Projection lens and projection equipment

Abstract

The utility model discloses a projection lens and projection equipment. The projection lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens which are sequentially arranged at intervals from an object side to an image side along an optical axis. The first lens has positive focal power, and the object side surface of the first lens is a convex surface; the second lens has negative focal power, the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a concave surface; the third lens has positive focal power, the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a convex surface; the fourth lens has negative focal power, the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a concave surface; the fifth lens has positive focal power, and the image side surface of the fifth lens is a convex surface; the sixth lens has positive focal power, and the object side surface of the sixth lens is a convex surface. The projection lens has the characteristics of miniaturization, small distortion and high image quality, and is beneficial for realizing miniaturization design of projection equipment.

Description

Technical Field

[0001] The present application relates to the field of optical imaging technology, and more specifically, to a projection lens and a projection device. Background Art

[0002] With the rapid development of augmented reality (AR) display technology, head-mounted AR devices (such as smart glasses) have become a hot research and development object. In AR devices, the projection lens is one of the important components of AR devices. On the one hand, the projection lens needs to couple the image information in the optical machine into the optical waveguide display lens, and then incident it into the user's eyes. On the other hand, the projection lens also needs to be compatible with the lighting system of the AR device.

[0003] Therefore, designing a projection lens with compact structure and high imaging quality has become the main goal of R&D personnel. Utility Model Content

[0004] Embodiments of the present application provide a projection lens and a projection device.

[0005] According to the first aspect of the present application, an embodiment of the present application provides a projection lens, which includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in sequence from the object side to the image side along the optical axis. Among them, the first lens has positive focal power, and the object side surface of the first lens is convex; the second lens has negative focal power, the object side surface of the second lens is concave, and the image side surface of the second lens is concave; the third lens has positive focal power, the object side surface of the third lens is convex, and the image side surface of the third lens is convex; the fourth lens has negative focal power, the object side surface of the fourth lens is concave, and the image side surface of the fourth lens is concave; the fifth lens has positive focal power, and the image side surface of the fifth lens is convex; the sixth lens has positive focal power, and the object side surface of the sixth lens is convex.

[0006] In some possible embodiments, the maximum field of view of the projection lens is FOV, and FOV satisfies the relationship: FOV>40°.

[0007] In some possible embodiments, the effective focal length of the first lens is f1, the effective focal length of the third lens is f3, and f1 and f3 satisfy the relationship: 0.75 <f3 / f1<1。

[0008] In some possible embodiments, the effective focal length of the projection lens is f, the effective focal length of the fifth lens is f5, the effective focal length of the sixth lens is f6, and f, f5 and f6 satisfy the relationship: 1.6<(f / f5+f / f6)<2.

[0009] In some possible embodiments, the radius of curvature of the object side surface of the third lens is R5, the radius of curvature of the image side surface of the third lens is R6, the effective focal length of the third lens is f3, and R5, R6 and f3 satisfy the relationship: (R5-R6) / f3≥3.5.

[0010] In some possible embodiments, the effective focal length of the second lens is f2, the effective focal length of the projection lens is f, and f2 and f satisfy the relationship: -0.46≤f2 / f<0.

[0011] In some possible embodiments, the effective focal length of the fourth lens is f4, the effective focal length of the projection lens is f, and f4 and f satisfy the relationship: -0.36≤f4 / f<0.

[0012] In some possible embodiments, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are spherical lenses.

[0013] According to the second aspect of the present application, an embodiment of the present application further provides a projection device, which includes the above-mentioned projection lens and an image source; wherein the image source is used to generate a projection image; and the projection lens is used to project the projection image.

[0014] In some possible embodiments, the main light angle of the image source is CRA, and CRA satisfies the relationship: -2° <CRA≤2°。

[0015] In some possible embodiments, the distance between the object side surface of the first lens and the image source is TTL, half of the diagonal length of the light emitting area of ​​the image source is IMH, and TTL and IMH satisfy the relationship: TTL / IMH≤4.0.

[0016] In some possible embodiments, the distance between the image side surface of the sixth lens and the image source is BFL, and BFL satisfies the relationship: 2.0 mm <BFL<2.6mm。

[0017] In some possible embodiments, the entrance pupil diameter of the projection lens is EPD, half of the diagonal length of the light exit area of ​​the image source is IMH, and EPD and IMH satisfy the relationship: EPD / IMH>1.

