JP2017156570A - Imaging lens, camera device, and sensing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact imaging lens that has a wide view angle, a small F-number, and high performance.SOLUTION: The imaging lens comprises, in order from the object side, a first lens L1 having negative refractive power, a second lens L2 having negative refractive power, a third lens L3 having positive refractive power, an aperture stop S, a fourth lens L4 having positive refractive power, a fifth lens L5 having negative refractive power, and a sixth lens L6 having positive refractive power. The first lens L1 has object-side and image-side surfaces that are both concave. The second lens L2 has a concave surface on the object side, and is configured in such a way that a curvature radius of the object-side surface is greater than that of an image-side surface in absolute terms. The third lens L3 has a convex surface on the image side, and is configured in such a way that an absolute value of a curvature radius of the image-side surface is greater than that of an object-side surface. The image-side surface of the second lens L2 and the object-side surface of the third lens L3 are cemented together.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging lens, a camera device, and a sensing device.

  There is a demand for miniaturization of a camera device and an imaging lens used therefor, in particular, miniaturization of a lens (front lens) closest to the object side of the imaging lens. In addition, an imaging lens used in such a camera device or the like is desired to have a wide angle of view, a small F number, and a high resolution.

  As an imaging lens for the purpose of downsizing and widening the angle of view, in order from the object side, a first lens having a negative refractive power, a second lens having a negative refractive index, and a third lens having a positive refractive power A fourth lens having a positive refractive power, a fifth lens having a negative refractive power, and a sixth lens having a positive refractive power, and both the object side and the image side of the first lens are concave surfaces, A retrofocus type lens in which the second lens has a concave surface facing the object side and the third lens has a convex surface facing the image side is disclosed (for example, see Patent Documents 1 to 3).

  However, in a retrofocus type lens, a lens having a negative refractive power disposed on the object side tends to be enlarged, and there is room for improvement in terms of a reduction in diameter. Patent Document 3 discloses a wide-angle imaging lens in which the diameter of the front lens is reduced by disposing an aperture stop relatively in front of the imaging lens. However, it is difficult to correct various aberrations as a side effect of downsizing the front lens. In addition, although it has a wide angle of view, the F number is as large as around 7, and there is room for improvement in terms of a large aperture.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a compact and high-performance imaging lens having a wide angle of view, a small F number.

  In order to achieve the above object, an imaging lens according to the present application includes, in order from the object side, a first lens having a negative refractive power, a second lens having a negative refractive index, and a third lens having a positive refractive power. A fourth lens having a positive refractive power, a fifth lens having a negative refractive power, and a sixth lens having a positive refractive power, and an aperture stop between the third lens and the fourth lens. The first lens has a concave surface on both the object side surface and the image side surface, and the second lens has a concave surface facing the object side, and the absolute value of the curvature of the object side surface is the absolute value of the curvature of the image side surface. The third lens has a convex surface facing the image side, and the absolute value of the curvature of the image side surface is greater than the absolute value of the curvature of the object side surface. The object side surfaces of the lens are bonded to each other.

  According to the present invention, it is possible to provide a compact and high-performance imaging lens having a wide angle of view, a small F number.

It is an optical arrangement | positioning figure which shows the lens structure of the imaging lens which concerns on Example 1 of this invention. It is an optical arrangement | positioning figure which shows the lens structure of the imaging lens which concerns on Example 2 of this invention. It is an optical arrangement | positioning figure which shows the lens structure of the imaging lens which concerns on Example 3 of this invention. It is an optical arrangement | positioning figure which shows the lens structure of the imaging lens which concerns on Example 4 of this invention. It is an optical arrangement | positioning figure which shows the lens structure of the imaging lens which concerns on Example 5 of this invention. FIG. 3 is an aberration curve diagram of the imaging lens according to Example 1 of the present invention. The thick line indicates the aberration with respect to the d line, and the thin line indicates the aberration with respect to the g line. The solid line in the astigmatism curve diagram indicates sagittal aberration, and the broken line indicates meridional aberration (the same applies to the following aberration diagrams). It is an aberration curve figure of the imaging lens which concerns on Example 2 of this invention. It is an aberration curve figure of the imaging lens which concerns on Example 3 of this invention. It is an aberration curve figure of the image formation lens concerning Example 4 of the present invention. FIG. 10 is an aberration curve diagram of the imaging lens according to Example 5 of the present invention. It is a perspective view which shows typically the external appearance structure of the camera apparatus which concerns on Example 6 of this invention, Comprising: (A) shows the perspective view of a front side, (B) shows the perspective view of a back surface side. It is a block diagram which shows the system structural example of the camera apparatus of FIG. It is explanatory drawing for demonstrating the stereo camera apparatus which concerns on Example 7 of this invention.

