CN111999868B

CN111999868B - Zoom lens

Info

Publication number: CN111999868B
Application number: CN202010682065.4A
Authority: CN
Inventors: 苏元宏; 陈凯筠
Original assignee: Young Optics Inc
Current assignee: Young Optics Inc
Priority date: 2014-10-10
Filing date: 2014-10-10
Publication date: 2022-07-05
Anticipated expiration: 2034-10-10
Also published as: CN111999868A; CN105572854A

Abstract

A zoom lens comprises a first lens, a second lens, a double-cemented lens, a third lens, a fourth lens, a fifth lens, a sixth lens and an aperture diaphragm, wherein the aperture diaphragm is arranged between the second lens and the third lens, the first lens is closest to an object side, when the zoom lens zooms, the aperture diaphragm is fixed, the first lens, the second lens and the cemented lens move to the aperture diaphragm, and a variable distance is arranged between the fourth lens and the fifth lens, wherein all lenses between the object side and the aperture stop form a lens group with negative diopter, all the lenses between the aperture stop and the variable pitch constitute a lens group with positive diopter, all the lenses at the other end of the variable pitch constitute a lens group with positive diopter, and one of the third lens, the fourth lens, the fifth lens and the sixth lens is an aspherical lens. The zoom lens has good imaging quality at the telephoto end, the wide-angle end and the middle position.

Description

Zoom lens

The application is a divisional application of an invention patent application with the application number of 201410529702.9, the application date of the original application is 2014, 10 and 10, and the invention creates the name of a zoom lens.

Technical Field

The present invention relates to a lens, and more particularly, to a zoom lens.

Background

The image capturing device captures an image of an object side by a lens and an image sensing element, wherein the lens can be used for focusing a light beam from the object side on the image sensing element. The lens can be divided into a fixed focus lens and a zoom lens, and the zoom lens has a function of changing the focal length, so that the zoom lens has great advantage in use convenience. The good zoom lens has to have good imaging quality in each focal segment, and how to design the zoom lens with good imaging quality in each focal segment is a great problem for lens designers.

At present, there are many patents related to zoom lenses, such as us patents No. 8,369,021, 5,481,404, 8,477,427, 4,838,669, 8,654,451, 4,468,097, 5,146,366 and 5,132,848. However, in the conventional zoom lens, two or more groups of lenses are used, and in the zoom lens using two groups of lenses, the resolution of the focal zones at the wide angle end, the telephoto end, the middle position, etc. is difficult to be optimized simultaneously, so the resolution of some focal zones is sacrificed. In addition, the zoom lens using four or more lens groups requires a complicated moving mechanism to move the lens groups, which results in high cost.

Disclosure of Invention

The invention provides a zoom lens which has good imaging quality in each focal section.

The zoom lens provided by the invention comprises a first lens, a second lens, a double-cemented lens, a third lens, a fourth lens, a fifth lens, a sixth lens and an aperture diaphragm, wherein the aperture diaphragm is arranged between the second lens and the third lens, the first lens is closest to an object side, when the zoom lens zooms, the aperture diaphragm is fixed, the first lens, the second lens and the cemented lens move to the aperture diaphragm, and a variable distance is arranged between the fourth lens and the fifth lens, wherein all lenses between the object side and the aperture stop form a lens group with negative diopter, all the lenses between the aperture stop and the variable pitch constitute a lens group with positive diopter, all the lenses at the other end of the variable pitch constitute a lens group with positive diopter, and one of the third lens, the fourth lens, the fifth lens and the sixth lens is an aspherical lens.

In an embodiment of the invention, a radius of a surface of the first lens facing the object side is D1, a radius of a surface of the sixth lens away from the object side is D2, and D1/D2 are greater than 3.77.

In an embodiment of the invention, a surface of the first lens element facing the object side is a convex surface.

In an embodiment of the invention, at least two of the third lens, the fourth lens, the fifth lens and the sixth lens are lenses with an abbe number greater than 80 and with positive diopter.

In an embodiment of the invention, the zoom lens includes at least two lenses having abbe numbers greater than 80.

