阅读说明：本技术 一种柔性全息基元膜及其制备方法和应用 (Flexible holographic base element film and preparation method and application thereof ) 是由 王广军 余为伟 于 2019-11-29 设计创作，主要内容包括：本发明涉及3D显示领域,公开了一种柔性全息基元膜,基元膜整体为柔性可弯曲薄膜结构,由若干单面镀有反射膜的柔性透明薄膜或是若干双面均镀有反射膜的柔性透明薄膜通过透明胶水粘接形成的反射层与透明层相间排列的结构,反射膜形成反射层,用于反射光线,柔性的透明薄膜和/或透明胶水形成透明层,用于透射光线,柔性全息基元膜的水平夹持下垂长度L(cm)与可对折次数n之间满足：n*L>9或L≥5cm,本发明所述制备方法的材料成本以及加工工艺成本都较低,适合大范围推广,同时应用本发明所述的柔性全息基元膜制备的3D显示全息膜,可以做成卷轴式屏幕、曲面屏幕等,灵活度较高,不使用时方便收纳,占用空间较小。(The invention relates to the field of 3D display, and discloses a flexible holographic base film, wherein the whole base film is of a flexible bendable thin film structure, a plurality of flexible transparent thin films with single surfaces plated with reflecting films or a structure that a plurality of flexible transparent thin films with double surfaces plated with reflecting films are adhered through transparent glue to form reflecting layers and transparent layers which are arranged alternately, the reflecting layers form reflecting layers for reflecting light rays, the flexible transparent thin films and/or the transparent glue form the transparent layers for transmitting light rays, and the horizontal clamping sag length L (cm) of the flexible holographic base film and the folding times n meet the following requirements: n L is greater than 9 or L is larger than or equal to 5cm, the material cost and the processing process cost of the preparation method are low, the preparation method is suitable for large-scale popularization, and meanwhile, the 3D display holographic film prepared by applying the flexible holographic element film can be made into a scroll screen, a curved screen and the like, the flexibility is high, the 3D display holographic film is convenient to store when not used, and the occupied space is small.)

1. A flexible holographic base film, comprising: the whole base element film (1) is of a flexible and bendable film structure, and is of a structure that a plurality of flexible transparent films with reflecting films plated on single surfaces or a plurality of flexible transparent films with reflecting films plated on double surfaces are adhered through transparent glue to form reflecting layers (2) and transparent layers (3) which are arranged alternately and in parallel;

the reflecting film forms a reflecting layer (2) for reflecting light;

the flexible transparent film and/or transparent glue forming a transparent layer (3) for transmitting light;

the horizontal clamping sagging length L (cm) of the flexible holographic element film and the folding times n meet the following conditions: n is L is greater than 9 or L is not less than 5.

2. A flexible holographic element film according to claim 1, wherein: the thickness of the reflecting layer (2) is 0.1-25 mu m, the thickness of the transparent layer (3) is 2-1 mm, and the thickness of the transparent layer (3) is larger than that of the reflecting layer (2).

3. A flexible holographic element film according to claim 1, wherein: the transparent film is any one of a plastic film, a PMMA film, an lPMMA film, a PS film, a PC film, a styrene acrylonitrile film, an MS film, a PET film, a PETG film, an ABS film, a PP film, a PA film, an SAN film, an MS film, an MBS film, a PES film, a CR-39 film, a TPX film, a HEMA film, an F4 film, an F3 film, an EFP film, a PVF film, a PVDF film, an EP film, a PF film, an UP film, a cellulose acetate film, a cellulose nitrate film, an EVA film, a PE film, a PVC film, an amorphous cycloolefin film and a modified bisphenol A epoxy resin film which are made of transparent materials.

4. A flexible holographic base film according to claim 4, wherein: the reflecting film is any one of aluminum foil, iron foil, tin foil, zinc foil, copper foil, chromium foil, nickel foil and titanium foil.

5. A flexible holographic element film according to claim 1, wherein: the transparent glue is any one of transparent epoxy resin AB glue, UV glue, shadowless glue, transparent glass glue, transparent wood glue and transparent all-purpose glue.

