CN113296279A - Alignment film, interference reduction alignment film and preparation method thereof, laminating alignment film and image recognition module - Google Patents

Abstract

The invention belongs to the field of image recognition, and particularly relates to a collimating film, an interference reducing collimating film and a preparation method thereof, a laminated collimating film and an image recognition module. The invention provides a collimating film, an interference reducing collimating film, a laminating collimating film, an image recognition module and a preparation method thereof, aiming at solving the problem that two layers of collimating diaphragms in a traditional rigid collimating sheet are difficult to align. The interference reduction collimation film sequentially comprises a collimation lens layer, a flexible substrate layer and a collimation hole layer; the collimating lens layer comprises a micro-lens array and a thickness; the collimating aperture layer comprises an array of collimating apertures; the micro-lens array of the collimating lens layer is arranged in disorder. The interference reduction collimation film provided by the invention can reduce the light interference phenomenon and improve the image identification accuracy. The image identification module provided by the invention has high identification accuracy, and can be applied to fingerprint unlocking and the like of consumer electronic products such as mobile phones (OLED screens).

Description

Alignment film, interference reduction alignment film and preparation method thereof, laminating alignment film and image recognition module

Technical Field

The invention belongs to the field of image recognition, and particularly relates to a collimating film, an interference reducing collimating film and a preparation method thereof, a laminated collimating film and an image recognition module.

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 (incident) and bottom (emergent) collimating structures needs to be increased, or the size of the microstructure 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, an interference reducing collimating film and a preparation method thereof, a laminating collimating film and an image recognition module, 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. Compared with the ordered collimating film, the interference reducing collimating film provided by the invention can reduce the light interference phenomenon and improve the image recognition accuracy.

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 foregoing collimating films are referred to as ordered collimating films (also known as ordered collimating structures). The foregoing ordered arrangement is characterized in that the pitch P of the principal optical axes of adjacent microlenses is a constant value.

The micro-lens array of the collimation lens layer and the collimation hole array of the collimation hole layer are arranged in sequence. The foregoing collimating films are referred to as ordered collimating films (also known as ordered collimating structures).

Further, the micro-lens array of the collimating lens layer is arranged in a disordered manner. The collimating film in which the microlens array is arranged in a disordered manner is called a subtractive interference collimating film (also called a disordered collimating structure, or a disordered array collimating film). The foregoing disordered arrangement is characterized in that the pitch P of the principal optical axes of adjacent microlenses is a value that varies within a range. Compared with the ordered collimating film, the interference reducing collimating film can reduce the phenomenon of light interference and improve the accuracy (recognition rate) of image recognition.

Further, the micro-lens array of the collimating lens layer and the collimating hole array of the collimating hole layer are arranged in disorder. The aforementioned collimating film is referred to as a subtractive interference collimating film (also referred to as a disordered collimating structure).

Further, in the interference reduction collimation film, in the microlens array of the collimation lens layer, the coordinates of the main optical axes of the three adjacent microlenses are connected to form a non-regular triangle. The non-regular triangle is also called a normal triangle, and refers to a triangle other than a triangle having three angles of 60 degrees.

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.

In the ordered collimating film, the pitches P of the main optical axes of the adjacent microlenses are the same, and P is selected from 10 to 50 μm, preferably 15 to 30 μm, and more preferably 18 to 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 a transparent polymer film.

Further, the material of the transparent polymer film 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 one or the combination of at least two of organic paint and inorganic plating.

The organic coating of the opacifying medium is selected from opaque polymeric ink systems.

Further, the opaque polymeric ink system comprises a light absorbing material and a polymeric 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 may be selected from one or a combination of at least two of acrylic systems (AR), polyurethane systems (PU), silicone Systems (SR), epoxy systems (EP), melamine resin systems (MF), phenolic resin systems (PF), urea resin systems (UF), or thermoplastic elastomeric materials (e.g. ethylene-vinyl acetate copolymers, thermoplastic elastomers TPE, or thermoplastic polyurethane elastomers 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 15 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 collimating aperture diameter φ may be 1-10 μm, such as 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 by using a microlens to form collimating apertures (43B), 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 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 preparation 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.

In addition, the orderly distributed collimating structure (which means that the microlens array of the collimating lens layer is orderly arranged) can meet the basic image recognition requirement in practical application, but there are interference fringes caused by too high regularity, as shown in fig. 11 a. Therefore, it is necessary to optimize the collimating structure to a disordered distribution, destroy regularity, and weaken interference fringes, as shown in fig. 11b, in order to further improve the image recognition accuracy (recognition rate).

