CN114420020A

CN114420020A - Optical projection system, projection module and welcome lamp

Info

Publication number: CN114420020A
Application number: CN202111538729.0A
Authority: CN
Inventors: 张星煦; 孙毅; 涂陈; 马庆鸿; 杨剑锋
Original assignee: Huizhou Xingjuyu Intelligent Technology Co ltd
Current assignee: Huizhou Xingjuyu Intelligent Technology Co ltd
Priority date: 2021-12-15
Filing date: 2021-12-15
Publication date: 2022-04-29

Abstract

The application provides an optical projection system, a projection module and a welcome lamp. The above optical projection system, in order from the image side to the object side along the optical axis, comprises: a first lens having a negative optical power; the second lens with negative focal power, the object side surface of the second lens is a convex surface at the optical axis, and the image side surface of the second lens is a concave surface at the optical axis; a third lens having a positive optical power; the optical projection system satisfies the following relation: 0.9< | f2/f | <2.4, 0.23< Φ 11/TTL < 0.45. By limiting the shapes of the image side surface and the object side surface of the second lens, the optical total length of the optical projection system is effectively shortened according to the relation between the focal length of the second lens and the system focal length and the relation between the caliber of the image side surface of the first lens and the system total length, so that the optical projection system is miniaturized.

Description

Optical projection system, projection module and welcome lamp

Technical Field

The invention relates to the technical field of optical projection, in particular to an optical projection system, a projection module and a welcome lamp.

Background

The welcome lamp (also called as a floor lamp) is used for auxiliary lighting and can be used for floor lighting or lighting of a traveling route under low ambient light. For example, a courtesy light used in an automobile is usually installed at a door or a rear view mirror, and when the door is opened, an illumination function is turned on to project an image on the ground, so that not only are unique and dazzling image light and projected image generated, but also a function of illuminating the ground can be provided when the door is opened under low ambient light at night, so that people getting on or off the automobile can notice the ground condition without mistakenly stepping on dirt, puddles or other dangerous terrains on the ground. The traditional greeting lamp comprises two parts, wherein one part is an illuminating part and used for focusing light rays of a light source, and the other part is a projection part and used for transmitting the light rays focused by the illuminating part.

However, the projection part of the traditional welcome lamp is mainly, and the number of lenses of the projection part is large, so that the length of the welcome lamp is long, the size of the welcome lamp is too large, and the welcome lamp is not convenient to disassemble, assemble and maintain.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides an optical projection system, a projection module and a welcome lamp which are effectively reduced in length.

The purpose of the invention is realized by the following technical scheme:

an optical projection system comprising, in order from an image side to an object side along an optical axis: a first lens having a negative optical power; the second lens with negative focal power, the object side surface of the second lens is a convex surface at the optical axis, and the image side surface of the second lens is a concave surface at the optical axis; a third lens having a positive optical power; the optical projection system satisfies the following relation: 0.9< | f2/f | <2.4, 0.23< Φ 11/TTL < 0.45; wherein f2 is a focal length of the second lens element, f is a focal length of the optical projection system, Φ 11 is a caliber of an image side surface of the first lens element, and TTL is a total length of the optical projection system.

In one embodiment, the optical projection system further satisfies the following relationship: TTL is more than 8mm and less than 12.1 mm.

In one embodiment, the optical projection system satisfies the following relationship: IH/TTL is more than 0.17 and less than 0.22; wherein IH is the maximum image height of the projection image of the optical projection system.

In one embodiment, the optical projection system satisfies the following relationship: CTmax-CTmin is more than 0.55 and less than 1.8; where CTmax is the maximum thickness of the lens of each lens, and CTmin is the minimum thickness of the lens of each lens.

In one embodiment, the optical projection system satisfies the following relationship: -3.8 < f1-f < -1.4; wherein f1 is the focal length of the first lens.

In one embodiment, the optical projection system satisfies the following relationship: -31 < f3-f2 < -4.5; wherein f3 is the focal length of the third lens.

In one embodiment, each lens is made of plastic.

A projection module comprising a stop and the optical projection system of any of the above embodiments, wherein the photosensitive element is located on an image side of the first lens element.

A welcome lamp comprises an illumination assembly, a lamp shell and the projection module, wherein the projection module is located in the lamp shell, the illumination assembly and the projection module are located on the same optical axis, and the illumination assembly is located on the object side of a third lens.

In one embodiment, the illumination assembly includes a fourth lens element and a fifth lens element, which are sequentially disposed from an image side to an object side along an optical axis, wherein an object-side surface of the fourth lens element is a plane, an image-side surface of the fourth lens element is a convex surface, an object-side surface of the fifth lens element is a plane, and an image-side surface of the fifth lens element is a convex surface.

Compared with the prior art, the invention has at least the following advantages:

the shape of the image side surface and the shape of the object side surface of the second lens are limited, namely, the object side surface of the second lens is a convex surface at the optical axis, the image side surface of the second lens is a concave surface at the optical axis, and the total optical length of the optical projection system is effectively controlled according to the relation between the focal length of the second lens and the focal length of the system, namely, the length of the optical projection system can be reduced when the projection imaging quality is ensured, and the total optical length of the optical projection system is effectively shortened according to the relation between the aperture of the image side surface of the first lens and the total system length, so that the miniaturization of the optical projection system is realized.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a schematic view of an optical projection system according to embodiment 1 of the present application;

fig. 2A to 2F are an astigmatism curve, a distortion curve, a grid distortion graph, an MTF graph, a relative illuminance graph and a projection image of the optical projection system of embodiment 1, respectively;

