Projection lens and projection equipment

Abstract

The invention discloses a projection lens and projection equipment. The projection lens comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are sequentially arranged at intervals from an object side to an image side along an optical axis. Wherein 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, and the image side surface of the second lens is a concave surface; the third lens has negative focal power, the object side surface of the third lens is a concave surface, and the image side surface of the third lens is a convex surface; the fourth lens has positive 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 convex surface; the fifth lens has positive focal power, the object side surface of the fifth lens is a convex surface, and the image side surface of the fifth lens is a convex surface. The invention provides a projection lens comprising five lenses. The projection lens has the characteristics of miniaturization, small distortion and high image quality.

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. Summary of the invention

[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, and a fifth 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 a convex surface; the second lens has negative focal power, and the image side surface of the second lens is a concave surface; the third lens has negative focal power, and the object side surface of the third lens is a concave surface, and the image side surface of the third lens is a convex surface; the fourth lens has positive focal power, and the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a convex surface; the fifth lens has positive focal power, and the object side surface of the fifth lens is a convex surface, and the image side surface of the fifth lens is a convex surface.

[0006] 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.

[0007] 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 and a fifth 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 negative optical power, the fourth lens has positive optical power, and the fifth lens has positive optical power. Therefore, the present application provides a projection lens including five lenses, which has the characteristics of miniaturization, small distortion and high image quality, which is conducive to the projection device (for example, AR glasses) equipped with the projection lens to achieve miniaturization design and improve the image display quality of the projection device. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] 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.

[0009] Figure 1 It is a schematic diagram of a projection device provided in an embodiment of the present application.

[0010] Figure 2 yes Figure 1 Schematic diagram of the structure of the projection lens and image source.

[0011] Figure 3 yes Figure 2 Schematic diagram of the structure of the image source.

[0012] Figure 4 yes Figure 2 Schematic diagram of the main light angle of the image source.

[0013] Figure 5 yes Figure 2 Schematic diagram of the corresponding parameters between each lens and image source.

[0014] Figure 6 This is a graph of astigmatism and distortion of the projection device provided in the first example of the present application.

[0015] Figure 7 This is a magnification chromatic aberration curve diagram of the projection device provided in the first example of the present application.

[0016] Figure 8 This is an on-axis chromatic aberration curve diagram of the projection device provided in the first example of the present application.

[0017] Fig. 9 This is a relative illumination curve diagram of the projection device provided in the first example of the present application.

[0018] Fig.10 It is a CRA curve diagram of the projection device provided in the first example of this application.

[0019] Fig.11 This is a graph of astigmatism and distortion of the projection device provided in the second example of the present application.

[0020] Fig.12 This is a magnification chromatic aberration curve diagram of the projection device provided in the second example of the present application.

[0021] Fig.13 This is an on-axis chromatic aberration curve diagram of the projection device provided in the second example of the present application.

[0022] Fig.14 This is a relative illumination curve diagram of the projection device provided in the second example of the present application.

[0023] Fig.15 This is a CRA curve diagram of the projection device provided in the second example of the present application. DETAILED DESCRIPTION

[0024] 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.

[0025] 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 60, an optical waveguide (not shown in the figure) and the above-mentioned projection lens 100, the image source 60 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.).

[0026] 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 and a fifth lens 50 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, and the image side surface S4 of the second lens 20 is a concave surface. The third lens 30 has negative focal power, the object side surface S5 of the third lens 30 is a concave surface, and the image side surface S6 of the third lens 30 is a convex surface. The fourth lens 40 has positive 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 convex surface. The fifth lens 50 has positive focal power, the object side surface S9 of the fifth lens 50 is a convex surface, and the image side surface S10 of the fifth lens 50 is a convex surface. It should be noted here 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 60 when used. For example, the "image side" of the above-mentioned projection lens 100 or each lens should be understood as the side where the image source 60 is located, 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 60, the side where the image source 60 is located is the "image side", the fifth lens 50 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 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.

[0027] This embodiment provides a projection lens 100 including five 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.