The micro-lens array of the collimating lens layer of the interference-reducing collimating film provided by the invention is arranged in disorder, and the micro-focusing punching mode is adopted, so that the collimating hole array of the collimating hole layer is completely consistent with the micro-lens array, the characteristic of disorder distribution is kept, high-precision coaxial alignment is also maintained, and the traditional punching mode can not be realized all the time. The disordered microlens array collimating film can destroy the regularity of the ordered microlens array and weaken interference fringes caused by the regularity (as shown in fig. 11 b) so as to further improve the image recognition accuracy (recognition rate) of the collimating film provided by the invention.

The collimating lens array and the collimating hole array of the disordered array collimating film (interference reducing collimating film) are disordered arrays, and the microlenses are closely arranged and overlapped with each other (as shown in fig. 12, the coordinates of the main optical axes of any three mutually overlapped microlenses are connected into a common triangle (not a regular triangle)). In the interference reducing collimating film (disordered collimating film), the value range of P is 5-55 μm, the distance P between the principal optical axes of the two mutually overlapped microlenses changes in a disorder manner within a certain value range, the variation of the distance P between adjacent principal optical axes is A (the difference between the highest value and the lowest value in the value range of P), the median value of the distance P between adjacent principal optical axes is Pm (the average value of the highest value and the lowest value in the value range of P), and then Pm-0.5A is not less than P and not more than Pm + 0.5A; the median value Pm is selected from 10 to 50 μm, preferably 15 to 30 μm, and more preferably 18 to 25 μm, and the variation A of the main optical axis distance P is selected from 1 to 10um, preferably 2 to 6 um.

Furthermore, in the interference reducing collimation film (disordered collimation film), the radius R of the micro lens is 6.1-30.2 μm, the height H of the collimation lens layer is 1.1-27.4 μm, and the refractive index n1 of the collimation lens layer material is 1.34-1.7; 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.

In embodiments 81 to 86, the collimating lens array and the collimating aperture array in the collimating film are disordered arrays, and the microlenses are closely arranged and overlapped with each other (as shown in fig. 12, the coordinates of the principal optical axes of any three microlenses overlapped with each other are connected to form a common triangle (not a regular triangle), the distance P between the principal optical axes of the two microlenses overlapped with each other changes disorderly within a certain value range (Pm ± 0.5A), 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 coated titanium carbide, the collimating film punches the collimating aperture 43B in a microlens punching manner, and other parameters are as follows:

p is Pm plus or minus 0.5A, Pm is 30 μm, A is 1-10 μm, R is 20.6 μm, H is 27.4 μm, n1 is 1.5;

t is 25 μm, n2 is 1.65, D is 3.1 μm;

t is 2.0 μm and phi is 4.0 μm. Further, the deviation Δ was 0.81 μm.

Compared with the prior art, the interference reduction collimation film provided by the invention only comprises one collimation aperture layer, the problem that two collimation diaphragms are difficult to align with each other is fundamentally solved, the thickness is low, the toughness is good, the breakage is not easy, the center of a collimation hole prepared by adopting a micro-focusing method is positioned on the main optical axis of a corresponding micro lens, and the alignment between the collimation hole and the corresponding micro lens is accurate. The preparation method of the interference reduction collimation film provided by the invention is easy to operate, can realize mass production, and improves the production yield. The interference reduction collimation film provided by the invention has excellent performance, can filter diffused light by collimated light, and reduces the light interference phenomenon. The interference reduction collimation 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 interference reduction collimation film is applied to a fingerprint unlocking scheme of consumer electronic products such as mobile phones (OLED screens), the market demand is extremely high, and the pursuit for the characteristics such as ultrathin, large screens and flexibility is higher, so that the interference reduction collimation film has obvious advantages.

On the other hand, the invention provides a bonded collimation film, which comprises a bonded adhesive layer and the interference reduction collimation film; the adhesive layer is adhered to the collimation hole layer in the interference reduction collimation film.

Further, the adhesive layer is selected from one of a solid optical transparent adhesive, a high-transmittance pressure-sensitive adhesive or a transparent hot melt adhesive.

Furthermore, the thickness of the adhesive layer is 5-35 μm.

On the other hand, the invention also provides an image identification module which sequentially comprises a collimation layer, a filter layer and a photoelectric sensing layer; the collimation layer is selected from the laminated collimation film or the interference reduction collimation film.

Fig. 14 is a schematic diagram of a trend of screen enlargement of an image recognition module (taking an OLED mobile phone fingerprint recognition module as an example), which shows top views of four types of OLED mobile phones (01), where there is a fingerprint recognition module (03) below an OLED screen (02), and a finger (04) needs to be placed in these specific areas to be able to recognize and unlock: the fingerprint identification module is small, so that an icon is often displayed in the area when the screen is activated so as to indicate the accurate placement position of a finger; (b) the coverage area of the fingerprint identification module reaches about 1/4 screens, and the problem that the single-finger identification unlocking is expanded to the double-finger identification unlocking is solved; (c) and (d) the design is designed to realize half screen and even full screen, and higher requirements are provided for the large screen of the fingerprint identification module.

