JP2006119262A - Imaging lens - Google Patents

Abstract

An object of the present invention is to provide an imaging lens capable of suppressing aberrations in the peripheral portion of an image and reducing the ratio of the entire length of the lens group and the outer diameter to the effective screen diagonal length of the imaging device. To do.
In order from the object side, a diaphragm 1, a first convex lens 2 having a biconvex surface and a positive refractive power, and a meniscus having a negative surface and a concave refractive surface on the object side. The second lens 3 having a shape and the third lens 4 having a convex surface on the object side and having a positive refractive power are included.
[Selection] Figure 1

Description

  The present invention relates to an imaging lens for an imaging apparatus using a solid-state imaging device such as a CCD solid-state imaging device or a CMOS solid-state imaging device, such as a small digital camera, a mobile phone camera, and a surveillance camera. .

Patent Document 1 discloses an imaging lens for an imaging apparatus using a solid-state imaging device such as a CCD-type solid-state imaging device or a CMOS-type solid-state imaging device such as a small digital camera, a mobile phone camera, and a surveillance camera in recent years. Something like that was known. The imaging lens includes, in order from the object side, an aperture stop, a biconvex first lens made of a plastic material, a second lens made of a plastic material and having a negative refractive power and having a concave surface facing the object side, and a plastic This is a triplet-type configuration composed of a third meniscus lens made of a material and having a convex surface facing the object side.
Japanese Patent Laid-Open No. 2004-4466

  However, in the imaging lens having the configuration described in the conventional example, since the refractive power of the first lens is larger than the refractive power of the third lens, aberrations in the peripheral portion of the image (particularly, distortion aberration, coma aberration). ) Gets worse. In addition, in order to suppress the aberration at the periphery of the image, the curvatures of the second lens and the third lens must be increased. As a result, there is a problem that not only the total length from the first lens to the third lens is increased, but also the outer diameters of these lenses are increased.

  The present invention solves the above-described problems, and provides an imaging lens that can suppress the aberration of the peripheral portion of an image and reduce the ratio of the entire length of the lens group and the outer diameter to the effective screen diagonal length of the imaging device. The purpose is to provide.

  In order to achieve this object, according to the first aspect of the present invention, in order from the object side, the stop, the object-side surface is a convex surface, and the image-side surface is a convex surface or a flat surface. And a first lens having a positive refractive power, the object side surface is a concave surface, a meniscus second lens having a negative refractive power, and the object side surface is a convex surface, Each of the first lens, the second lens, and the third lens has an aspheric surface on at least one surface, and the following conditions (1) to ( 4) An imaging lens configured to satisfy 4), which can suppress aberrations at the periphery of the image and reduce the ratio of the entire length of the lens group and the outer diameter with respect to the effective screen diagonal length of the imaging device. Has an effect.

(1) 1.00 <f / f ₁ <1.50
(2) 1.40 <f / | f ₂ | <1.95
(3) 1.00 <f / f ₃ <1.85
(4) 0.65 <f ₁ / f ₃ <1.60
However,
f: Composite focal length of the entire imaging lens f ₁ : Focal length of the first lens f ₂ : Focal length of the second lens f ₃ : Focal length of the third lens By defining the range of the condition (1) in the above configuration Thus, it is possible to obtain an image in which spherical aberration and coma are suppressed from the center to the periphery of the effective screen of the image sensor. If the upper limit of condition (1) is exceeded, the refractive power of the first lens becomes too strong, and it becomes difficult to ensure a sufficient angle of view, and at the same time, spherical aberration generated in the first lens increases. If the lower limit of the condition (1) is exceeded, the refractive power of the first lens becomes too weak, so it is necessary to give the third lens a strong refractive power. Since it is bent, the meridional image plane is greatly curved to the negative side at the periphery of the effective screen of the image sensor, resulting in a decrease in resolution.