[0028] In this embodiment, the image source 60 is used to generate a projection image. The image source 60 can modulate the incident light wave to generate a light wave carrying the projection image and emit the light wave in a specified direction. Figure 3, the image source 60 may include a light-emitting area S15 for emitting the light wave carrying the projection image. The light wave carrying the projection image will sequentially pass through 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 also enters the image source 60 through the light-emitting area S15. Specifically, the light-emitting area S15 may be generally rectangular. In this embodiment, half of the diagonal length of the light-emitting area S15 is denoted as IMH, and the plane where the light-emitting area S15 is located is denoted as the image plane.

[0029] Please refer to Figure 4 , in this embodiment, the principal light angle of the image source 60 is denoted as CRA. That is, CRA is the angle between the incident direction of the principal light ray L of the image plane and the direction perpendicular to the image plane. In Figure 4 , the principal light ray L of the image plane enters the image plane after being refracted by the lens group 41. Among them, the lens group 41 may include the first lens 10 to the fifth lens 50 in this embodiment. Specifically, CRA in this embodiment satisfies the relationship: -1° < CRA < 1°. Therefore, when the projection lens 100 in this embodiment is assembled into the projection device 200, it is easy to cooperate with the lighting module (not shown in the figure) in the projection device 200, so that the incident light wave to be modulated generated by the lighting module can accurately enter the light-emitting area S15 of the image source 60, reducing the assembly difficulty of the projection lens 100.

[0030] In this embodiment, the entrance pupil diameter (not shown in the figure) of the projection lens 100 is denoted as EPD. Among them, EPD is the pupil diameter seen from the object space. Specifically, when the focal length of the projection lens 100 is fixed, EPD and the F-number of the projection lens 100 are in an inverse proportional relationship. EPD and IMH in this embodiment satisfy the relationship: 1.1 < EPD / IMH < 1.34. Therefore, when the projection lens 100 in this embodiment is assembled into the projection device 200, it is more beneficial for the projection lens 100 and the lighting module in the projection device 200 to perform energy matching.

[0031] In some possible embodiments, the image source 60 may be a Digital Micromirror Device (DMD). The DMD 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 one pixel. Each digital micromirror flips under the drive of a drive signal generated by a control device. The number of flips of each digital micromirror is determined by the drive signal. The flipped digital micromirrors are used to modulate the incident light wave and generate a light wave carrying a projection image. In some other possible embodiments, the image source 60 may also be a High-Temperature Poly Silicon (HTPS) LCD display chip, a Liquid Crystal on Silicon (LCOS) of a reflective LCD, a MicroLight Emitting Diode Display (Micro LED), etc. The specific implementation manner of the image source 60 is not limited in this embodiment.

[0032] In this embodiment, the above lenses are arranged on the optical axis O in the order from the object side to the image side as follows: the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, and the fifth lens 50. Among them, the adjacent two lenses may be spaced by air. The distance between the fifth lens 50 and the image source 60 is the closest, and the distance between the first lens 10 and the image source 60 is the farthest. Specifically, each lens may include an object side and an image side, and the object side and the image side are located on opposite sides of the lens. Among them, the image side faces the image source 60, and the object side faces away from the image source 60. Therefore, the light wave carrying the projection image generated by the image source 60 enters the lens through the image side and exits through the object side.

[0033] In this embodiment, the first lens 10 has a positive optical power, that is, the first lens 10 can play a role in converging the light wave. Among them, the object side S1 of the first lens 10 is a convex surface, and the image side S2 of the first lens 10 may be a convex surface, a concave surface, a plane, etc. This embodiment does not make specific limitations on this. Specifically, please refer to Figure 5 , in this embodiment, the central thickness of the first lens 10 on the optical axis O is denoted as CT1, and the edge thickness of the first lens 10 on the optical axis O is denoted as ET1. CT1 and ET1 satisfy the relationship: 1.2 < CT1 / ET1 < 1.4. Therefore, the first lens 10 is generally in the shape of "thick in the middle and thin on both sides", ensuring the processability of the first lens 10.

[0034] In addition, in this embodiment, the distance between the object side S1 of the first lens 10 and the image source 60 is TTL, and TTL and IMH satisfy the relational expression: 6.0 < TTL / IMH < 7.7. 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 60 on the optical axis O.

[0035] In this embodiment, the second lens 20 has a negative optical 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 a convex surface, a concave surface, a flat surface, etc. This embodiment does not make specific limitations on this. The image side S4 of the second lens 20 is a concave surface. 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 relational expression: -1.1 < 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.

