A high contrast polymer dispersed liquid crystal reflective display device

Abstract

The present invention belongs to the field of display technology, and discloses a high-contrast polymer dispersed liquid crystal reflective display device, comprising: a PDLC film, a backplane, and an air spacer layer between the PDLC film and the backplane; the PDLC film comprises: a first substrate; a second substrate, arranged opposite to the first substrate; a first electrode layer, arranged inside the first substrate, close to the second substrate; a second electrode layer, arranged inside the second substrate, close to the first electrode layer and arranged opposite to the first electrode layer; a polymer dispersed liquid crystal layer, arranged between the first electrode layer and the second electrode layer. The present invention is used to solve the problem of low contrast of existing PDLC display devices, can effectively improve light efficiency, reduce energy consumption, and achieve a good reflective display effect. In addition, the present invention can also use a flexible substrate for large-area production to achieve flexible display.

Description

Technical Field

[0001] The invention belongs to the field of display technology, and in particular relates to a high-contrast polymer dispersed liquid crystal reflective display device. Background Art

[0002] After decades of development, liquid crystal display technology has entered people's lives in various forms, such as electronic watches, mobile phones, televisions, monitors, car-mounted central control screens, and so on. Usually, liquid crystal display devices need to use polarizers, orientation layers and other film layers to combine the optical anisotropy of liquid crystal molecules to achieve light regulation. However, these film layers are often accompanied by a decrease in light energy utilization, and it is difficult to achieve flexibility. At present, the cost of polarizers in liquid crystal display devices has accounted for nearly half of the cost of display modules. How to achieve liquid crystal display without polarizers is a major task in the current display field.

[0003] As a light control technology, polymer dispersed liquid crystal (PDLC) has received more and more attention and has been widely used in various fields. PDLC does not require polarizers and liquid crystal orientation layers when used in display devices, which greatly improves the utilization rate of light energy and can effectively reduce costs. PDLC is a thin film formed by mixing liquid crystal molecules with small molecule polymerizable monomers, initiating monomer polymerization under certain conditions, and forming liquid crystals into micron-sized droplets dispersed in a polymer matrix through phase separation. Since the liquid crystal still retains its original optical anisotropy and dielectric anisotropy, it can respond to an external electric field to achieve different control states of light. The preparation of PDLC only requires coating-curing, which greatly simplifies the production process and reduces costs. In addition to glass substrates, flexible substrates can also be used to achieve large-scale processing in a Roll-to-Roll manner, so it has great advantages in the field of flexible displays. However, the current mainstream PDLC display has a low contrast ratio, usually around 3 to 5, and the display effect is poor, which greatly limits its application. Summary of the invention

[0004] The purpose of the present invention is to provide a high-contrast polymer dispersed liquid crystal reflective display device, which has a higher contrast ratio than the traditional PDLC display, can effectively improve the light efficiency and reduce energy consumption.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A high contrast polymer dispersed liquid crystal reflective display device comprises: a PDLC film, a back plate, and an air spacing layer between the PDLC film and the back plate.

[0007] As a limitation, the PDLC film comprises:

[0008] a first substrate;

[0009] A second substrate, arranged opposite to the first substrate;

[0010] A first electrode layer is disposed inside the first substrate and close to the second substrate;

[0011] A second electrode layer is disposed on the inner side of the second substrate, close to the first electrode layer and opposite to the first electrode layer;

[0012] The polymer dispersed liquid crystal layer is arranged between the first electrode layer and the second electrode layer.

[0013] As a second limitation, a plurality of first sub-electrodes arranged in a matrix are provided on the first electrode layer, a plurality of second sub-electrodes arranged in a matrix are provided on the second electrode layer, the first sub-electrodes are each provided with a gate line and a data line connected thereto, and the second sub-electrodes are also each provided with a gate line and a data line connected thereto;

[0014] Alternatively, the first electrode layer is provided with a plurality of first sub-electrodes arranged in a matrix, each of which is provided with gate lines and data lines connected thereto; the second electrode layer is a common electrode, and the first sub-electrodes and the common electrode generate a vertical electric field to drive the polymer dispersed liquid crystal layer.