  Embodiments of an imaging lens according to the present invention will be described below with reference to the drawings. 1 to 5 show five embodiments of the imaging lens according to the present invention. The imaging lenses of these embodiments correspond to imaging lenses of Examples 1 to 5 described later.

  As shown in FIGS. 1 to 5, the imaging lens according to the embodiment of the present invention includes, in order from the object side, a first lens L1 having a negative refractive power, a second lens L2 having a negative refractive index, and a positive lens. A third lens L3 having a refractive power, a fourth lens L4 having a positive refractive power, a fifth lens L5 having a negative refractive power, and a sixth lens L6 having a positive refractive power. .

  An aperture stop S is disposed between the third lens L3 and the fourth lens L4. The first lens L1 is a negative lens having both concave surfaces on the object side surface and the image side surface. The second lens L2 is composed of a negative lens having a concave surface directed toward the object side, and is configured such that the absolute value of the curvature of the object side surface is larger than the absolute value of the curvature of the image side surface. The third lens L3 is composed of a positive lens having a convex surface facing the image side, and has an absolute value of the curvature of the image side surface larger than the absolute value of the curvature of the object side surface. The image side surface of the second lens L2 and the object side surface of the third lens L3 are cemented with each other.

  First, the imaging lens according to the embodiment of the present invention has a main imaging function on the image side while disposing a negative refractive power on the object side and realizing a power arrangement close to retrofocus suitable for widening the angle. A positive lens, negative lens, and positive lens triplet (fourth lens L4, fifth lens L5, and sixth lens L6) are arranged in the portion to ensure basic freedom of aberration correction. In addition, a positive lens (third lens L3) is disposed at a portion facing the above triplet with the aperture stop S interposed therebetween, and the asymmetry before and after the aperture stop S is relaxed. It is possible to sufficiently reduce the coma that increases.

  Further, both the object side surface and the image side surface of the first lens L1 are concave surfaces, and the second lens L2 is configured to have a concave surface facing the object side. With this configuration, a negative refractive power is concentrated on the object side, and the diameter of the front lens is reduced so that the entrance pupil is located on the object side as much as possible. On the other hand, by dividing the strong negative refractive power into three surfaces and avoiding sudden deflection of light rays, it is possible to suppress the occurrence of excessive aberrations, which is advantageous for increasing the aperture.

  The image side surface of the third lens L3 has a convex surface facing the image side. In addition, the curvature of the object side surface of the second lens L2 and the image side surface of the third lens L3 is compared with the opposite surface of each lens. Is set larger. With this configuration, the object side surface of the second lens L2 and the image side surface of the third lens L3 effectively exchange aberrations, which contributes particularly to reduction of field curvature. Furthermore, by using the second lens L2 and the third lens L3 that exchange such aberrations as a cemented lens, it is less susceptible to manufacturing errors that occur during assembly, and stable performance can be ensured.

  As described above, in the imaging lens according to the embodiment of the present invention, the configuration of each part is optimized for the purpose, has a wide angle of view, a small F number, and a sufficiently small size. The diameter of the ball can be reduced and a high-performance imaging lens can be realized.

Further, the imaging lens according to an embodiment of the present invention, the second lens L2 and the combined focal length of the cemented lens of the third lens L3 is f _23, the focal length of the entire system in a focused state on the infinite When f is satisfied, it is desirable to satisfy the following conditional expression (1).