  Furthermore, by setting the range of the condition (2), it is possible to obtain an image in which spherical aberration, coma aberration, and field curvature are suppressed from the center portion to the peripheral portion of the effective screen of the image sensor. When the upper limit of the condition (2) is exceeded, the diverging action of incident light by the second lens becomes too strong, so that the first lens or the third lens requires a strong refractive power. However, if the refractive power of the first lens is too strong, the spherical aberration generated in the first lens increases, and at the same time it is difficult to ensure a sufficient angle of view. Also, if the refractive power of the third lens is too strong, the light rays are strongly bent at the periphery of this lens, so that the meridional image plane is greatly curved to the negative side at the periphery of the effective screen of the image sensor, resulting in a decrease in resolution. Invite. If the lower limit of condition (2) is exceeded, the diverging action of incident light by the second lens becomes too weak, making it difficult to make the incident light reach the periphery of the effective screen of the image sensor.

  By setting the range in the condition (3), field curvature at the periphery of the effective screen of the image sensor is suppressed, and an image with uniform illuminance can be obtained over the entire effective screen of the image sensor. If the upper limit of the condition (3) is exceeded, the refractive index of the third lens becomes too strong, so that the meridional image plane is greatly curved to the negative side at the periphery of the effective screen of the image sensor, leading to a decrease in resolution. If the lower limit of the condition (3) is exceeded, the refractive power of the third lens becomes too weak, so that the incident angle of light incident on the periphery of the effective screen of the image sensor increases, but the sensitivity of the image sensor is the incident angle. The larger the value, the lower it. For this reason, the illuminance at the periphery of the effective screen of the image sensor is relatively undesirably lower than the illuminance at the center.

  By setting the range in the condition (4), it is possible to suppress the occurrence of spherical aberration from the central part to the peripheral part of the effective screen of the image sensor. If the upper limit of condition (4) is exceeded, the third lens will have a large spherical aberration because the refractive power of the third lens is too strong for the first lens.

  If the lower limit of condition (4) is exceeded, the refractive power of the first lens is too strong for the third lens, and thus large spherical aberration occurs in the first lens.

  The invention according to claim 2 is an imaging lens having a configuration satisfying the following conditions (5) to (7) in the invention according to claim 1, and can further suppress the aberration of the peripheral portion of the image. There is an effect.

(5) | r ₁ / r ₂ | <0.55
(6) 1.90 <f / | r ₄ | <3.20
(7) f / | r ₆ | <0.65
However,
r ₁ : radius of curvature of the object side surface of the first lens r ₂ : radius of curvature of the image side surface of the first lens r ₄ : radius of curvature of the image side surface of the second lens r ₆ : image of the third lens Radius of curvature of side surface By setting the range within the condition (5) in the above configuration, it is possible to keep a wide angle of view while suppressing the occurrence of spherical aberration in the first lens. When the upper limit of condition (5) is exceeded, large spherical aberration occurs on the image side surface of the first lens, and at the same time, it becomes difficult to keep the angle of view wide.

  Furthermore, by setting the range of the condition (6), it is possible to cause the incident light rays to reach the peripheral portion of the effective screen of the image sensor while suppressing the occurrence of spherical aberration and coma on the image side surface of the second lens. it can. If the upper limit of condition (6) is exceeded, spherical aberration occurring on the image side surface of the second lens will increase. Further, since the radius of curvature becomes small, it becomes difficult to manufacture the lens. When the lower limit of the condition (6) is exceeded, the radius of curvature of the object side surface of the second lens inevitably increases under the condition that satisfies the condition (2). This makes it difficult to sufficiently correct spherical aberration generated on the image side surface of the first lens. In addition, it becomes difficult to make incident light rays reach the periphery of the effective screen of the image sensor.

  By setting the range in the condition (7), it is possible to suppress the occurrence of field curvature at the periphery of the effective screen of the image sensor. If the upper limit of the condition (7) is exceeded, the light rays are strongly bent at the periphery of the image side surface of the third lens, so that the meridional image plane is greatly curved to the negative side at the periphery of the effective screen of the image sensor. Cause a decline.

  The invention according to claim 3 is an imaging lens having a configuration satisfying the following condition (8) in the invention according to claim 1, and has the effect of further suppressing chromatic aberration.

