A dual-sided independent projection display system and method

Abstract

The application discloses a double-sided independent projection display system and method, and relates to the technical field of double-sided display and naked-eye 3D technology. The double-sided independent projection display system comprises a double-sided imaging screen unit, a first projection unit, a second projection unit and a control unit. The control unit is used for adjusting the complementary and alternate switching of the light transmission state of the first electrically-controlled light adjustment layer and the light transmission state of the second electrically-controlled light adjustment layer. The first electrically-controlled light adjustment layer and the second electrically-controlled light adjustment layer are arranged on the two sides of the optical imaging layer respectively, and the control unit is used for keeping the light transmission state of the first electrically-controlled light adjustment layer and the second electrically-controlled light adjustment layer in complementary and alternate switching, and the first projection unit and the second projection unit are synchronously adjusted to alternately project, so that a dynamic light path isolation mechanism is constructed in the time dimension, only the light path of one side is conducted and the light path of the other side is blocked at the same time, the double-sided picture crosstalk is fundamentally eliminated, and the hardware and time sequence basis are provided for the double-sided independent three-dimensional display.

Description

Technical Field

[0001] This invention relates to the field of dual-sided display and naked-eye 3D technology, and more specifically, to a dual-sided independent projection display system and method. Background Technology

[0002] Naked-eye 3D is a technology that achieves stereoscopic visual effects without wearing glasses. It separates the images of the left and right eyes through methods such as light barriers, lenticular lenses, and directional light sources, and uses the principle of parallax to form three-dimensional perception [5-6]. Its core technologies include parallax barriers, microlens arrays, and pupil tracking [10-11], and it is widely used in gaming devices, advertising screens, medical and educational fields.

[0003] Naked-eye 3D projection display (stereoscopic display) mainly comprises two mainstream technologies: mechanical rotation and static double-sided projection. Mechanical rotation relies on a high-speed rotating physical light-blocking plate in conjunction with the projector. While it can achieve a stereoscopic visual effect, the presence of moving mechanical parts leads to high noise levels, easy wear and tear, and a short lifespan. Furthermore, it typically only serves a single-sided viewer, failing to meet the needs of simultaneous viewing from both sides. Static double-sided projection primarily uses a transparent screen with dual projectors, allowing light to pass through for viewing from both sides. However, existing static double-sided screens lack precise angle control of light, failing to create an effective parallax barrier and thus hindering stereoscopic display functionality. Simultaneously, the simultaneous transmission of images from both sides causes severe crosstalk, meaning a viewer on one side sees a ghost image of the other side, preventing independent and non-interfering display of the two images. Therefore, a technical solution capable of achieving double-sided optical path isolation and supporting 3D display within a static structure is urgently needed. Summary of the Invention

[0004] This invention provides a dual-sided independent projection display system and method, which can solve the problems of crosstalk in dual-sided display and inability to simultaneously achieve three-dimensional display in the prior art.

[0005] A dual-sided independent projection display system, comprising: A dual-sided imaging screen unit, the dual-sided imaging screen unit includes an optical imaging layer, and a first electronically controlled dimming layer and a second electronically controlled dimming layer are respectively disposed on both sides of the optical imaging layer; The dual-sided imaging screen unit is provided with a first projection unit and a second projection unit on both sides respectively. A control unit, which is communicatively connected to the first electrically controlled dimming layer, the second electrically controlled dimming layer, the first projection unit, and the second projection unit; The control unit is used to adjust the complementary alternating switching of the light transmission state of the first electronically controlled dimming layer and the light transmission state of the second electronically controlled dimming layer, and to synchronously adjust the alternating projection of the first projection unit and the second projection unit to achieve dynamic physical isolation of the double-sided light path and three-dimensional display.

[0006] The present invention provides a dual-sided independent projection display system, which, compared with the prior art, has, but is not limited to, the following beneficial effects: By setting a first electrically controlled dimming layer and a second electrically controlled dimming layer on both sides of the optical imaging layer in the dual-sided imaging screen unit, and using a control unit to keep the light transmission state of the first electrically controlled dimming layer and the second electrically controlled dimming layer complementary and alternately switching, while synchronously adjusting the first projection unit and the second projection unit to alternately project, a dynamic optical path isolation mechanism is constructed in the time dimension, so that only the optical path on one side is conducted at any given time while the optical path on the other side is blocked, fundamentally eliminating crosstalk between the two sides of the screen, and providing the hardware and timing basis for independent three-dimensional display on both sides.