[0036] In this embodiment, the third lens 30 has a negative optical power, that is, the third lens 30 can play a role in diverging light waves. Among them, the object side S5 of the third lens 30 is a concave surface, and the image side S6 of the third lens 30 is a convex surface.

[0037] In this embodiment, the fourth lens 40 has a positive optical power, that is, the fourth lens 40 can play a role in converging light waves. Among them, the object side S7 of the fourth lens 40 is a concave surface, and the image side S8 of the fourth lens 40 is a convex surface. Specifically, in this embodiment, the central thickness of the fourth lens 40 is denoted as CT4, and the edge thickness of the fourth lens 40 is denoted as ET4. CT4 and ET4 satisfy the relational expression: 2.0 < CT4 / ET4 < 2.8. Therefore, the fourth lens 40 is generally in the shape of "thick in the middle and thin on both sides". On the one hand, the fourth lens 40 adopting the above structure can better balance the phase difference; on the other hand, it also ensures the processability of the fourth lens 40.

[0038] Specifically, in this embodiment, the effective focal length of the first lens 10 is denoted as f1, and the effective focal length of the fourth lens 40 is denoted as f4. f1 and f4 satisfy the relational expression: 0.8 < f4 / f1 < 1.1. Therefore, the fourth lens 40 and the first lens 10 can achieve a reasonable distribution of positive optical power, which is beneficial to correcting off-axis aberrations and ensuring the imaging quality of the projection device 200.

[0039] In this embodiment, the fifth lens 50 has a positive optical power, that is, the fifth lens 50 can play a role in converging light waves. Among them, the object side surface S9 of the fifth lens 50 is a convex surface, and the image side surface S10 of the fifth lens 50 is a convex surface. Specifically, in this embodiment, the radius of curvature of the object side surface of the fifth lens 50 is denoted as R9, the radius of curvature of the image side surface of the fifth lens 50 is denoted as R10, and the effective focal length of the fifth lens 50 is denoted as f5. R9, R10, and f5 satisfy the relational expression: 3.2 < (R9 - R10) / f5 < 3.7. Therefore, the fifth lens 50 is generally in the shape of "thicker in the middle and thinner on both sides", and enables the fifth lens 50 to effectively balance the aberration of the projection lens 100.

[0040] In addition, in this embodiment, the distance between the image side surface S10 of the fifth lens 50 and the image source 60 is denoted as BFL. TTL and BFL satisfy the relational expression: 0.4 < BFL / TTL < 0.5. Therefore, the lenses in the projection lens 100 in this embodiment are more adapted to the image source 60. Among them, BFL should be understood as: the shortest distance between the image side surface S10 of the fifth lens 50 and the image plane of the image source 60 on the optical axis O.

[0041] Furthermore, in this embodiment, the maximum field of view angle of the projection lens 100 is denoted as FOV. On the one hand, when the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, and the fifth lens 50 all meet the above-mentioned optical power and surface type conditions, it is beneficial to the reasonable distribution of the optical power of the projection lens 100, easy to achieve the optical balance of the projection lens 100, and can correct various aberrations. On the other hand, the FOV in this embodiment satisfies the relational expression: 30° < FOV < 35°, which is beneficial for the projection lens 100 to meet the field of view angle requirements and ensures that the projection field of view range of the projection lens 100 is large enough.

[0042] Please refer to again Figure 2 , the projection lens 100 in this embodiment may further include a diaphragm STO. The diaphragm STO is disposed on the side of the first lens 10 facing away from the image source 60, and is used to limit the intensity of the incident light wave. Specifically, the diaphragm STO may be an aperture diaphragm or a field diaphragm, etc.

[0043] The projection lens 100 in this embodiment may further include a first transmission member 70 and a second transmission member 80, wherein the first transmission member 70 and the second transmission member 80 are sequentially arranged between the fifth lens 50 and the image source 60, and are located on the optical axis O. The first transmission member 70 can refract light waves. Specifically, the first transmission member 70 can be a right-angle prism, and the object side surface S11 and the image side surface S12 of the right-angle prism can be planes. The second transmission member 80 can be attached to one side of the image source 60 and cover the light emitting area S15 to protect the light emitting area S15. Specifically, the second transmission member 80 can be a cover glass, and the object side surface S13 and the image side surface S14 of the cover glass can be planes.

