CN101354475A - Focus fixing lens - Google Patents

Abstract

The invention discloses a fixed focus lens. A first lens group and a second lens group are sequentially arranged on the optical axis from the object end to the imaging end; the first lens group is provided with negative dioptre and the second lens group is provided with the positive dioptre; the fixed lens meets the condition as follows: 2Gf/1Gf is less than 0 and more than -1, wherein, 1Gf is the focus length of the first lens group and the 2Gf is the focus length of the second lens group. The fixed focus lens uniformly distributes the tolerance sensitiveness of the fixed focus lens, improves the qualified rate of the production and assembly, thus reducing the whole cost further. Part lens in the fixed focus lens of the invention adopts the non-spherical lens of plastic material, thus reducing the cost and improving the imaging quality. Matched with the design of optical parameter, the fixed focus lens of the invention also reduces the total length of the optical system of the fixed focus lens.

Description

Tight shot

Technical field

The present invention relates to a kind of camera lens, particularly a kind of tight shot.

Background technology

In recent years, digital camera device fast development.Along with the design of digital camera is tending towards compact gradually, the optical lens design on the digital camera is also just got over important.General camera lens can be divided into tight shot and zoom lens, and tight shot can provide favorable imaging quality to digital camera with lower cost because of its comparatively simple characteristic.

Though the tight shot design has developed one period time, optical system cost, length overall and the image quality of whole tight shot still have many progressive spaces.

Therefore how to reduce the optical system cost and the length overall of tight shot, and favorable imaging quality is provided, make camera apparatus can dwindle overall volume and cost, the target of being made great efforts for each manufacturer at present.

Summary of the invention

Therefore, the technical problem to be solved in the present invention just is to provide a kind of tight shot, in order to reducing cost, and provides favorable imaging quality.

The present invention solves the technical scheme that its technical matters adopts: propose a kind of tight shot, comprise successively on optical axis by thing end to imaging end: first lens combination with negative refractive index, described first lens combination includes the plastic cement negative lens, and at least one surface of described plastic cement negative lens is an aspheric surface; Second lens combination with positive refractive index, described second lens combination includes the plastic cement positive lens, and at least one surface of described plastic cement positive lens is an aspheric surface; And described tight shot satisfies following condition :-1＜2Gf/1Gf＜0, and wherein 1Gf is the focal length of described first lens combination, and 2Gf is the focal length of described second lens combination.

In the described tight shot, described first lens combination also comprises terminal positive lens, and described terminal positive lens is arranged on the imaging end of described plastic cement negative lens.And described first lens combination satisfies following condition :-0.5＜(C1 f/L3 f)＜0.5, and wherein C1 f is the focal length when comprising described plastic cement negative lens and not comprising described terminal positive lens, L3f is the focal length of described terminal positive lens.

Perhaps, described first lens combination also inclusion is rectified lens and terminal positive lens, and proper lens of described thing and terminal positive lens are separately positioned on the both sides of described plastic cement negative lens.Described first lens combination need satisfy following condition :-0.5＜(C1 f/L3 f)＜0.5, and wherein C1 f is the synthetic focal length that described thing is rectified lens and described plastic cement negative lens, L3f is the focal length of described terminal positive lens.

In the described tight shot, described second lens combination also comprises central positive lens and imaging end negative lens, and described central positive lens is arranged between described plastic cement positive lens and the described imaging end negative lens.Described second lens combination also satisfies following condition :-1.5＜(L5f/L6f)＜-0.5, and wherein L5f is the focal length of described central positive lens, L6f is the focal length of described imaging end negative lens.

Described tight shot also includes aperture diaphragm, and described aperture diaphragm is between described first lens combination and described second lens combination.Described tight shot also includes wave filter, and described wave filter is between described second lens combination and imaging end.

The present invention can improve the tolerance susceptibility uniform distribution of tight shot the qualification rate of producing assembling, and then reduce whole cost.In addition, because the part lens in the tight shot adopt the aspherical lens of plastic cement material, reduced cost and improved image quality.Cooperate the design of optical parametric, the present invention has also reduced the optical system length overall of tight shot.

Description of drawings

The invention will be further described below in conjunction with drawings and Examples, in the accompanying drawing:

Fig. 1 is the tight shot synoptic diagram of first embodiment of the invention;

Fig. 2 A is the curvature of field figure of the tight shot field of first embodiment of the invention;

Fig. 2 B is the distortion figure of the tight shot field of first embodiment of the invention;

Fig. 3 A-3F is respectively the light sector diagram of the tight shot of first embodiment of the invention;

Fig. 4 is the longitudinal aberration diagram of the tight shot of first embodiment of the invention;

Fig. 5 is the out of focus modulation transfer function figure of the tight shot of first embodiment of the invention.

Fig. 6 is the tight shot synoptic diagram of second embodiment of the invention;

Fig. 7 A is the curvature of field figure of the tight shot field of second embodiment of the invention;

Fig. 7 B is the distortion figure of the tight shot field of second embodiment of the invention;

Fig. 8 A-8F is respectively the light sector diagram of the tight shot of second embodiment of the invention;

Fig. 9 is the longitudinal aberration diagram of the tight shot of second embodiment of the invention;

Figure 10 A-10B is the out of focus modulation transfer function figure of the tight shot of second embodiment of the invention.

[primary clustering symbol description]

100/200: 110: the first lens combination of tight shot

114: the second negative lenses of 112: the first positive lenss

120: the second lens combination of 116: the three positive lenss

124: the five positive lenss of 122: the four positive lenss

Negative lens 130 in 126: the six: aperture diaphragm

140: wave filter 150: the imaging end

160: thing end 170: optical axis

Embodiment

Embodiments of the invention are with the uniform distribution of tolerance susceptibility, and the aspherical lens of part lens use plastic cement material, can reduce whole cost, improve image quality.Any those of ordinary skill in the art, under the situation that does not break away from the spirit and scope of the present invention, the material of variable optical parametric wherein and part lens is with the situation of realistic application.

The tight shot of the embodiment of the invention comprises first lens combination and second lens combination successively by thing end to imaging end on optical axis.In the time of in tight shot is installed in camera, the imaging end then is the photosensory assembly in the camera.First lens combination has negative refractive index, and includes the plastic cement negative lens, and it is aspheric surface that described plastic cement negative lens has at least one surface.Second lens combination has positive refractive index, and includes the plastic cement positive lens, and it is aspheric surface that described plastic cement positive lens has at least one surface.

The tight shot of various embodiments of the present invention satisfies following condition:

-1＜2Gf/1Gf＜0......(1)

Wherein, 1Gf is the focal length of first lens combination, and 2Gf is the focal length of second lens combination.

In addition, first lens combination also comprises terminal positive lens, be arranged at the imaging end of plastic cement negative lens, and first lens combination satisfies following condition:

-0.5＜(C1?f/L3?f)＜0.5......(2)

Wherein, C1 f is the focal length when comprising the plastic cement negative lens and not comprising terminal positive lens, and L3f is the focal length of terminal positive lens.

In addition, first lens combination also inclusion is rectified lens, be arranged at the thing end of plastic cement negative lens, and first lens combination satisfies above-listed condition (2).Wherein, C1 f is the synthetic focal length of proper lens of this thing and plastic cement negative lens, and L3f is the focal length of terminal positive lens.

And second lens combination also comprises central positive lens and imaging end negative lens, and central positive lens is arranged between plastic cement positive lens and the imaging end negative lens.Second lens combination satisfies following condition:

-1.5＜(L5f/L6f)＜-0.5......(3)

Wherein, L5f is the focal length of central positive lens, and L6f is the focal length of imaging end negative lens.

In order more carefully to describe relativeness and the effect between each lens, please refer to Fig. 1, be the synoptic diagram of thetight shot 100 of first embodiment of the invention.Tight shot 100 successively comprisesfirst lens combination 110 andsecond lens combination 120 to imagingend 150 in optical axis on 170 by thing end 160.Wherein,first lens combination 110 has negative refractive index, andsecond lens combination 120 has positive refractive index, andfirst lens combination 110 andsecond lens combination 120 are made up of three lens respectively.In order more to know the relative position between each lens, this sentences putting in order fromthing end 160 to imagingend 150 and is the lens name.

First lens combination 110 comprises firstpositive lens 112, secondnegative lens 114 and the 3rdpositive lens 116 by thing end 160 successively to imaging end 150.Wherein firstpositive lens 112 is the proper lens of above-mentioned thing, and secondnegative lens 114 is the plastic cement negative lens, and the 3rdpositive lens 116 is terminal positive lens.

Second lens combination 120 comprises the 4thpositive lens 122, the 5thpositive lens 124 and the 6thnegative lens 126 by thing end 160 successively to imaging end 150.Wherein the 4thpositive lens 122 is above-mentioned plastic cement positive lens, and the 5thpositive lens 124 is central positive lens, and the 6thnegative lens 126 is imaging end negative lens.

First lens combination 110 andsecond lens combination 120 necessary eligible (1) are with uniform distribution tolerance susceptibility.It is poor thatfirst lens combination 110 is received with correcting colour by positive and negative positive lens collocation, and wherein secondnegative lens 114 is designed to aspheric surface with the rectification aberration, and the focal length of each lens 112,114 offirst lens combination 110 and 116 necessary eligible (2).And insecond lens combination 120, the 5thpositive lens 124 and the 6thnegative lens 126 can be arranged in pairs or groups mutually with the rectification aberration, and the focal length of the 5thpositive lens 124 and the 6thnegative lens 126 necessary eligible (3).

In addition,tight shot 100 also includesaperture diaphragm 130, andaperture diaphragm 130 is arranged betweenfirst lens combination 110 and second lens combination 120.Other haswave filter 140 to be arranged betweensecond lens combination 120 and theimaging end 150.

Be illustrated in figure 6 as the synoptic diagram of thetight shot 200 of second embodiment of the invention.Tight shot 200 successively comprisesfirst lens combination 110 andsecond lens combination 120 toimaging end 150 in optical axis on 170 by thing end 160.Wherein,first lens combination 110 has negative refractive index, andsecond lens combination 120 has positive refractive index, andfirst lens combination 110 is made up of two lens, andsecond lens combination 120 is made up of three lens.In order more to know the relative position between each lens, this sentences putting in order fromthing end 160 to imagingend 150 and is the lens name.

First lens combination 110 comprises secondnegative lens 114, the 3rdpositive lens 116 by thing end 160 successively to imaging end 150.Wherein secondnegative lens 114 is the plastic cement negative lens, and the 3rdpositive lens 116 is terminal positive lens.

Second lens combination 120 comprises the 4thpositive lens 122, the 5thpositive lens 124 and the 6thnegative lens 126 by thing end 160 successively to imaging end 150.Wherein the 4thpositive lens 122 is above-mentioned plastic cement positive lens, and the 5thpositive lens 124 is central positive lens, and the 6thnegative lens 126 is imaging end negative lens.

The difference of thetight shot 200 of second embodiment of the invention and thetight shot 100 of first embodiment is, does not comprise first positive lens (thing is rectified lens) 112 of the thing end that is arranged on second negative lens (plastic cement negative lens) 114 in the tight shot 200.In thetight shot 200 of second embodiment,first lens combination 110 andsecond lens combination 120 necessary eligible (1) are with uniform distribution tolerance susceptibility.It is poor thatfirst lens combination 110 is received with correcting colour by negative positive lens collocation, and wherein secondnegative lens 114 is designed to aspheric surface with the rectification aberration, and the focal length of eachlens 114 offirst lens combination 110 and 116 necessary eligible (2).And insecond lens combination 120, the 5thpositive lens 124 and the 6thnegative lens 126 can be arranged in pairs or groups mutually with the rectification aberration, and the focal length of the 5thpositive lens 124 and the 6thnegative lens 126 necessary eligible (3).

In addition,tight shot 200 also includesaperture diaphragm 130, andaperture diaphragm 130 is arranged betweenfirst lens combination 110 and second lens combination 120.Other haswave filter 140 to be arranged betweensecond lens combination 120 and theimaging end 150.

For practicality and the advantage that shows tight shot of the present invention, below provide two embodiment, and expose every optical parametric and optical characteristics chart among these two embodiment according to above-mentioned condition design.

First embodiment

Table 1 has listed first lens combination of the tight shot of designing according to thepresent invention 100 and the parameters of second lens combination successively, wherein, S11 and S12 represent the thing end face and the imaging end face of first positive lens respectively, S21 and S22 represent the thing end face and the imaging end face of second negative lens respectively, S31 and S32 represent the thing end face and the imaging end face of the 3rd positive lens respectively, S41 and S42 represent the thing end face and the imaging end face of the 4th positive lens respectively, S51 and S52 represent the thing end face and the imaging end face of the 5th positive lens respectively, S61 and S62 represent the thing end face and the imaging end face of the 6th negative lens respectively, STO. beaperture diaphragm 130, FS1 and FS2 are the two sides of wave filter 140:

Other optical characteristics of tight shot first embodiment is then listed in the table 2:

As shown in Table 2, the 2Gf/1Gf parameter value of the tight shot of first embodiment is-0.529, eligible (1).(C1 f)/L3 f parameter value is 0.104, eligible (2).The L5f/L6f parameter value is-1.11, eligible (3).

In addition, second negative lens in first lens combination and the 4th positive lens in second lens combination are all non-spherical lens, and its non-spherical lens coefficient equation is as follows:

$z=\frac{c{h}^2}{1+{[1-(k+1)c^2{h}^2]}^{1/2}}+A{h}^4+B{h}^6+C{h}^8+D{h}^{10}$

Wherein z is the sag value of lens, that is the depression degree of lens face, and c is the inverse of radius-of-curvature, and h is that lens face arrives distance between optical axes, and k is circular cone coefficient (Conic Coefficient), and A, B, C and D then are respectively the high-order asphericity coefficient.Each aspheric high-order asphericity coefficient is listed in the table 3 in regular turn:

Then please refer to Fig. 2 A and Fig. 2 B, be respectively the curvature of field/distortion figure of tight shot first embodiment.Lambda1-wavelength among two figure is 486 rice (nm) how, Fig. 2 A is curvature of field figure, T among the figure represents the meridional ray (Tangential Ray) of incident light, S represents the sagittal ray (Sagittal Ray) of incident light, horizontal ordinate is expressed as the distance of picture point to desirable image planes, and ordinate is desirable image height or incident angle.Fig. 2 B is expressed as the percent difference of picture point to ideal point for distortion figure, horizontal ordinate, and ordinate is desirable image height or incident angle.Shown in Fig. 2 A and Fig. 2 B, the curvature of field of the tight shot of first embodiment and distortion situation are also not serious.

Please refer to Fig. 3 A to Fig. 3 F, represent respectively under the different image heights, wavelength is respectively 436,486,588 and 656 light fan-shaped (ray fan) figure of rice (nm) how.Wherein Fig. 3 A is respectively the result that 0,1.41,2.35,3.29,4.23 and 4.6 millimeter (mm) place of image height (IMA) gets to Fig. 3 F.Owing to have meridian and sagitta of arc two sides, so each image height all has two light sector diagrams, a corresponding meridian ellipse (PY and EY), a corresponding sagittal surface (PX and EX).According to the result of light sector diagram as can be known, the tight shot of first embodiment is under most situation, and its image error value all within the acceptable range.

Please refer to Fig. 4, be the synoptic diagram of longitudinal aberration.Be respectively 436,486,588 and 656 how under the light of rice at wavelength, the tight shot of first embodiment has good imaging effect.

Please refer to Fig. 5, be out of focus modulation transfer function (the Through Focus MTF) figure of tight shot.Wherein, spatial frequency (Spatial Frequency) is set at 100lp/mm.Skew and corresponding optical transfer function (Optical Transfer Function) result by focus can learn that the tight shot of first embodiment has good optical resolution.

The tight shot of first embodiment of the invention is the uniform distribution of tolerance susceptibility, thereby reduces cost.In addition, the part lens in the tight shot of the present invention adopt the aspherical mirror of plastic cement material, cooperate the design of optical parametric, make this tight shot have favorable imaging quality, also meet the consideration of cost simultaneously.And tight shot of the present invention is under the situation of the optical parametric that adopts first embodiment to disclose, and system's length overall only is 20.786 millimeters (mm), the optical system length overall of optical devices when having reduced practical application.

Second embodiment

Table 4 has listed first lens combination of the tight shot of designing according to thepresent invention 200 and the parameters of second lens combination successively, wherein, S11 ' and S12 ' represent the thing end face and the imaging end face of second negative lens respectively, S21 ' and S22 ' represent the thing end face and the imaging end face of the 3rd positive lens respectively, S31 ' and S32 ' represent the thing end face and the imaging end face of the 4th positive lens respectively, S41 ' and S42 ' represent the thing end face and the imaging end face of the 5th positive lens respectively, S51 ' and S52 ' represent the thing end face and the imaging end face of the 6th negative lens respectively, STO. beaperture diaphragm 130, FS1 and FS2 are the two sides of wave filter 140:

Other optical characteristics of tight shot second embodiment is then listed in the table 5:

As shown in Table 5, the 2Gf/1Gf parameter value of the tight shot of second embodiment is-0.39918, eligible (1).(C1 f)/L3 f parameter value is-0.4194, eligible (2).The L5f/L6f parameter value is-1.1169, eligible (3).

In addition, second negative lens in first lens combination and the 5th positive lens in second lens combination are all non-spherical lens, and its non-spherical lens coefficient equation is as follows:

$z=\frac{c{h}^2}{1+{[1-(k+1)c^2{h}^2]}^{1/2}}+A{h}^4+B{h}^6+C{h}^8+D{h}^{10}$

Wherein z is the sag value of lens, that is the depression degree of lens face, and c is the inverse of radius-of-curvature, and h is that lens face arrives distance between optical axes, and k is the circular cone coefficient, and A, B, C and D then are respectively the high-order asphericity coefficient.Each aspheric high-order asphericity coefficient is listed in the table 6 in regular turn:

Then please refer to Fig. 7 A and Fig. 7 B, be respectively the curvature of field/distortion figure of tight shot second embodiment.Lambda1-wavelength among two figure is 486 rice (nm) how, and Fig. 7 A is curvature of field figure, and the T among the figure represent meridional ray of incident light, and S represents the sagittal ray of incident light, and horizontal ordinate is expressed as the distance that picture point arrives desirable image planes, and ordinate is desirable image height or incident angle.Fig. 7 B is expressed as the percent difference of picture point to ideal point for distortion figure, horizontal ordinate, and ordinate is desirable image height or incident angle.Shown in Fig. 7 A and Fig. 7 B, the curvature of field of the tight shot of second embodiment and distortion situation are also not serious.

Please refer to Fig. 8 A to Fig. 8 F, represent respectively under the different image heights, wavelength is respectively 436,486, the 588 and 656 light sector diagrams of rice (nm) how.Wherein Fig. 3 A is respectively the result that 0,1.11,1.85,2.59,3.33 and 3.7 millimeter (mm) place of image height (IMA) gets to Fig. 3 F.Owing to have meridian and sagitta of arc two sides, so each image height all has two light sector diagrams, a corresponding meridian ellipse (PY and EY), a corresponding sagittal surface (PX and EX).According to the result of light sector diagram as can be known, the tight shot of second embodiment is under most situation, and its image error value all within the acceptable range.

Please refer to Fig. 9, be the synoptic diagram of longitudinal aberration.Be respectively 436,486,588 and 656 how under the light of rice at wavelength, the tight shot of second embodiment has good imaging effect.

Please refer to Figure 10 A and Figure 10 B, is out of focus modulation transfer function (the Through Focus MTF) figure of the tight shot of second embodiment.Wherein, among Figure 10 A, spatial frequency is set at 100lp/mm, and among Figure 10 B, spatial frequency is set at 200lp/mm.Skew and corresponding optical transfer function result by focus can learn that the tight shot of second embodiment has good optical resolution.

The tight shot of second embodiment of the invention is the uniform distribution of tolerance susceptibility, thereby reduces cost.In addition, the part lens in the tight shot of the present invention adopt the aspherical mirror of plastic cement material, cooperate the design of optical parametric, make this tight shot have favorable imaging quality, also meet the consideration of cost simultaneously.And tight shot of the present invention is under the situation of the optical parametric that adopts second embodiment to disclose, and system's length overall only is 18.47 millimeters (mm), the optical system length overall of optical devices when having reduced practical application.

Though the present invention discloses as above with embodiment; but it is not to be limitation of the invention; any those of ordinary skill in the art without departing from the spirit and scope of the present invention; can do various changes and retouching, so protection scope of the present invention is as the criterion with the appended scope that claim was defined.

Claims (9)

1. a tight shot is characterized in that, is comprised successively on optical axis by thing end to imaging end:

First lens combination with negative refractive index, described first lens combination includes the plastic cement negative lens, and at least one surface of described plastic cement negative lens is an aspheric surface;

Second lens combination with positive refractive index, described second lens combination includes the plastic cement positive lens, and at least one surface of described plastic cement positive lens is an aspheric surface;

And described tight shot satisfies following condition:

-1＜2Gf/1Gf＜0

Wherein 1Gf is the focal length of described first lens combination, and 2Gf is the focal length of described second lens combination.

2. tight shot as claimed in claim 1 is characterized in that, described first lens combination also inclusion is rectified lens and terminal positive lens, and proper lens of described thing and terminal positive lens are separately positioned on the both sides of described plastic cement negative lens.

3. tight shot as claimed in claim 2 is characterized in that, described first lens combination satisfies following condition:

-0.5＜(C1f/L3f)＜0.5

Wherein C1f is the synthetic focal length that described thing is rectified lens and described plastic cement negative lens, and L3f is the focal length of described terminal positive lens.

4. tight shot as claimed in claim 1 is characterized in that, described second lens combination also comprises central positive lens and imaging end negative lens, and described central positive lens is arranged between described plastic cement positive lens and the described imaging end negative lens.

5. tight shot as claimed in claim 4 is characterized in that, described second lens combination satisfies following condition:

-1.5＜(L5f/L6f)＜-0.5

Wherein L5f is the focal length of described central positive lens, and L6f is the focal length of described imaging end negative lens.

6. tight shot as claimed in claim 1 is characterized in that described tight shot also includes aperture diaphragm, and described aperture diaphragm is between described first lens combination and described second lens combination.

7. tight shot as claimed in claim 1 is characterized in that described tight shot also includes wave filter, and described wave filter is between described second lens combination and imaging end.

8. tight shot as claimed in claim 1 is characterized in that, described first lens combination also comprises terminal positive lens, and described terminal positive lens is arranged on the imaging end of described plastic cement negative lens.

9. tight shot as claimed in claim 8 is characterized in that, described first lens combination satisfies following condition:

-0.5＜(C1f/L3f)＜0.5

Wherein C1f is the focal length when comprising described plastic cement negative lens and not comprising described terminal positive lens, and L3f is the focal length of described terminal positive lens.

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