JP2013182090A - Imaging lens, imaging apparatus, and portable terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small imaging lens that has a bright F value and is satisfactorily corrected in various aberrations.SOLUTION: An imaging lens 10 satisfies a conditional expression (1) -0.70<fg1r/|fg2|<-0.01, where fg1r is the focal distance of the lens closest to an image in a first lens group Gr1 (i.e., a fifth lens L15), and fg2 is the focal distance of a second lens group Gr2. The imaging lens can maintain a tele-photo type and restrict an increase in the entire length of the imaging lens 10, by being set within the upper limit of the conditional expression (1). The imaging lens prevents the negative focal distance of the fifth lens L15 closest to the image in the first lens group Gr1 from becoming too short by being set beyond the lower limit. Accordingly, occurrence of distortion aberration can be restricted.

Description

  The present invention relates to a small and bright imaging lens, an imaging device including the imaging lens, and a portable terminal including the imaging device, which are used for imaging elements such as a CCD image sensor and a CMOS image sensor.

  In recent years, with the widespread use of portable terminals equipped with an imaging device using a solid-state imaging device such as a CCD type image sensor or a CMOS type image sensor, imaging with a high number of pixels so that a higher quality image can be obtained. A device equipped with an imaging device using an element has been supplied to the market. Conventional image pickup devices having a high number of pixels have been accompanied by an increase in size, but in recent years, pixels have become increasingly thinner and image pickup devices have become smaller. An imaging lens used for a highly thinned image sensor is required to have a high resolving power in order to cope with a highly thinned pixel. On the other hand, the resolving power of the lens is limited by the F value, and a bright imaging lens is required because a bright lens having a small F value can obtain a high resolving power.

  On the other hand, in order to further reduce the size of the imaging apparatus, it is required to further reduce the overall length of the imaging lens. As such an imaging lens, there are an imaging lens having a lens block in which a lens portion is formed on the object side surface of the imaging device, and an imaging lens having a lens block in which a lens portion is formed on a parallel plate surface arranged in the vicinity of the imaging device. Proposed. By adopting such a configuration, high performance is achieved while suppressing an increase in size due to an increase in the number of lenses.

  As this type of imaging lens, an imaging lens having a first lens group composed of two lenses in order from the object side and a second lens group in which a lens portion is formed on the object side surface of the imaging element is disclosed ( For example, Patent Documents 1 and 2).

  In addition, an imaging lens having a first lens group including three lenses in order from the object side and a second lens group having a lens portion formed on the object side surface of the imaging element is disclosed (for example, Patent Document 3). ~ 6).

  However, in the imaging lenses described in Patent Documents 1 and 2, since the first lens group has two positive lenses, various aberrations including chromatic aberration are not sufficiently corrected. In addition, since it is about F2.8, a portable terminal whose pixels are becoming increasingly thin cannot cope with an F value that can provide high resolution.

  Moreover, since the imaging lens of the said patent documents 3-6 has a 1st lens group 3 lens structure, aberration correction is inadequate and it is suitable for the imaging lens corresponding to high pixel-izing. It's hard to say.

JP 2008-216807 A JP 2008-217039 A JP 2009-8956 A JP 2009-75466 A JP 2009-145597 A JP 2009-2109237 A

  The present invention has been made in view of such problems, and an object of the present invention is to provide a small imaging lens having a clear F value and excellent correction of various aberrations.

  Another object of the present invention is to obtain an imaging device that can obtain a high-quality captured image by providing the imaging lens as described above, and a portable terminal that includes the imaging device.

  Here, although it is a scale of a small imaging lens, the present invention aims at miniaturization at a level satisfying the following expression. By satisfying this range, the entire imaging apparatus can be reduced in size and weight.

L / 2Y <1.1 (7)
However,
L: distance on the optical axis from the lens surface closest to the object side to the image side focal point of the entire imaging lens system 2Y: diagonal length of the imaging surface of the imaging device (diagonal length of the rectangular effective pixel area of the imaging device)
Here, the image-side focal point refers to an image point when a parallel light beam parallel to the optical axis is incident on the imaging lens. In the case where a parallel plate such as a seal glass of the image pickup device package is disposed between the most image side surface of the image pickup lens and the image side focal position, the parallel plate portion is defined as the above-described L Shall be calculated. The present invention is suitable for an imaging lens that forms an image of a subject on an imaging surface of an imaging device (for example, a photoelectric conversion surface of a solid-state imaging device), but is not limited thereto.

In order to achieve the above object, an imaging lens according to the present invention is an imaging lens for forming a subject image on an imaging surface of an imaging device, and sequentially includes a first lens group and a second lens group from the object side. The first lens group has a positive refractive power as a whole and is composed of at least four or more lenses. The most image side lens in the first lens group is a negative lens, and the second lens. The group includes one lens block in which a lens portion is formed on at least one of the object side surface and the image side surface of the substrate that is a parallel plate, and satisfies the following conditional expression.
−0.70 <fg1r / | fg2 | <−0.01 (1)
However,
fg1r: focal length of the most image side lens in the first lens group fg2: focal length of the second lens group

  In the imaging lens, since the first lens group has a positive refractive power as a whole and is composed of at least four or more lenses, the number of lens surfaces is relatively large. Accordingly, it is possible to suppress the occurrence of aberrations on each surface to be small, to easily increase the diameter of the lens, and to provide an imaging lens having good performance corresponding to an image sensor with a large number of pixels that is highly thinned. It becomes possible. Further, by using a negative lens as the most image-side lens in the first lens group, a so-called telephoto type lens configuration can be obtained, and a configuration advantageous for downsizing the entire length of the imaging lens can be achieved.

  The second lens group is composed of one lens block in which a lens portion is formed on at least one surface of a parallel plate. Thereby, on the surface of the flat lens substrate, for example, a plurality of lens portions are formed by the replica method, and the back surface of the lens substrate is left as it is, or a plurality of lens portions are formed on the back surface of the lens substrate by the same method. If each lens unit is cut out, it becomes possible to obtain a large number of lens blocks that can be incorporated into the imaging lens of the present invention. In particular, when the back surface or the front surface of the lens substrate is left as it is, the high flatness of the lens substrate can be used, so that the error can be reduced as compared with forming a flat surface. The thickness of the lens substrate cannot be freely changed unlike lens molding, but the surface of the lens substrate may be further molded with a resin or the like to change the thickness of the substrate.

  When trying to obtain sufficient performance in recent years with larger apertures and higher pixels, the second lens group is further arranged behind the first lens group as described above, so that the peripheral performance can be further improved. Since excellent aberration correction can be performed, it is possible to realize further higher performance.

  By falling below the upper limit of conditional expression (1), the negative focal length of the most image-side lens in the first lens group does not become too large, so that the telephoto type can be maintained, and an increase in the overall length of the imaging lens can be suppressed. On the other hand, by exceeding the lower limit, the negative focal length of the most image-side lens in the first lens group does not become too small, so that the occurrence of distortion can be suppressed. In addition, since the back focus of the first lens group can be maintained appropriately, the arrangement of the second lens group is facilitated.

Further, conditional expression (1) is more preferably in the range of the following expression.
−0.70 <fg1r / | fg2 | <−0.02 (1) ′

In a specific aspect or viewpoint of the present invention, the imaging lens satisfies the following conditional expression.
0.01 <f / | fg2 | <0.70 (2)
However,
f: Focal length of the entire imaging lens system fg2: Focal length of the second lens group

  By falling below the upper limit of the conditional expression (2), the focal length of the second lens group does not become too small, so that the occurrence of aberrations in the second lens group can be suppressed. On the other hand, by exceeding the lower limit, the focal length of the second lens group does not become too large, and aberration correction can be sufficiently performed.

