# US 2013/0155294 A1 · Zoom lens and image pickup unit

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- Number: US 2013/0155294 A1
- Document ID: US20130155294A1
- Status: Published application
- Kind: A1
- Application number: 13/680,809
- Filed: 2012-11-19
- Published: 2013-06-20
- Earliest claimed: 2011-12-20
- Assignees: Sony Corporation
- Inventors: Hideki Kai; Syuuji Maki
- Web page: https://patentgrep.com/patent/US20130155294A1

## CPC

- G02B 15/144113: {arranged +-++}
- G02B 15/173: arranged +-+
- H04N 5/262: Studio circuits, e.g. for mixing, switching-over, change of character of image, other special effects {; Cameras specially adapted for the electronic generation of special effects}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A zoom lens includes: a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power, the first to fourth lens groups being arranged in order from an object side, in which zooming is performed through varying a distance between adjacent lens groups of the first to fourth lens groups, and the fourth lens group includes a first positive lens, a first negative meniscus lens, and a cemented lens which are arranged in order from the object side, the cemented lens being configured of a second negative meniscus lens with a convex surface facing the object side and a second positive lens.

## Claims

### Claim 1

A zoom lens comprising:
a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power, the first to fourth lens groups being arranged in order from an object side,
wherein zooming is performed through varying a distance between adjacent lens groups of the first to fourth lens groups, and
the fourth lens group includes a first positive lens, a first negative meniscus lens, and a cemented lens which are arranged in order from the object side, the cemented lens being configured of a second negative meniscus lens with a convex surface facing the object side and a second positive lens.

### Claim 2 (depends on 1)

The zoom lens according to claim 1, wherein the third lens group includes a cemented lens being configured of a third meniscus lens and a positive lens, and a fourth negative meniscus lens which are arranged in order from the object side, the third meniscus lens having a convex surface facing the object side, and the fourth negative meniscus lens having a convex surface facing an image side.

### Claim 3 (depends on 1)

The zoom lens according to claim 1, wherein the following conditional expression is satisfied:
2≦f3/f4<3 (1)
where f3 is a focal length of the third lens group, and f4 is a focal length of the fourth lens group.

### Claim 4 (depends on 1)

The zoom lens according to claim 1, wherein the following conditional expression is satisfied:
4<ft/R31<5 (2)
where ft is a focal length of a whole system of the zoom lens at a telephoto end, and R31 is a radius of curvature of a lens surface located closest to the object side of the third lens group.

### Claim 5 (depends on 1)

The zoom lens according to claim 1, wherein the following conditional expression is satisfied:
0<|(R31+R35)/(R31−R35)|<1 (3)
where R31 is a radius of curvature of a lens surface located closest to the object side of the third lens group, and R35 is a radius of curvature of a lens surface located closest to an image side of the third lens group.

### Claim 6 (depends on 1)

The zoom lens according to claim 1, wherein the following conditional expression is satisfied:
2<f4r/f4<3 (4)
where f4r is a focal length of the cemented lens in the fourth lens group, and f4 is a focal length of the fourth lens group.

### Claim 7 (depends on 1)

The zoom lens according to claim 1, wherein the following conditional expression is satisfied:
|1/(f43×ν43)+1/(f44×ν44)|1<1×10−4 (5)
where f43 is a focal length of the second negative meniscus lens in the fourth lens group, ν43 is an Abbe number of the second negative meniscus lens in the fourth lens group, f44 is a focal length of the second positive lens in the fourth lens group, and ν44 is an Abbe number of the second positive lens in the fourth lens group.

### Claim 8 (depends on 1)

The zoom lens according to claim 1, wherein the following conditional expression is satisfied:
2<ft/dX1<3 (6)
where ft is a focal length of a whole system of the zoom lens at a telephoto end, and dX1 is a moving distance in an optical axis direction of the first lens group when the zooming is performed from a wide-angle end to the telephoto end.

### Claim 9 (depends on 1)

The zoom lens according to claim 1, wherein a lens surface on the object side of the first negative meniscus lens in the fourth lens group is aspheric.

### Claim 10 (depends on 1)

The zoom lens according to claim 1, wherein the first to fourth lens groups are moved when the zooming is performed from a wide-angle end to a telephoto end, to allow a distance between the first lens group and the second lens group to be increased and to allow a distance between the second lens group and the third lens group and a distance between the third lens group and the fourth lens group to be decreased.

### Claim 11

An image pickup unit with a zoom lens and an image pickup device outputting an image pickup signal based on an optical image formed by the zoom lens, the zoom lens comprising:
a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power, the first to fourth lens groups being arranged in order from an object side,
wherein zooming is performed through varying a distance between adjacent lens groups of the first to fourth lens groups, and
the fourth lens group includes a first positive lens, a first negative meniscus lens, and a cemented lens which are arranged in order from the object side, the cemented lens being configured of a second negative meniscus lens with a convex surface facing the object side and a second positive lens.