FIG. 3 is a schematic view of an optical projection system according to embodiment 2 of the present application;

fig. 4A to 4F are an astigmatism curve, a distortion curve, a grid distortion graph, an MTF graph, a relative illuminance graph and a projection image of the optical projection system of embodiment 2, respectively;

FIG. 5 is a schematic view of an optical projection system according to embodiment 3 of the present application;

fig. 6A to 6E are an astigmatism curve, a distortion curve, a grid distortion graph, an MTF graph and a relative illuminance graph of the optical projection system of embodiment 3, respectively;

FIG. 7 is a schematic view of an optical projection system according to embodiment 4 of the present application;

fig. 8A to 8E are an astigmatism curve, a distortion curve, a grid distortion curve, an MTF curve and a relative illuminance chart of the optical projection system of embodiment 4, respectively;

FIG. 9 is a schematic view of an optical projection system according to embodiment 5 of the present application;

fig. 10A to 10E are an astigmatism curve, a distortion curve, a grid distortion graph, an MTF graph and a relative illuminance graph of the optical projection system of embodiment 5, respectively;

FIG. 11 is a schematic view of an optical projection system according to embodiment 6 of the present application;

fig. 12A to 12F are an astigmatism curve, a distortion curve, a grid distortion graph, an MTF graph, a relative illuminance graph and a projection image of the optical projection system of embodiment 6, respectively.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only and do not represent the only embodiments.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In this specification, a space on a side of the optical element where the object is located is referred to as an object side of the optical element, and correspondingly, a space on a side of the optical element where the object is located is referred to as an image side of the optical element. The surface of each lens closest to the object is called the object side surface, and the surface of each lens closest to the image plane is called the image side surface. And defines the positive direction with distance from the object side to the image side.

In addition, in the following description, if it appears that a lens surface is convex and the convex position is not defined, it means that the lens surface is convex at least near the optical axis; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least at the position near the optical axis. Here, the paraxial region means a region near the optical axis.

The features, principles and other aspects of the present application are described in detail below.

Please refer to fig. 1, which is a schematic structural diagram of an optical projection system according to an embodiment of the present disclosure, the optical projection system includes three lenses, namely, a first lens, a second lens and a third lens, which are sequentially disposed along an optical axis from an object side to an image side.

The object side surface of the second lens is a convex surface at the optical axis, the image side surface of the second lens is a concave surface at the optical axis, and the total optical length of the optical projection system is effectively controlled according to the relationship between the focal length of the second lens and the focal length of the system, namely the length of the optical projection system can be reduced while the projection imaging quality is ensured, and the total optical length of the optical projection system is effectively shortened according to the relationship between the aperture of the image side surface of the first lens and the total system length, so that the miniaturization of the optical projection system is realized.

In this embodiment, the optical projection system satisfies the following relation: 0.9< | f2/f | <2.4, 0.23< Φ 11/TTL < 0.45; wherein f2 is a focal length of the second lens element, f is a focal length of the optical projection system, Φ 11 is a caliber of an image side surface of the first lens element, and TTL is a total length of the optical projection system. | f2/f | may be 0.958, 1.187, 1.268, 1.578, 1.588 or 2.334, and Φ 11/TTL may be 0.24, 0.25, 0.31, 0.33, 0.37 or 0.42. The shape of the image side surface and the shape of the object side surface of the second lens are limited, namely, the object side surface of the second lens is a convex surface at the optical axis, the image side surface of the second lens is a concave surface at the optical axis, and the total optical length of the optical projection system is effectively controlled according to the relation between the focal length of the second lens and the focal length of the system, namely, the length of the optical projection system can be reduced when the projection imaging quality is ensured, and the total optical length of the optical projection system is effectively shortened according to the relation between the aperture of the image side surface of the first lens and the total system length, so that the miniaturization of the optical projection system is realized.

In one embodiment, the optical projection system further satisfies the following relationship: TTL is more than 8mm and less than 12.1 mm. In this embodiment, since the image side surface of the first lens is used as the final transmission surface of the optical projection system, that is, after the optical refraction of the third lens and the second lens is processed, the light will be projected from the image side surface of the first lens, and by adjusting the aperture of the image side surface of the first lens, the light-emitting range of the image side surface of the first lens is conveniently adjusted, so as to ensure the projection imaging quality of the optical projection system, and conveniently control the total length of the optical projection system within a specified length range, that is, the total length of the optical projection system is controlled within a range from 8mm to 12.1mm, so as to facilitate the miniaturization of the optical projection system.

In one embodiment, the optical projection system satisfies the following relationship: IH/TTL is more than 0.17 and less than 0.22; wherein IH is the maximum image height of the projection image of the optical projection system. In this embodiment, the IH/TTL can be 0.178, 0.189, 0.190, 0.194, 0.212, or 0.216. The object side surface of the second lens is a convex surface at the optical axis, the image side surface of the second lens is a concave surface at the optical axis, and the total optical length of the optical projection system is effectively controlled according to the relationship between the focal length of the second lens and the focal length of the system, namely the length of the optical projection system can be reduced while the projection imaging quality is ensured, and the total optical length of the optical projection system is effectively shortened according to the relationship between the aperture of the image side surface of the first lens and the total system length, so that the miniaturization of the optical projection system is realized. The maximum height of the projected image of the optical projection system is adjusted, and the optical total length of the optical projection system can be effectively controlled by adjusting the ratio of the maximum image height of the optical projection system to the total length of the optical projection system, namely, the ratio of the maximum image height to the total length is controlled within a specified range, so that the total length of a lens is effectively shortened while the imaging quality of the optical projection system is ensured, and the miniaturization of the optical projection system is further facilitated.