[0018] The embodiment of the present application provides a projection lens and a projection device equipped with the projection lens, wherein the projection lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens arranged in sequence from the object side to the image side along the optical axis. Specifically, the first lens has positive optical power, the second lens has negative optical power, the third lens has positive optical power, the fourth lens has negative optical power, the fifth lens has positive optical power, and the sixth lens has positive optical power. Therefore, the present application provides a projection lens including six lenses, which has the characteristics of miniaturization, small distortion and high image quality, which is conducive to the miniaturization design of the projection device (for example, AR glasses) equipped with the projection lens and improves the image display quality of the projection device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 It is a schematic diagram of a projection device provided in an embodiment of the present application.

[0021] Figure 2 yes Figure 1 Schematic diagram of the structure of the projection lens and image source.

[0022] Figure 3 yes Figure 2 Schematic diagram of the structure of the image source.

[0023] Figure 4 yes Figure 2 Schematic diagram of the main light angle of the image source.

[0024] Figure 5 yes Figure 1 Another structural diagram of the projection lens and image source.

[0025] Figure 6 yes Figure 2 Schematic diagram of the corresponding parameters between each lens and image source.

[0026] Figure 7 is a graph of astigmatism and distortion of the projection lens provided in the first example of the present application.

[0027] Figure 8 4 is a magnification chromatic aberration curve diagram of the projection lens provided in the first example of the present application.

[0028] Fig. 9axial chromatic aberration curve of the projection lens provided in the first example of the present application.

[0029] Fig.10 is an MTF curve diagram of the projection lens provided in the first example of the present application.

[0030] Fig.11 is a CRA curve diagram of the projection lens provided in the first example of the present application.

[0031] Fig.12 4 is a graph showing the astigmatism and distortion of the projection lens provided in the second example of the present application.

[0032] Fig.13 4 is a magnification chromatic aberration curve diagram of the projection lens provided in the second example of the present application.

[0033] Fig.14 axial chromatic aberration curve of the projection lens provided in the second example of the present application.

[0034] Fig.15 is an MTF curve diagram of the projection lens provided in the second example of the present application.

[0035] Fig.16 is a CRA curve diagram of the projection lens provided in the second example of the present application. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0037] See also Figure 1 , an embodiment of the present application provides a projection lens 100 and a projection device 200 equipped with the projection lens 100. Among them, the projection device 200 may include an image source 70, an optical waveguide (not shown in the figure) and a projection lens 100, the image source 70 can be used to generate a projection image, and the projection lens 100 can be used to project the projection image. The optical waveguide is a medium device that guides the propagation of light waves therein. Specifically, the optical waveguide can be arranged on the optical path where the light waves carrying the projection image are located, which can project the above-mentioned light waves into the eyes of the user wearing the projection device 200. Specifically, the projection device 200 can be an AR device (for example, AR glasses, AR head display, etc.).

[0038] See also Figure 2The projection lens 100 provided in this embodiment may include a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, a fifth lens 50 and a sixth lens 60 which are arranged in sequence from the object side to the image side along the optical axis O. Among them, the first lens 10 has positive focal power, and the object side surface S1 of the first lens 10 is a convex surface. The second lens 20 has negative focal power, the object side surface S3 of the second lens 20 is a concave surface, and the image side surface S4 of the second lens 20 is a concave surface. The third lens 30 has positive focal power, the object side surface S5 of the third lens 30 is a convex surface, and the image side surface S6 of the third lens 30 is a convex surface. The fourth lens 40 has negative focal power, the object side surface S7 of the fourth lens 40 is a concave surface, and the image side surface S8 of the fourth lens 40 is a concave surface. The fifth lens 50 has positive focal power, and the image side surface S10 of the fifth lens 50 is a convex surface. The sixth lens 60 has positive focal power, and the object side surface S11 of the sixth lens 60 is a convex surface.

[0039] It should be noted that the above-mentioned "object side" and "image side" should be understood as the relative positional relationship between the projection lens 100 and the environment or image source 70 when used. For example, the "image side" of the above-mentioned projection lens 100 or each lens should be understood as the side facing the image source 70, and the "object side" of the above-mentioned projection lens 100 or each lens should be understood as the side where the external ambient light enters the projection lens 100. For another example, when the projection lens 100 is installed in the projection device 200 provided with the image source 70, the side where the image source 70 is located is the "image side", the sixth lens 60 is arranged close to the image side, and the first lens 10 is arranged away from the image side. The projection image generated by the projection device 200 will be transmitted to the object side through the sixth lens 60, the fifth lens 50, the fourth lens 40, the third lens 30, the second lens 20 and the first lens 10 in sequence. The "object side" can be the side of the eyes of the user wearing the projection device 200, or the side where the external ambient light enters the projection lens 100.

