JP2003270526A - Imaging optical system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide such an imaging optical system which can simultaneously image even an object point having a great difference in object distances to obtain images in the absence of moving parts. <P>SOLUTION: One or two surfaces of the lens surfaces in the imaging optical system L have curvatures r<SB>1</SB>and r<SB>1</SB>varying between an inner side region and outer side region coaxial with an optical axis. When the focal length of the entire system by the curvature of the outer side region is defined as f<SB>1</SB>, the focal length of the entire system by the curvature of the inner side region as f<SB>2</SB>, the area on the incident pupil surface of the axial luminous flux passing the outer side region as S<SB>1</SB>, and the area on the incident pupil surface of the axial luminous flux passing the inner side region as S<SB>2</SB>, the imaging optical system satisfies at least either of: 0.3≤f<SB>2</SB>/f<SB>1</SB>≤0.9...(1) and 0.5≤S<SB>1</SB>/S<SB>2</SB>≤11...(2). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup optical system, and more particularly, to a bifocal lens system capable of simultaneously picking up an image of an object point having a large difference in object point distance without a movable part.

[0002]

2. Description of the Related Art In an image pickup optical system, when images of two objects at different distances are imaged without a movable part, one means is to concentrically form a lens surface on an inner portion (a side closer to the optical axis) and an outer portion. A method is known in which two different focal lengths are provided by dividing into (far side from the optical axis) and different curvatures.

As a conventional example, for example, Japanese Patent Publication No. 7-119.
893 is mentioned. This relates to an endoscope optical system, and is intended to increase the depth of field by combining a multifocal lens and an auto iris mechanism. However, the difference between the focal lengths due to the plurality of focal points is small, and it is not possible to simultaneously image the object points with a large difference between the object point distances.

A multifocal lens is disclosed in Japanese Unexamined Patent Publication No.
-230114, Japanese Patent Laid-Open No. 2001-236686, etc., all of which have a small difference in focal length between a plurality of focal points.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional state of the art, and an object thereof is to provide a movable portion even in an object point having a large difference in object point distance in an imaging optical system. It is an object of the present invention to provide an optical system capable of simultaneously capturing images without using the optical system.

[0006]

According to a first imaging optical system of the present invention that achieves the above object, one or two lens surfaces in an imaging lens system have an inner region and an outer region which are coaxial with an optical axis. The region has a different curvature, and the focal length of the entire system due to the curvature of the outer region is f ₁ , and the focal length of the entire system due to the curvature of the inner region is f _2.
Then, 0.3 ≦ f ₂ / f ₁ ≦ 0.9 (1) is satisfied.

A second image pickup optical system of the present invention is an image pickup optical system in which one or two lens surfaces of an imaging lens system have different curvatures in an inner region and an outer region coaxial with an optical axis. , S ₁ is the area on the entrance pupil plane of the axial light flux passing through the outer region, and S ₁ is the area on the entrance pupil plane of the axial light flux passing through the inner region.
_When it is set to ₂ , 0.5 ≦ S ₁ / S ₂ ≦ 11 (2) is satisfied.

Hereinafter, the reason and function of the above-mentioned configuration in the present invention will be described.

FIG. 1 shows a schematic sectional view of an image pickup optical system according to the present invention. In this schematic diagram, an imaging optical system L according to the present invention is composed of a single lens having a first surface and a second surface, and the first surface has an inner region coaxial with an optical axis having a radius of curvature r _{1 ′} , The outer surface is composed of an outer region coaxial with the optical axis having a radius of curvature r ₁ , and the second surface has a common radius of curvature r ₂
In this case, the entrance pupil P is located in the vicinity of the first surface.

For example, an axial light beam B ₁ passing through the outer region of the image pickup optical system L from an infinite distance is focused on the center of the image plane I to form an image. On the other hand, the on-axis light flux B ₂ that exits from the center of the relatively close object O _N and passes through the inner region is focused and imaged on the center of the image plane I. On the other hand, the light ray F that emerges from infinity and is incident on the inner area becomes flare light without being imaged on the image plane I. Similarly, a light ray emitted from a relatively close object O _N and passing through the outer region does not form an image on the image plane I and becomes flare light.

At this time, the area on the plane P of the entrance pupil of the axial light beam B ₁ passing through the outer region is S ₁ , and the axial light beam B ₂ passing through the inner region is B _2.
The area on the P-plane of the entrance pupil of is S ₂ . The boundary between different radii of curvature r _{1 ′} and r _{1 on} the same lens surface is determined by the inner boundary of the axial light beam B ₁ passing through the outer region.

The focal length of the entire system in the outer area is f ₁ , and the focal length of the entire system in the inner area is f ₂ . At this time, it is desirable that 0.3 ≦ f ₂ / f ₁ ≦ 0.9 (1) is satisfied.

