Directional visual information traffic sign based on electrochromic composite film layer

Abstract

The invention discloses a directional visual information traffic sign based on an electrochromic composite film layer, and belongs to the field of intelligent traffic. The mark adopts an electrochromic dynamic information pattern generation technology, and comprises a display surface formed by compounding an electrochromic display membrane and a directional vision membrane; the electrochromic display diaphragm can respond to an electric signal to change local optical properties so as to dynamically generate an information pattern; the directional vision diaphragm is a microstructure optical film with a specific optical microstructure and is configured to redistribute incident scattered light and emit the incident scattered light at a narrow visual angle, and the visible range of the information pattern is restrained. The electrochromic display membrane comprises a backboard supporting layer, a driving electrode layer, an electrochromic functional layer, an ion conduction layer, an opposite electrode layer and a front substrate layer. According to the invention, directional visualization and accurate delivery of high-resolution information are realized, ultra-low power consumption and high reliability are realized, the problem of multi-lane information interference is effectively solved, and the safety and efficiency of traffic information transmission are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of intelligent transportation, in particular to a directional visual information traffic sign based on an electrochromic composite film layer. BACKGROUND

[0002] Traffic signs are the core facilities for guiding vehicle driving, ensuring driving safety, and improving road traffic efficiency. With the development of intelligent transportation systems (ITS), traditional static signs have been difficult to meet the management needs of dynamic, information-based, and intelligent. Therefore, variable message signs (VMS) have become an important carrier for traffic flow induction, event warning, and regulation declaration.

[0003] Currently, the mainstream variable information signs mainly use the following technologies: the first type is a dot matrix LED display scheme, which displays text or simple graphics by combining LED lamp beads. Its advantages are high brightness and long visual distance, but it has low resolution, cannot present complex patterns, has strong visual granular feeling, high power consumption, and insufficient contrast in strong light or dazzling at night. The second type is liquid crystal display (LCD) technology, which can support more rich colors and graphics, but has serious bottlenecks in outdoor applications: extremely high backlight brightness leads to huge energy consumption; there is a viewing angle limitation, and distortion may occur when viewed from different directions; the glass substrate is fragile and heavy, and has poor environmental adaptability. The third type is a mechanical flip sign, which relies on a motor-driven unit to flip and display different colored surfaces. Its static display has zero power consumption and good visibility in daylight, but the mechanical structure is complex, has a high failure rate, and information switching is slow, and is prone to jamming in rainy, snowy, and icy weather. The fourth type is a fiber array sign, which can usually only achieve simple dynamic effects (such as flashing) of fixed patterns, and has extremely limited information flexibility and narrow application scenarios.

[0004] In summary, existing variable information signs have significant defects in display performance, power consumption, reliability, and functionality. An ideal new traffic sign needs to have multiple characteristics: high resolution, support for complex dynamic graphics; low power consumption, suitable for new energy power supply; high environmental reliability; excellent visibility in all weather conditions; and innovative functions such as directional information delivery.

[0005] Especially important is that existing technologies generally use "broadcast" information publishing, and the content is visible to all directions. This can easily lead to interference and misreading in multi-lane control scenarios. For example, at a ramp with lane control, different instructions such as "straight" or "left turn" need to be displayed to different lanes, and traditional signs are difficult to clearly and accurately implement this function. Therefore, developing display technology with "directional visibility" capability is of great significance to improving the accuracy and safety of traffic information transmission.

[0006] Electrochromic (EC) technology is based on the reversible electrochemical reaction of the material driven by the external electric field, which changes its color and transmittance. It has the advantages of memory, adjustable gray scale, low driving voltage, and extremely low power consumption, and has been applied in smart windows, anti-dazzle glasses and other fields. However, it still faces challenges such as material patterning preparation, film uniformity, response speed and system integration when used for high-resolution and large-area traffic information display. Microstructure optical technology, such as micro-prism or micro-lens array, can precisely control the light propagation path and has been used in optical waveguide and backlight modulation fields, which provides the possibility for directional emission of light.

