Transparent display screen near-to-eye display system based on micro lens array

Abstract

The invention discloses a transparent display screen near-to-eye display system based on a micro lens array, which is characterized in that a micro lens is arranged on each display pixel of a transparent display screen to form a lens array, and light rays emitted by the display pixels are guided to infinity, so that the display content is presented as a far-focus image in the eyes of a user. By accurately controlling imaging of each pixel, the display image is successfully simulated into a far-focus image, meanwhile, the visibility of the environment in front of the transparent display is kept, and the method has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to a near-eye display system of a transparent display screen based on a micro lens array. Background Art

[0002] With the development of augmented reality technology, the demand for transparent display devices is increasing. Traditional near-eye display devices use eyepieces or other optical components to project images into the eye, which often limits the field of view and affects the visibility of the see-through environment. To provide a more natural viewing experience, a display system is needed that can simulate the displayed image as if it were infinitely far away while maintaining the foreground environment of the transparent display.

[0003] While existing technologies, such as optical waveguide displays or retinal scanning display systems, can achieve transparent displays and virtual far-focus displays, they face limitations in manufacturing costs, display quality, and transparency. Therefore, a new solution is urgently needed that can simultaneously meet the requirements of transparency, display quality, and comfortable near-eye vision. Summary of the Invention

[0004] The main purpose of the present invention is to provide a near-eye display system for a transparent display screen based on a microlens array. The system sets a microlens array in front of the display screen to project the image of each pixel to infinity while maintaining transparent transmission of ambient light, thereby realizing the combination of transparent display and far-focus imaging.

[0005] To achieve the above objectives, the present invention proposes a near-eye display system for a transparent display screen based on a microlens array, comprising:

[0006] Micro lens array: A micro lens is set on each display pixel of the transparent display to form a lens array, which guides the light emitted by the display pixel to infinity, so that the displayed content appears as a far-focus image in the user's eyes;

[0007] The display screen appears as a sphere with a specific curvature, the size of which depends on the set imaging distance and the spherical radius R value. Through refraction, light from different directions is projected into the human eye pupil, forming a multi-perspective image superposition and realizing stereoscopic vision.

[0008] Micro-lens gap design: By precisely designing the size and arrangement of the micro-lenses, sufficient gaps are ensured between each lens. These gaps allow ambient light to pass through, allowing users to see their surroundings through the screen without interference;

[0009] The microlens gap is designed to range from 1–20 μm.

[0010] Integration of display and environment: Through the micro-lens array, the light from each pixel of the display screen forms a virtual image at infinity after passing through the lens, while the gaps between the lenses allow ambient light to enter the eye, thereby retaining the transparency of the environmental vision while ensuring the clear presentation of the displayed content.

[0011] Electronic control and dynamic adjustment: The micro-lens array can dynamically adjust the focusing effect of the lens through an electronic control system to adapt to different display requirements and focal length adjustments, ensuring the clarity and comfort of the displayed image.

[0012] The present invention provides a near-eye display system for a transparent display screen based on a micro lens array, which has the following beneficial effects:

[0013] 1. Achieve far-focus imaging: The micro-lens array guides the light of each pixel to infinity, making the image present a natural virtual far-focus effect and reducing eye focusing fatigue.

[0014] 2. Maintaining environmental transparency: The lens gap design of the microlens array ensures that ambient light can pass through the display screen, maintaining transparency and allowing users to clearly observe the real environment.

[0015] 3. No additional optical elements: The present invention does not require additional optical elements, such as eyepieces or complex optical lenses, has a simple structure, and reduces the weight and volume of the equipment.

[0016] 4. Improve display resolution and comfort: Since each pixel is focused to a distance through a micro lens, high-definition virtual images can be achieved. At the same time, the user's eyes do not need to frequently adjust the focus, providing a more comfortable viewing experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0018] Figure 1 A schematic diagram of a near-eye display system structure of a transparent display screen based on a micro lens array provided by an embodiment of the present invention Figure 1 ;

[0019] Figure 2 A schematic diagram of a near-eye display system structure of a transparent display screen based on a micro lens array provided by an embodiment of the present invention Figure 2 ;

[0020] Figure 3A schematic diagram of light rays after display screen bending in a near-eye display system of a transparent display screen based on a microlens array provided by an embodiment of the present invention;

[0021] Figure 4 A schematic diagram of the principle of a near-eye display system for a transparent display screen based on a micro-lens array provided in an embodiment of the present invention;

[0022] Figure 5 A schematic diagram of the light path of a near-eye display system of a transparent display screen based on a microlens array provided in an embodiment of the present invention.

