CN101201448A - Microminiature lens - Google Patents

Abstract

The invention provides a micro lens. The lens from an object side to an image side is that a first lens is a crescentiform positive lens with a convex side toward the object side, which is mainly used for the interception of image and the balance of aberration; a second lens is a negative lens, which is mainly used for the compensation of color difference and the correction of off-axis aberration; a third lens is a positive lens, which is used to provide the main refractive power in the lens optical system and affect the main focus of the optical system; a fourth lens is a crescentiform negative lens with a concave side toward the object side. The curvature of both sides of the fourth lens is small; the shape of both sides of the fourth lens is quite bended; the effective optical radius is reduced through the characteristics; therefore, not only the whole total optical length is very short; the size can also be decreased; the curvature of both sides of the fourth lens shows a special relationship with the whole optical system. The micro lens of the invention can both satisfy the demand of analyzing degree and provide high imaging quality with a low cost and light quality.

Description

Microminiature lens

Technical field

The present invention relates to a kind of microminiature lens, particularly a kind of microminiature lens that is applicable on the portable electronic apparatus.

Background technology

Along with the continuous development of science and technology, portable electronic apparatus is integrated one of trend that has become current development in science and technology mutually with photoelectric technology as notebook computer, mobile phone or PDA(Personal Digital Assistant) etc., and camera mobile phone is the typical case's representative in this technology trend.The sampling image lens of camera mobile phone not only needs to have favorable imaging quality, also needs smaller volume and lower cost.

What early stage lens design adopted is spherical lens, but because of spherical lens unavoidably can produce aberration, as optical defects such as chromatic dispersions on spherical aberration, the axle, it is burnt to cause image fog to be lost, and for overcoming those aberrations, lens design person must use a lot of sheet lens to compensate in camera lens.Thereby when image quality improves, all corresponding increase of the length of camera lens, external diameter, weight and cost, thus make camera lens become not only big but also heavy.Yet various in recent years digitized video products all develop towards the direction of microminiaturization, but and the taking lens that is complementary with it also just must be more and more littler, promptly the length overall of camera lens will further shorten, therefore above-mentioned design concept can't be used again.

In order to reduce camera lens volume and manufacturing cost, the employing non-spherical lens that has in the present lens design.Non-spherical lens can be avoided because of adopting the spherical aberration that spherical lens produced, and a slice non-spherical lens can substitute several spherical lens aberration for compensation, can simplify the optical design of camera lens very significantly, reduces its volume and weight.

No matter be spherical mirror or aspheric mirror, it is made material and mainly contains glass and plastic cement.In the traditional design theory, if the camera lens of using as capture adopts glass material, because of the light-transmission coefficient of glass lens is bigger, imaging effect is good, but price is higher, so be mainly used in high-end product; If adopt plastic cement material, then less, cheap because of the light-transmission coefficient of plastic cement lens, so be mainly used in low-end product.But because of plastic cement material is light, and glass material is more thick and heavy, so can adopt plastic cement lens and the combined mode of glass lens when lens design, learns from other's strong points to offset one's weaknesses whereby, thereby designs needed camera lens.

Mobile lens in the market adopts the combination of glass and plastic cement lens mostly, as 1G (Glass, glass) 2P (Plastic, plastic cement) or the pattern of 1G3P, wherein the lens design pattern of 1G2P can be with reference to United States Patent (USP) the 6th, 441, the camera lens that is disclosed for No. 971, it to picture side, includes first lens from object space successively, second lens and the 3rd lens, first lens adopt the spherical glass eyeglass, second, the 3rd lens adopt the plastic cement aspherical lens, though this camera lens volume is less, be only applicable to the following image sensor of 640*480 pixel, so can't satisfy current growing higher pixel requirement.Though and existing 1G3P lens design pattern can reach higher pixel request, its weight, cost are still higher.

In view of above shortcoming, be necessary very much to provide the microminiature lens that a kind of cost is low, susceptibility is low and image quality is high.

Summary of the invention

The technical problem to be solved in the present invention is, at the above-mentioned deficiency of prior art, provides a kind of microminiature lens with low cost, low tolerance susceptibility and high-res characteristics.