In an embodiment of the present invention, when the zoom lens zooms, the third lens, the fourth lens, the fifth lens, and the sixth lens move toward the aperture stop.

In an embodiment of the invention, the first lens has a negative diopter, the second lens has a negative diopter, the double cemented lens is composed of lenses having a negative diopter and a positive diopter, the third lens has a negative diopter, the fourth lens has a positive diopter, the fifth lens has a negative diopter, and the sixth lens has a positive diopter.

In an embodiment of the invention, a seventh lens is further included between the aperture stop and the variable pitch, and the third lens, the fourth lens and the seventh lens form a triple cemented lens, and the abbe number of the lens in the middle of the triple cemented lens is greater than the abbe numbers of the lenses on both sides.

In an embodiment of the invention, the seventh lens element has a positive refractive power.

In an embodiment of the invention, an eighth lens is further included between the aperture stop and the third lens, and the eighth lens has a positive refractive power.

The zoom lens adopts a structure of three groups of lens groups, and the immovable aperture diaphragm is arranged between the first lens group and the second lens group, so that good imaging quality is achieved at the telephoto end, the wide-angle end and the middle position. In addition, compared with the conventional zoom lens with four groups of lenses, the zoom lens of the invention is beneficial to reducing the production cost because the number of the lens groups is less.

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. 1A and 1B are schematic diagrams of a zoom lens according to an embodiment of the present invention at a wide-angle end and a telephoto end.

Fig. 2A and 2B are schematic diagrams of a zoom lens according to another embodiment of the present invention at a wide-angle end and a telephoto end.

Fig. 3A and 3B are schematic diagrams of a zoom lens according to another embodiment of the present invention at a wide-angle end and a telephoto end.

FIG. 4 is a schematic diagram of a zoom lens according to another embodiment of the present invention.

Detailed Description

Fig. 1A and 1B are schematic diagrams of a zoom lens according to an embodiment of the present invention at a wide-angle end and a telephoto end. Referring to fig. 1A, the zoom lens 200 of the present embodiment includes a first lens group 210, a second lens group 220, a third lens group 230 and an aperture stop 240, wherein the first lens group 210, the aperture stop 240, the second lens group 220 and the third lens group 230 are sequentially arranged along an optical axis 250 from an object side to an image side, that is, the second lens group 220 is disposed between the first lens group 210 and the third lens group 230, and the aperture stop 240 is disposed between the first lens group 210 and the second lens group 220. When the zoom lens 200 zooms, the aperture stop 240 is fixed, and the first lens group 210, the second lens group 220, and the third lens group 230 are selectively movable.

Referring to fig. 1A and 1B, specifically, when the zoom lens 200 zooms from the wide-angle end (as shown in fig. 1A) to the telephoto end (as shown in fig. 1B), the aperture stop 240 is fixed, the first lens group 210 moves toward the aperture stop 240, and the second lens group 220 and the third lens group 230 also move toward the aperture stop 240, for example. When the zoom lens 200 zooms from the telephoto end to the wide-angle end, the aperture stop 240 is fixed, the first lens group 210 moves away from the aperture stop 240, and the second lens group 220 and the third lens group 230 move away from the aperture stop 240. In addition, the zoom lens 200 of the present embodiment performs focusing by fine-tuning the position of the first lens group 210.

The first lens group 210 has, for example, a negative refractive power, the second lens group 220 has, for example, a positive refractive power, and the third lens group 230 has, for example, a positive refractive power. The first lens group 210 includes a first lens 211 having a negative refractive power, a second lens 212 having a negative refractive power, a third lens 213 having a negative refractive power, and a fourth lens 214 having a positive refractive power, which are arranged in order from the object side to the image side. The second lens group 220 includes a fifth lens 221 having a positive refractive power, a sixth lens 222 having a negative refractive power, and a seventh lens 223 having a positive refractive power, which are sequentially arranged in a direction from the object side to the image side. The third lens group 230 includes an eighth lens 231 having a negative refractive power and a ninth lens 232 having a positive refractive power, which are sequentially arranged in a direction from the object side to the image side. The fourth lens 214 is located between the third lens 213 and the fifth lens 221, and the eighth lens 231 is located between the seventh lens 223 and the ninth lens 232. In the present embodiment, the third lens 213 and the fourth lens 214 are, for example, cemented lenses, and the sixth lens 222 and the seventh lens 223 are, for example, cemented lenses, but the invention is not limited thereto.

