Projection systems and optical display devices

Abstract

The present application provides a projection system and an optical display device; the projection system includes a projection lens, a color combining prism and an image source, the projection lens includes first to fourth lenses, the curvature of the lenses and the focal length of the projection lens satisfy ‑0.1<(K1+K2) / f<0.1, 0.2<(K3+K4) / f<0.35, ‑0.1<(K5+K6) / f<0 and ‑0.3<(K7+K8) / f<‑0.1; K1 and K2 are the curvatures of the surface of the first lens away from the image source and the curvature of the surface close to the image source, respectively; K3 and K4 are the curvatures of the surface of the second lens away from the image source and the curvature of the surface close to the image source, respectively; K5 and K6 are the curvatures of the surface of the third lens away from the image source and the curvature of the surface close to the image source, respectively; K7 and K8 are the curvatures of the surface of the fourth lens away from the image source and the curvature of the surface close to the image source, respectively; f is the focal length of the projection lens.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optical imaging technology. More specifically, the embodiments of the present application relate to a light projection system and an optical display device. Background Art

[0002] With the rise of the metaverse concept, AR optical display devices, such as AR smart glasses, are attracting significant attention as they serve as crucial hardware enablers for the metaverse experience. Miniaturization and lightweighting of AR smart glasses are key to their widespread adoption by consumers. As the core optical component of AR smart glasses, miniaturization of the AR optical engine (including the projection system) is particularly crucial. Currently, AR optical engines based on μLED technology are considered the ultimate choice for AR optical engines due to their simple design, compact size, and high display performance potential. However, because μLED technology currently only enables mass production of monochrome panels, the industry generally adopts the x-cube color combination scheme to combine red, green, and blue μLED panels for imaging, creating compact color AR optical engines to meet consumer demand for color imaging. Despite this, current color μLED optical engines using the xcube color combination scheme remain relatively large, limiting the further miniaturization and lightweighting of AR optical display devices, such as AR smart glasses. Summary of the Invention

[0003] The purpose of this application is to provide a new technical solution for a projection system and an optical display device.

[0004] In a first aspect, the present application provides a projection system. The projection system includes a projection lens, a color combining prism, and an image source arranged in sequence, wherein the projection lens includes a first lens, a second lens, a third lens, and a fourth lens arranged in sequence along the same optical axis;

[0005] The curvatures of the first to fourth lenses and the focal length of the projection lens satisfy:

[0006] -0.1<(K1+K2) / f<0.1;

[0007] 0.2<(K3+K4) / f<0.35;

[0008] -0.1<(K5+K6) / f<0;

[0009] -0.3<(K7+K8) / f<-0.1;

[0010] Among them, K1 is the curvature of the surface of the first lens away from the image source, K2 is the curvature of the surface of the first lens close to the image source; K3 is the curvature of the surface of the second lens away from the image source, K4 is the curvature of the surface of the second lens close to the image source; K5 is the curvature of the surface of the third lens away from the image source, K6 is the curvature of the surface of the third lens close to the image source; K7 is the curvature of the surface of the fourth lens away from the image source, K8 is the curvature of the surface of the fourth lens close to the image source; f is the focal length of the projection lens.

[0011] Optionally, the projection lens has positive optical power.

[0012] Optionally, the first lens has positive optical power, the second lens has negative optical power, the third lens has positive optical power, and the fourth lens has negative optical power.

[0013] Optionally, the focal lengths of the first lens to the fourth lens and the focal length of the projection lens satisfy:

[0014] 0.75<f1 / f<0.9;

[0015] -0.9<f2 / f<-0.65;

[0016] 0.6<f3 / f<0.7;

[0017] -3.5<f4 / f<-1.6;

[0018] Among them, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, and f is the focal length of the projection lens.

[0019] Optionally, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: 0.9<|f1 / f2|<1.2; the focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: 0.19<|f3 / f4|<1.

[0020] Optionally, the Abbe numbers of the first lens and the second lens satisfy: 1.85<V d1 / V d2 <2.3; where V d1 、V d2 are the Abbe numbers of the first lens and the second lens respectively;

[0021] The Abbe numbers of the third lens and the fourth lens satisfy: 2.4<V d3 / V d4 <2.7; among which, V d3 and Vd4 are the Abbe numbers of the third lens and the fourth lens respectively.

[0022] Optionally, the first lens, the second lens, the third lens and the fourth lens are aspherical lenses.

[0023] Optionally, the first lens is located on a side away from the image source;

[0024] The projection system further comprises a front aperture, wherein the front aperture is located on a side of the first lens (11) away from the image source;

[0025] The diameter of the front aperture is D, 2mm<D<5mm, and the diameter of the front aperture is used to match the entrance pupil diameter of an external optical waveguide component.

[0026] Optionally, the exit pupil distance of the projection system is L, 0<L<3mm, and the exit pupil distance is the distance from the surface of the first lens away from the image source to the front aperture.

[0027] Optionally, the image source is an RGBμLED image source, the pixel size of the image source is panel pixel, 2μm<panel pixel<5μm, the image height is H, and 0mm<H≤6mm.

[0028] In a second aspect, the present application provides an optical display device. The optical display device includes:

[0029] The projection system according to the first aspect; and

[0030] The optical waveguide device has a front aperture of the projection system whose diameter matches the entrance pupil diameter of the optical waveguide device.

