JP2018097150A - Imaging lens, lens unit, and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging lens unit and an imaging apparatus each of which is inexpensive, has a long back focus, a wide viewing angle, a large aperture, good optical performance, and superior weatherability.SOLUTION: An imaging lens 10 is a wide-angle lens configured to form an object image on an imaging surface 1 of a solid imaging device 51, and comprises a meniscus-shaped first lens L1 having negative power and convex to the object side, a second lens L2 having positive power, a third lens L3 having positive power, a fourth lens L4 having negative power, and a fifth lens L5 having positive power in order from the object side. The first lens L1 is a spherical glass lens and the second lens L2 is a plastic lens with at least one aspherical surface, while the third lens L3 is a glass lens and the fourth and fifth lenses L4, L5 are plastic lenses, each having at least one aspherical surface. The imaging lens 10 satisfies an appropriately set condition.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging lens, a lens unit, and an imaging apparatus, and more particularly to a wide-angle imaging lens and the like.

  In recent years, image sensors such as CCDs and CMOSs have been reduced in size and increased in pixels. At the same time, an image pickup apparatus body including these image pickup elements is also downsized, and an image pickup lens mounted thereon is also required to be downsized and high performance. In particular, in-vehicle lenses and surveillance camera lenses have a strong demand for a wide angle and a large aperture due to the assumed use environment. As a conventionally known imaging lens with a relatively small number of lenses that satisfies such requirements, for example, the one disclosed in Patent Document 1 below can be cited.

  The demand for lenses for in-vehicle cameras and surveillance cameras has become stricter year by year, and it is required to satisfy a plurality of advanced requirements at the same time. Specifically, while having a compact configuration with a small number of lenses, it has a long back focus so that a cover glass and a filter can be placed between the lens system and the image sensor, and has a large aperture and a full angle of view of 90 °. There has been a demand for an imaging lens in which aberrations are favorably corrected while ensuring the above wide angle. In addition, many imaging devices in the field such as the above-mentioned in-vehicle camera have a fixed focus that does not have an autofocus function, and the focus shift due to environmental changes directly affects the resolution performance. In recent years, there has been a growing demand for characteristics with respect to temperature changes. In addition, when used in an in-vehicle camera or a surveillance camera, the first lens exposed to the outside air is strongly required to have weather resistance, so that it is often necessary to use the first lens as a glass lens. In the imaging lens of Patent Document 1 below, since the first lens is formed of a plastic lens, various aberrations are effectively corrected while having a large aperture and a wide angle, and the resolution performance is good, but the weather resistance is excellent. It ’s hard to say.

JP 2016-38574 A

  The present invention has been made in view of the above-mentioned background art, has a long back focus, a wide angle of view is ensured, has a large aperture and is bright but has good optical performance, and is out of focus when the environment changes. An object of the present invention is to provide an imaging lens that is small, excellent in weather resistance, and inexpensive, and a lens unit and an imaging apparatus including the imaging lens.

In order to achieve the above object, an imaging lens according to the present invention is a spherical type first lens made of glass and having a negative meniscus shape on the object side, plastic, in order from the object side, plastic A second lens having a positive power and having at least one aspheric shape, a third lens having a positive power and formed of glass, and a plastic having a negative power and at least one having a negative power A fourth lens having an aspheric shape and a fifth lens made of plastic and having a positive power and having at least one aspheric shape satisfy the following conditional expressions (1) to (4). .
0 <f / f2 <0.3 (1)
−1.0 <f4 / f5 <−0.75 (2)
0 ≦ D45 / f <0.04 (3)
−1.5 <f4 / f <−1.0 (4)
here,
f: focal length of the entire lens system f2: focal length of the second lens f4: focal length of the fourth lens f5: focal length of the fifth lens D45: distance on the optical axis between the fourth lens and the fifth lens

  In the imaging lens, negative, positive, positive, negative, and positive lenses are arranged in this order from the object side, and the second, fourth, and fifth lenses are plastic aspherical lenses, thereby wide-angle imaging. In this optical system, although it is a small number, it is possible to satisfactorily correct aberrations that are a problem when the aperture is increased (that is, when the F number is reduced). Moreover, cost reduction can be achieved by using a plurality of plastic lenses. Furthermore, by satisfying the conditional expressions (1) to (3), it is possible to prevent a focus shift or a focus shift when the temperature changes while using a plastic lens. Specifically, by setting the focal length of the plastic second lens so as to satisfy the conditional expression (1), the focal length of the second lens is sufficiently longer than the focal length of the entire optical system, that is, the power. Therefore, even if the second lens made of plastic expands or contracts due to a temperature change, the influence of the focus shift associated therewith is reduced. Furthermore, since the fourth lens and the fifth lens that are easily affected by temperature changes satisfy both the conditional expressions (2) and (3), the combined power of the two plastic lenses can be set small. It becomes possible to make the configuration in which the out-of-focus is less likely to occur. Further, by satisfying conditional expression (4), it is possible to increase the individual powers of the fourth and fifth lenses while assuming conditional expressions (2) and (3). However, various aberrations can be corrected satisfactorily.

