JP2011175028A - Imaging lens and imaging module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging lens and imaging module that are configured to obtain satisfactory resolution around an image formed by imaging an object. <P>SOLUTION: The position, moved by a distance Pdis in a direction Z parallel to an optical axis La from the position Sa in which resolution is maximum in the center of an image, is used as an image surface S5, and relational expressions (1) and (2) are satisfied. In a single lens L, both of faces S1 and S2 are aspherical. An expression (1): 0.014<Pdis/f<0.035. An expression (2): 0.18<d/d2<0.30. In the expressions, f is the focal length of the entire imaging lens 100, d is the thickness of the center of the single lens L, d2 is an air conversion length from the center s2 of the face S2 to the image surface S5. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imaging lens and an imaging module for the purpose of mounting a portable terminal on a digital camera or the like.

  As the imaging module, various compact digital cameras, digital video units, and the like having a solid-state imaging device built therein have been developed. In particular, portable terminals such as portable information terminals and portable telephones have become widespread. In recent years, camera modules mounted on portable telephones that are popular machines for emerging countries, and imaging modules mounted on sub-cameras of portable terminals. On the other hand, a reduction in price is required by realizing a simple configuration and process technology. In order to satisfy this requirement, there is an increasing demand for an imaging lens configured using one lens.

  Patent Documents 1 and 2 disclose a technique for realizing an excellent resolving power in an imaging lens configured by using a single lens, in the object (subject) side and the image plane (imaging plane) side. An imaging lens is disclosed in which both of the formed surfaces are convex.

  In Patent Document 3, a stop is disposed on the object side of a meniscus lens body having a first surface located on the object side as a concave surface, and the lens body satisfies the following conditions (A) to (C). An imaging lens configured to be satisfactory is disclosed.

(A) Y ′ / fl ≧ 0.6
(B) 0.9 ≧ Dt / Dc ≧ 0.5
(C) 1.0 ≧ Ap ₂ / Am ₂ ≧ 0.9
However,
fl: focal length of the entire lens system Y ': maximum image height (image height 1.0)
Dt: the thickness of the thinnest part in the region including at least one optical surface of the lens Dc: the center thickness of the lens Ap ₂ : the effective radius of the second surface on the image plane side (the maximum radius of the part through which an effective ray passes)
Am ₂ : The maximum radius of the second surface on the image plane side.

  As another technique for realizing a good resolving power using a meniscus lens, an imaging lens disclosed in Patent Document 4 can be cited.

JP 2003-344758 A (released on December 3, 2003) Japanese Patent Laid-Open No. 6-88939 (published March 29, 1994) JP 2003-57538 A (published February 26, 2003) Japanese Patent Laid-Open No. 2002-98885 (released on April 5, 2002)

  The imaging lenses disclosed in Patent Documents 1 and 2 maintain telecentricity by having convex surfaces on both sides and setting optimum conditions for each, thereby correcting distortion well. On the other hand, when the angle of view becomes wider, the resolution around the image formed by forming an object deteriorates, or the F number becomes too large and the image becomes dark. Will occur.

  As disclosed in Patent Documents 1 and 2, an imaging lens composed of a single lens having convex surfaces on both sides can correct distortion satisfactorily, but requires an optical constant equivalent to that of a glass material. It is difficult to align the image plane at the material level. An imaging lens composed of one lens having convex surfaces on both sides has been widely implemented because it is a basic configuration that is easy to correct distortion and is effective for a wide angle of view. As a wide-angle lens that requires a horizontal angle of view of 52 ° or more, it is difficult to secure a desired resolution on the sagittal image plane around the image formed by imaging an object. The problem of difficulty arises.

  The imaging lens disclosed in Patent Document 3 has optimal conditions (A) to (C) set for a meniscus lens having a concave first surface located on the object side. In conditions (A) to (C), it can be said that the optimum conditions are set so that a good resolution can be obtained up to the periphery of an image formed by imaging an object in a compact optical system having a wide angle of view. Absent.

  That is, the condition (A) means that the angle of view is about 30 ° or more, but that the angle of view is about 30 ° or more is a specification value that is essential for the camera module and is good. It is a specification required for an imaging lens rather than a condition for obtaining the imaging lens. The condition (B) is a rule regarding the sag amount of the meniscus lens, and it cannot be said that an imaging lens having a good resolving power can be obtained only by satisfying this. Further, the condition (C) has little relation to the optical characteristics of the imaging lens itself.

  An imaging lens configured with one meniscus lens as disclosed in Patent Documents 3 and 4 forms an image of an object in the same manner as an imaging lens configured with one lens having both convex surfaces. It is difficult to secure a desired resolution around the formed image. Furthermore, the imaging lens composed of one meniscus lens has a problem that a large distortion occurs.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an imaging lens and an imaging that can obtain a good resolving power around an image formed by imaging an object. To provide a module.

  In order to solve the above problems, the imaging lens of the present invention includes an aperture stop and a single lens in order from the object side to the image plane side, and the single lens has a concave surface directed toward the object side. An imaging lens, which is a meniscus lens, is a position moved by a distance Pdis (where 0 <Pdis) in the optical axis direction from a position where the resolving power is maximum at the center of an image formed by imaging an object. And satisfying the relationship of 0.014 <Pdis / f <0.035 and the relationship of 0.18 <d / d2 <0.30. Is characterized in that both the surface facing the object side and the surface facing the image surface side are aspherical surfaces. Where f is the focal length of the entire imaging lens, d is the thickness of the center of the single lens, and d2 is the air equivalent length from the center of the surface toward the image plane to the image plane in the single lens. is there.

  According to the above configuration, the image plane is arranged by moving the distance Pdis in the optical axis direction from the position where the resolving power is maximum at the center of the image formed by imaging the object. With respect to the periphery, the resolution can be improved.

  In addition, when Pdis / f is 0.014 or less, there is a possibility that the resolving power around the image formed by imaging an object may be insufficient. When Pdis / f is 0.035 or more, There is a risk that the resolution will be insufficient. Considering these facts, Pdis / f needs to be more than 0.014 and less than 0.035.

  Further, when d / d2 is 0.18 or less, the single lens becomes too thin, and there is a concern that the productivity of the imaging lens may be lowered due to a limitation of applicable manufacturing processes. When a corner imaging lens is difficult to be realized and is 0.30 or more, distortion and astigmatism increase, and resolution may be degraded. Considering these, d / d2 needs to be more than 0.18 and less than 0.30.

  The imaging lens of the present invention is characterized in that the single lens is configured to satisfy a relationship of 0.5 <d ′ / d <0.9. Here, d ′ is the thickness of the end portion of the effective aperture of the single lens.

  When d ′ / d is 0.5 or less, the single lens becomes too thin, and there is a concern that the productivity of the imaging lens may be reduced due to a limitation of applicable manufacturing processes. In some cases, it becomes difficult to correct the resolving power around the image. Considering these, d ′ / d is preferably more than 0.5 and less than 0.9.

  The imaging lens of the present invention is characterized in that the thickness of the thinnest portion of the effective aperture of the single lens exceeds 150 μm.

  According to said structure, since a single lens does not become thin too much, it becomes possible to implement | achieve the imaging lens excellent in productivity.

  The imaging lens of the present invention is characterized in that the F number is less than 3.

  According to the above configuration, since the F number is less than 3, the amount of received light can be increased, and chromatic aberration is corrected well, so that high resolution can be obtained.

  In the imaging lens of the present invention, the single lens has a refractive index exceeding 1.4 and an Abbe number exceeding 43.

