JP2010266815A - Imaging lens, image capturing apparatus and mobile terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging lens capable of coping with a minute pixel pitch of an imaging device, and securing a back focus to maintain thickness of a cover glass even when achieving a short focus and a wide angle, and also suitable for mass production at low cost, and to provide an image capturing apparatus including the same and a mobile terminal. <P>SOLUTION: The imaging lens LN includes first and second lens blocks C1 and C2. Lens substrates L12 and L22 and lens parts L11, L13, L21 and L23 are different in quality of material. A surface nearest to an object side of the first lens block C1 has negative power. The imaging lens LN satisfies an expression (1):-2<ϕ_1Fn/ϕ_all<0 (in the expression (1), ϕ_1Fn means paraxial power of the surface nearest to the object side of the first lens block, and ϕ_all means paraxial power of the entire system), an expression (2):¾Δνd(s1-pt1)¾<50 (in the expression (2), Δνd(s1-pt1) means a difference of an Abbe number between material of the lens part constituting the surface nearest to the object side of the first lens group and material of the lens substrate of the first lens block), and an expression (3): nd_s1>1.4 (in the expression (3), nd_s1 means a refractive index of the material of the lens part constituting the surface nearest to the object side of the first lens block). <P>COPYRIGHT: (C)2011,JPO&INPIT

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

  When the size of the image sensor and the pixel pitch are reduced, it is necessary to shorten the focal length in order to perform shooting at 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.

  The present invention has been made in view of such a situation, and an object of the present invention 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. It is another object of the present invention to provide an imaging lens that can secure a back focus and that is suitable for mass production at low cost, and an imaging apparatus and a portable terminal including the imaging lens.

In order to achieve the above object, an imaging lens of a first invention 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. , The lens substrate and the lens portion are made of different materials and are imaging lenses including two blocks of the lens block. The lens blocks are arranged in order from the object side in the first order. When called a lens block or a second lens block, the most object side surface of the first lens block has a negative power and satisfies the following conditional expressions (1) to (3).
-2 <φ_1Fn / φ_all <0 (1)
| Δνd (s1-pt1) | <50… (2)
nd_s1> 1.4 (3)
However,
φ_1Fn: Paraxial power of the most object side surface of the first lens block,
φ_all: Paraxial power of the entire system,
Δνd (s1-pt1): difference in Abbe number between the material of the lens part constituting the most object side surface of the first lens block and the material of the lens substrate of the first lens block,
nd_s1: The refractive index of the material of the lens part constituting the most object side surface of the first lens block,
It is.

An imaging lens according to a second invention is a lens block including an optical element including 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 unit are different materials and are imaging lenses including two lens blocks. The lens blocks are arranged in order from the object side, the first lens block, the second lens block, and the like. When called, the most object side surface of the first lens block has negative power, and satisfies the following conditional expressions (2) to (4).
-2 <(φ_1Fn (0.5) + φ_1Fn (0.7) + φ_1Fn (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <0… (4)
| Δνd (s1-pt1) | <50… (2)
nd_s1> 1.4 (3)
However,
φ_1Fn (0.5): The power in the sagittal direction with respect to the principal ray with the angle of view of 50% of the maximum angle of view of the surface closest to the object side of the first lens block
φ_1Fn (0.7): The power in the sagittal direction with respect to the principal ray with the field angle of 70% of the maximum field angle of the surface closest to the object side of the first lens block.
φ_1Fn (0.9): the power in the sagittal direction with respect to the chief ray of 90% of the maximum field angle on the most object side surface of the first lens block,
φ_all (0.5): The power in the sagittal direction with respect to the chief ray of 50% of the maximum field angle of the entire system,
φ_all (0.7): The power in the sagittal direction with respect to the chief ray of 70% of the maximum field angle of the entire system,
φ_all (0.9): The power in the sagittal direction for the chief ray of 90% of the maximum field angle of the entire system,
Δνd (s1-pt1): difference in Abbe number between the material of the lens part constituting the most object side surface of the first lens block and the material of the lens substrate of the first lens block,
nd_s1: The refractive index of the material of the lens part constituting the most object side surface of the first lens block,
It is.

An imaging lens according to a third aspect of the invention is characterized in that, in the first or second aspect of the invention, the following conditional expression (5) is satisfied.
0.2 <fb / f_all <2 (5)
However,
fb: Back focus of the entire system,
f_all: the paraxial focal length of the entire system,
It is.

The imaging lens of a fourth invention is the imaging lens according to any one of the first to third inventions, wherein the most object side surface of the first lens block has a paraxial and concave shape on the object side, and The condition (6) is satisfied.
-5 <f_all / r_1Fn <0 (6)
However,
f_all: the paraxial focal length of the entire system,
r_1Fn: Paraxial radius of curvature of the most object side surface of the first lens block,
It is.

  The imaging lens according to a fifth aspect of the present invention is characterized in that, in any one of the first to fourth aspects, a diaphragm is disposed on a plane portion of the lens substrate of the first lens block.

  The imaging lens of a sixth invention is characterized in that, in any one of the first to fifth inventions, the most object side surface of the second lens block has a positive power.

The imaging lens of a seventh invention is the imaging lens of the sixth invention, wherein the most object side surface of the second lens block has a paraxial convex shape on the object side, and the following conditional expression (7): It is characterized by satisfaction.
0 <f_all / r_2Fp <4 (7)
However,
f_all: the paraxial focal length of the entire system,
r_2Fp: Paraxial radius of curvature of the positive power surface closest to the object side of the second lens block,
It is.

The imaging lens of an eighth invention is characterized in that, in the sixth invention, the most object side surface of the second lens block satisfies the following conditional expression (8) from the middle band to the periphery. .
0 <(φ_2Fp (0.5) + φ_2Fp (0.7) + φ_2Fp (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <2… (8)
However,
φ_2Fp (0.5): The power in the sagittal direction for the principal ray with the angle of view of 50% of the maximum angle of view of the surface closest to the object side of the second lens block
φ_2Fp (0.7): The power in the sagittal direction with respect to the principal ray with the field angle of 70% of the maximum field angle of the surface closest to the object side of the second lens block,
φ_2Fp (0.9): The power in the sagittal direction with respect to the chief ray at 90% of the maximum field angle of the surface closest to the object side of the second lens block,
φ_all (0.5): The power in the sagittal direction with respect to the chief ray of 50% of the maximum field angle of the entire system,
φ_all (0.7): The power in the sagittal direction with respect to the chief ray of 70% of the maximum field angle of the entire system,
φ_all (0.9): The power in the sagittal direction for the chief ray of 90% of the maximum field angle of the entire system,
It is.

  The imaging lens of a ninth invention is characterized in that, in any one of the sixth to eighth inventions, the surface closest to the image plane of the second lens block has a negative power.

  The imaging lens of a tenth invention is characterized in that, in any one of the sixth to eighth inventions, the surface closest to the image plane of the second lens block has a positive power.

  The imaging lens of an eleventh aspect of the present invention is the imaging lens according to any one of the first to fifth aspects, wherein the second lens block has a negative power on the most object side surface and a most image side surface. It has a positive power.

The imaging lens of a twelfth aspect of the present invention is the imaging lens according to the eleventh aspect of the invention, wherein the most image side surface of the second lens block has a paraxial convex shape on the image side, ) Is satisfied.
-4 <f_all / r_2Rp <0 (9)
However,
f_all: the paraxial focal length of the entire system,
r_2Rp: Paraxial radius of curvature of the positive power surface closest to the image plane of the second lens block,
It is.

An imaging lens of a thirteenth invention is characterized in that, in the eleventh invention, the surface closest to the image plane of the second lens block satisfies the following conditional expression (10) from the middle band to the periphery. To do.
0 <(φ_2Rp (0.5) + φ_2Rp (0.7) + φ_2Rp (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <2.0… (10)
However,
φ_2Rp (0.5): The power in the sagittal direction with respect to the principal ray with the field angle of 50% of the maximum field angle on the surface closest to the image plane of the second lens block,
φ_2Rp (0.7): Power in the sagittal direction with respect to the principal ray with a field angle of 50% of the maximum field angle of the surface closest to the image plane of the second lens block,
φ_2Rp (0.9): Power in the sagittal direction with respect to the chief ray with a field angle of 50% of the maximum field angle of the surface closest to the image plane of the second lens block,
φ_all (0.5): The power in the sagittal direction with respect to the chief ray of 50% of the maximum field angle of the entire system,
φ_all (0.7): The power in the sagittal direction with respect to the chief ray of 70% of the maximum field angle of the entire system,
φ_all (0.9): The power in the sagittal direction for the chief ray of 90% of the maximum field angle of the entire system,
It is.

