Projection system and near-to-eye display device

Abstract

The invention provides a projection system and near-to-eye display equipment, and the projection system sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens from an object side to an image side, the second lens has positive focal power; a correction lens group, wherein the correction lens group comprises one or two lenses; the third lens has positive focal power; the turning prism has positive focal power, the turning prism is provided with a first transmission surface, a reflection surface and a second transmission surface, the first transmission surface, the reflection surface and the second transmission surface face the image side surface of the third lens, and the two transmission surfaces are aspheric surfaces; wherein the focal length f of the projection system and the total optical length TTL of the projection system satisfy 0 lt; f / TTLlt; the projection system solves the problems that in the prior art, a projection system is small in field angle and difficult to miniaturize.

Description

Technical Field

[0001] The present invention relates to the technical field of optical imaging equipment, and in particular to a projection system and a near-eye display device. Background Art

[0002] With the continuous advancement and iteration of display technology, augmented reality (AR) technology has gradually become a hot topic that has attracted much attention. AR technology enables users to have a richer interactive experience by superimposing virtual information on the user's real world. The imaging quality of AR display devices is a key factor in determining user experience, and the projection system is one of the key components that affect imaging quality. The AR projection system in the prior art mainly achieves imaging through a combination of multiple lenses. Existing projection systems generally have the problem of a small field of view (generally 15°~45°), which causes users to feel a poor sense of immersion when using AR devices. In addition, the design of a system with a large field of view is difficult, requiring a large number of lenses and a large optical size. This not only increases the manufacturing cost of the system, but also limits its use in certain applications.

[0003] Therefore, how to design a projection system that can achieve a large field of view while reducing the optical size and the number of lenses is an urgent problem to be solved in the current field of AR technology. Summary of the invention

[0004] The main purpose of the present invention is to provide a projection system and a near-eye display device to solve the problem of small field of view and difficulty in miniaturization of the projection system in the prior art.

[0005] In order to achieve the above-mentioned object, according to one aspect of the present invention, a projection system is provided, which includes, from the object side to the image side, a first lens, the first lens has a negative optical focal length; a second lens, the second lens has a positive optical focal length; a correction lens group, the correction lens group includes one or two lenses; a third lens, the third lens has a positive optical focal length; a turning prism, the turning prism has a positive optical focal length, and the turning prism has a first transmission surface, a reflection surface, and a second transmission surface facing the image side of the third lens, and both transmission surfaces are aspherical surfaces; wherein the focal length f of the projection system and the total optical length TTL of the projection system satisfy the following relationship: <f / TTL<0.24。

[0006] Further, the focal length f1 of the first lens satisfies: -0.16<1 / f1<0.

[0007] Furthermore, the focal length f2 of the second lens satisfies: 0<1 / f2<0.25.

[0008] Furthermore, the correction lens group includes a first correction lens and a second correction lens, and the focal length f3 of the first correction lens, the focal length f4 of the second correction lens, and the focal length f5 of the third lens satisfy: -0.1<(1 / f3+1 / f4+1 / f5)<0.22.

[0009] Furthermore, the correction lens group includes a first correction lens, and the focal length f3 of the first correction lens and the focal length f5 of the third lens satisfy: -0.1<(1 / f3+1 / f5)<0.22.

[0010] Furthermore, the focal length f6 of the turning prism satisfies: 0<1 / f6<0.12.

[0011] Furthermore, the focal length f of the projection system and the maximum imaging height ImgH of the projection system satisfy the following relationship: 0.7 <ImgH / f<1。

[0012] Furthermore, the projection system further comprises an aperture stop located at the object side of the first lens, and a light transmission diameter EPD of the aperture stop satisfies: 2≤EPD≤2.4.

[0013] Furthermore, the material of the turning prism is plastic, the reflecting surface is used to turn the incident light, the second transmitting surface is close to the image side of the projection system, and the curvature radius R62 of the reflecting surface satisfies: |R62|=∞.

[0014] Furthermore, the curvature radius R61 of the first transmission surface satisfies: |R61|<∞, the curvature radius R63 of the second transmission surface satisfies: |R63|<∞, and the curvature radius R61 of the first transmission surface and the curvature radius R62 of the reflection surface satisfy: (1 / R61-1 / R62)>0.

[0015] Furthermore, a minimum value Min_CT of the center thickness of all lenses in the projection system satisfies: Min_CT>0.3.

[0016] Furthermore, a minimum value Min_ET of the edge thickness of all lenses in the projection system satisfies: Min_ET>0.35.

[0017] Furthermore, the number N of components with optical focal length in the projection system satisfies: 5≤N≤6, and the maximum field of view FOV of the projection system satisfies: 70°≤FOV≤82°.

[0018] Furthermore, the materials of the first lens, the second lens, the correction lens group and the third lens are glass, and the refractive indexes of the first lens, the second lens, the correction lens group and the third lens are all greater than 1.75.

[0019] According to another aspect of the present invention, a near-eye display device is provided, comprising the above-mentioned projection system.