According to a specific aspect of the present invention, in the imaging lens, the materials of the first to fifth lenses satisfy the following conditional expressions (5) to (9).
60>vd1> 45 (5)
35>vd2> 20 (6)
60>vd3> 45 (7)
35>vd4> 20 (8)
60>vd5> 50 (9)
here,
vd1: Abbe number of the first lens at the d-line vd2: Abbe number of the second lens at the d-line vd3: Abbe number of the third lens at the d-line vd4: Abbe number of the fourth lens at the d-line vd5: Abbe number at the d-line of the fifth lens

In the use of an in-vehicle camera or a surveillance camera, it is assumed that it is used not only in the daytime but also in the nighttime, so it is necessary to cope with imaging with not only visible light but also near infrared light. Therefore, in a fixed-focus optical system, chromatic aberration needs to be corrected from visible light to near-infrared light, and visible light can be obtained by using a material within the above conditional expressions (5) to (9). It is possible to correct chromatic aberration from near to near infrared light. It is more preferable to satisfy the following conditional expressions (5) ′ and (7) ′.
60>vd1> 50 (5) '
60>vd3> 50 (7) '

According to another aspect of the present invention, provided with a diaphragm disposed between the second lens and the third lens, when the object side from the diaphragm is a front group and the image side from the diaphragm is a rear group, the following conditions are satisfied. Formula (10) is satisfy | filled.
−2.5 <ff / fr <−1.8 (10)
here,
ff: focal length of front group fr: focal length of rear group

By setting it within the range of the conditional expression (10), a compact optical system can be obtained while having a long back focus. Specifically, a sufficient back focus can be secured by exceeding the lower limit of the conditional expression (10). On the other hand, by making the value less than the upper limit of conditional expression (10), the back focus does not become too long, and the imaging lens can be downsized. It is more preferable to satisfy the following conditional expression (10) ′.
−2.3 <ff / fr <−2.0 (10) ′

  According to still another aspect of the present invention, the fourth lens and the fifth lens are fitted and fixed to each other.

  Since a powerful aspheric plastic lens tends to have high decentration error sensitivity, both the fourth lens and the fifth lens are not fitted into the lens holder, but only one of the lenses is attached to the lens holder or It is possible to suppress the eccentricity of the lens by fitting the lens to the lens barrel and directly fitting the other lens to the above-described one lens itself.

  According to still another aspect of the present invention, the third lens has at least one aspheric surface.

  Since the third lens has at least one aspheric surface, the performance of the imaging lens is further improved.

According to still another aspect of the present invention, the following conditional expression (11) is satisfied.
R2 <R1 (11)
here,
R1: radius of curvature of the first lens on the object side R2: radius of curvature of the first lens on the image side

  By making it within the range of the conditional expression (11), it is possible to secure a wide angle of view while suppressing the occurrence of spherical aberration and the like.

  In order to achieve the above object, a lens unit according to the present invention includes the imaging lens described above and a lens barrel that holds the imaging lens.

  The above lens unit incorporates the imaging lens described above, so it has a long back focus, a wide angle of view is ensured, it has good optical performance while being bright, has a small focus shift when the environment changes, and is weather resistant. Excellent and inexpensive.

  In order to achieve the above object, an imaging apparatus according to the present invention includes the lens unit described above and an imaging element that projects an image by the lens unit.

  Since the imaging device incorporates the imaging lens described above, a wide angle of view is ensured, the optical device has good optical performance while being bright, is excellent in environmental changes and weather resistance, and is inexpensive.

It is a figure explaining an imaging device provided with the imaging lens of one embodiment of the present invention. (A) is a sectional view of the imaging lens of Example 1, and (B) to (D) are longitudinal aberration diagrams of Example 1. FIG. (A) is a sectional view of the imaging lens of Example 2, and (B) to (D) are longitudinal aberration diagrams of Example 2. FIG. (A) is a sectional view of the imaging lens of Example 3, and (B) to (D) are longitudinal aberration diagrams of Example 3. FIG.

  FIG. 1 is a diagram illustrating an imaging apparatus 100 according to an embodiment of the present invention. The imaging apparatus 100 includes a camera module 30 for forming an image signal, and a processing unit 60 that exhibits the function of the imaging apparatus 100 by operating the camera module 30.

  The camera module 30 includes a lens unit 40 including the imaging lens 10 and a sensor unit 50 that converts a subject image formed by the imaging lens 10 into an image signal. The camera module 30 incorporates an imaging lens 10 that will be described in detail below, has a wide angle of view, is bright but has good optical performance, is excellent in environmental changes and weather resistance, and is inexpensive. Can be provided.

