Arched structure electronic ink screen without front light guide plate

Abstract

The invention discloses an arched structure electronic ink screen without a front light guide plate, and belongs to the technical field of semiconductor display. The electronic ink screen comprises an arch-shaped EPD display module, wherein an effective display area of the arch-shaped EPD display module is integrally of an arch-shaped structure; luminous sources of the double-side luminous source assembly are arranged on the edges of the left side and the right side of the arch-shaped EPD display module in parallel, and the light emitting direction faces the inwards-concave curved surface of the arch-shaped EPD display module. By establishing and satisfying the specific mathematical relationship between the geometric parameters of the arched structure and the light source parameters, the light emitted by the light sources on the two sides can directly and uniformly cover the whole arched display surface, so that a traditional front light guide plate is omitted. The problems of heavy screen, complicated structure, low optical efficiency, high cost, poor outdoor adaptability and the like caused by the use of a light guide plate in the prior art are solved, the light guide plate is particularly suitable for a large-size outdoor display screen, and light, thin, high-reliability and efficient illumination is realized.

Description

Technical Field

[0001] This invention relates to the field of semiconductor display technology, and more specifically to an arched structure electronic ink screen without a front light guide plate. Background Technology

[0002] Electronic ink display (EPD) is a reflective display device based on the principle of electrophoresis. Due to its outstanding advantages such as bistable characteristics (the image can still be maintained after power is off), extremely low power consumption, no self-illumination, and visual experience close to traditional paper, it has been widely used in many fields such as e-book readers, electronic price tags, and static information signs.

[0003] However, e-ink screens themselves do not emit light; their display relies on the reflection of ambient light. In low-light conditions such as insufficient ambient light or at night, users cannot clearly see the screen content, thus necessitating the addition of an auxiliary lighting system, namely a frontlight system. Currently, commonly used frontlight solutions in the industry include... Figure 2 As shown, its basic components include: a front light guide plate disposed above the EPD display layer, and linear or dot-shaped light sources (usually LEDs) located on one or both sides of the light guide plate. Its working principle is as follows: light emitted from the light source couples into the light guide plate at a specific angle, is conducted through total internal reflection inside the light guide plate, and the total internal reflection condition is disrupted by microstructures (such as scattering dots, prism grooves, etc.) pre-fabricated on or inside the light guide plate, thereby uniformly converting the light emitted from the linear or dot-shaped light source into a planar light source covering the entire display area, illuminating the EPD display layer surface from top to bottom, achieving supplementary lighting.

[0004] While the aforementioned front-lighting solution with a light guide plate has addressed the reading problem in low light to some extent, it suffers from a series of inherent technical flaws, which become increasingly prominent as screen sizes grow larger and its application in complex outdoor environments: 1. Increased overall weight and thickness: The light guide plate itself is made of transparent optical materials (such as PMMA and PC), which have a certain thickness and weight. For large-size displays (such as those larger than 55 inches), the volume and weight of the light guide plate will increase dramatically, making the whole device bulky, which is not conducive to transportation and installation, and also puts higher demands on the support structure.

[0005] 2. High manufacturing cost and process complexity: To achieve uniform surface light output, the microstructure design and processing precision requirements within the light guide plate are extremely high. Injection molding and microstructure processing of large-size light guide plates are difficult, making it hard to control the yield rate. Furthermore, the optical coupling between the light guide plate and the light source, as well as the assembly and alignment processes with other layers of the display screen (such as protective glass and touch layer), are complex, further increasing production costs.

[0006] 3. Optical efficiency loss: Light undergoes multiple reflections, scattering, and refractions within the light guide plate before finally reaching the EPD surface. This long-path transmission inevitably involves light energy absorption and scattering losses, reducing overall illumination efficiency. To achieve sufficient brightness, it is often necessary to increase the power of the light source, leading to increased energy consumption.

[0007] 4. Poor adaptability to outdoor environments: Traditional structures typically consist of multiple layers, including protective glass, touch layer, light guide plate, and EPD display layer. In outdoor applications, the drastic temperature variations between day and night and between seasons can cause structural deformation and stress due to differences in the coefficients of thermal expansion between different material layers. This can lead to delamination, optical defects such as Newton's rings or interference fringes, affecting display performance and long-term product reliability.

[0008] 5. High transportation and installation risks: The large-area light guide plate and the screen components composed of it are fragile items. The packaging and protection measures required during transportation and installation are stringent, which increases logistics costs and operational risks.

