CN103885157A

CN103885157A - Shooting lens

Info

Publication number: CN103885157A
Application number: CN201210560035.1A
Authority: CN
Inventors: 田中宏明; 松坂庆二; 王明珠
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Opto Inc
Priority date: 2012-12-21
Filing date: 2012-12-21
Publication date: 2014-06-25
Anticipated expiration: 2032-12-21
Also published as: JP2014123097A; CN103885157B; TWI487938B; TW201425990A

Abstract

The invention relates to a shooting lens. The shooting lens comprises an aperture diaphragm, a positive first lens, a negative second lens, a third lens, a positive fourth lens and a negative fifth lens from the object side in sequence. The shooting lens meets the following conditional expressions: 0.8<= (r2F+r2R)/ (r2F-r2R)<=1.2; 0.8<= (r4F+r4R)/ (r4F-r4R)<=1.6; -1.6<=f2/f<=-0.8; and -0.212<=T5/f5<=-0.010 (r2F: curvature radius of object side surface of the second lens; r2R: curvature radius of image side surface of the second lens; r4F: curvature radius of object side surface of the fourth lens; r4R: curvature radius of image side surface of the fourth lens; f2: focal length of the second lens; f: whole focal length of the shooting lens; T5: thickness in optical axis of the fifth lens; and f5: focal length of the fifth lens). The shooting lens is used for forming the image of a shot object on the shooting surface of a shooting element.

Description

Shooting lens

Technical Field

The present invention relates to a photographing lens. More specifically, the present invention relates to an imaging optical device in which an image of a subject is captured by an imaging element (for example, a solid-state imaging element such as a CCD (charge coupled device) type image sensor or a CMOS (complementary metal oxide semiconductor) type image sensor), a digital device with an image input function mounted on the imaging optical device, and a compact imaging lens in which an optical image of the subject is formed on a light receiving surface of the imaging element with high resolution.

Background

In recent years, imaging optical devices using solid-state imaging elements such as CCD-type image sensors and CMOS-type image sensors have been mounted on portable terminals, and along with the spread of the portable terminals, devices equipped with imaging optical devices using imaging elements having a high number of pixels have been offered to the market in order to obtain images with higher image quality. The image pickup device having a high number of pixels has been once increased in size, and in recent years, the pixels have been increasingly refined, and the image pickup device has been reduced in size. An imaging lens used for such a high-definition imaging element is required to have high resolution so as to correspond to high-definition pixels.

The resolution of the lens is limited by the F value, and since a bright lens with a small F value can achieve high resolution, sufficient performance cannot be achieved at an F value of about F2.8. Therefore, a bright imaging lens of about F2 suitable for an imaging element with higher pixel count, higher resolution, and smaller size is required. As an imaging lens for such applications, an imaging lens having a 5-plate structure has been proposed because a large aperture ratio and high performance can be achieved as compared with a lens having a 3-plate structure or a 4-plate structure.

As the imaging lens having the 5-piece structure,

patent documents

1 and 2 disclose imaging lenses including a front group including a first lens having a positive or negative refractive index and a second lens having a positive refractive index, an aperture stop, and a rear group including a third lens having a negative refractive index, a fourth lens having a positive refractive index, and a fifth lens having a negative or positive refractive index in this order from the object side. As a 4-lens imaging lens, patent document 3 discloses an imaging lens including, in order from the object side, a front group including a first lens having a negative refractive index and a second lens having a positive refractive index, an aperture stop, and a rear group including a third lens having a negative refractive index and a fourth lens having a positive refractive index.

Patent document 1: japanese unexamined patent publication No. 2007-279282

Patent document 2: japanese unexamined patent publication No. 2006-293042

Patent document 3: japanese unexamined patent publication No. 2007-322844

However, in the imaging lens described in patent document 1, since the front group is constituted by a spherical system, when the light is as bright as F2, correction of spherical aberration and coma aberration is insufficient, and good performance cannot be ensured. Since both the front group and the rear group have a positive refractive index, the principal point position of the optical system is on the image side and the back focus is longer than in the case of the electrophotographic type in which the rear group has a negative refractive index. Therefore, it is a type disadvantageous to miniaturization.

Further, the imaging lens described in patent document 2 has brightness of about F2, but since the first lens and the second lens disposed on the object side of the aperture stop have both positive refractive indexes, color correction in the former group is insufficient. Further, like the lens described in patent document 1, the front group and the rear group are both configured to have positive refractive indices, and the final lens is also a positive lens, and therefore, the lens is a type that is disadvantageous for miniaturization.

The imaging lens described in patent document 3 has brightness of about F2, but has a 4-lens structure, and therefore aberration correction is insufficient. Therefore, it is difficult to say that the imaging lens is suitable for high pixelation.

Disclosure of Invention

The present invention has been made in view of the above problems, and an object of the present invention is to provide a photographing lens having a bright 5-piece structure of about F2.0, which is smaller than a conventional type and in which various aberrations are corrected well.

To achieve the above object, the photographing lens of claim 1 is a photographing lens for forming a subject image on a photographing surface of an image pickup device, including, in order from an object side, an aperture stop, a positive first lens, a negative second lens, a third lens, a positive fourth lens, and a negative fifth lens, and satisfying the following conditional expressions (1) to (4):

0.8≦（r2F＋r2R）/（r2F－r2R）≦1.2...（1）

0.8≦（r4F＋r4R）/（r4F－r4R）≦1.6...（2）

－1.6≦f2/f≦－0.8...（3）

-0.212≦T5/f5≦-0.010...（4）

wherein,

r 2F: the radius of curvature of the object side of the second lens,

r 2R: the radius of curvature of the image-side surface of the second lens,

r 4F: the radius of curvature of the object side of the fourth lens,

r 4R: the radius of curvature of the image-side surface of the fourth lens,

f 2: the focal length of the second lens is such that,

f: the focal length of the whole system of the photographing lens,

t5: the thickness on the optical axis of the fifth lens,

f 5: focal length of the fifth lens.

The imaging lens according to claim 2 is characterized in that, in the above invention 1, the following conditional expression (5) is satisfied:

0.4≦f1/f≦0.8...（5）

wherein,

f 1: the focal length of the first lens is such that,

f: the focal length of the entire system of the photographing lens.

The imaging lens of claim 3 is characterized in that, in the above-described 1 st or 2 nd invention, the following conditional expression (6) is satisfied:

0.15≦T1/f≦0.28...（6）

wherein,

t1: the thickness on the optical axis of the first lens,

f: the focal length of the entire system of the photographing lens.

The imaging lens of claim 4 is characterized in that, in any one of the inventions 1 to 3, the image side surface of the fifth lens element has an aspherical shape with a concave surface facing the image side on the optical axis, and has an inflection point at a position other than an intersection point with the optical axis when a contour line of a lens cross section along the optical axis is directed from the intersection point with the optical axis to the effective area end.