  According to the above configuration, a material having a low refractive index and a high dispersion value optical constant can be applied to a single lens. This allows for inexpensive material selection and application of manufacturing processes that are not constrained by materials.

  In the imaging lens of the present invention, the single lens is made of a thermosetting resin or an ultraviolet curable resin.

  By forming the single lens from a thermosetting resin or a UV (Ultra Violet) curable resin, a plurality of single lenses are molded into a resin in the manufacturing stage of the imaging module of the present invention, which will be described later. A lens array can be manufactured, and further, an imaging lens can be reflow mounted.

  An imaging module according to the present invention includes the imaging lens according to the present invention and a solid-state imaging device that receives an image formed by imaging an object with the imaging lens as light.

  According to said structure, it becomes possible to implement | achieve imaging modules, such as a digital camera, which has a wide angle of view, is compact, and has a further favorable resolving power.

  The imaging module of the present invention is characterized in that the solid-state imaging device is a VGA (Video Graphics Array) class imaging device.

  According to the above configuration, by applying a VGA class imaging device to a solid-state imaging device, an imaging module having a good resolving power can be realized, the number of lenses can be reduced, and manufacturing tolerances can be reduced. Therefore, it is possible to reduce the factors that may cause an imaging module that is easy to manufacture.

  In the imaging module of the present invention, the size of the pixel of the solid-state imaging device is 2.5 μm or less.

  According to said structure, it becomes possible to implement | achieve the imaging module using the resolving power which the imaging lens of this invention has. In addition, by downsizing the solid-state imaging device, it is possible to reduce the size of the imaging lens and thus the imaging module. Therefore, it is possible to realize a more compact imaging module such as a digital camera.

  In addition, the imaging module of the present invention is characterized in that it does not include a mechanism for adjusting the focus position of the imaging lens.

  The imaging lens of the present invention has a feature that a good resolving power can be obtained around an image formed by imaging an object. From this, it is not essential for the imaging module of the present invention to adjust the position of the solid-state imaging device with respect to the best image plane position in the optical axis direction. A mechanism for adjusting the focus position can be omitted. By omitting this mechanism, the imaging module of the present invention can reduce the manufacturing cost.

  In addition, an imaging module of the present invention provides a lens array including a plurality of the single lenses on the same surface and a sensor array including a plurality of the solid-state imaging elements on the same surface. After mounting the sensor array on the lens array so that the image pickup device is arranged to face the image in a one-to-one correspondence, the combination of the single lens and the solid-state image pickup device arranged to face each other is divided and manufactured. It is characterized by being made.

  According to the above configuration, a large number of imaging modules can be manufactured in a short time in a short time, so that the manufacturing cost of the imaging module can be reduced.

  As described above, the imaging lens of the present invention includes the aperture stop and the single lens in order from the object side to the image plane side, and the single lens is an imaging that is a meniscus lens having a concave surface facing the object side. A position of a lens, which is moved by a distance Pdis (where 0 <Pdis) in the optical axis direction from a position where the resolving power is maximum at the center of an image formed by imaging an object, and the image plane And satisfies the relationship of 0.014 <Pdis / f <0.035 and the relationship of 0.18 <d / d2 <0.30, and the single lens is located on the object side. Both the directed surface and the surface directed to the image surface side are aspherical. Where f is the focal length of the entire imaging lens, d is the thickness of the center of the single lens, and d2 is the air equivalent length from the center of the surface toward the image plane to the image plane in the single lens. is there.

  Therefore, the present invention has an effect that a good resolving power can be obtained around an image formed by imaging an object.

It is sectional drawing which shows the structure of the imaging lens which concerns on one embodiment of this invention. It is sectional drawing which shows the structure of the imaging lens which concerns on another embodiment of this invention. It is sectional drawing which shows the structure of the imaging lens which concerns on another embodiment of this invention. It is sectional drawing which shows the structure of the imaging lens which concerns on other embodiment of this invention. It is a graph which shows the defocus MTF (Modulation Transfer Function: Modulation transfer function) of the imaging lens shown in FIG. It is a graph which shows the MTF-spatial frequency characteristic of the imaging lens shown in FIG. 2 is a graph showing MTF-image height characteristics of the imaging lens shown in FIG. 1. 2 is a graph showing characteristics of various aberrations of the imaging lens shown in FIG. 1, where (a) shows astigmatism and (b) shows distortion. 3 is a graph showing defocus MTF of the imaging lens shown in FIG. 2. 3 is a graph showing MTF-spatial frequency characteristics of the imaging lens shown in FIG. 2. 3 is a graph showing MTF-image height characteristics of the imaging lens shown in FIG. 2. 3 is a graph showing characteristics of various aberrations of the imaging lens shown in FIG. 2, (a) showing astigmatism and (b) showing distortion. It is a graph which shows defocus MTF of the imaging lens shown in FIG. It is a graph which shows the MTF-spatial frequency characteristic of the imaging lens shown in FIG. It is a graph which shows the MTF-image height characteristic of the imaging lens shown in FIG. 4 is a graph showing characteristics of various aberrations of the imaging lens shown in FIG. 3, (a) showing astigmatism and (b) showing distortion. 5 is a graph showing defocus MTF of the imaging lens shown in FIG. 4. 5 is a graph showing MTF-spatial frequency characteristics of the imaging lens shown in FIG. 4. 5 is a graph showing MTF-image height characteristics of the imaging lens shown in FIG. 4. 5 is a graph showing characteristics of various aberrations of the imaging lens shown in FIG. 4, (a) showing astigmatism and (b) showing distortion. (A)-(c) is sectional drawing which shows the manufacturing method of the imaging module which concerns on one embodiment of this invention. It is sectional drawing which shows the structure of the imaging module which concerns on one embodiment of this invention. It is sectional drawing which shows the structure of the imaging module which concerns on another embodiment of this invention. It is sectional drawing which shows the structure of the imaging module which concerns on another embodiment of this invention.

  FIG. 1 is a cross-sectional view showing a configuration of an imaging lens 100 according to an embodiment of the present invention.

  FIG. 2 is a cross-sectional view showing a configuration of an imaging lens 200 according to another embodiment of the present invention.

  FIG. 3 is a cross-sectional view showing a configuration of an imaging lens 300 according to still another embodiment of the present invention.

  FIG. 4 is a cross-sectional view showing a configuration of an imaging lens 400 according to another embodiment of the present invention.

  The imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400 each have the following basic configuration.

  In the following description, for convenience of explanation, any one of the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400 will be referred to as “imaging lens 1” for explanation.

[Basic configuration of imaging lens 1]
1 to 4 are views each showing a cross section of the imaging lens 1 in the Y (up and down) direction and the Z (left and right) direction. The Z direction indicates a direction from the object 3 side to the image plane S5 side, and a direction from the image plane S5 side to the object 3 side, and the optical axis La of the imaging lens 1 extends in the Z direction. . The normal line direction with respect to the optical axis La of the imaging lens 1 is a direction that extends in a straight line from a certain optical axis La on the surface composed of the X direction and the Y direction.

  The imaging lens 1 includes an aperture stop 2, a single lens L, and a cover glass CG in order from the object 3 side to the image plane S5 side.

  Specifically, the aperture stop 2 is provided around a surface (lens object side surface) S1 of the single lens L facing the object 3 side. The aperture stop 2 is provided for the purpose of limiting the diameter of the on-axis beam bundle of the incident light in order to allow the light incident on the imaging lens 1 to appropriately pass through the single lens L. Yes.

