Manufacturing method of reflective film for vehicle

Abstract

The invention discloses a method for manufacturing a reflective film for a vehicle, which belongs to the field of display for the vehicle, and comprises the following steps: treating a substrate, spin-coating an alignment layer, spin-coating a liquid crystal film, separating the liquid crystal film from the substrate, removing the alignment layer, sticking a protective film and the like. A director of the second liquid crystal layer is of a spiral structure in the longitudinal direction, the first liquid crystal layer is attached to a windshield, and the reflecting film reflects light beams generated by a display device incident at the Brewster angle in a vehicle, so that the energy of the light beams forming double images is reduced, and the double images are eliminated. Only P polarized light close to the working wavelength of the display device is reflected for natural light outside a vehicle, and natural light with other wavelengths and polarization directions is transmitted, so that the reflective film for the vehicle has high reflectivity and high transmittance.

Description

Technical Field

[0001] The invention relates to the field of vehicle display, and in particular to a method for manufacturing a vehicle reflective film. Background Art

[0002] The car head-up display (HUD) is a visual assisted driving system that can provide the driver with key assisted driving information and project the driving information into a virtual image, which is displayed at a certain distance in front of the driver, so that the driver can obtain information such as vehicle speed, fuel level, real-time navigation, etc. in a head-up state, thereby avoiding the blind spot time caused by the driver lowering his head to check driving information, reducing potential traffic accidents, and ensuring driving safety.

[0003] When the existing head-up display device is used, Figure 1 As shown in the figure, point A is the image source. The light beam emitted by the image source enters the human eye after being reflected by the windshield, forming a virtual image. At the same time, the light beam emitted by the actual object in the outside world can also enter the human eye to form a real image, so as to achieve the display effect of augmented reality. Since the reflectivity of the air-glass interface is low, about 10%, only 10% of the energy of the light beam emitted by the image source can enter the human eye, the energy utilization rate is low, and the brightness is limited; at the same time, Figure 2 as well as Figure 3 As shown, reflection occurs on both sides of the windshield, both forming virtual images and causing ghosting problems, affecting driving safety.

[0004] In the prior art, a reflective film is attached to the inside of the windshield to increase the reflectivity, thereby improving energy utilization and brightness, so that the light emitted by the image source can be clear, but the problem of ghosting cannot be solved. Moreover, when the reflectivity of the reflective film is too high, the energy transmitted by the actual object will be reduced, making it impossible for the light beam of the external object to enter the human eye normally. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, one of the objectives of the present invention is to provide a method for manufacturing a vehicle reflective film that can avoid ghosting and ensure that both the light beams of external objects and the light of the image source inside the vehicle can effectively reach the human eye.

[0006] One of the purposes of the present invention is achieved by the following technical solution:

[0007] A method for manufacturing a vehicle reflective film comprises the following steps:

[0008] Substrate treatment: cleaning the glass substrate and heating the cleaned glass substrate to remove the chiral agent on the surface of the glass substrate;

[0009] Spin coating alignment layer: spin coating SD1 as the alignment layer of the substrate on the surface of the glass substrate from which the chiral agent has been removed, and aligning SD1 with ultraviolet light;

[0010] Spin-coated liquid crystal film: first spin-coat a first liquid crystal layer on the alignment layer, and then spin-coat a second liquid crystal layer on the first liquid crystal layer, the liquid crystal molecules of the first liquid crystal layer do not need to add hand-shaped liquid crystals, the directors of the first liquid crystal layer are in the same direction, and the directors of the second liquid crystal layer form a spiral structure in the longitudinal direction;

[0011] Separating the liquid crystal film from the substrate: sticking the optical adhesive with a protective film on the liquid crystal film, and then tearing off the protective film, the optical adhesive, the liquid crystal film, and the alignment layer from the glass substrate;

[0012] Removing the alignment layer: washing with water to remove the alignment layer;

[0013] Paste the protective film: Paste the optical adhesive with the protective film on the side where the alignment layer is removed to form a reflective film for the car.

[0014] Furthermore, in the substrate processing step, the glass substrate is cleaned in sequence by a glass cleaning agent, water, alcohol and water, and each cleaning is performed by an ultrasonic cleaning machine.