  The lens unit 40 includes an imaging lens 10 that is a wide-angle optical system, and a lens barrel 41 to which the imaging lens 10 is assembled.

  The imaging lens 10 has a front group G1 on the object side and a rear group G2 on the image side across the aperture stop AS, which will be described in detail later. The front group G1 includes first and second lenses L1 and L2, and the rear group G2 includes third to fifth lenses L3 to L5.

  The lens barrel 41 is formed of metal, resin, resin glass mixed with glass fiber, and the like, and accommodates and holds the imaging lens 10 therein. When the lens barrel 41 is formed of a metal, a resin mixed with glass fiber, it is less likely to expand than the resin, and the imaging lens 10 can be stably fixed. The lens barrel 41 has an opening OP1 through which a light beam from the object side is incident.

  The first to fifth lenses L1 to L5 constituting the imaging lens 10 are directly or indirectly held on the inner surface side of the lens barrel 41 at the flange portion or the outer peripheral portion thereof, and the optical axis AX direction and the optical axis Positioning in the direction perpendicular to AX is performed. Among these, the fourth lens L4 is supported and positioned by the lens barrel 41 via the fifth lens L5.

  The sensor unit 50 includes a solid-state imaging device 51 that photoelectrically converts a subject image formed by the imaging lens 10, a substrate 52 that supports the solid-state imaging device 51 from the back and is provided with wiring, peripheral circuits, and the like, and a substrate 52. And a sensor holder 53 for holding the solid-state imaging device 51. The solid-state image sensor 51 is, for example, a CMOS image sensor. The substrate 52 includes wiring for operating the solid-state imaging device 51, peripheral circuits, and the like. The sensor holder 53 is formed of a resin or other material, and not only positions the solid-state image sensor 51 with respect to the optical axis AX but also supports the parallel plate F so as to face the solid-state image sensor 51. The lens barrel 41 of the lens unit 40 is fixed in a state of being positioned so as to be fitted to the sensor holder 53.

  The solid-state imaging device (imaging device) 51 includes a photoelectric conversion unit 51a having an imaging surface I, and a signal processing circuit (not shown) is formed around the solid-state imaging device (imaging device) 51. The solid-state imaging device 51 is not limited to the above-described CMOS type image sensor, and may be a device to which a CCD or the like is applied.

  In addition, the parallel plate F arrange | positioned between the imaging lens 10 and the solid-state image sensor 51 is an optical low-pass filter, the seal glass of a solid-state image sensor, IR cut filter, a wavelength selection filter, etc.

  The processing unit 60 includes a drive unit 61, an input unit 62, a storage unit 63, a display unit 64, and a control unit 68. The drive unit 61 operates the solid-state imaging device 51 by receiving a supply of a digital control signal or the like from the control unit 68. The drive unit 61 receives YUV and other digital pixel signals as image data from the solid-state imaging device 51 and transfers them to the control unit 68. The input unit 62 is a part that receives a user operation or a command from an external device, and the storage unit 63 is a part that stores information necessary for the operation of the imaging apparatus 100, image data acquired by the camera module 30, and the like. The display unit 64 displays information to be presented to the user, captured images, and the like. The control unit 68 controls the operations of the drive unit 61, the input unit 62, the storage unit 63, and the like, and can perform various image processing on the image data obtained by the camera module 30, for example. Such image data can be output to an external circuit.

  Hereinafter, the details of the imaging lens 10 of the embodiment will be described with reference to FIG. 1. The imaging lens 10 illustrated in FIG. 1 has the same configuration as the imaging lens 11 of Example 1 described later.

  The illustrated imaging lens 10 is a wide-angle lens that forms a subject image on the imaging surface I of the solid-state imaging device 51, and has a meniscus shape that has negative power in the order from the object side and is convex on the object side. The first lens L1, the second lens L2 having positive power, the third lens L3 having positive power, the fourth lens L4 having negative power, and the fifth lens L5 having positive power. Here, the first lens L1 is a spherical type lens formed of glass and configured by a spherical surface. The second lens L2 is made of plastic and has at least one aspherical shape. The third lens L3 is made of glass. The fourth and fifth lenses L4 and L5 are made of plastic and have at least one aspherical shape. In particular, the third lens L3 has a biconvex shape. The third lens L3 is not limited to having a spherical shape but may have an aspheric shape.