[0007] By utilizing the rapid response characteristics of the first and second electrically controlled dimming layers between light-transmitting and scattering states, traditional mechanical rotating light-blocking components are replaced. When the first (or second) electrically controlled dimming layer is in the light-transmitting state, allowing the projected light from the corresponding side to be reflected by the optical imaging layer, the second (or first) electrically controlled dimming layer is simultaneously in the scattering state, forming a grating that physically blocks the light's penetration path on that side. This achieves dynamic spatiotemporal isolation of the double-sided optical path without the need for mechanical movement. This complementary timing control mechanism based on electrically controlled dimming layers not only completely eliminates mechanical wear and noise, significantly improving the system's lifespan and reliability, but also effectively solves the inherent crosstalk problem in static double-sided displays. This allows viewers on both sides to simultaneously view independent 3D images without interference, balancing high definition, high response speed, and a superior double-sided stereoscopic display experience.

[0008] Furthermore, both the first electronically controlled dimming layer and the second electronically controlled dimming layer are provided with a parallax barrier structure; In a scattering state, the parallax barrier structure forms a grating to block light from penetrating; In the light-transmitting state, the parallax barrier structure allows light to pass through.

[0009] Furthermore, the complementary alternating switching states include: During the first time period, the control unit adjusts the first electronically controlled dimming layer to a light-transmitting state and simultaneously adjusts the second electronically controlled dimming layer to a light-scattering state; During the second time period, the control unit adjusts the first electronically controlled dimming layer to a scattering state and simultaneously adjusts the second electronically controlled dimming layer to a light-transmitting state.

[0010] Furthermore, the materials of the first electro-controlled dimming layer and the second electro-controlled dimming layer include at least one of polymer-dispersed liquid crystal, microencapsulated liquid crystal, or polymer network liquid crystal; The parallax barrier structure includes a strip electrode structure, which is fabricated by nanolithography. The strip electrode structure is used to make the corresponding first or second electrically controlled dimming layer present a scattering state when the power is off, and to make the corresponding first or second electrically controlled dimming layer present a light-transmitting state when the power is on.

[0011] Furthermore, the optical imaging layer is a transparent thin film, which has diffuse reflection properties and allows background light to pass through; The refractive index of the optical imaging layer is matched with the refractive indices of the first and second electronically controlled dimming layers.

[0012] Furthermore, the transparent film has randomly distributed micron-scale random optical microstructures inside or on its surface. These micron-scale random optical microstructures are used to diffusely reflect incident projection light to form a projection image and allow ambient light to pass through in a straight line to present the background environment.

[0013] Furthermore, the micron-scale random optical microstructure is a mixture of irregularly arranged micro-bumps, micro-pits, microlenses, and micro-prisms.

[0014] Furthermore, it also includes: A first protective layer is disposed on the side of the first electronically controlled dimming layer that is away from the optical imaging layer; A second protective layer is disposed on the side of the second electronically controlled dimming layer that is opposite to the optical imaging layer; The optical imaging layer, the first electronically controlled dimming layer, the second electronically controlled dimming layer, the first protective layer, and the second protective layer are all bonded together using an adhesive bonding process to form a five-layer composite structure.

[0015] A method for dual-sided independent projection display, using the dual-sided independent projection display system as described above, includes: Using time-division multiplexing, the first projection unit and the second projection unit are alternately switched to project images onto the optical imaging layer; During the projection of the image, the light transmission states of the first and second electronically controlled dimming layers are switched synchronously to ensure that the light transmission states of the first and second electronically controlled dimming layers are complementary, thereby achieving dynamic physical isolation of the double-sided light path and three-dimensional display.

[0016] The dual-sided independent projection display method provided by this invention has, but is not limited to, the following beneficial effects compared to existing technologies: By using time-division multiplexing to separate the dual-sided display tasks on the time axis, and coordinating the synchronous and complementary switching of the first and second electronically controlled dimming layers, the unidirectional conductivity of the optical path is ensured during any display period, thereby guaranteeing the independence of the dual-sided display and the formation of stereoscopic vision at the method level.

[0017] Furthermore, the method for synchronously switching the light transmission state of the first electrically controlled dimming layer and the light transmission state of the second electrically controlled dimming layer includes: In the first stage, the first projection unit is turned on and projects the first parallax image, the second projection unit is turned off, and the first electronically controlled dimming layer is adjusted to be in a light-transmitting state and the second electronically controlled dimming layer is adjusted to be in a light-scattering state. In the second stage, the second projection unit is turned on and projects the second parallax image, the first projection unit is turned off, and the second electronically controlled dimming layer is adjusted to be in a light-transmitting state and the first electronically controlled dimming layer is in a light-scattering state. The first phase and the second phase are executed alternately and cyclically at a switching frequency higher than the visual persistence frequency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a dual-sided independent projection display system according to an embodiment of the present invention; Figure 2 for Figure 1 A schematic diagram of the AA section of the double-sided imaging screen unit.

