CN107153249B - Wide-angle lens for vehicle-mounted rear view - Google Patents

Abstract

A wide-angle lens for vehicle-mounted rear view includes in order from an object plane to an image plane: the lens comprises a first lens with negative focal power, a second lens with positive focal power, a third lens with positive focal power, a fourth lens with positive focal power, a fifth lens with negative focal power and a sixth lens with positive focal power; wherein an aperture diaphragm with a specified aperture is arranged between the second lens and the third lens; in addition, a protective glass and an optical filter are arranged between the sixth lens and the imaging surface; a light receiving surface on which a solid-state imaging element such as a CCD or a CMOS is arranged on an imaging surface; the second lens, the fourth lens and the sixth lens are all biconvex lenses; the fourth lens and the fifth lens are combined into a cemented lens, and the cemented surface of the cemented lens is bent towards the object; the second lens and the fifth lens are both high-refractive-index glass lenses. The first lens, the third lens, the fourth lens and the sixth lens are low-dispersion glass lenses.

Description

Wide-angle lens for vehicle-mounted rear view

Technical Field

The invention relates to a wide-angle lens for a vehicle, in particular to a large-relative-aperture wide-angle vehicle-mounted rearview lens.

Background

With the rapid development of the society and the rapid improvement of the living standard of people, people pay more attention to the safety awareness, which is also reflected in the field of vehicle-mounted lenses in the automobile industry. The vehicle-mounted lens comprises a driving recording lens at the front end of the vehicle, a reversing lens at the rear end of the vehicle, a streaming media rearview mirror, other lenses around the vehicle and the like, and the existence of the vehicle-mounted lens can not only provide evidence for disputes of people, but also guarantee the safety of lives and properties of the vehicle.

With the continuous development of the field of automobile unmanned driving, the wide-angle rearview mirror head for the vehicle-mounted streaming media gradually replaces the traditional automobile rearview mirror and provides information support for automatic automobile driving. The display effect of a general traditional rearview mirror can be influenced by passengers, luggage or automobiles in a rear seat, and the wide-angle rearview mirror head for vehicle-mounted streaming media can break through the limitations and comprehensively observe various information such as driving, parking, road conditions and the like. Compared with the traditional rearview mirror, the wide-angle rearview mirror head for the vehicle-mounted streaming media can record the picture in a larger angle range behind the vehicle in real time and transmit the picture to a driver through the rearview mirror (display screen) through certain data processing and information transmission, so that the driver can observe and judge the surrounding environment. The safety of the driver during driving is greatly improved, and meanwhile, powerful evidence can be provided for sudden traffic accidents, so that unnecessary civil disputes are avoided.

The existing wide-angle rearview mirror head for vehicle-carrying media cannot achieve two effects on two important parameters which affect the quality of the wide-angle lens, namely a large wide angle and a large relative aperture. A lens with a large field angle is often relatively small in aperture, and is difficult to obtain more picture details under low illumination conditions such as cloudy days and nights; the lens with a large relative aperture has a long focal length, and the field angle cannot meet the requirement of wide angle. Meanwhile, the image quality of a plurality of vehicle-mounted wide-angle lenses is poor after the field angle exceeds a certain degree, and better peripheral imaging cannot be obtained by means of post data processing.

The traditional inside rear-view mirror has a field angle of only 20-30 degrees, and the range of viewing the rear is very limited. Moreover, since the rearview mirror is arranged in the vehicle, the imaging only depends on the mirror reflection, so that the rearview mirror is easily influenced by a passenger in a rear seat, luggage or automobile parts, and the view field of the rearview mirror is shielded. When the night is, the strong light of the rear car light is directly reflected in the rearview mirror and enters the eyes of a driver, so that the driver can feel strong dizzy and even temporarily blindness is caused, and great potential safety hazard is brought to driving.

The wide-angle rearview lens for the existing vehicle-mounted streaming media has the following disadvantages:

(1) the relative pore size is small.

