A projection light machine

Abstract

The application discloses a projection light machine, and relates to the technical field of projection. The projection light machine comprises a light barrier, an image source and an optical lens group. The optical lens group comprises: a first lens with positive focal power; a second lens with positive focal power; a third lens with negative focal power; a fourth lens with positive focal power; and a fifth lens with positive focal power. The ratio of the effective focal length of the projection light machine to the total length of the projection light machine is within the range of 0.7 to 0.95. The greater the ratio of the effective focal length of the projection light machine to the total length of the projection light machine, the shorter the size of the projection light machine, that is, the application realizes the miniaturization of the projection light machine.

Description

[0001] This application claims priority to Chinese Patent Application No. 202211693900.X, filed on December 28, 2022, entitled “A Projection Optical Engine”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of projection technology, and in particular to a projection optical engine. Background Technology

[0003] Augmented Reality (AR) is a technology that cleverly blends virtual information with the real world. It projects virtual images onto the human eye through a near-eye display device, allowing users to simultaneously receive information from both the real and virtual worlds, resulting in a multi-sensory visual experience. The AR projection optical engine, as a key component in converting images from a near-eye screen display into the normal visual range of the human eye, typically employs a relatively complex optical path design and multiple lens groups to ensure a good visual experience.

[0004] Currently, there are various solutions for augmented reality near-eye display devices. Traditional solutions include projection schemes based on active light-emitting display sources such as Liquid Crystal Display (LCD) and Organic Light-Emitting Diode (OLED) screens, and projection schemes based on passive light-emitting display sources such as Liquid Crystal on Silicon (LCOS) and Digital Light Processing (DLP) screens. However, LCD and OLED screens lack sufficient brightness to provide adequate display brightness for users in outdoor conditions. LCOS and DLP screens, being passive light-emitting devices, require additional lighting systems, resulting in larger size and heavier weight, failing to meet users' demands for lightweight and portable designs. MicroLED screens, as a new type of high-brightness, high-resolution, and miniaturized active light-emitting display source device, offer the possibility of miniaturized projection optical engines. However, current optical engines adapted to MicroLED display sources are relatively long and bulky, failing to meet the appearance and high integration requirements of portable AR glasses.

[0005] Therefore, providing a miniaturized projection optical engine is a technical problem that urgently needs to be solved by those in the field. Summary of the Invention

[0006] The purpose of this application is to provide a projection optical engine for miniaturizing the projection optical engine.

[0007] To address the aforementioned technical problems, this application provides a projection optical engine, including an aperture stop, an image source, and an optical lens group, wherein the optical lens group includes:

[0008] The first lens has positive optical power;

[0009] The second lens has positive optical power;

[0010] The third lens has negative optical power;

[0011] The fourth lens has positive optical power;

[0012] The fifth lens has positive optical power;

[0013] The optical lens group satisfies:

[0014]

[0015] The effective focal length of the projection optical engine is EFL, and the distance from the aperture surface of the projection optical engine to the image source surface of the projection optical engine on the optical axis is TTL.

[0016] Preferably, along the direction from the object side to the image side of the projection optical engine, the aperture stop, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the image source are placed sequentially.

[0017] Preferably, the projection optical engine satisfies the following expression:

[0018]

[0019] The effective focal length of the projection optical engine is EFL, and the diameter of the aperture of the aperture is EPD.

[0020] Preferably, the projection optical engine satisfies the following formula:

[0021] 1.85≤TTL / (I mgh *2)≤2.65; and / or

[0022] 12°≤H FOV ≤18°; and / or

[0023] 0.21≤(CT 34 +CT 45 ) / TTL≤0.35

[0024] Where TTL is the distance from the center point of the aperture plane to the center point of the image source, I mgh H is half the diagonal length of the effective projection area of ​​the image source of the projection engine. FOVThe field of view is half of the diagonal direction of the projection optical engine, CT 34 The distance between the center point of the image-side lens surface of the third lens of the projection optical engine and the center point of the object-side lens surface of the fourth lens.

[0025] Preferably, the projection optical engine satisfies the following expression:

[0026] and / or

[0027]

[0028] in, The optical power of the first lens is... The optical power of the second lens is [value]. The optical power of the third lens is denoted as .

