Projection system and optical display apparatus

Abstract

The invention provides a projection system and optical display equipment. The projection system comprises a projection lens, a color combination prism and an image source, the projection lens comprises a first lens, a second lens, a third lens and a fourth lens, and the curvature of the lenses and the focal length of the projection lens meet the following conditions:-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 respectively the curvature of the surface, far away from the image source, of the first lens and the curvature of the surface, close to the image source, of the first lens; k3 and K4 are respectively the curvature of the surface, far away from the image source, of the second lens and the curvature of the surface, close to the image source, of the second lens; k5 and K6 are respectively the curvature of the surface, far away from the image source, of the third lens and the curvature of the surface, close to the image source, of the third lens; k7 and K8 are the curvature of the surface, far away from the image source, of the fourth lens and the curvature of the surface, close to the image source, of the fourth lens 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, and more specifically, relate to a light projection system and an optical display device. Background Art

[0002] With the rise of the concept of the metaverse, AR optical display devices such as AR smart glasses, as important hardware carriers for realizing the metaverse experience, have attracted much attention for their technological development. The miniaturization and lightweight of AR smart glasses are the key to popularizing them to consumers, and the miniaturization design of AR optical machines (including projection systems) as the core optical devices in AR smart glasses is particularly important. At present, AR optical machines based on μLED technology are regarded as the ultimate choice in the field of AR optical machines because of their simple structure, small size and great display performance potential. However, since μLED technology can only achieve mass production of monochrome panels at present, in response to consumers' demand for color imaging, the industry generally adopts the x-cube color combination scheme to combine the red, green and blue μLED panels for imaging to produce small-volume color AR optical machines. Despite this, the current color μLED optical machines using the xcube color combination scheme are still relatively large in size, which limits 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 lens to the fourth lens and the focal length of the projection lens satisfy:

[0006] -0.1<(K 1 +K 2 ) / f<0.1;

[0007] 0.2<(K 3 +K 4 ) / f<0.35;

[0008] -0.1<(K 5 +K 6 ) / f<0;

[0009] -0.3<(K 7 +K 8 ) / f<-0.1;

[0010] Among them, K 1 is the curvature of the surface of the first lens away from the image source, K 2 K is the curvature of the surface of the first lens close to the image source; 3 is the curvature of the surface of the second lens away from the image source, K 4 K is the curvature of the surface of the second lens close to the image source; 5 is the curvature of the surface of the third lens away from the image source, K 6 K is the curvature of the surface of the third lens close to the image source; 7 is the curvature of the surface of the fourth lens away from the image source, K 8 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<f 1 / f<0.9;

[0015] -0.9<f 2 / f<-0.65;

[0016] 0.6<f 3 / f<0.7;

[0017] -3.5<f 4 / f<-1.6;

[0018] Among them, f 1 is the focal length of the first lens, f 2 is the focal length of the second lens, f 3 is the focal length of the third lens, f 4 is the focal length of the fourth lens, and f is the focal length of the projection lens.

[0019] Optionally, the focal length f of the first lens is 1 The focal length f of the second lens 2 Satisfy: 0.9<|f 1 / f 2 |<1.2;The focal length f of the third lens 3 The focal length of the fourth lens is f 4Satisfy: 0.19<|f 3 / f 4 |<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; where V d3 and V d4 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 stop, wherein the front aperture stop 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 device.

[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 comprises:

[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 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 more uniform, and the aberration correction capability of each lens is equivalent, which 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 satisfying the above-mentioned curvature constraints, the curvature design of the lens can be optimized, which helps to reduce the thickness of each lens, thereby ensuring the optical performance while realizing the miniaturization of the projection system, which is crucial for portable optical display devices such as AR glasses, and can significantly reduce the weight of the device and improve the wearing comfort of the user.

[0033] To sum up, the projection system of the present application realizes 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 the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0036] Figure 1 One of the structural schematic diagrams of the projection system provided in the embodiment of the present application;

[0037] Figure 2 The second structural schematic diagram of the projection system provided in the 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 graphs of projection systems;

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

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

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

[0047] Fig.12 for Figure 8 Relative illumination diagram of the provided projection system.

[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 arrangement 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 application, 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 as 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 similar 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 in conjunction with the accompanying drawings.