[0023] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0025] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0026] In addition, the descriptions of "first", "second", etc. in the present invention are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0027] In the embodiment of the present invention, referring to Figure 1 Hezhi Figure 5 A transparent display screen near-eye display system based on a micro lens array comprises:

[0028] A micro lens array is formed by setting a micro lens on each display pixel of the transparent display screen to guide the light emitted by the display pixel to infinity, so that the displayed content appears as a far-focus image in the user's eyes. Each micro lens covers a sub-pixel group on the display panel.

[0029] Each micro lens splits the pixel light from the display (such as Micro-LED or OLED) into multiple sub-beams to form a multi-perspective image, simulating the natural parallax of the human eye and solving the vergence accommodation conflict (VAC) problem of traditional 3D display. In this embodiment, the display screen is presented as a spherical surface with a specific curvature, the curvature of which depends on the set imaging distance and the spherical radius R value. Through refraction, light from different directions is projected to the human eye pupil, forming a multi-perspective image superposition and achieving stereoscopic vision. Its principle diagram is shown as follows: Figure 1 and Figure 2 The lens array focuses or diverges the incident light, and combined with the diffraction / refraction effect, adjusts the direction of the light path and expands the field of view (up to 100° or more).

[0030] In this embodiment, the microlens array consists of hundreds to thousands of microlenses (5–50 μm in diameter) arranged periodically. The material is polymer (SU-8) or quartz glass. The smaller the diameter, the higher the resolution. The lens diameter of this embodiment can be designed to be 5–30 μm. Metasurfaces are used to achieve subwavelength lenses, further reducing the size.

[0031] In this embodiment, an optical coupling layer is designed to fill a transparent medium (such as PDMS) between the display panel and the lens array to reduce interface reflection loss.

[0032] Lens gap design: By precisely designing the size and arrangement of the microlenses, sufficient gaps are ensured between each lens. These gaps allow ambient light to pass through, allowing users to see their surroundings through the screen without interference.

[0033] 1. Geometric optical perspective

[0034] ① Principle of Light Propagation: According to geometric optics, light propagates in straight lines in a uniform medium. In a microlens array, the microlenses refract and converge light. By precisely designing the size and arrangement of the microlenses, the direction of light propagation after passing through the lenses can be controlled. The gaps between the lenses provide a direct channel for ambient light to propagate. As long as the gaps are appropriately sized and evenly distributed, ambient light can pass through the screen in a relatively parallel state and enter the user's eyes, allowing the user to see their surroundings.

[0035] ② Relationship between viewing angle and gap: From the user's perspective, in order for the user to see the surrounding environment clearly and without obstruction, the gap needs to meet certain geometric conditions. Assuming that the user's eyes are located in a fixed position, the size and arrangement of the microlenses must be within the user's visual angle range. The viewing angle corresponding to the gap can allow sufficient ambient light to enter the eye while avoiding excessive obstruction of ambient light by the microlenses. For example, if the diameter of the microlenses is too large or the arrangement is too close, and the gap is too small, then the ambient light incident from certain angles may be blocked by the microlenses, resulting in dark areas or discontinuities in the surrounding environment seen by the user.

[0036] 2. Physical optics perspective

[0037] ① Diffraction and interference: When light passes through the gaps between microlenses, diffraction occurs. If the gap size is comparable to the wavelength of light, the diffraction effect will be more obvious. However, by reasonably designing the gap size, the intensity distribution of the diffracted light can be kept within a certain range, minimizing interference with the user's vision. At the same time, since diffracted light from different gaps may interfere with each other, the impact of interference fringes on the visual effect needs to be considered. By precisely designing the size and arrangement spacing of the gaps, the interference fringes can be placed in an area that is not easily perceived by the human eye, or the area where interference is enhanced can be matched with the main propagation direction of the ambient light, thereby ensuring the uniformity and stability of the ambient light transmission.

