CN113406776A

CN113406776A - Lens and manufacturing method thereof

Info

Publication number: CN113406776A
Application number: CN202010507093.2A
Authority: CN
Inventors: 邱伟庭; 曾建雄
Original assignee: Young Optics Inc
Current assignee: Young Optics Inc
Priority date: 2020-03-16
Filing date: 2020-06-05
Publication date: 2021-09-17
Also published as: TW202136844A; TWI828879B

Abstract

A lens includes a first lens group, an aperture stop, and a second lens group arranged in order along an optical axis from an enlargement side to a reduction side. The first lens group is negative diopter and comprises three lenses with diopter. The first lens group comprises a lens with positive diopter and an aspheric lens. The second lens group is positive diopter and comprises three lenses with diopter. The second lens group includes a lens having negative diopter, and the lens closest to the reduction side is a combined lens and includes an aspherical lens. The total number of the lenses with diopter is between 6 and 8. The invention also provides a lens manufacturing method.

Description

Lens and manufacturing method thereof

Technical Field

The present disclosure relates to a lens assembly and a method for manufacturing the same, and more particularly, to an image capturing lens assembly and a method for manufacturing the same.

Background

The traditional wide-angle lens is difficult to reduce in size due to the limitation of the shape and material of the lens, and is difficult to have both wide visual angle and imaging quality under a large aperture. Therefore, the need for wide viewing angle, high image quality, environmental variation resistance, miniaturization and small thermal drift can be satisfied at the same time.

Disclosure of Invention

The invention provides a lens and a manufacturing method thereof, which can effectively reduce the number of lenses, improve aberration, effectively reduce cost and have good optical effect.

The invention provides a lens, which comprises a first lens group, a diaphragm and a second lens group which are sequentially arranged from an amplifying side to a reducing side along an optical axis. The first lens group is negative diopter and comprises three lenses with diopter. The first lens group comprises a lens with positive diopter and an aspheric lens. The second lens group is positive diopter and comprises three lenses with diopter. The second lens group includes a lens having negative diopter, and the lens closest to the reduction side is a combined lens and includes an aspherical lens. The total number of the lenses with diopter is between 6 and 8. The lens barrel satisfies 9< LT/EFL <15 and LT/D1<12, where LT is a distance along an optical axis from a lens surface of the first lens group closest to the magnification side to a lens surface of the second lens group farthest from the first lens group, EFL is an effective focal length of the lens barrel, and D1 is a thickness along the optical axis of a lens closest to the magnification side in the first lens group.

The invention further provides a lens comprising a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens and a sixth lens which are sequentially arranged from the magnifying side to the reducing side along the optical axis. The fifth lens and the sixth lens are cemented lenses. The lens satisfies 9< LT/EFL <15, 4< D6/D5<10, 180< FOV <230, and 80> a2>50, where LT is a distance on an optical axis from a lens surface of the first lens group closest to the magnification side to a lens surface of the second lens group farthest from the first lens group, EFL is an effective focal length of the lens, D5 is a thickness of the fifth lens on the optical axis, D6 is a thickness of the sixth lens on the optical axis, FOV is an angle of view of the lens, and a2 is an angle between an extension line of a concave edge of the second lens and the optical axis.

The present invention further provides a method for manufacturing a lens, which includes providing a lens barrel, and placing and fixing a first lens set, a second lens set and a diaphragm in the lens barrel. The first lens group is negative diopter and comprises three lenses with diopter. The first lens group comprises a lens with positive diopter and an aspheric lens. The second lens group is positive diopter and comprises three lenses with diopter. The second lens group includes a lens having negative diopter, and the lens closest to the reduction side is a combined lens and includes an aspherical lens. The total number of the lenses with diopter is between 6 and 8. The lens barrel satisfies 9< LT/EFL <15 and LT/D1<12, where LT is a distance along an optical axis from a lens surface of the first lens group closest to the magnification side to a lens surface of the second lens group farthest from the first lens group, EFL is an effective focal length of the lens barrel, and D1 is a thickness along the optical axis of a lens closest to the magnification side in the first lens group.