If this conditional expression (1) is satisfied, it becomes possible to simultaneously image object points having a large difference in object point distance on the same image plane I. If f ₂ / f ₁ is too small, F-number of imaging by the inner curvature decreases, becomes shallow depth of focus with it. In that case, when the object O _N relatively closer to the inner area is used for data reading or the like, the permissible amount for the variation of the object surface becomes small, which is disadvantageous. Therefore, the depth of focus can be secured by increasing the F number to some extent and making it dark so that 0.3 ≦ f ₂ / f ₁ . Furthermore, when used for data reading applications that are placed in a position close to a camera that captures an image of a landscape or the like, if the data reading is performed by the inner area for the above reason, the F number can be darkened, and thus the depth of focus can be increased. Can be secured.

Further, in the image pickup optical system of the present invention, a diaphragm is arranged in the image forming lens system, and it is desirable that a surface having different curvatures in the inner region and the outer region is close to the diaphragm position or the diaphragm. . This is because the farther the surface having different curvatures in the inner region and the outer region is from the stop, the off-axis rays due to the object points having different distances have different curvatures in the inner region and the outer region, respectively. Crossing each other with respect to the object point of (the part of the off-axis ray from the object point distance that is imaged on the image plane by the curvature part of the inner region passes through the curvature part of the outer region, and conversely, (Some of the off-axis rays from the object point distance that form an image on the image plane due to the curvature portion pass through the curvature portion of the inner region), so
This is because the amount of peripheral light due to the image-forming light at each object point decreases and the flare component increases.

When the area on the entrance pupil plane of the axial light flux passing through the outer region is S ₁ and the area on the entrance pupil plane of the axial light flux passing through the inner region is S ₂ , 0.5 ≦ S ₁ By satisfying / S ₂ ≦ 11 (2), it is possible to adjust the amount of the flare component due to the rays that do not contribute to the image formation by each object point.

For example, in the case of photographing images having different object distances for both the inner area and the outer area for camera use, it is desirable that the amounts of flare components be substantially the same at both object points. In that case, it is desirable that conditional expression (2) be satisfied near the lower limit. By doing so, the light amounts from both object points are incident at substantially the same ratio, and the flare amounts are also substantially the same ratio at both object points.

When the object to be imaged is used as a camera for the focal length of the outer region and for data reading at the focal length of the other region, when reading the data, the photographed image is not viewed as it is, but the image is not viewed as it is. Since processing such as processing is performed, it does not matter if the flare component is large to some extent. Therefore, in the case of such an application, it is desirable to determine the ratio of S ₁ / S ₂ of the conditional expression (2) according to the data processing capacity, while performing the data reading by the inner area portion, The upper limit of conditional expression (2) may be increased to about 11.

Further, when the camera is used in the outer area and the data is read in the inner area, by satisfying 5.5 ≦ S ₁ / S ₂ ≦ 11 (2-1), The flare component can be suppressed smaller in the camera image (image of the outer area),
A clear image can be captured.

The number of lenses of the image pickup optical system of the present invention is 1 in consideration of cost and ease of manufacture.
It is desirable to be composed of one lens.

It is also conceivable to use two lenses. By using two lenses, various aberrations can be easily taken. Furthermore, by using two surfaces having different curvatures in the inner region and the outer region, various aberrations, particularly images, can be obtained for both two different object points. It is possible to satisfactorily correct the surface curvature.

In the photographing optical system of the present invention, when the aperture stop is a fixed stop diameter in the outer region, the object O _{N is} relatively closer to the inner region while accompanied by flare light.
Can be imaged, and an image of a relatively distant object can be imaged in the outer region, but better performance can be obtained by making the aperture diameter variable. That is, it is desirable to arrange the diaphragm at a surface position having different curvatures in the inner region and the outer region or at a position close to it, and as the diaphragm, as shown in FIG. 2, a diaphragm having a variable shape is used. By inserting according to the point distance, when using the inner area, flare components due to light rays passing through the outer area, and when using outer area, removing flare components due to light rays passing through the inner area, It is possible to obtain good imaging performance. Figure 2 (a)
The diaphragm of FIG. 2 is a diaphragm that shields the inner area when the outer area is used, the diaphragm of FIG. 2B is a diaphragm that shields the outer area when the inner area is used, and FIG. The diaphragm is a diaphragm used when photographing an object at one object point position or an object at both object point positions through the entire aperture while allowing a flare component.

It should be noted that, instead of such a mechanical diaphragm,
An electro-optical element such as an electrochromic element capable of selectively changing the shield region as shown in FIGS. 2A to 2C may be used.

It is to be noted that an image pickup optical system of the present invention includes one having any of the above plural configurations.

[0024]

Embodiments 1 to 7 of the image pickup optical system of the present invention will be described below. Numerical data of each example will be described later.