The imaging lens of the fourteenth invention is the imaging lens of any one of the first to thirteenth inventions, wherein the most object-side surface of the second lens block has a paraxial and concave shape on the object side, and The following conditional expression (11) is satisfied.
-6 <f_all / r_2Fn <0 (11)
However,
f_all: the paraxial focal length of the entire system,
r_2Fn: Paraxial radius of curvature of the most object side negative power surface of the second lens block,
It is.

The imaging lens of a fifteenth aspect of the present invention is the imaging lens according to any one of the above eleventh to fourteenth aspects, wherein the most object side surface of the second lens block extends from the middle band to the periphery, and the following conditional expression (12) is satisfied: It is characterized by satisfaction.
-4 <(φ_2Fn (0.5) + φ_2Fn (0.7) + φ_2Fn (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <0… (12)
However,
φ_2Fn (0.5): The power in the sagittal direction for the principal ray with the angle of view of 50% of the maximum angle of view of the surface closest to the object side of the second lens block
φ_2Fn (0.7): The power in the sagittal direction with respect to the principal ray with the field angle of 70% of the maximum field angle of the surface closest to the object side of the second lens block,
φ_2Fn (0.9): Power in the sagittal direction with respect to the principal ray with 90% of the maximum field angle of the surface closest to the object side of the second lens block,
φ_all (0.5): The power in the sagittal direction with respect to the chief ray of 50% of the maximum field angle of the entire system,
φ_all (0.7): The power in the sagittal direction with respect to the chief ray of 70% of the maximum field angle of the entire system,
φ_all (0.9): The power in the sagittal direction for the chief ray of 90% of the maximum field angle of the entire system,
It is.

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

  An image pickup lens of a seventeenth invention is characterized in that, in any one of the first to sixteenth inventions, the lens portion is made of a resin material.

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

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

  The imaging lens of a twentieth invention is integrated with the step of sealing the lens substrates or the lens blocks through a lattice-like spacer member in any one of the first to nineteenth inventions. The lens block is manufactured by a manufacturing method including a step of cutting the lens substrate and the spacer member with a lattice frame of the spacer member.

  An image pickup apparatus according to a twenty-first invention includes the image pickup lens according to any one of the first to twentieth inventions, and an image pickup 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-second invention is characterized by comprising the imaging device according to the twenty-first invention.

  According to the present invention, it is possible to cope with a minute pixel pitch of an image pickup device, and it is possible to secure a feasible back focus to the extent that the thickness of the cover glass can be maintained even when the focal length is shortened and widened. An imaging lens suitable for mass production at a low cost while having high optical performance, an imaging device including the imaging lens, and a portable terminal can be realized. For example, by employing a wafer level lens that can be mass-produced, it is possible to achieve cost reduction, secure back focus, increase performance, and achieve 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 with reference to the drawings. The imaging lens according to the present invention includes two lens blocks. However, the “lens block” refers to an optical element that 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. Note that the lens substrate and the lens portion assumed here are made of different materials.

Since the imaging lens includes two lens blocks as described above, the imaging lens has a block arrangement including a first lens block and a second lens block in order from the object side. The most object-side surface of the first lens block has a negative power, and satisfies the following conditional expressions (1) to (3).
-2 <φ_1Fn / φ_all <0 (1)
| Δνd (s1-pt1) | <50… (2)
nd_s1> 1.4 (3)
However,
φ_1Fn: Paraxial power of the most object side surface of the first lens block,
φ_all: Paraxial power of the entire system,
Δνd (s1-pt1): difference in Abbe number between the material of the lens part constituting the most object side surface of the first lens block and the material of the lens substrate of the first lens block,
nd_s1: The refractive index of the material of the lens part constituting the most object side surface of the first lens block,
It is.

  Cost reduction is strongly demanded for an imaging apparatus, a portable terminal, and the like provided with an imaging lens such as 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. When the pixel 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. As the focal length decreases, the back focus decreases accordingly. For example, when the scale is performed in order to shorten the focal length of the conventional optical system, the total length and the back focus are also shortened. And the thickness of the cover glass is also scaled down.

  Since an imaging optical system such as the optical system according to the present invention is desired to be miniaturized, there is no allowance for back focus, and the cover glass is also designed with a minimum limit thickness. For this reason, when the scale-down is performed, the back focus is shortened, resulting in practical problems. In addition, a cover glass or the like for protecting the image sensor is also scaled down. However, it is difficult for the cover glass to be thinner than a certain thickness due to the necessity of strength. In order to further reduce the thickness, it is inevitable that the cost will be significantly increased, including changes in materials. Accordingly, it is difficult to simply widen the angle and shorten the focal length by a method of scaling an existing optical system.

  Therefore, the optical system according to the present invention is configured such that the back focus can be secured even with a short focal length by making the most object side optical surface a negative power surface. 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. Condition (1) is a condition for ensuring the back focus while maintaining high performance. If it falls within the range of conditional expression (1), various aberrations (particularly coma aberration) can be reduced while appropriately ensuring back focus, and a high-performance optical system can be realized. If the power becomes positive beyond the upper limit of conditional expression (1), it is difficult to ensure the back focus. On the other hand, if the lower limit of conditional expression (1) is exceeded, the negative power of the surface becomes too strong and coma becomes strong, so that practical performance cannot be achieved.

  In the case of an ordinary two-lens optical system, since the material of the most object side surface and the material of the image side surface of the first lens block are the same, aberration correction is limited. However, as in the optical system according to the present invention, if the lens block configuration forms an optical surface composed of a lens portion with a resin or the like on both sides of a parallel plate serving as a lens substrate, for example, the material before and after the parallel plate is used. By changing it, the front and back aberration correction (chromatic aberration correction, Petzval correction, etc.) can be performed independently, so even a two-block configuration has a much higher performance optical system than a two-lens optical system. Can be realized.

  Further, in the case of the lens block configuration as described above, the material of the parallel plate on the object side optical surface and the material of the parallel plate, and the material of the parallel plate on the image side optical surface and the material of the parallel plate are different. Then, chromatic aberration occurs at each boundary surface except when light rays are vertically incident and totally reflected, so it is possible to perform optimal chromatic aberration correction by making the difference in dispersion of this material appropriate. It becomes possible to realize a high-performance optical system. The condition is conditional expression (2).

  Δνd (s1−pt1) defined by the conditional expression (2) is the optical material of the lens part constituting the object-side surface (that is, the first surface) of the first lens block, and the lens substrate of the first lens block ( The difference between the Abbe number and the material of the parallel plate. In this part, since obliquely incident light rays generate chromatic aberration, optimal chromatic aberration correction can be performed by appropriately setting the generation amount. It is also possible to correct only the secondary chromatic aberration with the same main dispersion. Furthermore, it is also possible to change the monochromatic aberration only by the difference in the refractive index at the boundary and use it for aberration correction with the same dispersion. In any case, if the difference in dispersion is too large, the amount of chromatic aberration generated in this portion increases, and high performance cannot be maintained. Conditional expression (2) regulates the range, and within this range, it is possible to realize an imaging lens in which chromatic aberration is favorably corrected.

  Furthermore, it is important to appropriately set the refractive index of the material of the lens part that constitutes the most object-side surface (first surface) of the first lens block. In order to design a surface of the same power with different refractive index materials, it is necessary to change the radius of curvature. If the optical surface is configured with a high refractive index, the optical surface can be configured with a loose radius of curvature, and the occurrence of various aberrations can be reduced. Conditional expression (3) defines the refractive index of the material of the optical surface closest to the object side. If the curvature becomes tight, coma and the like are greatly generated and the performance deteriorates. Therefore, it is necessary to set the refractive index to an appropriate value. Conditional expression (3) defines the refractive index of the first surface necessary for maintaining high performance. If the refractive index is reduced beyond the lower limit of conditional expression (3), the curvature becomes tight, the coma aberration is deteriorated, and high performance cannot be maintained.