[0029] Preferably, the projection optical engine satisfies the following expression:

[0030] 1.67≤n1≤1.89, 35≤VD1≤57 and / or

[0031] 1.5≤n²≤1.6, 50≤VD²≤60 and / or

[0032] 1.61≤n3≤1.68, 19≤VD3≤26 and / or

[0033] 1.5≤n4≤1.6, 50≤VD4≤60 and / or

[0034] 1.61≤n5≤1.68, 19≤VD5≤26

[0035] Wherein, n1 is the refractive index of the first lens, VD1 is the Abbe number of the first lens, n2 is the refractive index of the second lens, VD2 is the Abbe number of the second lens, n3 is the refractive index of the third lens, VD3 is the Abbe number of the third lens, n4 is the refractive index of the fourth lens, VD4 is the Abbe number of the fourth lens, and n5 is the refractive index of the fifth lens, VD5 is the Abbe number of the fifth lens.

[0036] Preferably, the projection optical engine satisfies the following expression:

[0037] 0.9 ≤ f1 / EFL ≤ 1.6; and / or

[0038] 1.0 ≤ f2 / EFL ≤ 1.7; and / or

[0039] -1≤f3 / EFL≤-0.4; and / or

[0040] 2 ≤ f4 / EFL ≤ 3.4; and / or

[0041] 7≤f5 / EFL≤13

[0042] Wherein, f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, and EFL is the effective focal length of the projection optical engine.

[0043] Preferably, the projection optical engine satisfies the following formula:

[0044]

[0045] Among them, c 31 c is the curvature of the center point of the object-side surface of the third lens. 32 Let be the curvature of the center point of the image-side surface of the third lens.

[0046] Preferably, the projection optical engine satisfies the following formula:

[0047] and / or

[0048]

[0049] Wherein, c 11 Let c be the curvature of the center point of the object-side surface of the first lens. 12 Let c be the curvature of the center point of the image-side surface of the first lens. 21 Let c be the curvature of the center point of the object-side surface of the second lens. 22 Let be the curvature of the center point of the image-side surface of the second lens.

[0050] Preferably, the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all aspherical lenses.

[0051] This application provides a projection optical engine, including an aperture stop, an image source, and an optical lens group, wherein the optical lens group includes: a first lens having positive optical power; a second lens having positive optical power; a third lens having negative optical power; a fourth lens having positive optical power; and a fifth lens having positive optical power; the optical lens group satisfies:

[0052]

[0053] The effective focal length of the projection optical engine is EFL, and the distance from the aperture surface to the image source surface on the optical axis is TTL. The larger the ratio of the effective focal length of the optical lens group to the distance from the aperture surface to the image source surface on the optical axis (i.e., the total length of the projection optical engine), the shorter the size of the projection optical engine. The ratio of the effective focal length to the total length of the optical engine provided in this application is between 0.7 and 0.95, thus achieving miniaturization of the projection optical engine. Attached Figure Description

[0054] To more clearly illustrate the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 This is a schematic diagram of a projection optical engine provided in an embodiment of this application;

[0056] Figure 2 This is a schematic diagram of the optical path of the projection optical engine provided in the embodiments of this application;

[0057] Figure 3 A schematic diagram of the modulation transfer function of the projection optical engine provided in the embodiments of this application;

[0058] Figure 4a A schematic diagram of the field curvature of the projection optical engine provided in an embodiment of this application;

[0059] Figure 4b This is a schematic diagram of the distortion of the projection optical engine provided in the embodiments of this application;

[0060] Figure 5 Axial chromatic aberration diagram of the projection optical engine provided in the embodiments of this application;

[0061] Figure 6 The vertical axis color difference diagram provided in the embodiments of this application;

[0062] Figure 7 A schematic diagram of the relative illumination of the projection optical engine provided in an embodiment of this application;

[0063] Figure 8a The defocus curve of the projection optical engine provided in the embodiments of this application at -10°C;

[0064] Figure 8b The defocus curve of the projection optical engine at 20°C provided in the embodiments of this application;

[0065] Figure 8c The defocus curve of the projection optical engine provided in the embodiment of this application at 60°C. Detailed Implementation

[0066] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0067] The core of this application is to provide a projection optical engine for miniaturizing projection optical engines.

