Projection lens assembly, optical engine and near-eye display apparatus

Abstract

Disclosed in the present application are a projection lens assembly, an optical engine and a near-eye display apparatus. The projection lens assembly comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens; a diaphragm, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and an image source are sequentially arranged from an object side to an image side; and an object-side surface of the first lens is a convex surface, an object-side surface of the second lens is a convex surface, an image-side surface of the third lens is a concave surface, and an image-side surface of the fifth lens is an M-shaped curved surface.

Description

Projection lenses, optical engines, and near-eye display devices

[0001] This application claims priority to Chinese Patent Application No. 202411998463.1, filed with the Chinese Patent Office on December 31, 2024, entitled “Projection Lens, Optical Engine and Near-Eye Display Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of micro-projection display technology, and more particularly to a projection lens, optical engine, and near-eye display device. Background Technology

[0003] Near-eye display devices, such as AR (Augmented Reality) and VR (Virtual Reality) devices, include an optical engine and an optical waveguide. The optical engine is used to generate specific images and emit corresponding light signals, while the optical waveguide is used to directionally transmit the light signals emitted by the optical engine to the human eye for normal imaging, thus realizing near-eye display images.

[0004] However, the uniformity of images projected by current optical engine lenses is low, affecting the brightness distribution of the image and the viewing experience; moreover, the performance of various projection parameters of optical engine lenses is not high, affecting the image quality. Summary of the Invention

[0005] The first objective of this application is to provide a projection lens that addresses the technical problem of low uniformity in images projected by an optical engine lens.

[0006] To achieve the above objectives, the solution provided in this application is as follows:

[0007] A projection lens is applied to an optical engine, the optical engine including an aperture stop and an image source, the projection lens including a first lens, a second lens, a third lens, a fourth lens and a fifth lens, the aperture stop, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the image source being arranged sequentially from the object side to the image side along the optical axis;

[0008] The first lens, the second lens, the fourth lens, and the fifth lens all have positive optical power; the third lens has negative optical power.

[0009] The object-side surface of the first lens is convex, the object-side surface of the second lens is convex, the image-side surface of the third lens is concave, and the image-side surface of the fifth lens is an M-shaped curved surface.

[0010] The second objective of this application is to provide an optical engine, including an aperture, an image source, and the aforementioned projection lens.

[0011] The third objective of this application is to provide a near-eye display device, which includes an optical waveguide and the aforementioned optomechanical system. The optical waveguide is disposed on the side of the aperture away from the first lens and is used to receive a light beam emitted by the image source and transmit the light beam to the human eye for near-eye display.

[0012] The projection lens provided in this application has the following beneficial effects:

[0013] In the projection lens of this embodiment, the combination of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens can modulate the light to control the angle between the main ray and the edge ray of the lens and the optical axis to be limited to a certain range. This range is determined by the light intensity distribution curve of the image source. Specifically, the angle range in which the light intensity drops to 90% of the center light intensity can be selected so that the light intensity received by each field of view of the projection lens is close, thereby making the brightness distribution of the virtual image image projected by the projection lens uniform from the center to the edge, and improving the uniformity of the virtual image image projected by the projection lens. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art 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 the structures shown in these drawings without creative effort.

[0015] Figure 1 is a schematic diagram of an optical engine provided in an embodiment of this application;

[0016] Figure 2 is a schematic diagram of the optical path of the optomechanic shown in Figure 1;

[0017] Figure 3 is a schematic diagram of another structure of the optical engine provided in an embodiment of this application;

[0018] Figure 4 is a light intensity distribution curve of the image source in the embodiment provided in this application;

[0019] Figure 5 is a light receiving angle curve of the projection lens in Embodiment 1 of this application;

[0020] Figure 6 is a simulation diagram of the uniformity of the projection lens in Embodiment 1 provided in this application;

[0021] Figure 7 is a modulation transfer function curve of the projection lens in Embodiment 1 provided in this application;

[0022] Figure 8 is a defocus curve of the projection lens in Embodiment 1 provided in this application;

[0023] Figure 9 is an optical distortion and astigmatism curve of the projection lens in Embodiment 1 provided in this application;

[0024] Figure 10 is a TV distortion diagram of the projection lens in Embodiment 1 provided in this application;

[0025] Figure 11 is an axial chromatic difference curve of the projection lens in Embodiment 1 provided in this application;

[0026] Figure 12 is a chromatic aberration curve of the projection lens in Embodiment 1 provided in this application;

[0027] Figure 13 is a thermal defocusing curve of the optical engine at -10°C in Embodiment 1 of this application;

[0028] Figure 14 is a thermal defocusing curve of the optical engine at 20°C in Embodiment 1 of this application;

[0029] Figure 15 is a thermal defocusing curve of the optical engine at 50°C in Embodiment 1 of this application;

[0030] Figure 16 is a light receiving angle curve of the projection lens in Embodiment 2 provided in this application;

[0031] Figure 17 is a schematic diagram of the uniformity simulation of the projection lens in Embodiment 2 provided in this application;