Further, conditional expression (2) is more preferably in the range of the following expression.
0.04 <f / | fg2 | <0.60 (2) ′

In another aspect of the present invention, the following conditional expression is satisfied.
0.09 <dg2l / f <0.30 (3)
However,
dg2l: Distance on the optical axis from the object side surface apex of the lens unit formed on the most object side of the second lens group or the object side surface of the substrate (when there is no lens unit on the object side) to the imaging surface of the imaging lens f: Focal length of the entire imaging lens system

  By falling below the upper limit of conditional expression (3), the distance between the second lens group and the imaging surface is not too far away, so that the increase in the overall length of the imaging lens can be suppressed. On the other hand, by exceeding the lower limit, the second lens group does not approach the imaging surface too much, so the aberration correction effect in the second lens group is increased.

Further, conditional expression (3) is more preferably in the range of the following expression.
0.11 <dg2l / f <0.27 (3) ′

In still another aspect of the present invention, the following conditional expression is satisfied.
0.5 <Σdg2 / dMing1 ≦ 1.0 (4)
However,
Σdg2: Total thickness on the optical axis of the second lens group dMing1: Minimum thickness on the optical axis of the lenses constituting the first lens group

  Conditional expression (4) is a conditional expression for realizing downsizing of the imaging lens by making the total thickness of the second lens group thinner than the lenses constituting the first lens group. By falling below the upper limit of conditional expression (4), the thickness of the second lens group can be made the thinnest in the imaging lens, so that the increase in the overall length of the imaging lens can be suppressed. On the other hand, by exceeding the lower limit, the second lens group does not become too thin, so it is possible to suppress shape changes such as warping of the lens block.

Further, conditional expression (4) is more preferably in the range of the following expression.
0.6 <Σdg2 / dMing1 ≦ 1.0 (4) ′

In still another aspect of the present invention, the following conditional expression is satisfied.
0.10 <THg2l / THg2b <0.80 (5)
However,
THg2l: total thickness on the optical axis of the lens portion of the second lens group THg2b: thickness on the optical axis of the substrate of the second lens group Here, the total thickness on the optical axis of the lens portion is the substrate When the lens portion is formed on both the object side surface and the image side surface, the total thickness of both the lens portions is meant. When the lens portion is formed on one of the object side surface and the image side surface of the substrate, this It means the total thickness of one lens part.

  By falling below the upper limit of conditional expression (5), the lens portion does not become too thick as compared with the thickness of the substrate, and warpage of the substrate after molding can be suppressed. On the other hand, by exceeding the lower limit, it is possible to appropriately secure the thickness of the lens portion and to set the refractive power of the second lens group strongly, which is advantageous for aberration correction and shortening of the optical total length. Become.

Further, conditional expression (5) is more preferably in the range of the following expression.
0.20 <THg2l / THg2b <0.70 (5) '

  In still another aspect of the invention, the lens portion of the second lens group has an aspherical shape. Since the lens portion of the second lens group has an aspherical shape, various aberrations can be favorably corrected up to the periphery of the screen.

  In still another aspect of the present invention, the first lens group includes two positive lenses and two negative lenses. In this case, correction of chromatic aberration and reduction of Petzval sum are facilitated, and an imaging lens that secures good imaging performance up to the periphery of the screen can be obtained.

  In still another aspect of the invention, the second lens group has negative refractive power. The second lens group can be regarded as an image side lens group of the imaging lens together with the negative lens on the most image side of the first lens group, and since the negative refractive power of the image side lens group can be strongly arranged, the entire length of the imaging lens Can be shortened.

In still another aspect of the invention, the lens portion of the second lens group includes a material that satisfies the following conditional expression.
28 <νg2l <60 (6)
However,
νg2l: Abbe number of the material of the lens portion of the second lens group

  Conditional expression (6) is a conditional expression for satisfactorily correcting chromatic aberration by appropriately setting the Abbe number of the lens portion of the second lens group. Exceeding the lower limit of conditional expression (6) can suppress overcorrection. On the other hand, when the value is below the upper limit, it is possible to prevent the correction from being insufficient, and the lens portion can be formed of an easily available material, which leads to cost reduction of the imaging lens.

  In still another aspect of the present invention, in the lens block constituting the second lens group, a lens portion is formed only on the object side surface. By forming the lens portion only on the object side surface of the lens block in this way, the image side surface can be made flat and the clearance from the sensor surface can be easily obtained, so that the difficulty of the assembly process can be reduced. In this case, the second lens group can be formed on the sensor surface.

  In still another aspect of the present invention, in the lens block constituting the second lens group, a lens portion is formed only on the image side surface. By forming the lens portion only on the image side surface of the lens block in this way, the object side surface of the second lens group can be made flat, and it becomes easier to secure the clearance with the first lens group, so the second side. The lens group can be moved toward the object side. As a result, the aberration correction effect of the lens portion of the second lens group can be enhanced.

  In still another aspect of the present invention, in the lens block constituting the second lens group, lens portions are formed on both the object side and the image side. In this way, by forming lens portions on both the object side and the image side of the lens block, aberration correction can be performed on two surfaces, so that higher performance can be achieved.

  In still another aspect of the present invention, at least one of the object side surface and the image side surface of the substrate of the second lens group has a function of cutting infrared light. By providing a function of cutting infrared light on at least one surface of the substrate, it is not necessary to arrange an infrared light cut filter, so that the back focus of the imaging lens can be shortened and the imaging lens can be downsized.

  In still another aspect of the present invention, the lens further includes a lens having substantially no power.

  An imaging apparatus according to the present invention includes the imaging lens described above and an imaging element that photoelectrically converts an image formed on an imaging surface by the imaging lens. By using the imaging lens of the present invention, it is possible to obtain an imaging device that is small and bright, that various aberrations are corrected well, and that a high-quality captured image can be obtained.

  The portable terminal which concerns on this invention is provided with the above-mentioned imaging device. That is, the portable terminal according to the present invention includes an imaging device that can obtain a high-quality captured image as described above.

It is a figure explaining an imaging device provided with the imaging lens of one embodiment of the present invention. It is a block diagram explaining a portable communication terminal provided with the imaging device of FIG. (A) And (B) is a perspective view of the surface side and back surface side of a portable communication terminal, respectively. 2 is a cross-sectional view of an imaging lens of Example 1. FIG. (A)-(E) are the aberrational figures of the imaging lens of Example 1. FIG. 6 is a cross-sectional view of an imaging lens of Example 2. FIG. (A)-(E) are the aberrational figures of the imaging lens of Example 2. FIG. 6 is a cross-sectional view of an imaging lens of Example 3. FIG. FIGS. 7A to 7E are aberration diagrams of the imaging lens of Example 3. FIGS. 6 is a cross-sectional view of an imaging lens of Example 4. FIG. (A)-(E) are the aberrational figures of the imaging lens of Example 4. FIGS.

  Hereinafter, with reference to FIG. 1 etc., one Embodiment of the imaging lens, imaging device, etc. which concern on this invention is described. The imaging lens 10 illustrated in FIG. 1 has the same configuration as the imaging lens 10 of Example 1 described later.

  FIG. 1 is a cross-sectional view illustrating a camera module including an imaging lens according to an embodiment of the present invention.

  The camera module 50 includes an imaging lens 10 that forms a subject image, an imaging device 51 that detects a subject image formed by the imaging lens 10, and a wiring board 52 that holds the imaging device 51 from behind and has wiring and the like. And a lens barrel portion 54 having an opening OP for holding the imaging lens 10 and the like and allowing a light beam from the object side to enter. The imaging lens 10 has a function of forming a subject image on the image plane or the imaging plane (projected plane) I of the imaging element 51. The camera module 50 is used by being incorporated in an imaging device to be described later.