  The object 3 is an object on which the imaging lens 1 forms an image. In other words, the object 3 is an object to be imaged by the imaging lens 1. 1 to 4, for convenience, the object 3 and the imaging lens 1 are illustrated so as to be very close to each other. However, the interval between the object 3 and the imaging lens 1 is actually about 1200 mm, for example.

  The single lens L is a known meniscus lens having a concave surface S1 facing the object 3 side. Accordingly, in the single lens L, the surface (lens image side surface) S2 facing the image surface S5 side is a convex surface. The single lens L is aspheric on both surfaces S1 and S2.

  The convex surface of the lens indicates a portion where the spherical surface of the lens is bent outward. The concave surface of the lens indicates a portion where the lens is bent hollow, that is, a portion where the lens is bent inward.

  The optical axis La of the imaging lens 1 extends substantially linearly in the Z direction on a line segment connecting the center s1 of the surface S1 of the single lens L and the center s2 of the surface S2 of the single lens L.

  The cover glass CG is provided between the single lens L and the image plane S5. The cover glass CG is for protecting the image surface S5 from physical damage and the like by being coated on the image surface S5. The cover glass CG has a surface (object side surface) S3 directed toward the object 3 side and a surface (image side surface) S4 directed toward the image surface S5 side.

  The image plane S5 is a plane that is perpendicular to the optical axis La of the imaging lens 1 and on which an image is formed. A real image can be observed on a screen (not shown) placed on the image plane S5. In the imaging module including the imaging lens 1, an imaging element is disposed on the image plane S5.

  The distance d is a distance from the center s1 to the center s2, and corresponds to the thickness of the center of the single lens L.

  The distance d2 is a distance (in air) from the center s2 to the image plane S5, and corresponds to an air-converted length from the center s2 of the surface S2 toward the image plane S5 in the single lens L to the image plane S5. is doing. The air equivalent length indicates a length obtained by dividing the geometric length of the medium by the refractive index of the medium.

  The distance d ′ is a distance from the end portion e1 of the effective diameter on the surface S1 of the single lens L to the end portion e2 of the effective diameter on the surface S2 of the single lens L. Alternatively, the distance d ′ is a distance from the end ea of the effective aperture on the surface S1 of the single lens L to the end eb of the effective aperture on the surface S2 of the single lens L. The distance d ′ corresponds to the thickness of the end portion of the effective aperture of the single lens L.

  However, the actual imaging lens 1 is naturally three-dimensional, and as a result, the end e1 or ea corresponds to all edges (for example, the circumference) of the effective diameter in the surface S1, and the end e2 or eb is a surface. This corresponds to all the edges (for example, the circumference) of the effective diameter in S2. In this case, the distance d ′ may be interpreted as the dimension in the Z direction at the thinnest portion in the region including at least one optical surface of the single lens L.

  The distances d, d2, and d ′ are all distances (dimensions) in the Z direction, and their units are mm (millimeters).

  The image plane S5 is formed by a distance Pdis from a position Sa having a maximum resolving power at the center of an image (not shown) formed by imaging the object 3 with the imaging lens 1 in the Z direction, that is, in the direction of the optical axis La. (However, 0 <Pdis).

  That is, at the position Sa, at the image height h0 corresponding to the center of the image, the resolution of the imaging lens 1 is higher than the other image heights, and the resolution of the imaging lens 1 at the image height h0 is other image height. It can be interpreted that the position is higher than the surface position. The image plane S5 of the imaging lens 1 exists at a position shifted from the position Sa by the distance Pdis in the Z direction.

  The distance Pdis is a value that satisfies the following relational expression (1) with the focal length f (details will be described later) of the imaging lens 1 as a whole.

0.014 <Pdis / f <0.035 (1)
The imaging lens 1 has an arrangement in which the image plane S5 is moved from the position Sa by a distance Pdis in the Z direction parallel to the optical axis La. As a result, although the resolving power is reduced at the center of the image formed by imaging the object 3 by the imaging lens 1 as compared with the case where the image plane S5 is set at the position Sa, the image plane is formed around the image. The resolving power can be improved as compared with the case where S5 is set to the position Sa.

  When Pdis / f is 0.014 or less, there is a possibility that the resolving power around the image formed by imaging the object 3 may be insufficient. When Pdis / f is 0.035 or more, the center of the image There is a possibility that the resolving power in the case will be insufficient. Considering these, in order to improve the resolving power around the image without excessively reducing the resolving power at the center of the image, Pdis / f is set to exceed 0.014 and less than 0.035. There is a need.

  The imaging lens 1 is set to a value that satisfies the following relational expression (2) between the distance d and the distance d2.

0.18 <d / d2 <0.30 (2)
When d / d2 is 0.18 or less, the single lens L becomes too thin, and there is a concern that the productivity of the imaging lens 1 may be reduced due to a limitation of applicable manufacturing processes. When the corner imaging lens 1 is difficult to be realized and is 0.30 or more, distortion and astigmatism increase and resolution may be deteriorated. Considering these, d / d2 needs to be more than 0.18 and less than 0.30.

  Further, the imaging lens 1 has a value satisfying the following relational expression (3) between the distance d and the distance d ′ in the single lens L.

0.5 <d ′ / d <0.9 (3)
When d ′ / d is 0.5 or less, the single lens L becomes too thin, and there is a concern that the productivity of the imaging lens 1 may be lowered due to the limitation of applicable manufacturing processes. If this is the case, it is difficult to correct the resolving power around the image. Considering these, d ′ / d is preferably more than 0.5 and less than 0.9.

  Further, in the imaging lens 1, it is preferable that the thickness of the thinnest portion (the distance d ′ in FIGS. 1 to 4) of the effective aperture of the single lens L exceeds 150 μm. Since it does not become too thin, it is possible to realize a product with excellent productivity.

  In FIGS. 1 to 4, for the sake of convenience, only the effective aperture of the single lens L is illustrated, whereas the single lens L may have an edge formed on the outer periphery of the effective aperture. Even in this case, it is preferable that the thickness of the thinnest portion of the effective aperture of the single lens L exceeds 150 μm.

  The F number of the imaging lens 1 is preferably less than 3. The F number of the imaging lens 1 is represented by a value obtained by dividing the equivalent focal length of the imaging lens 1 by the entrance pupil diameter of the imaging lens 1. The imaging lens 1 can increase the amount of received light by setting the F number to less than 3, and the chromatic aberration is corrected well, so that high resolution can be obtained.

  The single lens L preferably has a refractive index with respect to d-line (wavelength: 587.6 nm) exceeding 1.4 and an Abbe number with respect to d-line exceeding 43. The Abbe number is a constant of the optical medium indicating the ratio of the refractive index to the dispersion of light. That is, the Abbe number is the degree to which light of different wavelengths is refracted in different directions, and a medium having a high Abbe number has less dispersion due to the degree of refraction of light rays for different wavelengths. Accordingly, the imaging lens 1 can apply a material having a low refractive index and an optical constant having a high dispersion value to the single lens L. Therefore, the material constituting the single lens L This makes it possible to select inexpensive materials and to apply manufacturing processes that are not limited by materials. A detailed description of the manufacturing process will be described later.

  The material constituting the single lens L is preferably a thermosetting resin or a UV curable resin. The thermosetting resin is a resin having a characteristic that changes its state from a liquid to a solid by applying a predetermined amount of heat or more. The UV curable resin is a resin having a characteristic that changes its state from a liquid to a solid when irradiated with ultraviolet rays having a predetermined intensity or more.

