JP2011017764A - Imaging lens, imaging apparatus and portable terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging lens that copes with a minute pixel pitch of an imaging device, and ensures a back focus capable of maintaining thickness of a cover glass even when achieving a shorter focal length and a wider angle and ensure high optical performance, and is suitable for mass production at low cost, and to provide an imaging apparatus and a portable terminal.SOLUTION: The imaging lens LN includes two blocks including first and second blocks C1 and C2 in order from an object side as an optical element having power, and an optical stop ST exists on an image side of the first block C1. An optical surface of the first block C1 nearest to the object side has shape nearly convex to the object side, and an optical surface of the second block C2 nearest to an image surface side has shape nearly convex to the image surface side.

Description

  The present invention relates to an imaging lens, an imaging device, and a portable terminal. More specifically, an imaging device that captures an image of a subject with an imaging device (for example, a solid-state imaging device such as a CCD (Charge Coupled Device) type image sensor, a CMOS (Complementary Metal-Oxide Semiconductor) type image sensor), and the like are mounted. The present invention relates to a portable terminal and an imaging lens that includes a wafer level lens suitable for mass production, for example, and forms an optical image on a light receiving surface of an imaging element.

  Compact and thin imaging devices are now mounted on portable terminals (for example, mobile phones and PDAs (Personal Digital Assistants), etc.) that are compact and thin electronic devices. This enables mutual information transmission with remote locations. Is possible not only for audio information but also for image information. As an image pickup device used in the image pickup apparatus, a solid-state image pickup device such as a CCD image sensor or a CMOS image sensor is used.

  2. Description of the Related Art In recent years, an imaging device having a small pixel pitch has been adopted in an imaging device having a wide angle of view mounted on a portable terminal for the purpose of miniaturization. The trend is increasingly accelerating. Patent Documents 1 to 4 propose imaging lenses used in such an imaging apparatus. These are all wide-angle imaging lenses from the standard, and are composed of wafer-level lenses aimed at mass production.

JP 2006-323365 A Japanese Patent No. 3929479 Japanese Patent No. 3976781 JP 2008-233984 A

  If only the pixel pitch is reduced with the size of the image sensor and the same number of pixels, it is necessary to shorten the focal length in order to perform photographing with the same angle of view. Further, in order to capture a wider range, it is necessary to further widen the angle. When the focal length is shortened, the back focus is naturally shortened. However, it is difficult to make the cover glass thinner than a certain thickness in consideration of strength, workability, cost, and the like. Further, the thickness of the cover glass is not proportional to the shortening of the focal length, and the thickness is required as it is. Therefore, if the thickness of the cover glass is maintained, the necessary back focus cannot be ensured. Therefore, it is difficult for an imaging lens as proposed in Patent Documents 1 to 4 to deal with a minute pixel pitch of the imaging element.

  Moreover, since the conventional imaging lenses proposed in Patent Documents 1 to 4 are slightly wider than the standard, when attempting to further widen the angle, in order to ensure the back focus and reduce the size, It becomes an asymmetrical configuration. If the lens type is asymmetric, it is difficult to correct various aberrations (for example, distortion aberration). As the angle of view increases, the imaging lens becomes more asymmetrical with respect to the stop, and it becomes difficult to ensure high performance.

  The present invention has been made in view of such a situation, and the object thereof is to support a minute pixel pitch of an image sensor, and to maintain the thickness of the cover glass even when the focal length is shortened and the angle is widened. An object of the present invention is to provide an imaging lens that can secure a back focus and high optical performance, and is suitable for mass production at a low cost, and an imaging apparatus and a portable terminal including the imaging lens.

  In order to achieve the above object, an imaging lens according to a first aspect of the present invention is an imaging lens having a two-block configuration including a first block and a second block in order from the object side as an optical element having power. The second block is composed of a lens substrate that is a parallel plate, and a lens portion that is formed on at least one of the object side surface and the image side surface and has a positive or negative power, and the lens substrate. The lens portion is made of a different material, an optical stop is present on the image side of the first block, the optical surface closest to the object side of the first block has a generally convex shape on the object side, and the second block The optical surface closest to the image plane of the block has a substantially convex shape on the image plane side.

The imaging lens of the second invention is characterized in that, in the first invention, the following conditional expressions (1) and (2) are satisfied.
0 <S (s1F-st) / r_1F <3.0 (1)
0 <S (s2R-st) / r_2R <3.0 (2)
However,
S (s1F-st): Air conversion distance from the optical surface closest to the object side of the first block to the stop,
S (s2R-st): Air equivalent distance from the optical surface closest to the image plane of the second block to the stop,
r_1F: Paraxial radius of curvature of the optical surface closest to the object in the first block,
r_2R: Paraxial radius of curvature of the optical surface closest to the image plane of the second block,
It is.

An imaging lens of a third invention is characterized in that, in the first or second invention, the following conditional expressions (3) and (4) are satisfied.
0 <{2 × S (s1F-st)} / {f_s1F (0.6) + f_s1F (0.8)} <3 (3)
0 <{2 × S (s2R-st)} / {f_s2R (0.6) + f_s2R (0.8)} <3… (4)
However,
S (s1F-st): Air conversion distance from the optical surface closest to the object side of the first block to the stop,
S (s2R-st): Air equivalent distance from the optical surface closest to the image plane of the second block to the stop,
f_s1F (0.6): Sagittal focal length on the most object-side optical surface of the first block for the chief ray of 60% of the maximum image height,
f_s1F (0.8): Sagittal focal length on the most object-side optical surface of the first block with respect to the principal ray with an image height of 80% of the maximum image height,
f_s2R (0.6): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 60% of the maximum image height,
f_s2R (0.8): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 80% of the maximum image height,
It is.

  According to a fourth aspect of the present invention, there is provided the imaging lens according to any one of the first to third aspects, wherein the optical aperture is located on a plane portion of a lens substrate of the second block.

The imaging lens of a fifth invention is characterized in that, in any one of the first to fourth inventions, the following conditional expression (5) is satisfied.
0.05 <{f_s2R (0.6) + f_s2R (0.8)} / {f_s1F (0.6) + f_s1F (0.8)} <3.0… (5)
However,
f_s1F (0.6): Sagittal focal length on the most object-side optical surface of the first block for the chief ray of 60% of the maximum image height,
f_s1F (0.8): Sagittal focal length on the most object-side optical surface of the first block with respect to the principal ray with an image height of 80% of the maximum image height,
f_s2R (0.6): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 60% of the maximum image height,
f_s2R (0.8): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 80% of the maximum image height,
It is.

In the imaging lens of a sixth invention according to any one of the first to fifth inventions, the optical surface closest to the image plane of the first block has negative power, and the following conditional expression (6) It is characterized by satisfying.
-5.0 <φ_s1R / φ_all <-0.01… (6)
However,
φ_s1R: power of the optical surface closest to the image plane of the first block,
φ_all: Power of the whole system,
It is.

The imaging lens of a seventh invention is characterized in that, in any one of the first to sixth inventions, the first block has a negative power as a whole and satisfies the following conditional expression (7): And
-2 <φ_s1_all / φ_all <0 (7)
However,
φ_s1_all: Power of the first block,
φ_all: Power of the whole system,
It is.

  An imaging lens according to an eighth aspect of the present invention is an imaging lens having a two-block configuration including, as an optical element having power, a first block and a second block in order from the object side, wherein the first block is formed from a substantially homogeneous medium. A lens substrate that is a parallel plate, and a lens unit that is formed on at least one of the object side surface and the image side surface and has positive or negative power. The lens substrate and the lens portion are made of different materials, and there is an optical stop on the image side of the first block, and the optical surface closest to the object side of the first block is substantially on the object side. It has a convex shape, and the optical surface closest to the image plane of the second block has a generally convex shape on the image plane side.

  The imaging lens of a ninth invention is characterized in that, in the eighth invention, the one lens made of the substantially homogeneous medium is a glass lens or a glass mold lens.

  The imaging lens of a tenth invention is characterized in that, in the eighth invention, the one lens made of the substantially homogeneous medium is a plastic lens.

The imaging lens of an eleventh aspect of the invention is characterized in that, in any one of the eighth to tenth aspects of the invention, the following conditional expressions (1) and (2) are satisfied.
0 <S (s1F-st) / r_1F <3.0 (1)
0 <S (s2R-st) / r_2R <3.0 (2)
However,
S (s1F-st): Air conversion distance from the optical surface closest to the object side of the first block to the stop,
S (s2R-st): Air equivalent distance from the optical surface closest to the image plane of the second block to the stop,
r_1F: Paraxial radius of curvature of the optical surface closest to the object in the first block,
r_2R: Paraxial radius of curvature of the optical surface closest to the image plane of the second block,
It is.

The imaging lens of a twelfth aspect of the invention is characterized in that, in any one of the eighth to eleventh aspects of the invention, the following conditional expressions (3) and (4) are satisfied.
0 <{2 × S (s1F-st)} / {f_s1F (0.6) + f_s1F (0.8)} <3 (3)
0 <{2 × S (s2R-st)} / {f_s2R (0.6) + f_s2R (0.8)} <3… (4)
However,
S (s1F-st): Air conversion distance from the optical surface closest to the object side of the first block to the stop,
S (s2R-st): Air equivalent distance from the optical surface closest to the image plane of the second block to the stop,
f_s1F (0.6): Sagittal focal length on the most object-side optical surface of the first block for the chief ray of 60% of the maximum image height,
f_s1F (0.8): Sagittal focal length on the most object-side optical surface of the first block with respect to the principal ray with an image height of 80% of the maximum image height,
f_s2R (0.6): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 60% of the maximum image height,
f_s2R (0.8): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 80% of the maximum image height,
It is.

  The imaging lens of a thirteenth invention is characterized in that, in any one of the eighth to twelfth inventions, the optical diaphragm is located on a plane portion of the lens substrate of the second block.