  Although details will be described later, the imaging lens 10 includes a first lens group Gr1 and a first lens group Gr2 in order from the object side. The first lens group Gr1 includes an aperture stop S, a first lens L11, and the like. A second lens L12, a third lens L13, a fourth lens L14, and a fifth lens L15 are provided. The second lens group Gr2 includes a lens block LB in which a lens portion L21 is formed on at least one of the object side surface and the image side surface of the substrate F.

The imaging lens 10 is small in size, and as a measure, the imaging lens 10 aims at miniaturization at a level that satisfies the following expression (7).
L / 2Y <1.1 (7)
Here, L is the distance on the optical axis OA from the most object side surface of the entire imaging lens 10 system to the image side focal point. 2Y is the diagonal length of the imaging surface of the imaging device 51 (the diagonal length of the rectangular effective pixel region of the imaging device 51). The image side focal point refers to an image point when a parallel light beam parallel to the optical axis OA is incident on the imaging lens 10. By satisfying this range, the entire camera module 50 can be reduced in size and weight.

  When a parallel flat plate such as a seal glass of the image pickup device package is disposed between the most image side surface of the imaging lens 10 and the image side focal position, the parallel flat plate portion is defined as an air conversion distance. The value of L is calculated.

  The image sensor 51 is a sensor chip made of a solid-state image sensor. The photoelectric conversion unit 51a of the image sensor 51 is composed of a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), photoelectrically converts incident light for each RGB, and outputs an analog signal thereof. The surface of the photoelectric conversion unit 51a as the light receiving unit is an imaging surface (projected surface) I.

  The wiring board 52 has a role of aligning and fixing the image sensor 51 to other members (for example, the lens barrel portion 54). The wiring board 52 can be supplied with a voltage and a signal for driving the imaging device 51 from an external circuit, and can output a detection signal to the external circuit.

  On the imaging lens 10 side of the imaging element 51, a substrate F is disposed and fixed so as to cover the imaging element 51 and the like by a holder member (not shown).

  The lens barrel 54 houses and holds the imaging lens 10. The lens barrel portion 54 moves any one or more of the lenses from the first lens 1L1 to the fifth lens L15 constituting the first lens group Gr1 of the imaging lens 10 along the optical axis OA. The driving mechanism 55a (see FIG. 2) for enabling the focusing operation of the imaging lens 10 is provided. The drive mechanism 55a can reciprocate any one of the lenses from the first lens L11 to the fifth lens L15 along the optical axis OA. The drive mechanism 55a includes, for example, a voice coil motor and a guide. The drive mechanism 55a can be composed of a stepping motor, a tangent screw type power transmission member, and a slide guide.

  Next, an example of a mobile phone or other mobile communication terminal 300 equipped with the camera module 50 illustrated in FIG. 1 will be described with reference to FIGS. 2, 3 (A), and 3 (B).

  The mobile communication terminal 300 is a smartphone-type mobile communication terminal, and an image capturing apparatus 100 having a camera module 50 and a control unit (CPU: Central Processing Unit) that centrally controls each unit and executes a program corresponding to each process. ) 310, a display operation unit 320 that is a touch panel that displays data related to communication, captured video, and the like and accepts user operations, an operation unit 330 including a power switch, and an external server via the antenna 341. A wireless communication unit 340 for realizing various information communication between the mobile communication terminal 300 and a storage unit (ROM) storing necessary data such as a system program, various processing programs, and a terminal ID (identification) of the mobile communication terminal 300 : Read Only Memory) 360 and various processing programs and data executed by the control unit 310. Data, processing data, or temporary memory used by the imaging device 100 as a work area for temporarily storing the imaging data and the like: and a (RAM Random Access Memory) 370.

  In addition to the camera module 50 described above, the imaging apparatus 100 includes a control unit 103, an optical system driving unit 105, an imaging element driving unit 107, an image memory 108, and the like.

  The control unit 103 controls each unit of the imaging device 100. The control unit 103 includes a CPU, a RAM, a ROM, and the like, and executes various processes in cooperation with various programs read from the ROM and expanded in the RAM. Note that the control unit 310 is communicably connected to the control unit 104 of the imaging apparatus 100, and can exchange control signals and image data.

  The optical system driving unit 105 controls the state of the imaging lens 10 by operating the driving mechanism 55 a of the imaging lens 10 when performing focusing, exposure, and the like under the control of the control unit 103. The optical system driving unit 105 operates the driving mechanism 55a to appropriately move a specific lens in the imaging lens 10 along the optical axis OA, thereby causing the imaging lens 10 to perform a focusing operation.

  The image sensor drive unit 107 controls the operation of the image sensor 51 when performing exposure or the like under the control of the control unit 103. Specifically, the image sensor drive unit 107 controls the image sensor 51 by scanning and driving based on the timing signal. Further, the image sensor driving unit 107 converts the detection signal output from the image sensor 51 or an analog signal as a photoelectric conversion signal into digital image data. Further, the image sensor driving unit 107 can perform various image processing such as distortion correction, color correction, and compression on the image signal detected by the image sensor 51.

  The image memory 108 receives the digitized image signal from the image sensor driving unit 107 and stores it as readable and writable image data.

  Here, the photographing operation of the mobile communication terminal 300 including the imaging device 100 will be described. When the camera mode in which the mobile communication terminal 300 is operated as a camera is set, subject monitoring (through image display) and image shooting execution are performed. In monitoring, an image of a subject obtained through the imaging lens 10 is formed on the imaging surface I (see FIG. 1) of the imaging element 51. The image sensor 51 is scanned and driven by the image sensor driving unit 107, and outputs an analog signal for one screen as a photoelectric conversion output corresponding to a light image formed at regular intervals.

  This analog signal is converted into digital data after gain adjustment is appropriately performed for each primary color component of RGB in a circuit attached to the image sensor 51. The digital data is subjected to color process processing including pixel interpolation processing and Y correction processing, and a digital luminance signal Y and color difference signals Cb, Cr (image data) are generated and stored in the image memory 108. The stored digital data is periodically read out from the image memory 108 to generate a video signal thereof, and is output to the display operation unit 320 via the control unit 103 and the control unit 310.

  The display operation unit 320 functions as an electronic viewfinder in monitoring and displays captured images in real time. In this state, focusing, exposure, and the like of the imaging lens 10 are set by driving the optical system driving unit 105 based on operation input performed by the user via the display operation unit 320 as needed.

  In such a monitoring state, when the user appropriately operates the display operation unit 320, still image data is captured. One frame of image data stored in the image memory 108 is read in accordance with the operation content of the display operation unit 320, and compressed by the image sensor driving unit 107. The compressed image data is recorded in the RAM 370, for example, via the control unit 103 and the control unit 310.

  The above-described imaging apparatus 100 is an example of an imaging apparatus suitable for the present invention, and the present invention is not limited to this.

  That is, the image pickup apparatus equipped with the camera module 50 or the image pickup lens 10 is not limited to the one built in the smartphone type mobile communication terminal 300, but is built into a mobile phone, a PHS (Personal Handyphone System), or the like. Alternatively, it may be incorporated in a PDA (Personal Digital Assistant), a tablet personal computer, a mobile personal computer, a digital still camera, a video camera, or the like.