[0015] As a third limitation, a plurality of pixel units formed by crossing gate lines and data lines are arranged on the first electrode layer, each pixel unit includes a first sub-electrode and a TFT unit, and the TFT unit is connected to the corresponding first sub-electrode;

[0016] The second electrode is a common electrode, and the first sub-electrode and the common electrode generate a vertical electric field to drive the polymer dispersed liquid crystal layer.

[0017] As a fourth limitation, a plurality of pixel units formed by crossing gate lines and data lines are arranged on the first electrode layer, each pixel unit includes a first sub-electrode and a TFT unit, and the TFT unit is connected to the corresponding first sub-electrode;

[0018] A plurality of pixel units formed by crossing gate lines and data lines are arranged on the second electrode layer, each pixel unit includes a second sub-electrode and a TFT unit, and the TFT unit is connected to the corresponding second sub-electrode;

[0019] The first sub-electrode and the second sub-electrode generate a vertical electric field to drive the polymer dispersed liquid crystal layer.

[0020] As a fifth limitation, the materials of the first electrode layer and the second electrode layer are both indium tin oxide, indium zinc oxide, graphene or silver nanowires.

[0021] As a sixth limitation, the polymer dispersed liquid crystal layer includes a polymer matrix and liquid crystal;

[0022] The polymer matrix is ​​formed by polymerizing a polymerizable monomer, and the polymerizable monomer is one or more of acrylates, methacrylates, thiols, epoxies or polyurethanes;

[0023] The liquid crystal is a nematic liquid crystal, a smectic liquid crystal or a cholesteric liquid crystal.

[0024] As a seventh limitation, the first substrate and the second substrate are glass substrates, plastic substrates or flexible substrates.

[0025] As an eighth limitation, the back panel is a black or colored back panel.

[0026] As a ninth limitation, at least one layer of thin film material is provided in the air spacing layer;

[0027] The film material is a prism film or an optical resin.

[0028] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with the prior art:

[0029] (1) The present invention can be used to reduce unnecessary reflection and enhance light emission by providing an air gap layer and a thin film material in the air gap layer, thereby improving contrast;

[0030] (2) The polymer dispersed liquid crystal layer used in the present invention has a higher contrast and a faster response speed than the traditional PDLC, which further promotes the realization and application of PDLC film and polymer dispersed liquid crystal reflective display devices;

[0031] (3) The present invention has a high contrast ratio, can effectively improve light efficiency, reduce energy consumption, and achieve a good reflective display effect;

[0032] (4) The present invention has a simple structure, does not require a polarizer or an alignment layer, and can achieve high-efficiency, low-cost display;

[0033] (5) The first substrate and the second substrate of the present invention can be glass substrates, plastic substrates or flexible substrates. Flexible substrates such as PET, PI, etc. can be applied to flexible displays.

[0034] The invention belongs to the field of display technology and is used to solve the problem of low contrast of existing PDLC display devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the structure of the PDLC film in Example 1 of the present invention;

[0036] Figure 2 is a flow chart for preparing a polymer dispersed liquid crystal layer according to Example 1 of the present invention;

[0037] Figure 3 is a transmittance-voltage curve of the polymer dispersed liquid crystal layer of Example 1 of the present invention;

[0038] Figure 4 It is a schematic diagram of a vertical cross-sectional structure of method 1 in embodiment 2 of the present invention;

[0039] Figure 5 It is a schematic diagram of the vertical cross-sectional structure of the second method in the second embodiment of the present invention;

[0040] Figure 6 It is a schematic diagram of the vertical cross-sectional structure of the third method in the second embodiment of the present invention;

[0041] Figure 7 It is a schematic diagram of the vertical cross-sectional structure of the fourth method in the second embodiment of the present invention;

[0042] Figure 8 It is a schematic diagram of the vertical cross-sectional structure of the fifth method in the second embodiment of the present invention;

[0043] Fig. 9 It is a schematic diagram of the vertical cross-sectional structure of the sixth embodiment of the second embodiment of the present invention;

[0044] Fig.10 The contrast enhancement diagrams of the methods 1 to 6 in the second embodiment of the present invention are shown;

[0045] Fig.11 This is a physical diagram of the on and off states of method six in embodiment 2 of the present invention.