Based on the above, in the lens barrel and the manufacturing method thereof of the present invention, the plurality of aspheric lenses are used to improve the resolution performance, and the negative diopter lens is used to achieve the wide-angle light-receiving capability, so as to effectively reduce the number of lenses, improve the aberration, effectively reduce the cost, and have a good optical effect.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood, the present invention may be implemented in accordance with the content of the description, and in order to make the above and other objects, features, and advantages of the present invention more clearly understood, the following preferred embodiments are described in detail with reference to the accompanying drawings.

Drawings

Fig. 1 is a schematic view of a lens barrel according to an embodiment of the invention.

Fig. 2A and 2B are an astigmatic field curve diagram and a distortion diagram of the lens barrel of the embodiment of fig. 1, respectively.

Fig. 3 is a schematic view of a lens barrel according to another embodiment of the invention.

Fig. 4A and 4B are an astigmatic field curve diagram and a distortion diagram of the lens barrel of the embodiment of fig. 3, respectively.

Fig. 5 is a schematic view of a lens barrel according to another embodiment of the invention.

Fig. 6A and 6B are an astigmatic field curve diagram and a distortion diagram of the lens barrel of the embodiment of fig. 5, respectively.

Detailed Description

Fig. 1 is a schematic view of a lens barrel according to an embodiment of the invention. Please refer to fig. 1. The present embodiment provides a lens 100, which is an image capturing lens and is suitable for use in the fields of security monitoring, vehicle-mounted or mobile photography, and the invention is not limited thereto. Specifically, the lens 100 is, for example, a fish-eye lens, and uses a plurality of aspheric lenses to improve the resolution, and achieves a wide-angle light-receiving capability with a negative-power lens.

The lens 100 has an optical axis a, and includes a first lens group 130, an aperture 140, and a second lens group 150 sequentially arranged from a magnification side 110 to a reduction side 120, wherein the magnification side 110 is a side of the light input lens 100, and the reduction side 120 is a side of the light output lens 100. In the present embodiment, the lens 100 further includes an infrared filter 160 and a light-transmitting protective cover 170, and the light entering the lens 100 can be transmitted from the magnifying side 110 to the reducing side 120 and imaged on the imaging surface 180.

The first lens group 130 has negative refractive power and includes at least one aspherical lens. The first lens group 130 includes a first lens L1, a second lens L2, and a third lens L3 sequentially arranged from the magnification side 110 to the reduction side 120.

The second lens group 150 has a positive refractive power and includes at least one aspherical lens. In this embodiment, the second lens group 150 includes a fourth lens L4, a fifth lens L5, and a sixth lens L6 sequentially arranged from the magnification side 110 to the reduction side 120. Wherein one of the fifth lens element L5 and the sixth lens element L6 has positive refractive power, and the other one has negative refractive power. In the present embodiment, the diopter of the fifth lens element L5 is negative, and the diopter of the sixth lens element L6 is positive. However, in an embodiment, the diopter of the fifth lens L5 can be positive, and the diopter of the sixth lens L6 can be negative, and the invention is not limited thereto. In the present embodiment, at least two lenses (i.e., the fifth lens L5 and the sixth lens L6) of the second lens group 150 that are closest to the reduced side 120 are cemented lenses.

Specifically, in the present embodiment, the total number of lenses of the lens 100 is 6, the number of aspheric lenses is 4, and the number of cemented lenses is 1, so that the number of lenses can be effectively reduced and the aberration can be improved. In addition, in the present embodiment, the diopters of the 6 lenses in the lens 100 are negative, positive, negative and positive in sequence from the magnifying side 110 to the shrinking side 120, and the materials are glass, plastic, glass, plastic and plastic, respectively. In other words, the material of the second lens element L2, the third lens element L3, the fifth lens element L5 and the sixth lens element L6 is plastic. Therefore, the cost can be effectively reduced, but the invention is not limited thereto.