6. The method of claim 1, comprising the steps of:

1) preparing a cured pile:

a) stacking a plurality of transparent thin films plated with reflecting films which are cut in advance layer by layer,

forming a reflective film stack in which a reflective layer and a transparent layer are alternately arranged;

b) soaking the whole reflecting film stack in transparent glue water until the transparent glue water completely permeates into gaps among layers of the reflecting film stack, and taking out the reflecting film stack;

c) standing and curing, wherein in the curing process, a certain pressure is applied to extrude out the redundant glue among the transparent films so as to control the thickness of the reflecting film stack, and a curing stack with alternately arranged reflecting layers (2) and transparent layers (3) is formed after curing;

2) preparing a basic element film: grinding a smooth surface in the direction vertical to the plane of the reflecting layer (2) to be recorded as a cutting reference surface, cutting a sheet from the solidified pile along the direction parallel to the cutting reference surface to be recorded as a substrate film (1), wherein the newly cut surface on the solidified pile is the cutting reference surface of the next cutting, repeating the cutting step, and cutting the solidified pile of the step 1) into a plurality of substrate films (1).

7. The method of claim 6, wherein the method comprises: the cured mass described in step 1) can also be prepared by:

the transparent film plated with the reflecting film is placed on a plane, transparent glue is uniformly coated on the upper surface of the transparent film, then another transparent film plated with the reflecting film is stacked on the transparent glue layer, the stacking process is repeated to form a structure in which the reflecting film and the transparent film are stacked alternately, and a solidified stack is formed after standing and solidifying.

8. The method of claim 6, wherein the method comprises: the curing stack can be prepared by adding at least one transmission film between two transparent films plated with reflection films, wherein the transmission film is any one of a plastic film, a PMMA film, an lPMMA film, a PS film, a PC film, a styrene acrylonitrile film, an MS film, a PET film, a PETG film, an ABS film, a PP film, a PA film, an SAN film, an MS film, an MBS film, a PES film, a CR-39 film, a TPX film, a HEMA film, an F4 film, an F3 film, an EFP film, a PVF film, a PVDF film, an EP film, a PF film, an UP film, a cellulose acetate film, a cellulose nitrate film, an EVA film, a PE film, a PVC film, an amorphous cycloolefin film and a modified bisphenol A epoxy resin film.

9. The method of claim 6, wherein the method comprises: before the cutting in the step 2), a transparent protective film is bonded on the cutting reference surface by using transparent glue, or a transparent protective film is bonded on one surface or two surfaces of the element film (1) after the cutting is finished, and the element film (1) with the transparent protective film is obtained after the cutting, wherein the transparent protective film is any one of transparent glass, acrylic, plastic film, PMMA film, lPMMA film, PS film, PC film, styrene acrylonitrile film, MS film, PET film, PETG film, ABS film, PP film, PA film, SAN film, MS film, MBS film, PES film, CR-39 film, TPX film, HEMA film, F4 film, F3 film, EFP film, PVF film, PVDF film, EP film, PF film, UP film, cellulose acetate film, cellulose nitrate film, EVA film, PE film, PVC film, amorphous cycloolefin film and modified bisphenol A epoxy film.

10. Use of a flexible holographic base film prepared by a method of preparing a flexible holographic base film according to any of claims 6 to 9, wherein: the flexible holographic base film (1) is applied to preparing a flexible 3D display holographic film, and specifically comprises the following steps:

two flexible substrate films (1) are bonded together up and down by using transparent glue, a flexible 3D display holographic film is formed after curing, the reflecting layer (2) and the transparent layer (3) on the two substrate films (1) are staggered by an included angle theta to form a grid (4) during bonding, the theta is more than or equal to 87 degrees and less than or equal to 93 degrees, and the horizontal clamping sagging length L (cm) of the flexible 3D display holographic film and the folding times n meet the following requirements: n L >9 or L is more than or equal to 5, and the element film (1) is provided with a flexible transparent protective film or is not provided with the transparent protective film.

11. Use of a base film with a transparent protective film according to claim 9, wherein: the application of the base element film (1) with the transparent protective film in the preparation of the hard 3D display holographic projection screen specifically comprises the following steps:

one substrate film (1) with a hard transparent protective film and the other substrate film (1) with or without the transparent protective film are bonded together up and down by using transparent glue, and the reflecting layer (2) and the transparent layer (3) on the two substrate films (1) are staggered at an included angle theta to form a grid (4), wherein the theta is more than or equal to 87 degrees and less than or equal to 93 degrees.

Technical Field

The invention relates to the field of 3D display, in particular to a flexible holographic base film and a preparation method and application thereof.

