JP2009198800A - Collapsible zoom lens - Google Patents

Collapsible zoom lens Download PDF

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Publication number
JP2009198800A
JP2009198800A JP2008040153A JP2008040153A JP2009198800A JP 2009198800 A JP2009198800 A JP 2009198800A JP 2008040153 A JP2008040153 A JP 2008040153A JP 2008040153 A JP2008040153 A JP 2008040153A JP 2009198800 A JP2009198800 A JP 2009198800A
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Japan
Prior art keywords
lt
lens group
gt
sb
lens
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JP2008040153A
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Japanese (ja)
Inventor
Satoshi Miyasaka
Kazuya Watanabe
Hirotaka Yamano
聡 宮坂
裕貴 山野
和也 渡辺
Original Assignee
Sony Corp
Tamron Co Ltd
ソニー株式会社
株式会社タムロン
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Application filed by Sony Corp, Tamron Co Ltd, ソニー株式会社, 株式会社タムロン filed Critical Sony Corp
Priority to JP2008040153A priority Critical patent/JP2009198800A/en
Priority claimed from CN 200910006469 external-priority patent/CN101515057B/en
Priority claimed from US12/389,560 external-priority patent/US7848029B2/en
Publication of JP2009198800A publication Critical patent/JP2009198800A/en
Application status is Pending legal-status Critical

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Abstract

<P>PROBLEM TO BE SOLVED: To provide a collapsible zoom lens that can achieve both a wider angle and a thickness decrease while maintaining high optical performance even if, for example, an optical vibration-proof function is incorporated in this zoom lens. <P>SOLUTION: The collapsible zoom lens includes, in order from an object side, a first lens group GR<SB>1</SB>with positive refractive power, a second lens group GR<SB>2</SB>with negative refractive power, a third lens group GR<SB>3</SB>with positive refractive power, and a fourth lens group GR<SB>4</SB>with positive refractive power. The collapsible zoom lens performs variable power by independently moving the first lens group GR<SB>1</SB>, second lens group GR<SB>2</SB>, third lens group GR<SB>3</SB>, and fourth lens group GR<SB>4</SB>along its optical axis. The zoom lens satisfies a prescribed condition, thereby achieving the wider angle and the thickness decrease while maintaining high optical performance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a collapsible zoom lens capable of high zooming, which is suitable for being mounted on a small imaging device such as a digital still camera or a home video camera.

  In recent years, there has been a demand for further miniaturization in small imaging devices such as digital still cameras and home video cameras. In order to meet this demand, a reduction in the thickness of a photographing lens mounted on a small imaging device is promoted. In particular, with regard to a photographic lens mounted on a digital still camera, a reduction in thickness and a wide angle and improvement in lens performance are attempted so as to cope with an increase in the number of pixels of an image sensor (for example, Patent Documents 1 to 5) reference.).

JP 2005-338740 A JP 2006-23530 A JP 2006-23531 A JP 2006-171055 A JP 2006-308649 A

  In order to reduce the thickness of a photographic lens, particularly when the zoom lens is retracted (the zoom lens is in its most contracted state: the state of the zoom lens when the power of the device main body is turned off when mounted on the imaging device) And the minimum air gap between the first lens group and the second lens group and between the second lens group and the third lens group is reduced. Is required. In order to meet this demand, conventional zoom lenses including the techniques disclosed in each of the above-mentioned patent documents cope with this by reducing the vertical magnification of the air gap in the third lens group with respect to the image plane. However, such a method has a problem that it is difficult to achieve a wide angle even if the zoom lens can be thinned.

  In order to reduce the thickness of the zoom lens, it is also effective to use a method in which a part of an optical member constituting the zoom lens is compared outside the optical axis when retracted. However, when an optical image stabilization function or the like is incorporated in the zoom lens, it is difficult to achieve a wide angle even if the thickness can be reduced.

  In order to solve the above-described problems caused by the prior art, the present invention is a collapsible that can achieve both wide angle and thinning while maintaining high optical performance even when an optical image stabilization function is incorporated. An object is to provide a zoom lens.

