Patent Publication Number: US-2021181464-A1

Title: Imaging lens

Description:
The present application is based on and claims priority of a Japanese patent application No. 2017-228116 filed on Nov. 28, 2017, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to an imaging lens which forms an image of an object on a solid-state image sensor such as a CCD sensor or a C-MOS sensor used in an imaging device, and more particularly relates to an imaging lens which is built in an increasingly compact and high-performance smartphone and mobile phone, an information terminal such as a PDA (Personal Digital Assistant), a game console, PC and a robot, and moreover, a home appliance with camera function, a monitoring camera and an automobile. 
     Description of the Related Art 
     In recent years, it becomes common that camera function is mounted in a home appliance, information terminal equipment, an automobile and public transportation. Demand of products with the camera function is more increased, and development of products is being made accordingly. 
     The imaging lens mounted in such equipment is required to be compact and have high-resolution performance. 
     As a conventional imaging lens aiming high performance, for example, the imaging lens disclosed in Patent Document 1 (JP2016-114803A) has been known. 
     Patent Document 1 discloses an imaging lens comprising, in order from an object side, a first lens having positive refractive power and a convex surface facing the object side, a second lens having negative refractive power, a third lens having the convex surface facing the object side, a fourth lens having the positive refractive power, a fifth lens having the negative refractive power, and a sixth lens having the negative refractive power. 
     SUMMARY OF THE INVENTION 
     However, in lens configurations disclosed in the Patent Document 1, when wide field of view, low-profileness and low F-number are to be realized, it is very difficult to correct aberrations at a peripheral area, and excellent optical performance can not be obtained. 
     The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an imaging lens with high resolution which satisfies demand of the wide field of view, the low-profileness and the low F-number in well balance and excellently corrects aberrations. 
     Regarding terms used in the present invention, “a convex surface”, “a concave surface” or “a plane surface” of lens surfaces implies that a shape of the lens surface near an optical axis (paraxial portion). “Refractive power” implies the refractive power near the optical axis. “A pole point” implies an off-axial point on an aspheric surface at which a tangential plane intersects the optical axis perpendicularly. “Total track length” is defined as a distance along the optical axis from an object-side surface of an optical element located closest to the object to an image plane. The total track length and a back focus is a distance obtained when thickness of an IR cut filter or a cover glass which may be arranged between the imaging lens and the image plane is converted into an air-converted distance. 
     An imaging lens according to the present invention comprises, in order from an object side to an image side, a first lens having positive refractive power and a convex surface facing the object side near the optical axis, a second lens having negative refractive power near the optical axis, a third lens, a fourth lens, a fifth lens and a sixth lens having the negative refractive power and a concave surface facing the image side near the optical axis, wherein the image-side surface of the sixth lens is formed as an aspheric surface having at least one off-axial pole point. 
     The imaging lens having the above-described configuration achieves wide field of view and low-profileness by strengthening the refractive power of the first lens. The second lens properly corrects spherical aberration and chromatic aberration occurring at the first lens. The third lens properly corrects coma aberration, astigmatism and distortion. The fourth lens properly corrects the spherical aberration, the coma aberration, the astigmatism and the distortion. The fifth lens properly corrects the astigmatism, field curvature and the distortion while maintaining the low-profileness. The sixth lens secures a back focus while maintaining the low-profileness. The image-side surface of the sixth lens has the concave surface facing the image side near the optical axis, and the field curvature and the distortion can be properly corrected and the light ray incident angle to an image sensor can be properly controlled, when the image-side surface of the sixth lens is formed as the aspheric surface having at least one off-axial pole point. 
     According to the imaging lens having the above-described configuration, it is preferable that the image-side surface of the first lens has the concave surface facing the image side near the optical axis. 
     When the image-side surface of the first lens has the concave surface facing the image side near the optical axis, proper corrections of the astigmatism and the distortion can be realized. 
     According to the imaging lens having the above-described configuration, it is preferable that the refractive power of the third lens is positive. 
     When the refractive power of the third lens is positive, it is advantageous for the low-profileness. 
     According to the imaging lens having the above-described configuration, it is preferable that the object-side surface of the third lens has the convex surface facing the object side near the optical axis. 
     When the object-side surface of the third lens has the convex surface facing the object side near the optical axis, the coma aberration and the astigmatism can be properly corrected. 
     According to the imaging lens having the above-described configuration, it is preferable that the image-side surface of the third lens has the concave surface facing the image side near the optical axis. 
     When the image-side surface of the third lens has the concave surface facing the image side near the optical axis, the field curvature and the distortion can be properly corrected. 
     According to the imaging lens having the above-described configuration, it is preferable that the image-side surface of the fourth lens has the concave surface facing the image side near the optical axis. 
     When the image-side surface of the fourth lens has the concave surface facing the image side near the optical axis, the coma aberration, the astigmatism and the distortion can be properly corrected. 
     According to the imaging lens having the above-described configuration, it is preferable that a shape of the fifth lens is biconvex shape having convex surfaces facing the object side and the image side near the optical axis. 
     When the fifth lens has the biconvex shape having the convex surfaces facing the object side and the image side near the optical axis, the positive refractive power of the both surfaces is advantageous for the low-profileness. 
     According to the imaging lens having the above-described configuration, it is preferable that the object-side surface of the sixth lens has the convex surface facing the object side near the optical axis. 
     When the object-side surface of the sixth lens has the convex surface facing the object side near the optical axis, the astigmatism, the field curvature and the distortion can be properly corrected. 
     According to the imaging lens having the above-described configuration, it is preferable that the object-side surface of the sixth lens is formed as the aspheric surface having the off-axial pole point. 
     When the object-side surface of the sixth lens is formed as the aspheric surface having the off-axial pole point, the field curvature and the distortion can be properly corrected and the light ray incident angle to the image sensor can be properly controlled. 
     According to the imaging lens having the above-described configuration, it is preferable that a below conditional expression (1) is satisfied: 
       11&lt;vd4&lt;36   (1)
 
     where 
     vd4: abbe number at d-ray of the fourth lens. 
     The conditional expression (1) defines an appropriate range of the abbe number at d-ray of the fourth lens. By satisfying the conditional expression (1), the chromatic aberration can be properly corrected. 
     According to the imaging lens having the above-described configuration, it is preferable that a below conditional expression (2) is satisfied: 
       2.0&lt;( T 4/ f )×100&lt;7.6   (2)
 
     where 
     T 4 : distance along the optical axis from the image-side surface of the fourth lens to the object-side surface of the fifth lens, and 
     f: focal length of the overall optical system of the imaging lens. 
     The conditional expression (2) defines an appropriate range of the distance along the optical axis from the image-side surface of the fourth lens to the object-side surface of the fifth lens. By satisfying the conditional expression (2), the total track length can be shortened, and the coma aberration, the field curvature and the distortion can be properly corrected. 
     According to the imaging lens having the above-described configuration, it is preferable that a below conditional expression (3) is satisfied: 
       −2.5&lt;( D 2/ f 2)×100&lt;−0.7   (3)
 