  Hereinafter, returning to FIG. 1, the imaging lens 10 according to an embodiment of the present invention will be described in detail. The imaging lens 10 shown in FIG. 1 forms a subject image on an imaging surface (projected surface) I of an image sensor 51. The imaging lens 10 includes a first lens group Gr1 and a first lens group Gr2 in order from the object side. The former first lens group Gr1 has a positive refractive power as a whole and is composed of at least four or more lenses. Specifically, the first lens group Gr1 includes, in order from the object side, an aperture stop S, a first lens L11, a second lens L12, a third lens L13, a fourth lens L14, and a fifth lens L15. It consists of. On the other hand, the second lens group Gr2 has a negative refractive power as a whole and includes a single lens block LB. The lens block LB includes a substrate F and a lens portion L21. The lens portion L21 is attached to and integrated with the object side surface FS1 of the substrate F which is a parallel plate. By arranging the second lens group Gr2 further behind the first lens group Gr1, it becomes possible to perform better aberration correction with respect to the peripheral performance. Sufficient performance can be ensured while meeting the requirements.

  In the specific first lens group Gr1, the first lens L11 has a positive refractive power, the second lens L12 has a negative refractive power, and the third lens L13 has a positive, negative, or zero. The fourth lens L14 has a positive refractive power, and the fifth lens L15 has a negative refractive power. That is, the fifth lens L15 which is the most image side lens in the first lens group Gr1 is a negative lens. The first lens group Gr1 includes two positive lenses and two negative lenses. As described above, by using the fifth lens L15 closest to the image side of the first lens group Gr1 as a negative lens, a so-called telephoto type lens configuration is obtained, which is advantageous for reducing the overall length of the imaging lens 10. Yes. Further, the first lens group Gr1 includes two positive first and fourth lenses L11 and L14 and two negative second and fifth lenses L12 and L15, thereby correcting chromatic aberration and Petzval sum. Can be easily reduced, and it is easy to ensure good imaging performance up to the periphery of the screen.

  The aperture stop S is disposed on the object side of the first lens L11, but may be disposed between the first lens L11 and the second lens L12.

  Since the second lens group Gr2 has a negative refractive power, it can be regarded as the negative lens group on the image side of the imaging lens 10 together with the negative fifth lens L15 on the most image side of the first lens group Gr1. That is, in the imaging lens 10, since the negative refractive power of the image side lens group including the fifth lens L15 and the second lens group Gr2 of the first lens group Gr1 can be strongly arranged, the overall length of the imaging lens 10 is shortened. Can be achieved. In addition, since the lens portion L21 of the second lens group Gr2 has an aspheric shape, various aberrations can be favorably corrected up to the peripheral portion of the screen.

  The lens block LB of the second lens group Gr2 is cut out from, for example, a wafer lens. The wafer lens is obtained by forming a plurality of resin lens portions L21 on the surface of a flat lens substrate, for example, by the replica method, and cutting out each lens portion L21 while leaving the back surface of the lens substrate as it is. . As shown in the figure, by forming the lens portion L21 only on the object side surface FS1 of the substrate F, the image side surface FS2 can be made flat, and the clearance from the imaging surface (sensor surface) I can be easily obtained, so that the assembly process is difficult. The degree can be lowered. The lens portion can be formed only on the image side surface FS2 of the substrate F. In this case, the object side surface of the second lens group Gr2, that is, the object side surface FS1 is a flat surface, and it is easy to secure a clearance with the first lens group Gr1. Therefore, the second lens group Gr2 can be moved closer to the object side, and the aberration correction effect by the lens portion L21 can be enhanced.

  In the obtained lens block LB, a filter layer 18 having a function of cutting infrared light is formed on the image side surface FS2 of the substrate F, for example. By providing the filter layer 18 on the substrate F, it is not necessary to separately arrange an infrared light cut filter, so that the back focus of the imaging lens 10 can be shortened and the imaging lens 10 can be downsized. When the lens block LB is cut out from the wafer lens, the filter layer is formed in advance on one side of the lens substrate before forming the plurality of lens portions on the lens substrate. The lens block LB provided with 18 can be obtained.

The imaging lens 10 described above has the conditional expression (1).
−0.70 <fg1r / | fg2 | <−0.01 (1)
Satisfied. Here, fg1r is the focal length of the most image side lens (specifically, the fifth lens L15) in the first lens group Gr1, and fg2 is the focal length of the second lens group Gr2.

  By making the value lower than the upper limit of conditional expression (1), the negative focal length of the fifth lens L15 closest to the image side in the first lens group Gr1 does not become too large, so that the telephoto type can be maintained, and the imaging lens Increase in size of 10 full lengths can be suppressed. On the other hand, by exceeding the lower limit, the negative focal length of the fifth lens L15 closest to the image side in the first lens group Gr1 does not become too small, so that the occurrence of distortion can be suppressed. Further, since the back focus of the first lens group Gr1 can be appropriately maintained, the arrangement of the second lens group Gr2 is facilitated.

The imaging lens 10 is more preferably the following conditional expression (1) ′:
−0.70 <fg1r / | fg2 | <−0.02 (1) ′
Meet.

The imaging lens 10 described above has the conditional expression (2).
0.01 <f / | fg2 | <0.70 (2)
Satisfied. Here, f is the focal length of the entire imaging lens 10, and fg2 is the focal length of the second lens group Gr2.

The imaging lens 10 is more preferably the following conditional expression (2) ′
0.04 <f / | fg2 | <0.60 (2) ′
Meet.

The imaging lens 10 described above has the conditional expression (3).
0.09 <dg2l / f <0.30 (3)
Satisfied. Here, dg2l is a distance on the optical axis OA from the object side surface vertex of the lens unit 21 formed on the most object side of the second lens group Gr2 or the object side surface of the substrate F to the imaging surface I. As shown in the figure, when the lens unit 21 is on the object side of the substrate F, the object side vertex of the lens unit 21 to the imaging surface I is considered, but when the lens unit 21 is not on the object side of the substrate F, Consider from the object side surface of the substrate F to the imaging surface I.

The imaging lens 10 is more preferably the following conditional expression (3) ′
0.11 <dg2l / f <0.27 (3) ′
Meet.

The imaging lens 10 described above has the conditional expression (4).
0.5 <Σdg2 / dMing1 ≦ 1.0 (4)
Satisfied. However, Σdg2 is the total thickness on the optical axis OA of the second lens group Gr2, and dMing1 is the minimum value of the thickness on the optical axis OA of the lenses constituting the first lens group Gr1.

The imaging lens 10 is more preferably the following conditional expression (4) ′:
0.6 <Σdg2 / dMing1 ≦ 1.0 (4) ′
Meet.

The imaging lens 10 described above has conditional expression (5).
0.10 <THg2l / THg2b <0.80 (5)
Satisfied. However, THg2l is the total thickness on the optical axis OA of the lens portion L21 of the second lens group Gr2, and THg2b is the thickness on the optical axis OA of the substrate F of the second lens group Gr2.

The imaging lens 10 is more preferably the following conditional expression (5) ′:
0.20 <THg2l / THg2b <0.70 (5) '
Meet.

The imaging lens 10 described above has the conditional expression (6).
28 <νg2l <60 (6)
Satisfied. Here, νg2l is the Abbe number of the material of the lens portion L21 of the second lens group Gr2.

〔Example〕
Examples of the imaging lens of the present invention will be shown below. Symbols used in each example are as follows.
f: Focal length of the entire imaging lens system fB: Back focus F: F number 2Y: Diagonal length of the imaging surface of the imaging device ENTP: Entrance pupil position (distance from the first surface to the entrance pupil position)
EXTP: exit pupil position (distance from imaging plane to exit pupil position)
H1: Front principal point position (distance from first surface to front principal point position)
H2: Rear principal point position (distance from the final surface to the rear principal point position)
R: radius of curvature D: spacing between axial upper surfaces Nd: refractive index νd of lens material with respect to d-line: Abbe number of lens material

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

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

  Hereinafter, specific examples of the imaging lens of the present invention will be described.