In order to solve the above-described problems and achieve the object, a retractable zoom lens according to the first aspect of the present invention includes, in order from the object side, a first lens group having a positive refractive power and a second lens group having a negative refractive power. A retractable zoom lens comprising a lens group, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power, wherein the first lens group to the first lens group are arranged. The thicknesses of the four lens groups on the optical axis are LT 1 , LT 2 , LT 3 and LT 4 , respectively, and the air spacing on the optical axis between the first lens group and the second lens group at the wide angle end is AT. 12W , when the air space on the optical axis between the second lens group and the third lens group at the telephoto end is AT 23T and the imaging circle diameter for the maximum incident light beam is DIMG MAX , It is characterized by satisfaction.
(LT 1 + LT 2 + LT 3 + LT 4 + AT 12W + AT 23T ) / DIMG MAX ≦ 2.5

  According to the first aspect of the present invention, the thickness on the optical axis when the retractable zoom lens is retracted can be reduced, and the reduction of the thickness of the retractable zoom lens when retracted is promoted.

A retractable zoom lens according to a second aspect of the present invention is the retractable zoom lens according to the first aspect of the present invention, wherein the amount of movement of the second lens group on the optical axis in zooming from the wide-angle end to the telephoto end is set to MO 2 . When the focal lengths at the wide-angle end and the telephoto end of the entire system at an infinite distance are f W and f T , respectively, the following conditional expressions are satisfied.
| MO 2 | / (f T / f W ) ≦ 0.5

  According to the second aspect of the present invention, it is possible to reduce the thickness of the retractable zoom lens while maintaining a balance between the length of the entire system at the wide-angle end of the retractable zoom lens and the length of the entire system at the telephoto end.

A retractable zoom lens according to a third aspect of the present invention is the retractable zoom lens according to the first or second aspect, wherein the air space on the optical axis between the second lens group and the third lens group at the wide-angle end is set. AT 23W is characterized in that the following conditional expression is satisfied, where AT 23T is an air interval on the optical axis between the second lens group and the third lens group at the telephoto end.
AT 23T / AT 23W ≦ 0.04

  According to the third aspect of the present invention, the air space on the optical axis between the second lens group and the third lens group is reduced, and the reduction in thickness of the retractable zoom lens is further promoted.

  According to the present invention, it is possible to provide a high zoom ratio retractable zoom lens capable of achieving both wide angle and thinning while maintaining high optical performance even when an optical image stabilization function is incorporated. There is an effect that can be. By satisfying predetermined conditions, the retractable zoom lens achieves a reduction in thickness and angle of view, and enables favorable aberration correction.

  Hereinafter, preferred embodiments of the retractable zoom lens according to the present invention will be described in detail.

  The retractable zoom lens according to this embodiment includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. And a fourth lens group having a positive refractive power are arranged. The retractable zoom lens performs zooming by moving the first to fourth lens groups independently along the optical axis. Further, focusing is performed by moving the fourth lens group along the optical axis.

  An object of the present invention is to provide a zoom lens having a high zoom ratio capable of achieving both wide angle and thinning while maintaining high optical performance even when an optical image stabilization function is incorporated. It is said. Therefore, in order to achieve such an object, the following conditions are set in addition to the above-described configuration.

First, the thicknesses on the optical axis of the first lens group to the fourth lens group constituting the retractable zoom lens of this embodiment are set to LT 1 , LT 2 , LT 3 , LT 4 , and the thicknesses at the wide angle end, respectively. The air gap on the optical axis between one lens group and the second lens group is AT 12W , and the air gap on the optical axis between the second lens group and the third lens group at the telephoto end is AT 23T. When the imaging circle diameter with respect to the maximum incident light beam is DIMG MAX , it is preferable that the following conditional expression is satisfied.
(1) (LT 1 + LT 2 + LT 3 + LT 4 + AT 12W + AT 23T ) / DIMG MAX ≦ 2.5

Conditional expression (1) is an expression showing a condition for reducing the thickness on the optical axis when the retractable zoom lens according to this embodiment is retracted. By satisfying conditional expression (1), it is possible to achieve a reduction in thickness when retracted. In this conditional expression (1), if any one of LT 1 , LT 2 , LT 3 , LT 4 , AT 12W , AT 23T increases and exceeds the upper limit of the conditional expression, The upper thickness increases, and a sufficient thickness reduction cannot be achieved.