An imaging optical apparatus according to claim 5 is characterized by comprising the imaging lens according to any one of the above 1 to 4 and an imaging device for converting an optical image formed on an imaging surface into an electric signal, wherein the imaging lens is provided so as to form an optical image of an object on the imaging surface of the imaging device.

The digital device according to claim 6 is provided with the imaging optical apparatus according to claim 5, and is characterized in that at least one of still image shooting and moving image shooting of the subject is added.

The digital device according to claim 7 is the digital device according to claim 6, wherein the digital device is a mobile terminal.

By adopting the configuration of the present invention, it is possible to realize a 5-lens configuration imaging lens and an imaging optical device including the imaging lens, which are smaller than conventional ones and have a bright F2.0 level in which various aberrations are corrected well. Further, by using the imaging optical device of the present invention for digital equipment such as a mobile phone and a portable information terminal, a high-performance image input function can be added to the digital equipment in a compact manner.

Drawings

FIG. 1 is an optical configuration diagram of a first embodiment (example 1);

FIG. 2 (A) to FIG. 2 (C) are aberration diagrams of example 1;

FIG. 3 is an optical configuration diagram of a second embodiment (example 2);

FIG. 4 (A) to FIG. 4 (C) are aberration diagrams of example 2;

FIG. 5 is an optical configuration diagram of a third embodiment (example 3);

FIG. 6 (A) to FIG. 6 (C) are aberration diagrams of example 3;

FIG. 7 is an optical configuration diagram of a fourth embodiment (example 4);

FIG. 8 (A) to FIG. 8 (C) are aberration diagrams of example 4;

FIG. 9 is an optical configuration diagram of a fifth embodiment (example 5);

FIG. 10 (A) to FIG. 10 (C) are aberration diagrams of example 5;

FIG. 11 is an optical configuration diagram of a sixth embodiment (example 6);

FIG. 12 (A) to FIG. 12 (C) are aberration diagrams of example 6;

fig. 13 is a schematic diagram showing a schematic configuration example of a digital device having a photographic lens mounted thereon.

Description of the marks

DU digital equipment

LU photographing optical device

LN (LN) shooting lens

L1-L5 first-fifth lenses

ST Aperture diaphragm (Aperture)

SR imaging device

SS light receiving surface (shooting surface)

IM image surface (optical image)

AX optical axis

1 Signal processing part

2 control part

3 memory

4 operating part

5 display part

Detailed Description

Next, the imaging lens and the like of the present invention will be described. The imaging lens of the present invention is an imaging lens for imaging a subject image on an imaging surface of an imaging element (for example, a photoelectric conversion unit of a solid-state imaging element), and is characterized by including, in order from an object side, an aperture stop, a positive first lens, a negative second lens, a third lens, a positive fourth lens, and a negative fifth lens, and satisfying the following conditional expressions (1) to (4).

0.8≦（r2F＋r2R）/（r2F－r2R）≦1.2...（1）

0.8≦（r4F＋r4R）/（r4F－r4R）≦1.6...（2）

－1.6≦f2/f≦－0.8...（3）

－0.212≦T5/f5≦－0.010...（4）

Wherein,

r 2F: the radius of curvature of the object side of the second lens,

r 2R: the radius of curvature of the image-side surface of the second lens,

r 4F: the radius of curvature of the object side of the fourth lens,

r 4R: the radius of curvature of the image-side surface of the fourth lens,

f 2: the focal length of the second lens is such that,

f: the focal length of the whole system of the photographing lens,

t5: the thickness on the optical axis of the fifth lens,

f 5: focal length of the fifth lens.

In order to obtain a small, bright, and aberration-corrected imaging lens, the basic configuration of the present invention is composed of an aperture stop, a positive first lens, a negative second lens, a third lens, a positive fourth lens, and a negative fifth lens. This lens structure is advantageous in downsizing the entire length of the imaging lens, because the lens structure is configured to have a so-called telematic arrangement in which a positive lens group including an aperture stop, a first lens, a second lens, a third lens, and a fourth lens, and a negative fifth lens are arranged in this order from the object side. In addition, by using at least 2 of the 5-piece structures as negative lenses, the number of surfaces having a divergent action increases, and correction of the petzval sum is easily performed. Therefore, a photographing lens ensuring good imaging performance up to the screen peripheral portion can be obtained. Further, by disposing the aperture stop on the object side of the first lens, the arrangement can easily ensure the telecentricity of the image-side light flux even if the height is reduced.

The conditional expression (1) is a conditional expression that specifies an optimum shape of the second lens for increasing the diameter of the second lens. When the corresponding value of conditional expression (1) is lower than the upper limit thereof, the radius of curvature of the image-side surface of the second lens is appropriately set, and therefore, high-order spherical aberration and coma aberration occurring in the image-side surface can be suppressed. On the other hand, when the corresponding value of conditional expression (1) exceeds the lower limit thereof, correction of coma, field curvature, astigmatism, chromatic aberration, and the like becomes easy.

The conditional expression (2) is a conditional expression that defines an optimal shape of the fourth lens for increasing the diameter. The fourth lens and the first lens both have positive power (power: amount defined by reciprocal of focal length), and play a large role in height reduction. When the corresponding value of conditional expression (2) is lower than the upper limit thereof, the radius of curvature of the object-side surface of the fourth lens can be prevented from being extremely increased, and thus high-order spherical aberration or coma aberration occurring on the object-side surface can be suppressed. On the other hand, since the radius of curvature of the object side surface of the fourth lens can be maintained as appropriate when the corresponding value of conditional expression (2) exceeds the lower limit thereof, the incident angle of the light beam toward the peripheral portion of the imaging element to the object side surface can be reduced, and coma aberration, distortion aberration, and the like can be suppressed.

The conditional expression (3) is a conditional expression for appropriately setting the focal length of the second lens. If the upper limit of the conditional expression (3) is exceeded, the negative power of the second lens is too strong, and coma cannot be completely corrected by the other lenses. In addition, when it is lower than the lower limit of the conditional expression (3), spherical aberration and axial chromatic aberration generated in the first lens cannot be sufficiently corrected.

The conditional expression (4) is a conditional expression for appropriately setting the thickness of the fifth lens. If the upper limit of the conditional expression (4) is exceeded, the correction of the distortion aberration is insufficient, and the advantage of the teletype cannot be exhibited, and it is difficult to achieve a lower height. Further, if the magnification is lower than the lower limit of conditional expression (4), the magnification of the peripheral portion of the fifth lens element cannot be increased, and therefore correction of field curvature is insufficient, and telecentricity of the image-side light flux is deteriorated, making it difficult to secure the peripheral light amount.

