CN102998780A - zoom lens - Google Patents

Abstract

The invention relates to a zoom lens which sequentially comprises a first lens group with negative diopter, a second lens group with positive diopter and a third lens group with positive diopter from an object side to an image side. The second lens group comprises a plurality of lenses, wherein the focal length of the lens closest to the object side is efl3, the focal length of the lens next to the object side is efl4, and efl3 and efl4 satisfy: 0 < efl3/efl4 < 0.3.

Description

Zoom lens

Technical field

The present invention relates to a kind of zoom lens, particularly relate to a kind of lightening, cost is low, high magnification and the good zoom lens of image quality.

Background technology

Image capture unit, for example digital camera or digital camera, usually capture the image of thing to be taken the photograph by camera lens module and image sensor, wherein camera lens module makes the light beam generation from thing to be taken the photograph reflect and be gathered on the image sensor, then image sensor is converted to digital electronic signal with the light signal of analogy, in order to carry out follow-up image processing, storage and transmission.The camera lens module of image capture unit normally is comprised of several lens groups (lens group), and the lens group number is fewer usually, and the cost of camera lens module is lower, size is less.In addition, for cost and the weight that reduces eyeglass, can utilize as far as possible the plastic cement lens to replace glass lens.Yet, the easy temperature influence of plastic cement lens, when adjusting focal length, for temperature compensation must have larger displacement, thereby the size of increase camera lens module.In addition, if use more plastic cement lens, image quality possibly can't reach requirement.

In view of this, having needs to propose a kind of new zoom lens, can satisfy simultaneously low-cost, lightening, as to reach high image quality requirement.

Summary of the invention

The object of the invention is to propose a kind of zoom lens, reducing under the prerequisite of manufacturing cost, realize simultaneously the zoom lens of lightening, high magnification, high image quality.

The object of the invention to solve the technical problems realizes by the following technical solutions.A kind of zoom lens according to the present invention proposes extremely sequentially comprises as side from the thing side: one has negative dioptric first lens group; One has the second lens group of positive diopter, comprises at least a first lens and one second lens, and the focal length of wherein said first lens is efl3, and the focal length of described the second lens is efl4, and efl3 and ef4 satisfy: 0＜efl3/efl4＜0.3; And the 3rd lens group with positive diopter.

The object of the invention to solve the technical problems also can be applied to the following technical measures to achieve further.

Aforesaid zoom lens, the Abbe number of the described first lens of wherein said the second lens group are VD3, and the Abbe number of described the second lens is VD4, and VD3 and VD4 meet the following conditions: VD3-VD4＞6.

Aforesaid zoom lens, wherein said zoom lens satisfy: 4＜ft/fw＜5, wherein, fw be described zoom lens in the focal length of wide-angle side, and ft is that described zoom lens is in the focal length of telescope end.

Aforesaid zoom lens, wherein said zoom lens also satisfy: | fG1/fG2|＞1, wherein, fG1 is described first lens group's focal length, fG2 is the focal length of described the second lens group.

Aforesaid zoom lens, wherein said first lens group, described the second lens group, described the 3rd lens group respectively comprise at least one non-spherical lens or a free-form surface lens.

Aforesaid zoom lens, wherein said first lens group, described the second lens group, described the 3rd lens group respectively comprise at least one plastic cement lens.

Aforesaid zoom lens, wherein said first lens group has the second lens that negative dioptric first lens and has positive diopter from the thing side to sequentially comprise one as side.

Aforesaid zoom lens, described the second lens of wherein said first lens group are a non-spherical lens or a free-form surface lens, and the material of described first lens is glass, the material of described the second lens is plastic cement.

Aforesaid zoom lens, the thing side surface of wherein said first lens has the negative value radius-of-curvature.

Aforesaid zoom lens, to sequentially comprise a first lens with positive diopter as side, one has the second lens of positive diopter to wherein said the second lens group from the thing side, and one has negative dioptric the 3rd lens.

Aforesaid zoom lens, described the second lens and described the 3rd lens of wherein said the second lens group are non-spherical lens or free-form surface lens, and the material of described first lens is glass, the material of described the second lens and described the 3rd lens is plastic cement.

