WO2021190268A1 - Lens system, camera apparatus, and moving object - Google Patents

Abstract

Disclosed is a lens system (100). The lens system (100) sequentially comprises, from an object side, a first lens group (G1), a diaphragm (S), a positive second lens group (G2), a negative third lens group (G3), and a positive fourth lens group (G4). Two negative meniscus lenses (L1, L2) with convex surfaces thereof facing the object side can be provided on the side of the first lens group (G1) that is closest to an object, the third lens group (G3) can be composed of two or fewer lenses, the fourth lens group (G4) can comprise at least one positive lens (L14) and a negative lens (L15), and the negative lens (L15) is arranged on the side closest to an image. When focusing from the infinity to the proximity of a photographed object, the third lens group (G3) can be moved toward the image side. With f1 being the focal length of the first lens group (G1), f4 being the focal length of the fourth lens group (G4), f being the focal length of the entire system, and vd1-2 being the average Abbe number at the line d of the two negative meniscus lenses (L1, L2) of the first lens group (G1), the following conditional expressions can be satisfied: 3.5 ＜ |f1/f|, 2.1 ＜ f4/f ＜ 5, and vd1-2 ＞ 50.

Description

Lens system, camera device and moving body

This disclosure relates to and claims the priority of a Japanese patent application filed with the Japanese Patent Office with the application number 2020-058211, titled "レンズ系, imaging device, and mobile body" on March 27, 2020, the entire contents of which are incorporated by reference Incorporated in this disclosure.

Technical field

The invention relates to a lens system, an imaging device and a moving body.

Background technique

Patent Document 1 discloses a lens system with a relatively large aperture and a relatively wide angle of view. Patent Document 2 discloses a large-diameter internal focusing type lens system.

Background technical literature:

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2010-097207

[Patent Document 2] Japanese Patent Laid-Open No. 2013-257395

Summary of the invention

A lens system according to an aspect of the present invention includes a first lens group, a diaphragm, a positive second lens group, a negative third lens group, and a positive fourth lens group in order from the object side. On the object side closest to the first lens group, two negative meniscus lenses with convex surfaces facing the object side may be arranged. The third lens group may be composed of two or less lenses. The fourth lens group may include at least one positive lens and a negative lens, and the negative lens is disposed closest to the object side. When focusing on a short-distance subject from infinity, the third lens group can move to the image side. Suppose f1 is the focal length of the first lens group, f4 is the focal length of the fourth lens group, f is the focal length of the entire system, and vd1-2 is the average of the two negative meniscus lenses of the first lens group at the d line. The number of shells can satisfy the conditional formula:

3.5＜|f1/f|

2.1＜f4/f＜5

vd1-2>50.

If the negative part group of the first lens group is the 1-a group and the positive part group of the first lens group is the 1-b group, then the 1-a group may include at least three negative lenses and one positive lens. Let f1a be the focal length of the lens group 1-a, which can satisfy the conditional formula:

-1.2<f1a/f<-0.6.

Let f34 be the combined focal length of the third lens group and the fourth lens group, and the conditional formula can be satisfied:

5.5<|f34/f|.

Let f3 be the focal length of the third lens group, the conditional formula can be satisfied:

-5<f3/f<-1.5.

Let β3 be the lateral magnification of the third lens group when focusing on an infinite subject, and β4 be the lateral magnification of the fourth lens group when focusing on an infinite subject, and the conditional expression can be satisfied:

(1-β3 ² )×β4 ² ＜-0.4

Let f1-b be the focal length of the 1-b group and f2 be the focal length of the second lens group, the conditional formula can be satisfied:

0.4＜f1-b/f2＜1.2

An imaging device according to an aspect of the present invention includes the above-mentioned lens system. The imaging device includes an imaging element.

A moving body according to an aspect of the present invention includes the above-mentioned lens system and moves.

The moving body may be an unmanned aircraft.

According to the above-mentioned lens system, it is possible to provide a lens system including a high-resolution large-aperture wide-angle lens system. In addition, it is possible to provide a lens system including a lightweight movable group.

In addition, the above summary of the invention does not enumerate all the essential features of the present invention. In addition, sub-combinations of these feature groups can also constitute inventions.

Description of the drawings

FIG. 1 shows the lens structure and image plane IM of the lens system 100 in the first embodiment at the same time.

FIG. 2 shows spherical aberration, astigmatism, and distortion aberration in the infinity focus state of the lens system 100 of the first embodiment.

FIG. 3 shows the lens structure, optical component P, and image plane IM of the lens system 200 in the second embodiment at the same time.

FIG. 4 shows spherical aberration, astigmatism, and distortion aberration in the infinity focus state of the lens system 200 of the second embodiment.

FIG. 5 shows the lens structure, optical component P, and image plane IM of the lens system 300 in the third embodiment at the same time.

FIG. 6 shows spherical aberration, astigmatism, and distortion aberration in the infinity focus state of the lens system 300 of the third embodiment.

FIG. 7 schematically shows an example of a mobile body system 10 including an unmanned aerial vehicle (UAV) 40 and a controller 50.

Fig. 8 shows an example of the functional blocks of UAV40.

FIG. 9 is an external perspective view showing an example of the stabilizer 3000.

Symbol Description:

10 Mobile system

40 UAV

50 Controller

52 Operation Department

54 Display

1101 UAV main body

1102 Interface

1104 Control Department

1106 memory

1110 Universal Joint

1112 Control Department

1114, 1116, 1118 drive

1124, 1126, 1128 drive unit

1130 Supporting Organization

1134, 1136, 1138 Rotating mechanism

1140 Camera Department

1160 lens device

1161 Drive mechanism

1162 Control Department

1163 memory

1168 Lens System

1220, 1230 Camera device

1221 Image sensor

1222 Control Department

1223 Memory

1231 Image sensor

1232 Control Department

1233 Memory

1234 Control Department

1235 lens

100, 200, 300 lens system

3000 stabilizer

3001 Device holder

3002 mobile equipment

3003 Handheld

3004 Shutter button

3005 Video button

3006 Operation button

3007 bracket

3009 translation axis

3010 Rolling shaft

3011 Tilt axis

3013 Camera unit

3014 Slot

3020 Universal Joint

Detailed ways

Hereinafter, the present invention will be described through the embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, all the feature combinations described in the embodiments are not necessarily necessary for the solution of the invention. It is obvious to a person of ordinary skill in the art that various changes or improvements can be made to the following embodiments. It is obvious from the description of the claims that all such changes or improvements can be included in the technical scope of the present invention.