As apparent from the above description, according to the characteristic structure of the imaging lens of the present invention, it is possible to realize an imaging lens having a bright 5-piece structure of about F2.0, which is smaller in size and in which various aberrations are corrected well as compared with the conventional type, and an imaging optical device including the same. Further, if the imaging optical device is used for digital equipment such as a mobile phone and a portable information terminal, a high-performance image input function can be added to the digital equipment in a compact manner, which contributes to the compactness, high performance, high functionality, and the like. The following describes conditions and the like for achieving higher optical performance, miniaturization, and the like while obtaining such effects in a well-balanced manner.

With regard to downsizing, particularly, lowering of the height of the imaging lens, it is preferable that the imaging lens satisfies the following conditional expression (α 1). By satisfying the conditional expression (α 1), the imaging lens and the imaging optical device can be reduced in height and weight while ensuring the above-described excellent aberration performance and brightness. For example, in an imaging optical device mounted on a smartphone (high-performance mobile phone) or a tablet terminal, the conditional expression (α 1) is satisfied, and TL ≦ 5.0mm is preferably satisfied, and TL ≦ 4.5mm is more preferably satisfied.

TL/2Y’≦0.9...（α1）

Wherein,

TL: total lens length (distance on optical axis from lens surface closest to object side to focal point on image side in entire photographing lens system),

2Y': the length of the diagonal line of the imaging surface of the imaging element (for example, the length of the diagonal line of the rectangular effective pixel region of the solid-state imaging element).

More preferably, the following conditional expression (1 a) is satisfied.

0.8≦（r2F＋r2R）/（r2F－r2R）≦1.0...（1a）

Even if the conditional expression (1 a) specifies the condition range of the conditional expression (1), a more preferable condition range from the above viewpoint and the like is specified. Therefore, it is preferable that the effect can be further increased by satisfying the conditional expression (1 a).

More preferably, the following conditional expression (2 a) is satisfied.

1.0≦（r4F＋r4R）/（r4F－r4R）≦1.5...（2a）

Even if the conditional expression (2 a) specifies the condition range of the conditional expression (2), a more preferable condition range from the above viewpoint and the like is specified. Therefore, it is preferable that the effect can be further increased by satisfying the conditional expression (2 a).

More preferably, the following conditional expression (3 a) is satisfied.

－1.4≦f2/f≦－0.9...（3a）

Even if the conditional expression (3 a) specifies the condition range of the conditional expression (3), a more preferable condition range from the above viewpoint and the like is specified. Therefore, it is preferable that the effect can be further increased by satisfying the conditional expression (3 a).

More preferably, the following conditional expression (4 a) is satisfied.

－0.200≦T5/f5≦－0.010...（4a）

Even if the conditional expression (4 a) specifies the condition range of the conditional expression (4), a more preferable condition range from the above viewpoint and the like is specified. Therefore, it is preferable that the effect can be further increased by satisfying the conditional expression (4 a).

The following conditional expression (5) is preferably satisfied.

0.4≦f1/f≦0.8...（5）

Wherein,

f 1: the focal length of the first lens,

f: the focal length of the entire system of the photographing lens.

The conditional expression (5) is a conditional expression for appropriately setting the focal length of the first lens. If the upper limit of the conditional expression (5) is exceeded, convergence of the light flux is deteriorated, and therefore it is difficult to achieve a lower height and a larger diameter, and if the positive power of the fourth lens is increased to prevent this, it is difficult to suppress coma aberration and astigmatism this time. In addition, if it is lower than the lower limit of conditional expression (5), it is difficult to sufficiently correct spherical aberration and axial chromatic aberration generated at the first lens with other lenses.

More preferably, the following conditional expression (5 a) is satisfied.

0.5≦f1/f≦0.8...（5a）

Even if the conditional expression (5 a) specifies the condition range of the conditional expression (5), a more preferable condition range from the above viewpoint and the like is specified. Therefore, it is preferable that the effect can be further increased by satisfying the conditional expression (5 a).

The following conditional formula (6) is preferably satisfied.

0.15≦T1/f≦0.28...（6）

Wherein,

t1: a thickness on the optical axis of the first lens,

f: the focal length of the entire system of the photographing lens.

The conditional expression (6) is a conditional expression for appropriately setting the thickness of the first lens. If the upper limit of conditional expression (6) is exceeded, if a desired positive power is to be obtained in the first lens, the curvature of the object side surface becomes extremely strong, and it becomes difficult to suppress the occurrence of spherical aberration or coma aberration. If the magnification is less than the lower limit of conditional expression (6), the positive power required for lowering the height of the first lens cannot be sufficiently obtained, and therefore, the power of the fourth lens needs to be increased, which increases coma aberration and astigmatism.

More preferably, the following conditional expression (6 a) is satisfied.

0.16≦T1/f≦0.24...（6a）

Even if the conditional expression (6 a) specifies the condition range of the conditional expression (6), a more preferable condition range from the above viewpoint and the like is specified. Therefore, it is preferable that the effect can be further increased by satisfying the conditional expression (6 a).

The image side surface of the fifth lens has an aspherical shape with a concave surface facing the image side on the optical axis, and when the contour line of the lens cross section along the optical axis extends from the intersection point with the optical axis to the end of the effective region, it is preferable that the fifth lens has an inflection point (change point) at a position other than the intersection point with the optical axis. Here, the "inflection point" refers to a point on an aspheric surface where a tangent plane on the aspheric surface becomes a plane perpendicular to the optical axis in a curve of the lens cross-sectional shape within the effective radius. By setting the image side surface of the fifth lens to a desired aspherical shape having a concave surface reference having the above-described characteristics, distortion aberration can be corrected satisfactorily, and the telecentricity of the image side beam can be controlled satisfactorily from the vicinity of the optical axis over the entire screen area.

The lens is preferably formed entirely of a plastics material. That is, the photographing lens preferably has only a plastic lens as a lens. In recent years, for the purpose of downsizing the entire imaging optical apparatus including a solid-state imaging device, a device has been developed in which the pixel pitch is small and the imaging surface size is small even for a solid-state imaging device having the same number of pixels. In the imaging lens for such a solid-state imaging device having a small imaging surface size, the focal length of the entire system needs to be short, and therefore the radius of curvature and the outer diameter of each lens are considerably small. Therefore, all lenses can be constituted by plastic lenses manufactured by injection molding as compared with glass lenses manufactured by time-consuming grinding, and thus, even lenses having small curvature radii and outer diameters can be mass-produced at low cost. Further, since the pressing temperature of the plastic lens can be reduced, the loss of the molding die can be suppressed, and as a result, the number of times of replacement and maintenance of the molding die can be reduced, and cost reduction can be achieved.

The imaging lens of the present invention is suitable for use as an imaging lens for a digital device with an image input function (for example, a portable terminal), and can be combined with an imaging element or the like to constitute an imaging optical apparatus that optically acquires an image of a subject and outputs the image as an electric signal. The imaging optical device is an optical device formed as a main component element of a camera used for still image shooting and moving image shooting of an object, and is configured by, for example, sequentially providing an imaging lens forming an optical image of the object from the object (i.e., the object) side, and an imaging element converting the optical image formed by the imaging lens into an electrical signal. Further, by disposing the imaging lens having the above-described characteristic structure so that an optical image of the subject is formed on the light receiving surface (i.e., imaging surface) of the imaging element, it is possible to realize a small-sized, low-cost, and high-performance imaging optical device and a digital apparatus including the optical device.

