JP2011257447A - Imaging lens and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a downsized large-diameter imaging lens, having excellent optical characteristics corresponding to a high-count pixel imaging device.SOLUTION: An imaging lens comprises, in order from an object side, a first lens having a positive refractive power, a meniscus-shaped second lens having a negative refractive power with a concave surface facing an image side, a third lens having a positive refractive power, a meniscus-shaped fourth lens having a positive refractive power with a concave surface facing the object side in vicinity of an optical axis, and a fifth lens having a negative refractive power in vicinity of the optical axis and a positive refractive power in a peripheral part, and satisfies the following conditional expression (1), conditional expression (2), and conditional expression(3): (1) ν-ν>35, (2) ν>50, and (3) ν>50.

Description

  The present invention relates to an imaging lens and an imaging apparatus, and is suitable for application to a large aperture imaging lens having an F number of about 1.8, for example, and a solid state such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). The present invention is suitable for application to a small-sized imaging device such as a digital still camera using an imaging device, a mobile phone with a camera, or the like.

  2. Description of the Related Art Conventionally, a mobile phone with a camera and a digital still camera on which an imaging device using a solid-state imaging device such as a CCD or CMOS is mounted are known. In such an imaging apparatus, further miniaturization is required, and an imaging lens mounted on the imaging apparatus is also required to be small and have a short overall length.

  In recent years, even in a small imaging device such as a mobile phone with a camera, the number of pixels of an imaging element has been increased along with the miniaturization. For example, a model equipped with a high pixel imaging element of 8 million pixels or more has become widespread. .

  On the other hand, in such an imaging device, a brighter lens having a larger aperture is required in order to prevent a decrease in sensitivity of the imaging element and an increase in noise due to a narrow cell pitch.

  As such a small and high-performance imaging lens, a lens having a four-lens configuration is currently mainstream (see, for example, Patent Document 1 and Patent Document 2).

JP 2009-265245 A JP 2010-49113 A

  The imaging lenses of Patent Document 1 and Patent Document 2 are four-lens imaging lenses corresponding to current high-pixel imaging elements, and are small and high by correcting various aberrations in a balanced manner while suppressing the optical total length. Ensures optical performance.

  However, Patent Document 1 and Patent Document 2 optimize the optical performance and the optical total length by using an imaging lens having an F number of about 2.8. If the aperture is increased to about 1.8, correction of spherical aberration of axial aberration, coma aberration of off-axis aberration, and curvature of field becomes insufficient, and it is difficult to ensure the required optical performance. There was a problem.

  Further, in order to further improve the optical performance, it is necessary to further suppress the axial chromatic aberration. However, in the configurations described in Patent Document 1 and Patent Document 2, the axial chromatic aberration is corrected while suppressing the total optical length. There is a problem that it is difficult to ensure the high resolution performance required as the diameter increases.

  The present invention has been made in consideration of the above points, and intends to propose a small-sized and large-diameter imaging lens and an imaging apparatus using the imaging lens having good optical characteristics corresponding to a high-pixel imaging device. To do.

In order to solve this problem, in the imaging lens of the present invention, in order from the object side, a first lens having a positive refractive power, and a meniscus second lens having a negative refractive power with a concave surface facing the image side, A third lens having positive refractive power, a meniscus fourth lens having positive refractive power with a concave surface facing the object side in the vicinity of the optical axis, and a peripheral portion having negative refractive power in the vicinity of the optical axis And a fifth lens having a positive refractive power so as to satisfy the following conditional expression (1), conditional expression (2) and conditional expression (3).
(1) ν ₁ −ν ₂ > 35
(2) ν ₃ > 50
(3) ν ₄ > 50
However,
ν ₁ : Abbe number at the d-line (wavelength 587.6 nm) of the first lens ν ₂ : Abbe number at the d-line (wavelength 587.6 nm) of the second lens ν ₃ : d-line (wavelength 587.6 nm) of the third lens ) Abbe number ν _{4 in} (): The Abbe number in the d-line (wavelength 587.6 nm) of the fourth lens.

  Conditional expression (1) represents the difference between the Abbe number of the first lens at the d-line and the Abbe number of the second lens at the d-line, and conditional expression (2) represents the Abbe number of the third lens at the d-line. 3) defines the Abbe number of the fourth lens at the d-line, and is a condition for satisfactorily correcting chromatic aberration occurring in the lens system.

  In this imaging lens, it is difficult to correct the axial chromatic aberration required for increasing the diameter of the F number of about 1.8 if the specified values of the conditional expressions (1), (2), and (3) are not satisfied. It becomes.

  As described above, the imaging lens of the present invention can satisfactorily correct the longitudinal chromatic aberration by satisfying the conditional expressions (1), (2), and (3).

  As a result, the imaging lens of the present invention is small and large with good optical performance in which spherical aberration of on-axis aberration, coma aberration of off-axis aberration, and field curvature are corrected in a well-balanced manner with respect to a high pixel imaging device. An imaging lens having a caliber can be configured.

  In the imaging lens of the present invention, it is possible to constitute a small and large-diameter imaging lens having high resolution performance in which axial chromatic aberration is well corrected while suppressing the optical total length with respect to a high pixel imaging device. Has been made.

Further, the imaging lens of the present invention is configured to satisfy the following conditional expression (4).
(4) 0.4 <f ₃ / f ₄ <4.5
However,
f ₃ : focal length of the third lens f ₄ : focal length of the fourth lens.

Condition (4), which defines the ratio between the focal length f ₄ of the focal length f ₃ of the third lens fourth lens, the balance between the refractive power and the refractive power of the fourth lens in the third lens Is limiting.

  In this imaging lens, if the upper limit value of conditional expression (4) is not satisfied, the power of the third lens becomes too weak, it becomes difficult to correct axial chromatic aberration, and good optical performance cannot be maintained. On the other hand, if the value falls outside the lower limit, the power of the third lens becomes strong, which is advantageous in terms of aberration correction. However, the power of the fourth lens becomes too weak and the total optical length increases, and this lens system can be downsized. It becomes difficult.

  Thus, in the imaging lens of the present invention, by satisfying conditional expression (4), the optical total length can be suppressed while effectively correcting axial chromatic aberration and ensuring good optical performance. Yes.

Furthermore, the imaging lens of the present invention is configured to satisfy the following conditional expression (5).
(5) 0.55 <| f ₁ / f ₂ | <1.0
However,
f ₁ : focal length of the first lens f ₂ : focal length of the second lens.

The conditional expression (5), the focal length f ₁ of the first lens is intended to define the ratio of the focal length f ₂ of the second lens, the balance of the refractive power and the refractive power of the second lens of the first lens Is limiting.

  In this imaging lens, if the upper limit value of conditional expression (5) is exceeded, the power of the second lens becomes strong, which is advantageous in terms of aberration correction, but the power of the second lens becomes too strong and the optical total length increases. This makes it difficult to reduce the size of the lens system. On the other hand, if the lower limit is exceeded, the power of the second lens becomes too weak, making it difficult to correct axial chromatic aberration, and good optical performance cannot be maintained.