The technical solution adopted for the present invention to solve the technical problems is, a kind of microminiature lens is provided, comprise successively to picture side from object space: have positive diopter first lens, aperture, have dioptric second lens of bearing, have the 3rd lens of positive diopter and have dioptric the 4th lens of bearing, wherein the 3rd lens and the 4th lens respectively have at least one aspheric surface, and described microminiature lens satisfies following condition:

$0.2<\frac{f3}{F}<1.3---\left(1\right)$

In formula (1), f3 represents the effective focal length of the 3rd lens, and F represents the effective focal length of entire system.

In the microminiature lens of the present invention, described first to fourth lens all can be the plastic cement lens, and first to fourth lens all can be double surface non-spherical lens.

Above-mentioned second lens are double-concave negative lens; First lens are the meniscus lens, and its convex surface is towards object space; The 4th lens are the meniscus lens, and its concave surface is towards object space.

Above-mentioned microminiature lens also need satisfy following condition:

$0.02<\frac{\left|R9\right|-\left|R8\right|}{F}<0.4---\left(2\right)$

In formula (2), R8 is the radius-of-curvature on the surface that is close to object space of the 4th lens, and R9 is the radius-of-curvature on the surface that is close to picture side of the 4th lens, and F represents the effective focal length of entire system.

The Image Sensor that above-mentioned microminiature lens also is provided with sheet glass and is positioned at the image space place in the picture side of described the 4th lens side.

The present invention solves another technical scheme that its technical matters adopts, a kind of microminiature lens is provided, comprise successively to picture side from object space: have positive diopter first lens, aperture, have dioptric second lens of bearing, have the 3rd lens of positive diopter and have dioptric the 4th lens of bearing, wherein the 3rd lens and the 4th lens respectively have at least one aspheric surface, and second lens are double-concave negative lens.

Above-mentioned microminiature lens need satisfy following condition:

$0.2<\frac{f3}{F}<1.3---\left(1\right)$

In formula (1), f3 represents the effective focal length of the 3rd lens, and F represents the effective focal length of entire system.

Above-mentioned microminiature lens also need satisfy following condition:

$0.02<\frac{\left|R9\right|-\left|R8\right|}{F}<0.4---\left(2\right)$

In formula (2), F represents the effective focal length of entire system, and R8 is the radius-of-curvature on the surface that is close to object space of the 4th lens, and R9 is the radius-of-curvature on the surface that is close to picture side of the 4th lens.

In the above-mentioned microminiature lens, described first lens are the meniscus lens, and its convex surface is towards object space; Described the 4th lens are the meniscus lens, and its concave surface is towards object space.

In the above-mentioned microminiature lens, described first to fourth lens all can be the plastic cement lens, and described first to fourth lens all can be double surface non-spherical lens.

The beneficial effect of implementing microminiature lens of the present invention is: microminiature lens of the present invention both can satisfy the high-res requirement, and very high image quality is provided, and cost is low, in light weight.Compared with prior art, the 3rd lens of microminiature lens of the present invention have satisfied a design conditions, make that the length overall of microminiature lens shortens, low, the low cost of manufacture of tolerance susceptibility.And the present invention's the 4th lens have satisfied another design conditions, thereby make microminiature lens of the present invention can access optical quality preferably.Second lens of microminiature lens of the present invention are double-concave negative lens, and its rectification for the Chromatically compensated and off-axis aberration of whole lens system provides main effect.In addition, four lens of the present invention can also all adopt plastic cement materials, not only cost reduce significantly, weight saving, also can satisfy the requirement of high-res simultaneously, move whole camera lens and can obtain the far and near very clearly image quality of taking all.

Description of drawings

Fig. 1 is the structural representation of a preferred embodiment of microminiature lens of the present invention;

Fig. 2 A is the curve synoptic diagram of microminiature lens of the present invention according to the formed longitudinal spherical aberration of the first numerical value embodiment;

Fig. 2 B is the curve synoptic diagram of microminiature lens of the present invention according to the formed image field depression of the first numerical value embodiment;

Fig. 2 C is the curve synoptic diagram of microminiature lens of the present invention according to the formed lateral chromatic aberration of the first numerical value embodiment;

Fig. 3 A is the curve synoptic diagram of microminiature lens of the present invention according to the formed longitudinal spherical aberration of second value embodiment;

Fig. 3 B is the curve synoptic diagram of microminiature lens of the present invention according to the formed image field depression of the first numerical value embodiment;

Fig. 3 C is the curve synoptic diagram of microminiature lens of the present invention according to the formed lateral chromatic aberration of the first numerical value embodiment.