Aforesaid zoom lens, wherein said the 3rd lens group comprise a first lens with positive diopter, and the described first lens of described the 3rd lens group is a non-spherical lens or a free-form surface lens, and the material of described first lens is plastic cement.

Aforesaid zoom lens, it more comprises a diaphragm, and described diaphragm is arranged between described first lens group and described the second lens group.

Aforesaid zoom lens, wherein said first lens is than the more close thing side of described the second lens.

The present invention compared with prior art has obvious advantage and beneficial effect.By technique scheme, zoom lens of the present invention has following advantages and beneficial effect at least: zoom lens of the present invention, not only realize to reduce cost and lightening purpose, the zoom lens that its image quality of while can be compared and is made of glass lens.

Above-mentioned explanation only is the general introduction of technical solution of the present invention, for can clearer understanding technological means of the present invention, and can be implemented according to the content of instructions, and for above and other purpose of the present invention, feature and advantage can be become apparent, below especially exemplified by preferred embodiment, and the cooperation accompanying drawing, be described in detail as follows.

Description of drawings

Fig. 1 shows the position of zoom lens ZL each lens when telescope end and wide-angle side of preferred embodiment of the present invention.

Fig. 2 A and Fig. 2 B show respectively the zoom lens of preferred embodiment of the present invention, with the spherical aberration curve of wavelength 587nm test light beam in wide-angle side and telescope end.

Fig. 3 A and Fig. 3 B show respectively the zoom lens of preferred embodiment of the present invention, with the curvature of field curve of wavelength 587nm test light beam in wide-angle side and telescope end.

Fig. 4 A and Fig. 4 B show respectively the zoom lens of preferred embodiment of the present invention, with wavelength 587nm test light beam in the distortion curve of wide-angle side and telescope end.

Embodiment

Each embodiment of this case below will be described in detail in detail, and cooperate graphic as illustration.Except these were described in detail, the present invention can also be implemented among other the embodiment widely, the substituting easily of any described embodiment, revise, equivalence changes and is included in the scope of this case, and with after claim be as the criterion.In the description of instructions, in order to make the reader the present invention there is more complete understanding, many specific detail are provided; Yet the present invention may at clipped or all under the prerequisite of these specific detail, still can implement.In addition, well-known step or element are not described in the details, with the restriction of avoiding causing the present invention unnecessary.Identical or similar element will represent with identical or simileys in graphic.What pay special attention to is, graphicly only is the usefulness of signal, is not size or the quantity of representation element reality, unless otherwise specified.

For reach lightening, cost is low, the requirement of high magnification, high image quality, the embodiment of the invention provides a kind of zoom lens, it has the second lens group that negative dioptric first lens group, has positive diopter from the thing side to sequentially comprise one as side, and the 3rd lens group with positive diopter.Each lens group respectively comprises at least one lens, and preferably, this first lens group and this second lens group relatively move on an optical axis, to determine an enlargement ratio of this zoom lens.

In addition, this second lens group comprises a plurality of lens, and wherein the focal length of the lens of the most close thing side is efl3, and the focal length of inferior lens near the thing side is efl4, and efl3 is satisfied with efl4: 0＜efl3/efl4＜0.3.When meeting above-mentioned condition, can reduce lens, particularly the plastic cement lens make the temperature compensation displacement that reduces lens for the susceptibility of temperature, therefore reach the purpose of size downsizing.

In addition, preferably, in a plurality of lens of this second lens group, the Abbe number of the lens of the most close thing side (Abbe number) is VD3, and the Abbe number of inferior lens near the thing side is VD4, and VD3 and VD4 meet the following conditions: VD3-VD4＞6.At another embodiment, VD3 and VD4 satisfy: VD3-VD4＞23.

In addition, this enlargement ratio has a maximal value ft/fw, wherein ft be this zoom lens in the focal length of telescope end, fw be this zoom lens in the focal distance f w of wide-angle side, and ft/fw satisfies following condition: 4＜ft/fw＜5.

In addition, preferably, this zoom lens also satisfies: | fG1/fG2|＞1, wherein, fG1 is this first lens group's focal length, fG2 is the focal length of this second lens group.