Further, in the retractable zoom lens according to this embodiment, the movement amount on the optical axis of the second lens group in zooming from the wide-angle end to the telephoto end is MO 2 , and the wide-angle end of the entire system with the subject distance at infinity. When the focal lengths at the telephoto end are f W and f T , respectively, it is preferable that the following conditional expressions are satisfied.
(2) | MO 2 | / (f T / f W ) ≦ 0.5

  Conditional expression (2) is an expression showing a condition for maintaining a balance between the length of the entire system at the wide-angle end and the length of the entire system at the telephoto end of the retractable zoom lens according to this embodiment. By satisfying conditional expression (2), it is possible to reduce the thickness of the retractable zoom lens while maintaining a balance between the length of the entire system at the wide-angle end and the length of the entire system at the telephoto end. If the upper limit of conditional expression (2) is exceeded, the balance between the total length at the wide-angle end and the total length at the telephoto end of the retractable zoom lens is lost, making it difficult to reduce the thickness.

For example, the value of | MO 2 | increases as the position of the second lens group at the wide-angle end moves to the object side more than the position at the telephoto end, and exceeds the upper limit of conditional expression (2). Although the length of the entire system at the telephoto end is shortened, the length of the entire system at the wide-angle end is increased, which hinders thinning. On the other hand, the value of | MO 2 | increases as the position of the second lens group at the telephoto end moves farther toward the object side than the position at the wide-angle end, and exceeds the upper limit of conditional expression (2). Although the length of the entire system at the wide-angle end is reduced, the length of the entire system at the telephoto end is increased, which hinders thinning and is not preferable.

Furthermore, in the retractable zoom lens according to this embodiment, the air interval on the optical axis between the second lens group and the third lens group at the wide-angle end is AT 23W , and the second lens group at the telephoto end is When the air space on the optical axis between the third lens group is AT 23T , it is preferable that the following conditional expression is satisfied.
(3) AT 23T / AT 23W ≦ 0.04

  Conditional expression (3) is an expression for defining an air space on the optical axis between the second lens group and the third lens group. Satisfying the conditional expression (3) promotes the thinning of the retractable zoom lens. If the upper limit of conditional expression (3) is exceeded, the air space on the optical axis between the second lens group and the third lens group constituting the retractable zoom lens increases, and the reduction in thickness is impeded. Therefore, it is not preferable.

  Embodiments of the retractable zoom lens according to the present invention will be described below.

FIG. 1 is a cross-sectional view along the optical axis showing the configuration of a retractable zoom lens according to an embodiment of the present invention. The retractable zoom lens includes a first lens group GR 1 having a positive refractive power, a second lens group GR 2 having a negative refractive power, and a third lens group GR having a positive refractive power in order from the object side (not shown). 3 and a fourth lens group GR 4 having a positive refractive power are arranged. Note that a filter FT formed of an infrared cut filter, a low-pass filter, and the like, and a cover glass CG of the image sensor are disposed between the fourth lens group GR 4 and the image plane IMG. These filters FT and cover glass CG are arranged as necessary, and can be omitted if unnecessary. In addition, a light receiving surface of an image sensor such as a CCD or a CMOS is disposed on the image plane IMG.

The first lens group GR 1 includes a negative lens L 1 and a positive lens L 2 arranged in order from the object side. The negative lens L 1 and the positive lens L 2 are cemented.