  In the illustrated example, among the lenses L1 to L5 constituting the imaging lens 10, the fourth and fifth lenses L4 and L5 are fitted with each other and fixed to each other. More specifically, a flange portion 15a is formed around the fifth lens L5, and an annular receiving portion 15c is provided on the fourth lens L4 side of the flange portion 15a. The inner diameter of the receiving portion 15c is equal to or slightly larger than the outer diameter of the fourth lens L4, and the fifth lens L5 side of the outer peripheral portion 14a of the fourth lens L4 can be fitted into the recess of the receiving portion 15c. The optical axis AX and the direction perpendicular to the optical axis AX can be aligned and fixed to each other. In the illustrated example, the fourth lens L4 is fitted into the fifth lens L5, but conversely, the fifth lens L5 can be fitted into the fourth lens L4. Since strong aspherical plastic lenses such as the fourth and fifth lenses L4 and L5 tend to have high decentering error sensitivity, both the fourth lens L4 and the fifth lens L5 are fitted into the lens barrel 41. Instead, only one lens (in this case, the fifth lens L5) is fitted into the lens barrel 41, and the other lens (in this case, the fourth lens L4) is the one lens (in this case, the first lens). By adopting a configuration in which the five lenses L5) are directly fitted to each other, the coaxiality of both the lenses L4 and L5 can be maintained, so that the decentering of the lenses can be suppressed and the collision between the optical surfaces can be avoided.

  In the imaging lens 10, negative, positive, positive, negative, and positive lenses L1 to L5 are arranged in order from the object side, and the second, fourth, and fifth lenses L2, L4, and L5 are plastic aspheric lenses. Thus, in a wide-angle imaging optical system, it is possible to satisfactorily correct aberrations that are a problem when the aperture is increased (that is, when the F number is reduced), although the number is small. Moreover, cost reduction can be achieved by using a plurality of plastic lenses.

The imaging lens 10 satisfies the following conditional expressions (1) to (4).
0 <f / f2 <0.3 (1)
−1.0 <f4 / f5 <−0.75 (2)
0 ≦ D45 / f <0.04 (3)
−1.5 <f4 / f <−1.0 (4)
However, the value f represents the focal length of the entire lens system, and the value f2 represents the focal length of the second lens L2. The value f4 represents the focal length of the fourth lens L4, and the value f5 represents the focal length of the fifth lens L5. Further, the value D45 represents the distance on the optical axis AX between the fourth lens L4 and the fifth lens L5.

  The imaging lens 10 is configured to satisfy the conditional expressions (1) to (3) so that a focus shift or a focus shift at the time of temperature change hardly occurs while using a plastic lens. That is, by setting the focal length of the plastic second lens L2 so as to satisfy the conditional expression (1), the focal length of the second lens L2 is sufficiently longer than the focal length of the entire optical system, that is, the power is increased. Therefore, even if the plastic lens, that is, the second lens L2 expands or contracts due to a change in temperature, the influence of the focus shift associated therewith is reduced. Furthermore, when the fourth lens L4 and the fifth lens L5 that are easily affected by the temperature change satisfy both the conditional expressions (2) and (3), the combined power of the two plastic lenses can be set small. For this reason, it is possible to make the configuration in which the focus shift is less likely to occur. Further, by satisfying the conditional expression (4), it is possible to increase the individual powers of the fourth and fifth lenses L4 and L5 while assuming the conditional expressions (2) and (3), and therefore the first lens L1. As a glass spherical lens, various aberrations can be corrected well.

  The imaging lens 10 has a configuration in which a focus shift or a focus shift at the time of a temperature change hardly occurs while using a plastic lens. However, a focus shift or a focus shift considering expansion / contraction due to linear expansion of a material constituting the sensor holder 53 is used. More preferably, the amount is set. By doing in this way, it becomes possible for the camera module 30 as a whole to suppress focus shift or focus shift at the time of temperature change.

The imaging lens 10 satisfies the following conditional expressions (5) to (9).
60>vd1> 45 (5)
35>vd2> 20 (6)
60>vd3> 45 (7)
35>vd4> 20 (8)
60>vd5> 50 (9)
However, the value vd1 represents the Abbe number of the first lens L1 on the d line, the value vd2 represents the Abbe number of the second lens L2 on the d line, and the value vd3 represents the d line of the third lens L3. The value vd4 represents the Abbe number of the fourth lens L4 at the d-line, and the value vd5 represents the Abbe number of the fifth lens L5 at the d-line.

When the imaging apparatus 100 is, for example, an in-vehicle camera or a surveillance camera, it is assumed that the imaging apparatus 100 is used not only in the daytime but also in the nighttime. Therefore, it is necessary to support not only visible light but also near infrared light. Therefore, chromatic aberration must be corrected from visible light to near-infrared light in a fixed-focus optical system, and chromatic aberration is corrected from visible light to near-infrared light by using a material within the above range. It becomes possible. Note that it is more preferable that the Abbe numbers vd1 and vd3 of the first and third lenses L1 and L3 on the d line satisfy the following conditional expressions (5) ′ and (7) ′.
60>vd1> 50 (5) '
60>vd3> 50 (7) '

The imaging lens 10 satisfies the following conditional expression (10).
−2.5 <ff / fr <−1.8 (10)
However, the value ff represents the focal length of the front group G1, and the value fr represents the focal length of the rear group G2.