The claims, the description, the drawings of the description, and the summary of the description include matters that are the objects of copyright protection. As long as anyone makes copies of these files as indicated in the patent office's documents or records, the copyright owner will not raise an objection. However, in other cases, all copyrights are reserved.

An embodiment of a lens system is disclosed in conjunction with FIGS. 1 to 6. As shown in each embodiment, the lens system of one embodiment includes, in order from the object side: a first lens group, a diaphragm, a positive second lens group, a negative third lens group, and a positive fourth lens group. Two negative meniscus lenses with convex surfaces facing the object side are arranged in the first lens group closest to the object side. The third lens group is composed of two or less lenses. The fourth lens group includes at least one positive lens and a negative lens, and the negative lens is disposed closest to the image side. When focusing on a subject from infinity to a short distance, the third lens group moves to the image side. Let f1 be the focal length of the first lens group, f4 be the focal length of the fourth lens group, f be the focal length of the entire system, and vd1-2 are the two negative meniscuses of the first lens group The average Abbe number of the lens at line d satisfies the conditional formula:

3.5＜|f1/f|...(1)

2.1＜f4/f＜5...(2)

vd1-2>50...(3).

Conditional expression (1) specifies the relationship between the focal length of the first lens group and the focal length of the entire system. If it is below the lower limit of conditional expression (1), the refractive power of the first lens group is too strong, so it is difficult to correct aberrations generated off-axis, and performance degradation due to eccentricity errors becomes large.

Conditional expression (2) specifies the relationship between the focal length of the fourth lens group and the focal length of the entire system. If it is more than the upper limit of the conditional expression (2), the refractive power of the fourth lens group becomes weak and the total length becomes longer. On the other hand, if it is below the lower limit of the conditional expression (2), the refractive power of the fourth lens group becomes stronger, it is difficult to correct aberrations with a smaller number of lenses, and the aberration variation caused by the subject distance becomes larger.

Conditional expression (3) specifies the average Abbe number at the d-line of the two negative meniscus lenses of the first lens group. If it is below the lower limit of the conditional expression, the chromatic aberration of magnification becomes large, and aberration correction becomes difficult.

If the negative part group of the first lens group is the 1-a group and the positive part group of the first lens group is the 1-b group, then the 1-a group includes at least three negative lenses and one positive lens group. lens. Let f1a be the focal length of the lens group 1-a, which satisfies the conditional formula:

-1.2<f1a/f<-0.6...(4).

Conditional expression (4) specifies the relationship between the focal length of the 1-a group and the focal length of the entire system. If it exceeds the upper limit of the conditional expression (4), the refractive power of the 1-a group becomes stronger, and correction of off-axis aberration becomes difficult. On the other hand, if it is less than the lower limit of the conditional expression (4), the refractive power required for wide viewing angle becomes weak, and it is difficult to reduce the size.

Let f34 be the combined focal length of the third lens group and the fourth lens group, and satisfy the conditional formula:

5.5<|f34/f|...(5).

Conditional expression (5) specifies the relationship between the combined focal length of the third lens group and the fourth lens group when focusing on an infinite subject and the focal length of the entire system. If the lower limit of the conditional expression is exceeded, since the refractive power of the third lens group and subsequent lenses becomes stronger, the aberration variation caused by the subject distance becomes larger.

f3 is the focal length of the third lens group, which satisfies the conditional formula:

-5<f3/f<-1.5...(6).

Conditional expression (6) specifies the relationship between the focal length of the third lens group and the focal length of the entire system. If it is more than the upper limit of the conditional expression, the refractive power of the third lens group becomes stronger, it is difficult to correct aberrations with two or less configurations, and the aberration variation caused by the subject distance also becomes larger. On the other hand, if it is below the lower limit of conditional expression (6), the refractive power of the third lens group becomes weak, and the range of movement of the third lens group for focusing from the shortest shooting distance to infinity becomes larger, and the total length Shortening becomes difficult.

Let β3 be the lateral magnification of the third lens group when focusing on an infinity subject, and β4 be the lateral magnification of the fourth lens group when focusing on an infinite subject, satisfying the conditional formula:

(1-β3 ² )×β4 ² <-0.4...(7).

Conditional expression (7) uses the lateral magnification of the third lens group and the lateral magnification of the fourth lens group when focusing on an infinite subject, how much the focus point on the imaging surface side moves when the third lens group is moved by a unit amount Make regulations. If it exceeds the upper limit of the conditional expression (7), the range of motion for focusing from the shortest shooting distance to infinity becomes larger, and it becomes difficult to shorten the total length.

Let f1-b be the focal length of the 1-b group, f2 be the focal length of the second lens group, and satisfy the conditional formula:

0.4<f1-b/f2<1.2...(8).

Conditional expression (8) specifies the relationship between the focal length of the 1-b group and the focal length of the second lens group. By satisfying the conditional expression (8), the on-axis light can effectively divide the positive component required for the reduction of the total length before and after the high aperture, and the on-axis aberration can be effectively corrected.

In addition, by satisfying the following conditional expressions, the above-mentioned effects can be made more remarkable.

0.6<f1-b/f2<1.0...(8-1).

As described above, according to the above-mentioned lens system, a large-aperture wide-angle lens system including high resolution can be provided. In addition, it is possible to provide a lens system including a lightweight movable group.

In addition, when the terms "consisting of ～", "consisting of ～", and "consisting of ～" are used in this specification, in addition to the listed constituent elements, lenses having substantially no refractive power may be included. , Diaphragms, filters, glass cover sheets, and other mechanical elements such as non-lens optical elements with substantial refractive power and/or lens flanges, imaging elements, and shake correction mechanisms. For example, when the terms "consisting of X", "consisting of X", and "consisting of X" are used, on the basis of X, non-lens optical elements and/or mechanism elements having substantially refractive power may be included.

Hereinafter, an example in which specific numerical values are applied to specific embodiments of the lens system will be described. First, the meaning of symbols and the like used in the description of each embodiment of the lens system will be described.