(1) -0.10 <f / f 23 <0.20

  As described above, in the imaging lens according to the embodiment of the present invention, an appropriate amount of aberration is exchanged between the object side surface of the second lens L2 and the image side surface of the third lens L3. The cemented lens composed of the second lens L2 and the third lens L3 has a meniscus shape as a whole. However, in order to properly maintain the balance of aberrations, it is desirable that the cemented lens does not have strong refractive power.

  If the conditional expression (1) is −0.10 or less, the astigmatic difference at the intermediate image height is likely to be increased, and introverted coma aberration is likely to occur. On the other hand, if conditional expression (1) is 0.20 or more, the astigmatic difference in the peripheral image height is likely to increase, or outward coma tends to occur, which is not preferable.

  For better aberration correction, it is desirable to satisfy the following conditional expression (1A).

(1A) -0.05 <f / f 23 <0.15

Further, the imaging lens according to an embodiment of the present invention, the radius of curvature of the object side surface of the second lens L2 and r _21, when the focal length of the entire system in a focused state on the infinite and is f, the following It is desirable to satisfy conditional expression (2).

_{(2) -1.0 <r 21 /} f <-0.6

  If the conditional expression (2) is −1.0 or less, it is difficult to exchange sufficient aberrations between the object side surface of the second lens L2 and the image side surface of the third lens L3, and field curvature is likely to occur. Therefore, it is not preferable. On the other hand, if the conditional expression (2) is −0.6 or more, the negative refractive power sharing balance between the object side surface of the second lens L2 and each surface of the first lens L1 is lost, and spherical aberration and coma aberration are caused. Since it becomes easy to generate | occur | produce, it is not preferable.

Further, the imaging lens according to an embodiment of the present invention, the focal length of the first lens L1 is f _1, a focal length of the entire system in a focused state on the infinite and is f, the following conditional expression ( It is desirable to satisfy 3).

_{(3) -3.5 <f 1 /} f <-1.0

  Since the first lens L1 shares negative refractive power with the object side surface of the second lens L2 as described above, it is necessary to have appropriate refractive power to some extent. If the refractive power of the first lens L1 becomes so weak that the conditional expression (3) is −3.5 or less, it becomes difficult to position the entrance pupil sufficiently toward the object side, so that the diameter of the front lens is easily increased. Or the curvature of the object side surface of the second lens L2 must be increased, and spherical aberration and coma aberration are likely to occur. On the other hand, when the refractive power of the first lens L1 becomes so strong that the conditional expression (3) is −1.0 or less, the degree of retrofocus increases and excessive negative distortion tends to occur. Deterioration in image performance due to decentering of the lens is undesirably increased.

Further, the imaging lens according to an embodiment of the present invention, the radius of curvature of the object side surface of the first lens L1 is r _11, when the focal length of the entire system in a focused state on the infinite and is f, the following It is desirable to satisfy conditional expression (4).
_{(4) -8.0 <r 11 /} f <-2.0

  When the conditional expression (4) is −8.0 or less, the object side surface of the first lens L1 cannot sufficiently share the negative refractive power, which easily increases spherical aberration and coma. In addition, since the radius of curvature of the first surface approaches infinity, a ghost due to reflection of return light from the sensor is likely to be condensed near the image plane I, which is not preferable. On the other hand, if the conditional expression (4) is −2.0 or more, the object side surface of the first lens L1 has an excessively negative refractive power, and negative distortion is likely to occur. Since disparity is likely to occur, it is not preferable.

  In the imaging lens according to the embodiment of the present invention, the fourth lens L4 having positive refractive power is a positive lens having a convex surface facing the object side, and the fifth lens L5 having negative refractive power is It is desirable that the sixth lens L6 having a negative refractive power facing the image side and having a positive refractive power is a positive lens having a convex surface facing the object side.

  With the fourth lens L4 having a convex surface facing the object side, a substantially symmetrical refractive power arrangement is created across the aperture stop S with the third lens L3 having the convex surface facing the image side, and spherical aberration and coma aberration are corrected in a well-balanced manner. It has the effect of facilitating.