[0040] This embodiment provides a projection lens 100 including six lenses. The projection lens 100 has the characteristics of miniaturization, small distortion and high image quality, which is beneficial for the projection device 200 (for example, AR glasses) equipped with the projection lens 100 to achieve miniaturization design and improve the image display quality of the projection device 200.

[0041] In this embodiment, the image source 70 is used to generate a projection image. The image source 70 can modulate the incident light wave (for example, illumination light) to generate a light wave carrying the projection image and emit the light wave in a specified direction. Figure 3, the image source 70 may be provided with a light emitting area S15, and the light emitting area S15 is used to emit the light waves carrying the projection image, and the light waves carrying the projection image will be transmitted sequentially through the sixth lens 60, the fifth lens 50, the fourth lens 40, the third lens 30, the second lens 20 and the first lens 10 on the optical axis O. Of course, the incident light wave to be modulated is also incident on the image source 70 through the light emitting area S15. Specifically, the light emitting area S15 may be roughly rectangular. In this embodiment, half of the diagonal length of the light emitting area S15 is recorded as IMH, and the plane where the light emitting area S15 is located is recorded as the image plane.

[0042] See also Figure 4 In this embodiment, the chief light angle of the image source 70 is recorded as CRA, that is, CRA is the angle between the incident direction of the image plane chief light L and the direction perpendicular to the image plane. Figure 4 In the embodiment, the image plane principal ray L is incident on the image plane after being refracted by the lens group 41, wherein the lens group 41 may include the first lens 10 to the sixth lens 60 in this embodiment. Specifically, the CRA in this embodiment satisfies the relationship: -2° <CRA≤2°。

[0043] Therefore, when the projection lens 100 in this embodiment is assembled into the projection device 200, it is easy to cooperate with the illumination module (not shown in the figure) in the projection device 200, so that the incident light wave to be modulated generated by the illumination module can be accurately incident on the light exit area S15 of the image source 70, reducing the assembly difficulty of the projection lens 100. In addition, CRA≤2° also indicates that the projection lens 100 is a telecentric lens.

[0044] In this embodiment, the entrance pupil diameter (not shown in the figure) of the projection lens 100 is recorded as EPD, where EPD is the pupil diameter seen from the object space. Specifically, when the focal length of the projection lens 100 is fixed, the EPD and the F number of the projection lens 100 are inversely proportional. The EPD and IMH in this embodiment satisfy the relationship: EPD / IMH>1. Therefore, when the projection lens 100 in this embodiment is assembled into the projection device 200, it is more conducive to the energy matching between the projection lens 100 and the illumination module in the projection device 200.

[0045] In some possible embodiments, the image source 70 may be a digital micromirror device (DMD), which may include a digital micromirror array, each digital micromirror in the digital micromirror array constitutes a modulation unit, and a modulation unit is used to modulate the image corresponding to a pixel. Each digital micromirror is flipped under the drive of the driving signal generated by the control device, and the number of flips of each digital micromirror is determined by the driving signal. The flipped digital micromirror is used to modulate the incident light wave and generate a light wave carrying a projected image. In some other possible embodiments, the image source 70 may also be a high-penetration high-temperature polysilicon (HTPS) LCD display chip, a reflective LCD silicon-based liquid crystal (LCOS), a micro light emitting diode display (Micro Light Emitting Diode Display, Micro LED), etc. This embodiment does not limit the specific implementation method of the image source 70.

[0046] Please refer again Figure 2 The projection device 200 in this embodiment may further include a transmission member 80, which is disposed between the sixth lens 60 and the image source 70 and is located on the optical axis O. The transmission member 80 may be attached to one side of the image source 70 and cover the light exit area S15 to protect the light exit area S15. Specifically, the transmission member 80 may be a cover glass, and the object side surface S13 and the image side surface S14 of the cover glass may be planes.

