JP2003149551A - Zoom lens and information equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute a small-sized zoom lens which is adaptive to a very small-sized imaging element and has an at least double power variation rate and excellent image forming performance by using a small number of lenses. SOLUTION: The zoom lens 1 comprises a 1st lens group GR1 having negative refracting power and a 2nd lens group GR2 having positive refracting power in order from the object side; the 1st lens group and 2nd lens group each being composed of a single lens. The zoom lens varies in power by moving the 2nd lens group on the optical axis and has an at least double power variation ratio, and at least two of the respective surfaces constituting the 1st and 2nd lens groups are made aspherical; and respective conditions of 7<TL<25, 0.5<f2(fw/f1-ft/f1)<10.0, 0.8<|f1.f2(1/fw-1/ft)|<15.0 are satisfied, where TL is the distance from the lens surface positioned most on the object side to the image plane, f1 the focal length of the 1st lens group, f2 the focal length of the 2nd lens group, fw the focal length of the whole lens system at the wide-angle end, and ft the focal length of the whole lens system at the telephone end.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small zoom lens suitable for an ultra-small image pickup device having a diagonal length of the image pickup surface of ⅕ to 1/7 inch and an image pickup apparatus using the zoom lens. Regarding equipment.

[0002]

2. Description of the Related Art In recent years, C-MOS (Com
plementary Metal Oxide Semiconductor) sensor and CC
Various image pickup devices using a solid-state image pickup device such as a D (Charge Coupled Device) have become widespread. Further, in the image pickup apparatus using these C-MOS sensor and CCD, the focal length of the image pickup lens can be continuously changed, that is, the magnification of the image formed on the image pickup surface can be continuously changed. Zoom lenses that can be used are widely used.

A zoom lens usually has 3 to 5 lens groups, and even if the number of lenses is small, it is 6 to 7,
Many use 10 or more. This is because the zoom lens has a structure in which the focal length is continuously changed (the magnification of the image formed on the image plane is changed) by moving the movable lens, and therefore, good imaging performance is obtained in the entire zoom range. Therefore, it is difficult to correct various aberrations by increasing the number of lenses and using expensive materials with different dispersions so that good imaging performance can be obtained on average in the entire zoom range. Because.

[0004]

By the way, various types of information devices such as mobile devices such as mobile phones and personal digital assistants, game devices, personal computers, etc., which have a small image pickup device built therein have appeared.

In the small-sized image pickup device built in the above-mentioned various devices, due to space limitation, a lens system is also used which is a single-focus small and lightweight lens system using one or two lenses, and also has an image pickup element. An ultra-small image pickup surface having a diagonal length of 1/4 inch or less is used. Especially, C-MOS
Since the sensor consumes little power, it is suitable for use in various information devices that are often carried.

Further, as described above, since the zoom lens is generally used in the image pickup apparatus, it is required to use the zoom lens also in the small-sized image pickup apparatus built in the above various information equipment. . When a zoom lens is applied to such a small-sized image pickup apparatus, it is necessary to make the size of the lens system as small and thin as possible and to reduce the cost.

As a conventional example in which a small zoom lens is realized with a small number of lenses, Japanese Patent Laid-Open No. 10-213745 is known.
The three-group, three-lens structure is formed by using the zoom lens having the three-group, six-lens structure described in Japanese Patent Publication No. JP-A-2004-12069, and the special lens having the radial type refractive index distribution described in Japanese Patent Laid-Open No. 11-6960. There is a zoom lens.

However, when the compact zoom lens shown as the above-mentioned conventional example is used in an image pickup apparatus incorporated in various devices, the former is insufficient in downsizing because the number of lenses is as large as 6, so various information is required. It cannot be used in a small image pickup device built into the equipment. In the latter, the number of lenses is three, which is small, but because a special lens having a radial type refractive index distribution is used, image pickup is performed. There is a problem that the device itself becomes expensive.

Therefore, in a small-sized zoom lens which is used in an image pickup device incorporated in various equipment and which corresponds to an ultra-small image pickup device, the number of lenses is minimized and no special material is used as a lens material. Like this
There is a demand for further miniaturization and price reduction.