[0068] As a key component in converting near-eye screen images into the normal visual range of the human eye, the AR projection optical engine typically employs a complex optical path design and multiple lens groups to ensure a good visual experience. To meet users' needs for lightweight and portable wearability, this application uses a MicroLED screen as the display source device for the projection optical engine. However, current optical engines adapted to MicroLED display sources are relatively long and bulky, failing to meet the aesthetic and high integration requirements of portable AR glasses. Furthermore, to ensure AR glasses function well under varying environmental temperatures, since the curvature and optical power of glass lenses are relatively insensitive to temperature, micro-projection optical engines often employ an all-glass lens design. However, an all-glass lens design is not conducive to volume reduction, and the weight of glass lenses is significant, hindering the improvement of user experience and the achievement of lightweight and portable AR augmented reality glasses. Therefore, this application proposes an AR projection optical engine based on a MicroLED screen design that is miniaturized, lightweight, high-quality, and capable of operating well under harsh temperatures, further enhancing the near-eye augmented reality display effect for users.

[0069] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. Figure 1 This is a schematic diagram of a projection optical engine provided in an embodiment of this application, as shown below. Figure 1 As shown, the system includes an aperture stop 1, an image source 7, and an optical lens group. The optical lens group includes: a first lens 2 with positive optical power; a second lens 3 with positive optical power; a third lens 4 with negative optical power; a fourth lens 5 with positive optical power; and a fifth lens 6 with positive optical power. The optical lens group satisfies the following:

[0070]

[0071] The effective focal length of the projection optical engine is EFL, and the distance from the aperture surface to the image source surface of the projection optical engine along the optical axis is TTL. The projection optical engine is used to receive the projection light emitted by the display unit, and the projection light passes through the projection optical engine and is directed to the aperture.

[0072] In the projection optical engine provided in this embodiment, the ratio of the effective focal length of the optical lens group to the distance from the aperture surface to the image source surface on the optical axis, i.e., the total length of the optical engine, is between 0.7 and 0.95. The larger the ratio of the effective focal length to the total length of the projection optical engine, the shorter the size of the projection optical engine, which means that the miniaturization of the projection optical engine is achieved.

[0073] In one embodiment, along the direction from the object side to the image side of the projection optical engine, an aperture, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and an image source are placed sequentially.

[0074] To improve the light extraction efficiency of the projection optical engine and reduce its overall power consumption, a preferred implementation is one where the projection optical engine satisfies the following expression:

[0075]

[0076] The effective focal length of the projection optical engine is EFL, and the aperture diameter of the aperture is EPD.

[0077] In one embodiment, to further reduce the size of the projection optical engine and increase the field of view of the optical system, a preferred embodiment is that the projection optical engine satisfies the following expression:

[0078] 1.85≤TTL / (I mgh *2)≤2.65; and / or

[0079] 12°≤H FOV ≤18°; and / or

[0080] 0.21≤(CT 34 +CT 45 ) / TTL≤0.35

[0081] Where TTL is the distance from the center point of the aperture plane to the center point of the image source, I mgh H is half the diagonal length of the effective projection area of ​​the image source of the projector. FOV The field of view is half the diagonal angle of the projector engine, CT 34 It is the distance between the center point of the image-side lens surface of the third lens of the projection optical engine and the center point of the object-side lens surface of the fourth lens.

[0082] In one embodiment, to balance the optical power of the projection engine and alleviate the sensitivity of the lens assembly in the optical system, thereby improving the imaging quality of the optical system, a preferred embodiment is that the projection engine satisfies the following expression:

[0083] and / or

[0084]

[0085] in, The optical power of the first lens. The optical power of the second lens. This is the optical power of the third lens.

[0086] In one embodiment, to further improve the imaging quality of the projection optical engine and control the cost of the optical system, a preferred implementation is to select conventional lens processing materials. The projection optical engine satisfies the following expression:

[0087] 1.67≤n1≤1.89, 35≤VD1≤57; and / or

[0088] 1.5≤n²≤1.6, 50≤VD²≤60; and / or

[0089] 1.61≤n3≤1.68, 19≤VD3≤26; and / or

[0090] 1.5≤n4≤1.6, 50≤VD4≤60; and / or

[0091] 1.61≤n5≤1.68, 19≤VD j ≤26

[0092] Wherein, n1 is the refractive index of the first lens, VD1 is the Abbe number of the first lens, n2 is the refractive index of the second lens, VD2 is the Abbe number of the second lens, n3 is the refractive index of the third lens, VD3 is the Abbe number of the third lens, n4 is the refractive index of the fourth lens, VD4 is the Abbe number of the fourth lens, and n5 is the refractive index of the fifth lens, VD5 is the Abbe number of the fifth lens.

