KR20050037701A - Optical imaging system for inch electronic sensor - Google Patents

Abstract

 The present invention relates to a short focus lens for imaging optics applied to a camera using a 1 / 4-inch electronic sensor as an imaging device.

The present invention provides a lens of a convex lens having positive refractive power having a positive refractive power from a subject, a two lens of a Plano Concave type having a negative refractive power, and a concave meniscus having a positive refractive power. It consists of three lenses, four lenses in the form of convex meniscus with negative refractive power, and five lenses in the form of a planar (electronic sensor protective glass), which satisfy the following equation as an optical system for forming an image: It is done.

3.8 <EFL <4.2

3.99 <EFL ／ BFL <18.88

EFL ₃  > EFL _One  > 0> EFL ₂  > EFL ₄

1.52 <n _One  = n ₃ = n ₄ = <1.55

n ₂  > 1.8

55 <v _One  = v ₃  = v ₄  <56

v ₂ <24

EFL: Focal Length

BFL: Post Focal Length

EFL _N : Focal length of N lens

n ₁ , n ₂ , n ₃ , n ₄ : refractive index of the first, _second , _third and _fourth lens components

v ₁ , v ₂ , v ₁ , v4: dispersion coefficients of the _first , _second , _third and fourth lens components

As a result, the short focus lens according to the present invention can realize an economical optical system having an image quality of megapixel class (300,000 pixels, 1,280 x 1,024).

Description

Optical Imaging System for Inch Electronic Sensor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging optical system for 1 / 4-inch electronic sensors, and more particularly, to a short focus lens for imaging optics applied to a camera mounted on a mobile phone or the like. Most imaging systems to date include three aspherical plastic lenses in order of positive refractive power (+), negative refractive power (-), positive refractive power (+), negative refractive power (-), plane infrared cut filter, electronic sensor protective glass, Six lenses consisting of one aspherical glass lens and two planar glass lenses are arranged, and many companies are using them because they can obtain a high quality of megapixel class (1.3 million pixels, 1,280 x 1,024). However, simply arranging a few lenses with a combination of refractive powers of (+) and (-) does not provide the best image quality. The combination of parameters such as material selection and shape design of each lens produces a satisfactory image on the top surface. You can get it. In addition, good quality can be achieved as aimed, but too much quality can reduce the economics of production.

Accordingly, the present invention is to overcome the above-mentioned conventional problems, and an object of the present invention is to define four lenses in order of positive refractive power (+), negative refractive power (-), positive refractive power (+), and negative refractive power (-). This is an imaging optical system for 1 / 4-inch electronic sensors arranged in the form of a lens. It is to provide a single focus lens designed to be obtained.

As an example of a single-focal lens for achieving the object of the present invention, one lens of the convex lens shape having positive refractive power with positive refractive power from the subject, two lenses of the plano concave shape with negative refractive power, positive It consists of three lenses in the form of concave meniscus with refractive power, four lenses in the form of convex meniscus with negative refractive power and five lenses in the form of a plane (electronic sensor protective glass). The optical system to be formed is characterized by satisfying the following formula simultaneously.

3.8 <EFL <4.2

3.99 <EFL ／ BFL <18.88

EFL ₃  > EFL _One  > 0> EFL ₂  > EFL ₄

 1.52 <n _One  = n ₃ = n ₄ = <1.55

n ₂  > 1.8

55 <v _One  = v ₃  = v ₄  <56

v ₂ <24

EFL: Focal Length

BFL: Post Focal Length

EFL _N : Focal length of N lens

n ₁ , n ₂ , n ₃ , n ₄ : refractive index of the first, _second , _third and _fourth lens components

v ₁ , v ₂ , v ₁ , v4: dispersion coefficients of the _first , _second , _third and fourth lens components

By such a configuration, the short focus lens according to the present invention can realize an economical optical system having an image quality of megapixel class (1.3 million pixels, 1,280 x 1,024).

Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2.

This embodiment illustrates an imaging system mounted on a mobile phone.

In this embodiment, five lenses (L1, L2, L3, L4, L5) are formed of a convex lens having positive refractive power from a subject, and two lenses of a plano concave shape having negative refractive power. Consists of three lenses in the form of concave meniscus with refractive power, four lenses in the form of convex meniscus with negative refractive power, and a flat (electronic sensor protective glass) lens at the rear. It is an imaging optical system for the 4 inch electronic sensor. The material of the lens is to provide a short focal lens designed through a combination of variables such as simplification of material selection and shape design while minimizing chromatic aberration.

Specifications of the optical system according to the present embodiment are shown in Table 1 below.

lens Bending Radius (R) Face spacing (d) Refractive index (Nd) Dispersion coefficient Remarks L1 R1: 3.857 d1: 0.84 1.529962 55.867805 Aspheric surface R2: -1.795 d2: 0.18 AIR AIR Aspheric surface L2 R3: -3.333 d3: 0.46 1.846664 23.784397 Aspheric surface R4: Plane d4: 0.80 AIR AIR L3 R5: -1.145 d5: 0..84 1.529962 55.867805 Aspheric surface R6: -1.003 d6: 0.09 AIR AIR Aspheric surface L4 R7: 1.438 d7: 0.61 1.529962 55.867805 Aspheric surface R8: 0.928 d8: 1.40 AIR AIR Aspheric surface L5 R9: Plane d9: 0.5 1.5168 64.166410 R10: Plane - AIR AIR

As described above, the short throw lens according to the present invention can realize an economical optical system having an image quality of megapixel class (1.3 million pixels, 1,280 x 1,024).

What has been described above is only one embodiment for implementing a single focal length lens according to the present invention, and the present invention is not limited to the above-described embodiment, and the scope of the present invention as claimed in the following claims Without departing from the scope of the present invention, those of ordinary skill in the art can make various modifications.

1 is a block diagram showing a short focus lens according to a first embodiment of the present invention

2 is a numerical performance analysis table of a single focal lens according to the first embodiment of the present invention;

Claims (2)

1 lens of the convex lens type having positive refractive power with positive refractive power from the subject, 2 lenses of the Plano Concave type having negative refractive power, 3 lenses of the concave meniscus type with positive refractive power, An optical system comprising four lenses in the form of convex meniscus with negative refractive power and five lenses in the form of a planar glass (electronic sensor protection glass), which satisfy the following formula at the same time. 3.8 <EFL <4.2 3.99 <EFL ／ BFL <18.88 EFL ₃  > EFL _One  > 0> EFL ₂  > EFL ₄ 1.52 <n _One  = n ₃ = n ₄ = <1.55 n ₂  > 1.8 55 <v _One  = v ₃  = v ₄  <56 v ₂ <24 EFL: Focal Length BFL: Post Focal Length EFL _N : Focal length of N lens n ₁ , n ₂ , n ₃ , n ₄ : refractive index of the first, _second , _third and _fourth lens components v ₁ , v ₂ , v ₁ , v4: dispersion coefficients of the _first , _second , _third and fourth lens components The method of claim 1, The second surface of said two lenses (L2) is made into a plane, and that surface acts as an infrared cut filter, The short focus optical system characterized by the above-mentioned.