[0019] Explanation of reference numerals in the attached figures: 1. Optical imaging layer; 2. First electronically controlled dimming layer; 3. Second electronically controlled dimming layer; 4. First protective layer; 5. Second protective layer. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application are described clearly and completely below with reference to the accompanying drawings. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.

[0021] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," "comprise," etc., in the specification, claims, and accompanying drawings of this application are open-ended terms, indicating that a method comprises one or more steps, or an apparatus comprises one or more elements, but do not exclude the inclusion of other steps or elements. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or primary / secondary relationship. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0022] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0024] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0025] See Figures 1-2 As shown, an embodiment of the present invention provides a dual-sided independent projection display system, comprising: The dual-sided imaging screen unit includes an optical imaging layer 1, with a first electronically controlled dimming layer 2 and a second electronically controlled dimming layer 3 respectively disposed on both sides of the optical imaging layer 1.

[0026] The dual-sided imaging screen unit has a first projection unit and a second projection unit on each side.

[0027] The control unit is communicatively connected to the first electronically controlled dimming layer 2, the second electronically controlled dimming layer 3, the first projection unit, and the second projection unit.

[0028] The control unit is used to adjust the complementary alternating switching of the light transmission state of the first electronically controlled dimming layer 2 and the light transmission state of the second electronically controlled dimming layer 3, and to synchronously adjust the alternating projection of the first projection unit and the second projection unit to achieve dynamic physical isolation of the double-sided light path and three-dimensional display.

[0029] In this embodiment, by setting a first electrically controlled dimming layer 2 and a second electrically controlled dimming layer 3 on both sides of the optical imaging layer 1 in the dual-sided imaging screen unit, and using a control unit to keep the light transmission state of the first electrically controlled dimming layer 2 and the second electrically controlled dimming layer 3 complementary and alternately switching, while synchronously adjusting the first projection unit and the second projection unit to alternately project, a dynamic optical path isolation mechanism is constructed in the time dimension, so that only the optical path on one side is open at any given time while the optical path on the other side is blocked, fundamentally eliminating crosstalk between the two sides of the screen, and providing a hardware and timing basis for independent three-dimensional display on both sides.

[0030] By utilizing the rapid response characteristics of the first electrically controlled dimming layer 2 and the second electrically controlled dimming layer 3 between light-transmitting and scattering states, the traditional mechanical rotating light-blocking component is replaced. When the first electrically controlled dimming layer 2 is in the light-transmitting state, allowing the corresponding side's projected light to be reflected by the optical imaging layer for imaging, the second electrically controlled dimming layer 3 simultaneously enters the scattering state to form a grating, physically blocking the penetration path of the light on that side. This achieves dynamic spatiotemporal isolation of the double-sided optical path without the need for mechanical movement. Correspondingly, when the second electrically controlled dimming layer 3 is in the light-transmitting state, allowing the corresponding side's projected light to be reflected by the optical imaging layer for imaging, the first electrically controlled dimming layer 2 simultaneously enters the scattering state to form a grating.

[0031] This complementary timing control mechanism based on the electronically controlled dimming layer not only completely eliminates mechanical wear and noise, significantly improving the system's lifespan and reliability, but also effectively solves the inherent crosstalk problem in static double-sided displays, allowing viewers on both sides to simultaneously view independent 3D images without interference, thus balancing high definition, high response speed, and a double-sided stereoscopic display experience.

[0032] Specifically, this embodiment differs from traditional static double-sided display technology. Complementary alternating switching means that within any given working period, the light transmission states of the first electronically controlled dimming layer 2 and the second electronically controlled dimming layer 3 are logically mutually exclusive. For example, when the first electronically controlled dimming layer 2 is in a light-transmitting state that allows light to pass through, the second electronically controlled dimming layer 3 must be in a non-light-transmitting state that blocks or scatters light, and vice versa. Synchronous alternating projection means that the output timing of the projected image is strictly bound to the switching timing of the dimming layers. That is, during the light-transmitting period of the first electronically controlled dimming layer 2, only the first projection unit outputs a valid image signal, while the second projection unit is off or outputs a black field signal; during the light-transmitting period of the second electronically controlled dimming layer 3, only the second projection unit outputs a valid image signal. Through the above-mentioned collaborative mechanism, the system constructs a dynamic physical light gate in the time dimension. Although from a macroscopic visual perspective, the screen is continuously transparent and displays simultaneously on both sides, at the microscopic physical level, at any given moment, only one unidirectional imaging light path exists, and the light path on the other side is physically blocked. This dynamic physical isolation fundamentally cuts off the path of optical crosstalk between the two images, allowing viewers on both sides to simultaneously view independent images without interference. At the same time, due to the sufficiently high switching frequency of the two images, the discrete time-division images are fused into a continuous three-dimensional stereoscopic visual experience by utilizing the persistence of vision in the human eye.