As lens data, a table indicating surface number, radius of curvature, surface interval, refractive index, and Abbe number is disclosed. In the table of lens data, the surface number is shown in the surface number column, with the surface closest to the object side as the first surface, and the surface number is sequentially increased toward the image side. The R column shows the radius of curvature of each surface. Column D shows the surface spacing on the optical axis between each surface and the surface adjacent to the image side. In addition, the column Nd shows the refractive index of each optical element with respect to the d-line (wavelength 587.6 nm (nanometer)), and the column vd shows the Abbe number based on the d-line of each optical element. Among them, the sign of the radius of curvature is positive when the surface shape is convex toward the object side, and negative when the surface shape is convex toward the image surface. The "INF" in the radius of curvature indicates that the surface is flat.

The lens data also includes the aperture stop S. The term “STO” is shown in the surface number column of the surface corresponding to the aperture stop S.

In the lens data, the surface number of the aspheric surface is marked with *, and the value of the paraxial curvature radius is shown in the curvature radius column. In addition, for the embodiment of the lens system having aspheric surfaces, a table including aspheric surface data including the surface numbers of the aspheric surfaces, the aspheric surface coefficients related to each aspheric surface, and the conic constant is attached. In the aspheric data table, "E±n" (n: natural number) of the numerical value of the aspheric coefficient is expressed as an exponent based on 10. That is, "E±n" means "×10 ^±n ". For example, "0.12345E-05" means "0.12345×10 ^-5 ". Let "zd" be the distance from the vertex of the lens surface in the optical axis direction (sag), "h" be the distance (height) in the direction perpendicular to the optical axis direction, and "c" be the distance at the vertex of the lens Paraxial curvature (the reciprocal of the radius of curvature), "k" is the conic constant (cone constant), and "Am" is the m-order aspheric coefficient, then the aspheric shape is defined by the following formula:

zd=ch ² /(1+(1-(1+k)c ² h ² ) ^1/2 )+∑Am*h ^m .

In addition, Σ represents the sum with respect to m.

In addition, a table of specification data of the lens system of each example is attached. In the specification data sheet, "f" means focal length. "Fno" represents the F number. "Ω" represents half angle of view (maximum half angle of view). "Y" represents the maximum image height. "TTL" means the total length of the optics.

In the table of lens data, changed surface interval data, and lens system specification data, "degree" is used as the angle unit, and "mm" is used as the length unit. However, since the lens system can be scaled up or down, it is possible to use other arbitrary units.

In addition, when the lens system is mounted on an imaging device as an imaging lens, it is preferable to include various filters such as a low-pass filter corresponding to the specifications of the imaging device, and optical elements such as a cover glass for protection. As the lens system of the present embodiment, it is possible to adopt a method including related optical elements or a method not including optical elements. It can be said that a lens system including related optical elements and a lens system not including optical elements are equivalent lens systems.

"Gi" represents a lens group. The i after the character G in "Gi" is a natural number, which is used to identify the lens group included in the lens system in each embodiment. The lens group includes more than one lens. "Lj" represents a lens. The j after the character L in "Lj" is a natural number, which is used to identify the lens included in the lens system in each embodiment. In the description of each embodiment, the lens to which the symbol Lj is assigned does not mean that the lens to which the same symbol Lj is assigned in the other embodiments is the same lens. Similarly, a lens or lens group assigned a specific symbol in a certain embodiment does not mean that the lens or lens group assigned the same symbol in other embodiments is the same lens or lens group.

FIG. 1 shows the lens structure of the lens system 100 and the image plane IM in the first embodiment at the same time.

The lens system 100 of the first embodiment is composed of a first lens group G1 including a positive refractive power, an aperture stop S, a second lens group G2 including a positive refractive power, and a third lens group G3 including a negative refractive power, in order from the object side. And the fourth lens group G4 including positive refractive power is constituted. The third lens group G3 is movable for focusing. The arrow corresponding to the third lens group G3 of FIG. 1 indicates the moving direction of the third lens group G3, where G3 is an active group when focusing from an infinite object to a close object.

The first lens group G1 includes: a group G1-a composed of three negative meniscus lenses L1, L2, and L3 with a convex surface facing the object side, a double-convex positive lens L4, and a negative lens L5 with a concave surface facing the object side; And a group G1-b consisting of a double-convex positive lens L6, a cemented lens of a negative lens L7, and a positive lens L8. The negative refractive power required for wide-angle is shared by at least three negative-component lenses, so that off-axis aberrations can be corrected well.

The second lens group G2 is composed of a positive lens L9 having a convex shape toward the object side and a cemented lens of a positive lens L10 and a negative lens L11, and the cemented lens has positive refractive power. The refractive power required by the second lens group G2 is shared by at least two positive-component lenses, and the correction of on-axis aberrations and off-axis aberrations can be achieved with a good balance.

The third lens group G3 is composed of a cemented lens of a biconvex positive lens L12 and a biconcave negative lens L13, and the cemented lens has negative refractive power. As a result, the weight of the active group can be reduced.

The fourth lens group G4 is composed of a biconvex positive lens L14 and a biconcave negative lens L15. The fourth lens group G4 includes at least one positive lens and a negative lens, so that off-axis aberration can be corrected well.

Table 1 shows lens data of the lens system 100 of the first embodiment. Table 2 is a table showing aspheric surface data of the lens system 100.

