diameter D of the micro-focus light spot, gradually reduce the minimum light blocking angle theta, and improve the light blocking performance. For the light transmission performance, the more the spot diameter D is close to the opening (collimating hole) diameter phi, the more the alignment deviation Δ has an influence on the light transmission, and a slight deviation, the loss of the signal light is generated, while the smaller D is, the less the influence on the alignment deviation is, and the light is still in the hole regardless of the direction of movement. In the embodiments 1 to 24 provided by the invention, the diameter phi of the opening is fixed to be 4 μm, except that D and phi are relatively close in the embodiments 21 to 23, other embodiments all keep certain difference, and the light transmission coefficient k is larger than 0.9. In general, most of examples 1 to 24 can achieve the level of more than two excellent light blocking performance and light transmission performance, and are based on the excellent implementation effect of a flexible substrate with the thickness of 25 μm.
Examples 25 to 30
In the collimating film provided in embodiment 1, the collimating lens array and the collimating aperture array in the collimating film are both closely arranged in a regular triangle, the collimating lens layer 41 is made of PMMA, the flexible substrate layer 42 is made of PET, the light-shielding medium 43A of the collimating aperture layer 43 is inorganic plated titanium carbide, the collimating film is perforated with the collimating apertures 43B by using a microlens perforation method, and the other parameters are listed in table 2.
TABLE 2 design parameters and optical Properties of examples 25-30
As shown in Table 2, examples 25 to 30 are examples of different thicknesses of the flexible substrate. Examples 25 to 27 each represent a set of collimation films with P of 10 μm, 15 μm and 20 μm, and examples 28 to 30 each represent a set of collimation films with P of 25 μm, and with T of 25 μm, 38 μm and 50 μm, respectively, under the condition that the other parameters are not changed. When T is continuously increased, in order to maintain the micro-focusing effect (the focus is always located near the lower surface of the substrate and the light shielding layer and the light spot is minimized), the micro-lens structure obviously needs to be shallow, i.e. the R value is increased and H is lowered under the condition of fixing the P value and the refractive index collocation (compared with the difference of the embodiment in table 1, the focal length design is adapted along with the increase of T, so H does not need to be increased but is lowered). It can be found that, when other conditions are unchanged, the thickness T is increased, which is beneficial to the structure becoming shallow, the light spot D is reduced, the minimum light-blocking angle θ is reduced, the light-blocking performance is improved, and the light-transmitting coefficient is further improved. Therefore, in the range of thickness allowed (ultra-thin applications are more and more common, and too thick is not allowed), the performance improvement of the alignment film is helpful by using a relatively thick substrate, and the principle that the alignment film with a large length-diameter ratio has better performance (such as the principle shown in fig. 3) is met. In summary, in the present invention, T is selected from 10 to 50 μm, and more preferably 25 to 38 μm.
Examples 31 to 40
As in the collimating film provided in embodiment 1, the collimating lens array and the collimating aperture array of the collimating film are both arranged in a regular triangle, the collimating lens layer 41 is made of PMMA, the flexible substrate layer 42 is made of PET, the light-shielding medium 43A of the collimating aperture layer 43 is inorganic plated titanium carbide, the collimating film is perforated with the collimating apertures 43B by using a microlens perforation method, and the other parameters are listed in table 3.
TABLE 3 design parameters and optical Properties of examples 31-40
As shown in Table 3, it can be seen from the comparative examples 31 to 36 that the P value is increased and the R value is increased when other conditions are not changed, and if the original aspect ratio is maintained, the focal length is increased according to the similar principle, so that H is increased. Even if the focal length can be controlled, the spot radii D and θ cannot be prevented from increasing, and k is therefore decreased for the same aperture diameter. Therefore, in general, the larger P value is not favorable for the performance of the collimating film, which also conforms to the principle that the collimating film with a large length-diameter ratio has better performance (as shown in FIG. 3). In addition, in comparative examples 37 and 33, 38 and 34, 39 and 35, when the spot D is sufficiently small, the diameter of the hole Φ can be reduced by adjusting the laser energy, and is not necessarily limited to a fixed value, and it can be found that the light blocking performance can be further improved after the diameter of the hole is reduced, but the light transmission effect is reduced. Example 40 has a P value of 50 μm and a corresponding large R and H, and overall for the collimating film of the present invention, the microlens size has reached the upper design limit, including the fact that the spot diameter D is also large (D is particularly small, and particularly not good less than 0.5 μm, which tends to cause a single point energy too high to burn the substrate), resulting in an opening diameter phi of up to 8 μm, while the minimum light-blocking angle theta is also large at 12 degrees, and the light-blocking performance is not very good. In summary, in the present invention, P is selected from 10 to 50 μm, preferably 15 to 30 μm, and more preferably 18 to 25 μm. Phi is selected from 1 to 10 μm (10 μm from example 47), and more preferably 3 to 5 μm. D is selected from 0.1 to 7.8 μm, preferably 0.5 to 4.9 μm, and more preferably 1 to 2 μm.