  Here, the above-described <negative power of the surface closest to the object side of the first lens block> will be described in more detail. The spherical surface of a normal coaxial optical system (when the optical surface is a spherical surface and is not decentered) has a paraxial axis (that is, near the optical axis) and an effective diameter range (a range through which peripheral rays pass). The radius of curvature is the same. Therefore, normally speaking, positive and negative powers are determined by the radius of curvature and refractive index of the paraxial surface. However, for peripheral rays, for example, chief rays, the power in the sagittal direction is the same at the center and the periphery, but the power in the meridional direction is different. This also causes astigmatism. In the case of a coaxial optical system, the power of the peripheral ray is different from the center, but there is no problem even if the paraxial power is used. (Note that the value corresponding to Conditional Expression (1) below is the calculated value for the paraxial power. .)

  On the other hand, the curvature of a non-spherical surface (for example, an aspheric surface) is usually different between the center and the periphery. Therefore, the power at the center and the periphery are usually different in the meridional direction and the sagittal direction. Further, as can be seen from the mathematical formulas that define the shape of the aspherical surface, it is possible to realize a complicated shape depending on how the coefficient is held, thereby greatly increasing the aberration correction capability. Therefore, the negative power is not generally determined by the paraxial radius of curvature and refractive index as in the spherical optical system. However, the negative power acts to diverge light rays, and the surface having this property is called a surface having negative power. Therefore, negative power means that there is a tendency to diverge light as a whole, and even if there is a part that is not part of the surface, if there is much tendency to diverge as a whole, negative power It will be called an optical surface having In order to discriminate between positive and negative power, the optical surface is subdivided, the power of each is obtained, and their combination or the average can be determined by whether the average is positive or negative. It is also possible to distinguish by selecting some points sufficiently randomly and combining or averaging the power of each surface. The essence referred to as negative power here is that it is a surface that tends to diverge light, and if it satisfies this condition, it is regarded as a negative power surface.

  Next, a method for calculating the surface power (the reciprocal of the focal length) will be described. Usually, the power of a surface having a coaxial system can be calculated from the local curvature of the surface at the intersection of the surface on the optical axis and the optical axis, and the refractive indexes before and after the surface. However, the case of off-axis is slightly different. For off-axis rays, power is calculated along the off-axis ray. In other words, the power of a surface with off-axis rays is the position where the principal ray of the off-axis light intersects the surface, the local curvature of the surface, the angle of incidence of the principal ray on the surface, and the front and back of the surface. And the refractive index of The power on a surface with an off-axis field angle (for example, 50% of the maximum field angle) is the local curvature of the surface at the position (intersection) where the principal ray of that field angle intersects that surface. And the incident angle of the principal ray on the surface and the refractive index before and after the surface. The off-axis power of a certain part, for example, the first lens block, is the power calculated along the principal ray of the off-axis light beam, and is the combined power of the powers on the above surfaces. Note that the corresponding values in conditional expressions (4), (8) and the like are values obtained by calculating the power of the surface with respect to the sagittal ray.

From the above viewpoint, the off-axis power may be defined instead of defining the paraxial power in the conditional expression (1). For example, it is desirable that the following conditional expression (4) is satisfied together with the conditional expressions (2) and (3).
-2 <(φ_1Fn (0.5) + φ_1Fn (0.7) + φ_1Fn (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <0… (4)
However,
φ_1Fn (0.5): The power in the sagittal direction with respect to the principal ray with the angle of view of 50% of the maximum angle of view of the surface closest to the object side of the first lens block
φ_1Fn (0.7): The power in the sagittal direction with respect to the principal ray with the field angle of 70% of the maximum field angle of the surface closest to the object side of the first lens block.
φ_1Fn (0.9): the power in the sagittal direction with respect to the chief ray of 90% of the maximum field angle on the most object side surface of the first lens block,
φ_all (0.5): The power in the sagittal direction with respect to the chief ray of 50% of the maximum field angle of the entire system,
φ_all (0.7): The power in the sagittal direction with respect to the chief ray of 70% of the maximum field angle of the entire system,
φ_all (0.9): The power in the sagittal direction for the chief ray of 90% of the maximum field angle of the entire system,
It is.

  Conditional expression (4) defines the power of the surface from the middle band to the periphery. If the negative power of the part is strong, the position of the real image surface on the optical axis can be arranged farther from the final optical surface, that is, the back focus is substantially increased, so the focal length is shortened. Even if it becomes, arrangement | positioning of a cover glass etc. is attained. In addition, this part particularly affects off-axis performance. If this part is strong beyond the lower limit of conditional expression (4), the flare of lateral aberration will be affected. In particular, since the vicinity of the marginal line of the lower ray is strongly bent downward, flare is strongly generated, and the performance cannot be secured. Also, if the power ratio becomes positive beyond the upper limit of conditional expression (4), the substantial image surface position on the optical axis becomes too close to the final optical surface, so a cover glass or the like cannot be placed, Practicality is lost.

It is desirable to satisfy the following conditional expression (4A), and it is more desirable to satisfy conditional expression (4B).
-1.5 <(φ_1Fn (0.5) + φ_1Fn (0.7) + φ_1Fn (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <0… (4A)
-0.8 <(φ_1Fn (0.5) + φ_1Fn (0.7) + φ_1Fn (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <-0.02… (4B)
These conditional expressions (4A) and (4B) define a more preferable condition range based on the same viewpoint as the conditional expression (4). Therefore, the above effect can be further enhanced by preferably satisfying conditional expression (4A), more preferably satisfying conditional expression (4B).

  A characteristic configuration that satisfies the conditional expressions (1) to (3) or (2) to (4) realizes a high-performance imaging lens and an imaging device including the same while ensuring a back focus. It is possible. And if an imaging device provided with the imaging lens is used for digital equipment, such as a portable terminal, it can contribute to the compactness, cost reduction, high performance, etc. The conditions for achieving such effects in a well-balanced manner and achieving higher optical performance, improved manufacturability, etc. will be described below.

It is desirable to satisfy the following conditional expression (1a), and it is more desirable to satisfy conditional expression (1b).
-1 <φ_1Fn / φ_all <0 (1a)
-0.8 <φ_1Fn / φ_all <-0.02… (1b)
These conditional expressions (1a) and (1b) define more preferable condition ranges based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (1). Therefore, the above effect can be further increased by preferably satisfying conditional expression (1a), more preferably satisfying conditional expression (1b).

It is desirable to satisfy the following conditional expression (3a), and it is more desirable to satisfy conditional expression (3b).
nd_s1> 1.5… (3a)
nd_s1> 1.52 (3b)
These conditional expressions (3a) and (3b) define more preferable condition ranges based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (3). Therefore, the above effect can be further enhanced by preferably satisfying conditional expression (3a), more preferably satisfying conditional expression (3b).

It is desirable to satisfy the following conditional expression (5).
0.2 <fb / f_all <2 (5)
However,
fb: Back focus of the entire system,
f_all: the paraxial focal length of the entire system,
It is.

  Conditional expression (5) defines the back focus. If the back focus becomes too large, the overall optical system becomes large, which is contrary to downsizing. In order to ensure a long back focus, it is necessary to increase the negative power of the surface closest to the object side, which leads to deterioration of coma aberration. In addition, when the back focus is shortened, the space for the cover glass and the element arrangement member is lost, which makes it difficult to realize the product as a product. Shortening the back focus also increases the power of the entire optical system, and as a result, various aberrations (especially spherical aberration and off-axis astigmatism) are deteriorated. Therefore, it is necessary to set the back focus appropriately.

  If the lower limit of conditional expression (5) is exceeded and the back focus becomes too short, it will be difficult to realize a practical imaging lens, various aberrations (especially spherical aberration, off-axis astigmatism) will deteriorate, and high Performance cannot be secured. If the back focus is too long beyond the upper limit of conditional expression (5), high performance cannot be secured due to deterioration of coma aberration.

