Patent ID: 12222581

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, and7are schematic views of the imaging lenses in Examples 1 to 4 according to the embodiments of the present invention, respectively.

As shown inFIG.1, the imaging lens according to the present invention comprises, in order from an object side to an image side, a first lens L1with positive refractive power, a second lens L2with negative refractive power, a third lens L3, a fourth lens L4with positive refractive power, and a fifth lens L5with negative refractive power, wherein said first lens L1has an object-side surface being convex in a paraxial region, said third lens L3has an image-side surface being convex in a paraxial region, and said fifth lens L5is formed in a biconcave shape having an object-side surface being concave and an image-side surface being concave in the paraxial region.

A filter IR such as an IR cut filter or a cover glass is arranged between the fifth lens L5and an image plane IMG (namely, the image plane of an image sensor). The filter IR is omissible.

By arranging an aperture stop ST on the object side of the first lens L1, correction of aberrations and control of an incident angle of the light ray of high image height to an image sensor become facilitated.

The first lens L1has the positive refractive power and is formed in a meniscus shape having the object-side surface being convex and an image-side surface being concave in the paraxial region. Furthermore, both-side surfaces of the first lens L1are formed as aspheric surfaces. Therefore, spherical aberration, coma aberration, astigmatism, field curvature, and distortion are suppressed.

The second lens L2has the negative refractive power and is formed in a meniscus shape having an object-side surface being convex and an image-side surface being concave in the paraxial region. Furthermore, both-side surfaces of the second lens L2are formed as aspheric surfaces. Therefore, chromatic aberration, the astigmatism, the field curvature, and the distortion are properly corrected.

The third lens L3has the negative refractive power and is formed in a meniscus shape having an object-side surface being concave and the image-side surface being convex in the paraxial region. Furthermore, both-side surfaces of the third lens L3are formed as aspheric surfaces. Therefore, the chromatic aberration, the astigmatism, the field curvature, and the distortion are properly corrected.

The refractive power of the third lens L3may be positive as in Examples 2 and 3 shown inFIGS.3and5. The third lens L3having the positive refractive power is favorable for reduction in the profile.

The fourth lens L4has the positive refractive power and is formed in a meniscus shape having an object-side surface being concave and an image-side surface being convex in the paraxial region. Furthermore, both-side surfaces of the fourth lens L4are formed as aspheric surfaces. Therefore, reduction in the profile is achieved, and the spherical aberration, the coma aberration, the astigmatism, the field curvature, and the distortion are properly corrected.

The fifth lens L5has the negative refractive power, and is formed in a biconcave shape having the object-side surface being concave and the image-side surface being concave in the paraxial region. Furthermore, both-side surfaces of the fifth lens L5are formed as aspheric surfaces. Therefore, the chromatic aberration, the astigmatism, the field curvature, and the distortion are corrected. Due to the image-side surface of the fifth lens L5being concave in the paraxial region, a back focus is secured while maintaining the low profile.

The image-side surface of the fifth lens L5is formed as the aspheric surface having at least one pole point in a position off the optical axis X. Therefore, the astigmatism, the field curvature, and the distortion are more properly corrected.

Regarding the imaging lens according to the present embodiments, it is preferable that all lenses of the first lens L1to the fifth lens L5are single lenses. Configuration only with the single lenses can frequently use the aspheric surfaces. In the present embodiments, all lens surfaces are formed as appropriate aspheric surfaces, and the aberrations are properly corrected. Furthermore, in comparison with the case in which a cemented lens is used, workload is reduced, and manufacturing in low cost is available.

Furthermore, the imaging lens according to the present embodiments makes manufacturing facilitated by using a plastic material for 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 applied in accordance with required performance.