Examples 41 to 47
As in the collimating film provided in embodiment 1, the collimating lens array and the collimating aperture array of the collimating film are both arranged in a regular triangle, the collimating lens layer 41 is made of PMMA, the flexible substrate layer 42 is made of PET, the light-shielding medium 43A of the collimating aperture layer 43 is inorganic plated titanium carbide, the collimating film is perforated with the collimating apertures 43B by using a microlens perforation method, and the other parameters are listed in table 4.
TABLE 4 design parameters and optical Properties of examples 41-47
As shown in Table 4, examples 41 to 47 are examples with different thicknesses t of the collimation holes. As can be seen from comparison of the first group of examples 41 to 44 and comparison of the second group of examples 45 to 47, when other conditions are not changed, increasing t contributes to improvement of light blocking performance, and t is too thin and is not a preferable value. Since laser drilling typically forms holes with smaller aspect ratios, the hole diameter tends to be larger than t, and thus when t is too thick, the hole diameter is actually too large (as in the second group of embodiments), which in turn gradually reduces the light blocking performance. In the present invention, t is selected from 0.5 to 7 μm, preferably 1 to 5 μm, and more preferably 2 to 3 μm.
Examples 48 to 57
The collimating film provided in embodiment 1, wherein the collimating lens array and the collimating hole array of the collimating film are both regularly triangular and closely arranged, the collimating lens layer 41 is made of PMMA, and further made of a photo-curable acrylic resin, the refractive index n1 is adjustable from 1.4 to 1.6, when n2 is 1.65, the flexible substrate layer 42 is made of PET, when n2 is 1.5, the flexible substrate layer 42 is made of COP, the light-shielding medium 43A of the collimating hole layer 43 is inorganic coated titanium carbide, the collimating film is perforated by microlenses to form collimating holes 43B, and the other parameters are listed in table 5.
TABLE 5 design parameters and optical Properties of examples 48-57
As shown in Table 5, examples 48-57 with different refractive index combinations are provided. As can be seen by comparing the first set of examples 48-52, under otherwise unchanged conditions: 1. increasing n1 (comparative examples 50, 48, 49 or comparative examples 51, 52) helps to reduce the flare D, lower θ and improve light blocking performance, with n1 being the best at 1.6 and n1 being the worst at 1.4; 2. the reduction in n2 (comparison of examples 51, 52 with examples 48, 49) was equally effective. The law of the influence of the refractive index remains the same in comparison with the second group of examples 53 to 57, but the influence is not so great because the second group has a shallow structure and the performance is originally excellent enough. For n1, the choice of molding material with too high or too low refractive index is narrower, while for n2, the physical properties of the flexible substrate itself and the light transmittance are considered more, and the refractive index is used only for the precise design of the structure. Therefore, n1 is selected from 1.4 to 1.6, preferably 1.5. n2 is selected from 1.5-1.65, which is not preferred according to the material difference.
Example 58
As in the collimating film provided in embodiment 48, the collimating lens array and the collimating aperture array of the collimating film are both arranged in a square shape (as shown in fig. 7), the collimating lens layer 41 is made of PMMA, the flexible substrate layer 42 is made of PET, the light-shielding medium 43A of the collimating aperture layer 43 is inorganic plated titanium carbide, the collimating film is perforated with the collimating apertures 43B by using a microlens perforation method, and the other parameters are listed in table 6.
TABLE 6 design parameters and optical Properties of examples 48, 58
As can be seen from table 6, when other parameters are not changed, the distribution of the microlenses is changed from regular triangles to squares, and a collimating film can still be obtained by the matching design of R, H. But the performance of the collimating film is slightly inferior to the regular triangular distribution. The main reason is that the squares are not dense like regular triangles in distribution, and the squares are larger in ratio between the diagonal lines and P, so that the spherical crowns arranged in the squares are more convex with the same P value, so that light spots are more scattered, D is larger, and theta is increased, the light blocking effect is poor, and the light transmittance is poor due to the fact that D is enlarged. Of course, square arrangement is not undesirable, and a smaller P value needs to be designed to achieve the same effect. The invention does not need to describe more square distribution embodiments, and the square distribution is always within the protection scope of the invention.