[0007] In summary, there is an urgent need in the art for an innovative solution that can integrate electrochromic materials and microstructure optical technology to break through the technical limitations of existing variable information signs and develop a new generation of intelligent traffic signs with high-resolution dynamic display, directional visibility, ultra-low power consumption and high reliability. The present application is proposed to meet this need. SUMMARY

[0008] In order to overcome the shortcomings of the prior art, the present application provides a directional visual information traffic sign based on an electrochromic composite film layer. Therefore, there is an urgent need in the art for an innovative technical solution that can integrate advanced functional materials and precise optical technology to break through the technical shackles of existing variable information signs and develop a next-generation intelligent traffic sign that can not only achieve high-resolution dynamic information display but also intelligently control the visible range of information, while also having the advantages of ultra-low power consumption, high reliability, etc. This is the core technical problem to be solved by the present application.

[0009] To achieve the above-mentioned purpose, the present application provides the following solutions: A directional visual information traffic sign based on an electrochromic composite film layer, characterized in that it comprises: a display surface composed of multiple functional films, at least including: an electrochromic display film and a directional visual film; the electrochromic display film can change the local optical properties in response to an electrical signal to dynamically generate an information pattern; the directional visual film is compounded on the light-emitting side of the display film and is a microstructure optical film made by micro-replication technology, and its surface forms a specific optical microstructure, which is configured to redistribute the incident scattered light and emit it at a predetermined narrow viewing angle, for constraining the visible observation angle range of the information pattern; The electrochromic display film comprises, from back to observation surface, a back plate support layer, a driving electrode layer, an electrochromic functional layer, an ion conduction layer, a counter electrode layer and a front substrate layer; the back plate support layer is made of transparent PET flexible substrate; the driving electrode layer comprises a matrix of independent pixel electrodes made of transparent conductive material; the electrochromic functional layer is formed on the driving electrode layer and is composed of one or more electrochromic polymer materials; the ion conduction layer is in contact with the electrochromic functional layer, provides ion migration channels and guarantees the electrochemical reaction; the counter electrode layer is in contact with the ion conduction layer and constitutes a common electrode of a loop; and the front substrate layer is made of transparent flexible material and is used for packaging and protecting the above-mentioned internal functional layers.

[0010] Further, the electrochromic functional layer comprises an electrochromic polymer pixel array formed by a printing process, the electrochromic polymer material includes one or more of polyaniline (PANI), poly(3,4-ethylenedioxythiophene) (PEDOT) and derivatives thereof; the printing process is high-mesh screen printing, the dry thickness of the electrochromic functional layer is 2-3 μm, and the coloring efficiency is not less than 150 cm² / C (@550nm); the driving electrode layer comprises a matrix of 200×200 independent pixel electrodes, and the pixel array is accurately aligned with the driving electrode matrix.

[0011] Further, the ion conduction layer adopts a solid-state polymer electrolyte PVDF-HFP composite system, and the thickness is 50 μm, and the ion conductivity at 25°C is not less than 1×10⁻³ S / cm.

[0012] Further, the directional vision film is attached to the outside of the front substrate layer by an optical grade transparent adhesive, the substrate is a PET film, the refractive index is 1.575 (@550nm), and the optical microstructure on the surface is configured to redistribute the Lambert-type scattered light from the electrochromic display film and emit in a narrow viewing angle with a horizontal direction full width at half maximum (FWHM) not greater than 30°.

[0013] Still further, the optical microstructure is prism-shaped, lens-shaped or a composite structure thereof, and is manufactured by laser direct writing + hot embossing process, and the size deviation is controlled within ±2%.

[0014] Further, the driving control module comprises: a master control chip, which is made of a low-power microcontroller and is used for receiving and processing image data; a driving chip, which is made of a special electrochromic display driving IC and is used for outputting multiple independent voltage signals; a wireless communication unit, which supports 4G / 5G, Wi-Fi or LoRa communication mode and is used for remotely receiving image data; and a storage unit, which is used for temporarily storing image data and a driving program.

[0015] A control method of directional visual information traffic sign, characterized in that it comprises the following steps: 801: information receiving and analysis, the driving control module receives the image data instruction issued by the traffic control center through the wireless communication unit, and the host chip analyzes it; 802: signal generation and mapping, the host chip generates the accurate voltage control signal sequence corresponding to each independent pixel of the electrochromic display film according to the analyzed image data, in combination with the pre-stored voltage-gray scale lookup table, and outputs it through the driving chip; 803: electrochromic driving, the driving chip applies the voltage control signal to the corresponding pixel electrode of the electrochromic display film, drives the local oxidation-reduction reaction of the electrochromic functional layer to dynamically form the required information pattern; 804: directional light emission, the scattered light emitted by the information pattern is redistributed and constrained in the preset narrow viewing angle range by the optical microstructure on the surface of the directional visual film, realizing accurate delivery of information to the target direction.

