CN100424537C - Zoom lens - Google Patents

Abstract

The related lens with high variable-focus rate and small size comprises: a front group, which includes a negative falcate lens, a biconcave negative lens and a positive third lens; and a back group, which includes a positive fourth lens, a fifth biconvex lens, and a sixth/seventh negative falcate lens. Wherein, the fourth and seventh lenses are aspheric lens made of plastic material.

Description

Zoom lens

Technical field

The present invention relates to a kind of zoom lens, relate in particular to a kind of anti-burnt type zoom lens that is used in two group-wises of solid-state module, this zoom lens for example can be used in compact image extraction element, for example video camera, digital camera etc.

Background technology

In recent years, image acquiring apparatus is toward the development of demand of miniaturization, and wherein zoom lens is very crucial assembly.Therefore zoom lens is actively towards reduced volume, weight and cost development, so that image acquiring apparatus reduces volume, weight and cost accordingly.

In the prior art, in the zoom lens design of camera, basically can be divided into two big classes about two group-wise zoom lens, the first kind is the type of dolly-out,ing dolly-back (telephoto type) combination, this kind zoom lens is born two group's camera lenses that dioptric back group combines for the preceding group with positive diopter (diopter) with having, utilize the airspace that changes between two groups to change focal length, characteristics are when principal plane is toward reach after making camera lens, can obtain short back focal length degree.

Second class is anti-burnt type (retrofocus type), two group's camera lenses that this kind of combines for preceding group with negative diopter (diopter) and the back group with positive diopter.Zoom lens about two group-wises is the United States Patent (USP) of US5179473 just like the patent No., this patent is anti-burnt type zoom lens, but its zoom ratio (zoom ratio) can't surpass 2, can only reach 1.8, therefore can't satisfy the property development requirement of the high zoom ratios of recent image acquiring apparatus.

Another is that the United States Patent (USP) and the patent No. of US5155629 is the United States Patent (USP) of US4750820 just like the patent No. also about the zoom lens of anti-burnt type, yet the patent No. is the zoom lens compact in size reference value of the United States Patent (USP) of US5155629, and promptly zoom system, pancreatic system total length (total track of zoom system) and image sensor size (image sensor size) are than approximating 10 greatly.The patent No. is that the compact in size reference value of the United States Patent (USP) of US4750820 also can surpass 16 in addition.Moreover the above-mentioned patent No. is that the compact in size reference value of the United States Patent (USP) of US5179473 also reaches 14.Because the size of zoom lens can be subjected to the influence of image sensor size usually consumingly, so zoom system, pancreatic system total length and image sensor size are than being the crucial reference value that the zoom lens size is wanted miniaturization.This reference value heals better little.

Therefore the present invention is directed to the defective of above-mentioned prior art, provide a kind of zoom lens to solve the above problems.

Summary of the invention

The object of the present invention is to provide a kind of zoom lens, it has high zoom ratios and has the miniaturization volume simultaneously, promptly reduces the volume of image acquiring apparatus.

Another object of the present invention is to provide a kind of zoom lens, its aspherical lens and general glass mirror commonly used of being made by plastic material is formed, and can reach purpose with low cost.The present invention simultaneously has simple in structure, easy-to-assemble advantage.

For achieving the above object, the invention provides a kind of zoom lens, it includes the eyeglass of a preceding group and a back group, should preceding group include: first eyeglass, it is a negative meniscus, second eyeglass, it is a double-concave negative lens, and prismatic glasses, and it is a positive lens; This back group includes: the 4th eyeglass, it is a positive lens, the 5th eyeglass, it is a biconvex lens, the 6th eyeglass, and it is a negative meniscus, and the 7th eyeglass, it is a negative meniscus, and wherein the 4th eyeglass and the 7th eyeglass are the non-spherical eyeglass made from plastic material, and this zoom lens meets following condition:

Condition (a): 1.42＜d ₁₂/

＜1.73

Condition (b): 1.20＜e ₁₃/ d ₁₃＜1.36

Condition (c): 1.2＜f ₂/ f _w＜1.3

Wherein, d ₁₂It is the axial distance of the 6th eyeglass and the 7th eyeglass;

It is the 6th eyeglass radial height;

e ₁₃Be the outer edge thickness of the 7th eyeglass, d ₁₃Be the 7th center of lens thickness;

f ₂Be the focal length of back group, f _wFocal length during for wide viewing angle.