[0032] Figure 18 is a modulation transfer function curve of the projection lens in Embodiment 2 provided in this application;

[0033] Figure 19 is a defocus curve of the projection lens in Embodiment 2 provided in this application;

[0034] Figure 20 is an optical distortion and astigmatism curve of the projection lens in Embodiment 2 provided in this application;

[0035] Figure 21 is a TV distortion diagram of the projection lens in Embodiment 2 provided in this application;

[0036] Figure 22 is an axial chromatic difference curve of the projection lens in Embodiment 2 provided in this application;

[0037] Figure 23 is a chromatic aberration curve of the projection lens in Embodiment 2 provided in this application;

[0038] Figure 24 is a thermal defocusing curve of the optical engine at -10°C in Embodiment 2 of this application;

[0039] Figure 25 is a thermal defocusing curve of the optical engine at 20°C in Embodiment 2 of this application;

[0040] Figure 26 is a graph showing the defocusing curve of the optical engine at 50°C in Embodiment 2 provided in this application.

[0041] The reference numerals are as follows: 100, aperture stop; 200, image source; 10, first lens; 20, second lens; 30, third lens; 40, fourth lens; 50, fifth lens. Detailed Implementation

[0042] 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 a part of the embodiments of this application, and not all of the 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 scope of protection of this application.

[0043] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0044] It should also be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or may be connected to an intermediary component. When a component is referred to as being "connected to" another component, it can be directly connected to the other component or indirectly connected to the other component through an intermediary component.

[0045] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0046] Currently, near-eye display modules consist of an optical engine and an optical waveguide, with the optical engine used to input image information into the optical waveguide. In related technologies, the brightness uniformity of the image projected by the optical engine lens is low, which is difficult to compensate for the extremely low uniformity of the optical waveguide, resulting in low uniformity of the image entering the eye and affecting the viewing experience. Simultaneously, the MTF (modulation transfer function), distortion, luminous efficacy, and thermal drift parameters of the optical engine lens remain at low levels, and after performance losses due to the optical waveguide, they cannot meet high-specification imaging quality requirements.

[0047] As shown in Figure 1, based on this, this application embodiment provides a projection lens, an optical engine, and a near-eye display device. The projection lens can be a MicroLED lens, and this embodiment is not specifically limited to it. It is applied to the optical engine of the near-eye display device. As the lens of the optical engine, the optical engine can be a monochrome optical engine or a color optical engine. Further, along the optical axis, the projection lens is disposed between the aperture 100 of the optical engine and the image source 200. The projection lens is adapted to the image source 200. The image source 200 can be a display screen using self-emissive display technology, such as a MicroLED display screen, and this embodiment is not specifically limited to it.

[0048] Specifically, the projection lens, based on the light intensity distribution curve of the image source 200, without significantly increasing the size of the optical engine, sets up a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, and a fifth lens 50, and optimizes each optical lens to limit the angle between the lens's principal ray and the edge ray and the optical axis to a certain range. This ensures that the light intensity received by each field of view of the projection lens is similar, resulting in a uniform brightness distribution from the center to the edge of the virtual image projected by the projection lens, thus improving the uniformity of the virtual image projected by the projection lens.

[0049] The following detailed description of some embodiments of this application is provided with reference to Figures 1 to 26. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0050] As shown in Figure 1, the projection lens provided in this embodiment includes a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, and a fifth lens 50. Along the optical axis, the aperture 100, the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, the fifth lens 50, and the image source 200 are arranged sequentially from the object side (i.e., the imaging side) to the image side (i.e., the image source side). Specifically, referring to Figure 1, the object side of the first lens 10 can be spaced apart from the light-transmitting aperture of the aperture 100. Referring to Figure 3, the object side of the first lens 10 can also protrude from the light-transmitting aperture of the aperture 100. This embodiment does not have specific limitations. The first lens 10, the second lens 20, the fourth lens 40, and the fifth lens 50 all have positive optical power; the third lens 30 has negative optical power. The first lens 10, the second lens 20, the fourth lens, and the fifth lens 50 all converge the light, while the third lens 30 diverges the light.

[0051] Furthermore, the object-side surface of the first lens 10 is convex, the object-side surface of the second lens 20 is convex, the image-side surface of the third lens 30 is concave, and the image-side surface of the fifth lens 50 is an M-shaped curved surface. This can be understood as the object-side surface of the first lens 10 bulging away from the image source 200, the object-side surface of the second lens 20 bulging away from the image source 200, and the image-side surface of the third lens 30 concave away from the image source 200. Along the optical axis, the image-side surface faces the image source 200, and the object-side surface faces away from the image source 200.

[0052] In this embodiment, referring to Figure 2, the light emitted by the image source 200 can be transmitted sequentially through the fifth lens 50, the fourth lens 40, the third lens 30, the second lens 20, and the first lens 10. The combination of five lenses can modulate the light to reduce the angle between the light emitted by the image source 200 and the optical axis, so as to control the angle between the main ray and the edge ray of the lens and the optical axis to be limited within a certain range. This range is determined by the light intensity distribution curve of the image source 200. Specifically, the angle range in which the light intensity drops to 90% of the center light intensity can be selected so that the light intensity received by each field of view of the projection lens is close, thereby adapting the light intensity received by each position from the center to the edge of the virtual image screen projected by the projection lens of the image source 200 to be close, and thus the brightness distribution from the center to the edge of the virtual image screen projected by the projection lens is uniform, improving the uniformity of the virtual image screen projected by the projection lens.