(8) 25 <ν ₁ −ν ₂
However,
ν ₁ : Abbe number of the first lens ν ₂ : Abbe number of the second lens By setting the Abbe number within the range of the condition (8) in the above configuration, the occurrence of chromatic aberration can be suppressed. When the lower limit of the condition (8) is exceeded, chromatic aberration correction by the first lens and the second lens becomes insufficient, and color blur occurs within the effective screen of the image sensor.

  Invention of Claim 4 is an imaging lens of the structure which satisfies the following conditions (9)-(12) in the invention of Claim 1, and keeping the optical total length of the whole imaging lens system short. There is an effect that the back focus can be lengthened.

(9) L / 2H <1.1
(10) b _f /2H>0.5
(11) D _max /2H<0.70
(12) 0 <( _{HD max} / 2) / b _f <0.43
However,
L: Total optical length of the entire imaging lens system 2H: Effective screen diagonal length of imaging device b _f : Back focus D _max : Maximum value among effective optical diameters of all lens surfaces Within the range of condition (9) in the above configuration By defining, it is possible to realize an imaging lens in which the entire optical length of the entire imaging lens system is shorter than the effective screen diagonal length of the imaging device. If the upper limit of condition (9) is exceeded, a small imaging lens that can be mounted on a mobile phone is realized when an imaging device with an effective screen diagonal length of 6 mm and a size of 1/3 inch or more is used. It becomes difficult to do.

  Furthermore, it is possible to ensure a sufficient back focus by setting the condition (10). When the lower limit of the condition (10) is exceeded, it becomes difficult to insert an optical element such as an IR cut filter or an OLPF between the image side surface of the third lens and the imaging element. In addition, it becomes difficult to sufficiently reduce the incident angle when light emitted from the image-side surface of the third lens reaches the peripheral portion of the effective screen of the image sensor, and the illuminance at the peripheral portion is reduced by the image sensor. It is lower than the illuminance at the center of the.

  By setting the condition (11) in the range, the maximum effective outer diameter of the lens can be made smaller than the effective screen diagonal length of the image sensor. If the upper limit of condition (11) is exceeded, the maximum effective outer diameter of the lens becomes too large. For this reason, it becomes difficult to mount the device on a device having a limited installation area, such as a mobile phone.

  By setting the range in the condition (12), it is possible to make the illuminance uniform at the central portion and the peripheral portion of the effective screen of the image pickup device, and to reduce the maximum effective outer diameter of the lens. If the upper limit of the condition (12) is exceeded, the incident angle when the emitted light from the image-side surface of the third lens reaches the periphery of the effective screen of the image sensor increases, and the center of the effective screen of the image sensor Illuminance at is reduced. When the lower limit of the condition (12) is exceeded, the maximum effective outer diameter of the lens becomes larger than the effective diagonal length of the image sensor, which is not preferable in terms of downsizing the image pickup lens.

  A fifth aspect of the present invention is the imaging lens according to the first aspect of the present invention, wherein the first lens and the third lens are made of glass material, and the length and outer diameter of the entire lens group can be reduced. Play.

  A sixth aspect of the present invention is the imaging lens according to the first aspect of the present invention, wherein the first lens to the third lens are made of a glass material, and not only the length and outer diameter of the entire lens group can be reduced, but also chromatic aberration. There is an effect that it becomes easy to suppress this.

  A seventh aspect of the present invention is the imaging lens according to the first aspect of the present invention, wherein the image side surface of the third lens is a spherical surface or a flat surface, and the lens shape and the dimensional tolerance between the lenses are reduced. And the production effect can be improved.

  The imaging lens of the present invention includes, in order from the object side, a diaphragm, a first lens having a positive refractive power, the object side surface being a convex surface, and the image side surface being a convex surface or a flat surface. A second meniscus lens having a negative refractive power and a negative refractive power, and a third lens having a positive refractive power and a positive refractive power. Since each of the first lens, the second lens, and the third lens has an aspheric surface on at least one surface, and is configured to satisfy the following conditions (1) to (4), Aberrations at the periphery of the image can be suppressed, and the ratio of the overall length of the lens group and the outer diameter to the effective screen diagonal length of the image sensor can be reduced.