According to technical scheme of the present invention, glue-bondable one-tenth one balsaming lens of the 5th eyeglass and the 6th eyeglass wherein.

According to technical scheme of the present invention, wherein this zoom lens also meets following condition (d):

0.28＜(n ₁₀-n ₁₁) absolute value＜0.31, wherein,

n ₁₀Be the refractive index of the 5th eyeglass, n ₁₁It is the refractive index of the 6th eyeglass.

According to technical scheme of the present invention, wherein this zoom lens also meets following condition (e):

1.49＜n ₈＜1.53, n wherein ₈It is the refractive index of the 4th eyeglass.

According to technical scheme of the present invention, wherein this zoom lens also meets following condition (f):

1.52＜n ₁₃＜1.59, n wherein ₁₃It is the refractive index of the 7th eyeglass.

According to technical scheme of the present invention, wherein this zoom lens also meets following condition (g):

56＜v ₈＜58, v wherein ₈It is Abbe (abbe) value of the 4th eyeglass.

According to technical scheme of the present invention, wherein this zoom lens also meets following condition (h):

29＜v ₁₃＜57, v wherein ₁₃It is the Abbe number of the 7th eyeglass.

According to technical scheme of the present invention, wherein this zoom lens also meets following condition:

1.49＜n ₈＜1.53, n wherein ₈It is the refractive index of the 4th eyeglass;

1.52＜n ₁₃＜1.59, n wherein ₁₃It is the refractive index of the 7th eyeglass;

56＜v ₈＜58, v wherein ₈It is the Abbe number of the 4th eyeglass; And

29＜v ₁₃＜57, v wherein ₁₃It is the Abbe number of the 7th eyeglass.

Beneficial effect of the present invention and characteristics are:

One, zoom lens of the present invention has high zoom ratios (reach 2.87, be better than prior art), and simultaneously, and its miniaturization reference value is little of 8.84 all far below prior art, can effectively save the space and reduce the volume of image acquiring apparatus.

Two, the 4th eyeglass L4 and the 7th eyeglass L7 are the non-spherical eyeglasses made from plastic material among the present invention, and other eyeglass can use general glass mirror commonly used.The aberration of the optical module of non-spheroidal mirror in can compensation optical system reduces cost, and weight reduction, so the present invention also has advantage with low cost.

Three, glue-bondable one-tenth one balsaming lens of the 5th eyeglass L5 and the 6th eyeglass L6 among the present invention can simplify the number of assembling steps of zoom lens whereby, reaches the advantage of easy assembling.

Description of drawings

Fig. 1 is the configuration schematic diagram of each eyeglass of zoom lens of the present invention.

Fig. 2 A represents the location drawing of embodiment one each lens when wide viewing angle.

Fig. 2 B represents the image curve figure of embodiment one when wide viewing angle.

Fig. 2 C represents the image curve figure of embodiment one when middle visual angle.

Fig. 2 D represents the image curve figure of embodiment one when small angle.

Fig. 3 A represents the location drawing of embodiment two each lens when wide viewing angle.

Fig. 3 B represents the image curve figure of embodiment two when wide viewing angle.

Fig. 3 C represents the image curve figure of embodiment two when middle visual angle.

Fig. 3 D represents the image curve figure of embodiment two when small angle.

Fig. 4 A represents the location drawing of embodiment three each lens when wide viewing angle.

Fig. 4 B represents the image curve figure of embodiment three when wide viewing angle.

Fig. 4 C represents the image curve figure of embodiment three when middle visual angle.

Fig. 4 D represents the image curve figure of embodiment three when small angle.

Fig. 5 A represents the location drawing of embodiment four each lens when wide viewing angle.

Fig. 5 B represents the image curve figure of embodiment four when wide viewing angle.