By setting it within the range of the following conditional expression (10), a compact optical system can be obtained while having a long back focus. That is, sufficient back focus can be secured by making the value ff / fr of the conditional expression (10) exceed the lower limit. On the other hand, by making the value ff / fr of the conditional expression (10) below the upper limit, the back focus does not become too long, and the imaging lens 10 can be downsized. Note that it is more preferable that the value ff / fr satisfies the following conditional expression (10) ′.
−2.3 <ff / fr <−2.0 (10) ′

The imaging lens 10 satisfies the following conditional expression (11).
R2 <R1 (11)
However, the value R1 represents the radius of curvature of the first lens L1 on the object side, and the value R2 represents the radius of curvature of the first lens L1 on the image side.

  By making it within the range of the conditional expression (11), it is possible to secure a wide angle of view while suppressing the occurrence of spherical aberration and the like.

  The imaging lens 10 is a wide-angle lens having a total angle of view exceeding 90 °, and the imaging lens according to the present invention is suitably realized as such a wide-angle lens.

  The fourth lens L4 and the fifth lens L5 may be cemented lenses with the image side surface of the fourth lens L4 and the object side surface of the fifth lens L5 having the same shape. In this case, the chromatic aberration can be corrected even better.

  When the object side surface of the first lens L1 is assumed to be used in a harsh environment such as an in-vehicle camera or a surveillance camera, it is preferable that processing for enhancing strength, scratch resistance, and chemical resistance is performed. Furthermore, it is preferable to apply a water repellent coat or a hydrophilic coat to the object side surface of the first lens L1.

  Although not described above, the imaging lens 10 of the embodiment can be used for the fixed focus camera module 30 or the imaging device 100 without a focus function. That is, it is not necessary to provide the lens barrel 41 with a lens moving mechanism.

  The parallel plate F is not essential, and for example, it is desirable that the wavelength selection filter is not provided as a separate structure and its function is imparted to the lens. For example, in the case of an infrared cut filter, infrared cut coating may be performed on one or a plurality of lens surfaces.

  Applications of the imaging lens 10 or the imaging apparatus 100 include security cameras or marketing camera lenses such as surveillance cameras, door phone cameras, and authentication cameras, in-vehicle camera lenses mounted on automobiles and other moving objects, medical endoscopes, Examples include healthcare measurement, industrial endoscopes, other medical or industrial optical lenses, and the like. In addition to the above, of course, the imaging lens 10 or the imaging device 100 may be applied to applications that require a wider angle.

〔Example〕
Examples of the imaging lens according to the present invention will be described below. Symbols used in each example are as follows. The unit for length is mm unless otherwise indicated, and the unit of angle is ° (degrees).
Fno: F value 2w: Maximum total angle of view PD: Temperature defocus when changing at 30 ° C (considering changes in refractive index and linear expansion)
R: radius of curvature d: spacing between top surfaces of axes nd: refractive index of lens material with respect to d-line vd: Abbe number of lens material

ただし、
Ａｉ：ｉ次の非球面係数
Ｒ ：曲率半径
Ｋ ：円錐定数 In each embodiment, the surface described with “*” after each surface number is a surface having an aspheric shape, and the shape of the aspheric surface has the vertex of the surface as the origin and the X axis in the optical axis direction. The height in the direction perpendicular to the optical axis is h, and is expressed by the following “Equation 1”.

However,
Ai: i-order aspheric coefficient R: radius of curvature K: conic constant

[Example 1]
The basic optical specification values of the imaging lens of Example 1 are shown below.
Fno = 2.03
2w = 134 °
PD = 0.009mm

The lens surface data of Example 1 is shown in Table 1 below. In Table 1 etc., the surface number is represented by “SN” and the infinity is represented by “infinity”. In the surface number, the lens surface is represented by “L1S1”, the aperture stop is represented by “AS”, the object side surface of the parallel plate is represented by “CGS1”, and the image side surface of the parallel plate is represented by “CGS2”. In the lens surface notation, the first half symbol Ln (n = 1 to 5) indicates the nth lens (specifically, the first to fifth lenses), and the second half symbol S1 is the nth lens. The object side surface of the lens is indicated, and the symbol S2 in the latter half indicates the image side surface of the nth lens. Furthermore, the symbol CG indicates a parallel plate. The value d of the axial upper surface interval means the distance from the surface of the column to the surface of the lower left column. Specifically, for example, the value d on the right side of the image side surface “CGS2” of the parallel plate indicates the axial top surface distance from the image side surface of the parallel plate to the imaging surface I (or the imaging surface).
[Table 1]
SN R d nd vd
L1S1 20.00 2.200 1.713 53.9
L1S2 2.70 2.645
L2S1 * -9.53 3.300 1.635 23.9
L2S2 * -5.64 -0.173
AS infinity 1.972
L3S1 14.30 1.600 1.713 53.9
L3S2 -4.80 0.423
L4S1 * -6.59 0.700 1.635 23.9
L4S2 * 4.18 0.083
L5S1 * 4.53 2.740 1.531 56.0
L5S2 * -4.52 2.100
CGS1 infinity 0.700 1.517 64.2
CGS2 infinity 3.200