The second lens group GR 2 includes a negative lens L 3 , a negative lens L 4 , and a positive lens L 5 arranged in order from the object side. Further, the both surfaces of the positive lens L 5 are aspheric formed.

The third lens group GR 3 includes a positive lens L 6 , a positive lens L 7 , and a negative lens L 8 arranged in order from the object side. The positive lens L 7 and the negative lens L 8 are cemented. Further, aspheric surfaces are formed on both surfaces of the positive lens L 6 . Further, a diaphragm IR is provided on the surface of the positive lens L 6 on the image plane IMG side.

The fourth lens group GR 4 includes a positive lens L 9 . The both surfaces of the positive lens L 9 aspheric surface is formed.

This collapsible zoom lens performs zooming by moving the first lens group GR 1 , the second lens group GR 2 , the third lens group GR 3 , and the fourth lens group GR 4 independently along the optical axis. Do. This retractable zoom lens is designed to be in a retracted state when mounted on an imaging device by setting the air spacing between the lens groups to the minimum spacing during zooming or less when the device is turned off. Is done. Further, focusing is performed by moving the fourth lens group GR 4 along the optical axis.

In this embodiment, an example is shown in which aspheric surfaces are formed on both surfaces of the positive lens L 5 constituting the second lens group GR 2 , but depending on the required angle of view and zoom ratio, the aspheric surface is not necessarily formed. do not have to. Further, although the negative lens L 3 and the negative lens L 4 are composed of spherical lenses, it is effective to use an aspherical lens when further higher zooming or wider angle is required.

  Various numerical data relating to the retractable zoom lens according to this example will be described below.

Focal length at wide-angle end (f W ) = 5.14 mm
Focal length at intermediate position (f) = 11.29mm
Focal length at the telephoto end (f T ) = 24.73mm
F number (Fno.) = 3.30 (wide-angle end) to 4.08 (intermediate position) to 5.37 (telephoto end)
Half angle of view (ω) = 38.7 ° (wide-angle end) to 18.5 ° (intermediate position) to 8.72 ° (telephoto end)

(Numerical values related to conditional expression (1))
(LT 1 + LT 2 + LT 3 + LT 4 + AT 12W + AT 23T ) / DIMG MAX = 1.926

(Numerical value related to conditional expression (2))
| MO 2 | / (f T / f W ) = 0.186

(Numerical value for conditional expression (3))
AT 23T / AT 23W = 0.026

r 1 = 25.214 d 1 = 0.750 n d1 = 1.93323 ν d1 = 20.7
r 2 = 17.558 d 2 = 2.431 n d2 = 1.80831 ν d2 = 46.3
r 3 = 197.551 d 3 = 0.400 (wide-angle end) to 7.161 (intermediate position) to 13.871 (telephoto end)
r 4 = 44.756 d 4 = 0.500 n d3 = 1.80831 ν d3 = 46.3
r 5 = 6.095 d 5 = 2.063
r 6 = 87.125 d 6 = 0.500 n d4 = 1.88815 ν d4 = 40.6
r 7 = 7.335 d 7 = 0.723
r 8 = 9.758 (aspherical surface) d 8 = 2.417 n d5 = 1.82918 ν d5 = 23.9
r 9 = 5.052 × 10 5 (aspherical surface) d 9 = 11.387 (wide-angle end) to 3.932 (intermediate position) to 0.300 (telephoto end)
r 10 = 4.908 (aspherical surface) d 10 = 1.321 n d6 = 1.69661 ν d6 = 53.0
r 11 = -17.101 (aspherical surface) d 11 = 0.150
r 12 = 4.086 d 12 = 1.091 n d7 = 1.49845 ν d7 = 81.2
r 13 = 28.986 d 13 = 0.400 n d8 = 1.91048 ν d8 = 31.1
r 14 = 2.942 d 14 = 4.777 (wide-angle end) to 6.059 (intermediate position) to 12.100 (telephoto end)
r 15 = 12.855 (aspherical surface) d 15 = 1.706 n d9 = 1.59412 ν d9 = 66.8
r 16 = -38.524 (aspherical surface) d 16 = 2.187 (wide angle end) to 4.442 (intermediate position) to 5.057 (telephoto end)
r 17 = ∞ d 17 = 0.330 n d10 = 1.51872 ν d10 = 64.0
r 18 = ∞ d 18 = 0.690
r 19 = ∞ d 19 = 0.500 n d11 = 1.51872 ν d11 = 64.0
r 20 = ∞ d 20 = 0.600
r 21 = ∞ (image plane)

