CN101561547A - Novel low-cost vehicle backing backsight wide angle lens - Google Patents

Abstract

The invention discloses a novel low-cost vehicle backing backsight wide angle lens. The lens comprises a first lens element, a second lens element, a third lens element and a fourth lens element which are sequentially arranged from an object; an orifice plate is arranged between the third lens element and the fourth lens element; the first lens element is a meniscus glass lens which has negative focal power and is protruded towards the object; the second lens element, the third lens element and the fourth lens element are plastic lenses; and the six mirror surfaces of the second lens element, the third lens element and the fourth lens element are all of aspheric surfaces. The lens can realize ultra wide angle, large relative aperture and shorter lens height under the conditions that few lens elements are used and the majority of the lenses are made of low-priced plastics, so that the lens is particularly applied to ultra wide angle monitoring systems and vehicle mounted imaging systems.

Description

Novel low-cost vehicle backing backsight wide angle lens

Technical field

The present invention relates to a kind of vehicle backing backsight lens system, be particularly suitable for monitoring, the novel low-cost vehicle backing backsight wide angle lens of in-vehicle camera and installed video system.

Background technology

Monitor at present and the low-cost bugeye lens of in-vehicle camera, 4 lens units of general employing are formed, as China Patent No. is that 200710137002 wide-angle lens and China Patent No. are 200610074775.9 wide-angle lens, just adopt 4 lens to form, but the camera lens sharpness is relatively poor, particularly the logical optical property of camera lens a little less than, promptly aperture only reaches FNO2.8.

Summary of the invention

Technical matters to be solved by this invention is to overcome above-mentioned technological deficiency, provides that a kind of cost is low, in light weight, high pass optical property FNO2.0 and better solutions be as the wide-angle lens of effect, can realize high performance camera lens solution at a low price.

A kind of novel low-cost vehicle backing backsight wide angle lens, it comprises from object space and begins to be provided with successively first lens element, second lens element, the 3rd lens element and the 4th lens element that aperture member is located between the 3rd and the 4th lens element, it is characterized in that:

Described first lens element has negative focal power and protruding curved month type eyeglass to object space;

Described second lens element has negative focal power and protrudingly is all aspheric curved month type eyeglass to object space, two sides;

Described the 3rd lens element has positive focal power, the two sides is all aspheric biconvex eyeglass;

Described the 4th lens element has positive focal power, the two sides is all aspheric biconvex eyeglass.

Described first lens element satisfies the following conditions formula:

Nd≥1.75，Vd≥45

Wherein Nd represents the d optical index of the first lens element material, and Vd represents the d light Abbe constant of the first lens element material.

Described the 3rd lens element satisfies the following conditions formula:

1.64≥Nd≥1.53，23≤Vd≤30

Wherein Nd represents the d optical index of the 3rd lens element material, and Vd represents the d light Abbe constant of the 3rd lens element material.

Described the 3rd lens and the 4th lens element satisfy the following conditions formula:

1.3≥F3/F4≥0.9

Wherein F3 represents the focal length value of the 3rd lens element, and F4 represents the focal length value of the 4th lens element.

Described the 4th lens element satisfies the following conditions formula:

6≥F1～F3/F4≥3

Wherein F1～F3 represents the synthetic focal length value of first lens to the, three lens elements, and F4 represents the focal length value of the 4th lens element.

Described focal length value satisfies the following conditions formula:

15≥F1～F3/F≥7.5

Wherein F1～F3 represents the synthetic focal length value of first lens to the, three lens elements, and F represents the whole focal length value of described camera lens.

Maximum field of view angle 2 ω of described wide-angle lens will satisfy following formula: field angle 2 ω 〉=140 °.

The first lens object space side outermost point of described wide-angle lens will satisfy following condition: TTL≤17mm to the imaging focal plane apart from TTL.

The described first lens element material is an optical glass; Described second, third, the 4th lens element material is optical plastic.

Compared with prior art, the present invention only uses 4 eyeglasses, make camera lens weight saving, cost reduces, the configuration of lens element can reach gratifying optical characteristics, super wide horizontal field of view angle, less f-number and moderate lens length with minimum eyeglass quantity, can satisfy overwhelming majority monitoring and in-vehicle camera system applies demand.

Description of drawings

Fig. 1 is a structural representation of the present invention.(object space is in left-most position, is in right-most position as the side)

Fig. 2 is chromatic curve figure of the present invention.

Fig. 3 is an astigmatism curve map of the present invention

Fig. 4 is distortion curve figure of the present invention.