[0046] Among them, 1. PDLC film; 101. first substrate; 102. first electrode layer; 103. polymer dispersed liquid crystal layer; 104. second electrode layer; 105. second substrate; 2. air spacer layer; 201. low refractive index optical resin; 202. high refractive index optical resin; 203. prism film; 3. back panel. DETAILED DESCRIPTION

[0047] The present invention is further described below in conjunction with embodiments, but those skilled in the art should understand that the present invention is not limited to the following embodiments, and any improvements and changes made based on the specific embodiments of the present invention are within the scope of protection of the claims of the present invention.

[0048] Example 1 A PDLC film

[0049] like Figure 1As shown, in this embodiment, the PDLC film 1 includes: a first substrate 101; a second substrate 105, which is arranged opposite to the first substrate 101; a first electrode layer 102, which is arranged inside the first substrate 101 and close to the second substrate 105; a second electrode layer 104, which is arranged inside the second substrate 105, close to the first electrode layer 102 and opposite to the first electrode layer 102; and a polymer dispersed liquid crystal layer 103, which is arranged between the first electrode layer 102 and the second electrode layer 104. In this embodiment, the first substrate 101 and the second substrate 105 are glass substrates; the materials of the first electrode layer 102 and the second electrode layer 104 are both indium tin oxide. In practical applications, the first substrate 101 and the second substrate 105 can also be plastic substrates or flexible substrates; the materials of the first electrode layer 102 and the second electrode layer 104 can also be indium tin oxide, indium zinc oxide, graphene or silver nanowires.

[0050] In this embodiment, when passive matrix driving is adopted, the first electrode layer 102 and the second electrode layer 104 are both matrix pixel electrodes, a plurality of first sub-electrodes arranged in a matrix are arranged on the first electrode layer 102, a plurality of second sub-electrodes arranged in a matrix are arranged on the second electrode layer 104, the first sub-electrodes are provided with gate lines and data lines connected thereto, and the second sub-electrodes are also provided with gate lines and data lines connected thereto. One end of the gate line and the data line are connected to the first sub-electrode and the second sub-electrode, and the other end is connected to the driving circuit. The gate line and the data line are connected to the driving circuit, and different voltage signals are applied to the first electrode layer 102 and the second electrode layer 104 respectively so that the polymer dispersed liquid crystal layer 103 is driven to achieve a display effect.

[0051] Alternatively, when passive matrix driving is adopted, a plurality of first sub-electrodes arranged in a matrix are provided on the first electrode layer 102, and the first sub-electrodes are provided with gate lines and data lines connected thereto; the second electrode layer 104 is a common electrode, and by applying voltage to the first sub-electrodes and the common electrode, the first sub-electrodes and the common electrode generate a vertical electric field to drive the polymer dispersed liquid crystal layer.

[0052] When active matrix driving is adopted, a plurality of pixel units formed by the intersection of gate lines and data lines are arranged on the first electrode layer 102, each pixel unit includes a first sub-electrode and a TFT unit, and the TFT unit is connected to the corresponding first sub-electrode; wherein the first sub-electrode can be set as a block electrode of the size of a pixel, or can be set as a plurality of strip electrodes, and the TFT unit and the first sub-electrode can be made by a general LCD forming method. The second electrode is set as a common electrode, and by applying a voltage to the first sub-electrode and the common electrode, the first sub-electrode and the common electrode generate a vertical electric field to drive the polymer dispersed liquid crystal layer 103.

[0053] Another structure when active matrix driving is adopted is: a plurality of pixel units consisting of crossing gate lines and data lines are arranged on the first electrode layer 102, each pixel unit includes a first sub-electrode and a TFT unit, and the TFT unit is connected to the corresponding first sub-electrode; a plurality of pixel units consisting of crossing gate lines and data lines are also arranged on the second electrode layer 104, each pixel unit includes a second sub-electrode and a TFT unit, and the TFT unit is connected to the corresponding second sub-electrode, and by applying voltage to the first sub-electrode and the second sub-electrode, the first sub-electrode and the second sub-electrode generate a vertical electric field to drive the polymer dispersed liquid crystal layer 103.