Fig. 15 is a schematic diagram of an image recognition module (taking an OLED mobile phone fingerprint recognition module as an example), in the complete fingerprint module, an interference reduction collimation film layer (05) is located at the middle layer, an OLED screen (02) is arranged above the collimation film, and an optical filter layer (06) and a photoelectric sensing layer (07) are arranged below the collimation film. When the collimating film is a soft base component, its dimensional stability (thermal shrinkage, thermal expansion, wrinkles, etc.) is a weak point, and therefore, in large-area use, it is necessary to bind with an underlying component, which may be a hard base component (e.g., a filter layer) or a soft base component (e.g., a filter layer may also be made of a soft base, and a photo-sensor chip may also be made of a TFT (thin film transistor), to increase the overall stiffness and thickness.

The laminated alignment film provided by the invention is provided with the laminating adhesive layer (44), and can be used for laminating the alignment film of a soft base (namely a flexible base layer) and a lower component of an image recognition module, so that the dimensional stability of the alignment film is improved, as shown in figure 16. Obviously, the flatness of the alignment film after lamination is higher, optical distortion caused by film material waves (wave) can be reduced, and the accuracy of image recognition is enhanced.

The laminated alignment film has four main structures from top to bottom, namely a disordered array alignment lens layer (41), a flexible substrate layer (42), an alignment hole layer (43) and an adhesive layer (44), as shown in fig. 17. Wherein, the design parameters of the disordered array collimating lens layer (41), the flexible base layer (42) and the collimating hole layer (43) are completely the same as those of the interference reducing collimating film, and the thickness of the bonding glue layer (44) is T₂And the thickness is selected from 5-50 μm, preferably 10-25 μm, too thin adhesive layer can cause poor adhesion (no matter before or after reliability), and too thick adhesive layer can cause signal light loss or crosstalk. As shown in fig. 18: (a) under normal conditions, if signal light is focused on the collimating aperture layer and then is scattered on the photoelectric sensor, light spots which are larger than the small apertures and smaller than the photoelectric sensor are generated, and the signal is completely received; (b) however, if the glue layer becomes thick, the distance of the photoelectric sensor becomes long and the light spot becomes large, the loss is generated; (c) when the glue layer is too thick, the distance between the photoelectric sensors is too far, the light spots are too large, and even the mutual crosstalk phenomenon of overlapping of adjacent light spots can be generated.

Further, the adhesive layer can be selected from solid OCA (optically clear adhesive), high-transmittance PSA (pressure sensitive adhesive) or transparent hot melt adhesive, and the like, and is preferably OCA and PSA with high light transmittance and reworkability. Furthermore, the materials of the OCA and the PSA are respectively selected from a thermosetting polyacrylate system or a light-curing polyacrylate system.

Further, in the laminated collimating film, the collimating lens array and the collimating hole array are disordered arrays, and the microlenses are closely arranged and overlapped with each other (as shown in fig. 12, the primary optical axis coordinates of any three mutually overlapped microlenses are connected into a common triangle (not a regular triangle), in the interference reducing collimating film (disordered collimating film), the value range of P is 5 to 55 μm, the distance P between the primary optical axes of the two mutually overlapped microlenses changes disorderly within a certain value range, the variation amount of the adjacent primary optical axis distance P is a (the difference between the highest value and the lowest value in the value range of P), the median value of the adjacent primary optical axis distance P is Pm (the average value of the highest value and the lowest value in the value range of P), Pm-0.5A is not more than P and not more than Pm +0.5A, the median value Pm is selected from 10 to 50 μm, preferably 15 to 30 μm, further preferably 18 to 25 μm, the variation A of the main optical axis distance P is selected from 1-10 um, preferably 2-6 um.

Furthermore, the radius R of the micro lens 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 1.34-1.7; 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.

The invention also provides a preparation method of the bonded collimating film, and the collimating holes 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 laminated collimating film prepared by the method, the distribution of the collimating hole array and the micro-lens array is completely consistent, and the circle center of any collimating hole is on the main optical axis of the corresponding micro-lens.

The invention also provides a preparation method of the laminated collimating film, which comprises the following steps:

(1) preparing a reduced interference collimation film;

(2) tearing the light release film from the OCA/PSA adhesive tape, and attaching the adhesive layer to the alignment hole layer.

Further, the preparation method comprises the following steps:

(1) preparing the interference reduction collimation film provided by the invention;

(2) tearing the light release film from the OCA/PSA adhesive tape, attaching the adhesive layer to the back surface (collimation hole layer) of the collimation film, and performing pressurization, temperature rise and vacuum pumping to perform air exhaust and bubble removal;

(3) before use, the heavy release film is torn off, so that the laminating type alignment film can be obtained, and the OCA/PSA glue layer is used for laminating the lower layer part.

