CN201273959Y - Small optical picture-taking lens with short rear focal and two lens - Google Patents

Abstract

The utility model relates to a small-sized optical taking lens with short back focus and two lenses. An aperture stop, a first lens, a second lens and an infrared optical filter are arranged along an optical axis from an object side to an image side in sequence, wherein, the first lens is in a meniscus shape and has positive refractive power and non-spherical surfaces and the convex surface faces the object side and the concave surface faces the image side, and the second lens is in the meniscus shape and has a negative refractive power and non-spherical surfaces and the convex surface faces the image side and the concave surface faces the object side; the optical taking lens satisfies the following conditions: -0.3 is less than or equal to f1/f2 is less than or equal to-0.01; and 0.25 is less than or equal to bf/TL is less than or equal to 0.4, wherein, f1 is the symbol of the focus length of the first lens, f2 is the symbol of the focus length of the second lens, bf is the symbol of the back focus of the taking lens system, and TL (total length) is the symbol of a distance between the aperture stop and an imaging surface; and thereby, the effect of short back focus is realized so as to effectively shorten the length of the optical taking lens, and therefore, the small-sized optical taking lens can be applied to the small-sized camera and the mobile phone so as to satisfy the use demands for size minimizing.

Description

Small-sized short rear focus and two lenses optical shooting lens

Technical field

The utility model is relevant a kind of small-sized short rear focus and two lenses optical shooting lens, especially refer to a kind of camera lens, and a kind of short back Jiao who is made of positive diopter and negative diopter lens, total length weak point and optical shooting lens cheaply are provided at uses CCD such as compact camera or mobile phone (the electric charge lotus root attaches together and puts) or CMOS image sensor such as (complementary metal oxide semiconductor (CMOS)s).

Background technology

In electronic product as: devices such as digital camera (Digital Still Camera), camera computer (PC camera), network cameras (Network camera), mobile phone (mobile phone), PDA(Personal Digital Assistant) have often possessed sampling image lens; And for easy to carry and meet the demand of hommization, sampling image lens not only needs to have good image quality, also needs smaller volume (or total length) and lower cost simultaneously, to meet user's demand.

Be applied to the sampling image lens of small-sized electronic product, having now has two eyeglass formulas, prismatic glasses formula, four eyeglass formulas and five eyeglass formulas with first-class different designs, yet considers with cost, and the lens that two eyeglass formulas are used are less, and its cost is than the tool advantage.Existing two eyeglass formula optical shooting lens have had multiple different structural design, but difference place therebetween or technical characterictic then are variation or the combinations that is decided by following various factors: the shaped design difference of corresponding matching between these two lens is respectively meniscus (meniscus shape) lens, biconvex (bi-convex), concave-concave (bi-concave) as first and second lens; Or the convex surface/concave direction difference of corresponding matching between these two lens; Or the positive and negative difference of diopter (refractive power) of corresponding matching between these two lens; Or the condition difference that satisfied such as the relevant optical data between these two lens set/eyeglass such as fs (effective focal length of sampling image lens system), di (distance between each optical surface i), Ri (each optical surface i radius-of-curvature); As from the foregoing, with regard to the design of the optical shooting lens of two eyeglass formulas, prior art is in design optical shooting lens technical field, be at the application of various different optical purposes and produce different variations or combination, and, promptly can be considered and have novelty (novelty) and progressive (inventive step) because of shape, combination, effect or the effect difference of its lens that use.

In recent years for be applied to compact camera, product such as the mobile phone of taking pictures, PDA, its sampling image lens requires miniaturization, focal length is short, the aberration adjustment is good, in the two lens sampling image lens design of various miniaturizations, with first lens of positive diopter, second lens of positive diopter or the design of other combinations, most probable reaches the demand of miniaturization, as U.S. Pat 2005/0073753, US2004/0160680, US7,110,190, US7,088,528, US2004/0160680; European patent EP 1793252, EP1302801; Jap.P. JP2007-156031, JP2006-154517, JP2006-189586; Taiwan patent TWM320680, TWI232325; Chinese patent CN101046544 etc.Yet, the disclosed optical shooting lens of these patents, its camera lens length overall must further be dwindled again; The burnt design in short back for user's demand just is being to use-is bearing dioptric combination as U.S. Pat 2006/0221467, Jap.P. JP2005121685, JP2006154517; U.S. Pat 20030/0197956 is used the combination of negative-positive diopter; U.S. Pat 5,835,288 use the combination of concave-concave and biconvex lens, the combination that Jap.P. JP20040281830 uses plus or minus-positive diopter; Or as Japanese patent application publication No. JP2003215446, JP2004-177976, European patent EP 1793252 and EP1793254, U.S. Pat 6,876,500, US2004/0160680, US7,088,528, Taiwan patent TWI266074 etc. is just using-combination of positive diopter, and the camera lens total length is reduced.In the design of various different shortening camera lens length overalls, still the most effectively, but directly shorten the result that back focal length will cause difficult focusing with short back Jiao.For this reason, the utility model proposes the more design of practicality, shortening back focal length simultaneously, utilize and shorten between eyeglass air clearance supplying difficult focusing and to be lowered into image distortion, be applied to compact camera easily, on the electronic product such as the mobile phone of taking pictures.