[0020] According to the technical solution of the present invention, the projection system includes a first lens, a second lens, a correction lens group, a third lens and a turning prism in sequence from the object side to the image side, wherein the first lens has a negative optical focal length; the second lens has a positive optical focal length; the correction lens group includes one or two lenses; the third lens has a positive optical focal length; the turning prism has a positive optical focal length, and the turning prism has a first transmission surface, a reflection surface and a second transmission surface, both of which are aspherical surfaces, and the first transmission surface faces the image side surface of the third lens; wherein the focal length f of the projection system and the total optical length TTL of the projection system satisfy the following conditions: <f / TTL<0.24。

[0021] The present application achieves an optical effect of a large field of view and high imaging quality with a relatively small number of lenses by using the above-mentioned lens combination and turning prism. Specifically, the first lens has a negative focal length, which helps to diverge the light close to the object side, obtain a larger exit angle, and expand the field of view. The positive focal length of the second lens effectively converges the light and reduces the focal length pressure of the subsequent lens; while the focal length distribution of the correction lens group and the third lens optimizes the aberration compensation and improves the imaging quality. The aspheric design of the turning prism not only realizes the turning of the light path, but also effectively corrects the large-aperture aberration, further improving the system performance. By limiting f / TTL within a reasonable range and controlling the ratio of the focal length to the total length of the projection system, the structure of the projection system can be made more compact, which is conducive to shortening the total length and achieving miniaturization. The overall design of the present application enables the projection system to achieve efficient light path management and excellent imaging effects while maintaining a compact structure, providing a better visual experience for augmented reality (AR) devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0023] Figure 1 A schematic diagram of the structure of a projection system according to a first embodiment of the present invention is shown;

[0024] Figure 2 Shows Figure 1 Light path diagram of the projection system in ;

[0025] Figure 3 Shows Figure 1 MTF curve of the projection system in;

[0026] Figure 4 Shows Figure 1 Distortion curve diagram of the projection system in ;

[0027] Figure 5 Shows Figure 1Relative illumination curve of the projection system in ;

[0028] Figure 6 Shows Figure 1 Astigmatism curve diagram of the projection system in;

[0029] Figure 7 A schematic diagram showing the structure of a projection system according to a second embodiment of the present invention is shown;

[0030] Figure 8 Shows Figure 7 Light path diagram of the projection system in ;

[0031] Fig. 9 Shows Figure 7 MTF curve of the projection system in;

[0032] Fig.10 Shows Figure 7 Distortion curve diagram of the projection system in ;

[0033] Fig.11 Shows Figure 7 Relative illumination curve of the projection system in ;

[0034] Fig.12 Shows Figure 7 Astigmatism curve diagram of the projection system in;

[0035] Fig.13 A schematic diagram showing the structure of a projection system according to a third embodiment of the present invention is shown;

[0036] Fig.14 Shows Fig.13 Light path diagram of the projection system in ;

[0037] Fig.15 Shows Fig.13 MTF curve of the projection system in;

[0038] Fig.16 Shows Fig.13 Distortion curve diagram of the projection system in ;

[0039] Fig.17 Shows Fig.13 Relative illumination curve of the projection system in ;

[0040] Fig.18 Shows Fig.13 Astigmatism curve diagram of the projection system in;

[0041] Fig.19 A schematic diagram showing the structure of a projection system according to a fourth embodiment of the present invention is shown;

[0042] Fig. 20 Shows Fig.19Light path diagram of the projection system in ;

[0043] Fig.21 Shows Fig.19 MTF curve of the projection system in;

[0044] Fig. 22 Shows Fig.19 Distortion curve diagram of the projection system in ;

[0045] Fig.23 Shows Fig.19 Relative illumination curve of the projection system in ;

[0046] Fig.24 Shows Fig.19 Astigmatism curve diagram of the projection system in;

[0047] Fig.25 A schematic diagram of the structure of a projection system according to a fifth embodiment of the present invention is shown;

[0048] Fig.26 Shows Fig.25 Light path diagram of the projection system in ;

[0049] Fig. 27 Shows Fig.25 MTF curve of the projection system in;

[0050] Fig.28 Shows Fig.25 Distortion curve diagram of the projection system in ;

[0051] Fig.29 Shows Fig.25 Relative illumination curve of the projection system in ;

[0052] Fig.30 Shows Fig.25 Astigmatism curve diagram of the projection system in;

[0053] Fig.31 A schematic diagram showing the structure of a projection system according to a sixth embodiment of the present invention is shown;

[0054] Fig.32 Shows Fig.31 Light path diagram of the projection system in ;

[0055] Fig.33 Shows Fig.31 MTF curve of the projection system in;

[0056] Fig.34 Shows Fig.31 Distortion curve diagram of the projection system in ;

[0057] Fig.35 Shows Fig.31 Relative illumination curve of the projection system in ;

[0058] Fig.36 Shows Fig.31 Astigmatism plot of the projection system in .

[0059] The above drawings include the following reference numerals:

[0060] STO, aperture; E1, polarizing plate; S2, object side surface of polarizing plate; S3, image side surface of polarizing plate; E2, first lens; S4, object side surface of first lens; S5, image side surface of first lens; E3, second lens; S6, object side surface of second lens; S7, image side surface of second lens; E4, first correction lens; S8, object side surface of first correction lens; S9, image side surface of first correction lens; E5, second correction lens; S10, object side surface of second correction lens; S11, second The image side surface of the correction lens; E6, the third lens; S12, the object side surface of the third lens; S13, the image side surface of the third lens; E7, the turning prism; S14, the first transmission surface of the turning prism; S15, the reflection surface of the turning prism; S16, the second transmission surface of the turning prism; E8, the polarization beam splitter; S17, the light incident surface; S18, the object side surface of the compensation plate; S19, the image side surface of the compensation plate; E9, the protective glass; S20, the object side surface of the protective glass; S21, the image side surface of the protective glass. DETAILED DESCRIPTION

[0061] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0062] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs.

[0063] In the present invention, unless otherwise specified, the directional words used, such as "up, down, top, bottom", usually refer to the directions shown in the drawings, or to the components themselves in the vertical, perpendicular or gravity directions; similarly, for ease of understanding and description, "inside and outside" refer to the inside and outside relative to the outline of each component itself, but the above-mentioned directional words are not used to limit the present invention.

[0064] It should be noted that in this specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teaching of the present application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0065] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0066] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is called the object side of the lens, and the surface of each lens closest to the imaging plane is called the image side of the lens.