In examples 93 to 102, the collimating lens array and the collimating aperture array in the collimating film are disordered arrays, and the microlenses are closely arranged and overlapped with each other (as shown in fig. 12, the coordinates of the principal optical axes of any three mutually overlapped microlenses are connected into a common triangle, the distance P between the principal optical axes of the two mutually overlapped microlenses varies disorderly within a certain range (Pm ± 0.5A), wherein the median Pm is 18 μm or 15 μm, the variation a is 4 μm, i.e., the range of P is 18 ± 2 μm or 15 ± 2 μm, and other parameters are listed in table 10, 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 by the microlenses to form collimating apertures 43B, and the other parameters are listed in table 10, the adhesive layer 44 of examples 93 to 99 is solid OCA, the material is a thermosetting polyacrylate system; the adhesive layer 44 of the embodiment 100 is a high-transmittance PSA made of a thermosetting polyacrylate system; the bonding adhesive layer 44 of the embodiment 101 is a solid OCA made of a photo-curable polyacrylate system; the adhesive layer 44 of example 102 is a high-transmittance PSA made of a photocurable polyacrylate system. The other parameters are as follows:

p is Pm plus or minus 0.5A, Pm is 18 μm, A is 4 μm, R is 14.8 μm, H is 16.3 μm, n1 is 1.5;

t is 25 μm, n2 is 1.65, D is 1.1 μm;

t is 2 μm and φ is 4 μm. Further, the deviation Δ was 0.41 μm.

Or P is Pm +/-0.5A, Pm is 15 μm, A is 4 μm, R is 17 μm, H is 2.4 μm, and n1 is 1.5;

t is 50 μm, n2 is 1.65, D is 0.5 μm;

t is 0.5 μm and φ is 5.0 μm. Further, the deviation Δ was 0.25 μm.

Compared with the prior art, the laminated 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 thickness is low, the toughness is good, the collimating film is not easy to break, the center of a collimating aperture prepared by adopting a micro-focusing method is on the main optical axis of a corresponding micro-lens, and the collimating aperture is accurately aligned with the corresponding micro-lens. The preparation method of the laminated collimating film provided by the invention is easy to operate, can be used for mass production, and improves the production yield. The laminated collimating film provided by the invention has excellent performance, can filter diffused light by collimated light, and reduces the light interference phenomenon. The laminated collimating film provided by the invention has the advantages that the laminated adhesive layer is arranged, the laminated collimating film can be laminated with a lower-layer component, the dimensional stability of the flexible collimating film is improved, and the optical distortion is reduced. The laminated 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 laminated collimating film is applied to a fingerprint unlocking scheme of consumer electronic products such as mobile phones (OLED screens), the laminated collimating film has obvious advantages due to great market demands and higher pursuit on the characteristics such as ultrathin, large screens and flexibility. The image identification module provided by the invention has high identification accuracy, and can be applied to fingerprint unlocking and the like of consumer electronic products such as mobile phones (OLED screens).

It should be noted that, in the collimating film of the present invention, the light-shielding medium of the collimating aperture layer has a light-shielding function, and can shield light, that is, the transmittance of light in a specific wavelength band is less than a certain value. In general, for optical sensor use, the transmittance of the light-shielding medium should be at least < 1%, i.e. the cut-off depth (cut-off level) OD 2. The light-shading medium adopts an opaque organic coating and an inorganic coating, and key substances contained in the medium are light-absorbing substances selected from carbon, carbide, carbonitride, sulfide and the like. In fact, the light-shielding medium of the present invention can also adopt a metal coating, and besides the above-mentioned opaque black light-absorbing substance, the metal coating can also realize the light-shielding function, and when the transmittance is less than 1%. The metal coating can be made very dense, with the same thickness, having advantages both in terms of cut-off depth (deeper, less transmission and less noise) and cut-off range (wavelength range cut off) (as shown in fig. 20 a).

In the image identification module, the photosensitive wave bands of different photoelectric sensors are different, light rays of corresponding wave bands are required to be blocked by the shading layer, otherwise, the light rays are received by the photoelectric sensors, and noise is generated. In a conventional photoelectric sensor, the photosensitive band of CMOS is 400-1100nm, and the photosensitive band of TFT is 400-850 nm. Therefore, the metal coating has certain advantages for the depth cut-off characteristic of the near infrared region, so that the metal coating is used in an image recognition module with a photoelectric sensor being a CMOS, and if a light absorbing substance is used as a light shielding layer (the light shielding medium of the collimation hole layer forms the light shielding layer), the thickness needs to be increased to compensate.