[0053] As shown in Figure 1, in some embodiments, the image-side surface of the first lens 10 is convex, that is, the image-side surface of the first lens 10 protrudes towards the image source 200, which is beneficial to control the angle between the main ray and the edge ray of the lens and the optical axis within a certain range, thereby improving the uniformity of the virtual image projected by the projection lens.

[0054] As shown in Figure 1, in some embodiments, the image-side surface of the second lens 20 is convex, that is, the image-side surface of the second lens 20 protrudes towards the image source 200, which is beneficial to control the angle between the main ray and the edge ray of the lens and the optical axis within a certain range, thereby improving the uniformity of the virtual image projected by the projection lens.

[0055] As shown in Figure 1, in some embodiments, the object side of the third lens 30 is convex, that is, the object side of the third lens 30 protrudes in the direction away from the image source 200, which is beneficial to control the angle between the main ray and the edge ray of the lens and the optical axis within a certain range, thereby improving the uniformity of the virtual image projected by the projection lens.

[0056] As shown in Figure 1, in some embodiments, the object-side surface of the fourth lens 40 is concave, and the image-side surface is convex. That is, the object-side surface of the fourth lens 40 is concave in the direction away from the aperture stop 100, and the image-side surface of the fourth lens 40 convex in the direction closer to the image source 200. In other embodiments, the object-side surface of the fourth lens 40 is convex, and the image-side surface is concave. That is, the object-side surface of the fourth lens 40 convex in the direction away from the image source 200, and the image-side surface of the fourth lens 40 concave in the direction away from the image source 200. This design helps to control the angles between the principal ray and the peripheral ray of the lens and the optical axis within a certain range, thereby improving the uniformity of the virtual image projected by the projection lens.

[0057] As shown in Figure 1, in some embodiments, the object-side surface of the fifth lens 50 is convex, that is, the object-side surface of the fifth lens 50 protrudes in a direction away from the image source 200. In other embodiments, the object-side surface of the fifth lens 50 is an M-shaped curved surface. These designs are beneficial for controlling the angles between the principal ray and the peripheral ray of the lens and the optical axis within a certain range, thereby improving the uniformity of the virtual image projected by the projection lens.

[0058] As shown in Figure 1, in one specific embodiment, the image-side surface of the fifth lens 50 includes a central region (not shown) and an edge region (not shown). The edge region surrounds the periphery of the central region. The central region is concave in a direction away from the image source 200, and the edge region protrudes in a direction closer to the image source 200.

[0059] Referring to Figure 1, in some embodiments, the first lens 10, the second lens 20, the third lens 30 and the fourth lens 40 are all plastic lenses, and the fifth lens 50 is a glass lens, which helps to improve the uniformity of the virtual image projected by the projection lens.

[0060] Referring to Figure 1, in some embodiments, the field of view (FOV) along the diagonal direction of the projection lens is defined as the projection lens, which satisfies the condition that 20° ≤ FOV ≤ 35°. For example, in the embodiments of this application, the FOV is set to 25°, 28°, or 30°.

[0061] Referring to Figure 1, in some embodiments, the diameter of the light-transmitting aperture of the aperture 100 is EPD, and the projection lens satisfies: 3.0mm≤EPD≤5.5mm.

[0062] Referring to Figure 1, in some embodiments, the aperture diameter of the aperture 100 is EPD, the effective focal length of the projection lens is EFL, and the projection lens satisfies the following expression:

[0063] As in the embodiments of this application, The value can be set to 1.4, 1.8, or 2.0, as disclosed in this embodiment. The smaller the value, the larger the aperture of the projection lens, the higher the light efficiency, and the brighter the projected image under rated power consumption. The above range can meet the requirements of most optical waveguides for the optical engine input light flux.

[0064] Referring to Figure 1, in some embodiments, the refractive index of the first lens 10 is disclosed as n1, and the Abbe number of the first lens 10 is VD1; the refractive index of the second lens 20 is n2, and the Abbe number of the second lens 20 is VD2; the refractive index of the third lens 30 is n3, and the Abbe number of the third lens 30 is VD3; the refractive index of the fourth lens 40 is n4, and the Abbe number of the fourth lens 40 is VD4; the refractive index of the fifth lens 50 is n5, and the Abbe number of the fifth lens 50 is VD5; the projection lens satisfies the following relationship:

[0065] 1.5≤n1≤1.6, 50≤VD1≤65; and / or,

[0066] 1.5≤n²≤1.6, 50≤VD²≤65; and / or,

[0067] 1.63≤n3≤1.7, 20≤VD3≤25; and / or,

[0068] 1.63≤n4≤1.7, 20≤VD4≤25; and / or,

[0069] 1.5≤n5≤1.6, 50≤VD5≤65.