It is more desirable to satisfy the following conditional expression (5a).
0.5 <fb / f_all <1.2 (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 most object side surface of the first lens block has a paraxial concave shape on the object side and satisfies the following conditional expression (6).
-5 <f_all / r_1Fn <0 (6)
However,
f_all: the paraxial focal length of the entire system,
r_1Fn: Paraxial radius of curvature of the most object side surface of the first lens block,
It is.

  The object-side surface of the first lens block preferably has negative power, but the surface has a paraxial concave shape, and the radius of curvature preferably satisfies the conditional expression (6). . Having a concave shape is advantageous for widening the angle. If the curvature becomes too strong, the negative power becomes strong, which is advantageous for securing the back focus, but if it becomes too strong, coma becomes large. If the curvature becomes too weak, the negative power becomes too weak and the back focus cannot be secured.

  Conditional expression (6) defines conditions for ensuring high performance by appropriately correcting coma while maintaining the back focus appropriately. If the radius of curvature becomes too small beyond the lower limit of conditional expression (6), the back focus cannot be secured. If the upper limit of conditional expression (6) is exceeded, coma increases and high performance cannot be maintained. Therefore, it is necessary to appropriately set the radius of curvature of the object side surface of the first lens block. The paraxial radius of curvature determines the focal length and paraxial back focus position as well as the refractive index. If this portion is significantly different from the shape from the middle band to the periphery, the difference between the paraxial portion and the peripheral portion of the spherical aberration is greatly different, and the spherical aberration is deteriorated, resulting in an image with low contrast. Therefore, if the conditional expression (6) is exceeded, the spherical aberration is deteriorated and an image with low contrast is obtained.

It is more desirable to satisfy the following conditional expression (6a).
-1.2 <f_all / r_1Fn <0 (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).

  It is desirable that a stop be disposed on the plane portion of the lens substrate of the first lens block. The imaging lens according to the present invention is required to be compact in relation to its application, and further to be small in the radial direction. In addition, this imaging lens may be used alone, but is often incorporated in other devices. Therefore, it is more convenient to use a smaller diameter in order to mount other parts and circuits in a more compact manner. Is good. Since the sensor size is determined on the image plane side, the required telecentric performance, that is, the angle of the incident light to the sensor is limited. Furthermore, since the brightness is determined, there is a limit to reducing the size in the radial direction on the image plane side. Therefore, in order to reduce the diameter on the object side, it is preferable to reduce the radial direction of the optical system. In particular, when the aperture is at the rear, the radial direction on the object side becomes large. Therefore, in order to reduce the optical system on the object side, it is advantageous to arrange the stop on the first lens block on the object side in order to make the radial direction compact.

  It is desirable that the most object side surface of the second lens block has a positive power. Since the first surface (the object side surface of the first lens block) has a negative power, the tendency of the image surface to fall excessively can be corrected by the positive power on the object side of the second lens block. . Further, a stronger positive power can be obtained by forming a positive power surface in the portion where the axial ray is higher due to the negative power of the first surface. Further, by making this surface convex, it is advantageous for correction of coma aberration. Therefore, by making the object side surface of the second lens block a positive power, that is, a convex surface on the object side, an optical system that is advantageous for short focal length and advantageous for correction of coma and image plane Is possible.

It is desirable that the most object-side surface of the second lens block has a paraxial convex shape on the object side and satisfies the following conditional expression (7).
0 <f_all / r_2Fp <4 (7)
However,
f_all: the paraxial focal length of the entire system,
r_2Fp: Paraxial radius of curvature of the positive power surface closest to the object side of the second lens block,
It is.

  Conditional expression (7) defines the radius of curvature of the most object side surface of the second lens block in the paraxial portion. If the radius of curvature is small and the positive curvature is strong, the ability to bend the axial ray toward the object side increases as it goes to the periphery, and the spherical aberration tends to deteriorate. In the case of a material having the same refractive index, if the radius of curvature is short, the power becomes strong and it is advantageous for shortening the focal length. However, the Petzval sum becomes positive and the image surface falls too much under. . In addition, if the radius of curvature is long, the power at that portion becomes weak, so that a short focal length cannot be achieved. Therefore, it can be said that conditional expression (7) is a condition for shortening the focal length while maintaining good spherical aberration and image planeness. If the curvature radius is shortened beyond the upper limit of conditional expression (7), the spherical aberration will be worsened. Further, if the curvature radius becomes negative (that is, the power is negative) beyond the lower limit of conditional expression (7), it becomes difficult to secure the focal length.

It is more desirable to satisfy the following conditional expression (7a).
0.3 <f_all / r_2Fp <2.5… (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).

It is desirable that the most object side surface (positive power surface) of the second lens block satisfies the following conditional expression (8) from the middle band to the periphery.
0 <(φ_2Fp (0.5) + φ_2Fp (0.7) + φ_2Fp (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <2… (8)
However,
φ_2Fp (0.5): The power in the sagittal direction for the principal ray with the angle of view of 50% of the maximum angle of view of the surface closest to the object side of the second lens block
φ_2Fp (0.7): The power in the sagittal direction with respect to the principal ray with the field angle of 70% of the maximum field angle of the surface closest to the object side of the second lens block,
φ_2Fp (0.9): The power in the sagittal direction with respect to the chief ray at 90% of the maximum field angle of the surface closest to the object side of the second lens block,
φ_all (0.5): The power in the sagittal direction with respect to the chief ray of 50% of the maximum field angle of the entire system,
φ_all (0.7): The power in the sagittal direction with respect to the chief ray of 70% of the maximum field angle of the entire system,
φ_all (0.9): The power in the sagittal direction for the chief ray of 90% of the maximum field angle of the entire system,
It is.

  Conditional expression (8) defines the power from the middle band to the periphery of the most object side surface of the second lens block. The middle band affects the zonal of the on-axis ray to the marginal ray and affects the peripheral ray of the off-axis ray. If the power of this portion is strong, the image will be flared because it falls greatly under the spherical aberration from zonal to marginal. Further, regarding the off-axis light, if the power of this portion is too strong, the upper light is bent downward, so that there is a tendency of coma aberration. On the contrary, if the power of this part is weak, the periphery of the spherical aberration is over, and the off-axis upper ray part is flare. Therefore, conditional expression (8) can be said to be a condition for correcting spherical aberration and off-axis coma flare. If the power becomes negative beyond the lower limit of the conditional expression (8), the spherical aberration falls from the zonal to the marginal, and the off-axis ray becomes flare, and high performance cannot be maintained. If the power exceeds the upper limit of conditional expression (8) and the power becomes too strong, the spherical aberration will fall greatly from zonal to marginal, and the peripheral rays will become coma, and high performance cannot be maintained.

It is more desirable to satisfy the following conditional expression (8A).
0.2 <(φ_2Fp (0.5) + φ_2Fp (0.7) + φ_2Fp (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <1.5… (8A)
This conditional expression (8A) defines a more preferable condition range based on the same viewpoint as the conditional expression (8). Therefore, the above effect can be further enhanced preferably by satisfying conditional expression (8A).

  It is desirable that the surface closest to the image plane of the second lens block has negative power (positive and negative power arrangement). In the second lens block, the most object side surface has a positive power and the most image side surface has a negative power, so that the second lens block has a convex shape on the object side. . Therefore, by having the meniscus shape, the principal point position of the second lens block can be arranged on the image plane side, so that it becomes easier to ensure the back focus.

  It is desirable that the surface closest to the image plane of the second lens block has a positive power (positive power arrangement). By making the surface closest to the image plane of the second lens block a surface having a positive power, the second lens block can be a positive power lens block. Therefore, the angle of the chief ray with respect to the image plane can be made gentle, which is advantageous in ensuring telecentricity. However, if the power is too strong, negative distortion increases, and positive Petzval increases. If the positive power of the second lens block is appropriately set, it is possible to ensure good telecentricity while appropriately correcting distortion and the image plane. Furthermore, since the second lens block has two surfaces with positive power, it is possible to individually loosen the power of these two surfaces rather than forming only one surface with positive power. Therefore, the occurrence of various aberrations can be reduced, which is advantageous for a high-performance optical system.