The shading medium adopts the metal coating and also has the following advantages: 1. compared with metal carbides, metals have lower general melting points (most metals have melting points less than 2000 ℃, but carbides are often higher than 3000 ℃, for example, titanium/zirconium has a melting point of 1675 ℃/1852 ℃, but titanium/zirconium carbide has a melting point of 3160 ℃/3540 ℃ respectively), and when the metal is subjected to laser drilling, the metal forms a circular boundary (a crater, as shown in 43B2 in fig. 22) of a molten recasting region (also called a recasting layer), so that the shape of the hole is better controlled, the roundness is higher (of course, the recasting region is not necessarily round, but does not influence light transmission), and special-shaped holes are not easy to generate; 2. the metal has ductility, the thin metal coating has certain flexibility, the problems of crack, pulverization and the like are not easy to generate in the punching process (the metal carbide is brittle and is easy to generate crack and pulverization), and the reliability is higher, as shown in a comparison graph 21.

It should be noted that fig. 20b also illustrates a disadvantage of the metal coating, i.e. the reflectivity is much higher than that of the black light absorbing material, which results in higher energy (much energy is reflected) for laser drilling, or the need to choose a suitable laser to drill with a band of the metal layer that absorbs more strongly, reducing the versatility of the device.

Furthermore, in the collimating film provided by the invention, the collimating film sequentially comprises a collimating lens layer, a flexible substrate layer and a collimating hole layer; the collimation hole layer comprises a shading dielectric layer (shading layer for short) and a collimation hole array.

The collimation hole layer comprises a shading medium and a collimation hole array formed after the shading medium is hollowed out.

The shading medium is a metal coating.

Further, the metal coating is selected from indium, tin, zinc, antimony, magnesium, aluminum, strontium, cerium, germanium, lanthanum, silver, gold, copper, manganese, gadolinium, nickel, cobalt, yttrium, iron, titanium, platinum, zirconium, chromium, hafnium, niobium, molybdenum which are suitable for magnetron sputtering.

Further, the metal plating layer is preferably tin, zinc, aluminum, germanium, silver, copper, manganese, nickel, cobalt, iron, titanium, chromium, niobium, molybdenum. The metal coating raw materials are more common and have low cost.

The coating mode of the light shielding medium is selected according to the type of the light shielding medium, and the metal coating layer is selected by a dry coating (such as physical vapor deposition) mode.

Furthermore, in the interference reduction collimation film provided by the invention, the shading medium is a metal coating.

Furthermore, in the laminated collimating film provided by the invention, the shading medium is a metal coating.

In example 103-109, the collimating lens array and the collimating aperture array in the collimating film are disordered arrays, and the microlenses are closely arranged and overlapped with each other (as shown in fig. 12, the coordinates of the principal optical axes of any three mutually overlapped microlenses are connected into a common triangle, the distance P between the principal optical axes of the two mutually overlapped microlenses varies disorderly within a certain range (Pm ± 0.5A), wherein the median Pm is 18 μm, the variation a is 4 μm, i.e., the range of P is 18 ± 2 μm, and other parameters are listed in table 11, 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 a metal plating layer, the collimating film is formed by punching the microlenses to form the collimating apertures 43b, the bonding adhesive layers 44 of examples 103-109 are solid OCAs, the material is a thermosetting polyacrylate system, the metal plating layers of examples 103-109 are respectively made of aluminum, Germanium, silver, copper, nickel, titanium, chromium. The light-shielding medium of example 93 has good cutoff performance for visible light, and among the near-infrared cutoff performance, the light-shielding media of examples 103 to 109 have excellent cutoff performance for visible light and good cutoff performance for near-infrared.

After the light-shielding medium in the technical scheme provided by the invention adopts the metal coating, the light-shielding performance and the light-transmitting performance of the collimating film are basically not influenced. But the light ray cutting-off performance is better, especially the cutting-off depth of infrared light can reach the OD2 level, and meanwhile, the roundness of the collimating hole is higher, and the reliability of the light shielding layer is higher.

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 is a process of testing light blocking performance (minimum light blocking angle) of the collimating film provided by the present invention;

FIG. 11a shows interference fringes produced by an ordered collimating structure;

FIG. 11b shows interference fringes produced by a disordered collimating structure;

FIG. 12 is a top view of a collimating lens layer in a disordered distribution (to illustrate the meaning of the disordered distribution);

FIG. 13 is a schematic perspective view of an interference reducing collimating film provided by the present invention (the microlens array is in disordered distribution);

FIG. 14 is a diagram illustrating a trend of a large screen of an image recognition module (taking an OLED mobile phone fingerprint recognition module as an example);

FIG. 15 is a schematic diagram of an image recognition module (taking an OLED mobile phone fingerprint recognition module as an example);

FIG. 16 is a schematic view of a bonded alignment film bonded to a lower member (taking an OLED mobile phone fingerprint recognition module as an example);

FIG. 17 is a four layer basic structure of a conformable collimating film;

FIG. 18 shows the effect of the thickness of the adhesive layer on the signal reception of the photosensor;

FIG. 19 is a schematic view of a structure of a bonded collimating film;

FIG. 20a is a graph showing the transmittance comparison between a black light-absorbing material (43A1) and a metal plating layer (43A 2);

FIG. 20b is a graph showing the comparison of the reflectance of the black light-absorbing material (43A1) and the metal plating layer (43A 2);

FIG. 21 is a comparison of the effect of micro-focused punching of black light absorbing material (43B1) and micro-focused punching of metal plating (43B 2);

FIG. 22 shows a crater pattern (001 as a plan view and 002 as a cross-sectional view) formed by laser drilling of a metal plating layer.