[0056] According to an 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<(K 1 +K 2 ) / f<0.1;

[0058] 0.2<(K 3 +K 4 ) / f<0.35;

[0059] -0.1<(K 5 +K 6 ) / f<0;

[0060] -0.3<(K 7 +K 8 ) / f<-0.1;

[0061] Among them, K 1 is the curvature of the surface of the first lens 11 away from the image source 3, K 2 K is the curvature of the surface of the first lens 11 close to the image source 3; 3 is the curvature of the surface of the second lens 12 away from the image source 3, K 4 K is the curvature of the surface of the second lens 12 close to the image source 3; 5 is the curvature of the surface of the third lens 13 away from the image source 3, K 6 K is the curvature of the surface of the third lens 13 close to the image source 3; 7 is the curvature of the surface of the fourth lens 14 away from the image source 3, K 8 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.

[0062] The projection system provided in the embodiment 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 uses four lenses, which are responsible for distributing the focal length together, and can ensure that the lens surface is a conventional surface shape to achieve the projection lens index function, reduce the difficulty of lens processing, and help design the lens barrel and AR optical machine module, which is conducive to 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 the present application: Figure 1 , which includes three monochromatic μLED image sources in terms of composition: a red light source 301, a green light source 302 and a blue light source 303, which emit red, green and blue light respectively. The three colors of light are combined by the color combining prism 2. The color combining prism 2 can combine the 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 the color combination by the color combining prism 2 is focused and amplified by the projection lens 1, and finally projected to 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 can not only keep the core elements of optical structure design unchanged, but also significantly reduce the complexity of optical structure design, making the optical design evaluation process more efficient and intuitive.

[0068] The projection system provided in the embodiment of the present application, wherein the projection lens 1 includes four lenses. Through the specially designed projection lens 1, 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<(K 1 +K 2 ) / 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<(K 3 +K 4 ) / 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<(K 5 +K 6 ) / f<0, the relationship between the curvature of the fourth lens 14 and the focal length f of the projection lens 1 is: -0.3<(K 7 +K 8 ) / f<-0.1.

[0071] By setting the curvature of each lens and the focal length of the entire projection lens 1, the above constraints can ensure that the surface distribution of each lens is uniform and the aberration correction capability of each lens is also equivalent. This helps to improve the lens tolerance sensitivity of the projection lens 1 design, so that the accuracy and performance of the entire projection system design can be better maintained during the production and assembly process.

[0072] According to this example of the present application, these constraints also help in the processing of the lens, 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 the projection system and even the AR optical machine, because thinner lenses can take up less space.

[0073] The imaging quality can be further improved by properly designing the relationship between the curvature of the lens and the focal length f of the entire projection lens 1. For example, these constraints help reduce optical distortion, improve the MTF (modulation transfer function) value, and increase the MTF value within the defocus range. The improvement of these parameters will directly improve the imaging quality of the projection system, enabling it to provide clearer images.

[0074] The projection system provided in the embodiment of the present application is a miniaturized color μLED projection system with 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 11 to the fourth lens 14 and the focal length f of the projection lens, the surface distribution of each lens is more uniform, and the aberration correction capability of each lens is equivalent, which 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; and, under the condition of satisfying the above curvature constraints, the curvature design of the lens is optimized, which helps to reduce the thickness of each lens, thereby ensuring the optical performance while realizing the miniaturization of the projection system, which is crucial for portable optical display devices such as AR glasses, and can significantly reduce the weight of the device and improve the wearing comfort of the user.

[0075] To sum up, the projection system of the present application realizes 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 the AR optical machine, the focal length of the projection lens 1 directly affects the imaging quality and overall performance of the AR optical machine. The design of positive focal length means that the projection lens 1 has a converging effect on light, which helps to accurately focus the light from the image source 3 onto the waveguide or the observer's eyes, thereby achieving clear imaging.

[0078] Secondly, the design of the projection lens 1 with positive optical power is conducive to achieving compactness and lightness of the projection lens. In AR optical machines, miniaturization and lightness are crucial design goals because they are directly related to the wearing comfort and portability of AR glasses. The projection lens with positive optical power can reduce the volume and weight of the projection lens 1 while maintaining good imaging performance by optimizing the structure and parameters of the lens, such as the radius of curvature, thickness and material.