In view of the above problems, the present invention is suitable for an ultra-small image pickup device, and has a variable zoom ratio of at least 2 or more and a small zoom lens having good image forming performance, which is inexpensive with a small number of lenses. The challenge is to configure

[0011]

In order to solve the above-mentioned problems, the present invention is a zoom lens and an information device using the zoom lens, wherein the zoom lens has a negative refracting power in order from the object side. By including the first lens group having and the second lens group having a positive refractive power, both the first lens group and the second lens group are constituted by a single lens, and the second lens group moves on the optical axis. The zoom lens is configured to perform zooming, has a zoom ratio of at least 2 or more, and at least two of the surfaces of the lenses forming the first lens group and the second lens group are aspherical surfaces, and at the same time, TL Is the distance from the lens surface located closest to the object side to the image surface, f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, fw is the focal length at the wide-angle end of the entire lens system, and ft is At the telephoto end of the entire lens system When the focal length, 7 <TL <2
5, 0.5 <f2 (fw / f1-ft / f1) <10.
0, 0.8 <| f1 · f2 (1 / fw-1 / ft) | <
It satisfies each condition of 15.0.

Therefore, it becomes possible to realize a compact zoom lens having a two-group, two-lens structure and an information device using the compact zoom lens having a two-group, two-lens structure.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The zoom lens according to the present invention has a C-size of about ⅕ to 1/7 inch, which has a number of pixels of about several hundred thousand.
It is a lens system suitable for ultra-small image pickup devices such as MOS sensors and CCDs, and is suitable for use in image pickup devices built into various mobile devices such as mobile phones and personal digital assistants, game machines, personal computers, and plastic materials. It is possible to use an inexpensive manufacturing method by die molding while using

That is, the zoom lens of the present invention comprises, in order from the object side, a first lens group having a negative refracting power and a second lens group having a positive refracting power.
The lens groups are both composed of a single lens, and the second lens group is adapted to perform zooming by moving on the optical axis, and has a zooming ratio of at least 2 or more. Among the surfaces of the lenses that form the lens group, at least two surfaces have an aspherical surface and have a simple structure of two elements in two groups.

The first lens and the second lens are formed of a plastic material by molding. Therefore, even if the outer diameter of the lens is small, it is possible to form aspherical surfaces on both surfaces with high precision, and it is possible to mass-produce at low cost.

In the zoom lens of the present invention, TL is the distance from the lens surface located closest to the object side to the image surface, f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, and fw is Focal length at wide-angle end of entire lens system, ft
Is the focal length at the telephoto end of the entire lens system, 7 <TL <25 (conditional expression 1), 0.5 <f2 (fw / f1-ft / f1) <10.0 (conditional expression 2), 0. 8 <| f1 · f2 (1 / fw-1 / ft) | <15.0 (conditional expression 3).

Furthermore, the zoom lens according to the present invention moves the second lens group, or the first lens group and the second lens group independently on the optical axis, thereby maintaining good imaging performance as a whole. It is desirable to focus while changing the focal length of the. By moving the second lens group or the first lens group and the second lens group independently on the optical axis, a zoom ratio of 2 times or more is achieved, and cost reduction and downsizing are realized. It becomes possible to do.

In the zoom lens of the present invention, there are few materials having suitable dispersion in the lens material, and chromatic aberration is caused by using materials having different dispersions for the two lenses constituting the first lens group and the second lens group. If it cannot be corrected, it is desirable to arrange an appropriate diffractive optical element between the second lens group and the image plane to correct chromatic aberration.

Conditional expression 1 defines the range (unit: mm) of the distance TL from the lens surface located closest to the object side of the zoom lens of the present invention to the image surface, that is, the total length TL. That is, if the total length TL is 25 mm or more, it becomes too large and the commercial value is lost. On the contrary, the total length TL is 7 m.
If it is less than or equal to m, the curvature of each lens surface becomes too small, and manufacturing becomes difficult.

Conditional expressions 2 and 3 define the relationship among the focal length f1 of the first lens group, the focal length f2 of the second lens group, the focal length fw at the wide-angle end, and the focal length ft at the telephoto end. Yes, f2 (fw / f1-ft /
By setting each value of f1) and | f1 · f2 (1 / fw-1 / ft) | within the specified range, each aberration becomes favorable.