  Further, by making the image side surface of the fifth lens L5 concave and making the object side surface of the sixth lens L6 convex, it becomes easier to control the amount of deflection of off-axis vertical rays, which also reduces high-order coma. effective.

Further, the imaging lens according to an embodiment of the present invention, the radius of curvature of the object side surface of the third lens L3 and r _31, when the focal length of the entire system in a focused state on the infinite and is f, the following It is desirable to satisfy conditional expression (5).

(5) 1.0 <r ₃₁ /f<1.3

  If the conditional expression (5) is 1.0 or less, spherical aberration tends to occur in the minus direction or inward coma tends to occur, which is not preferable. On the other hand, if conditional expression (5) is 1.3 or more, spherical aberration tends to occur in the positive direction and outward coma tends to occur, which is not preferable.

In the imaging lens according to the embodiment of the present invention, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 have an average refractive index of nd _2-5 and are set to infinity. It is desirable to satisfy the following conditional expression (6), where f is the focal length of the entire system in the focused state.

(6) 1.75 <nd _2-5 <2.05

  In an imaging lens having a large aperture and an F number of about 1.6, the depth of field is narrow, so it is necessary to sufficiently suppress field curvature. If the conditional expression (6) is 1.75 or less, it is difficult to sufficiently reduce the Petzval sum, and the field curvature tends to increase, which is not preferable. On the other hand, combinations of glass types for which conditional expression (6) is 2.05 or more are limited, and it is difficult to achieve compatibility with chromatic aberration correction.

In the imaging lens according to the embodiment of the present invention, the distance from the object side surface of the first lens L1 to the image plane I is L, the maximum image height is Y ′, and the maximum half angle of view (unit: degree) is set. When θ _max is satisfied, it is desirable that the following conditional expressions (7) and (8) are satisfied.

(7) 5.0 <L / Y ′ <8.0
(8) 30 < _θmax <40

  Conditional expression (7) regulates the total length of the imaging lens that best exhibits the effects of the present invention. Conditional expression (8) regulates the angle of view of the imaging lens that best exhibits the effects of the present invention.

Further, in the imaging lens according to an embodiment of the present invention, the second lens L2 third lens L3 is a refractive index at the d-line of the material constituting the third lens L3 is n _3, the second lens L2 It is desirable to satisfy the following conditional expression (9), where n ₂ is the refractive index of the material to be d-line.

_{(9) 0.10 <n 3 -n} 2 <0.30

  By giving an appropriate refractive index difference between the second lens L2 and the third lens within the range of the conditional expression (9), higher-order coma aberration can be corrected more favorably. .

Further, in the imaging lens according to an embodiment of the present invention, each of the refractive power of each lens L4, L5, L6 of the image side of the aperture stop S, a focal length of the fourth lens L4 and f _4, 5 the focal length of the lens L5 and f _5, a focal length of the sixth lens L6 and f _6, when the focal length of the entire system in a focused state on the infinite and is f, the following conditional expression (10) - ( It is desirable to satisfy 12).

(10) 0.8 <f ₄ /f<1.5
(11) −2.0 <f ₅ /f<−0.8
(12) 1.0 <f ₆ /f<2.5

In the imaging lens according to the embodiment of the present invention, the refractive powers of the lens group on the object side of the aperture stop S and the lens group on the image side of the aperture stop S are the first lens L1 and the second lens L2. The focal length of the lens group closer to the object side than the aperture stop S composed of three third lenses L3 is set to f _1-3, and the fourth lens L4, the fifth lens L5, and the sixth lens L6 are used. It is desirable that the following conditional expressions (13) and (14) are satisfied when the focal length of the lens unit on the image side of the configured aperture stop S is f _4-6 .

(13) -6.0 <f _1-3 /f<-1.6
(14) 1.1 <f _4-6 /f<1.6

  By keeping the refractive power of each lens and the refractive power of the lens group before and after the aperture stop S within the ranges of the conditional expressions (13) and (14), the half angle of view is 30 to 40 degrees and the F number is about 1.6. Therefore, it is more suitable for a small imaging lens.