[0070] In this embodiment, when the refractive index and Abbe number of the first lens 10 meet the above-mentioned range, it is advantageous for the first lens 10 to be made of glass; when the refractive index and Abbe number of the second lens 20, the third lens 30, the fourth lens 40 and the fifth lens 50 meet the above-mentioned range, it is advantageous for the second lens 20, the third lens 30, the fourth lens 40 and the fifth lens 50 to be made of plastic.

[0071] Referring to Figure 1, this embodiment discloses that the object-side half-aperture of the first lens 10 is R11, and the image-side half-aperture of the first lens 10 is R12; the object-side half-aperture of the second lens 20 is R21, and the image-side half-aperture of the second lens 20 is R22; the object-side half-aperture of the third lens 30 is R31, and the image-side half-aperture of the third lens 30 is R32; the object-side half-aperture of the fourth lens 40 is R41, and the image-side half-aperture of the fourth lens 40 is R42; the object-side half-aperture of the fifth lens 50 is R51, and the image-side half-aperture of the fifth lens 50 is R52. Simultaneously, the aperture diameter of the stop 100 is EPD, and the projection lens satisfies the following relationship:

[0072] And / or,

[0073] And / or,

[0074] And / or,

[0075] And / or,

[0076] In this embodiment, when the ratio between the half-aperture R and EPD of the surface of each projection lens meets the above range, it is beneficial for the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, and the fifth lens 50 to modulate the light so that the angle between the principal ray and the edge ray and the optical axis is within a certain range, thereby improving the uniformity of the virtual image projected by the projection lens.

[0077] Referring to Figure 1, in some embodiments, this embodiment discloses the half-aperture R of the object-side and image-side surfaces of each lens. Furthermore, this embodiment also discloses the curvature of the center point of the object-side surface of the first lens 10 as C11, the curvature of the center point of the image-side surface of the first lens 10 as C12, the curvature of the center point of the object-side surface of the second lens 20 as C21, the curvature of the center point of the image-side surface of the second lens 20 as C22, the curvature of the center point of the object-side surface of the third lens 30 as C31, the curvature of the center point of the image-side surface of the third lens 30 as C32, the curvature of the center point of the object-side surface of the fourth lens 40 as C41, the curvature of the center point of the image-side surface of the fourth lens 40 as C42, and the curvature of the center point of the object-side surface of the fifth lens 50 as C51, the curvature of the center point of the image-side surface of the fifth lens 50 as C52. The projection lens satisfies the following relationship:

[0078] And / or,

[0079] And / or,

[0080] And / or,

[0081] And / or,

[0082] In this embodiment, along the optical axis, when the ratio of the curvature C of the object side to the half-aperture R of the object side, and the ratio of the curvature C of the image side to the half-aperture R of the image side, satisfy the above-mentioned range in the same optical lens (first lens 10, second lens 20, third lens 30, fourth lens 40 or fifth lens 50), it can ensure that the lens scaling remains unchanged. It also helps the first lens 10, second lens 20, third lens 30, fourth lens 40 and fifth lens 50 to modulate the light so that the angle between the principal ray and the edge ray of the lens and the optical axis is within a certain range, thereby improving the uniformity of the virtual image projected by the projection lens.

[0083] Referring to Figure 1, further, based on the half-aperture R of the object-side and image-side surfaces of each lens disclosed in this embodiment, this embodiment also discloses that the center thickness of the object-side surface of the first lens 10 is T11, and the thickness of the image-side surface of the first lens 10 is T12; the center thickness of the object-side surface of the second lens 20 is T21, and the center thickness of the image-side surface of the second lens 20 is T22; the center thickness of the object-side surface of the third lens 30 is T31, and the center thickness of the image-side surface of the third lens 30 is T32; the thickness of the object-side surface of the fourth lens 40 is T41, and the center thickness of the image-side surface of the fourth lens 40 is T42; the center thickness of the object-side surface of the fifth lens 50 is T51, and the center thickness of the image-side surface of the fifth lens 50 is T52; the projection lens satisfies the following relationship:

[0084] And / or,

[0085] And / or,

[0086] And / or,

[0087] And / or,

[0088] In this embodiment, when the ratio between the center thickness T and half-aperture R of the surface of each projection lens meets the above range, it is beneficial for the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, and the fifth lens 50 to modulate the light to control the angle between the main ray and the edge ray of the lens and the optical axis, thereby improving the uniformity of the virtual image projected by the projection lens.

[0089] As shown in Figure 1, this application embodiment also provides an optical engine, including an aperture 100, an image source 200, and a projection lens as described in any of the above embodiments. By using the projection lens, the optical engine can improve the uniformity of the virtual image projected by the optical engine, thereby improving the quality of the virtual image projected by the optical engine.