Fig. 5 is a MTF curve map of the present invention.

Embodiment

Below with reference to above-mentioned accompanying drawing the embodiment of the invention is described in detail again.

The embodiment of novel low-cost vehicle backing backsight wide angle lens of the present invention as shown in Figure 1, it is particularly suitable for being applied to the in-vehicle camera system of reversing automobile backsight.This wide-angle lens extremely is followed successively by the first eyeglass L1, the second eyeglass L2, prismatic glasses L3, diaphragm r7, the 4th eyeglass L4, color filter GF, imaging surface IMA as side by the thing side.

The first eyeglass L1, it has negative focal power and protruding curved month type eyeglass to object space, is that the two sides all is the glass lens element of sphere; The second eyeglass L2, it has negative focal power and protruding curved month type eyeglass to object space, is that the two sides all is the plastic lens elements of aspheric surface; Prismatic glasses L3, it has the biconvex eyeglass of positive focal power, be that the two sides all is the plastic lens elements of aspheric surface, and plastic material has high dispersion; The 4th eyeglass L4, it has the biconvex eyeglass of positive focal power, is that the two sides all is the plastic lens elements of aspheric surface.So dispose, can reach the horizontal field of view angle of gratifying optical characteristics and broad with minimum eyeglass quantity.

In addition, the first lens element L1 adopts refractive index Nd 〉=1.75, the high-refractivity and low-dispersion material of Abbe constant Vd 〉=45, and one side can effectively import the above light of 140 ° of field angle and reduce the bore of first eyeglass, and is excessive to avoid volume; The influence of glass lens opposing rugged environment can be effectively protected on the other hand, the high reliability requirement of monitoring and in-vehicle camera can be adapted to.

The 3rd lens element L3 adopts refractive index 1.64 〉=Nd 〉=1.53, the high-dispersive optical plastic material of Abbe constant 23≤Vd≤30, the effectively value of chromatism in the compensation optical system.

The focal length value of the 3rd lens L3 and the 4th lens element L4 will satisfy formula 1.3 〉=F3/F4 〉=0.9, and because of when the F3/F4＜0.9, the 3rd lens strength is excessive, the chief ray emergence angle CRA of camera lens is increased, cause that relative brightness descends, and simultaneously, has increased the processing and forming difficulty of the 3rd lens; When F3/F4＞1.3, then the 4th power of lens is excessive, increases the generation and the processing technology difficulty of senior aberration.

This lens system is in when design, is before and after the boundary is divided into two groups with the diaphragm with camera lens, promptly is made up of lens one, lens two and lens three for first group, and its combined focal length is F1～F3; Be made up of lens four for second group, its focal length is F4.The whole focal length of lens system is F, then satisfies 6 〉=F1～F3/F4 〉=3,15 〉=F1～F3/F 〉=7.5.So design promptly requires the combined light focal power of first group and second group lens just to be all, and can effectively utilize the double gauss optical principle to eliminate aberration like this, and promptly the aberration of two groups of lens combination can be cancelled each other before and after the diaphragm, to improve the final imaging effect of lens system.

Fig. 2 to Fig. 5 is the optical performance curve figure corresponding to embodiment, and wherein Fig. 2 is chromatic curve figure (also can be the spherical aberration curve map), represents that by F, d commonly used, the wavelength of C three coloured light unit is mm.Fig. 3 is the astigmatism curve map, represents that by F, d commonly used, the wavelength of C three coloured light unit is mm.Fig. 4 is distortion curve figure, represents the distortion sizes values under the different field angle situations, and unit is %.Fig. 5 is the MTF curve map, has represented the picture level of comprehensively separating of an optical system.As seen from the figure, this wide-angle lens with various optical aberration correctings to being enough to practical level.

In the present embodiment, the whole focal length value of this wide-angle lens is F, and f-number is FNO, the maximum field of view angle is 2 ω=155 °, camera lens length overall TTL=14.2mm, and begin by the object space side, with each minute surface number consecutively, the minute surface of the first eyeglass L1 is r1, r2, and the minute surface of the second eyeglass L2 is r3, r4, and the minute surface of prismatic glasses L3 is r5, r6, the diaphragm face is r7, the minute surface of the 4th eyeglass L4 is r8, r9, and the minute surface of color filter GF is r10, r11, 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 the formula: Z is an aspheric surface along optical axis direction highly for the position of h the time, apart from the aspheric surface summit apart from rise sag.