3 to 3 are cross-sectional views including the optical axis of the imaging lens system constituting the image pickup optical systems of Examples 1 to 7 of the present invention.
It shows in FIG. In the figure, the first surface of the imaging lens system is r ₁ , the second surface
The surface is r ₂ , the third surface is r ₃ , the fourth surface is r ₄ , and the fifth surface is r _5.
, The surface distance between the first surface and the second surface is d ₁ , and the surface distance between the second surface and the third surface is
The surface spacing between the surfaces is d ₂ , the surface spacing between the third surface and the fourth surface is d ₃ , and the surface spacing between the fourth surface and the fifth surface is d ₄ . A double focal plane having different radii of curvature in the inner area and the outer area is indicated by W. Further, the object point due to the inner area is _ON , and the image plane is I.
Indicate.

As shown in FIG. 3, the image pickup optical system of Example 1 is composed of one lens, and the first surface thereof is a dual focal plane W having different radii of curvature in the inner region and the outer region. The diaphragm surface is provided on the first surface r ₁ . The numerical data described below are shown separately for the inner and outer regions, but
The surface r ₂ is a common surface, and the value of the surface distance d ₁ between the first surface r ₁ and the second surface r ₂ is different between the inner area and the outer area.

As shown in FIG. 4, the image pickup optical system of Example 2 is composed of two lenses, and the third surface thereof is a double focal plane W having different radii of curvature in the inner region and the outer region. Therefore, the diaphragm surface is provided on the third surface r ₃ . The numerical data described below are shown separately for the inner and outer areas.
The surface r ₁ , the second surface r ₂ , and the fourth surface r ₄ are common surfaces, and the value of the surface distance d ₂ between the second surface r ₂ and the third surface r _{3 is} the same as the third surface r ₃ and the fourth surface r 4.
The value of the surface distance d ₃ of the surface r ₄ is different in the inner area and the outer area.

The image pickup optical system of the third embodiment is as shown in FIG.
Consists of two lenses, and the diaphragm surface r between them₃But
The surface r on the first image side₂And the surface r on the second object side_FourBut
Double focus with different radii of curvature in the inner and outer regions
It is the point surface W. The numerical data described below is
Although shown separately in the outer region, its first surface r₁, Third surface r₃,
5th surface r_FiveIs a common surface, and the surface distance d between the first surface and the second surface is d.₁
Value, the surface distance d between the second surface and the third surface₂Value of the 3rd and 4th
Face spacing d₃Value, the surface distance d between the fourth surface and the fifth surface _FourThe value of the
Will be different in the inner and outer regions.

As shown in FIG. 6, the image pickup optical system of Example 4 is composed of two lenses, and the second surface thereof is a double focal plane W having different radii of curvature in the inner region and the outer region. The diaphragm surface is provided on the second surface r ₂ . The numerical data described below are shown separately for the inner and outer areas.
The surface r ₁ , the third surface r ₃ , and the fourth surface r ₄ are common surfaces, and the value of the surface distance d ₁ between the first surface r ₁ and the second surface r ₂ and the second surface r ₂ and the third surface r ₂ are the same.
The value of the surface distance d ₂ of the surface r ₃ is different between the inner area and the outer area.

As shown in FIG. 7, the image pickup optical system of Example 5 is composed of two lenses, and the third surface thereof is a double focal plane W having different radii of curvature in the inner region and the outer region. Therefore, the diaphragm surface is provided on the third surface r ₃ . The numerical data described below are shown separately for the inner and outer areas.
The surface r ₁ , the second surface r ₂ , and the fourth surface r ₄ are common surfaces, and the value of the surface distance d ₂ between the second surface r ₂ and the third surface r _{3 is} the same as the third surface r ₃ and the fourth surface r 4.
The value of the surface distance d ₃ of the surface r ₄ is different in the inner area and the outer area.

As shown in FIG. 8, the image pickup optical system of Example 6 is composed of two lenses, and the first surface thereof is a double focal plane W having different radii of curvature in the inner region and the outer region. The diaphragm surface is provided on the first surface r ₁ . The numerical data described below are shown separately for the inner and outer regions, but
The surface r ₂ , the third surface r ₃ , and the fourth surface r ₄ are common surfaces, and the value of the surface distance d ₁ between the first surface r ₁ and the second surface r ₂ is different between the inner area and the outer area. .

As shown in FIG. 9, the image pickup optical system of Example 7 is composed of two lenses, and the second surface thereof is a dual focal plane W having different radii of curvature in the inner region and the outer region. The diaphragm surface is provided on the second surface r ₂ . The numerical data described below are shown separately for the inner and outer areas.
The surface r ₁ , the third surface r ₃ , and the fourth surface r ₄ are common surfaces, and the value of the surface distance d ₁ between the first surface r ₁ and the second surface r ₂ and the second surface r ₂ and the third surface r ₂ are the same.
The value of the surface distance d ₂ of the surface r ₃ is different between the inner area and the outer area.

