CN114830006B

CN114830006B - Fisheye lens system, camera module and electronic device

Info

Publication number: CN114830006B
Application number: CN201980103056.0A
Authority: CN
Inventors: 藤本诚
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2019-12-18
Filing date: 2019-12-18
Publication date: 2023-09-01
Anticipated expiration: 2039-12-18
Also published as: WO2021120056A1; CN114830006A

Abstract

A fisheye lens system includes, in order from an object side to an image side: a first lens group comprising: a first negative meniscus lens protruding toward the object side, a second negative meniscus lens protruding toward the object side, a third meniscus lens protruding toward the image side, and a fourth positive lens; a second lens group including a plurality of lenses; an aperture stop on either side of either lens, wherein the center thickness of the third meniscus lens is less than the edge thickness of the third meniscus lens, the first lens group has at least one aspheric surface, and the second lens group has at least one aspheric surface.

Description

Fisheye lens system, camera module and electronic device

Background

Technical Field

The present invention relates to a fisheye lens system, and more particularly, to a fisheye lens with a viewing angle of 160 ° or more, a camera module, and an electronic device.

Background

The fisheye lens was first applied to meteorology in the 20 th century to study cloud formation. Since then, fisheye lenses have found a variety of applications.

Large-scale manufactured photographic fisheye lenses were first shown in the beginning of the 60 th century. Typical focal lengths for fish eye lenses are between 8mm and 10mm for circular images and between 15mm and 16mm for full-frame images for popular 35mm film formats. The F value of a fisheye lens is typically between F2.8 and F3.5 because it is difficult to design a fisheye lens greater than F2.0.

In a circular fisheye lens, an image circle is engraved in the film or sensor area.

In full-frame fisheye lenses, the image circle is confined around the film or sensor area.

In addition, the manner in which different fisheye lenses distort images is different, and the manner of distortion is referred to as the projection function of the fisheye lens. Basically, the projection functions of the fisheye lens are stereoscopic projection, equidistant projection, equal solid angle projection and orthographic projection.

A common projection method for fish-eye lenses is equidistant projection, mainly applied to meteorology, e.g. ephemeris measurement and cloud measurement.

Fisheye lenses have been used in automobiles. Initially, fisheye lenses were applied to automotive rear cameras. Since the F value of the fish eye lens is typically between F2.8 and F3.5, as described above, F2.8 is large enough for an automobile rear camera because the automobile is equipped with a backup light.

However, in recent years, there are other applications of fisheye lenses in automobiles, such as a vehicle recorder, a driving state monitor (driver status monitor, DSM), advanced driver-assistance system (ADAS), automatic driving, and the like. These applications require fish-eye lenses greater than F2.8 in a darker environment and without auxiliary light.

Disclosure of Invention

Embodiments of the present invention provide a fisheye lens system (optical lens system), a camera module, and an electronic device, so as to image a high-quality image with a fast F value of about F1.6. The rapid fisheye lens system can be applied to an automobile camera, a smart phone camera, a security camera or a standard camera. Fisheye lenses with a fast F-number of about F1.6 can be applied in many different fields where ordered fisheye lenses are not fast enough (i.e. ordered fisheye lenses with fast F-numbers up to F2.8). For example, the fisheye lens system of the present invention may be applied to a vehicle recorder, a driving state monitor (driver status monitor, DSM), an advanced driver-assistance system (ADAS), automatic driving, etc., to provide wide, clear, and bright image monitoring without auxiliary illumination (e.g., a backup light). For smart phone cameras, the requirements for wide and bright lenses are increasing. The fisheye lens system can provide wide and high-quality images for the camera of the smart phone, and has minimum ISO, thereby generating noise. For the same reason, the fisheye lens system of the invention can also be applied to a monitoring system based on a fisheye lens camera. The fisheye lens of the invention may be used for a longer period of time in a monitoring system before using the illumination system or infrared camera.

According to a first aspect of the present invention, a fisheye lens system comprises, in order from an object side to an image side: the first lens group includes: first and second negative meniscus lenses protruding toward the object side, a third meniscus lens protruding toward the image side, and a fourth positive lens; a second lens group including a plurality of lenses; an aperture stop on either side of either lens.