     where 
     D 2 : thickness along the optical axis of the second lens, and 
     f2: focal length of the second lens. 
     The conditional expression (3) defines an appropriate range of the thickness along the optical axis of the second lens. When a value is below the upper limit of the conditional expression (3), the thickness along the optical axis of the second lens is prevented from being too small, and formability of the lens becomes excellent. On the other hand, when the value is above the lower limit of the conditional expression (3), the thickness along the optical axis of the second lens is prevented from being too large, and an air gaps of the object side and the image side of the second lens can be easily secured. As a result, the low-profileness can be maintained. 
     According to the imaging lens having the above-described configuration, it is preferable that a below conditional expression (4) is satisfied: 
       0.03 &lt;T 1/ T 2&lt;0.15   (4)
 
     where 
     T 1 : distance along the optical axis from the image-side surface of the first lens to the object-side surface of the second lens, and 
     T 2 : distance along the optical axis from the image-side surface of the second lens to the object-side surface of the third lens. 
     The conditional expression (4) defines an appropriate range of an interval between the first lens and the second lens, and the interval between the second lens and the third lens. By satisfying the conditional expression (4), difference between the interval of the first lens and the second lens and the interval of the second lens and the third lens is suppressed from being increased, and the low-profileness is achieved. 
     According to the imaging lens having the above-described configuration, it is preferable that a below conditional expression (5) is satisfied: 
       0.55 &lt;|r 7 |/f&lt; 1.95   (5)
 
     where 
     r7: paraxial curvature radius of the object-side surface of the fourth lens, and f: focal length of the overall optical system of the imaging lens. 
     The conditional expression (5) defines an appropriate range of the paraxial curvature radius of the object-side surface of the fourth lens. When a value is below the upper limit of the conditional expression (5), the coma aberration can be properly corrected. On the other hand, when the value is above the lower limit of the conditional expression (5), the spherical aberration and the distortion can be properly corrected. 
     According to the imaging lens having the above-described configuration, it is preferable that a below conditional expression (6) is satisfied: 
       3.5&lt;( T 3/ f )×100&lt;11.5   (6)
 
     where 
     T 3 : distance along the optical axis from the image-side surface of the third lens to the object-side surface of the fourth lens, and 
     f: focal length of the overall optical system of the imaging lens. 
     The conditional expression (6) defines an appropriate range of the distance along the optical axis from the image-side surface of the third lens to the object-side surface of the fourth lens. By satisfying the conditional expression (6), the total track length can be shortened, and the coma aberration, the field curvature and the distortion can be properly corrected. 
     According to the imaging lens having the above-described configuration, it is preferable that the refractive power of the fourth lens is negative near the optical axis, and more preferable that a below conditional expression (7) is satisfied: 
       −3.7 &lt;f 4 /f&lt; −0.8   (7)
 
     where 
     f4: focal length of the fourth lens, and 
     f: focal length of the overall optical system of the imaging lens. 
     By having the negative refractive power, the fourth lens properly corrects the chromatic aberration. Furthermore, the conditional expression (7) defines an appropriate range of the refractive power of the fourth lens. When a value is below the upper limit of the conditional expression (7), the negative refractive power of the fourth lens becomes appropriate, and the low-profileness is achieved. On the other hand, when the value is above the lower limit of the conditional expression (7), the chromatic aberration and the spherical aberration can be properly corrected. 
     According to the imaging lens having the above-described configuration, it is preferable that the refractive power of the fifth lens is positive near the optical axis, and more preferable that a below conditional expression (8) is satisfied: 
       0.3 &lt;f 5 /f&lt; 1.2   (8)
 
     where 
     f5: focal length of the fifth lens, and 
     f: focal length of the overall optical system of the imaging lens. 
     By having the positive refractive power, the fifth lens achieves the low-profileness. Furthermore, the conditional expression (8) defines an appropriate range of the refractive power of the fifth lens. When a value is below the upper limit of the conditional expression (8), the positive refractive power of the fifth lens becomes appropriate, and the low-profileness is achieved. On the other hand, when the value is above the lower limit of the conditional expression (8), the spherical aberration, the coma aberration and the distortion can be properly corrected. 
     According to the imaging lens having the above-described configuration, it is preferable that a below conditional expression (9) is satisfied: 
       −0.9 &lt;f 1/ f 4&lt;−0.2   (9)
 
     where 
     f1: focal length of the first lens, and 
     f4: focal length of the fourth lens. 
     The conditional expression (9) defines an appropriate range of the refractive power of the first lens and the fourth lens. When a value is below the upper limit of the conditional expression (9), the spherical aberration can be properly corrected. On the other hand, when the value is above the lower limit of the conditional expression (9), the refractive power of the first lens becomes appropriate and the low-profileness can be achieved. Furthermore, the distortion can be properly corrected. 
     According to the imaging lens having the above-described configuration, it is preferable that a below conditional expression (10) is satisfied: 
       −2.4 &lt;r 9/ r 10&lt;−0.5   (10)
 
     where 
     r9: paraxial curvature radius of the object-side surface of the fifth lens, and 
     r10: paraxial curvature radius of the image-side surface of the fifth lens. 
     The conditional expression (10) defines a shape of the object-side surface and the image-side surface of the fifth lens with a ratio of the paraxial curvature radii. By satisfying the conditional expression (10), the spherical aberration and the distortion can be properly corrected. 
     According to the imaging lens having the above-described configuration, it is preferable that a below conditional expression (11) is satisfied: 
       1.5 &lt;r 3/ f&lt; 6.3   (11)
 
     where 
     r3: paraxial curvature radius of the object-side surface of the second lens, and 
     f: focal length of the overall optical system of the imaging lens. 
     The conditional expression (11) defines an appropriate range of the paraxial curvature radius of the object-side surface of the second lens. When a value is below the upper limit of the conditional expression (11), the field curvature and the distortion can be properly corrected. On the other hand, when the value is above the lower limit of the conditional expression (11), the spherical aberration can be properly corrected. 
     According to the imaging lens having the above-described configuration, it is preferable that a below conditional expression (12) is satisfied: 
       0.35 &lt;|r 9 |/f&lt; 1.50   (12)
 
     where 
     r9: paraxial curvature radius of the object-side surface of the fifth lens, and 
     f: focal length of the overall optical system of the imaging lens. 
     The conditional expression (12) defines an appropriate range of the paraxial curvature radius of the object-side surface of the fifth lens. When a value is below the upper limit of the conditional expression (12), the astigmatism and the field curvature can be properly corrected. On the other hand, when the value is above the lower limit of the conditional expression (12), while maintaining refractive power of the object-side surface of the fifth lens, the spherical aberration and the distortion occurring at this surface are suppressed, and it becomes facilitated to reduce the sensitivity to the manufacturing error. 
     According to the imaging lens having the above-described configuration, it is preferable that a below conditional expression (13) is satisfied: 
       −1.2 &lt;f 6 /f&lt;− 0.3   (13)
 
     where 
     f6: focal length of the sixth lens, and 
     f: focal length of the overall optical system of the imaging lens. 
     The conditional expression (13) defines an appropriate range of the refractive power of the sixth lens. When a value is below the upper limit of the conditional expression (13), the negative refractive power of the sixth lens becomes appropriate, and the low-profileness is achieved. On the other hand, when the value is above the lower limit of the conditional expression (13), the chromatic aberration, the field curvature and the distortion can be properly corrected. 
     According to the imaging lens having the above-described configuration, it is preferable that a below conditional expression (14) is satisfied: 
       −0.4 &lt;f 1 /f 2&lt;−0.1   (14)
 
