CN103576290A - Wide-angle lens - Google Patents

Abstract

The invention provides a wide-angle lens which comprises a front lens set with negative focal power, a diaphragm and a rear lens set with positive focal power from an object space to an image space in sequence. The front lens set comprises a first lens, a second lens and a third lens from the object space side in sequence, wherein the first lens is a negative meniscus lens protruding towards the object space, the second lens is a negative meniscus lens or a biconcave lens, and the third lens is a biconvex positive focal power lens. The rear lens set comprises a fourth lens, a fifth lens and a sixth lens from the object space side in sequence, wherein the fourth lens and the fifth lens form a bonding lens, the fourth lens has positive focal power, the fifth lens has negative focal power, the sixth lens is a biconvex positive focal power lens, and at least four lens contained in the lens from the second lens to the sixth lens are aspheric lenses. The wide-angle lens is low in cost, low in weight, little in distortion, small in size, high in light pervious performance and capable of meeting the requirement of high definition.

Description

A kind of wide-angle lens

Technical field

The present invention relates to a kind of wide-angle lens system, be particularly suitable for the wide-angle lens of the more severe outdoor monitoring of environment and vehicle mounted.

Background technology

High definition wide-angle lens is general at present adopts 5 to 8 sheet glass lens compositions, as the wide-angle lens that China Patent No. is 200710201261, just adopt 6 sheet glass lens to form, but not only weight is heavier for this wide-angle lens, and after field angle surpasses 90 °, distortion will be very serious.For this reason, also there is the wide-angle lens of enterprise development to adopt aspheric surface technology, to subtract amount distortion, as the U.S. Patent number wide-angle lens that is US2009251801A1, just adopting 6 lens to form, is wherein non-spherical lens containing 2, although can correct optical distortion, but Lens is larger, and it is higher to grow up.

Summary of the invention

The invention provides a kind of camera lens wide-angle lens, the serious problem of distortion after having solved wide-angle lens field angle and surpassing 90 °, its technical scheme is as described below:

A kind of wide-angle lens, comprise successively from the object side to the image side the front lens group with negative power, diaphragm, the rear lens group with positive light coke, described front lens group comprises first lens successively from object space side, the second lens, the 3rd lens, described first lens is the protruding diverging meniscus lens to object space, described the second lens are the lens of negative bent moon or concave-concave, the positive light coke lens that described the 3rd lens are biconvex, described rear lens group comprises the 4th lens successively from object space side, the 5th lens, the 6th lens, the 4th lens and the 5th lens form a balsaming lens, described the 4th lens have positive light coke, described the 5th lens have negative power, the lens of the positive light coke that described the 6th lens are biconvex, wherein in the second lens to the six lens, at least comprising four lens is non-spherical lenses.

Described camera lens meets following formula:

220°≥FOV≥130°

Wherein, FOV represents total field angle of described camera lens.

Further, described first lens meets relational expression

Nd≥1.65，Vd≥45

Wherein Nd is refractive index, and Vd is Abbe constant.

First lens can effectively import 130 ° of more than field angle light and reduce the bore of first lens like this, to avoid volume excessive, and the requirement of formula d*h/FOV≤0.205 that satisfies condition.

Further, described the 3rd lens meet condition formula below:

Nd≥1.55，Vd≤31

Wherein Nd is refractive index, and Vd is Abbe constant.

Described the 3rd lens can be assembled the light that the first two negative power lens are come fast, and the value of chromatism in high chromatic dispersion material energy effective compensation optical system.

Further, described camera lens meets condition formula below

TTL/EFL≤20

Wherein TTL is that described camera lens first lens object space side outermost point is to the distance of imaging surface, total focal length value that EFL is described wide-angle lens.

Further, described the second lens and rear lens group meet condition formula below:

-after 1.0 >=F/F2 >=-1.5

Wherein F2 represents the focal length value of the second lens, represents the focal length value of rear lens group after F.

Will satisfy condition after formula-1.0 >=F/F2 >=-1.5 of the focal length value of the second lens element and rear lens group, because of after F/during F2 >-1.0, the negative power of the second lens is excessive, the positive light coke of rear lens group is too small, thereby it is excessive to make whole optical system can embody local negative power, can cause the effect of rear burnt BFL " pyrocondensation cold expanding " of optical system (under hot conditions, the rear burnt BFL of camera lens can shorten, under cryogenic conditions, the rear burnt BFL of camera lens can be elongated, do not meet the condition that camera uses); After F/during F2 <-1.5, the negative power of the second lens is too small, the positive light coke of rear lens group is excessive, thereby make the local positive light coke of whole optical system excessive, the effect that can cause the rear burnt BFL of optical system " to expand with heat and contract with cold " is too obvious, thereby affects camera imaging definition in the temperature range of-40 ℃～+ 85 ℃.

