Projection lenses and near-eye display devices

Abstract

This specification provides one or more embodiments of a projection lens and a near-eye display device. The projection lens can be applied to a near-eye display device to project an image displayed on the device's screen onto the user's eyes. The projection lens includes: an aperture, a first lens, a second lens, a third lens, and a fourth lens arranged sequentially along the optical axis; the fourth lens is located near the display screen. The first lens has positive refractive power, the second lens has negative refractive power, the third lens has negative refractive power, and the fourth lens has positive refractive power. Furthermore, the projection lens satisfies 0.4 < (F × TTL) / (f × H) < 0.5, and NA ≥ 0.4; where F represents the aperture of the projection lens, TTL represents the total optical length of the projection lens, f represents the focal length of the projection lens, H represents the diagonal length of the maximum effective area of ​​the display screen, and NA represents the numerical aperture of the projection lens.

Description

Technical Field

[0001] This specification relates to the field of optical technology, and more particularly to a projection lens and a near-eye display device. Background Technology

[0002] Near-eye display devices, such as virtual reality (VR) and augmented reality (AR) headsets, can include projection lenses and displays. The projection lenses project images from the display screen towards the user's eyes to create a virtual reality or augmented reality experience. For example, when a user uses a VR headset for an immersive gaming experience, the projection lenses inside project the game image directly into their eyes, allowing them to see the game's scenes and objects within the virtual reality environment. This technology makes games more realistic and immersive, enhancing the user's gaming experience.

[0003] Because the user's eyes are very close to the head-mounted display's projection lens, the lens needs to have a short projection distance and a miniaturized design to accurately project images onto the user's retina. However, the miniaturization requirement may present challenges in manufacturing. Therefore, there is a need for a projection lens that ensures projected image quality while being easy to manufacture. Summary of the Invention

[0004] To ensure the quality of the projected image from the projection lens and to facilitate manufacturing, this specification provides one or more embodiments of a projection lens and a near-eye display device.

[0005] In a first aspect, one or more embodiments of this specification provide a projection lens for use in a near-eye display device, the near-eye display device including a display screen for projecting images through the projection lens; the projection lens includes: an aperture stop, a first lens, a second lens, a third lens, and a fourth lens arranged sequentially along the optical axis; wherein the fourth lens is located on the side closer to the display screen; the first lens has positive refractive power, the second lens has negative refractive power, the third lens has negative refractive power, and the fourth lens has positive refractive power; the projection lens satisfies 0.4 < (F × TTL) / (f × H) < 0.5, and NA ≥ 0.4; wherein F represents the aperture of the projection lens, TTL represents the total optical length of the projection lens, f represents the focal length of the projection lens, H represents the diagonal length of the maximum effective area of ​​the display screen, and NA represents the numerical aperture of the projection lens.

[0006] In a possible implementation, the image side of the first lens is convex, and the object side of the first lens is concave; the image side of the second lens is convex, and the object side of the second lens is concave; the image side of the third lens is concave, and the object side of the third lens is convex; the image side of the fourth lens is convex, and the object side of the fourth lens is concave.

[0007] In a possible implementation, the first lens satisfies -1 < (L1r1 - L1r2) / (L1r1 + L1r2) < -0.9, where L1r1 represents the radius of curvature of the image side of the first lens, and L1r2 represents the radius of curvature of the object side of the first lens.

[0008] In a possible implementation, the second lens satisfies 0.05 < (L2r1 - L2r2) / (L2r1 + L2r2) < 0.15, where L2r1 represents the radius of curvature of the image side of the second lens, and L2r2 represents the radius of curvature of the object side of the second lens.

[0009] In a possible implementation, the third lens satisfies -0.3 < (L3r1 - L3r2) / (L3r1 + L3r2) < -0.1, where L3r1 represents the radius of curvature of the image side of the third lens, and L3r2 represents the radius of curvature of the object side of the third lens.

[0010] In a possible implementation, the fourth lens satisfies -0.6 < (L4r1 - L4r2) / (L4r1 + L4r2) < -0.3, where L4r1 represents the radius of curvature of the image side of the fourth lens, and L4r2 represents the radius of curvature of the object side of the fourth lens.

[0011] In a possible implementation, the focal length f1 of the first lens satisfies 1 < f1 / f < 1.2, and the focal length f4 of the fourth lens satisfies 0.9 < f4 / f < 1.

[0012] In a possible implementation, the focal length f2 of the second lens satisfies -5.5 < f2 / f < -3.5, and the focal length f4 of the third lens satisfies -1.7 < f3 / f < -1.

[0013] In a possible implementation, the projection lens further includes a filter, and the filter is located between the display screen and the fourth lens.

[0014] In one possible implementation, the Abbe number of the first lens is 0.74638, the Abbe number of the second lens is 0.55815, the Abbe number of the third lens is 0.20500, the Abbe number of the fourth lens is 0.55695, and the Abbe number of the filter is 0.64167.