The lens 100 of the present embodiment has a number of lenses with diopter between 6 and 8, which is preferable and cost effective. Further, the lens barrel 100 of the present embodiment conforms to 9< LT/EFL <15, where LT is a distance along the optical axis a from a lens surface closest to the magnification side 110 in the lens barrel 100 (i.e., the surface S1 of the first lens L1) to a lens surface closest to the reduction side 120 in the lens barrel 100 (i.e., the surface S13 of the sixth lens L6), and EFL is an effective focal length of the lens barrel 100. In the present embodiment, the lens 100 conforms to LT/D1<12, where D1 is the thickness of the lens closest to the magnification side 110 (i.e., the first lens L1) in the lens 100 along the optical axis a. It is worth mentioning that the diopter of an image side surface (i.e., the surface S6) of the third lens element L3 is positive.

On the other hand, in the present embodiment, the lens barrel 100 conforms to 4< Z1/Z2<10, where Z1 is the larger thickness of the fifth lens L5 or the sixth lens L6 along the optical axis a, and Z2 is the smaller thickness of the fifth lens L5 or the sixth lens L6 along the optical axis a.

In addition, the lens 100 of the present embodiment conforms to 180 degrees < FOV <230 degrees, where FOV is the maximum field angle of the lens 100. In a preferred embodiment, the lens 100 conforms to a FOV >210 degrees. The thickness of the lens closest to the magnification side 110 (i.e., the first lens L1) in the present embodiment along the optical axis a is larger than 1 mm. The lens 100 of the present embodiment conforms to 0.7< R1/LT <2, where R1 is the effective radius R1 of the lens closest to the magnification side 110 (i.e., the first lens L1) in the lens 100. The lens barrel 100 of the present embodiment conforms to 0.2< RL/LT <0.38, where RL is the effective radius r6 of the lens closest to the reduction side 120 (i.e., the sixth lens L6) in the lens barrel 100. The lens 100 of the present embodiment conforms to D6/D5>2, where T6 is the thickness of the sixth lens L6 along the optical axis a, and D5 is the thickness of the fifth lens L5 along the optical axis a. The lens 100 of the present embodiment conforms to 50< a2<80, where a2 is an included angle B (or opening angle) between a tangent of a concave edge of the second lens element L2 and a direction perpendicular to the optical axis a, as shown in fig. 1.

Therefore, in the present embodiment, the lens 100 is a fixed focus imaging lens, and the aperture of the lens 100 can reach F/2.0, the total length can be within 12.5mm, and the half-viewing angle can reach more than 105 degrees. More specifically, the lens 100 of the present embodiment is a fish-eye lens, which can effectively reduce the number of lenses, improve aberration, effectively reduce cost, and has a good optical effect.

In the present embodiment, the actual design of the aforementioned components can be found in table one below.

Watch 1

Please refer to fig. 1 and table one at the same time. Specifically, in the lens barrel 100 of the present embodiment, the first lens L1 has a surface S1 and a surface S2 in sequence from the magnification side 110 to the reduction side 120, the first lens L2 has a surface S3 and a surface S4 in sequence from the magnification side 110 to the reduction side 120, the surface S3 and the surface S4 are aspheric surfaces, i.e., aspheric surfaces are denoted by symbol x, and so on, and the description of the surfaces corresponding to the elements is not repeated. Further, TTL is the total lens length, i.e., the distance along the optical axis a from the lens surface closest to the magnification side 110 in the lens barrel 100 (i.e., the surface S1 of the first lens L1) to the image plane 180 in the lens barrel 100, and IMH is the image plane diameter.

In addition, the spacing in Table one is the distance between the surface from the enlarged side 110 to the next surface of the reduced side 120. In other words, the thickness of the first lens L1 is 10.465 mm, the thickness of the second lens L2 is 6.101 mm, and the distance between the adjacent surfaces of the first lens L1 and the second lens L2 is 2.931 mm, and so on, and thus the description is not repeated.

In addition, the radius of curvature in table one is the radius of curvature of the surface, and the positive and negative values thereof represent the direction of the curvature, for example, the radius of curvature of the surface S1 of the first lens L1 is positive, and the radius of curvature of the surface S2 of the first lens L1 is positive. Therefore, the first lens L1 is a convex-concave lens. Also, for example, the radius of curvature of the surface S12 of the sixth lens L6 is positive, and the radius of curvature of the surface S13 of the sixth lens L6 is negative. Therefore, the first lens L1 is a biconvex lens, and so on, and thus the description thereof is not repeated.