Summary of the invention

The utility model fundamental purpose is to be to provide a kind of small-sized short rear focus and two lenses optical shooting lens, shortening back focal length simultaneously, utilize to shorten between eyeglass air clearance supplying difficult focusing and to be lowered into image distortion, be applied to compact camera easily, on the electronic product such as the mobile phone of taking pictures.

Small-sized short rear focus and two lenses optical shooting lens of the present utility model, it is arranged by thing side (object side) to picture side (image side) along optical axis and comprises in regular turn: an aperture diaphragm (aperture stop); First lens of one positive diopter (a first lens of positive refractive power) are that meniscus lens and thing side are convex surface, and two optical surfaces are aspheric surface; One to have negative dioptric second lens (asecond lens of negative refractive power) be meniscus lens and be convex surface as the side, and two optical surfaces are aspheric surface; One infrared filter and an image sensor; This optical shooting lens meets the following conditions again:

$0.25\≤\frac{d_2+d_4+d_6}{f_s}\≤0.4---\left(1\right)$

$0.25\≤\frac{\mathrm{bf}}{\mathrm{TL}}\≤0.4---\left(2\right)$

$-0.3\≤\frac{f_1}{f_2}\≤-0.01---\left(3\right)$

$-4.0\≤\frac{(R_2-R_3)}{(R_2+R_3)}\≤-1.5---\left(4\right)$

Wherein, f _sBe the effective focal length (effective focal length) of optical shooting lens, f ₁The focal length that is first lens is long, f ₂The focal length that is second lens is long, and bf is a focal length after this sampling image lens system, TL be on the optical axis aperture diaphragm to the distance of imaging surface, d ₂For first lens on the optical axis as the distance of lens thing side, side to the second, d ₄For second lens on the optical axis as the distance of side to infrared filter thing side, d ₆For infrared filter on the optical axis as the distance of side to the imaging surface of image sensor, R ₂Be the paraxial radius-of-curvature in picture side of first lens, R ₃It is the paraxial radius-of-curvature in thing side of second lens.

Moreover, first lens of this short rear focus and two lenses optical shooting lens and second lens can be glass or plastic cement is made.

By this, the combination of this two eyeglass can be reached and be had short focal length afterwards, further reduces the length of camera lens, and can use same material to make to reduce cost of manufacture, uses the application that promotes sampling image lens.

Description of drawings

Fig. 1 is an optical texture synoptic diagram of the present utility model;

Fig. 2 is a light channel structure synoptic diagram of the present utility model;

Fig. 3 is the curvature of field (field curvature) figure of the utility model first embodiment;

Fig. 4 is image deformation (distortion) figure of the utility model first embodiment;

Fig. 5 is the longitudinal aberration diagram of the utility model first embodiment (when radius 0.6086mm);

Fig. 6 is the curvature of field figure of the utility model second embodiment;

Fig. 7 is the image deformation figure of the utility model second embodiment;

Fig. 8 is the longitudinal aberration diagram of the utility model second embodiment (when radius 0.5588mm);

Fig. 9 is the curvature of field figure of the utility model the 3rd embodiment;

Figure 10 is the image deformation figure of the utility model the 3rd embodiment;

Figure 11 is the longitudinal aberration diagram of the utility model the 3rd embodiment (when radius 0.4996mm).