Further, the maximum clear aperture of described first lens and corresponding imaging image height, field angle meet following condition formula:

d/h/FOV≤0.025

Wherein FOV represents the maximum field of view angle of wide-angle lens, and d represents that the corresponding first lens in maximum field of view angle is towards the maximum clear aperture of object space convex surface, and h represents the corresponding imaging image height in maximum field of view angle.

Further, described the 4th lens adopt glue to carry out bonding joint with the 5th lens and form a lens subassembly, and the convex surface on composition surface is towards image side.

Further, described the 4th lens and the 5th lens adopt plastic material, and composition surface meets following condition formula:

θ≤60°|R|≤Φ/2

Wherein θ is the tangent line of any point on composition surface and the angle of optical axis, the curvature of centre radius that R is composition surface, the light effective aperture that Φ is composition surface.

Further, described camera lens meets condition formula below:

BFL/EFL≥2.0

The 6th lens image side outermost point that wherein BFL is described wide-angle lens is to the distance of imaging surface, the focal length value that EFL is described wide-angle lens.

In a word, five eyeglasses of the second lens to the six lens, need reasonably distribute focal power and be controlled within the scope of above-mentioned condition formula simultaneously, to reach good temperature characterisitic requirement.Meanwhile, in order further to improve temperature characterisitic effect, also the material of the 3rd lens can be adopted to glass material (because the temperature characterisitic of glass material is better than plastic resin material).

The first lens of optical lens adopts glass mirror, can effectively protect in use scratch resistant scrape along opposing rugged environment variable effect of optical lens, and the 4th lens and the 5th lens adopt bond layout, effectively to improve the aberration of optical system.The composition surface that simultaneously control to engage lens subassembly meet θ≤60 ° and | the condition formula of R| >=Φ/2, effectively to control the generation of senior aberration, thereby be beneficial to the logical luminous energy power (aperture FNO≤2.2) and the resolving power that improve whole optical system, and effectively reduce processing and the gluing technique requirement on composition surface.

Another important feature of the present invention is to keep still having longer rear lens focus BFL under the condition that camera lens overall length TTL is shorter, the larger dimensional requirement of imageing sensor periphery electronic devices and components when meeting camera design, simultaneously, because the long distance that makes lens element and optical filter leave imageing sensor of BFL is farther, can effectively reduce the surface cleanliness requirement to each lens element and optical filter, the assembling of easier camera is produced.

Use wide-angle lens provided by the invention, can realize cost low, lightweight, distort little, size is little, high pass optical property and meet the wide-angle lens that high definition requires, because having adopted more plastic aspherical element lens, can keep lighter weight and lower cost simultaneously.And can guarantee still to keep more perfect imaging definition in the temperature range of-40 ℃～+ 85 ℃, be specially adapted to outdoor monitoring and in-vehicle camera system.

Accompanying drawing explanation

Fig. 1 is the structural representation of the embodiment 1 of wide-angle lens provided by the invention;

Fig. 2 is the chromatic curve figure of the embodiment 1 of wide-angle lens provided by the invention;

Fig. 3 is the astigmatism curve map of the embodiment 1 of wide-angle lens provided by the invention;

Fig. 4 is the distortion curve figure of the embodiment 1 of wide-angle lens provided by the invention;

Fig. 5 is the structural representation of the embodiment 2 of wide-angle lens provided by the invention;

Fig. 6 is the chromatic curve figure of the embodiment 2 of wide-angle lens provided by the invention;

Fig. 7 is the astigmatism curve map of the embodiment 2 of wide-angle lens provided by the invention;

Fig. 8 is the distortion curve figure of the embodiment 2 of wide-angle lens provided by the invention.

Embodiment

Embodiments of the invention 1 as shown in Figures 1 to 4, described camera lens comprise successively from the object side to the image side have negative power front lens group, diaphragm, there is the rear lens group of positive light coke, described front lens group comprises first lens L1, the second lens L2, the 3rd lens L3 successively from object space side, and described rear lens group comprises the 4th lens L4, the 5th lens L5, the 6th lens L6 successively from object space side.

As shown in Figure 1, described camera lens is extremely followed successively by first lens L1, the second lens L2, the 3rd lens L3, diaphragm r7, the 4th lens L4, the 5th lens L5, the 6th lens L6, color filter GF, imaging surface IMA as side by thing side.