The relative aperture is one of the important parameters of an optical lens, expressed as the ratio of the lens' entrance pupil diameter to the focal length. Generally, the relative aperture size determines the brightness of the image formed by the lens, and the brightness of the image is proportional to the square of the relative aperture, with the focal length of the lens unchanged. Each time the relative aperture of the lens is doubled, the brightness of the image, the cross-sectional area of the incident beam and the luminous flux are all quadrupled. The conventional wide-angle vehicle-mounted lens has a relatively small relative aperture, and as described in patent document (101561550), although the wide-angle vehicle-mounted lens has a wide angle of 120 ° or more, its FNo (reciprocal of relative aperture) is 2, and it is difficult to have good performance in dark environments such as rainy days and nights.

(2) Poor quality and low brightness of the peripheral image.

In an optical system with a large field angle, the main aberrations affecting the image quality are chromatic aberration of magnification and field curvature distortion, and as the chromatic aberration of magnification of the optical system is larger, the edge color separation is more serious, and various phenomena such as "purple edge" and "blue edge" can occur. The larger the magnification chromatic aberration field curvature of the optical system is, the more curved a straight line is when the straight line is shot, and if the field curvature has one or more inflection points, the seen straight line can become a curved line. Meanwhile, the peripheral light ratio of one optical system also affects the imaging quality, and the dark angle appears at the edge of the imaging surface of the optical system with the low peripheral light ratio, which affects the observation of a user. The existing vehicle-mounted wide-angle rearview mirror head in the market has generally poor image quality at the edge, and dark corners mostly appear at the same time, namely, the image aberrations such as chromatic aberration, field curvature distortion and the like are not optimized, and the peripheral brightness ratio is not improved.

(3) The resolution is low.

Most of the existing vehicle-mounted wide-angle rearview mirrors in the market are 130 ten thousand pixels, although the situation behind the vehicle can be recorded, when the situation of an emergency needs to be investigated, the relevant details are lost because the resolution cannot meet the requirement, so that the driving record loses the significance of the driving record.

Disclosure of Invention

The invention provides a novel wide-angle rearview lens for vehicle-mounted media, which overcomes the defects in the prior art.

The technical scheme adopted by the invention is as follows:

a wide-angle lens for vehicle-mounted rear view includes in order from an object plane to an image plane: a first lens L1 with negative focal power, a second lens L2 with positive focal power, a third lens L3 with positive focal power, a fourth lens L4 with positive focal power, a fifth lens L5 with negative focal power and a sixth lens L6 with positive focal power; an aperture stop STP having a predetermined aperture is disposed between the second mirror L2 and the third mirror L3; further, a cover glass and a filter are disposed between the sixth lens L6 and the image forming surface IMG; a light receiving surface on which a solid-state imaging element such as a CCD or a CMOS is arranged on an imaging surface IMG;

the second lens piece L2, the fourth lens piece L4 and the sixth lens piece L6 are each a biconvex lens;

the second lens L2 and the fifth lens L5 are both high refractive index glass lenses. The first lens L1, the third lens L3, the fourth lens L4 and the sixth lens L6 are low dispersion glass lenses. Through the combination of the high-refractive-index and low-dispersion lenses, the axial chromatic aberration of the system can be greatly eliminated, and clear imaging of a peripheral field of view is realized;

the lens satisfies the following conditions:

the first lens L1 satisfies: vd >35;

the second lens L2 satisfies: nd > 1.82;

the third lens L3 satisfies: nd >1.75, Vd >35;

the fourth lens L4 satisfies: vd >35;

the fifth lens L5 satisfies: nd > 1.82;

the sixth lens L6 satisfies: nd >1.75, Vd >35;

where Nd denotes the d-light refractive index of the lens material, and Vd denotes the d-light abbe constant of the lens material.

The fourth lens L4 and the fifth lens L5 are combined to form a cemented lens, and the cemented surface of the cemented lens is curved to the object.