In one embodiment, the optical projection system satisfies the following relationship: CTmax-CTmin is more than 0.55 and less than 1.8; where CTmax is the maximum thickness of the lens of each lens, and CTmin is the minimum thickness of the lens of each lens. In this embodiment, CTmax-CTmin may be 0.550, 0.569, 0.704, 0.782, 0.788, or 1.799. The object side surface of the second lens is a convex surface at the optical axis, the image side surface of the second lens is a concave surface at the optical axis, and the total optical length of the optical projection system is effectively controlled according to the relationship between the focal length of the second lens and the focal length of the system, namely the length of the optical projection system can be reduced while the projection imaging quality is ensured, and the total optical length of the optical projection system is effectively shortened according to the relationship between the aperture of the image side surface of the first lens and the total system length, so that the miniaturization of the optical projection system is realized. The optical projection system has the advantages that the mode of calculating the difference value between the maximum thickness and the minimum thickness of each lens is realized by comparing the difference value of the thicknesses of the lenses of each lens, so that the space range of each lens is conveniently controlled, the length of the optical projection system is conveniently controlled, the whole mechanical structure of the optical projection system is more uniform, the reliability risk caused by the uneven thickness of the lenses is reduced, the total length of the optical projection system can be further reduced when the quality of projection imaging is ensured, and the miniaturization of the optical projection system is further facilitated.

In one embodiment, the optical projection system satisfies the following relationship: -3.8 < f1-f < -1.4; wherein f1 is the focal length of the first lens. In this embodiment, f1-f can be-3.734, -2.890, -2.010, -1.972, -1.588, or-1.442. The object side surface of the second lens is a convex surface at the optical axis, the image side surface of the second lens is a concave surface at the optical axis, and the total optical length of the optical projection system is effectively controlled according to the relationship between the focal length of the second lens and the focal length of the system, namely the length of the optical projection system can be reduced while the projection imaging quality is ensured, and the total optical length of the optical projection system is effectively shortened according to the relationship between the aperture of the image side surface of the first lens and the total system length, so that the miniaturization of the optical projection system is realized. The difference between the focal length of the first lens and the total focal length is determined by controlling the focal length of the first lens and the total focal length of the optical projection system, so that the deviation condition between the focal length of the first lens and the total focal length is conveniently determined, the focal length of the first lens can ensure the quality of projection imaging, and the first lens is used as the last lens for projection imaging after all. After the difference relation between the focal length of the first lens and the total focal length is adjusted, the total length of the optical projection system is controlled by reducing the difference between the first lens and the total focal length, and the miniaturization of the optical projection system is further facilitated.

In one embodiment, the optical projection system satisfies the following relationship: -31 < f3-f2 < -4.5; wherein f3 is the focal length of the third lens. In this embodiment, f3-f2 can be-30.799, -24.867, -19.948, -15.310, -6.168, or-4.822. The object side surface of the second lens is a convex surface at the optical axis, the image side surface of the second lens is a concave surface at the optical axis, and the total optical length of the optical projection system is effectively controlled according to the relationship between the focal length of the second lens and the focal length of the system, namely the length of the optical projection system can be reduced while the projection imaging quality is ensured, and the total optical length of the optical projection system is effectively shortened according to the relationship between the aperture of the image side surface of the first lens and the total system length, so that the miniaturization of the optical projection system is realized. And the distance between the second lens and the third lens is convenient to adjust by improving the focal length difference between the second lens and the third lens, so that the transmission angle of light is effectively controlled, the trend of the light is changed and optimized, and the resolving power and the chromatic aberration control capability of the optical projection system are effectively improved.

In another embodiment, the lenses are made of plastic, so that the problems of high processing difficulty, high cost, high distortion and heavy weight caused by the glass lenses are avoided, the total length of the optical projection system is effectively shortened, the overall volume of the optical projection system is reduced, and the miniaturization of the optical projection system is further facilitated.

Specific examples of the optical projection system that can be applied to the above-described embodiments are further described below with reference to the drawings.

Example 1

An optical projection system of embodiment 1 of the present application is described below with reference to fig. 1 to 2F.

Fig. 1 shows a schematic configuration diagram of an optical projection system of embodiment 1. As shown in fig. 1, the optical projection system includes, in order from an image side to an object side along an optical axis, a stop STO, a first lens element L1, a second lens element L2 and a third lens element L3, the stop being located on the image side of the first lens element.

The first lens element L1 has negative power, and both the image-side surface S1 and the object-side surface S2 are aspheric, and the image-side surface S1 of the first lens element L1 is convex at the optical axis and convex at the circumference, and the object-side surface S2 of the first lens element L1 is convex at the optical axis and convex at the circumference;

the second lens element L2 has negative power, and both the image-side surface S3 and the object-side surface S4 are aspheric, and the image-side surface S3 of the second lens element L2 is concave at the optical axis and convex at the circumference, and the object-side surface S4 of the second lens element L2 is convex at the optical axis and convex at the circumference;

the third lens element L3 has positive power, and both the image-side surface S5 and the object-side surface S6 are aspheric, and the image-side surface S5 of the third lens element L3 is convex at the optical axis and concave at the circumference, and the object-side surface S6 of the third lens element L3 is concave and convex at the circumference;

a stop STO is located on the image side of the first lens L1 to further improve the brightness of the image of the optical projection system and thus improve the imaging sharpness of the optical projection system.

Table 1 shows the surface type, radius of curvature, thickness, refractive index, and conic coefficient of each lens of the optical projection system of example 1, in which the total length, radius of curvature, and thickness of the optical projection system are all in units of millimeters (mm).