The details of the zoom lens of the present invention will be described below with reference to Numerical Examples 1 to 3 and the accompanying drawings.

In the following description, "ri" is the i-th surface counted from the object side and its radius of curvature, and "di" is the distance between the i-th surface and the (i + 1) th surface counted from the object side. , "Ni" is the d-line (wavelength 587.
The refractive index at 6 nm) and "nFL" indicate the refractive index at the d-line of the filter.

The aspherical surface is defined by the following formula 1 where "c" is a curvature at a surface vertex, "z" is an optical axis, "yz" is a sagittal surface, and "k" is a conic constant. And

[0024]

[Equation 1]

FIGS. 1 to 3 show a zoom lens 1 according to Numerical Example 1 of the zoom lens of the present invention, in which the first lens group GR1 and the second lens group GR2 are respectively formed.
The first lens L1 is a meniscus lens having a negative refracting power with a convex surface facing the object side, and the second lens L2 is a meniscus lens having a positive refracting power having a concave surface facing the object side.

The zoom lens 1 includes the first lens group GR.
A diaphragm STP is disposed between the first lens group GR2 and the first lens group GR2, and the diaphragm STP moves as the second lens group GR2 moves.
The optical system is configured to move integrally on the optical axis, and between the second lens group GR2 and the image plane IMG, control of frequency components in a specific region (not shown) and control of light rays outside the visible light region are performed. One of various filters or a combination of a plurality of filters and a cover glass of the image pickup element are arranged.

As described above, the first lens group GR1 and the second lens group GR1
A diaphragm STP is arranged between the lens group GR2 and the diaphragm STP so as to move integrally on the optical axis with the movement of the second lens group GR2, so that the second lens group and the diaphragm are integrated. This makes it possible to simplify the manufacturing process and is advantageous in terms of cost.

At the wide-angle end, the zoom lens 1 is shown in FIG.
As shown in, the first lens group GR1 is at the position farthest from the image plane IMG, and conversely, the second lens group GR2 is at the position closest to the image plane IMG. Therefore, at this wide-angle end, the distance between the first lens group GR1 and the second lens group is maximum, and the total length of the zoom lens 1 is maximum.
Then, as the zoom lens 1 is zoomed from the wide-angle end to the telephoto end, as shown in FIGS.
The distance between the lens group GR1 and the second lens group GR2 is narrowed, and conversely, the distance between the second lens and the image plane IMG is widened, and the total length of the zoom lens 1 is shortened.

As described above, in the zoom lens 1,
By appropriately moving the second lens group GR2 with respect to the moving amount of the first lens group GR1, it is possible to obtain a good image on the image plane IMG while changing the focal length.

Table 1 shows each numerical value of the zoom lens 1.

[0031]

[Table 1]

Table 2 shows numerical values at the wide-angle end, the intermediate focus position, and the telephoto end of d2 and d5 in which the distance changes with zooming.

[0033]

[Table 2]

Table 3 shows the conical constant k of each surface of the first lens L1 and the second lens L2 formed by an aspherical surface and the aspherical coefficients A to D of the 4th to 10th order. In addition, "E" in Table 3 represents an exponential expression with a base of 10, for example, "1".
" ^0-03 " is represented by "E-03".

[0035]

[Table 3]

Table 4 shows the focal length of the zoom lens 1, the F number (wide-angle end-intermediate focal position-telephoto end), the zoom ratio, the angle of view (wide-angle end-intermediate focal position-telephoto end), and the conditional expressions 1 to. The numerical value regarding 3 is shown.

[0037]

[Table 4]

The wide-angle end of the zoom lens 1 is shown in FIGS.
Spherical aberration, astigmatism at the intermediate focal position and the telephoto end,
Shows distortion. In the spherical aberration diagram and the distortion diagram, the solid line shows the value at the d line and the broken line shows the value at the F line (wavelength 486.1 nm). In the astigmatism diagram, the solid line shows the value at the d line on the sagittal image plane. The value, the thick solid line shows the value at the d line on the meridional image plane, the broken line shows the value at the F line on the sagittal image plane, and the thick broken line shows the value at the F line on the meridional image plane (see FIG. 1 described later).
The same applies to 0 to FIG. 12 and FIGS. 16 to 18. ).

