KR100452388B1 - Slim lens unit capable of compensating spherical aberration and coma aberration - Google Patents

Slim lens unit capable of compensating spherical aberration and coma aberration Download PDF

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KR100452388B1
KR100452388B1 KR1019970052567A KR19970052567A KR100452388B1 KR 100452388 B1 KR100452388 B1 KR 100452388B1 KR 1019970052567 A KR1019970052567 A KR 1019970052567A KR 19970052567 A KR19970052567 A KR 19970052567A KR 100452388 B1 KR100452388 B1 KR 100452388B1
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lens
refractive power
lens unit
aberration
spherical aberration
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KR1019970052567A
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Korean (ko)
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KR19990031735A (en
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여상옥
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엘지전자 주식회사
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
    • G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
    • G02B13/002—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface
    • G02B13/0035—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface having three lenses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
    • G02B1/041—Lenses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/18—Optical objectives specially designed for the purposes specified below with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B9/00—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or -
    • G02B9/12—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - having three components only
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B9/00—Exposure-making shutters; Diaphragms
    • G03B9/02—Diaphragms

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  • Optics & Photonics (AREA)
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Abstract

PURPOSE: A slim lens unit is provided to improve performance of the unit by compensating spherical aberration and coma aberration by using a non-spherical plastic lens. CONSTITUTION: A slim lens unit includes a first lens(10), a second lens(20), a diaphragm(30), and a third lens(40) implemented sequentially from an object side. The first lens has a negative refractive index. The second lens has a positive refractive index and includes convex portions at both ends thereof. The diaphragm adjusts an amount of light. The third lens has a positive refractive index and has a meniscus formation. The refractive indexes of the first and the third lens satisfy 0.8<abs(f1/fT) <0.9 and 3.2<abs(f3/fT)<3.4, where abs(a) means an absolute value of a, fT is a focal distance of the overall system, f1 is a focal distance of the first lens, and f3 is a focal distance of the third lens.

Description

초박형 렌즈 유니트Ultra Thin Lens Unit

본 발명은 디지털 스틸 카메라(Digital Still Camera : DSC), 컴퓨터용 카메라(Personal Computer Camera : PCC), 개인용 휴대정보 단말기(Personal Digital Assistant : PDA) 등의 멀티미디어용 기기에 사용되는 초박형 렌즈 유니트(slim lens unit )에 관한 것으로서 특히, 렌즈 매수를 줄여 염가형으로 구성할 수 있는 초박형 렌즈 유니트에 관한 것이다.The present invention is an ultra-thin lens unit (slim lens) used for multimedia devices such as a digital still camera (DSC), a personal computer camera (PCC), a personal digital assistant (PDA), and the like. unit), and particularly relates to an ultra-thin lens unit that can be configured inexpensively by reducing the number of lenses.

최근 멀티미디어 제품에서 화상 압축 및 복원 기술의 향상에 따라 멀티미디어 제품에 사용할 수 있도록 초박형 렌즈 유니트를 채용한 카메라 제품이 계속적으로 출시되고 있다. 이때, 상기 초박형 렌즈 유니트는 그 성능을 유지하면서 소형화시킬 수 있도록 하기 위하여 다수의 렌즈를 이용하여 구성하고 있다.Recently, with the improvement of image compression and reconstruction technology in multimedia products, camera products employing ultra-thin lens units for use in multimedia products have been continuously released. At this time, the ultra-thin lens unit is configured using a plurality of lenses in order to be miniaturized while maintaining the performance.