[0079] In addition, the design of the positive power projection lens 1 also helps to improve the aberration correction capability of the AR optical machine. Aberration is a common problem in optical systems, which will lead to a decrease in image quality. The positive power projection lens can effectively correct various aberrations, such as spherical aberration, coma and field curvature, through reasonable optical power distribution and lens combination, thereby improving the imaging quality and resolution of the AR optical machine.

[0080] In summary, the projection lens 1 is designed with positive focal length, which not only helps to achieve clear imaging of the AR optical machine, but also helps to achieve compactness and lightness of the projection lens, and improves the aberration correction capability of the AR optical machine. These technical effects jointly promote the development of AR optical machine technology and provide strong support for the miniaturization, lightness 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 uses four lenses, which can be seen in Figure 2 The first lens 11, the second lens 12, the third lens 13 and the fourth lens 14 are shown in the figure, and these lenses are arranged in sequence along the optical path. In particular, the optical power of these four lenses is carefully configured: the first lens 11 has a positive optical power, the second lens 12 has a negative optical power, the third lens 13 has a positive optical power, and the fourth lens 14 has a 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 the configuration of positive and negative optical powers, the geometric light aberrations such as spherical aberration and coma of the projection lens can be effectively reduced, thereby improving the imaging quality. The combination of positive and negative lenses enables each lens to take on the task of correcting aberrations to a certain extent, thereby improving the optical performance of the entire projection lens.

[0085] (2) Achieve a compact structure: The design uses a combination of four lenses, and each lens is carefully calculated and optimized, so that the entire projection lens can achieve a more compact structure while maintaining high image quality. This is crucial for the miniaturization of AR optical machines and helps promote the popularization and application of AR glasses.

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

[0087] In addition, the combination of positive and negative lenses can also help balance the chromatic aberration of the entire projection lens. Light of different wavelengths will undergo different degrees of refraction and dispersion when passing through the lens, and the combination of positive and negative lenses can partially offset this chromatic aberration effect, allowing the projection lens to maintain good imaging quality over a wider wavelength range. This is especially important for color AR optical machines, because 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<f 1 / f<0.9;

[0090] -0.9<f 2 / f<-0.65;

[0091] 0.6<f 3 / f<0.7;

[0092] -3.5<f 4 / f<-1.6;

[0093] Among them, f 1 is the focal length of the first lens 11, f 2 is the focal length of the second lens 12, f 3 is the focal length of the third lens 13, f 4 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 focal length f of the first lens 11 is 1 The ratio of the focal length f of the projection lens 1 is between 0.75 and 0.9;

[0096] The focal length f of the second lens 12 is 2 The ratio of the focal length f of the projection lens 1 is between -0.9 and -0.65;

[0097] The focal length f of the third lens 13 is 3 The ratio to the focal length f of the projection lens 1 is between 0.6 and 0.7;

[0098] The focal length f of the fourth lens 14 is 4 The ratio to the focal length f of the projection lens 1 is between -3.5 and -1.6.

[0099] The above focal length ratio design ensures that each lens plays its own 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, so that light can be properly converged or diverged after passing through each lens, thereby reducing aberrations and improving image quality.

[0100] The constraints in this example of the present application can improve the image quality. Specifically, because each lens has an appropriate light correction task and the focal length ratio is set reasonably, the entire projection lens can maintain high image quality at a wider field of view and a longer distance. This is crucial for AR optical display devices such as AR glasses, because it needs to provide users with clear image display.

[0101] In addition, under the premise of satisfying the imaging quality, by reasonably setting the focal length ratio of each lens, the number of lenses in the projection lens and the thickness of each lens can be reasonably controlled to a certain extent, thereby helping to reduce the overall volume 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 also satisfy: 0.9<|f 1 / f 2 |<1.2 and 0.19<|f 3 / f 4 |<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, that is, the ratio of the absolute value of the focal length of the first lens 11 to the second lens 12 |f 1 / f 2 | is between 0.9 and 1.2, the ratio of the absolute value of the focal length of the third lens 13 to that of the fourth lens 14 | f 3 / f 4 | 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 value ratio of the focal lengths of the first lens 11 and the second lens 12 to be between 0.9 and 1.2, it is possible to ensure that the two lenses play a more coordinated role in aberration correction. Similarly, by constraining the absolute value ratio of the focal lengths of the third lens 13 and the fourth lens 14 to be between 0.19 and 1, it is also helpful for them to jointly correct aberrations, thereby improving the imaging quality of the entire projection lens.