[0016] A road traffic information system, characterized in that it comprises at least two directional visual information traffic signs according to claim 1, which are arranged side by side; wherein the directional visual layer of the first sign is configured to make its information visible only to the first direction, and the directional visual layer of the second sign is configured to make its information visible only to the second direction, thereby realizing the projection of different traffic information to different spatial directions.

[0017] The technical scheme of the present application has the following advantages: The directional visibility and accurate delivery of information are realized: by combining electrochromic display technology with microstructure optical film, the visible range of the information pattern of the present sign can be strictly constrained in the preset narrow viewing angle range, so that the traffic management department can issue differentiated instructions (such as no entry in a certain lane, straight ahead in another lane) to the drivers in a specific lane or direction, effectively avoiding information interference and misreading in multi-lane scenarios, and greatly improving the accuracy of traffic information transmission and driving safety.

[0018] It has high-resolution dynamic display and ultra-low power consumption: the electrochromic display technology supports high-resolution (such as 200x200 pixels), gray-scale adjustable complex pattern and text information dynamic display, overcoming the shortcomings of low resolution, strong graininess of traditional LED dot matrix signs and the inability of mechanical signs to display complex information. At the same time, the electrochromic material has a bistable characteristic, only consuming power when switching images, and the power consumption is almost zero when displaying statically. Combined with a solar power supply system, it truly realizes energy self-sufficiency and ultra-low operating cost, especially suitable for outdoor environments without city power supply. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings described in the following are only some of the embodiments of the present application, and all other drawings obtained by those skilled in the art without creative labor based on the embodiments in the present application also belong to the protection scope of the present application.

[0020] Figure 1 It is a layer diagram of an electrochromic film piece of a directional visual information traffic sign based on an electrochromic composite film layer; Figure 2 It is a schematic diagram of an electrochromic film piece of a directional visual information traffic sign based on an electrochromic composite film layer; Figure 3 It is a light path principle diagram of a directional visual information traffic sign based on an electrochromic composite film layer; Figure 4 It is a schematic diagram of a road traffic information system; Figure 5 It is a directional visual film piece diagram of a directional visual information traffic sign based on an electrochromic composite film layer; Figure 6 It is a side view of a directional visual information traffic sign based on an electrochromic composite film layer; Figure 7 It is a control diagram of a directional visual information traffic sign based on an electrochromic composite film layer.

[0021] Explanation of the reference numerals in the drawings: 1, front basic layer; 2, counter electrode layer; 3, ion conduction layer; 4, electrochromic functional layer; 5, driving electrode layer; 6, back plate support layer; 7, independent pixel electrode matrix; 8, directional visual film piece; 9, optical microstructure; 10, protective shell; 11, tempered glass window; 12, driving control module; 13, power supply; 14, electrochromic display film piece; 15, electrode lead; A, light source; B, observer. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor also belong to the protection scope of the present application.

[0023] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail in the following with reference to the drawings and specific embodiments.

[0024] The application is based on the directional visual information traffic sign system of electrochromic composite film layer, through the multi-layer flexible film composite structure and the precise control circuit to realize the directional visual of high resolution dynamic information. The core components include electrochromic display film and directional visual film, which cooperates to limit the information pattern in the preset narrow visual angle range, effectively solving the problem of multi-lane information interference. The following is the key technology implementation method: The electrochromic display film as the core display unit is fixed in the predetermined position inside the shell through the precise clamp, can respond to the specific electrical signal to change its local optical properties (including transmittance, reflectance and color), thereby dynamically generating the required information pattern of text, symbols or graphics. The film adopts a multi-layer flexible film composite structure, which includes the following functional layers from the back (close to the drive control module side) to the observation surface: The back plate support layer adopts 0.25mm thick transparent PET (polyethylene terephthalate) flexible substrate, the elastic modulus is not less than 4 GPa, the visible light band transmittance is ≥90%, the haze is <1.5%, which provides mechanical support and protection for the whole film.