Description of reference numerals:

The 1-optical shooting lens; 11-first lens; R1-(first lens) thing side; R2-(first lens) is as the side; The S-aperture diaphragm; 12-second lens; R3-(second lens) thing side; R4-(second lens) is as the side; The 13-infrared filter; The 14-image sensor; The first lens thing side is to the distance of picture side on the d1-optical axis; First lens are as the distance of lens thing side, side to the second on the d2-optical axis; The second lens thing side is to the distance of picture side on the d3-optical axis; Second lens are as the distance of side to infrared filter thing side on the d4-optical axis; Infrared filter thing side is to the distance of picture side on the d5-optical axis; Infrared filter is as the distance of side to image sensor on the d6-optical axis.

Embodiment

For making the utility model clear and definite more full and accurate, enumerate preferred embodiment now and cooperate following diagram, structure of the present utility model and technical characterictic are described in detail as the back:

With reference to shown in Figure 1, it is double-lens optical taking lens 1 structural representation of the present utility model, and it is arranged by thing side (object side) to picture side (image side) along optical axis Z and comprises in regular turn: an aperture diaphragm S, one first lens 11, one second lens 12, an infrared filter (IR cut-off filter) 13 and one image sensor (image sensing chip) 14; During capture, the light of thing to be taken the photograph (object) is first through behind first lens 11 and second lens 12, images on the imaging surface (image) of image sensor 14 through infrared filter 13 again.

These first lens 11 are meniscus lens, and its thing side R1 is a convex surface and be concave surface as side R2, has positive diopter, can utilize glass or plastic cement material to make, again its thing side R1 and be aspheric surface as side R2.

These second lens 12 are meniscus lens, and its thing side R3 is a concave surface and be convex surface as side R4, has negative diopter, can utilize glass or plastic cement material to make, again its thing side R3 and be aspheric surface as side R4.

This aperture diaphragm (aperture stop) S belongs to a kind of preposition aperture, and it is to be attached on the thing side R1 of first lens 11; This infrared filter (IR cut-off filter) 13 can be an eyeglass, or utilizes coating technique formation one to have the film of infrared ray filtering functions; This image sensor (image sensingchip) 14 comprises CCD (the electric charge lotus root attaches together and puts) or CMOS (complementary metal oxide semiconductor (CMOS)).

The utility model double-lens optical taking lens 1 is at optical surface radius-of-curvature, non-spherical surface and the lens thickness (d1 and d3) and air clearance (d of first lens 11 and second lens 12 again ₂, d ₄And d ₆) after the optics combination, the camera lens of formation has short back focal length, it further can shorten the total length of camera lens and back focal length in a small range, promptly satisfies formula (2).The optical surface of first lens 11 and second lens 12 is an aspheric surface, and its aspheric equation (Aspherical Surface Formula) is formula (5)

$Z=\frac{{\mathrm{ch}}^2}{1+\sqrt{(1-(1+K)c^2{h}^2)}}+A_4{h}^4+A_6{h}^6+A_8{h}^8+A_{10}{h}^{10}+A_{12}{\mathrm{<figure-callout\; id="12"\; label="h"\; filenames="Y200820134900E00141.png"\; state="\{\{state\}\}">h</figure-callout>}}^{12}+A_{14}{h}^{14}---\left(5\right)$

Wherein c is a curvature, and h is the eyeglass height, and K is circular cone coefficient (Conic Constant), A ₄, A ₆, A ₈, A ₁₀, A ₁₂, A ₁₄The asphericity coefficient (Nth Order Aspherical Coefficient) of difference four, six, eight, ten, 12, ten quadravalences.

The mat said structure, focal length can effectively dwindle after the double-lens optical taking lens 1 of the present utility model, and lens length is reduced, and promptly satisfies formula (1)～formula (4).

Now enumerate preferred embodiment, and be respectively described below:

＜the first embodiment 〉

Please refer to shown in Fig. 2,3,4,5, it is respectively light channel structure synoptic diagram and the curvature of field (field curvature), image deformation (distortion) and the figure of the longitudinal aberration (vertical aberration) when radius (radius) 0.6086mm of the utility model optical shooting lens 1 first embodiment.

Show respectively in the following tabulation () by the thing side to the optical surface number (surface number) of numbering in regular turn as side, the radius of curvature R of each optical surface on the optical axis (unit: mm) on (the radius of curvature R), the optical axis between each face apart from d (unit: mm) (the on-axis surface spacing), the refractive index (N of each lens _d) and the Abbe number of each lens (Abbe ' s number) v _d

Table (one)

^*aspherical?surface

In table (), optical surface (Surface) has mark ^*The person is the aspherics face, and Surf 1, Surf 2 represent the thing side R1 and picture side R2 of first lens 11 respectively, and Surf 3, Surf 4 represent the thing side R3 and picture side R4, f of second lens 12 respectively _sEffective focal length for sampling image lens.Every coefficient of the aspheric surface formula (5) of each optical surface is shown in following tabulation (two):

Table (two)

In the present embodiment, first lens 11 are to utilize identical glass material to make with second lens 12, its refractive index N _dBe 1.587, Abbe number v _dBe 60.0; Infrared filter 13 is to use refractive index N _dBe 1.517, Abbe number v _dBe that 64.17 glass material is made.