Examples of the digital device with an image input function include cameras such as a digital camera, a video camera, a surveillance camera, a vehicle-mounted camera, and a camera for a television phone. Further, examples of the digital camera include devices having a camera function built in or externally attached to a personal computer, a portable digital device (for example, a small information device terminal such as a mobile phone, a smart phone, a tablet terminal, or a notebook computer), peripheral devices thereof (such as a scanner or a printer), and other digital devices. As can be seen from these examples, not only the camera can be configured by using the imaging optical device, but also a camera function can be added by mounting the imaging optical device in various devices. For example, a digital device with an image input function such as a camera-equipped mobile phone can be configured.

Fig. 13 shows a schematic configuration example of a digital device DU in a schematic cross section as an example of a digital device with an image input function. The imaging optical device LU mounted in the digital device DU shown in fig. 13 includes, in order from the object (i.e., subject) side: an imaging lens LN (AX: optical axis) for forming an optical image (image plane) IM of a subject, a parallel flat plate PT (a glass cover corresponding to the imaging element SR; an optical filter such as an optical low-pass filter or an infrared cut filter disposed as necessary), and the imaging element SR for converting the optical image IM formed on a light receiving surface (imaging plane) SS by the imaging lens LN into an electric signal. When the digital device DU with an image input function is constituted by the imaging optical device LU, the imaging optical device LU is usually disposed in the main body thereof, but when the camera function is realized, a method corresponding to the necessity may be adopted. For example, the unitized imaging optical device LU may be configured to be detachable from or rotatable with respect to the main body of the digital device DU.

As described above, the imaging lens LN has a fixed-focus 5-piece structure including the first to fifth lenses in order from the object side, and is configured to form the optical image IM on the light receiving surface SS of the imaging element SR. As the imaging element SR, for example, a solid-state imaging element such as a CCD type image sensor or a CMOS type image sensor having a plurality of pixels is used. Since the imaging lens LN is provided so as to form an optical image IM of an object on the light receiving surface SS, which is a photoelectric conversion portion of the imaging element SR, the optical image IM formed by the imaging lens LN is converted into an electric signal by the imaging element SR.

The digital device DU includes a signal processing unit 1, a control unit 2, a memory 3, an operation unit 4, a display unit 5, and the like in addition to the imaging optical device LU. The signal generated by the imaging element SR is subjected to predetermined digital image processing, image compression processing, and the like in the signal processing section 1 as necessary, and is recorded in the memory 3 (semiconductor memory, optical disk, and the like) as a digital video signal, or is transmitted to another device (for example, a communication function of a mobile phone) via a cable, an infrared signal, or the like as the case may be. The control unit 2 is composed of a microcomputer, and performs centralized control of functions such as a photographing function (a still image photographing function, a moving image photographing function, and the like) and an image reproducing function; control of a lens moving mechanism for focusing, and the like. For example, the control unit 2 controls the imaging optical device LU so as to perform at least one of still image shooting and moving image shooting of the subject. The display unit 5 is a portion including a display such as a liquid crystal monitor, and displays an image using the image signal converted by the imaging element SR or the image information recorded in the memory 3. The operation unit 4 is a part including operation members such as an operation button (for example, a shutter button) and an operation panel (for example, a shooting mode panel), and transmits information input by an operation of an operator to the control unit 2.

Next, specific optical configurations of the imaging lens LN will be described in more detail with reference to the first to sixth embodiments. Fig. 1, 3, 5, 7, 9, and 11 show first to sixth embodiments of an imaging lens LN in an infinity focusing state in an optical cross section. The j-th lens Lj is a lens located j-th from the object side, and the parallel plate PT disposed on the image side of the imaging lens LN is a plate assuming an optical low-pass filter, an IR cut filter, a seal glass of a solid-state imaging element, or the like. All lens surfaces constituting the photographing lens LN are aspherical surfaces, and all lenses are assumed to be made of a plastic material as an optical material. Further, it is assumed that the first lens L1 to the fifth lens L5 are moved integrally to perform overall focusing such as focusing by an auto-focusing function and a macro switching function.

In the photographing lens LN of the first to sixth embodiments, an aperture stop ST, a positive first lens L1, a negative second lens L2, a positive or negative third lens L3, a positive fourth lens L4, and a negative fifth lens L5 are arranged in this order from the object side. The convex surface of the first lens L1 faces the object side, and the concave surface of the second lens L2 faces the image side. The image side surface of the fifth lens is an aspherical surface having an inflection point at a position other than the intersection with the optical axis AX.

However, since a refractive index of a plastic material changes greatly when the temperature changes, if all the lenses are made of plastic lenses, there is a problem that the position of an image point of the entire imaging lens system changes when the ambient temperature changes. However, recently, it has been found that if inorganic fine particles are mixed in a plastic material, the influence of temperature change to which the plastic material is subjected can be reduced. In detail, generally, if fine particles are mixed in a transparent plastic material, light is scattered, and the transmittance is lowered, so that it is difficult to use the transparent plastic material as an optical material.

In addition, although the refractive index of the plastic material decreases as the temperature increases, the refractive index of the inorganic particles increases as the temperature increases. Therefore, by acting in such a manner as to cancel each other by utilizing these temperature dependencies, a refractive index change can be hardly generated. Specifically, a plastic material having extremely low temperature dependence of refractive index can be obtained by dispersing inorganic particles having a maximum length of 20 nm or less in a plastic material serving as a base material. For example by dispersing niobium oxide (Nb) in acrylic resin₂O₅) The fine particles of (2) can reduce a change in refractive index due to a change in temperature.

In the imaging lens LN of the present invention, the plastic material in which such inorganic particles are dispersed is used for the positive lens (for example, the first lens L1 and the fourth lens L4) or all the lenses (the first to fifth lenses L1 to L5) having a large refractive index, and thus, the variation in the position of the image point when the temperature of the entire imaging lens LN changes can be suppressed to be small.

In the embodiments described above and in the embodiments described below, the chief ray incident angle of the light beam incident on the imaging surface of the solid-state imaging device is not necessarily designed to be very small in the periphery of the imaging surface. However, in recent technologies, light shielding can be reduced by newly investigating the arrangement of a color filter and an on chip (microchip) microlens array of a solid-state imaging device. Specifically, if the pitch of the color filter and the integrated chip microlens array is set to be slightly smaller with respect to the pixel pitch of the imaging surface of the imaging element, the color filter and the integrated chip microlens array are displaced toward the optical axis of the imaging lens with respect to each pixel in the peripheral portion of the imaging surface, and therefore, the obliquely incident light beam can be efficiently introduced into the light receiving portion of each pixel. This can suppress light shielding generated in the solid-state imaging device to be small. In each of the embodiments described later, the above-described requirements are relaxed, and a design example of further downsizing is directed.

