WO2009110311A1

WO2009110311A1 - Imaging lens, imaging device and method for manufacturing imaging lens

Info

Publication number: WO2009110311A1
Application number: PCT/JP2009/052659
Authority: WO
Inventors: 貴志川崎; 慶二松坂
Original assignee: コニカミノルタオプト株式会社
Priority date: 2008-03-07
Filing date: 2009-02-17
Publication date: 2009-09-11

Abstract

In an imaging lens, performance deterioration due to production error is suppressed, and the imaging lens is manufactured with excellent productivity. At least two lens groups, which are included in the imaging lens and have a high axial beam height, are manufactured by a replica method. Thus, optical axis of a lens block included in the lens group is accurately aligned, and by reducing parallel eccentricity of the lens group, performance deterioration due to production error can be suppressed.

Description

Imaging lens, imaging device, and manufacturing method of imaging lens

The present invention relates to an imaging lens of an imaging apparatus using a solid-state imaging device such as a CCD (Charge Coupled Device) type image sensor or a CMOS (Complementary Metal-Oxide Semiconductor) type image sensor, and more specifically for mass production. The present invention relates to an imaging lens partially using a suitable wafer-scale lens, an imaging device using the imaging lens, and a manufacturing method of the imaging lens.

A compact and very thin imaging device (hereinafter also referred to as a camera module) is used in portable terminals that are compact and thin electronic devices such as mobile phones and PDAs (Personal Digital Assistants), and also uses a zoom lens. Small imaging devices are used for small digital cameras, video cameras, and the like. As an image pickup element used in these image pickup apparatuses, a solid-state image pickup element such as a CCD type image sensor or a CMOS type image sensor is used. In recent years, the number of pixels of an image sensor has been increased, and higher resolution and higher performance have been achieved. In addition, an imaging lens for forming a subject image on these imaging elements is required to be compact in response to miniaturization of the imaging element, and the demand tends to increase year by year.

As such an imaging lens used in the imaging apparatus, an optical system composed of a resin material lens and an optical system composed of a glass lens and a resin material lens are generally well known. However, in these optical systems, when the lens is miniaturized, the optical performance is significantly deteriorated due to a manufacturing error in the lens manufacturing (for example, the optical axis of the lens does not match the optical axis of the optical system). Therefore, it can be said that it is difficult to achieve both further ultra-compactness and mass productivity required for these imaging devices.

In order to overcome such problems, in the design of such an imaging lens, optimization of the power arrangement and the lens shape of each lens is performed so that the deterioration of the optical performance due to the manufacturing error is reduced. While aiming for a design that is excellent in mass productivity, it is possible to reduce blurring and improve performance by aligning lenses with high parallel eccentricity sensitivity (inclination of the lens and adjustment of the optical axis). Approaches have been taken.

With regard to such an imaging lens, a single focus lens is a triplet type lens as described in Patent Document 1, a zoom lens is a lens with optimized power arrangement and surface spacing as in Patent Document 2, and Patent Document 3 Such alignment methods have been proposed.
JP 2006-308789 A JP 2005-055592 A JP 2006-148662 A

However, such conventional technology is still insufficient to achieve both high-dimensional compatibility between suppressing manufacturing errors and ensuring mass productivity.

The present invention has been made in view of such a situation, and an object thereof is to provide an imaging lens that suppresses performance deterioration due to a manufacturing error and is excellent in mass productivity.

The imaging lens according to claim 1 integrates at least two lens blocks each having a lens portion formed on at least one of an object side surface and an image side surface of a lens substrate, which is a parallel plate, via an interval defining portion. An imaging lens having a lens group made of resin and a lens made of a resin material or a glass material, wherein a surface having a maximum ray height of an axial light beam of the imaging lens is in the lens group To do.

For the purpose of mass production and cost reduction of imaging lenses built in portable terminals, a large number of lens parts are simultaneously formed on a several inch wafer (lens substrate) by the replica method, and these are combined with the sensor wafer and then separated. A method of mass-producing camera modules is known. In this specification, a lens substrate and a lens part formed in large quantities on the lens substrate are collectively referred to as a lens block unit, and one separated from the lens block unit is referred to as a lens block.

In general, in an imaging lens, a lens that passes through a position where axial light rays are high is subject to collapsing due to a manufacturing error (the optical axis shift of the lens in a direction perpendicular to the optical axis of the optical system). The so-called “one-sided blur” in which the resolving power on the image sensor becomes asymmetrical may occur, and the performance may be significantly degraded. That is, in order to suppress performance degradation due to manufacturing errors, it is necessary to align the optical axis of a lens with a high axial ray height with the optical axis of the optical system.

According to the present invention, a lens group having a high axial ray height, which is a constituent element of an imaging lens, is included in this lens group by integrating at least two lens blocks via a space defining part such as a spacer. By aligning the optical axes of the lens blocks with high accuracy and reducing parallel decentering, performance degradation caused by manufacturing errors can be reduced. The maximum ray height of the on-axis light beam means the height (distance from the optical axis) of the light beam that forms the image on the optical axis and intersects the optical surface farthest from the optical axis. In this specification, the term “imaging lens” includes a so-called zoom lens having a zooming function.