The effective focal length f of present embodiment optical shooting lens 1 _sBe 3.408mm, the focal distance f of first lens 11 ₁Focal distance f for 2.7879mm, second lens 12 ₂For-15.418mm; On optical axis, be 3.763mm to the imaging surface of image sensor 15 apart from TL (total length) by the thing side R1 of first lens 11; That is,

$\frac{d_2+d_4+d_6}{f_s}=0.3811;$ $\frac{f_1}{f_2}=-0.1808;$ $\frac{\mathrm{bf}}{\mathrm{TL}}=0.350;$ $\frac{(R_2-R_3)}{(R_2+R_3)}=-3.6101$

The formula that can satisfy condition (1)-Shi (4).

Shown in the curvature of field (field curvature) of above-mentioned table (), table (two) and Fig. 3～5, image deformation (distortion) and longitudinal aberration (vertical aberration) figure when radius (radius) 0.6086mm, provable by this double-lens optical taking lens of the present utility model can effectively be revised aberration, make optical shooting lens 1 have the burnt effect of high-res and short back, can effectively dwindle lens length, and promote application of the present utility model.

In Fig. 3,6, the 9 represented curvature of field curve maps, horizontal ordinate is represented focal length, and unit is a millimeter; Ordinate is represented image height, and curve T, S respectively correspondence tangentially and radially as seen from the figure under the different focus offsets, change situation with the curvature of field that different image height was produced of optical axis.

In Fig. 4,7, the 10 represented image deformation curve maps, horizontal ordinate is represented the number percent of twisting coefficient; Ordinate is represented the different image heights with optical axis, during as seen from the figure for different image height, and the situation that its twisting coefficient changes.

Among Fig. 5,8, the 11 represented aberration curve figure, ordinate is a longitudinal aberration, and horizontal ordinate is a focal length, and unit is a millimeter.As seen from the figure, under different focus offsets, the variation situation of its spherical aberration.

＜the second embodiment 〉

Please refer to shown in Fig. 2,6,7,8, it is respectively light channel structure synoptic diagram and the curvature of field, image deformation and the longitudinal aberration diagram when radius 0.5588mm of the utility model optical shooting lens 1 second embodiment.

Show respectively in the following tabulation (three) by the thing side to the optical surface number of numbering in regular turn as side, on the radius of curvature R of each optical surface on the optical axis, the optical axis between each face apart from d, the refractive index (N of each lens _d) and the Abbe number v of each lens _d

Table (three)

^*aspherical?surface

Every coefficient of the aspheric surface formula (5) of each optical surface is shown in following tabulation (four):

Table (four)

In the present embodiment, first lens 11 are to utilize identical glass material to make with second lens 12, its refractive index N _dBe 1.587, Abbe number v _dBe 60.0; Infrared filter 13 is to use its refractive index N _dBe 1.517, Abbe number v _dBe that 64.17 glass material is made.

The effective focal length f of present embodiment optical shooting lens 1 _sBe 3.129mm, and the focal distance f of first lens 11 ₁Focal distance f for 2.7719mm, second lens 12 ₂For-130.8mm; On optical axis, be 3.5959mm to the imaging surface of image sensor 15 apart from TL (total length) by the thing side R1 of first lens 11; That is,

$\frac{d_2+d_4+d_6}{f_s}=0.3155;$ $\frac{f_1}{f_2}=-0.0212;$ $\frac{\mathrm{bf}}{\mathrm{TL}}=0.3946;$ $\frac{(R_2-R_3)}{(R_2+R_3)}=-2.6480$

The formula that can satisfy condition (1)～formula (4).

Shown in the curvature of field, image deformation and the longitudinal aberration diagram of above-mentioned table (three), table (four) and Fig. 6～8, provable by this double-lens optical taking lens of the present utility model can effectively be revised aberration, make optical shooting lens 1 have the burnt effect of high-res and short back, can effectively dwindle lens length, and promote application of the present utility model.

＜the three embodiment 〉

Please refer to shown in Fig. 2,9,10,11, it is respectively light channel structure synoptic diagram and the curvature of field, image deformation and the longitudinal aberration diagram when radius 0.4996mm of the utility model optical shooting lens 1 the 3rd embodiment.

Show respectively in the following tabulation (five) by the thing side to the optical surface number of numbering in regular turn, at optical axis as side. go up on the radius of curvature R, optical axis of each optical surface between each face apart from d the refractive index (N of each lens _d), the Abbe number v of each lens _d

Table (five)

^*aspherical?surface

Every coefficient of the aspheric surface formula (5) of each optical surface is shown in following tabulation (six):

Table (six)

In the present embodiment, first lens 11 are to utilize identical glass material to make with second lens 12, its refractive index N _dBe 1.580, Abbe number v _dBe 58.9; Infrared filter 13 is to use its refractive index N _dBe 1.517, Abbe number v _dBe that 64.17 glass material is made.

The effective focal length f of present embodiment optical shooting lens 1 _sBe 2.878mm, and the focal distance f of first lens 11 ₁Focal distance f for 2.4924mm, second lens 12 ₂For-11.1504mm; On optical axis, be 3.3509mm to the imaging surface of image sensor 15 apart from TL by the thing side R1 of first lens 11; That is,

$\frac{d_2+d_4+d_6}{f_s}=0.2898;$ $\frac{f_1}{f_2}=-0.2235;$ $\frac{\mathrm{bf}}{\mathrm{TL}}=0.3551;$ $\frac{(R_2-R_3)}{(R_2+R_3)}=-1.9593$

The formula that can satisfy condition (1)～formula (4).

Shown in the curvature of field, image deformation and the longitudinal aberration diagram of above-mentioned table (five), table (six) and Fig. 9～11, provable by this double-lens optical taking lens of the present utility model can effectively be revised aberration, make optical shooting lens 1 have the burnt effect of high-res and short back, can effectively dwindle lens length, and promote application of the present utility model.

More than shown in only be preferred embodiment of the present utility model, only be illustrative for the utility model, and nonrestrictive.This area tool common knowledge technology personnel understand, and can carry out many changes, modification even equivalence change to it in the spirit and scope that the utility model claim is limited, but all will fall in the interest field of the present utility model.

Claims (3)

1, a kind of small-sized short rear focus and two lenses optical shooting lens is characterized in that, arranges by the thing side along optical axis extremely to comprise in regular turn as side:

One aperture diaphragm;

One first lens have positive diopter, and it is meniscus lens, and its convex surface is towards the thing side, and two optical surfaces are aspheric surface;

One second lens have negative diopter, and it is meniscus lens, and its convex surface is towards the picture side, and two optical surfaces are aspheric surface;

One infrared filter; And

One image sensor;

Wherein, first lens and second lens are to use same glass material made; And meet the following conditions:

$0.25\&le;\frac{d_2+d_4+d_6}{f_s}\&le;0.4$

$-0.3\&le;\frac{f_1}{f_2}\&le;-0.01$

$0.25\&le;\frac{\mathrm{bf}}{\mathrm{TL}}\&le;0.4$

Wherein, f _sBe the effective focal length of optical shooting lens, f ₁The focal length that is first lens is long, f ₂Be the focal length of second lens, bf is this sampling image lens system focal length afterwards, and TL is the distance of aperture diaphragm to imaging surface, d ₂For first lens on the optical axis as the distance of lens thing side, side to the second, d ₄For second lens on the optical axis as the distance of side to infrared filter thing side, d ₆For infrared filter on the optical axis as the distance of side to the imaging surface of image sensor.

2, according to the described small-sized short rear focus and two lenses optical shooting lens of claim 1, it is characterized in that this sampling image lens has short back focal length, satisfy following condition:

$0.1\&le;\frac{d_2}{f_s}\&le;0.2$

Wherein, d ₂Be distance, the f of first lens on the optical axis as lens thing side, side to the second _sEffective focal length for optical shooting lens.

3, according to the described small-sized short rear focus and two lenses optical shooting lens of claim 1, it is characterized in that, meet the following conditions:

$-4.0\&le;\frac{(R_2-R_3)}{(R_2+R_3)}\&le;-1.5$

Wherein, R ₂Be the paraxial radius-of-curvature in picture side of first lens, R ₃It is the paraxial radius-of-curvature in thing side of second lens.

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