[0047] In this embodiment, the arrangement order of the above-mentioned lenses from the object side to the image side on the optical axis O is: the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, the fifth lens 50 and the sixth lens 60, wherein two adjacent lenses may be separated by air, the distance between the sixth lens 60 and the image source 70 is the shortest, and the distance between the first lens 10 and the image source 70 is the farthest. Specifically, each lens may include an object side surface and an image side surface, and the object side surface and the image side surface are located on opposite sides of the lens. The image side surface is arranged toward the image source 70, and the object side surface is arranged away from the image source 70. Therefore, the light wave carrying the projected image generated by the image source 70 is incident into the lens via the image side surface and then emitted via the object side surface.

[0048] In this embodiment, the first lens 10 has positive focal power, that is, the first lens 10 can converge light waves. The object side surface S1 of the first lens 10 is a convex surface, and the image side surface S2 of the first lens 10 can be a convex surface, a concave surface, a flat surface, etc., which is not specifically limited in this embodiment. Specifically, Figure 2In the illustrated embodiment, the image side S2 of the first lens 10 is concave. Please refer to Figure 5 , Figure 5 in the illustrated embodiment, the image side S2 of the first lens 10 is planar.

[0049] Specifically, please refer to Figure 6 , in this embodiment, the distance between the object side S1 of the first lens 10 and the image source 70 is denoted as TTL, and TTL and IMH satisfy the relationship: TTL / IMH ≤ 4.0. Therefore, the size of the projection lens 100 in this embodiment can meet the requirements of a thin and light structure, and it is easy for the projection device 200 to balance aberrations. Among them, TTL should be understood as: the shortest distance between the object side S1 of the first lens 10 and the image plane of the image source 70 on the optical axis O.

[0050] In this embodiment, the second lens 20 has a negative focal power, that is, the second lens 20 can play a role in diverging light waves. Among them, the object side S3 of the second lens 20 can be concave, and the image side S4 of the second lens 20 is concave.

[0051] Specifically, in this embodiment, the effective focal length of the second lens 20 is denoted as f2, and the effective focal length of the projection lens 100 is denoted as f. f2 and f satisfy the relationship: -0.46 ≤ f2 / f < 0. Therefore, the second lens 20 in this embodiment can better correct off-axis aberrations, thereby ensuring the imaging quality of the projection device 200.

[0052] In this embodiment, the third lens 30 has a positive focal power, that is, the third lens 30 can play a role in converging light waves. Among them, the object side S5 of the third lens 30 is convex, and the image side S6 of the third lens 30 is convex.

[0053] Specifically, in this embodiment, the radius of curvature of the object side S5 of the third lens 30 is denoted as R5, the radius of curvature of the image side S6 of the third lens 30 is denoted as R6, and the effective focal length of the third lens 30 is denoted as f3. R5, R6, and f3 satisfy the relationship: (R5 - R6) / f3 ≥ 3.5. Therefore, when the third lens 30 in this embodiment satisfies the above formula, the shape of the third lens 30 is restricted, which is beneficial to the projection device 200 to balance aberrations.

[0054] In addition, in this embodiment, the effective focal length of the third lens 30 is denoted as f3, and the effective focal length of the first lens 10 is denoted as f1. f3 and f1 satisfy the relationship: 0.75 < f3 / f1 < 1. Therefore, the third lens 30 and the first lens 10 in this embodiment can achieve a reasonable distribution of positive focal power, thereby being beneficial to correcting off-axis aberrations and ensuring the imaging quality of the projection device 200.

[0055] In this embodiment, the fourth lens 40 has a negative focal power, that is, the fourth lens 40 can play a role in diverging light waves. Among them, the object side surface S7 of the fourth lens 40 is concave, and the image side surface S8 of the fourth lens 40 is concave.

[0056] Specifically, in this embodiment, the effective focal length of the fourth lens 40 is denoted as f4, and the effective focal length of the projection lens 100 is denoted as f. f4 and f satisfy the relationship: -0.36 ≤ f4 / f < 0. Therefore, the fourth lens 40 in this embodiment can better correct off-axis aberrations and ensure the imaging quality of the projection device 200.

[0057] In this embodiment, the fifth lens 50 has a positive focal power, that is, the fifth lens 50 can play a role in converging light waves. Among them, the image side surface S10 of the fifth lens 50 is convex. The object side surface S9 of the fifth lens 50 can be convex, or can be concave, flat, etc. This embodiment does not make specific limitations on this. Specifically, in Figure 2 the illustrated embodiment, the object side surface S9 of the fifth lens 50 is concave. In Figure 5 the illustrated embodiment, the object side surface S9 of the fifth lens 50 is convex.