  Thus, in the imaging lens of the present invention, by satisfying conditional expression (5), the optical total length can be suppressed while effectively correcting axial chromatic aberration and ensuring good optical performance. Yes.

Furthermore, the imaging lens of the present invention is configured to satisfy the following conditional expressions (6) and (7).
(6) 0.4 <| f ₅ /f|<2.0
(7) ν ₅ > 50
However,
f: focal length of the entire lens system f ₅ : focal length ν _{5 of} the fifth lens: Abbe number at the d-line (wavelength 587.6 nm) of the fifth lens.

Condition (6) is intended to define the ratio of the focal length f ₅ and the lens focal length f of the fifth lens, which limits the power of the fifth lens.

  In this imaging lens, if the upper limit value of conditional expression (6) is exceeded, the power of the fifth lens becomes weak, which is advantageous in terms of aberration correction, but the total optical length increases, making it difficult to reduce the size of this lens system. turn into. On the other hand, if the lower limit is exceeded, the power of the fifth lens becomes too strong, and it becomes difficult to correct in a well-balanced field curvature that occurs at an intermediate image height (for example, 20 to 50% higher) from the center.

  Conditional expression (7) defines the Abbe number of the fifth lens at the d-line, and if it falls below this specified value, it is difficult to correct axial chromatic aberration and lateral chromatic aberration in a well-balanced manner. The performance cannot be maintained.

  As described above, in the imaging lens of the present invention, by satisfying the conditional expressions (6) and (7), the axial chromatic aberration and the lateral chromatic aberration are corrected in a well-balanced manner, and the excellent optical performance corresponding to the high pixel imaging element is achieved. The optical total length can be suppressed while securing the above.

  Furthermore, in the imaging lens of the present invention, the aperture stop for adjusting the light amount is arranged on the object side with respect to the object side surface of the second lens.

  Thereby, the imaging lens can reduce the chief ray incident angle of the imaging lens with respect to the optical axis by disposing the aperture stop closer to the object side than the object side surface of the second lens and making the exit pupil position as close as possible to the object side. Therefore, it is possible to improve the light receiving efficiency and avoid image quality deterioration due to color mixing.

  In addition, since the imaging lens is arranged at a position as close to the front of the optical system as possible, the exit pupil position is closer to the front than when the image pickup lens is placed closer to the image side than the object side surface of the second lens. Thus, the overall length of the lens system can be shortened.

Furthermore, the imaging apparatus of the present invention includes an imaging lens and an imaging element that converts an optical image formed by the imaging lens into an electrical signal.
The imaging lenses are in order from the object side.
A first lens having a positive refractive power;
A second meniscus lens having negative refractive power with a concave surface facing the image side;
A third lens having positive refractive power;
A meniscus fourth lens having a positive refractive power with a concave surface facing the object side in the vicinity of the optical axis;
A fifth lens having a negative refractive power in the vicinity of the optical axis and a positive refractive power in the peripheral portion,
The following conditional expression (1), conditional expression (2) and conditional expression (3) were satisfied.
(1) ν ₁ −ν ₂ > 35
(2) ν ₃ > 50
(3) ν ₄ > 50
However,
ν ₁ : Abbe number at the d-line (wavelength 587.6 nm) of the first lens ν ₂ : Abbe number at the d-line (wavelength 587.6 nm) of the second lens ν ₃ : d-line (wavelength 587.6 nm) of the third lens ) Abbe number ν _{4 in} (): The Abbe number in the d-line (wavelength 587.6 nm) of the fourth lens.

  Conditional expression (1) represents the difference between the Abbe number of the first lens at the d-line and the Abbe number of the second lens at the d-line, and conditional expression (2) represents the Abbe number of the third lens at the d-line. 3) defines the Abbe number of the fourth lens at the d-line, and is a condition for satisfactorily correcting chromatic aberration occurring in the lens system.

  In this imaging lens, it is difficult to correct the axial chromatic aberration required for increasing the diameter of the F number of about 1.8 if the specified values of the conditional expressions (1), (2), and (3) are not satisfied. It becomes.

  As described above, in the imaging lens in the imaging apparatus of the present invention, it is possible to satisfactorily correct the axial chromatic aberration by satisfying the conditional expressions (1), (2), and (3). Yes.

  As a result, in the image pickup apparatus of the present invention, a small and large optical device with good optical performance in which spherical aberration of on-axis aberration, coma aberration of off-axis aberration, and field curvature are corrected in a well-balanced manner with respect to a high pixel image pickup device. An imaging apparatus equipped with an aperture imaging lens can be configured.

  In the image pickup apparatus of the present invention, an image pickup device equipped with a small and large-diameter image pickup lens having high resolution performance, in which axial chromatic aberration is well corrected while suppressing the optical total length, is mounted on a high pixel image pickup device. The apparatus can be configured.

The imaging lens of the present invention has, in order from the object side, a first lens having a positive refractive power, a meniscus second lens having a negative refractive power with a concave surface facing the image side, and a positive refractive power. A third lens, a meniscus fourth lens having a positive refractive power with a concave surface facing the object side in the vicinity of the optical axis, and a negative refractive power in the vicinity of the optical axis and a positive refractive power in the peripheral portion The fifth lens is configured to satisfy the following conditional expression (1), conditional expression (2), and conditional expression (3).
(1) ν ₁ −ν ₂ > 35
(2) ν ₃ > 50
(3) ν ₄ > 50
However,
ν ₁ : Abbe number at the d-line (wavelength 587.6 nm) of the first lens ν ₂ : Abbe number at the d-line (wavelength 587.6 nm) of the second lens ν ₃ : d-line (wavelength 587.6 nm) of the third lens ) Abbe number ν _{4 in} (): The Abbe number in the d-line (wavelength 587.6 nm) of the fourth lens.

  The imaging lens can correct axial chromatic aberration satisfactorily by satisfying conditional expression (1), conditional expression (2), and conditional expression (3).

  As a result, the imaging lens is a small-sized and large-diameter imaging lens having excellent optical performance in which spherical aberration of on-axis aberration, coma aberration of off-axis aberration, and field curvature are corrected in a well-balanced manner relative to a high-pixel imaging device. Can be configured.

  Further, the imaging lens can constitute a small and large-diameter imaging lens having high resolution performance in which axial chromatic aberration is favorably corrected while suppressing the optical total length with respect to the high pixel imaging device.