[0054] In this embodiment, the polymer dispersed liquid crystal layer 103 includes a polymer matrix and liquid crystal; the polymer matrix is ​​formed by polymerizing a polymerizable monomer, and the polymerizable monomer is one or more of acrylates, methacrylates, thiols, epoxies or polyurethanes; the liquid crystal is a nematic liquid crystal, a smectic liquid crystal or a cholesteric liquid crystal.

[0055] During preparation, the polymer dispersed liquid crystal layer 103 is formed by curing a slurry of a polymerizable monomer, liquid crystal and a photoinitiator uniformly through ultraviolet irradiation. The preparation process is as follows: Figure 2 As shown. The specific process route is: purify the polymerizable monomer and liquid crystal raw materials respectively, then weigh them according to the formula ratio, mix them and add the photoinitiator, stir them evenly, place the mixed slurry between two ITO substrates to form the required thickness, and use ultraviolet light irradiation to cure under certain temperature conditions (0-25°C) to obtain a polymer dispersed liquid crystal layer 103. The mass percentages of polymerizable monomer, liquid crystal and photoinitiator used in the polymer dispersed liquid crystal layer 103 are (10-70)%: (90-30)%: (0.5-5)%. By adjusting the ratio of different components, a polymer dispersed liquid crystal layer 103 with different properties can be obtained.

[0056] like Figure 3 The transmittance T-voltage V curve of the polymer dispersed liquid crystal layer 103D2, O2, and C4 obtained after adjusting the ratio of different components in this embodiment is shown. The test of the curve shown in the figure adopts a passive drive direct power-on test, and does not involve circuit and drive optimization. The light regulation state of the polymer dispersed liquid crystal layer 103 can be controlled by voltage, and can switch between light transmission and light scattering, and can also achieve an intermediate grayscale state, that is, the transmittance can be adjusted by changing the voltage.

[0057] in, Figure 3The polymerizable monomers in the polymer dispersed liquid crystal layer 103D2, O2, and C4 are all methacrylates, and the liquid crystal is a nematic phase liquid crystal, which is cured by ultraviolet light at 25°C. The mass percentage of the polymerizable monomer, liquid crystal, and photoinitiator in D2 is 30:67:3; the mass percentage of the polymerizable monomer, liquid crystal, and photoinitiator in O2 is 35:62:3; and the mass percentage of the polymerizable monomer, liquid crystal, and photoinitiator in C4 is 40:57:3.

[0058] like Figure 3 As shown, after testing, the on-state transmittance Ton of the polymer dispersed liquid crystal layer 103D2 can reach 84.7%, the off-state transmittance Toff can reach 4.5%, the contrast CR can reach 18, and the on-state response time ton is about 1ms, and the off-state response time is about toff = 27.5ms. The on-state transmittance Ton of the polymer dispersed liquid crystal layer 103O2 is about 84.6%, the off-state transmittance Toff can be reduced to 2.5%, and the contrast CR can reach 35. The on-state response time ton is about 1ms, and the off-state response time is about toff = 35.8ms. The on-state transmittance Ton of the polymer dispersed liquid crystal layer 103C4 is about 80.7%, the off-state transmittance Toff is about 5.0%, and the contrast CR can reach 16. The on-state response time ton is about 0.6ms, and the off-state response time is about toff = 41.3ms. Figure 3 It can be seen that the properties of the polymer dispersed liquid crystal layer 103D2, O2, and C4 are superior to those of the traditional PDLC, and can be optimized and customized by adjusting the materials.

[0059] The polymer dispersed liquid crystal layer 103 in this embodiment is transparent when powered and is in a scattered state when not powered. By changing the preparation process, it can be realized that it is in a scattered state when powered and in a transparent state when not powered. In addition, by doping dyes into the polymer dispersed liquid crystal layer 103, black and white or other color display can be realized.