[0058] In this embodiment, the sixth lens 60 has a positive focal power, that is, the sixth lens 60 can play a role in converging light waves. Among them, the object side surface S11 of the sixth lens 60 is convex, and the image side surface S12 of the sixth lens 60 can be convex, or can be concave, flat, etc. This embodiment does not make specific limitations on this. Specifically, in Figure 2 the illustrated embodiment, the image side surface S12 of the sixth lens 60 is convex. In Figure 5 the illustrated embodiment, the image side surface S12 of the sixth lens 60 is concave.

[0059] Specifically, in this embodiment, the effective focal length of the projection lens 100 is denoted as f, the effective focal length of the fifth lens 50 is denoted as f5, and the effective focal length of the sixth lens 60 is denoted as f6. f, f5, and f6 satisfy the relationship: 1.6 < (f / f5 + f / f6) < 2. Therefore, the fifth lens 50 and the sixth lens 60 can achieve a reasonable distribution of positive focal power, which is beneficial to the design of the chief ray angle of incidence CRA on the image plane.

[0060] In addition, in this embodiment, the distance between the image side surface S12 of the sixth lens 60 and the image source 70 is denoted as BFL, and BFL satisfies the relationship: 2.0 mm < BFL < 2.6 mm. Therefore, the lenses in the projection lens 100 in this embodiment are more adapted to the image source 70. As Figure 6 shown, BFL should be understood as: the shortest distance between the image side surface S12 of the sixth lens 60 and the image plane of the image source 70 on the optical axis O.

[0061] Furthermore, in this embodiment, the maximum field of view of the projection lens 100 is recorded as FOV. On the one hand, when the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, the fifth lens 50 and the sixth lens 60 all meet the above-mentioned optical power and surface conditions, it is conducive to the reasonable distribution of the optical power of the projection lens 100, and it is easy to achieve the optical balance of the projection lens 100 and correct various aberrations. On the other hand, the FOV in this embodiment satisfies the relationship: FOV>40°, which is conducive to the projection lens 100 meeting the field of view angle requirements and ensures that the projection field of view of the projection lens 100 is large enough.

[0062] In addition, it is not difficult to find that the projection lens 100 in this embodiment can also satisfy TTL / IMH≤4.0 when the maximum field of view angle (that is, the diagonal field of view angle) is greater than 40°, which means that the projection lens 100 has the advantages of a sufficiently large projection field of view and a thin lens size.

[0063] Please refer again Figure 2 The projection lens 100 in this embodiment may further include a stop STO, which is disposed on the side of the first lens 10 away from the image source 70 and is used to limit the intensity of the incident light wave. Specifically, the stop STO may be an aperture stop or a field stop, etc.

[0064] It is not difficult to find here that the projection lens 100 in this embodiment adopts a pre-aperture structure, so that the head size of the projection lens 100 can be minimized. When the projection lens 100 is used in the projection device 200, the pre-aperture structure can achieve better optical matching between the projection lens 100 and the coupling region of the optical waveguide, so as to improve the projection quality of the projection device 200.

[0065] In this embodiment, the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, the fifth lens 50 and the sixth lens 60 are all spherical lenses. Therefore, the projection lens 100 adopts a lens architecture of a spherical lens, which can reduce the processing cost of the projection lens 100. It should be noted that the relative aperture F number of the projection lens 100 in this embodiment can reach 2.5, indicating that the luminous flux of the projection lens 100 is relatively large, so as to ensure the projection quality of the projection device 200.

[0066] Please refer to Table 1, which shows a basic parameter table of the projection device 200 provided in the first example of the present application. Figure 2 The projection lens 100 is shown.