[0105] (2) Improving optical stability: The focal length ratio design in this example of the present application helps to 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: The distribution of incident projection light can be further optimized 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. This helps to ensure that the light can be appropriately converged or diverged after passing through each lens, thereby improving the utilization rate of light and the 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<f 1 / f<0.9;

[0109] -0.9<f 2 / f<-0.65;

[0110] 0.6<f 3 / f<0.7;

[0111] -3.5<f 4 / f<-1.6;

[0112] And the focal lengths of the first lens 11 to the fourth lens 14 also satisfy: 0.9<|f 1 / f 2 |<1.2 and 0.19<|f 3 / f 4 |<1.

[0113] According to this specific embodiment, by adjusting the focal power distribution of each lens to ensure that the light correction capability it undertakes is balanced and consistent, this design significantly enhances the sensitivity of lens tolerance in projection system design. This means that during the manufacturing and assembly process, even if there is a slight size or shape deviation in the lens, the stability of the overall optical performance can be ensured, thereby greatly improving the flexibility and production efficiency of assembly.

[0114] The projection lens of this application uses adjacent positive and negative lenses together, so that they jointly undertake the task of correcting aberrations and achieve a balanced distribution of aberration correction. This optical design effectively reduces geometric light aberrations such as spherical aberration and coma, significantly improves the imaging quality of the AR optical machine, and ensures the clarity of the image.

[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 to measure the dispersion ability of lens materials. The higher the value, the smaller the dispersion, that is, the closer the refractive ability of the lens 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 machines, chromatic aberration is one of the key factors affecting imaging quality. In this application, by precisely controlling the Abbe number ratio of the lens, the chromatic aberration of the projection system can be significantly reduced, thereby improving the overall performance of the AR optical machine. In addition, this control also helps to improve the uniformity of the AR optical machine, making the imaging clearer.

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

[0123] In summary, the Abbe number ratio constraint proposed in this example for the first lens 11 to the fourth lens 14 is intended to reduce chromatic aberration and improve the imaging quality and overall performance of the AR optical machine by precisely controlling the dispersion capability of the lens. At the same time, this constraint also helps to optimize the optical machine architecture and achieve a more compact and lightweight design goal.

[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 adopts a design of 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 correct light more accurately and improve imaging quality.

[0127] Secondly, the projection lens 1 of the present application adopts a four-lens design, which works together to distribute and adjust 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 has laid a solid foundation for the large-scale mass production of AR optical machines and has strongly promoted 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 process 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 in a lighter and smaller direction.

[0129] The projection system provided in the embodiment of the present application effectively solves the problem of the large size of the color μLED AR optical machine using the x-cube color combination prism solution in the prior art. Specifically, by using 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, which has made 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 a side away from the image source 3; the projection system also includes a front aperture 01, and 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.

[0131] In this example of the present application, the diameter of the front aperture 01 is D, which is controlled within 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 2 mm and 5 mm, it is possible to ensure that the light output by the projection system matches the entrance pupil diameter of the external optical waveguide device. This helps to reduce the loss of light during the coupling process, improve the optical coupling efficiency, and thus enhance the display brightness and clarity of AR optical display devices such as AR optical machines.

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

[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] The range control of the exit pupil distance L of the projection system provided in the embodiment of the present application (i.e., 0<L<3mm) is the key to realizing a miniaturized AR optical machine. This range ensures that sufficient light can enter the user's eyes through the projection system 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 propagation path of light 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 convenience. A shorter pupil distance means that the AR optical machine can be closer to the user's eyes without causing too much interference or obstruction to the user's line of sight.

[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 RGBμLED image source, the pixel size of the image source 3 is a panel pixel, the range is controlled within 2μm<panel pixel<5μm, the image height is H, the range is controlled within 0mm<H≤6mm. 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 2 μm and 5 μm, which can ensure that the image source outputs an image with high resolution. This is crucial for AR glasses because high-resolution images can provide a more delicate visual experience.