As can be seen from the aberration diagrams of FIGS. 4 to 6, the zoom lens 1 is well corrected for various aberrations at all focal length positions from the wide-angle end to the telephoto end, and has good imaging performance. It is understood that it is being done.

FIGS. 7 to 9 show a zoom lens 2 according to Numerical Example 2 of the zoom lens of the present invention. The first lens group GR1 and the second lens group GR2 are respectively
The first lens L1 which is a meniscus lens having a negative refractive power with the convex surface facing the object side, and the second lens L2 which is a biconvex lens.
It is composed by.

The zoom lens 2 includes the second lens group GR.
2 and the image plane IMG are arranged between the diaphragm STP and the image plane IMG. The diaphragm STP is arranged to move integrally on the optical axis as the second lens group GR2 moves. Between, and one of various filters for controlling frequency components in a specific region (not shown) or controlling light rays outside the visible light region, or a combination thereof, and a cover glass of the image sensor. And are arranged.

The zoom lens 2 is shown in FIG.
As shown in, the first lens group GR1 is at the position farthest from the image plane IMG, and conversely, the second lens group GR2 is at the position closest to the image plane IMG. Therefore, at this wide-angle end, the distance between the first lens group GR1 and the second lens group is maximum, and the total length of the zoom lens 2 is maximum.
Then, as the zoom lens 2 is zoomed from the wide-angle end to the telephoto end, as shown in FIGS.
The distance between the lens group GR1 and the second lens group GR2 is narrowed, and conversely, the distance between the second lens and the image plane IMG is widened, and the total length of the zoom lens 2 is shortened.

Compared with the zoom lens 1, the zoom lens 2 has a structure in which the amount of movement of the first lens unit is small and the total length is small in the process from the wide-angle end to the telephoto end. A certain first lens L1 does not move much to the object side even at the wide-angle end, and is smaller. Further, the zoom lens 2 strengthens the refracting power of the first lens L1, and the stop S
By disposing the TP on the image side of the second lens L2 and moving the exit pupil position toward the image side, distortion in the entire zoom range from the wide-angle end to the telephoto end can be made larger than that of the zoom lens 1. In addition to being able to satisfactorily correct, the manufacturing process can be simplified, which is advantageous in terms of cost.

Also in the zoom lens 2, by appropriately moving the second lens group GR2 with respect to the moving amount of the first lens group GR1, it is possible to obtain a good image on the image plane while changing the focal length. It is possible.

Table 5 shows each numerical value of the zoom lens 2.

[0046]

[Table 5]

Table 6 shows numerical values at d2 and d5 at the wide-angle end, the intermediate focal point position, and the telephoto end where the distance changes with zooming.

[0048]

[Table 6]

Table 7 shows the conical constant k and the fourth-order to tenth-order aspherical surface coefficients A to D of the respective surfaces of the first lens L1 and the second lens L2 which are aspherical surfaces.

[0050]

[Table 7]

Table 8 shows the focal length of the zoom lens 2, the F number (wide-angle end-intermediate focus position-telephoto end), the zoom ratio, the angle of view (wide-angle end-intermediate focus position-telephoto end), and the conditional expressions 1 to 1. The numerical value regarding 3 is shown.

[0052]

[Table 8]

10 to 12 show spherical aberration, astigmatism, and distortion of the zoom lens 2 at the wide-angle end, the intermediate focal position, and the telephoto end.

As is apparent from the aberration diagrams of FIGS. 10 to 12, the zoom lens 2 has various aberrations favorably corrected at all focal length positions from the wide-angle end to the telephoto end, and excellent imaging performance is obtained. It is understood that it is being done.

FIGS. 13 to 15 show a zoom lens 3 according to Numerical Example 3 of the zoom lens of the present invention. The first lens group GR1 and the second lens group GR2 each have a convex surface facing the object side. The first lens L1 is a meniscus lens having a negative refractive power, and the second lens L2 is a biconvex lens.