Further, in the lens block in which the lens portion is formed on the lens substrate, the shape is limited due to the lens substrate being a parallel plate, but at least one lens group other than the lens group configured by a plurality of lens blocks is used. By setting it as the imaging lens which has a lens, the freedom degree of a shape increases and it can be set as a higher performance imaging lens.

The imaging lens according to claim 2 is the invention according to claim 1, wherein the lens group includes at least two lens block units each having a plurality of lens blocks formed in a lattice shape. And a step of adhering via the interval defining portion, and a step of cutting the adhered lens block unit and the interval defining portion at the position of the lattice frame of the interval defining portion. It is characterized by being.

When manufacturing a lens group composed of a plurality of lens blocks, another lens block unit is laminated and bonded via a space defining portion such as a spacer member on the lens block unit formed with a large number of lens portions, and bonded. Disconnect. With this configuration, when the lens block units are stacked, the optical axes of the other lens blocks can be aligned together simply by aligning the optical axes of the two lens blocks. For this reason, the optical axes of the lens blocks constituting a large number of lens groups can be adjusted simultaneously and with the same accuracy as compared with the case where, for example, one lens group composed of at least two glass lenses or plastic lenses is created. Thus, a lens group having a small parallel decentration, which is composed of at least two lens blocks and whose optical axes are aligned with high accuracy, can be produced in large quantities and at low cost in a short time. Furthermore, since it is bonded and fixed, it is possible to prevent the optical axes of the lens blocks from being shifted after the production. In addition, this manufacturing method is not limited to the camera module, and a lens group in which a plurality of lens blocks are bonded can be mass-produced except for the sensor wafer.

The imaging lens according to claim 3 is the imaging lens according to claim 1 or 2, wherein E is a parallel decentering sensitivity at 70% image height of each of the lens groups, and each of the lens blocks. Emax is the maximum absolute value of the 70% parallel decentration sensitivity, and the lens group includes a parallel decentering sensitivity lens block having a sign opposite to Emax, and satisfies the following conditional expression: To do.
| E / Emax | <0.5 (1)
However, the parallel decentering sensitivity is a value of ΔM / Δ when the change amount ΔM of the meridional image plane with respect to the decentering amount Δ of the lens in the direction perpendicular to the optical axis of the image pickup lens is 70% image height. Is a height of 70% that is 1/2 of the diagonal length of the rectangular effective pixel region of the solid-state imaging device.

If the parallel decentering sensitivity of a lens decentered due to a manufacturing error is high, the meridional image plane is greatly tilted with respect to the imaging surface even with small decentering, and performance degradation due to single blurring also increases. However, even a lens with high parallel eccentricity sensitivity can be combined with a single lens with parallel eccentricity sensitivity of the opposite sign to make a lens group, which reduces the parallel eccentricity sensitivity of the entire lens group. Is possible. Therefore, in the present invention, the lens group that is a component of the imaging lens includes a lens block having a parallel eccentricity sensitivity of the opposite sign to the lens block having the highest absolute value of the parallel eccentricity sensitivity. By using the lens group, the parallel eccentric sensitivity as the lens group can be reduced. In particular, by satisfying conditional expression (1), even when the sensitivity of parallel decentering of the lens blocks constituting the lens group is high, the tilt of the image plane due to the parallel decentering of the lens group is reduced, and performance degradation due to single blurring is suppressed to a minimum. be able to. However, regarding a lens having a zoom function, conditional expression (1) is satisfied at a position where the value of | E / Emax | is the largest. The following conditional expression (1 ′),
| E / Emax | <0.3 (1 ′)
It is further desirable to satisfy

In this specification, “parallel decentering sensitivity” means the value of ΔM / Δ when the change amount ΔM of the meridional image plane between the optical axis of the imaging lens and the decentering amount Δ of the lens in the vertical direction. Good, “reverse sign” means that the meridional image plane moves in the opposite direction parallel to the optical axis with respect to the eccentricity of each of the two lenses in the same vertical direction as the optical axis. The surface on which the meridional light beam forms the sharpest image is assumed.

The imaging lens according to claim 4 is an aperture stop on any lens substrate of the lens block forming the lens group in the invention according to any one of claims 1 to 3. It is characterized by having.

An aperture stop can be easily formed on the lens substrate by applying a light-shielding member on the surface of the lens substrate or by vacuum deposition.

The imaging lens according to claim 5 is the imaging lens according to any one of claims 1 to 4, wherein the lens portion is made of a resin material and the lens substrate is made of a glass material. It is characterized by.

An imaging lens that is easy to polish by using a glass substrate for the lens substrate, which is a parallel plate, and that has a complicated shape and a resin material with good moldability, so that high performance can be achieved at low cost. Can be formed.