Numerical data of each of the above-mentioned embodiments will be shown below. Symbols other than the above, f is the focal length of the entire system, F _NO is the F number, φ _P is the entrance pupil radius, FB is the back focus, and s is
Is the object point distance, φ _S is the aperture radius (however, the aperture radius of the inner area is the value when the aperture is variable), φ
_i (i is an integer) is the effective radius of the inner surface of the i-plane, r ₁ , r ₂
... is the radius of curvature of each lens surface, d ₁ , d ₂ ... is the distance between the lens surfaces, n _e1 , n _e2 ... is the refractive index of the e-line of each lens, ν
_e1 , ν _e2 … are the Abbe number corresponding values (ν _{e
= (N e -1) / (} n F '-n C') (n e, n F ', n C' each e-line, F 'line (480.0nm), C' line (6
(Refractive index of 43.9 nm)). ). The aspherical shape is represented by the following formula, where x is an optical axis with the traveling direction of light being positive and y is a direction orthogonal to the optical axis.

X = (y ² / r) / [1+ {1- (K +
1) (y / r) ² } ^1/2 ] + A ₄ y ⁴ + A ₆ y ⁶ + A ₈ y ⁸ +
A ₁₀ y ¹⁰ However, r is a paraxial radius of curvature, K is a conic coefficient, A ₄ , A ₆ ,
A ₈ and A ₁₀ are aspherical coefficients of the 4th, 6th, 8th and 10th orders, respectively.

Example 1 (outer region) r ₁ = 1.424 (aspherical surface) d ₁ = 1.058 n _e1 = 1.52458 ν _e1 = 59.6 r ₂ = 1.490 (aspherical surface) aspherical coefficient first surface K = 0.0000 A ₄ = 7.5219 × 10 ^-3 A ₆ = -5.9 930 × 10 ^-3 A ₈ = 1.1076 × 10 ^-2 A ₁₀ = -3.3877 × 10 ^-3 Second surface K = 0.0000 A ₄ = 1.7284 × 10 ^-1 A ₆ = -2.4154 × 10 ^-1 A ₈ = 4.7112 × 10 ^-1 A ₁₀ = 0.0000 (inner area) r ₁ = 1.305 (aspherical surface) d ₁ = 1.061 n _e1 = 1.52458 ν _e1 = 59.6 r ₂ = 1.490 (aspherical surface) aspherical surface factor first surface _{K = 0.0000 A 4 = 6.4325 ×} 10 -2 A 6 = -1.2303 A 8 = 1.2875 × 10 +1 A 10 = -8.1239 × 10 +1 second surface _{K = 0.0000 A 4 = 1.7284 ×} 10 - ¹ A ₆ = -2.4154 × 10 ^-1 A ₈ = 4.7112 × 10 ^-1 A ₁₀ = 0.0000 Outer area Inner area f (mm) 4.764 3.575 φ _P (mm) 1.011 0.293 FB (mm) 3.191 3.191 s (mm) ∞ 17.944 φ _S (mm) 1.011 0.293.

Example 2 (outer region) r ₁ = 7.431 (aspherical surface) d ₁ = 0.832 n _e1 = 1.52458 ν _e1 = 59.6 r ₂ = 2.324 d ₂ = 1.171 r ₃ = 3.686 d ₃ = 2.432 n _e2 = 1.52458 ν _e2 = 59.6 r ₄ = -3.007 (aspherical surface) aspherical surface coefficient 1st surface K = 0.0000 A ₄ = -1.5023 × 10 ^-2 A ₆ = -8.3476 × 10 ^-5 A ₈ = 3.4403 × 10 ^-3 A ₁₀ = -1.0311 × 10 ^-3 4th surface K = 0.0000 A ₄ = 1.9133 × 10 ^-3 A ₆ = 8.7057 × 10 ^-4 A ₈ = 1.7880 × 10 ^-4 A ₁₀ = 2.7327 × 10 ^-4 (inner area) r ₁ = 7.431 (aspherical surface) d ₁ = 0.832 n _e1 = 1.52458 ν _e1 = 59.6 r ₂ = 2.324 d ₂ = 1.177 r ₃ = 2.791 d ₃ = 2.426 n _e2 = 1.52458 ν _e2 = 59.6 r ₄ = -3.007 (non-spherical) Aspherical surface Aspherical coefficient 1st surface K = 0.0000 A ₄ = -1.5023 × 10 ^-2 A ₆ = -8.3476 × 10 ^-5 A ₈ = 3.4403 × 10 ^-3 A ₁₀ = -1.0311 × 10 ^-3 4th surface K = 0.0000 A ₄ = 1.9133 × 10 ^-3 A ₆ = 8.7057 × 10 ^-4 A ₈ = 1.7880 × 10 ^-4 A ₁₀ = 2.7327 × 10 ^-4 Outer area Inner area f (mm) 4.800 4.065 φ _P (mm) 0.857 0.323 FB (mm) 5.376 5.376 s (mm) ∞ 15.155 φ _S (mm) 1.019 0.369.