[0025] The drive electrode layer is deposited on the back plate support layer by a magnetron sputtering process to form a layer of about 150nm thick ITO (indium tin oxide, In2O3:Sn) transparent conductive film, and the sheet resistance is 25±5 Ω / □. Then the ITO film is patterned by standard photolithography and wet etching process to form a matrix composed of 200 rows x 200 columns of independent pixel electrodes, the size of a single pixel electrode is about 1.4mm x 1.4mm, and the pixel pitch (Pitch) is 1.5mm including the electrode gap. Each pixel electrode is connected to the corresponding output channel of the drive control module through a fine metal lead (such as silver paste printed lead) to receive independent voltage control signals.

[0026] The electrochromic functional layer is covered on the patterned driving electrode layer and is composed of a plurality of electrochromic polymer materials, including polyaniline (PANI), poly(3,4-ethylenedioxythiophene) (PEDOT) and derivatives thereof. The functional layer is deposited on each pixel electrode by a high-precision electronic circuit silver paste printing process or a high-mesh screen silver paste printing process (screen mesh number ≥ 350 meshes) to form an electrochromic polymer pixel array accurately aligned with the driving electrode matrix. After drying, the thickness of the film layer is about 2-3 μm. The material undergoes reversible electrochemical oxidation-reduction reaction under the action of an electric field, and the coloration efficiency is not less than 150 cm² / C (@550nm), and the response time (90% switching) is less than 2 seconds, and multi-level gray display can be realized. More importantly, under the irradiation of environmental light, the electrochromic functional layer or its opposite electrode layer in the colored state acts as a high-efficiency diffuse reflector, so that the reflected light forms a Lambertian distributed scattering light field, that is, the light intensity is proportional to the cosine value of the observation angle, thereby providing uniform and isotropic incident light "raw materials" for the subsequent directional vision film.

[0027] The ion conduction layer has a thickness of 50 μm and is made of a solid-state polymer electrolyte PVDF-HFP composite system, and the ion conductivity thereof at 25°C is not less than 1×10⁻³ S / cm. The layer is uniformly covered on the electrochromic functional layer by a doctor blade coating process and is in close contact with the electrochromic functional layer, thereby providing a channel for ion migration required in the electrochemical reaction process and ensuring the rapid progress and reversibility of the reaction.

[0028] The opposite electrode layer is a transparent PET flexible substrate (thickness 0.175 mm, ITO sheet resistance ≤ 50 Ω / □) with an ITO common electrode, which is in contact with the ion conduction layer. On the ITO layer of the opposite electrode, a layer of Prussian blue (Prussian Blue) or tungsten trioxide (WO3) or other ion storage materials with high charge capacity is formed by electrochemical deposition, and the charge capacity thereof is matched with the electrochromic functional layer to form a complete electrochemical loop common electrode, thereby ensuring the charge balance of the coloring process.

[0029] The front substrate layer is a 0.125 mm thick transparent PET protective layer, and the surface thereof can be hardened (hardness up to 3H). The front substrate layer is attached to the opposite electrode layer by an optical grade transparent adhesive (OCA) to encapsulate and protect all the internal functional layers, thereby preventing water and oxygen penetration and mechanical scratching.

[0030] The electrochromic film responds to the piezoelectric signal by reversible oxidation-reduction reaction of the electrochromic polymer material to dynamically generate text, symbols or graphic information.

[0031] The directional vision film is tightly attached to the light-emitting side of the electrochromic display film (i.e. the outside of the front substrate layer) by an optical-grade transparent adhesive (OCA) with a refractive index of 1.48. The film is a microstructured optical film made by microreplication technology, with a substrate of PET film with a refractive index of 1.575 (@550nm). Its surface is precisely processed to form a specific optical microstructure, and the function of the microstructure is strictly dependent on the incident scattered light provided by the aforementioned electrochromic display film, which has Lambertian distribution characteristics. The microstructure is configured to redistribute the scattered light from the electrochromic display film, which is originally Lambertian distributed, and concentrate the light out at a preset narrow viewing angle (in this embodiment, ±15° in the horizontal direction), thereby restricting the visible observation angle range of the information pattern to this narrow area and achieving directional delivery of information.