[0033] It should be emphasized that the dynamic physical isolation in this embodiment is a functional state description based on time-series multiplexing. Its implementation does not depend on specific mechanical moving parts, nor is it limited to a specific electro-optic material response curve. Any scheme that can achieve mutual exclusion conduction of the optical paths on both sides on the time axis through electronic control means such as control units falls within the protection scope of this embodiment.

[0034] Optionally, both the first electrically controlled dimming layer 2 and the second electrically controlled dimming layer 3 are provided with a parallax barrier structure.

[0035] In a scattering state, the parallax barrier structure forms a grating to block light from passing through.

[0036] In a light-transmitting state, the parallax barrier structure allows light to pass through.

[0037] In this embodiment, the parallax barrier structure differs from the fixed physical slit gratings in existing technologies; it is essentially an electrically controlled, reconfigurable optical modulation unit. In the scattering state, the parallax barrier structure forms a grating to block light penetration; in the transmittance state, it allows light to pass through. This state switching is not a simple mechanical opening and closing, but rather achieved based on changes in the degree of order within the microstructure of the electro-optic material. When in the scattering state, a refractive index mismatch region or periodic dielectric constant perturbation forms within the parallax barrier structure, causing strong volume scattering or diffraction of the incident light, thus macroscopically exhibiting a grating-like light-blocking effect, effectively blocking the light's path to the opposite side. When in the transmittance state, the refractive index within the material tends to be uniform or the microstructure is neatly aligned, eliminating light scattering centers and allowing light to pass through in a straight line. This dynamic grating based on a scattering mechanism, compared to traditional absorption polarizers or metal gratings, has higher light energy utilization and more flexible viewing angle control capabilities, forming the basis for achieving anti-crosstalk functionality in dual-sided independent displays.

[0038] Optionally, the complementary alternating switching states include: During the first time period, the control unit adjusts the first electronically controlled dimming layer 2 to a light-transmitting state and simultaneously adjusts the second electronically controlled dimming layer 3 to a light-scattering state.

[0039] During the second time period, the control unit adjusts the first electronically controlled dimming layer 2 to a scattering state and simultaneously adjusts the second electronically controlled dimming layer 3 to a light-transmitting state.

[0040] In this embodiment, the system's operating cycle is divided into alternating first time period T1 and second time period T2. During the first time period T1, the control unit applies a driving voltage to the first electrically controlled dimming layer 2, making it transparent, while simultaneously removing or reversing the driving voltage applied to the second electrically controlled dimming layer 3, making it diffuse. In this state, the image light emitted by the first projection unit can smoothly pass through the first electrically controlled dimming layer 2, and after reflection or diffuse reflection by the optical imaging layer 1, enter the field of view of the first-side viewer. At the same time, because the second electrically controlled dimming layer 3 is in a diffuse state, the grating structure formed inside it effectively blocks the light from the first projection unit from continuing to penetrate to the second side, and also blocks the interference of ambient light or potential light leakage from the second projection unit on the imaging of the first side.

[0041] Correspondingly, during the second time period T2, the states of the first electronically controlled dimming layer 2 and the second electronically controlled dimming layer 3 are reversed. That is, the first electronically controlled dimming layer 2 switches to a scattering state to block the light path on the first side, while the second electronically controlled dimming layer 3 switches to a light-transmitting state to conduct the light path on the second side. In conjunction with the projection of the second projection unit, an independent display facing the audience on the second side is achieved.

[0042] The strict mutual exclusion and synchronization of the light transmission and scattering states is the specific hardware-level mapping of the dynamic physical isolation of the double-sided optical path achieved in this application. Mutual exclusion requires avoiding simultaneous light transmission on both sides in physical time. If there is a brief overlap during the state transition where both sides are light-transmitting, optical crosstalk may occur between the two images at that instant. Therefore, in practical engineering implementations, the control unit is usually configured with precise timing control circuits or FPGA logic to ensure that the moment one side of the electro-dimming layer begins to transition to the scattering state is earlier than or at least synchronized with the moment the other side begins to transition to the light transmission state, or a blackout period is inserted between the two to completely eliminate the risk of crosstalk. Simultaneously, to support this high-frequency state transition, the electro-optical response time of the first electro-dimming layer 2 and the second electro-dimming layer 3 typically needs to be controlled within the millisecond or even microsecond range. For example, the response time of PDLC materials is typically in the range of 1ms to 10ms. This allows the system to maintain sufficient effective display time window while ensuring the persistence of vision fusion effect (e.g., switching frequency greater than 60Hz or 120Hz).

[0043] Optionally, the materials of the first electrically controlled dimming layer 2 and the second electrically controlled dimming layer 3 include at least one of polymer-dispersed liquid crystal (PDLC), microencapsulated liquid crystal (NCAP), or polymer network liquid crystal (PNLC). The parallax barrier structure can be given a specific hardware implementation.

[0044] The parallax barrier structure includes a strip electrode structure, which is fabricated by nanolithography. The strip electrode structure is used to make the corresponding first electrically controlled dimming layer 2 or second electrically controlled dimming layer 3 present a scattering state when the power is off, and to make the corresponding first electrically controlled dimming layer 2 or second electrically controlled dimming layer 3 present a light-transmitting state when the power is on.

[0045] In this embodiment, although the three materials—polymer-dispersed liquid crystals, microcapsule liquid crystals, and polymer network liquid crystals—have different microscopic morphologies, they all possess electric field response characteristics. This means that an applied electric field can alter the arrangement of liquid crystal molecules, thereby controlling the overall optical properties of the material. For example, PDLC materials consist of micron-sized liquid crystal droplets dispersed in a polymer matrix, NCAP encapsulates liquid crystals within microcapsules and then disperses them in a matrix, while PNLC forms a cross-linked polymer network to stabilize the liquid crystal molecules. Regardless of the specific material used, their common response mechanism is as follows: under no or weak electric field, liquid crystal molecules align randomly or at a specific pretilt angle, resulting in a significant refractive index difference between the liquid crystal and the polymer matrix, triggering strong scattering; under a sufficiently strong electric field, the liquid crystal molecules orient themselves along the direction of the electric field, matching the ordinary refractive index with the refractive index of the polymer matrix, thus making the material transparent. This multi-material parallel implementation ensures that the technical solution is not tied to a single material supplier, enhancing the security and coverage of the supply chain.

[0046] In order to precisely control the distribution of the light transmission and scattering areas of the above materials, the strip electrode structure is usually set on the inner surface of the electronically controlled dimming layer (first electronically controlled dimming layer 2, second electronically controlled dimming layer 3). Its shape, spacing and arrangement direction directly determine the grating parameters of the parallax barrier.

[0047] As a preferred manufacturing process, strip electrode structures are fabricated using nanolithography. Nanolithography enables electrode linewidth and spacing precision at the micrometer and even sub-micrometer levels, which is crucial for forming high-resolution parallax barriers. High-precision electrode structures not only generate uniform and steep electric field edges, reducing crosstalk between adjacent pixels, but also support higher-density viewpoint arrangements, thereby improving the viewing angle and smoothness of 3D displays.

[0048] In other embodiments, other patterned conductive film technologies such as laser etching, screen printing, or inkjet printing can be used depending on the resolution requirements, as long as an electrode distribution that meets the grating period requirements can be formed.

[0049] From a security perspective, when the system malfunctions or experiences an unexpected power outage, the screen automatically enters a scattering and shielding state, avoiding the serious visual confusion or privacy risks caused by simultaneous display of images on both sides. From an optical performance perspective, the natural relaxation state of electrically controlled dimming materials (especially PDLCs) is the scattering state, requiring no continuous voltage application to maintain it, and only consuming power when light transmission is needed, which helps reduce the average power consumption of the system. In practical implementation, the initial orientation of the liquid crystal material or the anchoring conditions of the polymer network can also be adjusted to design it into a "power-off light transmission, power-on scattering" mode to adapt to specific application requirements.

[0050] Optionally, the optical imaging layer 1 is a transparent film with diffuse reflection properties and allows background light to pass through.

[0051] The refractive index of the optical imaging layer 1 is matched with the refractive indices of the first electrically controlled dimming layer 2 and the second electrically controlled dimming layer 3.

[0052] In this embodiment, refractive index matching refers to controlling the difference between the refractive index of the substrate of optical imaging layer 1 and the effective refractive index of the adjacent first electrically controlled dimming layer 2 and second electrically controlled dimming layer 3 in the light-transmitting state within a preset threshold range. This matching design aims to eliminate Fresnel reflection loss at the interlayer interface. When light passes through the interface of media with different refractive indices, if the refractive index difference is large, significant interface reflection will occur. This not only reduces the transmittance of background light, causing the screen to appear grayish or severely reflective, but also generates stray light that interferes with the contrast of the projected image. Through refractive index matching, each functional layer is optically approximated as a homogeneous medium, thereby maximizing the overall transmittance and imaging clarity of the system and providing a pure optical substrate for the subsequent selective modulation of micron-level random optical microstructures.