In addition, preferably, this first lens group comprises a plurality of lens, the lens of the most close thing side wherein, and its radius-of-curvature towards the thing side surface is negative value, so can further reduce the overall length of zoom lens.

In addition, when zoom lens need to change its whole focal length, each lens group can move along optical axis, to adjust enlargement ratio, adjusting focal length skew.Preferably, when zoom lens changes multiplying power by wide-angle side to telescope end, first lens group and the second lens group move towards the thing side direction, and wherein the first lens group is first towards moving as lateral deviation, move towards the thing side direction, and the second lens group can move towards the thing side direction to constant speed.In addition, the 3rd lens also can be mobile a little along person's optical axis, with the compensation focus offset.

In addition, each lens group respectively comprises at least one non-spherical lens or a free-form surface lens, and its material can be plastic cement or glass; Wherein, plastic cement material can comprise, but is not restricted to, and polycarbonate (polycarbonate), cyclic olefine copolymer for example are APEL, and vibrin, such as OKP4 or OKP4HT etc.Particularly, glass lens be glass take optical grade as material, utilize grinding and polishing or glass moulding processing procedure (glass molding process, GMP) to make, and the plastic cement lens can be to utilize the polymkeric substance ejection formation to make.In addition, each free-form surface lens has at least one continuous smooth surface (free-form freedom surface), and each non-spherical lens has at least one non-spherical surface, and this non-spherical surface satisfies following mathematical expression:

$Z=\frac{{\mathrm{CY}}^2}{1+\sqrt{1-(K+1)C^2{\mathrm{<figure-callout\; id="2"\; label="Y"\; filenames="HSA00000575074600042.png"\; state="\{\{state\}\}">Y</figure-callout>}}^2}}+A_4{Y}^4+A_6{Y}^6+A_8{Y}^8+A_{10}{\mathrm{<figure-callout\; id="10"\; label="Y"\; filenames="HSA00000575074600041.png"\; state="\{\{state\}\}">Y</figure-callout>}}^{10}+A_{12}{Y}^{12},$

Wherein Z is the coordinate figure in optical axis OA direction, take optical transmission direction as positive dirction, and A ₄, A ₆, A ₈, A ₁₀And A ₁₂Be asphericity coefficient, K is the quadric surface constant, and C=1/R, R are radius-of-curvature, and Y is the coordinate figure that is orthogonal to optical axis direction, take the top as positive dirction.In addition, the parameters of the aspheric surface mathematical expression of each non-spherical lens or the value of coefficient can be set respectively, to determine the focal length of each non-spherical lens.

The zoom lens of the embodiment of the invention can be applicable to have on the device of image projecting or acquisition function, for example, and digital camera, digital camera, mobile phone, or projector.

Below with an embodiment zoom lens of the present invention is described.

Fig. 1 shows the position of zoom lens ZL each lens when telescope end (tele) and wide-angle side (wide) of preferred embodiment of the present invention.In the present embodiment, zoom lens ZL mainly comprises, and to the picture side, has the second lens group G2 that bears dioptric first lens group G1, has positive diopter, the 3rd lens group G3 with positive diopter from the thing side.These three lens groups arrange along optical axis OA, and in have imaging surface I as side.In addition, zoom lens ZL can comprise diaphragm S and optical filter F.Diaphragm S can be arranged between first lens group G1 and the second lens group G2, enters the luminous flux of the second lens group G2 in order to the light beam of restricted passage first lens group G1; Optical filter F can be arranged between the 3rd lens group G3 and the imaging surface I, and in order to the invisible light in the filtering light beam, wherein optical filter F can be an infrared filter.In addition, on the imaging surface I image acquisition unit can be set, penetrate the light beam of optical filter F with reception, and convert the light anaiog signal to electric digital signal.In addition, between imaging surface I and optical filter F, more can increase planar optics (not shown), in order to protect image acquisition unit.

In the present embodiment, sequentially extremely look like side from the thing side, first lens group G1 comprises the second lens L12 that has negative dioptric first lens L11, has positive diopter; The second lens group G2 comprises first lens L21, the second lens L22 with positive diopter with positive diopter, has negative dioptric the 3rd lens L23; The 3rd lens group G3 comprises the first lens L31 with positive diopter.Zoom lens ZL of the present invention can be not limited to said structure.