The imaging lens according to claim 6 is characterized in that, in the invention according to any one of claims 1 to 5, the surface of the lens portion that contacts air is an aspherical surface. .

¡By making the lens surface in contact with the air of the lens part an aspherical surface, the difference in refractive index is the largest at the boundary surface between the air and the lens part, and the effect of the aspheric surface can be utilized to the maximum. Further, by making the lens surfaces all aspherical, the occurrence of various aberrations can be minimized, and high performance can be easily achieved.

The imaging lens according to claim 7 is characterized in that, in the invention according to any one of claims 1 to 6, the lens portion is made of an energy curable resin.

By constructing the lens portion with an energy curable resin material, it becomes possible to cure the lens portion to a wafer-like lens substrate in a large amount at the same time by a mold by various means, so that mass productivity can be improved. become. The energy curable resin material refers to a thermosetting resin material that is cured by heat, an ultraviolet (UV) curable resin material that is cured by light, or the like. The energy curable resin material is preferably composed of a UV curable resin material. By comprising a UV curable resin material, the curing time can be shortened and the mass productivity can be improved. In recent years, resin materials having excellent heat resistance have been developed and can withstand reflow treatment.

The imaging lens according to claim 8 is the invention according to claims 1 to 7, wherein inorganic fine particles having a length of 30 nanometers or less are dispersed in the resin material. It is characterized by.

Dispersing inorganic fine particles of 30 nanometers or less in a lens part made of a resin material can reduce performance deterioration and image point position fluctuations even when the temperature changes, and also reduce light transmittance. In addition, an imaging lens having excellent optical characteristics regardless of environmental changes can be provided.

In general, mixing fine particles with a transparent resin material causes light scattering and decreases the transmittance, making it difficult to use as an optical material. However, the size of the fine particles should be smaller than the wavelength of the transmitted light beam. Thus, substantially no scattering can occur.

Also, 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, by dispersing inorganic particles of 30 nanometers or less in the resin material as the base material, preferably 20 nanometers or less, more preferably 15 nanometers or less in the resin material as the base material, A material having any temperature dependency can be provided.

Furthermore, although the refractive index of the resin material decreases as the temperature rises, if inorganic particles whose refractive index increases as the temperature rises are dispersed in the resin material as the base material, these properties will cancel each other. 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, by dispersing inorganic particles of 30 nanometers or less in the resin material as the base material, preferably 20 nanometers or less, more preferably 15 nanometers or less in the resin material as the base material, A material having any temperature dependency can be provided.

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 temperature change A of the refractive index will be described in detail. The temperature change A of the refractive index is expressed by the following equation by differentiating the refractive index n with respect to the temperature t based on the Lorentz-Lorentz equation (Equation 1).

In the case of a resin material, the contribution of the second term is generally smaller than the first term in the formula, and can be almost ignored. For example, in the case of PMMA resin, the linear expansion coefficient α is 7 × 10 ⁻⁵ , and if it is substituted into the above equation, dn / dt = −1.2 × 10 ⁻⁴ [/ ° C.], which is almost the same as the actually 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 is substantially increased, so as to cancel out the change due to the linear expansion of the first term. . 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 .

It is also possible to further increase the contribution of the second term and to have temperature characteristics opposite to those of the base resin material. That is, it is possible to obtain a material whose refractive index increases instead of decreasing the refractive index as the temperature increases. Similarly, although the refractive index of the resin material increases due to water absorption, a material whose refractive index decreases can be obtained.

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 claim 9 is the imaging lens according to any one of claims 1 to 8, wherein the lens substrate and the lens portion are formed through a thin film. It is characterized by having.

By forming an aperture stop or infrared cut filter formed of a thin film between the lens portion and the lens substrate, the optical member can be simplified and the cost can be reduced.

The imaging lens according to claim 10 is the invention according to any one of claims 1 to 9, wherein the lens group has a lens block in which a lens portion is formed only on one side. It is characterized by.

When the lens substrate is a parallel plate, the aberration correction function is assigned to a surface having no curvature by design, so that the influence on the aberration performance can be reduced without forming a resin portion on one side. In such a case, it is better not to form the lens portion considering the balance between good aberration performance and low cost. Further, if one side has no curvature, a function such as infrared cut can be provided by depositing a thin film on the surface.

The imaging lens according to claim 11 is the imaging lens according to any one of claims 1 to 10, wherein the lens block is provided on one of the lens portion and the lens substrate, respectively. Means for aligning the optical axis is formed.

As a means for aligning the optical axis, for example, by providing a mark on a part of the lens substrate, for example, when forming a lens portion on the lens substrate by a replica method, or between a plurality of lens blocks or a plurality of lens block units When bonding them together via a space defining portion such as a spacer member, the optical axes can be aligned more accurately, the time for aligning the optical axes can be shortened, and mass productivity can be improved.