The following will give an example of the parameters of the zoom lens 200. It should be noted that the data listed in the tables of the following embodiments are not intended to limit the present invention, and those skilled in the art may make appropriate changes to the parameters or settings thereof after referring to the present invention, which should fall within the scope of the present invention.

(watch one)

(watch two)

	Wide angle end	Telescope end
			Variable pitch A	13.47	2.18
Variable pitch B	6.30	0.10
			Variable spacing C	0.14	0.30
Variable spacing D	3.66	9.71

In the first table, the surfaces S1, S2 are two surfaces of the first lens 211, the surfaces S3, S4 are two surfaces of the second lens 212, and the third lens 213 and the fourth lens 214 are combined to be a cemented lens, for example, so the surface S5 is one surface of the third lens 213, the surface S6 is one surface of the third lens 213 cemented to the fourth lens 214, the surface S7 is the other surface of the fourth lens 214, the surface S8 is the aperture stop 240, the surfaces S9, S10 are two surfaces of the fifth lens 221, the sixth lens 222 and the seventh lens 223 are combined to be a cemented lens, for example, so the surface S11 is one surface of the sixth lens 222, the surface S12 is one surface of the sixth lens 222 cemented to the seventh lens 223, the surface S13 is the other surface of the seventh lens 223, the surfaces S14, S15 are two surfaces of the eighth lens 231, the surfaces S16, the surfaces S17 are two surfaces of the ninth lens 232, and the surface S18 is an image forming surface. If the zoom lens 200 is applied to an image capturing device, the surface S18 is an image sensing surface of the image sensing device. The pitch referred to in Table one is the linear distance between two adjacent surfaces on the optical axis 250. For example, the distance between the surface S1 is the linear distance between the surface S1 and the surface S2 on the optical axis 250.

In the present embodiment, the surfaces S7, S8, S13, and S17 are variable pitches, and specifically, as shown in table two, the pitch of the surface S7 at the wide-angle end is 13.47 millimeters (mm), the pitch at the telephoto end is 2.18 mm, the pitch of the surface S8 at the wide-angle end is 6.30 mm, the pitch at the telephoto end is 0.10 mm, the pitch of the surface S13 at the wide-angle end is 0.14 mm, the pitch at the telephoto end is 0.30 mm, the pitch of the surface S17 at the wide-angle end is 3.66 mm, and the pitch at the telephoto end is 9.71 mm.

The zoom lens 200 of the present embodiment adopts a three-group lens structure, and the stationary aperture stop 240 is disposed between the first lens group 210 and the second lens group 220, so as to have good imaging quality at the telephoto end, the wide-angle end and the middle position. Compared with the conventional zoom lens with four lens groups, the zoom lens 200 has a smaller number of lens groups, which helps to reduce the production cost. In addition, in order to make the zoom lens 200 achieve the confocal effect of visible light and infrared light, the second lens group 220 and the third lens group 230 include at least one lens with an abbe number greater than 45 and a positive refractive power. For example, the second lens group 220 and the third lens group 230 of the present embodiment have three lenses with abbe numbers greater than 45 and positive refractive power, i.e., the fifth lens 221, the seventh lens 223, and the ninth lens 232.

In addition, in order to eliminate the aberration generated by the large aperture, the second lens group 220 and the third lens group 230 include at least one aspheric lens. For example, the second lens group 220 and the third lens group 230 include two aspheric lenses, i.e., the fifth lens 221 of the second lens group 220 and the ninth lens 232 of the third lens group 230 are aspheric lenses. The shapes of the surfaces S9, S10 of the fifth lens 221 and the surfaces S16, S17 of the ninth lens 232 conform to the following aspheric formula:

where z (h) is the offset (sag) in the direction of the optical axis 250, and r is the radius of curvature near the optical axis 250 (e.g., the radius of curvature of the surfaces S9, S10, S16, and S17 in table one). k is a conic constant (con constant), and h is an aspheric height, i.e., a height from the center of the lens to the edge of the lens. C2, C4, C6, C8, C10.