Examples 59 to 80
The collimating film provided in embodiments 53 to 57, wherein the collimating lens array and the collimating aperture array of the collimating film are both closely arranged in a regular triangle, the minimum pitch P of the main optical axes of the microlenses of the collimating lens layer is 20 μm, the radius of curvature R is 18.3 μm, the total thickness of the collimating lens layer is 4.1 μm, the thickness of the flexible substrate layer is 50 μm, the thickness of the collimating aperture layer is 2 μm, the diameter of the collimating aperture is 4 μm, the collimating film is formed by punching the microlenses to form the collimating apertures 43B, and the alignment errors Δ between the microlenses and the collimating apertures are less than 1 μm. The light blocking angles theta are all smaller than 5 degrees, the light blocking performance is excellent, the light transmission coefficients k are all larger 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 collimating hole layer shading medium are listed in table 7, the refractive index n1 of the collimating lens layer and the refractive index n2 of the flexible base layer are different according to the materials, and errors caused by different processes of +/-0.02 same materials are allowed, and are not listed in the table.
TABLE 7 design parameters and optical Properties of examples 59-80
Note 2: for the same material of the collimating lens layer, the molding method is not limited to photocuring, thermocuring, injection molding, hot pressing, etc.
As shown in Table 7, it is understood that the performance of the alignment film is not greatly affected by the same or close refractive index of the material before and after changing the material in comparative examples 59 to 80.
It should be noted that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention. All equivalent changes and modifications made according to the disclosure of the present invention are covered by the scope of the claims of the present invention.
Claims (10)
1. The collimating film is characterized by comprising a collimating lens layer, a flexible substrate layer and a collimating hole layer in sequence.
2. The collimating film of claim 1, wherein the collimating film comprises, in order, a collimating lens layer, a flexible substrate layer, and a collimating aperture layer.
3. The collimating film of claim 2, wherein the collimating lens layer comprises an array of microlenses and a thickness, and wherein the collimating aperture layer comprises an array of collimating apertures.
4. The collimating film of claim 3, wherein the collimating aperture layer comprises a light blocking dielectric layer and an array of collimating apertures.
5. The collimating film of claim 3, wherein the array of collimating holes is substantially coincident with the distribution of the array of microlenses.
6. The collimating film of claim 5, wherein each collimating hole is on a primary optical axis of the corresponding microlens; the micro-lens array of the collimating lens layer is orderly arranged.
7. The collimating film of claim 3, wherein the microlens array of the collimating lens layer and the collimating aperture array of the collimating aperture layer are both arranged in an ordered arrangement.
8. The collimating film of claim 3, wherein in the microlens array of the collimating lens layer, the coordinates of the principal optical axes of adjacent three microlenses are connected to form a regular triangle, or the coordinates of the principal optical axes of adjacent four microlenses are connected to form a square; the microlenses in the microlens array are closely arranged.
9. The collimating film of claim 3, wherein in the collimating lens layer, the pitch P of the principal optical axes of the adjacent microlenses is 10 to 50 μm, the radius R of the microlenses is 6.1 to 30.2 μm, the height H of the collimating lens layer is 1.1 to 27.4 μm, and the refractive index n1 of the collimating lens layer material is 1.34 to 1.7;
in the flexible substrate layer, the thickness T of the flexible substrate layer is 10-50 mu m, and the refractive index n2 of the flexible substrate layer material is 1.48-1.7;
in the collimation hole layer, the thickness t of the collimation hole layer is 0.5-7 μm, and the diameter phi of collimation holes in the collimation hole array is 1-10 μm.
10. The method of preparing a collimating film according to any of claims 1 to 9, wherein the collimating holes of the collimating film are perforated by a micro-focusing method; in the preparation method, laser is vertically irradiated on the collimating lens layer, the laser is focused through the micro lens of the collimating lens layer, and a light spot formed by focusing falls on the collimating lens layer to form a collimating hole.
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| PCT/CN2021/074161 WO2021169722A1 (en) | 2020-02-24 | 2021-01-28 | Collimation film and preparation method therefor |
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