[0009] In summary, existing e-ink screen lighting solutions based on front light guide plates face multiple technical bottlenecks when moving towards larger sizes and more demanding outdoor applications, including lightweighting, thinning, cost control, and reliability improvement. Therefore, there is an urgent need in this field to develop a new front-lighting technology solution for e-ink screens that can eliminate the need for traditional light guide plates, innovate directly from the lighting principle and structure, and achieve a lightweight, thin, efficient, reliable solution suitable for large-size outdoor applications. Summary of the Invention

[0010] In view of the technical problems of existing e-ink screens using front light guide plates, such as large weight, high thickness, complex structure, low optical efficiency, and poor outdoor adaptability, this invention aims to provide an innovative lighting solution and its implementation structure.

[0011] The primary objective of this invention is to provide an e-ink screen illumination structure and method that completely eliminates the need for a traditional front light guide plate. Another objective is to provide an e-ink screen that is lighter, thinner, and has a simpler mechanical structure, making it particularly suitable for large-size, outdoor applications. A further objective is to provide a solution with a more direct lighting path, higher light energy utilization, and uniform illumination of the display surface. A further objective is to reduce the material costs and manufacturing complexity of e-ink screens and improve their long-term reliability in harsh outdoor environments.

[0012] This invention is achieved through the following technical solution: an arched electronic ink screen without a front light guide plate, characterized in that its basic structure includes: 1. Arch-shaped EPD display module: As the display function layer of the electronic ink screen, the effective image display area as a whole is in an arch-shaped structure. This arch-shaped structure shows a smooth arc surface in the cross-sectional profile, for example, preferably a circular arc. This module can be realized by bending and fixing a flexible electronic ink film (EPD film) on a rigid or semi-rigid backplane with the same arch-shaped structure.

[0013] 2. Bilateral light source assembly: At the left and right edges of the arch-shaped EPD display module, at least one light source is respectively arranged in parallel. Preferably, the light source is a patch LED strip. The main light-emitting direction of all light sources is set to face the concave curved surface of the arch-shaped EPD display module.

[0014] 3. Key parameter matching relationship: To achieve uniform illumination of the arch-shaped curved surface directly from both sides, the present invention establishes a design matching relationship between the geometric parameters of the arch-shaped EPD display module and the optical / position parameters of the bilateral light source assembly. Define the following key parameters: H: The arch height of the arch-shaped EPD display module, that is, the vertical distance from the arch vertex to the bottom chord.

[0015] W: The chord width of the arch-shaped EPD display module, that is, the effective width of the display area.

[0016] R: The radius of curvature of the cross-sectional profile of the arch-shaped EPD display module.

[0017] L: The vertical installation distance from the light source to the tangent of the edge of the arch-shaped EPD display module.

[0018] θ: The angle between the central light intensity axis of the light source and the tangent direction of the edge, that is, the designed light-emitting angle.

[0019] To achieve effective lighting coverage, the above parameters need to satisfy the following relationships: Basic geometric relationship: The arch height H, chord width W and radius of curvature R satisfy the formula: R = (H²+(W / 2)²) / (2H). In a preferred solution, the value range of the arch height H is: 0 < H ≤ 50 mm, to ensure that the display surface is visually approximate to a plane while achieving key optical effects.

[0020] Basic optical coverage relationship: To ensure that the light can at least cover the center of the display area, the light-emitting angle θ needs to satisfy: θ ≥ arctan((W / 2) / (R - H + L)).

[0021] Uniformity optimization relationship: To obtain better illumination uniformity, the output angle θ is further preferably satisfied as follows: θ = arctan((W / 2) / (R-H+L)) + Δθ. Wherein, Δθ is the optimization compensation angle, with a value ranging from 5° to 15°. The introduction of Δθ aims to allow the main beams from the two light sources to slightly cross the central region and overlap, compensating for the light attenuation caused by the difference in optical path length, thereby achieving a more uniform light intensity distribution across the entire arched surface.

[0022] As a further optimization and supplement to the above basic technical solution: A lens structure (such as a secondary optical lens) can be added to the outer surface of the light source. The optical design of the lens structure enables it to converge or guide the light emitted by the light source, so that the light emission angle is close to or equal to the optimal θ value calculated above (i.e., including Δθ), thereby projecting the light energy more concentratedly onto the arched surface, improving the light utilization rate and the brightness of the central area.

[0023] A diffuser with a microstructure can be set on the outside of the dual-sided light source assembly to perform optical shaping and diffusion of the original light emitted by the light source, so that its light intensity distribution is more suitable for the lighting requirements of the arched surface.

[0024] The surface of the arched EPD display module can be microtextured (e.g., forming micron-sized diffuse particles) to further eliminate possible local bright spots or dark areas by enhancing the diffuse reflection of light, thereby improving the uniformity of illumination within the viewing angle range.