[0032] The microstructure can be prism-shaped, lens-shaped, or a composite structure thereof. In this specific embodiment, the most commonly used asymmetric sawtooth prism structure is used as an example for detailed description.

[0033] The core optical goal of this design is to achieve a full width at half maximum (FWHM) viewing angle of light in the horizontal direction of not more than 30° (i.e. ±15°) in the visible light band of 380nm to 780nm, and to ensure the highest brightness near the normal 0°. To achieve this core optical goal of limiting the outgoing light to within ±15° (full width at half maximum, FWHM) in the horizontal direction, the following strict and precise design and manufacturing processes are required: The design input parameters include: the electrochromic display film light-emitting characteristics are approximately Lambertian light source, with scattered light; the directional vision film substrate uses polyethylene terephthalate (PET), with a refractive index of 1.575 (@550nm); the working environment is air, with a refractive index of 1.0; the target observation distance is set to 350 meters to meet the visibility requirements of typical high-grade highway traffic signs.

[0034] The microstructure unit adopts an asymmetric sawtooth prism structure, whose optical principle is not simply refraction, but a combination of refraction, total internal reflection, and collimation. Specifically, after the scattered light enters the microstructure interface from the PET substrate side, most of the light is designed to undergo total internal reflection on the first inclined surface, and the reflected light and the light directly refracted from the second inclined surface are superimposed near the target exit angle to form a narrow viewing angle light beam. This asymmetric design can more efficiently collect and direct the collection of high-angle scattered light compared to symmetric structures, significantly improving the front brightness and viewing angle control efficiency.

[0035] The key size parameters are finally determined through iterative optimization by optical simulation software such as LightTools or TracePro: the prism top angle a prism is designed as 90°, which is the core parameter to realize the light-emitting range of ±15° and directly determines the light deflection angle; the prism pitch is set as 40 μm, which is much smaller than the resolution limit (about 2.9 mm) of the human eye at the minimum design viewing distance (10 meters), ensuring that the driver cannot perceive the granular feeling of the film at any reasonable distance and can only see a uniform limited-view image; the prism height H is calculated as about 286 μm (calculation formula: H = (Pitch / 2) x tan(a prism)). The microstructure is periodically and closely arranged in the horizontal direction to form a one-dimensional linear grating array, and the prism extension direction is the vertical direction. This arrangement makes it only constrain the light propagation in the horizontal direction (X axis), while maintaining a wide viewing angle in the vertical direction (Y axis) to meet the observation needs of drivers of different heights.

[0036] The above parameters are verified by an optical simulation model, a Lambertian light source is set, and more than 1 million rays are traced. The simulation results show that: in the horizontal direction, the light intensity reaches a peak at 0° normal, and the brightness decreases smoothly with the increase of the angle, and the brightness at ±15° is about 50% of the peak brightness (consistent with the definition of half peak full width), and the brightness outside ±30° decreases to less than 5% of the peak value, and the effective visible range is strictly limited. The angle resolution luminance meter is used to measure the viewing angle distribution of the directional vision film, and the results show that: in the horizontal direction, the light intensity reaches a peak at 0° normal, and the brightness decreases smoothly with the increase of the angle, and the brightness at ±15° is about 50% of the peak brightness (consistent with the definition of half peak full width), and the brightness outside ±30° decreases to less than 5% of the peak value. The measured visible range is consistent with the simulation results, meeting the preset requirement of ±15° narrow viewing angle. The simulation also shows that this structure can redistribute and converge about 75% of the incident scattered light into a ±30° cone angle, and the optical efficiency is significantly higher than that of a simple diffusion film or a symmetric structure. Note: The experimental conditions are an observation distance of 50 meters and an ambient light of 1000 lux.

[0037] The microstructure is manufactured by micro-replication technology: laser direct writing (DLW) technology is used to directly engrave the microstructure on the PET film, avoiding the dependence on the master mold, and then the processed master mold roller is installed in a precision roll-to-roll imprinting equipment, and the microstructure is batch transferred to the PET film surface by hot stamping or ultraviolet stamping. Finally, the size deviation (controlled within ±2%) is detected by a white light interferometer or a confocal microscope, and the viewing angle distribution is measured by an angle resolution luminance meter to ensure consistency with the simulation results, so as to ensure the consistency of the optical performance of the mass-produced film.