The aspheric coefficients of the lens surfaces of Example 1 are shown in Table 2 below. In the following (including the lens data in the table), a power of 10 (for example, 2.5 × 10 ⁻⁰² ) is expressed using e (for example, 2.5E-02).
[Table 2]
Surface [L2S1]
K = 8.5122E + 00, A4 = -3.9639E-04, A6 = -1.2593E-03,
A8 = 8.6878E-04, A10 = -2.9800E-04, A12 = 4.9280E-05,
A14 = -3.1467E-06, A16 = 0.0000E + 00
Surface [L2S2]
K = 3.7767E + 00, A4 = 1.8769E-03, A6 = 1.2447E-03,
A8 = -7.7400E-04, A10 = 3.1173E-04, A12 = -5.6148E-05,
A14 = 3.9256E-06, A16 = 0.0000E + 00
Surface [L4S1]
K = -1.0041E + 01, A4 = -1.5528E-02, A6 = 4.7349E-03,
A8 = -2.7621E-03, 10 = 9.7684E-04, A12 = -1.9513E-04,
A14 = 2.0048E-05, A16 = -7.9636E-07
Surface [L4S2]
K = -1.7041E + 00, A4 = -4.8153E-04, A6 = 1.2819E-04,
A8 = -1.0475E-03, A10 = 4.2896E-04, A12 = -8.0295E-05,
A14 = 7.5442E-06, A16 = -2.9036E-07
Surface [L5S1]
K = 6.1133E-01, A4 = 2.6316E-03, A6 = -2.6231E-03,
A8 = 1.5969E-04, A10 = 7.1418E-05, A12 = -1.7153E-05,
A14 = 1.5422E-06, A16 = -5.2690E-08
Surface [L5S2]
K = -3.5544E-01, A4 = -1.8446E-04, A6 = -5.9860E-05,
A8 = 4.7716E-05, A10 = -5.5970E-06, A12 = 7.4749E-08,
A14 = 6.4323E-08, A16 = -3.6356E-09

  FIG. 2A is a cross-sectional view of the imaging lens 11 of the first embodiment. The imaging lens 11 includes a first lens L1 that is convex toward the object side and has a negative meniscus, a second lens L2 that is convex toward the image side and is a positive meniscus, a third lens L3 that is biconvex and positive, and a negative first lens L2 that is both concave and negative. Four lenses L4 and a biconvex positive fifth lens L5 are provided. Among these, the first and third lenses L1, L3 are both spherical type lenses, and the second, fourth, and fifth lenses L2, L4, L5 are both aspherical type lenses. An aperture stop AS is disposed between the second lens L2 and the third lens L3. Note that an imaging surface I is disposed on the image side of the fifth lens L5 via a parallel plate F such as a filter.

  2 (B) to 2 (D) show longitudinal aberrations (spherical aberration, astigmatism, distortion) of the imaging lens 11 of Example 1. FIG.

[Example 2]
The basic optical specification values of the imaging lens of Example 2 are shown below.
Fno = 2.11
2w = 142 °
PD = 0.009mm

The lens surface data of Example 2 is shown in Table 3 below.
[Table 3]
SN R d nd vd
L1S1 20.00 1.200 1.713 53.9
L1S2 2.70 2.675
L2S1 * -9.53 3.300 1.635 23.9
L2S2 * -5.64 -0.173
AS infinity 1.972
L3S1 14.30 1.600 1.713 53.9
L3S2 -4.80 0.423
L4S1 * -6.59 0.700 1.635 23.9
L4S2 * 4.18 0.083
L5S1 * 4.53 2.740 1.531 56.0
L5S2 * -4.52 2.100
CGS1 infinity 0.700 1.517 64.2
CGS2 infinity 3.190