[0015] Secondly, one or more embodiments of this specification also provide a near-eye display device, including at least one display screen and a projection lens as described in any one of the first aspects, corresponding to each of the display screens; the projection lens is used to project the image displayed on the display screen.

[0016] In summary, this specification provides a projection lens and a near-eye display device through one or more embodiments. Because it uses a small number of lenses and has a simple structure, it significantly reduces the difficulty of production and assembly. Secondly, the projection lens has a large light-gathering angle, which improves the utilization rate of light source energy. Furthermore, the combination of positive-negative-negative-positive refractive forces of the first, second, third, and fourth lenses allows each lens to more evenly handle the incident light angle, thus correcting aberrations. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of one or more embodiments of this specification, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of one or more embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This specification provides a schematic diagram of an application scenario for one or more embodiments.

[0019] Figure 2 A schematic diagram of an application scenario from the A-direction perspective provided for one or more embodiments of this specification;

[0020] Figure 3 A schematic diagram of the structure of a projection lens 200 provided for one or more embodiments of this specification;

[0021] Figure 4 A schematic diagram of the reverse optical path design of a projection lens 200 provided for one or more embodiments of this specification;

[0022] Figure 5 A schematic diagram of the MTF of a projection lens 200 provided in one or more embodiments of this specification;

[0023] Figure 6A field curvature diagram of a projection lens 200 provided in one or more embodiments of this specification;

[0024] Figure 7 A distortion diagram of the projection lens 200 provided in one or more embodiments of this specification;

[0025] Figure 8 A schematic diagram of the relative illumination of a projection lens 200 provided in one or more embodiments of this specification;

[0026] Figure 9 A schematic diagram of the transverse chromatic aberration of the projection lens 200 provided in one or more embodiments of this specification;

[0027] Figure 10 MTF diagram of another projection lens 200 provided for one or more embodiments of this specification;

[0028] Figure 11 A field curvature diagram of another projection lens 200 provided for one or more embodiments of this specification;

[0029] Figure 12 A distortion diagram of another projection lens 200 provided for one or more embodiments of this specification;

[0030] Figure 13 A schematic diagram of the relative illumination of another projection lens 200 provided for one or more embodiments of this specification;

[0031] Figure 14 This is a schematic diagram of the vertical chromatic aberration of three-color light in another projection lens 200 provided for one or more embodiments of this specification. Detailed Implementation

[0032] The present specification describes one or more embodiments in further detail below with reference to the accompanying drawings and examples. Through these descriptions, the features and advantages of one or more embodiments of the present specification will become clearer and more apparent.

[0033] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0034] Furthermore, the technical features described below in one or more embodiments of this specification may be combined with each other as long as they do not conflict with each other.

[0035] To facilitate understanding, the application scenarios of the technical solutions provided in one or more embodiments of this specification will be described below.

[0036] Figure 1 This is a schematic diagram illustrating an application scenario provided for one or more embodiments of this specification. Figure 2 for Figure 1 A schematic diagram of the application scenario from the A-axis perspective.

[0037] like Figure 1 and Figure 2 As shown, the near-eye display device 100 can be a head-mounted display device such as VR glasses or AR glasses. The near-eye display device 100 may include a projection lens 200 and a display screen 300. The near-eye display device 100 may also include components such as a camera (not shown), a sensor (not shown), and a vision processor (not shown). When a user wears the near-eye display device 100, the projection lens 200 is positioned between the display screen 300 and the user's eyes 400.

[0038] The device includes a camera that captures images and videos of the real world and transmits this image information to a vision processor. Sensors detect the user's head and body movements and transmit this sensor data to the vision processor. The vision processor processes the received image information and sensor data to overlay virtual images or information onto a real-world scene. A display screen 300 displays the virtual images or information processed by the vision processor. A projection lens 200 projects the virtual images or information displayed on the display screen 300 onto the eyes 400 of the user wearing the near-eye display device 100. Thus, because the user can see scenes and objects in the virtual world through the projection lens 200 of the near-eye display device 100, the user experiences an immersive, lifelike experience.

[0039] It should be noted that the near-eye display device 100 may include one display screen 300 and one projection lens 200, or it may include two display screens 300 and two projection lenses 200. The two projection lenses 200 correspond one-to-one with the two display screens 300, and the two display screens 300 correspond one-to-one with the user's two eyes. Thus, one set of display screens 300 and projection lenses 200 can be used to project an image to one of the user's eyes, and the other set of display screens 300 and projection lenses 200 can be used to project an image to the user's other eye.