The second table below lists the values of the conic coefficients K and the aspheric coefficients A-H of each order for each aspheric surface. The aspherical polynomial can be expressed by the following formula (1):

where x is the offset (sag) in the direction of the optical axis a, c' is the reciprocal of the radius of the Osculating Sphere (Osculating Sphere), i.e. the reciprocal of the radius of curvature near the optical axis, K is the conic coefficient, and y is the aspheric height, i.e. the height from the center of the lens to the edge of the lens. A-H represent aspheric coefficients of respective orders of the aspheric polynomial, respectively.

Watch two

	S3	S4	S5	S6
					K	-1.924	-0.988	-4.477	-6.852
A	0	0	0	0
					B	9.14E-04	4.92E-02	6.20E-02	7.08E-02
C	-7.76E-03	4.06E-02	4.89E-03	-6.29E-03
					D	2.47E-03	-4.61E-02	-4.27E-03	-1.63E-01
E	-3.72E-04	2.00E-02	5.05E-03	5.67E-01
					F	2.84E-05	1.77E-03	-1.72E-03	-1.01E-02
G	-8.25E-07	1.71E-03	5.58E-04	-1.26E+00
					H	-1.14E-08	-1.43E-03	-3.01E-04	8.52E-01
	S10	S11	S12	S13
					K	1.14	-1.693	-1.693	-6.985
A	0	0	0	0
					B	-3.74E-02	2.48E-02	2.48E-02	-4.59E-02
C	2.49E-02	3.62E-02	3.62E-02	3.02E-02
					D	-8.76E-03	-1.23E-02	-1.23E-02	-1.16E-02
E	-7.24E-06	-3.13E-05	-3.13E-05	2.08E-03
					F	8.48E-06	1.17E-05	1.17E-05	3.62E-05
G	1.35E-04	5.21E-05	5.21E-05	-5.48E-05
					H	1.50E-04	1.06E-04	1.06E-04	4.16E-06

Fig. 3 is a schematic view of a lens barrel according to another embodiment of the invention. Please refer to fig. 3. The lens 100A shown in the present embodiment is similar to the lens 100 shown in fig. 1. The main difference between the two is that, in the present embodiment, the surface S11 of the fifth lens L5 is a spherical surface.

In the present embodiment, the actual design of the foregoing components can be found in table three below. The interpretation of table three is the same as that of table one, and therefore, the explanation is omitted.

Watch III

The fourth table below lists the values of the conic coefficients K and the aspheric coefficients A-H of each order for each aspheric surface.

Watch four

Fig. 5 is a schematic view of a lens barrel according to another embodiment of the invention. Please refer to fig. 5. The lens 100B of the present embodiment is similar to the lens 100 shown in fig. 1. The main difference between the two is that the surface S11 of the fifth lens L5 is a spherical surface in this embodiment.

In this embodiment, the actual design of the foregoing components can be seen in table five below. The interpretation of table five is the same as that of table one, and therefore, the explanation is omitted.

Watch five

The sixth table below lists the values of the conic coefficients K and the aspheric coefficients A-H of each order for each aspheric surface.

Watch six

Fig. 2A and 2B, fig. 4A and 4B, and fig. 6A and 6B are an astigmatic field curvature diagram and a distortion diagram of the

lenses

100, 100A, and 100B according to the embodiment, respectively. Fig. 2A, 4A, and 6A are graphs of astigmatic field curvatures (astigmatic field curvatures) of the

lenses

100, 100A, and 100B, in which the horizontal axis represents the focal point displacement (mm), the vertical axis represents the image height, T represents a curve in the meridional direction, S represents a curve in the sagittal direction, and different line segment patterns represent measurement at different wavelengths. Fig. 2B, 4B, and 6B are graphs of distortion (distortion) of the

lenses

100, 100A, and 100B, in which the horizontal axis represents distortion percentage (%), the vertical axis represents image height, and different line segment patterns represent measurement at different wavelengths. It can be verified that the astigmatic field curvatures and distortions exhibited by the

lenses

100, 100A, and 100B of the present embodiment are within the standard range between 450 nm and 650 nm, and thus have good optical imaging quality, as shown in fig. 2A and 2B, fig. 4A and 4B, and fig. 6A and 6B.