The aspherical coefficients of the lens surfaces of Example 2 are shown in Table 4 below.
[Table 4]
Surface [L2S1]
K = 8.5122E + 00, A4 = -3.9639E-04, A6 = -1.2593E-03,
A8 = 8.6878E-04, A10 = -2.9800E-04, A12 = 4.9280E-05,
A14 = -3.1467E-06, A16 = 0.0000E + 00
Surface [L2S2]
K = 3.7767E + 00, A4 = 1.8769E-03, A6 = 1.2447E-03,
A8 = -7.7400E-04, A10 = 3.1173E-04, A12 = -5.6148E-05,
A14 = 3.9256E-06, A16 = 0.0000E + 00
Surface [L4S1]
K = -1.0041E + 01, A4 = -1.5528E-02, A6 = 4.7349E-03,
A8 = -2.7621E-03, A10 = 9.7684E-04, A12 = -1.9513E-04,
A14 = 2.0048E-05, A16 = -7.9636E-07
Surface [L4S2]
K = -1.7041E + 00, A4 = -4.8153E-04, A6 = 1.2819E-04,
A8 = -1.0475E-03, A10 = 4.2896E-04, A12 = -8.0295E-05,
A14 = 7.5442E-06, A16 = -2.9036E-07
Surface [L5S1]
K = 6.1133E-01, A4 = 2.6316E-03, A6 = -2.6231E-03,
A8 = 1.5969E-04, A10 = 7.1418E-05, A12 = -1.7153E-05,
A14 = 1.5422E-06, A16 = -5.2690E-08
Surface [L5S2]
K = -3.5544E-01, A4 = -1.8446E-04, A6 = -5.9860E-05,
A8 = 4.7716E-05, A10 = -5.5970E-06, A12 = 7.4749E-08,
A14 = 6.4323E-08, A16 = -3.6356E-09

  FIG. 3A is a cross-sectional view of the imaging lens 12 of the second embodiment. The imaging lens 12 includes a first lens L1 that is convex toward the object side and has a negative meniscus, a second lens L2 that is convex toward the image side and is a positive meniscus, a third lens L3 that is biconvex and positive, and a first lens L3 that is both concave and negative. Four lenses L4 and a biconvex positive fifth lens L5 are provided. Among these, the first and third lenses L1, L3 are both spherical type lenses, and the second, fourth, and fifth lenses L2, L4, L5 are both aspherical type lenses. An aperture stop AS is disposed between the second lens L2 and the third lens L3. Note that an imaging surface I is disposed on the image side of the fifth lens L5 via a parallel plate F such as a filter.

  3 (B) to 3 (D) show longitudinal aberrations (spherical aberration, astigmatism, distortion) of the imaging lens 12 of Example 2. FIG.

Example 3
The basic optical specification values of the imaging lens of Example 3 are shown below.
Fno = 2.02
2w = 134 °
PD = 0.006mm

The lens surface data of Example 3 is shown in Table 5 below.
[Table 5]
SN R d nd vd
L1S1 20.10 1.900 1.713 53.9
L1S2 2.790 2.568
L2S1 * -8.057 3.094 1.635 23.9
L2S2 * -5.232 0.518
AS infinity 1.792
L3S1 13.630 1.600 1.713 53.9
L3S2 -4.700 0.448
L4S1 * -4.537 0.700 1.635 23.9
L4S2 * 5.603 0.110
L5S1 * 4.656 2.770 1.531 56.0
L5S2 * -4.453 2.100
CGS1 infinity 0.700 1.517 64.2
CGS2 infinity 3.200

Table 6 below shows the aspheric coefficients of the lens surfaces of Example 3.
[Table 6]
Surface [L2S1]
K = 4.0979E + 00, A4 = -1.4325E-03, A6 = 1.3888E-04,
A8 = 6.4509E-06, A10 = -1.2718E-05, A12 = 2.7673E-06,
A14 = -1.8618E-07, A16 = 0.0000E + 00
Surface [L2S2]
K = 3.1781E + 00, A4 = 3.3165E-03, A6 = 6.0534E-05,
A8 = 9.2743E-05, A10 = 1.2563E-05, A12 = -6.4648E-06,
A14 = 8.6405E-07, A16 = 0.0000E + 00
Surface [L4S1]
K = -1.2719E + 01, A4 = -7.8506E-03, A6 = -3.5585E-03,
A8 = 1.6544E-03, A10 = -3.1284E-04, A12 = 4.4307E-06,
A14 = 6.4040E-06, A16 = -6.3216E-07
Surface [L4S2]
K = -1.1277E-01, A4 = 2.4379E-02, A6 = -2.1914E-02,
A8 = 9.4597E-03, A10 = -2.4870E-03, A12 = 3.9421E-04,
A14 = -3.4525E-05, A16 = 1.2822E-06
Surface [L5S1]
K = 1.6361E-01, A4 = 1.1118E-02, A6 = -1.3810E-02,
A8 = 5.5904E-03, A10 = -1.3230E-03, A12 = 1.8611E-04,
A14 = -1.4350E-05, A16 = 4.6803E-07
Surface [L5S2]
K = 1.3956E-01, A4 = -4.9788E-04, A6 = 3.6684E-04,
A8 = -7.5647E-05, A10 = 4.1936E-06, A12 = 1.4651E-06,
A14 = -2.5799E-07, A16 = 1.3256E-08