The zoom lens 3 includes the first lens group GR.
The position of 1 is fixed, and only the second lens group GR2 moves on the optical axis to keep the total length constant,
It is adapted to carry out zooming and focusing by changing the focal length. Further, in the zoom lens 3, a diaphragm STP is arranged between the second lens group GR2 and the image plane IMG, and the diaphragm STP is provided.
Is configured to move integrally on the optical axis with the movement of the second lens group GR2, and the stop STP and the image plane IM
Between G and one of various filters (not shown) for controlling frequency components in a specific region and controlling light rays outside the visible light region, or a combination of a plurality of filters, and a cover for the image sensor. Glass and is arranged.

At the wide-angle end, the zoom lens 3 has the structure shown in FIG.
As shown in FIG. 3, the second lens group GR2 is located farthest from the first lens group GR1 and near the image plane IMG. And
As the zoom lens 3 is zoomed from the wide-angle end to the telephoto end, as shown in FIGS. 13 to 15, the second lens group GR2 moves away from the image plane IMG and the first lens group GR1.
And the distance between the first lens group GR1 and the second lens group GR2 becomes the shortest.

Further, the zoom lens 3 has a diaphragm STP.
Is provided on the image side of the second lens L2 and the exit pupil position is moved toward the image side, so that the distortion aberration is better than that of the zoom lens 1 in the entire zoom range from the wide-angle end to the telephoto end. It is possible to make corrections to the above, and the manufacturing process can be simplified, which is advantageous in terms of cost.

The zoom lens 3 has a structure in which the first lens group GR1 does not move and only the second lens group GR2 moves on the optical axis, so that the focal length is changed to perform zooming and the focal position is corrected. It also focuses on you. Therefore, the entire length of the zoom lens 3 does not change during zooming from the wide-angle end to the telephoto end.
Compared with the above, the size is further reduced, and since the first lens L1 which is the front lens does not move, it is easy to handle when it is commercialized, and it is possible to reduce damage and the like.

Also in the zoom lens 3, by moving only the second lens group GR2, it is possible to obtain a good image on the image plane while changing the focal length.

Table 9 shows each numerical value of the zoom lens 3.

[0062]

[Table 9]

Table 10 shows the numerical values at d2 and d5 at the wide-angle end, the intermediate focus position, and the telephoto end where the distance changes with zooming.

[0064]

[Table 10]

Table 11 shows the conical constant k and the fourth-order to tenth-order aspherical surface coefficients A to D of the respective surfaces of the first lens L1 and the second lens L2 which are aspherical surfaces.

[0066]

[Table 11]

Table 12 shows the focal length of the zoom lens 3, the F number (wide-angle end-intermediate focal position-telephoto end), the zoom ratio, the angle of view (wide-angle end-intermediate focal position-telephoto end), and the conditional expression 1 above.
Numerical values relating to 3 are shown.

[0068]

[Table 12]

16 to 18 show spherical aberration, astigmatism, and distortion at the wide-angle end, the intermediate focus position, and the telephoto end of the zoom lens 3.

As is clear from the aberration diagrams in FIGS. 16 to 18, the zoom lens 2 has good correction of various aberrations and good imaging performance at all focal length positions from the wide-angle end to the telephoto end. It is understood that it is being done.

As described above, the zoom lenses 1 and 2
3 and 3 have a two-group two-lens structure using aspherical surfaces, and have a simple structure in which each lens is formed by molding using a plastic material, so that low cost and downsizing are realized. It is possible to In addition, the first lens group GR1 and the second lens group GR2 are independent of each other, or
By moving only the lens group GR2 on the optical axis,
It is also possible to change the overall focal length while maintaining good imaging performance so as to have a zoom ratio of 2 times or more.

Finally, an example 10 of an information device incorporating a small image pickup device using the zoom lens 1, 2 or 3 as an image pickup lens will be described.

FIG. 19 schematically shows the configuration of the information device 10. The information device 10 is, for example, a mobile device such as a mobile phone or a mobile information terminal, a game device, a personal computer, and the like. A small-sized image pickup device 11 is included as a part of the function.