In view of the above-mentioned defects of the existing rearview mirror and wide-angle rearview mirror head, the inventor of the present invention has made extensive practical experience and professional knowledge based on the design and manufacture of such products, and has actively studied and innovated in cooperation with the application of theory, so as to create a novel structure of the vehicular streaming media wide-angle rearview mirror head, which can improve the general existing lens and make it more practical. After continuous research and design and repeated trial production and improvement, the invention with practical value is finally created.

The wide-angle lens of the invention can achieve a plurality of characteristics such as large field angle, large relative aperture, high relative illumination, low aberration, high image quality and the like by adopting the structure. The system can give consideration to both a large field angle and a large relative aperture, can ensure that the imaging quality of peripheral image quality is improved under the image quality of 200 ten thousand 1080P high-definition pixels, and can combine various functions of an automobile multimedia system, live-action navigation, a vehicle recorder, track playback and the like.

The invention has the following advantages:

1. the relative aperture is large.

The wide-angle lens designed by the invention has FNo (reciprocal of relative aperture) of 1.3, and under the condition of the same field angle, the illumination intensity obtained by the wide-angle lens designed by the invention is 2.5 times of that of other lenses on the market, so that the object details under the dark light environment can be better obtained. The use quality of the user in rainy days and night driving is guaranteed.

2. The field angle is large, the peripheral image quality is good, and the brightness is high.

The wide-angle lens designed by the invention has a field angle of 70-90 degrees under the condition of different sensors, which is 3-4 times of that of the traditional rearview mirror. Meanwhile, most of transverse chromatic aberration of light rays with different frequencies is controlled within the airy spot range, imaging chromatic aberration is relatively uniform, axial chromatic aberration is well corrected, and clear imaging can be realized. The curvature of field of the lens is well corrected, and the image quality of the full field of view is uniform although the wide field of view is provided. Under the condition of a full view field, the lens can keep more than 60% of peripheral brightness ratio, so that the integral illumination of the image surface is uniform, and the defect that the periphery of some lenses on the market is darker is avoided.

3. The resolution is high.

Through innovating the lens structure of the optical system, the image quality of the wide-angle lens is well corrected and improved, and the image output performance of more than 200 ten thousand pixels of full high definition 1080P can be easily realized. When the automobile driving recorder is used, a user can obtain more details from the picture, so that the driving record is more accurate.

Drawings

FIG. 1 is a schematic diagram of a wide-angle lens according to the present invention;

FIG. 2 is a schematic MTF diagram of a wide-angle lens according to the present invention;

FIG. 3 is a schematic diagram of axial chromatic aberration and image curvature of a wide-angle lens according to the present invention;

fig. 4 is a relative illuminance diagram of a wide-angle lens in the present invention.

Detailed Description

The following further describes embodiments of the present invention with reference to the accompanying drawings.

A wide-angle lens for vehicle-mounted rear view includes in order from an object plane to an image plane: the lens comprises a first lens L1 with negative focal power, a second lens L2 with positive focal power, a third lens L3 with positive focal power, a fourth lens L4 with positive focal power, a fifth lens L5 with negative focal power and a sixth lens L6 with positive focal power. An aperture stop STP having a predetermined aperture is disposed between the second mirror L2 and the third mirror L3; further, a cover glass and a filter are disposed between the sixth lens L6 and the image forming surface IMG. On the imaging plane IMG, a light receiving surface of a solid-state imaging element such as a CCD or a CMOS is arranged.

Wherein each lens satisfies the following conditions: a first lens L1 meniscus lens; the second lens piece L2, the fourth lens piece L4 and the sixth lens piece L6 are each a biconvex lens; the fourth lens L4 and the fifth lens L5 are combined to form a cemented lens, and the cemented surface of the cemented lens is curved to the object.

Hereinafter, various numerical data regarding the wide-angle lens of the embodiment are shown.

EFL (effective focal length) 3.9 mm;

FNo (relative pore size) ═ 1.3;

HFOV (horizontal field angle) is 70 to 90 ° (different horizontal field angles are provided in cooperation with different sensors);

table 1 shows the wide angle lens configuration parameters of the examples.