[0040] Because the user's eye 400 is very close to the projection lens 200, the projection lens 200 needs to have a short projection distance and a miniaturized design in order to accurately project the image onto the user's retina. However, the miniaturized design requirements may present challenges in manufacturing. Therefore, there is a need to provide a projection lens that ensures projected image quality while being easy to manufacture.

[0041] The following describes an embodiment of the projection lens 200 provided in one or more embodiments of this specification.

[0042] See Figure 3 , Figure 3 This is a structural schematic diagram of a projection lens 200 provided for one or more embodiments of this specification. Figure 3 As shown, the projection lens 200 may include an aperture stop 201, a first lens 202, a second lens 203, a third lens 204, and a fourth lens 205 arranged sequentially along the optical axis X. The first lens 202 is positioned close to the user's eye 400, and the fourth lens 205 is positioned close to the display screen 300.

[0043] The aperture stop 201 can be fitted around the circumference of the first lens 202, and the diameter of the aperture stop 201 can be the same as the maximum diameter of the first lens 202. The aperture stop 201 can be used to adjust the amount of light entering, thereby controlling the exposure and depth of field of the image.

[0044] The first lens 202 has positive refractive power, the second lens 203 has negative refractive power, the third lens 204 has negative refractive power, and the fourth lens 205 has positive refractive power. Each of the four lenses—first lens 202, second lens 203, third lens 204, and fourth lens 205—includes an object-side surface and an image-side surface. The object-side surface refers to the side closer to the display screen, while the image-side surface refers to the side furthest from the display screen.

[0045] In one possible implementation, the image-side surface 2021 of the first lens 202 is convex, and the object-side surface 2022 of the first lens 202 is concave; the image-side surface 2031 of the second lens 203 is convex, and the object-side surface 2032 of the second lens 203 is concave; the image-side surface 2041 of the third lens 204 is concave, and the object-side surface 2042 of the third lens 204 is convex; the image-side surface 2051 of the fourth lens 205 is convex, and the object-side surface 2052 of the fourth lens 205 is concave.

[0046] For example, the second lens 203 can adopt a meniscus structure, and the third lens 204 can be designed to have a curvature point. In this way, the second lens 203 can better correct the field curvature and astigmatism of the system. The third lens 204 can better correct higher-order aperture aberrations.

[0047] In this way, the first lens 202, the second lens 203, the third lens 204 and the fourth lens 205, through the combination of positive and negative refractive forces, can make each lens bear the incident angle of light more evenly and correct aberrations.

[0048] The projection lens 200 can satisfy the following relations (1) and relations (2).

[0049] 0.4 < (F × TTL) / (f × H) < 0.5, Relationship (1)

[0050] NA ≥ 0.4, Relationship (2)

[0051] Among them, F represents the aperture of the projection lens 200, TTL represents the total optical length of the projection lens 200, f represents the focal length of the projection lens 200, H represents the diagonal length of the maximum effective area of the display screen 300, and NA represents the numerical aperture of the projection lens 200. The aperture F of the projection lens 200 is the ratio of the focal length f of the projection lens 200 to the aperture R of the projection lens 200, and NA is the reciprocal of 2F.

[0052] In one realizable manner, according to the principle of optical path reversibility, a reverse optical path can be adopted to design the projection lens 200 so that the projection lens 200 satisfies the above Relationship (1) and Relationship (2). As Figure 4 shown, the aperture R of the projection lens 200 can be the diameter corresponding to the diaphragm 201, and the total optical length TTL of the projection lens 200 can be the distance between the image side of the first lens 202 and the display screen 300.

[0053] In this way, since the NA of the projection lens 200 ≥ 0.4, which has a relatively large numerical aperture, a large light-receiving angle of the projection lens 200 is achieved, improving the utilization rate of the energy of the light source. In addition, the projection lens 200 satisfies 0.4 < (F × TTL) / (f × H) < 0.5. Therefore, such a projection lens 200 has the characteristics of a compact structure and can meet the requirements of miniaturization of the projection lens 200. For example, the field angle of the projection lens 200 can reach 30°, and the total optical length TTL can reach 7.3 mm.

[0054] For the projection lens 200 provided by one or more embodiments of this specification, since the number of lenses used is small and the structure is simple, the production and assembly difficulties can be greatly reduced. In addition, through the combination of the refractive powers of the first lens 202, the second lens 203, the third lens 204, and the fourth lens 205 being positive, negative, negative, and positive, each lens can bear the incident light deflection angle more evenly and correct the aberration. Through the above configuration method of multiple lenses, not only can the lenses with different refractive powers and focal lengths be effectively utilized to achieve the enlarged imaging of the light source image, but also the overall image distortion can be ensured to be small, the brightness is uniform, and the imaging quality is good.

[0055] To further optimize the performance of the projection lens 200, the projection lens 200 can satisfy any one or more of the following Relationships (3) to Relationship (10).