The imaging lens according to the present embodiments shows preferable effects by satisfying the following conditional expressions (1) to (21),
−9.00<r3/r7/D2<−4.20  (1)
0.10<r5/r6  (2)
r7/T2<−9.00  (3)
0.50<r10/(D5−T4)<9.50  (4)
17.00<vd3<34.00  (5)
1.00<r2/D1<20.50  (6)
0.50<r1×r2/f<3.85  (7)
0.01<r2/r5/r8<0.70  (8)
−14.50<r5/r2<−2.50  (9)
1.00<r2/f1<3.60  (10)
0.15<r2/r3/r10<1.00  (11)
−8.15<r3/r7/(D4−D2)<−2.50  (12)
r5/f<−4.80  (13)
−14.50<r6/f<−2.50  (14)
−9.50<r6/r2<−1.30  (15)
−70.00<r7/T4<−19.00  (16)
−4.50<r9/f<−0.65  (17)
−0.10<r10/r5<−0.01  (18)
−4.50<(D2/f2)×100<−1.70  (19)
0.00<(D3/|f3|)×100<2.50  (20)
0.10<(f4/f)+(f5/f)<0.60  (21)wherevd3: an abbe number at d-ray of the third lens L3,D1: a thickness along the optical axis X of the first lens L1,D2: a thickness along the optical axis X of the second lens L2,D3: a thickness along the optical axis X of the third lens L3,D4: a thickness along the optical axis X of the fourth lens L4,D5: a thickness along the optical axis X of the fifth lens L5,T2: a distance along the optical axis X from an image-side surface of the second lens L2to an object-side surface of the third lens L3,T4: a distance along the optical axis X from an image-side surface of the fourth lens L4to an object-side surface of the fifth lens L5,f: a focal length of the overall optical system of the imaging lens,f1: a focal length of the first lens L1,f2: a focal length of the second lens L2,f3: a focal length of the third lens L3,f4: a focal length of the fourth lens L4,f5: a focal length of the fifth lens L5,r1: a paraxial curvature radius of an object-side surface of the first lens L1,r2: a paraxial curvature radius of an image-side surface of the first lens L1,r3: a paraxial curvature radius of an object-side surface of the second lens L2,r5: a paraxial curvature radius of an object-side surface of the third lens L3,r6: a paraxial curvature radius of an image-side surface of the third lens L3,r7: a paraxial curvature radius of an object-side surface of the fourth lens L4,r8: a paraxial curvature radius of an image-side surface of the fourth lens L4,r9: a paraxial curvature radius of an object-side surface of the fifth lens L5, andr10: a paraxial curvature radius of an image-side surface of the fifth lens L5.

It is not necessary to satisfy the above all conditional expressions. An operational advantage corresponding to each conditional expression can be obtained by satisfying the conditional expression individually.

The imaging lens according to the present embodiments shows further preferable effects by satisfying the following conditional expressions (1a) to (21a),
−8.40<r3/r7/D2<−4.70  (1a)
0.40<r5/r6<100.00  (2a)
−100.00<r7/T2<−14.00  (3a)
2.50<r10/(D5−T4)<7.50  (4a)
21.00<vd3<30.00  (5a)
5.00<r2/D1<16.00  (6a)
1.20<r1×r2/f<3.00  (7a)
0.05<r2/r5/r8<0.40  (8a)
−12.00<r5/r2<−3.50  (9a)
1.50<r2/f1<3.00  (10a)
0.25<r2/r3/r10<0.80  (11a)
−6.80<r3/r7/(D4−D2)<−3.00  (12a)
−100.00<r5/f<−5.60  (13a)
−12.00<r6/f<−3.75  (14a)
−8.00<r6/r2<−2.00  (15a)
−55.00<r7/T4<−23.50  (16a)
−3.50<r9/f<−1.25  (17a)
−0.075<r10/r5<−0.015  (18a)
−3.25<(D2/f2)×100<−2.10  (19a)
0.04<(D3/|f3|)×100<1.60  (20a)
0.20<(f4/f)+(f5/f)<0.45.  (21a)

The signs in the above conditional expressions have the same meanings as those in the paragraph before the preceding paragraph. Additionally, only lower limits or upper limits of the conditional expressions (1a) to (21a) may be applied to the corresponding conditional expressions (1) to (21).