Wherein:

1: target image, 11-17: 7 continuous pixel points of the target image; 2: collimator, 21: top (entrance) collimating structure layer, 22: a bottom (light-emitting) collimating structure layer; 3: photoelectric sensing chip, 31 ~ 37: 7 photoelectric sensors corresponding to the continuous pixel points; 4: the collimating film provided by the invention, 4': comparative example provided collimating film, 40: central axis of collimating structure (microlens principal axis), 41: collimating lens layer, 41A: microlens array, 41B: thickness of meat, 41C: microlens apex, 42: flexible substrate layer, 43: collimation aperture layer, 43A: light-shielding medium, 43B: a collimating aperture; 5: flat-top beam laser; 6: inspecting the light source; 7: gaussian beam laser; o: laser positioning origin; 01: OLED cell phone, 02: OLED screen, 03: fingerprint identification module, 04: finger, 05: interference reducing collimation film layer, 06: infrared filter layer, 07: photoelectric sensing layer (including photoelectric sensing chip, flexible circuit board and reinforcement base plate), 44: adhesive layer, 43a 1: black light-absorbing substance, 43a 2: metal plating, 43B 1: micro-focused perforation of black light absorbing species, 43B 2: micro-focusing drilling of the metal coating.

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 Δ_n，Δ_n-1<Δ_n(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 is the maximum (obtained by testing a standard sample under the high-precision condition of an optical simulation or a laser head, generally about 90 percent); 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).

(C) Spectral characteristics

In the design and optimization of the collimating film, specific spectral property requirements are put on important components, including Transmittance (abbreviated as T%) and Reflectance (abbreviated as R%) for specific wavelength bands (generally divided into visible and near-infrared bands). The evaluation of the spectral characteristics is detected by using an ultraviolet-visible light-near infrared spectrophotometer, and equipment of models such as Cary5000/7000 of Agilent company can meet the requirements.

Regarding the shading medium, the meaning of T% is the light ray cut-off performance, the invention divides the cut-off performance into 3 grades according to T%, and the corresponding relation is as follows: excellent: t% < 0.01%, excellent: t% < 0.1%, good: t% < 1%, medium: t% < 10%, difference: t% is more than or equal to 10%; i.e., OD4, OD3, OD2, OD1, and no cutoff, respectively.

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

Note 1 is as in Table 1.

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

Note 1 is as in Table 1.

As shown in Table 3, it can be seen from the comparative examples 31 to 36 that the R value becomes large when the P value is increased without changing other conditions, and the focal length becomes far and H becomes large according to the similar principle if the original aspect ratio is maintained. 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

Note 1 is as in Table 1.

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

Note 1 is as in Table 1.

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

Note 1 is as in Table 1.

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 1 is as in Table 1.

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.

Examples 81 to 86

A collimating film as provided in example 24, having a cross-section as shown in fig. 6 and a perspective view as shown in fig. 13. The collimating lens array and the collimating hole array in the collimating film are disordered arrays, and the microlenses are closely arranged and overlapped with each other (as shown in fig. 12, the primary optical axis coordinates of any three mutually overlapped microlenses are connected into a common triangle (not a regular triangle), the distance P between the primary optical axes of the two mutually overlapped microlenses changes in a disordered way within a certain value range (Pm +/-0.5A), wherein the median Pm and the variation a are listed in table 8, 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 coating titanium carbide, the collimating film punches the collimating hole 43B by adopting a microlens punching mode, and other parameters are listed in table 8.

TABLE 8 design parameters and optical Properties of examples 24 and examples 81-86

Note 1: p is the distance between the main optical axes of the two mutually overlapped micro lenses, and the value range of P is Pm +/-0.5A and the unit of mum; pm is the average value of the maximum value and the minimum value in the value range of P, called the median, A is the difference between the maximum value and the minimum value in the value range of P, called the variation, unit mum; r is the curvature radius of the micro lens and the unit is mum; h is the thickness (or called height) 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 for measuring the alignment accuracy of the collimating holes and the microlenses

Note 2: the collimating lens array and the collimating aperture array of example 24 are both in regular triangular close arrangement; the collimating lens arrays and the collimating hole arrays of embodiments 81-86 are disordered arrays and closely arranged;

as can be seen from table 8, when the other parameters were not changed, the alignment film changed from a fixed P value to a P value that varied randomly, and the performance was not substantially affected. The A value is a variable selected from 1 to 10 μm, preferably 2 to 6 μm. When a is too small, the interference reduction effect is not significant, and when a is too large, the array morphology becomes poorly controlled, reproducibility is poor, and there are many light leakage regions that occur due to too far a distance.