(watch three)

Fig. 2A and 2B are schematic diagrams of a zoom lens according to another embodiment of the present invention at a wide-angle end and a telephoto end. Referring to fig. 2A and 2B, the zoom lens 200a of the present embodiment has the same structure and advantages as the zoom lens 200 of the present embodiment, and therefore the same portions of the

zoom lenses

200 and 200a are not repeated in the present embodiment. The difference between the zoom lens 200a of the present embodiment and the zoom lens 200 is that in the zoom lens 200a of the present embodiment, the second lens group 220a further includes a tenth lens 224 with negative refractive power, and the tenth lens 224 is disposed between the seventh lens 223 of the second lens group 220a and the eighth lens 231 of the third lens group 230 a. In the present embodiment, the tenth lens 224 constitutes a cemented lens with, for example, the sixth lens 222 and the seventh lens 223. An example of the parameters of the zoom lens 200a will be described below, with reference to table four, table five, and table six.

(watch four)

(watch five)

	Wide angle end	Telescope end
			Variable spacing E	10.89	1.41
Variable spacing F	6.73	0.09
			Variable pitch G	0.17	0.34
Variable pitch H	3.66	10.12

In table four, the surfaces S1, S2 are both surfaces of the first lens 211, and the surfaces S3, S4 are both surfaces of the second lens 212. The third lens 213 and the fourth lens 214 are combined to form a cemented lens, for example, the surface S5 is a surface of the third lens 213, the surface S6 is a surface of the third lens 213 cemented with the fourth lens 214, and the surface S7 is another surface of the fourth lens 214. The surface S8 is the aperture stop 240, and the surfaces S9, S10 are both surfaces of the fifth lens 221. The sixth lens 222, the seventh lens 223, and the tenth lens 224 are, for example, combined into a cemented lens, so that the surface S11 is a surface of the sixth lens 222, the surface S12 is a surface of the sixth lens 222 cemented with the seventh lens 223, the surface S13 is a surface of the seventh lens 223 cemented with the tenth lens 224, and the surface S14 is another surface of the tenth lens 224. The surfaces S15 and S16 are both surfaces of the eighth lens 231, the surfaces S17 and S18 are both surfaces of the ninth lens 232, and the surface S19 is a surface on the image side.

In the present embodiment, the surfaces S7, S8, S14, and S18 are variable pitches, and specifically, as shown in table five, the pitch of the surface S7 at the wide-angle end is 10.89 millimeters (mm), the pitch at the telephoto end is 1.41 mm, the pitch of the surface S8 at the wide-angle end is 6.73 mm, the pitch at the telephoto end is 0.09 mm, the pitch of the surface S14 at the wide-angle end is 0.17 mm, the pitch at the telephoto end is 0.34 mm, the pitch of the surface S18 at the wide-angle end is 3.66 mm, and the pitch at the telephoto end is 10.12 mm.

Similar to the zoom lens 200, the second lens group 220a and the third lens group 230a include at least one aspheric lens for eliminating the aberration caused by the large aperture. For example, the second lens group 220a and the third lens group 230a include two aspheric lenses, i.e., a fifth lens 221 and a ninth lens 232. The surfaces S9 and S10 of the fifth lens 221 and the surfaces S17 and S18 of the ninth lens 232 conform to the aspheric formula, and the detailed numerical values of aspheric coefficients such as C2, C4, C6, C8, C10.

(watch six)

	S9	S10	S17	S18
					k	0	0	0	0
C2	0	0	0	0
					C4	-0.00061307	-0.00015649	-0.00199597	-0.00055566
C6	-3.3316E-05	-3.4643E-06	-7.969E-06	0.00011004
					C8	3.05887E-06	-2.3608E-07	-1.034E-05	-3.5693E-05
C10	-3.1668E-07	-1.746E-07	-1.4866E-06	8.6798E-07

The zoom lens 200a of the present embodiment has advantages similar to those of the zoom lens 200 of the previous embodiment of the present invention, and therefore, will not be repeated here.