[0038] ② Polarization characteristics: Ambient light is typically natural light and contains various polarization directions. Microlenses and the materials between them may have different effects on light with different polarization directions. For example, certain polymer materials may absorb or scatter light with a certain polarization direction. During design, it is necessary to consider the polarization characteristics of the material and try to choose materials that have a minimal effect on the polarization of ambient light. Alternatively, by optimizing the structure of the lens and gap, light with different polarization directions can be transmitted more evenly to ensure that the color and contrast of the surrounding environment seen by the user are not significantly changed due to polarization effects.

[0039] 3. Visual Perception Angle

[0040] ① Resolution and Clearance: The human eye has a certain resolution. The resolution of the surrounding environment seen through the screen should not be significantly affected by the design of the lens clearance. The size and distribution of the clearance should ensure that the ambient light passing through can provide sufficient detail information, allowing users to clearly distinguish objects and scenes in the surrounding environment. If the clearance is too small or unevenly distributed, the information of the ambient light passing through may be lost, making the surrounding environment appear blurry or grainy.

[0041] ② Contrast and Brightness: The design of the lens gap also needs to consider the contrast and brightness balance between ambient light and the light emitted by the display itself. The gap allows ambient light to pass through, and its brightness needs to be coordinated with the brightness of the image displayed on the display to ensure that users can comfortably see their surroundings while viewing the content on the display. If the ambient light is too strong, it may obscure the content on the display; if the ambient light is too weak, the user will feel that the surrounding environment is dark and unnatural. By properly designing the gap size and the optical properties of the microlens, the ratio of ambient light to display light can be adjusted to achieve the appropriate contrast and brightness, thereby improving the user's visual experience.

[0042] In this embodiment, the lens gap is designed to be in the range of 1–20 μm (typically 5–10% of the lens diameter) to avoid light energy waste and prevent crosstalk.

[0043] 1. Theoretical analysis:

[0044] ① Optical performance: The working principle of the microlens is based on the refraction and focusing of light. From the perspective of geometric optics, light follows the law of refraction when passing through the lens. When the lens gap is too small, for example, less than 1μm, it will cause significant light interference and diffraction. According to Fresnel diffraction theory, under tiny gaps, light will interfere with each other during propagation, resulting in disordered light intensity distribution, and the expected function of the lens to accurately focus light cannot be achieved, and the image quality will be seriously reduced. When the gap is too large, exceeding 20μm, the number of lenses per unit area is reduced, and the ability to control light is weakened. In the near-eye display system of a transparent display screen based on a microlens array, it is difficult to achieve precise guidance of light from different perspectives, and it is impossible to form a clear and stable multi-perspective image superposition, and it is difficult to achieve an ideal stereoscopic visual effect.

[0045] ② Light energy transmission: In this display system, sufficient light energy must be transmitted from the display screen to the human eye to ensure good image brightness and contrast. If the gap is too small, light will lose excessive energy due to multiple scattering and absorption when passing through the lens gap. According to the Lambert-Beer law, when light propagates in a medium, its intensity decreases with the propagation distance and the properties of the medium. A gap that is too small is equivalent to increasing the effective path length of light propagation, resulting in increased light energy loss. Conversely, a gap that is too large will reduce the lens's efficiency in collecting and transmitting light, resulting in insufficient light energy reaching the human eye, affecting the clarity and visibility of the displayed image.

[0046] ③ Pixel matching: The pixel layout of the display screen and the microlens array need to work together. The light emitted by the display screen pixels must be accurately captured and modulated by the microlenses. The pixel size of a typical display screen is on the order of several microns to tens of microns. When the microlens gap is in the range of 1-20μm, it can better match the pixel size of common displays. For example, for a display screen with a pixel size of 5-10μm, this gap range allows the light emitted by each pixel to be received and processed by the appropriate number of microlenses, avoiding cross-interference of light or insufficient light utilization due to an insufficient number of lenses, thereby ensuring image resolution and detail.

[0047] ④ Space limitations and integration: In near-eye display systems, device size and integration are crucial. As a key component of the system, the gap design of the microlens array must take into account the overall spatial layout. If the gap is too small, the manufacturing process becomes more difficult and the cost rises significantly. It is also difficult to achieve large-scale microlens integration within a limited space. If the gap is too large, it will occupy too much space, hindering the miniaturization and lightweight design of the system, and failing to meet the portability and comfort requirements of near-eye display devices.