[0031] The beneficial effects of this application are:

[0032] The projection system provided in the embodiment of the present application is a miniaturized color μLED projection system with a compact structure and excellent imaging quality, which can be applied to AR optical machines. Specifically, by constraining the proportional relationship between the curvature of each surface of the first lens to the fourth lens and the focal length of the projection lens, the surface distribution of each lens is made more uniform, and the aberration correction capability of each lens is equivalent. This not only improves the lens tolerance sensitivity of the optical machine design, but also makes the projection system more tolerant to lens manufacturing errors, thereby simplifying the assembly production process and improving production efficiency; and, under the condition of meeting the above-mentioned curvature constraints, the curvature design of the lens can be optimized, which helps to reduce the thickness of each lens, thereby achieving the miniaturization of the projection system while ensuring optical performance. This is crucial for portable optical display devices such as AR glasses, which can significantly reduce the weight of the device and improve user wearing comfort.

[0033] In summary, the projection system of the present application achieves the lightweight and miniaturization of the projection system and improves the imaging quality by precisely controlling the proportional relationship between the curvature of each lens and the focal length of the projection lens, providing a high-performance and reliable optical solution for portable display devices such as AR glasses.

[0034] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0036] Figure 1 This is one of the structural diagrams of the projection system provided in an embodiment of the present application;

[0037] Figure 2 This is a second structural diagram of the projection system provided in an embodiment of the present application;

[0038] Figure 3 The optical architecture and light path diagram of the projection system provided in Example 1 of the present application;

[0039] Figure 4 for Figure 3 Provided optical distortion diagram of the projection system;

[0040] Figure 5 for Figure 3 Modulation transfer function plots of the provided projection systems;

[0041] Figure 6 for Figure 3 Provided through-focus MTF graph of the projection system;

[0042] Figure 7 for Figure 3 Relative illumination diagram of the provided projection system;

[0043] Figure 8 The optical architecture and light path diagram of the projection system provided in Example 2 of the present application;

[0044] Figure 9 for Figure 8 Provided optical distortion diagram of the projection system;

[0045] Figure 10 for Figure 8 Modulation transfer function plots of the provided projection systems;

[0046] Figure 11 for Figure 8Provided through-focus MTF graph of the projection system;

[0047] Figure 12 for Figure 8 Relative illumination diagrams of the provided projection systems.

[0048] Description of reference numerals:

[0049] 1. Projection lens; 11. First lens; 12. Second lens; 13. Third lens; 14. Fourth lens; 2. Color combining prism; 3. Image source; 301. Red light source; 302. Green light source; 303. Blue light source; 01. Aperture. DETAILED DESCRIPTION

[0050] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0051] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0052] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0053] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0054] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0055] The projection system and optical display device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0056] According to one embodiment of the present application, a projection system is provided. Figure 1 and Figure 2 The projection system includes a projection lens 1, a color combining prism 2, and an image source 3 arranged in sequence; wherein the projection lens 1 includes a first lens 11, a second lens 12, a third lens 13, and a fourth lens 14 arranged in sequence along the same optical axis, and the curvatures of the first lens 11 to the fourth lens 14 and the focal length of the projection lens 1 satisfy:

[0057] -0.1<(K1+K2) / f<0.1;

[0058] 0.2<(K3+K4) / f<0.35;

[0059] -0.1<(K5+K6) / f<0;

[0060] -0.3<(K7+K8) / f<-0.1;

[0061] Among them, K1 is the curvature of the surface of the first lens 11 away from the image source 3, K2 is the curvature of the surface of the first lens 11 close to the image source 3; K3 is the curvature of the surface of the second lens 12 away from the image source 3, K4 is the curvature of the surface of the second lens 12 close to the image source 3; K5 is the curvature of the surface of the third lens 13 away from the image source 3, K6 is the curvature of the surface of the third lens 13 close to the image source 3; K7 is the curvature of the surface of the fourth lens 14 away from the image source 3, K8 is the curvature of the surface of the fourth lens 14 close to the image source 3; f is the focal length of the projection lens 1.

[0062] The projection system provided in the embodiments of the present application is designed for a color μLED AR light machine.

[0063] The projection system provided in the embodiment of the present application mainly includes three key optical components: a projection lens 1, a color combining prism 2, and an image source 3. The three optical components are described in detail below.

[0064] The projection lens 1 in the embodiment of the present application includes four lenses arranged in sequence along the same optical axis: a first lens 11, a second lens 12, a third lens 13, and a fourth lens 14. The entire projection lens utilizes four lenses, which share the responsibility of distributing optical power. This ensures that the lens surface remains conventional while still meeting the projection lens's specifications. This reduces the difficulty of lens manufacturing, facilitates the design of lens barrels and AR optical modules, and facilitates mass production.

[0065] The color combining prism 2 (x-cube color combining prism) in the embodiment of the present application is used to combine the red, green, and blue (R / G / B) light from the image source 3 to generate a full-color image.

[0066] Image source 3 in the embodiment of this application: Figure 1, it includes three monochrome μLED image sources: a red light source 301, a green light source 302, and a blue light source 303, which emit red, green, and blue light respectively. These three colors of light are combined by the color combining prism 2. The color combining prism 2 is able to combine red, green, and blue light from different image sources to form a full-color image through its special optical design. In this process, the color combining prism 2 ensures the correct alignment of the light and the uniformity of the color mixing, thereby ensuring the color accuracy and clarity of the final output image. The light after color combining by the color combining prism 2 is then focused and amplified by the projection lens 1, and finally projected onto the target area to achieve a high-quality color display effect.

[0067] In order to simplify and visualize the optical design and evaluation process, the color combining prism 2 is idealized as a cubic prism model in the embodiment of the present application. At the same time, the three independent red light sources 301 (R), green light sources 302 (G), and blue light sources 303 (B) in reality are equivalently integrated into a virtual RGBμLED image source. Figure 2 Image source 3 is shown in Figure 3. This equivalent processing not only keeps the core elements of optical structure design unchanged, but also significantly reduces the complexity of optical structure design, making the optical design evaluation process more efficient and intuitive.