[0044] In this embodiment, the first lens 10, the second lens 20, the third lens 30, the fourth lens 40 and the fifth lens 50 may include an aspherical lens, and the remaining lenses are spherical lenses. Therefore, the projection lens 100 adopts a lens structure of one aspherical lens and four spherical lenses. Since an aspherical lens is provided in the projection lens 100, the imaging quality of the projection lens 100 can be significantly improved, and the size of the lens can be reduced, thereby realizing a miniaturized design of the projection lens 100.

[0045] In some possible embodiments, the fourth lens 40 may be an aspherical lens, and the first lens 10, the second lens 20, the third lens 30 and the fifth lens 50 may be spherical lenses. 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.

[0046] Table-1

[0047]

[0048]

[0049] 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, 1.90 and 31.3 are taken as examples, indicating that the refractive index of the first lens 10 is 1.90 and the dispersion coefficient of the first lens 10 is 31.3.

[0050] Please refer to Table 2, which shows the surface coefficient table of the aspheric lens (ie, the fourth lens 40) provided in the first example of the present application.

[0051] Table-2

[0052] Face number K A B C D S7 -1.359E+01 -1.008E-03 9.038E-05 9.516E-05 -3.528E-05 S8 -1.368E-01 -4.671E-05 3.936E-05 -1.197E-05 8.819E-06 Face number E F G H J S7 5.062E-06 -2.333E-07 0 0 0 S8 -1.691E-06 1.181E-07 0 0 0

[0053] Please refer to Table 3, which shows the optical parameter table of the projection device 200 provided in the first example of the present application.

[0054] Table-3

[0055] FOV(°) 35 TTL / IMH 7.64 CRA(°) 1 BFL / TTL 0.53 f4 / f1 0.8 f2 / f -1.10 CT1 / ET1 1.30 CT4 / ET4 2.30 (R9-R10) / f5 3.61 EPD / IMH 1.31

[0056] Specifically, in the first example, IMH is 2.16 mm, TTL is 16.5 mm, and f is 6.9 mm.

[0057] See also Figure 6 , Figure 6 The astigmatism and distortion curves of the projection device 200 provided in the first example of the present application are shown. Figure 6 The left side of is the field curvature curve (Field Curvature), in which the three T lines represent the meridian image curvature at wavelengths of 615nm, 540nm and 455nm, and the three S lines represent the sagittal image curvature at wavelengths of 615nm, 540nm and 455nm. Figure 6 The right side of is the distortion curve (Distortion), which indicates the distortion size corresponding to different image heights. Figure 6 It is not difficult to see that the astigmatism of the projection device 200 is less than 0.1 mil, and the optical distortion is less than 1%. Therefore, the distortion degree of the image projected by the projection device 200 provided in the first example is relatively small.

[0058] See also Figure 7 , Figure 7 The magnification chromatic aberration curve of the projection device 200 provided in the first example of the present application is shown. The reference wavelength is 540nm, and the magnification chromatic aberration curve represents the magnitude of the magnification chromatic aberration corresponding to different image heights. Figure 8 , Figure 8 The axial chromatic aberration curve diagram of the projection device 200 provided in the first example of the present application is shown. Figure 8 The three curves in the figure correspond to wavelengths of 615nm, 540nm and 455nm respectively. The axial chromatic aberration curve indicates the size of the chromatic aberration corresponding to different apertures in the central field of view. Figure 7 and Figure 8 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.

[0059] See also Fig. 9 , Fig. 9 The relative illumination curve of the projection device 200 provided in the first example of the present application is shown. The wavelength is 540nm, and the relative illumination curve represents the relative illumination (Relative illumination) corresponding to different image heights. Fig. 9It is not difficult to see that the illumination at the edge of the field of view is higher, so the illumination distribution of the image projected by the projection device 200 is more uniform.

[0060] See also Fig.10 , Fig.10 The CRA curve of the projection device 200 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.10 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 improving the matching degree between the lens and the image source 60 (ie, the projection chip).