First lens L1 is the diverging meniscus lens with negative focal power, is that two sides is all the glass lens element of sphere; The second lens L2 is the lens with negative focal power, is that two sides is all aspheric plastic lens elements; The 3rd lens L3 is the biconvex lens with positive focal power, is that two sides is all the glass lens element of sphere; The 4th lens L4 is the biconvex lens with positive focal power, is that two sides is all aspheric plastic lens elements; The 5th lens L5 is the diverging meniscus lens with negative focal power, is that two sides is all aspheric plastic lens elements; And L4 and L5 are combined into a balsaming lens; The 6th lens L6 is the biconvex lens with positive focal power, is that two sides is all aspheric plastic lens elements.

Fig. 2 to Fig. 4 is the optical performance curve figure corresponding to embodiment 1, and wherein Fig. 2 is chromatic curve figure (also can be spherical aberration curve map), by the F commonly using, d, C tri-look light wavelengths, is represented, unit is mm.Fig. 3 is astigmatism curve map, by the F commonly using, d, C tri-look light wavelengths, is represented, unit is mm.Fig. 4 is distortion curve figure, represents the distortion sizes values in different field angle situations, and unit is %.

In embodiment 1, the whole focal length value of this wide-angle lens is F, f-number is FNO, field angle is 2 ω, camera lens overall length TTL, and started by object space side, by each minute surface number consecutively, the minute surface of first lens L1 is r1, r2, and the minute surface of the second lens L2 is r3, r4, the minute surface of the 3rd lens L3 is r5, r6, diaphragm face is r7, and the minute surface of the 4th lens L4 and the 5th lens L5 is r8, r9, r10, and the minute surface of the 6th lens L6 is r11, r12, the minute surface of color filter GF is r13, r14, and the formula of aspherical mirror is:

$Z\left(h\right)=\frac{{\mathrm{ch}}^2}{1+\sqrt{1-(1+k)c^2{h}^2}}+{\mathrm{Ah}}^4+{\mathrm{Bh}}^6+{\mathrm{Ch}}^8+{\mathrm{Dh}}^{10}+{\mathrm{Eh}}^{12}$

In formula: Z is aspheric surface along optical axis direction when highly for the position of h, apart from the distance rise on aspheric surface summit.

C=1/r, r represents the radius-of-curvature of minute surface, k is circular cone coefficient conic, A, B, C, D, E is high order aspheric surface coefficient, and e in coefficient represents scientific notation, as e-05 represents 10 ^-5, F=0.9mm, FNO=2.0,2 ω=200 °, TTL=16.97mm.

Following table is the related parameter values of lens, and the minute surface of beating " * " number is aspheric surface.

Table 1

Face sequence number	Radius-of-curvature r	Center thickness d	Half clear aperture	Refractive index Nd	Abbe constant Vd
						1	12.95	0.8	6.53	1.7725	49.6
2	3.404	2.81	3.32	?	?
						*3	33.169	1.02	3.32	1.5120	56.3
*4	1.294	1.75	2.31	?	?
						5	7.631	2.02	2.32	1.8467	23.8
6	-7.631	1.8	2.14	?	?
						7	infinity	0.15	0.76	?	?
*8	8.556	1.77	0.88	1.5346	56.1

*9	-0.687	0.65	1.13	1.5825	30.1
						*10	-9.877	0.1	1.58	?	?
*11	3.854	1.61	1.85	1.5120	56.3
						*12	-2.431	0.2	1.91	?	?
13	infinity	0.3	1.91	1.5168	64.2
						14	infinity	1.99	1.91	?	?
IMA	infinity	?	?	?	?

That following table is listed is aspheric surface COEFFICIENT K, A, B, C, D, E

Table 2

Face sequence number	K	A	B	C	D	E
							3	79.99021	-0.0042659546	9.4631562e-005	-3.0200331e-006	-3.7003845e-008	-2.999142e-009
4	-1.058149	-0.0032511133	-0.001657005	0.00015082279	-1.965371e-006	4.9503562e-008
							8	3.031043	-0.0014875755	0.0035086339	0.00017211948	0.0024831484	-0.0087874694
9	-1.269367	0.0079119604	-0.20265194	0.091143269	0.023102888	0.00070986224
							10	22.10825	-0.020130878	0.0088589345	-0.00085243241	6.8934527e-006	3.4289817e-005
11	-19.01586	-0.0025299003	0.0038368061	-0.00041239933	3.2806525e-005	-3.3669318e-007
							12	-4.836767	-0.013623879	0.004967567	-0.00033398864	2.2741961e-005	-9.271765e-007

According to above-mentioned case study on implementation data, the numerical value that calculates condition formula involved in claims is as table 3 and table 4:

Table 3

Table 4

Embodiments of the invention 2 are as shown in Fig. 5 to Fig. 8, described camera lens comprise successively from the object side to the image side have negative power front lens group, diaphragm, there is the rear lens group of positive light coke, described front lens group comprises first lens L1, the second lens L2, the 3rd lens L3 successively from object space side, and described rear lens group comprises the 4th lens L4, the 5th lens L5, the 6th lens L6 successively from object space side.