[0067] Table-1

[0068] Face number Surface type Radius of curvature thickness Material Semi-caliber STO Spherical endless 1 1.6 S1 Spherical 3.7 1.4 1.83,42.7 2.2 S2 Spherical 49.2 0.3 2.1 S3 Spherical -14.9 0.6 1.73,28.3 2.0 S4 Spherical 3.3 0.4 1.9 S5 Spherical 5.9 1.3 1.88,39.2 2.0 S6 Spherical -5.9 0.7 2.0 S7 Spherical -3.1 0.8 1.76,26.7 1.9 S8 Spherical 8.2 0.7 2.2 S9 Spherical -9.7 0.9 1.91,35.3 2.3 S10 Spherical -7.0 0.1 2.6 S11 Spherical 10.2 1.8 1.88,39.2 3.4 S12 Spherical -10.2 0.9 3.4 S13 Spherical endless 1.7 1.52,64.2 3.2 S14 Spherical endless 0.001 3.1 S15 Spherical endless 0 3.1

[0069] The units of the radius of curvature, thickness and semi-aperture are all millimeters (mm). The first parameter in each cell of the material column is the refractive index of the corresponding lens, and the second parameter is the dispersion coefficient of the corresponding lens. Here, 1.83 and 42.7 are taken as examples to indicate that the refractive index of the first lens 10 is 1.83 and the dispersion coefficient of the first lens 10 is 42.7.

[0070] Please refer to Table 2, which shows the optical parameter table of the projection device 200 provided in the first example of the present application.

[0071] Table-2

[0072] FOV(°) 41.2 TTL / IMH 3.80 CRA(°) 2.0 BFL(mm) 2.54 f3 / f1 0.76 f2 / f -0.45 (f / f5+f / f6) 1.67 f4 / f -0.35 (R5-R6) / f3 3.4 EPD / IMH 1.04

[0073] Specifically, in the first example, IMH is 3.05 mm, TTL is 11.6 mm, and f is 7.9 mm.

[0074] See also Figure 7 , Figure 7 The astigmatism and distortion curves of the projection lens 100 provided in the first example of the present application are shown. Figure 7 The left side of is the field curvature curve (Field Curvature), in which the three solid lines represent the meridian image curvature at wavelengths of 637nm, 520nm and 450nm, and the three dotted lines represent the sagittal image curvature at wavelengths of 637nm, 520nm and 450nm. Figure 7 The right side of is the distortion curve (Distortion), which indicates the distortion size corresponding to different image heights. Figure 7 It is not difficult to see that the optical distortion is less than 2%. Therefore, the image projected by the projection lens 100 provided in the first example has a relatively small degree of distortion.

[0075] See also Figure 8 , Figure 8 The magnification chromatic aberration curve of the projection lens 100 provided in the first example of the present application is shown. The magnification chromatic aberration curve represents the magnitude of the magnification chromatic aberration corresponding to different image heights. Figure 8 It is not difficult to see that the magnification chromatic aberration is less than 3.0 um. Therefore, the image projected by the projection lens 100 provided in the first example has a higher definition.

[0076] See also Fig. 9 , Fig. 9 The axial chromatic aberration curve of the projection lens 100 provided in the first example of the present application is shown. Fig. 9 The three curves in the figure correspond to wavelengths of 637nm, 520nm and 450nm respectively. The axial chromatic aberration curve indicates the size of the chromatic aberration corresponding to different apertures in the central field of view. Figure 8 and Fig. 9It is not difficult to see that the chromatic aberration of the projection lens 100 is relatively small. Therefore, the image lines projected by the projection lens 100 will not have obvious color edges, and there will be no obvious color dispersion spots in the center of the image.

[0077] See also Fig.10 , Fig.10 The MTF curve of the projection lens 100 provided in the first example of the present application is shown. The MTF curve represents the relationship between the modulation transfer function (MTF) and the spatial frequency corresponding to different image heights. Fig.11 , Fig.11 The CRA curve of the projection lens 100 provided in the first example of the present application is shown. The CRA curve represents the size of the incident angle (Incident Angle in Degrees) of the image plane chief ray corresponding to different image heights. Fig.11 It is not difficult to see that the CRA value is small, indicating that the projection device 200 is a telecentric lens, which is beneficial to improve the matching degree between the lens and the image source 70 (ie, the projection chip).

[0078] In summary, from Figures 7 to 11 It is not difficult to find from the curve graphs shown that the projection device 200 provided in the first example of the present application has good projection performance.

[0079] Please refer to Table 3, which shows a basic parameter table of the projection device 200 provided in the second example of the present application. Figure 5 The projection lens 100 is shown.

[0080] Table-3

[0081]

[0082]

[0083] The units of the radius of curvature, thickness and semi-aperture are all millimeters (mm). The first parameter in each cell of the material column is the refractive index of the corresponding lens, and the second parameter is the dispersion coefficient of the corresponding lens. Here, 1.82, 46.6 are taken as examples, indicating that the refractive index of the first lens 10 is 1.82 and the dispersion coefficient of the first lens 10 is 46.6.