TABLE 1

As can be seen from table 1, in the present embodiment, the first lens L1 to the third lens L3 are all plastic aspheric lenses, and each aspheric surface type x is defined by the following formula:

wherein x is the rise of the distance from the aspheric surface vertex to the aspheric surface vertex when the aspheric surface is at the position with the height of h along the optical axis direction; c is the paraxial curvature of the aspheric surface, c being 1/R (i.e., paraxial curvature c is the inverse of radius of curvature R in table 1); k is a conic coefficient; ai is the ith order coefficient of the aspheric surface. Table 2 below gives the high-order term coefficients a4, a6, A8, a10, and a12 that can be used for the lens aspheres S1 through S6 in example 1.

TABLE 2

Flour mark	A4	A6	A8	A10	A12
						S1	-6.7358370E-04	-1.0972788E-03	-3.3863085E-04	-2.4175251E-04	5.4674112E-07
S2	-1.7691347E-03	-5.6913754E-03	-2.5186933E-03	-7.6674992E-04	5.2872316E-04
						S3	-7.4548928E-03	-5.6815393E-03	-3.3374164E-03	-1.9015417E-03	5.4831838E-04
S4	-4.8326658E-03	5.2294509E-03	-7.4146507E-04	2.0098882E-04	-3.1067586E-04
						S5	-1.9496813E-02	-4.3299972E-03	2.5235424E-03	-2.4421976E-04	-1.2520138E-04
S6	-2.8150134E-02	-2.2611956E-03	2.6565483E-03	-1.8417215E-03	3.0399723E-04

As can be seen from the data in tables 1 and 2, the optical projection system in example 1 satisfies:

1.268, wherein f2 is the focal length of the second lens, and f is the focal length of the optical projection system.

Φ 11/TTL is 0.335, where Φ 11 is the aperture of the image-side surface of the first lens, and TTL is the total length of the optical projection system.

And IH/TTL is 0.194, wherein IH is the maximum image height of a projection image of the optical projection system.

CTmax-CTmin of 1.799, where CTmax is the maximum thickness of the optic for each lens and CTmin is the minimum thickness of the optic for each lens.

f 1-f-1.588, wherein f1 is the focal length of the first lens.

f3-f2 is-30.799, wherein f3 is the focal length of the third lens.

Fig. 2A shows astigmatism curves of the optical projection system of embodiment 1, which represent meridional field curvature and sagittal field curvature; FIG. 2B shows a distortion curve for the optical projection system of example 1, which represents the percentage of distortion for different image heights; fig. 2C shows the mesh distortion of the optical projection system of embodiment 1; fig. 2D shows MTF curves for the optical projection system of embodiment 1, wherein the MTF curves for a plurality of half diagonal field angles, including 0 °, 3.63 °, 9.37 °, 12.30 °, and 15.64 °; fig. 2E shows the relative illuminance of the projection image of the optical projection system of embodiment 1. As can be seen from fig. 2A to 2E, by adjusting the relationship between the focal length of the second lens and the system focal length and the relationship between the aperture of the image-side surface of the first lens and the total system length, that is, by adjusting the values of If2/f | and Φ 11/TTL, the projection imaging sharpness is ensured even when the optical projection system is miniaturized. Wherein fig. 2F shows a specific projection imaging effect of the optical projection system of embodiment 1.

Example 2

An optical projection system of embodiment 2 of the present application is described below with reference to fig. 3 to 4F.

Fig. 3 shows a schematic configuration diagram of an optical projection system of embodiment 2. As shown in fig. 3, the optical projection system includes, in order from an image side to an object side along an optical axis, a stop STO, a first lens element L1, a second lens element L2 and a third lens element L3, the stop being located on the image side of the first lens element.

The first lens element L1 has negative power, and both the image-side surface S1 and the object-side surface S2 are aspheric, and the image-side surface S1 of the first lens element L1 is convex at the optical axis and convex at the circumference, and the object-side surface S2 of the first lens element L1 is convex at the optical axis and concave at the circumference;

Table 3 shows the surface type, radius of curvature, thickness, refractive index, and conic coefficient of each lens of the optical projection system of example 2, in which the total length, radius of curvature, and thickness of the optical projection system are all in units of millimeters (mm).

TABLE 3

As can be seen from table 3, in the present embodiment, the first lens L1 to the third lens L3 are all plastic aspheric lenses, and each aspheric surface type x is defined by the following formula:

wherein x is the rise of the distance from the aspheric surface vertex to the aspheric surface vertex when the aspheric surface is at the position with the height of h along the optical axis direction; c is the paraxial curvature of the aspheric surface, c being 1/R (i.e., paraxial curvature c is the inverse of radius of curvature R in table 3); k is a conic coefficient; ai is the ith order coefficient of the aspheric surface. Table 4 below gives the high-order term coefficients a4, a6, A8, a10, and a12 that can be used for the lens aspheres S1 through S6 in example 2.

TABLE 4

As can be seen from the data in tables 3 and 4, the optical projection system in example 2 satisfies:

and | f2/f | -0.958, wherein f2 is the focal length of the second lens and f is the focal length of the optical projection system.

Φ 11/TTL is 0.312, where Φ 11 is the aperture of the image-side surface of the first lens, and TTL is the total length of the optical projection system.

And IH/TTL is 0.216, wherein IH is the maximum image height of a projection image of the optical projection system.

CTmax-CTmin is 0.550, where CTmax is the maximum thickness of the optic of each lens and CTmin is the minimum thickness of the optic of each lens.

f 1-f-3.734, wherein f1 is the focal length of the first lens.

f3-f2 is-4.822, wherein f3 is the focal length of the third lens.

Fig. 4A shows astigmatism curves of the optical projection system of embodiment 2, which represent meridional field curvature and sagittal field curvature; FIG. 4B shows a distortion curve for the optical projection system of example 2, which represents the percentage of distortion for different image heights; fig. 4C shows the mesh distortion of the optical projection system of embodiment 2; fig. 4D shows MTF curves for the optical projection system of embodiment 2, wherein the MTF curves for a plurality of half diagonal field angles, including 0 °, 3.63 °, 9.37 °, 12.30 °, and 15.64 °; fig. 4E shows the relative illuminance of the projection image of the optical projection system of embodiment 2. As can be seen from fig. 4A to 4E, by adjusting the relationship between the focal length of the second lens and the system focal length and the relationship between the aperture of the image-side surface of the first lens and the total system length, that is, by adjusting the values of | f2/f | and Φ 11/TTL, the projection imaging sharpness is ensured even when the optical projection system is miniaturized. Wherein fig. 4F shows a specific projection imaging effect of the optical projection system of embodiment 2.

Example 3

An optical projection system of embodiment 3 of the present application is described below with reference to fig. 5 to 6E.

Fig. 5 shows a schematic configuration diagram of an optical projection system of embodiment 3. As shown in fig. 5, the optical projection system includes, in order from an image side to an object side along an optical axis, a stop STO, a first lens element L1, a second lens element L2 and a third lens element L3, the stop being located on the image side of the first lens element.

the second lens element L2 has negative power, and both the image-side surface S3 and the object-side surface S4 are aspheric, and the image-side surface S3 of the second lens element L2 is concave at the optical axis and convex at the circumference, and the object-side surface S4 of the second lens element L2 is convex at the optical axis and concave at the circumference;

the third lens element L3 has positive power, and both the image-side surface S5 and the object-side surface S6 are aspheric, and the image-side surface S5 of the third lens element L3 is convex at the optical axis and concave at the circumference, and the object-side surface S6 of the third lens element L3 is concave at the circumference and concave;

Table 5 shows the surface type, radius of curvature, thickness, refractive index, and conic coefficient of each lens of the optical projection system of example 3, in which the total length, radius of curvature, and thickness of the optical projection system are all in units of millimeters (mm).

TABLE 5

As can be seen from table 5, in the present embodiment, the first lens L1 to the third lens L3 all adopt plastic aspheric lenses, and each aspheric surface type x is defined by the following formula:

wherein x is the rise of the distance from the aspheric surface vertex to the aspheric surface vertex when the aspheric surface is at the position with the height of h along the optical axis direction; c is the paraxial curvature of the aspheric surface, c being 1/R (i.e., paraxial curvature c is the inverse of radius of curvature R in table 5); k is a conic coefficient; ai is the ith order coefficient of the aspheric surface. Table 6 below gives the high-order term coefficients a4, a6, A8, a10, and a12 that can be used for the lens aspheres S1 through S6 in example 3.

TABLE 6

Flour mark	A4	A6	A8	A10	A12
						S1	-2.1350705E-05	1.3291820E-04	-1.4365705E-04	-1.9675396E-05	9.0206303E-06
S2	6.1272604E-05	-1.5205138E-03	-8.6234500E-04	-8.4632336E-05	5.9940282E-05
						S3	-5.2620854E-03	-1.7875506E-03	-5.3891476E-04	-2.9639182E-04	8.3569159E-05
S4	-1.8317769E-04	4.5816620E-03	8.6301613E-05	-2.5793776E-06	-5.6843347E-05
						S5	-1.0139088E-02	2.8872082E-03	2.9497063E-04	2.9498635E-06	-5.3127320E-05
S6	-3.0754836E-02	3.8963495E-03	-6.7367440E-04	1.0498520E-04	-1.4739250E-05

As can be seen from the data in tables 5 and 6, the optical projection system in example 3 satisfies:

1.187, where f2 is the focal length of the second lens and f is the focal length of the optical projection system.

Φ 11/TTL is 0.373, where Φ 11 is the aperture of the image-side surface of the first lens, and TTL is the total length of the optical projection system.

And IH/TTL is 0.212, wherein IH is the maximum image height of a projection image of the optical projection system.

CTmax-CTmin is 0.569, where CTmax is the maximum thickness of the optic of each lens and CTmin is the minimum thickness of the optic of each lens.

f 1-f-2.890, wherein f1 is the focal length of the first lens.

f3-f2 is-6.168, wherein f3 is the focal length of the third lens.

Fig. 6A shows astigmatism curves of the optical projection system of embodiment 3, which represent meridional field curvature and sagittal field curvature; FIG. 6B shows a distortion curve for the optical projection system of example 3, which represents the percentage of distortion for different image heights; fig. 6C shows the mesh distortion of the optical projection system of embodiment 3; fig. 6D shows MTF curves for the optical projection system of embodiment 3, where the MTF curves for a plurality of half diagonal field angles, including 0 °, 3.63 °, 9.37 °, 12.30 °, and 15.64 °; fig. 6E shows the relative illuminance of the projection image of the optical projection system of embodiment 3. As can be seen from fig. 6A to 6E, by adjusting the relationship between the focal length of the second lens and the system focal length and the relationship between the aperture of the image-side surface of the first lens and the total system length, that is, by adjusting the values of | f2/f | and Φ 11/TTL, the projection imaging sharpness is ensured even when the optical projection system is miniaturized.

Example 4

An optical projection system of embodiment 4 of the present application is described below with reference to fig. 7 to 8E.

Fig. 7 shows a schematic configuration diagram of an optical projection system of embodiment 4. As shown in fig. 7, the optical projection system includes, in order from an image side to an object side along an optical axis, a stop STO, a first lens element L1, a second lens element L2 and a third lens element L3, the stop being located on the image side of the first lens element.

the second lens element L2 has negative power, and both the image-side surface S3 and the object-side surface S4 are aspheric, and the image-side surface S3 of the second lens element L2 is concave at the optical axis and concave at the circumference, and the object-side surface S4 of the second lens element L2 is convex at the optical axis and concave at the circumference;

Table 7 shows the surface type, radius of curvature, thickness, refractive index, and conic coefficient of each lens of the optical projection system of example 4, in which the total length, radius of curvature, and thickness of the optical projection system are all in units of millimeters (mm).

TABLE 7

As can be seen from table 7, in the present embodiment, the first lens L1 to the third lens L3 are all aspheric lenses, and each aspheric surface x is defined by the following formula:

wherein x is the rise of the distance from the aspheric surface vertex to the aspheric surface vertex when the aspheric surface is at the position with the height of h along the optical axis direction; c is the paraxial curvature of the aspheric surface, c being 1/R (i.e., paraxial curvature c is the inverse of radius of curvature R in table 7); k is a conic coefficient; ai is the ith order coefficient of the aspheric surface. Table 8 below gives the high-order term coefficients a4, a6, A8, a10, and a12 that can be used for the lens aspheres S1 through S6 in example 4.

TABLE 8

As can be seen from the data in table 7 and table 8, the optical word projection system in example 4 satisfies:

1.578, | f2/f |, where f2 is the focal length of the second lens and f is the focal length of the optical projection system.

Φ 11/TTL is 0.424, where Φ 11 is the aperture of the image-side surface of the first lens, and TTL is the total length of the optical projection system.

And IH/TTL is 0.189, wherein IH is the maximum image height of a projection image of the optical projection system.

CTmax-CTmin is 0.788, where CTmax is the maximum thickness of the optic for each lens and CTmin is the minimum thickness of the optic for each lens.

f 1-f-1.972, wherein f1 is the focal length of the first lens.

f3-f2 is-19.948, wherein f3 is the focal length of the third lens.

Fig. 8A shows astigmatism curves representing meridional field curvature and sagittal field curvature of the optical projection system of example 4; FIG. 8B shows a distortion curve for the optical projection system of example 4, which represents the percentage of distortion for different image heights; fig. 8C shows the mesh distortion of the optical projection system of embodiment 4; fig. 8D shows MTF curves for the optical projection system of embodiment 4, where the MTF curves for a plurality of half diagonal field angles, including 0 °, 3.63 °, 9.37 °, 12.30 °, and 15.64 °; fig. 8E shows the relative illuminance of the projection image of the optical projection system of embodiment 4. As can be seen from fig. 8A to 8E, by adjusting the relationship between the focal length of the second lens and the system focal length and the relationship between the aperture of the image-side surface of the first lens and the total system length, that is, by adjusting the values of | f2/f | and Φ 11/TTL, the projection imaging sharpness is ensured even when the optical projection system is miniaturized.

Example 5

An optical projection system of embodiment 5 of the present application is described below with reference to fig. 9 to 10E.

Fig. 9 shows a schematic configuration diagram of an optical projection system of embodiment 5. As shown in fig. 9, the optical projection system includes, in order from the image side to the object side along the optical axis, a stop STO, a first lens element L1, a second lens element L2 and a third lens element L3, the stop being located on the image side of the first lens element.

Table 9 shows the surface type, radius of curvature, thickness, refractive index, and conic coefficient of each lens of the optical projection system of example 5, in which the total length, radius of curvature, and thickness of the optical projection system are all in units of millimeters (mm).

TABLE 9

As can be seen from table 9, in the present embodiment, the first lens L1 to the third lens L3 are all plastic aspherical lenses, and each aspherical surface type x is defined by the following formula:

wherein x is the rise of the distance from the aspheric surface vertex to the aspheric surface vertex when the aspheric surface is at the position with the height of h along the optical axis direction; c is the paraxial curvature of the aspheric surface, c being 1/R (i.e., paraxial curvature c is the inverse of radius of curvature R in table 9); k is a conic coefficient; ai is the ith order coefficient of the aspheric surface. Table 10 below gives the high-order term coefficients a4, a6, A8, a10, and a12 that can be used for the lens aspheres S1 through S6 in example 5.

Watch 10

Flour mark	A4	A6	A8	A10	A12
						S1	6.3832830E-04	-5.4752790E-04	-1.5374371E-04	6.9456994E-05	1.3486421E-04
S2	-3.0195243E-03	4.0211729E-04	5.1215945E-04	1.0531002E-04	-2.9627428E-05
						S3	-2.6423980E-03	7.3223081E-04	2.0831885E-04	-3.2834712E-04	2.7580000E-05
S4	2.1513128E-04	2.8013662E-03	7.8758988E-05	-1.7320606E-04	-3.5004692E-05
						S5	-1.3226388E-02	1.2422028E-03	-9.9637752E-05	-1.5995283E-05	-7.7106613E-05
S6	-1.8816848E-02	2.5959318E-04	3.1498359E-07	-7.6436154E-05	-6.4590106E-06

As can be seen from the data in table 9 and table 10, the optical projection system in example 5 satisfies:

1.588, wherein f2 is the focal length of the second lens and f is the focal length of the optical projection system.

Φ 11/TTL is 0.249, where Φ 11 is an aperture of an image-side surface of the first lens, and TTL is a total length of the optical projection system.

And IH/TTL is 0.190, wherein IH is the maximum image height of a projection image of the optical projection system.

CTmax-CTmin is 0.782, where CTmax is the maximum thickness of the optic of each lens and CTmin is the minimum thickness of the optic of each lens.

f 1-f-2.010, wherein f1 is the focal length of the first lens.

f3-f2 is-15.310, wherein f3 is the focal length of the third lens.

Fig. 10A shows astigmatism curves representing meridional field curvature and sagittal field curvature of the optical projection system of example 5; FIG. 10B shows a distortion curve for the optical projection system of example 5, which represents the percentage of distortion for different image heights; FIG. 10C shows the distortion of the mesh of the optical projection system of example 5; fig. 10D shows MTF curves for the optical projection system of embodiment 5, wherein the MTF curves for a plurality of half diagonal field angles, including 0 °, 3.63 °, 9.37 °, 12.30 °, and 15.64 °; fig. 10E shows the relative illuminance of the projection image of the optical projection system of embodiment 5. As can be seen from fig. 10A to 10E, by adjusting the relationship between the focal length of the second lens and the system focal length and the relationship between the aperture of the image-side surface of the first lens and the total system length, that is, by adjusting the values of | f2/f | and Φ 11/TTL, the projection imaging sharpness is ensured even when the optical projection system is miniaturized.

Example 6

An optical projection system of embodiment 6 of the present application is described below with reference to fig. 11 to 12F.

Fig. 11 shows a schematic configuration diagram of an optical projection system of embodiment 6. As shown in fig. 11, the optical projection system includes, in order from an image side to an object side along an optical axis, a stop STO, a first lens element L1, a second lens element L2 and a third lens element L3, the stop being located on the image side of the first lens element.

The first lens element L1 has negative power, and both the image-side surface S1 and the object-side surface S2 are aspheric, and the image-side surface S1 of the first lens element L1 is convex at the optical axis and concave at the circumference, and the object-side surface S2 of the first lens element L1 is convex at the optical axis and convex at the circumference;

Table 11 shows the surface type, radius of curvature, thickness, refractive index, and conic coefficient of each lens of the optical projection system of example 6, in which the total length, radius of curvature, and thickness of the optical projection system are all in units of millimeters (mm).

TABLE 11

As can be seen from table 11, in the present embodiment, the first lens L1 to the third lens L3 all adopt plastic aspheric lenses, and each aspheric surface type x is defined by the following formula:

wherein x is the rise of the distance from the aspheric surface vertex to the aspheric surface vertex when the aspheric surface is at the position with the height of h along the optical axis direction; c is the paraxial curvature of the aspheric surface, c being 1/R (i.e., paraxial curvature c is the inverse of radius of curvature R in table 11); k is a conic coefficient; ai is the ith order coefficient of the aspheric surface. Table 12 below gives the high-order term coefficients a4, a6, A8, a10, and a12 that can be used for the lens aspheres S1 through S6 in example 6.

TABLE 12

Flour mark	A4	A6	A8	A10	A12
						S1	1.3957589E-03	-2.0778049E-03	-1.1285948E-03	3.9366903E-04	8.1881786E-04
S2	-2.8571476E-03	8.4173003E-04	-4.8293623E-04	-2.9142261E-04	1.8963005E-04
						S3	-1.4522838E-03	4.1351388E-04	7.3812347E-04	-2.0277131E-04	-9.3829888E-04
S4	-6.0833705E-04	2.5787525E-03	2.9587647E-06	-2.3047151E-04	-1.0787781E-04
						S5	-1.3540850E-02	8.9255118E-04	-3.2663452E-04	-1.3204933E-04	-1.1387187E-04
S6	-1.9718551E-02	4.4003776E-05	-8.2565953E-05	-1.1522620E-04	-2.6666208E-05

As can be seen from the data in tables 11 and 12, the optical word projection system in example 6 satisfies:

2.334, where f2 is the focal length of the second lens and f is the focal length of the optical projection system.

Φ 11/TTL is 0.236, where Φ 11 is the aperture of the image-side surface of the first lens, and TTL is the total length of the optical projection system.

And IH/TTL is 0.178, wherein IH is the maximum image height of a projection image of the optical projection system.

CTmax-CTmin is 0.704, where CTmax is the maximum thickness of the optic of each lens and CTmin is the minimum thickness of the optic of each lens.

f 1-f-1.442, wherein f1 is the focal length of the first lens.

f3-f2 is-24.867, wherein f3 is the focal length of the third lens.

Fig. 12A shows astigmatism curves representing meridional field curvature and sagittal field curvature of the optical projection system of example 6; FIG. 12B shows a distortion curve for the optical projection system of example 6, which represents the percentage of distortion for different image heights; FIG. 12C shows the distortion of the mesh of the optical projection system of example 6; fig. 12D shows MTF curves for the optical projection system of embodiment 6, wherein the MTF curves for a plurality of half diagonal field angles, including 0 °, 3.63 °, 9.37 °, 12.30 °, and 15.64 °; fig. 12E shows the relative illuminance of the projection image of the optical projection system of embodiment 6. As can be seen from fig. 12A to 12E, by adjusting the relationship between the focal length of the second lens and the system focal length and the relationship between the aperture of the image-side surface of the first lens and the total system length, that is, by adjusting the values of | f2/f | and Φ 11/TTL, the projection imaging sharpness is ensured even when the optical projection system is miniaturized. Wherein fig. 12F shows a specific projection imaging effect of the optical projection system of embodiment 6.

In one embodiment, the present application further provides a projection module, which includes a stop and the optical projection system of any of the above embodiments, wherein the photosensitive element is located on an image side of the first lens element. In this embodiment, the optical projection system includes, in order from an image side to an object side along an optical axis: a first lens having a negative optical power; the second lens with negative focal power, the object side surface of the second lens is a convex surface at the optical axis, and the image side surface of the second lens is a concave surface at the optical axis; a third lens having a positive optical power; the optical projection system satisfies the following relation: 0.9< | f2/f | <2.4, 0.23< dP11/TTL < 0.45; wherein f2 is a focal length of the second lens element, f is a focal length of the optical projection system, Φ 11 is a caliber of an image side surface of the first lens element, and TTL is a total length of the optical projection system. The shape of the image side surface and the shape of the object side surface of the second lens are limited, namely, the object side surface of the second lens is a convex surface at the optical axis, the image side surface of the second lens is a concave surface at the optical axis, and the total optical length of the optical projection system is effectively controlled according to the relation between the focal length of the second lens and the focal length of the system, namely, the length of the optical projection system can be reduced when the projection imaging quality is ensured, and the total optical length of the optical projection system is effectively shortened according to the relation between the aperture of the image side surface of the first lens and the total system length, so that the miniaturization of the optical projection system is realized.

In one embodiment, the present application further provides a welcome lamp, which includes an illumination assembly, a lamp housing and the projection module of the above embodiment, wherein the illumination assembly and the projection module are located in the lamp housing, the illumination assembly and the projection module are located on the same optical axis, and the illumination assembly is located on the object side of the third lens. In this embodiment, the optical projection system includes, in order from an image side to an object side along an optical axis: a first lens having a negative optical power; the second lens with negative focal power, the object side surface of the second lens is a convex surface at the optical axis, and the image side surface of the second lens is a concave surface at the optical axis; a third lens having a positive optical power; the optical projection system satisfies the following relation: 0.9< | f2/f | <2.4, 0.23< Φ 11/TTL < 0.45; wherein f2 is a focal length of the second lens element, f is a focal length of the optical projection system, Φ 11 is a caliber of an image side surface of the first lens element, and TTL is a total length of the optical projection system. The shape of the image side surface and the shape of the object side surface of the second lens are limited, namely, the object side surface of the second lens is a convex surface at the optical axis, the image side surface of the second lens is a concave surface at the optical axis, and the total optical length of the optical projection system is effectively controlled according to the relation between the focal length of the second lens and the focal length of the system, namely, the length of the optical projection system can be reduced when the projection imaging quality is ensured, and the total optical length of the optical projection system is effectively shortened according to the relation between the aperture of the image side surface of the first lens and the total system length, so that the miniaturization of the optical projection system is realized.

In one embodiment, the illumination assembly includes a fourth lens element and a fifth lens element, which are sequentially disposed from an image side to an object side along an optical axis, wherein an object-side surface of the fourth lens element is a plane, an image-side surface of the fourth lens element is a convex surface, an object-side surface of the fifth lens element is a plane, and an image-side surface of the fifth lens element is a convex surface. In this embodiment, the fourth lens and the fifth lens process the light emitted from the light source, so as to improve the uniformity and brightness of the light passing through the optical projection system.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. An optical projection system, comprising, in order from an image side to an object side along an optical axis:

a first lens having a negative optical power;

the second lens with negative focal power, the object side surface of the second lens is a convex surface at the optical axis, and the image side surface of the second lens is a concave surface at the optical axis;

a third lens having a positive optical power;

the optical projection system satisfies the following relation:

0.9<|f2/f|<2.4，0.23<Φ11/TTL<0.45；

wherein f2 is a focal length of the second lens element, f is a focal length of the optical projection system, Φ 11 is a caliber of an image side surface of the first lens element, and TTL is a total length of the optical projection system.

2. The optical projection system of claim 1, wherein the optical projection system further satisfies the following relationship:

8mm<TTL<12.1mm。

3. the optical projection system of claim 1, wherein the optical projection system satisfies the following relationship:

0.17<IH/TTL<0.22；

wherein IH is the maximum image height of the projection image of the optical projection system.

4. The optical projection system of claim 1, wherein the optical projection system satisfies the following relationship:

0.55<CTmax-CTmin<1.8；

where CTmax is the maximum thickness of the lens of each lens, and CTmin is the minimum thickness of the lens of each lens.

5. The optical projection system of claim 1, wherein the optical projection system satisfies the following relationship:

-3.8<f1-f<-1.4；

wherein f1 is the focal length of the first lens.

6. The optical projection system of claim 1, wherein the optical projection system satisfies the following relationship:

-31<f3-f2<-4.5；

wherein f3 is the focal length of the third lens.

7. The optical projection system of claim 1, wherein the material of each lens is plastic.

8. A projection module comprising an aperture stop and the optical projection system of any of claims 1-7, wherein the photosensitive element is located image-wise of the first lens element.

9. A welcome lamp comprising an illumination assembly, a lamp housing and the projection module set forth in claim 8, wherein the illumination assembly and the projection module set are located in the lamp housing, the illumination assembly and the projection module set are located on the same optical axis, and the illumination assembly is located on the object side of the third lens.

10. The greeting lamp of claim 9, wherein the illumination assembly includes a fourth lens element and a fifth lens element, the fourth lens element and the fifth lens element are sequentially disposed from an image side to an object side along an optical axis, an object-side surface of the fourth lens element is a plane at the optical axis, an image-side surface of the fourth lens element is a convex surface at the optical axis, an object-side surface of the fifth lens element is a plane at the optical axis, and an image-side surface of the fifth lens element is a convex surface at the optical axis.