TABLE 1

Number of noodles	Radius of curvature	Center thickness
			1	35.13	0.85
2	2.91	1.4
			3	19.38	1.91
4	-50.81	0.6
			STO	INF	1.25
6	-8.64	3.92
			7	-5.43	0.1
8	15.81	2.65
			9	-5.21	0.5
10	-36.26	0.1
			11	11.90	2.85
12	-23.52	2.13
				INF	0.8
	INF	3
			IMG	INF

Fig. 1 is a schematic structural diagram of a wide-angle lens in the present invention.

Fig. 2 is a MTF diagram of the wide-angle lens of the present invention. MTF is the modulation transfer function, and the horizontal axis in the graph represents the space frequency and the unit is lp/mm; the longitudinal axis represents the value of the modulation transfer function, the MTF value is used for evaluating the imaging quality of the lens, the value range is 0-1, the higher the MTF curve is, the straighter the MTF curve represents the imaging quality of the lens, and the stronger the reduction capability of the real image is. It can be seen from fig. 2 that the image quality is well corrected, and the output performance of more than 200 ten thousand pixels can be easily realized.

FIG. 3 is a schematic diagram of axial chromatic aberration and image curvature of a wide-angle lens according to the present invention. As can be seen from FIG. 3, most of the lateral chromatic aberration of the light with different frequencies is within the Airy spot range, the imaging chromatic aberration is relatively uniform, i.e. the axial chromatic aberration is well corrected, and clear imaging can be realized. And the field curvature of the system is better corrected, and the full-view image quality is more uniform although the system has a wide-angle view field.

Fig. 4 is a relative illuminance diagram of a wide-angle lens in the present invention. As can be seen from fig. 4, the relative illumination of more than 60% can be maintained in the full field of view, so that the overall illumination of the image plane is uniform, and the defect that some lenses on the market are dark at the periphery is avoided.

The embodiments described in this specification are merely illustrative of implementations of the inventive concept and the scope of the present invention should not be considered limited to the specific forms set forth in the embodiments but rather by the equivalents thereof as may occur to those skilled in the art upon consideration of the present inventive concept.

Claims (1)

1. A wide-angle lens for vehicle-mounted rearview sequentially comprises a lens body, a lens body and a lens barrel, wherein the lens body is arranged on the lens body; a first lens (Ll) having a negative optical power, a second lens (L2) having a positive optical power, a third lens (L3) having a positive optical power, a fourth lens (L4) having a positive optical power, a fifth lens (L5) having a negative optical power, and a sixth lens (L6) having a positive optical power; wherein an aperture Stop (STP) defining a predetermined aperture is provided between the second lens (L2) and the third lens (L3); further, a cover glass and a filter are disposed between the sixth lens (L6) and the image forming surface (IMG); a solid-state imaging element is arranged on an imaging plane (IMG);

the FNo =1.3 of the wide-angle lens for the vehicle-mounted rear view; wherein the FNo represents an inverse number of a relative aperture of the wide-angle lens for vehicle rear view;

the second lens (L2), the fourth lens (L4) and the sixth lens (L6) are all biconvex lenses;

the fourth lens (L4) and the fifth lens (L5) are combined into a cemented lens, and the cemented surface of the cemented lens is bent towards the object;

the second lens (L2) and the fifth lens (L5) are both high-refractive-index glass lenses; the first lens (Ll), the third lens (L3), the fourth lens (L4) and the sixth lens (L6) are low dispersion glass lenses;

the lens satisfies the following conditions;

the first lens (Ll) satisfies: vd >35;

the second lens (L2) satisfies: nd is greater than l.82;

the third lens (L3) satisfies: nd > l.75, Vd >35;

the fourth lens (L4) satisfies: vd >35;

the fifth lens (L5) satisfies: nd is greater than l.82;

the sixth lens (L6) satisfies: nd > l.75, Vd >35;

where Nd denotes the d-light refractive index of the lens material, and Vd denotes the d-light abbe constant of the lens material.

Images