【Table 1】

Face number	R	D	Nd	Vd
1	46.846	2.000	1.72916	54.67
2	18.500	8.301	To	To
3*	37.064	1.800	1.59201	67.02
4*	19.551	2.277	To	To
5	31.301	1.800	1.49700	81.61
6	20.015	6.196	To	To
7	120.868	4.117	1.84666	23.78
8	-80.175	2.437	To	To
9	-32.111	1.400	1.49700	81.61
10	444.659	10.035	To	To
11	58.170	4.965	1.83481	42.72
12	-64.048	3.602	To	To
13	44.798	1.200	1.84666	23.78
14	18.127	6.436	1.49700	81.61
15	-1697.802	3.761	To	To
STO	INF	1.800	To	To
17	67.614	2.350	1.87070	40.73
18	581.278	0.200	To	To
19	80.824	4.000	1.49700	81.61
20	-36.642	1.200	1.76182	26.61
twenty one	-55.556	1.605	To	To
twenty two	97.682	4.430	1.80809	22.76
twenty three	-22.774	1.200	1.90366	31.32
twenty four	26.550	4.623	To	To
25*	30.6528	8.412	1.61881	63.85
26*	-27.7534	1.754	To	To
27*	-200.0000	1.600	1.85135	40.1
28*	45.2449	21.500	To	To
29	INF	0.000	To	To

【Table 2】

Face number	K	A4	A6	A8	A10
3	-1.31929E+00	1.89044E-05	-9.58812E-08	3.32946E-10	-4.53077E-13
4	-4.69573E-01	1.20000E-05	-1.70533E-07	5.73690E-10	-1.20658E-12
25	0.00000E+00	4.95402E-06	7.40811E-08	-5.04849E-10	0.00000E+00
26	0.00000E+00	4.04665E-06	-1.41909E-07	3.45191E-10	0.00000E+00
27	1.00000E+01	-8.00000E-05	-2.05065E-07	1.18143E-09	2.83140E-12
28	8.51871E+00	-6.44154E-05	-1.07772E-07	2.14986E-09	-5.80070E-12

Table 3 is a table showing the specification data of the focal length f, F number-Fno, half angle of view ω, image height Y, and optical total length TTL of the entire system when the lens system 100 of the first embodiment focuses on an infinity subject .

【table 3】

To	INF
F	19.60
Fno	2.05
Ω	48.75
Y	21.7
TTL	115.00

FIG. 2 shows spherical aberration, astigmatism, and distortion aberration of the lens system 100 in a state where the lens system 100 is focused on a subject at infinity. In the spherical aberration, the one-dot chain line represents the value of the C line (656.27 nm), the solid line represents the value of the d line (587.56 nm), and the broken line represents the value of the g line (435.84 nm). In astigmatism, the solid line represents the value of the sagittal image surface of the d-line, and the broken line represents the value of the meridional image surface of the d-line. The value of the d-line is shown in the distortion aberration. From the various aberration diagrams, it is obvious that various aberrations in the lens system 100 of the first embodiment are well corrected and have excellent imaging performance.

FIG. 3 shows the lens structure, optical component P, and image plane IM of the lens system 200 in the second embodiment at the same time.

The lens system 200 of the second embodiment is composed of a first lens group G1 having a positive refractive power, an aperture stop S, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power in order from the object side. And the fourth lens group G4 having positive refractive power is constituted. The third lens group G3 is movable for focusing. The arrow corresponding to the third lens group G3 of FIG. 3 indicates the moving direction of the third lens group G3, where G3 is an active group when focusing from an infinitely distant subject to a short-distance subject.

The first lens group G1 includes: a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, a biconcave negative lens L3, and a biconvex positive lens L4 A group G1-a composed of a cemented lens and a negative lens L5 with a concave surface facing the object side; and a group G1-b composed of a cemented lens of a double convex positive lens L6, a negative lens L7, and a positive lens L8. The negative refractive power required for wide-angle is shared by at least three negative-component lenses, and off-axis aberrations can be corrected well.

The second lens group G2 is composed of a cemented lens of a positive lens L9 and a negative lens L10 with a concave surface facing the object side, and a double-convex positive lens L11, wherein the cemented lens has positive refractive power. The refractive power required by the second lens group G2 is shared by at least two positive components, and the on-axis aberration and off-axis aberration can be corrected with a good balance.

The third lens group G3 is composed of a negative lens L12 whose concave surface faces the image side. The third lens group G3 is composed of a negative lens L12, so the weight of the movable group can be reduced.

The fourth lens group G4 is composed of a biconvex positive lens L13, a positive lens L14 whose convex surface faces the image side, and a negative lens L15 whose concave surface faces the image side. The fourth lens group G4 includes at least one positive lens and a negative lens, thereby being able to correct off-axis aberrations well.

Table 4 shows lens data of the lens system 200 of the second embodiment. Table 5 is a table showing aspheric surface data of the lens system 200.

【Table 4】

Face number	R	D	Nd	Vd
1	37.800	2.000	1.72916	54.67
2	18.650	7.542	To	To
3	29.268	1.500	1.58313	59.46
4	14.800	9.495	To	To
5	-106.447	1.500	1.49700	81.54
6	24.680	7.345	1.85478	24.8
7	-124.877	4.052	To	To
8	-34.483	1.400	1.92286	20.88
9	1,654.189	4.098	To	To
10	85.054	3.981	1.95375	32.32
11	-59.466	3.299	To	To
12	38.334	1.200	1.84666	23.78
13	17.949	5.817	1.49700	81.61
14	-3662.700	3.050	To	To
STO	INF	1.738	To	To
16	1000.000	4.975	1.49700	81.61
17	-20.110	1.200	1.68893	31.16
18	-60.949	1.880	To	To
19	66.592	3.274	1.84666	23.78
20	-108.025	1.612	To	To
twenty one	112.912	1.200	1.69350	53.20
twenty two	37.654	4.827	To	To
twenty three	33.201	5.440	1.59349	67.00
twenty four	-51.023	0.219	To	To
25	-192.8020	3.384	1.49700	81.61
26	-37.6637	0.250	To	To
27	200.0000	1.400	1.8061	40.73
28	22.8137	23.512	To	To
29	INF	2.810	1.51680	64.2
30	INF	1.000	To	To
31	INF	0	To	To

【table 5】

Face number	K	A4	A6	A8	A10
3	9.91564E-01	-9.59456E-06	-4.47618E-08	1.20474E-10	-2.61527E-13
4	-1.01981E+00	1.62544E-05	-5.93988E-08	2.17241E-10	-6.05126E-13
twenty one	-7.53708E+00	-1.07877E-05	1.67507E-07	-8.91835E-10	1.82227E-12
twenty two	2.22117E+00	-1.32507E-05	1.66267E-07	-8.45337E-10	1.57773E-12
27	-1.00000E+01	-3.60000E-05	3.18734E-08	1.95249E-12	-6.48619E-13
28	-4.63702E+00	3.79013E-05	-8.45695E-08	4.44540E-10	-1.74219E-12

Table 6 is a table showing the specification data of the focal length f, F number Fno, half angle of view ω, image height Y, and total optical length TTL of the entire system when the lens system 200 of the second embodiment focuses on an infinity subject.