The center thickness of the third meniscus lens is less than the edge thickness of the third meniscus lens.

According to a first aspect of the invention, the ratio of the edge thickness of the third meniscus lens to the center thickness of the third meniscus lens is in the range of 1.03 to 1.3, preferably in the range of 1.05 to 1.25.

The first lens group has at least one aspherical surface, and the second lens group has at least one aspherical surface.

The first and second negative meniscus lenses have at least one spherical surface such that they have very little spherical aberration and coma.

According to the first aspect of the present invention, the z factor of the third meniscus lens is preferably in the following range:

(i) 0<z factor <0.15.

The z-factor represents the ability of the lens to be automatically centered between the bell clips.

The z factor is as follows:

if the lens is biconvex or biconcave, then

(ii) z factor=0.5×| (B1/r1+b2/R2) |,

if the lens is meniscus-shaped, then

(iii) z factor=0.5×| (B1/R1-B2/R2) |,

where B1 and B2 are radii of clear aperture of the lens and R1 and R2 are radii of curvature of the first and second surfaces (i.e., front and rear surfaces) of the lens.

When the z-factor is greater than 0.15, the spherical aberration and coma are large.

The spherical aberration and coma of the third meniscus lens are very small, which is very effective for keeping astigmatism at a low level. In addition, the third meniscus lens makes the height of the edge ray higher so that the lens can correct spherical aberration.

According to a first aspect of the present invention, the fisheye lens system satisfies the following condition:

(iv)

wherein ,is the power of the whole fisheye lens system, +.>Is the power of the first lens group.

(v)

wherein ,is the power of the whole fisheye lens system, +.>Is the power of the third negative meniscus lens.

Positive power of the first lens groupIs very small, and thus the decentering tolerance and tilting tolerance of the first lens group should be sufficiently large.

Negative power of the third lensVery small, so that the eccentricity tolerance and the tilt tolerance are sufficiently large.

According to a first aspect of the invention, the second lens group comprises three lenses.

According to a first aspect of the invention, the second lens comprises two sub-lens groups.

By satisfying the above conditions, the fisheye lens system according to the present invention can have a lens with an F value greater than F1.8.

Fisheye lens systems having lenses with F values greater than F1.8 may be advantageously applied to a variety of camera systems without the need for auxiliary illumination.

According to a first aspect of the present invention, the fisheye lens system is applied to an automobile.

According to a first aspect of the invention, the fisheye lens system is applied to at least one of an automobile camera, a smart phone camera or a security camera.

According to a second aspect, the invention relates to an imaging (monitoring) system based on a fisheye lens camera. The system comprises: at least one fisheye lens camera comprising a fisheye lens system according to the first aspect or any of the above implementations of the first aspect; and a controller for converting the fisheye lens image into an output image. That is, the fisheye lens system is applied to an imaging (monitoring) system including: at least one fisheye lens camera and a controller for converting the fisheye lens image to an output image.

According to a third aspect, the invention relates to a camera module. The camera module includes: a fisheye lens system according to the first aspect or any of the above implementations of the first aspect; an image sensor for capturing an input image; one or more image processors; a non-transitory computer-readable storage medium storing instructions that, when executed, cause the one or more image processors to generate an output image. That is, the fisheye lens system is applied to a camera module, the camera module includes: an image sensor for capturing an input image; one or more image processors; a non-transitory computer-readable storage medium storing instructions that, when executed, cause the one or more image processors to generate an output image. The camera module can be applied to any electronic device.

According to a fourth aspect, the invention relates to an electronic device. The electronic device includes: a camera module according to the third aspect or any of the foregoing implementations of the third aspect; a display unit; and the control unit is used for controlling the camera module and the display unit. That is, the camera module of the present invention is applied to an electronic device including a display unit and a control unit, wherein the control unit controls the camera module and the display unit. For example, the electronic device may be a vehicle recorder, a ride status monitor (driver status monitor, DSM), an advanced driver-assistance system (ADAS), an automobile autopilot, a smart phone (mobile phone), a security camera system, etc.