     where 
     f1: focal length of the first lens, and 
     f2: focal length of the second lens. 
     The conditional expression (14) defines an appropriate range of the refractive power of the first lens and the second lens. When a value is below the upper limit of the conditional expression (14), the coma aberration, the astigmatism and the distortion can be properly corrected. On the other hand, when the value is above the lower limit of the conditional expression (14), the refractive power of the first lens becomes appropriate and the low-profileness can be achieved. 
     According to the imaging lens having the above-described configuration, it is preferable that composite refractive power of the second lens, the third lens and the fourth lens is negative, and more preferable that a below conditional expression (15) is satisfied: 
       −3.1 &lt;f 234/ f&lt; −0.7   (15)
 
     where 
     f234: composite focal length of the second lens, the third lens and the fourth lens, and 
     f: focal length of the overall optical system of the imaging lens. 
     When the composite refractive power of the second lens, the third lens and the fourth lens is negative, the chromatic aberration can be properly corrected. Furthermore, the conditional expression (15) defines an appropriate range of the composite refractive power of the second lens, the third lens and the fourth lens. When a value is below the upper limit of the conditional expression (15), the negative composite refractive power of the second lens, the third lens and the fourth lens become appropriate, and the low-profileness can be achieved. On the other hand, when the value is above the lower limit of the conditional expression (15), the chromatic aberration and the spherical aberration can be properly corrected. 
     Effect of Invention 
     According to the present invention, there can be provided an imaging lens with high resolution which satisfies demand of the wide field of view, the low-profileness and the low F-number in well balance, and properly corrects aberrations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view showing a general configuration of an imaging lens in Example 1 according to the present invention; 
         FIG. 2  shows spherical aberration, astigmatism, and distortion of the imaging lens in Example 1 according to the present invention; 
         FIG. 3  is a schematic view showing the general configuration of an imaging lens in Example 2 according to the present invention; 
         FIG. 4  shows spherical aberration, astigmatism, and distortion of the imaging lens in Example 2 according to the present invention; 
         FIG. 5  is a schematic view showing the general configuration of an imaging lens in Example 3 according to the present invention; 
         FIG. 6  shows spherical aberration, astigmatism, and distortion of the imaging lens in Example 3 according to the present invention; 
         FIG. 7  is a schematic view showing the general configuration of an imaging lens in Example 4 according to the present invention; 
         FIG. 8  shows spherical aberration, astigmatism, and distortion of the imaging lens in Example 4 according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, the preferred embodiment of the present invention will be described in detail referring to the accompanying drawings. 
       FIGS. 1, 3, 5 and 7  are schematic views of the imaging lenses in Examples 1 to 4 according to the embodiments of the present invention. 
     As shown in  FIG. 1 , the imaging lens according to the present embodiments comprises, in order from an object side to an image side, a first lens L 1  having positive refractive power and a convex surface facing the object side near the optical axis X, a second lens L 2  having negative refractive power near the optical axis X, a third lens L 3 , a fourth lens L 4 , a fifth lens L 5  and a sixth lens L 6  having negative refractive power and a concave surface facing the image side near the optical axis X. The image-side surface of the sixth lens L 6  is formed as an aspheric surface having at least one off-axial pole point. 
     A filter IR such as an IR cut filter and a cover glass is arranged between the sixth lens L 6  and an image plane IMG (namely, the image plane of an image sensor). The filter IR is omissible. 
     An aperture stop ST is arranged on the object side of the first lens L 1 , and the aberration correction is facilitated and control of the light ray incident angle of high image height to the image sensor become facilitated. Furthermore, the aperture stop ST may be arranged between the second lens L 2  and the third lens L 3  as in Examples 3 and 4 shown in  FIGS. 5 and 7 . In this case, the aberration correction and the wide field of view are facilitated. 
     The first lens L 1  has the positive refractive power, and achieves wide field of view and the low-profileness by strengthening the refractive power. A shape of the first lens L 1  is a meniscus shape having a convex surface facing the object side and a concave surface facing the image side near an optical axis X, and the spherical aberration, the astigmatism and the distortion can be properly corrected. 
     The second lens L 2  has the negative refractive power, and properly corrects the spherical aberration and the chromatic aberration occurring at the first lens L 1 . A shape of the second lens L 2  is the meniscus shape having the convex surface facing the object side near the optical axis X, and the spherical aberration, the astigmatism, the field curvature and the distortion can be properly corrected. 
     The third lens L 3  has the positive refractive power, and properly corrects the coma aberration, the astigmatism and the distortion. A shape of the third lens L 3  is the meniscus shape having the convex surface facing the object side and the concave surface facing the image side near the optical axis X, and the coma aberration, the astigmatism, the field curvature and the distortion can be properly corrected. 
     The fourth lens L 4  has the negative refractive power, and properly corrects the spherical aberration, the coma aberration, the astigmatism and the distortion. A shape of the fourth lens L 4  is the meniscus shape having the convex surface facing the object side and the concave surface facing the image side near the optical axis X, and the coma aberration, the astigmatism and the distortion can be properly corrected. 
     The fifth lens L 5  has the positive refractive power, and properly corrects the astigmatism, the field curvature and the distortion while maintaining the low-profileness. A shape of the fifth lens L 5  is a biconvex shape having the convex surfaces facing the object side and the image side near the optical axis X, and the positive refractive power of the both surfaces is advantageous for the low-profileness. 
     The sixth lens L 6  has the negative refractive power, and secures a back focus while maintaining the low-profileness. A shape of the sixth lens L 6  is the meniscus shape having the convex surface facing the object side and the concave surface facing the image side near the optical axis X, and the astigmatism, the field curvature and the distortion can be properly corrected. 
     Furthermore, the object-side surface and the image-side surface of the sixth lens L 6  are formed as the aspheric surface having the off-axial pole point, and the field curvature and the distortion are properly corrected and the light ray incident angle to the image sensor can be properly controlled. 
     Regarding the imaging lens according to the present embodiments, it is preferable that all lenses from the first lens L 1  to the sixth lens L 6  is single lens. Configuration consisting of only the single lenses can frequently use the aspheric surfaces. In the present embodiments, all lens-surfaces are formed as the appropriate aspherical surfaces, and proper aberration correction is made. In comparison with the case in which a cemented lens is used, workload is reduced, and manufacturing in low cost becomes possible. 
     Furthermore, the imaging lens according to the present embodiments makes manufacturing facilitated by using plastic material for all of the lenses, and mass production in a low cost can be realized. 
     The material applied to the lens is not limited to the plastic material. By using glass material, further high performance may be aimed. It is preferable that all of lens-surfaces are formed as aspheric surfaces, however, spherical surfaces easy to be manufactured may be adopted in accordance with required performance. 
     The imaging lens according to the present embodiments shows preferable effect by satisfying the below conditional expressions (1) to (15). 
       11&lt;vd4&lt;36   (1)
 
       2.0&lt;( T 4/ f )×100&lt;7.6   (2)
 
       −2.5&lt;( D 2/ f 2)×100&lt;−0.7   (3)
 