[0038] The sign also includes a protective shell made of high-strength 6063-T5 aluminum alloy material, with a surface treated by anodic oxidation, a film layer thickness of not less than 10 μm, good corrosion resistance and mechanical strength. The shell structure is designed as a sealed type, all joints are sealed with weather-resistant silicone sealant, the front cover and bottom shell are connected by stainless steel 304 fasteners, ensuring that the whole reaches IP65 protection level, effectively preventing dust and water, and adapting to outdoor harsh environments.

[0039] The front of the shell is provided with a high-transmittance tempered glass window, with a glass thickness of 4 mm, a transmittance of not less than 92%, a Mohs hardness of not less than 6, and can withstand the impact of a steel ball with a diameter of 22 mm freely falling from a height of 1 meter. The inside of the shell is provided with precise mounting grooves and fixing hole positions for firmly fixing the electrochromic display film, drive control module and power supply system. The rear of the shell is provided with a strip-shaped heat dissipation hole, with a dustproof and waterproof breathable film attached inside the heat dissipation hole to ensure heat dissipation while maintaining the protection level; at the same time, it is provided with a waterproof wiring port of M20x1.5 specification, facilitating the introduction of power lines and communication lines. Taking a typical medium-sized sign as an example, its outer dimensions are designed as 1200 mm (wide) x 800 mm (high) x 120 mm (thick), with a back reserved for mounting lugs in accordance with national standards, supporting various installation methods such as hoop installation or column installation.

[0040] The drive control module is installed at the rear of the shell, mainly including a main control chip, a drive chip, a wireless communication unit and a storage unit. The main control chip adopts an STM32L4 series ultra-low power microcontroller based on an ARM Cortex-M4 core, with a maximum running frequency of 80 MHz, and integrates a hardware graphics accelerator (Chrom-ART Accelerator™). It is responsible for receiving image data (supporting BMP, PNG and other formats) from the traffic control center through the wireless communication unit, and performing analysis, processing and data mapping. The drive chip adopts a customized special electrochromic display drive chip, providing 40,000 (corresponding to 200x200 pixels) independent voltage output channels. Each channel integrates a 12-bit precision digital-to-analog converter (DAC), with an output voltage range of -2.0 V to +2.0 V, which can apply an accurate voltage control signal to each pixel to accurately control the oxidation-reduction state of the electrochromic material and achieve rich grayscale display. The main communication module of the wireless communication unit adopts a 4G Cat.1 communication module (such as the Yida EC200S series), which supports the TCP / IP protocol stack and can reliably access the Internet to realize real-time data interaction with the remote traffic control center and receive image update instructions and data. At the same time, a LoRa (Long Range) communication module can be optionally configured as a backup or regional networking communication method, suitable for low-power, short-range data reporting scenarios. The storage unit has an external 16MB SPI Flash memory for storing system drivers, font libraries, and a number of pre-set common traffic sign patterns (such as speed limit signs, arrow indicators, prohibition signs, etc.), which can be used to display pre-set information when the network is not available.

[0041] After the main control chip receives new image data, it decodes and converts it into a 200x200 grayscale pixel matrix for each frame. The system internally stores a lookup table of the voltage-grayscale (γ) correspondence of the electrochromic material determined in advance through experiments. The main control chip maps the target grayscale value to the corresponding voltage amplitude and necessary pulse width signal according to the LUT, and accurately applies it to each pixel electrode through the drive IC, driving the electrochromic functional layer to locally change color, and finally completing the refresh display of the entire information pattern within 2 seconds.

[0042] The power system is located at the bottom of the shell, including a solar panel, a storage battery and a power management circuit. The solar panel uses monocrystalline silicon or polycrystalline silicon material with a conversion efficiency of not less than 20%, installed on the top or side of the sign, used for collecting solar energy and converting it into electrical energy. The storage battery uses a lithium ion or iron phosphate lithium battery pack, with a capacity configured according to actual needs, used for storing electrical energy and providing power at night or on cloudy days. The power management circuit is responsible for power conversion, distribution and charge / discharge management to ensure stable and efficient operation of the system. The entire power system supports off-grid operation and is suitable for outdoor environments without mains power supply.