The main element symbol description:

Microminiature lens 1 first lens 10

Aperture 80 second lens 20

The 3rd lens 30 the 4th lens 40

Parallel-plate 50 imaging surfaces 60

Embodiment

As shown in Figure 1, microminiature lens 1 in the one embodiment of the invention comprises from the object side to the image side successively: first lens 10, aperture 80, second lens 20, the 3rd lens 30, the 4th lens 40, parallel-plate 50 and imaging surface 60, wherein first lens 10 are the meniscus positive lens, its convex surface is towards object space, be mainly used in intercepting image and balance aberration, make whole optical system be in low tolerance susceptibility; Aperture 80 is positioned between first lens 10 and second lens 20, thus can so that the exit pupil position move towards the thing end; Second lens 20 are double-concave negative lens, and its rectification for the Chromatically compensated and off-axis aberration of whole lens system provides main effect; The 3rd lens 30 are positive lens, have at least one aspheric surface, and it can provide lens optical system main refracting power, and affect total focal length of this optical system, and relation between the two is detailed later; The 4th lens 40 are the meniscus negative lens, and it has at least one aspheric surface, whereby can be so that light accurately is gathered on the imaging surface, and be used to correct off-axis aberration (astigmatism and distortion etc.).The concave surface of the 4th lens 40 is towards object space, the curvature on its two sides is bigger, shape is quite crooked, this characteristic makes the optics effective diameter diminish, therefore not only whole optics length overall is very short, and size also can diminish, and the whole optical system of the refracting power of the 4th lens 40 and microminiature lens 1 there is no relation clearly, but the curvature on the 4th lens 40 two sides presents special relationship with whole optical system, and its relation is detailed later; Parallel-plate 50 is a sheet glass, and it has at least a coating surface to have one deck to have the film of certain effect (for example: antireflection or infrared ray filter), thereby improves image quality; Imaging surface 60 is the surface of Image Sensor; it is positioned at the image aspect and puts; this Image Sensor is generally charge-coupled device (CCD) (Charge Coupled Device; be called for short CCD) or CMOS (Complementary Metal Oxide Semiconductor) (Complementary Metal-Oxide Semiconductor is called for short CMOS); generally speaking; in mobile phone,, can adopt cmos element usually because of cost consideration.

For reaching the purpose of short and small length overall, low tolerance susceptibility and high-res, microminiature lens 1 of the present invention need meet the following conditions:

$0.2<\frac{f3}{F}<1.3---\left(1\right)$

In above-mentioned formula (1), f3 represents the effective focal length of the 3rd lens 30, and F represents the effective focal length of entire system.In formula (1), when the ratio of the effective focal length of the effective focal length of the 3rd lens 30 and entire system during greater than the upper limit (promptly 1.3), microminiature lens 1 length overall is elongated, so do not meet the requirement of microminiature lens; When this ratio during less than lower limit (promptly 0.2), the 3rd lens 30 will bear the most focusing force of system, thereby cause the 3rd lens 30 susceptibilitys significantly to increase, and its limit is thick simultaneously also a deficiency, is difficult for producing.

For obtaining better image quality, microminiature lens 1 of the present invention also need meet the following conditions:

$0.02<\frac{\left|R9\right|-\left|R8\right|}{F}<0.4---\left(2\right)$

In above-mentioned formula (2), F represents the effective focal length of entire system, and R8 is the radius-of-curvature on the surface that is close to object space of the 4th lens 40, and R9 is the radius-of-curvature on the surface that is close to picture side of the 4th lens 40.In formula (2), when the ratio of the effective focal length of the radius-of-curvature difference on two surfaces of the 4th lens 40 and entire system during greater than the upper limit (promptly 0.4), the off-axis aberration of microminiature lens 1 will be difficult for correcting, and especially distortion is too big; When this ratio during less than lower limit (promptly 0.02), the degree of crook of the 4th lens 40 will be too big and be difficult for producing.