[0093] In one embodiment, the projection optical engine satisfies the following expression:

[0094] 0.9 ≤ f1 / EFL ≤ 1.6; and / or

[0095] 1.0 ≤ f2 / EFL ≤ 1.7; and / or

[0096] -1≤f3 / EFL≤-0.4; and / or

[0097] 2 ≤ f4 / EFL ≤ 3.4; and / or

[0098] 7≤f5 / EFL≤13

[0099] Wherein, f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, and EFL is the effective focal length of the projection optical engine. The projection optical engine provided in this embodiment facilitates the rational allocation of optical power between the positive and negative lenses, achieving a heat-free design for the projection optical engine and enabling the lens to operate well under harsh temperatures.

[0100] In one embodiment, the projection optical engine satisfies the following expression:

[0101]

[0102] Among them, c 31 Let c be the curvature of the center point of the object-side surface of the third lens. 32 The curvature is the center point of the image side surface of the third lens. The projection optical engine provided in this embodiment can effectively suppress "ghosting" in the optical system, especially suppressing some of the "ghosting" generated by reflections between the first, second, and third lenses, thereby improving the imaging quality of the optical system.

[0103] In one embodiment, the projection optical engine satisfies the following expression:

[0104] and / or

[0105]

[0106] Among them, c 11 Let c be the curvature of the center point of the object-side surface of the first lens. 12 Let c be the curvature of the center point of the image-side surface of the first lens. 21 Let c be the curvature of the center point of the object-side surface of the second lens. 22 Let be the curvature of the center point of the image-side surface of the second lens. The projection optical engine provided in this embodiment can achieve miniaturization and alleviate the sensitivity of lens assembly, thereby improving the imaging quality of the optical system.

[0107] In practice, to improve image quality and reduce the weight of the projection optical engine, the preferred embodiment is that the first, second, third, fourth, and fifth lenses are all aspherical lenses. Since aspherical lenses offer advantages over spherical lenses, such as spherical aberration correction, system miniaturization, and weight reduction, the aspherical lenses used in this embodiment exhibit better imaging performance and image quality compared to spherical lenses.

[0108] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings, tables, and specific embodiments. Table 1 shows the optomechanical parameters. Table 2 shows the aspherical coefficients. Table 3 shows the system parameters. Table 4 shows the spectral range emitted from the optomechanical image source surface.

[0109] Table 1 shows the optomechanical parameters.

[0110]

[0111]

[0112] Table 2 Aspherical Coefficients

[0113] 2 -0.815 0 2.963E-03 -3.883E-04 8.082E-06 7.933E-06 -8.064E-07 3 -38.883 0 4.166E-03 -6.217E-04 6.606E-05 4.202E-07 -4.713E-07 4 -0.537 0 -1.393E-03 -4.009E-04 5.757E-04 -1.389E-04 1.164E-05 5 -61.078 0 -4.538E-03 3.127E-03 -8.729E-04 1.380E-04 -7.271E-06 6 -40.419 0 2.527E-02 -1.109E-02 3.116E-03 -3.564E-04 8.049E-06 7 -0.413 0 1.134E-03 5.199E-04 -4.106E-03 3.362E-03 -6.340E-04 8 -3.948 0 -2.424E-02 4.733E-03 -9.075E-04 1.316E-03 -3.068E-04 9 6.019 0 -4.652E-02 7.980E-03 -1.292E-06 3.102E-04 -1.250E-04 10 -2.666 0 -3.864E-02 4.486E-03 -5.727E-03 2.680E-03 -5.276E-04 11 2.036 0 -4.644E-02 -2.947E-03 -1.709E-03 6.062E-04 -9.127E-05

[0114] Table 3 System Parameters

[0115] <![CDATA[I mgh ]]> 1.651mm <![CDATA[H FOV ]]> 14° EPD 4.5mm

[0116] Table 4. Spectral range of light emitted from the optomechanical image source surface.

[0117]

[0118]