【Table 6】

To	INF
f	20.50
Fno	2.05
ω	47.16
Y	21.7
TTL	115.00

FIG. 4 shows spherical aberration, astigmatism, and distortion aberration of the lens system 200 in a focused state of an infinity subject. In the spherical aberration, the one-dot chain line represents the value of the C line (656.27 nm), the solid line represents the value of the d line (587.56 nm), and the broken line represents the value of the g line (435.84 nm). In astigmatism, the solid line represents the value of the sagittal image surface of the d-line, and the broken line represents the value of the meridional image surface of the d-line. The value of the d-line is shown in the distortion aberration. From the various aberration diagrams, it is obvious that various aberrations in the lens system 200 of the second embodiment are well corrected and have excellent imaging performance.

FIG. 5 shows the lens structure, optical component P, and image plane IM of the lens system 300 in the third embodiment at the same time.

The lens system 300 of the second embodiment is composed of a first lens group G1 having a positive refractive power, an aperture stop S, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power in order from the object side. And the fourth lens group G4 having positive refractive power is constituted. The third lens group G3 is movable for focusing. The arrow corresponding to the third lens group G3 in FIG. 5 indicates the moving direction of the third lens group G3, where G3 is an active group when focusing from an infinitely distant subject to a short-distance subject.

The first lens group G1 includes: a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, a biconcave negative lens L3, and a biconvex positive lens L4 A group G1-a consisting of a cemented lens and a negative lens L5 with a concave surface facing the object side; and a group G1-b consisting of a cemented lens of a double-convex positive lens L6, a negative lens L7, and a positive lens L8. The negative refractive power required for wide-angle is shared by at least three negative-component lenses, and off-axis aberrations can be corrected well.

The second lens group G2 is composed of a cemented lens of a positive lens L9 and a negative lens L10 with a concave surface facing the object side, and a double-convex positive lens L11, wherein the cemented lens has positive refractive power. The refractive power required by the second lens group G2 is shared by at least two positive components, and a good balance can be achieved for the correction of on-axis aberration and off-axis aberration.

The third lens group G3 is composed of a negative lens L12 whose concave surface faces the image side. As a result, the weight of the active group can be reduced.

The fourth lens group G4 is composed of a positive lens L13 having a biconvex shape, a negative lens L14 with a concave surface facing the image side, and a negative lens L15 with a concave surface facing the object side. The fourth lens group G4 includes at least one positive lens and a negative lens, thereby being able to correct off-axis aberrations well.

Table 7 shows lens data of the lens system 300 of the third embodiment. Table 8 is a table showing aspheric surface data of the lens system 300.

【Table 7】

Face number	R	D	Nd	Vd
1	38.850	1.800	1.72916	54.67
2	18.600	7.380	To	To
3	29.500	1.500	1.58313	59.46
4	15.099	9.770	To	To
5	-78.586	1.350	1.49700	81.61
6	29.281	6.960	1.85451	25.15
7	-84.822	3.840	To	To
8	-30.000	1.400	1.80809	22.76
9	-281.310	3.990	To	To
10	83.670	4.790	1.91082	35.25
11	-55.307	3.720	To	To
12	35.491	1.200	1.84666	23.78
13	17.468	5.860	1.49700	81.61
14	1054.100	3.100	To	To
STO	INF	2.500	To	To
16	1,833.150	5.230	1.49700	81.61
17	-18.048	1.200	1.69895	30.05
18	-81.899	1.130	To	To
19	89.150	3.970	1.84666	23.78
20	-55.555	1.604	To	To
twenty one	111.366	1.200	1.69350	53.20
twenty two	33.773	4.364	To	To
twenty three	28.243	6.730	1.49700	81.61
twenty four	-36.942	0.150	To	To
25	125.9340	1.300	1.54814	45.82
26	25.7790	4.540	To	To
27	-90.0000	1.500	1.85135	40.1
28	-128.0000	19.110	To	To
29	INF	2.810	1.51680	64.2
30	INF	1.000	To	To

【Table 8】

Face number	K	A4	A6	A8	A10
3	-8.50000E-01	-3.40000E-06	5.82961E-09	-3.95187E-12	-1.77210E-14
4	-9.39700E-01	5.40148E-06	-1.95540E-08	7.10116E-11	-4.56971E-13
twenty one	7.23532E-02	-1.70573E-05	2.50484E-07	-1.28883E-09	3.17837E-12
twenty two	-1.00000E+01	1.79304E-05	1.65745E-07	-1.02508E-09	3.01533E-12
27	1.00000E+01	-3.20000E-05	9.18610E-08	-7.39667E-11	-5.95471E-13
28	-9.95931E+00	-1.12018E-05	1.08126E-07	2.09143E-11	-5.32619E-13

Table 9 is a table showing the specification data of the focal length f, F number-Fno, half angle of view ω, image height Y, and optical total length TTL of the entire system when the lens system 300 of the third embodiment focuses on an infinite subject. .

【Table 9】

To	INF
f	20.50
Fno	2.06
ω	47.20
Y	21.7
TTL	115.00

FIG. 6 shows spherical aberration, astigmatism, and distortion aberration of the lens system 300 in a state of focusing on an infinite subject. In the spherical aberration, the one-dot chain line represents the value of the C line (656.27 nm), the solid line represents the value of the d line (587.56 nm), and the broken line represents the value of the g line (435.84 nm). In astigmatism, the solid line represents the value of the sagittal image surface of the d-line, and the broken line represents the value of the meridional image surface of the d-line. The value of the d-line is shown in the distortion aberration. From the various aberration diagrams, it is obvious that the lens system 300 of the third embodiment has various aberrations well corrected and has excellent imaging performance.

Table 10 shows the corresponding values of the conditional expressions (1) to (8) in the lens system from the first embodiment to the third embodiment. Table 11 and Table 12 show respective numerical values related to conditional expressions (1) to (8).