The imaging lens of the fourteenth invention is characterized in that, in any one of the eighth to thirteenth inventions, the following conditional expression (5) is satisfied.
0.05 <{f_s2R (0.6) + f_s2R (0.8)} / {f_s1F (0.6) + f_s1F (0.8)} <3.0… (5)
However,
f_s1F (0.6): Sagittal focal length on the most object-side optical surface of the first block for the chief ray of 60% of the maximum image height,
f_s1F (0.8): Sagittal focal length on the most object-side optical surface of the first block with respect to the principal ray with an image height of 80% of the maximum image height,
f_s2R (0.6): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 60% of the maximum image height,
f_s2R (0.8): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 80% of the maximum image height,
It is.

The imaging lens of the fifteenth aspect of the present invention is the imaging lens according to any one of the eighth to fourteenth aspects, wherein the optical surface closest to the image plane of the first block has a negative power. It is characterized by satisfying.
-5.0 <φ_s1R / φ_all <-0.01… (6)
However,
φ_s1R: power of the optical surface closest to the image plane of the first block,
φ_all: Power of the whole system,
It is.

The imaging lens of a sixteenth aspect of the invention is characterized in that, in any one of the eighth to fifteenth aspects, the first block has a negative power as a whole and satisfies the following conditional expression (7): And
-2 <φ_s1_all / φ_all <0 (7)
However,
φ_s1_all: Power of the first block,
φ_all: Power of the whole system,
It is.

  The image pickup lens of a seventeenth invention is characterized in that, in any one of the first to sixteenth inventions, the lens substrate is made of a glass material.

  The imaging lens of an eighteenth invention is characterized in that, in any one of the first to seventeenth inventions, the lens portion is made of a resin material.

  The imaging lens of a nineteenth invention is characterized in that, in the eighteenth invention, the resin material is an energy curable resin material.

  An image pickup lens of a twentieth invention is characterized in that, in the eighteenth or nineteenth invention, inorganic resin particles of 30 nanometers or less are dispersed in the resin material.

  The imaging lens of a twenty-first aspect of the invention is any one of the first to twentieth aspects of the invention, a step of sealing the lens substrates or the first and second blocks through a lattice-shaped spacer member; The block is manufactured by a manufacturing method including a step of cutting the integrated lens substrate and the spacer member with a lattice frame of the spacer member.

  An imaging device according to a twenty-second aspect includes the imaging lens according to any one of the first to twenty-first aspects, and an imaging element that converts an optical image formed on the light receiving surface into an electrical signal. The imaging lens is provided so that an optical image of a subject is formed on a light receiving surface of the imaging element.

  A portable terminal according to a twenty-third aspect includes the imaging device according to the twenty-second aspect.

  When the imaging lens system is widened, the power of the first block tends to be negative in order to secure the back focus, and the asymmetry becomes strong. On the other hand, the optical surface closest to the object side has a convex shape toward the object side, the optical surface closest to the image surface has a convex shape toward the image surface side, and an optical aperture is formed on the image surface from the first block. By disposing the lens on the side, the imaging lens can be as close to a symmetric system as possible to ensure high optical performance.

  Therefore, according to the present invention, it is possible to cope with a minute pixel pitch of the image pickup device, and it is possible to ensure a back focus that can be realized even when the focal length is shortened and the angle of view is widened, and to ensure high optical performance. It is possible to realize an imaging lens that can ensure performance and is suitable for mass production at low cost, and an imaging device and a portable terminal including the imaging lens. For example, by adopting a wafer level lens that can be mass-produced, for example, it is possible to achieve cost reduction and secure back focus, high performance, and compactness.

The optical block diagram of 1st Embodiment (Example 1). The optical block diagram of 2nd Embodiment (Example 2). The optical block diagram of 3rd Embodiment (Example 3). The optical block diagram of 4th Embodiment (Example 4). The optical block diagram of 5th Embodiment (Example 5). The optical block diagram of 6th Embodiment (Example 6). The optical block diagram of 7th Embodiment (Example 7). The optical block diagram of 8th Embodiment (Example 8). The optical block diagram of 9th Embodiment (Example 9). The optical block diagram of 10th Embodiment (Example 10). FIG. 6 is an aberration diagram of Example 1. FIG. 6 is an aberration diagram of Example 2. FIG. 6 is an aberration diagram of Example 3. FIG. 6 is an aberration diagram of Example 4. FIG. 6 is an aberration diagram of Example 5. FIG. 10 is an aberration diagram of Example 6. FIG. 10 is an aberration diagram of Example 7. FIG. 10 is an aberration diagram of Example 8. FIG. 10 is an aberration diagram of Example 9. FIG. 10 is an aberration diagram of Example 10. The figure which shows the example of schematic structure of the portable terminal carrying an imaging device in a typical cross section. FIG. 6 is a schematic cross-sectional view illustrating an example of a manufacturing process of an imaging lens.

  Hereinafter, an imaging lens, an imaging device, a portable terminal, and the like according to the present invention will be described. The imaging lens according to the present invention has a two-block configuration including a first block and a second block in order from the object side as an optical element having power. Among the first and second blocks, at least the second block includes a lens substrate that is a parallel plate, and a lens unit that is formed on at least one of the object side surface and the image side surface and has positive or negative power. It is configured. The lens substrate and the lens portion assumed here are different in material, but if the material of the lens substrate and the lens portion is the same, it is equivalent to one lens made of a substantially homogeneous medium. Therefore, the imaging lens according to the present invention includes a type 1 in which the first and second blocks are each composed of the lens substrate and the lens portion, and a single lens in which the first block is made of a substantially homogeneous medium. , And the second block is divided into type 2 composed of the lens substrate and the lens portion.

  The type 1 imaging lens includes a lens substrate in which the first and second blocks are parallel plates, and a lens unit that is formed on at least one of the object side surface and the image side surface and has positive or negative power. Each lens board and lens part are made of different materials. There is an optical stop on the image side of the first block, and the most object-side optical surface of the first block has a generally convex shape on the object side. In addition, the optical surface closest to the image plane of the second block has a generally convex shape on the image plane side.

  In the type 2 imaging lens, the first block is composed of a single lens made of a substantially homogeneous medium, and the second block is a lens substrate that is a parallel plate, of the object side surface and the image side surface. The lens unit is formed on at least one side and has a positive or negative power. The lens substrate and the lens unit are made of different materials, and there is an optical stop on the image side from the first block. The optical surface closest to the object side has a substantially convex shape toward the object side, and the optical surface closest to the image surface side of the second block has a generally convex shape toward the image surface side.

  By the way, cost reduction is strongly demanded for an imaging apparatus, a portable terminal, and the like provided with an imaging lens like the optical system according to the present invention. As a configuration with the lowest cost, an optical system composed of one block can be considered. Even in such a case, as in the optical system according to the present invention, it is possible to form optical surfaces with lens portions on both sides of a lens substrate that is a parallel plate, and it is possible to change the material of both lens portions. . It is also possible to make the material of the lens substrate different from the material of the lens portion forming the optical surface. Therefore, there is a possibility that chromatic aberration can be corrected by the difference in the material. However, since there are only two optical surfaces, it is difficult to perform on-axis and off-axis color correction, image plane Petzval correction, and coma aberration correction, and it is difficult to use two surfaces. Can not. On the other hand, an aberration correction capability is high in an optical system having three or more blocks. However, in addition to the processing cost of the three blocks, a considerable cost is required to assemble them in a predetermined position (particularly so that the eccentricity is reduced), and the manufacturing cost is too high. Therefore, it is not suitable for mass production at low cost.

  For the above reasons, it is optimal to configure with two blocks to satisfy the requirements of high performance and low cost. In the case of two blocks, there are four optical surfaces and two parallel flat plates. Therefore, two surfaces can be positive power and two surfaces can be negative power, or three surfaces can be positive power and one surface can be negative power. According to this configuration, not only chromatic aberration correction but also other aberration corrections can be sufficiently corrected, and high optical performance can be ensured. In addition, the two-block configuration is advantageous in terms of cost because the processing and assembly can be performed at low cost.

  In recent years, the pixel pitch of the image sensor has been reduced, and the pixel size has been reduced regardless of the higher density. If the pixel size is reduced and the image sensor size is reduced, it is necessary to shorten the focal length in order to maintain the same angle of view specification. Also, as one of the product lineup, an optical system that captures a wider angle of view is desired, and from this point of view, a wider angle is desired. Normally, when the focal length is shortened, the back focus is shortened accordingly. However, it is difficult to make the thickness of the cover glass or the like that protects the image sensor thinner than a certain thickness from the viewpoint of strength and cost. Therefore, it is necessary to ensure a certain amount of back focus even if the focal length is shortened. In order to secure the back focus by the optical system, for example, a retrofocus optical system preceded by negative power is advantageous. In the retrofocus optical system, negative and positive power are arranged from the object side.

  Moreover, in an imaging apparatus or a portable terminal equipped with an imaging lens such as the optical system according to the present invention, it is necessary to further reduce the size of the imaging lens. In order to reduce the size of the imaging lens, it is advantageous to dispose the stop closer to the object side in the optical system. If the optical aperture is located closer to the object side, for example, the size in the radial direction can be made considerably small. However, if the optical diaphragm is located closer to the object side in the optical system and a power arrangement such as retrofocus is adopted, the optical system becomes a very asymmetric arrangement, making it difficult to ensure optical performance. . Sometimes, the asymmetric arrangement of the optical system makes it difficult to correct symmetric aberrations (distortion aberration, lateral chromatic aberration, etc.), and as a result, it is difficult to widen the optical system.

  In order to solve the above problems, in the present invention, as in each type of imaging lens, there is an optical stop on the image side from the first block, and the optical surface on the most object side of the first block is generally convex on the object side. (For example, a substantially convex shape), and the optical surface closest to the image plane of the second block has a generally convex shape (for example, a substantially convex shape) on the image plane side. With this configuration, the symmetry of the optical system can be ensured as much as possible, so that high optical performance can be ensured as described below.