  In addition, in order to correct aberrations, it is desirable to provide aspheric surfaces for the fourth lens L4 and the sixth lens L6. This configuration has a great effect on correcting spherical aberration, coma, astigmatism, and distortion.

  The camera device and the sensing device according to the embodiment of the present invention include the imaging lens as described above. By using such an imaging lens, it is possible to obtain a compact and high-performance camera device and sensing device with a wide angle of view, a small F number. In particular, it can be suitably used for in-vehicle cameras, in-vehicle stereo cameras, in-vehicle sensing cameras, digital cameras, video cameras, and the like.

  Hereinafter, specific embodiments (numerical embodiments) of the present invention will be described with reference to the drawings. In all the embodiments described below, the maximum image height Y ′ is 3 mm.

  1 to 5 are optical arrangement diagrams showing the lens configuration of an imaging lens according to Examples 1 to 5 of the present invention. 1 to 5, the left side of the paper is the object side, the right side of the paper is the image side, and each lens is arranged from the left side of the paper on the object side to the right side of the paper that is the image side. Yes.

  The imaging lenses according to Examples 1 to 5 shown in FIGS. 1 to 5 are, in order from the object side, a first lens L1 having a negative refractive power, a second lens L2 having a negative refractive index, A third lens L3 having positive refractive power, an aperture stop S, a fourth lens L4 having positive refractive power, a fifth lens L5 having negative refractive power, and a sixth lens L6 having positive refractive power are arranged. Configured.

  1 to 5, I denotes an image plane, and an optical element F disposed on the image plane I side of the fourth lens L4 is a CMOS (complementary metal oxide semiconductor) image sensor or a CCD (charge coupled device). ) A seal glass (cover glass) of a light receiving image pickup device such as an image sensor is shown as one parallel flat glass. The optical element F is disposed such that the image side surface is located at a position of about 0.5 mm from the image forming surface to the object side. Of course, the present invention is not limited to this configuration, and may be divided into a plurality of sheets.

  The aberration of the imaging lens of each example is corrected well and has high imaging performance. By constructing the imaging lens as in the present invention, the half angle of view is as wide as 30 to 40, and the F number is as large as about 1.6. And it is clear from each Example that sufficient resolving power can be ensured.

The meanings of the common symbols in each embodiment are as follows.
f: Focal length of entire system F: F number ω: Half angle of view (degrees)
Y ′: image height (y ′ in FIGS. 6 to 10)
R: radius of curvature D: surface spacing N _d : refractive index ν _{d at} d-line: Abbe number P _{g, F} : partial dispersion ratio P _{g, F} = ( _ng −n _F ) / (n _F −n _C )
K: aspherical conic constant A _4: 4-order aspherical coefficients A _6: 6-order aspherical coefficients A _8: 8-order aspherical coefficients A _10: 10-order aspherical coefficients

  In Examples 1-5, it has an aspherical lens surface. The aspheric surface used here is defined by the following equation (a), where C is the reciprocal of the paraxial radius of curvature (paraxial curvature) and H is the height from the optical axis.

Example 1
Hereinafter, numerical examples (numerical examples) of the imaging lens according to Example 1 shown in FIG. 1 will be shown. Table 1 below shows the optical characteristics of each optical element. In Table 1, “glass type name” is an optical glass type name of OHARA Corporation and HOYA Corporation. Further, the curvature radius R = ∞ represents a plane. Further, the symbol “*” is given to the surface number of the aspheric surface. The same applies to the tables of other examples. Table 2 below shows the conic constant and aspheric coefficient of the aspheric surface, and Table 3 below shows the calculation result (conditional numerical value) of the conditional expression.

  FIG. 6 shows aberration curve diagrams of spherical aberration, astigmatism, distortion aberration, and coma aberration of the imaging lens according to Example 1 at an object at infinity. In each aberration diagram, the thick line indicates the aberration with respect to the d line, and the thin line indicates the aberration with respect to the g line. A solid line in the astigmatism curve diagram indicates sagittal aberration, and a broken line indicates meridional aberration. The same applies to the aberration curve diagrams according to the other examples.