Background

The 3D display technology is capable of displaying stereoscopic pictures in space, and is the mainstream direction of the next generation display technology. Although there are many solutions for realizing 3D display, such as volume display technology, stereo image pair technology, pepper's ear illusion, etc., there is no perfect 3D solution at present, and the main reason is the lack of optical glass element for large area light source manipulation.

The traditional optical glass processing technology can only process microstructures in a hundred-micron scale, high-precision large-area optical processing needs and high processing cost, and the optical glass is made of hard materials and is easy to break and generate residual stress in the processing process.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: aiming at the problems that the processing cost of the traditional high-precision large-area optical glass is high in the prior art, and the yield is affected by the easy breakage of the glass, the residual stress and the like in the processing process, the flexible holographic base film and the preparation method and application thereof are provided.

In order to solve the technical problems, the invention provides a flexible holographic element film, wherein the whole element film is of a flexible and bendable thin film structure, and the flexible holographic element film is of a structure in which a plurality of flexible transparent thin films with single surfaces plated with reflecting films or a plurality of flexible transparent thin films with double surfaces plated with reflecting films are adhered through transparent glue to form reflecting layers and transparent layers which are arranged alternately;

the reflecting film forms a reflecting layer for reflecting light;

the flexible transparent film and/or the transparent glue form a transparent layer for transmitting light;

the horizontal clamping sagging length L (cm) of the flexible holographic element film and the folding times n meet the following conditions: n is L is greater than 9 or L is not less than 5.

Furthermore, the thickness of the reflecting layer is 0.1-25 μm, the thickness of the transparent layer is 2-1 mm, and the thickness of the transparent layer is greater than that of the reflecting layer.

Further, the transparent film is any one of a plastic film, a PMMA film, an lPMMA film, a PS film, a PC film, a styrene acrylonitrile film, an MS film, a PET film, a PETG film, an ABS film, a PP film, a PA film, a SAN film, an MS film, an MBS film, a PES film, a CR-39 film, a TPX film, a HEMA film, an F4 film, an F3 film, an EFP film, a PVF film, a PVDF film, an EP film, a PF film, an UP film, a cellulose acetate film, a cellulose nitrate film, an EVA film, a PE film, a PVC film, a novel amorphous thermoplastic polyester film, an amorphous cycloolefin film, and a modified bisphenol a epoxy resin film.

Further, the reflective film is any one of aluminum foil, iron foil, tin foil, zinc foil, copper foil, chromium foil, nickel foil and titanium foil.

Further, the transparent glue is any one of transparent epoxy resin AB glue, UV glue, shadowless glue, transparent glass glue, transparent wood glue and transparent all-purpose glue.

The invention also provides a preparation method of the flexible holographic base element film, which comprises the following steps:

1) preparing a cured pile:

a) stacking a plurality of transparent thin films plated with reflecting films which are cut in advance layer by layer to form a reflecting film stack with alternately arranged reflecting layers and transparent layers;

b) soaking the whole reflecting film stack in transparent glue until the transparent glue completely penetrates into the gap between the transparent film and the reflecting film, and taking out;

c) standing and curing, wherein in the curing process, a certain pressure is applied to extrude out the redundant glue among the transparent films so as to control the thickness of the transparent layer, and a curing stack with the reflecting layer and the transparent layer arranged alternately is formed after curing;

2) preparing a basic element film: grinding a smooth surface in the direction vertical to the plane of the reflecting layer, recording the smooth surface as a cutting reference surface, cutting a sheet from the solidified pile along the direction parallel to the cutting reference surface, recording the sheet as a base element film, wherein the newly cut surface on the solidified pile is the cutting reference surface for the next cutting, and repeating the cutting step to cut the solidified pile in the step 1) into a plurality of base element films.

Further, the cured pile described in step 1) may also be prepared by:

the transparent film plated with the reflecting film is placed on a plane, transparent glue is uniformly coated on the upper surface of the transparent film, then another transparent film plated with the reflecting film is stacked on the transparent glue layer, the stacking process is repeated to form a structure in which the reflecting film and the transparent film are stacked alternately, and a solidified stack is formed after standing and solidifying.