[0056] 1 < f1 / f < 1.2, Relationship (3)

[0057] -5.5 < f2 / f < -3.5, Relationship (4)

[0058] -1.7 < f3 / f < -1, Relationship (5)

[0059] 0.9 < f4 / f < 1, Relationship (6)

[0060] -1 < (L1r1 - L1r2) / (L1r1 + L1r2) < -0.9, Relationship (7)

[0061] 0.05 < (L2r1 - L2r2) / (L2r1 + L2r2) < 0.15, Relationship (8)

[0062] -0.3 < (L3r1 - L3r2) / (L3r1 + L3r2) < -0.1, Relationship (9)

[0063] -0.6 < (L4r1 - L4r2) / (L4r1 + L4r2) < -0.3, Relationship (10)

[0064] Where, f1 represents the focal length of the first lens 202, f2 represents the focal length of the second lens 203, f3 represents the focal length of the third lens 204, f4 represents the focal length of the fourth lens 205, L1r1 represents the radius of curvature of the image side of the first lens 202, and L1r2 represents the radius of curvature of the object side of the first lens 202. L2r1 represents the radius of curvature of the image side of the second lens 203, and L2r2 represents the radius of curvature of the object side of the second lens 203. L3r1 represents the radius of curvature of the image side of the third lens 204, and L3r2 represents the radius of curvature of the object side of the third lens 204. L4r1 represents the radius of curvature of the image side of the fourth lens 205, and L4r2 represents the radius of curvature of the object side of the fourth lens 205.

[0065] Exemplarily, the projection lens 200 can satisfy the above Relationship (3) and Relationship (6). That is, the focal length f1 of the first lens 202 satisfies 1 < f1 / f < 1.2, and the focal length f4 of the fourth lens 205 satisfies 0.9 < f4 / f < 1. Thus, by limiting the focal lengths of the first lens 202 and the fourth lens 205 within a smaller range, on the one hand, the overall length of the imaging optical system can be shortened, and on the other hand, the high-order spherical aberration and coma generated by the lens can be suppressed to a smaller extent.

[0066] In another example, the projection lens 200 can satisfy the above relationships (4) and (5). That is, the focal length f2 of the second lens 203 satisfies -5.5 < f2 / f < -3.5, and the focal length f4 of the third lens 204 satisfies -1.7 < f3 / f < -1. In this way, the second lens 203 and the third lens 204 with negative refractive power can compensate for the field curvature accumulated in the marginal field of view of the system, and are also beneficial to the miniaturization of the overall structure of the projection lens 200.

[0067] In another example, the projection lens 200 can satisfy the above relationships (7) to (10). That is, the first lens 202 satisfies -1 < (L1r1 - L1r2) / (L1r1 + L1r2) < -0.9, the second lens 203 satisfies 0.05 < (L2r1 - L2r2) / (L2r1 + L2r2) < 0.15, the third lens 204 satisfies -0.3 < (L3r1 - L3r2) / (L3r1 + L3r2) < -0.1, and the fourth lens 205 satisfies -0.6 < (L4r1 - L4r2) / (L4r1 + L4r2) < -0.3. In this way, when the structures of the lenses satisfy the above relationships (7) to (10), the refraction angles corresponding to each surface in each lens can be suppressed to be relatively small, and the light can be deflected smoothly in each lens and each mirror surface, so as to minimize various aberrations. It can also make the distribution of the optical power of each lens in the projection lens 200 uniform, and make the tolerance sensitivity of each lens lower.

[0068] Optionally, the first lens 202, the second lens 203, the third lens 204, and the fourth lens 205 can all be selected as even aspherical surfaces. In this way, more optimization variables can be obtained to correct aberrations, improve thermal stability, reduce the number of lenses used, etc.

[0069] Optionally, the first lens 202, the second lens 203, the third lens 204, and the fourth lens 205 can be made of light-transmitting materials such as glass, plastic, resin, etc. For example, considering weight reduction, the first lens 202, the second lens 203, the third lens 204, and the fourth lens 205 can be made of resin materials.

[0070] Optionally, a filter 206 can also be included between the display screen 300 and the fourth lens 205. The filter 206 can allow light of a specific wavelength band to enter the first lens 202, the second lens 203, the third lens 204, and the fourth lens 205, and filter out light other than the specific wavelength band to ensure the light quality entering the first lens 202, the second lens 203, the third lens 204, and the fourth lens 205. For example, the light of the specific wavelength band includes red light, green light, and blue light, which are the wavelength bands corresponding to the three primary colors of light.

[0071] Thus, when using the projection lens 200 provided in one or more embodiments of this specification, the light emitted from the display screen 300 passes sequentially through the filter 206, the fourth lens 205, the third lens 204, the second lens 203, the first lens 202, and the aperture 201. Finally, the light exits from the aperture 201 and forms an image in the user's eye 400. In this way, the image displayed on the display screen 300 is projected onto the user's eye 400 through the projection lens 200.

