CN114326035A

CN114326035A - Projection lens

Info

Publication number: CN114326035A
Application number: CN202210034266.2A
Authority: CN
Inventors: 周兴; 关健; 徐松; 赵晋
Original assignee: Meta Bounds Inc
Current assignee: Meta Bounds Inc
Priority date: 2022-01-12
Filing date: 2022-01-12
Publication date: 2022-04-12

Abstract

The invention discloses a projection lens, which sequentially comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens from an object side to an image side along an optical axis, wherein the first lens has positive focal power; the second lens has negative focal power; the third lens has positive focal power; the fourth lens has positive focal power; the fifth lens has negative focal power; the effective focal length of the projection lens is EFL, the distance of the projection lens on an optical axis along the direction from the object side to the image side is TTL, and the requirements are as follows:

the projection lens disclosed by the application designs the lens with a large view field, a large light transmission aperture, a small volume and high image quality by matching five lenses, and is favorable for improving the near-to-eye display effect of projection equipment.

Description

Projection lens

Technical Field

The invention relates to the technical field of optical lenses, in particular to a projection lens.

Background

At present, with the continuous progress of science and technology, interactive devices such as Augmented Reality (Augmented Reality) are gradually rising, and the application range of the projection lens is also wider and wider. The AR equipment projects the virtual display image to human eyes through the near-eye display device, so that the user receives information of the real world and the virtual world at the same time, and the super-sensory visual experience is obtained; the conventional projection schemes include a projection scheme based On an active Light Emitting Display source of a Liquid Crystal Display (LCD) screen and an Organic Light-Emitting Diode (OLED) screen, and a projection scheme based On a passive Light Emitting Display source of a Liquid Crystal On Silicon (LCOS) screen and a Digital Light Processing (DLP) screen, which are generally large in size, heavy in weight, and not comfortable for a user to wear for a long time. Therefore, the Micro LED screen is taken as a novel high-brightness miniaturized light-emitting display source device, the light-weight and portable comfortable wearing experience is easier to realize by the projection scheme taking the Micro LED screen as a light-emitting display source, and the Micro LED screen is more favored by users.

However, the projection lens on the market still cannot meet the requirements of large field of view and light weight, so that the combination scheme with the Micro LED screen is difficult to balance between large field of view angle and high image quality, small volume, low cost and high brightness, and the defect of insufficient near-eye display effect of the AR projection device is generated.

Accordingly, the prior art is yet to be improved and developed.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a projection lens, which is intended to solve the problem of poor near-eye display effect of the current AR projection apparatus.

The technical scheme of the invention is as follows:

a projection lens comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens from an object side to an image side along an optical axis in sequence, wherein the first lens has positive focal power; the second lens has negative focal power; the third lens has positive focal power; the fourth lens has positive focal power; the fifth lens has negative focal power; the effective focal length of the projection lens is EFL, and the projection lens is along the objectThe distance on the optical axis from the side to the image side is TTL, and the following requirements are met:

the projection lens further comprises a diaphragm arranged on an optical axis, and the diaphragm is positioned on one side of the first lens, which is far away from the second lens; moreover, the diameter of the light through hole of the diaphragm is EPD, and the projection lens meets the following requirements:

the projection lens, wherein the refractive index of the first lens is n₁And satisfies the following conditions: n is more than or equal to 1.8₁≤2.0。

The projection lens further comprises an image source surface arranged on an optical axis, and the image source surface is positioned on one side of the fifth lens, which is far away from the fourth lens; and, the projection lens satisfies: TTL/(I) of 2.7 or less_mgh2) is less than or equal to 3.65; wherein, I_mghIs one half of the diagonal length within the effective projection area of the image source surface.

The projection lens, wherein the projection lens satisfies: h is not more than 12 degrees_FOVLess than or equal to 18 degrees; wherein H_FOVIs half of the angle of view of the projection lens along the diagonal direction.

The projection lens, wherein the projection lens satisfies: 0.14 ≤ (CT)₂₃+CT₃₄) TTL is less than or equal to 0.26; wherein, CT₂₃Is the distance between the center point of the surface of the second lens facing the image side and the center point of the surface of the third lens facing the object side, CT₃₄The distance between the center point of the surface of the third lens facing the image side and the center point of the surface of the fourth lens facing the object side is included.

The projection lens, wherein the projection lens satisfies: f1/EFL is more than or equal to 0.7 and less than or equal to 1.2; and/or-2. ltoreq. f 2/EFL. ltoreq. 1; and/or-0.95 is less than or equal to f5/EFL is less than or equal to-0.4; wherein f1, f2, f5 are the effective focal lengths of the first lens, the second lens and the fifth lens, respectively.

The projection lens, wherein the projection lens satisfies:

wherein, c₁₁Is the radius of curvature of the object-side surface of the first lens, c₁₂Is the curvature radius of the surface of the first lens facing the image side.

The projection lens, wherein the projection lens satisfies:

wherein, c₄₁Is the radius of curvature of the surface of the fourth lens facing the object side, c₄₂Is the curvature radius of the surface of the fourth lens facing the image side.

The projection lens, wherein the projection lens satisfies: VD₂≤30；VD₅Less than or equal to 30; wherein, VD₂Is the Abbe number of the first lens, VD₅Is the abbe number of the fifth lens.

Compared with the prior art, the embodiment of the invention has the following advantages:

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a lens arrangement of a projection lens according to the present invention;

FIG. 2 is a schematic diagram of an optical path of a projection lens according to the present invention;

FIG. 3 is a parameter diagram of a projection lens according to the present invention;

FIG. 4 is a diagram of the modulation transfer function of the projection lens according to the present invention;

FIG. 5(a) is a field curvature diagram of a projection lens according to the present invention;

FIG. 5(b) is a distortion diagram of a projection lens according to the present invention;

FIG. 6 is a diagram of axial chromatic aberration of a projection lens according to the present invention;

FIG. 7 is a vertical axis chromatic aberration diagram of the projection lens of the present invention.

10, a first lens; 20. a second lens; 30. a third lens; 40. a fourth lens; 50. a fifth lens; 60. a diaphragm; 70. an image source side.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, in an embodiment of the present application, a projection lens is disclosed, wherein the projection lens includes, in order from an object side to an image side along an optical axis, a first lens element 10, a second lens element 20, a third lens element 30, a fourth lens element 40 and a fifth lens element 50, the first lens element 10 has a positive refractive power; the second lens 20 having a negative focal power; the third lens 30 having a positive refractive power; the fourth lens 40 has positive focal power; the fifth lens 50 having a negative focal power; the effective focal length of the projection lens is EFL, the distance of the projection lens on an optical axis along the direction from the object side to the image side is TTL, and the requirements are as follows:

the utility model discloses projection lens note projection light is called the optical axis from image source central point to diaphragm central point light propagation path, and the light path in the concrete projection lens is shown as figure 2, through five kinds of lens of collocation in proper order on the optical axis, has designed the projection lens that has big visual field, big clear aperture, small volume, high image quality, is favorable to promoting projection equipment's near-to-eye display effect.

Specifically, as an implementation manner of this embodiment, it is disclosed that the projection lens further includes a diaphragm 60 disposed on an optical axis, where the diaphragm 60 is located on a side of the first lens 10 away from the second lens 20; moreover, the diameter of the light-passing hole of the diaphragm 60 is EPD, and the projection lens satisfies:

specifically, as another embodiment of this embodiment, it is disclosed that the refractive index of the first lens 10 is n₁And satisfies the following conditions: n is more than or equal to 1.8₁Less than or equal to 2.0. In this embodiment, the first lens element 10 has positive refractive power, and can effectively reduce the length of the projection lens, and both the surface facing the object side and the surface facing the image side are convex.

Specifically, as another embodiment of this embodiment, it is disclosed that the surface of the second lens element 20 facing the object side and the image side is concave; the surface of the third lens element 30 facing the object side and the image side is concave; the surface of the fourth lens element 40 facing the object side is convex, and the surface facing the image side is concave; the surface of the fifth lens element 50 facing the object side and the image side is concave; the distance between the first lens 10 and the fifth lens 50 is adjusted through arrangement of the first lens and the fifth lens, so that the focal length of the projection lens can be adjusted, clear projection is met, meanwhile, the total length of light transmission in the projection lens is reduced, and the purposes of light weight and large field of view are achieved; meanwhile, the cost is saved, and the space is saved.

Specifically, as another implementation manner of this embodiment, it is disclosed that the projection lens further includes an image source surface 70 disposed on the optical axis, where the image source surface 70 is located on a side of the fifth lens element 50 away from the fourth lens element 40; and, define I_mghIs one-half of the diagonal length within the effective projection area of the image source surface 70; the projection lens satisfies: TTL/(I) of 2.7 or less_mgh*2)≤3.65。

Specifically, as another embodiment of this embodiment, it is disclosed that the projection lens satisfies: h is not more than 12 degrees_FOVLess than or equal to 18 degrees; wherein H_FOVIs half of the angle of view of the projection lens along the diagonal direction.

Specifically, as another embodiment of this embodiment, it is disclosed that the projection lens satisfies: 0.14 ≤ (CT)₂₃+CT₃₄) TTL is less than or equal to 0.26; wherein, CT₂₃Is the distance between the center point of the surface of the second lens 20 facing the image side and the center point of the surface of the third lens 30 facing the object side, CT₃₄The distance between the center point of the surface of the third lens 30 facing the image side and the center point of the surface of the fourth lens 40 facing the object side is included.

Specifically, in actual manufacturing, to meet the imaging requirements of a projection lens for high image quality and a large viewing angle, the above three conditions need to be met: TTL/(I) of 2.7 or less_mgh*2)≤3.65；12°≤H_FOV≤18°；0.14≤(CT₂₃+CT₃₄) At least one of/TTL ≦ 0.26.

Specifically, as another embodiment of this embodiment, it is disclosed that the projection lens satisfies: f1/EFL is more than or equal to 0.7 and less than or equal to 1.2; and/or-2. ltoreq. f 2/EFL. ltoreq. 1; and/or-0.95 is less than or equal to f5/EFL is less than or equal to-0.4; wherein f1, f2, f5 are the effective focal lengths of the first lens 10, the second lens 20, and the fifth lens 50, respectively.

Specifically, as another embodiment of this embodiment, it is disclosed that the projection lens satisfies:

wherein, c₁₁Is the radius of curvature of the object-side surface of the first lens 10, c₁₂Is the radius of curvature of the surface of the first lens element 10 facing the image side.

Specifically, as another embodiment of the present embodiment, the disclosureThe projection lens meets the following requirements:

wherein, c₄₁Is the radius of curvature of the surface of the fourth lens 40 facing the object side, c₄₂Is the radius of curvature of the image-side facing surface of the fourth lens element 40.

Specifically, as another embodiment of this embodiment, it is disclosed that the projection lens satisfies: VD₂≤30；VD₅Less than or equal to 30; wherein, VD₂Is the Abbe number, VD, of the first lens 10₅Is the abbe number of the fifth lens 50.

Specifically, as another implementation manner of the present embodiment, a projection lens is disclosed, where table 1 shows parameters of the projection lens of the present embodiment.

TABLE 1

Full field angle	32°
		F number	1.45
I_mgh	1.655mm
		TTL	11.679mm
H_FOV	16°

Optical performance parameters of the respective lens surfaces in the projection lens are shown in fig. 3; in addition, it can be seen from FIG. 4 that the projection lens of this embodiment has a modulation transfer function value of 0.31 to 1.0 for light with a wavelength ranging from 0.496 microns to 0.5876 microns and a spatial frequency ranging from 0lp/m to 300 lp/m. As can be seen from fig. 5(a), the field curvature of the projection lens of this embodiment, for a light ray with a wavelength of 0.528 μm, and the field curvature in the Tangential (tagential) direction and the Sagittal (Sagittal) direction is between-10 mm and 10 mm. As shown in FIG. 5(b), the distortion of the projection lens of this embodiment to the light with a wavelength of 0.528 μm is between-0.95% and 0%. As can be seen from fig. 6, the axial color difference value of the projection lens of this embodiment for the light with the wavelength of 0.573 microns, 0.528 microns, 0.514 microns, 0.496 microns and 0.5876 microns is between-1 micron and 4.5 microns. As can be seen from fig. 7, the projection lens of this embodiment generates a vertical axis color difference value between-1 micron and 2 microns for different heights of the field of view for the light with wavelengths of 0.573 microns, 0.528 microns, 0.514 microns, 0.496 microns and 0.5876 microns. Obviously, the field curvature, distortion, axial chromatic aberration and vertical axis chromatic aberration of the projection lens of the embodiment can be effectively corrected, and the resolution and the focal depth of the lens can meet the use requirements, so that better optical performance can be obtained. The projection lens disclosed by the embodiment can achieve the effects of large view field, large light transmission aperture, small volume and high image quality.

In summary, the present application discloses a projection lens, which includes, in order from an object side to an image side along an optical axis, a first lens element 10, a second lens element 20, a third lens element 30, a fourth lens element 40, and a fifth lens element 50, wherein the first lens element 10 has a positive refractive power; the second lens 20 having a negative focal power; the third lens 30 having a positive refractive power; the fourth lens 40 has positive focal power; the fifth lens 50 having a negative focal power; the effective focal length of the projection lens is EFL, the distance of the projection lens on an optical axis along the direction from the object side to the image side is TTL, and the requirements are as follows:

the projection lens disclosed by the application records the light from the object side to the image side of the projection lightThe line propagation path is called the optical axis. Through five kinds of lens of collocation in proper order on the optical axis, designed the camera lens that has big visual field, big clear aperture, small, high image quality, be favorable to promoting projection equipment's near-to-eye display effect.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

It should be noted that, the present invention takes the projection lens as an example to describe the specific structure and the operation principle of the present invention, but the application of the present invention is not limited to the projection lens, and the present invention can also be applied to the production and use of other similar workpieces.

It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A projection lens is characterized by comprising a first lens, a second lens, a third lens, a fourth lens and a fifth lens from an object side to an image side along an optical axis in sequence, wherein the first lens has positive focal power;

the second lens has negative focal power;

the third lens has positive focal power;

the fourth lens has positive focal power;

the fifth lens has negative focal power;

the effective focal length of the projection lens is EFL, the distance of the projection lens on an optical axis along the direction from the object side to the image side is TTL, and the requirements are as follows:

2. the projection lens of claim 1, further comprising a diaphragm disposed on an optical axis, the diaphragm being located on a side of the first lens facing away from the second lens; moreover, the diameter of the light through hole of the diaphragm is EPD, and the projection lens meets the following requirements:

3. the projection lens of claim 1 wherein the first lens has a refractive index n₁And satisfies the following conditions: n is more than or equal to 1.8₁≤2.0。

4. The projection lens of claim 1, further comprising an image source surface disposed on an optical axis, wherein the image source surface is located on a side of the fifth lens facing away from the fourth lens; and, the projection lens satisfies:

2.7≤TTL/(I_mgh*2)≤3.65；

wherein, I_mghIs one half of the diagonal length within the effective projection area of the image source surface.

5. The projection lens of claim 1, wherein the projection lens satisfies:

12°≤H_FOV≤18°；

wherein H_FOVIs half of the angle of view of the projection lens along the diagonal direction.

6. The projection lens of claim 1, wherein the projection lens satisfies:

0.14≤(CT₂₃+CT₃₄)/TTL≤0.26；

wherein, CT₂₃Between the center point of the surface of the second lens facing the image side and the center point of the surface of the third lens facing the object sideDistance, CT₃₄The distance between the center point of the surface of the third lens facing the image side and the center point of the surface of the fourth lens facing the object side is included.

7. The projection lens of claim 1, wherein the projection lens satisfies:

f1/EFL is more than or equal to 0.7 and less than or equal to 1.2; and/or the presence of a gas in the gas,

-2. ltoreq. f 2/EFL. ltoreq. 1; and/or the presence of a gas in the gas,

-0.95≤f5/EFL≤-0.4；

wherein f1, f2, f5 are the effective focal lengths of the first lens, the second lens and the fifth lens, respectively.

8. The projection lens of claim 1, wherein the projection lens satisfies:

9. The projection lens of claim 1, wherein the projection lens satisfies:

10. The projection lens of claim 1, wherein the projection lens satisfies:

VD₂≤30；

VD₅≤30；

wherein, VD₂Is the Abbe number of the first lens, VD₅Is the abbe number of the fifth lens.