[0084] Please refer to Table 4, which shows an optical parameter table of the projection device 200 provided in the second example of the present application.

[0085] Table-4

[0086] FOV(°) 43 TTL / IMH 4.0 CRA(°) 1.0 BFL(mm) 2.16 f3 / f1 0.96 f2 / f -0.46 (f / f5+f / f6) 1.92 f4 / f -0.36 (R5-R6) / f3 3.5 EPD / IMH 1.06

[0087] Specifically, in the second example, IMH is 2.87 mm, TTL is 11.6 mm, and f is 7.6 mm.

[0088] See also Fig.12 , Fig.12 The astigmatism and distortion curves of the projection lens 100 provided in the second example of the present application are shown. Fig.12 The left side of is the field curvature curve (Field Curvature), in which the three solid lines represent the meridian image curvature at wavelengths of 637nm, 520nm and 450nm, and the three dotted lines represent the sagittal image curvature at wavelengths of 637nm, 520nm and 450nm. Fig.12 The right side of is the distortion curve (Distortion), which indicates the distortion size corresponding to different image heights. Fig.12 It is not difficult to see that the optical distortion is less than 1%. Therefore, the image projected by the projection lens 100 provided in the second example has a relatively small degree of distortion.

[0089] See also Fig.13 , Fig.13 The chromatic aberration curve of the projection lens 100 provided in the second example of the present application is shown. The chromatic aberration curve of the chromatic aberration of the magnification indicates the magnitude of the chromatic aberration ... magnification corresponding to different image heights. Fig.13 It is not difficult to see that the magnification chromatic aberration is less than 3.0 um. Therefore, the image projected by the projection lens 100 provided in the second example has a higher definition.

[0090] See also Fig.14 , Fig.14 The axial chromatic aberration curve of the projection lens 100 provided in the second example of the present application is shown. Fig.14 The three curves in the figure correspond to wavelengths of 637nm, 520nm and 450nm respectively. The axial chromatic aberration curve indicates the size of the chromatic aberration corresponding to different apertures in the central field of view. Fig.13 and Fig.14 It is not difficult to see that the color difference of the projection device 200 is small. Therefore, the image lines projected by the projection device 200 will not have obvious color edges, and there will be no obvious color dispersion spots in the center of the image.

[0091] See also Fig.15 , Fig.15 The MTF curve of the projection lens 100 provided in the second example of the present application is shown. The MTF curve represents the relationship between the modulation transfer function (MTF) and the spatial frequency corresponding to different image heights. Fig.16 , Fig.16The CRA curve of the projection device 200 provided in the second example of the present application is shown. The CRA curve represents the size of the incident angle (Incident Angle in Degrees) of the image plane chief ray corresponding to different image heights. Fig.16 It is not difficult to see that the CRA value is small, indicating that the projection device 200 is a telecentric lens, which is beneficial to improve the matching degree between the lens and the image source 70 (ie, the projection chip).

[0092] In summary, from Figures 12 to 16 It is not difficult to find from the curve graphs shown that the projection device 200 provided in the first example of the present application has good projection performance.

[0093] It is not difficult to see here that, compared with the projection lens 100 provided in the first example, the projection lens 100 in the second example can reduce the optical distortion by 1% when the shapes of the fifth lens 50 and the sixth lens 60 are different, so that the projection lens 100 has better imaging quality. In addition, the exit pupil distance (thickness corresponding to STO) can be reduced by 0.8 mm, and the overall structure is more compact, which can save the installation space of the projection device 200 and is conducive to the miniaturization design of the projection device 200.

[0094] The embodiment of the present application provides a projection lens 100 and a projection device 200 equipped with the projection lens 100. The projection lens 100 may include a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, a fifth lens 50 and a sixth lens 60 arranged in sequence from the object side to the image side along the optical axis O. Among them, the first lens 10 has positive optical power, and the object side surface S1 of the first lens 10 is a convex surface. The second lens 20 has negative optical power, the object side surface S3 of the second lens 20 is a concave surface, and the image side surface S4 of the second lens 20 is a concave surface. The third lens 30 has positive optical power, the object side surface S5 of the third lens 30 is a convex surface, and the image side surface S6 of the third lens 30 is a convex surface. The fourth lens 40 has negative optical power, the object side surface S7 of the fourth lens 40 is a concave surface, and the image side surface S8 of the fourth lens 40 is a concave surface. The fifth lens 50 has positive optical power, and the image side surface S10 of the fifth lens 50 is a convex surface. The sixth lens element 60 has positive refractive power, and the object-side surface S11 of the sixth lens element 60 is a convex surface.