  If the optical aperture is arranged on the image side of the first block, and the optical surface closest to the object side of the first block has a convex shape toward the object side, the optical surface becomes a concentric shape with respect to the aperture. Therefore, off-axis rays can enter the optical system without causing large aberrations on this surface. Due to the action of this surface, the occurrence of distortion is reduced, and the occurrence of astigmatism can also be reduced. Therefore, it is possible to further reduce the performance degradation due to distortion and astigmatism in the entire system. Further, when the optical surface closest to the image surface of the second block is formed to be substantially convex toward the image surface, the optical surface becomes a substantially concentric surface with respect to the stop. Thereby, the occurrence of distortion on this surface is reduced, and the occurrence of astigmatism can also be reduced. In addition, since the two optical surfaces have a certain degree of symmetry with respect to the diaphragm, distortion, lateral chromatic aberration, coma, and the like caused by the two are canceled out to a smaller value, so that high performance optical The system can be secured.

  Here, the generally convex shape of the first and second blocks will be described. For example, consider the case of an optical surface in which air is positioned on the object side and a medium is positioned on the image plane side, such as the optical surface closest to the object side of the first block. If the optical surface is spherical and has a convex shape on the object side, the optical surface has positive power (positive focal length). At this time, the radius of curvature is a positive value. If the optical surface is aspherical, it may be a convex shape on the object side, but it may be a paraxial shape, or it may be a convex shape on the object side by looking at the overall shape. is there. Therefore, the above-described generally convex shape refers to the case described below. The same can be applied to an optical surface in which a medium is positioned on the object side and air is positioned on the image plane side, such as the optical surface closest to the image plane of the second block.

  When the paraxial surface shape is convex and the sag amount of the surface from the center toward the effective diameter increases positively, this surface is clearly convex on the object side. At this time, the paraxial radius of curvature is a positive value, and the shape of the surface is also clearly convex. Also, the paraxial part is a flat surface or concave on the object side, and the sign of the sag changes to a positive part at a small part in the effective diameter direction from the optical axis, and the sag increases beyond the original surface vertex. However, it can be said that a shape whose surface is directed toward the effective diameter in the direction of the image surface is generally convex. In addition, the paraxial shape is convex toward the object side, and is slightly concave toward the object side when it is slightly in the direction of the effective diameter. If is strong, this also has a generally convex shape. Since the convex shape has a positive focal length (power is positive), the generally convex shape means a case where the focal length is almost positive (power is almost positive) over the entire surface. Strictly speaking, the term “substantially convex” in the present invention can be considered as a case where more than half of the surface has a positive power in the sectional view of the surface.

  In each type of imaging lens, as described above, an optical aperture is present on the image side from the first block, the most object-side optical surface of the first block has a generally convex shape on the object side, and the second block The optical surface closest to the image surface of the image surface has a generally convex shape on the image surface side, so that it is possible to cope with the minute pixel pitch of the image sensor. It is possible to secure a feasible back focus that can maintain the thickness and secure high optical performance, and to realize an imaging lens suitable for mass production at low cost and an imaging apparatus equipped with the imaging lens. It is. In addition, by adopting the above configuration in an imaging lens composed of a wafer level lens that can be mass-produced, it is possible to achieve cost reduction, secure back focus, increase performance, and achieve compactness. And if an imaging device provided with the imaging lens is used for a digital device such as a portable terminal, it can contribute to higher performance, higher functionality, compactness, lower cost, and the like. In each type of imaging lens according to the present invention, conditions for obtaining the above effects in a well-balanced manner and achieving higher optical performance, improved manufacturability, and the like will be described below.

It is desirable to satisfy at least one of the following conditional expressions (1) and (2), and it is more desirable to satisfy both.
0 <S (s1F-st) / r_1F <3.0 (1)
0 <S (s2R-st) / r_2R <3.0 (2)
However,
S (s1F-st): Air conversion distance from the optical surface closest to the object side of the first block to the stop,
S (s2R-st): Air equivalent distance from the optical surface closest to the image plane of the second block to the stop,
r_1F: Paraxial radius of curvature of the optical surface closest to the object in the first block,
r_2R: Paraxial radius of curvature of the optical surface closest to the image plane of the second block,
It is.

  Conditional expression (1) defines the relative relationship between the paraxial radius of curvature of the optical surface closest to the object and the distance from the stop of this surface. The off-axis light beam enters the optical surface closest to the object side from the object side toward the stop (more precisely, the entrance pupil). At that time, if the optical surface closest to the object has a concentric shape with respect to the stop, off-axis rays can be incident on the optical surface without causing large aberrations. In particular, distortion and astigmatism can be suppressed and reduced. Conditional expression (1) gives the appropriate relationship. If the condition range of the conditional expression (1) is not met, distortion and astigmatism will occur greatly, making it difficult to ensure optical performance. If the optical surface becomes a negative power surface exceeding the lower limit of conditional expression (1), negative distortion will occur on this surface. For this reason, large negative distortion tends to occur in the entire optical system, and it becomes difficult to ensure optical performance.

  Conditional expression (2) defines the relative relationship between the paraxial radius of curvature of the optical surface closest to the image plane and the distance from the stop of this surface. The off-axis light beam exits from the optical surface closest to the image plane from the stop (exactly, the exit pupil) toward the image plane. At that time, if the optical surface closest to the image plane has a concentric shape with respect to the stop, the off-axis light beam exits from the optical surface without causing large aberration and travels toward the image plane. . In particular, distortion and astigmatism can be suppressed and reduced. Conditional expression (2) gives the appropriate relationship. If the condition range of the conditional expression (2) is not met, distortion and astigmatism will occur greatly, making it difficult to ensure optical performance. Further, if the optical surface becomes a negative power surface exceeding the lower limit of the conditional expression (2), it becomes difficult to ensure telecentricity.

It is more desirable to satisfy the following conditional expression (1a).
0 <S (s1F-st) / r_1F <1.5 (1a)
The conditional expression (1a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (1). Therefore, the above effect can be further increased preferably by satisfying conditional expression (1a).

It is more desirable to satisfy the following conditional expression (2a).
0 <S (s2R-st) / r_2R <1.0 (2a)
The conditional expression (2a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (2). Therefore, the above effect can be further enhanced preferably by satisfying conditional expression (2a).

It is desirable to satisfy at least one of the following conditional expressions (3) and (4), and it is more desirable to satisfy both.
0 <{2 × S (s1F-st)} / {f_s1F (0.6) + f_s1F (0.8)} <3 (3)
0 <{2 × S (s2R-st)} / {f_s2R (0.6) + f_s2R (0.8)} <3… (4)
However,
S (s1F-st): Air conversion distance from the optical surface closest to the object side of the first block to the stop,
S (s2R-st): Air equivalent distance from the optical surface closest to the image plane of the second block to the stop,
f_s1F (0.6): Sagittal focal length on the most object-side optical surface of the first block for the chief ray of 60% of the maximum image height,
f_s1F (0.8): Sagittal focal length on the most object-side optical surface of the first block with respect to the principal ray with an image height of 80% of the maximum image height,
f_s2R (0.6): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 60% of the maximum image height,
f_s2R (0.8): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 80% of the maximum image height,
It is.

  Conditional expressions (3) and (4) are expressed as follows: the power in each middle band of the optical surface closest to the object side and the optical surface closest to the image plane (power is defined by the reciprocal of the focal length) and the aperture position. It defines the relationship. If the optical system is a wide-angle optical system and an asymmetric optical system, it is particularly difficult to correct off-axis performance. Therefore, it is more desirable to appropriately set the relationship between the focal length on the optical surface of the chief rays of 60% and 80% of the maximum image height and the aperture position. The power of the surface with respect to the off-axis ray is the position where the principal ray intersects the surface, the local curvature of the surface, the angle of incidence of the principal ray on the surface, the refractive index before and after the surface, Can be calculated more.

  Conditional expression (3) is the average focal length of the most object-side optical surface with respect to chief rays of 60% and 80% of the maximum image height, the relative position of the stop and the most object-side optical surface, The relationship is defined. When the focal length (power) of this optical surface is appropriate, the occurrence of distortion and astigmatism on this optical surface can be suppressed and reduced. If the condition range of the conditional expression (3) is not met, distortion and astigmatism will increase and it will be difficult to ensure high performance. In particular, if this optical surface becomes a negative power surface beyond the lower limit of conditional expression (3), negative distortion will occur on this surface. For this reason, large negative distortion tends to occur in the entire optical system, and it becomes difficult to ensure optical performance.

  Conditional expression (4) indicates the average focal length of the optical surface closest to the image plane with respect to the principal rays having the maximum image height of 60% and 80%, and the relative position between the stop and the optical surface closest to the object. Stipulates the relationship. When the focal length (power) of this optical surface is appropriate, the occurrence of distortion and astigmatism on this optical surface can be suppressed and reduced. If the condition range of the conditional expression (4) is not met, distortion and astigmatism will increase and it will be difficult to ensure high performance. Also, if the optical surface becomes a negative power surface beyond the lower limit of conditional expression (4), it becomes difficult to ensure telecentricity.

It is more desirable to satisfy the following conditional expression (3a).
0 <{2 × S (s1F-st)} / {f_s1F (0.6) + f_s1F (0.8)} <1… (3a)
The conditional expression (3a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (3). Therefore, the above effect can be further enhanced preferably by satisfying conditional expression (3a).

It is more desirable to satisfy the following conditional expression (4a).
0.1 <{2 × S (s2R-st)} / {f_s2R (0.6) + f_s2R (0.8)} <0.5… (4a)
This conditional expression (4a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (4). Therefore, the above effect can be further enhanced preferably by satisfying conditional expression (4a).