The invention will be presented in further detail by the following description and the accompanying drawings, which are presented for illustrative purposes only, and which illustrate preferred embodiments provided by the invention.

Drawings

The invention may be better understood by reference to the following detailed description of non-limiting embodiments of the invention, taken in conjunction with the accompanying drawings, in which:

fig. 1 is a cross-sectional view of a prior art fisheye lens.

Fig. 2 is a bar chart of spherical aberration coefficients of the fish-eye lens shown in fig. 1.

Fig. 3 is a bar chart of coma coefficients of the fisheye lens shown in fig. 1.

Fig. 4 is a bar chart of the astigmatic difference coefficient of the fish-eye lens shown in fig. 1.

Fig. 5 is a cross-sectional view of a fisheye lens in one embodiment.

Fig. 6 is a bar graph of the spherical aberration coefficients of the fish-eye lens of fig. 5 in one embodiment.

Fig. 7 is a bar graph of the coma coefficients of the fisheye lens shown in fig. 5 in one embodiment.

Fig. 8 is a bar graph of the astigmatic difference coefficients of the fish-eye lens shown in fig. 5 in one embodiment.

Fig. 9 is a graph of spherical aberration of the fisheye lens shown in fig. 5 in one embodiment.

Fig. 10 is a diagram of curvature of field of the fish-eye lens of fig. 5 in one embodiment.

Fig. 11 is a diagram of the distortion of the fisheye lens shown in fig. 5 in one embodiment.

Fig. 12 is a cross-sectional view of a fisheye lens in another embodiment.

Fig. 13 is a graph of spherical aberration of the fisheye lens of fig. 12 in another embodiment.

Fig. 14 is a diagram of curvature of field of the fish-eye lens of fig. 12 in another embodiment.

Fig. 15 is a diagram of the distortion of the fish-eye lens of fig. 12 in another embodiment.

Fig. 16 is a cross-sectional view of a fisheye lens in another embodiment.

Fig. 17 is a graph of spherical aberration of the fisheye lens of fig. 16 in another embodiment.

Fig. 18 is a diagram of curvature of field of the fish-eye lens of fig. 16 in another embodiment.

Fig. 19 is a diagram of the distortion of the fish-eye lens shown in fig. 16 in another embodiment.

Fig. 20 shows an exemplary architecture of a camera module.

Fig. 21 is a block diagram of an electronic device according to an embodiment of the present invention.

Detailed Description

Fig. 1 shows a cross-sectional view of a fish-eye lens system in the related art, which includes a first lens group G1, an aperture stop S, a second lens group G2, and an optical filter F in order from an object side to an image side.

The first lens group G1 includes, in order from the object side to the image side: first negative curve protruding toward object sideA meniscus lens L1, a second negative meniscus lens L2 protruding toward the object side, and two lenses L3 ₁ and L3₂ And a third reinforcing convex lens L3.

Since the third lens L3 is a positive lens, the center thickness of the third lens L3 is larger than the edge thickness.

The second lens group G2 includes, in order from the object side: fourth reinforced positive meniscus lens L4, comprising two lenses L4 ₁ and L4₂ The method comprises the steps of carrying out a first treatment on the surface of the A fifth reinforced positive lens L5 comprising two lenses L5 ₁ and L5₂ 。

In the prior art, the fisheye lens system has an F value of F2.8 and a viewing angle of 200 °.

Fig. 2 is a bar graph of the spherical aberration coefficients of the prior art fisheye lens system of fig. 1.

Fig. 3 is a bar chart of coma coefficients of the prior art fisheye lens system shown in fig. 1.

Fig. 4 is a bar chart of the astigmatic difference coefficients of the prior art fisheye lens system of fig. 1.

The bar graphs of fig. 2 to 4 are obtained by Zemax with the total focal length normalized to 1 ^TM Calculated. Welford (aberration of an optical system) is used as a reference for deriving the seedel (Seidel) aberration coefficient.

First embodiment

Fig. 5 shows a cross-sectional view of a seven-piece fisheye lens system in the first embodiment, which includes a first lens group G1, a second lens group G2, and a filter F in order from the object side to the image side.