(Example 2)
Hereinafter, numerical examples of the imaging lens according to Example 2 shown in FIG. 2 will be shown. Tables 4 to 6 below show optical characteristics of each optical element, aspherical conic constant and aspherical coefficient, and calculation results of conditional expressions. FIG. 7 is a diagram showing aberration curves of spherical aberration, astigmatism, distortion and coma aberration of the imaging lens according to Example 2.

(Example 3)
The following is a numerical example of the imaging lens according to Example 3 shown in FIG. Tables 7 to 9 below show the optical characteristics of each optical element, the aspherical conic constant and the aspherical coefficient, and the calculation results of the conditional expressions. Further, FIG. 8 shows respective aberration curve diagrams of the spherical aberration, astigmatism, distortion aberration and coma aberration of the imaging lens according to Example 3.

Example 4
The following is a numerical example of the imaging lens according to Example 4 shown in FIG. Tables 10 to 12 below show the optical characteristics of each optical element, the aspherical conic constant and the aspherical coefficient, and the calculation results of the conditional expressions. In addition, FIG. 9 shows respective aberration curve diagrams of spherical aberration, astigmatism, distortion aberration and coma aberration of the imaging lens according to Example 4.

(Example 5)
The following is a numerical example of the imaging lens according to Example 5 shown in FIG. Tables 13 to 15 below show the optical characteristics of each optical element, the aspherical conic constant and the aspherical coefficient, and the calculation results of the conditional expressions. FIG. 10 is a graph showing aberration curves for spherical aberration, astigmatism, distortion, and coma of the imaging lens according to Example 5.

  As described above, the calculation results of the conditional expressions of the imaging lens according to Examples 1 to 5 of the present invention are all within the range of the conditional expressions (1) to (14). Furthermore, the more preferable conditional expression (1A) is also satisfied. According to these calculation results and the aberration curve diagrams of FIGS. 6 to 10, the imaging lens according to Examples 1 to 5 of the present invention has a half angle of view of 30 to 40 degrees and an F number of 1.6. Therefore, it is possible to provide a high-performance imaging lens that achieves a reduction in size, particularly a sufficiently small diameter, and has a resolving power corresponding to an image sensor with 1 to 4 million pixels.

(Example 6)
Next, as a sixth embodiment, an embodiment of a camera apparatus configured by adopting the imaging lens of the first to seventh embodiments according to the present invention described above as an optical system for image acquisition will be described with reference to FIGS. This will be described with reference to FIG. In the sixth embodiment, a digital camera which is an example of a camera device will be described.

  The camera device of the present invention is not limited to a digital camera, but mainly a camera device dedicated to imaging including a video camera mainly for moving image shooting and a film camera using a conventional so-called silver salt film, The imaging lens as in the first to fifth embodiments can be used in a monitoring camera device, and further in an in-vehicle drive recorder, a rear view camera, a surround view camera, and the like.

  In addition to such a camera device, a mobile information terminal device called a mobile phone, a PDA (personal data assistant) or the like, and a mobile terminal device such as a smartphone or a tablet terminal including these functions are also available. An imaging function corresponding to a digital camera or the like is often incorporated into various information devices (portable information terminal devices). Such an information device also includes substantially the same functions and configuration as a digital camera or the like, although the appearance is slightly different. In such an information device, the results of the first to fifth embodiments described above are included. An image lens can be used.

  As shown in FIGS. 11A and 11B, the digital camera 100 of this embodiment includes a housing (camera body) 5 and an imaging lens (imaging lens) 1 as an image acquisition optical system. An optical finder 2, a strobe (electronic flashlight) 3, a shutter button 4, a power switch 6, a liquid crystal monitor 7, an operation button 8, a memory card slot 9, a zoom switch 10, and the like are provided. Furthermore, as shown in FIG. 12, the digital camera 100 includes a central processing unit (CPU) 11, an image processing device 12, a light receiving element 13, a signal processing device 14, a semiconductor memory 15, a communication card 16, and the like in a housing 5. It has.