[0067] It should also be understood that the terms "including" and / or "having", when used in this specification, indicate the presence of the stated features, elements and / or components, but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when describing the embodiments of the present application, the term "may" is used to mean "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

[0068] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as commonly understood by ordinary technicians in the field to which this application belongs. It should also be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having the same meaning as their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0069] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0070] In order to solve the problem in the prior art that the projection system has a small field of view and is difficult to miniaturize, the present invention provides a projection system and a near-eye display device.

[0071] like Figures 1 to 36 As shown, the projection system includes a first lens, a second lens, a correction lens group, a third lens and a turning prism in sequence from the object side to the image side, the first lens has a negative optical focal length; the second lens has a positive optical focal length; the correction lens group includes one or two lenses; the third lens has a positive optical focal length; the turning prism has a positive optical focal length, and the turning prism has a first transmission surface facing the image side of the third lens, a reflection surface and a second transmission surface for turning the incident light, and both transmission surfaces are aspherical surfaces; wherein the focal length f of the projection system and the total optical length TTL of the projection system satisfy: <f / TTL<0.24。

[0072] The present application achieves an optical effect of a large field of view and high imaging quality with a relatively small number of lenses by using the above-mentioned lens combination and turning prism. Specifically, the first lens has a negative focal length, which helps to diverge the light close to the object side, obtain a larger exit angle, and expand the field of view; the positive focal length of the second lens effectively converges the light and reduces the focal length pressure of the subsequent lens; and the focal length distribution of the correction lens group and the third lens optimizes the aberration compensation and improves the imaging quality. The turning prism utilizes the aspheric design of the reflection surface and the transmission surface to realize the turning of the light, which not only realizes the turning of the light path, but also effectively corrects the large-aperture aberration, further improving the system performance. By limiting f / TTL within a reasonable range and controlling the ratio of the focal length to the total length of the projection system, the structure of the projection system can be made more compact, which is conducive to shortening the total length and realizing miniaturization. The overall design of the present application enables the projection system to achieve efficient light path management and excellent imaging effects while maintaining a compact structure, providing a better visual experience for augmented reality (AR) devices.

[0073] In this embodiment, the projection system further includes, from the object side to the image side, an aperture stop and a polarizer located on the object side of the first lens, and a polarization splitter prism without optical power, a compensation plate, an imaging surface protection glass and a chip located on the image side of the turning prism.

[0074] It should be noted that the total optical length TTL of the projection system is the distance from the aperture surface to the imaging surface of the projection system on the optical axis.

[0075] In this embodiment, the focal length f1 of the first lens satisfies: -0.16<1 / f1<0. The first lens has a negative focal length, which helps to diverge the light close to the object side by limiting 1 / f1 within a reasonable range, thereby obtaining a larger exit angle and expanding the field of view.

[0076] In this embodiment, the focal length f2 of the second lens satisfies: 0<1 / f2<0.25. The second lens bears the main positive focal length, and by limiting 1 / f2 within a reasonable range, the incident light with a large field angle is converged, the focal length pressure of the subsequent lens is reduced, and the problem of an effective aperture being too large is avoided, thereby reducing the size of the projection system, facilitating a miniaturized design, and making the AR device more portable and comfortable.

[0077] In this embodiment, the correction lens group includes a first correction lens and a second correction lens. The focal lengths f3 of the first correction lens, f4 of the second correction lens, and f5 of the third lens satisfy: -0.1 < (1 / f3 + 1 / f4 + 1 / f5) < 0.22. The shapes of the three lenses generally present a meniscus shape, which is beneficial to the smooth transition of light, compensates for the aberration generated by the front lens, and improves the imaging quality. At the same time, through the reasonable distribution of the optical power of the correction lens group and the third lens, the optical power mismatch of the front lens is balanced by the optical power that can be positive or negative, reducing the tolerance sensitivity of the projection system, and thus improving the yield.

[0078] In another possible embodiment, the correction lens group may include one lens, that is, it includes a first correction lens. The focal lengths f3 of the first correction lens and f5 of the third lens satisfy: -0.1 < (1 / f3 + 1 / f5) < 0.22. The shapes of the two lenses, the first correction lens and the third lens, generally present a meniscus shape, which is beneficial to the smooth transition of light, compensates for the aberration generated by the front lens, and improves the imaging quality. At the same time, through the reasonable distribution of the optical power of the correction lens group and the third lens, the optical power mismatch of the front lens is balanced by the optical power that can be positive or negative, reducing the tolerance sensitivity of the projection system, and thus improving the yield.

[0079] In this embodiment, the focal length f6 of the turning prism satisfies: 0 < 1 / f6 < 0.12. By restricting 1 / f6 within a reasonable range, the turning prism provides a certain range of positive optical power, which is beneficial to focusing light onto the image plane and reducing the incident angle of the chief ray on the image plane. Combining with the aspherical surface shape of the transmission surface of the turning prism, spherical aberration, coma and other large-aperture aberrations can also be corrected to the greatest extent.

[0080] In this embodiment, the focal length f of the projection system and the maximum imaging height ImgH of the projection system satisfy: 0.7 < ImgH / f < 1. By restricting ImgH / f within a reasonable range, it is beneficial to expand the field of view angle as much as possible while ensuring that the distortion meets the requirements.

[0081] In this embodiment, the light-transmitting aperture EPD of the aperture stop satisfies: 2 ≤ EPD ≤ 2.4. By limiting the entrance pupil diameter within a reasonable range, the contradiction between the light passing amount and the image quality is balanced, and at the same time, the exit pupil of the projection system can be matched with the entrance pupil of the waveguide, reducing the loss of image quality and light flux.