The information device 10 includes an image pickup device 11 including a zoom lens 1, 2 or 3 and an image pickup device 12 which converts a light beam incident from the zoom lens 1, 2 or 3 into an electric signal and outputs the electric signal. Information processing unit 1 that performs appropriate processing using the electric signal output from the image sensor 12 as image information
3 and an information storage unit 14 that stores the image information output from the information processing unit.

The zoom lens 1, 2 or 3 constituting the image pickup device 11 and the image pickup element 12 are housed and integrated in a plastic casing 15. By the way, the total length of the housing 15 in which the zoom lens 1, 2 or 3 and the image pickup device 12 are integrally housed is about 7 to 25 mm.

The image pickup device 12 has a C-MO of about ⅕ to ⅙ inch having several hundreds of thousands of pixels.
A solid-state image sensor such as an S sensor or CCD is used, but C
It is desirable to use a C-MOS sensor that consumes less power than a CD.

In addition, the information equipment 10 includes the image pickup device 11 described above.
In addition to the above, an operation unit 16 for performing various operations, an information input / output unit 17 for inputting / outputting various kinds of information including information that is captured by the imaging device 11 and processed as image information by the information processing unit 13 to the outside, It has a display unit 18 for displaying various information including image information.

In the information device 10, various operations including image capturing are performed by the user operating the operation unit 16 having operation switches and the like. For example, an electric signal output from the image sensor 12 and input to the information processing unit 13 by an image capturing operation is processed as image information, is temporarily recorded in a built-in memory forming a part of the information storage unit 14, and then is stored. By the operation of, the recording on an external recording medium forming a part of the information storage unit 14 like the built-in memory, the display on the information display unit 18 including a display device, the output from the information input / output unit 17 to the outside, etc. Appropriate processing is performed.

In the information device 10, the image pickup device 11
In addition, a compact and lightweight zoom lens 1, 2 or 3 made of plastic and composed of 2 elements in 2 groups is used, and an ultra-small image pickup element 1 is used.
Since the image pickup device 11 is used, the space for disposing other components is not compressed by incorporating the image pickup device 11, and the weight increase due to incorporating the image pickup device 11 is small.

It should be noted that the specific shapes and structures of the respective portions shown in the above-mentioned embodiments are merely examples of the implementation in carrying out the present invention, and the techniques of the present invention can be realized by these. The scope should not be limitedly interpreted.

[0081]

As is apparent from the above description, the zoom lens according to the present invention comprises, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power. The first lens group and the second lens group are both composed of a single lens, and the second lens group moves along the optical axis to perform zooming, and has a zoom ratio of at least 2 or more. Of the surfaces of the lenses that form the first lens group and the second lens group, at least two surfaces are aspherical surfaces, and TL is the distance from the lens surface located closest to the object side to the image surface, f1 7 <TL <25, where f2 is the focal length of the second lens group, fw is the focal length at the wide-angle end of the entire lens system, and ft is the focal length at the telephoto end of the entire lens system. 0.5 <
f2 (fw / f1-ft / f1) <10.0, 0.8 <
It is characterized in that each condition of | f1 · f2 (1 / fw-1 / ft) | <15.0 is satisfied.

Therefore, with a simple structure of two lenses in two groups using aspherical surfaces, it is possible to inexpensively manufacture a compact zoom lens having good imaging performance and a zoom ratio of 2 or more.

Further, the information equipment of the present invention is provided with an image pickup device including a zoom lens and an image pickup device for converting a light flux incident from the zoom lens into an electric signal and outputting the electric signal, and includes information inputted from the image pickup device. An information device having an information processing unit that performs appropriate processing on various types of information, in which a zoom lens and an image sensor are housed in a common housing, and the zoom lens sequentially applies negative refractive power from the object side. Have first
It is composed of a lens group and a second lens group having a positive refractive power, both the first lens group and the second lens group are constituted by a single lens, and the second lens group moves along the optical axis to change the magnification. And at least two surfaces of the surfaces of the lenses that form the first lens group and the second lens group have an aspherical surface and a TL is closest to the object side. The distance from the lens surface located at to the image plane, f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, fw is the focal length at the wide-angle end of the entire lens system, and ft is the focal length of the entire lens system. Assuming the focal length at the telephoto end, 7 <TL <25, 0.5 <f2 (fw / f1
−ft / f1) <10.0, 0.8 <| f1 · f2 (1
/Fw-1/ft)|<15.0 is satisfied.