Conic constant (Κ) and aspheric coefficients (A, B, C, D)
(8th page)
Κ = 5.18670 × 10 -2 ,
A = -8.52936 × 10 -5 , B = -1.58620 × 10 -5 ,
C = 1.18099 × 10 −6 , D = −2.61136 × 10 −8
(9th page)
Κ = 0,
A = -2.62703 × 10 −4 , B = -1.42954 × 10 −5 ,
C = 1.16250 × 10 −6 , D = −3.224788 × 10 −8
(Tenth aspect)
Κ = 0,
A = -7.60897 × 10 -4 , B = -2.24476 × 10 -4 ,
C = 4.92808 × 10 -5 , D = -6.95411 × 10 -6
(11th page)
Κ = 0,
A = 5.82435 × 10 −4 , B = −3.41641 × 10 −4 ,
C = 8.54948 × 10 −5 , D = -1.09402 × 10 −5
(15th page)
Κ = 0,
A = -3.81066 × 10 -4 , B = 7.08912 × 10 -5 ,
C = -5.38903 × 10 −6 , D = 1.36319 × 10 −7
(16th surface)
Κ = 0,
A = -3.28899 × 10 −4 , B = 7.80046 × 10 −5 ,
C = -5.93756 × 10 −6 , D = 1.47937 × 10 −7

In the above numerical data, r 1 , r 2 ,... Are the radii of curvature of the lenses and the diaphragm surface, and d 1 , d 2 ,. Or the distance between the surfaces, n d1 , n d2 ,... Is the refractive index of the d-line of each lens or optical filter, and ν d1 , ν d2 ,. Shows the Abbe number.

  Each of the aspheric shapes is represented by the following formula, where Z is the sag amount of the surface parallel to the optical axis, h is the height from the optical axis, and the light traveling direction is positive.

  Here, c is the curvature at the surface vertex (= 1 / r), Κ is the conic constant, and A, B, C, and D are the fourth, sixth, eighth, and tenth aspherical coefficients, respectively.

  FIG. 2 is a diagram showing various aberrations at the wide-angle end of the retractable zoom lens according to the example of the present invention. FIG. 3 is a diagram of various aberrations at the intermediate position of the retractable zoom lens according to the embodiment of the present invention. FIG. 4 is a diagram of various aberrations at the telephoto end of the retractable zoom lens according to the example of the present invention.

  As described above, according to the present invention, even when an optical image stabilization function or the like is incorporated, high zoom ratio (5) capable of achieving both wide angle and thinning while maintaining high optical performance. A retractable zoom lens of approximately twice the magnification). In particular, this retractable zoom lens achieves a reduction in thickness (especially when retracted) and widening of the angle by satisfying predetermined conditions, and enables favorable aberration correction.

  In addition, since the retractable zoom lens according to the present invention includes a lens having an aspherical surface, various aberrations can be favorably corrected with a small number of lenses.

  As described above, the retractable zoom lens according to the present invention is useful for an imaging apparatus, and is particularly suitable for an imaging apparatus that is required to be downsized, such as a digital still camera and a home video camera.

It is sectional drawing which follows the optical axis which shows the structure of the retractable zoom lens concerning the Example of this invention. FIG. 6 is a diagram illustrating all aberrations at the wide-angle end of the retractable zoom lens according to the example of the present invention. FIG. 6 is a diagram illustrating various aberrations at an intermediate position of the retractable zoom lens according to the example of the present invention. FIG. 6 is a diagram illustrating all aberrations at the telephoto end of the retractable zoom lens according to the example of the present invention.