종래 기술에 의한 초박형 렌즈 유니트의 구성은 도 1에 도시된 바와 같이 4매의 렌즈로 이루어지는데, 음(-)의 굴절력을 가진 제1 렌즈(1)와, 양(+)의 굴절력을 가지고 양볼록 형태로 이루어지는 제2 렌즈(2)와, 양(+)의 굴절력을 가진 제3 렌즈(3) 및 음(-)의 굴절력을 가진 제4 렌즈(4)로 이루어지는 이중렌즈가 물체측으로부터 순차적으로 배치되어 이루어진다.The structure of the ultra-thin lens unit according to the prior art is composed of four lenses, as shown in FIG. 1, which has a first lens 1 having a negative refractive power and a positive refractive power. A dual lens composed of a convex second lens 2, a third lens 3 having positive (+) refractive power and a fourth lens 4 having a negative (-) refractive power is sequentially formed from the object side. It is arranged to be made.

이때, 성능유지를 위한 색수차 보정용으로서 하나 이상의 이중렌즈(doublet)가 필요하다.In this case, at least one doublet is required for chromatic aberration correction to maintain performance.

따라서, 상기와 같은 렌즈 구성으로 인하여 카메라를 박형화하는데 한계가 있으며, 카메라 내부에 아이리스(iris)를 장착하는 것이 불가능하여 밝은 대낮이나 옥외 촬영시 과다 노출로 인하여 스미어 현상이 발생되기 때문에 사용영역의 제한을 받게 되는 문제점이 있다.Therefore, there is a limitation in thinning the camera due to the lens configuration as described above, and since it is impossible to mount an iris inside the camera, a smear phenomenon occurs due to overexposure during bright daylight or outdoor shooting. There is a problem to receive.

본 발명은 상기와 같은 문제점을 해결하기 위하여 안출된 것으로서, 그 목적은 렌즈군 사이에 조리개를 설치하여 렌즈 매수를 줄일 수 있도록 함으로써 카메라를 소형화 할 수 있는 초박형 렌즈 유니트를 제공하는데 있다.The present invention has been made to solve the above problems, an object of the present invention is to provide an ultra-thin lens unit that can be miniaturized by installing a diaphragm between the lens group to reduce the number of lenses.

본 발명의 다른 목적은 비구면 플라스틱 렌즈를 사용하여 코마(coma) 수차 및 구면 수차를 보정함으로써 성능을 향상시킬 수 있는 초박형 렌즈 유니트를 제공하는데 있다.Another object of the present invention is to provide an ultra-thin lens unit that can improve performance by correcting coma and spherical aberration using an aspherical plastic lens.

도 1은 종래 기술에 의한 초박형 렌즈 유니트의 구성을 나타내는 도면,1 is a view showing the configuration of an ultra-thin lens unit according to the prior art,

도 2는 본 발명의 의한 초박형 렌즈 유니트의 구성을 나타내는 도면.2 is a view showing the configuration of an ultra-thin lens unit of the present invention.

< 도면의 주요 부분에 대한 부호의 설명 ><Description of Symbols for Main Parts of Drawings>

10 : 제1 렌즈 20 : 제2 렌즈10: first lens 20: second lens

30 : 조리개 40 : 제3 렌즈30: aperture 40: third lens

상기와 같은 목적을 달성하기 위한 본 발명의 특징에 따르면, 음(-)의 굴절력을 가진 제1 렌즈와, 양(+)의 굴절력을 가지고 양볼록 형태로 이루어지는 제2 렌즈와, 광량의 조절을 위한 조리개와, 양(+)의 굴절력을 가지고 오목볼록(meniscus) 형태로 이루어지는 제3 렌즈가 물체측으로부터 순차적으로 배치되어 이루어지며, 상기 제1 렌즈 및 제3 렌즈의 굴절력은 0.8 < ｜ fⅠ/fT ｜ < 0.9 , 3.2 < fⅢ/fT < 3.4 의 식을 만족한다. 이때, fT 는 전계의 초점거리, fⅠ 는 제1 렌즈의 초점거리, fⅢ 는 제3 렌즈의 초점거리를 나타낸다.According to a feature of the present invention for achieving the above object, the first lens having a negative (-) refractive power, the second lens having a positive (+) refractive power and formed in a positive convex form, and adjusting the amount of light And a third lens having positive (+) refractive power and formed in a convex shape (meniscus) in order from the object side, and the refractive power of the first lens and the third lens is 0.8 <| fI / fT | <0.9, 3.2 <fIII / fT <3.4 In this case, fT is the focal length of the electric field, fI is the focal length of the first lens, and fIII is the focal length of the third lens.