[Example 1]
The overall specifications of Example 1 are shown below.
f = 3.6mm
fB = 0.37mm
F = 2.26
2Y = 5.712mm
ENTP = 0mm
EXTP = -1.97mm
H1 = -1.95mm
H2 = −3.23mm

Table 1 shows lens data of Example 1.
[Table 1]
Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 (Aperture) ∞ -0.18 0.80
2 * 1.464 0.45 1.54470 56.2 0.82
3 * -67.640 0.09 0.83
4 * 27.713 0.20 1.63470 23.9 0.84
5 * 2.415 0.35 0.86
6 * 8.677 0.46 1.54470 56.2 0.97
7 * ∞ 0.60 1.11
8 * -7.717 0.49 1.54470 56.2 1.48
9 * -1.119 0.42 1.68
10 * -1.817 0.29 1.54470 56.2 2.41
11 * 2.451 0.35 2.55
12 * -10.867 0.07 1.61000 29.0 2.81
13 ∞ 0.11 1.51630 64.1 3.00
14 ∞ 3.00
In the following (including the lens data in the table), a power of 10 (for example, 2.5 × 10 ⁻⁰² ) is expressed using E (for example, 2.5E-02).

Table 2 below shows the aspheric coefficients of the lens surfaces of the imaging lens of Example 1.
[Table 2]
Second side
K = 0.10181E + 00, A4 = 0.45557E-02, A6 = 0.70217E-03, A8 = 0.30064E-02,
A10 = 0.41367E-01, A12 = -0.19883E-01, A14 = -0.38951E-01
Third side
K = -0.29789E + 02, A4 = 0.46943E-01, A6 = 0.22847E-01, A8 = 0.26880E-02,
A10 = -0.87261E-01, A12 = -0.44278E-01, A14 = 0.35897E-01
4th page
K = -0.41568E + 02, A4 = 0.15532E-01, A6 = 0.11655E + 00, A8 = -0.12025E + 00,
A10 = -0.10027E + 00, A12 = -0.15320E-01, A14 = 0.98167E-01
5th page
K = -0.16892E + 02, A4 = 0.11961E + 00, A6 = 0.30583E-01, A8 = -0.31507E-01,
A10 = 0.15542E-01, A12 = -0.69388E-01, A14 = 0.12262E + 00
6th page
K = 0.13142E + 02, A4 = -0.12796E + 00, A6 = 0.23281E-01, A8 = -0.44115E-01,
A10 = 0.34599E-01, A12 = 0.79014E-01, A14 = -0.36018E-01
7th page
K = 0.00000E + 00, A4 = -0.84074E-01, A6 = -0.21335E-01, A8 = 0.67291E-02,
A10 = -0.60574E-03, A12 = 0.66307E-03, A14 = 0.15306E-01
8th page
K = 0.25355E + 02, A4 = -0.60626E-01, A6 = 0.33906E-01, A8 = -0.14287E-01,
A10 = -0.61215E-02, A12 = 0.85124E-03, A14 = 0.12607E-02
9th page
K = -0.31583E + 01, A4 = -0.71606E-01, A6 = 0.61314E-01, A8 = -0.10183E-01,
A10 = -0.11619E-02, A12 = 0.10669E-03, A14 = 0.22439E-04
10th page
K = -0.43711E + 01, A4 = -0.18748E-01, A6 = 0.85451E-02, A8 = 0.11461E-03,
A10 = -0.22548E-03, A12 = 0.13339E-04, A14 = 0.69696E-06
11th page
K = -0.24743E + 02, A4 = -0.37168E-01, A6 = 0.11892E-01, A8 = -0.29024E-02,
A10 = 0.23746E-03, A12 = -0.27455E-05, A14 = 0.20637E-06
12th page
K = 0.73239E-01, A4 = 0.20618E-01, A6 = -0.28926E-02, A8 = 0.79852E-04,
A10 = 0.11166E-04, A12 = 0.30193E-06, A14 = -0.10419E-06

The single lens data of Example 1 is shown in Table 3 below.
[Table 3]
Lens Start surface Focal length (mm)
1 2 2.636
2 4 -4.181
3 6 15.931
4 8 2.343
5 10 -1.871
6 12 -17.670

  FIG. 4 is a cross-sectional view of the imaging lens 11 (10) of the first embodiment. The imaging lens 11 (10) includes a first lens group Gr1 and a first lens group Gr2 in order from the object side. The first lens group Gr1 has a positive refractive power as a whole, and in order from the object side, the aperture stop S, the first lens L11, the second lens L12, the third lens L13, and the fourth lens L14. And a fifth lens L15. The first to fifth lenses L11 to L15 are made of resin. The first lens L11 is a biconvex aspherical lens having positive refractive power. The second lens L12 is a meniscus both aspherical lens having negative refractive power and convex toward the object side. The third lens L13 is a bi-aspheric lens having a slightly positive refractive power and convex toward the object side. The fourth lens L14 is a meniscus aspherical lens having positive refractive power and convex toward the image side. The fifth lens L15 is a biconcave aspherical lens having negative refractive power. The first lens group Gr2 has a negative refractive power as a whole, and is a lens block in which the lens portion L21 and the substrate F are joined in order from the object side. The lens portion L21 is an aspheric lens having negative refractive power and concave on the object side. The substrate F is a parallel plate, and one of the object side surface and the image side surface has a function of cutting infrared light or an optical low-pass filter. In addition, the board | substrate F may serve as the sealing glass of the image pick-up element 51, etc.

  5A to 5C show aberration diagrams (spherical aberration, astigmatism, and distortion aberration) of the imaging lens 11 of Example 1. FIG. 5D and 5E show the meridional coma aberration of the imaging lens 11 of Example 1. FIG. In the aberration diagrams and the subsequent aberration diagrams, in the spherical aberration diagram, the solid line represents the d line and the dotted line represents the g line, and in the astigmatism diagram, the solid line represents the sagittal image plane and the dotted line represents the meridional. It shall represent the image plane.

[Example 2]
The overall specifications of Example 2 are shown below.
f = 3.77 mm
fB = 0.5mm
F = 2.8
2Y = 5.744mm
ENTP = 0.34mm
EXTP = −2.03mm
H1 = -1.49mm
H2 = -3.27mm

Table 4 shows lens data of Example 2.
[Table 4]
Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 * 2.030 0.44 1.54470 56.2 0.88
2 * -11.483 0.03 0.74
3 (Aperture) ∞ 0.15 0.63
4 * 4.580 0.31 1.63200 23.4 0.74
5 * 1.749 0.37 0.82
6 * 5.472 0.52 1.54470 56.2 1.04
7 * 31.038 0.31 1.22
8 * -5.351 0.70 1.54470 56.2 1.38
9 * -1.567 0.22 1.65
10 * 15.794 0.70 1.54470 56.2 2.18
11 * 2.354 0.28 2.47
12 * 8.648 0.08 1.58510 33.8 2.54
13 ∞ 0.30 1.51630 64.1 2.65
14 ∞ 0.05 1.60860 26.5 2.75
15 * 2.957 0.50 2.76
16 ∞ 2.76