The imaging device according to claim 12 is characterized by using the imaging lens according to any one of claims 1 to 11, so that it can be used in a low-cost and high-humidity environment. Can be provided.

The imaging lens manufacturing method according to claim 13 is a lens block unit in which a plurality of lens blocks each having a lens portion formed on at least one of an object side surface and an image side surface of a lens substrate that is a parallel plate are formed. A step of bonding the two through the lattice-shaped interval defining portion, and a step of cutting the bonded lens block unit and the interval defining portion at the position of the lattice frame of the interval defining portion to obtain a lens group And a step of arranging the lens group at a position on the optical axis where the surface having the maximum light flux of the on-axis light beam of the imaging lens is located in the lens group. Thereby, a lens group having a high axial ray height, which is a component of the imaging lens, can be produced in a large amount and at a low cost, and an imaging lens with reduced performance degradation caused by a manufacturing error can be manufactured.

According to the present invention, it is possible to provide an imaging lens that suppresses performance degradation due to manufacturing errors and is excellent in mass productivity.

It is a perspective view of the imaging device 50 concerning this Embodiment. FIG. 2 is a cross-sectional view of the configuration of FIG. 1 taken along line II-II and viewed in the direction of the arrow. It is a figure which shows the state equipped with the imaging device 50 in the mobile telephone 100 as a portable terminal. 3 is a control block diagram of the mobile phone 100. FIG. It is a figure which shows the process of manufacturing the imaging lens concerning this Embodiment. It is sectional drawing of 1st Example. FIG. 4 is an aberration diagram of the imaging lens shown in Example 1. It is sectional drawing of 2nd Example. FIG. 6 is an aberration diagram of the imaging lens shown in Example 2. FIG. 6 is an aberration diagram of the imaging lens shown in Example 2. FIG. 6 is an aberration diagram of the imaging lens shown in Example 2. It is sectional drawing of 3rd Example. FIG. 6 is an aberration diagram of the imaging lens shown in Example 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Imaging lens 20 Case 50 Imaging device 51 Image sensor 51a Photoelectric conversion part 51b Signal processing circuit 52 Board | substrate 60 Input part 70 Display part 80 Wireless communication part 92 Temporary memory | storage part 93 Nonvolatile memory | storage part 100 Cellular phone 101 Control part B1 1st Lens block B1a First object side lens unit B1b First lens substrate B1c First image side lens unit B2 Second lens block B2a Second object side lens unit B2b Second lens substrate B2c Second image side lens unit F Optical member L3 First 3 lenses LG lens group SP spacer SP1 first spacer SP2 second spacer SP3 third spacer UT1 first lens block unit UT2 second lens block unit

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an imaging apparatus 50 according to the present embodiment, and FIG. 2 is a cross-sectional view of the configuration of FIG. 1 taken along the line II-II and viewed in the direction of the arrow. As shown in FIG. 2, the imaging device 50 includes a CMOS image sensor 51 as a solid-state imaging device having a photoelectric conversion unit 51 a, an imaging lens 10 that causes the photoelectric conversion unit 51 a of the image sensor 51 to capture a subject image, A substrate 52 having an external connection terminal (not shown) for holding the image sensor 51 and transmitting / receiving the electric signal is provided, and these are integrally formed. The imaging lens 10 is held by a housing 20 and includes a first lens block B1, a second lens block B2, and a third lens L3.

In the image sensor 51, a photoelectric conversion unit 51a as a light receiving unit in which pixels (photoelectric conversion elements) are two-dimensionally arranged is formed in the center of a plane on the light receiving side. A processing circuit 51b is formed. The signal processing circuit 51b forms a picture signal output by using a drive circuit unit that sequentially drives each pixel to obtain a signal charge, an A / D conversion unit that converts each signal charge into a digital signal, and the digital signal. It consists of a signal processing unit and the like. A number of pads (not shown) are arranged near the outer edge of the plane on the light receiving side of the image sensor 51, and are connected to the substrate 52 via wires (not shown). The image sensor 51 converts the signal charge from the photoelectric conversion unit 51a into an image signal such as a digital YUV signal, and outputs the image signal to a predetermined circuit on the substrate 52 via a wire (not shown). Here, Y is a luminance signal, U (= RY) is a color difference signal between red and the luminance signal, and V (= BY) is a color difference signal between blue and the luminance signal. Note that the solid-state imaging device is not limited to the CMOS image sensor, and other devices such as a CCD may be used.

The substrate 52 that supports the image sensor 51 is communicably connected to the image sensor 51 through a wiring (not shown).

The substrate 52 is connected to an external circuit (for example, a control circuit included in a host device of a portable terminal mounted with an imaging device) via an external connection terminal (not shown), and a voltage for driving the image sensor 51 from the external circuit. And a clock signal can be received, and a digital YUV signal can be output to an external circuit.