  By configuring the single lens L to be made of a thermosetting resin or a UV curable resin, a plurality of single lenses L can be molded into a resin in a manufacturing stage of the imaging module to produce a lens array described later. In addition, the imaging lens 1 can be reflow mounted.

  However, the single lens L may be a plastic lens or a glass lens.

  The imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400 all have a configuration in which the position moved to the object 3 side from the position Sa by Pdis is the image plane S5. The position moved to the opposite side of the object 3 by Pdis may be the image plane S5.

[MTF and aberration characteristics of imaging lens 100]
FIG. 5 is a graph showing the relationship between the defocus MTF of the imaging lens 100, that is, the MTF (unit: none) shown on the vertical axis and the focus shift position (unit: mm) shown on the horizontal axis. .

  FIG. 6 is a graph showing the relationship between the MTF shown on the vertical axis and the spatial frequency (unit: lp / mm) shown on the horizontal axis of the imaging lens 100.

  FIG. 7 is a graph showing the relationship between the MTF shown on the vertical axis and the image height (unit: mm) shown on the horizontal axis of the imaging lens 100.

  FIG. 8 is a graph showing the characteristics of various aberrations of the imaging lens 100, where (a) shows astigmatism and (b) shows distortion.

  Each of the image heights shown in FIGS. 5 to 7, 9 to 11, 13 to 15, and 17 to 19 is the center of the image formed by imaging the object 3 with the imaging lens 1. The height of the image with reference to is expressed as an absolute value, but it can also be expressed as a percentage of the maximum image height, and the following correspondences between the absolute value and the percentage of the maximum image height, respectively: have.

0.0000 mm = image height h0 (image center)
0.1400 mm = image height h0.2 (height corresponding to 20% of the maximum image height)
0.2800 mm = image height h0.4 (height corresponding to 40% of the maximum image height)
0.4200 mm = image height h0.6 (height corresponding to 60% of the maximum image height)
0.5600 mm = image height h0.8 (height corresponding to 80% of the maximum image height)
0.7000 mm = image height h1.0 (maximum image height)
FIG. 5 and FIG. 9, FIG. 13, and FIG. 17 described later all show image heights h0, h0.2, h0.4, h0.6 when the spatial frequency is “Nyquist frequency / 4”. The characteristics in the tangential image plane (T) and the sagittal image plane (S) for each of h0.8 and h1.0 are illustrated.

  6, and FIGS. 10, 14, and 18, which will be described later, all have image heights h0, h0.2, h0.4, h0... When the spatial frequency is 0 to “Nyquist frequency / 2”. 6 illustrates each characteristic in the tangential image plane (T) and the sagittal image plane (S) for each of 6, h0.8, and h1.0.

  FIG. 7, and FIG. 11, FIG. 15, and FIG. 19 described later all relate to image heights h0 to h1.0 when the spatial frequencies are “Nyquist frequency / 4” and “Nyquist frequency / 2”. Each characteristic in a tangential image surface and a sagittal image surface is illustrated.

Note that the Nyquist frequency is a value corresponding to the Nyquist frequency of a sensor (solid-state imaging device) that is preferably combined with the imaging lens 1, and is resolvable calculated from the pixel pitch of the sensor. The value of the spatial frequency. Specifically, the Nyquist frequency Nyq. (Unit: lp / mm)
Nyq. = 1 / (sensor pixel pitch) / 2
Is calculated by 5 to 20, the sensor is of the VGA class, the size is 1/13 type, the pixel size (pixel pitch) is 1.75 μm, and D (diagonal) ) Is 1.400 mm, H (horizontal) is 1.120 mm, and V (vertical) is 0.840 mm.

  Also, in order to obtain the characteristics shown in FIGS. 5 to 20, it is assumed that the object distance is 500 mm, and the simulation light source (not shown) is based on the following weighting (mixing ratio of each wavelength constituting white) White light), adjusted as follows:

404.66 nm = 0.13
435.84 nm = 0.49
486. 1327 nm = 1.57
546.07 nm = 3.12
587.5618nm = 3.18
656.2725 nm = 1.51
A graph 51 in FIG. 5 shows the relationship of the MTF with respect to the focus shift position of −0.1 mm to 0.1 mm at the image height h0 corresponding to the center of the image formed by imaging the object 3 by the imaging lens 100. Show.

  The graph 51 has the MTF peak value at the focus shift position of 0.025 mm. In other words, the maximum resolution is obtained at the image height h0 at the focus shift position of 0.025 mm. Is shown. The focus shift position of 0.025 mm corresponds to the position Sa shown in FIG.

  On the other hand, the actual image plane S5 (see FIG. 1) of the imaging lens 100 corresponds to a focus shift position of 0 mm. From this, it is clear that the Pdis of the imaging lens 100 is 0.025 mm (see Table 5).

  The imaging lens 100 has a focal length f of 0.853 mm (see Table 5). Therefore, Pdis / f of the imaging lens 100 is 0.029, which satisfies the relational expression (1).

  6 and 7 show the characteristics at the position of the image plane S5 determined based on the graph of FIG.

  As shown in FIG. 6, in the imaging lens 100, the MTF of the sagittal image plane with an image height h1.0 is slightly lower in a high spatial frequency band exceeding 70 lp / mm. 0.0, which has a high MTF characteristic at any image height, and the overall resolving power is the center of an image formed by imaging the object 3 with the imaging lens 100 as compared with the conventional imaging lens. It can be said that it has excellent resolving power from to the periphery.

  As shown in FIG. 7, the imaging lens 100 has a slightly lower MTF with an image height of h0.8 (0.56 mm) or higher with respect to the graph 74 showing the MTF of the sagittal image plane having a spatial frequency corresponding to “Nyquist frequency / 2”. It has become. However, a graph 71 showing the MTF of the tangential image plane having the spatial frequency corresponding to “Nyquist frequency / 4”, a graph 72 showing the MTF of the sagittal image plane having the same spatial frequency, and “Nyquist frequency / 2”. Regarding the graph 73 showing the MTF of the spatial frequency tangential image plane, the image height h0 to h1.0 (0.7 mm) has a high MTF at any image height. Therefore, the imaging lens 100 has an excellent resolving power from the center to the periphery of the image formed by imaging the object 3 by the imaging lens 100 as a total resolving power as compared with the conventional imaging lens. It can be said that.

  According to the graphs shown in FIGS. 8A and 8B, both the tangential image surface (T) and the sagittal image surface (S) have a small residual aberration amount (each aberration with respect to the normal direction with respect to the optical axis La). Therefore, it can be seen that the imaging lens 100 has good optical characteristics.

[MTF and aberration characteristics of imaging lens 200]
FIG. 9 is a graph showing the relationship between the defocus MTF of the imaging lens 200, that is, the MTF shown on the vertical axis, and the focus shift position shown on the horizontal axis, and corresponds to FIG. These characteristics are shown.

  FIG. 10 is a graph showing the relationship between the MTF shown on the vertical axis and the spatial frequency shown on the horizontal axis of the imaging lens 200, and shows the characteristics of the imaging lens 200 corresponding to FIG. It is.

  FIG. 11 is a graph showing the relationship between the MTF shown on the vertical axis and the image height shown on the horizontal axis of the imaging lens 200, and shows the characteristics of the imaging lens 200 corresponding to FIG. It is.

  FIG. 12 is a graph showing the characteristics of various aberrations of the imaging lens 200. FIG. 12A shows astigmatism, FIG. 12B shows distortion, and FIG. 8A and FIG. 8B respectively. Each characteristic of the imaging lens 200 corresponding to the above is shown.