The first lens group G1 includes, in order from the object side to the image side, a first negative meniscus lens L1 protruding toward the object side, a second negative meniscus lens L2 protruding toward the object side, a third negative meniscus lens L3 protruding toward the image side, and a fourth positive lens L4.

Both sides of the second negative meniscus lens L2 are aspherical.

The center thickness TL3 of the third negative meniscus lens L3 is smaller than the edge thickness EL3 of the third negative meniscus lens L3.

The second lens group G2 is subject toSub-comprising fifth positive lens L5, aperture stop S, comprising positive lens L6 ₁ And negative lens L6 ₂ A sixth reinforced negative lens L6 and a seventh positive lens L7.

Both sides of the seventh positive lens L7 are aspherical.

Fig. 6 is a bar chart of the spherical aberration coefficients of the fisheye lens system in the first embodiment.

Fig. 7 is a bar chart of coma coefficients of the fisheye lens system in the first embodiment.

Fig. 8 is a bar chart of each lens element of the fisheye lens system in the first embodiment.

The bar graphs of fig. 6 to 8 are obtained by Zemax with the total focal length normalized to 1 ^TM Calculated. Welford (aberration of an optical system) is used as a reference for deriving the seedel (Seidel) aberration coefficient.

Referring to the bar charts of fig. 6, 7 and 8, it is noted that the spherical aberration and the astigmatic difference of the first lens group G1 are very small compared to the bar charts of the related art.

It should also be noted that the spherical aberration and coma of the third negative meniscus lens are very small. Therefore, it is very effective to control the astigmatic difference.

It should be noted that the fourth positive lens has some spherical aberration, small coma, and astigmatism. The positive spherical aberration cancels out the spherical aberration of the second lens group. Therefore, controlling the spherical aberration is very effective.

It should be noted that, the spherical aberration is mainly canceled by the fifth positive lens L5 and the sixth reinforcing negative lens L6, and the astigmatic aberration is mainly canceled by the fifth positive lens L5 and the seventh positive lens L7.

The curves of fig. 9, 10 and 11 show spherical aberration, field curvature and distortion, respectively. With respect to distortion, the ideal image height is calculated as equidistant.

The z factor and other key factors of the third negative meniscus lens L3 are as follows:

z factor = 0.05

TL3＝3.77

EL3＝4.14

EL3/TL3＝1.10

wherein ,is the power of the whole lens system, +.>Is the power of the first lens group, +.>Is the power of the third negative meniscus lens L3.

Thus, the first embodiment satisfies the conditions (i), (ii), and (iii).

Table 1-1 shows the specification of each lens element of the fisheye lens system in the first embodiment.

TABLE 1-1

f＝1.904

2ω＝200°

Fno＝1.8

Tables 1-2 show the conic constants of the aspherical surfaces of lenses L2 and L7.

TABLE 1-2

	L2 front	After L2	Before L7	After L7
					Conical constant	–2.41E+00	–8.06E–01	–9.06E–01	–3.42E+01
Coefficient of order 4	–2.12E–03	–1.22E–02	–1.10E–03	–2.92E–03
					Coefficient of order 6	7.50E–05	2.67E–04	1.33E–04	3.98E–04
Coefficient of 8 th order	–8.17E–07	–2.55E–05	–3.46E–06	–1.10E–05

The fisheye lens system according to the first embodiment achieves an F value of F1.8 and a viewing angle of 200 °.

Second embodiment

Fig. 12 shows a cross-sectional view of a seven-piece fisheye lens system in the second embodiment, which includes a first lens group G1, a second lens group G2, and a filter F in order from the object side to the image side.

The first lens group G1 includes, in order from the object side, a first negative meniscus lens L1 protruding toward the object side, a second negative meniscus lens L2 protruding toward the object side, a third negative meniscus lens L3 protruding toward the image side, and a fourth positive lens L4.

Both sides of the second negative meniscus lens L2 are aspherical.

The second lens group G2 includes, in order from the object side, a fifth positive lens L5, an aperture stop S, and a positive lens L6 ₁ And negative lens L6 ₂ A sixth reinforced negative lens L6 and a seventh positive lens L7.

Both sides of the seventh positive lens L7 are aspherical.