[0090] As shown in Figure 1, this embodiment of the application also provides a near-eye display device, including an optical waveguide and the aforementioned optical engine. The optical waveguide is disposed on the side of the aperture 100 opposite to the first lens 10, for receiving a light beam emitted by the image source 200 and transmitting the light beam to the human eye for near-eye display. Because this embodiment uses the aforementioned optical engine, the near-eye display device can improve the uniformity of the virtual image projected by the near-eye display device, thereby improving the quality of the virtual image projected by the near-eye display device.

[0091] To further illustrate the effects of the projection lens and optical engine in this embodiment, this application also provides Embodiment 1 and Embodiment 2, as well as modulation transfer function curves, defocus curves, optical distortion and astigmatism curves, TV distortion diagrams, chromatic aberration curves, thermal drift defocus curves, etc., in conjunction with each embodiment to illustrate the effects, so as to make the effects of this embodiment more intuitive.

[0092] Example 1:

[0093] As shown in Figure 1, the projection lens in this embodiment is a MicroLED lens, and the image source 200 is a MicroLED display screen. The light intensity distribution curve of the MicroLED display screen (i.e., the light intensity distribution curve of the image source 200) is shown in Figure 4. As shown in Figure 4, the normalized relative intensity of the light beam with a received angle of light intensity in the range of -20° to 20° is close to 1, indicating that the light intensity of the light beam in the range of -20° to 20° is relatively strong.

[0094] In this embodiment, the projection lens is designed according to the light intensity distribution curve shown in Figure 4, including the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, and the fifth lens 50, to modulate the angles of the principal ray and the edge ray of the lens, so that the receiving light angle of the projection lens matches the light intensity angle distribution curve, thereby adapting the projection lens to the image source 200. The light receiving angle curve of the projection lens is shown in Figure 5.

[0095] Specifically, along the optical axis, from the aperture stop 100 to the image source 200, a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, and a fifth lens 50 are sequentially spaced. The parameters of each lens are shown in Table 1-1, and the aspherical coefficients of each lens are shown in Table 1-2. In Table 1-1, STOP represents the aperture stop 100, IMG represents the image source 200, the object-side surface S1 of the first lens 10 is convex, the image-side surface S2 of the first lens 10 is convex, the object-side surface S3 of the second lens 20 is convex, the image-side surface S4 of the second lens 20 is convex, the object-side surface S5 of the third lens 30 is convex, the image-side surface S6 of the third lens 30 is concave, the object-side surface S7 of the fourth lens 40 is concave, the image-side surface S8 of the fourth lens 40 is convex, the object-side surface S9 of the fifth lens 50 is convex, and the image-side surface S10 of the fifth lens 50 is an M-shaped curved surface. The basic optical parameters of the projection lens shown in Table 1-1 are as follows: the diagonal field of view (FOV) of the projection lens is 25°, the aperture diameter (EPD) of the aperture 100 is 4.8 mm, and the F-number (F#, F-number, relative aperture) is 1.48. Table 1-2 is the aspherical coefficient table, which shows the aspherical coefficients of each lens surface of the projection lens in this embodiment.

[0096] Table 1-1

[0097] Table 1-2

[0098] In this embodiment, each surface of the lens is an even-order aspherical surface, and the surface shapes shown above satisfy the aspherical formula:

[0099] Where z is the sag of the lens surface under different apertures, c is the reciprocal of the radius of curvature R, r is the aperture in the radial direction, k is the conic coefficient, and A, B, C, D, E, F, G, H, and J are all higher-order coefficient terms.

[0100] Furthermore, the projection lens disclosed in Embodiment 1 was tested in conjunction with a MicroLED display screen.

[0101] Combining Figures 4 and 5, the normalized relative intensity of the light beam with a receiving angle in the range of -20° to 20° is close to 1. Moreover, the light receiving angle at various positions from the center to the edge of the projection lens is between 0° and 6°, indicating that the projection lens has high light efficiency. Here, the receiving angle is the angle between the light beam and the optical axis.

[0102] As shown in Figure 6, this embodiment discloses a uniformity simulation structure diagram. Combining Figures 5 and 6, the light receiving angles at various positions from the center to the edge of the projection lens are between 0° and 6°. The smaller the light receiving angle, the closer the light intensity received by each field of view of the projection lens is. As a result, the smaller the difference in illuminance between various positions from the center to the edge of the virtual image projected by the projection lens, the better the uniformity of the virtual image.

[0103] Furthermore, the illuminance data for each point in Figure 6 are shown in Table 1-3:

[0104] Table 1-3

[0105] Based on relevant technologies and calculated according to ANSI 13-point standards, the brightness uniformity values ​​are as follows:

[0106] In the above formula, min(13Point) represents the minimum value among the 13 values ​​in Table 1-3, and max(13Point) represents the maximum value among the 13 values ​​in Table 1-3. From the formula, it can be seen that the brightness uniformity of the virtual image projected by the MicroLED lens in this embodiment is 97%. This indicates that this embodiment can improve the brightness uniformity of the virtual image projected by the current MicroLED lens from 80% to 97%, thus demonstrating that the projection lens of this embodiment can greatly improve the brightness uniformity of the virtual image projected by the lens.