Example 3 (outer region) r ₁ = 4.717 (aspherical surface) d ₁ = 2.090 n _e1 = 1.52458 ν _e1 = 59.6 r ₂ = 1.405 d ₂ = 0.287 r ₃ = ∞ (aperture) d ₃ = 0.280 r ₄ = 2.502 (aspherical surface) d ₄ = 2.255 n _e2 = 1.52458 ν _e2 = 59.6 r ₅ = -2.402 (aspherical surface) aspherical surface 1st surface K = 0.0000 A ₄ = -2.5965 × 10 ^-3 A ₆ =- 5.0727 × 10 ^-3 A ₈ = 1.9793 × 10 ^-3 A ₁₀ = -2.4123 × 10 ^-4 4th surface K = 0.0000 A ₄ = 1.6169 × 10 ^-2 A ₆ = 4.6356 × 10 ^-3 A ₈ = 1.2499 × 10 ^-3 A ₁₀ = -8.4763 × ₁₀ ^-3 fifth surface _{K = 0.0000 A 4 = -1.9135 ×} 10 -3 A 6 = 8.8160 × 10 -3 A 8 = -3.4986 × 10 -3 A 10 = 3.2282 × 10 - ³ (inner area) r ₁ = 4.717 (aspherical surface) d ₁ = 2.097 n _e1 = 1.52458 ν _e1 = 59.6 r ₂ = 1.898 d ₂ = 0.280 r ₃ = ∞ (aperture) d ₃ = 0.280 r ₄ = 2.463 (non-aperture) Spherical surface) d ₄ = 2.255 n _e2 = 1.52458 ν _e2 = 59.6 r ₅ = -2.402 (aspherical surface) aspherical coefficient first surface K = 0.0000 A ₄ = -2.5965 × 10 ^-3 A ₆ = -5.0727 × 10 ^-3 A ₈ = 1.9793 × 10 ^-3 A ₁₀ = -2 .4123 × 10 ^-4 4th surface K = 0.0000 A ₄ = -6.4381 × 10 ^-2 A ₆ = 1.0394 × 10 ^-1 A ₈ = 6.0498 × 10 ^-2 A ₁₀ = 1.8652 × 10 ^-1 5th surface K = 0.0000 A ₄ = -1.9135 × 10 ^-3 A ₆ = 8.8160 × 10 ^-3 A ₈ = -3.4986 × 10 ^-3 A ₁₀ = 3.2282 × 10 ^-3 Outer area Inner area f (mm) 4.800 4.019 φ _P (mm) 0.857 0.323 FB (mm) 4.501 4.501 s (mm) ∞ 15.155 φ ₂ (mm) 0.268 φ ₄ (mm) 0.303 φ _S (mm) 0.750 0.284.

Example 4 (outer region) r ₁ = -6.856 (aspherical surface) d ₁ = 1.217 n _e1 = 1.52458 ν _e1 = 59.6 r ₂ = -2.069 d ₂ = 0.810 r ₃ = -1.617 d ₃ = 1.346 n _{e2 = 1.52458 ν e2 = 59.6 r} 4 = -1.686 ( aspherical surface) = 0.0000 aspherical coefficients first plane ^{_{K A 4 = -3.1620 × 10 -2}} A 6 = 1.3449 × 10 -2 A 8 = -1.5622 × 10 - ² A ₁₀ = 2.9986 × 10 ^-3 4th surface K = 0.0000 A ₄ = 1.6940 × 10 ^-2 A ₆ = 4.0555 × 10 ^-3 A ₈ = -4.5382 × 10 ^-3 A ₁₀ = 2.3623 × 10 ^-3 (inside Area) r ₁ = -6.856 (aspherical surface) d ₁ = 1.224 n _e1 = 1.52458 ν _e1 = 59.6 r ₂ = -1.703 d ₂ = 0.803 r ₃ = -1.617 d ₃ = 1.346 n _e2 = 1.52458 ν _e2 = 59.6 r ₄ = -1.686 (aspherical surface) aspherical coefficients first surface _{K = 0.0000 A 4 = -3.1620 ×} 10 -2 A 6 = 1.3449 × 10 -2 A 8 = -1.5622 × 10 -2 A 10 = 2.9986 × 10 - ³ 4th surface K = 0.0000 A ₄ = 1.6940 × 10 ^-2 A ₆ = 4.0555 × 10 ^-3 A ₈ = -4.5382 × 10 ^-3 A ₁₀ = 2.3623 × 10 ^-3 Outside area Inside area f (mm) 4.800 4.049 φ _P (mm) 0.857 0.323 FB (mm) 4.847 4.8 47 s (mm) ∞ 15.153 φ _S (mm) 0.931 0.343.