       0.03 &lt;T 1/ T 2&lt;0.15   (4)
 
       0.55 &lt;|r 7 |/f&lt; 1.95   (5)
 
       3.5&lt;( T 3/ f )×100&lt;11.5   (6)
 
       −3.7 &lt;f 4 /f&lt; −0.8   (7)
 
       0.3 &lt;f 5 /f&lt; 1.2   (8)
 
       −0.9 &lt;f 1/ f 4&lt;−0.2   (9)
 
       −2.4 &lt;r 9/ r 10&lt;−0.5   (10)
 
       1.5 &lt;r 3/ f&lt; 6.3   (11)
 
       0.35 &lt;|r 9 |/f&lt; 1.50   (12)
 
       −1.2 &lt;f 6 /f&lt;− 0.3   (13)
 
       −0.4 &lt;f 1 /f 2&lt;−0.1   (14)
 
       −3.1 &lt;f 234/ f&lt; −0.7   (15)
 
     where 
     vd4: abbe number at d-ray of the fourth lens L 4 , 
     D 2 : thickness along the optical axis X of the second lens L 2 , 
     T 1 : distance along the optical axis X from the image-side surface of the first lens L 1  to the object-side surface of the second lens L 2 , 
     T 2 : distance along the optical axis X from the image-side surface of the second lens L 2  to the object-side surface of the third lens L 3 , 
     T 3 : distance along the optical axis X from the image-side surface of the third lens L 3  to the object-side surface of the fourth lens L 4 , 
     T 4 : distance along the optical axis X from the image-side surface of the fourth lens L 4  to the object-side surface of the fifth lens L 5 , 
     f: focal length of the overall optical system of the imaging lens, 
     f1: focal length of the first lens L 1 , 
     f2: focal length of the second lens L 2 , 
     f4: focal length of the fourth lens L 4 , 
     f5: focal length of the fifth lens L 5 , 
     f6: focal length of the sixth lens L 6 , 
     f234: composite focal length of the second lens L 2 , the third lens L 3  and the fourth lens L 4 , 
     r3: paraxial curvature radius of the object-side surface of the second lens L 2 , 
     r7: paraxial curvature radius of the object-side surface of the fourth lens L 4 , 
     r9: paraxial curvature radius of the object-side surface of the fifth lens L 5 , and 
     r10: paraxial curvature radius of the image-side surface of the fifth lens L 5 . 
     It is not necessary to satisfy the above all conditional expressions, and by satisfying the conditional expression individually, operational advantage corresponding to each conditional expression can be obtained. 
     The imaging lens according to the present embodiments shows further preferable effect by satisfying the below conditional expressions (1a) to (15a). 
       17&lt;vd4&lt;29   (1a)
 
       3.0&lt;( T 4/ f )×100&lt;6.3   (2a)
 
       −2.0&lt;( D 2/ f 2)×100&lt;−1.1   (3a)
 
       0.05 &lt;T 1/ T 2&lt;0.12   (4a)
 
       0.85 &lt;|r 7 |/f&lt; 1.60   (5a)
 
       5.0&lt;( T 3/ f )×100&lt;6.5   (6a)
 
       −3.1 &lt;f 4 /f&lt; −1.3   (7a)
 
       0.50 &lt;f 5 /f&lt; 0.95   (8a)
 
       −0.75 &lt;f 1/ f 4&lt;−0.30   (9a)
 
       −2.0 &lt;r 9/ r 10&lt;−0.8   (10a)
 
       2.5 &lt;r 3/ f&lt; 5.2   (11a)
 
       0.55 &lt;|r 9 |/f&lt; 1.25   (12a)
 
       −0.95 &lt;f 6 /f&lt;− 0.50   (13a)
 
       −0.3 &lt;f 1 /f 2&lt;−0.15   (14a)
 
       −2.6 &lt;f 234/ f&lt; −1.0   (15a)
 
     The signs in the above conditional expressions have the same meanings as those in the paragraph before the preceding paragraph. 
     In this embodiment, the aspheric shapes of the surfaces of the aspheric lens are expressed by Equation 1, where Z denotes an axis in the optical axis direction, H denotes a height perpendicular to the optical axis, R denotes a paraxial curvature radius, k denotes a conic constant, and A 4 , A 6 , A 8 , A 10 , A 12 , A 14  and A 16  denote aspheric surface coefficients. 
     
       
         
           
             Z 
             = 
             
               
                 
                   
                     H 
                     2 
                   
                   R 
                 
                 
                   1 
                   + 
                   
                     
                       1 
                       - 
                       
                         
                           ( 
                           
                             k 
                             + 
                             1 
                           
                           ) 
                         
                          
                         
                           
                             H 
                             2 
                           
                           
                             R 
                             2 
                           
                         
                       
                     
                   
                 
               
               + 
               
                 
                   A 
                   4 
                 
                  
                 
                   H 
                   4 
                 
               
               + 
               
                 
                   A 
                   6 
                 
                  
                 
                   H 
                   6 
                 
               
               + 
               
                 
                   A 
                   8 
                 
                  
                 
                   H 
                   8 
                 
               
               + 
               
                 
                   A 
                   10 
                 
                  
                 
                   H 
                   10 
                 
               
               + 
               
                 
                   A 
                   12 
                 
                  
                 
                   H 
                   12 
                 
               
               + 
               
                 
                   A 
                   14 
                 
                  
                 
                   H 
                   14 
                 
               
               + 
               
                 
                   A 
                   16 
                 
                  
                 
                   H 
                   16 
                 
               
             
           
         
       
     
     Next, examples of the imaging lens according to this embodiment will be explained. In each example, f denotes the focal length of the overall optical system of the imaging lens, Fno denotes an F-number, ω denotes a half field of view, ih denotes a maximum image height, and TTL denotes a total track length. Additionally, i denotes surface number counted from the object side, r denotes a curvature radius, d denotes the distance of lenses along the optical axis (surface distance), Nd denotes a refractive index at d-ray (reference wavelength), and vd denotes an abbe number at d-ray. As for aspheric surfaces, an asterisk (*) is added after surface number i. 
     EXAMPLE 1 
     The basic lens data is shown below in Table 1. 
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Example 1 
               
               
                 Unit mm 
               
               
                 f = 3.44 
               
               
                 Fno = 1.4 
               
               
                 ω(°) = 38.2 
               
               
                 ih = 2.91 
               
               
                 TTL = 4.30 
               
               
                   
               
             
            
               
                 Surface Data 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Surface 
                 Curvature 
                 Surface 
                 Refractive 
                 Abbe 
                   
               
               
                   
                 Number i 
                 Radius r 
                 Distance d 
                 index Nd 
                 Number νd 
               
               
                   
                   
               
               
                   
                 (Object) 
                 Infinity 
                 Infinity 
               
               
                   
                 1 (Stop) 
                 Infinity 
                 −0.3900 
               
               
                   
                 2* 
                 1.6094 
                 0.6977 
                 1.544 
                 55.57 
                 (νd1) 
               
               
                   
                 3* 
                 9.3835 
                 0.0397 
               
               
                   
                 4* 
                 11.9664 
                 0.2300 
                 1.661 
                 20.37 
                 (νd2) 
               
               
                   