또한, 본 발명의 부가적인 특징에 따르면, 상기 제2 렌즈 및 제3 렌즈는 비구면 플라스틱 렌즈로 이루어진다.In addition, according to an additional feature of the invention, the second lens and the third lens are made of aspherical plastic lenses.

이하, 본 발명의 바람직한 실시예를 첨부한 도면을 참조하여 상세히 설명하면 다음과 같다.Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.

도 2는 본 발명에 의한 초박형 렌즈 유니트의 구성을 나타내는 도면이다.2 is a view showing the configuration of an ultra-thin lens unit according to the present invention.

도 2를 참조하면, 본 발명은 음(-)의 굴절력을 가진 제1 렌즈(10)와, 양(+)의 굴절력을 가지고 양볼록 형태로 이루어지는 제2 렌즈(20)와, 광량의 조절을 위한 조리개(30)와, 양(+)의 굴절력을 가지고 오목볼록(meniscus) 형태로 이루어지는 제3 렌즈(40)가 물체측으로부터 순차적으로 배치되어 이루어진다.Referring to FIG. 2, the present invention controls the first lens 10 having a negative refractive power, the second lens 20 having a positive refractive power, and having a positive convex shape, and adjusting the amount of light. The aperture 30 and the third lens 40 having a positive refractive power and formed in a convex shape (meniscus) are sequentially arranged from the object side.

이때, 상기의 구성은 수차의 균형을 위하여 4면 이상의 비구면을 갖으며, 상기 제2 렌즈(20) 및 제3 렌즈(40)는 비구면 플라스틱 렌즈로 이루어지고, 상기 제1 렌즈(10) 및 제3 렌즈(40)의 굴절력은 하기의 식을 만족한다.In this case, the above configuration has an aspherical surface having four or more surfaces for balance of aberration, and the second lens 20 and the third lens 40 are made of aspherical plastic lenses, and the first lens 10 and the first lens The refractive power of the three lenses 40 satisfies the following equation.

Figure 1019970052567_B1_M0001
Figure 1019970052567_B1_M0001

Figure 1019970052567_B1_M0002
Figure 1019970052567_B1_M0002

이때, fT는 전계의 초점거리, fⅠ는 제1 렌즈의 초점거리, fⅢ는 제3 렌즈의 초점거리를 나타낸다.In this case, f T is the focal length of the electric field, f I is the focal length of the first lens, and f III is the focal length of the third lens.

상기의 수학식 1은 제1 렌즈(10)의 굴절력을 한정하는 것으로서, 하한치를 넘어 굴절력이 강해지면 렌즈 유니트의 소형화에 유리하나, 그에 따라 공차에 민감하여 렌즈 가공성이 떨어져 생산성이 저하되고 축상 색수차가 나빠지는 단점이 발생한다. 또한, 상한치를 넘어 굴절력이 약해지면 수차 보정에는 유리하나, 광학계 전장이 길어지고 제1 렌즈(10)의 유효경이 커져 소형화 및 경량화에 불리해지는 단점이 발생한다.Equation 1 above is to limit the refractive power of the first lens 10, if the refractive power is stronger beyond the lower limit, it is advantageous to the miniaturization of the lens unit, but it is sensitive to the tolerance, thereby reducing the lens workability, resulting in reduced productivity and axial chromatic aberration The disadvantage is that it gets worse. In addition, if the refractive power becomes weak beyond the upper limit, it is advantageous for aberration correction, but the optical system length becomes long and the effective diameter of the first lens 10 becomes large, which causes disadvantages in miniaturization and light weight.