The imaging device of the present invention includes an imaging lens and an imaging element that converts an optical image formed by the imaging lens into an electrical signal,
The imaging lenses are in order from the object side.
A first lens having a positive refractive power;
A second meniscus lens having negative refractive power with a concave surface facing the image side;
A third lens having positive refractive power;
A meniscus fourth lens having a positive refractive power with a concave surface facing the object side in the vicinity of the optical axis;
A fifth lens having a negative refractive power in the vicinity of the optical axis and a positive refractive power in the peripheral portion,
The following conditional expression (1), conditional expression (2) and conditional expression (3) were satisfied.
(1) ν ₁ −ν ₂ > 35
(2) ν ₃ > 50
(3) ν ₄ > 50
However,
ν ₁ : Abbe number at the d-line (wavelength 587.6 nm) of the first lens ν ₂ : Abbe number at the d-line (wavelength 587.6 nm) of the second lens ν ₃ : d-line (wavelength 587.6 nm) of the third lens ) Abbe number ν _{4 in} (): The Abbe number in the d-line (wavelength 587.6 nm) of the fourth lens.

  In the imaging lens in the imaging apparatus, the axial chromatic aberration can be favorably corrected by satisfying conditional expressions (1), (2), and (3).

  As a result, the image pickup apparatus is a small and large-diameter imaging lens having excellent optical performance, in which spherical aberration of axial aberration, coma aberration of off-axis aberration, and field curvature are corrected in a well-balanced manner with respect to a high-pixel imaging device. Can be configured.

  In addition, the imaging apparatus constitutes an imaging apparatus equipped with a small and large-diameter imaging lens having high resolution performance in which axial chromatic aberration is favorably corrected while suppressing the optical total length with respect to the high-pixel imaging element. be able to.

It is a rough-line sectional drawing which shows the structure of the imaging lens in a 1st numerical example. It is a characteristic curve figure which shows the various aberrations in the 1st numerical example. It is an approximate line sectional view showing composition of an image pick-up lens in the 2nd numerical example. It is a characteristic curve figure which shows the various aberrations in the 2nd numerical example. It is an approximate line sectional view showing composition of an image pick-up lens in the 3rd numerical example. It is a characteristic curve figure which shows the various aberrations in the 3rd numerical example. It is a rough-line perspective view which shows the external appearance structure (1) of the mobile telephone carrying an imaging device. It is a rough-line perspective view which shows the external appearance structure (2) of the mobile telephone carrying an imaging device. It is a rough block diagram which shows the circuit structure of a mobile telephone.

Hereinafter, modes for carrying out the invention (hereinafter referred to as embodiments) will be described. The description will be given in the following order.
1. Embodiment 2. FIG. Numerical examples corresponding to the embodiments (first numerical example to third numerical example)
3. 3. Imaging device and mobile phone Other embodiments

<1. Embodiment>
[1. Configuration of imaging lens]
The imaging lens of the present invention has, in order from the object side, a first lens having a positive refractive power, a meniscus second lens having a negative refractive power with a concave surface facing the image side, and a positive refractive power. A third lens, a meniscus fourth lens having a positive refractive power with a concave surface facing the object side in the vicinity of the optical axis, and a negative refractive power in the vicinity of the optical axis and a positive refractive power in the peripheral portion And a fifth lens. Incidentally, the imaging lens has a performance corresponding to a focal length of the entire lens system in a range of 24 to 40 [mm] in terms of 35 mm film.

In addition, the imaging lens is configured to satisfy the following conditional expression (1), conditional expression (2), and conditional expression (3).
(1) ν ₁ −ν ₂ > 35
(2) ν ₃ > 50
(3) ν ₄ > 50
However,
ν ₁ : Abbe number at the d-line (wavelength 587.6 nm) of the first lens ν ₂ : Abbe number at the d-line (wavelength 587.6 nm) of the second lens ν ₃ : d-line (wavelength 587.6 nm) of the third lens ) Abbe number ν _{4 in} (): The Abbe number in the d-line (wavelength 587.6 nm) of the fourth lens.

  Conditional expression (1) represents the difference between the Abbe number of the first lens at the d-line and the Abbe number of the second lens at the d-line, and conditional expression (2) represents the Abbe number of the third lens at the d-line. 3) defines the Abbe number of the fourth lens at the d-line, and is a condition for satisfactorily correcting chromatic aberration occurring in the lens system.

  In this imaging lens, it is difficult to correct the axial chromatic aberration required for increasing the diameter of the F number of about 1.8 if the specified values of the conditional expressions (1), (2), and (3) are not satisfied. It becomes.

  As described above, the imaging lens can satisfactorily correct the longitudinal chromatic aberration by satisfying the conditional expressions (1), (2), and (3).

  As a result, the imaging lens has good optical performance corresponding to the high-pixel imaging device, and the imaging lens can be reduced in size and increased in diameter.

The imaging lens is configured to satisfy the following conditional expression (4).
(4) 0.4 <f ₃ / f ₄ <4.5
However,
f ₃ : focal length of the third lens f ₄ : focal length of the fourth lens.

Condition (4), which defines the ratio between the focal length f ₄ of the focal length f ₃ of the third lens fourth lens, the balance between the refractive power and the refractive power of the fourth lens in the third lens Is limiting.

  In this imaging lens, if the upper limit of conditional expression (4) is exceeded, the power (refractive power) of the third lens becomes too weak, making it difficult to correct axial chromatic aberration, making it impossible to maintain good optical performance. End up. On the other hand, if the value falls outside the lower limit, the power of the third lens becomes strong, which is advantageous in terms of aberration correction. However, the power of the fourth lens becomes too weak and the total optical length increases, and this lens system can be downsized. It becomes difficult.

  Thus, in the imaging lens, by satisfying conditional expression (4), the optical total length can be suppressed while axial chromatic aberration is effectively corrected to ensure good optical performance.

Furthermore, the imaging lens is configured to satisfy the following conditional expression (5).
(5) 0.55 <| f ₁ / f ₂ | <1.0
However,
f ₁ : focal length of the first lens f ₂ : focal length of the second lens.

Condition (5), the focal length f ₁ of the first lens is intended to define the ratio of the focal length f ₂ of the second lens, the balance of the refractive power and the refractive power of the second lens of the first lens Is limiting.

  In this imaging lens, if the upper limit value of conditional expression (5) is exceeded, the power of the second lens becomes strong, which is advantageous in terms of aberration correction, but the power of the second lens becomes too strong and the optical total length increases. This makes it difficult to reduce the size of the lens system. On the other hand, if the lower limit is exceeded, the power of the second lens becomes too weak, making it difficult to correct axial chromatic aberration, and good optical performance cannot be maintained.

  As described above, in the imaging lens, by satisfying conditional expression (5), it is possible to suppress the total optical length while effectively correcting axial chromatic aberration and ensuring good optical performance.

Further, the imaging lens is configured to satisfy the following conditional expressions (6) and (7).
(6) 0.4 <| f ₅ /f|<2.0
(7) ν ₅ > 50
However,
f: focal length of the entire lens system f ₅ : focal length ν _{5 of} the fifth lens: Abbe number at the d-line (wavelength 587.6 nm) of the fifth lens.

Condition (6) is intended to define the ratio of the focal length f ₅ and the lens focal length f of the fifth lens, which limits the power of the fifth lens.