[0043] In the system workflow, the traffic control center generates corresponding instruction information such as "left turn closed", "speed limit 80", "congestion ahead" and corresponding graphic data according to real-time traffic flow, accidents or construction, etc., and issues them to the driving control module of the target sign through the 4G network. The main control chip receives and analyzes these data. The driving control module generates corresponding pixel-level voltage control signals according to the image data, and applies them to each independent pixel electrode of the electrochromic display film. The electrochromic functional layer undergoes rapid and reversible electrochemical reaction under voltage driving, and dynamically generates a clear information pattern. Under the irradiation of environmental light, the information pattern light (scattered light) generated by the electrochromic layer forms a Lambertian distribution. The information pattern light (scattered light) generated by the electrochromic layer passes through the directional vision film. This scattered light as a light source, when passing through the directional vision film, the precise microstructure on the surface of the film re-distributes the light, and most of its energy is constrained in the preset narrow viewing angle range. Only the driver (Observer A) in the preset target direction or lane (for example, the left turn lane) can clearly see the complete "left turn" arrow sign, while the driver (Observer B) in the adjacent lane (straight lane) observes a sharp drop in brightness and can only see a weak background or no display state. This fundamentally avoids the possibility of mutual interference of multi-lane information and misreading by the driver. After the image refresh is completed, the electrochromic material can maintain the display state for a long time (several hours to several days, depending on the environmental conditions) without power supply due to its bistable characteristics. At this time, the system power consumption is reduced to standby level (<2W), which is maintained by the solar panel and battery system, achieving extremely high energy utilization efficiency. Bistable characteristic experiment verification: the electrochromic functional layer can maintain the display state for up to 72 hours in a laboratory environment (25℃, 50% RH); the longest maintenance time in outdoor exposure test (40℃, 80% humidity) is ≤48 hours. Therefore, it is recommended to set a timing refresh mechanism for the system, and the refresh cycle for outdoor application scenarios should not be longer than 24 hours to ensure the absolute reliability of the display information.

[0044] The directional vision information traffic sign of the present application can be flexibly combined to build an intelligent road traffic information system. For example, at the merging and diverging place of the highway ramp or on the multi-lane main road in the city, two or more signs as claimed in claim 1 can be arranged side by side (see Figure 3: system application schematic diagram). By precisely designing the installation angle, the light beams of the directional visual layer of the first sign are directed to the first direction (for example, corresponding to the left-turn lane), and the light beams of the directional visual layer of the second sign are directed to the second direction (for example, corresponding to the straight lane). Each sign can independently receive and display different instruction information (for example, the first sign displays “turn left”, and the second sign displays “go straight”), so as to project completely different traffic information to the lanes in different spatial directions, realize unprecedented fine lane-level management and information guidance, and greatly improve the road traffic efficiency and safety.

[0045] In the description of the present application, it should be understood that the terms “front”, “back”, “up”, “down”, “outer”, “inner”, “horizontal”, “top”, “bottom”, “surface”, “bottom layer”, “top layer”, “upper”, “lower”, “bottom”, “top”, “inner”, “surface”, “center”, “right side”, “middle” and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0046] The above-described embodiments are only descriptions of the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A directional visual information traffic sign based on an electrochromic composite film layer, characterized in that, The display surface is composed of multiple functional films, including at least an electrochromic display film and a directional vision film; the electrochromic display film can change local optical properties in response to electrical signals to dynamically generate information patterns; the directional vision film is compounded on the light-emitting side of the display film and is a microstructured optical film made by microreplication technology, with specific optical microstructures on its surface, which are configured to redistribute incident scattered light and emit it at a preset narrow viewing angle, for constraining the visible observation angle range of the information patterns. The electrochromic display film includes, from back to observation surface, a back plate support layer, a driving electrode layer, an electrochromic functional layer, an ion conduction layer, a counter electrode layer, and a front substrate layer; the back plate support layer uses a transparent PET flexible substrate; the driving electrode layer includes a matrix of independent pixel electrodes made of transparent conductive material; the electrochromic functional layer is overlaid on the driving electrode layer and is composed of one or more electrochromic polymer materials; the ion conduction layer is in contact with the electrochromic functional layer, providing ion migration channels to ensure the electrochemical reaction; the counter electrode layer is in contact with the ion conduction layer, constituting the common electrode of the circuit; the front substrate layer is a transparent flexible material for encapsulating and protecting the above-mentioned internal functional layers. The electrochromic functional layer includes an electrochromic polymer pixel array formed by a printing process, the electrochromic polymer material including one or more of polyaniline (PANI), poly(3,4-ethylenedioxythiophene) (PEDOT), and derivatives thereof; the printing process is high-mesh screen printing, and the dry thickness of the electrochromic functional layer is 2-3 μm, with a coloring efficiency not less than 150 cm² / C (@550nm); the driving electrode layer includes a 200×200 matrix of independent pixel electrodes, and the pixel array is accurately aligned with the driving electrode matrix.