[0082] In this embodiment, the turning prism can be called an aspheric right-angle prism. The material of the turning prism is plastic. The turning prism includes a first transmission surface close to the object side of the projection system, a reflection surface, and a second transmission surface close to the image side of the projection system. The curvature radius R62 of the reflection surface satisfies: |R62|=∞. The optical axis of the projection system is rotated 90° by using the reflection surface, so that the subsequent structure is assembled along the rotated direction, which is conducive to improving space utilization, making the structure of the projection system more compact, and reducing the risk of interference between the structures. In addition, the material of the aspheric right-angle prism is set to plastic, the injection molding process is mature, and it has excellent mass production performance.

[0083] In this embodiment, the radius of curvature R61 of the first transmission surface satisfies: |R61|<∞, the radius of curvature R63 of the second transmission surface satisfies: |R63|<∞, and the radius of curvature R61 of the first transmission surface and the radius of curvature R62 of the reflection surface satisfy: (1 / R61-1 / R62)>0. The first transmission surface and the second transmission surface of the aspherical surface provide additional positive focal length, further constraining the direction of the light, ensuring that the light has a smaller main ray angle when reaching the imaging surface, reducing the focal length pressure of other lenses, providing additional aberration elimination channels, and reducing the number of lenses required for the projection system.

[0084] In this embodiment, the minimum value Min_CT of the center thickness of all lenses in the projection system satisfies: Min_CT>0.3. By controlling the center thickness of the lens, the machinability of the lens made of glass is guaranteed.

[0085] In this embodiment, the minimum value Min_ET of the edge thickness of all lenses in the projection system satisfies: Min_ET>0.35. By controlling the edge thickness of the lens, the processability of the lens made of glass is also guaranteed.

[0086] In this embodiment, the number N of components with optical power in the projection system satisfies: 5≤N≤6, and the maximum field of view FOV of the projection system satisfies: 70°≤FOV≤82°. Under the premise of ensuring the field of view of the projection system, by restricting the number of components with optical power, the number of lenses used is minimized, and the assembly tolerance is reduced, which is also conducive to achieving a more compact structural design and lower mass production costs.

[0087] In this embodiment, the first lens, the second lens, the correction lens group and the third lens are made of glass, and the refractive index of the first lens, the second lens, the correction lens group and the third lens is greater than 1.75. The glass material can improve the stress problem of the projection system and reduce the focus shift problem caused by temperature drift. The high refractive index material can alleviate the geometric aberration caused by the large field of view light and improve the imaging quality.

[0088] In the present application, at least one of the mirror surfaces of each lens is an aspherical mirror surface. The characteristic of an aspherical lens is that the curvature changes continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens having a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has a better curvature radius characteristic, and has the advantages of improving distortion aberration and improving astigmatism aberration. After using an aspherical lens, the aberration occurring during imaging can be eliminated as much as possible, thereby improving the imaging quality.

[0089] However, those skilled in the art should understand that, without departing from the technical solution claimed in the present application, the number of lenses constituting the projection system can be changed to obtain the various results and advantages described in this specification.

[0090] The following further describes examples of specific surface shapes and parameters of the projection system applicable to the above-mentioned embodiments with reference to the accompanying drawings.

[0091] Embodiment 1

[0092] like Figures 1 to 6 As shown, the projection system of the first embodiment of the present application is described. Figure 1 FIG. 2 shows a structural diagram of a projection system according to Embodiment 1. Figure 2 The optical path diagram of the projection system of the first embodiment is shown.

[0093] like Figure 1 and Figure 2 As shown, the projection system includes an aperture STO, a polarizer E1, a first lens E2, a second lens E3, a first correction lens E4, a second correction lens E5, a third lens E6, a turning prism E7, a polarization splitter prism E8, a compensation plate, a protective glass E9 and a chip arranged in sequence from the object side to the image side.

[0094] In this embodiment, the polarizing plate E1 has an object side surface S2 of the polarizing plate and an image side surface S3 of the polarizing plate; the first lens E2 has a negative optical focal length, the object side surface S4 of the first lens is a convex surface, and the image side surface S5 of the first lens is a concave surface; the second lens E3 has a positive optical focal length, the object side surface S6 of the second lens is a concave surface, and the image side surface S7 of the second lens is a convex surface; the first correction lens E4 has a positive optical focal length, the object side surface S8 of the first correction lens is a concave surface, and the image side surface S9 of the first correction lens is a convex surface; the second correction lens E5 has a negative optical focal length, the object side surface S10 of the second correction lens is a concave surface, and the image side surface S11 of the second correction lens is a convex surface; the third lens E6 has a positive optical focal length, the object side surface S12 of the third lens is a concave surface, and the image side surface S13 of the third lens is a convex surface. The side surface S13 is a convex surface; the turning prism E7 has a positive optical focal length, the first transmission surface S14 of the turning prism is a concave surface and faces the image side surface S13 of the third lens, the reflection surface S15 of the turning prism is a plane, and the optical axis of the projection system rotates 90° after passing through the reflection surface S15, and the second transmission surface S16 of the turning prism is a convex surface; the polarization beam splitter prism E8 has a light incident surface S17 and a light exit surface, the compensation plate has an object side surface S18 of the compensation plate and an image side surface S19 of the compensation plate, and the object side surface S18 of the compensation plate is arranged on the light exit surface of the polarization beam splitter prism E8, the protective glass E9 has an object side surface S20 of the protective glass and an image side surface S21 of the protective glass, the chip is located on the image side surface S21 of the protective glass, and the imaging surface of the projection system is located on the chip.

[0095] In this embodiment, the second lens E3 and the first correction lens E4 are cemented together, that is, the image side surface S7 of the second lens and the object side surface S8 of the first correction lens are the same optically effective surface, but for the object side surface and the image side surface, when the curvature radius is the same, the surface shapes of the two are different, so the image side surface S7 of the second lens is a convex surface, and the object side surface S8 of the first correction lens is a concave surface.

[0096] Table 1 shows basic parameters of the projection system of Example 1, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm).