[0053] Optionally, the transparent film has randomly distributed micron-scale random optical microstructures inside or on its surface. These micron-scale random optical microstructures are used to diffusely reflect incident projection light to form a projected image and allow ambient light to pass through in a straight line to present the background environment.

[0054] Micrometer-scale random optical microstructures are irregularly arranged micro-bumps, micro-pits, microlenses, and micro-prisms in a mixed distribution.

[0055] In this embodiment, by altering the local medium interface morphology, directional scattering, reflection, and refraction of incident light are achieved, thereby realizing optical functions such as imaging, viewing angle control, beam splitting, and moiré pattern elimination. Unlike regular array gratings and Fresnel lenses, it has no fixed repetition period and is specifically designed for bidirectional diffuse reflection imaging, while avoiding interference moiré patterns with PDLC strip gratings.

[0056] Micrometer-scale random optical microstructures are not simply surface roughening processes. As an optical scattering mechanism, for projection beams collimated from the projection unit or incident at a specific angle, the characteristic size of the micrometer-scale random optical microstructure is on the same order of magnitude as the wavelength of the projection light or satisfies specific scattering resonance conditions, thereby inducing strong Mie scattering or diffraction effects, efficiently diffusely reflecting the projection light to the target viewing area. However, for omnidirectional, incoherent background light from the surrounding environment, due to its wide incident angle distribution and complex spectral composition, most of the light does not satisfy the strong scattering conditions when interacting with the micrometer-scale random optical microstructure, or is mainly transmitted due to phase cancellation effects caused by random distribution, with only a very small portion being scattered. This selective response to the spatial coherence and incident angle of the light source is the microscopic key to achieving the coexistence of high-brightness projection imaging and high-transparency background perspective.

[0057] In practical implementation, the size range of micron-scale random optical microstructures is typically set between 1 and 50 micrometers, and the distribution density can be optimized and adjusted according to the wavelength of the projected light and the target viewing angle. For visible light projection, the average particle size of the micron-scale random optical microstructures is preferably between 5 and 20 micrometers. This ensures efficient scattering of the projected light while avoiding image graininess caused by excessively large structures or increased haze caused by Rayleigh scattering due to excessively small structures. Furthermore, the use of randomly distributed rather than periodically arranged micron-scale random optical microstructures has significant engineering value. Although periodic microstructures theoretically have controllable scattering efficiency, in practical applications they are prone to interference with the pixel array of the projected image, producing moiré patterns or rainbow patterns, and their scattered light field is often concentrated in a specific diffraction order, resulting in a narrow viewing angle. In contrast, the randomly distributed micron-scale random optical microstructures break the regularity of spatial frequency, fundamentally eliminating the conditions for the generation of moiré patterns. At the same time, its scattered light field exhibits a continuous Lambertian or Lambertian-like distribution, significantly widening the viewing angle of the three-dimensional display and ensuring that viewers on both sides can obtain a stereoscopic visual experience with uniform brightness and no artifacts from different positions.

[0058] Optionally, the dual-sided independent projection display system also includes: The first protective layer 4 is disposed on the side of the first electronically controlled dimming layer 2 that is away from the optical imaging layer 1.

[0059] The second protective layer 5 is disposed on the side of the second electronically controlled dimming layer 3 that is away from the optical imaging layer 1.

[0060] The optical imaging layer 1, the first electronically controlled dimming layer 2, the second electronically controlled dimming layer 3, the first protective layer 4, and the second protective layer 5 are all bonded together using an adhesive bonding process to form a five-layer composite structure.

[0061] In this embodiment, the selection of materials for the first protective layer 4 and the second protective layer 5 requires comprehensive consideration of optical transparency, mechanical strength, and processing adaptability. As a preferred embodiment, the first protective layer 4 and the second protective layer 5 can be made of tempered glass with high light transmittance. This glass has high surface hardness, wear resistance, and good flatness, which helps ensure the uniformity of the large-size screen display. For example, when applied to scenarios with high security requirements, such as commercial shop windows or exhibition displays, tempered glass with a thickness of 3mm to 6mm can be selected to provide sufficient rigid support and resistance to damage. For lightweight or irregularly shaped displays, the protective layer can also be made of optical-grade plastic substrates such as polycarbonate (PC), polymethyl methacrylate (PMMA), or cyclic olefin polymers (COP). These materials have lower density and better toughness, making them easy to hot-bend, but they usually require a surface-hardening coating to improve scratch resistance. Regardless of the material used, the thickness and material parameters of the first protective layer 4 and the second protective layer 5 must match the thermal expansion coefficient of the internal functional layer to avoid delamination or optical distortion due to stress mismatch during temperature cycling, thereby ensuring the optical performance stability and mechanical durability of the dual-sided independent projection display system during long-term operation.