[ examples ] A method for producing a compound

Next, the configuration of the imaging lens according to the present invention will be described in more detail by referring to configuration data of the embodiment. Examples 1 to 6 (EX 1 to 6) illustrated herein are numerical examples corresponding to the first to sixth embodiments described above, and optical configuration diagrams (fig. 1, 3, 5, 7, 9, and 11) showing the first to sixth embodiments respectively show the lens structures of examples 1 to 6.

In the configuration data of each example, the surface number, the radius of curvature r (mm), the axial upper surface interval d (mm), the refractive index nd on the d-line (wavelength: 587.56 nm), and the Abbe number vd on the d-line are shown in order from the left column as surface data. The surface denoted by the reference numeral is an aspherical surface, and the surface shape is defined by the following expression (AS) using a local orthogonal coordinate system (X, Y, Z) with the surface vertex AS the origin. As aspherical data, representAspheric coefficients, etc. Note that the coefficient of an item not described in the aspherical surface data of each example is 0, and all the data are E-n ═ x 10^-n。

[ number 1 ]

Wherein,

h: height (h) in a direction perpendicular to the X-axis (optical axis AX)²＝Y²＋Z²）、

X: a sag (surface apex reference) in the optical axis AX direction at a position of the height h,

R: a reference radius of curvature (corresponding to radius of curvature r),

K: a conic constant,

Ai: aspheric coefficients of order i.

The various data are the focal lengths (F, mm) of the entire imaging lens system, the back focal points (fB, mm), the F number (F), the diagonal lengths (2Y ', mm; Y ' is the maximum image height) of the imaging surface SS of the imaging element SR, the total lens lengths (TL, mm), the half-picture angles (omega, °), and the corresponding values (TL/2Y ') of the conditional expression (alpha 1), and the focal lengths (mm) of the respective lenses are shown as single lens data. However, the back focus fB used here is a distance from the image side surface of the parallel flat plate PT to the image plane IM, and the total lens length TL is a distance from the foremost lens surface to the image plane IM. Table 1 shows the values corresponding to the conditional expressions in the examples.

Fig. 2, 4, 6, 8, 10, and 12 are aberration diagrams of examples 1 to 6 (EX 1 to 6), where (a) represents spherical aberration (mm), (B) represents astigmatism (mm), and (C) represents distortion aberration (%). In the spherical aberration diagram (a), the solid line indicates the amount of spherical aberration from the d-line (wavelength 587.56 nm) by the amount of deviation from the paraxial image plane in the direction of the optical axis AX, the broken line indicates the amount of spherical aberration from the g-line (wavelength 435.84 nm) by the amount of deviation from the paraxial image plane in the direction of the optical axis AX, the alternate long and short dashed line indicates the amount of spherical aberration from the c-line (wavelength 656.28 nm) by the amount of deviation from the paraxial image plane in the direction of the optical axis AX, and the vertical axis indicates the F value. In the astigmatism diagram (B), the broken line M represents a meridional image plane with respect to the d-line by the amount of deviation in the direction of the optical axis AX from the paraxial image plane, the solid line S represents a vertical-line image plane with respect to the d-line by the amount of deviation in the direction of the optical axis AX from the paraxial image plane, and the vertical axis represents the image height Y' (mm). In the distorted aberration diagram (C), the horizontal axis represents distortion with respect to the d-line, and the vertical axis represents the image height Y' (mm). The maximum image height Y' corresponds to half of the length of the diagonal line of the imaging surface SS of the imaging element SR.

The photographing lens LN of embodiment 1 (fig. 1) is composed of, in order from the object side, an aperture stop ST, a positive first lens L1, a negative second lens L2, a positive third lens L3, a positive fourth lens L4, and a negative fifth lens L5, all of which are formed of a plastic material, and whose lens surfaces are aspherical surfaces. When each lens is viewed in a paraxial surface shape, the first lens L1 is a biconvex positive lens, the second lens L2 is a biconcave negative lens, the third lens L3 is a convex positive plano-convex lens on the object side, the fourth lens L4 is a convex positive meniscus lens on the image side, and the fifth lens L5 is a biconcave negative lens. A filter (e.g., an optical low-pass filter or an IR cut filter), a parallel flat plate PT such as a seal glass of a solid-state imaging element, or the like is disposed on the image side of the imaging lens LN.

A photographing lens LN (fig. 3) of embodiment 2 is composed of, in order from the object side, an aperture stop ST, a positive first lens L1, a negative second lens L2, a positive third lens L3, a positive fourth lens L4, and a negative fifth lens L5, all of which are formed of a plastic material, and whose lens surfaces are aspherical surfaces. When each lens is viewed in a paraxial surface shape, the first lens L1 is a biconvex positive lens, the second lens L2 is a biconcave negative lens, the third lens L3 is a convex positive plano-convex lens on the object side, the fourth lens L4 is a convex positive meniscus lens on the image side, and the fifth lens L5 is a biconcave negative lens. A filter (e.g., an optical low-pass filter or an IR cut filter), a parallel flat plate PT such as a seal glass of a solid-state imaging element, or the like is disposed on the image side of the imaging lens LN.

A photographing lens LN (fig. 5) of embodiment 3 is composed of, in order from the object side, an aperture stop ST, a positive first lens L1, a negative second lens L2, a positive third lens L3, a positive fourth lens L4, and a negative fifth lens L5, all of which are formed of a plastic material, and whose lens surfaces are aspherical surfaces. When each lens is viewed in a paraxial surface shape, the first lens L1 is a biconvex positive lens, the second lens L2 is a biconcave negative lens, the third lens L3 is a convex positive plano-convex lens on the object side, the fourth lens L4 is a convex positive meniscus lens on the image side, and the fifth lens L5 is a biconcave negative lens. A filter (e.g., an optical low-pass filter or an IR cut filter), a parallel flat plate PT such as a seal glass of a solid-state imaging element, or the like is disposed on the image side of the imaging lens LN.

A photographing lens LN (fig. 7) of embodiment 4 is composed of, in order from the object side, an aperture stop ST, a positive first lens L1, a negative second lens L2, a negative third lens L3, a positive fourth lens L4, and a negative fifth lens L5, all of which are formed of a plastic material, and whose lens surfaces are aspherical surfaces. When each lens is viewed in a paraxial surface shape, the first lens L1 is a biconvex positive lens, the second lens L2 is a biconcave negative lens, the third lens L3 is a concave negative meniscus lens on the image side, the fourth lens L4 is a convex positive meniscus lens on the image side, and the fifth lens L5 is a biconcave negative lens. A filter (e.g., an optical low-pass filter or an IR cut filter), a parallel flat plate PT such as a seal glass of a solid-state imaging element, or the like is disposed on the image side of the imaging lens LN.