  In this imaging lens, if the upper limit value of conditional expression (6) is exceeded, the power of the fifth lens becomes weak, which is advantageous in terms of aberration correction, but the total optical length increases, making it difficult to reduce the size of this lens system. turn into. On the other hand, if the lower limit is exceeded, the power of the fifth lens becomes too strong, and it becomes difficult to correct in a well-balanced field curvature that occurs at an intermediate image height (for example, 20 to 50% higher) from the center.

  Conditional expression (7) defines the Abbe number of the fifth lens at the d-line, and if it falls below this specified value, it is difficult to correct axial chromatic aberration and lateral chromatic aberration in a well-balanced manner. The performance cannot be maintained.

  As described above, in the imaging lens, by satisfying conditional expressions (6) and (7), axial chromatic aberration and lateral chromatic aberration are corrected in a well-balanced manner to ensure good optical performance corresponding to a high pixel imaging element. However, the optical total length can be suppressed.

  In the imaging lens of the present invention, the aperture stop for adjusting the amount of light is disposed closer to the object side than the object side surface of the second lens.

  Thereby, the imaging lens can reduce the chief ray incident angle of the imaging lens with respect to the optical axis by disposing the aperture stop closer to the object side than the object side surface of the second lens and making the exit pupil position as close as possible to the object side. Therefore, it is possible to improve the light receiving efficiency and avoid image quality deterioration due to color mixing.

  In addition, since the imaging lens is arranged at a position as close to the front of the optical system as possible, the exit pupil position is closer to the front than when the image pickup lens is placed closer to the image side than the object side surface of the second lens. Thus, the overall length of the lens system can be shortened.

  Thus, in the imaging lens of the present invention, even if the aperture is increased to about F-number 1.8, for example, spherical aberration of on-axis aberration or coma aberration of off-axis aberration is applied to a high-pixel imaging device having 8 million pixels or more. The optical field curvature is excellently balanced and has good optical performance.

  In the present invention, for example, a small and large-diameter imaging lens having a high resolving performance in which axial chromatic aberration is favorably corrected while suppressing an optical total length is configured for a high-pixel imaging device having 8 million pixels or more. It is made to be able to do.

<2. Numerical Example Corresponding to Embodiment>
Next, numerical examples in which specific numerical values are applied to the imaging lens of the present invention will be described below with reference to the drawings and diagrams. Here, the meanings of the symbols used in the numerical examples are as follows.

  “FNo” is the F-number, “f” is the focal length of the entire lens system, “2ω” is the diagonal total angle of view, “Si” is the i-th surface number counted from the object side, and “Ri” is the i-th The radius of curvature of the i th surface, “di” is the axial upper surface distance between the i th surface and the i + 1 th surface from the object side, and “ni” is the refractive index of the i th lens at the d-line (wavelength 587.6 nm). , “Νi” is the Abbe number of the d-line (wavelength 587.6 nm) of the i-th lens.

  Regarding the surface number, “ASP” indicates that the surface is an aspherical surface, and regarding the radius of curvature, “∞” indicates that the surface is a flat surface.

  The imaging lens used in each numerical example has an aspherical lens surface, and the aspherical shape has an aspherical depth of “Z” and a height from the optical axis. “Y”, radius of curvature “R”, conic constant “K”, fourth-order, sixth-order, eighth-order and tenth-order aspheric coefficients “A”, “B”, “C” and “D”, respectively. Then, it is defined by the following formula 8.

[2-1. First numerical example]
In FIG. 1, reference numeral 1 denotes an image pickup lens in a first numerical example corresponding to the embodiment as a whole, and has a configuration having five lenses.

  The imaging lens 1 includes, in order from the object side, an aperture stop STO, a first lens L1 having a positive refractive power, a meniscus second lens L2 having a negative refractive power with a concave surface facing the image side, and a positive lens. A third lens L3 having a refractive power of 4 mm, a meniscus fourth lens L4 having a positive refractive power with a concave surface facing the object side in the vicinity of the optical axis, and a peripheral portion having a negative refractive power in the vicinity of the optical axis And a fifth lens L5 having a positive refractive power.

  In the imaging lens 1, a seal glass SG for protecting the image plane IMG is disposed between the fifth lens L5 and the image plane IMG.

  In the imaging lens 1 having such a configuration, the aperture stop STO is disposed in front of the object side.

  As a result, in this imaging lens 1, the aperture stop STO is disposed closer to the object side than the object side surface of the second lens L2, and the exit pupil position is as close to the object side as possible, whereby the principal ray incident angle of the imaging lens 1 with respect to the optical axis. Therefore, it is possible to improve the light receiving efficiency and avoid image quality deterioration due to color mixing.

  As described above, the imaging lens 1 has five imaging lenses and has the above-described power arrangement, thereby suppressing the overall optical length and suppressing the spherical aberration, which is an on-axis aberration, which becomes a problem when the aperture is increased. The coma aberration and the field curvature of the off-axis aberration can be corrected with a good balance.

  Table 1 shows lens data together with the F number FNo, the focal length f of the entire lens system, and the field angle 2ω when specific numerical values are applied to the imaging lens 1 of the first numerical example corresponding to the embodiment. Incidentally, the imaging lens 1 has a performance equivalent to a focal length of 33 [mm] in terms of 35 mm film. In Table 1, the radius of curvature Ri∞ means a plane.

  In this imaging lens 1, the object side surface (S2) of the first lens L1, the image side surface (S3) of the first lens L1, the object side surface (S4) of the second lens L2, and the second lens L2. An image side surface (S5), an object side surface (S6) of the third lens L3, an image side surface (S7) of the third lens L3, an object side surface (S8) of the fourth lens L4, and a fourth lens. The image side surface (S9) of the lens L4, the object side surface (S10) of the fifth lens L5, and the image side surface (S11) of the fifth lens L5 are formed in an aspheric shape.

Subsequently, the aspherical fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients “A”, “B”, “C”, and “D” in the imaging lens 1 of the first numerical example are represented by the conic coefficient “ Table 2 together with “K”. Incidentally, in Table 2, “E-02” represents an exponential expression with a base of 10, that is, “10 ⁻² ”, for example “0.12345E-05” represents “0.12345 × 10 ⁻⁵ ”. ing.

  Next, various aberrations in the imaging lens 1 of the first numerical example are shown in FIG. In this astigmatism diagram, the solid line indicates the value on the sagittal image plane, and the broken line indicates the value on the meridional image plane.

  From the various aberration diagrams (spherical aberration diagram, astigmatism diagram and distortion diagram) in FIG. 2, the imaging lens 1 of the first numerical example corrects various aberrations satisfactorily and has excellent imaging performance. I understand that.

  Incidentally, the Abbe numbers and focal lengths of the respective lenses in the imaging lens 1 of the first numerical example are as shown in Table 3.