한편, 상기의 수학식 2는 제3 렌즈(40)의 굴절력을 한정하는 것으로서, 하한치를 넘어 굴절력이 강해지면 구면수차 보정은 용이해지나 축상 색수차가 커지게 되어 광학적 성능이 저하되는 단점이 발생한다. 또한, 상한치를 넘어 굴절력이 약해지면 후초점거리가 길어지고 축상의 구면수차가 커지게 되어 상면 만곡이 커지게 되는 단점이 발생한다.On the other hand, Equation 2 above is to limit the refractive power of the third lens 40, when the refractive power is stronger than the lower limit, the spherical aberration correction becomes easy, but the axial chromatic aberration increases, there is a disadvantage that the optical performance is degraded. . In addition, when the refractive power becomes weak beyond the upper limit, the postfocal length becomes long and the spherical aberration increases on the axial, resulting in an increase in curvature of the upper surface.

결국, 카메라의 렌즈를 박형화하는 동시에 성능유지를 위한 색수차 보정을 위하여는 각 요소의 굴절력을 강하게 하여야 하며, 이때 발생하는 코마(coma) 수차 및 구면 수차는 비구면 플라스틱 렌즈를 사용하여 보정하여야 한다.As a result, in order to reduce the lens of the camera and simultaneously correct chromatic aberration for maintaining performance, the refractive power of each element must be strengthened, and coma and spherical aberration generated at this time must be corrected using an aspherical plastic lens.

이상에서 설명한 바와 같은 본 발명의 초박형 렌즈 유니트는 비구면 플라스틱 렌즈를 사용하기 때문에 코마(coma) 수차 및 구면 수차를 양호하게 보정할 수 있어서 광학적 성능을 향상시킬 수 있는 효과가 있다.As described above, since the ultra-thin lens unit of the present invention uses an aspherical plastic lens, coma aberration and spherical aberration can be well corrected, thereby improving optical performance.

또한, 렌즈군을 3매로 하여 종래 기술에 비하여 렌즈군을 줄일 수 있기 때문에 박형화에 유리하며, 카메라를 소형화할 수 있는 효과가 있다.In addition, since the lens group can be reduced by using three lens groups as compared with the prior art, it is advantageous for thinning, and the camera can be miniaturized.

Claims (2)

음(-)의 굴절력을 가진 제1 렌즈와, 양(+)의 굴절력을 가지고 양볼록 형태로 이루어지는 제2 렌즈와, 광량의 조절을 위한 조리개와, 양(+)의 굴절력을 가지고 오목볼록(meniscus) 형태로 이루어지는 제3 렌즈가 물체측으로부터 순차적으로 배치되어 이루어지는 초박형 렌즈 유니트에 있어서,A first lens having a negative refractive power, a second lens having a positive refractive power and having a positive convex shape, an aperture for controlling the amount of light, and a concave convex having a positive refractive power In the ultra-thin lens unit in which the third lens having a meniscus) shape is sequentially arranged from the object side, 상기 제1 렌즈 및 제3 렌즈의 굴절력은 하기의 식을 만족하는 것을 특징으로 하는 초박형 렌즈 유니트.The refractive power of the first lens and the third lens satisfy the following equation. 0.8 < ｜ fⅠ/fT｜ < 0.9 , 3.2 < fⅢ/fT< 3.40.8 <| f I / f T | <0.9, 3.2 <f III / f T <3.4 이때, fT는 전계의 초점거리, fⅠ는 제1 렌즈의 초점거리, fⅢ는 제3 렌즈의 초점거리를 나타낸다.In this case, f T is the focal length of the electric field, f I is the focal length of the first lens, and f III is the focal length of the third lens. 제 1 항에 있어서,The method of claim 1, 상기 제2 렌즈 및 제3 렌즈는 비구면 플라스틱 렌즈로 이루어지는 것을 특징으로 하는 초박형 렌즈 유니트.And the second lens and the third lens are made of aspherical plastic lenses.
KR1019970052567A 1997-10-14 1997-10-14 Slim lens unit capable of compensating spherical aberration and coma aberration KR100452388B1 (en)

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