[0072] The construction and performance of the projection lens 200 provided in one or more embodiments of this specification will be described below with reference to specific examples.

[0073] Example 1

[0074] The projection lens 200 provided in Example 1 includes an aperture stop 201, a first lens 202, a second lens 203, a third lens 204, a fourth lens 205, and a filter 206 arranged sequentially along the optical axis. The radius of curvature of the side of the filter 206 away from the display screen is L5r1, and the radius of curvature of the side of the filter closer to the display screen is L5r2. The parameters of each component in the projection lens 200 provided in Example 1 are shown in Tables 1 and 2.

[0075] Table 1

[0076]

[0077]

[0078] It should be noted that in Table 1, L1r2→L2r1 represents the distance between the object side of the first lens and the image side of the second lens, L2r2→L3r1 represents the distance between the object side of the second lens and the image side of the third lens, L3r2→L4r1 represents the distance between the object side of the third lens and the image side of the fourth lens, L4r2→L5r1 represents the distance between the object side of the fourth lens and the image side of the filter, and L5r2→display screen represents the distance between the object side of the filter and the display screen.

[0079] It should also be noted that the first, second, third, and fourth lenses all have even-order aspherical surfaces, while the aperture, filter, and display screen all have standard surfaces. The display screen can utilize 4µm micro-light-emitting diodes (MicroLEDs). Because MicroLEDs are self-emissive, their structure is more compact and their size is smaller, which is beneficial for miniaturizing the projection lens.

[0080] Table 2

[0081]

[0082]

[0083] In this way, the structure of each lens in the projection lens 200 and the positional relationship between each component can be determined based on the following even-order aspherical surface shape expression (11), the data in Table 1 and Table 2.

[0084]

[0085] In relation (11), x represents the distance from the vertex of the lens in the direction of the optical axis, y represents the distance in the direction perpendicular to the optical axis, c represents the reciprocal of the radius of curvature at the vertex of the lens, and K, A, B, C, D, E, F, and G represent the 2nd, 4th, 6th, 8th, 10th, 12th, 14th, and 16th order surface coefficients of even-order aspherical surfaces.

[0086] Thus, based on the curvature radius, thickness and other parameters of each lens in Table 1 and the surface coefficient of each lens in Table 2, the structure corresponding to each lens can be calculated using the above relationship (11).

[0087] Furthermore, based on the thickness, spacing, and other parameters of each component, such as the aperture stop, first lens, second lens, third lens, fourth lens, and filter, as well as the calculated structure of each lens, a projection lens 200 can be designed. The components in the projection lens 200 designed in this way satisfy the parameters recorded in Tables 1 and 2 above.

[0088] After obtaining the projection lens 200, the parameters shown in Table 3 can be calculated using relevant calculation tools.

[0089] Table 3

[0090] parameter Numerical (F×TTL) / (f×H) 0.45 NA 0.41 f1 / f 1.12 f2 / f -4.90 f3 / f -1.40 f4 / f 0.97 (L1r1-L1r2) / (L1r1+L1r2) -0.94 (L2r1-L2r2) / (L2r1+L2r2) 0.1 (L3r1-L3r2) / (L3r1+L3r2) -0.2 (L4r1-L4r2) / (L4r1+L4r2) -0.46

[0091] As can be seen, the values ​​shown in Table 3 satisfy the above relationships (1) to (10).

[0092] To more intuitively demonstrate the advantages of the projection lens 200 provided in one or more embodiments of this specification, such as low overall image distortion and uniform brightness, and its good imaging quality, the modulation transfer function (MTF), field curvature, distortion, relative illumination, and chromatic aberration of the three colors of light along the vertical axis of the projection lens 200 provided in Example 1 were tested.

[0093] Figure 5 This is a schematic diagram of the MTF of the projection lens 200 corresponding to Example 1. Figure 5 The MTF curves in the figure are the MTF curves corresponding to different fields of view.

[0094] MTF (Mean Transmission Frequency) reflects an optical system's ability to transmit signals at different spatial frequencies. It can be understood as the system's ability to reproduce images. A higher MTF value indicates a better signal transmission capability at that spatial frequency, meaning better image reproduction. Generally, the MTF curve gradually decreases as the spatial frequency increases, because the imaging capability of an optical system is limited by factors such as diffraction.

[0095] In an MTF curve, the horizontal axis represents spatial frequency, a concept that describes the frequency of detail in an object within an optical system or image. It refers to the frequency of changes in object detail within an image, typically used to describe the level of detail in edges, textures, and other features. The vertical axis represents the amplitude transfer function (MTF).