Furthermore, at least one transmission film can be added between two transparent films plated with reflection films during preparation of the cured stack, and the transmission film is any one of a plastic film, a PMMA film, an lPMMA film, a PS film, a PC film, a styrene acrylonitrile film, an MS film, a PET film, a PETG film, an ABS film, a PP film, a PA film, a SAN film, an MS film, an MBS film, a PES film, a CR-39 film, a TPX film, a HEMA film, a F4 film, a F3 film, an EFP film, a PVF film, a PVDF film, an EP film, a PF film, a UP film, a cellulose acetate film, a cellulose nitrate film, an EVA film, a PE film, a PVC film, a novel amorphous thermoplastic polyester film, an amorphous cycloolefin film and a modified bisphenol A epoxy resin film.

Further, before the cutting in the step 2), a transparent protective film is adhered on the cutting reference surface by using transparent glue, or bonding a transparent protective film on one or two surfaces of the element film after cutting to obtain the element film with the transparent protective film after cutting, the transparent protective film is any one of a plastic film, a PMMA film, an lPMMA film, a PS film, a PC film, a styrene acrylonitrile film, an MS film, a PET film, a PETG film, an ABS film, a PP film, a PA film, an SAN film, an MS film, an MBS film, a PES film, a CR-39 film, a TPX film, a HEMA film, an F4 film, an F3 film, an EFP film, a PVF film, a PVDF film, an EP film, a PF film, an UP film, a cellulose acetate film, a cellulose nitrate film, an EVA film, a PE film, a PVC film, a novel amorphous thermoplastic polyester film, an amorphous cycloolefin film and a modified bisphenol A epoxy resin film.

The invention also provides an application of the flexible holographic element film prepared by the preparation method of the flexible holographic element film, and the flexible holographic element film is applied to preparing a flexible 3D display holographic film, and specifically comprises the following steps:

the two flexible element films are bonded together up and down by using transparent glue, a flexible 3D display holographic film is formed after curing, the reflecting layers and the transparent layers on the two element films are staggered at an included angle theta to form a grid when bonding, the theta is more than or equal to 87 degrees and less than or equal to 93 degrees, and the horizontal clamping sagging length L (cm) of the flexible 3D display holographic film and the number n of folding times meet the following requirements: n L is greater than 9 or L is greater than or equal to 5cm, and the element film is provided with a flexible transparent protective film or is not provided with the transparent protective film.

The invention also provides an application of the elementary film with the transparent protective film, which is used for preparing the hard 3D display holographic projection screen and specifically comprises the following steps:

one element film with a hard transparent protective film (such as glass or acrylic) and the other element film with or without the transparent protective film are bonded together up and down by using transparent glue, and the reflecting layers and the transparent layers on the two element films are staggered at an included angle theta to form a grid, wherein the theta is more than or equal to 87 degrees and less than or equal to 93 degrees.

Compared with the prior art, the invention has the advantages that:

compared with the extremely high processing cost of the existing high-precision optical glass processing technology, the preparation method has lower material cost and processing technology cost, and is suitable for large-scale popularization; meanwhile, the holographic element film with the grids is flexible, so that the holographic element film is not easy to break when being processed, the problems of residual stress generated in the glass processing process and the like are avoided, the yield is greatly improved, the holographic element film can be made into a scroll screen, a curved screen and the like when being specifically applied, the flexibility is higher, the holographic element film is convenient to store when not being used, and the occupied space is smaller.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a front view showing the structure of a substrate film 1 formed by bonding a double-sided coated transparent film by transparent glue,

FIG. 2 is a front view showing the structure of a substrate film 1 formed by bonding a single-sided coated transparent film by transparent glue,

figure 3 is an enlarged view of a portion of i in figure 2,

FIG. 4 is a structural view of a base film 1 with a transparent protective film

Figure 5 is a perspective view of a 3D display holographic film structure,

figure 6 is a front view and a top view of figure 5,

figure 7 is a diagram of an aero-levitation display system,

figure 8 is an imaging schematic of a 3D display holographic film,

figure 9 is a side view of figure 8,

figure 10 is a schematic diagram of the partial internal ray reflection at ii in figure 9,

figure 11 is a diagram of the effect of a flexible holographic screen for an air suspension display system application,

FIG. 12 is a graph showing the simulation effect of the imaging light path of the holographic film in 3D,

the reference numbers are as follows:

a base film 1, a reflective layer 2, a transparent layer 3, a grid 4, a holographic projector 10, a projection screen 20, an interactive response unit 30, a processor 40, and a motion actuator 50.