  It is desirable that the optical diaphragm be located on the plane portion of the lens substrate (parallel plate) of the second block. A wafer level lens is formed by simultaneously replicating a large number of lens elements on a glass substrate of several inches that is a parallel plate by a replica method, and after combining a glass substrate (lens wafer) on which a large number of these lens elements are formed with a sensor wafer, It is a lens manufactured by separating. Therefore, if wafer level lenses are used, lens modules can be mass-produced. Since the glass substrate serving as the lens substrate is a parallel plate, it is easy to form a stop. For example, prepare a plate-like or sheet-like part that only penetrates the aperture-shaped light beam so that it matches the position of the lens element in advance, place it on a parallel plate, and place the lens element on it. By forming and separating, a large number of apertures can be formed at one time. Moreover, it is possible to form a large number of apertures at a lower cost by printing the shape of the aperture, etching, or painting on the parallel plate itself. A large number of apertures can be formed at one time because the substrate is a parallel plate and can be achieved by using a wafer level lens. Therefore, the cost can be significantly reduced by forming the aperture on the parallel plate of the second block.

It is desirable to satisfy the following conditional expression (5).
0.05 <{f_s2R (0.6) + f_s2R (0.8)} / {f_s1F (0.6) + f_s1F (0.8)} <3.0… (5)
However,
f_s1F (0.6): Sagittal focal length on the most object-side optical surface of the first block for the chief ray of 60% of the maximum image height,
f_s1F (0.8): Sagittal focal length on the most object-side optical surface of the first block with respect to the principal ray with an image height of 80% of the maximum image height,
f_s2R (0.6): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 60% of the maximum image height,
f_s2R (0.8): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 80% of the maximum image height,
It is.

  Conditional expression (5) appropriately defines the relationship between the focal length of the optical surface closest to the object side and the focal length of the optical surface closest to the image plane. In particular, the focal length is the focal length of the chief ray at the image height at 60% and 80% of the maximum image height, and defines the average relationship. That is, this defines the symmetry between the most object-side optical surface and the most image-side optical surface. When the value corresponding to this conditional expression (5) is 1, the average of the power (in other words, the focal length) is equal and is completely symmetric. However, there are conditions such as how light rays pass, the positional relationship with the stop, and the relationship with other optical surfaces, and considering the actual practical performance, the range of conditional expression (5) is an appropriate range. The lower limit side boundary value of the conditional expression (5) is a small value because the distance between the optical surface closest to the image plane and the image plane is short, and it is desirable to have stronger power.

  If the condition range of the conditional expression (5) is not satisfied, the aberrations generated on each optical surface cannot be canceled out, and distortion and astigmatism increase, making it difficult to ensure optical performance. For example, when the upper limit of the conditional expression (5) is exceeded and the focal length of the optical surface on the object side of the first block becomes too smaller than the focal length of the optical surface on the image plane side of the second block (that is, the first block If the power on the object side of the block becomes too strong), the positive distortion will be too great. If the lower limit of conditional expression (5) is exceeded and the focal length of the optical surface on the image plane side of the second block becomes too small compared to the focal length of the optical surface on the object side of the first block (that is, the second block). If the power on the image side of the block becomes too strong), the negative distortion will be too great.

It is more desirable to satisfy the following conditional expression (5a).
0.05 <{f_s2R (0.6) + f_s2R (0.8)} / {f_s1F (0.6) + f_s1F (0.8)} <1.5… (5a)
This conditional expression (5a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (5). Therefore, the above effect can be further enhanced preferably by satisfying conditional expression (5a).

It is desirable that the optical surface closest to the image plane of the first block has a negative power and satisfies the following conditional expression (6).
-5.0 <φ_s1R / φ_all <-0.01… (6)
However,
φ_s1R: power of the optical surface closest to the image plane of the first block,
φ_all: Power of the whole system,
It is.

  In order to secure the necessary back focus while shortening the focal length, it is desirable to arrange negative power as much as possible on the object side so that the optical system has a retrofocus configuration. For that purpose, it is desirable that the object side surface of the first block has a negative power. However, in order to ensure the symmetry of the optical system, the optical surface closest to the object side is a surface convex to the object side (that is, a positive power). Therefore, it is desirable to give negative power to the image side surface of the first block. When the image side surface of the first block has negative power, the surface shape is concave on the image surface side. In the case of the surface shape, when an off-axis light beam having a large angle of view is incident, the declination angle can be reduced with respect to the light beam, so that the occurrence of coma and distortion can be suppressed and reduced. Therefore, it is desirable that the image side surface of the first block has negative power in order to ensure optical performance.

  However, if the negative power on the image side surface of the first block is too strong, the curvature of the concave surface becomes strong and the lower side flare of lateral aberration increases in the periphery. Further, when the negative power is weak, it is difficult to ensure the back focus. From this point of view, conditional expression (6) defines the power of the image side surface of the first block. By satisfying conditional expression (6), it is possible to realize an optical system with good performance while ensuring back focus. If the power is too weak beyond the upper limit of conditional expression (6), it will be difficult to secure the back focus. Moreover, since Petzval becomes negative in terms of negative power, it is possible to correct by reducing the positive Petzval of other positive lenses. If the negative power of this surface becomes too small, correction of Petzval becomes insufficient, making it difficult to correct the image surface. Further, if the negative power becomes too strong beyond the lower limit of conditional expression (6), peripheral lateral aberrations deteriorate and it is difficult to ensure high performance.

It is more desirable to satisfy the following conditional expression (6a).
-2.5 <φ_s1R / φ_all <-0.01 (6a)
The conditional expression (6a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (6). Therefore, the above effect can be further increased preferably by satisfying conditional expression (6a).

In the case of a type 2 imaging lens, it is more desirable to satisfy the following conditional expression (6b) for the image side surface of one lens made of a substantially homogeneous medium constituting the first block.
-3.5 <φ_s1R / φ_all <-0.01… (6b)
This conditional expression (6b) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (6). Therefore, the above effect can be further increased preferably by satisfying conditional expression (6b).

It is desirable that the first block has a negative power as a whole and satisfies the following conditional expression (7).
-2 <φ_s1_all / φ_all <0 (7)
However,
φ_s1_all: Power of the first block,
φ_all: Power of the whole system,
It is.

  In order to secure the necessary back focus while shortening the focal length, it is desirable to arrange negative power as much as possible on the object side so that the optical system has a retrofocus configuration. Therefore, it is desirable that the first block has negative power. In order to secure the back focus as much as possible, it is sufficient that the negative power is strong. However, it is difficult to ensure the performance even if it is strongly increased. In particular, since the negative power is closest to the object side, if the negative power is strong, a large negative distortion occurs and a large chromatic aberration of magnification also occurs. In order to secure the back focus while maintaining high performance, it is necessary to appropriately set the power of the negative lens. The appropriate range is defined by conditional expression (7). If it falls within the condition range of conditional expression (7), it is possible to realize a high-performance optical system with small distortion and lateral chromatic aberration while appropriately securing the back focus. When the power of the first block is increased beyond the lower limit of conditional expression (7), aberrations (especially distortion and lateral chromatic aberration) are greatly generated and it is difficult to achieve high performance. If the power exceeds the upper limit of conditional expression (7) and the power becomes positive, the retrofocus configuration cannot be maintained, and it becomes difficult to secure the back focus.

It is more desirable to satisfy the following conditional expression (7a).
-1 <φ_s1_all / φ_all <0 (7a)
The conditional expression (7a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (7). Therefore, the above effect can be further enhanced preferably by satisfying conditional expression (7a).

  When the optical system is to be configured at a lower cost, it is desirable to configure the first block with a single lens made of a substantially homogeneous medium, like the type 2 imaging lens. In a block structure composed of a lens substrate that is a parallel plate and a lens unit that is formed on at least one of the object side surface and the image side surface and has positive or negative power, the lens unit is formed on the lens substrate. Therefore, the thickness is limited. In addition, there is a restriction that it is difficult to form a strong curvature. When a thick lens or a surface with a strong curvature is required to ensure a predetermined performance or the like, the block structure alone may not ensure sufficient performance. In such a case, if the first block is composed of a single lens made of a substantially homogeneous medium, it is possible to secure good optical performance and further reduce the cost.

  In the type 2 imaging lens, it is preferable that the one lens made of the substantially homogeneous medium is a glass lens or a glass mold lens. For example, in the case of a type 2 imaging lens, if the first block is formed of a glass lens or a glass mold lens, the first block can have a higher refractive index and a wide dispersion value, which is advantageous for aberration correction. Become. The material constituting the block structure (for example, a wafer level lens) composed of the lens substrate and the lens portion is particularly limited to a glass mold having a high refractive index because both the refractive index and dispersion thereof are still narrow. This facilitates aberration correction. Further, since the dispersion is wide, it is possible to correct chromatic aberration that cannot be corrected by the dispersion of the optical material on the front and back surfaces of the second block.

  In the type 2 imaging lens, it is preferable that one lens made of the substantially homogeneous medium is a plastic lens. For example, in the case of a type 2 imaging lens, by configuring the first block with a plastic lens, the range of refractive index and dispersion is narrower than when configured with glass or a glass mold lens, but the cost is kept low. It becomes possible.

  The lens substrate is preferably made of a glass material. Since glass has a higher softening temperature than resin, if the lens substrate is made of glass, it does not easily change even if reflow treatment is performed, and the cost can be reduced. More preferably, the lens substrate is made of glass having a high softening temperature. When the material used for the lens substrate is glass, it is possible to reduce deterioration of optical characteristics (such as birefringence in the lens) due to distortion inside the lens, compared to resin.

  The lens part is preferably made of a resin material. As a material used for the lens portion, a resin material has better processability than a glass material and can be reduced in cost.

  The resin material is preferably an energy curable resin material. By configuring the lens portion with an energy curable resin material, it becomes possible to simultaneously cure and form a large number of lens portions with a mold on a wafer-like lens substrate. Therefore, mass productivity can be improved. The energy curable resin material here refers to a resin material that is cured by heat, a resin material that is cured by light, and the like, and various means for applying energy such as heat and light can be used for the curing.