In addition, the second lens L12 of first lens group G1, the second lens L22 of the second lens group G2 and the 3rd lens L23, and the first lens L31 of the 3rd lens group G3, can adopt two surfaces to be the free-form surface lens that aspheric non-spherical lens or two surfaces are free form surface, or one the surface be aspheric surface another the surface be that the lens of free form surface, all the other lens can adopt the two sides to be glass lens or the plastic cement lens of sphere.In the present embodiment, the second lens L12, the second lens L22, the 3rd lens L23, first lens L31 are the plastic cement lens, and all the other lens are glass lens.

Table one is listed the particulars according to this preferred embodiment zoom lens, and it comprises radius-of-curvature, thickness, refractive index, Abbe number, focal length (focal length, effective focal length) of each lens etc.Wherein the surperficial code name of eyeglass is to the sequentially layout of picture side from the thing side, for example: " S1 " represents first lens L11 towards the surface of thing side, and " S2 " represents first lens L11 and represent the second lens L12 towards surface, " S3 " of picture side and represent diaphragm surface etc. towards surface, " S " of thing side.In this example, the focal length of the first lens L21 of the second lens group is that the focal length of 7.98, the second lens is 60, and both ratio meets aforementioned definitions: 0＜efl3/efl4＜0.3.At another embodiment, the value of efl3/efl4 can be less than 0.145.

Table one

In addition, " thickness " represents this surface and adjacent to the distance as side one surface, for example, " thickness " of surperficial S1 is the distance of surperficial S1 and surperficial S2, and " thickness " of surperficial S2 is the distance of surperficial S2 and surperficial S3.If one-tenth-value thickness 1/10 is denoted as " D1 " " D2 " " D3 ", and different, its distance as shown in Table 2 according to wide-angle side and telescope end for the distance that represents two surfaces.

Table two

Thickness	Wide-angle side (mm)	Telescope end (mm)
			D1	16	1.1
D2	2.811	22.332
			D3	4.012	2.3

In addition, table three lists such as the zoom lens of table one example focal distance f, f-number FNO, visual angle half-angle ω (half angle view), image height Y and the total lens length TL respectively at wide-angle side and telescope end.

Table three

Parameter	Wide-angle side	Telescope end
			F(mm)	4.67	22.65
FNO	3.5	6.6
			ω(°)	43.64	10.13
Y(mm)	3.5	3.875
			TL(mm)	33.2	42.2

In addition, in Table 1, the surface of surperficial code name " S3 " " S4 " " S7 " " S8 " " S09 " " S10 " " S11 " " S12 " is aspheric surface, and the every coefficient in its aspheric surface mathematical expression as shown in Table 4.

Table four

K

A 4

A 6

A 8

A 10

A 12

S3

0

-0.00041

-2.13E-05

2.84E-06

-5.69E-08

0

S4

0

-0.00079

-6.62-06

2.18E-06

-5.90E-08

0

S7

0

-0.00166

-9.60E-05

-7.06E-06

7.36E-07

0

S8

0

-0.00384

1.32E-03

-2.25E-04

1.67E-05

0

S09

0

-0.00587

1.74E-03

-3.16E-04

1.86E-05

0

S10

0

-0.00369

6.50E-04

-1.90E-04

5.53E-06

0

S11

0

-2.29E-05

1.38E-05

1.01E-06

-1.73E-08

0

S12

0

0.000249

-1.18E-05

2.45E-06

-4.46E-08

0

Fig. 2 A and Fig. 2 B show respectively the zoom lens such as table one example, with spherical aberration (the longitudinal spherical aberration) curve of wavelength 587nm test light beam in wide-angle side and telescope end.Be shown in the spherical aberration of wide-angle side among the figure less than 0.03mm, the spherical aberration of telescope end is controlled in (0.035mm, 0.03mm) scope.