2. The traffic sign based on the electrochromic composite film layer for directional visual information according to claim 1, characterized in that, The ion conduction layer uses a solid-state polymer electrolyte PVDF-HFP composite system with a thickness of 50 μm, and an ionic conductivity not less than 1×10⁻³ S / cm at 25°C.

3. The electrochromic composite film layer based directional visual information traffic sign according to claim 1, characterized in that, The counter electrode layer uses a transparent PET flexible substrate with an ITO common electrode, and an ion storage material layer is formed on the ITO layer, the ion storage material including Prussian Blue or tungsten trioxide (WO3).

4. The electrochromic composite film layer based directional visual information traffic sign according to claim 1, characterized in that, The directional vision film is attached to the outside of the front substrate layer by an optical-grade transparent adhesive, and its substrate is a PET film with a refractive index of 1.575 (@550nm), and the optical microstructures on its surface are configured to redistribute the Lambertian scattered light from the electrochromic display film and emit it in a narrow viewing angle with a horizontal full width at half maximum (FWHM) not greater than 30°.

5. The electrochromic composite film layer based directional visual information traffic sign according to claim 1, characterized in that, The optical microstructures are prism-shaped, lens-shaped, or their composite structures, manufactured by laser direct writing + hot embossing process, with a size deviation controlled within ±2%.

6. The electrochromic composite film layer based directional visual information traffic sign according to claim 5, characterized in that, ​ 7. The electrochromic composite film layer based directional visual information traffic sign according to claim 1, characterized in that, The driving control module comprises: a master control chip, which is a low-power microcontroller, for receiving and processing image data; a driving chip, which is a dedicated electrochromic display driving IC, for outputting multiple independent voltage signals; a wireless communication unit, which supports 4G / 5G, Wi-Fi or LoRa communication modes, for remotely receiving image data; and a storage unit for temporarily storing image data and a driving program.

8. A control method of a directional visual information traffic sign, characterized by, The method comprises the following steps: 801: information receiving and analyzing, the driving control module receives image data instructions issued by the traffic control center through the wireless communication unit, and the master control chip analyzes the received data; 802: signal generation and mapping, the master control chip generates accurate voltage control signal sequences corresponding to each independent pixel of the electrochromic display film according to the analyzed image data and in combination with a pre-stored voltage-gray scale lookup table, and outputs the signal sequences through the driving chip; 803: electrochromic driving, the driving chip applies the voltage control signal to the corresponding pixel electrode of the electrochromic display film, drives the local oxidation-reduction reaction of the electrochromic functional layer, and dynamically forms the required information pattern; 804: light directional emission, the scattered light emitted by the information pattern passes through the directional vision film, is redistributed and constrained in a preset narrow viewing angle range by the optical microstructure on the surface of the film, and is concentratedly emitted, thereby realizing accurate delivery of information to the target direction.

9. A road traffic information system characterized by comprising: The method comprises the following steps: 801: information receiving and analyzing, the driving control module receives image data instructions issued by the traffic control center through the wireless communication unit, and the master control chip analyzes the received data; 802: signal generation and mapping, the master control chip generates accurate voltage control signal sequences corresponding to each independent pixel of the electrochromic display film according to the analyzed image data and in combination with a pre-stored voltage-gray scale lookup table, and outputs the signal sequences through the driving chip; 803: electrochromic driving, the driving chip applies the voltage control signal to the corresponding pixel electrode of the electrochromic display film, drives the local oxidation-reduction reaction of the electrochromic functional layer, and dynamically forms the required information pattern; 804: light directional emission, the scattered light emitted by the information pattern passes through the directional vision film, is redistributed and constrained in a preset narrow viewing angle range by the optical microstructure on the surface of the film, and is concentratedly emitted, thereby realizing accurate delivery of information to the target direction.

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