In a word, microminiature lens 1 of the present invention has with great visual angle (being about 60 degree), large aperture numerical value (about 1: 2.8), the low susceptibility of making reaches characteristics cheaply.Microminiature lens 1 of the present invention is made up of above-mentioned four lens, these lens can also all adopt plastic cement material, not only cost reduce significantly, weight saving, also can satisfy the requirement of high-res simultaneously, move whole camera lens and can obtain the far and near very clearly image quality of taking all.

The 3rd lens 30 and the 4th lens 40 of microminiature lens 1 of the present invention all have an aspheric surface at least, and it satisfies following aspheric surface formula:

$z=\frac{{\mathrm{ch}}^2}{1+[1-(k+1)c^2{h}^2{]}^{1/2}}+{\mathrm{Ah}}^4+{\mathrm{Bh}}^6+{\mathrm{Ch}}^8+{\mathrm{<figure-callout\; id="10"\; label="Dh"\; filenames="A20061016853600141.png"\; state="\{\{state\}\}">Dh</figure-callout>}}^{10}+{\mathrm{Eh}}^{12}---\left(3\right)$

In above-mentioned formula (3), 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=l/r, r represents radius-of-curvature; H represents the eyeglass height; A represents four times asphericity coefficient (4th Order Aspherical Coefficient); B represents six times asphericity coefficient (6th Order Aspherical Coefficient); C represents eight times asphericity coefficient (8thOrder Aspherical Coefficient); D represents ten times asphericity coefficient (10th Order AsphericalCoefficient); E represents the asphericity coefficient (12th Order Aspherical Coefficient) of ten secondaries.

To illustrate the numerical value embodiment of microminiature lens 1 of the present invention in specific implementation process below, the lens surface sequence number of wherein being quoted 1,2,3,4,5,6,7,8,9,10 will represent the surface that is close to object space of first lens 10 respectively, the surface that is close to picture side of first lens 10, aperture 80, the surface that is close to object space of second lens 20, the surface that is close to picture side of second lens 20, the surface that is close to object space of the 3rd lens 30, the surface that is close to picture side of the 3rd lens 30, the surface that is close to object space of the 4th lens 40, the surface that is close to picture side of the 4th lens 40 and the plane that is close to object space of parallel-plate 50.

Microminiature lens 1 of the present invention at the first numerical value embodiment in the specific implementation process shown in following table one:

Table one

The surface sequence number	Radius-of-curvature (mm)	Thickness (mm)	Refractive index (Nd)	Abbe coefficient (Vd)
					1	1.4767	0.875	1.5146	57.2
2	3.9918	0.12
					3	∞	0.2
4	-4.9533	0.32	1.6074	29.0
					5	4.6787	0.221
6	11.304	1.152	1.5247	56.2
					7	-1.6073	0.85
8	-0.727	0.684	1.6074	29.0
					9	-1.008	1.48
10	∞	0.3	1.5168	64.2

In the first numerical value embodiment shown in the table one, four lens all adopt the aspheric surface design, and the concrete numerical value of its asphericity coefficient is:

Surface sequence number 1 (the object space sides of first lens 10):

k＝0.7208890793746 A＝-0.0162170839274 B＝0.01492023335

C＝-0.0308691156272 D＝0.0199342861188 E＝-0.005286344405

Surface sequence number 2 (picture side's sides of first lens 10):

k＝-38.8289156103687 A＝0.1348445356663 B＝-0.1119284881658

C＝0.2539583122095 D＝0 E＝0

Surface sequence number 4 (the object space sides of second lens 20):

k＝15.1662100079089 A＝-0.0127740232788 B＝-0.0380927089023

C＝0.102338957832 D＝0 E＝0

Surface sequence number 5 (picture side's sides of second lens 20):

k＝19.6667392959543 A＝-0.0381407658363 B＝0.066858744529

C＝-0.056035722863 D＝-0.0105458334847 E＝0

Surface sequence number 6 (the object space sides of the 3rd lens 30):