[2-2. Second numerical example]
In FIG. 3, in which parts corresponding to those in FIG. 1 are denoted by the same reference numerals, 10 denotes an imaging lens as a whole in the second numerical example, and in this case also, there are five lenses.

  The imaging lens 10 includes, in order from the object side, an aperture stop STO, a first lens L11 having a positive refractive power, a meniscus second lens L12 having a negative refractive power with a concave surface facing the image side, A third lens L13 having a positive refractive power, a meniscus fourth lens L14 having a positive refractive power with a concave surface facing the object side in the vicinity of the optical axis, and a peripheral having a negative refractive power in the vicinity of the optical axis And a fifth lens L15 having positive refractive power in the part.

  In the imaging lens 10, a seal glass SG for protecting the image plane IMG is disposed between the fifth lens L15 and the image plane IMG.

  In the imaging lens 10 having such a configuration, the aperture stop STO is disposed in front of the object side.

  As a result, in this imaging lens 10, the aperture stop STO is disposed closer to the object side than the object side surface of the second lens L12, and the exit pupil position is as close to the object side as possible, whereby the principal ray incident angle of the imaging lens 10 with respect to the optical axis. Therefore, it is possible to improve the light receiving efficiency and avoid image quality deterioration due to color mixing.

  As described above, in the imaging lens 10, the five imaging lenses are configured and the power arrangement as described above is used, so that while suppressing the overall optical length, the spherical aberration, which is an on-axis aberration that becomes a problem when the aperture is increased, The coma aberration and the field curvature of the off-axis aberration can be corrected with a good balance.

  Table 4 shows lens data when specific numerical values are applied to the imaging lens 10 of the second numerical example, together with the F number FNo, the focal length f of the entire lens system, and the angle of view 2ω. Incidentally, the imaging lens 10 has a performance equivalent to a focal length of 34 [mm] in terms of 35 mm film.

  In the imaging lens 10, the object side surface (S2) of the first lens L1, the image side surface (S3) of the first lens L1, the object side surface (S4) of the second lens L2, and the second lens L2. An image side surface (S5), an object side surface (S6) of the third lens L3, an image side surface (S7) of the third lens L3, an object side surface (S8) of the fourth lens L4, and a fourth lens. The image side surface (S9) of the lens L4, the object side surface (S10) of the fifth lens L5, and the image side surface (S11) of the fifth lens L5 are formed in an aspheric shape.

Subsequently, the aspherical fourth-order, sixth-order, eighth-order, and tenth-order aspheric coefficients “A”, “B”, “C”, and “D” in the imaging lens 10 of the second numerical example are represented by the conic coefficient “ Table 5 together with “K”. Incidentally, in Table 5, “E-01” represents an exponential expression with a base of 10, that is, “10 ⁻¹ ”.

  Next, various aberrations in the imaging lens 10 of the second numerical example are shown in FIG. Also in this astigmatism diagram, the solid line shows the value on the sagittal image plane, and the broken line shows the value on the meridional image plane.

  From the various aberration diagrams (spherical aberration diagram, astigmatism diagram and distortion diagram) in FIG. 4, various aberrations are corrected well in the imaging lens 10 of the second numerical example, and the imaging performance is excellent. I understand that

  Incidentally, the Abbe number and the focal length of each lens in the imaging lens 10 of the second numerical example are as shown in Table 6.

[2-3. Third numerical example]
In FIG. 5, in which parts corresponding to those in FIG. 1 are assigned the same reference numerals, 20 denotes an image pickup lens in the third numerical example as a whole, and in this case also, there are five lenses.

  The imaging lens 20 includes, in order from the object side, a first lens L21 having a positive refractive power, an aperture stop STO, a second meniscus lens L22 having a negative refractive power with a concave surface facing the image side, A third lens L23 having a positive refractive power, a meniscus fourth lens L24 having a positive refractive power with a concave surface facing the object side in the vicinity of the optical axis, and a peripheral having a negative refractive power in the vicinity of the optical axis And a fifth lens L25 having positive refractive power in the part.

  In the imaging lens 20, a seal glass SG for protecting the image plane IMG is disposed between the fifth lens L25 and the image plane IMG.

  In the imaging lens 20 having such a configuration, the aperture stop STO is not disposed in front of the object side, but is disposed between the first lens L21 and the second lens L22.

  The imaging lens 20 is arranged such that the aperture stop STO is positioned as close to the front of the optical system as possible (on the object side of the object side of the second lens L22), so that an image is formed on the object side of the second lens L22. Compared to the case where the lens is disposed on the side, the exit pupil position is closer to the front, and the overall length of the lens system can be shortened.

  As described above, in the imaging lens 20, the five imaging lenses are configured and the power arrangement as described above is used, and while suppressing the overall optical length, the spherical aberration, which is an on-axis aberration that becomes a problem when the aperture is increased, The coma aberration and the field curvature of the off-axis aberration can be corrected with a good balance.

  Table 7 shows lens data when specific numerical values are applied to the imaging lens 20 of the third numerical value example together with the F number FNo, the focal length f of the entire lens system, and the angle of view 2ω. Incidentally, the imaging lens 20 has a performance equivalent to a focal length of 36 [mm] in terms of 35 mm film.

  In the imaging lens 20, the object-side surface (S1) of the first lens L21, the image-side surface (S2) of the first lens L21, the object-side surface (S4) of the second lens L22, and the second lens L22. Image-side surface (S5), object-side surface (S6) of the third lens L23, object-side surface (S8) of the fourth lens L24, image-side surface (S9) of the fourth lens L24, fifth The object side surface (S10) of the lens L25 and the image side surface (S11) of the fifth lens L25 are formed in an aspheric shape.

  In the imaging lens 20, the image side surface (S7) of the third lens L23 is formed in a spherical shape.

Subsequently, the aspherical fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients “A”, “B”, “C”, and “D” in the imaging lens 20 of the third numerical example are represented by the conic coefficient “ Table 8 together with “K”. In Table 8, “E-02” represents an exponential expression with a base of 10, that is, “10 ⁻² ”.

  Next, various aberrations in the imaging lens 20 of the third numerical example are shown in FIG. Also in this astigmatism diagram, the solid line shows the value on the sagittal image plane, and the broken line shows the value on the meridional image plane.

  From the various aberration diagrams (spherical aberration diagram, astigmatism diagram, and distortion diagram) in FIG. 6, various aberrations are corrected well in the imaging lens 20 of the third numerical example, and the imaging performance is excellent. I understand that

  Incidentally, the Abbe number and the focal length of each lens in the imaging lens 20 of the third numerical example are as shown in Table 9.

[2-4. Various values corresponding to the conditional expression]
Next, various numerical values of the first numerical example to the third numerical example corresponding to the conditional expressions (1) to (7) are derived based on Tables 3, 6 and 9, and are shown in Table 10. Show.