The curves of fig. 13, 14 and 15 show spherical aberration, field curvature and distortion, respectively. With respect to distortion, the ideal image height is calculated as equidistant.

The z factor and other key factors of the third negative meniscus lens L3 are as follows,

z factor = 0.04

TL3＝3.66

EL3＝4.03

EL3/TL3＝1.10

Thus, the second embodiment satisfies the conditions (i), (ii), and (iii).

Table 2-1 shows the specification of each lens element of the fisheye lens system in the second embodiment.

TABLE 2-1

f＝1.904

2ω＝200°

Fno＝1.6

Table 2-2 shows the conic constants of the aspherical surfaces of lenses L2 and L7.

TABLE 2-2

	L2 front	After L2	Before L7	After L7
					Conical constant	–2.22E+00	–8.18E–01	–1.01E+00	–3.15E+01
Coefficient of order 4	–2.25E–03	–1.24E–02	–1.08E–03	–3.16E–03
					Coefficient of order 6	7.60E–05	2.73E–04	1.54E–04	4.37E–04
Coefficient of 8 th order	–8.15E–07	–2.42E–05	–4.41E–06	–1.28E–05

The fisheye lens system according to the second embodiment achieves an F value of F1.6 and a viewing angle of 200 °.

Third embodiment

Fig. 16 shows a cross-sectional view of a seven-piece fisheye lens system in the third embodiment, which includes a first lens group G1, a second lens group G2, and a filter F in order from the object side to the image side.

The first lens group G1 includes, in order from the object side, a first negative meniscus lens L1 protruding toward the object side, a second negative meniscus lens L2 protruding toward the object side, a third meniscus lens L3 protruding toward the image side, and a fourth positive lens L4.

Both sides of the first negative meniscus lens L1 are spherical surfaces made of glass materials.

Both sides of the second negative meniscus lens L2 are aspherical surfaces made of plastic materials.

Both sides of the third meniscus lens L3 are aspheric surfaces made of plastic material. The center thickness TL3 of the third meniscus lens L3 is smaller than the edge thickness EL3 of the third negative meniscus lens L3.

Both sides of the fourth positive lens L4 are aspheric surfaces made of plastic materials.

The second lens group G2 includes, in order from the object side, a fifth positive lens L5, an aperture stop S, a sixth negative lens L6, and a seventh positive lens L7.

Both sides of the fifth negative lens L5 are spherical surfaces made of glass.

Both sides of the sixth negative lens L6 are aspherical surfaces made of plastic materials.

Both sides of the seventh positive lens L7 are aspherical surfaces made of plastic materials.

The fisheye lens system in the third embodiment uses a plastic aspherical lens and a glass spherical lens to reduce the cost because the glass aspherical lens is very expensive.

The glass spherical lens provides good environmental characteristics for the third embodiment.

The curves of fig. 17, 18 and 19 show spherical aberration, field curvature and distortion, respectively. With respect to distortion, the ideal image height is calculated as equidistant.

The key factors are as follows. Since both sides of the third meniscus lens L3 are aspherical, there is no z factor.

TL3＝3.46

EL3＝4.12

EL3/TL3＝1.19

Therefore, the third embodiment satisfies the conditions (2) and (3). There is no z-factor as described above.

Table 3-1 shows the specification of each lens element of the fisheye lens system in the third embodiment.

TABLE 3-1

f＝1.904

2ω＝200°

Fno＝1.6

Table 3-2 shows the conic constants of the aspherical surfaces of lenses L2, L3, L4, L6 and L7.

TABLE 3-2

The fisheye lens system according to the third embodiment achieves an F value of F1.6 and a viewing angle of 200 °.

Exemplary Camera configuration

Fig. 20 is a block diagram of a fisheye lens camera (camera module) 10 according to an embodiment. In the illustrated embodiment, the fisheye lens camera 10 may include an imaging unit 20, the imaging unit 20 including a fisheye lens system 22, an image sensor 24, and an image processor 26. The fisheye lens camera 10 may additionally or alternatively include a system controller 30 (e.g., a microcontroller or microprocessor), may control the operation and functions of the fisheye lens camera 10, and a system memory 40, the system memory 40 may be used to store executable computer instructions that, when executed by the system controller 30 and/or the image processor 26, may perform camera functions. The fisheye lens camera 10 may additionally or alternatively include a sensor 50, an audio system 60, an I/O interface 70, and a control/display 80. In some embodiments, the fisheye lens camera 10 may optionally include multiple imaging units 20 to capture fields of view in different fields of view or for different functions. One of the plurality of imaging units 20 may have a lens system (not shown) other than the fisheye lens system.