【Table 10】

【Table 11】

To	f	f1	f2	f3	f4
The first embodiment	19.614	77.194	42.729	-34.369	46.056
Second embodiment	20.511	700.128	44.098	-81.997	83.226
The third embodiment	20.513	123.327	44.613	-70.342	78.395

【Table 12】

To	vd1-2	f1a	f1b	f34	β3	β4
The first embodiment	60.845	-19.229	36.638	-152.671	3.800	0.327
Second embodiment	57.065	-16.523	33.456	-1227.948	1.904	0.515
The third embodiment	57.065	-17.845	32.749	-653.467	1.970	0.533

As described above, according to the lens system of this embodiment, it is possible to provide a large-aperture wide-angle lens system including high resolution. In addition, it is possible to provide a lens system including a lightweight movable group. This enables high-speed focusing.

In addition, the configurations included in the above-mentioned lens system can be combined arbitrarily, and can be appropriately and selectively adopted according to the required specifications. For example, the lens system based on the above-mentioned embodiment may satisfy the conditional expressions (1) to (8) and (8-1) on the basis of satisfying conditional expressions (1) to (8) and (8-1). Any one can also satisfy any combination of these conditional expressions.

As mentioned above, the present invention has been described by enumerating the embodiments and examples, but the present invention is not limited to the above-mentioned embodiments and examples, and various modifications can be made. For example, the radius of curvature, the surface interval, the refractive index, and the Abbe number of each lens are not limited to the values shown in the foregoing embodiments, and other values may be adopted.

The lens system according to this embodiment can be applied to lens systems for imaging devices such as digital cameras and video cameras. The lens system according to this embodiment can be applied to a lens system that does not include a zoom mechanism. The lens system according to this embodiment can be applied to lens systems such as aerial cameras and surveillance cameras. The lens system according to this embodiment can be applied to an imaging lens included in a non-interchangeable lens type imaging device. The lens system according to this embodiment can be applied to interchangeable lenses of interchangeable lens cameras such as single-lens reflex cameras.

Hereinafter, as an example of a system including the lens system according to this embodiment, a moving body system will be described.

FIG. 7 schematically shows an example of a mobile body system 10 including an unmanned aerial vehicle (UAV) 40 and a controller 50. The UAV 40 includes a UAV main body 1101, a universal joint 1110, a plurality of camera devices 1230, and a camera device 1220. The imaging device 1220 includes a lens device 1160 and an imaging unit 1140. The lens device 1160 includes the above-mentioned lens system. The UAV40 is an example of a moving body that includes the imaging device having the above-mentioned lens system and moves. The mobile body refers to a concept that includes other airplanes that move in the air, vehicles that move on the ground, and ships that move on the water in addition to UAVs.

The UAV main body 1101 includes a plurality of rotors. The UAV main body 1101 makes the UAV 40 fly by controlling the rotation of a plurality of rotors. The UAV main body 1101 uses, for example, four rotors to fly the UAV 40. The number of rotors is not limited to four. UAV40 can also be a fixed-wing aircraft without rotors.

The imaging device 1230 is an imaging camera that captures a subject included in a desired imaging range. The plurality of imaging devices 1230 are sensing cameras that photograph the surroundings of the UAV 40 in order to control the flight of the UAV 40. The camera 1230 may be fixed on the UAV main body 1101.

The two camera devices 1230 can be installed on the nose of the UAV 40, that is, on the front side. In addition, the other two camera devices 1230 can be installed on the bottom surface of the UAV 40. The two camera devices 1230 on the front side can be paired to function as a so-called stereo camera. The two imaging devices 1230 on the bottom side can also be paired to function as a stereo camera. The three-dimensional spatial data around the UAV 40 can be generated based on the images captured by the plurality of camera devices 1230. The distance to the subject captured by the plurality of imaging devices 1230 can be determined by the stereo cameras of the plurality of imaging devices 1230.

The number of camera devices 1230 included in the UAV 40 is not limited to four. The UAV40 only needs to include at least one camera 1230. The UAV40 may also include at least one camera 1230 on the nose, tail, sides, bottom and top of the UAV40. The camera 1230 may also include a single focus lens or a fisheye lens. In the description related to UAV40, the plurality of imaging devices 1230 may be simply collectively referred to as imaging devices 1230.

The controller 50 includes a display unit 54 and an operation unit 52. The operation unit 52 receives an input operation for controlling the posture of the UAV 40 from the user. The controller 50 transmits a signal for controlling the UAV 40 in accordance with the user's operation received by the operation unit 52.

The controller 50 receives an image captured by at least one of the camera 1230 and the camera 1220. The display section 54 displays the image received by the controller 50. The display part 54 may be a touch panel. The controller 50 may receive input operations from the user through the display part 54. The display unit 54 can receive a user operation or the like that the user specifies the position of the subject to be photographed by the imaging device 1220.

The imaging unit 1140 generates and records image data of an optical image formed by the lens device 1160. The lens device 1160 may be integrally provided on the imaging unit 1140. The lens device 1160 may be a so-called interchangeable lens. The lens device 1160 can be detachably installed with respect to the imaging unit 1140.

The universal joint 1110 includes a supporting mechanism that movably supports the camera device 1220. The camera device 1220 is mounted on the UAV main body 1101 through a universal joint 1110. The universal joint 1110 rotatably supports the imaging device 1220 around the pitch axis. The universal joint 1110 rotatably supports the imaging device 1220 with the roll axis as the center. The universal joint 1110 rotatably supports the camera device 1220 around the yaw axis. The universal joint 1110 can rotatably support the camera device 1220 around at least one of the pitch axis, the roll axis, and the yaw axis. The universal joint 1110 can rotatably support the camera device 1220 around the pitch axis, the roll axis, and the yaw axis, respectively. The universal joint 1110 may also hold the imaging unit 1140. The universal joint 1110 may also hold the lens device 1160. The universal joint 1110 can rotate the imaging unit 1140 and the lens device 1160 around at least one of the yaw axis, the pitch axis, and the roll axis, thereby changing the imaging direction of the imaging device 1220.

Fig. 8 shows an example of the functional blocks of UAV40. The UAV 40 includes an interface 1102, a control unit 1104, a memory 1106, a universal joint 1110, a camera unit 1140, and a lens device 1160.