                 5* 
                 5.2011 
                 0.4398 
               
               
                   
                 6* 
                 4.1175 
                 0.3243 
                 1.544 
                 55.57 
                 (νd3) 
               
               
                   
                 7* 
                 5.6753 
                 0.2409 
               
               
                   
                 8* 
                 4.3770 
                 0.2361 
                 1.639 
                 23.52 
                 (νd4) 
               
               
                   
                 9* 
                 2.0019 
                 0.1384 
               
               
                   
                 10*  
                 2.9677 
                 0.4602 
                 1.544 
                 55.57 
                 (νd5) 
               
               
                   
                 11*  
                 −2.2917 
                 0.2723 
               
               
                   
                 12*  
                 19.6142 
                 0.3800 
                 1.544 
                 55.57 
                 (νd6) 
               
               
                   
                 13*  
                 1.3006 
                 0.3700 
               
               
                   
                 14  
                 Infinity 
                 0.2100 
                 1.517 
                 64.20 
               
               
                   
                 15  
                 Infinity 
                 0.3276 
               
               
                   
                 Image Plane 
                 Infinity 
               
               
                   
                   
               
            
           
           
               
            
               
                 Constituent Lens Data 
               
            
           
           
               
               
               
               
               
            
               
                 Lens 
                 Start Surface 
                 Focal Length 
                   
                 Composite Focal Length 
               
               
                   
               
               
                 1 
                 2 
                 3.463 
                 f234 
                 −4.915 
               
               
                 2 
                 4 
                 −14.114 
               
               
                 3 
                 6 
                 25.699 
               
               
                 4 
                 8 
                 −6.005 
               
               
                 5 
                 10 
                 2.453 
               
               
                 6 
                 12 
                 −2.580 
               
               
                   
               
            
           
           
               
               
            
               
                 Aspheric Surface Data 
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Second Surface 
                 Third Surface 
                 Fourth Surface 
                 Fifth Surface 
                 Sixth Surface 
                 Seventh Surface 
               
               
                   
               
               
                 k 
                 4.987035E−01 
                 −2.688782E+01 
                  9.000000E+01 
                 −1.856577E+01  
                 −9.000000E+01 
                 2.472940E+01 
               
               
                 A4 
                 −5.555494E−02  
                 −1.526273E−01 
                 −2.108435E−01 
                 −3.756019E−02  
                  1.235746E−02 
                 −1.394801E−01  
               
               
                 A6 
                 8.572612E−02 
                  1.045746E−01 
                  2.835538E−01 
                 5.608209E−02 
                 −6.218280E−02 
                 1.208818E−01 
               
               
                 A8 
                 −1.718496E−01  
                  9.773003E−02 
                 −1.205436E−01 
                 3.736784E−02 
                 −2.038960E−01 
                 −3.767377E−01  
               
               
                 A10 
                 1.382639E−01 
                 −2.286096E−01 
                 −6.208203E−02 
                 −7.567982E−02  
                  3.895483E−01 
                 3.669745E−01 
               
               
                 A12 
                 −6.006648E−02  
                  1.423253E−01 
                  7.684567E−02 
                 7.091145E−03 
                 −3.489239E−01 
                 −2.381596E−01  
               
               
                 A14 
                 5.064121E−03 
                 −3.073652E−02 
                 −1.739348E−02 
                 2.009295E−02 
                  1.175107E−01 
                 6.249413E−02 
               
               
                 A16 
                 0.000000E+00 
                  0.000000E+00 
                  0.000000E+00 
                 0.000000E+00 
                  0.000000E+00 
                 0.000000E+00 
               
               
                   
               
               
                   
                 Eighth Surface 
                 Ninth Surface 
                 Tenth Surface 
                 Eleventh Surface 
                 Twelfth Surface 
                 Thirteenth Surface 
               
               
                   
               
               
                 k 
                  5.516206E+00 
                 −1.745471E+01 
                 −6.520200E−01 
                 −2.603744E+00 
                  9.000000E+01 
                 −1.028107E+01 
               
               
                 A4 
                 −4.192880E−01 
                 −3.059849E−01 
                 −8.561753E−02 
                  4.071701E−02 
                 −5.253138E−01 
                 −1.717883E−01 
               
               
                 A6 
                  4.368567E−01 
                  1.740502E−01 
                 −6.962971E−02 
                  1.331782E−01 
                  4.277920E−01 
                  9.521773E−02 
               
               
                 A8 
                 −2.237165E−01 
                 −7.340010E−02 
                  4.220132E−03 
                 −3.153323E−01 
                 −2.728194E−01 
                 −3.981095E−02 
               
               
                 A10 
                 −2.804664E−01 
                 −1.242653E−01 
                 −5.916369E−02 
                  2.336124E−01 
                  1.326861E−01 
                  1.124559E−02 
               
               
                 A12 
                  3.578753E−01 
                  2.815231E−01 
                  9.270319E−02 
                 −8.297637E−02 
                 −3.917612E−02 
                 −2.058028E−03 
               
               
                 A14 
                 −6.906181E−02 
                 −1.937360E−01 
                 −3.677506E−02 
                  1.482006E−02 
                  6.065312E−03 
                  2.131075E−04 
               
               
                 A16 
                 −5.671833E−02 
                  4.110195E−02 
                  2.755416E−03 
                 −1.086163E−03 
                 −3.791973E−04 
                 −9.911666E−06 
               
               
                   
               
            
           
         
       
     
     The imaging lens in Example 1 satisfies conditional expressions (1) to (15) as shown in Table 5. 
       FIG. 2  shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens in Example 1. The spherical aberration diagram shows the amount of aberration at wavelengths of F-ray (486 nm), d-ray (588 nm), and C-ray (656 nm). The astigmatism diagram shows the amount of aberration at d-ray on a sagittal image surface S (solid line) and on tangential image surface T (broken line), respectively (same as  FIGS. 4, 6 and 8 ). 
     EXAMPLE 2 
     The basic lens data is shown below in Table 2. 
     
       
         
           
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Example 2 
               
               
                 Unit mm 
               
               
                 f = 3.48 
               
               
                 Fno = 1.4 
               
               
                 ω(°) = 38.3 
               
               
                 ih = 2.91 
               
               
                 TTL = 4.32 
               
               
                   
               
             
            
               
                 Surface Data 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Surface 
                 Curvature 
                 Surface 
                 Refractive 
                 Abbe 
                   
               
               
                   
                 Number i 
                 Radius r 
                 Distance d 
                 Index Nd 
                 Number νd 
               
               
                   
                   
               
               
                   
                 (Object) 
                 Infinity 
                 infinity 
               
               
                   
                 1 (Stop) 
                 Infinity 
                 −0.3900 
               
               
                   
                 2* 
                 1.6269 
                 0.7020 
                 1.544 
                 55.57 
                 (νd1) 
               
               
                   
                 3* 
                 8.3877 
                 0.0419 
               
               
                   
                 4* 
                 11.8788 
                 0.2300 
                 1.661 
                 20.37 
                 (νd2) 
               
               
                   
                 5* 
                 5.4986 
                 0.4227 
               
               
                   
                 6* 
                 4.3162 
                 0.3429 
                 1.544 
                 55.57 
                 (νd3) 
               