  The digital camera 100 includes an imaging lens 1 as an imaging lens and a light receiving element 13 configured as an image sensor using a CMOS (complementary metal oxide semiconductor) imaging device or a CCD (charge coupled device) imaging device. The light receiving element 13 reads a subject optical image formed by the imaging lens 1. As the imaging lens 1, the imaging lens of the first to seventh embodiments described above can be used.

  The output of the light receiving element 13 is processed by a signal processing device 14 controlled by the central processing unit 11 and converted into digital image information. The image information digitized by the signal processing device 14 is subjected to predetermined image processing in the image processing device 12 which is also controlled by the central processing unit 11 and then recorded in the semiconductor memory 15 such as a nonvolatile memory. In this case, the semiconductor memory 15 may be a memory card loaded in the memory card slot 9 or a semiconductor memory built on board in the digital camera body.

  The liquid crystal monitor 7 can display an image being shot, and can display an image recorded in the semiconductor memory 15. Further, the image recorded in the semiconductor memory 15 is transmitted to the outside via the communication card 16 or the like loaded in the communication card slot (not clearly shown, but can also be used as the memory card slot 9). Is also possible.

  When the camera is carried, the objective surface of the imaging lens 1 is covered with a lens barrier (not clearly shown). When the user operates the power switch 6 to turn on the power, the lens barrier opens, The objective surface is exposed.

  When the image recorded in the semiconductor memory 15 is displayed on the liquid crystal monitor 7 or transmitted to the outside via the communication card 16 or the like, the operation button 8 is operated in a predetermined manner. The semiconductor memory 15 and the communication card 16 are used by being loaded into dedicated or general-purpose slots such as the memory card slot 9 and the communication card slot.

  As described above, according to the sixth embodiment, the half angle of view is 30 to 40 degrees and the F number is about 1.6 as in the first to fifth embodiments of the present invention. In addition, by using the imaging lens 1 configured by using a high-performance imaging lens having a resolving power corresponding to an imaging device with 1 to 4 million pixels, sufficient S / N is ensured and the appearance is improved. It is possible to realize a high-quality digital camera (camera apparatus) in which the lens portion exposed to the screen is not conspicuous.

(Example 7)
Next, as a seventh embodiment, an in-vehicle stereo camera device as a sensing device configured by adopting the imaging lens of the first to fifth embodiments according to the present invention described above as an image acquisition optical system of the camera function unit One embodiment will be described with reference to FIG.

  As shown in FIG. 13, the in-vehicle stereo camera 200 according to the seventh embodiment includes two camera devices 100a and 100b as camera function units. Each of the camera devices 100a and 100b uses an imaging lens 1 formed of an imaging lens as in the first to fifth embodiments. As the camera devices 100a and 100b, for example, a device having the same configuration as that of the digital camera (camera device) 100 according to the sixth embodiment shown in FIG. 11 can be used, but is not limited thereto. The digital image information output from the camera devices 100a and 100b is subjected to appropriate correction and image processing by an image processing unit or the like provided in the in-vehicle stereo camera 200 and output, thereby sensing technology such as control of a production line or a vehicle. Can be used. The sensing device is not limited to the in-vehicle stereo camera device of the seventh embodiment, and may be a monocular type sensing device. For example, the imaging lens according to the first to fifth embodiments of the present invention can be applied to a sensing device that performs lane detection, obstacle detection, sign recognition, signal recognition, and the like.

  As described above, according to the seventh embodiment, the half angle of view is 30 to 40 degrees and the F number is about 1.6 as in the first to fifth embodiments of the present invention, so that the size reduction, particularly a sufficiently small diameter is achieved. In addition, by using the imaging lens 1 configured by using a high-performance imaging lens having a resolving power corresponding to an imaging device with 1 to 4 million pixels, sufficient S / N is ensured and the appearance is improved. It is possible to realize a high-quality in-vehicle stereo camera device (sensing device) in which the lens portion exposed to the surface is not conspicuous.