[0048] 2. Experimental data support:

[0049] ① Imaging clarity experiment: A near-eye display system model with different microlens gaps (0.5μm, 1μm, 5μm, 10μm, 15μm, 20μm, and 25μm) was constructed. A standard resolution test chart was used as the display content, and the imaging clarity was evaluated through subjective evaluation by the human eye and objective measurement using image analysis software. The experimental results show that when the gap is 0.5μm, the image edges are blurred and the resolution is extremely low due to severe interference and diffraction of light. When the gap is 1μm, the imaging quality improves, but obvious interference fringes still exist. When the gap is between 5-20μm, the image clarity is high and relatively stable, with clear lines and a resolution close to the inherent resolution of the display. However, when the gap is 25μm, the image clarity is significantly reduced, and details are lost. This is because the lens's ability to control light is insufficient.

[0050] ② Light energy transmission efficiency experiment: In the experimental setup, an optical power meter was used to measure the initial light power emitted by the display screen and the light power reaching the human eye after passing through microlens arrays with different gaps. The light energy transmission efficiency (the ratio of the light power after transmission to the initial light power) was calculated. Experimental data showed that when the gap was 0.5μm, the light energy transmission efficiency was only 20%; when the gap was 1μm, the efficiency increased to 30%; when the gap was in the range of 5-15μm, the light energy transmission efficiency stabilized between 60% and 70%; when the gap was 20μm, the efficiency was 55%; and when the gap was 25μm, the efficiency dropped to 40%. This shows that in the range of 1-20μm, the light energy transmission efficiency is relatively high, which can meet the image brightness requirements of near-eye display systems.

[0051] ③ Stereoscopic visual effect experiment: Invite multiple observers to experience the stereoscopic visual effect of the near-eye display system under different gap settings. By wearing the system, the observer observes the 3D test image with depth information and subjectively scores the stereoscopic effect (1-10 points, 10 points is the best). At the same time, the eye tracking equipment is used to measure the convergence and divergence of the observer's eyes to objectively evaluate the comfort of stereoscopic vision. The experimental results show that when the gap is 1μm, the observers generally report that the stereoscopic effect is not obvious, with a score of 3-4 points, and the eye tracking data shows that the eyes have difficulty adjusting; when the gap is 5-20μm, the stereoscopic effect is obvious, with a score of 7-9 points, and the eye tracking data shows that the eye adjustment is more natural and comfortable; when the gap is 25μm, the stereoscopic effect is blurred, with a score of 5-6 points, and the eyes are prone to fatigue.

[0052] ④ Ambient Light Interference Experiment: The display performance of near-eye display systems using microlens arrays with different gaps was tested under varying ambient light intensities (low light, normal indoor light, and strong light). By comparing image contrast and visibility under ambient light interference, it was found that when the gap is within the 1-20μm range, the system has a strong ability to resist ambient light interference, and image contrast and visibility are less affected. However, when the gap is too small or too large, ambient light easily scatters and reflects in the lens gap, seriously interfering with the displayed image and reducing image contrast and visibility.

[0053] In summary, based on comprehensive theoretical analysis and experimental data, the design range of the microlens gap is determined to be 1-20μm, which can achieve a good balance in ensuring optical performance, light energy transmission, pixel matching, and spatial integration, thereby achieving the optimal performance of the transparent display near-eye display system based on the microlens array.

[0054] Integration of display and environment: Through a micro-lens array, light from each pixel on the display forms a virtual image at infinity after passing through the lens. The gaps between the lenses allow ambient light to enter the eye, preserving the transparency of the surrounding visual environment while ensuring the clarity of the displayed content. The control circuit drives the pixel-level signals of the display panel, and some systems can integrate eye-tracking sensors.

[0055] Electronic control and dynamic adjustment: The micro lens array dynamically adjusts the focusing effect of the lens through the electronic control system to adapt to different display requirements and focal length adjustment, ensuring the clarity and comfort of the displayed image. The focal length (f) of the lens is determined by the curvature radius. n is the material's refractive index, designed to be 10-20μm. Liquid crystal materials are combined to create an MLA with adjustable focal length, adapting to users with different diopters.

[0056] In this embodiment, referring to Figure 3 ,The light regulation process of the micro-lens array can be divided into three stages: pixel light emission → lens modulation → human eye imaging.