[0068] The projection system provided in the embodiments of the present application includes a projection lens 1 comprising four lenses. Through the specially designed projection lens 1, and in particular the control of the proportional relationship between the curvature of each surface of the first lens 11 to the fourth lens 14 and the focal length f of the projection lens 1, the design and optical performance of each lens are optimized.

[0069] The constraints in the embodiments of this application are as follows:

[0070] The relationship between the curvature of the first lens 11 and the focal length f of the projection lens 1 is: -0.1<(K1+K2) / f<0.1, the relationship between the curvature of the second lens 12 and the focal length f of the projection lens 1 is: 0.2<(K3+K4) / f<0.35, the relationship between the curvature of the third lens 13 and the focal length f of the projection lens 1 is: -0.1<(K5+K6) / f<0, and the relationship between the curvature of the fourth lens 14 and the focal length f of the projection lens 1 is: -0.3<(K7+K8) / f<-0.1.

[0071] By setting the curvature of each lens and the focal length of the entire projection lens 1, these constraints ensure that the surface profiles of each lens are evenly distributed and that each lens has comparable aberration correction capabilities. This helps improve the lens tolerance sensitivity of the projection lens 1 design, thereby better maintaining the accuracy and performance of the entire projection system design during the production and assembly process.

[0072] According to this example of the present application, these constraints also facilitate lens processing, because by optimizing the curvature distribution, the thickness of each lens can be reduced while still meeting the design requirements. This is conducive to the miniaturization of projection systems and even AR optical machines, because thinner lenses can take up less space.

[0073] By properly designing the relationship between the lens curvature and the focal length f of the entire projection lens 1, image quality can be further improved. For example, these constraints help reduce optical distortion, improve the MTF (Modulation Transfer Function) value, and increase the MTF value within the defocus range. Improving these parameters directly enhances the image quality of the projection system, enabling it to provide clearer images.

[0074] The projection system provided in the embodiments of the present application is a compact, miniaturized color μLED projection system with excellent imaging quality, which can be applied to AR optical machines. Specifically, by constraining the proportional relationship between the curvature of each surface of the first lens 11 to the fourth lens 14 and the focal length f of the projection lens, the surface distribution of each lens is made more uniform, and the aberration correction capability of each lens is equivalent. This not only improves the lens tolerance sensitivity of the AR optical machine design, but also makes the projection system more tolerant to lens manufacturing errors, thereby simplifying the assembly production process and improving production efficiency. Moreover, under the condition of meeting the above-mentioned curvature constraints, the curvature design of the lens can be optimized, which helps to reduce the thickness of each lens, thereby achieving the miniaturization of the projection system while ensuring optical performance. This is crucial for portable optical display devices such as AR glasses, which can significantly reduce the weight of the device and improve user wearing comfort.

[0075] In summary, the projection system of the present application achieves the lightweight and miniaturization of the projection system and improves the imaging quality by precisely controlling the proportional relationship between the curvature of each lens and the focal length of the projection lens, providing a high-performance and reliable optical solution for portable display devices such as AR glasses.

[0076] In some examples of the present application, the projection lens 1 has positive optical power.

[0077] First, as one of the core optical components of an AR system, the optical power of the projection lens 1 directly impacts the imaging quality and overall performance of the AR system. A positive optical power design means that the projection lens 1 has a converging effect on light, which helps accurately focus light from the image source 3 onto the waveguide or the observer's eye, achieving clear imaging.

[0078] Secondly, the design of a positive-power projection lens 1 facilitates compactness and lightweighting. In AR optical machines, miniaturization and lightweighting are crucial design goals, as they directly impact the wearing comfort and portability of AR glasses. A positive-power projection lens can reduce the size and weight of the projection lens 1 while maintaining good imaging performance by optimizing its structure and parameters, such as radius of curvature, thickness, and material.

[0079] Furthermore, the design of a positive-power projection lens 1 also helps improve the aberration correction capabilities of AR optical machines. Aberration is a common problem in optical systems that can lead to reduced image quality. A positive-power projection lens can effectively correct various aberrations, such as spherical aberration, coma, and field curvature, through a reasonable distribution of optical power and lens combination, thereby improving the imaging quality and resolution of AR optical machines.

[0080] In summary, the positive-power design of the projection lens 1 not only helps achieve clear imaging for AR optical machines, but also facilitates compactness and lightweighting of the projection lens, and improves the aberration correction capability of AR optical machines. These technical effects have jointly promoted the development of AR optical machine technology and provided strong support for the miniaturization, lightweighting, and high-performance of AR glasses.

[0081] In some examples of the present application, the first lens 11 has positive optical power, the second lens 12 has negative optical power, the third lens 13 has positive optical power, and the fourth lens 14 has negative optical power.

[0082] In this example of the present application, the optical architecture design of the projection lens adopts four lenses, which can be seen in Figure 2 The first lens 11, second lens 12, third lens 13, and fourth lens 14 are shown in FIG. These lenses are arranged sequentially along the optical path. Specifically, the optical powers of these four lenses are carefully configured: the first lens 11 has positive optical power, the second lens 12 has negative optical power, the third lens 13 has positive optical power, and the fourth lens 14 has negative optical power.

[0083] In this example of the present application, the distribution of the focal length of the first lens 11 to the fourth lens 14 can at least bring the following technical effects:

[0084] (1) Optimizing aberration correction: By alternating between positive and negative optical powers, the projection lens can effectively reduce geometric aberrations such as spherical aberration and coma, thereby improving image quality. The combination of positive and negative lenses allows each lens to perform aberration correction to a certain extent, thereby improving the optical performance of the entire projection lens.