Fig. 3A and 3B are schematic diagrams of a zoom lens according to still another embodiment of the invention at a wide-angle end and a telephoto end. Referring to fig. 3A and 3B, the zoom lens 200B of the present embodiment has the same structure and advantages as the zoom lens 200a, so the same portions of the zoom lenses 200a and 200B will not be repeated in the present embodiment, and only the differences will be described. In the present embodiment, in order to make the zoom lens 200b achieve the confocal effect of visible light and infrared light, the second lens group 220b and the third lens group 230b include at least one lens with an abbe number greater than 35 and a positive refractive power. For example, abbe numbers of the fifth lens 221, the seventh lens 223, and the ninth lens 232 are, for example, greater than 35.

An example of the parameters of the zoom lens 200b is shown below, with reference to table seven, table eight, and table nine.

(watch seven)

(watch eight)

	Wide angle end	Telescope end
			Variable pitch I	29.02	2.46
Variable pitch J	9.85	0.10
			Variable spacing K	0.77	0.55
Variable pitch L	6.75	16.73

In table seven, the surfaces S1, S2 are both surfaces of the first lens 211, and the surfaces S3, S4 are both surfaces of the second lens 212. The third lens 213 and the fourth lens 214 are combined to form a cemented lens, for example, the surface S5 is a surface of the third lens 213, the surface S6 is a surface of the third lens 213 cemented with the fourth lens 214, and the surface S7 is another surface of the fourth lens 214. The surface S8 is the aperture stop 240, and the surfaces S9, S10 are both surfaces of the fifth lens 221. The sixth lens 222, the seventh lens 223, and the tenth lens 224 are, for example, combined into a cemented lens, so that the surface S11 is a surface of the sixth lens 222, the surface S12 is a surface of the sixth lens 222 cemented with the seventh lens 223, the surface S13 is a surface of the seventh lens 223 cemented with the tenth lens 224, and the surface S14 is another surface of the tenth lens 224. The surfaces S15 and S16 are both surfaces of the eighth lens 231, the surfaces S17 and S18 are both surfaces of the ninth lens 232, and the surface S19 is a surface on the image side.

In the present embodiment, the surfaces S7, S8, S14, and S18 are variable pitches, and specifically, as shown in table eight, the pitch of the surface S7 at the wide-angle end is 29.02 millimeters (mm), the pitch at the telephoto end is 2.46 mm, the pitch of the surface S8 at the wide-angle end is 9.85 mm, the pitch at the telephoto end is 0.10 mm, the pitch of the surface S14 at the wide-angle end is 0.77 mm, the pitch at the telephoto end is 0.55 mm, the pitch of the surface S18 at the wide-angle end is 6.75 mm, and the pitch at the telephoto end is 16.73 mm.

In the present embodiment, the fifth lens 221 and the ninth lens 232 are aspheric lenses, the surfaces S9 and S10 of the fifth lens 221 and the surfaces S17 and S18 of the ninth lens 232 conform to the aspheric formula, and the detailed values of the aspheric coefficients of C2, C4, C6, C8, C10.

(watch nine)

	S9	S10	S17	S18
					k	0	0	0	0
C2	0	0	0	0
					C4	-2.9130E-05	6.7755E-05	-3.1864E-04	-7.7748E-05
C6	9.7061E-08	2.0751E-07	-1.0504E-05	-6.3683E-05
					C8	-2.7719E-09	5.8169E-09	2.8871E-07	1.1704E-07
C10	8.8231E-11	-1.7519E-11	-1.8002E-08	-7.3918E-09

The zoom lens 200b of the present embodiment has advantages similar to those of the zoom lens 200a described above, and therefore, will not be described again here.