[0097] Table 1

[0098]

[0099] In this embodiment, the first lens to the turning prism can be designed as an aspherical surface or a spherical surface, and the surface shape of each lens can be defined by but not limited to the following aspherical surface formula:

[0100] Formula (1);

[0101] Wherein, X is the relative distance between the point on the aspheric surface and the intersection plane tangent to the optical axis of the aspheric surface at a distance Y from the optical axis; Y is the vertical distance between the point on the aspheric curve and the optical axis; R is the radius of curvature; k is the cone coefficient; Ai is the i-th order aspheric coefficient. The following Table 2 lists the high-order coefficients A4, A6, A8, A10, A12, A14, and A16 that can be used for each aspheric mirror surface in this embodiment. Wherein, the k value and high-order coefficient values ​​of surfaces 4 to 11 and surface 15 are all 0, that is, these surface types are spherical or flat.

[0102] Table 2

[0103]

[0104] Figure 3 The MTF curve of the projection system of the first embodiment is shown, which indicates the image fineness at different spatial frequencies. Figure 4 The distortion curve of the projection system of the first embodiment is shown, which indicates the distortion magnitude values ​​corresponding to different field angles. Figure 5 A relative illumination curve diagram of the projection system of the first embodiment is shown, which indicates the consistency of illumination at different image heights. Figure 6 The astigmatism curve of the projection system of the first embodiment is shown, which represents the meridional image plane curvature and the sagittal image plane curvature.

[0105] according to Figures 3 to 6 It can be seen that the projection system provided in the first embodiment can achieve good imaging quality.

[0106] Embodiment 2

[0107] like Figures 7 to 12 As shown, the projection system of the second embodiment of the present application is described. Figure 7 FIG. 2 shows a structural diagram of a projection system according to Embodiment 2. Figure 8 The optical path diagram of the projection system of the second embodiment is shown.

[0108] like Figure 7 and Figure 8 As shown, the projection system includes an aperture STO, a polarizer E1, a first lens E2, a second lens E3, a first correction lens E4, a second correction lens E5, a third lens E6, a turning prism E7, a polarization splitter prism E8, a compensation plate, a protective glass E9 and a chip arranged in sequence from the object side to the image side.

[0109] In this embodiment, the polarizing plate E1 has an object side surface S2 of the polarizing plate and an image side surface S3 of the polarizing plate; the first lens E2 has a negative optical focal length, the object side surface S4 of the first lens is a convex surface, and the image side surface S5 of the first lens is a concave surface; the second lens E3 has a positive optical focal length, the object side surface S6 of the second lens is a concave surface, and the image side surface S7 of the second lens is a convex surface; the first correction lens E4 has a positive optical focal length, the object side surface S8 of the first correction lens is a concave surface, and the image side surface S9 of the first correction lens is a convex surface; the second correction lens E5 has a negative optical focal length, the object side surface S10 of the second correction lens is a concave surface, and the image side surface S11 of the second correction lens is a convex surface; the third lens E6 has a positive optical focal length, the object side surface S12 of the third lens is a concave surface, and the image side surface S13 of the third lens is a convex surface. The side surface S13 is a convex surface; the turning prism E7 has a positive optical focal length, the first transmission surface S14 of the turning prism is a concave surface and faces the image side surface S13 of the third lens, the reflection surface S15 of the turning prism is a plane, and the optical axis of the projection system rotates 90° after passing through the reflection surface S15, and the second transmission surface S16 of the turning prism is a convex surface; the polarization beam splitter prism E8 has a light incident surface S17 and a light exit surface, the compensation plate has an object side surface S18 of the compensation plate and an image side surface S19 of the compensation plate, and the object side surface S18 of the compensation plate is arranged on the light exit surface of the polarization beam splitter prism E8, the protective glass E9 has an object side surface S20 of the protective glass and an image side surface S21 of the protective glass, the chip is located on the image side surface S21 of the protective glass, and the imaging surface of the projection system is located on the chip.

[0110] Table 3 shows basic parameters of the projection system of Example 2, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm).

[0111] Table 3

[0112]

[0113] In this embodiment, the first lens to the turning prism can be designed as an aspherical surface or a spherical surface, and the surface type of each lens can be defined by, but not limited to, formula (1) in Embodiment 1. Table 4 shows the high-order coefficients that can be used for each aspherical mirror surface in this embodiment. Among them, the k value and high-order coefficient value of surface 4 to surface 11 and surface 15 are all 0, that is, these surface types are spherical or flat.

[0114] Table 4

[0115]

[0116] Fig. 9 The MTF curve of the projection system of the second embodiment is shown, which indicates the image fineness at different spatial frequencies. Fig.10 The distortion curve of the projection system of the second embodiment is shown, which indicates the distortion magnitude values ​​corresponding to different field angles. Fig.11A relative illumination curve diagram of the projection system of the second embodiment is shown, which indicates the consistency of illumination at different image heights. Fig.12 The astigmatism curve of the projection system of the second embodiment is shown, which represents the meridional image plane curvature and the sagittal image plane curvature.

[0117] according to Figures 9 to 12 It can be seen that the projection system provided in the second embodiment can achieve good imaging quality.

[0118] Embodiment 3

[0119] like Figures 13 to 18 As shown, the projection system of the third embodiment of the present application is described. Fig.13 FIG. 4 shows a structural diagram of a projection system of Embodiment 3. Fig.14 The optical path diagram of the projection system of the third embodiment is shown.

[0120] like Fig.13 and Fig.14 As shown, the projection system includes an aperture STO, a polarizer E1, a first lens E2, a second lens E3, a first correction lens E4, a second correction lens E5, a third lens E6, a turning prism E7, a polarization splitter prism E8, a compensation plate, a protective glass E9 and a chip arranged in sequence from the object side to the image side.