According to Table 10, the Abbe number ν ₁ of the d-line (wavelength 587.6 nm) of the first lens L1 and the Abbe number ν ₂ of the d-line of the second lens L2 in the first numerical example (FIG. 1). Difference between the Abbe number ν ₁ of the d-line of the first lens L11 and the Abbe number ν ₂ of the d-line of the second lens L12 in the second numerical example (FIG. 3), and the third numerical example (FIG. The difference between the Abbe number ν ₁ of the d-line of the first lens L21 and the Abbe number ν ₂ of the d-line of the second lens L22 in 5) is the maximum from the minimum value “38.2” (third numerical example). It can be seen that the value “40.6” (second numerical example) satisfies the conditional expression (1) ν ₁ −ν ₂ > 35.

Further, according to Table 10, the d-line of the third lens L3 (FIG. 1), L13 (FIG. 3), and L23 (FIG. 5) in the first numerical example to the third numerical example, as in the conditional expression (2). It is understood that the Abbe number ν ₃ of the third numerical example is “55.8” of the third numerical example at the minimum, and satisfies the conditional expression (2) ν ₃ > 50.

Further, according to Table 10, the d-line of the fourth lens L4 (FIG. 1), L14 (FIG. 3), and L24 (FIG. 5) in the first numerical example to the third numerical example, as in conditional expression (3). It can be seen that the Abbe number ν ₄ of the third numerical example is “55.8” of the third numerical example at the minimum and satisfies the conditional expression (3) ν ₄ > 50.

Further, according to Table 10, “f ₃ / f ₄ ” is “0.61” in the second numerical example, which is the minimum value, and “3. Since “10” is the maximum value, it is understood that the conditional expression (4) 0.4 <f ₃ / f ₄ <4.5 is satisfied.

Further, according to Table 10, “| f ₁ / f ₂ |” is “0.68” in the second numerical example, which is the minimum value, and “ Since “0.81” is the maximum value, it is understood that the conditional expression (5) 0.55 <| f ₁ / f ₂ | <1.0 is satisfied.

Further, according to Table 10, “| f ₅ / f |” is the minimum value of “0.61” in the third numerical example, and “2. Since 30 ”is the maximum value, it can be seen that conditional expression (6) 0.4 <| f ₅ /f|<2.0 is satisfied.

Finally, according to Table 10, as in conditional expression (7), d of the fifth lenses L5 (FIG. 1), L15 (FIG. 3), and L25 (FIG. 5) in the first to third numerical examples. It can be seen that the Abbe number ν ₅ in the line is “55.8” in the third numerical example at the minimum, and the conditional expression (7) ν ₅ > 50 is satisfied.

  Therefore, the imaging lenses 1, 10 and 20 in the first numerical example to the third numerical example satisfy all the conditional expressions (1) to (7) described above.

  Thus, in the imaging lenses 1, 10 and 20 in the first numerical example to the third numerical example, when the aperture is increased to about F-number 1.8, spherical aberration and off-axis aberration of axial aberration are achieved. Thus, it is possible to satisfactorily correct the coma aberration and the curvature of field, and to have an optical performance that can sufficiently cope with, for example, a high-pixel imaging device having 8 million pixels or more.

  Further, in the imaging lenses 1, 10 and 20 in the first to third numerical examples, the axial chromatic aberration can be corrected well while suppressing the optical total length, and the large aperture having an F number of about 1.8. It is possible to have high resolution performance that is required with the development.

<3. Imaging device and mobile phone>
[3-1. Configuration of imaging device]
Subsequently, the imaging lens of the present invention, and an imaging device such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor for converting an optical image formed by the imaging lens into an electrical signal. An imaging device having a configuration in which is combined will be described.

  In the following description, an imaging apparatus using an imaging lens (for example, the imaging lens 1 in the first numerical example described above) in which the aperture stop is disposed in front of the object side will be described. An imaging lens in which an aperture stop is disposed between the first lens and the second lens, such as the imaging lens 20 (FIG. 5) in the numerical example, can be similarly applied to the imaging apparatus. Incidentally, as an imaging lens applied to an imaging apparatus, the focal length of the entire lens system has a performance corresponding to a focal length of 24 to 40 [mm] in terms of 35 mm film.

  The imaging lens provided in the imaging apparatus includes, in order from the object side, an aperture stop, a first lens having a positive refractive power, and a meniscus second lens having a negative refractive power with a concave surface facing the image side. A third lens having a positive refractive power, a fourth lens having a meniscus shape having a positive refractive power with a concave surface facing the object side in the vicinity of the optical axis, and a peripheral lens having a negative refractive power in the vicinity of the optical axis And a fifth lens having a positive refractive power in the part.

  In the imaging lens of the imaging apparatus having such a configuration, the aperture stop is disposed in front of the object side.

  Thus, in the imaging lens of the imaging apparatus, the aperture stop is disposed on the object side of the object side of the second lens, and the exit pupil position is as close as possible to the object side, thereby reducing the chief ray incident angle of the imaging lens with respect to the optical axis. Therefore, it is possible to improve the light receiving efficiency and avoid image quality deterioration due to color mixing.

The imaging device is configured so that the imaging lens satisfies the following conditional expression (1), conditional expression (2), and conditional expression (3).
(1) ν ₁ −ν ₂ > 35
(2) ν ₃ > 50
(3) ν ₄ > 50
However,
ν ₁ : Abbe number at the d-line (wavelength 587.6 nm) of the first lens ν ₂ : Abbe number at the d-line (wavelength 587.6 nm) of the second lens ν ₃ : d-line (wavelength 587.6 nm) of the third lens ) Abbe number ν _{4 in} (): The Abbe number in the d-line (wavelength 587.6 nm) of the fourth lens.

  Conditional expression (1) represents the difference between the Abbe number of the first lens at the d-line and the Abbe number of the second lens at the d-line, and conditional expression (2) represents the Abbe number of the third lens at the d-line. 3) defines the Abbe number of the fourth lens at the d-line, and is a condition for satisfactorily correcting chromatic aberration occurring in the lens system.

  In this imaging lens, it is difficult to correct the axial chromatic aberration required for increasing the diameter of the F number of about 1.8 if the specified values of the conditional expressions (1), (2), and (3) are not satisfied. It becomes.

  As described above, in the imaging apparatus, when the imaging lens satisfies the conditional expression (1), the conditional expression (2), and the conditional expression (3), it is possible to correct axial chromatic aberration satisfactorily.

Further, this imaging apparatus is configured to satisfy the following conditional expression (4) in the imaging lens.
(4) 0.4 <f ₃ / f ₄ <4.5
However,
f ₃ : focal length of the third lens f ₄ : focal length of the fourth lens.

Condition (4), which defines the ratio between the focal length f ₄ of the focal length f ₃ of the third lens fourth lens, the balance between the refractive power and the refractive power of the fourth lens in the third lens Is limiting.