[0025] The e-ink screen may also include an ambient light sensing module and a drive control circuit connected thereto, used to automatically adjust the brightness of the dual-sided light source components according to the ambient light intensity, so as to achieve intelligent energy saving and the best visual experience.

[0026] The beneficial effects of this invention are as follows: 1. Achieve lightweight and thin design: Eliminate the heavy light guide plate component, reduce the weight and thickness of the screen module, and bring benefits such as reduced transportation costs, convenient installation, and simplified support structure for large-size outdoor displays.

[0027] 2. Simplify structure and improve reliability: Eliminate the light guide plate and complex assembly process, reduce the stacked structure, reduce assembly difficulty and cost, reduce potential failure points, and improve the stability and reliability of the product in harsh environments.

[0028] 3. Improved optical efficiency and energy saving: Light directly illuminates the EPD display surface, avoiding transmission loss within the light guide plate. This results in higher screen illuminance for the same power consumption, or lower power consumption for the same illuminance, making it more energy-efficient and environmentally friendly.

[0029] 4. Reduce overall costs: Eliminating the light guide plate reduces material costs and saves on related processing, testing, and assembly costs.

[0030] 5. Enhanced safety and applicability: The lighter screen body reduces the load on the support frame and the risk of detachment, improving safety in public places; the simplified structure facilitates waterproof and dustproof design, enhancing outdoor adaptability.

[0031] 6. Optimize visual experience: Removing the light guide plate reduces reflection loss, and theoretically, the screen contrast and clarity are superior to the traditional structure during the day or when there is sufficient ambient light. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 : A schematic cross-sectional view of the overall structure of an embodiment of the present invention; Figure 2 : A cross-sectional diagram of a traditional e-ink screen with a front light guide plate; Figure 3 : A cross-sectional schematic diagram of the overall structural optimization implementation of this invention embodiment; The labels in the diagram represent: 1. Light source; 2. Front light guide plate; 3. Microstructure; 4. EPD display module; 5. Lens structure. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Reference Figure 1 As shown, this embodiment uses an 86-inch electronic ink display for outdoor bus stop signs. 1. Fabrication of the arched EPD display module: The goal of this step is to manufacture a display functional layer with a specific arched structure.

[0036] Design goals and basic parameters were defined: the display screen needed to meet the requirements of outdoor visibility, lightweight design, and nighttime readability. The effective chord width of the display area was set to W = 1870 mm. To achieve effective illumination while ensuring a near-flat visual appearance, a suitable arch height H = 15 mm was selected (meeting the preferred range of H ≤ 50 mm in this invention). The arch's geometric parameters were calculated: based on the geometric relationship formula proposed in this invention, the radius of curvature R of the arch section was calculated. The calculated radius of curvature R is approximately 29142 mm. This value is extremely large, indicating that the arch is an extremely gentle curved surface, almost imperceptible to the human eye at normal viewing distances, effectively avoiding geometric distortion of the image. However, this minute curvature has a crucial impact on light reception optically.

[0037] Back panel fabrication and display layer bonding: Based on the calculated radius of curvature R, a rigid backplate with the same arched profile is fabricated using metal (such as aluminum alloy) or high-strength engineering plastic. The backplate surface must be flat and smooth, and designed with structures for fixing and routing cables.

[0038] A mature flexible electronic ink film (EPD film) is selected as the display medium. Through a precise bonding process (such as optical adhesive bonding), the EPD film is smoothly and bubble-free adhered to the concave surface of the arched backplate to form an arched EPD display module. During bonding, it is essential to ensure uniform film tension and avoid wrinkles.

[0039] 2. Installation and Optical Design of Dual-Sided Light Source Components This step is crucial for ensuring uniform illumination and involves the precise design of position, angle, and light distribution.

[0040] Determine the installation location: Initially determine the installation location of the LED light strip, that is, the vertical distance L = 8mm from the center of the light source to the tangent of the edge of the EPD module. This distance needs to be reserved in the structural design, taking into account heat dissipation, electrical insulation and mechanical strength.

[0041] Computational fundamentals and optimization of the output angle: Calculate the minimum coverage angle θ min To ensure that the light reaches at least the center point O of the display surface, calculate the minimum light emission angle.