Fig. 5 C represents the image curve figure of embodiment four when middle visual angle.

Fig. 5 D represents the image curve figure of embodiment four when small angle.

Wherein, description of reference numerals is as follows:

The preceding G1 of group

The first eyeglass L1, the second eyeglass L2

Prismatic glasses L3

The back G2 of group

The 4th eyeglass L4 the 5th eyeglass L5

The 6th eyeglass L6 the 7th eyeglass L7

Axial distance between each minute surface of d1～d18

The minute surface numbering of each lens of S1～S14

Embodiment

See also Fig. 1, it shows the configuration schematic diagram of each eyeglass of zoom lens of the present invention.Zoom lens of the present invention is made up of seven eyeglasses.By in the combining and configuring graph of a relation of each eyeglass shown in the Reference numeral as can be known, zoom lens of the present invention includes the eyeglass of the G1 of group and a back G2 of group before one.Wherein should before the G1 of group have the characteristic of negative diopter (negative diopter, or be called negative power), the G2 of this back group has the characteristic of positive diopter (positive diopter).The variation of formed airspace between group and the back group before utilizing, that is above-mentioned forward and backward group forms the focal length that zoom lens can change this lens combination by the spacing that changes the optical axis direction between group.

In preferred embodiment of the present invention, this preceding G1 of group includes: the first eyeglass L1, and it is a negative meniscus; The second eyeglass L2, it is a double-concave negative lens; And prismatic glasses L3, it is a positive lens.The G2 of this back group includes: the 4th eyeglass L4, and it is a positive lens; The 5th eyeglass L5, it is a biconvex lens; The 6th eyeglass L6, it is a negative meniscus; And the 7th eyeglass L7, it is a negative meniscus.The S that is positioned at the 4th eyeglass L4 the place ahead represents aperture.

The aspherical lens that the 4th eyeglass L4 and the 7th eyeglass L7 preferably make with plastic material among the present invention, other eyeglass then can use general glass mirror commonly used, can effectively reduce the cost of camera whereby, reach purpose with low cost.Yet the present invention still has the characteristics of compact in size and can keep the quality of image.This is because non-spherical eyeglass can effectively be eliminated off-axis aberration, particularly the 7th eyeglass L7.S1～S19 is the minute surface numbering of each lens, and d1～d18 represents the axial distance between each minute surface.

In this preferred embodiment, glue-bondable one-tenth one balsaming lens of the 5th eyeglass and the 6th eyeglass as shown in the figure, only is considered as a minute surface S11 and not apart from d.So can simplify the number of assembling steps of zoom lens, have easy-to-assemble advantage.

The present invention can make this zoom lens meet following condition, that is have following feature in order to realize compact in size and to keep the quality of image:

Condition (a): 1.42＜d ₁₂/

＜1.73;

Condition (b): 1.20＜e ₁₃/ d ₁₃＜1.36;

Condition (c): 1.2＜f ₂/ f _w＜1.3;

D wherein ₁₂It is the axial distance (that is the distance between minute surface S12～S13) of the 6th eyeglass and the 7th eyeglass; It is the radial height of the 6th eyeglass;

e ₁₃It is the outer edge thickness of the 7th eyeglass; d ₁₃It is the center thickness of the 7th eyeglass;

f ₂Focal length for back group; f _wFocal length during for wide viewing angle.

It below is first explanation of the present invention to the 4th embodiment.

＜the first embodiment 〉

Fig. 2 A represents the location drawing of embodiment one each lens when wide viewing angle; Fig. 2 B represents the image curve figure of embodiment one when wide viewing angle; Fig. 2 C represents the image curve figure of embodiment one when middle visual angle; Fig. 2 D represents the image curve figure of embodiment one when small angle.Wherein Fig. 2 A is substantially identical with Fig. 1, and change is a little only arranged on the external form of part eyeglass and distance, and is more succinct for making drawing, omitted the Reference numeral of S1～S19 and d1～d18.The structural drawing of the following example also is identical.