               
                   
                 7* 
                 5.8420 
                 0.2515 
               
               
                   
                 8* 
                 4.0944 
                 0.2347 
                 1.639 
                 23.52 
                 (νd4) 
               
               
                   
                 9* 
                 2.2752 
                 0.1512 
               
               
                   
                 10*  
                 3.3505 
                 0.4942 
                 1.544 
                 55.57 
                 (νd5) 
               
               
                   
                 11*  
                 −2.3338 
                 0.2213 
               
               
                   
                 12*  
                 19.0931 
                 0.3800 
                 1.544 
                 55.57 
                 (νd6) 
               
               
                   
                 13*  
                 1.2266 
                 0.3700 
               
               
                   
                 14  
                 Infinity 
                 0.2100 
                 1.517 
                 64.20 
               
               
                   
                 15  
                 Infinity 
                 0.3358 
               
               
                   
                 Image Plane 
                 Infinity 
               
               
                   
                   
               
            
           
           
               
            
               
                 Constituent Lens Data 
               
            
           
           
               
               
               
               
               
            
               
                 Lens 
                 Start Surface 
                 Focal Length 
                   
                 Composite Focal Length 
               
               
                   
               
               
                 1 
                 2 
                 3.581 
                 f234 
                 −6.673 
               
               
                 2 
                 4 
                 −15.719 
               
               
                 3 
                 6 
                 28.161 
               
               
                 4 
                 8 
                 −8.436 
               
               
                 5 
                 10 
                 2.609 
               
               
                 6 
                 12 
                 −2.429 
               
               
                   
               
            
           
           
               
            
               
                 Aspheric Surface Data 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Second Surface 
                 Third Surface 
                 Fourth Surface 
                 Fifth Surface 
                 Sixth Surface 
                 Seventh Surface 
               
               
                   
               
               
                 k 
                 4.674292E−01 
                 −6.642430E+01 
                  9.000000E+01 
                 −1.534102E+01  
                 −9.000000E+01 
                 2.368849E+01 
               
               
                 A4 
                 −5.436709E−02  
                 −1.534125E−01 
                 −2.105661E−01 
                 −3.471366E−02  
                  2.186688E−02 
                 −1.453991E−01  
               
               
                 A6 
                 8.625409E−02 
                  1.046284E−01 
                  2.827697E−01 
                 6.231902E−02 
                 −5.154471E−02 
                 1.432295E−01 
               
               
                 A8 
                 −1.719724E−01  
                  9.712010E−02 
                 −1.201174E−01 
                 3.845416E−02 
                 −1.927084E−01 
                 −3.551228E−01  
               
               
                 A10 
                 1.385664E−01 
                 −2.292563E−01 
                 −6.135078E−02 
                 −7.898329E−02  
                  3.955738E−01 
                 3.576395E−01 
               
               
                 A12 
                 −5.966951E−02  
                  1.430458E−01 
                  7.682668E−02 
                 7.286037E−03 
                 −3.542074E−01 
                 −2.583263E−01  
               
               
                 A14 
                 5.261949E−03 
                 −3.163729E−02 
                 −1.817577E−02 
                 2.571477E−02 
                  1 229529E−01 
                 7.900652E−02 
               
               
                 A16 
                 0.000000E+00 
                  0.000000E+00 
                  0.000000E+00 
                 0.000000E+00 
                  0.000000E+00 
                 0.000000E+00 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 Eighth Surface 
                 Ninth Surface 
                 Tenth Surface 
                 Eleventh Surface 
                 Twelfth Surface Thirteenth Surface 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 k 
                  5.575416E+00 
                 −2.008031E+01 
                  2.228684E+00 
                 −8.896047E+00 
                  9.000000E+01 
                 −9.083602E+00 
               
               
                 A4 
                 −4.188360E−01 
                 −3.088397E−01 
                 −6.219145E−02 
                  2.744640E−02 
                 −5.261346E−01 
                 −1.860829E−01 
               
               
                 A6 
                  4.444972E−01 
                  1.914914E−01 
                 −8.776622E−02 
                  1.249411E−01 
                  4.265122E−01 
                  1.062952E−01 
               
               
                 A8 
                 −2.308657E−01 
                 −7.229759E−02 
                  3.578921E−03 
                 −3.153029E−01 
                 −2.726456E−01 
                 −4.238918E−02 
               
               
                 A10 
                 −2.785255E−01 
                 −1.285472E−01 
                 −5.660369E−02 
                  2.341448E−01 
                  1.327908E−01 
                  1.138713E−02 
               
               
                 A12 
                  3.685006E−01 
                  2.886875E−01 
                  9.260148E−02 
                 −8.285056E−02 
                 −3 915949E−02 
                 −2.032684E−03 
               
               
                 A14 
                 −6.578524E−02 
                 −1.936005E−01 
                 −3.729032E−02 
                  1.481650E−02 
                  6.064388E−03 
                  2.129837E−04 
               
               
                 A16 
                 −7.178390E−02 
                  4.189695E−02 
                  3.120460E−03 
                 −1.094056E−03 
                 −3.810985E−04 
                 −1.021343E−05 
               
               
                   
               
            
           
         
       
     
     The imaging lens in Example 2 satisfies conditional expressions (1) to (15) as shown in Table 5. 
       FIG. 4  shows the spherical aberration (mm), the astigmatism (mm), and the distortion (%) of the imaging lens in Example 2. 
     EXAMPLE 3 
     The basic lens data is shown below in Table 3. 
     
       
         
           
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 Example 3 
               
               
                 Unit mm 
               
               
                 f = 3.62 
               
               
                 Fno = 1.4 
               
               
                 ω(°) = 38.3 
               
               
                 ih = 2.91 
               
               
                 TTL = 4.34 
               
               
                   
               
             
            
               
                 Surface Data 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Surface 
                 Curvature 
                 Surface 
                 Refractive 
                 Abbe 
                   
               
               
                   
                 Number i 
                 Radius r 
                 Distance d 
                 Index Nd 
                 Number νd 
               
               
                   
                   
               
               
                   
                 (Object) 
                 Infinity 
                 Infinity 
               
               
                   
                 1* 
                 1.63857 
                 0.7395 
                 1.544 
                 55.57 
                 (νd1) 
               
               
                   
                 2* 
                 8.0871 
                 0.0282 
               
               
                   
                 3* 
                 15.0991 
                 0.2300 
                 1.661 
                 20.37 
                 (νd2) 
               
               
                   
                 4* 
                 6.2513 
                 0.2651 
               
               
                   
                 5 (Stop) 
                 Infinity 
                 0.1584 
               
               
                   
                 6* 
                 5.1327 
                 0.3183 
                 1.544 
                 55.57 
                 (νd3) 
               
               
                   
                 7* 
                 6.7234 
                 0.2744 
               
               
                   
                 8* 
                 4.4365 
                 0.2412 
                 1.639 
                 23.52 
                 (νd4) 
               
               
                   
                 9* 
                 2.2014 
                 0.1506 
               
               
                   
                 10*  
                 2.6750 
                 0.5452 
                 1.544 
                 55.57 
                 (νd5) 
               
               
                   
                 11*  
                 −2.4043 
                 0.1900 
               
               
                   