The upper part of the image sensor 51 is sealed with a flat optical member F such as an infrared cut filter fixed on the upper surface of the substrate 52. On the upper surface around the optical member F, the lower end of the third spacer SP3, which is a space defining portion, is fixed. The flange portion of the third lens L3 is fixed to the upper end of the third spacer SP3, and the lower end of the second spacer SP2 that is the interval defining portion is fixed to the upper surface of the flange portion of the third lens L3. The periphery of the second lens substrate B2b of the second lens block B2 is fixed to the upper end of the second spacer SP2, and the lower end of the first spacer SP1 that is the interval defining portion is fixed to the upper surface of the periphery of the second lens substrate B2b. The periphery of the first lens substrate B1b of the first lens block B1 is fixed to the upper end of the first spacer SP1. In the drawing, an example is shown in which the first to third spacers SP1 to SP3 are configured as separate members as the interval defining portion. However, the present invention is not limited to this. For example, the lens portion B1c formed on the lens substrate, A shape corresponding to the function of the first spacer SP1 may be integrally formed as at least one of B2a as the space defining portion. In addition, a shape corresponding to the second spacer SP2 and the third spacer SP3 may be formed as a spacer portion integrally with the flange portion of the third lens L3.

The first lens block B1 is formed on a first lens substrate B1b which is a glass parallel plate, a resin-made first object-side lens portion B1a formed on the object side surface, and an image side surface of the first lens substrate B1b. The first image side lens portion B1c made of resin. An aperture stop S is formed between the first object side lens unit B1a and the first lens substrate B1b by an optical thin film formed on the surface of the first lens substrate B1b. The second lens block B2 is formed on a second lens substrate B2b which is a glass parallel plate, a resin second object side lens portion B2a formed on the object side surface, and an image side surface of the second lens substrate B2b. The second image side lens portion B2c made of resin. In the lens group LG composed of the first lens block B1 and the second lens block B2, the maximum light beam height of the axial light beam passing through the lens group LG is the maximum light beam height of the axial light beam of the imaging lens 10. Each lens part B1a, B1c, B2a, B2c is preferably made of a thermosetting resin or an ultraviolet curable resin material in which inorganic fine particles having a maximum length of 30 nanometers or less are dispersed. Is preferably an aspherical surface. In addition, the lens part may be formed only on the object side surface or the image side surface of the lens substrates B1b and B2b.

The usage mode of the imaging device 50 described above will be described. FIG. 3 is a diagram illustrating a state in which the imaging device 50 is mounted on a mobile phone 100 as a mobile terminal that is a digital device. FIG. 4 is a control block diagram of the mobile phone 100.

The imaging device 50 is provided, for example, such that the object-side end surface of the imaging lens is provided on the back surface of the mobile phone 100 (the liquid crystal display unit side is the front surface) and is located at a position corresponding to the lower side of the liquid crystal display unit.

The external connection terminal (not shown) of the imaging device 50 is connected to the control unit 101 of the mobile phone 100 and outputs an image signal such as a luminance signal or a color difference signal to the control unit 101 side.

On the other hand, as shown in FIG. 4, the mobile phone 100 controls each unit in an integrated manner, and also supports a control unit (CPU) 101 that executes a program corresponding to each process, and inputs a number and the like with keys. An input unit 60, a display unit 70 for displaying captured images and videos, a wireless communication unit 80 for realizing various information communications with an external server, a system program and various processing programs for the mobile phone 100, A storage unit (ROM) 91 that stores necessary data such as a terminal ID, and various processing programs and data executed by the control unit 101, processing data, imaging data by the imaging device 50, and the like are temporarily stored. A temporary storage unit (RAM) 92 used as a work area to be stored, a non-volatile storage unit 93 that records captured images and videos, and a non-illustrated my , It is equipped with a speaker or the like.

When the photographer holding the mobile phone 100 points the imaging lens 10 of the imaging device 50 toward the subject, an image signal of a still image or a moving image is captured by the image sensor 51. When the photographer presses the button BT shown in FIG. 3 at a desired photo opportunity, release is performed, and the image signal is taken into the imaging device 50. The image signal input from the imaging device 50 is displayed on the display unit 70 by the control unit 101 or recorded in the nonvolatile storage unit 93, and further externally as video information via the wireless communication unit 80. Will be sent.

A method for manufacturing the imaging lens according to the present embodiment will be described. FIG. 5 is a diagram illustrating a process of manufacturing a lens group that is a component of the imaging lens according to the present embodiment. First, as shown in the sectional view of FIG. 5A, a lens block unit UT in which a plurality of lens blocks B are two-dimensionally arranged is manufactured. Since the first lens block unit UT1 and the second lens block unit UT2 are manufactured in the same process, only the first lens block unit UT1 will be described. For example, a replica method is used for the first lens block unit UT1, and a large number of lens portions B1a and B1c are formed on the lens substrate B1b. Although the number of lens blocks included in the lens block unit is at least two, the lens portions formed on the lens substrate do not need to be provided on both sides, and may be provided on only one side.