  In this imaging apparatus, if the imaging lens deviates from the upper limit value of the conditional expression (4), the power (refractive power) of the third lens becomes too weak, making it difficult to correct axial chromatic aberration and achieving good optical performance. It becomes impossible to maintain. On the other hand, if the value falls outside the lower limit, the power of the third lens becomes strong, which is advantageous in terms of aberration correction. However, the power of the fourth lens becomes too weak and the total optical length increases, and this lens system can be downsized. It becomes difficult.

  As described above, the imaging apparatus satisfies the conditional expression (4) in the imaging lens, thereby effectively correcting the axial chromatic aberration and ensuring good optical performance while suppressing the optical total length. Yes.

Further, in this imaging apparatus, the imaging lens is configured to satisfy the following conditional expression (5).
(5) 0.55 <| f ₁ / f ₂ | <1.0
However,
f ₁ : focal length of the first lens f ₂ : focal length of the second lens.

Condition (5), the focal length f ₁ of the first lens is intended to define the ratio of the focal length f ₂ of the second lens, the balance of the refractive power and the refractive power of the second lens of the first lens Is limiting.

  In this imaging apparatus, if the imaging lens deviates from the upper limit value of the conditional expression (5), the power of the second lens becomes strong, which is advantageous in terms of aberration correction. However, the power of the second lens becomes too strong and optical. The overall length increases, and it becomes difficult to reduce the size of the lens system. On the other hand, if the lower limit is exceeded, the power of the second lens becomes too weak, making it difficult to correct axial chromatic aberration, and good optical performance cannot be maintained.

  As described above, the imaging apparatus satisfies the conditional expression (5) in the imaging lens, and thereby can effectively correct the longitudinal chromatic aberration and ensure good optical performance while suppressing the optical total length. Yes.

Further, in this imaging apparatus, the imaging lens is configured to satisfy the following conditional expressions (6) and (7).
(6) 0.4 <| f ₅ /f|<2.0
(7) ν ₅ > 50
However,
f: focal length of the entire lens system f ₅ : focal length ν _{5 of} the fifth lens: Abbe number at the d-line (wavelength 587.6 nm) of the fifth lens.

Condition (6) is intended to define the ratio of the focal length f ₅ and the lens focal length f of the fifth lens, which limits the power of the fifth lens.

  In this imaging apparatus, if the imaging lens deviates from the upper limit value of conditional expression (6), the power of the fifth lens becomes weak, which is advantageous in terms of aberration correction. However, the total optical length increases, and this lens system is downsized. Will become difficult. On the other hand, if the lower limit is exceeded, the power of the fifth lens becomes too strong, and it becomes difficult to correct in a well-balanced field curvature that occurs at an intermediate image height (for example, 20 to 50% higher) from the center.

  Conditional expression (7) defines the Abbe number of the fifth lens at the d-line, and if it falls below this specified value, it is difficult to correct axial chromatic aberration and lateral chromatic aberration in a well-balanced manner. The performance cannot be maintained.

  As described above, the imaging apparatus satisfies the conditional expressions (6) and (7) in the imaging lens, thereby correcting the axial chromatic aberration and the chromatic aberration of magnification in a well-balanced manner, and good optical performance corresponding to the high pixel imaging device. The optical total length can be suppressed while securing the above.

  Thus, in the imaging lens of the imaging apparatus of the present invention, even if the aperture is increased to about F number 1.8, for example, a spherical aberration or an off-axis aberration of an on-axis aberration with respect to a high-pixel imaging element having 8 million pixels or more. The coma aberration and the curvature of field are excellently balanced and corrected to have a good optical performance.

  In the present invention, for example, a small and large-diameter imaging lens having high resolution performance, in which axial chromatic aberration is well corrected while suppressing the optical total length, is mounted on a high-pixel imaging device having 8 million pixels or more. An image pickup apparatus can be configured.

[3-2. Configuration of mobile phone equipped with imaging device]
Next, a mobile phone equipped with the imaging device of the present invention will be described.

  As shown in FIGS. 7 and 8, the mobile phone 100 includes a display unit 101 and a main body unit 102 that are foldably connected via a hinge unit 103, and the display unit 101 and the main body unit 102 are folded when being carried. The folded state (FIG. 7) and the display unit 101 and the main unit 102 are unfolded during use such as during a call (FIG. 8).

  The display unit 101 includes a liquid crystal display panel 111 on one surface, and a speaker 112 above the liquid crystal display panel 111. The display unit 101 includes an imaging device 107 therein, and an infrared communication unit 104 for performing infrared wireless communication at the tip.

  The display unit 101 has a cover lens 105 disposed on the object side of the first lens in the imaging device 107 on the other surface.

  The main body 102 is provided with various operation keys 113 such as numeric keys and power keys on one surface, and a microphone 114 at the lower end. The main body 102 is provided with a memory card slot 106 on a side surface thereof, and the memory card 120 can be inserted into and removed from the memory card slot 106.

  As shown in FIG. 9, the mobile phone 100 has a CPU (Central Processing Unit) 130, expands a control program stored in a ROM (Read Only Memory) 131 in a RAM (Random Access Memory) 132, and generates a bus. The entire mobile phone 100 is controlled in an integrated manner via 133.

  The cellular phone 100 includes a camera control unit 140 and can take a still image or a moving image by controlling the imaging device 107 via the camera control unit 140.

  The camera control unit 140 performs compression processing by JPEG (Joint Photographic Experts Group), MPEG (Moving Picture Expert Group), or the like on the image data obtained by shooting through the imaging device 107, and the resulting image Data is sent to the CPU 130, display control unit 134, communication control unit 160, memory card interface 170 or infrared interface 135 via the bus 133.

  The image pickup apparatus 107 is configured by combining any one of the image pickup lenses 1, 10, and 20 and an image pickup element SS formed of a CCD sensor, a CMOS sensor, or the like.

  In the mobile phone 100, the CPU 130 temporarily stores the image data supplied from the camera control unit 140 in the RAM 132, the image data stored in the memory card 120 by the memory card interface 170 as necessary, or the display control unit. The data is output to the liquid crystal display panel 111 via 134.

  In addition, the cellular phone 100 temporarily stores the audio data recorded through the microphone 114 at the same time as shooting at the RAM 132 through the audio codec 150, or the memory card 120 through the memory card interface 170 as necessary. Or audio output from the speaker 112 via the audio codec 150 simultaneously with the image display on the liquid crystal display panel 111.

  The mobile phone 100 can output image data and audio data to the outside via the infrared interface 135 and the infrared communication unit 104, and other electronic devices having an infrared communication function such as a mobile phone, a personal computer, a PDA (Personal Digital). Assistant) etc. can be transmitted.

  Incidentally, in the mobile phone 100, when displaying a moving image or a still image on the liquid crystal display panel 111 based on the image data stored in the RAM 132 or the memory card 120, the camera control unit 140 decodes and decompresses the image data. After that, the data is output to the liquid crystal display panel 111 via the display control unit 134.