  A graph 91 in FIG. 9 shows the relationship of the MTF with respect to the focus shift position of −0.1 mm to 0.1 mm at the image height h0 corresponding to the center of the image formed by imaging the object 3 with the imaging lens 200. Show.

  The graph 91 has the MTF peak value at the focus shift position of 0.025 mm. In other words, the maximum resolution is obtained at the image height h0 at the focus shift position of 0.025 mm. Is shown. The focus shift position of 0.025 mm corresponds to the position Sa shown in FIG.

  On the other hand, the actual image plane S5 (see FIG. 2) of the imaging lens 200 corresponds to a focus shift position of 0 mm. From this, it is clear that the Pdis of the imaging lens 200 is 0.025 mm (see Table 5).

  The imaging lens 200 has a focal length f of 0.853 mm (see Table 5). Accordingly, Pdis / f of the imaging lens 200 is 0.029, which satisfies the relational expression (1).

  10 and 11 show the characteristics at the position of the image plane S5 determined based on the graph of FIG.

  As shown in FIG. 10, in the imaging lens 200, the MTF of the sagittal image plane with an image height h1.0 is slightly lower in a high spatial frequency band exceeding 70 lp / mm. 0.0, which has a high MTF characteristic at any image height, and the total resolving power is the center of an image formed by imaging the object 3 with the imaging lens 200 as compared with the conventional imaging lens. It can be said that it has excellent resolving power from to the periphery.

  As shown in FIG. 11, the imaging lens 200 has a slightly lower MTF with an image height of h0.8 (0.56 mm) or more with respect to the graph 114 showing the MTF of the sagittal image plane corresponding to “Nyquist frequency / 2”. It has become. However, the graph 111 showing the MTF of the tangential image plane of the spatial frequency corresponding to “Nyquist frequency / 4”, the graph 112 showing the MTF of the sagittal image plane of the same spatial frequency, and “Nyquist frequency / 2”. Regarding the graph 113 showing the MTF of the tangential image plane at the spatial frequency, the image height h0 to h1.0 (0.7 mm) has a high MTF at any image height. Therefore, the imaging lens 200 has an excellent resolving power from the center to the periphery of the image formed by imaging the object 3 by the imaging lens 200 as a total resolving power as compared with the conventional imaging lens. It can be said that.

  According to the graphs shown in FIGS. 12A and 12B, both the tangential image surface (T) and the sagittal image surface (S) have a small residual aberration amount (each aberration with respect to the normal direction with respect to the optical axis La). Therefore, it can be seen that the imaging lens 200 has good optical characteristics.

[MTF and aberration characteristics of imaging lens 300]
FIG. 13 is a graph showing a relationship between the defocus MTF of the imaging lens 300, that is, the MTF shown on the vertical axis, and the focus shift position shown on the horizontal axis, and corresponds to FIG. These characteristics are shown.

  FIG. 14 is a graph showing the relationship between the MTF shown on the vertical axis and the spatial frequency shown on the horizontal axis of the imaging lens 300, and shows the characteristics of the imaging lens 300 corresponding to FIG. It is.

  FIG. 15 is a graph showing the relationship between the MTF shown on the vertical axis and the image height shown on the horizontal axis of the imaging lens 300, and shows the characteristics of the imaging lens 300 corresponding to FIG. It is.

  FIG. 16 is a graph showing characteristics of various aberrations of the imaging lens 300. (a) shows astigmatism, (b) shows distortion, and FIGS. 8 (a) and (b) respectively. Each characteristic of the imaging lens 300 corresponding to the above is shown.

  A graph 131 in FIG. 13 shows the relationship of the MTF with respect to the focus shift position of −0.1 mm to 0.1 mm at the image height h0 corresponding to the center of the image formed by imaging the object 3 by the imaging lens 300. Show.

  The graph 131 has a peak value of MTF at the focus shift position of 0.024 mm. In other words, the maximum resolution is obtained at the image height h0 at the focus shift position of 0.024 mm. Is shown. The focus shift position of 0.024 mm corresponds to the position Sa shown in FIG.

  On the other hand, the actual image plane S5 (see FIG. 3) of the imaging lens 300 corresponds to a focus shift position of 0 mm. From this, it is clear that the Pdis of the imaging lens 300 is 0.024 mm (see Table 5).

  The imaging lens 300 has a focal length f of 0.872 mm (see Table 5). Therefore, Pdis / f of the imaging lens 300 is 0.028, which satisfies the relational expression (1).

  14 and 15 show the characteristics at the position of the image plane S5 determined based on the graph of FIG.

  As shown in FIG. 14, in the imaging lens 300, the MTF of the sagittal image plane with an image height of h1.0 is slightly lower in the high spatial frequency band exceeding 85.74 lp / mm, but the image height h0 is otherwise. It has a high MTF characteristic at any image height of ˜h1.0, and the total resolving power is an image formed by imaging the object 3 with the imaging lens 300 as compared with the conventional imaging lens. It can be said that it has excellent resolution from the center to the periphery.

  As shown in FIG. 15, the imaging lens 300 has a slightly lower MTF with an image height of h0.85 (0.595 mm) or more with respect to a graph 154 showing the MTF of the sagittal image plane having a spatial frequency corresponding to “Nyquist frequency / 2”. It has become. However, a graph 151 showing the MTF of the tangential image plane having the spatial frequency corresponding to “Nyquist frequency / 4”, a graph 152 showing the MTF of the sagittal image plane having the same spatial frequency, and “Nyquist frequency / 2” The graph 153 showing the MTF of the spatial frequency tangential image plane has a high MTF at any image height of image heights h0 to h1.0 (0.7 mm). Therefore, the imaging lens 300 has excellent resolving power from the center to the periphery of the image formed by imaging the object 3 by the imaging lens 300 as a total resolving power as compared with the conventional imaging lens. It can be said that.

  According to the graphs shown in FIGS. 16A and 16B, both the tangential image surface (T) and the sagittal image surface (S) have a small residual aberration amount (each aberration with respect to the normal direction with respect to the optical axis La). Therefore, it can be seen that the imaging lens 300 has good optical characteristics.

[MTF and aberration characteristics of imaging lens 400]
FIG. 17 is a graph showing the relationship between the defocus MTF of the imaging lens 400, that is, the MTF shown on the vertical axis, and the focus shift position shown on the horizontal axis, and corresponds to FIG. These characteristics are shown.

  FIG. 18 is a graph showing the relationship between the MTF shown on the vertical axis and the spatial frequency shown on the horizontal axis of the imaging lens 400, and shows the characteristics of the imaging lens 400 corresponding to FIG. It is.

  FIG. 19 is a graph showing the relationship between the MTF shown on the vertical axis and the image height shown on the horizontal axis of the imaging lens 400, and shows the characteristics of the imaging lens 400 corresponding to FIG. It is.

  FIG. 20 is a graph showing characteristics of various aberrations of the imaging lens 400. FIG. 20A shows astigmatism, FIG. 20B shows distortion, and FIG. 8A and FIG. 8B respectively. Each characteristic of the imaging lens 400 corresponding to the above is shown.

  A graph 171 in FIG. 17 shows the relationship of the MTF with respect to the focus shift position of −0.1 mm to 0.1 mm at the image height h0 corresponding to the center of the image formed by imaging the object 3 by the imaging lens 400. Show.

  The graph 171 has a peak value of MTF at the focus shift position of 0.023 mm. In other words, at the focus shift position of 0.023 mm, the maximum resolving power can be obtained at the image height h0. Is shown. This 0.023 mm focus shift position corresponds to the position Sa shown in FIG.