Example 5 (outer region) r ₁ = -7.597 (aspherical surface) d ₁ = 1.127 n _e1 = 1.52458 ν _e1 = 59.6 r ₂ = -2.197 d ₂ = 0.575 r ₃ = -1.775 d ₃ = 0.925 n _{e2 = 1.52458 ν e2 = 59.6 r} 4 = -1.723 ( aspherical surface) = 0.0000 aspherical coefficients first plane ^{_{K A 4 = -3.9892 × 10 -2}} A 6 = 1.5707 × 10 -2 A 8 = -1.2148 × 10 - ² A ₁₀ = 2.3342 × 10 ^-3 4th surface K = 0.0000 A ₄ = 1.3291 × 10 ^-2 A ₆ = 3.2071 × 10 ^-4 A ₈ = -1.3469 × 10 ^-3 A ₁₀ = 2.5178 × 10 ^-3 (inside Area) r ₁ = -7.597 (aspherical surface) d ₁ = 1.127 n _e1 = 1.52458 ν _e1 = 59.6 r ₂ = -2.197 d ₂ = 0.581 r ₃ = -2.275 d ₃ = 0.919 n _e2 = 1.52458 ν _e2 = 59.6 r ₄ = -1.723 (aspherical surface) aspherical coefficients first surface _{K = 0.0000 A 4 = -3.9892 ×} 10 -2 A 6 = 1.5707 × 10 -2 A 8 = -1.2148 × 10 -2 A 10 = 2.3342 × 10 - ³ 4th surface K = 0.0000 A ₄ = 1.3291 × 10 ^-2 A ₆ = 3.2071 × 10 ^-4 A ₈ = -1.3469 × 10 ^-3 A ₁₀ = 2.5178 × 10 ^-3 Outside area Inside area f (mm) 4.800 3.870 φ _P (mm) 0.857 0.323 FB (mm) 5.001 5.0 01 s (mm) ∞ 14.600 φ _S (mm) 0.842 0.307.

Example 6 (outer region) r ₁ = -4.844 d ₁ = 1.175 n _e1 = 1.52458 ν _e1 = 59.6 r ₂ = -2.069 (aspherical surface) d ₂ = 0.706 r ₃ = -1.788 d ₃ = 1.279 n _{e2 = 1.52458 ν e2 = 59.6 r} 4 = -1.716 ( aspherical surface) = 0.0000 aspherical coefficients second surface ^{_{K A 4 = 3.1126 × 10 -2}} A 6 = -1.5180 × 10 -3 A 8 = -3.4962 × 10 - ³ A ₁₀ = 1.2136 × 10 ^-3 4th surface K = 0.0000 A ₄ = 8.8707 × 10 ^-3 A ₆ = 4.2059 × 10 ^-3 A ₈ = -5.6825 × 10 ^-3 A ₁₀ = 2.5585 × 10 ^-3 (inside Area) r ₁ = -16.638 d ₁ = 1.168 n _e1 = 1.52458 ν _e1 = 59.6 r ₂ = -2.069 (aspherical surface) d ₂ = 0.706 r ₃ = -1.788 d ₃ = 1.279 n _e2 = 1.52458 ν _e2 = 59.6 r ₄ = -1.716 (aspherical surface) aspheric coefficient the second surface _{K = 0.0000 A 4 = 3.1126 ×} 10 -2 A 6 = -1.5180 × 10 -3 A 8 = -3.4962 × 10 -3 A 10 = 1.2136 × 10 - ³ 4th surface K = 0.0000 A ₄ = 8.8707 × 10 ^-3 A ₆ = 4.2059 × 10 ^-3 A ₈ = -5.6825 × 10 ^-3 A ₁₀ = 2.5585 × 10 ^-3 Outer area Inner area f (mm) 4.800 4.078 φ _P (mm) 0.857 0.323 FB (mm) 5.024 5. 024 s (mm) ∞ 14.470 φ _S (mm) 0.857 0.323.