[0061] In some other possible embodiments, the third lens 30 is an aspherical lens, and the first lens 10, the second lens 20, the fourth lens 40 and the fifth lens 50 are spherical lenses. Please refer to Table 4, which shows a basic parameter table of the projection device 200 provided in the second example of the present application.

[0062] Table-4

[0063] Face number Surface type Radius of curvature thickness Material Semi-caliber STO Spherical endless 0 1.45 S1 Spherical 4.332 1.000 1.85,32.3 1.53 S2 Spherical -2043.237 0.200 1.51 S3 Spherical 8.253 0.650 1.74,27.8 1.49 S4 Spherical 3.090 1.201 1.40 S5 Aspheric -2.535 1.200 1.92,20.9 1.49 S6 Aspheric -38.048 0.150 2.27 S7 Spherical -95.291 1.670 1.82,46.6 2.49 S8 Spherical -4.157 0.200 2.82 S9 Spherical 14.007 1.429 1.82,46.6 3.31 S10 Spherical -12.903 0.130 3.33 S11 Spherical endless 7.000 1.51,64.2 3.50 S12 Spherical endless 0.100 3.50 S13 Spherical endless 0.700 1.51,64.2 3.50 S14 Spherical endless 0.300 3.50 S15 Spherical endless 0.000 2.19

[0064] 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, 1.85, 32.3 are taken as examples, indicating that the refractive index of the first lens 10 is 1.85 and the dispersion coefficient of the first lens 10 is 32.3.

[0065] Please refer to Table 5, which shows the surface coefficient table of the aspheric lens (ie, the third lens 30) provided in the second example of the present application.

[0066] Table-5

[0067] Face number K A B C D S5 -1.626E-01 -2.054E-03 3.440E-03 -6.137E-03 5.912E-03 S6 9.000E+01 2.666E-03 -7.152E-04 5.312E-04 -9.472E-05 Face number E F G H J S5 2.618E-05 -6.156E-03 5.570E-03 -2.018E-03 2.691E-04 S6 -1.001E-04 6.353E-05 -1.560E-05 1.802E-06 -8.106E-08

[0068] Please refer to Table 6, which shows the optical parameter table of the projection device 200 provided in the second example of the present application.

[0069] Table-6

[0070] FOV(°) 34 TTL / IMH 7.34 CRA(°) 1 BFL / TTL 0.51 f4 / f1 1.04 f2 / f -0.98 CT1 / ET1 1.38 CT4 / ET4 2.76 (R9-R10) / f5 3.21 EPD / IMH 1.41

[0071] Specifically, in the second example, IMH is 2.17 mm, TTL is 15.9 mm, and f is 7.1 mm.

[0072] See also Fig.11 , Fig.11The astigmatism and distortion curves of the projection device 200 provided in the second example of the present application are shown. Fig.11 The left side of is the field curvature curve (Field Curvature), in which the three T lines represent the meridian image curvature at wavelengths of 615nm, 540nm and 455nm, and the three S lines represent the sagittal image curvature at wavelengths of 615nm, 540nm and 455nm. Fig.11 The right side of is the distortion curve (Distortion), which indicates the distortion size corresponding to different image heights. Fig.11 It is not difficult to see that the astigmatism of the projection device 200 is less than 0.1 mil, and the optical distortion is less than 1%. Therefore, the distortion degree of the image projected by the projection device 200 provided in the second example is relatively small.

[0073] See also Fig.12 , Fig.12 The magnification chromatic aberration curve of the projection device 200 provided in the second example of the present application is shown. The reference wavelength is 540nm, and the magnification chromatic aberration curve represents the magnitude of the magnification chromatic aberration corresponding to different image heights. Fig.13 , Fig.13 The axial chromatic aberration curve diagram of the projection device 200 provided in the second example of the present application is shown. Fig.13 The three curves in the figure correspond to wavelengths of 615nm, 540nm and 455nm respectively. The axial chromatic aberration curve indicates the size of the chromatic aberration corresponding to different apertures in the central field of view. Fig.12 and Fig.13 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.

[0074] See also Fig.14 , Fig.14 The relative illumination curve of the projection device 200 provided in the second example of the present application is shown. The wavelength is 540nm, and the relative illumination curve represents the relative illumination (Relative illumination) corresponding to different image heights. Fig.14 It is not difficult to see that the illumination at the edge of the field of view is higher, so the illumination distribution of the image projected by the projection device 200 is more uniform.