  The communication control unit 160 transmits and receives radio waves to and from the base station via an antenna (not shown). In the voice call mode, the communication control unit 160 performs predetermined processing on the received voice data, and then performs voice processing. The data is output to the speaker 112 via the codec 150.

  Further, the communication control unit 160 performs a predetermined process on the audio signal collected by the microphone 114 via the audio codec 150 and then transmits the audio signal via an antenna (not shown).

  This imaging device 107 has a configuration in which the imaging lens 1, 10 or 20 incorporated therein can be reduced in size and diameter while suppressing the optical total length as described above. This is advantageous when mounted on an electronic device that is required to be downsized.

<4. Other embodiments>
In the above-described embodiment, as the first numerical example to the third numerical example, the specific shapes, structures, and numerical values of the respective parts in the imaging lenses 1, 10 and 20 are all performed when the present invention is implemented. These are merely examples of realization, and the technical scope of the present invention should not be construed in a limited manner.

  In the above-described embodiment, the case where the specific numerical values in Table 10 are shown based on the first numerical example to the third numerical example has been described. However, the present invention is not limited to this, and the conditions Various other specific shapes, structures, and numerical values may be used as long as they are within the range that satisfies the expressions (1) to (7).

  Further, in the above-described embodiment, the case where the imaging lens uses the first lens having positive refractive power with the convex surfaces facing the object side and the image side has been described, but the present invention is not limited to this. As long as the conditional expressions (1) and (5) are satisfied, the imaging lens may be, for example, a meniscus first lens having a positive refractive power with the concave surface facing the image side.

  Furthermore, in the above-described embodiment, the imaging lens satisfies the conditional expressions (1) to (3), the conditional expression (4), the conditional expression (5), the conditional expression (6), and the conditional expression (7). The case has been described where the aperture stop STO is arranged on the object side with respect to the object side surface of the second lens.

  The present invention is not limited to this, and the imaging lens satisfies only conditional expressions (1) to (3), conditional expression (4), and conditional expression (5), and the aperture stop STO is from the object side surface of the second lens. May also be arranged on the object side.

  The present invention is not limited to this, and the imaging lens satisfies only conditional expressions (1) to (3), conditional expression (4), conditional expression (6), and conditional expression (7), and an aperture stop STO is provided. The second lens may be arranged closer to the object side than the object side surface, or only the conditional expressions (1) to (3) and (4) are satisfied, and the aperture stop STO has the second lens. It may be arranged closer to the object side than the object side surface.

  Further, the imaging lens satisfies only conditional expressions (1) to (3), conditional expression (5), conditional expression (6), and conditional expression (7), and the aperture stop STO is closer to the object side surface of the second lens. May be arranged on the object side, or satisfy only conditional expressions (1) to (3) and (5), and the aperture stop STO is closer to the object than the object side surface of the second lens. It may be arranged on the side.

  Further, the imaging lens satisfies only conditional expressions (1) to (3), conditional expression (6), and conditional expression (7), and the aperture stop STO is disposed on the object side of the second lens relative to the object side surface. You may be made to do.

  Further, the imaging lens may satisfy only conditional expressions (1) to (3), and the aperture stop STO may be disposed on the object side with respect to the object side surface of the second lens.

  In the imaging lens and imaging device of the present invention, the case where the imaging device 107 is mounted on the mobile phone 100 is shown as an example, but the application target of the imaging device is not limited to this. The present invention can be widely applied to various other electronic devices such as a digital still camera, a personal computer equipped with a camera, and a PDA incorporating a camera.

  DESCRIPTION OF SYMBOLS 1, 10, 20 ... Imaging lens, 100 ... Cell-phone, 101 ... Display part, 102 ... Main part, 103 ... Hinge part, 104 ... Infrared communication part, 105 ... Cover lens, 106 ... Memory card slot, 107... Imaging device, 111. Liquid crystal display panel, 112... Speaker, 113 .. Operation key, 114. ... RAM, 134... Display control unit, 135... Infrared interface, 140... Camera control unit, 150.

Claims (6)

From the object side,
A first lens having a positive refractive power;
A second meniscus lens having negative refractive power with a concave surface facing the image side;
A third lens having positive refractive power;
A meniscus fourth lens having a positive refractive power with the concave surface facing the object side in the vicinity of the optical axis;
A fifth lens having a negative refractive power in the vicinity of the optical axis and having a positive refractive power in the peripheral portion,
An imaging lens that satisfies the following conditional expressions (1), (2), and (3).
(1) ν ₁ −ν ₂ > 35
(2) ν ₃ > 50
(3) ν ₄ > 50
However,
ν ₁ : Abbe number at the d-line (wavelength 587.6 nm) of the first lens ν ₂ : Abbe number at the d-line (wavelength 587.6 nm) of the second lens ν ₃ : d-line (wavelength 587.6 nm) of the third lens ) Abbe number ν _{4 in} (): The Abbe number in the d-line (wavelength 587.6 nm) of the fourth lens. The imaging lens according to claim 1, wherein the following conditional expression (4) is satisfied.
(4) 0.4 <f ₃ / f ₄ <4.5
However,
f ₃ : focal length of the third lens f ₄ : focal length of the fourth lens. The imaging lens according to claim 1 or 2, wherein the following conditional expression (5) is satisfied.
(5) 0.55 <| f ₁ / f ₂ | <1.0
However,
f ₁ : focal length of the first lens f ₂ : focal length of the second lens. The imaging lens according to claim 1, wherein the following conditional expression (6) and conditional expression (7) are satisfied.
(6) 0.4 <| f ₅ /f|<2.0
(7) ν ₅ > 50
However,
f: focal length of the entire lens system f ₅ : focal length ν _{5 of} the fifth lens: Abbe number at the d-line (wavelength 587.6 nm) of the fifth lens. The imaging lens according to claim 1, wherein an aperture stop that adjusts the amount of light is disposed closer to the object side than an object side surface of the second lens. An imaging lens, and an imaging element that converts an optical image formed by the imaging lens into an electrical signal;
The imaging lens, in order from the object side,
A first lens having a positive refractive power;
A second meniscus lens having negative refractive power with a concave surface facing the image side;
A third lens having positive refractive power;
A meniscus fourth lens having a positive refractive power with the concave surface facing the object side in the vicinity of the optical axis;
A fifth lens having a negative refractive power in the vicinity of the optical axis and having a positive refractive power in the peripheral portion,
An imaging device that satisfies the following conditional expression (1), conditional expression (2), and conditional expression (3).
(1) ν ₁ −ν ₂ > 35
(2) ν ₃ > 50
(3) ν ₄ > 50
However,
ν ₁ : Abbe number at the d-line (wavelength 587.6 nm) of the first lens ν ₂ : Abbe number at the d-line (wavelength 587.6 nm) of the second lens ν ₃ : d-line (wavelength 587.6 nm) of the third lens ) Abbe number ν _{4 in} (): The Abbe number in the d-line (wavelength 587.6 nm) of the fourth lens.

Images