[0042]

[0043] The final optical angle θ was determined as follows: To ensure effective superposition of light rays from both sides in the central region and to compensate for attenuation caused by the optical path difference and increased incident angle, an optimized compensation angle was introduced. (In this invention) (within the preferred range). Therefore, the final designed beam angle is:

[0044] Light source selection and light distribution: High-efficiency, long-life surface-mount LEDs are selected as the light source and arranged in a light strip. To achieve a beam angle of approximately 12° (half-angle), a secondary optical lens is selected or customized for each LED. The optical design of this lens controls its beam angle (e.g., full width at half maximum) to approximately 24° (corresponding to a half-angle of approximately 12°), ensuring that most of the light energy is concentrated and projected onto the arched curved surface, such as... Figure 3 As shown.

[0045] Installation and debugging: Install the LED light strips with lenses on the left and right sides of the arched EPD display module, ensuring that the long axis of the light strip is parallel to the edge of the module. Adjust the angle between the optical center axis of the lens of all LEDs and the tangent of the edge to about 11.84° and point to the concave surface of the module.

[0046] 3. Uniformity Optimization Auxiliary Measures (Optional but Recommended) To further improve lighting uniformity, one or more of the following auxiliary measures can be adopted: Add a diffuse reflector: Install a diffuse reflector with microprisms or scattering particles on the inner surface of the LED strip on the outside (the side facing away from the EPD). This reflector can reflect or scatter some of the light escaping to the side and the gap light between the LED chips back to the arched surface, and perform initial homogenization of the original light, making the light intensity distribution projected onto the EPD surface softer and more continuous.

[0047] Surface texturing: The outermost protective surface (or touch layer surface) of the arched EPD display module is finely textured, for example, by chemical etching or coating with micron-sized diffuse particle coatings to form a light scattering structure. This helps to break up slight light spots or bright lines that may be caused by precise light distribution, and increases the diffusion angle of light, thereby obtaining a more consistent brightness perception from different viewing angles.

[0048] Optical Simulation and Verification: Before physical fabrication, a virtual model including an arched EPD surface and LED light source (including a lens model) is created using professional optical simulation software (such as LightTools and TracePro). Ray tracing simulation allows for direct observation of light coverage and fine-tuning of parameters (L, θ, lens light distribution curve). This embodiment verifies through simulation that, using the above parameters and adding a diffuser, the screen's illuminance uniformity (minimum illuminance / maximum illuminance) in a darkroom environment can reach over 85%, meeting the visual requirements for outdoor information display.

[0049] 4. System Integration and Control Drive and Control: Connect the arched EPD display module and the bilateral LED light bars to the drive control circuit board respectively. Integrate an ambient light sensor in the control system. The system software is configured to automatically adjust the PWM (pulse width modulation) drive current of the bilateral LED light bars according to the ambient illuminance value collected by the ambient light sensor, achieving stepless dimming. For example, in the late night when the ambient light is extremely weak, the LEDs work at full power; at dusk or dawn, the LEDs work at medium power; during the day, the LEDs are completely turned off to save power consumption.

[0050] Outdoor Protection Package: Install the above-integrated core display module in a housing with an IP65 or higher protection level. The housing should use a front panel made of UV-resistant material (such as UV-stabilized polycarbonate) to protect the internal structure from sun and rain. At the same time, design a good heat dissipation air duct or use heat-conducting materials to ensure that the heat generated when the LEDs work can be effectively dissipated.

[0051] Effect of Embodiment: The 86-inch outdoor electronic ink screen manufactured through the above specific implementation methods, compared with the same-size screen using a light guide plate traditionally: The weight is reduced by about 35%, mainly due to the cancellation of the heavy light guide plate.

[0052] The thickness of the module is reduced by about 30%, and the structure is more compact.

[0053] When lit at night, the screen brightness is uniform, without the obvious "dark area" phenomenon of bright on both sides and dark in the center.

[0054] The overall power consumption (at the same subjective brightness) is reduced by about 20%, and the energy-saving effect is remarkable.

[0055] In the high-temperature and high-humidity and temperature cycle accelerated aging tests, no Newton's rings or delamination problems caused by the thermal expansion mismatch of the lamination materials occurred, and the reliability was verified.

[0056] Other Implementation Possibilities: Those skilled in the art should understand that the above embodiments are for demonstration only, not for limitation. Under the premise of following the core principle of the present invention, various modifications can be made: Adjustment of Arch Height H: For screens of different sizes (such as 32 inches, 55 inches) or different application scenarios (indoor, semi-outdoor), the arch height H can be flexibly selected within the preferred range defined in the present invention (0 < H ≤ 50). Smaller-sized screens can choose smaller H values (such as -3 - 8 mm) to balance lightweight and optical effects.

[0057] Diversity of Light Sources: The light source is not limited to LEDs. Others such as OLED light strips, cold cathode fluorescent lamps (CCFL), etc. can also be applied after adapting the corresponding drive and optical designs.