k＝106.5689754206271 A＝-0.0580598937846 B＝0.0612451022458

C＝-0.0921876702607 D＝0.0997090013496 E＝-0.0614782904

Surface sequence number 7 (picture side's sides of the 3rd lens 30):

k＝0.2773997046302 A＝0.0077766586785 B＝0.027067498253

C＝-0.0252545246416 D＝0.0275244707512 E＝-0.0084848671412

Surface sequence number 8 (the object space sides of the 4th lens 40):

k＝-1.0A＝-0.0846451939962 B＝0.1305499071261

C＝-0.0530030308202 D＝0.0121621691829 E＝-0.0037141184818

Surface sequence number 9 (picture side's sides of the 4th lens 40):

k＝-1.0A＝-0.0261266578478 B＝0.0226267374401

C＝0.0011900696081 D＝-0.0026104228328 E＝0.0002444934435

According to the design of above-mentioned table one, can obtain following each parameter value:

The effective focal length of system (F)	4.7mm
		Visual angle (F.O.V)	62.5 degree
System's length overall (Total Length)	6.2mm
		Aperture value (F-number)	2.86
f3/F	0.59
		|R9|-|R8|/F	0.06

Design according to the above first numerical value embodiment, the longitudinal spherical aberration of microminiature lens 1 of the present invention, image field depression and lateral chromatic aberration all can effectively be proofreaied and correct, and its optical appearance is shown in Fig. 2 A-2C.

Microminiature lens 1 of the present invention at the second value embodiment in the specific implementation process shown in following table two:

Table two

The surface sequence number	Radius-of-curvature (mm)	Thickness (mm)	Refractive index (Nd)	Abbe coefficient (Vd)
					1	1.4785	0.872	1.5247	56.21
2	3.709	0.14
					3	∞	0.1665
4	-5.402	0.4	1.5855	29.9
					5	4.982	0.32
6	9.6021	1.073	1.5247	56.21
					7	-1.8053	0.9
8	-0.7645	0.6608	1.6074	28.97
					9	-1.0404	1.2
10	∞	0.3	1.5168	64.17

In the second value embodiment shown in the table two, four lens all adopt the aspheric surface design, and the concrete numerical value of its asphericity coefficient is:

Surface sequence number 1 (the object space sides of first lens 10):

k＝0.7009181735917 A＝-0.0170231768259 B＝0.0127314496109

C＝-0.0332635198087 D＝0.0273869703056 E＝-0.0108725258542

Surface sequence number 2 (picture side's sides of first lens 10):

k＝-94.5952021995947 A＝0.2446161356042 B＝-0.3286676970061

C＝0.4163132161899 D＝0 E＝0

Surface sequence number 4 (the object space sides of second lens 20):

k＝14.7294919277834 A＝-0.0007163477527 B＝-0.0342319716817

C＝0.0951401603632 D＝0 E＝0

Surface sequence number 5 (picture side's sides of second lens 20):

k＝17.7129919891044 A＝-0.0034585186132 B＝0.037882875996

C＝-0.0228896924796 D＝-0.0009122530641 E＝0

Surface sequence number 6 (the object space sides of the 3rd lens 30):

k＝59.9331204189686 A＝-0.0517716484757 B＝0.044055269749

C＝-0.0795528662745 D＝0.0785186344995 E＝-0.0348610378733

Surface sequence number 7 (picture side's sides of the 3rd lens 30):

k＝0.6272580987026 A＝-0.0006995902127 B＝0.0216895214376

C＝-0.0216378264554 D＝0.0204890051535 E＝-0.0052971909755

Surface sequence number 8 (the object space sides of the 4th lens 40):

k＝-1 A＝-0.0868641243537 B＝0.1273745820457

C＝-0.0583325836995 D＝0.0180288577003 E＝-0.0042745702609

Surface sequence number 9 (picture side's sides of the 4th lens 40):

k＝-1.0 A＝-0.0171872759778 B＝0.0169286146538

C＝0.003160749626 D＝-0.00280828688 E＝0.0002854608383

According to the design of above-mentioned table two, can obtain following each parameter value:

The effective focal length of system (F)	4.75mm
		Visual angle (F.O.V)	62 degree
System's length overall (Total Length)	6.0mm
		Aperture value (F-number)	2.84
f3/F	0.63
		|R9|-|R8|/F	0.058

Design according to above second value embodiment, the longitudinal spherical aberration of microminiature lens 1 of the present invention, image field depression and lateral chromatic aberration all can effectively be proofreaied and correct, and its optical appearance is shown in Fig. 3 A-Fig. 3 C.