  On the other hand, the actual image plane S5 (see FIG. 4) of the imaging lens 400 corresponds to a focus shift position of 0 mm. From this, it is clear that the Pdis of the imaging lens 400 is 0.023 mm (see Table 5).

  The imaging lens 400 has a focal length f of 0.891 mm (see Table 5). Therefore, Pdis / f of the imaging lens 400 is 0.026, which satisfies the relational expression (1).

  18 and 19 show the characteristics at the position of the image plane S5 determined based on the graph of FIG.

  As shown in FIG. 18, in the imaging lens 400, the MTF of the sagittal image plane with an image height of h1.0 is slightly lower in the high spatial frequency band exceeding 100 lp / mm, but the image heights h0 to h1 are otherwise. 0.0, which has a high MTF characteristic at any image height, and the total resolving power is the center of the image formed by imaging the object 3 with the imaging lens 400 as compared with the conventional imaging lens. It can be said that it has excellent resolving power from to the periphery.

  As shown in FIG. 19, the imaging lens 400 has a slightly lower MTF with an image height of h0.9 (0.63 mm) or higher with respect to the graph 194 showing the MTF of the sagittal image plane corresponding to “Nyquist frequency / 2”. It has become. However, the graph 191 showing the MTF of the tangential image plane at the spatial frequency corresponding to “Nyquist frequency / 4”, the graph 192 showing the MTF of the sagittal image plane at the same spatial frequency, and “Nyquist frequency / 2”. Regarding the graph 193 showing the MTF of the spatial frequency tangential image plane, the image height h0 to h1.0 (0.7 mm) has a high MTF at any image height. Therefore, the imaging lens 400 has excellent resolving power from the center to the periphery of the image formed by imaging the object 3 by the imaging lens 400 as a total resolving power as compared with the conventional imaging lens. It can be said that.

  20A and 20B, according to the graphs shown in FIGS. 20A and 20B, both the tangential image plane (T) and the sagittal image plane (S) have a small residual aberration amount (each aberration with respect to the normal direction with respect to the optical axis La). Therefore, it can be seen that the imaging lens 400 has good optical characteristics.

  Note that the imaging lens 300 is superior to the imaging lenses 100 and 200 from the viewpoint of realizing an excellent resolving power in the periphery of an image formed by imaging the object 3 by the imaging lens 1. The imaging lens 400 is considered to be superior to the imaging lens 300.

[Characteristic data of each imaging lens 1]
[Table 1] is a table showing design data of the imaging lens 100.

  [Table 2] is a table showing design data of the imaging lens 200.

  [Table 3] is a table showing design data of the imaging lens 300.

  [Table 4] is a table showing design data of the imaging lens 400.

  [Table 5] shows a case where an imaging module is configured by arranging a sensor (solid-state imaging device) on the image plane S5 for each of the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400. It is the table | surface which showed an example of the specification.

  In measuring each data of [Table 1] to [Table 5], the sensor is VGA class, the size is 1/13 type, the pixel size (pixel pitch) is 1.75 μm, and D A (diagonal) size of 1.400 mm, an H (horizontal) size of 1.120 mm, and a V (vertical) size of 0.840 mm was applied.

  In addition, in order to obtain the characteristics shown in [Table 5], it is assumed that the object distance is 500 mm, and as a simulation light source (not shown), the following weighting (the mixing ratio of each wavelength constituting white is White light (adjusted as follows) was used.

404.66 nm = 0.13
435.84 nm = 0.49
486. 1327 nm = 1.57
546.07 nm = 3.12
587.5618nm = 3.18
656.2725 nm = 1.51
In the items “elements” in [Table 1] to [Table 4], the design data relating to the aperture stop 2 is indicated in the line indicated as “aperture”, and the design data relating to the single lens L is indicated in the line indicated as “Lens”. In the row labeled “CG”, the design data related to the cover glass CG is shown, and in the row labeled “sensor”, the design data related to the sensor arranged on the image plane S5 is shown.

  In the items “Materials” of [Table 1] to [Table 4], “Nd” represents the refractive index with respect to the d-line of the single lens L and the cover glass CG, and “νd” represents the single lens L and the cover glass CG. The Abbe numbers with respect to the d-line are respectively shown. As is clear from this item, the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400 all have a refractive index of 1.498 exceeding 1.4, and the single lens L Since the Abbe number is 46 which exceeds 43, it is preferable.

  S1 to S5 in the item “surface” in [Table 1] to [Table 4] correspond to the surface S1, the surface S2, the surface S3, the surface S4, and the image surface S5, respectively, and the designs related to these surfaces. The data is shown on the same line.

  The item “curvature” in [Table 1] to [Table 4] indicates the curvature of the surfaces S1 and S2 of the single lens L.

  The item “center thickness” in [Table 1] to [Table 4] is the optical axis La from the center of the corresponding surface to the center of the next surface toward the image surface S5 (see FIGS. 1 to 4). The direction distance is shown.

  The item “effective radius” in [Table 1] to [Table 4] indicates the radius of the aperture stop 2 and the circular areas of the surfaces S1 and S2 of the single lens L that can regulate the light flux range.

  The item “aspheric coefficient” in [Table 1] to [Table 4] is the i-order aspheric coefficient Ai in the aspheric expression (4) constituting the aspheric surface of each of the surfaces S1 and S2 of the single lens L. (I is an even number of 4 or more). In the aspherical expression (4), Z is a coordinate in the optical axis direction (Z direction in FIG. 1), x is a coordinate in the normal direction (X direction in FIG. 1) with respect to the optical axis, and R is a radius of curvature ( K is a conic coefficient.

  As is clear from the item “Aspheric coefficient” in [Table 1] to [Table 4], the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400 are all on both sides of the single lens L. An aspheric coefficient is given, whereby both surfaces of the single lens L are aspherical. By using the single lens L whose both surfaces are aspherical surfaces, it is preferable in the imaging lens 1 because various aberrations can be easily and satisfactorily corrected.

  As shown in [Table 5], since the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400 all have an F number of 2.80, which is less than 3, high resolution can be obtained. Is.

  In the item “focal length f” of [Table 5], the focal length f of the entire imaging lens 1 is indicated by a unit: mm.

  In the item “view angle” in [Table 5], the view angle of the imaging lens 1, that is, the angle at which an image can be formed by the imaging lens 1, is indicated in units of deg (°), and D (diagonal) , H (horizontal), and V (vertical). The imaging lens 1 has an H (horizontal) angle of view of 52 ° or more, and can be used as a wide-angle lens such as an imaging lens for a portable terminal.

  The item “peripheral light amount ratio” in [Table 5] includes each peripheral light amount ratio (image height h0) of the imaging lens 1 at each of an image height h0.6, an image height h0.8, and an image height h1.0. The ratio of the amount of light to the amount of light). The imaging lens 1 can obtain a high light quantity of 70% or more of the image height h0 at an image height h1.0.

  The item “CRA” in [Table 5] includes each chief ray angle (CRA) of the imaging lens 1 at each of an image height h0.6, an image height h0.8, and an image height h1.0. Is shown.

  The item “optical total length (including CG)” in [Table 5] indicates the distance of the imaging lens 1 from the portion where the aperture stop 2 stops light to the image plane S5. In other words, the optical total length of the imaging lens 1 means the total dimension in the optical axis direction of all the components that have a certain influence on the optical characteristics.

  The item “CG thickness” in [Table 5] indicates the thickness of the cover glass CG in the optical axis direction.