Table 5 below shows the aspheric coefficients of the lens surfaces of the imaging lens of Example 2.
[Table 5]
First side
K = -0.28388E + 00, A4 = -0.11429E-01, A6 = 0.58394E-02, A8 = -0.30635E-01,
A10 = 0.25844E-01, A12 = -0.11762E-01, A14 = -0.24890E-02
Second side
K = 0.29247E + 02, A4 = -0.24343E-01, A6 = 0.16540E + 00, A8 = -0.35209E + 00,
A10 = 0.38420E + 00, A12 = -0.26046E + 00, A14 = 0.77919E-01
4th page
K = -0.29353E + 02, A4 = -0.58267E-01, A6 = 0.27269E + 00, A8 = -0.39392E + 00,
A10 = 0.22595E + 00, A12 = -0.42192E-01, A14 = -0.51043E-03
5th page
K = -0.55718E + 01, A4 = -0.71904E-02, A6 = 0.15580E + 00, A8 = -0.14089E + 00,
A10 = 0.28229E-01, A12 = -0.32553E-01, A14 = 0.38484E-01
6th page
K = 0.22272E + 02, A4 = -0.10217E + 00, A6 = -0.13167E-01, A8 = 0.99700E-01,
A10 = -0.14042E + 00, A12 = 0.12255E + 00, A14 = -0.50937E-01
7th page
K = -0.95653E + 02, A4 = -0.61924E-01, A6 = 0.13566E-01, A8 = -0.35274E-01,
A10 = 0.20141E-01, A12 = 0.64892E-02, A14 = -0.31555E-02
8th page
K = 0.10552E + 02, A4 = 0.14950E-01, A6 = 0.82129E-02, A8 = -0.12281E-01,
A10 = -0.26695E-02, A12 = 0.44153E-02, A14 = -0.68681E-03
9th page
K = -0.39323E + 01, A4 = -0.70567E-01, A6 = 0.49341E-01, A8 = -0.42386E-02,
A10 = -0.20788E-04, A12 = -0.91338E-03, A14 = 0.18678E-03
10th page
K = 0.79799E + 01, A4 = -0.11271E + 00, A6 = 0.35926E-01, A8 = -0.81251E-03,
A10 = -0.12071E-02, A12 = 0.18687E-03, A14 = -0.80839E-05
11th page
K = -0.60657E + 01, A4 = -0.62302E-01, A6 = 0.18921E-01, A8 = -0.44435E-02,
A10 = 0.53983E-03, A12 = -0.23945E-04, A14 = -0.61553E-07
12th page
K = 0.00000E + 00, A4 = -0.41247E-01, A6 = 0.88984E-02, A8 = -0.13715E-02,
A10 = 0.91871E-04
15th page
K = 0.00000E + 00, A4 = -0.41247E-01, A6 = 0.88984E-02, A8 = -0.13715E-02,
A10 = 0.91871E-04

The single lens data of Example 2 is shown in Table 6 below.
[Table 6]
Lens Start surface Focal length (mm)
1 1 3.204
2 4 -4.674
3 6 12.110
4 8 3.821
5 10 -5.174
6 12 -7.447

  FIG. 6 is a cross-sectional view of the imaging lens 12 (10) of the second embodiment. The imaging lens 12 (10) includes a first lens group Gr1 and a first lens group Gr2 in order from the object side. The first lens group Gr1 has a positive refractive power as a whole, and in order from the object side, the first lens L11, the aperture stop S, the second lens L12, the third lens L13, and the fourth lens L14. And a fifth lens L15. The first to fifth lenses L11 to L15 are made of resin. The first lens L11 is a biconvex aspherical lens having positive refractive power. The second lens L12 is a meniscus both aspherical lens having negative refractive power and convex toward the object side. The third lens L13 is a meniscus aspherical lens having slightly positive refractive power and convex toward the object side. The fourth lens L14 is a meniscus aspherical lens having positive refractive power and convex toward the image side. The fifth lens L15 is a double meniscus aspheric lens having negative refractive power and convex toward the object side. The first lens group Gr2 has a negative refractive power as a whole, and is a lens block in which the first lens portion L21, the substrate F, and the second lens portion L22 are joined in order from the object side. The first lens portion L21 is an aspheric lens having positive refractive power and convex toward the object side. The substrate F is a parallel plate, and one of the object side surface and the image side surface has a function of cutting infrared light or an optical low-pass filter. The second lens portion L22 is an aspheric lens having negative refractive power and concave on the image side.

  7A to 7C show aberration diagrams (spherical aberration, astigmatism, and distortion aberration) of the imaging lens 12 of Example 2. FIG. 7D and 7E show the meridional coma aberration of the imaging lens 12 of Example 2. FIG. In the aberration diagrams and the subsequent aberration diagrams, in the spherical aberration diagram, the solid line represents the d line and the dotted line represents the g line, and in the astigmatism diagram, the solid line represents the sagittal image plane and the dotted line represents the meridional. It shall represent the image plane.

Example 3
The overall specifications of Example 3 are shown below.
f = 3.77 mm
fB = 0.27mm
F = 2.8
2Y = 5.744mm
ENTP = 0.43mm
EXTP = −2.54mm
H1 = −0.85mm
H2 = -3.5mm

Table 7 shows lens data of Example 3.
[Table 7]
Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 * 2.116 0.59 1.54470 56.2 0.91
2 * -9.293 0.01 0.67
3 (Aperture) ∞ 0.11 0.62
4 * 3.481 0.30 1.63200 23.4 0.70
5 * 1.541 0.36 0.78
6 * 5.470 0.55 1.54470 56.2 1.02
7 * 17.217 0.37 1.24
8 * -5.497 0.75 1.54470 56.2 1.46
9 * -1.144 0.08 1.71
10 * 18.919 0.73 1.54470 56.2 2.15
11 * 1.196 0.67 2.53
12 ∞ 0.15 1.51630 64.1 2.80
13 ∞ 0.06 1.56000 52.6 2.84
14 * 33.544 0.00 2.86
15 ∞ 2.85

Table 8 below shows the aspheric coefficients of the lens surfaces of the imaging lens of Example 3.
[Table 8]
First side
K = -0.28388E + 00, A4 = -0.11429E-01, A6 = 0.58394E-02, A8 = -0.30635E-01,
A10 = 0.25844E-01, A12 = -0.11762E-01, A14 = -0.24890E-02
Second side
K = 0.29247E + 02, A4 = -0.24343E-01, A6 = 0.16540E + 00, A8 = -0.35209E + 00,
A10 = 0.38420E + 00, A12 = -0.26046E + 00, A14 = 0.77919E-01
4th page
K = -0.29353E + 02, A4 = -0.58267E-01, A6 = 0.27269E + 00, A8 = -0.39392E + 00,
A10 = 0.22595E + 00, A12 = -0.42192E-01, A14 = -0.51043E-03
5th page
K = -0.55718E + 01, A4 = -0.71904E-02, A6 = 0.15580E + 00, A8 = -0.14089E + 00,
A10 = 0.28229E-01, A12 = -0.32553E-01, A14 = 0.38484E-01
6th page
K = 0.22272E + 02, A4 = -0.10217E + 00, A6 = -0.13167E-01, A8 = 0.99700E-01,
A10 = -0.14042E + 00, A12 = 0.12255E + 00, A14 = -0.50937E-01
7th page
K = -0.95653E + 02, A4 = -0.61924E-01, A6 = 0.13566E-01, A8 = -0.35274E-01,
A10 = 0.20141E-01, A12 = 0.64892E-02, A14 = -0.31555E-02
8th page
K = 0.10552E + 02, A4 = 0.14950E-01, A6 = 0.82129E-02, A8 = -0.12281E-01,
A10 = -0.26695E-02, A12 = 0.44153E-02, A14 = -0.68681E-03
9th page
K = -0.39323E + 01, A4 = -0.70567E-01, A6 = 0.49341E-01, A8 = -0.42386E-02,
A10 = -0.20788E-04, A12 = -0.91338E-03, A14 = 0.18678E-03
10th page
K = 0.79799E + 01, A4 = -0.11271E + 00, A6 = 0.35926E-01, A8 = -0.81251E-03,
A10 = -0.12071E-02, A12 = 0.18687E-03, A14 = -0.80839E-05
11th page
K = -0.60657E + 01, A4 = -0.62302E-01, A6 = 0.18921E-01, A8 = -0.44435E-02,
A10 = 0.53983E-03, A12 = -0.23945E-04, A14 = -0.61553E-07
14th page
K = 0.00000E + 00, A4 = -0.48840E-02, A6 = -0.44704E-04, A8 = 0.13976E-03,
A10 = -0.10240E-04, A12 = -0.23945E-04, A14 = -0.61553E-07