[0058] Extended driving modes: Dual-sided light sources can be controlled independently in zones. For example, each light strip can be divided into two or more segments, and dimmed independently according to the brightness requirements of the area displaying content on the screen, achieving more precise energy-saving control.

[0059] In summary, this invention achieves ultimate lightweighting and thinning: it completely eliminates the heavy light guide plate assembly found in traditional solutions, significantly reducing the overall weight and structural thickness of the screen module. For large-size outdoor displays, this directly brings a chain of benefits, including reduced transportation costs, improved installation convenience, and simplified support structures.

[0060] This invention significantly simplifies the overall structure and improves reliability: it eliminates the need for a precision light guide plate and its complex assembly and alignment process, reducing the number of layers in the screen. This not only reduces assembly difficulty and cost, but also reduces potential failure points such as delamination and Newton's rings caused by mismatched thermal expansion coefficients of multiple materials, significantly improving the long-term stability and reliability of the product under harsh environments such as outdoor temperature cycling and vibration.

[0061] This invention improves optical efficiency and energy saving: light emitted from both light sources directly illuminates the EPD display surface, avoiding absorption and scattering losses during long-distance transmission within the light guide plate. Therefore, with the same power consumption, higher screen illuminance can be achieved; or, while achieving the same illuminance, lower power consumption is achieved, making it more energy-efficient and environmentally friendly.

[0062] This invention effectively reduces overall costs: Light guide plates, especially large-sized ones with high uniformity requirements, are a major cost component of traditional front-facing lighting systems. This invention eliminates the light guide plate, directly reducing material costs (BOMCost), and also saving on related precision machining, testing, and assembly costs.

[0063] This invention enhances safety and applicability: the lighter screen body reduces the load on the mounting brackets and decreases the risk of accidental detachment, improving safety for use in public places. The simplified structure facilitates waterproof and dustproof sealing designs, enhancing adaptability for outdoor applications.

[0064] This invention optimizes the visual experience: by removing the physical layer of the light guide plate, the reflection loss of light at the air-light guide plate interface is reduced. In theory, the contrast and clarity of the screen are superior to the traditional structure with a light guide plate in daylight or when there is sufficient ambient light.

[0065] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An arched structure electronic ink screen without a front light guide plate, characterized in that, include: The arched EPD display module has an overall arched structure in its effective display area; A dual-sided light source assembly includes light sources that are respectively arranged parallel to the left and right edges of the arched EPD display module, and the light emission direction of the light sources is towards the concave curved surface of the arched EPD display module; The relative positional relationship between the arched EPD display module and the dual-sided light source components satisfies the following condition: the light emission angle θ of the light source satisfies: θ≥arctan((W / 2) / (R-H+L)), Where H is the arch height of the arched EPD display module, W is the chord width of the arched EPD display module, R is the radius of curvature of the cross-sectional profile of the arched EPD display module, and L is the vertical distance from the light source to the tangent of the edge of the arched EPD display module.

2. The arched structure electronic ink screen without a front light guide plate according to claim 1, characterized in that, The arch height H of the arched EPD display module satisfies: 0 <H≤50mm。 3. The arched structure electronic ink screen without a front light guide plate according to claim 1 or 2, characterized in that, The arch height H, chord width W, and radius of curvature R of the arched EPD display module satisfy the following relationship: R=(H²+(W / 2)²) / (2H).

4. The arched structure electronic ink screen without a front light guide plate according to claim 1, characterized in that, The light emission angle θ of the light source further satisfies: θ=arctan((W / 2) / (R-H+L))+Δθ, where Δθ is the optimized compensation angle, and 5°≤Δθ≤15°.

5. The arched structure electronic ink screen without a front light guide plate according to claim 4, characterized in that, The outer surface of the light source is provided with a lens structure, which is configured to make the light emission angle of the light source close to θ.

6. The arched structure electronic ink screen without a front light guide plate according to claim 1, characterized in that, The arched EPD display module includes a flexible EPD film and an arched back plate that supports the flexible EPD film.

7. The arched structure electronic ink screen without a front light guide plate according to claim 1, characterized in that, The light source is an LED light strip.

8. The arched structure electronic ink screen without a front light guide plate according to claim 1, characterized in that, It also includes a microstructure diffuse reflector disposed on the outside of the dual-sided light source assembly.

9. The arched structure electronic ink screen without a front light guide plate according to claim 1, characterized in that, The surface of the arched EPD display module has been treated with fine texturing.

10. The arched structure electronic ink screen without a front light guide plate according to claim 1, characterized in that, It also includes a drive control circuit for adjusting the brightness of the dual-sided light source components according to the ambient light intensity.

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