(1) 1.00 <f / f ₁ <1.50
(2) 1.40 <f / | f ₂ | <1.95
(3) 1.00 <f / f ₃ <1.85
(4) 0.65 <f ₁ / f ₃ <1.60
However,
f: Composite focal length of the entire imaging lens f ₁ : Focal length of the first lens f ₂ : Focal length of the second lens f ₃ : Focal length of the third lens

  FIG. 1 is an explanatory diagram showing a schematic arrangement of imaging lenses according to an embodiment of the present invention.

  In FIG. 1, 1 is an aperture, 2, 3 and 4 are first, second and third lenses made of a glass material, 5 is an infrared light filter (hereinafter referred to as an IR cut filter), and 6 is an image sensor. It is. Further, in FIG. 1, in order from the object side, the aperture 1, the first lens 2 having a positive refractive power, the object side surface being a convex surface, the image side surface being a convex surface, and the object The second surface 3 is a meniscus-shaped second lens 3 having a negative refractive power and a negative refractive power, and the third lens 4 having a convex surface and a positive refractive power. The first lens 2 and the second lens 3 are both aspherical, the object-side surface of the third lens 4 is aspherical, and the image-side surface is composed of a spherical surface. (1) to (4) are satisfied.

(1) 1.00 <f / f ₁ <1.50
(2) 1.40 <f / | f ₂ | <1.95
(3) 1.00 <f / f ₃ <1.85
(4) 0.65 <f ₁ / f ₃ <1.60
However,
f: Composite focal length of the entire imaging lens system f ₁ : Focal length of the first lens f ₂ : Focal length of the second lens f ₃ : Focal length of the third lens With this configuration, it is possible to suppress aberrations in the peripheral portion of the image. At the same time, the ratio of the overall length of the lens group and the outer diameter to the effective screen diagonal length of the image sensor 6 can be reduced.

  More specifically, by setting the range of the condition (1) in the above configuration, an image in which spherical aberration and coma aberration are suppressed from the center to the periphery of the effective screen of the image sensor 6 can be obtained. Is possible. If the upper limit of condition (1) is exceeded, the refractive power of the first lens becomes too strong, so that it becomes difficult to ensure a sufficient angle of view, and at the same time, the spherical aberration generated in the first lens 2 increases. If the lower limit of the condition (1) is exceeded, the refractive power of the first lens 2 becomes too weak, so it is necessary to give the third lens 4 a strong refractive power. Since the light rays are strongly bent, the meridional image plane is greatly curved to the negative side at the periphery of the effective screen of the image sensor 6 and the resolution is lowered.

  Furthermore, by setting the range of the condition (2), it is possible to obtain an image in which spherical aberration, coma aberration, and field curvature are suppressed from the center to the periphery of the effective screen of the image sensor 6. . If the upper limit of the condition (2) is exceeded, the diverging action of incident light by the second lens 3 becomes too strong, so that the first lens 2 or the third lens 4 needs a strong refractive power. However, if the refractive power of the first lens 2 is too strong, the spherical aberration generated in the first lens 2 increases and it becomes difficult to ensure a sufficient angle of view. If the refractive power of the third lens 4 is too strong, the light beam is strongly bent at the periphery of the lens 4, so that the meridional image plane is greatly curved to the negative side at the periphery of the effective screen of the image sensor 6. Cause a decline. If the lower limit of condition (2) is exceeded, the diverging action of incident light by the second lens 3 becomes too weak, making it difficult to make the incident light reach the periphery of the effective screen of the image sensor 6.

  By setting in the range of condition (3), curvature of field at the periphery of the effective screen of the image sensor 6 is suppressed, and an image with uniform illuminance can be obtained over the entire effective screen of the image sensor 6. . If the upper limit of condition (3) is exceeded, the refractive index of the third lens 4 becomes too strong, so that the meridional image plane is greatly curved to the negative side at the periphery of the effective screen of the image sensor 6 and the resolution is lowered. If the lower limit of the condition (3) is exceeded, the refractive power of the third lens 4 becomes too weak, so that the incident angle of light incident on the periphery of the effective screen of the image sensor 6 increases. However, the sensitivity of the image sensor 6 is It decreases as the incident angle increases. Therefore, the illuminance at the periphery of the effective screen of the image sensor 6 is relatively undesirably lower than the illuminance at the center.