[0060] Example 2 A high contrast polymer dispersed liquid crystal reflective display device

[0061] This embodiment includes a PDLC film 1, a backplane 3, and an air spacer layer 2 between the PDLC film 1 and the backplane 3. The PDLC film 1 adopts the PDLC film 1 in Embodiment 1, and the first electrode layer 102 and the second electrode layer 104 in the PDLC film 1 are both set as matrix pixel electrodes, that is, a plurality of first sub-electrodes arranged in a matrix are set on the first electrode layer 102, and a plurality of second sub-electrodes arranged in a matrix are set on the second electrode layer 104, and a passive matrix drive is adopted; the polymer dispersed liquid crystal layer 103 adopts a polymer dispersed liquid crystal layer 103O2; the backplane 3 is a black backplane 3; the PDLC film 1 and the backplane 3 are not in direct contact, but are provided with an air spacer layer 2, which can increase the display contrast. In actual application, the backplane 3 can also adopt a colored backplane 3.

[0062] In this embodiment, the air spacer layer 2 may be provided with at least one layer of film material; the film material may be a prism film 203 or an optical resin; when at least two layers of optical resin are provided in the air spacer layer 2, optical resins with different refractive indices may be used. The film material may also be other films with specially designed shapes and patterns.

[0063] In this embodiment, different high contrast polymer dispersed liquid crystal reflective display devices are designed by using air spacer layers 2 with different structures, which are recorded as Mode 1 to Mode 6. Figures 4 to 9 The vertical cross-sectional schematic diagrams of high contrast polymer dispersed liquid crystal reflective display devices of Modes 1 to 6 are shown.

[0064] in, Figure 4 An air gap layer 2 is directly provided between the PDLC film 1 and the back plate 3; the air gap in the air gap layer 2 can be set to 1 mm; in practice, it can also be set to 1 um to 1 mm;

[0065] Figure 5 A layer of low-refractive-index optical resin 201 is disposed in the air spacer layer 2, and its refractive index n=1.32;

[0066] Figure 6 A layer of high refractive index optical resin 202 is arranged in the air spacer layer 2, and its refractive index n=1.665;

[0067] Figure 7 A prism film 203 is disposed in the air spacer layer 2, and the prism surface of the prism film 203 faces the direction of the first substrate 101;

[0068] Figure 8 A prism film 203 is disposed in the air spacer layer, and the prism surface of the prism film 203 faces the direction of the back plate 3 and away from the direction of the first substrate 101;

[0069] Fig. 9Two layers of prism films 203 are arranged in the air spacer 2, and the prism surface of the prism film 203 faces the direction of the back plate 3 and away from the direction of the first substrate 101; the prism directions of the two layers of prism films 203 have a certain angle θ, θ = 90°, and the prism film 203 is superimposed as follows Fig. 9 Partial enlargement shown.

[0070] Optical tests were conducted on the above-mentioned methods 1 to 6. When no external voltage was applied, i.e., in the off state, the polymer dispersed liquid crystal layer 103 was in a light scattering state, and the high-contrast polymer dispersed liquid crystal reflective display device was white; when voltage was applied, i.e., in the on state, the polymer dispersed liquid crystal layer 103 was in a transparent state, and the high-contrast polymer dispersed liquid crystal reflective display device displayed the color of the backplane 3. The reflectivity Toff and Ton in the two states were tested respectively, and the display contrast CR of the device was calculated by the formula CR=Toff / Ton.

[0071] Taking the contrast CR1 of mode 1 as the reference, the contrasts of modes 2 to 6 are compared with it to obtain the contrast enhancement values ​​CRx / CR1 under other modes, such as Fig.10 As shown. Fig.10 It can be seen that adding a thin film material in the air gap layer 2 is beneficial to improving the contrast. Among various settings, the prism film 203 has the best effect, because the prism film 203 can gather large-angle light to the normal direction of the film surface, increasing the bright light intensity in the normal direction. Compared with the single-layer prism film 203, the double-layer superimposed prism film 203 can act on light in more directions, so it has a better effect. Compared with the method of only setting an air gap layer 2, the contrast is improved by five times.

[0072] like Fig.11 As shown, it is a physical diagram of the open state and the closed state of the sixth embodiment of the present invention. Fig.11 Taken under indoor brightness, the image shows that the polymer dispersed liquid crystal reflective display device of mode six has a good contrast.

[0073] In this embodiment, the PDLC film 1 only controls the amount of light passing through, and the ambient light is white light, so the polymer dispersed liquid crystal reflective display device is a black and white display. Further, by doping a color dye in the polymer dispersed liquid crystal layer 103, or replacing the backplane 3 with a color backplane 3, other color displays can be achieved.