[0107] As shown in Figure 7, the modulation transfer function (MTF) curve of the projection lens in Embodiment 1 of this embodiment is illustrated. The MTF refers to the relationship between modulation density and the number of line logs per millimeter in the image. It can be used to evaluate the imaging quality of the lens and measure its ability to reproduce object details. In Figure 7, the lowest value of the MTF is 0.8. The closer the MTF curve is to 1, the better. A curve closer to 1 indicates better lens imaging quality. Therefore, a higher MTF curve indicates a clearer image, demonstrating the high clarity of the virtual image projected by the projection lens in this embodiment.

[0108] As shown in Figure 8, the defocus curve of the projection lens in Embodiment 1 disclosed in this embodiment is shown. In Figure 8, the horizontal axis is the defocus distance and the vertical axis is the OTF (Optical Transfer Function) modulus. The defocus curve represents the change of MTF when the image plane deviates from the design value. In Figure 8, the defocus curves of each field of view have good convergence, indicating that the virtual image projected by the projection lens of this embodiment has high overall clarity across the entire field of view.

[0109] As shown in Figure 9, the optical distortion and astigmatism curve of the projection lens in Embodiment 1 disclosed in this embodiment are shown. In Figure 9, the optical distortion is within 1.1%. The smaller the distortion, the better the shape preservation effect, indicating that the projection lens of this embodiment can project virtual image images that are not obviously distorted when viewed.

[0110] As shown in Figure 10, the TV distortion diagram of the projection lens in Embodiment 1 disclosed in this embodiment shows that the virtual image projected by the projection lens in this embodiment is clear and without obvious distortion.

[0111] As shown in Figure 11, the axial chromatic aberration curve of the projection lens in Embodiment 1 disclosed in this embodiment is shown. In Figure 11, the vertical axis represents the longitudinal spherical aberration, and the horizontal axis represents the focal point offset. In Figure 11, the maximum distance between the curves is less than 0.003mm, and the spacing is small, indicating that the virtual image projected by the projection lens of this embodiment has good chromatic aberration.

[0112] As shown in Figure 12, the vertical axis chromatic difference curve of the projection lens in Embodiment 1 disclosed in this embodiment shows that the maximum offset of different wavelengths is 0.001mm. The smaller the vertical axis chromatic difference, the higher the image quality and the clearer the image, indicating that the virtual image projected by the projection lens of this embodiment is clear and has good image quality.

[0113] As shown in Figures 13, 14 and 15, the thermal drift defocus curves of the optical engine with the projection lens of Embodiment 1 disclosed in this embodiment are shown at -10°, 20° and 50° respectively. It can be seen from Figures 13 to 15 that the thermal drift performance of the optical engine is improved by using the projection lens of this embodiment. The optical engine can work well under different ambient temperatures, ensuring the clarity of the projected virtual image.

[0114] As can be seen from the above embodiments, the projection lens of this embodiment can improve the brightness uniformity of the virtual image projected by the lens, and the performance parameters such as MTF (Modulation Transfer Function), distortion, light efficiency, and thermal drift can be at a high level. Therefore, when the optical engine of this projection lens is used in conjunction with the optical waveguide, the image quality entering the eye can be improved, and the high-specification imaging quality requirements can be met.

[0115] Example 2:

[0116] As shown in Figure 3, the main differences between this embodiment and Embodiment 1 are: the light receiving angle curve of the projection lens, the basic optical parameters of the projection lens, and the specific parameters of each optical lens.

[0117] Specifically, the light receiving angle curve of the projection lens is shown in Figure 16. The light receiving angle of this embodiment is also adapted to the light intensity angle distribution curve shown in Figure 4, so that the projection lens of this embodiment is also adapted to the image source 200.

[0118] Specifically, the basic optical parameters of the projection lens are as follows: the diagonal field of view (FOV) is 26°, the aperture diameter (EPD) of the 100 aperture is 5.0 mm, and the F-number (F#, F-number, relative aperture) is 1.47. The specific parameters of each optical lens are shown in Table 2-1.

[0119] Table 2-1

[0120] Table 2-2

[0121] Table 2-2 above is the aspherical coefficient table, which shows the aspherical coefficients of each lens surface of the projection lens in this embodiment.

[0122] Furthermore, the projection lens disclosed in Embodiment 2 was tested in conjunction with a MicroLED display screen.

[0123] Combining Figures 4 and 16, the normalized relative intensity of the light beam with a receiving angle in the range of -20° to 20° is close to 1. Moreover, the light receiving angle at various positions from the center to the edge of the projection lens is between 0° and 6°, indicating that the projection lens has high light efficiency. Here, the receiving angle is the angle between the light beam and the optical axis.

[0124] As shown in Figure 17, this embodiment discloses a uniformity simulation structure diagram. Combining Figures 16 and 17, the light receiving angles at various positions from the center to the edge of the projection lens are between 0° and 6°. The smaller the light receiving angle, the closer the light intensity received by each field of view of the projection lens is. As a result, the smaller the difference in illuminance between various positions from the center to the edge of the virtual image projected by the projection lens, the better the uniformity of the virtual image.