  It is desirable to use a UV curable resin material as the energy curable resin material. If a UV curable resin material is used, mass productivity can be improved by shortening the curing time. In recent years, curable resin materials with excellent heat resistance have been developed. By using heat-resistant resins, camera modules that can withstand reflow processing can be used, and a more inexpensive camera module can be provided. Can do. The reflow process here refers to printing solder paste on a printed circuit board (circuit board), placing a component (camera module) on it, then applying heat to melt the solder, sensor external terminals and circuit board This is a process of automatic welding.

  It is desirable that inorganic fine particles of 30 nm or less are dispersed in the resin material. By dispersing inorganic fine particles of 30 nanometers or less in a lens portion made of a resin material, it is possible to reduce performance deterioration and image point position fluctuation even when the temperature changes. In addition, it is possible to obtain an imaging lens having excellent optical characteristics regardless of environmental changes without reducing the light transmittance. Generally, when fine particles are mixed in a transparent resin material, light scattering occurs and the transmittance decreases, so it is difficult to use as an optical material. However, the size of the fine particles is made smaller than the wavelength of the transmitted light beam. In this way, scattering can be substantially prevented from occurring.

  In addition, the resin material has a disadvantage that the refractive index is lower than that of the glass material, but it has been found that the refractive index can be increased by dispersing inorganic particles having a high refractive index in the resin material as a base material. Specifically, a material having an arbitrary temperature dependency is provided by dispersing inorganic particles of 30 nanometers or less, desirably 20 nanometers or less, and more desirably 15 nanometers or less in a resin material as a base material. can do.

Furthermore, the refractive index of the resin material decreases as the temperature rises. However, when inorganic particles whose refractive index increases as the temperature rises are dispersed in the resin material as the base material, these properties cancel each other out. It is also known that the refractive index change with respect to the temperature change can be reduced. On the other hand, it is also known that when the inorganic particles whose refractive index decreases as the temperature rises are dispersed in the resin material as the base material, the refractive index change with respect to the temperature change can be increased. Specifically, a material having an arbitrary temperature dependency is provided by dispersing inorganic particles of 30 nanometers or less, desirably 20 nanometers or less, and more desirably 15 nanometers or less in a resin material as a base material. can do. For example, by dispersing fine particles of aluminum oxide (Al ₂ O ₃ ) or lithium niobate (LiNbO ₃ ) in an acrylic resin, a resin material having a high refractive index can be obtained, and the refractive index change with respect to temperature can be reduced. Can do.

  Next, the change A due to the temperature of the refractive index will be described in detail. The change A due to the temperature of the refractive index is expressed by the following formula (FA) by differentiating the refractive index n by the temperature t based on the Lorentz-Lorentz formula.

…(FA)

… (FA)

However, in the formula (FA)
α: linear expansion coefficient,
[R]: molecular refraction,
It is.

In the case of a resin material, the contribution of the second term is generally small compared to the first term in the formula (FA) and can be almost ignored. For example, in the case of PMMA (polymethyl methacrylate) resin, the linear expansion coefficient α is 7 × 10 ⁻⁵ , and when it is substituted into the above formula (FA), dn / dt = −1.2 × 10 ⁻⁴ [/ ° C.] This is almost the same as the measured value.

Here, by dispersing fine particles, desirably inorganic fine particles, in the resin material, the contribution of the second term of the above formula (FA) is substantially increased, so as to cancel out the change due to the linear expansion of the first term. I am letting. Specifically, it is desirable to suppress the change of about −1.2 × 10 ^{−4 in the} past to an absolute value of less than 8 × 10 ⁻⁵ . In addition, the contribution of the second term can be further increased to have a temperature characteristic opposite to that of the resin material of the base material. That is, it is possible to obtain a material whose refractive index increases instead of decreasing the refractive index as the temperature increases. The mixing ratio can be appropriately increased or decreased in order to control the rate of change of the refractive index with respect to the temperature, and a plurality of types of nano-sized inorganic particles can be blended and dispersed.

  The imaging lens according to the present invention is suitable for use in a digital device with an image input function (for example, a portable terminal), and by combining this with an imaging device or the like, an image of a subject is optically captured and an electrical signal is obtained. Can be configured. An imaging device is an optical device that constitutes the main component of a camera used for still image shooting and moving image shooting of a subject.For example, an imaging lens that forms an optical image of an object in order from the object (i.e., subject) side, and its And an imaging device that converts an optical image formed by the imaging lens into an electrical signal. Then, an imaging lens having the above-described characteristic configuration is arranged so that an optical image of a subject is formed on the light receiving surface of the imaging element, and an imaging device having high performance at low cost and the same are provided. A digital device (for example, a portable terminal) can be realized.

  Examples of cameras include digital cameras, video cameras, surveillance cameras, in-vehicle cameras, videophone cameras, etc., and small and portable information such as personal computers and mobile terminals (for example, mobile phones and mobile computers). (Device terminal), peripheral devices (scanners, printers, etc.), cameras incorporated in or external to other digital devices, and the like. As can be seen from these examples, it is possible not only to configure a camera by using an imaging device, but also to add a camera function by mounting the imaging device on various devices. For example, a digital device with an image input function such as a mobile phone with a camera can be configured.

  FIG. 21 is a schematic cross-sectional view illustrating a schematic configuration example of a mobile terminal DU as an example of a digital device with an image input function. The imaging device LU mounted on the portable terminal DU shown in FIG. 21 is in parallel with an imaging lens LN (AX: optical axis) that forms an optical image (image plane) IM of the object in order from the object (namely, subject) side. It is formed on the light receiving surface SS by a flat plate PT (optical filters such as an optical low-pass filter and an infrared cut filter disposed as necessary; corresponding to a cover glass of the image sensor SR) and an image pickup lens LN. And an image sensor SR for converting the optical image IM into an electrical signal. When a mobile terminal DU having an image input function is configured by the imaging device LU, the imaging device LU is usually arranged inside the body. However, when realizing the camera function, a form as necessary is adopted. It is possible. For example, the unitized imaging device LU can be configured to be detachable or rotatable with respect to the main body of the portable terminal DU.

  As the image sensor SR, for example, a solid-state image sensor such as a CCD image sensor or a CMOS image sensor having a plurality of pixels is used. Since the imaging lens LN is provided so that an optical image IM of the subject is formed on the light receiving surface SS of the imaging element SR, the optical image IM formed by the imaging lens LN is electrically converted by the imaging element SR. Converted to a signal.

  The portable terminal DU includes a signal processing unit 1, a control unit 2, a memory 3, an operation unit 4, a display unit 5 and the like in addition to the imaging device LU. The signal generated by the image sensor SR is subjected to predetermined digital image processing, image compression processing, and the like in the signal processing unit 1 as necessary, and is recorded in the memory 3 (semiconductor memory, optical disk, etc.) as a digital video signal, In some cases, it is transmitted to other devices via a cable or converted into an infrared signal or the like (for example, a communication function of a mobile phone). The control unit 2 is composed of a microcomputer, and performs function control such as a photographing function and an image reproduction function; control of a lens moving mechanism for focusing and the like. For example, the control unit 2 controls the imaging device LU so as to perform at least one of still image shooting and moving image shooting of a subject. The display unit 5 includes a display such as a liquid crystal monitor, and displays an image using an image signal converted by the image sensor SR or image information recorded in the memory 3. The operation unit 4 includes operation members such as an operation button (for example, a release button) and an operation dial (for example, a shooting mode dial), and transmits information input by the operator to the control unit 2.

  As described above, the imaging lens LN includes two blocks (consisting of a first block C1 and a second block C2 in order from the object side), and forms an optical image IM on the light receiving surface SS of the imaging element SR. It has become. The optical image to be formed by the imaging lens LN is, for example, an optical low-pass filter (corresponding to the parallel plane plate PT in FIG. 21) having a predetermined cutoff frequency characteristic determined by the pixel pitch of the imaging element SR. By passing, the spatial frequency characteristic is adjusted so that so-called aliasing noise generated when converted into an electrical signal is minimized. Thereby, generation | occurrence | production of a color moire can be suppressed. However, if the performance around the resolution limit frequency is suppressed, there is no need to worry about the occurrence of noise without using an optical low-pass filter, and the display system where the noise is not very noticeable (for example, the liquid crystal of a mobile phone) When the user uses the screen or the like to perform shooting or viewing, it is not necessary to use an optical low-pass filter.

  The focusing of the imaging lens LN may be performed by moving the entire lens unit in the optical axis AX direction using an actuator, or may move a part of the lens in the optical axis AX direction. For example, if focusing is performed only in the first block C1, the actuator can be reduced in size. Further, the focus function may be realized by performing a process of increasing the depth of focus by software from the information recorded in the image sensor SR without focusing the lens by moving the lens in the optical axis direction. In that case, the actuator is not necessary, and the miniaturization and the cost reduction can be realized simultaneously.

  The imaging lens LN includes a step of sealing the lens substrates or the blocks with a lattice-shaped spacer member, and a step of cutting the integrated lens substrate and the spacer member with a lattice frame of the spacer member. The block is preferably manufactured by a manufacturing method including: For example, in the imaging lens LN in which all the lenses are formed of blocks, in a manufacturing method for manufacturing a plurality of imaging lenses LN that form the subject image IM or imaging devices LU including the imaging lens LN, the lens substrates are connected to each other via a lattice-like spacer member. Providing the sealing step and the step of cutting the integrated lens substrate and spacer member with the lattice frame of the spacer member enables easy production. Thereby, mass production of an inexpensive imaging lens becomes possible.