  In the second lens block, it is desirable that the most object side surface has negative power and the most image side surface has positive power (negative positive power arrangement). By making the most image surface side surface of the second lens block a surface having a positive power, the angle of the principal ray to the image surface can be made gentle, which is advantageous in securing telecentricity. In particular, in an optical system with small pixels such as an imaging lens according to the present invention, it is necessary to increase the amount of light incident on the sensor. In particular, since the focal length is short, the difference in the amount of light between the axis and the periphery increases. I want to avoid that. When the incident angle on the sensor becomes steep, the amount of light is insufficient. Therefore, ensuring telecentricity is important. Further, if the second lens block has a negative positive configuration, it has a meniscus shape with respect to the image plane, which is advantageous for correcting astigmatism.

It is desirable that the most image side surface of the second lens block has a paraxial convex shape on the image side and satisfies the following conditional expression (9).
-4 <f_all / r_2Rp <0 (9)
However,
f_all: the paraxial focal length of the entire system,
r_2Rp: Paraxial radius of curvature of the positive power surface closest to the image plane of the second lens block,
It is.

  Conditional expression (9) defines the paraxial curvature of the positive power surface closest to the image plane. Since this surface is closest to the image surface side, it has a larger influence on off-axis light than on-axis light, and in particular has a large effect on image surface properties and distortion. If the curvature radius is strong, a large negative distortion occurs in the vicinity. Also, if the radius of curvature is loose, a short focal length cannot be achieved. Conditional expression (9) is a condition for achieving a short focal length while appropriately correcting distortion. When the radius of curvature decreases beyond the lower limit of conditional expression (9), negative distortion increases. If the upper limit of conditional expression (9) is exceeded, a concave surface is formed on the image plane side and the power becomes negative, so that a short focal length cannot be obtained in the entire system.

It is more desirable to satisfy the following conditional expression (9a).
-3.5 <f_all / r_2Rp <-0.8… (9a)
The conditional expression (9a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by the conditional expression (9). Therefore, the above effect can be further enhanced preferably by satisfying conditional expression (9a).

It is desirable that the most image surface side surface (positive power surface) of the second lens block satisfies the following conditional expression (10) from the middle band to the periphery.
0 <(φ_2Rp (0.5) + φ_2Rp (0.7) + φ_2Rp (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <2.0… (10)
However,
φ_2Rp (0.5): The power in the sagittal direction with respect to the principal ray with the field angle of 50% of the maximum field angle on the surface closest to the image plane of the second lens block,
φ_2Rp (0.7): Power in the sagittal direction with respect to the principal ray with a field angle of 50% of the maximum field angle of the surface closest to the image plane of the second lens block,
φ_2Rp (0.9): Power in the sagittal direction with respect to the chief ray with a field angle of 50% of the maximum field angle of the surface closest to the image plane of the second lens block,
φ_all (0.5): The power in the sagittal direction with respect to the chief ray of 50% of the maximum field angle of the entire system,
φ_all (0.7): The power in the sagittal direction with respect to the chief ray of 70% of the maximum field angle of the entire system,
φ_all (0.9): The power in the sagittal direction for the chief ray of 90% of the maximum field angle of the entire system,
It is.

  Conditional expression (10) defines the power from the middle band to the periphery of the surface closest to the image plane of the second lens block. In particular, peripheral rays mainly pass through this portion. By appropriately setting the power of this portion, the axial ray is not affected so much and the peripheral ray can be greatly affected. If the peripheral power becomes too strong, a large negative distortion occurs. If the peripheral power is too weak, the telecentric performance cannot be secured. Therefore, it can be said that the conditional expression (10) is a condition for ensuring good telecentricity while appropriately distorting. If the power becomes negative beyond the lower limit of conditional expression (10), it becomes difficult to ensure telecentricity. If the power exceeds the upper limit of conditional expression (10) and becomes too strong, negative distortion will increase.

It is more desirable to satisfy the following conditional expression (10A).
0.3 <(φ_2Rp (0.5) + φ_2Rp (0.7) + φ_2Rp (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <1.5… (10A)
Conditional expression (10A) defines a more preferable condition range based on the same viewpoint as the conditional expression (10). Therefore, the above effect can be further enhanced preferably by satisfying conditional expression (10A).

It is desirable that the most object side surface of the second lens block has a paraxial concave shape on the object side and satisfies the following conditional expression (11).
-6 <f_all / r_2Fn <0 (11)
However,
f_all: the paraxial focal length of the entire system,
r_2Fn: Paraxial radius of curvature of the most object side negative power surface of the second lens block,
It is.

  By constructing the most object side surface of the second lens block as a concave surface, this surface becomes a concentric surface with respect to the stop. That is, the shape is advantageous for astigmatism. In order to shorten the focal length and secure the back focus, if the power of the surface closest to the object is made negative, the imaging lens must be asymmetric. This makes it particularly difficult to correct the image plane. Therefore, this configuration is desirable because it is necessary to make astigmatism as small as possible. This surface also has negative power and generates negative Petzval. If the radius of curvature decreases and the power becomes too strong, the Petzval sum becomes too large and the image plane falls over. If the radius of curvature increases and the power decreases, the Petzval sum becomes too large and the image surface falls under. Therefore, it can be said that the conditional expression (11) is a condition for correcting the image plane while correcting astigmatism. If the lower limit of conditional expression (11) is exceeded and the radius of curvature becomes too small (that is, the curvature becomes too tight), the image plane will fall over. Also, if the upper limit of conditional expression (11) is exceeded, the image surface will fall to the underside because it will be convex on the object side and the power will be positive.

It is more desirable to satisfy the following conditional expression (11a).
-5 <f_all / r_2Fn <-3 (11a)
Conditional expression (11a) defines a more preferable condition range based on the above viewpoints, etc., among the condition ranges defined by conditional expression (11). Therefore, the above effect can be further enhanced preferably by satisfying conditional expression (11a).

It is desirable that the most object side surface (negative power surface) of the second lens block satisfies the following conditional expression (12) from the middle band to the periphery.
-4 <(φ_2Fn (0.5) + φ_2Fn (0.7) + φ_2Fn (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <0… (12)
However,
φ_2Fn (0.5): The power in the sagittal direction for the principal ray with the angle of view of 50% of the maximum angle of view of the surface closest to the object side of the second lens block
φ_2Fn (0.7): The power in the sagittal direction with respect to the principal ray with the field angle of 70% of the maximum field angle of the surface closest to the object side of the second lens block,
φ_2Fn (0.9): Power in the sagittal direction with respect to the principal ray with 90% of the maximum field angle of the surface closest to the object side of the second lens block,
φ_all (0.5): The power in the sagittal direction with respect to the chief ray of 50% of the maximum field angle of the entire system,
φ_all (0.7): The power in the sagittal direction with respect to the chief ray of 70% of the maximum field angle of the entire system,
φ_all (0.9): The power in the sagittal direction for the chief ray of 90% of the maximum field angle of the entire system,
It is.

  The power from the midband to the periphery of this surface affects especially off-axis rays. Since this surface has a concentric shape with respect to the stop, it is a shape advantageous for astigmatism. In addition, if the power from the middle band to the periphery of this surface becomes strong, it may cause coma flare on this surface. Further, if the power is weak in this portion, the effect of directing the off-axis rays outward on this surface becomes weak, which is disadvantageous for telecentricity. Therefore, it can be said that the conditional expression (12) is a condition for ensuring telecentricity while correcting astigmatism and coma flare. If the power exceeds the upper limit of conditional expression (12) and becomes positive, astigmatism deteriorates and telecentricity cannot be secured. Further, if the power is too strong exceeding the lower limit of the conditional expression (12), the coma flare becomes large and high performance cannot be secured.

It is more desirable to satisfy the following conditional expression (12A).
-2.5 <(φ_2Fn (0.5) + φ_2Fn (0.7) + φ_2Fn (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <-1.5… (12A)
This conditional expression (12A) defines a more preferable condition range based on the same viewpoint as the conditional expression (12). Therefore, the above effect can be further enhanced preferably by satisfying conditional expression (12A).