Examples 87 to 92

A collimating film as provided in example 4 has a cross-section as shown in fig. 6 and a perspective view as shown in fig. 13. The collimating lens array and the collimating hole array in the collimating film are disordered arrays, and the microlenses are closely arranged and overlapped with each other (as shown in fig. 12, the primary optical axis coordinates of any three mutually overlapped microlenses are connected into a common triangle (not a regular triangle), the distance P between the primary optical axes of the two mutually overlapped microlenses changes in a disordered way within a certain value range (Pm ± 0.5A), wherein the median Pm and the variation a are listed in table 9, 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 coating titanium carbide, the collimating film punches the collimating hole 43B by adopting a microlens punching mode, and other parameters are listed in table 9.

TABLE 9 design parameters and optical Properties of examples 4 and 87-92

Note 1 is as in Table 8;

note 2: the collimating lens array and the collimating aperture array of embodiment 4 are both in regular triangle close arrangement; the collimating lens array and the collimating aperture array of embodiments 87-92 are both disordered arrays and closely arranged;

as can be seen from Table 9, when the other parameters were not changed, the P value of the collimating film changed from a constant P value of 18 μm to a disordered P value (in the narrowest range of 17.5 to 18.5 μm, and in the widest range of 13 to 23 μm), and the performance was not substantially affected. The A value is a variable selected from 1 to 10 μm, preferably 2 to 6 μm. When a is too small, the interference reduction effect is not significant, and when a is too large, the array morphology becomes poorly controlled, reproducibility is poor, and there are many light leakage regions that occur due to too far a distance.

Examples 93 to 102

The cross-sectional view of the collimating films provided in examples 93-102 is shown in FIG. 19. The collimating film is characterized in that a collimating lens array and a collimating hole array are disordered arrays, and microlenses are closely arranged and overlapped with each other (as shown in fig. 12, the primary optical axis coordinates of any three mutually overlapped microlenses are connected into a common triangle, the distance P between the primary optical axes of the two mutually overlapped microlenses changes in a disordered way within a certain value range (Pm +/-0.5A), wherein the median Pm is 18 mu m or 15 mu m, the variation A is 4 mu m, namely the value range of P is 18 +/-2 mu m or 15 +/-2 mu m, other parameters are listed in table 10, the collimating lens layer 41 is made of PMMA, the flexible substrate layer 42 is made of PET, the shading medium 43A of the collimating hole layer 43 is inorganic plating titanium carbide, the collimating film adopts a microlens punching mode to punch out collimating holes 43B, the other parameters are listed in table 10, the bonding glue layer 44 of the embodiment 93-99 is solid OCA, the material is a thermosetting polyacrylate system; the adhesive layer 44 of the embodiment 100 is a high-transmittance PSA made of a thermosetting polyacrylate system; the bonding adhesive layer 44 of the embodiment 101 is a solid OCA made of a photo-curable polyacrylate system; the adhesive layer 44 of example 102 is a high-transmittance PSA made of a photocurable polyacrylate system.

TABLE 10 design parameters and optical Properties of examples 93-102

Note 1 is as in Table 8;

note 2: the collimating lens array and the collimating hole array of embodiments 93-102 are disordered arrays and closely arranged;

note 3: t is₂The thickness of the adhesive layer is in unit of μm;

as can be seen from the examples 93-98 in Table 10, when the parameters of the three-layer core structure (41, 42, 43) of the interference reduction collimation film are not changed, the thickness of the adhesive layer (44) does not affect the optical collimation performance (light blocking performance and light transmission performance). But a thickness T₂Too little can result in poor adhesion (whether before or after reliability), and too much can still result in loss of signal light or crosstalk. In particular, when the thickness T is₂When the value of (A) is increased to a certain critical value, a collimating film with a shallower microlens structure and a larger length-diameter ratio is needed, as in example 98 and the implementationExample 99, a 50 μm thick flexible substrate layer (which would be problematic if a 25 μm thick layer were still used) and 2.4 μm H were used. It can be seen from comparison of examples 97, 100 and 102 that the material of the bonding glue layer (44) does not affect the optical alignment performance when the parameters of the three-layer core structure (41, 42, 43) of the interference reduction alignment film are not changed.

It should be understood that, in any of the ordered alignment films of the present invention, the P value can be changed to a certain degree to obtain a new disordered alignment film, and therefore, the Pm value in the disordered alignment film and the P value in the ordered alignment film are both selected from 10 to 50 μm, preferably 15 to 30 μm, and further preferably 18 to 25 μm. The invention only uses the embodiment 24 to carry out disorder optimization, and does not need to list more embodiments for further description, but the patent scope of the disorder collimating film provided by the invention is not influenced.