As shown in Figure 5, described the second lens to the six lens have all adopted non-spherical lens.This optical lens is extremely followed successively by first lens L1, the second lens L2, the 3rd lens L3, diaphragm r7, the 4th lens L4, the 5th lens L5, the 6th lens L6, color filter GF, imaging surface IMA as side by thing side.

First lens L1 is the diverging meniscus lens with negative focal power, is that two sides is all the glass lens element of sphere; The second lens L2 is the biconcave lens with negative focal power, is that two sides is all aspheric plastic lens elements; The 3rd lens L3 is the biconvex lens with positive focal power, is that two sides is all aspheric plastic lens elements; The 4th lens L4 is the double convex glass lens with positive focal power, and the 5th lens L5 is the negative bent moon glass lens with negative focal power, and L4 and L5 are combined into a balsaming lens; The 6th lens L6 is the biconvex lens with positive focal power, is that two sides is all aspheric plastic lens elements.

Fig. 6 to Fig. 8 is the optical performance curve figure corresponding to embodiment 2, and wherein Fig. 6 is chromatic curve figure (also can be spherical aberration curve map), by the F commonly using, d, C tri-look light wavelengths, is represented, unit is mm.Fig. 7 is astigmatism curve map, by the F commonly using, d, C tri-look light wavelengths, is represented, unit is mm.Fig. 8 is distortion curve figure, represents the distortion sizes values in different field angle situations, and unit is %.

In the present embodiment, the whole focal length value of this optics wide-angle lens is F, f-number is FNO, field angle is 2 ω, camera lens overall length TTL, and started by object space side, by each minute surface number consecutively, the minute surface of first lens L1 is r1, r2, and the minute surface of the second lens L2 is r3, r4, the minute surface of the 3rd lens L3 is r5, r6, diaphragm face is r7, and the minute surface of the 4th lens L4 and the 5th lens L5 is r8, r9, r10, and the minute surface of the 6th lens L6 is r11, r12, the minute surface of color filter GF is r13, r14, and the formula of aspherical mirror is:

$Z\left(h\right)=\frac{{\mathrm{ch}}^2}{1+\sqrt{1-(1+k)c^2{h}^2}}+{\mathrm{Ah}}^4+{\mathrm{Bh}}^6+{\mathrm{Ch}}^8+{\mathrm{Dh}}^{10}+{\mathrm{Eh}}^{12}$

In formula: Z is aspheric surface along optical axis direction when highly for the position of h, apart from the distance rise on aspheric surface summit.

C=1/r, r represents the radius-of-curvature of minute surface, k is circular cone coefficient conic, A, B, C, D, E is high order aspheric surface coefficient, and e in coefficient represents scientific notation, as e-05 represents 10 ^-5.

F=0.90mm，FNO=2.0，2ω=187°，TTL=17.02mm

Following table is the correlation parameter of lens, and the minute surface of beating " * " number is aspheric surface

Table 5

Face sequence number

Radius-of-curvature r

Center thickness d

Half clear aperture

Refractive index Nd

Abbe constant Vd

1	13.1	0.8	6.24	1.7725	49.6
						2	3.427	2.67	3.30	?	?
*3	32.926	0.98	3.39	1.5120	56.3
						*4	1.299	1.74	2.31	?	?
*5	5.944	2.0	2.31	1.6355	23.8
						*6	-5.964	1.89	2.14	?	?
7	infinity	0.15	0.76	?	?
						*8	8.464	1.83	0.87	1.5346	56.1
*9	-0.693	0.65	1.16	1.5825	30.1
						*10	-9.813	0.1	1.55	?	?
*11	3.821	1.68	1.77	1.5120	56.3
						*12	-2.432	0.2	1.84	?	?
13	infinity	0.3	1.82	1.5168	64.2
						14	infinity	2.0	1.82	?	?
IMA	infinity	?	?	?	?