[0142] (2) Optimize imaging quality:

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

[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 in the embodiment of the present application has low optical distortion (<1%), which can significantly improve the imaging quality. At the same time, the average MTF (modulation transfer function) value of each field of view is also high, for example, at 125lp / mm, MTF>0.7, which further proves 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 embodiment of the present application is applicable to μLED panels of various sizes, showing its wide adaptability. At the same time, the entire projection system also 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 embodiment of the present application realizes a small-sized, high-quality color μLED AR optical projection system by adopting four aspherical lenses, reasonable optical power distribution and curvature design. The projection system is not only conducive to mass production and assembly, but also significantly improves the wearing comfort and imaging quality of AR glasses, making an important 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 and the entrance pupil diameter of the optical waveguide device of the optical display device ensures that the light emitted by the projection system can be efficiently coupled into the optical waveguide device. This efficient coupling reduces light loss and improves the overall brightness of the optical display device.

[0151] The exit pupil diameter of the projection system matches the entrance pupil diameter of the optical waveguide device, which helps to maintain the collimation and focus of the light, thereby avoiding image blur and distortion caused by light scattering or defocusing, which 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 effects in a variety of usage environments.

[0153] Optical display devices that integrate efficient projection systems and optical waveguide devices can provide users with clearer images and a more comfortable wearing experience. This is especially 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 form 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 focal power, the second lens 12 has negative focal power, the third lens 13 has positive focal power, and the fourth lens 14 has negative focal power;

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

[0160] The projection system shown in the present embodiment 1 has an optical total 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 wavelength of the projection light is 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 seen 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 that the optical distortion of the projection system of the present embodiment 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 5The 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 this embodiment 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 transmit the details and contrast of the image 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 a defocused state. Figure 6 It can be seen that in the projection system provided in this embodiment 1, MTF>0.4@125lp / mm (Nyquist frequency) and the defocus range>0.02mm. This shows that the projection system has a large defocus range, which is conducive to improving the imaging quality.

[0169] See also Figure 7 , Figure 7 The relative illumination diagram of the projection system is shown, and the illumination at the edge relative to the center is > 88%, which indicates that the light distribution of the projection system is very uniform, which is conducive to improving the uniformity of the AR optical machine using the projection system. This is of great significance for improving the visual experience and comfort of users.

[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 form 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 focal power, the second lens 12 has negative focal power, the third lens 13 has positive focal power, and the fourth lens 14 has negative focal power;

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

[0175] The projection system shown in this embodiment 2 has an optical total 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 wavelength of the projection light is 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 seen in Figures 9 to 12 :

[0182] See also Fig. 9 , Fig. 9 The optical distortion diagram of the projection system is shown. Fig. 9 It can be seen that the optical distortion of the projection system of this embodiment 2 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.

[0183] See also Fig.10 , Fig.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. Fig.10 It can be seen that in this embodiment 2, the average MTF of each field of view is greater than MTF>0.66@200lp / mm (Nyquist frequency), which shows that the projection system can well transmit the details and contrast of the image and has good imaging quality.

[0184] See also Fig.11 , Fig.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 a through-focus state. Fig.11 It can be seen that in this embodiment 2, the defocus range where MTF is greater than MTF>0.3 is>0.016mm, which is beneficial to improving the imaging quality.

[0185] See also Fig.12 , Fig.12 The relative illumination diagram of the projection system is shown, and the illumination at the edge relative to the center is > 88%, which indicates that the light distribution of the projection system is very uniform, which is conducive to improving the uniformity of the AR optical machine using the projection system. This is of great significance for improving the visual experience and comfort of users.

[0186] See also Figures 4 to 7 ,as well as Figures 9 to 12It can be seen that the projection system provided by the embodiment of the present application has excellent optical performance. By optimizing key parameters such as optical distortion, modulation transfer function, defocus MTF and relative illumination, high-quality full-color display is achieved. These excellent performances make the 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 only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments 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, characterized in that: The projection lens (1) has a positive optical power.

3. The projection system according to claim 2, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: 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; where 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, characterized in that: 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 stop (01), wherein the front aperture stop (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, characterized in that: 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).

10. The projection system according to claim 8, characterized in that: 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 component, wherein the diameter of a front aperture (01) of the projection system matches the entrance pupil diameter of the optical waveguide component.

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