[0074] It should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high contrast polymer dispersed liquid crystal reflective display device, characterized in that: The high contrast polymer dispersed liquid crystal reflective display device comprises: a PDLC film, a back plate, and an air spacer layer between the PDLC film and the back plate; The PDLC film comprises: a first substrate; A second substrate, arranged opposite to the first substrate; A first electrode layer is disposed inside the first substrate and close to the second substrate; A second electrode layer is disposed on the inner side of the second substrate, close to the first electrode layer and opposite to the first electrode layer; A polymer dispersed liquid crystal layer is disposed between the first electrode layer and the second electrode layer; The polymer dispersed liquid crystal layer comprises a polymer matrix and liquid crystal; The polymer matrix is ​​formed by polymerizing polymerizable monomers, and the polymerizable monomers are one or more of acrylates, methacrylates, thiols, epoxies or polyurethanes; The liquid crystal is a nematic liquid crystal, a smectic liquid crystal or a cholesteric liquid crystal; During preparation, the polymer dispersed liquid crystal layer is formed by curing a slurry of a polymerizable monomer, liquid crystal and photoinitiator uniformly mixed by ultraviolet irradiation. The specific process is: purify the polymerizable monomer and liquid crystal separately, then weigh them according to the formula ratio, mix and add the photoinitiator, stir evenly, place the mixed slurry between two layers of ITO substrates, and use ultraviolet light irradiation to cure at a temperature of 0 to 25°C to obtain a polymer dispersed liquid crystal layer; wherein the mass percentages of the polymerizable monomer, liquid crystal and photoinitiator are (10 to 70)%: (90 to 30)%: (0.5 to 5)%.

2. A high contrast polymer dispersed liquid crystal reflective display device according to claim 1, characterized in that: The first electrode layer is provided with a plurality of first sub-electrodes arranged in a matrix, the second electrode layer is provided with a plurality of second sub-electrodes arranged in a matrix, the first sub-electrodes are provided with gate lines and data lines connected thereto, and the second sub-electrodes are also provided with gate lines and data lines connected thereto; Alternatively, the first electrode layer is provided with a plurality of first sub-electrodes arranged in a matrix, each of which is provided with gate lines and data lines connected thereto; the second electrode layer is a common electrode, and the first sub-electrodes and the common electrode generate a vertical electric field to drive the polymer dispersed liquid crystal layer.

3. A high contrast polymer dispersed liquid crystal reflective display device according to claim 1, characterized in that: A plurality of pixel units formed by crossing gate lines and data lines are arranged on the first electrode layer, each pixel unit includes a first sub-electrode and a TFT unit, and the TFT unit is connected to the corresponding first sub-electrode; The second electrode is a common electrode, and the first sub-electrode and the common electrode generate a vertical electric field to drive the polymer dispersed liquid crystal layer.

4. A high contrast polymer dispersed liquid crystal reflective display device according to claim 1, characterized in that: A plurality of pixel units formed by crossing gate lines and data lines are arranged on the first electrode layer, each pixel unit includes a first sub-electrode and a TFT unit, and the TFT unit is connected to the corresponding first sub-electrode; A plurality of pixel units formed by crossing gate lines and data lines are arranged on the second electrode layer, each pixel unit includes a second sub-electrode and a TFT unit, and the TFT unit is connected to the corresponding second sub-electrode; The first sub-electrode and the second sub-electrode generate a vertical electric field to drive the polymer dispersed liquid crystal layer.

5. A high contrast polymer dispersed liquid crystal reflective display device according to any one of claims 1 to 4, characterized in that: The materials of the first electrode layer and the second electrode layer are both indium tin oxide, indium zinc oxide, graphene or silver nanowires.

6. A high contrast polymer dispersed liquid crystal reflective display device according to claim 1, characterized in that: The first substrate and the second substrate are glass substrates, plastic substrates or flexible substrates.

7. A high contrast polymer dispersed liquid crystal reflective display device according to claim 1, characterized in that: The back plate is a black or colored back plate.

8. The high contrast polymer dispersed liquid crystal reflective display device according to claim 1, characterized in that: At least one layer of film material is arranged in the air spacing layer; The film material is a prism film or an optical resin.

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