  The item “lens center thickness d” in [Table 5] is the thickness of the center of the single lens L, that is, the distance from the center s1 to the center s2 of the single lens L.

  The item “lens optical effective diameter end thickness d ′” in Table 5 includes the thickness of the end of the effective aperture of the single lens L, that is, the end e1 (ea) to the end e2 (eb of the single lens L). ). In particular, in the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400, the thickness of the thinnest portion of the effective aperture of the single lens L corresponds to this d ′. As is apparent from this item, the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400 have d 'that is the thickness of the thinnest portion of the effective aperture of the single lens L, 0.203 mm, 0.203 mm, 0.205 mm, and 0.203 mm, which are all preferable because they exceed 0.150 mm (that is, 150 μm).

  As is clear from the item “d ′ / d” in Table 5, all of the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400 have d ′ / d exceeding 0.5, And since it is less than 0.9, it is a value which satisfies the above-mentioned relational expression (3).

  As is clear from the item “d / d2” in [Table 5], all of the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400 have d / d2 exceeding 0.18 and 0. Since it is less than .30, the value satisfies the above-described relational expression (2).

  The item “Pdis” in [Table 5] indicates a specific value of Pdis.

  The item “Pdis / f” in [Table 5] shows a specific value of Pdis / f. As described above, the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400 all have a value Pdis / f satisfying the relational expression (1).

[Method of Manufacturing Imaging Module 270]
21A to 21C are cross-sectional views illustrating a method for manufacturing the imaging module 270.

  21A to 21C show an example in which the imaging module 270 is manufactured by a manufacturing process called a wafer level lens process.

  In the wafer level lens process, a lens array 211 is produced by molding or shaping a plurality of single lenses L on the same surface of a molded object such as a resin, and the sensor 218 is further formed on the same surface. Are prepared, and after mounting the sensor array 217 on the lens array 211 so that each single lens L and each sensor 218 are arranged to face each other in a one-to-one correspondence, This is a manufacturing process for manufacturing the imaging module 270 by dividing the combination of the single lens L and the sensor 218 in units of the dividing line 220. According to this manufacturing process, it is possible to manufacture a large number of imaging modules in a short time and in a short time, so that the manufacturing cost of the imaging module can be reduced.

  In recent years, a so-called heat-resistant camera module using a thermosetting resin or a UV curable resin as a material for the single lens L has been developed. The imaging module 270 described here is a kind of this heat-resistant camera module, and a thermosetting resin or a UV curable resin is used as the material of the single lens L.

  The reason for using a thermosetting resin or a UV curable resin as the material of the single lens L is to reduce the manufacturing cost of the imaging module 270 by manufacturing a large number of imaging modules 270 in a short time. Therefore, the reflow can be performed on the imaging module 270 including the imaging lens 1.

  Many techniques for manufacturing the imaging module 270 have been proposed. Among them, typical techniques are injection molding and a wafer level lens process described in detail below. In particular, a wafer level lens (reflowable lens) process, which is considered to be more advantageous in the manufacturing time of an imaging module and other comprehensive knowledge, has recently attracted attention.

  In carrying out the wafer level lens process, it is necessary to suppress the occurrence of plastic deformation in the single lens L due to heat. Because of this need, as a single lens L, a wafer level lens (lens array) using a thermosetting resin material or a UV curable resin material, which is not easily deformed even when heat is applied and has excellent heat resistance. Is attracting attention. Specifically, a wafer level using a thermosetting resin material or a UV curable resin material that has heat resistance that does not cause plastic deformation even when heat of 260 to 280 degrees Celsius is applied for 10 seconds or more. The lens is drawing attention.

  In the wafer level lens process, first, an array mold 212 in which a large number of convex portions having a shape opposite to the surface S1 of the single lens L are formed on the same surface, and a shape opposite to the surface S2 of the single lens L are provided. An array mold lower 213 having a large number of recesses formed on the same surface is prepared. In addition, each convex part on the upper side of the array mold 212 and each concave part on the lower side of the array mold 213 are associated one-to-one, and one convex part and one corresponding concave part. Are arranged opposite to each other.

  A thermosetting resin or UV curable resin is sandwiched between the upper mold 212 and the lower mold 213 and cured by heating, and a single lens is provided for each combination of corresponding convex and concave portions on the same surface. A lens array 211 in which L is molded is produced (see FIG. 21A).

  A sensor array 217 having a large number of sensors 218 formed on the same surface is prepared. The interval between the sensors 218 formed on the sensor array 217 is set to be the same as the interval between the single lenses L formed on the lens array 211.

  For the sensor array 217, as shown in FIG. 21B, a cover glass 216 large enough to cover a plurality of sensors 218 at once may be mounted. Further, as shown in FIG. 21 (b), a spacer 215 for fixing these intervals is provided between the cover glass 216 or the sensor array 217 and the lens array 211 as needed. Also good.

  A sensor array 217 is mounted on the lens array 211. Here, the sensor array 217 is mounted on the lens array 211 via the spacer 215 and the cover glass 216. At this time, the lens array 211 and the sensor array 217 are arranged so that one sensor 218 is opposed to one single lens L with respect to each single lens L and each sensor 218 (FIG. 21B). reference).

  Further, in the step shown in FIG. 21B, a light shielding member (aperture) 214 to be the aperture stop 2 later is mounted around each concave portion that becomes the surface S1 of each single lens L in the lens array 211. The light shielding member (aperture) 214 is provided on the outer peripheral portion of each recess so as to expose each recess in the lens array 211.

  As a method for performing alignment between the lens array 211 and the sensor array 217, there are various methods such as performing alignment while performing imaging, and the alignment is performed depending on the pitch finish accuracy of the wafer. Is also affected.

  Through the process shown in FIG. 21B, a large number of imaging modules 270 arranged in an array are interposed between the single lens L and the sensor 218 that are opposed to each other, and between the single lens L and the sensor 218. The aperture stop 2 (a part of the light shielding member (aperture) 214), the spacer 219 (a part of the spacer 215), and the cover glass CG (a part of the cover glass 216) are combined into a unit. In other words, one imaging module 270 is taken as a unit and divided by the dividing line 220 (see FIG. 21C).

  Through the above steps, one imaging module 270 is completed.

  The manufacturing cost of the imaging module 270 can be reduced by manufacturing a large number of imaging modules 270 in a lump by the wafer level lens process shown in FIGS. Furthermore, in order to avoid the single lens L from being plastically deformed due to heat generated by reflow (maximum temperature is about 260 degrees Celsius) when the completed imaging module 270 is mounted on the substrate, the single lens L is more preferably a thermosetting resin or a UV curable resin having a resistance of 10 seconds or more to heat of 260 to 280 degrees Celsius. Thereby, reflow can be performed on the imaging module 270. By applying a resin material having heat resistance to the manufacturing process at the wafer level, it is possible to manufacture an imaging module that can handle reflow at low cost.

[Configuration 1 of imaging module]
FIG. 22 is a cross-sectional view illustrating a configuration of the imaging module 270. The imaging module 270 is the same as that manufactured by the wafer level lens process shown in FIGS.

  The imaging module 270 includes an aperture stop 2, a single lens L, a spacer 219, a cover glass CG, and a sensor 218. Among these, the aperture stop 2, the single lens L, and the cover glass CG constitute an imaging lens 1 (see FIGS. 1 to 4), and have the same configurations and functions as the imaging lens 1. Therefore, detailed description is omitted.