The interface 1102 communicates with the controller 50. The interface 1102 receives various instructions from the controller 50. The control unit 1104 controls the flight of the UAV 40 in accordance with instructions received from the controller 50. The control unit 1104 controls the universal joint 1110, the imaging unit 1140, and the lens device 1160. The control unit 1104 may be composed of a microprocessor such as a CPU or an MPU, a microcontroller such as an MCU, and the like. The memory 1106 stores programs and the like necessary for the control unit 1104 to control the gimbal 1110, the imaging unit 1140, and the lens device 1160.

The memory 1106 may be a computer-readable recording medium. The memory 1106 may include at least one of flash memory such as SRAM, DRAM, EPROM, EEPROM, and USB memory. The storage 1106 may be provided in the housing of the UAV40. It can be set to be detachable from the UAV40 housing.

The universal joint 1110 includes a control part 1112, a driver 1114, a driver 1116, a driver 1118, a driving part 1124, a driving part 1126, a driving part 1128 and a supporting mechanism 1130. The driving part 1124, the driving part 1126, and the driving part 1128 may be electric motors.

The supporting mechanism 1130 supports the imaging device 1220. The supporting mechanism 1130 movably supports the imaging device 1220 in the imaging direction. The supporting mechanism 1130 rotatably supports the imaging unit 1140 and the lens device 1160 around the yaw axis, the pitch axis, and the roll axis. The supporting mechanism 1130 includes a rotating mechanism 1134, a rotating mechanism 1136, and a rotating mechanism 1138. The rotation mechanism 1134 uses the drive unit 1124 to rotate the imaging unit 1140 and the lens device 1160 around the yaw axis. The rotation mechanism 1136 uses the drive unit 1126 to rotate the imaging unit 1140 and the lens device 1160 around the pitch axis. The rotation mechanism 1138 uses the drive unit 1128 to rotate the imaging unit 1140 and the lens device 1160 around the roll axis.

The control unit 1112 outputs an operation command to the driver 1114, the driver 1116, and the driver 1118 in accordance with the operation command of the universal joint 1110 from the control unit 1104, and the operation command is used to indicate each rotation angle. The driver 1114, the driver 1116, and the driver 1118 drive the driving unit 1124, the driving unit 1126, and the driving unit 1128 in accordance with an operation command indicating the rotation angle. The rotation mechanism 1134, the rotation mechanism 1136, and the rotation mechanism 1138 are driven and rotated by the drive unit 1124, the drive unit 1126, and the drive unit 1128, respectively, thereby changing the postures of the imaging unit 1140 and the lens device 1160.

The imaging unit 1140 uses the light passing through the lens system 1168 to perform imaging. The imaging unit 1140 includes a control unit 1222, an imaging element 1221, and a memory 1223. The control unit 1222 may be constituted by a microprocessor such as a CPU or an MPU, a microcontroller such as an MCU, or the like. The control unit 1222 performs focus control of the lens system 1168. The control unit 1222 controls the imaging unit 1140 and the lens device 1160 in accordance with the operation instructions for the imaging unit 1140 and the lens device 1160 from the control unit 1104. The control unit 1222 outputs a control command for the lens device 1160 to the lens device 1160 according to the signal received from the controller 50. In addition to an instruction to move the lens group responsible for focusing, the control instruction may also include an instruction to vibrate the lens system 1168, an instruction to detect the temperature of the lens system 1168, and the like.

The memory 1223 may be a computer-readable recording medium, and may include at least one of flash memory such as SRAM, DRAM, EPROM, EEPROM, and USB memory. The memory 1223 may be provided inside the housing of the imaging unit 1140. The imaging unit 1140 can be configured to be detachable from the housing.

The imaging element 1221 is held inside the housing of the imaging unit 1140, generates image data of an imaged optical image through the lens device 1160, and outputs the image data to the control unit 1222. The imaging element 1221 converts the optical image formed by the lens system 1168 into an electric signal. For example, the imaging element 1221 may be a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor, complementary MOS) or the like. The imaging element 1221 is provided such that the imaging surface thereof coincides with the image surface of the lens system 1168. The image taken by the lens system 1168 is formed on the imaging surface of the imaging element 1221 and output from the imaging element 1221 as image data. The control unit 1222 performs signal processing on the image data output from the imaging element 1221 and stores it in the memory 1223. The control unit 1222 may output the image data to the memory 1106 through the control unit 1104 and store it.

The lens device 1160 includes a control unit 1162, a memory 1163, a driving mechanism 1161, and a lens system 1168. The lens system 1168 can apply the lens system according to the above-mentioned embodiments and examples.

The control unit 1162 can drive the lens system 1168 according to a control command from the control unit 1222. The driving mechanism 1161 can move one or more lens groups and the aperture stop included in the lens system 1168 in the optical axis direction according to a control command from the control unit 1162, thereby adjusting the focus of the lens system 1168. The driving mechanism 1161 can control the aperture stop included in the lens system 1168 according to a control command from the control unit 1162. The driving mechanism 1161 can vibrate the lens system 1168 in accordance with a control command from the control unit 1162. The driving mechanism 1161 includes, for example, an actuator and the like. The imaging unit 1140 captures an image formed by the lens system 1168 of the lens device 1160.

The lens device 1160 may be integrally provided on the imaging unit 1140. The lens device 1160 may be a so-called interchangeable lens. The lens device 1160 can be detachably installed with respect to the imaging unit 1140.

The imaging device 1230 includes a control unit 1232, a control unit 1234, an imaging element 1231, a memory 1233, and a lens 1235. The control unit 1232 may be constituted by a microprocessor such as a CPU or an MPU, a microcontroller such as an MCU, or the like. The control unit 1232 controls the imaging element 1231 in accordance with the operation command of the imaging element 1231 from the control unit 1104.

The control unit 1234 may be constituted by a microprocessor such as a CPU or an MPU, a microcontroller such as an MCU, or the like. The control unit 1234 can adjust the focus of the lens 1235 in accordance with the operation instruction for the lens 1235. The control unit 1234 can control the aperture stop included in the lens 1235 in accordance with an operation command for the lens 1235.

The memory 1233 may be a computer-readable recording medium. The memory 1233 may include at least one of flash memory such as SRAM, DRAM, EPROM, EEPROM, and USB memory.