Example 7 (outer region) r ₁ = -6.599 (aspherical surface) d ₁ = 1.221 n _e1 = 1.52458 ν _e1 = 59.6 r ₂ = -2.088 d ₂ = 0.825 r ₃ = -1.639 d ₃ = 1.339 n _{e2 = 1.52458 ν e2 = 59.6 r} 4 = -1.683 ( aspherical surface) = 0.0000 aspherical coefficients first plane ^{_{K A 4 = -4.2086 × 10 -2}} A 6 = 1.5116 × 10 -2 A 8 = -1.3465 × 10 - ² A ₁₀ = 3.3009 × 10 ^-3 4th surface K = 0.0000 A ₄ = 1.3042 × 10 ^-2 A ₆ = 5.7733 × 10 ^-3 A ₈ = -3.3057 × 10 ^-3 A ₁₀ = 1.8797 × 10 ^-3 (inside) Area) r ₁ = -6.599 (aspherical surface) d ₁ = 1.242 n _e1 = 1.52458 ν _e1 = 59.6 r ₂ = -1.749 d ₂ = 0.803 r ₃ = -1.639 d ₃ = 1.339 n _e2 = 1.52458 ν _e2 = 59.6 r ₄ = -1.683 (aspherical surface) aspherical coefficients first surface _{K = 0.0000 A 4 = -4.2086 ×} 10 -2 A 6 = 1.5116 × 10 -2 A 8 = -1.3465 × 10 -2 A 10 = 3.3009 × 10 - ³ 4th surface K = 0.0000 A ₄ = 1.3042 × 10 ^-2 A ₆ = 5.7733 × 10 ^-3 A ₈ = -3.3057 × 10 ^-3 A ₁₀ = 1.8797 × 10 ^-3 Outer area Inner area f (mm) 4.800 4.112 φ _P (mm) 0.857 0.606 FB (mm) 4.975 4.9 75 s (mm) ∞ 15.189 φ _S (mm) 0.939 0.650.

F ₂ / f ₁ of the conditional expression (1) in the above embodiment
And the value of S ₁ / S ₂ of the conditional expression (2) are as follows. Examples f ₂ / f ₁ S ₁ / S ₂ 1 0.750 10.900 2 0.847 6.040 3 0.837 6.040 4 0.844 6.040 5 0.806 6.040 6 0.850 6.040 7 0.857 1.000.

The above-described image pickup optical system of the present invention is an image pickup apparatus which forms an object image by the image formation optical system and receives the image by the image pickup element such as CCD, and in particular, it is portable. It can be used for electronic devices that are particularly convenient to carry, such as personal digital assistants, mobile phones, and digital cameras.
Hereinafter, one embodiment will be exemplified.

FIG. 10A is a front view of the mobile phone 400,
10B is a side view, and FIG. 10C is a photographing optical system 40.
5 is a sectional view of FIG. As shown in FIGS. 10A to 10C, the mobile phone 400 includes a microphone unit 401 for inputting the voice of the operator as information, a speaker unit 402 for outputting the voice of the other party of the call, and an operator for information. Input dial 4 to enter
03, a monitor 404 for displaying a photographed image of the operator himself / herself or the other party, information such as a telephone number, and a photographing optical system 405.
And an antenna 406 for transmitting and receiving communication radio waves, and processing means (not shown) for processing image information, communication information, input signals and the like. Where the monitor 404
Is a liquid crystal display device. Further, in the drawing, the arrangement position of each component is not particularly limited to these. This photographing optical system 405
Has an objective lens 112 which is arranged on the photographing optical path 407 and which is an image pickup optical system having a dual focus according to the present invention, and an image pickup element chip 162 which receives an object image. These are built into the mobile phone 400.

Here, an optical low pass filter LF is additionally attached on the image pickup device chip 162 to integrally form an image pickup unit 160, and the objective lens 1
Since it can be fitted and attached to the rear end of the lens frame 113 of No. 12 with one touch, the centering of the objective lens 112 and the image pickup device chip 162 and the adjustment of the surface interval are unnecessary, and the assembly is easy. . Further, a cover glass 114 for protecting the objective lens 112 is arranged at the tip (not shown) of the lens frame 113.

A video signal of an object image such as a landscape received by the image pickup element chip 162 or an image of data (character data etc.) arranged at a short distance is input to a processing means (not shown) through a terminal 166. And is displayed as an electronic image on the monitor 404, on the monitor of the communication partner, or on both. Further, when transmitting an image or a character image to a communication partner, the processing means includes a signal processing function of converting the information of the object image received by the image pickup element chip 162 into a transmittable signal.

The above-described image pickup optical system of the present invention can be constructed, for example, as follows.

[1] One of the lens surfaces in the imaging lens system
Or, the two surfaces are different in the inner area and the outer area that are coaxial with the optical axis.
Has a curvature of
f ₁, The focal length of the entire system due to the curvature of the inner area is f₂age
When     0.3 ≦ f₂/ F₁≤ 0.9 (1) An image pickup optical system characterized by satisfying:

[2] In an imaging optical system in which one or two of the lens surfaces in the imaging lens system have different curvatures in an inner region and an outer region coaxial with the optical axis, an axial light flux passing through the outer region Let S _{1 be} the area on the entrance pupil plane of S, and let S ₂ be the area on the entrance pupil plane of the axial light flux passing through the inner region, then 0.5 ≦ S ₁ / S ₂ ≦ 11 (2) An imaging optical system characterized by satisfying.

[3] A diaphragm is arranged in the imaging lens system, and the above-mentioned one surface or two surfaces are arranged at a diaphragm position or a position adjacent to the diaphragm. The imaging optical system described.

[4] The image pickup optical system according to the above item 2, wherein 5.5 ≦ S ₁ / S ₂ ≦ 11 (2-1) is satisfied.