[0085] (2) Achieving a compact structure: The design uses a four-lens combination, and each lens is carefully calculated and optimized, allowing the entire projection lens to achieve a more compact structure while maintaining high image quality. This is crucial for the miniaturization of AR optical machines and will help promote the popularization and application of AR glasses.

[0086] (3) Improved lens tolerance sensitivity: Since each lens is responsible for appropriate light correction, the tolerance sensitivity of the projection lens is improved. During the production process, even if there are certain manufacturing errors in the lens, they can be compensated through subsequent assembly and adjustment, thus ensuring that the overall performance of the entire projection lens is not affected.

[0087] Furthermore, the combination of positive and negative lenses helps balance chromatic aberration across the entire projection lens. Light of different wavelengths experiences varying degrees of refraction and dispersion when passing through a lens. The combination of positive and negative lenses can partially offset this chromatic aberration, allowing the projection lens to maintain good image quality across a wider wavelength range. This is particularly important for color AR cameras, as color imaging requires the simultaneous processing of three different wavelengths of light: red, green, and blue.

[0088] In some examples of the present application, the focal lengths of the first lens 11 to the fourth lens 14 and the focal length f of the projection lens 1 satisfy:

[0089] 0.75<f1 / f<0.9;

[0090] -0.9<f2 / f<-0.65;

[0091] 0.6<f3 / f<0.7;

[0092] -3.5<f4 / f<-1.6;

[0093] Wherein, f1 is the focal length of the first lens 11 , f2 is the focal length of the second lens 12 , f3 is the focal length of the third lens 13 , f4 is the focal length of the fourth lens 14 , and f is the focal length of the projection lens 1 .

[0094] In this example of the present application, constraints are set regarding the proportional relationship between the focal lengths of the first lens 11 to the fourth lens 14 and the focal length f of the projection lens 1 , and these constraints are as follows:

[0095] The ratio of the focal length f1 of the first lens 11 to the focal length f of the projection lens 1 is between 0.75 and 0.9;

[0096] The ratio of the focal length f2 of the second lens 12 to the focal length f of the projection lens 1 is between -0.9 and -0.65;

[0097] The ratio of the focal length f3 of the third lens 13 to the focal length f of the projection lens 1 is between 0.6 and 0.7;

[0098] The ratio of the focal length f4 of the fourth lens 14 to the focal length f of the projection lens 1 is between -3.5 and -1.6.

[0099] This focal length ratio design ensures that each lens plays a unique role in light distribution and correction. By precisely controlling the focal length and focal length ratio of each lens, light can be more effectively balanced and distributed, ensuring that light is appropriately converged or diverged after passing through each lens, thereby reducing aberrations and improving image quality.

[0100] The constraints in this example can improve image quality. Specifically, because each lens performs appropriate light correction and the focal length ratio is set appropriately, the entire projection lens can maintain high image quality over a wider field of view and longer distances. This is crucial for AR optical display devices such as AR glasses, which need to provide users with clear image displays.

[0101] Furthermore, while maintaining image quality, by properly setting the focal length ratio of each lens, the number of lenses in the projection lens and their thickness can be controlled to a certain extent, thereby reducing the overall size and weight of the AR optical machine. This is of great significance for promoting the miniaturization and lightweighting of AR glasses, for example.

[0102] In some examples of the present application, the focal lengths of the first lens 11 to the fourth lens 14 further satisfy the following conditions: 0.9<|f1 / f2|<1.2 and 0.19<|f3 / f4|<1.

[0103] The projection lens of the present application, while satisfying the proportional relationship between the focal lengths of the first lens 11 to the fourth lens 14 and the focal length of the projection lens 1 mentioned in the above example, also sets an additional proportional relationship constraint between the focal lengths of the first lens 11 to the fourth lens 14, namely, the absolute value ratio of the focal lengths of the first lens 11 and the second lens 12, |f1 / f2|, is between 0.9 and 1.2, and the absolute value ratio of the focal lengths of the third lens 13 and the fourth lens 14, |f3 / f4|, is between 0.19 and 1. According to this example of the present application, at least the following technical effects can be achieved:

[0104] (1) Enhanced aberration correction capability: By constraining the absolute focal length ratio of the first lens 11 to the second lens 12 to be between 0.9 and 1.2, the two lenses can be more coordinated in aberration correction. Similarly, by constraining the absolute focal length ratio of the third lens 13 to the fourth lens 14 to be between 0.19 and 1, they can also be used to jointly correct aberrations, thereby improving the imaging quality of the entire projection lens.

[0105] (2) Improved optical stability: The focal length ratio design in this example helps enhance the optical stability of the entire projection lens. For example, when the external environment (such as temperature, humidity, etc.) changes, the focal length ratio relationship between adjacent lenses can remain relatively stable, thereby ensuring that the projection lens can provide high-quality imaging under various conditions.

[0106] (3) Optimizing Light Distribution: By controlling the focal length ratio between the first lens 11 and the second lens 12, and the focal length ratio between the third lens 13 and the fourth lens 14, the distribution of incident projection light can be further optimized. This helps ensure that light is appropriately converged or diverged after passing through each lens, thereby improving light utilization and imaging quality.