Therefore, by using a compact and lightweight zoom lens and using an ultra-compact image pickup element, the space for disposing other components is not pressed by incorporating the image pickup apparatus, and the image pickup apparatus is It is possible to minimize the increase in weight due to the inclusion of the.

According to the invention described in claim 2,
Since the lens group and the second lens group move independently on the optical axis to perform the magnification change, it is possible to perform the magnification change while maintaining a good imaging performance.

In the invention described in claim 3, the first aspect
Since the lens group is composed of the first lens which is a concave meniscus lens, and the second lens group is composed of the second lens which is a convex meniscus lens, it is possible to obtain good imaging performance with an appropriate power arrangement.

In the invention described in claim 4, the first
Since the lens group is composed of the first lens which is a concave meniscus lens, and the second lens group is composed of the second lens which is a biconvex lens, it is possible to obtain good imaging performance by an appropriate power arrangement and to make the optical system It can be made smaller.

In the invention described in claim 5, the second aspect
Since the diaphragm is arranged in the vicinity of the lens group and the diaphragm moves integrally with the second lens group on the optical axis,
It becomes possible to integrate the lens group and the diaphragm,
The manufacturing process can be simplified, and it is also advantageous in terms of cost.

According to the invention described in claim 6, since the diaphragm is arranged between the second lens group and the image plane, the distortion aberration is well corrected in the entire zoom range from the wide-angle end to the telephoto end. can do.

In the invention described in Item 7, since each lens is made of a plastic material, the zoom lens can be constructed at low cost.

[Brief description of drawings]

FIG. 1 shows Numerical example 1 of the zoom lens of the present invention together with FIGS. 2 to 6, and is a diagram schematically showing the lens configuration at the wide-angle end.

FIG. 2 is a diagram schematically showing a lens configuration at an intermediate focus position.

FIG. 3 is a diagram schematically showing a lens configuration at a telephoto end.

FIG. 4 is a diagram showing various aberrations at the wide-angle end.

FIG. 5 is a diagram showing various aberrations at an intermediate focus position.

FIG. 6 is a diagram showing various aberrations at the telephoto end.

FIG. 7 shows Numerical example 2 of the zoom lens of the present invention together with FIGS. 8 to 12, and is a diagram schematically showing the lens configuration at the wide-angle end.

FIG. 8 is a diagram schematically showing a lens configuration at an intermediate focus position.

FIG. 9 is a diagram schematically showing a lens configuration at a telephoto end.

FIG. 10 is a diagram showing various aberrations at the wide-angle end.

FIG. 11 is a diagram showing various aberrations at an intermediate focus position.

FIG. 12 is a diagram showing various aberrations at the telephoto end.

FIG. 13 shows Numerical example 3 of the zoom lens of the present invention together with FIGS. 14 to 18, and is a diagram schematically showing the lens configuration at the wide-angle end.

FIG. 14 is a diagram schematically showing a lens configuration at an intermediate focus position.

FIG. 15 is a diagram schematically showing a lens configuration at a telephoto end.

FIG. 16 is a diagram showing various aberrations at the wide-angle end.

FIG. 17 is a diagram showing various aberrations at an intermediate focus position.

FIG. 18 is a diagram showing various aberrations at the telephoto end.

FIG. 19 is a block diagram schematically showing an example of the information device of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Zoom lens, 2 ... Zoom lens, 3 ... Zoom lens, 10 ... Information equipment, 11 ... Imaging device, 12 ... Imaging element, 13 ... Information processing part, GR1 ... 1st lens group, GR2
... second lens group, L1 ... first lens, L2 ... second lens, STP ... diaphragm

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[Procedure amendment]

[Submission date] December 4, 2001 (2001.12.
4)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

Further, non-spherical, curvature "c" in the surface apex, the optical axis "z" and a conical coefficient to "k", and shall be defined by Equation 1 below.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

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The wide-angle end of the zoom lens 1 is shown in FIGS.
Spherical aberration, astigmatism at the intermediate focal position and the telephoto end,
Shows distortion. In the spherical aberration diagram and the distortion diagram, the solid line (d) is the d line, and the broken line (F) is the F line (wavelength 48
In the astigmatism diagram, the solid line (Sd) is the value at the d line on the sagittal image plane, and the thick solid line (Md) is the d on the meridional image plane.
A line value, a broken line (SF) indicates a value on the F line on the sagittal image plane, and a thick broken line (MF) indicates a value on the F line on the meridional image plane (see FIG. 10 described later).
The same applies to FIGS. 12 and 16 to 18. ).