[0062] If air gaps exist between adjacent layers of a double-sided imaging screen unit, the significant difference in refractive index between air and the materials of each functional layer will cause severe Fresnel reflection at the interface, resulting in a substantial decrease in the overall light transmittance of the system and stray light interference with imaging contrast. The lamination process utilizes optically transparent adhesive (OCA), polyvinyl butyral (PVB), or ethylene-vinyl acetate copolymer (EVA) as lamination materials, enabling full lamination. This effectively fills the microscopic gaps between layers, eliminates residual air, and makes each layer optically approximate a continuous medium. This not only significantly improves the transmittance of background light and the clarity of the projected image but also enhances the impact resistance and environmental aging resistance of the composite structure, preventing moisture or dust intrusion that could cause the electronically controlled dimming layer to fail.

[0063] In another embodiment, a dual-sided independent projection display method is provided, using the dual-sided independent projection display system as described above, including: Using time-division multiplexing, the first projection unit and the second projection unit alternately project images onto the optical imaging layer 1.

[0064] During the projection of the image, the light transmission states of the first electronically controlled dimming layer 2 and the second electronically controlled dimming layer 3 are switched synchronously to keep the light transmission states of the first electronically controlled dimming layer 2 and the second electronically controlled dimming layer 3 complementary, so as to achieve dynamic physical isolation of the double-sided light path and three-dimensional display.

[0065] In this embodiment, the first projection unit and the second projection unit alternately project images onto the optical imaging layer 1 using time-division multiplexing. During this process, the control unit divides the continuous time axis into a series of discrete display time slots and activates different projection channels within adjacent time slots. Alternating switching refers not only to simple on / off switching but also to frame-level scheduling of the projected content, ensuring that the first projection unit projects a left-eye or right-eye parallax image facing the first-side viewer, while the second projection unit projects the corresponding parallax image facing the second-side viewer. Through this time-division multiplexing strategy, the spatially overlapping double-sided display requirement is transformed into a temporally non-overlapping unidirectional display task, fundamentally avoiding the possibility of both image signals competing for the same optical channel at the same time.

[0066] During image projection, the light transmission states of the first electrically controlled dimming layer 2 and the second electrically controlled dimming layer 3 are switched synchronously to maintain complementarity, thereby achieving dynamic physical isolation of the double-sided optical path and three-dimensional display. Specifically, synchronous switching requires that the state flipping sequence of the first electrically controlled dimming layer 2 and the second electrically controlled dimming layer 3 be strictly aligned with the projection sequence of the first projection unit and the second projection unit. The control unit is typically equipped with a high-precision timing generator or synchronous trigger module. When the first projection unit starts outputting a valid image, it immediately drives the first electrically controlled dimming layer 2 to switch to the light transmission state and simultaneously drives the second electrically controlled dimming layer 3 to switch to the scattering state. This complementary relationship means that within any display time slot, the sum of the light transmittance of the two dimming layers logically approaches a constant (i.e., when one side is highly transparent, the other side must be highly impeded), thus constructing a virtual light shutter that moves dynamically over time along the optical path. This ensures the unidirectional conductivity of the optical path during any display period, thereby guaranteeing the independence of the double-sided display and the formation of stereoscopic vision at the methodological level.

[0067] Optionally, the method for synchronously switching the light transmission state of the first electrically controlled dimming layer 2 and the light transmission state of the second electrically controlled dimming layer 3 includes: In the first stage, the first projection unit is turned on and projects the first parallax image, the second projection unit is turned off, and the first electronically controlled dimming layer 2 is adjusted to be in a light-transmitting state and the second electronically controlled dimming layer 3 is adjusted to be in a scattering state.

[0068] In the second stage, the second projection unit is turned on and projects the second parallax image, the first projection unit is turned off, and the second electronically controlled dimming layer 3 is adjusted to be in a light-transmitting state and the first electronically controlled dimming layer 2 is adjusted to be in a scattering state.

[0069] The first and second phases are executed alternately in a loop at a switching frequency higher than the visual persistence frequency.