The elementary optical characteristics of embodiment one is Fno=1: 3.65-6.81, f=7.53-21.60, w=29.7 °-11.1 °.Wherein Fno represents the aperture bore corresponding to wide viewing angle and small angle, and f represents the system's focal length corresponding to wide viewing angle and small angle, and w represents the half angle of view corresponding to wide viewing angle and small angle.Its data please refer to following table one, wherein r represents that (unit is millimeter (mm) to each surperficial radius-of-curvature, following examples together), d represents the axial distance (unit is millimeter (mm), and following examples together) between each minute surface, and n represents the refractive index of each minute surface, v represents the Abbe number (abbe value) of each minute surface, Abbe number is the numerical value of chromatic dispersion (chromatic aberration) characteristic of expression material, and Abbe number and dispersion measure are inversely proportional to, and " infinite " represents infinitely great.

＜table one 〉:

In the lens combination, wherein octahedral, the 9th, the 13 and the tenth four sides be aspheric surface, and its asphericity coefficient data is distinguished as follows:

Variable d6 is as follows respectively with respect to the relation of different zoom positions with d14:

Above-mentioned aspheric surface can be expressed as follows at equation radially:

$Z=\frac{\left(\mathrm{curv}\right)Y^2}{1+(1-(1+K){\left(\mathrm{curv}\right)}^2{Y}^2)}+\left(A\right)Y^4+\left(B\right){\mathrm{<figure-callout\; id="6"\; label="Y"\; filenames="C20051009990000181.png"\; state="\{\{state\}\}">Y</figure-callout>}}^6+\left(C\right)Y^8+\left(D\right)Y^{10}$

$+\left(E\right)Y^{12}+\left(F\right){\mathrm{<figure-callout\; id="14"\; label="Y"\; filenames="C20051009990000181.png"\; state="\{\{state\}\}">Y</figure-callout>}}^{14}+\left(G\right)Y^{16}+\left(H\right)Y^{18}+\left(J\right)Y^{20}$

Wherein, the Z value is the prominent amount (sag) that falls into, and curv is a curvature, K is the quadric surface constant, and Y is the height vertical with lens light axis, and A is 4 rank asphericity coefficients, B is 6 rank asphericity coefficients, C is 8 rank asphericity coefficients, and D is 10 rank asphericity coefficients, and E is 12 rank asphericity coefficients, F is 14 rank asphericity coefficients, G is 16 rank asphericity coefficients, and H is 18 rank asphericity coefficients, and J is 20 rank asphericity coefficients.

＜the second embodiment 〉

Fig. 3 A represents the location drawing of embodiment two each lens when wide viewing angle; Fig. 3 B represents the image curve figure of embodiment two when wide viewing angle; Fig. 3 C represents the image curve figure of embodiment two when middle visual angle; Fig. 3 D represents the image curve figure of embodiment two when small angle.

The elementary optical characteristics of embodiment two is Fno=1: 3.65-6.81, f=7.30-20.94, w=30.5 °-11.5 °.Wherein Fno represents the aperture bore corresponding to wide viewing angle and small angle, and f represents the system's focal length corresponding to wide viewing angle and small angle, and w represents the half angle of view corresponding to wide viewing angle and small angle.Its data please refer to following table one, and wherein r represents the radius-of-curvature that each is surperficial, and d represents the axial distance between each minute surface, and n represents the refractive index of each minute surface, and v represents the Abbe number of each minute surface.

＜table two 〉

In the lens combination, wherein octahedral, the 9th, the 13 and the tenth four sides be aspheric surface, and its asphericity coefficient data is distinguished as follows:

Variable d6 is as follows respectively with respect to the relation of different zoom positions with d14:

＜the three embodiment 〉

Fig. 4 A represents the location drawing of embodiment three each lens when wide viewing angle; Fig. 4 B represents the image curve figure of embodiment three when wide viewing angle; Fig. 4 C represents the image curve figure of embodiment three when middle visual angle; Fig. 4 D represents the image curve figure of embodiment three when small angle.