[0096] like Figure 5 As shown, Figure 5 The MTF (Mean Transmission Format) at different spatial frequencies under different fields of view is shown. At a spatial frequency of 63.0, the MTF for all fields of view is greater than 0.75. This means that at a spatial frequency of 63.0, the projection lens 200 can effectively transmit and retain the detail information in the image, indicating that the projection lens 200 has good imaging quality and can capture and retain details at high spatial frequencies.

[0097] Figure 6 This is a schematic diagram of the field curvature of the projection lens 200 corresponding to Example 1. Figure 6 The field curves in the diagram represent the field curves corresponding to different colors of light. For example, the solid lines 0.4600, 0.5270, and 0.6350 represent the field curves corresponding to blue, green, and red light in the meridional direction, respectively, while the dashed lines 0.4600, 0.5270, and 0.6350 represent the field curves corresponding to blue, green, and red light in the sagittal direction, respectively.

[0098] Field curvature is an aberration caused by the image plane not being flat. This aberration can be corrected by methods such as... Figure 6 The field curve shown represents the deviation of the actual image plane from the theoretical image plane. A smaller deviation indicates less field curvature, resulting in better actual image quality. Figure 6 As shown, the horizontal axis represents the deviation amount, and the vertical axis represents the half-field angle. It can be seen that the maximum deviation in each field of view is less than 0.04mm, which meets the requirements for human visual perception.

[0099] Figure 7 This is a schematic diagram of the distortion of the projection lens 200 corresponding to Example 1. Figure 7 The distortion curves in the image represent the distortion curves corresponding to different colors of light. For example, 0.4600, 0.5270, and 0.6350 represent the distortion curves corresponding to blue, green, and red light, respectively.

[0100] The distortion curve reflects whether and to what extent distortion occurs during the imaging process of the projection lens 200. For example... Figure 7 As shown, the horizontal axis represents the percentage of distortion, and the vertical axis represents the half-field of view. It can be seen that the maximum percentage of distortion in each field of view is less than 2.2%, which means that the distortion level of the projection lens 200 is very low, almost imperceptible to the human eye. Thus, the projection lens 200 with very low distortion can ensure the accuracy and quality of the image, making the image more natural and easier to understand.

[0101] Figure 8 This is a schematic diagram of the relative illumination of the projection lens 200 corresponding to Example 1.

[0102] Relative illuminance refers to the ratio of the illuminance of each field of view to the illuminance of the central field of view. For example... Figure 8 As shown, the horizontal axis represents the Y-field of view, and the vertical axis represents the relative illumination. The Y-field of view refers to the field of view in the vertical direction within the projection lens 200. From Figure 8 As can be seen, the relative illumination curve is smooth and without inversion, and the relative illumination at the edge field of view is greater than 80%, which means that the imaging brightness of the projection lens 200 is uniform.

[0103] Figure 9 This is a schematic diagram of the chromatic aberration of the three colors of light along the vertical axis of the projection lens 200 corresponding to Example 1.

[0104] Chromatic aberration of trichromatic light refers to the distortion caused by the dispersion effect of light of different wavelengths when light passes through a lens or other optical element. This distortion causes different colors of light in the optical system to focus at different positions, thus producing the chromatic aberration phenomenon.

[0105] like Figure 9 As shown, Figure 9 This illustrates the deviation of blue (0.4600), green (0.5270), and red (0.6350) light from their vertical axes at different light source heights. The horizontal axis represents the deviation amount, and the vertical axis represents the actual image height (the actual image center corresponds to 0). From... Figure 9 It can be seen that the maximum offset between the three colors is less than 4μm. This indicates that the transverse chromatic difference of the three colors in the projection lens 200 is very small, which can ensure the color fidelity and clarity of the image.

[0106] Example 2

[0107] The projection lens 200 provided in Example 2 includes an aperture stop 201, a first lens 202, a second lens 203, a third lens 204, a fourth lens 205, and a filter 206 arranged sequentially along the optical axis. The radius of curvature of the side of the filter 206 furthest from the display screen is L5r1, and the radius of curvature of the side of the filter closest to the display screen is L5r2. The parameters of each component in the projection lens 200 provided in Example 2 are shown in Tables 4 and 5. Based on Tables 4 and 5 and the above relationship (11), the structure corresponding to each lens can be calculated.

[0108] Furthermore, based on the thickness, spacing, and other parameters of each component, such as the aperture, first lens, second lens, third lens, fourth lens, and filter, as shown in Table 4, and the calculated structure of each lens, a projection lens 200 can be designed. The components in the projection lens 200 designed in this way satisfy the parameters recorded in Tables 4 and 5 above.

[0109] After obtaining the projection lens 200, the parameters shown in Table 6 can be calculated using relevant calculation tools.