And lens group LG which is a component of imaging lens 10 is manufactured using lens block units UT1 and UT2 manufactured by such a method. An example of the subsequent manufacturing process of this lens group LG is shown in FIGS.

The first lens block unit UT1 includes a first lens substrate B1b that is a parallel plate, a plurality of first object-side lens portions B1a formed on one plane thereof, and a plurality of first lenses formed on the other plane. And an image side lens portion B1c. At this time, the first lens substrate B1b and the first object-side lens portion B1a are formed via a diaphragm S (see FIG. 2) formed of an optical thin film. It is preferable to provide the infrared cut filter and the diaphragm on the lens substrate because the number of constituent members can be reduced as compared with the case where it is provided separately. Furthermore, if an antireflection coating is provided on the lens substrate, reflection between the lens portion and the lens substrate can be prevented, and flare and ghost can be reduced. The lens portions B1a and B1c are preferably formed directly on the lens substrate B1b, but may be formed using an adhesive or the like.

The second lens block unit UT2 includes a second lens substrate B2b that is a parallel plate, a plurality of second object-side lens portions B2a formed on one plane thereof, and a plurality of second lenses formed on the other plane. And an image side lens portion B2c. Similarly, if an antireflection coating is provided on the lens substrate, reflection between the lens portion and the lens substrate can be prevented, and flare and ghost can be reduced. In addition, although it is preferable to form lens part B2a and B2c directly on lens board | substrate B2b, what was formed using the adhesive agent etc. may be used.

A plurality of openings are formed, and a spacer SP as an interval defining portion formed of a light shielding material in a lattice shape is interposed between the first lens block unit UT1 and the second lens block unit UT2, and both lenses The interval between the block units UT1 and UT2 is kept constant. In such a state, adjustment is made so that the optical axes of the lens portions B1a, B1c, B2a, and B2c located at the respective openings of the spacer SP are accurately aligned. As means for aligning the optical axes, for example, the lens substrate B1b and B2b, or the lens unit B1a or B1c and B2a or B2c is formed with a position reference mark that is observed as a feature point having different brightness from other parts, The optical axes of the lens block B1 and the lens block B2 can be aligned with high precision by adjusting the position so that they coincide with each other (see Japanese Patent Laid-Open No. 2006-146043).

Here, since the spacer SP is interposed between the first lens block unit UT1 and the second lens block unit UT2, the lens substrates B1b and B2b (the first image side lens unit B1c and the second object side) are arranged. Lens part B2a) is sealed and integrated.

Then, when the first lens substrate B1b and the second lens substrate B2b connected via the spacer SP are cut along the lattice frame (position of the broken line Q) of the spacer SP, as shown in FIG. In addition, a plurality of lens groups LG having a two-lens structure integrated with each lens block are efficiently formed. After that, the lens group LG is arranged at a position on the optical axis where the surface of the imaging lens 10 having the maximum light flux of the on-axis light beam is located in the lens group LG, and combined with the third lens L3. Further, the imaging lens 10 and the optical member F thus formed are held by the housing 20 so as to face the image sensor 51 assembled to the substrate 52, whereby the imaging apparatus shown in FIG. Obtainable.

As described above, when the two lens block units in which the plurality of lens groups LG are formed are separated at the position of the grating and the lens group LG which is a component of the imaging lens 10 is manufactured, each of the imaging lenses 10 Lens interval adjustment and assembly are simplified. Therefore, mass production of imaging devices that are expected to have high image quality is possible.

Moreover, since the spacer SP has a lattice shape, the spacer SP also serves as a mark when the lens groups LG are separated. Therefore, the lens group LG can be easily cut out, and it does not take time and effort. As a result, the lens group LG can be mass-produced at a low cost.

That is, in the manufacturing method of the lens group LG which is a constituent element of the imaging lens 10, the lens block units B1 and B2 each having a plurality of lens blocks each having a lens portion formed on the lens substrate are opened at positions corresponding to the lens portions. The step of adhering via the lattice-shaped interval defining portion in which the portion is formed (see FIG. 5B), and the two lens block units integrated by adhesion and the interval defining portion at the position of the lattice frame And a step of cutting (see FIG. 5C). Such a manufacturing method can reduce the mass production of the lens system. In addition, although the example which adhere | attaches two lens block units through the spacer which is a space | interval definition part was demonstrated, it is not restricted to this, Three or more lens block units are adhere | attached via a space | interval definition part, and You may cut | disconnect in the position of the lattice frame of a space | interval prescription | regulation part.

In addition, the spacer that is the space defining portion is not a separate member, and a functional portion corresponding to the spacer SP may be integrally formed as a space defining portion on at least one of the lens portions B1c and B2a formed on the lens substrate. .