The elementary optical characteristics of embodiment three is Fno=1: 3.65-6.81, f=7.57-21.72, w=29.5 °-11.1 °.Wherein Fno represents the aperture bore corresponding to wide viewing angle and small angle, and f represents the system's focal length corresponding to wide viewing angle and small angle, and w represents the half angle of view corresponding to wide viewing angle and small angle.Its data please refer to following table three, and wherein r represents the radius-of-curvature that each is surperficial, and d represents the axial distance between each minute surface, and n represents the refractive index of each minute surface, and v represents the Abbe number of each minute surface.

＜table three 〉

In the lens combination, wherein octahedral, the 9th, the 13 and the tenth four sides be aspheric surface, and its asphericity coefficient data is distinguished as follows:

Variable d6 is as follows respectively with respect to the relation of different zoom positions with d14:

＜the four embodiment 〉

Fig. 5 A represents the location drawing of embodiment four each lens when wide viewing angle; Fig. 5 B represents the image curve figure of embodiment four when wide viewing angle; Fig. 5 C represents the image curve figure of embodiment four when middle visual angle; Fig. 5 D represents the image curve figure of embodiment four when small angle.

The elementary optical characteristics of embodiment four is Fno=1: 3.65-6.81, f=7.45-21.39, w=29.9 °-11.2 °.Wherein Fno represents the aperture bore corresponding to wide viewing angle and small angle, and f represents the system's focal length corresponding to wide viewing angle and small angle, and w represents the half angle of view corresponding to wide viewing angle and small angle.Its data please refer to following table four, and wherein r represents the radius-of-curvature that each is surperficial, and d represents the axial distance between each minute surface, and n represents the refractive index of each minute surface, and v represents the Abbe number of each minute surface.

＜table four 〉

In the lens combination, wherein octahedral, the 9th, the 13 and the tenth four sides be aspheric surface, and its asphericity coefficient data is distinguished as follows:

Variable d6 is as follows respectively with respect to the relation of different zoom positions with d14:

Table five is above four embodiment and the relevant statistical form of condition (a) to (h).Above embodiment miniaturization reference value (OAL/IMA) is all little of 8.84, far below prior art.

Table five

Wherein the meaning of field code name is as follows:

OAL/IMA represents the ratio of zoom system, pancreatic system total length (total track) and image sensor size (image sensorsize), is defined as the miniaturization reference value;

d ₁₂It is the axial distance of the 6th eyeglass L6 and the 7th eyeglass L7;

It is the radial height of the 6th eyeglass L6;

e ₁₃Be the outer edge thickness of the 7th eyeglass L7, d ₁₃It is the center thickness of the 7th eyeglass L7;

f ₂Be the focal length of back group, f _wFocal length during for wide viewing angle.

n ₁₀Be the refractive index of the 5th eyeglass L5, n ₁₁Be the refractive index of the 6th eyeglass L6, n ₈The refractive index (index) of representing the 4th eyeglass L4, n ₁₃The refractive index of representing the 7th eyeglass L7; v ₈Be the Abbe number of the 4th eyeglass L4, v ₁₃It is the Abbe number of the 7th eyeglass L7.

The zoom lens that cooperates this preferred embodiment, wherein glue-bondable one-tenth one balsaming lens of the 5th eyeglass L5 of this zoom lens and the 6th eyeglass L6 preferably meets following condition (d): 0.28＜(n ₁₀-n ₁₁) absolute value＜0.31, wherein, n ₁₀Be the refractive index of the 5th eyeglass L5, n ₁₁It is the refractive index of the 6th eyeglass L6.

And the data by the preferred embodiment of the invention described above can learn, wherein this zoom lens is preferable also meets following condition (e), (f), (g), (h):

(e) 1.49＜n ₈＜1.53, n wherein ₈It is the refractive index of the 4th eyeglass L4;

(f) 1.52＜n ₁₃＜1.59, n wherein ₁₃It is the refractive index of the 7th eyeglass L7;

(g) 56＜v ₈＜58, v wherein ₈It is the Abbe number of the 4th eyeglass L4; And

(h) 29＜v ₁₃＜57, v wherein ₁₃It is the Abbe number of the 7th eyeglass L7.