[0110] Table 4

[0111]

[0112]

[0113] Table 5

[0114]

[0115]

[0116] Table 6

[0117] parameter Numerical (F×TTL) / (f×H) 0.45 NA 0.41 f1 / f 1.11 f2 / f -3.83 f3 / f -1.39 f4 / f 0.94 (L1r1-L1r2) / (L1r1+L1r2) -0.95 (L2r1-L2r2) / (L2r1+L2r2) 0.12 (L3r1-L3r2) / (L3r1+L3r2) -0.19 (L4r1-L4r2) / (L4r1+L4r2) -0.47

[0118] As can be seen, the values ​​shown in Table 6 satisfy the above relationships (1) to (10). For details about Tables 4, 5 and 6, please refer to the descriptions of Tables 1, 2 and 3, which will not be repeated here.

[0119] To more intuitively demonstrate the advantages of the projection lens 200 provided in one or more embodiments of this specification, such as low overall image distortion, uniform brightness, and good imaging quality, the imaging quality-related performance of the projection lens 200 provided in Example 2, such as MTF, field curvature, distortion, relative illumination, and chromatic aberration of the three colors, was tested.

[0120] Figure 10 This is a schematic diagram of the MTF of the projection lens 200 corresponding to Example 2. Figure 11 This is a schematic diagram of the field curvature of the projection lens 200 corresponding to Example 2. Figure 12This is a distortion diagram of the projection lens 200 corresponding to Example 2. Figure 13 This is a schematic diagram showing the relative illumination of the projection lens 200 corresponding to Example 2. Figure 14 This is a schematic diagram of the vertical chromatic aberration of the three colors of light from the projection lens 200 corresponding to Example 2.

[0121] like Figure 10 As shown, at a spatial frequency of 63.0, the MTF corresponding to all fields of view is greater than 0.75. That is to say, at a spatial frequency of 63.0, the projection lens 200 can effectively transmit and retain the detail information in the image, indicating that the projection lens 200 has good imaging quality and can capture and retain details at high spatial frequencies.

[0122] like Figure 11 As shown, the maximum deviation in each field of view is less than 0.04mm, which meets the requirements for human viewing.

[0123] like Figure 12 As shown, the maximum distortion percentage in each field of view is less than 2.2%, which means that the distortion level of the projection lens 200 is very low and difficult for the human eye to perceive. Thus, the projection lens 200 with very low distortion can ensure the accuracy and quality of the image, making the image more natural and easier to understand.

[0124] like Figure 13 As shown, the relative illumination curve is smooth and without inversion, and the relative illumination at the edge field of view is greater than 80%, which means that the imaging brightness of the projection lens 200 is uniform.

[0125] like Figure 14 As shown, the maximum offset between the three colors is less than 4μm. This indicates that the transverse chromatic difference of the three colors in the projection lens 200 is very small, which can ensure the color fidelity and clarity of the image.

[0126] It should be noted that, regarding Figures 10 to 14 See also the Figures 5 to 9 The description will not be repeated here.

[0127] In summary, the projection lens 200 provided in one or more embodiments of this specification, due to its small number of lenses and simple structure, can greatly reduce the difficulty of production and assembly. Secondly, the projection lens 200 has a large light-gathering angle, which improves the utilization rate of light source energy. Furthermore, the combination of positive-negative-negative-positive refractive forces of the first lens 202, second lens 203, third lens 204, and fourth lens 205 allows each lens to more evenly bear the incident light angle, correcting aberrations. Combining the imaging performance test results such as MTF, field curvature, distortion, relative illuminance, and transverse chromatic aberration of the three colors provided in Examples 1 and 2, it can be seen that the projection lens 200 has small imaging distortion and field curvature aberrations, uniform brightness, and good image quality.

[0128] It is understood that the above embodiments are merely examples, and modifications can be made to the above embodiments in actual implementation. Those skilled in the art will understand that any modifications to the above embodiments that do not require creative effort fall within the protection scope of one or more embodiments of this specification, and will not be described again in the embodiments.

[0129] Based on the same inventive concept, one or more embodiments of this specification also provide a near-eye display device, which may include at least one display screen 300 and a projection lens 200 corresponding to each display screen 300; wherein, the projection lens 200 is used to project the image displayed on the display screen 300.

[0130] The projection lens 200 can be referred to in the above description of the projection lens embodiment, and will not be repeated here.

[0131] For example, a near-eye display device may include two displays 300 and two projection lenses 200. Each of the two projection lenses 200 corresponds one-to-one with one of the two displays 300, and each of the two displays 300 corresponds one-to-one with one of the user's eyes. Thus, one set of displays 300 and projection lenses 200 can be used to project an image to one of the user's eyes, and the other set of displays 300 and projection lenses 200 can be used to project an image to the user's other eye.

[0132] It should be noted that one or more embodiments in this specification do not limit the specific form of the near-eye display device. For example, the near-eye display device can be a VR glasses, AR glasses, VR helmet, AR helmet, or other head-mounted near-eye display device.