[0125] Furthermore, the illuminance data for each point in Figure 17 are shown in Table 2-3:

[0126] Table 2-3

[0127] Based on relevant technologies and calculated according to ANSI 13-point standards, the brightness uniformity values ​​are as follows:

[0128] In the above formula, min(13Point) represents the minimum value among the 13 values ​​in Table 2-3, and max(13Point) represents the maximum value among the 13 values ​​in Table 2-3. From the formula, it can be seen that the brightness uniformity of the virtual image projected by the MicroLED lens in this embodiment is 96.4%. This indicates that this embodiment can improve the brightness uniformity of the virtual image projected by the current MicroLED lens from 80% to 96.4%, thus demonstrating that the projection lens of this embodiment can greatly improve the brightness uniformity of the virtual image projected by the lens.

[0129] As shown in Figure 18, the modulation transfer function (MTF) curve of the projection lens in Embodiment 2 of this embodiment is illustrated. The MTF refers to the relationship between modulation density and the number of line logs per millimeter in the image. It can be used to evaluate the imaging quality of the lens and measure its ability to reproduce object details. In Figure 18, the lowest value of the MTF is 0.7. The closer the MTF curve is to 1, the better. A curve closer to 1 indicates better lens imaging quality. Therefore, a higher MTF curve indicates a clearer image, indicating that the virtual image projected by the projection lens in this embodiment is relatively clear.

[0130] As shown in Figure 19, the defocus curve of the projection lens in Embodiment 2 disclosed in this embodiment is shown. In Figure 19, the horizontal axis is the defocus distance and the vertical axis is the OTF (Optical Transfer Function) modulus. The defocus curve represents the change of MTF when the image plane deviates from the design value. In Figure 19, the defocus curves of each field of view have good convergence, indicating that the virtual image projected by the projection lens of this embodiment is relatively clear.

[0131] As shown in Figure 20, the optical distortion and astigmatism curve of the projection lens in Embodiment 2 disclosed in this embodiment are shown. In Figure 20, the optical distortion is within 2%. The smaller the distortion, the better the shape preservation effect, indicating that the projection lens of this embodiment can project virtual image images with no obvious distortion when viewed.

[0132] As shown in Figure 21, the TV distortion diagram of the projection lens in Embodiment 2 disclosed in this embodiment shows that the virtual image projected by the projection lens in this embodiment is clear and without obvious distortion.

[0133] As shown in Figure 22, the axial chromatic aberration curve of the projection lens in Embodiment 2 disclosed in this embodiment is shown. In Figure 22, the vertical axis represents the longitudinal spherical aberration, and the horizontal axis represents the focal point offset. In Figure 22, the maximum distance between the curves is less than 0.004mm, and the spacing is small, indicating that the virtual image projected by the projection lens of this embodiment has good chromatic aberration.

[0134] As shown in Figure 23, the vertical axis chromatic difference curve of the projection lens in Embodiment 2 disclosed in this embodiment shows that the maximum offset of different wavelengths is 0.003mm. The smaller the vertical axis chromatic difference, the higher the image quality and the clearer the image. This indicates that the virtual image projected by the projection lens of this embodiment is clear and has good image quality.

[0135] As shown in Figures 24 to 26, the thermal drift defocus curves of the optical engine with the projection lens of Embodiment 2 disclosed in this embodiment are shown at -10°, 20°, and 50°. It can be seen from Figures 24 to 26 that the thermal drift performance of the optical engine is improved by using the projection lens of this embodiment, and the optical engine can work well under different ambient temperatures to ensure the clarity of the projected virtual image.

[0136] As can be seen from the above embodiments, the projection lens of this embodiment can improve the brightness uniformity of the virtual image projected by the lens, and the performance parameters of the projection lens such as MTF (modulation transfer function), distortion, light efficiency, and thermal drift can be at a high level. Therefore, the use of the optical engine of this projection lens in conjunction with the optical waveguide can improve the image quality entering the eye and meet the high-specification imaging quality requirements.

[0137] The above description is merely a preferred embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the content of this application's specification and drawings under the concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A projection lens applied to an optical engine, the optical engine including an aperture and an image source, the projection lens including a first lens, a second lens, a third lens, a fourth lens and a fifth lens, wherein the aperture, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the image source are arranged sequentially from the object side to the image side along the optical axis; The first lens, the second lens, the fourth lens, and the fifth lens all have positive optical power; the third lens has negative optical power. The object-side surface of the first lens is convex, the object-side surface of the second lens is convex, the image-side surface of the third lens is concave, and the image-side surface of the fifth lens is an M-shaped curved surface.

2. The projection lens as described in claim 1, wherein, The image-side surface of the first lens is convex; and / or, the image-side surface of the second lens is convex.

3. The projection lens as described in claim 1, wherein, The object-side surface of the third lens is convex; and / or, the object-side surface of the fifth lens is convex or M-shaped curved.

4. The projection lens as described in claim 1, wherein, The image-side surface of the fourth lens is convex, and the object-side surface of the fourth lens is concave; or, the image-side surface of the fourth lens is concave, and the object-side surface of the fourth lens is convex.