[0119] Figure 2 This is a schematic diagram of the optical path of the projection optical engine provided in an embodiment of this application. Figure 3 This diagram illustrates the modulation transfer function of a projection optical engine provided in an embodiment of this application. The lowest value of the modulation transfer function in this application is 0.7. The higher the curve of the modulation transfer function, the clearer the image. Figure 4a This is a schematic diagram of the field curvature of the projection optical engine provided in an embodiment of this application. Figure 4b This is a schematic diagram illustrating the distortion of the projection optical engine provided in an embodiment of this application. Figure 4b It can be seen that the distortion is less than 2%. Since the smaller the distortion, the better the shape preservation effect. Figure 5 This is an axial chromatic aberration diagram of the projection optical engine provided in an embodiment of this application. Figure 5 It can be seen that the maximum offset for different wavelengths is 18μm. The smaller the axial chromatic difference, the higher the image quality. Figure 6 This is a chromatic aberration diagram provided for an embodiment of this application. For example... Figure 6 As shown, the maximum offset for different wavelengths is 2.2 μm. The smaller the chromatic aberration along the vertical axis, the higher the image quality. Figure 7 This is a schematic diagram of the relative illuminance of the projection engine provided in an embodiment of this application. The ratio of illuminance at the image edge to illuminance at the image center exceeds 90%. The higher the ratio of illuminance at the image edge to illuminance in the image, the higher the uniformity of the image. Figure 8a The defocus curve of the projection optical engine provided in this embodiment of the application at -10°C is shown. Figure 8b The defocus curve of the projection optical engine at 20°C provided in the embodiments of this application; Figure 8c The defocus curve of the projection optical engine provided in this embodiment of the application at 60°C. Figure 8a , 8b As can be seen from 8c, the projection optical engine provided by this application can achieve good operation under different ambient temperatures.

[0120] In summary, the projection optical engine based on MicroLED screen provided in this application is miniaturized, lightweight, and has high image quality. It is also capable of operating well in harsh temperatures, which is beneficial for further improving the effect of near-eye augmented reality display for users.

[0121] The foregoing has provided a detailed description of a projection optical engine provided in this application. The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

[0122] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A projection optical engine, comprising an aperture and an image source, characterized in that, It also includes an optical lens group, wherein the number of lenses with optical power in the optical lens group is 5, and the optical lens group includes: The first lens has positive optical power; The second lens has positive optical power; The third lens has negative optical power; The fourth lens has positive optical power; The fifth lens has positive optical power; The optical lens group satisfies: ； Wherein, the effective focal length of the projection optical engine is The distance from the aperture surface of the projection optical engine to the image source surface of the projection optical engine on the optical axis is... ; The projection optical engine satisfies the following expression: ; and / or ； in, The optical power of the first lens is... The optical power of the second lens is [value missing]. The optical power of the third lens is denoted as .

2. The projection optical engine according to claim 1, characterized in that, Along the direction from the object side to the image side of the projection optical engine, the aperture stop, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the image source are placed in sequence.

3. The projection optical engine according to claim 2, characterized in that, The projection optical engine satisfies the following expression: ； Wherein, the effective focal length of the projection optical engine is The diameter of the light aperture of the aperture is .

4. The projection optical engine according to claim 1, characterized in that, The projection optical engine satisfies the following formula: ; and / or ; and / or ； in, The distance is the distance from the center point of the aperture plane to the center point of the image source. It is half the diagonal length of the effective projection area of ​​the image source of the projection engine. It is half of the field of view in the diagonal direction of the projection optical engine. The distance between the center point of the image-side lens surface of the third lens of the projection optical engine and the center point of the object-side lens surface of the fourth lens.

5. The projection optical engine according to claim 1, characterized in that, The projection optical engine satisfies the following expression: , ; and / or , ; and / or , ; and / or , ; and / or ， ； in, Let be the refractive index of the first lens. Let be the Abbe number of the first lens, where Let be the refractive index of the second lens. Let be the Abbe number of the second lens, where The refractive index of the third lens is... Let be the Abbe number of the third lens, where The refractive index of the fourth lens is... Let be the Abbe number of the fourth lens, where The refractive index of the fifth lens is... Let be the Abbe number of the fifth lens.

6. The projection optical engine according to claim 1, characterized in that, The projection optical engine satisfies the following expression: ; and / or ; and / or ; and / or ; and / or ； in, The effective focal length of the first lens is... The effective focal length of the second lens is... The effective focal length of the third lens is... The effective focal length of the fourth lens is... The effective focal length of the fifth lens is... The effective focal length of the projection optical engine is given.

7. The projection optical engine according to claim 1, characterized in that, The projection optical engine satisfies the following formula: ； in, Let be the curvature of the center point of the object-side surface of the third lens. Let be the curvature of the center point of the image-side surface of the third lens.

8. The projection optical engine according to claim 1, characterized in that, The projection optical engine satisfies the following formula: ; and / or ； Among them, the Let be the curvature of the center point of the object-side surface of the first lens. Let be the curvature of the center point of the image-side surface of the first lens. Let be the curvature of the center point of the object-side surface of the second lens. Let be the curvature of the center point of the image-side surface of the second lens.

9. The projection optical engine according to claim 1, characterized in that, The first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all aspherical lenses.

Images