The single lens data of Example 3 is shown in Table 9 below.
[Table 9]
Lens Start surface Focal length (mm)
1 1 3.223
2 4 -4.655
3 6 14.482
4 8 2.500
5 10 -2.378
6 13 -59.629

  FIG. 8 is a cross-sectional view of the imaging lens 13 (10) of the third embodiment. The imaging lens 13 (10) includes a first lens group Gr1 and a first lens group Gr2 in order from the object side. The first lens group Gr1 has a positive refractive power as a whole, and in order from the object side, the first lens L11, the aperture stop S, the second lens L12, the third lens L13, and the fourth lens L14. And a fifth lens L15. The first to fifth lenses L11 to L15 are made of resin. The first lens L11 is a biconvex aspherical lens having positive refractive power. The second lens L12 is a meniscus both aspherical lens having negative refractive power and convex toward the object side. The third lens L13 is a meniscus aspherical lens having slightly positive refractive power and convex toward the object side. The fourth lens L14 is a meniscus aspherical lens having positive refractive power and convex toward the image side. The fifth lens L15 is a double meniscus aspheric lens having negative refractive power and convex toward the object side. The first lens group Gr2 has a negative refractive power as a whole, and is a lens block in which the substrate F and the lens portion L21 are joined in order from the object side. The lens portion L21 is an aspheric lens having negative refractive power and concave on the image side. The substrate F is a parallel plate, and one of the object side surface and the image side surface has a function of cutting infrared light or an optical low-pass filter.

  9A to 9C show aberration diagrams (spherical aberration, astigmatism, and distortion aberration) of the imaging lens 10 of Example 3. FIG. 9D and 9E show the meridional coma aberration of the imaging lens 10 of Example 3. FIG. In the aberration diagrams and the subsequent aberration diagrams, in the spherical aberration diagram, the solid line represents the d line and the dotted line represents the g line, and in the astigmatism diagram, the solid line represents the sagittal image plane and the dotted line represents the meridional. It shall represent the image plane.

Example 4
The overall specifications of Example 4 are shown below.
f = 3.32mm
fB = 0.1mm
F = 2.4
2Y = 4.6mm
ENTP = 0mm
EXTP = -2.79mm
H1 = -0.5mm
H2 = −3.22mm

Table 10 shows lens data of Example 4.
[Table 10]
Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 (Aperture) ∞ -0.14 0.69
2 * 1.313 0.48 1.54470 56.2 0.77
3 * -14.050 0.03 0.77
4 * 6.737 0.30 1.63470 23.9 0.77
5 * 1.681 0.46 0.76
6 * -20.987 0.50 1.54470 56.2 0.85
7 * 29.826 0.20 1.05
8 * 2.671 0.70 1.54470 56.2 1.19
9 * -1.588 0.21 1.43
10 * -0.904 0.70 1.53050 55.7 1.51
11 * -14.650 0.10 1.98
12 * 9.413 0.10 1.59040 32.3 2.08
13 ∞ 0.40 1.51630 64.1 2.14
14 ∞ 2.25

Table 11 below shows the aspheric coefficients of the lens surfaces of the imaging lens of Example 4.
[Table 11]
Second side
K = -0.77153E-01, A4 = 0.24309E-01, A6 = -0.29670E-01, A8 = 0.71186E-01,
A10 = 0.13183E + 00, A12 = -0.32981E + 00
Third side
K = 0.22040E + 02, A4 = 0.45383E-01, A6 = -0.21303E-01, A8 = 0.27381E-01,
A10 = -0.28659E + 00, A12 = 0.16532E-01
4th page
K = 0.21833E + 02, A4 = -0.79239E-01, A6 = 0.12210E + 00, A8 = -0.10743E-01,
A10 = -0.76329E + 00, A12 = 0.72524E + 00
5th page
K = 0.60974E + 00, A4 = -0.11501E + 00, A6 = 0.37667E + 00, A8 = -0.59474E + 00,
A10 = 0.46812E + 00, A12 = 0.19003E + 00
6th page
K = -0.50000E + 02, A4 = -0.17590E + 00, A6 = 0.44954E-01, A8 = -0.13494E + 00,
A10 = 0.38627E-01, A12 = 0.61774E-01
7th page
K = -0.50000E + 02, A4 = -0.31528E + 00, A6 = 0.17177E-01, A8 = 0.72983E-01,
A10 = -0.97338E-01, A12 = 0.57302E-01
8th page
K = -0.94551E + 01, A4 = -0.15307E + 00, A6 = -0.18675E-01, A8 = -0.68439E-01,
A10 = 0.56595E-01, A12 = -0.89291E-02
9th page
K = -0.34620E + 01, A4 = -0.46891E-01, A6 = 0.50201E-01, A8 = -0.34803E-01,
A10 = 0.15085E-01, A12 = -0.25638E-02
10th page
K = -0.77469E + 00, A4 = 0.17528E + 00, A6 = 0.26278E-01, A8 = -0.95459E-02,
A10 = -0.12061E-02, A12 = 0.59429E-03
11th page
K = 0.42130E + 02, A4 = 0.47613E-01, A6 = -0.24404E-01, A8 = -0.63569E-03,
A10 = 0.13131E-02, A12 = -0.15780E-03
12th page
K = 0.00000E + 00, A4 = -0.28499E-01, A6 = 0.11823E-02, A8 = 0.29404E-04,
A10 = 0.22778E-04, A12 = 0.25749E-05

The single lens data of Example 4 is shown in Table 12 below.
[Table 12]
Lens Start surface Focal length (mm)
1 2 2.230
2 4 -3.611
3 6 -22.538
4 8 1.941
5 10 -1.849
6 12 15.828

  FIG. 10 is a cross-sectional view of the imaging lens 14 (10) of the fourth embodiment. The imaging lens 14 (10) includes a first lens group Gr1 and a first lens group Gr2 in order from the object side. The first lens group Gr1 has a positive refractive power as a whole, and in order from the object side, the aperture stop S, the first lens L11, the second lens L12, the third lens L13, and the fourth lens L14. And a fifth lens L15. The first to fifth lenses L11 to L15 are made of resin. The first lens L11 is a biconvex aspherical lens having positive refractive power. The second lens L12 is a meniscus both aspherical lens having negative refractive power and convex toward the object side. The third lens L13 is a biconcave aspherical lens having slightly negative refractive power. The fourth lens L14 is a biconvex aspherical lens having positive refractive power. The fifth lens L15 is a meniscus both aspherical lens having negative refractive power and convex toward the image side. The first lens group Gr2 has a slight positive refractive power as a whole, and is a lens block in which the lens portion L21 and the substrate F are joined in order from the object side. The lens portion L21 is an aspheric lens having positive refractive power and convex toward the object side. The substrate F is a parallel plate, and one of the object side surface and the image side surface has a function of cutting infrared light or an optical low-pass filter. In addition, the board | substrate F may serve as the sealing glass of the image pick-up element 51, etc.