                 12*  
                 19.2401 
                 0.3596 
                 1.544 
                 55.57 
                 (νd6) 
               
               
                   
                 13*  
                 1.2194 
                 0.3700 
               
               
                   
                 14  
                 Infinity 
                 0.2100 
                 1.517 
                 64.20 
               
               
                   
                 15  
                 Infinity 
                 0.3294 
               
               
                   
                 Image Plane 
                 Infinity 
               
               
                   
                   
               
            
           
           
               
            
               
                 Constituent Lens Data 
               
            
           
           
               
               
               
               
               
            
               
                 Lens 
                 Start Surface 
                 Focal Length 
                   
                 Composite Focal Length 
               
               
                   
               
               
                 1 
                 1 
                 3.632 
                 f234 
                 −5.576 
               
               
                 2 
                 3 
                 −16.314 
               
               
                 3 
                 6 
                 37.266 
               
               
                 4 
                 8 
                 −7.137 
               
               
                 5 
                 10 
                 2.420 
               
               
                 6 
                 12 
                 −2.411 
               
               
                   
               
            
           
           
               
               
            
               
                 Aspheric Surface Data 
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 First Surface 
                 Second Surface 
                 Third Surface 
                 Fourth Surface 
                 Sixth Surface 
                 Seventh Surface 
               
               
                   
               
               
                 k 
                 4.292635E−01 
                 −4.673005E+02 
                  9.000000E+01 
                 −9.000000E+01  
                 −9.000000E+01 
                 3.050070E+01 
               
               
                 A4 
                 −4.764840E−02  
                 −1.231120E−01 
                 −1.920483E−01 
                 1.503460E−02 
                  1.425028E−02 
                 −1.281827E−01  
               
               
                 A6 
                 7.816589E−02 
                  1.082146E−01 
                  2.857160E−01 
                 3.320769E−02 
                 −4.453322E−02 
                 1.594509E−01 
               
               
                 A8 
                 −1.607793E−01  
                  9.125536E−02 
                 −1.234023E−01 
                 1.663734E−02 
                 −1.657714E−01 
                 −3.624213E−01  
               
               
                 A10 
                 1.402530E−01 
                 −2.334920E−01 
                 −7.067358E−02 
                 −6.149833E−02  
                  3.937586E−01 
                 3.833063E−01 
               
               
                 A12 
                 −6.128964E−02  
                  1.413819E−01 
                  7.430328E−02 
                 2.286959E−02 
                 −3.888770E−01 
                 −2.709135E−01  
               
               
                 A14 
                 6.309933E−03 
                 −2.856066E−02 
                 −1.367259E−02 
                 8.818410E−03 
                  1.384630E−01 
                 7.681260E−02 
               
               
                 A16 
                 0.000000E+00 
                  0.000000E+00 
                  0.000000E+00 
                 0.000000E+00 
                  0.000000E+00 
                 0.000000E+00 
               
               
                   
               
               
                   
                 Eighth Surface 
                 Ninth Surface 
                 Tenth Surface 
                 Eleventh Surface 
                 Twelfth Surface 
                 Thirteenth Surface 
               
               
                   
               
               
                 k 
                  7.577463E+00 
                 −2.262531E+01 
                  4.246122E−01 
                 −2.146051E+01 
                  9.000000E+01 
                 −9.891763E+00 
               
               
                 A4 
                 −4.104396E−01 
                 −3.031196E−01 
                 −6.972641E−02 
                  2.532353E−02 
                 −5.009980E−01 
                 −1.860990E−01 
               
               
                 A6 
                  4 341799E−01 
                  1.782258E−01 
                 −8.223397E−02 
                  1.260623E−01 
                  4.235586E−01 
                  1.099991E−01 
               
               
                 A8 
                 −2.103227E−01 
                 −6.977898E−02 
                  1.314064E−03 
                 −3.154896E−01 
                 −2.725211E−01 
                 −4.351227E−02 
               
               
                 A10 
                 −2.678530E−01 
                 −1.252425E−01 
                 −6.064637E−02 
                  2.342039E−01 
                  1.326518E−01 
                  1.145726E−02 
               
               
                 A12 
                  3.506000E−01 
                  2.892027E−01 
                  9.249015E−02 
                 −5.283409E−02 
                 −3.922772E−02 
                 −2.018059E−03 
               
               
                 A14 
                 −6.425914E−02 
                 −1.933433E−01 
                 −3.579175E−02 
                  1.482390E−02 
                  6.054290E−03 
                  2.134428E−04 
               
               
                 A16 
                 −6.100393E−02 
                  4.183590E−02 
                  3.161054E−03 
                 −1.111762E−03 
                 −3.754109E−04 
                 −1.063284E−05 
               
               
                   
               
            
           
         
       
     
     The imaging lens in Example 3 satisfies conditional expressions (1) to (15) as shown in Table 5. 
       FIG. 6  shows the spherical aberration (mm), the astigmatism (mm), and the distortion (%) of the imaging lens in Example 3. 
     EXAMPLE 4 
     The basic lens data is shown below in Table 4. 
     
       
         
           
               
             
               
                 TABLE 4 
               
               
                   
               
               
                 Example 4 
               
               
                 Unit mm 
               
               
                 f = 3.44 
               
               
                 Fno = 1.4 
               
               
                 ω(°) = 38.3 
               
               
                 ih = 2.91 
               
               
                 TTL = 3.61 
               
               
                   
               
             
            
               
                 Surface Data 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Surface 
                 Curvature 
                 Surface 
                 Refractive 
                 Abbe 
                   
               
               
                   
                 Number i 
                 Radius r 
                 Distance d 
                 Index Nd 
                 Number νd 
               
               
                   
                   
               
               
                   
                 (Object) 
                 Infinity 
                 infinity 
               
               
                   
                 1* 
                 1.626946 
                 0.6886 
                 1.544 
                 55.57 
                 (νd1) 
               
               
                   
                 2* 
                 8.2213 
                 0.0420 
               
               
                   
                 3* 
                 11.8535 
                 0.2300 
                 1.661 
                 20.37 
                 (νd2) 
               
               
                   
                 4* 
                 5.6089 
                 0.2580 
               
               
                   
                 5 (Stop) 
                 Infinity 
                 0.1683 
               
               
                   
                 6* 
                 4.1755 
                 0.3303 
                 1.544 
                 55.57 
                 (νd3) 
               
               
                   
                 7* 
                 5.8629 
                 0.2499 
               
               
                   
                 8* 
                 4.0431 
                 0.2290 
                 1.633 
                 23.52 
                 (νd4) 
               
               
                   
                 9* 
                 2.2648 
                 0.1740 
               
               
                   
                 10*  
                 3.3705 
                 0.4967 
                 1.544 
                 55.57 
                 (νd5) 
               
               
                   
                 11*  
                 −2.1389 
                 0.1949 
               
               
                   
                 12*  
                 19.3162 
                 0.3800 
                 1.544 
                 55.57 
                 (νd6) 
               
               
                   
                 13*  
                 1.1600 
                 0.3700 
               
               
                   
                 14  
                 Infinity 
                 0.2100 
                 1.517 
                 64.20 
               
               
                   
                 15  
                 Infinity 
                 0.3484 
               
               
                   