  As a manufacturing method for manufacturing a plurality of imaging lenses LN, for example, a reflow method or a replica method is used. In the reflow method, a low softening point glass film is formed by the CVD (Chemical Vapor Deposition) method, fine processing is performed by lithography and dry etching, and glass reflow is performed by heat treatment, so that a large number of lenses are simultaneously produced on the glass substrate. Is done. In the replica method, a large number of lenses are simultaneously manufactured by transferring a large amount of lens shapes on a lens wafer simultaneously with a mold using a curable resin. In any method, a large number of lenses can be manufactured at the same time, so that the cost can be reduced. For example, when different lenses manufactured by the above-described method (two lenses having different lens portions manufactured by separating the lens portions one by one on the lens substrate) are bonded to each other, the first The lens unit, the first parallel plate, the second parallel plate, and the second lens unit are arranged in this order.

  FIG. 22 is a schematic sectional view showing an example of the manufacturing process of the imaging lens LN (type 1). The first block C1 includes a first lens substrate L12 made of a parallel plate, a plurality of first object-side lens portions L11 bonded to one plane, and a plurality of first image-side lenses bonded to the other plane. Part L13. The first lens substrate L12 may be constituted by one parallel flat plate, or may be constituted by bonding two parallel flat plates as described above. The second block C2 includes a second lens substrate L22 made of a parallel plate, a plurality of second object side lens portions L21 bonded to one plane thereof, and a plurality of second image side lenses bonded to the other plane. Part L23. Similar to the first lens substrate L12, the second lens substrate L22 may be constituted by one parallel flat plate, or may be constituted by bonding two parallel flat plates as described above. Further, the object side surface or the image side surface of the second lens substrate L22 (for example, between the second lens substrate L22 and the second object side lens portion L21, or between the second lens substrate L22 and the second image side lens portion L23). ) Is provided with a diaphragm ST (FIGS. 1 to 10) which will be described later. That is, the optical diaphragm in each type of imaging lens described above is provided on the lens substrate (parallel plate) L22 of the second block C2.

  The grid-like spacer member B1 is a two-stage grid that defines a block interval and keeps it constant, and each lens portion is arranged in a hole portion of the grid. The substrate B2 is a wafer level sensor chip size package including a microlens array, or a parallel flat plate such as a sensor cover glass or an IR cut filter (corresponding to the parallel flat plate PT in FIG. 21). The lens substrates are sealed on the substrate B2 via the spacer member B1, and the first lens substrate L12, the second lens substrate L22, and the spacer member B1 integrated with each other are connected to the lattice frame of the spacer member B1 (position of the broken line Q). When cutting with, a plurality of two-block imaging lenses are obtained. Of course, the blocks through the resin layer may be sealed without sealing the lens substrates. Thus, if the imaging lens is separated from a state where a plurality of first blocks C1 and second blocks C2 are assembled, it is not necessary to adjust and assemble the lens interval for each imaging lens, and mass production is possible. Become. Moreover, by making the spacer member B1 into a lattice shape, it can be used as a mark when the spacer member B1 is cut off. This is in accordance with the gist of the present technical field, and can contribute to mass production of an inexpensive lens system.

  Next, the specific optical configuration of the imaging lens LN will be described in more detail with reference to the first to tenth embodiments. 1 to 10 show the lens configurations of the first to tenth embodiments of the imaging lens LN in optical cross sections, respectively. The imaging lens LN of each embodiment is a single focus lens for imaging (for example, for a portable terminal) that forms an optical image IM with respect to the imaging element SR (FIG. 21). It is composed of two blocks, a block C1 and a second block C2. The first to sixth, ninth, and tenth embodiments are type 1 imaging lenses, and the seventh and eighth embodiments are type 2 imaging lenses.

  In the first to sixth and ninth embodiments, the blocks C1 and C2 are configured as follows in order from the object side. In the first block C1, the first object side lens unit L11, the first lens substrate L12, and the first image side lens unit L13 are arranged in this order. In the second block C2, the second object-side lens portion L21, the second lens substrate L22, and the second image-side lens portion L23 are arranged in this order, and the planar portion (second object-side lens portion L21 of the second lens substrate L22). Alternatively, an aperture stop ST is disposed on a boundary surface with the second image side lens portion L23. When the nth block (n = 1, 2) from the object side to the image side is the nth block Cn, both surfaces of the nth block Cn are aspherical (that is, all lens surfaces in contact with air). The nth object side lens portion Ln1 and the nth lens substrate Ln2 have different refractive indexes, and the nth lens substrate Ln2 and the nth image side lens portion Ln3 have different refractive indexes.

  In the tenth embodiment, the blocks C1 and C2 are configured as follows in order from the object side. In the first block C1, the first object side lens unit L11, the first lens substrate L12, and the first image side lens unit L13 are arranged in this order. In the second block C2, the second lens substrate L22 and the second image side lens portion L23 are arranged in this order, and an opening is formed in the plane portion of the second lens substrate L22 (boundary surface with the second image side lens portion L23). A diaphragm ST is disposed. The first block C1 is aspheric on both surfaces, and the refractive index is different between the first object side lens portion L11 and the first lens substrate L12, and the first lens substrate L12 and the first image side lens portion L13 are refracted. The rate is different. The image side surface of the second block C2 is aspherical, and the refractive index is different between the second lens substrate L22 and the second image side lens portion L23. In this embodiment, the object side portion of the second block C2 is the second lens substrate L22, and thus one side of the block can be formed as a substrate surface. That is, what provided the lens part only on the one side of the lens substrate can also be called a block.

  In the seventh and eighth embodiments, the blocks C1 and C2 are configured as follows in order from the object side. The first block C1 includes a single first lens L1 made of a substantially homogeneous medium. In the second block C2, the second object-side lens portion L21, the second lens substrate L22, and the second image-side lens portion L23 are arranged in this order, and the planar portion (second object-side lens portion L21 of the second lens substrate L22). An aperture stop ST is disposed on the boundary surface between the aperture stop ST and the aperture stop ST. When the nth block (n = 1, 2) from the object side to the image side is the nth block Cn, both surfaces of the nth block Cn are aspherical (that is, all lens surfaces in contact with air). The nth object side lens portion Ln1 and the nth lens substrate Ln2 have different refractive indexes, and the nth lens substrate Ln2 and the nth image side lens portion Ln3 have different refractive indexes.

  Hereinafter, the configuration and the like of the imaging lens embodying the present invention will be described more specifically with reference to the construction data of the examples. Examples 1 to 10 listed here are numerical examples corresponding to the first to tenth embodiments, respectively, and are optical configuration diagrams showing the first to tenth embodiments (FIGS. 1 to 10). 10) shows the lens configurations of the corresponding Examples 1 to 10, respectively.

In the construction data of each example, as surface data, in order from the left column, the surface number, the radius of curvature r (mm), the surface spacing d (mm) on the axis, and the refractive index with respect to the d-line (wavelength: 587.56 nm). The Abbe number vd for the nd and d lines is shown. The surface with * in the surface number is an aspheric surface, and the surface shape is defined by the following formula (AS) using the local Cartesian coordinate system (x, y, z) with the surface vertex as the origin. . As aspheric data, an aspheric coefficient or the like is shown. It should be noted that the coefficient of the term not described in the aspheric data of each embodiment is 0, and en = × 10 ⁻ⁿ for all data.
z = (c · h ² ) / [1 + √ {1− (1 + K) · c ² · h ² }] + Σ (Aj · h ^j )… (AS)
However,
h: height (h ² = x ² + y ² ) in the direction perpendicular to the z axis (optical axis AX)
z: Sag amount in the direction of the optical axis AX at the position of height h (based on the surface vertex),
c: curvature at the surface vertex (the reciprocal of the radius of curvature r),
K: conic constant,
Aj: j-th order aspheric coefficient,
It is.

Various data include focal length (f, mm), F number (Fno.), Half angle of view (ω, °), image height (y'max, mm), total lens length (TL, mm), back focus (BF , Mm). In the back focus, the distance from the lens final surface to the paraxial image surface is expressed by an air conversion length, and the total lens length is obtained by adding the back focus to the distance from the lens front surface to the lens final surface. Furthermore, the optical surface closest to the object side of the power of the first block C1 (mm ^-1), the most image side of the optical surface of the power of the second block C2 (mm ^-1), the power of the first block C1 (mm ^{- 1} ) and the power (mm ⁻¹ ) of the second block C2 are shown in Tables 1 and 2. However, the power shown in Table 1 is a paraxial power, and the power shown in Table 2 is the sagittal direction of each block C1C2 with respect to the principal ray in the middle band (each image height of 60% and 80% of the maximum image height). Power. Table 3 shows values corresponding to the conditional expressions.

  FIGS. 11 to 20 are aberration diagrams of Examples 1 to 10 (EX1 to 10) (infinite focus state). In each of FIGS. 11 to 20, (A) is a spherical aberration diagram, (B) is an astigmatism diagram, and (C) is a distortion diagram. The spherical aberration diagram shows the amount of spherical aberration with respect to the d-line (wavelength 587.56 nm) indicated by the solid line, the amount of spherical aberration with respect to the C-line (wavelength 656.28 nm) indicated by the alternate long and short dash line, and the amount of spherical aberration with respect to the g-line (wavelength 435.84 nm) indicated by the broken line. Is expressed by the amount of deviation (unit: mm) in the optical axis AX direction from the paraxial image plane, and the vertical axis is a value obtained by normalizing the incident height to the pupil by the maximum height (that is, relative pupil height). )). In the astigmatism diagram, the broken line T represents the tangential image surface with respect to the d-line, and the solid line S represents the sagittal image surface with respect to the d-line in terms of the deviation (unit: mm) in the optical axis AX direction from the paraxial image surface. The vertical axis represents the image height (IMG HT, unit: mm). In the distortion diagram, the horizontal axis represents distortion (unit:%) with respect to the d-line, and the vertical axis represents image height (IMG HT, unit: mm). The maximum value of the image height IMG HT corresponds to the maximum image height y′max (half the diagonal length of the light receiving surface SS of the image sensor SR) on the image plane IM.