  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. In other words, 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 mobile 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, the signal is transmitted to another device through a cable or converted into an infrared signal. 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 lens blocks (including the first lens block C1 and the second lens block C2 in order from the object side), and the optical image IM is formed on the light receiving surface SS of the imaging element SR. It is the structure to form. 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 with the first lens block C1, the actuator can be downsized. 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 lens 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 lens block is preferably manufactured by a manufacturing method including: For example, in the imaging lens LN in which all the lenses are formed of lens 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 spacer member. Or it becomes possible to produce easily by providing the process which seals lens blocks, and the process of cut | disconnecting the integrated lens board | substrate and a spacer member with the lattice frame of the spacer member. 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 can be fabricated on the glass substrate simultaneously. 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 Lens block, a first parallel flat plate, a second parallel flat plate, and a second lens unit.

  FIG. 22 is a schematic sectional view showing an example of the manufacturing process of the imaging lens LN. The first lens 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 sides bonded to the other plane. And a lens portion 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 lens 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, and a plurality of second image sides bonded to the other plane. And a lens portion 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.

  The lattice-shaped spacer member B1 defines a distance between the lens blocks and keeps the lens block constant. The lattice-shaped spacer member B1 is a two-stage lattice, and each lens portion is disposed in a hole portion of the lattice. 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-lens imaging lenses are obtained. Of course, the lens blocks via the resin layer may be sealed without sealing the lens substrates. In this way, if the imaging lens is separated from a state where a plurality of first lens blocks C1 and second lens blocks C2 are assembled, it is not necessary to adjust and assemble the lens interval for each imaging lens, so mass production is possible. It becomes possible. 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 lens blocks, a lens block C1 and a second lens block C2.

  In the first to tenth embodiments, the lens blocks C1 and C2 are configured in the following order from the object side. In the first lens block C1, the first object side lens portion L11, the first lens substrate L12, and the first image side lens portion L13 are arranged in this order, and the planar portion (first object side lens portion) of the first lens substrate L12 is arranged. An aperture stop ST is disposed on a boundary surface between L11 and the first image side lens unit L13. In the second lens 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. If the nth (n = 1, 2) lens block from the object side to the image side is the nth lens block Cn, both surfaces of the nth lens block Cn (that is, all lens surfaces in contact with air) are not. It is a spherical surface, and the refractive index is different between the nth object side lens portion Ln1 and the nth lens substrate Ln2, and the refractive index is different between the nth lens substrate Ln2 and the nth image side lens portion Ln3.

  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 distance 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 aspherical 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: The amount of sag 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. Further, Table 1 shows the power (mm ⁻¹ ) of each lens block as lens block data. However, the paraxial power and the image heights Y ′ (0.5), Y ′ (0.7), Y ′ (0. The power at the position corresponding to 9) is shown. Table 2 shows values corresponding to the conditional expressions.

  FIGS. 11 to 20 are aberration diagrams of Examples 1 to 10 (EX1 to 10) (focused state at infinity). 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 * -14.021 0.050 1.57 34.0
2 (Aperture) ∞ 0.300 1.52 62.0
3 ∞ 0.300 1.51 56.0
4 * -3.544 0.347
5 * 1.128 0.400 1.51 56.0
6 ∞ 0.300 1.52 62.0
7 ∞ 0.060 1.57 34.0
8 * 3.848 0.530
9 ∞ 0.350 1.47 65.0
10 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = 0
A4 = -6.0838e-001
A6 = 7.2309e + 000
A8 = -5.3304e + 001
A10 = 1.2957e + 002
A12 = 2.1385e + 001
4th page
K = 0
A4 = -2.8174e-001
A6 = -7.6210e-001
A8 = 2.5996e + 000
A10 = -2.0762e + 000
A12 = -3.8000e + 000
5th page
K = 0
A4 = -1.0737e-001
A6 = -1.2223e-001
A8 = 2.1538e-001
A10 = -1.3100e-001
A12 = -8.1506e-002
8th page
K = 1.5133e + 001
A4 = 3.0461e-001
A6 = -4.1660e-001
A8 = 5.3692e-001
A10 = -2.9650e-001
A12 = -1.0927e-001

Various data
f 2.23
Fno. 2.88
ω 34.63
y'max 1.50
TL 3.33
BF 1.57

Example 2
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * -4.622 0.050 1.57 34.0
2 ∞ 0.600 1.52 62.0
3 (Aperture) ∞ 1.379 1.51 56.0
4 * -1.692 0.050
5 * 1.097 0.549 1.51 56.0
6 ∞ 0.300 1.52 62.0
7 ∞ 0.060 1.57 34.0
8 * 1.230 0.506
9 ∞ 0.350 1.47 65.0
10 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = 0
A4 = -1.1778e-001
A6 = 2.3470e-001
A8 = -4.2525e-001
A10 = 3.7649e-001
4th page
K = 0
A4 = -3.9604e-002
A6 = -2.8383e-001
A8 = 6.9308e-001
A10 = -7.2680e-001
A12 = 2.5357e-001
5th page
K = -4.5130e-001
A4 = -4.5150e-002
A6 = -6.8186e-002
A8 = 1.2514e-001
A10 = -1.0532e-001
A12 = 1.6948e-002
8th page
K = 3.6728e-001
A4 = 1.6389e-001
A6 = -2.7609e-001
A8 = 2.0617e-001
A10 = -1.4262e-001
A12 = -5.8064e-002

Various data
f 2.23
Fno. 2.88
ω 34.90
y'max 1.50
TL 4.53
BF 1.54

Example 3
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * -8.593 0.050 1.57 34.0
2 (Aperture) ∞ 0.300 1.52 62.0
3 ∞ 0.338 1.51 56.0
4 * -0.645 0.449
5 * -0.497 0.050 1.57 34.0
6 ∞ 0.300 1.52 62.0
7 ∞ 0.419 1.51 56.0
8 * -0.699 0.440
9 ∞ 0.350 1.47 65.0
10 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = -9.9332e + 001
A4 = -5.5745e-001
A6 = -8.6273e-001
A8 = 1.9231e-001
A10 = -1.8849e + 001
A12 = -2.0140e-009
A14 = -1.1152e-011
A16 = -2.0141e-018
4th page
K = 3.4749e-002
A4 = 3.4880e-001
A6 = 1.4473e-003
A8 = 1.5351e + 000
A10 = 3.1848e + 000
A12 = -2.6214e + 001
A14 = 7.0318e + 001
A16 = 7.4437e-019
5th page
K = -5.6668e-001
A4 = 9.5060e-001
A6 = 1.8347e + 000
A8 = -3.9402e + 000
A10 = 6.7916e + 000
A12 = -3.0224e + 000
A14 = 2.8062e + 000
A16 = -2.3940e-017
8th page
K = -6.6144e-001
A4 = 2.9232e-001
A6 = 2.2254e-001
A8 = 1.0153e-001
A10 = -1.5407e-001
A12 = 9.8295e-002
A14 = -3.9927e-002
A16 = -5.3944e-015

Various data
f 2.07
Fno. 2.88
ω 34.33
y'max 1.50
TL 3.38
BF 1.48

Example 4
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * -6.863 0.050 1.57 34.0
2 (Aperture) ∞ 0.300 1.52 62.0
3 ∞ 0.335 1.51 56.0
4 * -0.628 0.454
5 * -0.620 0.050 1.57 34.0
6 ∞ 0.600 1.52 62.0
7 ∞ 0.225 1.51 56.0
8 * -0.987 0.332
9 ∞ 0.350 1.47 65.0
10 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = 2.4079e + 002
A4 = -5.4274e-001
A6 = 8.5027e-001
A8 = -1.3449e + 001
A10 = 3.6984e + 001
A12 = 1.7650e-007
A14 = 3.8935e-007
4th page
K = -3.4187e-001
A4 = 2.9043e-001
A6 = -4.7953e-001
A8 = 1.3446e + 000
A10 = -2.8521e + 000
5th page
K = -1.1802e + 000
A4 = 9.3511e-001
A6 = -7.2357e-001
A8 = 3.0355e-001
A10 = 2.0402e-002
8th page
K = 0.0000e + 000
A4 = 4.6506e-001
A6 = 3.5604e-001
A8 = -4.9123e-001
A10 = 3.9468e-001