Example 103-109

A collimating film as provided in example 93, having a cross-section as shown in figure 19. The collimating film includes a collimating lens array and a collimating aperture array, which are disordered arrays, and microlenses are closely arranged and overlapped with each other (as shown in fig. 12, the primary optical axis coordinates of any three microlenses overlapped with each other are connected to form a common triangle, the distance P between the primary optical axes of the two microlenses overlapped with each other is disordered and varies within a certain value range (Pm ± 0.5A), wherein the median Pm is 18 μm, the variation a is 4 μm, i.e., the value range of P is 18 ± 2 μm, other parameters are listed in table 11, 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 a metal plating layer, the collimating film is provided with collimating apertures 43b formed by perforating the microlenses, the bonding glue layers 44 of examples 103-109 are solid OCA, the materials are thermosetting polyacrylate systems, and the metal plating layers of examples 103-109 are respectively aluminum, and aluminum, and aluminum, respectively, and copper, respectively, and copper, and aluminum, and copper, respectively, and copper, respectively, and copper, and, Germanium, silver, copper, nickel, titanium, chromium. The light-shielding medium of example 93 has good cutoff performance for visible light, and among the near-infrared cutoff performance, the light-shielding media of examples 103 to 109 have excellent cutoff performance for visible light and good cutoff performance for near-infrared.

TABLE 11 design parameters and optical Properties of examples 93, 103-109

Note 1 is as in Table 8;

note 2: the collimating lens array and the collimating hole array of embodiments 93, 103-109 are disordered arrays and closely arranged;

note 3: t is₂The thickness of the adhesive layer is in unit of μm;

as can be seen from comparison between example 93 and examples 103 to 109 in Table 11, the light blocking property and the light transmittance of the alignment film are not substantially affected after the light blocking medium is changed to the metal plating layer. However, in the embodiments 103 to 109, the light-blocking performance is better, especially the infrared light-blocking depth can reach the level of OD2, and the roundness of the collimating holes is higher, so that the light-shielding layer is not easily broken and has higher reliability.

It should be understood that in any of the above embodiments (1 to 102) of the present invention, the light-shielding medium may be implemented by using a metal plating layer, and further description is not repeated in the present invention, which does not affect the patent scope of the collimating film provided by the present invention.

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 (11)

1. The collimating film is characterized by comprising a collimating lens layer, a flexible substrate layer and a collimating hole layer in sequence; the collimation hole layer comprises a shading medium layer and a collimation hole array.

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; the collimating lens layer includes a microlens array and a thickness.

3. The collimating film of claim 2, wherein the light-shielding medium of the collimating aperture layer is one of an organic paint, an inorganic plating, or a combination of at least two thereof; the collimating hole array and the micro-lens array are completely distributed in the same way, each collimating hole is arranged on the main optical axis of the corresponding micro-lens, and the micro-lens arrays of the collimating lens layer are arranged in order.

4. The collimating film of claim 1, wherein the light-blocking medium of the collimating aperture layer is a metal plating; the distribution of the collimation hole array is completely consistent with that of the micro-lens array, and each collimation hole is arranged on the main optical axis of the corresponding micro-lens.

5. A subtractive interference collimating film selected from the collimating films of claims 1, 2 or 4 wherein the microlens array of the collimating lens layer is in a disordered arrangement.

6. The subtractive interference collimating film according to claim 5, wherein the microlenses in the microlens array are closely spaced.

7. The interference reduction collimation film of claim 5, wherein coordinates of primary optical axes of three adjacent microlenses in the microlens array of the collimation lens layer are connected to form a non-regular triangle.

8. The interference reduction collimation film as claimed in claim 5, wherein in the collimation lens layer, the pitch P of the main optical axes of the adjacent microlenses is 5-55 μm, the variation of the pitch P of the main optical axes of the adjacent microlenses is A, the median value of the pitch P of the main optical axes is Pm, and then Pm-0.5A is not less than P is not less than Pm + 0.5A; the Pm is 10-50 mu m, and the variation A of the main optical axis distance P is 1-10 mu m; the radius R of the micro lens 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 1.34-1.7;

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.

9. A conformable collimating film, comprising a layer of conformable adhesive and the interference reducing collimating film of any of claims 5-8; the adhesive layer is adhered to the collimation hole layer in the interference reduction collimation film.

10. An image recognition module is characterized by comprising a collimation layer, a filter layer and a photoelectric sensing layer in sequence; the collimating layer is selected from the conformable collimating film of claim 9 or the subtractive interference collimating film of any of claims 5-8.

11. The method for preparing the interference reduction collimation film as claimed in any one of claims 5 to 8, wherein the collimation holes of the collimation film are punched 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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