[0057] 1. Light emission from the display panel

[0058] Pixel structure:

[0059] Each pixel of a display panel (such as a Micro-LED / OLED panel, which provides a high-brightness, high-contrast image source) is composed of multiple sub-pixels (RGB), each of which emits light in a specific direction (with a divergence angle of approximately ±15°).

[0060] The display's substrate material is made of glass or flexible polymer (such as PET) to support the lens array structure.

[0061] The correspondence between pixels and lenses:

[0062] Each microlens covers a pixel group (e.g. 3×3 or 5×5 pixels), ensuring that each lens receives light from multiple pixels.

[0063] 2. Light modulation by microlenses

[0064] Focus and Divergence:

[0065] The microlens focuses or diverges the incident light and adjusts the propagation direction of the light.

[0066] Focusing lens: converts divergent light into parallel light (collimation) to reduce cross-interference of light.

[0067] Diverging lens (partial design): expands the field of view, but the spread of the light spot needs to be controlled.

[0068] Multi-perspective separation:

[0069] Each lens divides the light of the same pixel into multiple sub-beams at different angles (such as 9 directions) to form a multi-viewpoint image.

[0070] 3. Human Eye Reception and Imaging

[0071] Pupil captures the light field:

[0072] The human eye pupil receives light from multiple lenses at the same time, and the light from each perspective is superimposed on the retina to form a 3D image with depth information.

[0073] Dynamic Parallax:

[0074] When the user moves their head, light from different perspectives switches in real time, enhancing the sense of immersion.

[0075] The light path of this embodiment is as follows Figure 5 As shown, ● represents the micro lens (diameter D, gap G), θ1, θ2, θ3: the light emission angles at different viewing angles (determined by the lens curvature and arrangement), → represents the direction of light propagation.

[0076] Characteristics and design of optical path:

[0077] 1. Light angle control

[0078] The formula for the angle of incidence is:

[0079] The ray angle θ is determined by the lens focal length f and the pixel position x: For example, if the pixel is 10 μm away from the optical axis and the focal length is 50 μm, then θ ≈ 11.3°.

[0080] 2. Light field superposition and crosstalk suppression

[0081] Light field superposition:

[0082] The light from adjacent lenses partially overlaps at the pupil, forming a continuous field of view (such as θ1, θ2, and θ3 in the figure).

[0083] Crosstalk suppression:

[0084] By optimizing the gap GG and lens filling factor, it is ensured that the light from adjacent lenses does not overlap before reaching the human eye.

[0085] This invention provides a technical solution for achieving transparent and near-eye display through a microlens array. By precisely controlling the imaging of each pixel, the displayed image is successfully simulated as a far-focus image while maintaining visibility of the surroundings in front of the transparent display. This solution has broad application prospects and is suitable for devices that require a transparent display while simultaneously presenting virtual information, such as smart glasses and AR headsets. It allows users to see both displayed content and real-world objects without compromising transparency.

[0086] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A transparent display screen near-eye display system based on a micro lens array, characterized in that: include: A micro lens array is formed by placing a micro lens on each display pixel of the transparent display screen to guide the light emitted by the display pixel to infinity, so that the displayed content appears as a far-focus image to the user's eyes; The microlens gap is designed to range from 1–20 μm; The display screen appears as a sphere with a specific curvature. The curvature depends on the set imaging distance and the spherical radius R. Through refraction, light from different directions is projected into the human eye pupil, forming a multi-view image superposition and achieving stereoscopic vision. The micro-lens array dynamically adjusts the focusing effect of the lens through an electronic control system to adapt to different display requirements and focal length adjustments, ensuring the clarity and comfort of the displayed image.

2. The transparent display screen near-eye display system based on a micro lens array according to claim 1, characterized in that: The micro lens array is composed of hundreds to thousands of micro lenses (diameter 5-50 μm) arranged periodically, and the material is polymer (SU-8) or quartz glass.

3. The transparent display screen near-eye display system based on a micro lens array according to claim 1, characterized in that: Also includes: Optical coupling layer: A transparent medium filled between the display panel and the lens array to reduce interface reflection loss.

4. The transparent display screen near-eye display system based on a micro lens array according to claim 1, wherein: The substrate material of the display screen is glass or flexible polymer, which supports the lens array structure.

5. The transparent display screen near-eye display system based on a micro lens array according to claim 1, characterized in that: The display source of the display screen is a Micro-LED / OLED panel, which provides a high-brightness and high-contrast image source.

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