  The spacer 219 is placed on the cover glass CG, and a single lens L is placed thereon. According to the length of the spacer 219, the distance between the single lens L and the sensor 218 on which the cover glass CG is mounted is It is fixed at a desired interval.

  The sensor (solid-state imaging device) 218 is disposed on the image plane S5 (see FIGS. 1 to 4) of the imaging lens 1 as a component of the imaging module 270, and the object 3 is captured by the imaging lens 1. An image formed by forming an image is received as an optical signal, and the optical signal is converted into an electrical signal. The sensor 218 is configured by a known electronic image sensor or the like.

  Here, it is preferable that the sensor 218 is a VGA class imaging device, whereby the imaging module 270 having a good resolving power can be realized, and the number of lenses can be reduced to one of the single lenses L. Since it is possible to reduce the number of factors that can cause manufacturing tolerances, it is possible to realize an imaging module 270 that is easy to manufacture.

  The sensor 218 preferably has a pixel size (pixel pitch) of 2.5 μm or less, which makes it possible to realize an imaging module 270 that takes advantage of the resolving power of the imaging lens 1. By downsizing the sensor 218, the imaging lens 1 and thus the imaging module 270 can be downsized, so that a more compact imaging module 270 such as a digital camera can be realized.

  The sensor 218 is, for example, the VGA class used to obtain the various characteristics described above, the size is 1/13 type, the pixel size (pixel pitch) is 1.75 μm, and D (diagonal) Preferably, the size is 1.400 mm, the size of H (horizontal) is 1.120 mm, and the size of V (vertical) is 0.840 mm.

  The imaging module 270 does not include a mechanism for adjusting the focus position of the imaging lens 1.

  This is a feasible configuration because the imaging lens 1 has a feature that a good resolving power can be obtained around the image formed by imaging the object 3. That is, the image pickup module 270 does not necessarily adjust the position of the sensor 218 with respect to the best image plane position in the direction of the optical axis La in the image pickup lens 1, and thus has been conventionally required for the adjustment. The mechanism for adjusting the focus position of 1 can be omitted. By omitting this mechanism, the imaging module 270 can reduce the manufacturing cost.

  Further, according to the above configuration, the imaging module 270 does not include the lens barrel and / or the lens holder, so that it is possible to reduce the manufacturing process and the number of components, thereby realizing cost reduction. It becomes.

[Configuration 2 of imaging module]
FIG. 23 is a cross-sectional view illustrating a configuration of an imaging module 280 that is a modification of the imaging module 270.

  The imaging module 280 is different from the imaging module 270 in the following points.

  Unlike the imaging module 270, the imaging module 280 does not use the spacer 219.

  On the other hand, in the imaging module 280, unlike the imaging module 270, a lens edge 231 that protrudes toward the image plane S5 is formed on the single lens L. The lens edge 231 is a region corresponding to the outer peripheral portion of the effective aperture of the single lens L.

  The lens edge 231 protruding to the image surface S5 side is placed on the cover glass CG and is formed integrally with the single lens L, and the single lens L and the cover according to the length of the projection of the lens edge 231. It has the same function as the spacer 219 that fixes the distance between the sensor 218 mounted with the glass CG to a desired distance.

  Other configurations of the imaging module 280 are the same as those of the imaging module 270.

  In the imaging module 280, the spacer 219 is unnecessary, and by using a configuration that does not use the spacer 219, it is possible to further reduce the manufacturing process and the number of components, thereby realizing further cost reduction. .

[Configuration 3 of imaging module]
FIG. 24 is a cross-sectional view illustrating a configuration of an imaging module 290 that is another modified example of the imaging module 270.

  The imaging module 290 is different from the imaging module 270 in the following points.

  Unlike the imaging module 270, the imaging module 290 does not use the spacer 219.

  On the other hand, in the imaging module 290, unlike the imaging module 270, the single lens L is inserted and fixed to the lens barrel 241 placed on the cover glass CG.

  The lens barrel 241 is mounted on the cover glass CG and fixes the inserted single lens L. The distance between the single lens L and the sensor 218 mounted with the cover glass CG is set to a desired distance. It has the same function as the spacer 219 of fixing.

  The aperture stop 2 is formed as a part of the lens barrel 241.

  Other configurations of the imaging module 290 are the same as those of the imaging module 270.

  The imaging module 270, the imaging module 280, and the imaging module 290 are all suitable for use as an imaging module for a digital camera or the like having a wide angle of view, a compact size, and an excellent resolution. .

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The present invention can be used for an imaging lens and an imaging module for the purpose of mounting a portable terminal on a digital camera or the like.

1, 100, 200, 300, and 400 Imaging lens 2 Aperture stop 3 Object 211 Lens array 217 Sensor array 218 Sensor (solid-state imaging device)
270, 280, 290 Imaging module CG Cover glass L Single lens La Optical axis Pdis Distance from the position where the resolving power is maximum at the center of the image to the image plane S5 Position where the resolving power is maximized at the center of the image plane Sa image d ′ Thickness of the end of the effective aperture of the single lens d Thickness of the center of the single lens d2 Air-converted lengths e1, e2, ea, eb from the center of the surface toward the image plane to the image plane in the single lens End f of effective aperture of single lens f Focal length s1 Center of single lens s2 Center of single lens

Claims (11)

In order from the object side to the image surface side, it has an aperture stop and a single lens,
The single lens is an imaging lens that is a meniscus lens having a concave surface facing the object side,
A position moved by a distance Pdis (where 0 <Pdis) in the optical axis direction from a position where the resolving power is maximum at the center of an image formed by imaging an object is the image plane. And,
0.014 <Pdis / f <0.035
(Where f is the focal length of the entire imaging lens)
And the relationship
0.18 <d / d2 <0.30
(However, d: thickness of the center of the single lens, d2: air conversion length from the center of the surface toward the image plane to the image plane in the single lens)
Is satisfied with the relationship
The imaging lens according to claim 1, wherein both the surface directed toward the object side and the surface directed toward the image plane side are aspherical surfaces. The single lens is
0.5 <d ′ / d <0.9
(However, d ': thickness of the end of the effective aperture of the single lens)
The imaging lens according to claim 1, wherein the imaging lens is configured to satisfy the following relationship.   The imaging lens according to claim 1 or 2, wherein the thickness of the thinnest portion of the effective aperture of the single lens exceeds 150 µm.   The imaging lens according to claim 1, wherein the F number is less than 3. 5.   5. The imaging lens according to claim 1, wherein the single lens has a refractive index exceeding 1.4 and an Abbe number exceeding 43. 6.   The imaging lens according to claim 1, wherein the single lens is made of a thermosetting resin or an ultraviolet curable resin. The imaging lens according to any one of claims 1 to 6,
An imaging module comprising: a solid-state imaging device that receives an image formed by imaging an object with the imaging lens as light.   The imaging module according to claim 7, wherein the solid-state imaging device is a VGA class imaging device.   9. The imaging module according to claim 7, wherein a size of a pixel of the solid-state imaging device is 2.5 μm or less.   The imaging module according to any one of claims 7 to 9, wherein a mechanism for adjusting a focus position of the imaging lens is not provided. A lens array including a plurality of the single lenses on the same surface and a sensor array including a plurality of the solid-state imaging elements on the same surface are prepared,
After mounting the sensor array on the lens array so that each single lens and each solid-state imaging element are opposed to each other in a one-to-one relationship,
The imaging module according to any one of claims 7 to 10, wherein the imaging module is manufactured by dividing a combination of the single lens and the solid-state imaging device that are arranged to face each other.

Images