Fig. 3 A and Fig. 3 B show respectively the zoom lens such as table one example, with the curvature of field (field curvature) curve of wavelength 587nm test light beam in wide-angle side and telescope end.Wherein, curve T, S are respectively that zoom lens is for the curvature of field value of tangent light beam (Tangential Rays) with sagittal beam (Sagittal Rays).The tangent curvature of field value and the Sagittal field curvature value that are shown in wide-angle side among the figure are controlled in (0.15mm, 0.05mm) scope, and the tangent curvature of field value of telescope end and Sagittal field curvature value all are controlled in (0.1mm, 0.02mm) scope.

Fig. 4 A and Fig. 4 B show respectively the zoom lens such as table one example, with distortion (distortion) curve of wavelength 587nm test light beam in wide-angle side and telescope end.The aberration rate that is shown in wide-angle side among the figure is controlled in (20%, 0%) scope, and the aberration rate of telescope end is controlled in (1.3%, 0.2%) scope.

More than, the zoom lens of preferred embodiment of the present invention is using under the condition that reaches four plastic cement lens the characteristics such as its spherical aberration, the curvature of field and distortion, the camera lens that can compare and be made of glass lens.Therefore, the zoom lens of the embodiment of the invention, under the condition of keeping high magnification and high image quality, further weight reduction and reduction cost.

The above, it only is preferred embodiment of the present invention, be not that the present invention is done any pro forma restriction, although the present invention discloses as above with preferred embodiment, yet be not to limit the present invention, any those skilled in the art, within not breaking away from the technical solution of the present invention scope, when the technology contents that can utilize above-mentioned announcement is made a little change or is modified to the equivalent embodiment of equivalent variations, in every case be the content that does not break away from technical solution of the present invention, any simple modification that foundation technical spirit of the present invention is done above embodiment, equivalent variations and modification all still belong in the scope of technical solution of the present invention.

Claims (14)

1. A zoom lens is characterized in that it comprises sequentially from the object side to the image side: a first lens group with negative diopter; A second lens group with positive diopter at least includes a first lens and a second lens, wherein the focal length of the first lens is efl3, the focal length of the second lens is efl4, and efl3 and efl4 satisfy: 0 <efl3/efl4<0.3; and A third lens group with positive diopter. 2. The zoom lens according to claim 1, wherein the Abbe number of the first lens of the second lens group is VD3, the Abbe number of the second lens is VD4, and VD3 and VD4 Satisfy the following condition: VD3-VD4>6. 3. The zoom lens according to claim 1, wherein the zoom lens satisfies: 4<ft/fw<5, wherein fw is the focal length of the zoom lens at the wide-angle end, and ft is the focal length of the zoom lens at the wide-angle end. The focal length at the telephoto end. 4. The zoom lens according to claim 1, wherein the zoom lens also satisfies: |fG1/fG2|>1, wherein fG1 is the focal length of the first lens group, and fG2 is the second lens group The focal length of the group. 5 . The zoom lens according to claim 1 , wherein the first lens group, the second lens group, and the third lens group each comprise at least one aspherical lens or a free-form surface lens. 6 . The zoom lens according to claim 1 , wherein each of the first lens group, the second lens group, and the third lens group includes at least one plastic lens. 7 . The zoom lens according to claim 6 , wherein the first lens group sequentially includes a first lens with negative diopter and a second lens with positive diopter from the object side to the image side. 8. The zoom lens according to claim 7, wherein the second lens of the first lens group is an aspherical lens or a free-form surface lens, and the material of the first lens is glass, so The material of the second lens is plastic. 9. The zoom lens according to claim 7, wherein the object-side surface of the first lens has a negative curvature radius. 10. The zoom lens according to claim 6, wherein the second lens group comprises a first lens with positive diopter, a second lens with positive diopter, and a Third lens with negative diopter. 11. The zoom lens according to claim 10, wherein the second lens and the third lens of the second lens group are aspheric lenses or free-form lenses, and the material of the first lens is Glass, the material of the second lens and the third lens is plastic. 12. The zoom lens according to claim 6, wherein the third lens group comprises a first lens with positive diopter, and the first lens of the third lens group is a plastic aspheric surface lens or a plastic free-form surface lens. 13. The zoom lens according to claim 1, further comprising a stop, the stop is disposed between the first lens group and the second lens group. 14. The zoom lens according to claim 1 or 2, wherein the first lens is closer to the object side than the second lens.

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