  FIG. 4A is a cross-sectional view of the imaging lens 13 of the third embodiment. The imaging lens 13 includes a first lens L1 that is convex toward the object side and has a negative meniscus, a second lens L2 that is convex toward the image side and is a positive meniscus, a third lens L3 that is biconvex and positive, and a first lens L3 that is both concave and negative. Four lenses L4 and a biconvex positive fifth lens L5 are provided. Among these, the first and third lenses L1, L3 are both spherical type lenses, and the second, fourth, and fifth lenses L2, L4, L5 are both aspherical type lenses. An aperture stop AS is disposed between the second lens L2 and the third lens L3. Note that an imaging surface I is disposed on the image side of the fifth lens L5 via a parallel plate F such as a filter.

  4B to 4D show the longitudinal aberrations (spherical aberration, astigmatism, distortion) of the imaging lens 13 of Example 3. FIG.

Table 7 below summarizes the values of Examples 1 to 3 corresponding to the conditional expressions (1) to (11) for reference.
[Table 7]

  The image pickup lens according to the embodiment has been described above, but the image pickup lens according to the present invention is not limited to the above example. For example, in the above embodiment, a lens having substantially no refractive power can be added between the first to fifth lenses L1 to L5, or on the image side or the object side thereof.

  In the first to third embodiments, the fourth and fifth lenses L4 and L5 are not fitted, but both lenses L4 and L5 can be fitted in the same manner as shown in FIG.

  Moreover, in the said embodiment, about the parallel plate F, when imaging with visible light or near-infrared light in uses, such as a vehicle-mounted camera and a surveillance camera, the filter which is a parallel plate is divided | segmented into 2 sheets, and each is separate. It is also possible to adopt a configuration such as having the role of

  AX: Optical axis, F: Parallel plate, G1: Front group, G2: Rear group, I ... Imaging surface, L1-L5 ... Lens, OP1 ... Aperture, 10 ... Imaging lens, 11-13 ... Imaging lens, 14a ... Outer circumference 15a ... Flange part, 15c ... Receiving part, 30 ... Camera module, 41 ... Lens barrel, 50 ... Sensor part, 51 ... Solid-state imaging device, 51a ... Photoelectric conversion part, 60 ... Processing part, 61 ... Drive part, 64 ... Display unit 68 ... Control unit 100 ... Imaging device

Claims (8)

In order from the object side,
A spherical first lens formed of glass, having negative power, and having a convex meniscus shape on the object side;
A second lens made of plastic and having a positive power and having at least one aspheric shape;
A third lens made of glass and having positive power;
A fourth lens made of plastic and having negative power and having at least one aspheric shape; and substantially from a fifth lens made of plastic and having positive power and having at least one aspheric shape. Become
An imaging lens satisfying the following conditional expression:
0 <f / f2 <0.3 (1)
−1.0 <f4 / f5 <−0.75 (2)
0 ≦ D45 / f <0.04 (3)
−1.5 <f4 / f <−1.0 (4)
here,
f: focal length of the entire lens system f2: focal length of the second lens f4: focal length of the fourth lens f5: focal length of the fifth lens D45: optical axis between the fourth lens and the fifth lens Top spacing The imaging lens according to claim 1, wherein the materials of the first to fifth lenses satisfy the following conditional expression.
60>vd1> 45 (5)
35>vd2> 20 (6)
60>vd3> 45 (7)
35>vd4> 20 (8)
60>vd5> 50 (9)
here,
vd1: Abbe number of the first lens at the d-line vd2: Abbe number of the second lens at the d-line vd3: Abbe number of the third lens at the d-line vd4: d-line of the fourth lens at the d-line Abbe number vd5: Abbe number at the d-line of the fifth lens A diaphragm disposed between the second lens and the third lens;
3. The imaging lens according to claim 1, wherein the following conditional expression is satisfied when the object side from the diaphragm is a front group and the image side from the diaphragm is a rear group.
−2.5 <ff / fr <−1.8 (10)
here,
ff: focal length of the front group fr: focal length of the rear group   The imaging lens according to any one of claims 1 to 3, wherein the fourth lens and the fifth lens are fitted to each other and fixed to each other.   The imaging lens according to claim 1, wherein the third lens has at least one aspheric surface. The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
R2 <R1 (11)
here,
R1: radius of curvature on the object side of the first lens R2: radius of curvature on the image side of the first lens The imaging lens according to any one of claims 1 to 6,
A lens barrel for holding the imaging lens;
A lens unit comprising: A lens unit according to claim 7;
An image sensor that projects an image by the lens unit;
An imaging apparatus comprising:

Images