  By setting the range in the condition (4), it is possible to suppress the occurrence of spherical aberration from the central portion to the peripheral portion of the effective screen of the image sensor 6. If the upper limit of the condition (4) is exceeded, the third lens 4 has a large refracting power with respect to the first lens 2, so that a large spherical aberration occurs in the third lens 4.

  When the lower limit of the condition (4) is exceeded, the refractive power of the first lens 2 is too strong for the third lens 4, and thus large spherical aberration occurs in the first lens 2.

  In the present embodiment, since all of the first lens 2, the second lens 3, and the third lens 4 are made of glass material, it is easy to suppress chromatic aberration.

  In the present embodiment, since the image-side surface of the third lens 4 is a spherical surface, the lens shape and the dimensional tolerance between the lenses can be relaxed, and the manufacturing yield can be improved.

  Moreover, in this Embodiment, although the example in which all the 1st lens 2, the 2nd lens 3, and the 3rd lens 4 were formed from the glass material was demonstrated, the 1st lens 2 and the 3rd lens 4 are made of glass material. A sufficient effect can be obtained even with the structure formed from the above.

  Further, in the present embodiment, the example in which the image side surface of the third lens 4 is a spherical surface has been described, but a sufficient effect can be obtained even in a configuration in which the surface is a flat surface.

  In the present embodiment, since the configuration satisfies the following conditions (5) to (7), the aberration in the peripheral portion of the image can be further suppressed.

(5) | r ₁ / r ₂ | <0.55
(6) 1.90 <f / | r ₄ | <3.20
(7) f / | r ₆ | <0.65
However,
r ₁ : radius of curvature of the object side surface of the first lens r ₂ : radius of curvature of the image side surface of the first lens r ₄ : radius of curvature of the image side surface of the second lens r ₆ : image of the third lens The radius of curvature of the side surface will be described in more detail. By defining the range within the condition (5) in the above configuration, the angle of view can be kept wide while suppressing the occurrence of spherical aberration in the first lens 2. If the upper limit of the condition (5) is exceeded, large spherical aberration occurs on the image side surface of the first lens 2 and at the same time it is difficult to keep the angle of view wide.

  Furthermore, by setting the range of the condition (6), the incident light beam reaches the peripheral portion of the effective screen of the image sensor 6 while suppressing the occurrence of spherical aberration and coma aberration on the image side surface of the second lens 3. be able to. If the upper limit of condition (6) is exceeded, spherical aberration occurring on the image side surface of the second lens 3 increases. Further, since the radius of curvature becomes small, it becomes difficult to manufacture the lens. When the lower limit of the condition (6) is exceeded, the radius of curvature of the object side surface of the second lens 3 inevitably increases under the condition that satisfies the condition (2). Therefore, it is difficult to sufficiently correct spherical aberration generated on the image side surface of the first lens 2. In addition, it becomes difficult to make incident light rays reach the periphery of the effective screen of the image sensor 6.

  By setting the range in the condition (7), it is possible to suppress the occurrence of field curvature at the periphery of the effective screen of the image sensor 6. If the upper limit of condition (7) is exceeded, the light rays are strongly bent at the periphery of the image side surface of the third lens 4, so that the meridional image plane is greatly curved to the negative side at the periphery of the effective screen of the image sensor 6. Incurs a decrease in resolution.

  In the present embodiment, chromatic aberration can be further suppressed by satisfying the following condition (8).

(8) 25 <ν ₁ −ν ₂
However,
ν ₁ : Abbe number of the first lens ν ₂ : Abbe number of the second lens More specifically, the occurrence of chromatic aberration can be suppressed by setting the condition within the range of condition (8) in the above configuration. When the lower limit of condition (8) is exceeded, chromatic aberration correction by the first lens 2 and the second lens 3 becomes insufficient, and color blur occurs in the effective screen of the image sensor 6.

  In the present embodiment, the configuration satisfying the following conditions (9) to (12) can increase the back focus while keeping the entire optical length of the entire imaging lens system short.