[0015] Furthermore, in the substrate processing step, deionized water is used to flush away residual substances after each cleaning.

[0016] Furthermore, in the substrate processing step, the glass substrate is heated at 90-110° C. for 0.5-1.5 h.

[0017] Furthermore, in the spin coating alignment layer step, the SD1 is colored.

[0018] Furthermore, in the step of spin-coating the liquid crystal film, the thickness of the first liquid crystal layer is a quarter wave plate.

[0019] Furthermore, the thickness of the first liquid crystal layer is d=λ / Δn / 4, λ is the central wavelength of the light beam emitted by the display device, and Δn is the refractive index difference of the liquid crystal material.

[0020] Furthermore, in the spin coating liquid crystal film step, the pitch of the second liquid crystal layer is n is the average refractive index of the liquid crystal material, and θ is the Brewster angle corresponding to the windshield.

[0021] Furthermore, θ = arcsin(1 / n glasss ), n glasss is the refractive index of the windshield.

[0022] Furthermore, in the step of sticking the protective film, forming the vehicle reflective film includes sequentially arranging the protective film, the optical adhesive, the first liquid crystal layer, the second liquid crystal layer, the optical adhesive and the protective film.

[0023] Compared with the prior art, the method for manufacturing a vehicle reflective film of the present invention includes the steps of substrate processing, spin coating an alignment layer, spin coating a liquid crystal film, separation of the liquid crystal film from the substrate, removal of the alignment layer, and adhesion of a protective film. The directors of the first liquid crystal layer of the manufactured vehicle reflective film are in the same direction, the directors of the second liquid crystal layer form a spiral structure in the longitudinal direction, the first liquid crystal layer is bonded to the windshield, and the reflective film reflects the light beam generated by the display device in the vehicle that is incident at the Brewster angle, so that the energy of the light beam that forms the ghost image becomes smaller and the ghost image is eliminated; for the natural light outside the vehicle, only the P polarized light close to the working wavelength of the display device is reflected, and the natural light of other wavelengths and polarization directions is transmitted, so that the vehicle reflective film has both high reflectivity and high transmittance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a light path diagram of the head-up display in the background technology;

[0025] Figure 2 It is a light path diagram produced by ghosting in the background technology;

[0026] Figure 3 It is a schematic diagram of ghosting in the background technology;

[0027] Figure 4 This is a flow chart of the method for manufacturing the vehicle reflective film of the present application;

[0028] Figure 5 This is a process diagram of the method for manufacturing the vehicle reflective film of the present application;

[0029] Figure 6 A light path diagram of a vehicle reflective film manufactured by the vehicle reflective film manufacturing method of the present application when in use;

[0030] Figure 7 This is a rendering of the method for manufacturing a vehicle reflective film of the present application;

[0031] Figure 8 This is the reflection curve of natural light of the vehicle reflective film manufacturing method of this application.

[0032] In the figure: 10, windshield; 21, first liquid crystal layer; 22, second liquid crystal layer. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may be another intermediate component through which it is fixed. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may be another intermediate component at the same time. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be another intermediate component at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0036] See also Figure 4 as well as Figure 5 The present application provides a method for manufacturing a vehicle reflective film, comprising the following steps:

[0037] Substrate treatment: cleaning the glass substrate and heating the cleaned glass substrate to remove the chiral agent on the surface of the glass substrate;

[0038] Spin coating alignment layer: Spin coating SD1 as the alignment layer of the substrate on the surface of the glass substrate from which the chiral agent has been removed, and aligning SD1 with ultraviolet light;

[0039] Spin-coated liquid crystal film: first spin-coat the first liquid crystal layer 21 on the alignment layer, and then spin-coat the second liquid crystal layer 22 on the first liquid crystal layer 21. The liquid crystal molecules of the first liquid crystal layer 21 do not need to add chirped liquid crystals. The directors of the first liquid crystal layer 21 are in the same direction, and the directors of the second liquid crystal layer 22 form a spiral structure in the longitudinal direction.

[0040] Separation of the liquid crystal film from the substrate: stick the optical adhesive with a protective film on the liquid crystal film, and then tear off the protective film, optical adhesive, liquid crystal film, and alignment layer from the glass substrate;

[0041] Removing the alignment layer: washing with water to remove the alignment layer;

[0042] Paste the protective film: Paste the optical adhesive with the protective film on the side where the alignment layer is removed to form a reflective film for the car.

[0043] Specifically, in the substrate processing step, the glass substrate is cleaned by glass cleaning agent, water, alcohol and water in turn, and each cleaning is performed by an ultrasonic cleaning machine. After each cleaning, deionized water is used to rinse off residual substances. The glass substrate is heated at 90-110°C for 0.5-1.5h. In this embodiment, the glass substrate is placed on a heating table and heated at 100°C for 1h.

[0044] In the spin coating alignment layer step, SD1 is colored, so SD1 needs to be removed in the subsequent steps.

[0045] In the step of spin coating the liquid crystal film, the thickness of the first liquid crystal layer 21 is a 1 / 4 wave plate. The thickness of the first liquid crystal layer 21 is d = λ / △n / 4, where λ is the central wavelength of the light beam emitted by the display device and △n is the refractive index difference of the liquid crystal material. The pitch of the second liquid crystal layer is n is the average refractive index of the liquid crystal material, and θ is the Brewster angle corresponding to the windshield. θ = arcsin (1 / n glasss ), n glasss is the refractive index of the windshield.

[0046] In the step of pasting the protective film, the vehicle reflective film is formed by sequentially arranging the protective film, the optical adhesive, the first liquid crystal layer 21, the second liquid crystal layer 22, the optical adhesive and the protective film.

[0047] As attached Figure 6 As shown, when using the vehicle reflective film, the protective film on the side of the vehicle reflective film close to the first liquid crystal layer 21 is torn off, and the vehicle reflective film is attached to the inner side of the windshield 10. The display device disposed in the vehicle is connected to the vehicle control system to obtain the driving parameters of the vehicle, which include information such as vehicle speed, time, gear position, weather, etc. The display device emits the driving parameters in the form of left-handed circularly polarized light.

[0048] When the left-handed circularly polarized light emitted by the display device (image source) enters the windshield 10 at the Brewster angle (56 degrees), the light beam first enters the second liquid crystal layer 22. Since the rotation direction of the light beam is the same as the rotation direction of the longitudinal period of the second liquid crystal layer 22, about 80% of the energy will be reflected and enter the human eye, and the remaining 20% ​​of the energy will pass through the first liquid crystal layer 21 and enter the interface between the windshield 10 and the air. Assuming that P light and S light each account for 10%, P light completely passes through the glass, and the energy reflected by s light is about 2%. After passing through the first liquid crystal layer 21, it becomes right-handed circularly polarized light and will be reflected by the second liquid crystal layer 22 instead of directly entering the human eye. Finally, through the second liquid crystal layer 22, the energy of the light beam that forms a ghost image and enters the human eye is only 0.4%. Even in the worst case, the light beam that enters the glass-air is all s light, and the energy of the light beam that forms a ghost image is only 0.8%. The ghost image contrast is 100, which meets the needs of safe driving. Figure 7 shown.

[0049] Since the director of the second liquid crystal layer 22 forms a spiral structure in the longitudinal direction, the spiral liquid crystal director distribution has two properties. One property is wavelength selectivity. The center position of the wavelength that can be reflected is located near λ, λ=nP cos(θ), where n is the average refractive index of the liquid crystal light, P is the pitch of the spiral liquid crystal, and θ is the propagation angle in the liquid crystal. It has no response to other wavelengths. The other property is circular polarization selectivity, which only works on circularly polarized light of one rotation direction. The natural light outside the car is not polarized, which is equivalent to 50% P polarized light and 50% S polarized light. The P light first enters the first liquid crystal layer 21 and becomes left-handed circularly polarized light, which almost completely passes through the second liquid crystal layer 22. After the S light enters the first liquid crystal layer 21, it becomes right-handed circularly polarized light and is inevitably reflected, but it also only reflects near λ, rather than the entire visible light spectrum range. Figure 8 As shown. The light beams generated by the display device (image source) are all left-handed circularly polarized light, which can be reflected with high reflectivity. Therefore, the vehicle reflective film manufacturing method 20 only reflects P-polarized light close to the working wavelength of the display device for external natural light, and transmits natural light of other wavelengths and polarization directions, thereby solving the incompatibility problem between high reflectivity and high transmittance.

[0050] Compared with the prior art, the method for manufacturing a vehicle reflective film of the present invention includes the steps of substrate processing, spin coating an alignment layer, spin coating a liquid crystal film, separating the liquid crystal film from the substrate, removing the alignment layer, and pasting a protective film. The first liquid crystal layer 21 of the manufactured vehicle reflective film has its directors in the same direction, and the directors of the second liquid crystal layer 22 form a spiral structure in the longitudinal direction. The first liquid crystal layer 21 is bonded to the windshield 10. The reflective film reflects the light beam generated by the display device in the vehicle that is incident at the Brewster angle, thereby reducing the energy of the light beam that forms the ghost image and eliminating the ghost image. For the natural light outside the vehicle, it only reflects the P polarized light that is close to the working wavelength of the display device, and transmits the natural light of other wavelengths and polarization directions, so that the vehicle reflective film has both high reflectivity and high transmittance.

[0051] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which are equivalent modifications and improvements made to the above embodiments based on the essential technology of the present invention, and all of them belong to the protection scope of the present invention.

Claims

1. A method for manufacturing a reflective film for a vehicle, characterized in that: The following steps are involved: Substrate treatment: cleaning the glass substrate and heating the cleaned glass substrate to remove the chiral agent on the surface of the glass substrate; Spin coating alignment layer: spin coating SD1 as the alignment layer of the substrate on the surface of the glass substrate from which the chiral agent has been removed, and aligning SD1 with ultraviolet light; Spin-coated liquid crystal film: first spin-coat a first liquid crystal layer on the alignment layer, and then spin-coat a second liquid crystal layer on the first liquid crystal layer, the liquid crystal molecules of the first liquid crystal layer do not need to add hand-shaped liquid crystals, the directors of the first liquid crystal layer are in the same direction, and the directors of the second liquid crystal layer form a spiral structure in the longitudinal direction; Separating the liquid crystal film from the substrate: sticking the optical adhesive with a protective film on the liquid crystal film, and then tearing off the protective film, the optical adhesive, the liquid crystal film, and the alignment layer from the glass substrate; Removing the alignment layer: washing with water to remove the alignment layer; Paste the protective film: Paste the optical adhesive with the protective film on the side where the alignment layer is removed to form a reflective film for the car.

2. The method for manufacturing a reflective film for a vehicle according to claim 1, wherein: In the substrate processing step, the glass substrate is cleaned in sequence by glass cleaning agent, water, alcohol and water, and each cleaning is performed by an ultrasonic cleaning machine.

3. The method for manufacturing a reflective film for a vehicle according to claim 2, wherein: In the substrate processing step, deionized water is used to flush away residual substances after each cleaning.

4. The method for manufacturing a reflective film for a vehicle according to claim 1, wherein: In the substrate processing step, the glass substrate is heated at 90-110° C. for 0.5-1.5 hours.

5. The method for manufacturing a reflective film for a vehicle according to claim 1, wherein: In the spin coating alignment layer step, the SD1 is colored.

6. The method for manufacturing a reflective film for a vehicle according to claim 1, wherein: In the step of spin coating the liquid crystal film, the thickness of the first liquid crystal layer is a quarter wave plate.

7. The method for manufacturing a reflective film for a vehicle according to claim 6, wherein: The thickness of the first liquid crystal layer is d=λ / Δn / 4, where λ is the central wavelength of the light beam emitted by the display device, and Δn is the refractive index difference of the liquid crystal material.

8. The method for manufacturing a reflective film for a vehicle according to claim 1, wherein: In the spin coating liquid crystal film step, the pitch of the second liquid crystal layer is n is the average refractive index of the liquid crystal material, and θ is the Brewster angle corresponding to the windshield.

9. The method for manufacturing a reflective film for a vehicle according to claim 8, characterized in that: θ=arcsin(1 / n glasss ), n glasss is the refractive index of the windshield.

10. The method for manufacturing a reflective film for a vehicle according to claim 1, wherein: In the step of sticking the protective film, forming a vehicle reflective film includes sequentially arranging the protective film, the optical adhesive, the first liquid crystal layer, the second liquid crystal layer, the optical adhesive and the protective film.

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