The fisheye lens system 22 may focus light entering the fisheye lens to the image sensor 24, where the image sensor 24 captures an image and/or video frame.

The image sensor 24 may capture high definition images or video having, for example, 720p, 1080p, 4k or higher resolution. For video, the image sensor 24 may capture video at a frame rate of, for example, 30 frames per second, 60 frames per second, or higher. Image processor 26 may perform one or more image processing functions of the captured image or video. For example, the image processor 26 may perform bayer conversion, demosaicing, noise reduction, image sharpening, image stabilization, rolling shutter artifact reduction, color space conversion, compression, or other intra-camera processing functions. The processed images and video may be temporarily or permanently stored to the system memory 40 and/or to a non-volatile memory, which may be in the form of an internal memory or an external memory card.

Input/output (I/O) interface 70 may transmit and receive data from various external devices. For example, the I/O interface 70 may facilitate the reception or transmission of video or audio information through an I/O port. Examples of I/O ports or interfaces may include USB ports, HDMI ports, ethernet ports, audio ports, and the like. Further, embodiments of the I/O interface 70 may include a wireless port that may accommodate wireless connections. Examples of wireless ports include bluetooth, wireless USB, short range wireless communication technology (Near Field Communication, NFC), etc. The I/O interface 70 may also include an interface for synchronizing the fisheye lens camera 10 with other cameras or other external devices such as car cameras, smart phone cameras, security cameras, and standard cameras.

Control/display subsystem 80 may include various control and display components associated with the operation of fisheye lens camera 10, including LED lights, displays, keys, microphones, speakers, and the like. For example, the audio system 60 may include one or more microphones and one or more audio processors to capture and process audio data related to video capture. In one embodiment, the audio system 60 may include a microphone array having two or microphones arranged to obtain directional audio signals.

The sensor 50 may capture various metadata simultaneously with or separately from the video or image capture. For example, sensor 50 may capture timestamp location information in accordance with a global positioning system (global positioning system, GPS) sensor and/or altimeter. Other sensors 50 may be used to detect and capture the orientation of the fisheye lens camera 10, including an orientation sensor, accelerometer, gyroscope, or magnetometer. Sensor data captured from the various sensors 50 may be processed to generate other types of metadata. For example, sensor data from an accelerometer may be used to generate motion metadata, including velocity and/or acceleration vectors representing the motion of the fisheye lens camera 10. In addition, sensor data from the direction sensor may be used to generate direction metadata describing the direction of the fish-eye lens camera 10. Sensor data from the GPS sensor provides GPS coordinates identifying the position of the fisheye lens camera 10, and the altimeter measures the height of the fisheye lens camera 10. In one embodiment, the sensor 50 may be solidly coupled to the fisheye lens camera 10 such that any movement, direction, or change in position experienced by the fisheye lens camera 10 may also be experienced by the sensor 50. The sensors 50 may also associate a timestamp indicating when data was captured by each sensor. In one embodiment, the sensor 50 may automatically begin collecting sensor metadata when the fisheye lens camera 10 begins recording video or capturing images.

Fig. 21 is a block diagram of an electronic device 100 according to an embodiment of the invention. As examples of the present embodiment, the electronic apparatus 100 is a drive recorder for an automobile, a smart phone, a security camera system, or the like, a driving state monitoring (driver status monitor, DSM), an advanced driver-assistance system (ADAS), and automatic driving. The electronic device 100 may have a housing (not shown).

The electronic device 100 includes a fisheye lens camera 110, a display unit 140, a wireless communication unit 150, a user interface 120, and a control unit 130. Any one of the fisheye lens camera 110, the display unit 140, the wireless communication unit 150, and the user interface 120 need not be included in the electronic device 100.