[5] An image pickup optical system according to any one of the above items 1 to 4, which comprises one lens.

[6] An image pickup optical system according to any one of the above items 1 to 4, which comprises two lenses.

[7] The image pickup optical system according to the above item 3, wherein the diaphragm is a mechanical diaphragm having a variable aperture.

[8] The image pickup optical system described in the above item 3, wherein the diaphragm is an electro-optical diaphragm having a variable aperture.

[0056]

[9] An image pickup optical system for picking up images of objects at different object distances
9. The image pickup optical system according to any one of items 8.

[10] An imaging optical system for reading short-distance data through the inner area and picking up a long-distance image through the outer area.
The imaging optical system according to any one of 1.

[11] 1 of the lens surface in the imaging lens system
The surfaces or two surfaces have different curvatures in the inner area and the outer area coaxial with the optical axis, the focal length of the entire system is f ₁ due to the curvature of the outer area, and the focal length of the entire system is f due to the curvature of the inner area. ₂ ,
When the area on the entrance pupil plane of the axial light flux passing through the outer region is S ₁ and the area on the entrance pupil plane of the axial light flux passing through the inner region is S ₂ , 0.3 ≦ f ₂ / f ₁ ≦ 0 .. (1) 0.5 ≦ S ₁ / S ₂ ≦ 11 (2) The imaging optical system is characterized by the following.

[12] In the above item 11, the items 2 to 1 above
An image pickup optical system having the configuration according to any one of 0.

[0060]

As is apparent from the above description, according to the image pickup optical system of the present invention, an optical system capable of simultaneously picking up an image of an object point having a large difference in object point distance without a movable part is realized. can do.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an image pickup optical system according to the present invention.

FIG. 2 is a diagram showing an example of a variable shape diaphragm that can be used in the present invention.

FIG. 3 is a cross-sectional view including the optical axis of the image pickup optical system according to the first embodiment of the present invention.

FIG. 4 is a sectional view including an optical axis of an image pickup optical system according to a second embodiment of the present invention.

FIG. 5 is a sectional view including an optical axis of an image pickup optical system according to a third embodiment of the present invention.

FIG. 6 is a sectional view including an optical axis of an image pickup optical system according to a fourth embodiment of the present invention.

FIG. 7 is a sectional view including an optical axis of an image pickup optical system according to a fifth embodiment of the present invention.

FIG. 8 is a sectional view including an optical axis of an image pickup optical system according to a sixth embodiment of the present invention.

FIG. 9 is a sectional view including an optical axis of an image pickup optical system according to a seventh embodiment of the present invention.

FIG. 10 is a front view, a side view, and a sectional view of a photographing optical system of a mobile phone in which an image pickup optical system according to the present invention is incorporated as an objective optical system.

[Explanation of symbols]

L ... Imaging optical system B ₁ ... On-axis light flux B ₂ passing through the outer area ... On-axis light flux I passing through the inner area ... Image plane O _N ... Short-distance object (object point) F ... Flare light P ... Entrance pupil W ... Two Heavy focal plane 112 ... Objective lens 113 ... Mirror frame 114 ... Cover glass 160 ... Imaging unit 162 ... Imaging element chip 166 ... Terminal 400 ... Mobile phone 401 ... Microphone section 402 ... Speaker section 403 ... Input dial 404 ... Monitor 405 ... Photographing optics System 406 ... Antenna 407 ... Photographing optical path

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 5/335 H04N 5/335 V F term (reference) 2H087 KA03 LA01 LA03 NA00 PA01 PA02 PA17 PB01 PB02 QA02 QA03 QA06 QA07 QA12 QA17 QA21 QA32 QA34 QA41 QA42 RA01 RA05 RA12 RA13 RA32 RA34 5C022 AC42 AC54 AC77 AC78 5C024 EX21 EX42

Claims (3)

[Claims] 1. One or two lens surfaces in an imaging lens system.
The surface has different curvatures in the inner region and the outer region coaxial with the optical axis, and the focal length of the entire system due to the curvature of the outer region is f ₁ ,
When the focal length of the entire system due to the curvature of the inner region is f ₂ , 0.3 ≦ f ₂ / f ₁ ≦ 0.9 (1) is satisfied. 2. One or two of the lens surfaces in the imaging lens system.
In an imaging optical system whose surfaces have different curvatures in an inner region and an outer region which are coaxial with the optical axis, the area on the entrance pupil plane of the axial light flux passing through the outer region is S ₁ , and the axial light flux of the axial light flux passing through the inner region is When the area on the entrance pupil surface is S ₂ , 0.5 ≦ S ₁ / S ₂ ≦ 11 (2) is satisfied. 3. A diaphragm is disposed in the image forming lens system, and the diaphragm is arranged at a diaphragm position or a position adjacent to the diaphragm.
A surface or two surfaces are arranged.
Alternatively, the imaging optical system described in 2.