(9) L / 2H <1.1
(10) b _f /2H>0.5
(11) D _max /2H<0.70
(12) 0 <( _{HD max} / 2) / b _f <0.43
However,
L: Total optical length of the entire imaging lens system 2H: Effective screen diagonal length of imaging device b _f : Back focus D _max : Maximum value among effective optical diameters of all lens surfaces By setting the range in the condition (9), it is possible to realize an imaging lens in which the entire optical length of the imaging lens system is shorter than the effective screen diagonal length of the imaging device 6. If the upper limit of the condition (9) is exceeded, the effective screen diagonal length of the image sensor 6 is 6 mm. When the image sensor 6 having a size of 1/3 inch or more is used, a compact image pickup lens that can be mounted on a mobile phone. It becomes difficult to realize.

  Furthermore, it is possible to ensure a sufficient back focus by setting the condition (10). If the lower limit of condition (10) is exceeded, it will be difficult to insert the IR cut filter 5 between the image-side surface of the third lens 4 and the image sensor 6. In addition, it becomes difficult to sufficiently reduce the incident angle when the emitted light from the image-side surface of the third lens 4 reaches the peripheral portion of the effective screen of the image sensor 6, and the illuminance at the peripheral portion is reduced. It is lower than the illuminance at the center of the image sensor 6.

  By setting the range in the condition (11), the maximum effective outer diameter of the lens can be made smaller than the effective screen diagonal length of the image sensor 6. If the upper limit of condition (11) is exceeded, the maximum effective outer diameter of the lens becomes too large. For this reason, it becomes difficult to mount the device on a device having a limited installation area, such as a mobile phone.

  By setting the range in the condition (12), it is possible to make the illuminance uniform at the central portion and the peripheral portion of the effective screen of the image sensor 6 and at the same time reduce the maximum effective outer diameter of the lens. If the upper limit of the condition (12) is exceeded, the incident angle when the emitted light from the image-side surface of the third lens 4 reaches the peripheral portion of the effective screen of the image sensor 6 becomes large, and the effective screen of the image sensor 6 The illuminance at the center of the is reduced. If the lower limit of the condition (12) is exceeded, the maximum effective outer diameter of the lens becomes larger than the effective diagonal length of the image sensor 6, which is not preferable in terms of downsizing the image pickup lens.

  Next, although the specification of an imaging lens is demonstrated based on Examples 1-20, each specification is not limited to this. Here, symbols used in each example are as follows.

r: Paraxial radius of curvature d: Lens thickness or lens spacing n _d : Refractive index of d line ν _d : Abbe number of d line D: Optical effective diameter of lens In each example, the aspherical shape of the lens is Using an orthogonal coordinate system in which the z-axis is in the optical axis direction and the x-axis and the y-axis are in the direction orthogonal to the optical axis, the following expression is used.

Incidentally, notation K and A _p in the table is defined as follows.

For example, “6.0023456E-4” represents 6.023456 × 10 ⁻⁴ .

In each embodiment, the IR cut filter 5 is installed in front of the image plane of the image sensor 6, but the total optical length L and back focus b _f of the entire image pickup lens system are the thickness of the IR cut filter 5. Calculated by converting to air.

Example 1
Data of the imaging lens is shown in (Table 1), (Table 2), and (Table 3).

  FIG. 2 is an explanatory diagram illustrating a schematic arrangement of the imaging lens according to the first embodiment. 2, the same components as those in FIG. 1 are denoted by the same reference numerals and detailed description thereof is omitted. FIG. 3 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 2)
Data of the imaging lens is shown in (Table 4), (Table 5), and (Table 6).

  FIG. 4 is an explanatory diagram illustrating a schematic arrangement of the imaging lens according to the second embodiment. 4, the same components as those in FIG. 1 are denoted by the same reference numerals and detailed description thereof is omitted. FIG. 5 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 3)
Data of the imaging lens is shown in (Table 7), (Table 8), and (Table 9).

  FIG. 6 is an explanatory diagram illustrating a schematic arrangement of the imaging lens of the third embodiment. In FIG. 6, the same components as those in FIG. FIG. 7 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

Example 4
Data of the imaging lens is shown in (Table 10), (Table 11), and (Table 12).