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

F＝1.4mm，FNO＝2.0，2ω＝155°，TTL＝14.2mm

Optical system parameter of the present invention sees Table 1:

Table 1

The face sequence number	Radius-of-curvature r	Center thickness d	Refractive index Nd	Abbe constant Vd
					1	19.18	0.7	1.7725	49.6
2	3.44	2
					*3	3.343	0.85	1.5120	56.26
*4	0.922	0.95
					*5	2.305	2.67	1.5855	29.9
*6	-4.828	1.24
					7	infinity	1.05
*8	6.555	1.77	1.5120	56.26
					*9	-2.07	0.1
10	infinity	0.55	1.51680	64.16
					11	infinity
IMA	infinity

The minute surface of beating " * " number in the last table is an aspheric surface, and its correlation parameter sees Table 2:

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

Table 2

The face sequence number	K	A	B	C	D	E
							3	-0.2462503	-0.019301499	0.00057054486	-1.4602204e-005	-4.5099782e-009	3.6738736e-009
4	-1.023171	-0.023899554	-0.0012200379	0.00013940188	-1.2568324e-005	-2.7162455e-007
							5	-0.4312873	-0.0032686275	0.0016399596	-0.00034488996	-1.5335098e-005	-3.7572205e-007
6	-1.711919	0.0038836512	0.00058249778	-0.00022109315	8.6503027e-006	7.1463366e-007
							8	2.965645	-0.012493337	-0.015074644	0.01487616	-0.0063059827	0.0009371435
9	-1.81763	0.0035267546	-0.0096401799	0.0033288421	-0.00056153947	2.4700231e-005

Claims (9)

1, a kind of novel low-cost vehicle backing backsight wide angle lens, it comprises from object space and begins to be provided with successively first lens element, second lens element, the 3rd lens element and the 4th lens element, aperture member is located between the 3rd and the 4th lens element, it is characterized in that:

Described first lens element has negative focal power and protruding curved month type eyeglass to object space;

Described second lens element has negative focal power and protrudingly is all aspheric curved month type eyeglass to object space, two sides;

Described the 3rd lens element has positive focal power, the two sides is all aspheric biconvex eyeglass;

Described the 4th lens element has positive focal power, the two sides is all aspheric biconvex eyeglass.

2, novel low-cost vehicle backing backsight wide angle lens as claimed in claim 1 is characterized in that described first lens element satisfies the following conditions formula:

Nd≥1.75，Vd≥45

Wherein Nd represents the d optical index of the first lens element material, and Vd represents the d light Abbe constant of the first lens element material.

3, novel low-cost vehicle backing backsight wide angle lens as claimed in claim 1 is characterized in that described the 3rd lens element satisfies the following conditions formula:

1.64≥Nd≥1.53，23≤Vd≤30

Wherein Nd represents the d optical index of the 3rd lens element material, and Vd represents the d light Abbe constant of the 3rd lens element material.

4, novel low-cost vehicle backing backsight wide angle lens as claimed in claim 1 is characterized in that described the 3rd lens and the 4th lens element satisfy the following conditions formula:

1.3≥F3/F4≥0.9

Wherein F3 represents the focal length value of the 3rd lens element, and F4 represents the focal length value of the 4th lens element.

5, novel low-cost vehicle backing backsight wide angle lens as claimed in claim 1 is characterized in that described the 4th lens element satisfies the following conditions formula:

6≥F1～F3/F4≥3

Wherein F1～F3 represents the synthetic focal length value of first lens to the, three lens elements, and F4 represents the focal length value of the 4th lens element.

6, novel low-cost vehicle backing backsight wide angle lens as claimed in claim 1 is characterized in that described focal length value satisfies the following conditions formula:

15≥F1～F3/F≥7.5

Wherein F1～F3 represents the synthetic focal length value of first lens to the, three lens elements, and F represents the whole focal length value of described camera lens.

7, novel low-cost vehicle backing backsight wide angle lens as claimed in claim 1 is characterized in that maximum field of view angle 2 ω of described wide-angle lens will satisfy following formula: field angle 2 ω 〉=140 °.

8, novel low-cost vehicle backing backsight wide angle lens as claimed in claim 1, the first lens object space side outermost point that it is characterized in that described wide-angle lens will satisfy following condition: TTL≤17mm to the imaging focal plane apart from TTL.

9,, it is characterized in that the described first lens element material is an optical glass as each described novel low-cost vehicle backing backsight wide angle lens of claim 1～8; Described second, third, the 4th lens element material is optical plastic.

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