Detailed Description

The following detailed description of the present invention is given for the purpose of better understanding technical solutions of the present invention by those skilled in the art, and the present description is only exemplary and explanatory and should not be construed as limiting the scope of the present invention in any way.

Referring to fig. 1 to 12, the present invention provides a flexible holographic base film, which is a flexible and bendable film structure, and has a horizontal clamping and sagging length of l (cm), and a folding number of n, satisfying: l is more than or equal to 5 or n L is more than 9;

in practical application, in order to ensure the reliability as much as possible, n is preferably more than or equal to 2 and L is more than 9;

it should be noted that, where n is the number of times of folding, testThe area of the sample is 100cm²The square flexible holographic base film 1 is characterized in that the base film 1 is folded into a rectangle along the middle line position of the square (or within 1cm near the middle line position), then the folded base film 1 is clamped between two flat plates, 10-20N of force is applied to pressurize for 3-5 s, then the base film 1 is opened (at the moment, a folding test is completed once), whether the base film 1 generates local micro-cracks or is broken into two parts along creases is checked, if not, the test is repeated until the base film 1 generates local micro-cracks or is broken into two parts, the test is stopped, and the total folding times in the test process are recorded as N;

wherein L is the horizontal clamping sagging length, the test method comprises the following steps: taking a narrow strip element film 1 with the width of 5cm +/-0.5 cm and the length of about 25cm, enabling one end of the narrow strip element film to be tightly attached to a horizontal reference table top, ensuring that the length of the narrow strip extending out of the table top is 20cm +/-1 cm, standing, and measuring the vertical height difference between the end point of the narrow strip extending out of the table top and the horizontal reference table top after the narrow strip is stabilized to be recorded as a horizontal droop length L;

the test is an accelerated test means, the reliability of a sample in a long-term use process can be rapidly judged, the flexible 3D display base element film 1 needs to bear operations such as winding, storage, opening and the like for many times when being applied, the operation is calculated according to the designed 5-year service life, the whole life cycle needs to be stored and unfolded for about 10000 times, and in order to accelerate the evaluation of the service life of the base element film 1, the folding test and the horizontal clamping droop length test are adopted in the invention;

when n is greater than L9, the larger n is, the smaller the ultimate bending curvature radius of the base element film 1 is, the stronger the breaking resistance is, and meanwhile, the larger L is, the better the flexibility of the base element film 1 is, the more difficult the base element film 1 structure is to be damaged due to winding, experiments show that the base element film 1 structure is basically equivalent to 10000 times of opening and closing tests when n is greater than L9, the requirement on the minimum design life is met, and if the n is smaller, the quality problem is easy to occur in the service cycle of a product, and the customer experience is reduced;

in practical application, some transparent adhesive tapes and transparent films which are relatively hard after being cured can be used, so that the prepared flexible holographic base film 1 can be broken when being folded in half, but the structure can not be damaged when being wound, and the flexible holographic base film is also suitable for winding screens. For such materials, as long as the prepared base membrane 1 can be wound into a cylinder with the diameter less than 5cm, when L is more than 5cm, the whole base membrane 1 is relatively flexible, and the fracture loss in the processing process is small.

As shown in fig. 1 to fig. 3, the reflective film may be formed by bonding a plurality of flexible transparent films with one surfaces plated with reflective films through transparent glue, or may be formed by bonding a plurality of flexible transparent films with two surfaces plated with reflective films through transparent glue;

the reflecting film forms a reflecting layer 2 for reflecting light, the reflecting film is a metal foil capable of reflecting light or other films with interfaces having the function of reflecting light, it should be noted that if the reflecting film is too thick, too much light can be shielded, the thinner the reflecting film is, but in consideration of the process preparation difficulty and cost, the thickness of the reflecting film is 0.1-25 μm of aluminum foil, iron foil, tin foil, zinc foil, copper foil, chromium foil, nickel foil, titanium foil or other reflecting films capable of reflecting light;

the transparent layer 3 is formed by flexible transparent film and/or transparent glue and used for transmitting light, the thickness of the transparent layer 3 is always larger than that of the reflecting layer 2, and the thickness of the transparent layer is preferably 2 mu m-1 mm;