Examples of the imaging lens applied to the above embodiment will be described 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 imaging surface of solid-state imaging device (diagonal length of rectangular effective pixel area of solid-state imaging device)
ENTP: entrance pupil position (distance from the first surface to the entrance pupil)
EXTP: Exit pupil position (distance from image plane to exit pupil)
H1: Front principal point position (distance from the first surface to the front principal point)
H2: Rear principal point position (distance from the final surface to the rear principal point)
R: radius of curvature of refracting surface D: spacing between upper surfaces of axis Nd: refractive index of d-line of lens material at room temperature νd: Abbe number of lens material In each example, the aspherical shape has an apex at the surface as the origin, light The X axis is taken in the axial direction, and the height in the direction perpendicular to the optical axis is h.

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). The surface number of the lens data was given in order with the object side of the first lens as one surface. In addition, the unit of the numerical value showing the length as described in an Example shall be mm.

Example 1
Lens data of the imaging lens of Example 1 is shown in the following (Table 1). Table 2 shows the maximum height (axial beam height) that intersects each lens surface among luminous fluxes (axial luminous flux) imaged on the optical axis in the imaging lens of Example 1.

FIG. 6 is a cross-sectional view of the imaging lens according to the first example. In Example 1, in order from the object side along the optical axis, a first lens block B1 including a first object side lens unit B1a, an aperture stop S, a first lens substrate B1b, and a first image side lens unit B1c; A lens group LG composed of a second lens block B2 composed of a second object side lens unit B2a, a second lens substrate B2b, and a second image side lens unit B2c; a third lens L3 that is a single lens; An optical member F which is a flat plate assuming an optical low-pass filter, an infrared cut filter, a seal glass of a solid-state imaging device, and the like is disposed. IS is an imaging surface of the solid-state imaging device. Further, in Example 1, all the air contact surfaces of the lens portions constituting the lens block have an aspherical shape, and the first lens block B1 and the second lens block B2 are bonded via a spacer SP.

As shown in Table 2 and FIG. 6, the imaging lens of Example 1 has the highest light flux of the axial light beam on the first surface (surface in contact with the air of the lens unit B1a) constituting the lens group LG. ing. That is, the lens surface that has the maximum ray height of the axial light beam of the imaging lens of Example 1 is in the lens group LG configured by the first lens block B1 and the second lens block B2.

FIG. 7 is an aberration diagram (spherical aberration diagram (a), astigmatism diagram (b), distortion diagram (c), meridional coma aberration diagram (d)) of the imaging lens shown in Example 1. In the following 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 image plane.

(Example 2)
Lens data of the imaging lens of Example 2 is shown in the following (Table 3) and (Table 4). Table 5 shows the maximum height (axial beam height) that intersects each lens surface among luminous fluxes (axial luminous flux) imaged on the optical axis in the imaging lens of Example 2.

FIG. 8 is a cross-sectional view of an imaging lens according to Example 2 which is a zoom lens. In Example 2, in order from the object side along the optical axis, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power (including an aperture stop S), and a positive refractive power The third lens group G3, and an optical member F that is a flat plate assuming an optical low-pass filter, an infrared cut filter, a seal glass of a solid-state imaging device, and the like are disposed. IS is an imaging surface of the solid-state imaging device. During zooming from the wide-angle end to the telephoto end, the position of the third lens group G3 on the optical axis is unchanged, and the first lens group G1 moves to the image side as indicated by the arrow A, and then moves to the object side. Then, as the second lens group G2 is indicated by an arrow B, zooming can be performed by gradually moving toward the object side and changing the interval between the lens groups. In addition, the second lens group G2 of Example 2 constitutes a lens group composed of lens blocks B3 and B4. However, the material, manufacturing method, etc. are the same as those of the above-described example except for the shape thereof, and thus the description thereof is omitted. To do.

More specifically, the first lens group G1 includes a negative lens L1 and a positive lens L2, and the second lens group G2 includes a third object side lens unit B3a, a third lens substrate B3b, and a third image side lens unit. A positive third lens block B3 composed of B3c, and a negative fourth lens block B4 composed of a fourth object side lens unit B4a, a fourth lens substrate B4b, and a fourth image side lens unit B4c. The third lens group G3 comprises solely a positive lens L5. All the air contact surfaces of the lens unit of the lens group including the lens blocks B3 and B4 are aspherical, and the third lens block B3 and the fourth lens block B4 are bonded via a spacer SP.

As shown in Table 5 and FIG. 8, the imaging lens of Example 2 has a fifth surface in the lens group consisting of lens blocks B3 and B4 over the entire range from the wide-angle end (Wide) to the telephoto end (Tele). On the surface of the lens portion B3a that is in contact with the air), the beam height of the axial light beam is the highest. That is, the lens surface that has the maximum ray height of the on-axis light beam of the imaging lens of the second embodiment is in the lens group that includes the third lens block B3 and the fourth lens block B4.