  As described above, the imaging lens, the camera device, and the sensing device of the present invention have been described based on each embodiment and each example. The present invention is not limited to the configurations of the above embodiments and examples. Design changes and additions are permitted without departing from the spirit of the present application. Further, the number, position, shape, and the like of the constituent members are not limited to the respective embodiments, and can be set to a number, position, shape, and the like suitable for carrying out the present application. In each of the above embodiments and examples, a camera device such as an in-vehicle camera, an in-vehicle stereo camera, an in-vehicle sensing camera, a digital camera, and a video camera, a silver salt camera, a drive recorder, a rear view camera, a surround view camera, and a lane detection device The example is applied to an imaging lens used for an obstacle detection device, a sign recognition device, a signal recognition device, and a camera device or a sensing device using the imaging lens, but the present application is limited to these. There is no. For example, the present invention can also be applied to an optical system used for an optical sensor and a projection optical system used for an image projection apparatus.

L1 1st lens L2 2nd lens L3 3rd lens L4 4th lens L5 5th lens L6 6th lens 1 Imaging lens (imaging lens)
DESCRIPTION OF SYMBOLS 100 Digital camera (camera apparatus) 100a, 100b Camera apparatus 200 Car-mounted stereo camera (sensing apparatus) S Aperture stop I Image plane

JP 2004-054013 A JP 2004-348082 A Japanese Patent No. 5750618

Claims (11)

In order from the object side, a first lens having a negative refractive power, a second lens having a negative refractive index, a third lens having a positive refractive power, a fourth lens having a positive refractive power, and a negative refractive power. A fifth lens having a sixth lens having a positive refractive power,
An aperture stop is disposed between the third lens and the fourth lens,
The first lens has both an object side surface and an image side surface concave.
The second lens has a concave surface facing the object side, and the absolute value of the curvature of the object side surface is configured to be larger than the absolute value of the curvature of the image side surface,
The third lens has a convex surface facing the image side, and the absolute value of the curvature of the image side surface is greater than the absolute value of the curvature of the object side surface,
An imaging lens, wherein an image side surface of the second lens and an object side surface of the third lens are cemented with each other. A composite focal distance f ₂₃ of the cemented lens of the third lens and the second lens, when the focal length of the entire system in a focused state on the infinite and is f, which satisfies the following condition The imaging lens according to claim 1, characterized in that:
(1) -0.10 <f / f 23 <0.20 2. The following conditional expression is satisfied, where r ₂₁ is the radius of curvature of the object side surface of the second lens and f is the focal length of the entire system in a state of focusing at infinity: The imaging lens according to 2.
_{(2) -1.0 <r 21 /} f <-0.6 The focal length of the first lens and f _1, the focal length of the entire system in a focused state on the infinite and is f, any of claims 1 to 3, characterized by satisfying the following condition The imaging lens according to claim 1.
_{(3) -3.5 <f 1 /} f <-1.0 The following conditional expression is satisfied, where r ₁₁ is the radius of curvature of the object side surface of the first lens, and f is the focal length of the entire system in a state of focusing at infinity. 5. The imaging lens according to any one of 4.
_{(4) -8.0 <r 11 /} f <-2.0   The fourth lens having a positive refractive power has a convex surface facing the object side, and the fifth lens having a negative refractive power has a concave surface facing the image side, and has a positive refractive power. The imaging lens according to claim 1, wherein the six lenses have a convex surface facing the object side. The following conditional expression is satisfied, where r ₃₁ is a radius of curvature of the object side surface of the third lens, and f is a focal length of the entire system in a state of being focused at infinity. The imaging lens as described in any one of 6.
(5) 1.0 <r ₃₁ /f<1.3 When the average refractive index of the second lens, the third lens, the fourth lens, and the fifth lens is nd _2-5 and the focal length of the entire system in the state of focusing at infinity is f, The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
(6) 1.75 <nd _2-5 <2.05 The following conditional expression is satisfied, where L is a distance from the object side surface to the image plane of the first lens, Y ′ is a maximum image height, and θ _max is a maximum half field angle. The imaging lens as described in any one of 1-8.
(7) 5.0 <L / Y ′ <8.0
(8) 30 < _θmax <40   A camera apparatus comprising: the imaging lens according to claim 1 as an image acquisition optical system.   A sensing apparatus comprising the imaging lens according to claim 1 as an image acquisition optical system of a camera function unit.