  FIG. 8 is an explanatory diagram illustrating a schematic arrangement of the imaging lens of the fourth embodiment. In FIG. 8, the same components as those in FIG. FIG. 9 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 5)
Data of the imaging lens is shown in (Table 13), (Table 14), and (Table 15).

  FIG. 10 is an explanatory diagram illustrating a schematic arrangement of the imaging lens of the fifth embodiment. 10, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 11 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 6)
Data of the imaging lens is shown in (Table 16), (Table 17), and (Table 18).

  FIG. 12 is an explanatory diagram illustrating a schematic arrangement of the imaging lens of the sixth embodiment. 12, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 13 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 7)
Data of the imaging lens is shown in (Table 19), (Table 20), and (Table 21).

  FIG. 14 is an explanatory diagram illustrating a schematic arrangement of the imaging lens of the seventh embodiment. 14, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 15 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 8)
Data of the imaging lens is shown in (Table 22), (Table 23), and (Table 24).

  FIG. 16 is an explanatory diagram illustrating a schematic arrangement of the imaging lens of the eighth embodiment. In FIG. 16, the same components as those in FIG. FIG. 17 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

Example 9
Data of the imaging lens is shown in (Table 25), (Table 26), and (Table 27).

  FIG. 18 is an explanatory diagram illustrating a schematic arrangement of the imaging lens of the ninth embodiment. In FIG. 18, the same components as those in FIG. FIG. 19 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 10)
Data of the imaging lens is shown in (Table 28), (Table 29), and (Table 30).

  FIG. 20 is an explanatory diagram illustrating a schematic arrangement of the imaging lens according to the tenth embodiment. 20, the same components as those in FIG. 1 are denoted by the same reference numerals and detailed description thereof is omitted. FIG. 21 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 11)
Data of the imaging lens is shown in (Table 31), (Table 32), and (Table 33).

  FIG. 22 is an explanatory diagram illustrating a schematic arrangement of the imaging lens of the eleventh embodiment. 22, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 23 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 12)
Data of the imaging lens is shown in (Table 34), (Table 35), and (Table 36).

  FIG. 24 is an explanatory diagram illustrating a schematic arrangement of the imaging lens of the twelfth embodiment. 24, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 25 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 13)
Data of the imaging lens is shown in (Table 37), (Table 38), and (Table 39).

  FIG. 26 is an explanatory diagram illustrating a schematic arrangement of the imaging lens of the thirteenth embodiment. In FIG. 26, the same components as those in FIG. FIG. 27 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 14)
Data of the imaging lens is shown in (Table 40), (Table 41), and (Table 42).

  FIG. 28 is an explanatory diagram showing a schematic arrangement of the imaging lens of Example 14. In FIG. 28, the same components as those in FIG. 1 are denoted by the same reference numerals and detailed description thereof is omitted. FIG. 29 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 15)
Data of the imaging lens is shown in (Table 43), (Table 44), and (Table 45).

  FIG. 30 is an explanatory diagram illustrating a schematic arrangement of the imaging lens of the fifteenth embodiment. 30, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 31 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 16)
Data of the imaging lens is shown in (Table 46), (Table 47), and (Table 48).

  FIG. 32 is an explanatory diagram illustrating a schematic arrangement of the imaging lens according to the sixteenth embodiment. 32, the same components as those in FIG. 1 are denoted by the same reference numerals and detailed description thereof is omitted. FIG. 33 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 17)
Data of the imaging lens is shown in (Table 49), (Table 50), and (Table 51).

  FIG. 34 is an explanatory diagram showing a schematic arrangement of the imaging lens of Example 17. 34, the same components as those in FIG. 1 are denoted by the same reference numerals and detailed description thereof is omitted. FIG. 35 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 18)
Data of the imaging lens is shown in (Table 52), (Table 53), and (Table 54).

  FIG. 36 is an explanatory diagram showing a schematic arrangement of the imaging lens of Example 18. In FIG. 36, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 37 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 19)
Data of the imaging lens is shown in (Table 55), (Table 56), and (Table 57).

  FIG. 38 is an explanatory diagram showing a schematic arrangement of the imaging lens of Example 19. 38, the same components as those in FIG. 1 are denoted by the same reference numerals and detailed description thereof is omitted. FIG. 39 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

(Example 20)
Data of the imaging lens is shown in (Table 58), (Table 59), and (Table 60).