A photographing lens LN (fig. 9) of embodiment 5 is composed of, in order from the object side, an aperture stop ST, a positive first lens L1, a negative second lens L2, a positive third lens L3, a positive fourth lens L4, and a negative fifth lens L5, all of which are formed of a plastic material, and whose lens surfaces are aspherical surfaces. When each lens is viewed in a paraxial surface shape, the first lens L1 is a biconvex positive lens, the second lens L2 is a biconcave negative lens, the third lens L3 is a convex positive plano-convex lens on the object side, the fourth lens L4 is a convex positive meniscus lens on the image side, and the fifth lens L5 is a biconcave negative lens. A filter (e.g., an optical low-pass filter or an IR cut filter), a parallel flat plate PT such as a seal glass of a solid-state imaging element, or the like is disposed on the image side of the imaging lens LN.

A photographing lens LN (fig. 11) of embodiment 6 is composed of, in order from the object side, an aperture stop ST, a positive first lens L1, a negative second lens L2, a positive third lens L3, a positive fourth lens L4, and a negative fifth lens L5, all of which are formed of a plastic material, and whose lens surfaces are aspherical surfaces. When each lens is viewed in a paraxial surface shape, the first lens L1 is a biconvex positive lens, the second lens L2 is a concave negative meniscus lens on the image side, the third lens L3 is a convex positive plano-convex lens on the object side, the fourth lens L4 is a convex positive meniscus lens on the image side, and the fifth lens L5 is a biconcave negative lens. A filter (e.g., an optical low-pass filter or an IR cut filter), a parallel flat plate PT such as a seal glass of a solid-state imaging element, or the like is disposed on the image side of the imaging lens LN.