  FIGS. 11A to 11C show aberration diagrams (spherical aberration, astigmatism, and distortion aberration) of the imaging lens 10 of Example 4. FIGS. FIGS. 11D and 11E show the meridional coma aberration of the imaging lens 10 of Example 4. FIG. In the aberration diagrams and the subsequent aberration diagrams, in the spherical aberration diagram, the solid line represents the d line and the dotted line represents the g line, and in the astigmatism diagram, the solid line represents the sagittal image plane and the dotted line represents the meridional. It shall represent the image plane.

For reference, Table 13 below summarizes the values of Examples 1 to 4 corresponding to the conditional expressions (1) to (7).
[Table 13]

  In the above, the present invention has been described based on the embodiments and examples, but the present invention is not limited to the above-described embodiments and the like.

In recent years, as a method of mounting an image pickup apparatus at a low cost (production cost) and in large quantities, an IC (integrated circuit) chip or other electronic components and optical elements are mounted on a substrate on which solder has been potted or built in advance. A technique has been proposed in which an electronic component and an optical element are simultaneously mounted on a substrate by performing a reflow process (heating process) while being placed and melting solder. In order to mount using such a reflow process, it is necessary to heat an optical element to about 200-260 degreeC with an electronic component. Under such a high temperature, there is a problem that a lens using a thermoplastic resin is thermally deformed or discolored and its optical performance is deteriorated. As one of the methods for solving such a problem, a technique has been proposed in which a glass mold lens having excellent heat resistance is used to achieve both miniaturization and optical performance in a high temperature environment. However, since glass mold lenses are generally more expensive than lenses using thermoplastic resins, there has been a problem that it is difficult to meet the demand for cost reduction of imaging devices. Therefore, by using an energy curable resin as the material of the imaging lens 10, a decrease in optical performance when exposed to a high temperature is reduced as compared with a lens using a thermoplastic resin such as polycarbonate or polyolefin. . Such an energy curable resin is effective for the reflow treatment, and is easier to manufacture and less expensive than the glass mold lens. Thereby, both low cost and mass productivity of the imaging device incorporating the imaging lens 10 can be achieved. The energy curable resin refers to both a thermosetting resin and an ultraviolet curable resin.
A plastic material in which inorganic particles are dispersed can also be used for manufacturing the lenses L11 to L15 of Examples 1 to 4. Thereby, it is possible to further suppress the image point position fluctuation when the temperature of the entire imaging lens 10 system changes.

  In the first to fourth embodiments, the principal ray incident angle of the light beam incident on the imaging surface I of the photoelectric conversion unit 51a provided in the imaging element 51 is designed to be sufficiently small in the peripheral portion of the imaging surface I. Absent. However, with recent technology, it has become possible to reduce shading (unevenness of brightness) by reviewing the arrangement of the color filters of the image sensor 51 and the on-chip microlens array. Specifically, if the pitch of the arrangement of the color filters and the on-chip microlens array is set slightly smaller than the pixel pitch of the image pickup surface I of the image pickup device 51, the pixel is closer to the periphery of the image pickup surface I. The color filter and the on-chip microlens array shift to the optical axis AX side of the imaging lens 10. Therefore, the obliquely incident light beam can be efficiently guided to the light receiving portion (imaging surface) of each pixel. Thereby, the shading which generate | occur | produces in the image pick-up element 51 can be restrained small. Examples 1 to 4 are design examples aiming at further miniaturization for the portion in which the above-described requirements are relaxed.

  Although not shown, it is also within the scope of the present invention to add a dummy lens having substantially no power to the imaging lens 10 of the embodiment.

DESCRIPTION OF SYMBOLS 10 ... Imaging lens, 50 ... Camera module, 51 ... Imaging device, 52 ... Wiring board, 54 ... Lens barrel part, 100 ... Imaging device, 103 ... Control part, 105 ... Optical system drive part, 107 ... Imaging element drive part, DESCRIPTION OF SYMBOLS 108 ... Image memory 300 ... Portable communication terminal 310 ... Control part 320 ... Display operation part 330 ... Operation part 340 ... Wireless communication part OA ... Optical axis I ... Imaging surface Gr1 ... 1st lens group, Gr2: First lens group, L11, L12, L13, L14, L15 ... Lens, L21, L22 ... Lens part, F ... Substrate, OP ... Opening

Claims (16)

An imaging lens for forming a subject image on an imaging surface of an imaging element,
In order from the object side, it consists of a first lens group and a second lens group,
The first lens group has a positive refractive power as a whole, and is composed of at least four or more lenses.
The most image side lens in the first lens group is a negative lens;
The second lens group includes one lens block in which a lens portion is formed on at least one of an object side surface and an image side surface of a substrate that is a parallel plate.
An imaging lens that satisfies the following conditional expression.
−0.70 <fg1r / | fg2 | <−0.01 (1)
However,
fg1r: focal length of the most image side lens in the first lens group fg2: focal length of the second lens group The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
0.01 <f / | fg2 | <0.70 (2)
However,
f: focal length of the entire imaging lens system fg2: focal length of the second lens group The imaging lens according to claim 1, wherein the imaging lens satisfies the following conditional expression.
0.09 <dg2l / f <0.30 (3)
However,
dg2l: distance on the optical axis from the object side vertex of the lens unit formed on the most object side of the second lens group or the object side surface of the substrate to the imaging surface of the imaging lens f: focal length of the entire imaging lens system The imaging lens according to any one of claims 1 to 3, wherein the following conditional expression is satisfied.
0.5 <Σdg2 / dMing1 ≦ 1.0 (4)
However,
Σdg2: Total thickness on the optical axis of the second lens group dMing1: Minimum thickness on the optical axis of the lenses constituting the first lens group The imaging lens according to any one of claims 1 to 4, which satisfies the following conditional expression.
0.10 <THg2l / THg2b <0.80 (5)
However,
THg2l: total thickness of the second lens group on the optical axis of the lens portion THg2b: thickness of the second lens group on the optical axis of the substrate   The imaging lens according to any one of claims 1 to 5, wherein the lens portion of the second lens group has an aspherical shape.   The imaging lens according to any one of claims 1 to 6, wherein the first lens group includes two positive lenses and two negative lenses.   The imaging lens according to claim 1, wherein the second lens group has a negative refractive power. The imaging lens according to any one of claims 1 to 8, wherein the lens portion of the second lens group includes a material that satisfies the following conditional expression.
28 <νg2l <60 (6)
However,
νg2l: Abbe number of the material of the lens portion of the second lens group   10. The imaging lens according to claim 1, wherein in the lens block constituting the second lens group, the lens portion is formed only on the object side surface. 10.   10. The imaging lens according to claim 1, wherein in the lens block constituting the second lens group, the lens portion is formed only on an image side surface. 10.   The imaging lens according to any one of claims 1 to 9, wherein in the lens block constituting the second lens group, the lens portions are formed on both the object side and the image side.   The imaging lens according to claim 1, wherein at least one of the object side surface and the image side surface of the substrate of the second lens group has a function of cutting infrared light.   The imaging lens according to claim 1, further comprising a lens having substantially no power. The imaging lens according to any one of claims 1 to 14,
An imaging apparatus comprising: the imaging element that photoelectrically converts an image formed on an imaging surface by the imaging lens.   A portable terminal comprising the imaging device according to claim 15.

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