[0070] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A dual-sided independent projection display system, characterized in that, include: A dual-sided imaging screen unit, the dual-sided imaging screen unit includes an optical imaging layer (1), and a first electronically controlled dimming layer (2) and a second electronically controlled dimming layer (3) are respectively provided on both sides of the optical imaging layer (1). The dual-sided imaging screen unit is provided with a first projection unit and a second projection unit on both sides respectively. The control unit is communicatively connected to the first electronically controlled dimming layer (2), the second electronically controlled dimming layer (3), the first projection unit, and the second projection unit. The control unit is used to adjust the complementary alternating switching of the light transmission state of the first electronically controlled dimming layer (2) and the light transmission state of the second electronically controlled dimming layer (3), and to synchronously adjust the first projection unit and the second projection unit to project alternately, so as to realize the dynamic physical isolation of the double-sided light path and three-dimensional display.

2. The dual-sided independent projection display system as described in claim 1, characterized in that, Both the first electronically controlled dimming layer (2) and the second electronically controlled dimming layer (3) are provided with parallax barrier structures; In a scattering state, the parallax barrier structure forms a grating to block light from penetrating; In the light-transmitting state, the parallax barrier structure allows light to pass through.

3. The dual-sided independent projection display system as described in claim 1, characterized in that, The complementary alternating switching states include: During the first time period, the control unit adjusts the first electronically controlled dimming layer (2) to be in a light-transmitting state and simultaneously adjusts the second electronically controlled dimming layer (3) to be in a scattering state; During the second time period, the control unit adjusts the first electronically controlled dimming layer (2) to a scattering state and simultaneously adjusts the second electronically controlled dimming layer (3) to a light-transmitting state.

4. The dual-sided independent projection display system as described in claim 2, characterized in that, The materials of the first electro-dimming layer (2) and the second electro-dimming layer (3) include at least one of polymer-dispersed liquid crystal, microcapsule liquid crystal, or polymer network liquid crystal; The parallax barrier structure includes a strip electrode structure, which is prepared by nanolithography and is used to make the corresponding first electronically controlled dimming layer (2) or the second electronically controlled dimming layer (3) present a scattering state in the power-off state, and to make the corresponding first electronically controlled dimming layer (2) or the second electronically controlled dimming layer (3) present a light-transmitting state in the power-on state.

5. The dual-sided independent projection display system as described in claim 1, characterized in that, The optical imaging layer (1) is a transparent film with diffuse reflection properties and allows background light to pass through; The refractive index of the optical imaging layer (1) matches the refractive indices of the first electronically controlled dimming layer (2) and the second electronically controlled dimming layer (3).

6. The dual-sided independent projection display system as described in claim 5, characterized in that, The transparent film has randomly distributed micron-scale random optical microstructures inside or on its surface. These micron-scale random optical microstructures are used to diffusely reflect incident projection light to form a projection image and allow ambient light to pass through in a straight line to present the background environment.

7. The dual-sided independent projection display system as described in claim 6, characterized in that, The micron-level random optical microstructure is a mixture of irregularly arranged micro-bumps, micro-pits, microlenses, and micro-prisms.

8. The dual-sided independent projection display system as described in claim 1, characterized in that, Also includes: The first protective layer (4) is disposed on the side of the first electronically controlled dimming layer (2) away from the optical imaging layer (1); The second protective layer (5) is disposed on the side of the second electronically controlled dimming layer (3) away from the optical imaging layer (1); The optical imaging layer (1), the first electronically controlled dimming layer (2), the second electronically controlled dimming layer (3), the first protective layer (4), and the second protective layer (5) are all bonded together by an adhesive bonding process to form a five-layer composite structure.

9. A method for dual-sided independent projection display, using the dual-sided independent projection display system as described in any one of claims 1-8, characterized in that, include: Using time-division multiplexing, the first projection unit and the second projection unit are alternately switched to project images onto the optical imaging layer (1); During the projection of the image, the light transmission states of the first electronically controlled dimming layer (2) and the second electronically controlled dimming layer (3) are switched synchronously to make the light transmission states of the first electronically controlled dimming layer (2) and the second electronically controlled dimming layer (3) complementary, so as to achieve dynamic physical isolation of the double-sided light path and three-dimensional display.

10. The dual-sided independent projection display method as described in claim 9, characterized in that, The method for synchronously switching the light transmission state of the first electronically controlled dimming layer (2) and the light transmission state of the second electronically controlled dimming layer (3) includes: In the first stage, the first projection unit is turned on and projects the first parallax image, the second projection unit is turned off, and the first electronically controlled dimming layer (2) is adjusted to be in a light-transmitting state and the second electronically controlled dimming layer (3) is adjusted to be in a scattering state. In the second stage, the second projection unit is turned on and projects the second parallax image, the first projection unit is turned off, and the second electronically controlled dimming layer (3) is adjusted to be in a light-transmitting state and the first electronically controlled dimming layer (2) is in a scattering state. The first phase and the second phase are executed alternately and cyclically at a switching frequency higher than the visual persistence frequency.

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