The imaging element 1231 generates image data of an optical image formed by the lens 1235, and outputs it to the control unit 1232. The control unit 1232 stores the image data output from the imaging element 1231 in the memory 1233.

In this embodiment, the UAV 40 includes a control unit 1104, a control unit 1112, a control unit 1222, a control unit 1232, a control unit 1234, and a control unit 1162. However, the processing performed by a plurality of the control unit 1104, the control unit 1112, the control unit 1222, the control unit 1232, the control unit 1234, and the control unit 1162 may be executed by any one control unit. The processing executed by the control unit 1104, the control unit 1112, the control unit 1222, the control unit 1232, the control unit 1234, and the control unit 1162 may also be executed by one control unit. In this embodiment, the UAV 40 includes a memory 1106, a memory 1223, and a memory 1233. The information stored in at least one of the storage 1106, the storage 1223, and the storage 1233 may be stored in one or more other storages among the storage 1106, the storage 1223, and the storage 1233.

The imaging device 1220 includes the lens device 1160 including the lens system according to the above-mentioned embodiments and examples, thereby being able to provide an unmanned aircraft with high image quality, bright, wide-angle shooting, and high-speed focusing.

Hereinafter, as an example of a system including the lens system according to the above-mentioned embodiments and examples, a stabilizer will be described.

FIG. 9 is an external perspective view showing an example of the stabilizer 3000. The stabilizer 3000 is another example of a moving body. For example, the camera unit 3013 included in the stabilizer 3000 may include an imaging device having the same configuration as the imaging device 1220. The camera unit 3013 may include a lens device of the same configuration as the lens device 1160.

The stabilizer 3000 includes a camera unit 3013, a universal joint 3020, and a handle 3003. The universal joint 3020 rotatably supports the camera unit 3013. The universal joint 3020 includes a translation shaft 3009, a roll shaft 3010, and a tilt shaft 3011. The universal joint 3020 rotatably supports the camera unit 3013 centered on the translation shaft 3009, the roll shaft 3010, and the tilt shaft 3011. The universal joint 3020 is an example of a supporting mechanism.

The camera unit 3013 is an example of an imaging device. The camera unit 3013 includes a slot 3014 into which a memory is inserted. The universal joint 3020 is fixed on the handle 3003 by a bracket 3007.

The handle 3003 includes various buttons for operating the universal joint 3020 and the camera unit 3013. The handheld portion 3003 includes a shutter button 3004, a recording button 3005, and an operation button 3006. By pressing the shutter button 3004, a still image can be recorded by the camera unit 3013. By pressing the recording button 3005, the camera unit 3013 can record a video.

The device holder 3001 is fixed on the handle 3003. The device holder 3001 holds a mobile device 3002 such as a smart phone. The mobile device 3002 is communicably connected with the stabilizer 3000 through a wireless network such as WiFi. In this way, the image taken by the camera unit 3013 can be displayed on the screen of the mobile device 3002.

In the stabilizer 3000, the camera unit 3013 also includes the lens system according to the above-mentioned embodiment, so that it is possible to provide a stabilizer with high image quality, bright, wide-angle shooting, and high-speed focusing.

In the above, the UAV 40 and the stabilizer 3000 are cited as an example of the mobile body for description. The imaging device including the same configuration as the imaging device 1220 can be mounted on a moving body other than the UAV 40 and the stabilizer 3000.

The present invention has been described above using the embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments. It is obvious to a person of ordinary skill in the art that various changes or improvements can be made to the above-mentioned embodiments. It is obvious from the description of the claims that all such changes or improvements can be included in the technical scope of the present invention.

It should be noted that the execution order of the actions, sequences, steps, and stages in the devices, systems, programs and methods shown in the claims, descriptions and drawings, as long as there is no special indication that "in... "Before", "in advance", etc., and as long as the output of the previous processing is not used in the subsequent processing, they can be implemented in any order. Regarding the operation flow in the claims, the specification and the drawings, the description is made using "first", "next", etc. for convenience, but it does not mean that it must be implemented in this order.

Claims (9)

1. A lens system, characterized in that it includes a first lens group, a diaphragm, a positive second lens group, a negative third lens group, and a positive fourth lens group in order from the object side;

   On the side closest to the object of the first lens group, two negative meniscus lenses with convex surfaces facing the object side are arranged;

   The third lens group is composed of two or less lenses;

   The fourth lens group includes at least one positive lens and a negative lens, and the negative lens is arranged closest to the image side;

   When focusing on a subject from infinity to a short distance, the third lens group moves to the image side;

   Let f1 be the focal length of the first lens group, f4 be the focal length of the fourth lens group, f be the focal length of the entire system, and vd1-2 are the two negative meniscuses of the first lens group The average Abbe number of the lens at line d satisfies the conditional formula:

   3.5＜|f1/f|

   2.1＜f4/f＜5

   vd1-2>50.
2. The lens system according to claim 1, wherein if the negative part group of the first lens group is the 1-a group, the positive part group of the first lens group is the 1-b group,

   Then the first group 1-a includes at least three negative lenses and one positive lens,

   Let f1a be the focal length of the lens group 1-a, which satisfies the expression:

   -1.2<f1a/f<-0.6.
3. The lens system according to claim 1 or 2, wherein f34 is the composite focal length of the third lens group and the fourth lens group, and satisfies the conditional formula:

   5.5<|f34/f|.
4. The lens system according to claim 1 or 2, wherein f3 is the focal length of the third lens group, which satisfies the conditional formula:

   -5<f3/f<-1.5.
5. The lens system according to claim 1 or 2, wherein β3 is the lateral magnification of the third lens group when focusing on an infinity object, and β4 is when focusing on an infinity object. The lateral magnification of the fourth lens group satisfies the conditional formula:

   (1-β3 ² )×β4 ² <-0.4.
6. The lens system according to claim 2, wherein f1-b is the focal length of the 1-b group and f2 is the focal length of the second lens group, and the conditional expression is satisfied:

   0.4<f1-b/f2<1.2.
7. An imaging device, characterized in that it comprises the lens system according to claim 1 or 2; and

   Camera components.
8. A moving body, characterized in that it comprises the lens system according to claim 1 or 2 and moves.
9. The mobile body according to claim 8, wherein the mobile body is an unmanned aircraft.

Images