5. The projection lens as described in claim 1, wherein, The first lens is a glass lens, while the second, third, fourth, and fifth lenses are all plastic lenses.

6. The projection lens as described in claim 1, wherein, The projection lens satisfies the following expression: 20°≤FOV≤35°; and / or, 3.0mm≤EPD≤5.5mm; Wherein, the field of view of the projection lens in the diagonal direction is FOV, and the diameter of the light-transmitting aperture of the aperture is EPD.

7. The projection lens as described in claim 1, wherein, The projection lens satisfies the following expression: Wherein, the diameter of the light-passing aperture of the aperture is EPD, and the effective focal length of the projection lens is EFL.

8. The projection lens as described in claim 1, wherein, The projection lens satisfies at least one of the following relationships: 1.5≤n1≤1.6, 50≤VD1≤65; and / or, 1.5≤n2≤1.6, 50≤VD2≤65; and / or, 1.63≤n3≤1.7, 20≤VD3≤25; and / or, 1.63≤n4≤1.7, 20≤VD4≤25; and / or, 1.5≤n5≤1.6, 50≤VD5≤65; Wherein, the refractive index of the first lens is n1, and the Abbe number of the first lens is VD1; the refractive index of the second lens is n2, and the Abbe number of the second lens is VD2; the refractive index of the third lens is n3, and the Abbe number of the third lens is VD3; the refractive index of the fourth lens is n4, and the Abbe number of the fourth lens is VD4; and the refractive index of the fifth lens is n5, and the Abbe number of the fifth lens is VD5.

9. The projection lens as described in claim 1, wherein, The projection lens satisfies at least one of the following relationships: And / or, And / or, And / or, And / or, Wherein, the object-side half-aperture of the first lens is R11, and the image-side half-aperture of the first lens is R12; the object-side half-aperture of the second lens is R21, and the image-side half-aperture of the second lens is R22; the object-side half-aperture of the third lens is R31, and the image-side half-aperture of the third lens is R32; the object-side half-aperture of the fourth lens is R41, and the image-side half-aperture of the fourth lens is R42; the object-side half-aperture of the fifth lens is R51, and the image-side half-aperture of the fifth lens is R52; and the aperture diameter of the stop is EPD.

10. The projection lens as claimed in claim 1, wherein, The projection lens satisfies at least one of the following relationships: And / or, And / or, And / or, And / or, Wherein, the curvature of the center point of the object side of the first lens is C11, the curvature of the center point of the image side of the first lens is C12, the curvature of the center point of the object side of the second lens is C21, the curvature of the center point of the image side of the second lens is C22, the curvature of the center point of the object side of the third lens is C31, the curvature of the center point of the image side of the third lens is C32, the curvature of the center point of the object side of the fourth lens is C41, the curvature of the center point of the image side of the fourth lens is C42, the curvature of the center point of the object side of the fifth lens is C51, and the curvature of the center point of the image side of the fifth lens is C52. The object-side half-aperture of the first lens is R11, and the image-side half-aperture of the first lens is R12; the object-side half-aperture of the second lens is R21, and the image-side half-aperture of the second lens is R22; the object-side half-aperture of the third lens is R31, and the image-side half-aperture of the third lens is R32; the object-side half-aperture of the fourth lens is R41, and the image-side half-aperture of the fourth lens is R42; the object-side half-aperture of the fifth lens is R51, and the image-side half-aperture of the fifth lens is R52.

11. The projection lens as claimed in claim 1, wherein, The projection lens satisfies at least one of the following relationships: And / or, And / or, And / or, And / or, Wherein, the center thickness of the object-side surface of the first lens is T11, and the thickness of the image-side surface of the first lens is T12; the center thickness of the object-side surface of the second lens is T21, and the center thickness of the image-side surface of the second lens is T22; the center thickness of the object-side surface of the third lens is T31, and the center thickness of the image-side surface of the third lens is T32; the thickness of the object-side surface of the fourth lens is T41, and the center thickness of the image-side surface of the fourth lens is T42; the center thickness of the object-side surface of the fifth lens is T51, and the center thickness of the image-side surface of the fifth lens is T52. The object-side half-aperture of the first lens is R11, and the image-side half-aperture of the first lens is R12; the object-side half-aperture of the second lens is R21, and the image-side half-aperture of the second lens is R22; the object-side half-aperture of the third lens is R31, and the image-side half-aperture of the third lens is R32; the object-side half-aperture of the fourth lens is R41, and the image-side half-aperture of the fourth lens is R42; the object-side half-aperture of the fifth lens is R51, and the image-side half-aperture of the fifth lens is R52.

12. An optical engine, wherein, It includes an aperture, an image source, and a projection lens as described in any one of claims 1-11.

13. A near-eye display device, wherein, Includes an optical waveguide and an optical engine according to claim 12, wherein the optical waveguide is disposed on the side of the aperture away from the first lens, for receiving a light beam emitted by the image source and transmitting the light beam to the human eye for near-eye display.

Images