Above-mentioned condition can select one, or meet simultaneously.

(creation characteristic of the present invention and characteristics)

Therefore characteristics that can produce by the present invention and function through put in order as after:

One, zoom lens of the present invention has high zoom ratios (reach 2.87, be better than prior art), and simultaneously its miniaturization reference value is little of 8.84, far below prior art, can effectively save the space and reduce the volume of image acquiring apparatus.

Two, the 4th eyeglass L4 and the 7th eyeglass L7 are the non-spherical eyeglasses made from plastic material among the present invention, and other eyeglass can use general glass mirror commonly used.The aberration of the optical module of non-spheroidal mirror in can compensation optical system reduces cost, and weight reduction, so the present invention also has advantage with low cost.

Three, glue-bondable one-tenth one balsaming lens of the 5th eyeglass L5 and the 6th eyeglass L6 among the present invention can simplify the number of assembling steps of zoom lens thus, reaches the advantage of easy assembling.

Yet above disclosed, only be preferred embodiment of the present invention, nature can not limit the scope of the present invention with this, therefore to equal variation or modification that the present invention did, must belong to protection scope of the present invention.

Claims (8)

1. a zoom lens comprises a preceding group and a back group, it is characterized in that,

Group comprises before described: first eyeglass, and it is a negative meniscus; Second eyeglass, it is a double-concave negative lens; And prismatic glasses, it is a positive lens; Group comprises after described: the 4th eyeglass, and it is a positive lens; The 5th eyeglass, it is a biconvex lens; The 6th eyeglass, it is a negative meniscus; And the 7th eyeglass, it is a negative meniscus, wherein the 4th eyeglass and the 7th eyeglass are the non-spherical eyeglass made from plastic material, and this zoom lens meets following condition:

Condition (a):

Condition (b): 1.20＜e ₁₃/ d ₁₃＜1.36

Condition (c): 1.2＜f ₂/ f _w＜1.3

Wherein,

d ₁₂It is the axial distance of the 6th eyeglass and the 7th eyeglass;

It is the radial height of the 6th eyeglass;

e ₁₃Be the outer edge thickness of the 7th eyeglass, d ₁₃It is the center thickness of the 7th eyeglass;

f ₂Be the focal length of back group, f _wFocal length during for wide viewing angle.

2. zoom lens as claimed in claim 1 is characterized in that, the 5th eyeglass and the 6th eyeglass compose a balsaming lens.

3. zoom lens as claimed in claim 1 is characterized in that, this zoom lens also meets following condition (d):

0.28＜(n ₁₀-n ₁₁) absolute value＜0.31, wherein,

n ₁₀Be the refractive index of the 5th eyeglass, n ₁₁It is the refractive index of the 6th eyeglass.

4. zoom lens as claimed in claim 1 is characterized in that, this zoom lens also meets following condition (e):

1.49＜n ₈＜1.53, n wherein ₈It is the refractive index of the 4th eyeglass.

5. zoom lens as claimed in claim 1 is characterized in that, this zoom lens also meets following condition (f):

1.52＜n ₁₃＜1.59, n wherein ₁₃It is the refractive index of the 7th eyeglass.

6. zoom lens as claimed in claim 1 is characterized in that, this zoom lens also meets following condition (g):

56＜v ₈＜58, v wherein ₈It is the Abbe number of the 4th eyeglass.

7. zoom lens as claimed in claim 1 is characterized in that, this zoom lens also meets following condition (h):

29＜v ₁₃＜57, v wherein ₁₃It is the Abbe number of the 7th eyeglass.

8. zoom lens as claimed in claim 1 is characterized in that, this zoom lens also meets following condition:

1.49＜n ₈＜1.53, n wherein ₈It is the refractive index of the 4th eyeglass;

1.52＜n ₁₃＜1.59, n wherein ₁₃It is the refractive index of the 7th eyeglass;

56＜v ₈＜58, v wherein ₈It is the Abbe number of the 4th eyeglass; And

29＜v ₁₃＜57, v wherein ₁₃It is the Abbe number of the 7th eyeglass.

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