  FIG. 40 is an explanatory diagram showing a schematic arrangement of the imaging lens of Example 20. In FIG. 40, the same components as those in FIG. 41 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG.

  INDUSTRIAL APPLICABILITY The present invention is useful as an imaging lens that can suppress aberrations in the peripheral portion of an image and reduce the ratio of the overall length of the lens group and the outer diameter to the effective screen diagonal length of the imaging device.

Explanatory drawing which shows schematic arrangement | positioning of the imaging lens in embodiment of this invention Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 1. FIG. Explanatory drawing which shows spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 2. FIG. Explanatory drawing which shows spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 3. FIG. Explanatory drawing which shows the spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 4. FIG. Explanatory drawing which shows spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 5. FIG. Explanatory drawing which shows spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 6. FIG. Explanatory drawing which shows spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 7. FIG. Explanatory drawing which shows the spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 8. FIG. Explanatory drawing which shows the spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 9. FIG. Explanatory drawing which shows spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 10. FIG. 20 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 11. FIG. Explanatory drawing which shows the spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 12. FIG. Explanatory drawing which shows the spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 13. FIG. 26 is an explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 14. FIG. Explanatory drawing which shows the spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 15. Explanatory diagram showing spherical aberration, distortion, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement of the imaging lens of Example 16. Explanatory drawing which shows the spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement of the imaging lens of Example 17. Explanatory drawing which shows the spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 18. FIG. Explanatory drawing which shows the spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement of the imaging lens of Example 19. Explanatory drawing which shows the spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG. Explanatory drawing which shows schematic arrangement | positioning of the imaging lens of Example 20. FIG. Explanatory drawing which shows spherical aberration, distortion aberration, and astigmatism of the imaging lens of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Diaphragm 2 1st lens 3 2nd lens 4 3rd lens 5 IR cut filter 6 Image sensor

Claims (7)

In order from the object side, the stop, the object-side surface is a convex surface, the image-side surface is a convex surface or a flat surface, and has a positive refractive power, and the object-side surface is A first lens having a concave meniscus shape having a negative refractive power and a third lens having a convex surface and a positive refractive power, the first lens, An imaging lens, wherein each of the second lens and the third lens has an aspheric surface on at least one surface and satisfies the following conditions.
(1) 1.00 <f / f ₁ <1.50
(2) 1.40 <f / | f ₂ | <1.95
(3) 1.00 <f / f ₃ <1.85
(4) 0.65 <f ₁ / f ₃ <1.60
However,
f: Composite focal length of the entire imaging lens f ₁ : Focal length of the first lens f ₂ : Focal length of the second lens f ₃ : Focal length of the third lens The imaging lens according to claim 1, wherein the following condition is satisfied.
(5) | r ₁ / r ₂ | <0.55
(6) 1.90 <f / | r ₄ | <3.20
(7) f / | r ₆ | <0.65
However,
r ₁ : radius of curvature of the object side surface of the first lens r ₂ : radius of curvature of the image side surface of the first lens r ₄ : radius of curvature of the image side surface of the second lens r ₆ : image of the third lens Radius of curvature of side face The imaging lens according to claim 1, wherein the following condition is satisfied.
(8) 25 <ν ₁ −ν ₂
However,
ν ₁ : Abbe number of the first lens ν ₂ : Abbe number of the second lens The imaging lens according to claim 1, wherein the following condition is satisfied.
(9) L / 2H <1.1
(10) b _f /2H>0.5
(11) D _max /2H<0.70
(12) 0 <( _{HD max} / 2) / b _f <0.43
However,
L: Total optical length of the entire imaging lens system 2H: Effective screen diagonal length b _f : Back focus D _max : Maximum value among effective optical diameters of all lens surfaces The imaging lens according to claim 1, wherein the first lens and the third lens are made of a glass material. The imaging lens according to claim 1, wherein the first lens to the third lens are made of a glass material. The imaging lens according to claim 1, wherein the image-side surface of the third lens is a spherical surface or a flat surface.

Images