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

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[Figure 4]

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

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[Figure 5]

[Procedure Amendment 5]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

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[Figure 6]

[Procedure correction 6]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 10

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[Figure 10]

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[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 11

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FIG. 11

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[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 12

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[Fig. 12]

[Procedure Amendment 9]

[Document name to be corrected] Drawing

[Correction target item name] Fig. 16

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FIG. 16

[Procedure Amendment 10]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 17

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FIG. 17

[Procedure Amendment 11]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 18

[Correction method] Change

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FIG. 18

Continued front page    F-term (reference) 2H054 AA00                 2H087 KA03 PA02 PA17 PB02 QA02                       QA07 QA17 QA21 QA32 QA34                       QA42 RA12 RA13 RA32 RA35                       RA42 SA07 SA09 SA62 SA63                       SB02 SB12 UA01                 5C022 AB66 AC54

Claims (8)

[Claims] 1. A first lens group having a negative refracting power and a second lens group having a positive refracting power in order from the object side, both of the first lens group and the second lens group being a single lens. A zoom lens configured by: the second lens group is configured to perform zooming by moving on the optical axis, and has a zooming ratio of at least 2 times or more; A zoom lens characterized in that at least two of the surfaces of the lenses constituting the second lens group are aspherical surfaces and the following conditions are satisfied. 7 <TL <25 0.5 <f2 (fw / f1-ft / f1) <10.0 0.8 <| f1 · f2 (1 / fw-1 / ft) | <1
5.0 where TL: distance from the lens surface closest to the object side to the image plane, f1: focal length of the first lens group, f2: focal length of the second lens group, fw: wide-angle end of the entire lens system , Ft: focal length at the telephoto end of the entire lens system. 2. The zoom lens according to claim 1, wherein the first lens group and the second lens group are independently moved on the optical axis to perform zooming. . 3. The zoom lens according to claim 1, wherein the first lens group is composed of a first lens which is a concave meniscus lens, and the second lens group is composed of a second lens which is a convex meniscus lens. . 4. The zoom lens according to claim 1, wherein the first lens group is composed of a first lens which is a concave meniscus lens, and the second lens group is composed of a second lens which is a biconvex lens. 5. The diaphragm according to claim 1, wherein a diaphragm is arranged in the vicinity of the second lens group, and the diaphragm moves integrally with the second lens group on the optical axis. Zoom lens. 6. The zoom lens according to claim 5, wherein the stop is arranged between the second lens group and the image plane. 7. The zoom lens according to claim 1, wherein each lens is made of a plastic material. 8. An image pickup device comprising a zoom lens and an image pickup device for converting a light beam incident from the zoom lens into an electric signal and outputting the electric signal. Various information including information input from the image pickup device is provided. An information device including an information processing unit that performs appropriate processing, wherein the zoom lens and the image sensor are housed in a common housing, and the zoom lens has a negative refractive power in order from the object side. By including a lens group and a second lens group having a positive refractive power, both the first lens group and the second lens group are composed of a single lens, and the second lens group moves on the optical axis. The zooming is performed, and the zooming ratio is at least 2 times or more, and at least two of the surfaces of the lenses forming the first lens group and the second lens group are aspherical surfaces. With Information equipment, characterized in that it is to satisfy each condition. 7 <TL <25 0.5 <f2 (fw / f1-ft / f1) <10.0 0.8 <| f1 · f2 (1 / fw-1 / ft) | <1
5.0 where TL: distance from the lens surface closest to the object side to the image plane, f1: focal length of the first lens group, f2: focal length of the second lens group, fw: wide-angle end of the entire lens system , Ft: focal length at the telephoto end of the entire lens system.