Explanation of symbols

GR 1 first lens group GR 2 second lens group GR 3 third lens group GR 4 fourth lens group L 1 , L 3 , L 4 , L 8 negative lenses L 2 , L 5 , L 6 , L 7 , L 9 Positive lens IMG Image plane IR Aperture FT Filter CG Cover glass S Spherical image plane (Sagittal image plane)
T Meridian image plane (tangential image plane)

Claims (3)

  1. In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a positive refractive power A retractable zoom lens comprising a group,
    The thicknesses of the first lens group to the fourth lens group on the optical axis are LT 1 , LT 2 , LT 3 , LT 4 , respectively, between the first lens group and the second lens group at the wide angle end. The air spacing on the optical axis is AT 12W , the air spacing on the optical axis between the second lens group and the third lens group at the telephoto end is AT 23T , and the imaging circle diameter for the maximum incident light beam is DIMG MAX A retractable zoom lens characterized by satisfying the following conditional expression:
    (LT 1 + LT 2 + LT 3 + LT 4 + AT 12W + AT 23T ) / DIMG MAX ≦ 2.5
  2. The amount of movement of the second lens group on the optical axis in zooming from the wide-angle end to the telephoto end is MO 2 , and the focal lengths at the wide-angle end and the telephoto end of the entire system when the object distance is infinity are f W and f The retractable zoom lens according to claim 1, wherein when T , the following conditional expression is satisfied.
    | MO 2 | / (f T / f W ) ≦ 0.5
  3. The air space on the optical axis between the second lens group and the third lens group at the wide-angle end is defined as AT 23W , and on the optical axis between the second lens group and the third lens group at the telephoto end. The retractable zoom lens according to claim 1 or 2, wherein the following conditional expression is satisfied when the air interval is AT 23T .
    AT 23T / AT 23W ≦ 0.04
JP2008040153A 2008-02-21 2008-02-21 Collapsible zoom lens Pending JP2009198800A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2008040153A JP2009198800A (en) 2008-02-21 2008-02-21 Collapsible zoom lens

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2008040153A JP2009198800A (en) 2008-02-21 2008-02-21 Collapsible zoom lens
CN 200910006469 CN101515057B (en) 2008-02-21 2009-02-18 Retractable zoom lens
US12/389,560 US7848029B2 (en) 2008-02-21 2009-02-20 Retractable zoom lens

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61260210A (en) * 1985-05-15 1986-11-18 Olympus Optical Co Ltd Zoom lens
JPS63116113A (en) * 1986-11-05 1988-05-20 Nikon Corp Telephoto zoom lens
JP2001117005A (en) * 1999-10-18 2001-04-27 Sigma Corp High variable power zoom lens
JP2001154093A (en) * 1999-11-24 2001-06-08 Olympus Optical Co Ltd Small-sized high variable power wide-angle zoom lens
WO2006025130A1 (en) * 2004-09-02 2006-03-09 Tamron Co., Ltd. Zoom lens with high zoom ratio
JP2007240747A (en) * 2006-03-07 2007-09-20 Olympus Imaging Corp Zoom lens and imaging device using the same

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61260210A (en) * 1985-05-15 1986-11-18 Olympus Optical Co Ltd Zoom lens
JPS63116113A (en) * 1986-11-05 1988-05-20 Nikon Corp Telephoto zoom lens
JP2001117005A (en) * 1999-10-18 2001-04-27 Sigma Corp High variable power zoom lens
JP2001154093A (en) * 1999-11-24 2001-06-08 Olympus Optical Co Ltd Small-sized high variable power wide-angle zoom lens
WO2006025130A1 (en) * 2004-09-02 2006-03-09 Tamron Co., Ltd. Zoom lens with high zoom ratio
JP2007240747A (en) * 2006-03-07 2007-09-20 Olympus Imaging Corp Zoom lens and imaging device using the same

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