[0133] It should also be noted that near-eye display devices may also include components such as cameras, sensors, and vision processors.

[0134] Since the principle behind the problem solved by near-eye display devices is similar to that of the aforementioned projection lenses, the implementation of near-eye display devices can be found in the implementation of the aforementioned projection lenses, and the repetitive parts will not be repeated.

[0135] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. In particular, the near-eye display device embodiments are basically similar to the projection lens embodiments, so the description is relatively simple; relevant parts can be referred to the description of the projection lens embodiments.

[0136] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying 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. Those skilled in the art will understand the specific meaning of the above terms in one or more embodiments of this specification, depending on the specific circumstances.

[0137] It should be noted that, unless otherwise specified, one or more embodiments and features thereof in this specification can be combined with each other. This specification is not limited to any single aspect, nor to any single embodiment, nor to any combination and / or substitution of such aspects and / or embodiments. Furthermore, each aspect and / or embodiment of one or more embodiments of this specification can be used alone or in combination with one or more other aspects and / or embodiments thereof.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of one or more embodiments of this specification, and are not intended to limit them. Although one or more embodiments of this specification have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of one or more embodiments of this specification, and they should all be covered within the scope of the claims and the specification of one or more embodiments of this specification.

[0139] The foregoing description of one or more embodiments of this specification has been provided in conjunction with optional implementation methods. However, these embodiments are merely exemplary and serve only an illustrative purpose. Based on this, various substitutions and modifications can be made to one or more embodiments of this specification, all of which fall within the protection scope of one or more embodiments of this specification.

Claims

1. A projection lens, characterized in that, Applied to a near-eye display device, the near-eye display device includes a display screen for projecting an image through the projection lens; The projection lens includes: an aperture stop, a first lens, a second lens, a third lens, and a fourth lens arranged in sequence along the optical axis direction; wherein, the fourth lens is located on the side close to the display screen; The first lens has a positive refractive power, the second lens has a negative refractive power, the third lens has a negative refractive power, and the fourth lens has a positive refractive power; The projection lens satisfies 0.4 < (F × TTL) / (f × H) < 0.5, and NA ≥ 0.4; where F represents the aperture of the projection lens, TTL represents the total optical length of the projection lens, f represents the focal length of the projection lens, H represents the diagonal length of the maximum effective area of the display screen, and NA represents the numerical aperture of the projection lens.

2. The projection lens as described in claim 1, characterized in that, The image side surface of the first lens is convex, and the object side surface of the first lens is concave; the image side surface of the second lens is convex, and the object side surface of the second lens is concave; the image side surface of the third lens is concave, and the object side surface of the third lens is convex; the image side surface of the fourth lens is convex, and the object side surface of the fourth lens is concave.

3. The projection lens as described in claim 2, characterized in that, The first lens satisfies -1 < (L1r1 - L1r2) / (L1r1 + L1r2) < -0.9, where L1r1 represents the radius of curvature of the image side surface of the first lens, and L1r2 represents the radius of curvature of the object side surface of the first lens.

4. The projection lens as described in claim 2, characterized in that, The second lens satisfies 0.05 < (L2r1 - L2r2) / (L2r1 + L2r2) < 0.15, where L2r1 represents the radius of curvature of the image side surface of the second lens, and L2r2 represents the radius of curvature of the object side surface of the second lens.

5. The projection lens as described in claim 2, characterized in that, The third lens satisfies -0.3 < (L3r1 - L3r2) / (L3r1 + L3r2) < -0.1, where L3r1 represents the radius of curvature of the image side surface of the third lens, and L3r2 represents the radius of curvature of the object side surface of the third lens.

6. The projection lens as described in claim 2, characterized in that, The fourth lens satisfies -0.6 < (L4r1 - L4r2) / (L4r1 + L4r2) < -0.3, where L4r1 represents the radius of curvature of the image side surface of the fourth lens, and L4r2 represents the radius of curvature of the object side surface of the fourth lens.

7. The projection lens as described in claim 1, characterized in that, The focal length f1 of the first lens satisfies 1 < f1 / f < 1.2, and the focal length f4 of the fourth lens satisfies 0.9 < f4 / f < 1.

8. The projection lens as described in claim 1 or 7, characterized in that, The focal length f2 of the second lens satisfies -5.5 < f2 / f < -3.5, and the focal length f4 of the third lens satisfies -1.7 < f3 / f < -1. (It should be noted that there is a misrepresentation here. It should be f3 instead of f4 in the description of the third lens' focal length relationship.) 9. The projection lens as described in claim 1, characterized in that, The projection lens further includes a filter located between the display screen and the fourth lens.

10. A near-eye display device, characterized in that, Including at least one display screen and a projection lens corresponding to each of the display screens as described in any one of claims 1 - 9; the projection lens is used to project the image displayed on the display screen.

Images