when a flexible transparent film with a reflecting film plated on one side is adopted, the single-layer transparent layer 3 is formed by the flexible transparent film and transparent glue after being cured; when a flexible transparent film with reflecting films plated on both sides is adopted, the transparent layer 3 is formed by alternately curing layers of the transparent film and transparent glue, wherein the transparent glue can be any one of transparent epoxy resin AB glue, UV glue, shadowless glue, transparent glass glue, transparent wood glue and transparent universal glue;

the transparent film may be any one of a plastic film, a PMMA film, an lPMMA film, a PS film, a PC film, a PE film, a styrene acrylonitrile film, an MS film, a PET film, a PETG film, an ABS film, a PP film, a PA film, a SAN film, an MS film, an MBS film, a PEs film, a CR-39 film, a TPX film, a HEMA film, an F4 film, an F3 film, an EFP film, a PVF film, a PVDF film, an EP film, a PF film, an UP film, a cellulose acetate film, a cellulose nitrate film, an EVA film, a PE film, a PVC film, a novel amorphous thermoplastic polyester film, an amorphous cycloolefin film, and a modified bisphenol a epoxy resin film.

The invention also provides a preparation method of the flexible holographic base element film, which comprises the following specific steps:

1) preparing a cured pile:

a) stacking a plurality of transparent thin films plated with reflecting films which are cut in advance layer by layer to form a reflecting film stack with alternately arranged reflecting layers and transparent layers;

b) the whole reflecting film stack is soaked in transparent glue, and is taken out until the transparent glue completely permeates into gaps between the transparent films, and it is required to be noted that the transparent films are piled up to form a fluffy stack, gaps exist between the layers, so that the transparent glue can penetrate into the layers under the action of surface tension when contacting with the transparent glue and is completely filled, bubbles are not easy to appear, and the glue has a bonding effect on various materials, so that the transparent films and the reflecting film are very easy to infiltrate, and the transparent films and the reflecting film can be filled between the transparent films and the reflecting film under the action of the surface tension, and the capillary phenomenon is similar;

c) standing and curing, wherein in the curing process, a certain pressure is applied to extrude out redundant glue among the transparent films so as to control the thickness of the transparent layer, a curing stack with alternately arranged reflecting layers 2 and transparent layers 3 is formed after curing, wherein the reflecting layers form the reflecting layers 2, and the transparent films and/or the transparent glue curing layers form the transparent layer 3;

2) preparing a basic element film: grinding a smooth surface in the direction vertical to the plane of the reflecting layer 2, marking the smooth surface as a cutting reference surface, cutting a sheet from the solidified pile along the direction parallel to the cutting reference surface, marking the sheet as a base element film 1, wherein the newly cut surface on the solidified pile is the cutting reference surface of the next cutting, and repeating the cutting step to cut the solidified pile in the step 1) into a plurality of base element films 1.

Wherein, the preparation of the curing stack in the step 1) can also adopt the following mode:

the transparent film plated with the reflecting film is placed on a plane, transparent glue is uniformly coated on the upper surface of the transparent film, then another transparent film plated with the reflecting film is stacked on the transparent glue layer, the stacking process is repeated to form a structure in which the reflecting film and the transparent film are stacked alternately, and a solidified stack is formed after standing and solidifying.

It should be noted that the transparent layer 3 is formed by curing a flexible transparent film and/or transparent glue, and based on the materials of the transparent glue and the transparent film, the cured transparent layer 3 has better flexibility, so that the cut element film 1 also has better flexibility.

In order to reduce the amount of transparent glue and further increase the thickness of the transparent layer 3, at least one transparent film of transparent plastic material may be adhered between the two reflective layers 2 by transparent glue during actual preparation.

Reference may be made in particular to the thicknesses of the reflective layer 2, the transparent layer 3 and the elementary film 1 in the following table:

thickness of reflecting layer (mum)	Thickness of transparent layer (μm)	Elementary film thickness (μm)
			0.1	1	1
1	2	2
			5	10	10
10	20	20
			15	30	30
20	50	50
			25	100	100
25	300	300
			25	1000	1000

The following examples are further provided to illustrate the preparation method of a flexible holographic base film according to the present invention, wherein the reflective layer 2 is a 10 μm aluminum foil reflective film, the transparent layer 3 is 20 μm, the transparent film is a PE film, and the transparent glue is an epoxy AB glue to prepare a flexible 3D display holographic film with a thickness of 20 μm: