CN214895980U - Small short-distance identification lens - Google Patents

Abstract

The invention provides a small short-distance identification lens which has the advantages of small volume, easiness in processing, good imaging quality and the like, has better resolution in a short-distance scene, and sequentially comprises an aperture diaphragm (ST), a first lens (L1), a second lens (L2), a third lens (L3), a fourth lens (L4) and chip protection glass (CG) from an object plane to an image plane; the first lens (L1) is a positive lens, and both the object side surface and the image side surface of the first lens are convex; the second lens (L2) is a negative lens, and both the object side surface and the image side surface of the negative lens are concave; the third lens (L3) is a positive lens, the object side surface of the third lens is concave, and the image side surface of the third lens is convex; the fourth lens (L4) is a negative lens, and both the object-side surface and the image-side surface of the fourth lens are concave.

Description

Small short-distance identification lens

[ technical field ] A method for producing a semiconductor device

The invention relates to a small short-distance identification lens.

[ background of the invention ]

With the increasing degree of social informatization, people also put forward higher requirements on information acquisition technologies. In the current society, intelligent identification technologies such as fingerprint identification, face identification and pupil identification are more and more widely applied, and an identification lens is a key in the intelligent identification technology, so that in order to meet the market demand and solve the problems that the optical aperture of the existing lens is not small enough, the distortion is large and the like, an identification lens with small volume, simple structure, high imaging quality and low production cost needs to be designed.

The present invention has been made based on such a situation.

[ summary of the invention ]

Aiming at the defects or improvement requirements of the prior art, the invention provides a small short-distance identification lens which has the obvious advantages of small volume, wide view field, easy production and the like, ensures higher imaging quality, reduces distortion and the whole length of the lens, ensures that the whole length of the whole lens is less than 5mm, and greatly reduces the processing difficulty and the production cost because the used aspheric lenses are made of plastic materials.

In order to achieve the purpose, the invention adopts the technical scheme that:

a small-sized close-range identification lens comprises an aperture diaphragm (ST), a first lens (L1), a second lens (L2), a third lens (L3), a fourth lens (L4) and chip protection glass (CG) in sequence from an object plane to an image plane; the first lens (L1) is a positive lens, and both the object side surface and the image side surface of the first lens are convex; the second lens (L2) is a negative lens, and both the object side surface and the image side surface of the negative lens are concave; the third lens (L3) is a positive lens, the object side surface of the third lens is concave, and the image side surface of the third lens is convex; the fourth lens (L4) is a negative lens, and both the object-side surface and the image-side surface of the fourth lens are concave.

The small-size short-distance identification lens is characterized in that:

1.5<TTL/f<1.8； (1)

wherein, TTL is the distance on the optical axis from the object plane to the imaging plane of the small-sized close-range identification lens, and f is the effective focal length of the lens.

The small short-distance identification lens can ensure that the lens has shorter working distance under the condition of meeting the formula (1) and has higher imaging quality in a close scene.

Above-mentioned small-size recognition lens closely, its characterized in that, first lens (L1), second lens (L2), third lens (L3), fourth lens (L4) are the plastic aspheric lens, greatly reduced the processing degree of difficulty and the manufacturing cost of lens, be favorable to the camera lens volume production.

The small-size short-distance identification lens is characterized in that:

0.5<f1/f<0.9； (2)

-1.71<f2/f<-1.45； (3)

0.61<f3/f<0.73； (4)

-0.59<f4/f<-0.53； (5)

where f1 is an effective focal length of the first lens (L1), f2 is an effective focal length of the second lens (L2), f3 is an effective focal length of the third lens (L3), f4 is an effective focal length of the fourth lens (L4), and f is an effective focal length of the small-sized short-distance recognition lens.

The second lens (L2) has a larger focal length, which is beneficial to correcting higher-order aberration, the positive and negative lenses of the first lens (L1) and the second lens (L2) are matched with each other, and the positive and negative lenses of the third lens (L3) and the fourth lens (L4) are matched with each other, which is beneficial to correcting chromatic aberration, astigmatism and distortion. The optical power of the first lens (L1), the third lens (L3) and the fourth lens (L4) is uniformly distributed, so that the tolerance sensitivity is reduced, and the aberration is reduced.

The small-size short-distance identification lens is characterized in that:

0.22<T1/∑T<0.28； (6)

0.21<T2/∑T<0.27； (7)

0.29<T3/∑T<0.33； (8)

0.15<T4/∑T<0.19； (9)

Σ T is the total of the thicknesses of the first lens (L1), the second lens (L2), the third lens (L3), and the fourth lens (L4) on the optical axis, and T1, T2, T3, and T4 are the lens thicknesses of the first lens (L1), the second lens (L2), the third lens (L3), and the fourth lens (L4) on the optical axis, respectively.

The small-sized short-distance identification lens is favorable for controlling the center thickness of each lens and reducing the sensitivity of tolerance under the condition of meeting the formulas (6), (7), (8) and (9), and restricts the whole length of the lens to the maximum extent on the basis of considering the injection molding process, thereby realizing the miniaturization of the lens and simultaneously ensuring better imaging quality.

The small-size short-distance identification lens is characterized in that:

30<|Vd1-Vd2|<35； (10)

wherein Vd1 is the abbe number of the first lens (L1); vd2 is the abbe number of the second lens (L2).

Satisfying formula (10) can restrain the material scope of camera lens, reduces the colour difference.

The small-size short-distance identification lens is characterized in that:

4.5<L/f<7.3； (11)

wherein, L is the optimal imaging object distance of the small-sized short-distance identification lens, and f is the effective focal length of the lens.

The small-sized short-distance identification lens is beneficial to balancing the relation between the object distance and the focal length under the condition of satisfying the formula (11), and the depth of field is optimized while the imaging quality is ensured.

The small-size short-distance identification lens is characterized in that:

0.4<D/f<0.7； (12)

wherein D is the diaphragm diameter of the small-sized close-range identification lens, and f is the effective focal length of the lens.

The small short-distance identification lens satisfying the formula (12) has a large relative aperture, and is beneficial to improving the image quality and the overall illumination of the lens.

The small-size short-distance identification lens is characterized in that:

1.68<TTL/ImgH<2.31； (13)

1.03<f/ImgH<1.35； (14)

wherein, TTL is the distance between the object plane and the imaging plane of the small close-range identification lens on the optical axis, ImgH is the maximum half-image height of the lens, and f is the effective focal length of the lens.

The formulas (13) and (14) can limit the overall length, the imaging quality and the angle of view of the small-sized short-distance recognition lens within a proper range, meet the miniaturization requirement and ensure that the image quality of the lens is fit with the requirement of practical application.

[ description of the drawings ]

FIG. 1 is a schematic structural diagram of the compact short-distance recognition lens;

FIG. 2 is a diagram showing the on-axis aberration of the compact short-distance recognition lens;

FIG. 3 is a diagram of aberration curves of the compact short-range identification lens;

fig. 4 is a distortion diagram of the small short-distance recognition lens.

[ detailed description ] embodiments

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in fig. 1, the compact short-distance recognition lens provided by the present invention sequentially includes an aperture Stop (ST), a first lens (L1), a second lens (L2), a third lens (L3), a fourth lens (L4), and a chip protection glass (CG) from an object plane to an image plane; the first lens (L1) is a positive lens, and both the object side surface and the image side surface of the first lens are convex; the second lens (L2) is a negative lens, and both the object side surface and the image side surface of the negative lens are concave; the third lens (L3) is a positive lens, the object side surface of the third lens is concave, and the image side surface of the third lens is convex; the fourth lens (L4) is a negative lens, and both the object-side surface and the image-side surface of the fourth lens are concave.

Compared with the prior identification lens, the small-sized short-distance identification lens has the advantages of small volume, easiness in processing, good imaging quality and the like, has better resolution ratio in a close scene, and the aspheric lenses of the lens are made of plastic materials, so that the production cost and the processing difficulty are greatly reduced, and the small-sized short-distance identification lens is more suitable for mass production.

Some optical parameters in the small-sized short-distance recognition lens embodiment are as follows, in the lens data table of this embodiment, the units of radius and thickness are mm, and S (solid line) and T (broken line) in the aberration graphs represent sagittal image plane and meridional image plane, respectively.

The following table is a table of lens data for the examples

Table 1 is a structural parameter table of a small short-distance identification lens

Surface	Type	Radius(mm)	Thickness(mm)	Glass
					Object	Sphere	Infinity	15.1953
Stop	Sphere	Infinity	-0.15
					2	Asphere	1.5818	0.5511	1.54:56.2
3	Asphere	-14.3938	0.1271
					4	Asphere	-12.0000	0.6291	1.64:22.4
5	Asphere	4.4204	0.6233
					6	Asphere	-5.6299	0.7866	1.54:56.2
7	Asphere	-0.9467	0.2215
					8	Asphere	14.7203	0.4509	1.53:55.9
9	Asphere	0.8505	0.4883
					10	Sphere	Infinity	0.4000	1.51:64.2
11	Sphere	Infinity	0.5963
					Image	Sphere	Infinity	0.0000

TABLE 1

Table 2 shows the ratio of rise to radius R of the first lens L1 of the compact short-range recognition lens

TABLE 2

Table 3 shows the ratio of rise to radius R of the second lens L2 of the compact short-range recognition lens

TABLE 3

Table 4 shows the ratio of rise to radius R of the third lens L3 of the compact short-range recognition lens

TABLE 4

Table 5 shows the ratio of rise to radius R of the fourth lens L4 of the compact short-range recognition lens

Table 5.

Claims (9)

1. A small-sized close-range identification lens is characterized by comprising an aperture diaphragm (ST), a first lens (L1), a second lens (L2), a third lens (L3), a fourth lens (L4) and chip protection glass (CG) in sequence from an object plane to an image plane; the first lens (L1) is a positive lens, and both the object side surface and the image side surface of the first lens are convex; the second lens (L2) is a negative lens, and both the object side surface and the image side surface of the negative lens are concave; the third lens (L3) is a positive lens, the object side surface of the third lens is concave, and the image side surface of the third lens is convex; the fourth lens (L4) is a negative lens, and both the object-side surface and the image-side surface of the fourth lens are concave.

2. A compact short-range recognition lens according to claim 1, wherein the following relation is satisfied:

1.5<TTL/f<1.8；

wherein, TTL is the distance on the optical axis from the object plane to the imaging plane of the small-sized close-range identification lens, and f is the effective focal length of the lens.

3. The compact short-range identification lens of claim 1, wherein the first lens (L1), the second lens (L2), the third lens (L3) and the fourth lens (L4) are all plastic aspheric lenses.

4. A compact short-range recognition lens according to claim 1, wherein the following relation is satisfied:

0.5<f1/f<0.9；

-1.71<f2/f<-1.45；

0.61<f3/f<0.73；

-0.59<f4/f<-0.53；

where f1 is an effective focal length of the first lens (L1), f2 is an effective focal length of the second lens (L2), f3 is an effective focal length of the third lens (L3), f4 is an effective focal length of the fourth lens (L4), and f is an effective focal length of the small-sized short-distance recognition lens.

5. A compact short-range recognition lens according to claim 1, wherein the following relation is satisfied:

0.22<T1/∑T<0.28；

0.21<T2/∑T<0.27；

0.29<T3/∑T<0.33；

0.15<T4/∑T<0.19；

Σ T is the total of the thicknesses of the first lens (L1), the second lens (L2), the third lens (L3), and the fourth lens (L4) on the optical axis, and T1, T2, T3, and T4 are the lens thicknesses of the first lens (L1), the second lens (L2), the third lens (L3), and the fourth lens (L4) on the optical axis, respectively.

6. A compact short-range recognition lens according to claim 1, wherein the following relation is satisfied:

30<|Vd1-Vd2|<35；

wherein Vd1 is the abbe number of the first lens (L1); vd2 is the abbe number of the second lens (L2).

7. A compact short-range recognition lens according to claim 1, wherein the following relation is satisfied:

4.5<L/f<7.3；

wherein, L is the optimal imaging object distance of the small-sized short-distance identification lens, and f is the effective focal length of the lens.

8. A compact short-range recognition lens according to claim 1, wherein the following relation is satisfied:

0.4<D/f<0.7；

wherein D is the diaphragm diameter of the small-sized close-range identification lens, and f is the effective focal length of the lens.

9. A compact short-range recognition lens according to claim 1, wherein the following relation is satisfied:

1.68<TTL/ImgH<2.31；

1.03<f/ImgH<1.35；

wherein, TTL is the distance between the object plane and the imaging plane of the small close-range identification lens on the optical axis, ImgH is the maximum half-image height of the lens, and f is the effective focal length of the lens.

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