The fisheye lens camera 110 images an object. The fisheye lens camera 110 may be mounted in the case such that an optical axis of the fisheye lens camera 110 is parallel to a thickness direction of the thin case. The fisheye lens camera 110 may generate and provide image data to at least one of the display part 101, the wireless communication unit 150, and a storage part (not shown).

The display unit 140 displays image data. The display unit 140 may display character data operated by a user and operation buttons.

The wireless communication unit 150 may transmit and receive information using wireless communication, such as a wireless communication network, a wireless local area network (Local Area Network, LAN), bluetooth, or infrared communication. As an example, the wireless communication unit 150 may transmit image data to another electronic device.

The user interface 120 receives operation inputs from a user. The user interface 120 may be integrally formed with the display unit 140.

The control unit 130 may perform overall control of the electronic device 100. For example, the control unit 130 controls imaging of the fisheye lens camera 110.

The above-described embodiments of the present invention provide a faster fisheye lens system having an F value of F1.8 or F value greater than F1.8 and a viewing angle of about 200 deg. whereas conventional fisheye lens systems have an F value of about F2.8.

Therefore, the fisheye lens system according to the present invention can be used not only for automobiles but also for various applications even in environments where sufficient light cannot be provided.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. A fisheye lens system, comprising, in order from an object side to an image side:

a first lens group comprising:

a first negative meniscus lens element protruding towards the object side,

a second negative meniscus lens element protruding towards the object side,

a third meniscus lens element protruding towards the image side,

a fourth positive lens element;

a second lens group including a plurality of lens elements;

an aperture stop on either side of either lens element,

wherein the center thickness of the third meniscus lens element is smaller than the edge thickness of the third meniscus lens element,

the first lens group has at least one aspheric surface, and the second lens group has at least one aspheric surface;

the ratio of the edge thickness of the third meniscus lens element to the center thickness of the third meniscus lens element is in the range of 1.03 to 1.3.

2. The fish-eye lens system of claim 1, wherein a ratio of the edge thickness of the third meniscus lens element to the center thickness of the third meniscus lens element is in the range of 1.05 to 1.25.

3. The fish-eye lens system of claim 1, wherein the z-factor of the third meniscus lens element is preferably in the following range:

(i) The 0<z factor is <0.15,

wherein the z-factor of the third meniscus lens element is as follows:

if the third meniscus lens element is biconvex or biconcave

(ii) z factor=0.5×| (B1/r1+b2/R2) |,

if the third meniscus lens element is a meniscus

(iii) z factor=0.5×| (B1/R1-B2/R2) |,

wherein B1 and B2 are radii of clear apertures of the third meniscus lens element, and R1 and R2 are radii of curvature of front and rear surfaces of the third meniscus lens element.

4. A fisheye lens system according to any one of claims 1-3 wherein the fisheye lens system meets the following conditions:

(iv)

5. A fisheye lens system according to any one of claims 1-3 wherein the fisheye lens system meets the following conditions:

(v)

wherein ,is the power of the whole fisheye lens system, +.>Is the power of the third meniscus lens element.

6. A fisheye lens system according to any one of claims 1-3 wherein the second lens set comprises three lens elements.

7. A fisheye lens system according to any one of claims 1-3 wherein the second lens group comprises two sub-lens groups.

8. A fisheye lens system according to any one of claims 1 to 3 wherein the fisheye lens system is for use in an automobile.

9. A fisheye lens system according to any one of claims 1 to 3 wherein the fisheye lens system is applied to at least one of an automotive camera, a smart phone camera or a security camera.

10. An imaging system based on a fisheye lens camera, comprising:

at least one fisheye lens camera comprising a fisheye lens system according to any one of claims 1 to 9;

and a controller for converting the fisheye lens image into an output image.

11. A camera module, comprising:

the fish-eye lens system according to any one of claims 1 to 9;

an image sensor for capturing an input image;

one or more image processors;

a non-transitory computer-readable storage medium storing instructions that, when executed, cause the one or more image processors to generate an output image.

12. An electronic device, comprising:

the camera module of claim 11;

a display unit;

and the control unit is used for controlling the camera module and the display unit.