[0095] This embodiment provides a projection lens 100 including six lenses. The projection lens 100 has the characteristics of miniaturization, small distortion and high image quality, which is beneficial for the projection device 200 (for example, AR glasses) equipped with the projection lens 100 to achieve miniaturization design and improve the image display quality of the projection device 200.

[0096] In the specification of this application, certain words are used to refer to specific components in the specification and claims. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. The specification and claims do not use the difference in name as a way to distinguish components, but use the difference in function of the components as the criterion for distinction. For example, "including" mentioned throughout the specification and claims is an open term, so it should be interpreted as "including but not limited to"; "substantially" means that those skilled in the art can solve technical problems within a certain error range and basically achieve technical effects.

[0097] In the description of the present application, it should be understood that terms such as "upper", "lower", "front", "back", "left", "right", and "inside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are merely simplified descriptions for the convenience of describing the present application. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0098] In this application, unless otherwise clearly specified or limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can be internal communication between two elements, or it can be only surface contact. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0099] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0100] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A projection lens, characterized in that: It includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens which are sequentially arranged from the object side to the image side along the optical axis; The first lens has positive optical power, and the object side surface of the first lens is convex; The second lens has negative optical power, the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a concave surface; The third lens has positive power, the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a convex surface; The fourth lens has negative optical power, the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a concave surface; The fifth lens has positive refractive power, and the image side surface of the fifth lens is a convex surface; The sixth lens has positive refractive power, and the object side surface of the sixth lens is a convex surface.

2. The projection lens according to claim 1, characterized in that: The maximum field of view of the projection lens is FOV, and the FOV satisfies the relationship: FOV>40°.

3. The projection lens according to claim 1, characterized in that: The effective focal length of the first lens is f1, the effective focal length of the third lens is f3, and f1 and f3 satisfy the relationship: 0.75 <f3 / f1<1。 4. The projection lens according to claim 1, characterized in that: The effective focal length of the projection lens is f, the effective focal length of the fifth lens is f5, the effective focal length of the sixth lens is f6, and f, f5 and f6 satisfy the relationship: 1.6<(f / f5+f / f6)<2.

5. The projection lens according to claim 1, wherein: The radius of curvature of the object side surface of the third lens is R5, the radius of curvature of the image side surface of the third lens is R6, the effective focal length of the third lens is f3, and R5, R6 and f3 satisfy the relationship: (R5-R6) / f3≥3.

5.

6. The projection lens according to claim 1, wherein: The effective focal length of the second lens is f2, the effective focal length of the projection lens is f, and f2 and f satisfy the relationship: -0.46≤f2 / f<0.

7. The projection lens according to claim 1, wherein: The effective focal length of the fourth lens is f4, the effective focal length of the projection lens is f, and f4 and f satisfy the relationship: -0.36≤f4 / f<0.

8. The projection lens according to any one of claims 1 to 7, characterized in that: The first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are spherical lenses.

9. A projection device, characterized in that: A projection lens and an image source as claimed in any one of claims 1 to 8; The image source is used to generate a projection image; The projection lens is used to project the projection image.

10. The projection device according to claim 9, characterized in that: The main light angle of the image source is CRA, and the CRA satisfies the relationship: -2° <CRA≤2°。 11. The projection device according to claim 9, characterized in that: The distance between the object side surface of the first lens and the image source is TTL, half of the diagonal length of the light emitting area of ​​the image source is IMH, and the TTL and the IMH satisfy the relationship: TTL / IMH≤4.

0.

12. The projection device according to claim 9, characterized in that: The distance between the image side surface of the sixth lens and the image source is BFL, and the BFL satisfies the relationship: 2.0 mm <BFL<2.6mm。 13. The projection device according to claim 9, characterized in that: The entrance pupil diameter of the projection lens is EPD, half of the diagonal length of the light exit area of ​​the image source is IMH, and the EPD and the IMH satisfy the relationship: EPD / IMH>1.

Images