[0121] In this embodiment, the polarizing plate E1 has an object side surface S2 of the polarizing plate and an image side surface S3 of the polarizing plate; the first lens E2 has a negative optical power, the object side surface S4 of the first lens is a concave surface, and the image side surface S5 of the first lens is a concave surface; the second lens E3 has a positive optical power, the object side surface S6 of the second lens is a concave surface, and the image side surface S7 of the second lens is a convex surface; the first correction lens E4 has a positive optical power, the object side surface S8 of the first correction lens is a concave surface, and the image side surface S9 of the first correction lens is a convex surface; the second correction lens E5 has a positive optical power, the object side surface S10 of the second correction lens is a concave surface, and the image side surface S11 of the second correction lens is a convex surface; the third lens E6 has a positive optical power, the object side surface S12 of the third lens is a concave surface, and the image side surface S13 of the third lens is a convex surface. The side surface S13 is a convex surface; the turning prism E7 has a positive optical focal length, the first transmission surface S14 of the turning prism is a concave surface and faces the image side surface S13 of the third lens, the reflection surface S15 of the turning prism is a plane, and the optical axis of the projection system rotates 90° after passing through the reflection surface S15, and the second transmission surface S16 of the turning prism is a convex surface; the polarization beam splitter prism E8 has a light incident surface S17 and a light exit surface, the compensation plate has an object side surface S18 of the compensation plate and an image side surface S19 of the compensation plate, and the object side surface S18 of the compensation plate is arranged on the light exit surface of the polarization beam splitter prism E8, the protective glass E9 has an object side surface S20 of the protective glass and an image side surface S21 of the protective glass, the chip is located on the image side surface S21 of the protective glass, and the imaging surface of the projection system is located on the chip.

[0122] In this embodiment, the first correction lens E4 and the second correction lens E5 are glued together, that is, the image side surface S9 of the first correction lens and the object side surface S10 of the second correction lens are the same optically effective surface, but for the object side surface and the image side surface, when the curvature radius is the same, the surface shapes of the two are different, so the image side surface S9 of the first correction lens is a convex surface, and the object side surface S10 of the second correction lens is a concave surface.

[0123] Table 5 shows the basic parameters of the projection system of Example 3, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm).

[0124] Table 5

[0125]

[0126] In this embodiment, the first lens to the turning prism can be designed as an aspherical surface or a spherical surface, and the surface type of each lens can be defined by, but not limited to, the formula (1) in the first embodiment. Table 6 shows the high-order coefficients that can be used for each aspherical mirror surface in this embodiment. Among them, the k value and the high-order coefficient value of the surface 4 to the surface 11 and the surface 15 are all 0, that is, these surface types are spherical or flat.

[0127] Table 6

[0128]

[0129] Fig.15 The MTF curve of the projection system of the third embodiment is shown, which indicates the image fineness at different spatial frequencies. Fig.16 The distortion curve of the projection system of the third embodiment is shown, which indicates the distortion magnitude values ​​corresponding to different field angles. Fig.17 A relative illumination curve diagram of the projection system of the third embodiment is shown, which indicates the consistency of illumination at different image heights. Fig.18 The astigmatism curve of the projection system of the third embodiment is shown, which represents the meridional image plane curvature and the sagittal image plane curvature.

[0130] according to Figures 15 to 18 It can be seen that the projection system provided in the third embodiment can achieve good imaging quality.

[0131] Embodiment 4

[0132] like Figures 19 to 24 As shown, the projection system of the fourth embodiment of the present application is described. Fig.19 FIG. 4 shows a structural diagram of a projection system according to Embodiment 4. Fig. 20 The optical path diagram of the projection system of the fourth embodiment is shown.

[0133] like Fig.19 and Fig. 20As shown, the projection system includes an aperture STO, a polarizer E1, a first lens E2, a second lens E3, a first correction lens E4, a second correction lens E5, a third lens E6, a turning prism E7, a polarization splitter prism E8, a compensation plate, a protective glass E9 and a chip arranged in sequence from the object side to the image side.

[0134] In this embodiment, the polarizing plate E1 has an object side surface S2 of the polarizing plate and an image side surface S3 of the polarizing plate; the first lens E2 has a negative optical focal length, the object side surface S4 of the first lens is a convex surface, and the image side surface S5 of the first lens is a concave surface; the second lens E3 has a positive optical focal length, the object side surface S6 of the second lens is a concave surface, and the image side surface S7 of the second lens is a convex surface; the first correction lens E4 has a positive optical focal length, the object side surface S8 of the first correction lens is a concave surface, and the image side surface S9 of the first correction lens is a convex surface; the second correction lens E5 has a negative optical focal length, the object side surface S10 of the second correction lens is a concave surface, and the image side surface S11 of the second correction lens is a convex surface; the third lens E6 has a positive optical focal length, the object side surface S12 of the third lens is a concave surface, and the image side surface S13 of the third lens is a convex surface. The side surface S13 is a convex surface; the turning prism E7 has a positive optical focal length, the first transmission surface S14 of the turning prism is a convex surface and faces the image side surface S13 of the third lens, the reflection surface S15 of the turning prism is a plane, and the optical axis of the projection system rotates 90° after passing through the reflection surface S15, and the second transmission surface S16 of the turning prism is a convex surface; the polarization beam splitter prism E8 has a light incident surface S17 and a light exit surface, the compensation plate has an object side surface S18 of the compensation plate and an image side surface S19 of the compensation plate, and the object side surface S18 of the compensation plate is arranged on the light exit surface of the polarization beam splitter prism E8, the protective glass E9 has an object side surface S20 of the protective glass and an image side surface S21 of the protective glass, the chip is located on the image side surface S21 of the protective glass, and the imaging surface of the projection system is located on the chip.

[0135] Table 7 shows the basic parameters of the projection system of Example 4, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm).