Example 1

Unit: mm is

Surface data

Aspheric data

Second surface

K=0.73738E+00

A4=－0.23195E－01

A6=－0.19578E－01

A8=0.29831E－01

A10=－0.91606E－01

A12=0.89175E－01

A14=－0.51475E－01

Third side

K=－0.88673E+02

A4=0.20661E－01

A6=0.96030E－01

A8=－0.18244E+00

A10=-0.11672E-02

A12=0.46941E-01

A14=0.10608E-01

Fourth surface

K=0.21528E+02

A4=0.10799E－01

A6=0.17926E+00

A8=－0.24119E+00

A10=－0.83162E－01

A12=0.19900E+00

A14=－0.30968E－01

Fifth surface

K=－0.31344E+02

A4=0.15544E+00

A6=－0.67883E－01

A8=0.73401E－01

A10=－0.42046E－02

A12=－0.81554E－01

A14=0.84143E－01

Sixth surface

K=－0.78894E+02

A3=－0.41274E－01

A4=0.28108E－01

A5=－0.18551E+00

A6=0.79822E－01

A7=0.12609E+00

A8=－0.73527E－01

A10=－0.66279E－01

A12=0.11943E+00

A14=－0.53716E－01

Seventh aspect of the invention

K=0.00000E+00

A4=-0.85797E-01

A6=0.54167E-01

A8=－0.55051E－01

A10=0.31289E－01

A12=0.82636E－02

A14=－0.59250E－02

Eighth aspect of the invention

K=0.14976E+02

A3=0.34873E－01

A4=－0.63497E－01

A5=－0.63073E－02

A6=0.73208E－01

A7=－0.12114E－02

A8=－0.31550E－01

A10=－0.92739E－02

A12=0.11271E－01

A14=－0.30433E－02

Ninth surface

K=－0.41827E+01

A4=－0.79722E－01

A6=0.74067E－01

A8=－0.24708E－01

A10=0.41068E－02

A12=－0.10678E－02

A14=0.12695E－03

The tenth side

K=0.21670E+02

A3=－0.17800E+00

A4=0.38445E－01

A5=0.89935E－02

A6=-0.17622E-02

A7=0.64112E-03

A8=0.43367E-03

A10=－0.13239E－04

A12=－0.21143E－04

A14=0.19746E－05

The eleventh aspect

K=－0.70403E+01

A3=－0.92091E－01

A4=0.10464E－01

A5=－0.55640E－02

A6=0.53312E－02

A7=0.11416E－03

A8=－0.12349E－02

A10=0.10165E－03

A12=－0.11113E－04

A14=0.14035E－05

Various data

f=3.68mm

fB=0.45mm

F=2

2Y'=5.842mm

TL=4.55mm

ω=37.4°

TL/2Y′＝0.779

Single lens data

Example 2

Unit: mm is

Surface data

Aspheric data

Second surface

K=0.76542E+00

A4=－0.24741E－01

A6=－0.20949E－01

A8=0.29684E－01

A10=－0.91561E－01

A12=0.87919E－01

A14=－0.48846E－01

Third side

K=－0.90001E+02

A4=0.17985E－01

A6=0.90968E－01

A8=-0.17974E+00

A10=-0.50235E-03

A12=0.48086E-01

A14=0.97721E－02

Fourth surface

K=－0.73275E+02

A3=－0.27688E－01

A4=0.75232E－01

A5=－0.81489E－01

A6=0.20402E+00

A7=0.40040E－01

A8=－0.29621E+00

A10=－0.25453E－01

A12=0.14178E+00

A14=－0.84773E－02

Fifth surface

K=－0.85565E+01

A3=－0.23039E－01

A4=0.64454E－01

A5=－0.10977E－02

A6=0.16234E+00

A7=－0.44305E－02

A8=－0.32037E+00

A10=0.45766E+00

A12=－0.40242E+00

A14=0.17712E+00

Sixth surface

K=0.90000E+02

A3=－0.47053E－01

A4=0.43389E－01

A5=－0.20750E+00

A6=0.80022E-01

A7=0.12820E+00

A8=-0.63718E-01

A10=－0.64954E－01

A12=0.11357E+00

A14=－0.54054E－01

Seventh aspect of the invention

K=0.00000E+00

A4=－0.86795E－01

A6=0.42711E－01

A8=－0.46117E－01

A10=0.31680E－01

A12=0.78676E－02

A14=－0.67256E－02

Eighth aspect of the invention

K=0.13035E+02

A3=0.44370E－01

A4=－0.72759E－01

A5=0.10151E－01

A6=0.72236E－01

A7=－0.39159E－02

A8=－0.32565E－01

A10=－0.78458E－02

A12=0.11949E－01

A14=－0.35819E－02

Ninth surface

K=－0.42106E+01

A4=－0.79786E－01

A6=0.80881E－01

A8=－0.24859E－01

A10=0.32460E－02

A12=-0.11706E-02

A14=0.18291E-03

The tenth side

K=0.89619E+02

A3=－0.17088E+00

A4=0.38075E－01

A5=0.76978E－02

A6=－0.20400E－02

A7=0.62360E－03

A8=0.54927E－03

A10=－0.96481E－05

A12=－0.21813E－04

A14=0.18696E－05

The eleventh aspect

K=－0.70569E+01

A3=－0.91431E－01

A4=0.11947E－01

A5=－0.51300E－02

A6=0.46480E－02

A7=－0.62277E－04

A8=－0.11926E－02

A10=0.11361E－03

A12=－0.13079E－04

A14=0.16715E－05

Various data

f=3.70mm

fB=0.45mm

F=2

2Y'=5.867mm

TL=4.55mm

ω=37.3°

TL/2Y′＝0.776

Single lens data

Example 3

Unit: mm is

Surface data

Aspheric data

Second surface

K=0.36289E+00

A4=－0.17322E－01

A6=0.16655E－01

A8=－0.27227E－01

A10=-0.62734E-01

A12=0.14361E+00

A14=-0.91396E-01

Third side

K=－0.90000E+02

A4=－0.39662E－02

A6=0.13781E+00

A8=－0.22259E+00

A10=0.12637E－01

A12=0.68653E－01

A14=－0.37730E－01

Fourth surface

K=0.90000E+02

A4=0.19383E－01

A6=0.17599E+00

A8=－0.21941E+00

A10=－0.10578E+00

A12=0.19185E+00

A14=－0.61220E－01

Fifth surface

K=－0.35312E+02

A4=0.17285E+00

A6=－0.37830E－01

A8=0.63078E－01

A10=－0.23538E－01

A12=－0.57601E－01

A14=0.79998E－01

Sixth surface

K=0.90000E+02

A3=－0.62474E－01

A4=－0.13327E－02

A5=-0.13676E+00

A6=0.49613E-01

A7=0.74428E-01

A8=－0.70631E－01

A10=－0.28274E－02

A12=0.10937E+00

A14=－0.74823E－01

Seventh aspect of the invention

K=0.00000E+00

A4=－0.14874E+00

A6=0.76527E－01

A8=－0.67515E－01

A10=0.27299E－01

A12=0.23732E－01

A14=－0.13708E－01

Eighth aspect of the invention

K=－0.55383E+02

A4=－0.11454E+00

A6=0.62472E－01

A8=－0.21548E－01

A10=－0.23122E－02

A12=0.68054E－02

A14=－0.28866E－02

Ninth surface

K=－0.34054E+01

A4=－0.88460E－01

A6=0.51775E－01

A8=－0.96636E－03

A10=0.19711E－02

A12=－0.39586E－02

A14=0.76364E－03

The tenth side

K=-0.22967E+01

A4=0.28928E-01

A6=－0.48352E－02

A8=0.55647E－03

A10=0.60531E－04

A12=－0.18633E－04

A14=0.11412E－05

The eleventh aspect

K=－0.17978E+02

A4=－0.83226E+00

A6=0.37675E－01

A8=0.21288E－02

A10=0.90556E－02

A12=0.94940E－04

A14=0.17570E－04

Various data

f=3.67mm

fB=0.45mm

F=1.9

2Y'=5.867mm

TL=4.55mm

ω=37.3°

TL/2Y′＝0.776

Single lens data

Example 4

Unit: mm is

Surface data

Aspheric data

Second surface

K=0.33674E+00

A4=－0.17733E－01

A6=0.15840E－01

A8=－0.29978E－01

A10=－0.63238E－01

A12=0.14385E+00

A14=－0.95794E－01

Third side

K=0.37461E+02

A4=－0.42011E－02

A6=0.13715E+00

A8=－0.22216E+00

A10=0.14550E-01

A12=0.71162E-01

A14=-0.33228E-01

Fourth surface

K=－0.90000E+02

A4=0.29951E－01

A6=0.18411E+00

A8=－0.21374E+00

A10=－0.10252E+00

A12=0.19702E+00

A14=－0.52139E－01

Fifth surface

K=－0.39888E+02

A4=0.18399E+00

A6=－0.34234E－01

A8=0.60822E－01

A10=－0.13810E－01

A12=－0.38486E－01

A14=0.79998E－01

Sixth surface

K=0.90000E+02

A3=－0.58359E－01

A4=－0.30616E－01

A5=－0.11680E+00

A6=0.53316E－01

A7=0.64245E－01

A8=－0.80561E－01

A10=0.10711E－02

A12=0.11028E+00

A14=－0.76128E－01

Seventh aspect of the invention

K=0.00000E+00

A4=-0.14684E+00

A6=0.83204E-01

A8=－0.65893E－01

A10=0.22765E－01

A12=0.22175E－01

A14=－0.11905E－01

Eighth aspect of the invention

K=－0.68240E+02

A4=－0.11455E+00

A6=0.64854E－01

A8=－0.20558E－01

A10=－0.29174E－02

A12=0.58903E－02

A14=－0.24409E－02

Ninth surface

K=－0.32836E+01

A4=－0.93014E－01

A6=0.45925E－01

A8=0.17897E－03

A10=0.28849E－02

A12=－0.39190E－02

A14=0.64414E－03

The tenth side

K=－0.25363E+01

A4=0.25181E－01

A6=－0.49877E－02

A8=0.60469E－03

A10=0.65707E－04

A12=－0.18467E－04

A14=0.10291E－05