FIG. 4 is a schematic diagram of a zoom lens according to another embodiment of the present invention. Referring to fig. 4, the zoom lens 300 includes a first lens group 310, a second lens group 320, a third lens group 330, an aperture stop 340, a focusing ring 360, a zoom ring 370 and a lens barrel 380, wherein the first lens group 310 is disposed in the focusing ring 360, and the first lens group 310 is driven by the focusing ring 360. The second lens group 320 and the third lens group 330 are disposed in the zoom ring 370, the second lens group 320 and the third lens group 330 are driven by the zoom ring 370, and the aperture stop 340 is located between the focusing ring 360 and the zoom ring 370. Focus ring 360, aperture stop 340, and zoom ring 370 are disposed within barrel 380. The first lens group 310, the second lens group 320 and the third lens group 330 may be the first lens group, the second lens group and the third lens group of the zoom lens according to any of the above embodiments. When focusing is to be performed, the focusing ring 360 may be adjusted. When zooming is to be performed, the zoom ring 370 may be adjusted.

In summary, the zoom lens of the present invention adopts a structure of three lens groups, and the fixed aperture stop is disposed between the first lens group and the second lens group, so as to have good imaging quality at the telephoto end, the wide-angle end and the middle position. In addition, compared with the conventional zoom lens with four groups of lenses, the zoom lens of the invention is beneficial to reducing the production cost because the number of the lens groups is less. In addition, the Abbe number of at least one lens with positive diopter in the second lens group and the third lens group is larger than 35 and even larger than 45, so that the zoom lens can achieve the confocal effect of visible light and infrared light. Moreover, at least one aspheric lens in the second lens group and the third lens group can eliminate the aberration caused by large aperture. The zoom lens can reach f/1.2 large aperture and is more convenient to use.

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A zoom lens, comprising a first lens, a second lens, a doublet, a third lens, a fourth lens, a fifth lens, a sixth lens and an aperture stop, wherein the aperture stop is disposed between the second lens and the third lens, the first lens is closest to an object side, a radius of a surface of the first lens facing the object side is D1, a radius of a surface of the sixth lens away from the object side is D2, and D1/D2 is greater than 3.77, when the zoom lens is zoomed, the aperture stop is fixed, the first lens, the second lens and the cemented lens move toward the aperture stop, and a variable distance is provided between the fourth lens and the fifth lens, wherein all the lenses between the object side and the aperture stop constitute a lens group having negative refractive power, all the lenses between the aperture stop and the variable pitch constitute a lens group having a positive refractive power, all the lenses at the other end of the variable pitch constitute a lens group having a positive refractive power, and one of the third lens, the fourth lens, the fifth lens, and the sixth lens is an aspherical lens.

2. The zoom lens according to claim 1, wherein a surface of the first lens facing the object side is a convex surface.

3. The zoom lens according to any one of claims 1 to 2, wherein at least two of the third lens, the fourth lens, the fifth lens, and the sixth lens are lenses having an abbe number greater than 80 and having a positive refractive power.

4. A zoom lens according to any one of claims 1 to 2, comprising at least two lenses having an abbe number greater than 80.

5. The zoom lens according to any one of claims 1 to 2, wherein the third lens, the fourth lens, the fifth lens, and the sixth lens are moved toward the aperture stop when the zoom lens is zoomed.

6. The zoom lens according to any one of claims 1 to 2, wherein the first lens is a negative refractive power, the second lens is a negative refractive power, the double cemented lens is composed of lenses of a negative refractive power and a positive refractive power, the third lens is a negative refractive power, the fourth lens is a positive refractive power, the fifth lens is a negative refractive power, and the sixth lens is a positive refractive power.

7. The zoom lens according to any one of claims 1 to 2, further comprising a seventh lens between the aperture stop and the variable pitch, wherein the third lens, the fourth lens and the seventh lens constitute a triple cemented lens, and an abbe number of a lens in the middle of the triple cemented lens is larger than abbe numbers of lenses on both sides of the triple cemented lens.

8. The zoom lens of claim 7, wherein the seventh lens is of positive refractive power.

9. The zoom lens of claim 7, further comprising an eighth lens between the aperture stop and the third lens, the eighth lens having a positive refractive power.