[0107] In a specific embodiment of the present application, the focal lengths of the first lens 11 to the fourth lens 14 and the focal length of the projection lens 1 satisfy:

[0108] 0.75<f1 / f<0.9;

[0109] -0.9<f2 / f<-0.65;

[0110] 0.6<f3 / f<0.7;

[0111] -3.5<f4 / f<-1.6;

[0112] Furthermore, the focal lengths of the first lens 11 to the fourth lens 14 further satisfy the following conditions: 0.9<|f1 / f2|<1.2 and 0.19<|f3 / f4|<1.

[0113] According to this specific embodiment, by regulating the optical power distribution of each lens to ensure uniform light correction capabilities, this design significantly enhances the sensitivity of lens tolerances in projection system design. This means that during the manufacturing and assembly process, even if the lens has slight size or shape deviations, the overall optical performance is guaranteed to be stable, significantly improving assembly flexibility and production efficiency.

[0114] The projection lens of this application uses adjacent positive and negative lenses together to jointly correct aberrations, achieving a balanced distribution of aberration correction. This optical design effectively reduces geometric light aberrations such as spherical aberration and coma, significantly improving the imaging quality of AR optical machines and ensuring image clarity.

[0115] In some examples of the present application, the Abbe numbers of the first lens 11 to the fourth lens 14 satisfy:

[0116] 1.85<V d1 / V d2 <2.3;

[0117] 2.4<V d3 / V d4 <2.7;

[0118] Among them, V d1 、V d2 、V d3 and V d4 are the Abbe numbers of the first lens 11 , the second lens 12 , the third lens 13 and the fourth lens 14 , respectively.

[0119] The Abbe number is an important parameter for measuring the dispersion ability of lens materials. The higher the value, the smaller the dispersion, that is, the closer the lens's refractive ability for light of different wavelengths is, which helps to reduce chromatic aberration.

[0120] By controlling the Abbe number ratio of adjacent lenses within a certain range, the present application can make the refraction of light of different wavelengths by these lenses more consistent during the imaging process, thereby reducing chromatic aberration and improving imaging quality.

[0121] In AR optical systems, chromatic aberration is a key factor affecting image quality. In this application, by precisely controlling the Abbe number ratio of the lenses, chromatic aberration in the projection system can be significantly reduced, thereby improving the overall performance of the AR optical system. Furthermore, this control helps improve the uniformity of the AR optical system, resulting in clearer images.

[0122] As part of AR optical engine design, the lens Abbe number constraint is closely related to other aspects of the entire AR optical engine architecture, such as lens power distribution and surface design. By comprehensively considering these factors, the AR optical engine architecture can be further optimized to achieve a smaller and lighter design.

[0123] In summary, the Abbe number ratio constraint proposed in this example for the first through fourth lenses 11, 14 is designed to precisely control the lens' dispersion capabilities, reduce chromatic aberration, and improve the imaging quality and overall performance of the AR optical engine. This constraint also helps optimize the optical-mechanical architecture, achieving a more compact and lightweight design.

[0124] In some examples of the present application, the first lens 11 , the second lens 12 , the third lens 13 , and the fourth lens 14 are aspherical lenses.

[0125] That is to say, the four lenses included in the projection lens 1 are all aspherical lenses.

[0126] First, the projection lens 1 is designed with four aspherical lenses, and its production and processing is based on molds. This production method is conducive to mass production and improves production efficiency. Compared with spherical lenses, aspherical lenses can more accurately correct light and improve image quality.

[0127] Secondly, the projection lens 1 of the present application adopts a four-lens design. These lenses work together to distribute and control the angle of light, thereby ensuring that even with a conventional lens surface, the predetermined functional indicators of the projection lens can be achieved. This design strategy not only significantly reduces the difficulty of lens processing, making the production process smoother, but also provides greater flexibility and convenience for the design of lens barrels and AR optical machine modules. More importantly, it lays a solid foundation for the large-scale mass production of AR optical machines, and strongly promotes the popularization and application of AR technology.

[0128] Furthermore, the projection lens 1 of the present application uses only four lenses, and all lenses are designed as even-order aspherical lenses. This efficient lens design scheme enables the projection lens to achieve the target optical parameters with a minimum number of lenses while maintaining excellent optical performance, greatly promoting the miniaturization of AR optical machines. The application of even-order aspherical lenses not only further optimizes the focusing and correction capabilities of light, but also effectively reduces the overall volume and weight of the optical machine by reducing the number of lenses, providing a strong guarantee for the portability and comfort of AR glasses, and is the key to promoting the development of AR technology towards lighter and smaller directions.

[0129] The projection system provided by the embodiment of the present application effectively solves the problem of excessive size of the color μLED AR optical machine using the x-cube color combination prism solution in the prior art. Specifically, by adopting four aspherical lenses as the projection lens 1, the aspherical lenses are produced and processed based on molds, which significantly improves the feasibility of mass production; at the same time, these four lenses work together to reasonably distribute the optical focal length, so that the lens surface remains in a regular shape to meet the various performance indicators of the projection lens, thereby greatly reducing the difficulty of lens processing, providing more convenience for the design of the lens barrel and AR optical machine module, and further accelerating the process of mass production. In addition, the projection system of the present application only requires four even-order aspherical lenses to accurately achieve the target optical machine parameters, making a positive contribution to promoting the miniaturization of AR optical machines.

[0130] In some examples of this application, see Figure 2 , the first lens 11 is located on the side away from the image source 3; the projection system also includes a front aperture 01, which is located on the side of the first lens 11 away from the image source 3; the diameter of the front aperture 01 is D, 2mm<D<5mm, and the diameter of the front aperture 01 is used to match the entrance pupil diameter of the external optical waveguide device.

[0131] In this example of the present application, the diameter of the front aperture 01 is D, which is controlled in the range of 2mm<D<5mm. The diameter of the front aperture 01 is used to match the entrance pupil diameter of the external optical waveguide device. This design can improve the optical coupling efficiency.

[0132] Specifically, by precisely controlling the diameter D of the front aperture 01 between 2mm and 5mm, the light output by the projection system can be matched to the entrance pupil diameter of the external optical waveguide device. This helps reduce light loss during the coupling process, improves optical coupling efficiency, and thus enhances the display brightness and clarity of AR optical display devices such as AR light engines.

[0133] As a key component in AR optical display devices such as AR glasses, the performance of optical waveguides directly impacts the user's visual experience. By matching the diameter of the front aperture 01 with the entrance pupil diameter of the optical waveguide, we ensure more stable and uniform light propagation through the waveguide, thereby optimizing the imaging performance of the waveguide.

[0134] In some examples of the present application, the exit pupil distance of the projection system is L, 0<L<3mm, and the exit pupil distance is the distance from the surface of the first lens 11 away from the image source 3 to the front aperture 01.

[0135] Controlling the range of the exit pupil distance L (i.e., 0 < L < 3 mm) of the projection system provided in the embodiments of this application is key to achieving a miniaturized AR optical machine. This range ensures that sufficient light can pass through the projection system and enter the user's eyes while limiting the size and weight of the AR optical machine. For example, a smaller exit pupil distance L can also help reduce the wearing burden of AR glasses and improve user comfort.

[0136] By accurately calculating and adjusting the exit pupil distance L, the light propagation path in the projection system can be further optimized, making the imaging more accurate and stable.

[0137] In addition, the design of AR glasses needs to consider the user's wearing comfort and ease of use. A shorter pupil distance means that the AR optical machine can be closer to the user's eyes without causing excessive interference or obstruction to the user's vision.

[0138] In some examples of the present application, the image source 3 is an RGBμLED image source, the pixel size of the image source 3 is panel pixel, 2μm<panel pixel<5μm, the image height is H, and 0mm<H≤6mm.

[0139] In this example of the present application, the image source 3 is an RGB μLED image source. The pixel size of the image source 3 is a panel pixel, which is controlled within the range of 2 μm < panel pixel < 5 μm. The image height is H, which is controlled within the range of 0 mm < H ≤ 6 mm. The design of the image source 3 in this example can bring the following technical effects:

[0140] (1) Improve image resolution:

[0141] The pixel size of the image source 3 is between 2μm and 5μm, which ensures that the image source outputs high-resolution images. This is crucial for AR glasses because high-resolution images can provide a more delicate visual experience.

[0142] (2) Optimize imaging quality:

[0143] Controlling the image height of the image source 3 (0mm<H≤6mm) helps optimize imaging quality. Appropriate image height can ensure that light is fully utilized and corrected in the projection system, thereby reducing aberrations and distortions and improving imaging clarity and accuracy.

[0144] In addition, under the premise of meeting the optical performance requirements of the projection system, by reasonably controlling the range of pixel size and image height, the manufacturing cost of the image source can be reduced to a certain extent, thereby improving the market competitiveness of the entire AR glasses.

[0145] The projection system provided by the embodiments of the present application has low optical distortion (less than 1%), which significantly improves imaging quality. Furthermore, the average MTF (Modulation Transfer Function) value per field of view is high. For example, at 125 lp / mm, the MTF is greater than 0.7, further demonstrating the excellent imaging performance of the projection system.

[0146] The projection system provided in the embodiment of the present application has a field of view (FOV) of 20° to 40°.

[0147] The projection system provided in the embodiments of this application is suitable for μLED panels of various sizes, demonstrating its wide adaptability. Furthermore, the entire projection system supports full-color imaging in the visible light wavelength range, meeting the color performance requirements of AR optical machines.

[0148] In summary, the projection system provided in the embodiments of this application, through the use of four aspheric lenses, reasonable optical power distribution, and curvature design, realizes a compact, high-quality color μLED AR optical projection system. This projection system not only facilitates mass production and assembly, but also significantly improves the wearing comfort and imaging quality of AR glasses, making a significant contribution to the popularization and development of AR technology.

[0149] According to another embodiment of the present application, an optical display device is provided, comprising: the projection system and the optical waveguide device as described above, wherein the diameter of the front aperture 01 of the projection system matches the entrance pupil diameter of the optical waveguide device.

[0150] The precise matching of the diameter of the front aperture 01 with the entrance pupil diameter of the optical waveguide component of the optical display device ensures that the light emitted by the projection system can be efficiently coupled into the optical waveguide component. This efficient coupling reduces light loss and improves the overall brightness of the optical display device.

[0151] The projection system's exit pupil diameter matches the optical waveguide's entrance pupil diameter, helping to maintain the collimation and focus of light, thereby avoiding image blur and distortion caused by light scattering or loss of focus. This provides users with a clearer visual experience.

[0152] By precisely matching the diameter of the projection system's front aperture 01 with the entrance pupil diameter of the optical waveguide, the stability of the entire optical display system can be enhanced. This helps ensure that the projection system can provide stable imaging results in various usage environments.

[0153] Optical display devices that integrate efficient projection systems and optical waveguides can provide users with clearer images and a more comfortable wearing experience. This is particularly important for miniaturized and lightweight optical display devices such as AR glasses.

[0154] The present application is described in detail below through Example 1 and Example 2.

[0155] Example 1

[0156] See also Figure 3 The projection system includes a front aperture 01, a first lens 11, a second lens 12, a third lens 13, a fourth lens 14, a color combining prism 2 and an image source 3, which are arranged in sequence;

[0157] The first lens 11, the second lens 12, the third lens 13 and the fourth lens 14 constitute a projection lens 1, and the optical power of the projection lens 1 is positive;

[0158] The first lens 11, the second lens 12, the third lens 13 and the fourth lens 14 are all aspherical lenses, and the first lens 11 has positive refractive power, the second lens 12 has negative refractive power, the third lens 13 has positive refractive power, and the fourth lens 14 has negative refractive power.

[0159] The image source 3 is based on a 640*480*4μm μLED panel with an image height of 3.2mm and a FOV of 25°.

[0160] The projection system shown in Example 1 has a total optical length of 11.6 mm, an entrance pupil diameter of 3.7 mm, an F number of 1.9, and an effective focal length EFFL of 7.1 mm.

[0161] The wavelengths of the projection light are set to 463:527:635nm=1:2:1.

[0162] The optical parameters of the lenses and prisms in the projection system provided in Example 1 are shown in Table 1.

[0163] Table 1

[0164] # Type Radius Thickness Material Semi-Diameter Conic Par1 Par2 Par3 Par4 0 STANDARD unlimited unlimited 0 0 0 0 0 0 1 STANDARD unlimited 1.2 1.85 0.00 0.00 0.00 0.00 0.00 2 EVENASPH 14.92 0.80 1.69,53.0 2.23 -100.00 0 1.66E-02 -2.54E-03 1.64E-04 3 EVENASPH -5.59 0.10 2.23 -38.29 0 1.63E-02 -3.38E-03 2.51E-04 4 EVENASPH 1.81 0.60 1.64,23.4 2.21 -1.92 0 -6.31E-03 -1.38E-04 4.70E-05 5 EVENASPH 1.10 1.10 2.01 -2.20 0 1.08E-02 -4.17E-03 6.27E-04 6 EVENASPH 10.31 1.13 1.53,56.3 2.05 -41.80 0 1.02E-02 -2.25E-03 1.59E-04 7 EVENASPH -2.85 0.43 2.09 -2.92 0 1.30E-02 -2.30E-03 1.60E-04 8 EVENASPH -1.35 0.54 1.65,21.4 2.08 -1.97 0 2.15E-02 -4.83E-03 8.25E-04 9 EVENASPH -1.88 0.54 2.11 -1.04 0.0 3.38E-02 -4.99E-03 5.79E-04 10 STANDARD unlimited 4.60 1.52,64.2 2.25 0.00 0.0 0.00 0.00 0.00 11 STANDARD unlimited 0 1.69 0.00 0.0 0.00 0.00 0.00 12 STANDARD unlimited 0.55 1.69 0.00 0.00 0.00 0.00 0.00 13 STANDARD unlimited 0 1.59 0 0 0 0 0

[0165] The optical performance of the projection system provided in this embodiment 1 can be found in Figures 4 to 7 :

[0166] See also Figure 4 , Figure 4 The optical distortion diagram of the projection system is shown. Figure 4 It can be seen from the figure that the optical distortion of the projection system of Example 1 is less than 1%, which is a very good performance. This small optical distortion indicates that the imaging quality is high and the user can see a clear image.

[0167] See also Figure 5 , Figure 5 The figure shows the modulation transfer function (MTF) of the projection system. MTF measures the contrast transfer capability of the projection system for different spatial frequencies. Figure 5 It can be seen that in Example 1, the average MTF of each field of view is greater than 0.7@125lp / mm (Nyquist frequency), which indicates that the projection system can well convey image details and contrast, and has good imaging quality.

[0168] See also Figure 6 , Figure 6 The figure shows the through-focus MTF diagram of the projection system, which is used to evaluate the imaging quality of the projection system in the defocus state. Figure 6It can be seen that in the projection system provided in Example 1, MTF>0.4@125lp / mm (Nyquist frequency) and defocus range>0.02mm. This shows that the projection system has a large defocus range, which is beneficial to improving imaging quality.

[0169] See also Figure 7 , Figure 7 The figure shows the relative illumination of the projection system. The illumination at the outermost edge relative to the center is >88%, indicating that the light distribution of the projection system is very uniform, which is conducive to improving the uniformity of the AR light engine using this projection system. This is of great significance for improving the user's visual experience and comfort.

[0170] Example 2

[0171] See also Figure 8 The projection system includes a front aperture 01, a first lens 11, a second lens 12, a third lens 13, a fourth lens 14, a color combining prism 2 and an image source 3, which are arranged in sequence;

[0172] The first lens 11, the second lens 12, the third lens 13 and the fourth lens 14 constitute a projection lens 1, and the optical power of the projection lens 1 is positive;

[0173] The first lens 11, the second lens 12, the third lens 13 and the fourth lens 14 are all aspherical lenses, and the first lens 11 has positive refractive power, the second lens 12 has negative refractive power, the third lens 13 has positive refractive power, and the fourth lens 14 has negative refractive power.

[0174] The image source 3 is based on a 600*800*2.5μm μLED panel with an image height of 2.5mm and a FOV of 25°.

[0175] The projection system shown in Example 2 has a total optical length of 8.1 mm, an entrance pupil diameter of 3.1 mm, an F number of 1.8, and an effective focal length EFFL of 5.5 mm.

[0176] The wavelengths of the projection light are set to 463:527:635nm=1:2:1.

[0177] The optical parameters of the lenses and prisms in the projection system provided in Example 2 are shown in Table 2.

[0178] Table 2

[0179]

[0180]

[0181] The optical performance of the projection system provided in this embodiment 2 can be found in Figures 9 to 12 :

[0182] See also Figure 9 , Figure 9 The optical distortion diagram of the projection system is shown. Figure 9 It can be seen from the figure that the optical distortion of the projection system of Example 2 is less than 1%, which is a very good performance. The small optical distortion indicates that the imaging quality is high and the user can see a clear image.