9 to 11 are aberration diagrams (spherical aberration diagram (a), astigmatism diagram (b), distortion diagram (c), and meridional coma aberration (d)) of the imaging lens shown in Example 2. FIG. . 9 is an aberration diagram with a focal length of 4.550 mm, FIG. 10 is an aberration diagram with a focal length of 8.640 mm, and FIG. 11 is an aberration diagram with a focal length of 12.423 mm.

(Example 3)
Lens data of the imaging lens of Example 3 is shown in (Table 6) below. Table 7 shows the maximum height (axial beam height) that intersects each lens surface among luminous fluxes (axial luminous flux) imaged on the optical axis in the imaging lens of Example 3.

FIG. 12 is a cross-sectional view of the imaging lens according to the third example. In Example 3, in order from the object side along the optical axis, a first lens block B1 including a first object side lens unit B1a, an aperture stop S, a first lens substrate B1b, and a first image side lens unit B1c; A lens group LG composed of a second lens block B2 composed of a second object side lens portion B2a and a second lens substrate B2b, a third lens L3 that is a single lens, an optical low-pass filter, and an infrared cut filter An optical member F which is a parallel plate assuming a sealing glass of a solid-state imaging device is disposed. IS is an imaging surface of the solid-state imaging device. In Example 3, all air contact surfaces of the lens portions constituting the lens block have an aspherical shape, and the first lens block B1 and the second lens block B2 are bonded via the spacer SP.

As shown in Table 7 and FIG. 12, the imaging lens of Example 3 has the highest ray height of the axial light beam on the first surface (surface in contact with the air of the lens unit B1a) constituting the lens group LG. It has become. That is, the lens surface that has the maximum ray height of the on-axis light beam of the imaging lens of the third embodiment is in the lens group LG configured by the first lens block B1 and the second lens block B2.

FIG. 13 is an aberration diagram (spherical aberration diagram (a), astigmatism diagram (b), distortion diagram (c), meridional coma aberration diagram (d)) of the imaging lens shown in Example 3.

(Table 8) shows the values of the example corresponding to the conditional expression (1). However, Example 2 is a value at a focal length of 8.640 mm where the value of Expression (1) is the largest.

Claims

A lens group in which at least two lens blocks each having a lens portion formed on at least one of an object side surface and an image side surface of a lens substrate that is a parallel plate are integrated via a space defining portion;
An imaging lens having a lens made of a resin material or a glass material,
The imaging lens according to claim 1, wherein a surface having a maximum ray height of the axial light beam of the imaging lens is in the lens group.
The lens group is
Bonding at least two of the lens block units formed with a plurality of the lens blocks via the lattice-shaped spacing defining portion;
The bonded lens block unit and the interval defining portion are manufactured by a manufacturing method having a step of cutting at a position of a lattice frame of the interval defining portion. The imaging lens described in 1.
The parallel decentering sensitivity at 70% image height of the lens group is E, and the maximum decentering sensitivity of 70% image height of each lens block is Emax, and the lens group is opposite to Emax. 3. The imaging lens according to claim 1, wherein the imaging lens includes a lens block having a parallel decentering sensitivity of a symbol and satisfies the following conditional expression.
| E / Emax | <0.5 (1)
However, the parallel decentering sensitivity is a value of ΔM / Δ when the change amount ΔM of the meridional image plane with respect to the decentering amount Δ of the lens in the direction perpendicular to the optical axis of the image pickup lens is 70% image height. Is a height of 70% that is 1/2 of the diagonal length of the rectangular effective pixel region of the solid-state imaging device.
The imaging lens according to any one of claims 1 to 3, further comprising an aperture stop on any lens substrate of the lens block forming the lens group.
The imaging lens according to any one of claims 1 to 4, wherein the lens portion is made of a resin material and the lens substrate is made of a glass material.
The imaging lens according to any one of claims 1 to 5, wherein a surface of the lens portion that contacts air is an aspherical surface.
The imaging lens according to any one of claims 1 to 6, wherein the lens portion is made of an energy curable resin.
The imaging lens according to any one of claims 1 to 7, wherein inorganic fine particles having a length of 30 nanometers or less are dispersed in the resin material.
The imaging lens according to any one of claims 1 to 8, wherein the lens substrate and the lens portion have a lens block formed through a thin film.
The imaging lens according to any one of claims 1 to 9, wherein the lens group includes a lens block in which a lens portion is formed only on one side.
11. The lens block according to claim 1, wherein means for aligning an optical axis is formed on one of the lens portion and the lens substrate, respectively. Imaging lens.
An image pickup apparatus using the image pickup lens according to any one of claims 1 to 11.
Adhering at least two lens block units each having a plurality of lens blocks each having a lens portion formed on at least one of the object side surface and the image side surface of a lens substrate that is a parallel plate through the lattice-shaped spacing defining portion. When,
Cutting the bonded lens block unit and the interval defining portion at a position of a lattice frame of the interval defining portion to obtain a lens group;
And a step of arranging the lens group at a position on the optical axis where a surface having the maximum light flux of the axial light beam of the imaging lens is a position in the lens group. Method.