Example 1
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * 42.334 0.303 1.51 56.0
2 ∞ 0.348 1.52 62.0
3 ∞ 0.070 1.57 34.0
4 * 46.379 0.362
5 * -7.083 0.060 1.57 34.0
6 ∞ 0.300 1.52 62.0
7 (Aperture) ∞ 0.558 1.51 56.0
8 * 11.062 1.358
9 ∞ 0.350 1.47 65.2
10 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = 0
A4 = 9.1494e-002
A6 = 1.9100e-002
A8 = 2.4496e-002
A10 = -1.1908e-002
4th page
K = 0
A4 = 3.3304e-001
A6 = 8.7157e-001
A8 = -2.8598
A10 = 7.5466
5th page
K = -2.3170e + 002
A4 = 4.8310e-002
A6 = 3.5940e-001
A8 = 7.1048e-001
A10 = -3.0884
8th page
K = 8.8562E + 01
A2 = -5.2635E-01
A4 = -2.3051E-02
A6 = -1.4910E-01
A8 = 6.2797E-01
A10 = -9.1441E-01
A12 = 7.6458E-01

Various data
f 2.29
Fno. 2.80
ω 34.20
y'max 1.50
TL 4.40
BF 2.40

Example 2
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * 27.922 0.307 1.51 56.0
2 ∞ 0.354 1.52 62.0
3 ∞ 0.073 1.57 34.0
4 * 15.975 0.400
5 * -7.963 0.124 1.57 34.0
6 (Aperture) ∞ 0.300 1.52 62.0
7 ∞ 0.433 1.51 56.0
8 * 12.713 1.354
9 ∞ 0.350 1.47 65.2
10 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = 0
A4 = 8.8672e-002
A6 = 1.9196e-002
A8 = 2.5903e-002
A10 = -1.0994e-002
4th page
K = 0
A4 = 3.3987e-001
A6 = 8.2961e-001
A8 = -2.8674e + 000
A10 = 8.4144e + 000
5th page
K = -2.3122e + 002
A4 = 5.2801e-002
A6 = 3.9852e-001
A8 = 7.9421e-001
A10 = -4.2867
8th page
K = 1.0620E + 02
A2 = -5.2854E-01
A4 = -2.2710E-02
A6 = -1.2772E-01
A8 = 6.2288E-01
A10 = -9.9935E-01
A12 = 7.8724E-01

Various data
f 2.28
Fno. 2.80
ω 34.34
y'max 1.50
TL 4.38
BF 2.39

Example 3
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * 2.612 0.473 1.51 56.0
2 ∞ 0.200 1.52 62.0
3 ∞ 0.101 1.57 34.0
4 * 2.507 0.268
5 * -4.612 0.088 1.57 34.0
6 (Aperture) ∞ 0.300 1.52 62.0
7 ∞ 0.474 1.51 56.0
8 * -0.870 1.105
9 ∞ 0.350 1.47 65.2
10 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = 0
A4 = 8.0486e-002
A6 = 1.1082e-002
A8 = 5.3524e-002
A10 = 2.0356e-002
4th page
K = 0
A4 = 4.8054e-001
A6 = 6.9315e-001
A8 = -2.3861
A10 = 2.5887e + 001
5th page
K = -1.7607e + 002
A4 = -2.4008e-001
A6 = 1.1199
A8 = 3.8344
A10 = -2.2967e + 001
8th page
K = 0
A4 = 9.2129e-002
A6 = -4.2878e-002
A8 = 2.9923e-001
A10 = 1.1748e-001

Various data
f 2.20
Fno. 2.80
ω 34.85
y'max 1.50
TL 4.04
BF 2.14

Example 4
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * 3.490 0.400 1.51 56.0
2 ∞ 0.350 1.52 62.0
3 ∞ 0.065 1.85 23.8
4 * 5.324 0.192
5 * -1.695 0.050 1.57 34.0
6 ∞ 0.200 1.52 62.0
7 (Aperture) ∞ 0.371 1.51 56.0
8 * -0.705 1.275
9 ∞ 0.350 1.47 65.2
10 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = 0
A4 = 3.2081e-002
A6 = 1.7037e-001
A8 = -1.9368e-001
A10 = 1.6059e-001
4th page
K = 0.0000
A4 = 3.3106e-001
A6 = 7.7466e-001
A8 = -3.7496
A10 = 2.3889e + 001
5th page
K = 1.1138e + 001
A4 = -5.5347e-002
A6 = 1.6705
A8 = -7.3490
A10 = 1.3307e + 001
8th page
K = -4.6577e-002
A4 = 5.7456e-002
A6 = -2.2996e-001
A8 = 5.9818e-001
A10 = -2.1731

Various data
f 2.20
Fno. 2.80
ω 35.41
y'max 1.50
TL 3.94
BF 2.31

Example 5
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * 4.061 0.400 1.51 56.0
2 ∞ 0.332 1.81 33.2
3 ∞ 0.050 1.84 23.7
4 * 6.074 0.168
5 * -2.173 0.084 1.57 34.0
6 (Aperture) ∞ 0.300 1.52 62.0
7 ∞ 0.384 1.51 56.0
8 * -0.778 1.318
9 ∞ 0.350 1.47 65.2
10 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = 0
A4 = 3.9939e-002
A6 = 1.7567e-001
A8 = -1.9202e-001
A10 = 1.8144e-001
4th page
K = 0
A4 = 2.9517e-001
A6 = 5.7168e-001
A8 = -1.9757
A10 = 1.6561e + 001
5th page
K = 1.9641e + 001
A4 = 3.7939e-002
A6 = 1.4543
A8 = -6.6048
A10 = 3.2186e + 001
8th page
K = 0
A4 = 7.9622e-002
A6 = -3.4328e-001
A8 = 1.6456e + 000
A10 = -2.4147

Various data
f 2.20
Fno. 2.80
ω 36.15
y'max 1.50
TL 4.07
BF 2.36

Example 6
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * 8.884 0.430 1.51 56.0
2 ∞ 0.150 1.52 62.0
3 ∞ 0.050 1.57 34.0
4 * 6.821 0.600
5 * -5.270 0.065 1.57 34.0
6 ∞ 0.201 1.52 62.0
7 (Aperture) ∞ 0.512 1.51 56.0
8 * -0.930 1.298
9 ∞ 0.350 1.47 65.2
10 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = 0
A4 = 5.4130e-002
A6 = 9.3416e-002
A8 = -7.1479e-002
A10 = 3.7461e-002
4th page
K = 0
A4 = 6.7658e-002
A6 = 1.1941
A8 = -2.6972
A10 = 3.3188
5th page
K = 0
A4 = -8.6704e-002
A6 = -1.7296e-001
A8 = 7.6911e-001
A10 = -5.0451
8th page
K = 0
A4 = 5.8049e-002
A6 = -1.1394e-001
A8 = 6.6746e-001
A10 = -7.8003e-001

Various data
f 2.20
Fno. 2.80
ω 35.27
y'max 1.50
TL 4.34
BF 2.33

Example 7
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * 2.829 1.000 1.70 43.0
2 * 1.470 0.400
3 * -3.675 0.185 1.57 34.0
4 (Aperture) ∞ 0.320 1.52 62.0
5 ∞ 0.297 1.51 56.0
6 * -0.733 1.339
7 ∞ 0.350 1.47 65.2
8 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = 0
A4 = 5.3762e-002
A6 = 1.3712e-002
A8 = -9.6510e-003
A10 = 1.0487e-002
Second side
K = 0
A4 = 4.6459e-001
A6 = 6.5562e-001
A8 = -3.0592
A10 = 1.6488e + 001
Third side
K = 0
A4 = -2.6822e-001
A6 = -1.3641e-001
A8 = -7.6431e-002
A10 = -1.8217e + 001
6th page
K = 0
A4 = 9.7259e-002
A6 = 1.2668e-001
A8 = -4.9175e-001
A10 = 1.6901

Various data
f 2.20
Fno. 2.80
ω 34.52
y'max 1.50
TL 4.58
BF 2.38

Example 8
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * 1.228 0.853 1.81 27.0
2 * 0.553 0.517
3 * 1.832 0.233 1.57 34.0
4 (Aperture) ∞ 0.200 1.52 62.0
5 ∞ 0.734 1.51 56.0
6 * -0.900 1.016
7 ∞ 0.350 1.47 65.2
8 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = 0
A4 = 2.8878e-002
A6 = -4.8964e-002
A8 = 6.6759e-002
A10 = -2.9418e-002
Second side
K = 7.1493e-002
A4 = 2.9922e-001
A6 = -2.2798e + 000
A8 = 1.4867e + 001
A10 = -3.0252e + 001
Third side
K = 0
A4 = 3.9229e-002
A6 = 2.1646
A8 = -1.5181e + 001
A10 = 4.6488e + 001
6th page
K = -2.1170e-001
A4 = 1.2551e-001
A6 = 2.2210e-001
A8 = -1.2692e-001
A10 = 6.9722e-001

Various data
f 2.21
Fno. 2.80
ω 36.18
y'max 1.50
TL 4.59
BF 2.05

Example 9
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * 1.599 0.758 1.51389 56.53
2 ∞ 0.300 1.52000 62.00
3 ∞ 0.050 1.57207 34.88
4 * 0.725 0.264
5 * 7.762 0.166 1.57207 34.80
6 (Aperture) ∞ 0.300 1.52000 62.00
7 ∞ 0.400 1.51389 56.53
8 * -0.737 1.095
9 ∞ 0.350 1.47140 65.20
10 ∞ 0.801
Image plane ∞

Aspheric data first surface
K = 0
A4 = 3.1740e-002
A6 = 4.4374e-003
A8 = 3.8255e-003
A10 = 9.1158e-003
4th page
K = 1.5860
A4 = 3.0127e-001
A6 = -1.5803
A8 = 6.3772
A10 = 2.0364e + 001
5th page
K = 0
A4 = -5.1980e-002
A6 = 2.2810
A8 = -1.1854e + 001
A10 = 5.1937e + 001
8th page
K = -1.5772e-001
A4 = 5.7721e-002
A6 = -1.0146e-002
A8 = -2.4452e-001
A10 = 1.8885