In summary, in the lens barrel and the manufacturing method thereof of the present invention, the plurality of aspheric lenses are used to improve the resolution, and the negative diopter lens is used to achieve the wide-angle light-receiving capability, so as to effectively reduce the number of lenses, improve the aberration, effectively reduce the cost, and have a good optical effect.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A lens barrel characterized by comprising:

a first lens group, a diaphragm and a second lens group arranged in sequence from an enlarged side to a diminished side along an optical axis;

wherein the content of the first and second substances,

the first lens group is negative diopter, the first lens group comprises three lenses with diopter, the first lens group comprises a lens with positive diopter, and the first lens group comprises an aspheric lens;

the second lens group is positive diopter, the second lens group comprises three lenses with diopter, the second lens group comprises a lens with negative diopter, the lens of the second lens group closest to the reduction side is a combined lens, and the second lens group comprises an aspheric lens;

the total number of the lenses with diopter is between 6 and 8; and

the lens satisfies the following conditions:

(1)9< LT/EFL <15, where LT is a distance along the optical axis from a lens surface of the first lens group closest to the magnification side to a lens surface of the second lens group farthest from the first lens group, and EFL is an effective focal length of the lens barrel; and

(2) LT/D1<12, wherein D1 is a thickness of a lens closest to the magnification side in the first lens group along the optical axis.

2. The lens barrel as claimed in claim 1, wherein the first lens group includes a first lens, a second lens and a third lens arranged in order along the optical axis from the magnification side toward the reduction side, and the second lens group includes a fourth lens, a fifth lens and a sixth lens arranged in order along the optical axis from the magnification side toward the reduction side.

3. A lens barrel, comprising:

a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens and a sixth lens which are sequentially arranged from an enlargement side to a reduction side along an optical axis;

wherein the content of the first and second substances,

the fifth lens and the sixth lens are a cemented lens; and

the lens satisfies the following conditions:

(1)9< LT/EFL <15, where LT is a distance along the optical axis from a lens surface of the first lens group closest to the magnification side to a lens surface of the second lens group farthest from the first lens group, and EFL is an effective focal length of the lens barrel;

(2)4< D6/D5<10, wherein D5 is a thickness of the fifth lens along the optical axis, and D6 is a thickness of the sixth lens along the optical axis;

(3)180< FOV <230, where FOV is the field angle of the lens; and

(4)80> A2>50, wherein A2 is the angle between the line of extension of the concave edge of the second lens and the optical axis.

4. The lens of claim 1 or 3, wherein the lens conforms to a FOV >210, where FOV is the field angle of the lens.

5. A lens barrel according to claim 1 or 3, wherein a thickness of a lens closest to the magnification side along the optical axis is larger than 1 mm.

6. The lens barrel according to claim 2 or 3, wherein diopters of the first lens to the fourth lens are negative, positive, and positive in order.

7. The lens barrel as claimed in claim 2 or 3, wherein one of the fifth lens and the sixth lens has a positive refractive power and the other thereof has a negative refractive power.

8. The lens barrel as claimed in claim 2 or 3, wherein the first lens and the fourth lens are made of glass, and the second lens, the third lens, the fifth lens and the sixth lens are made of plastic.

9. The lens barrel according to claim 2 or 3, wherein the lens barrel conforms to 4< Z1/Z2<10, wherein Z1 is the larger thickness of the fifth lens or the sixth lens along the optical axis, and Z2 is the smaller thickness of the fifth lens or the sixth lens along the optical axis.

10. A method for manufacturing a lens, comprising:

providing a lens barrel; and

a first lens group, a second lens group and a diaphragm are arranged and fixed in the lens cone,

wherein the first lens group has negative diopter, the first lens group comprises three lenses with diopter, the first lens group comprises a lens with positive diopter, the first lens group comprises an aspheric lens, the second lens group has positive diopter, the second lens group comprises three lenses with diopter, the second lens group comprises a lens with negative diopter, the lens of the second lens group closest to the reduction side is a combined lens, the second lens group comprises an aspheric lens, and the total number of the lenses with diopter is between 6 and 8 lenses,

the lens satisfies the following conditions: