CN100520474C - Minisized imaging lens - Google Patents

Abstract

The invention discloses a micro view-finding lens which comprises a first aspheric surface lens with positive diopter and a second aspheric surface with negative diopter, wherein the first lens is a lunes lens projecting to the imaging plane, which includes the concave plane against to the object and the convex plane opposite to the imaging plane for enlarging light beam on the concave plane and getting larger area on the convex plane to correct image difference and low error sensitivities. The second lens is a negative lens which employs aspheric design to compensate color difference, correct positive axle image difference and shorten the general length of the optical system.

Description

Minisize image acquisition lens

[technical field]

The present invention relates to a kind of minisize image acquisition lens, especially mean a kind ofly to constitute, be adapted at the short and small minisize image acquisition lens of high-performance, low cost and size that uses in mobile phone, the slim digital camera by less eyeglass.

[background technology]

Mobile data device such as mobile phone, PDA(Personal Digital Assistant) and photoelectric technology are integrated has become one of trend of current development in science and technology, and camera mobile phone is the typical case's representative in this technology trend.With regard to design, for easy to carry and meet the hommization requirement, the sampling image lens of camera mobile phone not only needs to have favorable imaging quality, also needs smaller volume and lower cost.Therefore, different with adjustable focus, the Varifocal zoom lens of traditional camera, video camera and general digital camera, employed sampling image lens size is much smaller in the camera mobile phone, and structure is also simple a lot, and mainly is based on tight shot.Eyeglass form and material at sampling image lens are selected, because the selection of the material of traditional sphere abrading glass eyeglass is more, it is comparatively favourable for correcting chromatic aberration, and widely industry is used.But when sphere abrading glass eyeglass was used in less and visual angle (Wide-angle) the bigger situation of numerical aperture (F Number), the correction of aberrations such as spherical aberration and astigmatism is difficulty still.In order to improve the defective of sphere abrading glass eyeglass in the conventional lenses, industry employing aspheric surface glass lens or aspheric surface modeling glass lens are as the optical module of capture eyeglass, to obtain preferable image quality.For effective aberration correction, sampling image lens normally is made of the multiple lens group, and for example United States Patent (USP) announces the 6th, 031, the sampling image lens structure that is disclosed for No. 670.But this type of is longer relatively by the sampling image lens overall dimensions that the poly-lens group constitutes, required installing space is bigger, is unaccommodated at 20mm for gauge for camera heads such as interior mobile phone or slim digital camera, because both being difficult to pack into, this type of camera lens in the mobile phone mechanism part, also increased and increased the weight of the weight of final products owing to eyeglass too much causes cost.

In addition, United States Patent (USP) the 6th, 441, the minisize image acquisition lens that a kind of suitable camera mobile phone that discloses for 971 B2 numbers uses, it is the prismatic glasses configuration that adopts a glass mirror to combine with two glass lens, and aperture placed first eyeglass the place ahead, can make that the assembly of aperture or shutter and eyeglass is irrelevant, and elongate emergent pupil (Exit Pupil) position.First eyeglass major function near aperture taken imaging as the leading factor, provide refracting power (Power), and second and third sheet eyeglass will provide not only refracting power with focal imaging, more needs to revise various aberrations to obtain preferable imaging image quality.Yet under this kind form, the face core shift is very responsive mostly, and the form that a glass mirror adds two glass lens not only loses competitive power on price factor, also makes that the entire length of camera lens is still longer, and weight is also still heavier because of containing glass mirror.Therefore, this type of micro-lens still has necessity of further improvement design.

[summary of the invention]

The object of the present invention is to provide a kind of minisize image acquisition lens, the less number of lenses of this camera lens and compact conformation, Lens and weight reduction have been dwindled, have with great visual angle, large aperture numerical value and low sensitivity, and the effectively aberration correction and the curvature of field, help saving cost and improve the applicability of sampling image lens on the portable electronic image-taking device.

The object of the invention can be achieved through the following technical solutions: a kind of minisize image acquisition lens, it comprises first eyeglass and negative dioptric second eyeglass of positive diopter from the object side to the image side successively, this first eyeglass includes first second of reaching in the face of imaging surface in the face of subject, this second eyeglass includes the 3rd fourth face that reaches in the face of imaging surface in the face of subject, wherein this first face is the concave surface that is the configuration that caves in respect to subject, second face is to be the convex surface that protrudes configuration with respect to imaging surface, and this is first years old, have at least one side to be aspheric surface, the 3rd in two, also have at least one side to be aspheric surface in the four sides.

Above-mentioned minisize image acquisition lens, it satisfies following relational expression:

$0.6<-\frac{f_1}{{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="C200510075667E00121.png,C200510075667E00131.png"\; state="\{\{state\}\}">f</figure-callout>}}_2}<1.2---(a-1)$

Among the formula a-1, f ₁Be the optical focal length of first eyeglass, f ₂It is the optical focal length of second eyeglass.

Above-mentioned minisize image acquisition lens, wherein first of first eyeglass and second face are aspheric surface.

Above-mentioned minisize image acquisition lens, wherein first of first eyeglass and second is satisfied following condition:

$0.1<\frac{S_1}{{\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="C200510075667E00121.png,C200510075667E00131.png"\; state="\{\{state\}\}">S</figure-callout>}}_2}\&CenterDot;F_{\mathrm{NO}}<0.3---(a-2)$

Among the formula a-2, S ₁Be the amount of bow of first maximum diameter of hole, S ₂Be the amount of bow of second maximum diameter of hole, F _NOBe stop opening numerical value.

Above-mentioned minisize image acquisition lens, wherein the 3rd of second of first eyeglass and second eyeglass is satisfied following condition:

$0.45<\frac{R_2}{{\mathrm{<figure-callout\; id="3"\; label="R"\; filenames="C200510075667E00121.png,C200510075667E00131.png"\; state="\{\{state\}\}">R</figure-callout>}}_3}<0.95---(a-3)$

Among the formula a-3, R ₂Be second radius-of-curvature of first eyeglass, R ₃It is the 3rd radius-of-curvature of second eyeglass.

Above-mentioned minisize image acquisition lens wherein is provided with aperture between first of first eyeglass and the subject.

In the above-mentioned minisize image acquisition lens, the aspheric surface of first and second eyeglass can be by following aspheric surface equation expression:

$z=\frac{{\mathrm{<figure-callout\; id="2"\; label="ch"\; filenames="C200510075667E00121.png,C200510075667E00131.png"\; state="\{\{state\}\}">ch</figure-callout>}}^2}{1+{[1-(k+1)c^2{h}^2]}^{\frac{1}{2}}}+{\mathrm{<figure-callout\; id="4"\; label="Ah"\; filenames="C200510075667E00121.png,C200510075667E00131.png"\; state="\{\{state\}\}">Ah</figure-callout>}}^4+{\mathrm{Bh}}^6+{\mathrm{Ch}}^8+{\mathrm{Dh}}^{10}+{\mathrm{<figure-callout\; id="12"\; label="Eh"\; filenames="C200510075667E00121.png,C200510075667E00131.png"\; state="\{\{state\}\}">Eh</figure-callout>}}^{12}+{\mathrm{Fh}}^{14}+{\mathrm{Gh}}^{16}$

Compared with prior art, minisize image acquisition lens of the present invention adopts positive and negative two aspherical lens, first eyeglass is protruding semilune eyeglass to imaging surface, can make incident beam at first with regard to wealthy bundle, thereby make the light beam bigger area that on second, can distribute, so can give full play to aspheric function, correct aberration and lower the tolerance susceptibility.Second eyeglass is a negative lens, and its major function is compensate for chromatic aberration and corrects off-axis aberration, adopts the aspheric surface design also to help to shorten the length overall of lens optical system except rectifiable aberration.And first and second eyeglass all can adopt plastic material, helps eliminating aberration and alleviates camera lens weight.Whole optical system of the present invention is only used two glass lens, can reduce the cost, and is fit to a large amount of production, and its compact conformation, and the tolerance susceptibility is low, is easy to make assembly, meets the requirement of scale of mass production.

[description of drawings]

Fig. 1 is the optical structure chart of minisize image acquisition lens of the present invention.

Fig. 2 is the optical structure chart of minisize image acquisition lens of the present invention according to the first numerical value embodiment.

Fig. 3 A is the longitudinal spherical aberration performance figure of the first numerical value embodiment of the present invention.

Fig. 3 B is the curvature of field performance figure of the first numerical value embodiment of the present invention.

Fig. 4 is the optical structure chart of minisize image acquisition lens of the present invention according to second value embodiment.

Fig. 5 A is the longitudinal spherical aberration performance figure of second value embodiment of the present invention.

Fig. 5 B is the curvature of field performance figure of second value embodiment of the present invention.

Fig. 6 is the optical structure chart of minisize image acquisition lens of the present invention according to third value embodiment.

Fig. 7 A is the longitudinal spherical aberration performance figure of third value embodiment of the present invention.

Fig. 7 B is the curvature of field performance figure of third value embodiment of the present invention.

[embodiment]

Be illustrated in figure 1 as the optical structure chart of minisize image acquisition lens of the present invention, this minisize image acquisition lens comprises first eyeglass 1 and negative dioptric second eyeglass 2 of positive diopter from the object side to the image side successively, after making light see through first eyeglass 1 and second eyeglass 2, focus on a CCD (Charge Coupled Device, Charged Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor, CMOS (Complementary Metal Oxide Semiconductor)) on the image sensor 4 (imaging surface), and obtains blur-free imaging.Wherein, this first eyeglass 1 comprises first 11 second 12 of reaching in the face of imaging surface in the face of subject, this first 11 is the concave surfaces that are the configuration that caves in respect to subject, second 12 is to be the convex surface that protrudes configuration with respect to imaging surface, and make this first eyeglass 1 be semilune, and have at least in first and second face 11,12 one side be aspheric surface.In addition, second eyeglass 2 also comprises the 3rd 21 fourth face 22 that reaches in the face of imaging surface in the face of subject, wherein the 3rd 21 is the concave surfaces that are the configuration that caves in respect to subject, fourth face 22 then is to be the concave surface that falls into configuration with respect to imaging surface, and to have one side in this third and fourth face 21,22 at least be aspheric surface.Be provided with a glass cover-plate 3 between second eyeglass 2 and imaging surface 4, aperture 5 then is arranged on first eyeglass, 1 the place ahead, promptly between first 11 and the subject.Aperture places the forefront of system, can make emergent pupil (Exit Pupil) position of optical system elongated.

In the minisize image acquisition lens of the present invention, first eyeglass 1 and second eyeglass 2 satisfy following formula:

$0.6<-\frac{f_1}{{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="C200510075667E00121.png,C200510075667E00131.png"\; state="\{\{state\}\}">f</figure-callout>}}_2}<1.2---(a-1)$

Among the formula a-1, f ₁Be the optical focal length of first eyeglass 1, f ₂It is the optical focal length of second eyeglass 2.Work as f ₁/ f ₂Ratio reach in limited time, defocus (Defocus) significantly.Prescribe a time limit when this value reaches down, it is littler that Po Zi cuts down radius (Petzval Radius), and off-axis aberration more is difficult to correct.

Understand easily, in the minisize image acquisition lens of the present invention, first 11 and second 12 of first eyeglass 1 all can be designed to aspheric surface.Because first 11 is concave surface, can make incident beam at this first 11 with regard to wealthy bundle, make light beam at the convex surface of this first eyeglass 1 bigger area that promptly distributes on second 12, all be designed to aspheric surface as first 11 and second 12, then the semilune of this first eyeglass 1 structure can be given full play to aspheric function, corrects aberration and lowers the tolerance susceptibility.

When first 11 and second 12 of first eyeglass 1 were aspheric surface, these first 11 and second 12 were satisfied following condition:

$0.1<\frac{S_1}{{\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="C200510075667E00121.png,C200510075667E00131.png"\; state="\{\{state\}\}">S</figure-callout>}}_2}\&CenterDot;F_{\mathrm{NO}}<0.3---(a-2)$

Among the formula a-2, S ₁Be the amount of bow of first 11 maximum diameter of hole, S ₂Be the amount of bow of second 12 maximum diameter of hole, F _NOBe stop opening numerical value.When this value reaches in limited time,, produce the smear phenomenon of luminous point from the difficult rectification of the last light beam of axle.Prescribe a time limit when this value reaches down, it is big that aperture aberration becomes, as aperture numerical value (F _NO) greater than 4 when above, and not obvious, however in order to obtain enough lights, at present mobile phone on the market with camera lens extremely mostly aperture numerical value be 2.8 or 3.2.

The 3rd 21 of second eyeglass 2 of minisize image acquisition lens of the present invention and fourth face 22 also can be designed to aspheric surface, so that minisize image acquisition lens obtains preferable aberration correction.Wherein, second of the 3rd of second eyeglass the and first eyeglass is satisfied following condition:

$0.45<\frac{R_2}{{\mathrm{<figure-callout\; id="3"\; label="R"\; filenames="C200510075667E00121.png,C200510075667E00131.png"\; state="\{\{state\}\}">R</figure-callout>}}_3}<0.95---(a-3)$

Among the formula a-3, R ₂Be second radius-of-curvature of first eyeglass, R ₃It is the 3rd radius-of-curvature of second eyeglass.When this value reaches in limited time, can cause serious interior the bending of the curvature of field (Field Curvature).Prescribe a time limit when this value reaches down, astigmatism (Astigmatism) can be difficult to correct.

First and second eyeglass 1,2 is if adopt spheric glass, then need sufficiently long space and complex optics is set correcting aberration, so the present invention adopts aspherical lens, can reduce the eyeglass number of camera lens and reduce the camera lens length overall.Wherein, aspheric type can be used following formulate:

$z=\frac{{\mathrm{<figure-callout\; id="2"\; label="ch"\; filenames="C200510075667E00121.png,C200510075667E00131.png"\; state="\{\{state\}\}">ch</figure-callout>}}^2}{1+{[1-(k+1)c^2{h}^2]}^{\frac{1}{2}}}+{\mathrm{<figure-callout\; id="4"\; label="Ah"\; filenames="C200510075667E00121.png,C200510075667E00131.png"\; state="\{\{state\}\}">Ah</figure-callout>}}^4+{\mathrm{Bh}}^6+{\mathrm{Ch}}^8+{\mathrm{Dh}}^{10}+{\mathrm{<figure-callout\; id="12"\; label="Eh"\; filenames="C200510075667E00121.png,C200510075667E00131.png"\; state="\{\{state\}\}">Eh</figure-callout>}}^{12}+{\mathrm{Fh}}^{14}+{\mathrm{Gh}}^{16}$

Wherein, z be along optical axis direction highly for the position of h with the surface vertices shift value apart from optical axis for referencial use; K is the tapering constant; C is the inverse of radius-of-curvature; A, B, C, D, E, F, G are the high-order asphericity coefficient.

Based on aforementioned technology contents of the present invention, can specifically implement according to following numerical value embodiment:

The first numerical value embodiment:

The concrete numerical value such as the following table of asphericity coefficient are listed:

According to aforementioned a-1, a-2 and a-3 formula, comply with the correlated performance index such as the following table of the minisize image acquisition lens of opening first numerical value embodiment enforcement:

-f 1/f 2	0.769
		S 1*F NO/S 2	0.215
R 2/R 3	0.674
		F NO	2.84
Focal length (Focal length)	2.48mm

See also shown in Figure 2, the minisize image acquisition lens of the present invention that the above-mentioned first numerical value embodiment of foundation is implemented, wherein 1 first on first eyeglass and second face are aspheric surface, the 3rd of second eyeglass 2 and fourth face also are aspheric surfaces, the focal length of camera lens is 2.48mm, stop opening numerical value is 2.84, and the numerical value of aforementioned a-1 formula, a-2 formula and a-3 formula is respectively :-f ₁/ f ₂=0.769, S ₁* F _NO/ S ₂=0.215, R ₂/ R ₃=0.674.The present invention is according to the longitudinal spherical aberration performance of the minisize image acquisition lens of first numerical value embodiment acquisition as shown in Figure 3A, and the curvature of field performance shown in Fig. 3 B shows that the present invention has the good optical performance according to the minisize image acquisition lens that the first numerical value embodiment implements.

Minisize image acquisition lens of the present invention also can specifically be implemented according to following second value embodiment:

The concrete numerical value such as the following table of asphericity coefficient are listed:

According to aforementioned a-1, a-2 and a-3 formula, comply with the correlated performance index such as the following table of the minisize image acquisition lens of above-mentioned second value embodiment enforcement:

-f 1/f 2	0.763
		S 1*F NO/S 2	0.243
R 2/R 3	0.657
		F NO	2.84
Focal length (Focal length)	2.48mm

See also shown in Figure 4, the minisize image acquisition lens of the present invention that the above-mentioned second value embodiment of foundation is implemented, wherein 1 first on first eyeglass and second face are aspheric surface, the 3rd of second eyeglass 2 and fourth face also are aspheric surfaces, the focal length of camera lens is 2.48mm, stop opening numerical value is 2.84, and the numerical value of aforementioned a-1 formula, a-2 formula and a-3 formula is respectively :-f ₁/ f ₂=0.763, S ₁* F _NO/ S ₂=0.243, R ₂/ R ₃=0.657.See also the present invention shown in Fig. 5 A according to the longitudinal spherical aberration performance of the minisize image acquisition lens of second value embodiment acquisition and the curvature of field performance shown in Fig. 5 B, show that the present invention has the good optical performance according to the minisize image acquisition lens that second value embodiment implements.

Minisize image acquisition lens of the present invention also can specifically be implemented according to following third value embodiment:

The concrete numerical value such as the following table of asphericity coefficient are listed:

According to aforementioned a-1, a-2 and a-3 formula, comply with the correlated performance index such as the following table of the minisize image acquisition lens of above-mentioned third value embodiment enforcement:

-f 1/f 2	0.913
		S 1*F NO/S 2	0.164
R 2/R 3	0.847
		F NO	3.0
Focal length (Focal length)	2.51mm

See also shown in Figure 6, the minisize image acquisition lens of the present invention that the above-mentioned third value embodiment of foundation is implemented, wherein 1 first on first eyeglass and second face are aspheric surface, the 3rd of second eyeglass 2 and fourth face also are aspheric surfaces, the focal length of camera lens is 2.51mm, stop opening numerical value is 3.0, and the numerical value of aforementioned a-1 formula, a-2 formula and a-3 formula is respectively :-f ₁/ f ₂=0.913, S ₁* F _NO/ S ₂=0.164, R ₂/ R ₃=0.847.See also the present invention shown in Fig. 7 A according to the longitudinal spherical aberration performance of the minisize image acquisition lens of third value embodiment acquisition and the curvature of field performance shown in Fig. 7 B, show that the present invention has the good optical performance according to the minisize image acquisition lens that third value embodiment implements.

Minisize image acquisition lens of the present invention adopts positive and negative two aspherical lens, first eyeglass 1 is protruding semilune eyeglass to imaging surface, can make incident beam at first 11 with regard to wealthy bundle, thereby make the light beam bigger area that on second 12, can distribute, so can give full play to aspheric function, correct aberration and lower the tolerance susceptibility.Second eyeglass 2 is a negative lens, and its major function is compensate for chromatic aberration and corrects off-axis aberration, adopts the aspheric surface design also to help to shorten the length overall of lens optical system except rectifiable aberration.And first and second eyeglass 1,2 all can adopt plastic material, helps eliminating aberration and alleviates camera lens weight.Whole optical system of the present invention is only used two glass lens, can reduce the cost, and is fit to a large amount of production, and its compact conformation, and the tolerance susceptibility is low, is easy to make assembling, meets the requirement of scale of mass production.

Claims (7)

1. minisize image acquisition lens, it is characterized in that: it comprises first eyeglass and second eyeglass from subject one side successively to imaging surface one side, wherein first eyeglass includes first second of reaching in the face of imaging surface in the face of subject, described first face is the concave surface that is the configuration that caves in respect to subject, second face is to be the convex surface that protrudes configuration with respect to imaging surface, and first of described first eyeglass and second face are aspheric surface and full $0.1<\frac{S_1}{S_2}\&CenterDot;F_{\mathrm{NO}}<0.3$ This conditional, wherein S ₁Be the amount of bow of first maximum diameter of hole, S ₂Be the amount of bow of second maximum diameter of hole, F _NOBe stop opening numerical value; Second eyeglass is a negative dioptric eyeglass, and it includes in the face of the 3rd of subject and in the face of the fourth face of imaging surface, and to have one side in described third and fourth face at least be aspheric surface.

2. minisize image acquisition lens as claimed in claim 1 is characterized in that: described first eyeglass and second eyeglass satisfy following relational expression:

$0.6<-\frac{f_1}{f_1}<1.2$

In the following formula, f ₁Be the optical focal length of first eyeglass, f ₂It is the optical focal length of second eyeglass.

3. minisize image acquisition lens as claimed in claim 2 is characterized in that: the 3rd face of described second eyeglass is an aspheric surface.

4. minisize image acquisition lens as claimed in claim 3 is characterized in that: satisfy following condition between second of the 3rd of described second eyeglass and first eyeglass:

$0.45<\frac{R_2}{R_3}<0.95$

In the following formula, R ₂Be second radius-of-curvature of first eyeglass, R ₃It is the 3rd radius-of-curvature of second eyeglass.

5. minisize image acquisition lens as claimed in claim 4 is characterized in that: the fourth face of described second eyeglass is an aspheric surface.

6. minisize image acquisition lens as claimed in claim 5 is characterized in that: described aspheric type satisfies following formula:

$z=\frac{{\mathrm{ch}}^2}{1+{[1-(k+1)c^2{h}^2]}^{\frac{1}{2}}}+{\mathrm{Ah}}^4+{\mathrm{Bh}}^6+{\mathrm{Ch}}^8+{\mathrm{Dh}}^{10}+{\mathrm{Eh}}^{12}+{\mathrm{Fh}}^{14}+{\mathrm{Gh}}^{16}$

Wherein, z be along optical axis direction highly for the position of h with the surface vertices shift value apart from optical axis for referencial use; K is the tapering constant; C is the inverse of radius-of-curvature; A, B, C, D, E, F, G are the high-order asphericity coefficient.

7. minisize image acquisition lens as claimed in claim 1 is characterized in that: be provided with aperture between first of described first eyeglass and the subject.

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