The eleventh aspect

K=-0.18004E+02

A4=-0.33311E-01

A6=0.66857E－02

A8=－0.14313E－02

A10=0.11540E－03

A12=－0.11084E－05

A14=0.94421E－07

Various data

f=3.66mm

fB=0.45mm

F=1.9

2Y'=5.867mm

TL=4.53mm

ω=37.6°

TL/2Y′＝0.772

Single lens data

Example 5

Unit: mm is

Surface data

Aspheric data

Second surface

K=0.74153E+00

A4=－0.24204E－01

A6=－0.19768E－01

A8=0.29285E－01

A10=－0.90081E－01

A12=0.87245E－01

A14=－0.49909E－01

Third side

K=－0.78010E+02

A4=0.19474E－01

A6=0.94270E－01

A8=－0.18031E+00

A10=－0.16043E－02

A12=0.47373E－01

A14=0.99755E－02

Fourth surface

K=－0.90000E+02

A4=0.90791E－02

A6=0.17611E+00

A8=－0.23815E+00

A10=-0.81703E-01

A12=0.19480E+00

A14=-0.30000E-01

Fifth surface

K=－0.29786E+02

A4=0.15575E+00

A6=－0.68478E－01

A8=0.69745E－01

A10=－0.51907E－02

A12=－0.80841E－01

A14=0.81258E－01

Sixth surface

K=0.90000E+02

A3=－0.42536E－01

A4=0.36743E－01

A5=－0.19388E+00

A6=0.78760E－01

A7=0.12311E+00

A8=－0.68845E－01

A10=－0.62217E－01

A12=0.11445E+00

A14=－0.54920E－01

Seventh aspect of the invention

K=0.00000E+00

A4=－0.83995E－01

A6=0.47298E－01

A8=－0.50543E－01

A10=0.32305E－01

A12=0.82350E－02

A14=－0.68592E－02

Eighth aspect of the invention

K=0.17517E+02

A3=0.32512E-01

A4=-0.61123E-01

A5=－0.70964E－02

A6=0.76368E－01

A7=－0.23964E－02

A8=－0.32484E－01

A10=－0.76448E－02

A12=0.11083E－01

A14=－0.31857E－02

Ninth surface

K=－0.42421E+01

A4=－0.79276E－01

A6=0.74501E－01

A8=－0.24351E－01

A10=0.39327E－02

A12=－0.10544E－02

A14=0.11876E－03

The tenth side

K=0.33071E+02

A3=－0.17066E+00

A4=0.38973E－01

A5=0.77206E－02

A6=－0.21364E－02

A7=0.58901E－03

A8=0.54576E－03

A10=－0.82460E－05

A12=－0.21300E－04

A14=0.18019E－05

The eleventh aspect

K=－0.71220E+01

A3=-0.91282E-01

A4=0.11508E-01

A5=-0.50750E-02

A6=0.46791E－02

A7=－0.17433E－04

A8=－0.11868E－02

A10=0.11681E－03

A12=－0.12854E－04

A14=0.14995E－05

Various data

f=3.70mm

fB=0.45mm

F=2

2Y'=5.867mm

TL=4.55mm

ω=37.4°

TL/2Y′＝0.776

Single lens data

Example 6

Unit: mm is

Surface data

Aspheric data

Second surface

K=0.86517E+00

A3=－0.13314E－02

A4=－0.19305E－01

A5=－0.25214E－02

A6=－0.19822E－01

A7=0.17350E－02

A8=0.32303E－01

A10=－0.93007E－01

A12=0.85296E－01

A14=－0.39687E－01

Third side

K=－0.90000E+02

A4=0.40858E－01

A6=0.73150E－01

A8=－0.18654E+00

A10=0.17233E－02

A12=0.55018E－01

A14=0.32962E－01

Fourth surface

K=-0.89853E+02

A3=-0.37858E-01

A4=0.53275E-01

A5=－0.92884E－01

A6=0.20070E+00

A7=0.36080E－01

A8=－0.30347E+00

A10=－0.32372E－01

A12=0.14649E+00

A14=0.10248E－01

Fifth surface

K=－0.11153E+02

A3=－0.18124E－01

A4=0.60877E－01

A5=－0.42686E－02

A6=0.15302E+00

A7=－0.14624E－01

A8=－0.32432E+00

A10=0.46890E+00

A12=－0.39333E+00

A14=0.17111E+00

Sixth surface

K=0.90000E+02

A3=－0.47053E－01

A4=0.43389E－01

A5=－0.20750E+00

A6=0.80022E－01

A7=0.12820E+00

A8=－0.63718E－01

A10=－0.64954E－01

A12=0.11357E+00

A14=-0.54054E-01

Seventh aspect of the invention

K=0.00000E+00

A4=－0.86795E－01

A6=0.42711E－01

A8=－0.46117E－01

A10=0.31680E－01

A12=0.78676E－02

A14=－0.67256E－02

Eighth aspect of the invention

K=0.13035E+02

A3=0.44370E－01

A4=－0.72759E－01

A5=0.10151E－01

A6=0.72236E－01

A7=－0.39159E－02

A8=－0.32565E－01

A10=－0.78458E－02

A12=0.11949E－01

A14=－0.35819E－02

Ninth surface

K=－0.42106E+01

A4=－0.79786E－01

A6=0.80881E－01

A8=－0.24859E－01

A10=0.32460E－02

A12=－0.11706E－02

A14=0.18291E－03

The tenth side

K=－0.67491E+00

A3=－0.15527E+00

A4=0.32102E-01

A5=0.79147E-02

A6=-0.18503E-02

A7=0.79580E－03

A8=0.58211E－03

A10=－0.89952E－05

A12=－0.24066E－04

A14=0.19782E－05

The eleventh aspect

K=－0.76364E+01

A3=－0.84595E－01

A4=0.74896E－02

A5=－0.64723E－02

A6=0.55090E－02

A7=－0.53477E－04

A8=－0.11827E－02

A10=0.11185E－03

A12=－0.14550E－04

A14=0.21714E－05

Various data

f=3.90mm

fB=0.45mm

F=2.2

2Y'=5.867mm

TL=4.79mm

ω=35.5°

TL/2Y′＝0.816

Single lens data

[ TABLE 1 ]

Claims

1. A photographing lens for forming an object image on a photographing surface of a photographing element, comprising, in order from an object side, an aperture stop, a positive first lens, a negative second lens, a third lens, a positive fourth lens, and a negative fifth lens, and satisfying the following conditional expressions (1) to (4):

0.8≦（r2F＋r2R）/（r2F－r2R）≦1.2…（1）

0.8≦（r4F＋r4R）/（r4F－r4R）≦1.6…（2）

－1.6≦f2/f≦－0.8…（3）

－0.212≦T5/f5≦－0.010…（4）

wherein,

r 2F: the radius of curvature of the object side of the second lens,

r 2R: the radius of curvature of the image-side surface of the second lens,

r 4F: the radius of curvature of the object side of the fourth lens,

r 4R: the radius of curvature of the image-side surface of the fourth lens,

f 2: the focal length of the second lens is such that,

f: the focal length of the whole system of the photographing lens,

t5: the thickness on the optical axis of the fifth lens,

f 5: focal length of the fifth lens.

2. The photographing lens according to claim 1,

the following conditional formula (5) is satisfied:

0.4≦f1/f≦0.8…（5）

wherein,

f 1: the focal length of the first lens is such that,

f: the focal length of the entire system of the photographing lens.

3. Photographing lens according to claim 1 or 2,

the following conditional formula (6) is satisfied:

0.15≦T1/f≦0.28…（6）

wherein,

t1: the thickness on the optical axis of the first lens,

f: the focal length of the entire system of the photographing lens.

4. The photographing lens according to any one of claims 1 to 3,

the image side surface of the fifth lens element has an aspherical shape with a concave surface facing the image side on the optical axis, and has an inflection point at a position other than an intersection point with the optical axis when the effective area end is located from the intersection point with the optical axis on a contour line of a lens cross section along the optical axis.

5. A photographing optical device is characterized in that,

the imaging lens according to any one of claims 1 to 4, and an imaging device for converting an optical image formed on an imaging surface into an electric signal, wherein the imaging lens is provided so that an optical image of a subject is formed on the imaging surface of the imaging device.

6. A digital device, characterized in that,

the imaging optical apparatus according to claim 5 is provided with at least one of the functions of still image imaging and moving image imaging of the subject.

7. The digital device of claim 6,

the digital device is a portable terminal.