                 Image Plane 
                 Infinity 
               
               
                   
                   
               
            
           
           
               
            
               
                 Constituent Lens Data 
               
            
           
           
               
               
               
               
               
            
               
                 Lens 
                 Start Surface 
                 Focal Length 
                   
                 Composite Focal Length 
               
               
                   
               
               
                 1 
                 1 
                 3.598 
                 f234 
                 −7.077 
               
               
                 2 
                 3 
                 −16.353 
               
               
                 3 
                 6 
                 24.956 
               
               
                 4 
                 8 
                 −8.482 
               
               
                 5 
                 10 
                 2.485 
               
               
                 6 
                 12 
                 −2.286 
               
               
                   
               
            
           
           
               
               
            
               
                 Aspheric Surface Data 
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 First Surface 
                 Second Surface 
                 Third Surface 
                 Fourth Surface 
                 Sixth Surface 
                 Seventh Surface 
               
               
                   
               
               
                 k 
                 4.650145E−01 
                 −6.807935E+01 
                  9.000000E+01 
                 −1.641581E+01  
                 −9000000E+01  
                 2.579662E+01 
               
               
                 A4 
                 −5.436606E−02  
                 −1.534084E−01 
                 −2.101424E−01 
                 −3.474483E−02  
                 2.058137E−02 
                 −1.440144E−01  
               
               
                 A6 
                 8.502136E−02 
                  1.045000E−01 
                  2.831234E−01 
                 6.303872E−02 
                 −4.805425E−02  
                 1.410286E−01 
               
               
                 A8 
                 −1.720221E−01  
                  9.714180E−02 
                 −1.201909E−01 
                 3.900853E−02 
                 −1.925217E−01  
                 −3.599600E−01  
               
               
                 A10 
                 1.386486E−01 
                 −2.293090E−01 
                 −6.146194E−02 
                 −7.878531E−02  
                 3.902814E−01 
                 3.567147E−01 
               
               
                 A12 
                 −5.963227E−02  
                  1.430207E-01 
                  7.651942E−02 
                 7.245198E−03 
                 −3.497843E−01  
                 −2.553186E−01  
               
               
                 A14 
                 5.329615E−03 
                 −3.171423E−02 
                 −1.864880E−02 
                 2.511084E−02 
                 1.257731E−01 
                 8.011225E−02 
               
               
                 A16 
                 0.000000E+00 
                  0.000000E+00 
                  0.000000E+00 
                 0.000000E+00 
                 0.000000E+00 
                 0.000000E+00 
               
               
                   
               
               
                   
                 Eighth Surface 
                 Ninth Surface 
                 Tenth Surface 
                 Eleventh Surface 
                 Twelfth Surface 
                 Thirteenth Surface 
               
               
                   
               
               
                 k 
                  5.778851E+00 
                 −1.975464E+01 
                  2.425331E+00 
                 −9.704061E+00 
                  9.000000E+01 
                 −8.407133E+00 
               
               
                 A4 
                 −4.183232E−01 
                 −3.118326E−01 
                 −6.006068E−02 
                  2.620193E−02 
                 −5.211330E−01 
                 −1.832961E−01 
               
               
                 A6 
                  4.437189E−01 
                  1.970768E−01 
                 −8.520303E−02 
                  1.251110E−01 
                  4.270640E−01 
                  1.058335E−01 
               
               
                 A8 
                 −2.279514E−01 
                 −6.575957E−02 
                  5.917753E−04 
                 −3.149448E−01 
                 −2.725782E−01 
                 −4.258133E−02 
               
               
                 A10 
                 −2.746843E−01 
                 −1.282865E−01 
                 −5.784861E−02 
                  2.342704E−01 
                  1.327608E−01 
                  1.141069E−02 
               
               
                 A12 
                  3.688652E−01 
                  2.868699E−01 
                  9.354924E−02 
                 −8.280205E−02 
                 −3.918463E−02 
                 −2.029144E−03 
               
               
                 A14 
                 −6.627791E−02 
                 −1.934900E−01 
                 −3.691356E−02 
                  1.481968E−02 
                  6.062707E−03 
                  2.134956E−04 
               
               
                 A16 
                 −7.191544E−02 
                  4.205677E−02 
                  3.234076E−03 
                 −1.103796E−03 
                 −3.796598E−04 
                 −1.041536E−05 
               
               
                   
               
            
           
         
       
     
     The imaging lens in Example 4 satisfies conditional expressions (1) to (15) as shown in Table 5. 
       FIG. 8  shows the spherical aberration (mm), the astigmatism (mm), and the distortion (%) of the imaging lens in Example 4. 
     In table 5, values of conditional expressions (1) to (15) related to the Examples 1 to 4 are shown. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 5 
               
               
                   
               
               
                 Conditional expression 
                 Example1 
                 Example2 
                 Example3 
                 Example4 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 (1) 
                 νd4 
                 23.52 
                 23.52 
                 23.52 
                 23.52 
               
               
                 (2) 
                 (T4/f) × 100 
                 4.03 
                 4.34 
                 4.15 
                 5.06 
               
               
                 (3) 
                 (D2/f2) × 100 
                 −1.63 
                 −1.46 
                 −1.41 
                 −1.41 
               
               
                 (4) 
                 T1/T2 
                 0.09 
                 0.10 
                 0.07 
                 0.10 
               
               
                 (5) 
                 |r7|/f 
                 1.27 
                 1.18 
                 1.22 
                 1.18 
               
               
                 (6) 
                 (T3/f) × 100 
                 7.00 
                 7.23 
                 7.57 
                 7.27 
               
               
                 (7) 
                 f4/f 
                 −1.75 
                 −2.42 
                 −1.97 
                 −2.47 
               
               
                 (8) 
                 f5/f 
                 0.71 
                 0.75 
                 0.67 
                 0.72 
               
               
                 (9) 
                 f1/f4 
                 −0.58 
                 −0.42 
                 −0.51 
                 −0.42 
               
               
                 (10)  
                 r9/r10 
                 −1.29 
                 −1.44 
                 −1.11 
                 −1.58 
               
               
                 (11)  
                 r3/f 
                 3.48 
                 3.41 
                 4.17 
                 3.45 
               
               
                 (12)  
                 |r9|/f 
                 0.86 
                 0.96 
                 0.74 
                 0.98 
               
               
                 (13)  
                 f6/1 
                 −0.75 
                 −0.70 
                 −0.67 
                 −0.67 
               
               
                 (14)  
                 f1/f2 
                 −0.25 
                 −0.23 
                 −0.22 
                 −0.22 
               
               
                 (15)  
                 f234/f 
                 −1.43 
                 −1.92 
                 −1.54 
                 −2.06 
               
               
                   
               
            
           
         
       
     
     When the imaging lens according to the present invention is adopted to a product with the camera function, there is realized contribution to the wide field of view, the low-profileness and the low F-number of the camera and also high performance thereof. 
     DESCRIPTION OF REFERENCE NUMERALS 
     ST: an aperture stop 
     L 1 : first lens 
     L 2 : second lens 
     L 3 : third lens 
     L 4 : fourth lens 
     L 5 : fifth lens 
     L 6 : sixth lensih: maximum image height 
     IR: filter 
     IMG: imaging plane