[0183] See also Figure 10 , Figure 10 The figure shows the modulation transfer function (MTF) of the projection system. MTF measures the contrast transfer capability of the projection system for different spatial frequencies. Figure 10 It can be seen that in Example 2, the average MTF of each field of view is greater than MTF>0.66@200lp / mm (Nyquist frequency), which indicates that the projection system can well convey image details and contrast, and has good imaging quality.

[0184] See also Figure 11 , Figure 11 The figure shows the through-focus MTF diagram of the projection system, which is used to evaluate the imaging quality of the projection system in the defocus state. Figure 11 It can be seen from the figure that in this embodiment 2, the defocus range where MTF is greater than MTF>0.3 is greater than 0.016 mm, which is beneficial to improving imaging quality.

[0185] See also Figure 12 , Figure 12 The figure shows the relative illumination of the projection system. The illumination at the outermost edge relative to the center is >88%, indicating that the light distribution of the projection system is very uniform, which is conducive to improving the uniformity of the AR light engine using this projection system. This is of great significance for improving the user's visual experience and comfort.

[0186] See also Figures 4 to 7 ,as well as Figures 9 to 12 As can be seen, the projection system provided by the embodiments of this application has excellent optical performance. By optimizing key parameters such as optical distortion, modulation transfer function, through-focus MTF, and relative illumination, high-quality full-color display is achieved. These excellent performances make this projection system have broad application prospects in the field of AR optical machines.

[0187] The above embodiments focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0188] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above examples may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A projection system, characterized in that: The invention comprises a projection lens (1), a color combining prism (2) and an image source (3) which are arranged in sequence, wherein the projection lens (1) comprises a first lens (11), a second lens (12), a third lens (13) and a fourth lens (14) which are arranged in sequence along the same optical axis; The curvatures of the first lens (11) to the fourth lens (14) and the focal length of the projection lens (1) satisfy: -0.1<(K1+K2) / f<0.1; 0.2<(K3+K4) / f<0.35; -0.1<(K5+K6) / f<0; -0.3<(K7+K8) / f<-0.1; Wherein, K1 is the curvature of the surface of the first lens (11) away from the image source (3), K2 is the curvature of the surface of the first lens (11) close to the image source (3); K3 is the curvature of the surface of the second lens (12) away from the image source (3), K4 is the curvature of the surface of the second lens (12) close to the image source (3); K5 is the curvature of the surface of the third lens (13) away from the image source (3), K6 is the curvature of the surface of the third lens (13) close to the image source (3); K7 is the curvature of the surface of the fourth lens (14) away from the image source (3), K8 is the curvature of the surface of the fourth lens (14) close to the image source (3); and f is the focal length of the projection lens (1).

2. The projection system according to claim 1, wherein: The projection lens (1) has positive optical power.

3. The projection system according to claim 2, wherein: The first lens (11) has positive optical power, the second lens (12) has negative optical power, the third lens (13) has positive optical power, and the fourth lens (14) has negative optical power.

4. The projection system according to claim 1, wherein: The focal lengths of the first lens (11) to the fourth lens (14) and the focal length of the projection lens (1) satisfy: 0.75<f1 / f<0.9; -0.9<f2 / f<-0.65; 0.6<f3 / f<0.7; -3.5<f4 / f<-1.6; Wherein, f1 is the focal length of the first lens (11), f2 is the focal length of the second lens (12), f3 is the focal length of the third lens (13), and f4 is the focal length of the fourth lens (14).

5. The projection system according to claim 4, wherein: The focal length f1 of the first lens (11) and the focal length f2 of the second lens (12) satisfy: 0.9<|f1 / f2|<1.2; The focal length f3 of the third lens (13) and the focal length f4 of the fourth lens (14) satisfy: 0.19<|f3 / f4|<1.

6. The projection system according to claim 1, wherein: The Abbe numbers of the first lens (11) and the second lens (12) satisfy: 1.85<V d1 / V d2 <2.3; Among them, V d1 、V d2 are the Abbe numbers of the first lens (11) and the second lens (12), respectively; The Abbe numbers of the third lens (13) and the fourth lens (14) satisfy: 2.4<V d3 / V d4 <2.7; among which, V d3 and V d4 are the Abbe numbers of the third lens (13) and the fourth lens (14), respectively.

7. The projection system according to claim 1, wherein: The first lens (11), the second lens (12), the third lens (13) and the fourth lens (14) are aspherical lenses.

8. The projection system according to any one of claims 1 to 7, characterized in that: The first lens (11) is located on a side away from the image source (3); The projection system further comprises a front aperture (01), wherein the front aperture (01) is located on a side of the first lens (11) away from the image source (3); The diameter of the front aperture (01) is D, 2mm<D<5mm, and the diameter of the front aperture (01) is used to match the entrance pupil diameter of an external optical waveguide device.

9. The projection system according to claim 8, wherein: The projection system has an exit pupil distance L, 0<L<3 mm, and the exit pupil distance is the distance from the surface of the first lens (11) away from the image source (3) to the front aperture (01).

10. The projection system according to claim 8, wherein: The image source (3) is an RGBμLED image source, the pixel size of the image source (3) is panelpixel, 2μm<panelpixel<5μm, the image height is H, and 0mm<H≤6mm.

11. An optical display device, characterized in that: include: The projection system according to any one of claims 1 to 10; and An optical waveguide device, wherein the diameter of the front aperture (01) of the projection system matches the entrance pupil diameter of the optical waveguide device.

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