[0136] Table 7

[0137]

[0138] In this embodiment, the first lens to the turning prism can be designed as an aspherical surface or a spherical surface, and the surface type of each lens can be defined by, but not limited to, formula (1) in Embodiment 1. Table 8 shows the high-order coefficients that can be used for each aspherical mirror surface in this embodiment. Among them, the k value and the high-order coefficient value of surface 4 to surface 11 and surface 15 are all 0, that is, these surface types are spherical or flat.

[0139] Table 8

[0140]

[0141] Fig.21 The MTF curve of the projection system of the fourth embodiment is shown, which indicates the image fineness at different spatial frequencies. Fig. 22 The distortion curve of the projection system of the fourth embodiment is shown, which indicates the distortion magnitude values ​​corresponding to different field angles. Fig.23 A relative illumination curve diagram of the projection system of the fourth embodiment is shown, which indicates the consistency of illumination at different image heights. Fig.24 The astigmatism curve of the projection system of Example 4 is shown, which represents the meridional image plane curvature and the sagittal image plane curvature.

[0142] according to Figure 21 to Figure 24 It can be seen that the projection system provided in the fourth embodiment can achieve good imaging quality.

[0143] Embodiment 5

[0144] like Figures 25 to 30 As shown, the projection system of the fifth embodiment of the present application is described. Fig.25 FIG. 4 shows a structural diagram of a projection system of Embodiment 5. Fig.26 The optical path diagram of the projection system of the fifth embodiment is shown.

[0145] like Fig.25 and Fig.26 As shown, the projection system includes an aperture STO, a polarizer E1, a first lens E2, a second lens E3, a first correction lens E4, a third lens E6, a turning prism E7, a polarization beam splitter prism E8, a compensation plate, a protective glass E9 and a chip, which are arranged in sequence from the object side to the image side.

[0146] In this embodiment, the polarizing plate E1 has an object side surface S2 of the polarizing plate and an image side surface S3 of the polarizing plate; the first lens E2 has a negative optical power, the object side surface S4 of the first lens is a convex surface, and the image side surface S5 of the first lens is a concave surface; the second lens E3 has a positive optical power, the object side surface S6 of the second lens is a convex surface, and the image side surface S7 of the second lens is a convex surface; the first correction lens E4 has a positive optical power, the object side surface S8 of the first correction lens is a concave surface, and the image side surface S9 of the first correction lens is a convex surface; the third lens E6 has a positive optical power, the object side surface S12 of the third lens is a concave surface, and the image side surface S13 of the third lens is a convex surface; the turning prism E7 has a positive optical power, the turning prism The first transmission surface S14 of the mirror is a concave surface and faces the image side surface S13 of the third lens. The reflection surface S15 of the turning prism is a plane. The optical axis of the projection system rotates 90° after passing through the reflection surface S15. The second transmission surface S16 of the turning prism is a convex surface. The polarization beam splitter prism E8 has a light incident surface S17 and a light exit surface. The compensation plate has an object side surface S18 of the compensation plate and an image side surface S19 of the compensation plate. The object side surface S18 of the compensation plate is arranged on the light exit surface of the polarization beam splitter prism E8. The protective glass E9 has an object side surface S20 of the protective glass and an image side surface S21 of the protective glass. The chip is located on the image side surface S21 of the protective glass. The imaging surface of the projection system is located on the chip.

[0147] Table 9 shows the basic parameters of the projection system of Example 5. The units of the radius of curvature and thickness / distance are all millimeters (mm).

[0148] Table 9

[0149]

[0150] In this embodiment, the first lens to the turning prism can be designed as an aspherical surface or a spherical surface, and the surface type of each lens can be defined by, but not limited to, the formula (1) in the first embodiment. Table 10 shows the high-order coefficients that can be used for each aspherical mirror surface in this embodiment. Among them, the k value and high-order coefficient value of surfaces 4 to 9 and surfaces 15, 17, and 18 are all 0, that is, these surface types are spherical or flat.

[0151] Table 10

[0152]

[0153] Fig. 27 The MTF curve of the projection system of the fifth embodiment is shown, which indicates the image fineness at different spatial frequencies. Fig.28 The distortion curve of the projection system of the fifth embodiment is shown, which indicates the distortion magnitude values ​​corresponding to different field angles. Fig.29 A relative illumination curve diagram of the projection system of Example 5 is shown, which indicates the consistency of illumination at different image heights. Fig.30The astigmatism curve of the projection system of Example 5 is shown, which represents the meridional image plane curvature and the sagittal image plane curvature.

[0154] according to Figures 27 to 30 It can be seen that the projection system provided in the fifth embodiment can achieve good imaging quality.

[0155] Embodiment 6

[0156] like Figure 31 to Figure 36 As shown, the projection system of embodiment 6 of the present application is described. Fig.31 FIG. 4 shows a structural diagram of a projection system according to Embodiment 6. Fig.32 The optical path diagram of the projection system of the sixth embodiment is shown.

[0157] like Fig.31 and Fig.32 As shown, the projection system includes an aperture STO, a polarizer E1, a first lens E2, a second lens E3, a first correction lens E4, a third lens E6, a turning prism E7, a polarization beam splitter prism E8, a compensation plate, a protective glass E9 and a chip, which are arranged in sequence from the object side to the image side.