Various data
f 2.224
Fno. 2.88
ω 31.30
y'max 1.50
TL 3.38
BF 1.37

Example 5
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * -12.686 0.078 1.57 34.0
2 (Aperture) ∞ 0.300 1.52 62.0
3 ∞ 0.123 1.51 56.0
4 * -7.371 0.050
5 * 4.393 0.151 1.57 34.0
6 ∞ 0.300 1.52 62.0
7 ∞ 0.241 1.51 56.0
8 * -1.665 1.063
9 ∞ 0.350 1.47 65.0
10 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = -6.8586e + 002
A4 = -4.6422e-001
A6 = 2.6350e + 000
A8 = -1.8540e + 001
A10 = 4.5650e + 001
A12 = -8.6658e-009
A14 = -3.1903e-009
4th page
K = -9.5381e + 001
A4 = -7.4367e-001
A6 = 1.2986e + 000
A8 = 4.4559e-001
A10 = -4.9827e + 000
A12 = 8.6146e-001
A14 = 2.7348e-002
5th page
K = -9.1614e-001
A4 = -4.3535e-001
A6 = 1.5577e + 000
A8 = -1.8381e + 000
A10 = 4.8804e-001
A12 = 2.9047e-003
A14 = 4.0935e-001
8th page
K = 0
A4 = 1.3665e-001
A6 = -1.5607e-001
A8 = 4.4887e-001
A10 = -2.1918e-001

Various data
f 2.23
Fno. 2.88
ω 37.21
y'max 1.50
TL 3.34
BF 2.10

Example 6
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * -2.297 0.080 1.57 34.0
2 (Aperture) ∞ 0.300 1.52 62.0
3 ∞ 0.130 1.51 56.0
4 * -2.526 0.052
5 * 2.424 0.135 1.51 56.0
6 ∞ 0.300 1.52 62.0
7 ∞ 0.180 1.51 56.0
8 * -2.081 1.196
9 ∞ 0.350 1.47 65.0
10 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = -8.9470
A4 = -5.3954e-001
A6 = 2.8023
A8 = -1.9466e + 001
A10 = 4.6025e + 001
A12 = -1.5135e-008
A14 = -5.2664e-009
4th page
K = -8.8847
A4 = -7.9723e-001
A6 = 1.2824
A8 = 5.3032e-001
A10 = -5.8549
A12 = 9.9163e-001
A14 = 2.7348e-002
5th page
K = -6.0421
A4 = -4.3310e-001
A6 = 1.5332
A8 = -1.8693
A10 = 3.3175e-001
A12 = 2.0732e-002
A14 = 4.2711e-001
8th page
K = 0
A4 = 1.1654e-001
A6 = -1.4027e-001
A8 = 4.6566e-001
A10 = -4.0809e-001

Various data
f 2.23
Fno. 2.88
ω 39.09
y'max 1.50
TL 3.34
BF 2.23

Example 7
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * -54.142 0.050 1.84 23.0
2 ∞ 0.300 1.52 62.0
3 (Aperture) ∞ 0.500 1.51 56.0
4 * -3.879 0.512
5 * 1.186 0.489 1.51 56.0
6 ∞ 0.300 1.52 62.0
7 ∞ 0.060 1.57 34.0
8 * 4.665 0.417
9 ∞ 0.350 1.47 65.0
10 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = -1.8139e + 005
A4 = -1.4256e-001
A6 = 1.7007e-001
A8 = -1.0151e + 000
A10 = 2.5730e
4th page
K = 2.6232e
A4 = -2.2070e-001
A6 = -3.7169e-001
A8 = 1.3874
A10 = -9.7028e-001
A12 = -2.7604
5th page
K = -3.5636e-001
A4 = -6.6708e-002
A6 = -7.2517e-002
A8 = 1.2306e-001
A10 = -9.1537e-002
A12 = 1.6750e-002
8th page
K = 1.5168e + 001
A4 = 2.3937e-001
A6 = -2.7590e-001
A8 = 2.3136e-001
A10 = -9.1650e-002
A12 = -8.9284e-003

Various data
f 2.228
Fno. 2.880
ω 36.280
y'max 1.500
TL 3.666
BF 1.454

Example 8
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * -69.034 0.064 1.57 34.0
2 ∞ 0.316 1.84 23.0
3 (Aperture) ∞ 0.500 1.51 56.0
4 * -4.106 0.493
5 * 1.191 0.495 1.51 56.0
6 ∞ 0.314 1.52 62.0
7 ∞ 0.060 1.57 34.0
8 * 4.784 0.401
9 ∞ 0.350 1.47 65.0
10 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = 5.8908e + 002
A4 = -1.6216e-001
A6 = 9.4950e-002
A8 = -1.0965
A10 = 3.6320
4th page
K = 3.3206
A4 = -2.2223e-001
A6 = -3.7470e-001
A8 = 1.4044
A10 = -8.3572e-001
A12 = -2.7594
5th page
K = -3.4721e-001
A4 = -6.5293e-002
A6 = -7.2140e-002
A8 = 1.2307e-001
A10 = -9.0703e-002
A12 = 1.8384e-002
8th page
K = 1.5875e + 001
A4 = 2.4187e-001
A6 = -2.7472e-001
A8 = 2.3305e-001
A10 = -8.9091e-002
A12 = -7.8452e-003

Various data
f 2.228
Fno. 2.880
ω 36.125
y'max 1.500
TL 3.681
BF 1.439

Example 9
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * -64.499 0.050 1.92 20.8
2 ∞ 0.300 1.84 23.8
3 (Aperture) ∞ 0.500 1.51 56.0
4 * -4.003 0.499
5 * 1.180 0.480 1.51 56.0
6 ∞ 0.302 1.52 62.0
7 ∞ 0.060 1.57 34.0
8 * 4.695 0.426
9 ∞ 0.350 1.47 65.0
10 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = -1.3762e + 005
A4 = -1.4037e-001
A6 = 1.8592e-001
A8 = -1.0061
A10 = 2.3012
4th page
K = 6.4385
A4 = -2.2992e-001
A6 = -3.8217e-001
A8 = 1.3966
A10 = -8.5445e-001
A12 = -2.7774e + 000
5th page
K = -3.6555e-001
A4 = -6.9113e-002
A6 = -7.1518e-002
A8 = 1.2447e-001
A10 = -9.2161e-002
A12 = 1.2759e-002
8th page
K = 1.5910e + 001
A4 = 2.4199e-001
A6 = -2.7608e-001
A8 = 2.2871e-001
A10 = -9.4519e-002
A12 = -9.6867e-003

Various data
f 2.228
Fno. 2.880
ω 36.322
y'max 1.500
TL 3.655
BF 1.463

Example 10
Unit: mm
Surface data surface number rd nd vd
Object ∞ ∞
1 * -67.117 0.052 1.80 33.7
2 ∞ 0.302 1.71 53.4
3 (Aperture) ∞ 0.500 1.51 56.0
4 * -4.046 0.500
5 * 1.180 0.479 1.51 56.0
6 ∞ 0.302 1.52 62.0
7 ∞ 0.060 1.57 34.0
8 * 4.694 0.423
9 ∞ 0.350 1.47 65.0
10 ∞ 0.800
Image plane ∞

Aspheric data first surface
K = -1.2017e + 005
A4 = -1.4131e-001
A6 = 1.8229e-001
A8 = -1.0188
A10 = 2.2581
4th page
K = 6.0617
A4 = -2.2907e-001
A6 = -3.7996e-001
A8 = 1.4020
A10 = -8.4132e-001
A12 = -2.7774
5th page
K = -3.6593e-001
A4 = -6.9195e-002
A6 = -7.1541e-002
A8 = 1.2446e-001
A10 = -9.2161e-002
A12 = 1.2759e-002
8th page
K = 1.5917e + 001
A4 = 2.4212e-001
A6 = -2.7604e-001
A8 = 2.2872e-001
A10 = -9.4516e-002
A12 = -9.6844e-003

Various data
f 2.227
Fno. 2.880
ω 36.302
y'max 1.500
TL 3.655
BF 1.461

DU portable terminal LU imaging device LN imaging lens C1, C2 first and second lens block L11, L21 first and second object side lens unit L12, L22 first and second lens substrate L13, L23 first and second image Side lens ST Aperture stop (aperture)
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 (22)