In this embodiment, the aspheric shapes of the aspheric surfaces of the 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 A4, A6, A8, A10, A12, A14, A16, A18 and A20 denote aspheric surface coefficients.

Z=H2R1+1-(k+1)⁢H2R2+A4⁢H4+A6⁢H6+A8⁢H8+A10⁢H10+A12⁢H12+A14⁢H14+A16⁢H16+A18⁢H18+A20⁢H20[Equation⁢1]

Next, examples of the imaging lens according to this embodiment will be explained. In each example, f denotes a focal length of the overall optical system of the imaging lens, Fno denotes a F-number, w denotes a half field of view, ih denotes a maximum image height, and TTL denotes a total track length. Additionally, i denotes a surface number counted from the object side, r denotes a paraxial curvature radius, d denotes a distance between 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 1Example 1Unit mmf = 3.70Fno = 2.00ω(°) = 39.3h = 3.07TTL = 4.12Surface DatairdNdνd(Object)InfinityInfinity1 (Stop)Infinity−0.35882*1.22030.60971.53555.69(νd1)3*5.56630.05374*12.16600.20001.66120.37(νd2)5*3.47330.30976*−28.66250.40001.61425.59(νd3)7*−31.32080.42658*−7.85070.51461.53555.69(νd4)9*−1.37060.175310*−7.19760.51271.53555.69(νd5)11*1.39520.500012Infinity0.21001.51764.2013Infinity0.2838Image PlaneConstituent Lens DataLensStart SurfaceFocal LengthTTL to diagonal length of effective image area122.7860.6724−7.42536−583.224483.021510−2.141Aspheric Surface Data2nd Surface3rd Surface4th Surface5th Surface6th Surfacek−6.442009E−010.000000E+000.000000E+008.019344E+000.000000E+00A41.998263E−02−6.092753E−02−7.647532E−028.385006E−03−1.777942E−01A62.042566E−01−1.137059E+00−8.891448E−01−3.166782E−01−1.649236E−01A8−7.227408E−016.458684E+006.960006E+004.001527E+007.290064E−01A101.603520E+00−1.687084E+01−1.995914E+01−1.334958E+01−2.078353E+00A12−2.035530E+002.391524E+013.045298E+012.417790E+013.428064E+00A141.380844E+00−1.792066E+01−2.425421E+01−2.282176E+01−3.268401E+00A16−4.538982E−015.544517E+008.047653E+009.702170E+001.371069E+00A180.000000E+000.000000E+000.000000E+000.000000E+000.000000E+00A200.000000E+000.000000E+000.000000E+000.000000E+000.000000E+007th Surface8th Surface9th Surface10th Surface11th Surfacek0.000000E+000.000000E+00−5.753058E+001.312877E+00−8.511152E+00A4−1.472273E−017.623529E−02−5.506982E−02−3.068550E−01−1.868552E−01A61.289102E−01−3.659808E−01−7.944182E−021.465386E−011.469933E−01A8−6.545542E−016.318437E−011.969281E−015.435976E−02−8.930352E−02A101.657575E+00−8.232734E−01−2.030920E−01−7.353972E−023.910967E−02A12−2.219747E+007.393829E−011.608408E−013.094931E−02−1.207762E−02A141.561463E+00−4.593076E−01−9.067754E−02−7.069209E−032.509478E−03A16−4.330539E−011.959055E−013.109594E−029.387802E−04−3.314435E−04A180.000000E+00−5.032627E−02−5.690775E−03−6.835416E−052.525655E−05A200.000000E+005.635460E−034.250815E−042.108956E−06−8.512804E−07

The imaging lens in Example 1 achieves a ratio of a total track length to a diagonal length of an effective image area of the image sensor of 0.67, and a F number of 2.00. As shown in Table 4, the imaging lens in Example 1 satisfies the conditional expressions (1) to (21).

FIG.2shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens in Example 1. The spherical aberration diagram shows the amount of aberration at each wavelength 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 the amount of aberration at d-ray on tangential image surface T (broken line), respectively (same asFIGS.4,6, and8). As shown inFIG.2, each aberration is corrected excellently.

Example 2

The basic lens data is shown below in Table 2.

TABLE 2Example 2Unit mmf = 3.72Fno = 2.00ω(°) = 39.2h = 3.07TTL = 4.12Surface DatairdNdνd(Object)InfinityInfinity1 (Stop)Infinity−0.36002*1.27080.58741.53555.69(νd1)3*6.72370.06054*7.51380.18181.66120.37(νd2)5*2.66220.36396*−64.79710.27951.61425.59(νd3)7*−18.56040.48658*−6.99080.48981.53555.69(νd4)9*−1.42230.253610*−10.33400.49301.53555.69(νd5)11*1.39530.200012Infinity0.21001.51764.2013Infinity0.5848Image PlaneConstituent Lens DataLensStart SurfaceFocal LengthTTL to diagonal length of effective image area122.8240.6724−6.3343642.250483.239510−2.265Aspheric Surface Data2nd Surface3rd Surface4th Surface5th Surface6th Surfacek−6.814540E−013.773666E+00−1.484195E+013.611762E+000.000000E+00A42.002590E−02−3.683668E−02−8.386084E−02−2.020477E−02−1.897020E−01A61.928205E−01−1.145835E+00−8.930117E−01−3.026823E−01−1.220860E−01A8−7.164505E−016.455213E+006.954985E+003.971371E+006.793398E−01A101.606966E+00−1.686276E+01−1.999418E+01−1.339128E+01−2.116079E+00A12−2.035991E+002.393143E+013.043325E+012.430755E+013.597545E+00A141.373484E+00−1.793817E+01−2.417960E+01−2.287393E+01−3.070937E+00A16−4.241757E−015.541887E+007.920066E+009.125510E+001.281882E+00A180.000000E+000.000000E+000.000000E+000.000000E+000.000000E+00A200.000000E+000.000000E+000.000000E+000.000000E+000.000000E+007th Surface8th Surface9th Surface10th Surface11th Surfacek1.345107E+01−8.666258E+01−5.292544E+009.991145E+00−7.901635E+00A4−1.730784E−013.520168E−02−3.703843E−02−2.907995E−01−1.803371E−01A61.265224E−01−2.376705E−01−9.956345E−029.289225E−021.294682E−01A8−6.713836E−011.440507E−011.363385E−011.064997E−01−7.195563E−02A101.652057E+002.312053E−01−6.037314E−02−9.937681E−022.986948E−02A12−2.205513E+00−5.847606E−012.288870E−023.743879E−02−9.070804E−03A141.589519E+005.271167E−01−1.700146E−02−7.643431E−031.911996E−03A16−4.263115E−01−2.344631E−018.511704E−038.595529E−04−2.605055E−04A180.000000E+005.151836E−02−1.969446E−03−4.721221E−052.036921E−05A200.000000E+00−4.474406E−031.701966E−048.255870E−07−6.862909E−07

The imaging lens in Example 2 achieves a ratio of a total track length to a diagonal length of an effective image area of the image sensor of 0.67, and a F number of 2.00. As shown in Table 4, the imaging lens in Example 2 satisfies the conditional expressions (1) to (21).

FIG.4shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens in Example 2. As shown inFIG.4, each aberration is corrected excellently.

Example 3

The basic lens data is shown below in Table 3.

TABLE 3Example 3Unit mmf = 3.71Fno = 2.00ω(°) = 39.2h = 3.07TTL = 4.12Surface DatairdNdνd(Object)InfinityInfinity1 (Stop)Infinity−0.36002*1.25670.60291.53555.69(νd1)3*6.54070.05504*8.55690.20001.66120.37(νd2)5*2.92020.35166*−29.71050.35001.61425.59(νd3)7*−22.90160.43238*−8.22050.48271.53555.69(νd4)9*−1.44070.243710*−7.43510.49011.53555.69(νd5)11*1.45870.200012Infinity0.21001.51764.2013Infinity0.5725Image PlaneConstituent Lens DataLensStart SurfaceFocal LengthTTL to diagonal length of effective image area122.7970.6724−6.80536159.572483.187510−2.237Aspheric Surface Data2nd Surface3rd Surface4th Surface5th Surface6th Surfacek−6.668214E−01−5.114133E+00−1.489161E+014.608653E+00−3.488642E+01A41.989012E−02−4.179678E−02−8.472497E−02−1.169848E−02−1.763371E−01A61.978578E−01−1.140865E+00−8.944283E−01−3.047677E−01−1.238215E−01A8−7.201051E−016.466479E+006.951172E+003.965710E+007.063517E−01A101.604464E+00−1.686523E+01−1.998679E+01−1.341870E+01−2.067942E+00A12−2.031517E+002.389860E+013.042297E+012.426961E+013.518877E+00A141.390359E+00−1.796195E+01−2.424807E+01−2.271808E+01−3.284861E+00A16−4.460032E−015.594201E+008.029214E+009.133377E+001.418944E+00A180.000000E+000.000000E+000.000000E+000.000000E+000.000000E+00A200.000000E+000.000000E+000.000000E+000.000000E+000.000000E+007th Surface8th Surface9th Surface10th Surface11th Surfacek−9.083439E+00−9.000000E+01−5.584872E+003.396063E+00−8.683961E+00A4−1.602831E−013.818288E−02−3.645676E−02−2.857302E−01−1.803096E−01A61.399731E−01−2.430883E−01−9.759621E−029.306931E−021.293231E−01A8−6.647682E−011.451299E−011.363715E−011.064962E−01−7.210428E−02A101.653086E+002.316909E−01−6.054163E−02−9.939096E−022.987608E−02A12−2.212561E+00−5.846337E−012.287392E−023.743477E−02−9.067645E−03A141.573961E+005.271569E−01−1.700597E−02−7.643593E−031.912119E−03A16−4.364162E−01−2.345443E−018.514921E−038.597623E−04−2.605355E−04A180.000000E+005.149460E−02−1.968887E−03−4.716460E−052.036550E−05A200.000000E+00−4.465142E−031.696616E−048.158509E−07−6.854058E−07

The imaging lens in Example 3 achieves a ratio of a total track length to a diagonal length of an effective image area of the image sensor of 0.67, and a F number of 2.00. As shown in Table 4, the imaging lens in Example 3 satisfies the conditional expressions (1) to (21).

FIG.6shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens in Example 3. As shown inFIG.6, each aberration is corrected excellently.

Example 4

The basic lens data is shown below in Table 4.

TABLE 4Example 4Unit mmf = 3.71Fno = 2.00ω(°) = 39.3h = 3.07TTL = 4.12Surface DatairdNdνd(Object)InfinityInfinity1 (Stop)Infinity−0.36002*1.22570.60721.53555.69(νd1)3*5.62290.05304*11.12410.20001.66120.37(νd2)5*3.42550.33056*−24.20050.40001.61425.59(νd3)7*−35.37640.43108*−7.39330.47701.53555.69(νd4)9*−1.35090.196810*−6.80390.50911.53555.69(νd5)11*1.40850.200012Infinity0.21001.51764.2013Infinity0.5759Image PlaneConstituent Lens DataLensStart SurfaceFocal LengthTTL to diagonal length of effective image area122.7960.6724−7.56936−126.439483.008510−2.136Aspheric Surface Data2nd Surface3rd Surface4th Surface5th Surface6th Surfacek−6.447220E−01−1.473892E+013.313859E+017.778026E+006.421644E+00A41.998997E−02−4.811340E−02−8.002167E−026.901398E−03−1.757343E−01A62.038249E−01−1.137164E+00−8.911405E−01−3.170360E−01−1.624627E−01A8−7.225588E−016.461367E+006.958445E+003.999424E+007.313763E−01A101.604142E+00−1.687005E+01−1.996043E+01−1.335909E+01−2.079541E+00A12−2.034835E+002.391329E+013.045276E+012.416051E+013.414660E+00A141.381998E+00−1.792248E+01−2.425220E+01−2.282590E+01−3.286241E+00A16−4.515097E−015.547597E+008.048227E+009.765125E+001.456672E+00A180.000000E+000.000000E+000.000000E+000.000000E+000.000000E+00A200.000000E+000.000000E+000.000000E+000.000000E+000.000000E+007th Surface8th Surface9th Surface10th Surface11th Surfacek−1.628317E+01−9.000000E+01−5.729914E+001.712568E+00−8.915158E+00A4−1.454269E−015.130491E−02−4.198275E−02−2.845923E−01−1.781813E−01A61.278564E−01−2.514247E−01−9.240765E−029.318556E−021.287571E−01A8−6.571175E−011.491593E−011.367761E−011.065050E−01−7.218330E−02A101.655746E+002.340949E−01−6.079051E−02−9.938734E−022.987495E−02A12−2.220270E+00−5.852905E−012.279080E−023.743269E−02−9.066304E−03A141.561681E+005.265645E−01−1.701110E−02−7.643764E−031.912349E−03A16−4.325525E−01−2.346963E−018.525327E−038.598517E−04−2.605403E−04A180.000000E+005.155298E−02−1.965272E−03−4.715256E−052.036466E−05A200.000000E+00−4.449901E−031.678877E−048.127140E−07−6.845785E−07

The imaging lens in Example 4 achieves a ratio of a total track length to a diagonal length of an effective image area of the image sensor of 0.67, and a F number of 2.00. As shown in Table 4, the imaging lens in Example 4 satisfies the conditional expressions (1) to (21).

FIG.8shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens in Example 4. As shown inFIG.8, each aberration is corrected excellently.

In table 5, values of conditional expressions (1) to (21) related to Examples 1 to 4 are shown.

TABLE 5Conditional ExpressionExample 1Example 2Example 3Example 4(1)r3/r7/D2−7.75−5.91−5.20−7.52(2)r5/r60.923.491.300.68(3)r7/T2−25.35−19.21−23.38−22.37(4)r10/(D5 − T4)4.145.835.924.51(5)νd 325.5925.5925.5925.59(6)r2/D19.1311.4510.859.26(7)r1 × r2/f1.832.302.221.86(8)r2/r5/r80.140.070.150.17(9)r5/r2−5.15−9.64−4.54−4.30(10)r2/f12.002.382.342.01(11)r2/r3/r100.330.640.520.36(12)r3/r7/(D4 − D2)−4.93−3.49−3.68−5.43(13)r5/f−7.74−17.44−8.01−6.52(14)r6/f−8.46−5.00−6.17−9.53(15)r6/r2−5.63−2.76−3.50−6.29(16)r7/T4−44.78−27.57−33.73−37.57(17)r9/f−1.94−2.78−2.00−1.83(18)r10/r5−0.049−0.022−0.049−0.058(19)(D2/f2) × 100−2.69−2.87−2.94−2.64(20)(D3/|f3|) × 1000.070.660.220.32(21)(f4/f) + (f5/f)0.240.260.260.24

When the imaging lens according to the present invention is adopted to a product with the camera function, there is realized contribution to the low profile and the low F-number of the camera, and also high performance thereof.

DESCRIPTION OF REFERENCE NUMERALS

ST: aperture stopL1: first lensL2: second lensL3: third lensL4: fourth lensL5: fifth lensIR: filterIMG: imaging plane