[0075] See also Fig.15 , Fig.15 The 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.15It 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 improving the matching degree between the lens and the image source 60 (ie, the projection chip).

[0076] It is not difficult to see here that, compared with the projection device 200 provided in the first example, the projection device 200 provided in the second example has a different arrangement order of the aspherical lenses, and the corresponding on-axis chromatic aberration curves, CRA curves, and astigmatism and distortion curves of the two projection devices 200 are substantially the same, indicating that the imaging performance of the two projection devices 200 is equivalent. The TTL value of the projection device 200 in the second example is 0.6 mm smaller than the TTL value of the projection device 200 in the first example, 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.

[0077] 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, and a fifth lens 50 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, and the image side surface S4 of the second lens 20 is a concave surface. The third lens 30 has negative optical power, the object side surface S5 of the third lens 30 is a concave surface, and the image side surface S6 of the third lens 30 is a convex surface. The fourth lens 40 has positive 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 convex surface. The fifth lens 50 has positive optical power, the object side surface S9 of the fifth lens 50 is a convex surface, and the image side surface S10 of the fifth lens 50 is a convex surface.

[0078] This embodiment provides a projection lens 100 including five 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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 and a fifth 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, and the image side surface of the second lens is a concave surface; The third lens has negative optical power, the object side surface of the third lens is concave, and the image side surface of the third lens is convex; The fourth lens has positive refractive power, the object side surface of the fourth lens is concave, and the image side surface of the fourth lens is convex; The fifth lens has positive refractive power, the object side surface of the fifth lens is a convex surface, and the image side surface of the fifth 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: 30° <FOV<35°。 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 fourth lens is f4, and f1 and f4 satisfy the relationship: 0.8 <f4 / f1<1.1。 4. The projection lens according to claim 1, characterized in that: The center thickness of the first lens is CT1, the edge thickness of the first lens is ET1, and the CT1 and the ET1 satisfy the relationship: 1.2 <CT1 / ET1<1.4。 5. The projection lens according to claim 1, wherein: The curvature radius of the object side surface of the fifth lens is R9, the curvature radius of the image side surface of the fifth lens is R10, the effective focal length of the fifth lens is f5, and R9, R10 and f5 satisfy the relationship: 3.2<(R9-R10) / f5<3.

7.

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: -1.1 <f2 / f<0。 7. The projection lens according to claim 1, wherein: The center thickness of the fourth lens is CT4, the edge thickness of the fourth lens is ET4, and the CT4 and the ET4 satisfy the relationship: 2.0 <CT4 / ET4<2.8。 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 and the fifth lens include an aspherical lens.

9. The projection lens according to claim 8, characterized in that: The fourth lens is an aspherical lens, and the first lens, the second lens, the third lens and the fifth lens are spherical lenses.

10. The projection lens according to claim 8, characterized in that: The third lens is an aspherical lens, and the first lens, the second lens, the fourth lens and the fifth lens are spherical lenses.

11. A projection device, characterized in that: A projection lens and an image source as claimed in any one of claims 1 to 10; The image source is used to generate a projection image; The projection lens is used to project the projection image.

12. The projection device according to claim 11, characterized in that: The main light angle of the image source is CRA, and the CRA satisfies the relationship: -1° <CRA<1°。 13. The projection device according to claim 11, characterized in that: The distance between the object side of the first lens and the image source is TTL, and half of the diagonal length of the light emitting area of ​​the image source is IMH. The TTL and the IMH satisfy the relationship: 6.0 <TTL / IMH<7.7。 14. The projection device according to claim 11, characterized in that: The distance between the object side of the first lens and the image source is TTL, the distance between the image side of the fifth lens and the image source is BFL, and the TTL and the BFL satisfy the relationship: 0.4 <BFL / TTL<0.5。 15. The projection device according to claim 11, characterized in that: The entrance pupil diameter of the projection lens is EPD, and half of the diagonal length of the light-emitting area of ​​the image source is IMH. The EPD and the IMH satisfy the relationship: 1.1 <EPD / IMH<1.34。

Images