When an optical element including 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 is referred to as a lens block, the lens substrate and the An imaging lens made of a material different from that of the lens part and including two lens blocks,
When the lens block is referred to as a first lens block and a second lens block in order from the object side, the most object side surface of the first lens block has a negative power, and the following conditional expressions (1) to (1): An imaging lens characterized by satisfying (3);
-2 <φ_1Fn / φ_all <0 (1)
| Δνd (s1-pt1) | <50… (2)
nd_s1> 1.4 (3)
However,
φ_1Fn: Paraxial power of the most object side surface of the first lens block,
φ_all: Paraxial power of the whole system
Δνd (s1-pt1): difference in Abbe number between the material of the lens part constituting the most object side surface of the first lens block and the material of the lens substrate of the first lens block,
nd_s1: The refractive index of the material of the lens part constituting the most object side surface of the first lens block,
It is. When an optical element including 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 is referred to as a lens block, the lens substrate and the An imaging lens made of a material different from that of the lens part and including two lens blocks,
When the lens block is called a first lens block and a second lens block in order from the object side, the most object side surface of the first lens block has negative power, and the following conditional expressions (2) to (2): An imaging lens characterized by satisfying (4);
-2 <(φ_1Fn (0.5) + φ_1Fn (0.7) + φ_1Fn (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <0… (4)
| Δνd (s1-pt1) | <50… (2)
nd_s1> 1.4 (3)
However,
φ_1Fn (0.5): The power in the sagittal direction with respect to the principal ray with the angle of view of 50% of the maximum angle of view of the surface closest to the object side of the first lens block
φ_1Fn (0.7): The power in the sagittal direction with respect to the principal ray with the field angle of 70% of the maximum field angle of the surface closest to the object side of the first lens block.
φ_1Fn (0.9): the power in the sagittal direction with respect to the chief ray of 90% of the maximum field angle on the most object side surface of the first lens block,
φ_all (0.5): The power in the sagittal direction with respect to the chief ray of 50% of the maximum field angle of the entire system,
φ_all (0.7): The power in the sagittal direction with respect to the chief ray of 70% of the maximum field angle of the entire system,
φ_all (0.9): The power in the sagittal direction for the chief ray of 90% of the maximum field angle of the entire system,
Δνd (s1-pt1): difference in Abbe number between the material of the lens part constituting the most object side surface of the first lens block and the material of the lens substrate of the first lens block,
nd_s1: The refractive index of the material of the lens part constituting the most object side surface of the first lens block,
It is. The imaging lens according to claim 1, wherein the following conditional expression (5) is satisfied:
0.2 <fb / f_all <2 (5)
However,
fb: Back focus of the entire system,
f_all: the paraxial focal length of the entire system,
It is. The most object-side surface of the first lens block has a paraxial concave shape on the object side, and satisfies the following conditional expression (6): The imaging lens according to item
-5 <f_all / r_1Fn <0 (6)
However,
f_all: the paraxial focal length of the entire system,
r_1Fn: Paraxial radius of curvature of the most object side surface of the first lens block,
It is.   The imaging lens according to any one of claims 1 to 4, wherein a stop is disposed on a plane portion of a lens substrate of the first lens block.   The imaging lens according to claim 1, wherein a surface closest to the object side of the second lens block has a positive power. The imaging lens according to claim 6, wherein a surface closest to the object side of the second lens block has a paraxial convex shape on the object side, and satisfies the following conditional expression (7):
0 <f_all / r_2Fp <4 (7)
However,
f_all: the paraxial focal length of the entire system,
r_2Fp: Paraxial radius of curvature of the positive power surface closest to the object side of the second lens block,
It is. The imaging lens according to claim 6, wherein a surface closest to the object side of the second lens block satisfies the following conditional expression (8) from the middle band to the periphery.
0 <(φ_2Fp (0.5) + φ_2Fp (0.7) + φ_2Fp (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <2… (8)
However,
φ_2Fp (0.5): The power in the sagittal direction for the principal ray with the angle of view of 50% of the maximum angle of view of the surface closest to the object side of the second lens block
φ_2Fp (0.7): The power in the sagittal direction with respect to the principal ray with the field angle of 70% of the maximum field angle of the surface closest to the object side of the second lens block,
φ_2Fp (0.9): The power in the sagittal direction with respect to the chief ray at 90% of the maximum field angle of the surface closest to the object side of the second lens block,
φ_all (0.5): The power in the sagittal direction with respect to the chief ray of 50% of the maximum field angle of the entire system,
φ_all (0.7): The power in the sagittal direction with respect to the chief ray of 70% of the maximum field angle of the entire system,
φ_all (0.9): The power in the sagittal direction for the chief ray of 90% of the maximum field angle of the entire system,
It is.   The imaging lens according to claim 6, wherein a surface closest to the image plane of the second lens block has a negative power.   The imaging lens according to claim 6, wherein a surface closest to the image plane of the second lens block has a positive power.   6. The second lens block according to claim 1, wherein the most object side surface has a negative power and the most image side surface has a positive power. Imaging lens. 12. The imaging lens according to claim 11, wherein a surface closest to the image plane of the second lens block has a paraxial convex shape on the image plane side, and satisfies the following conditional expression (9). ;
-4 <f_all / r_2Rp <0 (9)
However,
f_all: the paraxial focal length of the entire system,
r_2Rp: Paraxial radius of curvature of the positive power surface closest to the image plane of the second lens block,
It is. The imaging lens according to claim 11, wherein a surface closest to the image plane of the second lens block satisfies the following conditional expression (10) from the middle band to the periphery.
0 <(φ_2Rp (0.5) + φ_2Rp (0.7) + φ_2Rp (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <2.0… (10)
However,
φ_2Rp (0.5): The power in the sagittal direction with respect to the principal ray with the field angle of 50% of the maximum field angle on the surface closest to the image plane of the second lens block,
φ_2Rp (0.7): Power in the sagittal direction with respect to the principal ray with a field angle of 50% of the maximum field angle of the surface closest to the image plane of the second lens block,
φ_2Rp (0.9): Power in the sagittal direction with respect to the chief ray with a field angle of 50% of the maximum field angle of the surface closest to the image plane of the second lens block,
φ_all (0.5): The power in the sagittal direction with respect to the chief ray of 50% of the maximum field angle of the entire system,
φ_all (0.7): The power in the sagittal direction with respect to the chief ray of 70% of the maximum field angle of the entire system,
φ_all (0.9): The power in the sagittal direction for the chief ray of 90% of the maximum field angle of the entire system,
It is. The surface closest to the object side of the second lens block has a paraxial and concave shape on the object side, and satisfies the following conditional expression (11): The imaging lens according to the item;
-6 <f_all / r_2Fn <0 (11)
However,
f_all: the paraxial focal length of the entire system,
r_2Fn: Paraxial radius of curvature of the most object side negative power surface of the second lens block,
It is. The imaging lens according to any one of claims 11 to 14, wherein a surface closest to the object side of the second lens block satisfies the following conditional expression (12) from the middle band to the periphery.
-4 <(φ_2Fn (0.5) + φ_2Fn (0.7) + φ_2Fn (0.9)) / (φ_all (0.5) + φ_all (0.7) + φ_all (0.9)) <0… (12)
However,
φ_2Fn (0.5): The power in the sagittal direction for the principal ray with the angle of view of 50% of the maximum angle of view of the surface closest to the object side of the second lens block
φ_2Fn (0.7): The power in the sagittal direction with respect to the principal ray with the field angle of 70% of the maximum field angle of the surface closest to the object side of the second lens block,
φ_2Fn (0.9): Power in the sagittal direction with respect to the principal ray with 90% of the maximum field angle of the surface closest to the object side of the second lens block,
φ_all (0.5): The power in the sagittal direction with respect to the chief ray of 50% of the maximum field angle of the entire system,
φ_all (0.7): The power in the sagittal direction with respect to the chief ray of 70% of the maximum field angle of the entire system,
φ_all (0.9): The power in the sagittal direction for the chief ray of 90% of the maximum field angle of the entire 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 17, wherein the resin material is an energy curable resin material.   The imaging lens according to claim 17 or 18, comprising inorganic fine particles of 30 nanometers or less dispersed in the resin material.   A process comprising: sealing the lens substrates or the lens blocks with a lattice-shaped 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 claim 1, wherein the lens block is manufactured by a method.   An imaging lens according to any one of claims 1 to 20, 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 mobile terminal comprising the imaging device according to claim 21.

Images