Various data
f 2.21
Fno. 2.80
ω 36.80
y'max 1.50
TL 4.37
BF 2.13

Example 10
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * 1.678 0.470 1.51 56.0
2 ∞ 0.200 1.52 62.0
3 ∞ 0.075 1.57 34.0
4 * 1.449 0.300
5 ∞ 0.300 1.52 62.0
6 (Aperture) ∞ 0.610 1.51 56.0
7 * -0.933 0.891
8 ∞ 0.350 1.47 65.2
9 ∞ 0.805
Image plane ∞

Aspheric data first surface
K = 1.1949
A4 = 9.7029e-003
A6 = 5.3220e-002
A8 = -6.7672e-002
A10 = 7.6506e-002
4th page
K = 1.4511
A4 = 1.8328e-001
A6 = 1.9488
A8 = -8.2447
A10 = 2.5459e + 001
7th page
K = -2.3568e-001
A4 = 1.9822e-001
A6 = -1.7204
A8 = 6.5317
A10 = -8.5755

Various data
f 2.20
Fno. 2.80
ω 35.78
y'max 1.50
TL 3.89
BF 1.93

DU mobile terminal LU imaging device LN imaging lens C1, C2 first and second block L1 first lens (one lens made of a substantially homogeneous medium)
L11, L21 First and second object side lens portions L12, L22 First and second lens substrates L13, L23 First and second image side lens portions ST Aperture stop (optical stop)
SR Image sensor SS Light-receiving surface IM Image surface (optical image)
AX optical axis B1 spacer member 1 signal processing unit 2 control unit 3 memory 4 operation unit 5 display unit

Claims (23)

As an optical element having power, an imaging lens having a two-block configuration including a first block and a second block in order from the object side,
The first and second blocks are each composed of a lens substrate that is a parallel plate, and a lens unit that is formed on at least one of the object side surface and the image side surface, and has a positive or negative power, The lens substrate and the lens portion are made of different materials, and there is an optical stop on the image side of the first block, and the optical surface closest to the object side of the first block has a substantially convex shape on the object side, An imaging lens, wherein an optical surface closest to the image plane of the second block has a substantially convex shape on the image plane side. The imaging lens according to claim 1, wherein the following conditional expressions (1) and (2) are satisfied:
0 <S (s1F-st) / r_1F <3.0 (1)
0 <S (s2R-st) / r_2R <3.0 (2)
However,
S (s1F-st): Air conversion distance from the optical surface closest to the object side of the first block to the stop,
S (s2R-st): Air equivalent distance from the optical surface closest to the image plane of the second block to the stop,
r_1F: Paraxial radius of curvature of the optical surface closest to the object in the first block,
r_2R: Paraxial radius of curvature of the optical surface closest to the image plane of the second block,
It is. The imaging lens according to claim 1 or 2, wherein the following conditional expressions (3) and (4) are satisfied:
0 <{2 × S (s1F-st)} / {f_s1F (0.6) + f_s1F (0.8)} <3 (3)
0 <{2 × S (s2R-st)} / {f_s2R (0.6) + f_s2R (0.8)} <3… (4)
However,
S (s1F-st): Air conversion distance from the optical surface closest to the object side of the first block to the stop,
S (s2R-st): Air equivalent distance from the optical surface closest to the image plane of the second block to the stop,
f_s1F (0.6): Sagittal focal length on the most object-side optical surface of the first block for the chief ray of 60% of the maximum image height,
f_s1F (0.8): Sagittal focal length on the most object-side optical surface of the first block with respect to the principal ray with an image height of 80% of the maximum image height,
f_s2R (0.6): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 60% of the maximum image height,
f_s2R (0.8): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 80% of the maximum image height,
It is.   The imaging lens according to any one of claims 1 to 3, wherein the optical aperture is located on a plane portion of the lens substrate of the second block. The imaging lens according to claim 1, wherein the following conditional expression (5) is satisfied:
0.05 <{f_s2R (0.6) + f_s2R (0.8)} / {f_s1F (0.6) + f_s1F (0.8)} <3.0… (5)
However,
f_s1F (0.6): Sagittal focal length on the most object-side optical surface of the first block for the chief ray of 60% of the maximum image height,
f_s1F (0.8): Sagittal focal length on the most object-side optical surface of the first block with respect to the principal ray with an image height of 80% of the maximum image height,
f_s2R (0.6): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 60% of the maximum image height,
f_s2R (0.8): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 80% of the maximum image height,
It is. 6. The imaging lens according to claim 1, wherein the optical surface closest to the image plane of the first block has negative power and satisfies the following conditional expression (6): ;
-5.0 <φ_s1R / φ_all <-0.01… (6)
However,
φ_s1R: power of the optical surface closest to the image plane of the first block,
φ_all: Power of the whole system,
It is. The imaging lens according to any one of claims 1 to 6, wherein the first block has a negative power as a whole and satisfies the following conditional expression (7):
-2 <φ_s1_all / φ_all <0 (7)
However,
φ_s1_all: Power of the first block,
φ_all: Power of the whole system,
It is. As an optical element having power, an imaging lens having a two-block configuration including a first block and a second block in order from the object side,
The first block is composed of a single lens made of a substantially homogeneous medium, and the second block is formed on at least one of a lens substrate that is a parallel plate and its object side surface and image side surface. A lens portion having positive or negative power, and the lens substrate and the lens portion are made of different materials, and an optical diaphragm is present on the image side from the first block, An imaging lens, wherein an optical surface closest to the object side has a generally convex shape toward the object side, and an optical surface closest to the image surface of the second block has a generally convex shape toward the image surface side.   The imaging lens according to claim 8, wherein the one lens made of the substantially homogeneous medium is a glass lens or a glass mold lens.   9. The imaging lens according to claim 8, wherein the one lens made of the substantially homogeneous medium is a plastic lens. The imaging lens according to claim 8, wherein the following conditional expressions (1) and (2) are satisfied:
0 <S (s1F-st) / r_1F <3.0 (1)
0 <S (s2R-st) / r_2R <3.0 (2)
However,
S (s1F-st): Air conversion distance from the optical surface closest to the object side of the first block to the stop,
S (s2R-st): Air equivalent distance from the optical surface closest to the image plane of the second block to the stop,
r_1F: Paraxial radius of curvature of the optical surface closest to the object in the first block,
r_2R: Paraxial radius of curvature of the optical surface closest to the image plane of the second block,
It is. The imaging lens according to any one of claims 8 to 11, wherein the following conditional expressions (3) and (4) are satisfied:
0 <{2 × S (s1F-st)} / {f_s1F (0.6) + f_s1F (0.8)} <3 (3)
0 <{2 × S (s2R-st)} / {f_s2R (0.6) + f_s2R (0.8)} <3… (4)
However,
S (s1F-st): Air conversion distance from the optical surface closest to the object side of the first block to the stop,
S (s2R-st): Air equivalent distance from the optical surface closest to the image plane of the second block to the stop,
f_s1F (0.6): Sagittal focal length on the most object-side optical surface of the first block for the chief ray of 60% of the maximum image height,
f_s1F (0.8): Sagittal focal length on the most object-side optical surface of the first block with respect to the principal ray with an image height of 80% of the maximum image height,
f_s2R (0.6): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 60% of the maximum image height,
f_s2R (0.8): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 80% of the maximum image height,
It is.   The imaging lens according to any one of claims 8 to 12, wherein the optical aperture is located on a plane portion of a lens substrate of the second block. The imaging lens according to claim 8, wherein the following conditional expression (5) is satisfied:
0.05 <{f_s2R (0.6) + f_s2R (0.8)} / {f_s1F (0.6) + f_s1F (0.8)} <3.0… (5)
However,
f_s1F (0.6): Sagittal focal length on the most object-side optical surface of the first block for the chief ray of 60% of the maximum image height,
f_s1F (0.8): Sagittal focal length on the most object-side optical surface of the first block with respect to the principal ray with an image height of 80% of the maximum image height,
f_s2R (0.6): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 60% of the maximum image height,
f_s2R (0.8): Sagittal focal length on the optical surface closest to the image plane of the second block with respect to the chief ray with an image height of 80% of the maximum image height,
It is. The imaging lens according to claim 8, wherein an optical surface closest to the image plane of the first block has negative power and satisfies the following conditional expression (6): ;
-5.0 <φ_s1R / φ_all <-0.01… (6)
However,
φ_s1R: power of the optical surface closest to the image plane of the first block,
φ_all: Power of the whole system,
It is. The imaging lens according to claim 8, wherein the first block has negative power as a whole and satisfies the following conditional expression (7):
-2 <φ_s1_all / φ_all <0 (7)
However,
φ_s1_all: Power of the first block,
φ_all: Power of the whole system,
It is.   The imaging lens according to claim 1, wherein the lens substrate is made of a glass material.   The imaging lens according to claim 1, wherein the lens portion is made of a resin material.   The imaging lens according to claim 18, wherein the resin material is an energy curable resin material.   The imaging lens according to claim 18 or 19, comprising inorganic fine particles of 30 nanometers or less dispersed in the resin material.   Sealing the lens substrates or the first and second blocks via a lattice spacer member, and cutting the integrated lens substrate and the spacer member with a lattice frame of the spacer member; The imaging lens according to any one of claims 1 to 20, wherein the block is manufactured by a manufacturing method including:   An imaging lens according to any one of claims 1 to 21, and an imaging device that converts an optical image formed on the light receiving surface into an electrical signal, and a subject on the light receiving surface of the imaging device. An imaging apparatus, wherein the imaging lens is provided so as to form an optical image.   A portable terminal comprising the imaging device according to claim 22.

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