In sum, the present invention has met the important document of patent of invention, so propose patented claim in accordance with the law.But above said content only is the description to better embodiment of the present invention, and those of ordinary skill in the art modifies or variation according to the equivalence that spirit of the present invention is done as can be known, all falls within the protection domain of the application's claims.

Claims (16)

1. microminiature lens, it is characterized in that, comprise successively to picture side from object space: have positive diopter first lens, aperture, have dioptric second lens of bearing, have the 3rd lens of positive diopter and have dioptric the 4th lens of bearing, wherein the 3rd lens and the 4th lens respectively have at least one aspheric surface, and described microminiature lens satisfies following condition:

$0.2<\frac{f3}{F}<1.3---\left(1\right)$

Wherein f3 represents the effective focal length of the 3rd lens, and F represents the effective focal length of entire system.

2. microminiature lens as claimed in claim 1 is characterized in that, described first to fourth lens are the plastic cement lens.

3. microminiature lens as claimed in claim 2 is characterized in that, described first to fourth lens are double surface non-spherical lens.

4. as claim 1 or 3 described microminiature lens, it is characterized in that described second lens are double-concave negative lens.

5. microminiature lens as claimed in claim 4 is characterized in that, described microminiature lens also need satisfy following condition:

$0.02<\frac{\left|R9\right|-\left|R8\right|}{F}<0.4---\left(2\right)$

Wherein F system represents the effective focal length of entire system, and R8 is the radius-of-curvature on the surface that is close to object space of the 4th lens, and R9 is the radius-of-curvature on the surface that is close to picture side of the 4th lens.

6. microminiature lens as claimed in claim 5 is characterized in that, described first lens are the meniscus lens, and its convex surface is towards object space.

7. microminiature lens as claimed in claim 6 is characterized in that, described the 4th lens are the meniscus lens, and its concave surface is towards object space.

8. microminiature lens as claimed in claim 3 is characterized in that side also is provided with sheet glass in the picture side of the 4th lens.

9. microminiature lens as claimed in claim 8 is characterized in that, is provided with Image Sensor at the image space place of described camera lens.

10. microminiature lens, it is characterized in that, comprise successively to picture side from object space: have positive diopter first lens, aperture, have dioptric second lens of bearing, have the 3rd lens of positive diopter and have dioptric the 4th lens of bearing, wherein the 3rd lens and the 4th lens respectively have at least one aspheric surface, and second lens are double-concave negative lens.

11. microminiature lens as claimed in claim 10 is characterized in that, described microminiature lens need satisfy following condition:

$0.2<\frac{f3}{F}<1.3---\left(1\right)$

Wherein f3 represents the effective focal length of the 3rd lens, and F represents the effective focal length of entire system.

12. microminiature lens as claimed in claim 11 is characterized in that, described microminiature lens also need satisfy following condition:

$0.02<\frac{\left|R9\right|-\left|R8\right|}{F}<0.4---\left(2\right)$

Wherein F represents the effective focal length of entire system, and R8 is the radius-of-curvature on the surface that is close to object space of the 4th lens, and R9 is the radius-of-curvature on the surface that is close to picture side of the 4th lens.

13., it is characterized in that described first lens are the meniscus lens as claim 10 or 12 described microminiature lens, its convex surface is towards object space.

14. microminiature lens as claimed in claim 13 is characterized in that, described the 4th lens are the meniscus lens, and its concave surface is towards object space.

15. microminiature lens as claimed in claim 14 is characterized in that, described first to fourth lens are the plastic cement lens.

16. microminiature lens as claimed in claim 15 is characterized in that, described first to fourth lens are double surface non-spherical lens.

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