[0158] In this embodiment, the polarizing plate E1 has an object side surface S2 of the polarizing plate and an image side surface S3 of the polarizing plate; the first lens E2 has a negative optical power, the object side surface S4 of the first lens is a convex surface, and the image side surface S5 of the first lens is a concave surface; the second lens E3 has a positive optical power, the object side surface S6 of the second lens is a convex surface, and the image side surface S7 of the second lens is a convex surface; the first correction lens E4 has a positive optical power, the object side surface S8 of the first correction lens is a concave surface, and the image side surface S9 of the first correction lens is a convex surface; the third lens E6 has a positive optical power, the object side surface S12 of the third lens is a concave surface, and the image side surface S13 of the third lens is a convex surface; the turning prism E7 has a positive optical power, the turning prism The first transmission surface S14 of the mirror is a concave surface and faces the image side surface S13 of the third lens. The reflection surface S15 of the turning prism is a plane. The optical axis of the projection system rotates 90° after passing through the reflection surface S15. The second transmission surface S16 of the turning prism is a convex surface. The polarization beam splitter prism E8 has a light incident surface S17 and a light exit surface. The compensation plate has an object side surface S18 of the compensation plate and an image side surface S19 of the compensation plate. The object side surface S18 of the compensation plate is arranged on the light exit surface of the polarization beam splitter prism E8. The protective glass E9 has an object side surface S20 of the protective glass and an image side surface S21 of the protective glass. The chip is located on the image side surface S21 of the protective glass. The imaging surface of the projection system is located on the chip.

[0159] Table 11 shows the basic parameters of the projection system of Example 6, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm).

[0160] Table 11

[0161]

[0162] In this embodiment, the first lens to the turning prism can be designed as an aspherical surface or a spherical surface, and the surface type of each lens can be defined by, but not limited to, the formula (1) in the first embodiment. Table 12 shows the high-order coefficients that can be used for each aspherical mirror surface in this embodiment. Among them, the k value and high-order coefficient value of surfaces 4 to 9 and surfaces 15, 17, and 18 are all 0, that is, these surface types are spherical or flat.

[0163] Table 12

[0164]

[0165] Fig.33 The MTF curve of the projection system of Example 6 is shown, which represents the image fineness at different spatial frequencies. Fig.34 The distortion curve of the projection system of the sixth embodiment is shown, which indicates the distortion magnitude values ​​corresponding to different field angles. Fig.35 A relative illumination curve diagram of the projection system of Example 6 is shown, which indicates the consistency of illumination at different image heights. Fig.36 The astigmatism curve of the projection system of Example 6 is shown, which represents the meridional image plane curvature and the sagittal image plane curvature.

[0166] according to Figure 33 to Figure 36 It can be seen that the projection system provided in the sixth embodiment can achieve good imaging quality.

[0167] In summary, Embodiments 1 to 6 respectively satisfy the relationships shown in Table 13.

[0168] Table 13

[0169]

[0170] Obviously, the embodiments described above are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0171] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0172] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0173] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A projection system, characterized in that: The projection system includes, from the object side to the image side, the following: a first lens having negative optical power; a second lens having positive optical power; A correction lens group, wherein the correction lens group includes one or two lenses; a third lens having positive optical power; A turning prism, wherein the turning prism has positive optical power, and the turning prism has a first transmission surface, a reflection surface, and a second transmission surface facing the image side surface of the third lens, and the first transmission surface and the second transmission surface are both aspherical surfaces; Wherein, the focal length f of the projection system and the total optical length TTL of the projection system satisfy: <f / TTL<0.24。 2. The projection system according to claim 1, characterized in that: The focal length f1 of the first lens satisfies: -0.16<1 / f1<0.

3. The projection system according to claim 1, characterized in that: The focal length f2 of the second lens satisfies: 0<1 / f2<0.

25.

4. The projection system according to claim 1, characterized in that: The correction lens group includes a first correction lens and a second correction lens, and the focal length f3 of the first correction lens, the focal length f4 of the second correction lens, and the focal length f5 of the third lens satisfy: -0.1<(1 / f3+1 / f4+1 / f5)<0.

22.

5. The projection system according to claim 1, characterized in that: The correction lens group includes a first correction lens, and the focal length f3 of the first correction lens and the focal length f5 of the third lens satisfy: -0.1<(1 / f3+1 / f5)<0.

22.

6. The projection system according to any one of claims 1 to 5, characterized in that: The focal length f6 of the turning prism satisfies: 0<1 / f6<0.

12.

7. The projection system according to claim 1, characterized in that: The focal length f of the projection system and the maximum imaging height ImgH of the projection system satisfy: 0.7 <ImgH / f<1。 8. The projection system according to claim 1, characterized in that: The projection system further includes an aperture stop located at the object side of the first lens, and a light transmission diameter EPD of the aperture stop satisfies: 2≤EPD≤2.

4.

9. The projection system according to claim 1, characterized in that: The material of the turning prism is plastic, the reflecting surface is used to turn the incident light, the second transmitting surface is close to the image side of the projection system, and the curvature radius R62 of the reflecting surface satisfies: |R62|=∞.

10. The projection system according to claim 9, characterized in that: The curvature radius R61 of the first transmission surface satisfies: |R61|<∞, the curvature radius R63 of the second transmission surface satisfies: |R63|<∞, and the curvature radius R61 of the first transmission surface and the curvature radius R62 of the reflection surface satisfy: (1 / R61-1 / R62)>0.

11. The projection system according to claim 1, characterized in that: The minimum value Min_CT of the center thickness of all lenses in the projection system satisfies: Min_CT>0.

3.

12. The projection system according to claim 1, characterized in that: The minimum value Min_ET of the edge thickness of all lenses in the projection system satisfies: Min_ET>0.

35.

13. The projection system according to claim 1, characterized in that: The number N of components with optical focal length in the projection system satisfies: 5≤N≤6, and the maximum field of view FOV of the projection system satisfies: 70°≤FOV≤82°.

14. The projection system according to claim 1, characterized in that: The first lens, the second lens, the correction lens group and the third lens are made of glass, and the refractive indexes of the first lens, the second lens, the correction lens group and the third lens are all greater than 1.

75.

15. A near-eye display device, characterized in that: A projection system comprising the projection system of any one of claims 1 to 14.

Images