That following table is listed is aspheric surface COEFFICIENT K, A, B, C, D, E:

Table 6

Face sequence number	K	A	B	C	D	E
							3	80.58686	-0.0042504692	9.207951e-005	-3.031417e-006	-3.3073693e-008	-1.6766032e-009
4	-1.055555	-0.0032133829	-0.0016403787	0.00015137651	-2.3179658e-006	-8.5946605e-009
							5	-0.08022798	-4.8906947e-005	-1.4895662e-005	-2.2704909e-006	-2.6128756e-007	-2.7212036e-008
6	-0.1028616	6.7599093e-005	1.58338e-005	2.1286227e-006	3.0569114e-007	1.694758e-007
							8	3.732483	-0.0013300724	0.003242239	-0.0015030752	0.00040620602	-0.012090322
9	-1.286186	0.012699311	-0.1965926	0.098207211	0.030681026	2.8950911e-005
							10	22.02222	-0.020117535	0.0088747261	-0.00085252398	1.1138494e-005	2.9990352e-005
11	-19.13132	-0.0025779759	0.0038205694	-0.00041333781	3.4110945e-005	-7.5965892e-007
							12	-4.846718	-0.013541154	0.0050000524	-0.00032401493	2.4973762e-005	-1.0894172e-006

According to above-mentioned case study on implementation data, the numerical value that calculates condition formula involved in claims is as table 7 and table 8:

Table 7

Table 8

Wide-angle lens provided by the invention, can realize cost low, lightweight, distort little, size is little, high pass optical property and meet the wide-angle lens that high definition requires, because having adopted more plastic aspherical element lens, can keep lighter weight and lower cost simultaneously.

Claims (10)

1. a wide-angle lens, it is characterized in that: comprise successively from the object side to the image side the front lens group with negative power, diaphragm, the rear lens group with positive light coke, described front lens group comprises first lens successively from object space side, the second lens, the 3rd lens, described first lens is the protruding diverging meniscus lens to object space, described the second lens are the lens of negative bent moon or concave-concave, the positive light coke lens that described the 3rd lens are biconvex, described rear lens group comprises the 4th lens successively from object space side, the 5th lens, the 6th lens, the 4th lens and the 5th lens form a balsaming lens, described the 4th lens have positive light coke, described the 5th lens have negative power, the lens of the positive light coke that described the 6th lens are biconvex, wherein in the second lens to the six lens, at least comprising four lens is non-spherical lenses.

2. wide-angle lens according to claim 1, is characterized in that: described camera lens meets following formula:

220°≥FOV≥130°

Wherein, FOV represents total field angle of described camera lens.

3. wide-angle lens according to claim 1, is characterized in that: described first lens meets relational expression

Nd≥1.65，Vd≥45

Wherein Nd is refractive index, and Vd is Abbe constant.

4. wide-angle lens according to claim 1, is characterized in that: described the 3rd lens meet condition formula below:

Nd≥1.55，Vd≤31

Wherein Nd is refractive index, and Vd is Abbe constant.

5. wide-angle lens according to claim 1, is characterized in that: described camera lens meets condition formula below

TTL/EFL≤20

Wherein TTL is that described camera lens first lens object space side outermost point is to the distance of imaging surface, total focal length value that EFL is described wide-angle lens.

6. wide-angle lens according to claim 1, is characterized in that: described the second lens and rear lens group meet condition formula below:

-after 1.0 >=F/F2 >=-1.5

Wherein F2 represents the focal length value of the second lens, represents the focal length value of rear lens group after F.

7. wide-angle lens according to claim 1, is characterized in that: the maximum clear aperture of described first lens and corresponding imaging image height, field angle meet following condition formula:

d/h/FOV≤0.025

Wherein FOV represents the maximum field of view angle of wide-angle lens, and d represents that the corresponding first lens in maximum field of view angle is towards the maximum clear aperture of object space convex surface, and h represents the corresponding imaging image height in maximum field of view angle.

8. wide-angle lens according to claim 1, is characterized in that: described the 4th lens adopt glue to carry out bonding joint with the 5th lens and form a lens subassembly, and the convex surface on composition surface is towards image side.

9. wide-angle lens according to claim 1, is characterized in that: described the 4th lens and the 5th lens adopt plastic material, and composition surface meets following condition formula:

θ≤60°|R|≤Φ/2

Wherein θ is the tangent line of any point on composition surface and the angle of optical axis, the curvature of centre radius that R is composition surface, the light effective aperture that Φ is composition surface.

10. wide-angle lens according to claim 1, is characterized in that: described camera lens meets condition formula below:

BFL/EFL≥2.0

The 6th lens image side outermost point that wherein BFL is described wide-angle lens is to the distance of imaging surface, the focal length value that EFL is described wide-angle lens.

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