JP2011248319A - Imaging lens and imaging module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an imaging lens and an imaging module which have a desired resolving power and provide the sense of excellent resolution which makes image distortion unnoticeable, with a small number of lenses.SOLUTION: An imaging lens 100 directs incoming light to a light receiver of a sensor 4. The light receiver is quadrilateral and the ratio of the short side length and the long side length is a:b. The imaging lens 100 satisfies the following conditional expressions (1) to (5): 2.0%<distA<5.0% ...(1), 0.5%<distA-distB<1.4% ...(2), distC-distB<0% ...(3), A=a/(a+b)...(4), and B=b/(a+b)...(5)

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. In particular, the present invention relates to an imaging module using a solid-state imaging device and an imaging lens that is convenient for application to the imaging module.

  In recent years, the demand for digital cameras with a low pixel count has increased. The digital camera is mounted on a mobile phone (mobile terminal) for emerging countries, a sub-camera of a mobile phone, a personal computer, or the like.

  The above-mentioned digital camera having a low pixel number is generally low in selling price, and the number of lenses is reduced in order to reduce the manufacturing cost, so that it is difficult to perform sufficient aberration correction.

  In addition, the digital camera mounted for mobile phones requires a wide angle of view, but the digital camera with a wide angle of view increases distortion.

  As a technique for realizing an optical system having a desired resolution and a good resolution that is not easily noticeable with a small number of lenses, the technique disclosed in Patent Document 1 can be cited.

  The imaging optical system according to Patent Document 1 relates to distortion, and is configured to satisfy the following conditional expressions (A) to (C).

2.0% <│DIST6 | <5.0% (A)
│DIST8-DIST6│ <0.5% (B)
│DIST10-DIST8│ <1.8% (C)
However, DIST6 is an optical distortion at an image height of 60%, DIST8 is an optical distortion at an image height of 80%, and DIST10 is an optical distortion at an image height of 100%.

JP 2005-107370 A (published April 21, 2005)

  However, when the imaging optical system according to Patent Document 1 has a wide angle of view, distortion at a position far from the optical axis becomes large, and it is difficult to satisfy the conditional expressions (A) to (C). Problem occurs.

  Further, the imaging optical system according to Patent Document 1 is a case where the conditional expressions (A) to (C) are satisfied, even if the conditional expressions (D) to (F) are further satisfied, or the conditional expression When the conditions (G) to (I) are further satisfied, a distortion having a shape like a Jinkasa is generated, which causes a problem that the distortion becomes conspicuous.

0% <DIST6 (D)
DIST8-DIST6 <0% (E)
0% <DIST10-DIST8 (F)
DIST6 <0% (G)
0% <DIST8-DIST6 (H)
DIST10-DIST8 <0% (I)
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 device that have a desired resolving power with a small number of lenses and that can provide a good resolution with less noticeable distortion. It is to realize a module.

  In order to solve the above-described problem, the imaging lens of the present invention guides incident light to a rectangular light-receiving unit in which the ratio of the short side dimension to the long side dimension is a: b. It is a lens, and conditional expressions (1) to (5)

However,
distA: Distortion at a height corresponding to A of the maximum image height from the center of the image distB: Distortion at a height corresponding to B of the maximum image height from the center of the image distC: At the maximum image height Each of the distortions is adjusted so as to satisfy the distortion.

  According to the above configuration, it is possible to realize an optical system in which distortion is not noticeable even when it is difficult to correct distortion well.

  When distA ≦ 2.0%, it is easy to correct the distortion satisfactorily. Therefore, it is not necessary to apply the configuration according to the present invention.

  When 5.0% ≦ distA, the distortion is too large and the distortion becomes conspicuous.

  In the case of distA−distB ≦ 0.5%, it is easy to correct the distortion satisfactorily. Therefore, it is not necessary to apply the configuration according to the present invention.

  When 1.4% ≦ distA−distB, the distortion is too large and the distortion becomes conspicuous.

  When 0% ≦ distC−distB, a distortion having a shape like Jinkasa occurs, and the distortion becomes conspicuous.

  That is, the inventors of the present application have found the above problems as a result of intensive studies, and satisfy the conditional expressions (1) to (5) in order to overcome these problems. I came up with it.

  From the above, it can be said that the imaging lens of the present invention has a desired resolving power with a small number of lenses, and can provide a good resolution that makes distortion less noticeable.

  In addition, conditional expression (3) allows distC, which is distortion at an image height h1.0, to a relatively large value, so that distortion at a position far from the optical axis is caused by a wide angle of view of the imaging lens. Even if it becomes large, it can be satisfied easily.

  In addition, the imaging lens of the present invention is characterized in that the maximum angle of view exceeds 62 °.

  Although the distortion tends to occur as the angle of view increases, the imaging lens of the present invention is not noticeable even if the distortion occurs due to the optimization of the distortion. Therefore, the imaging lens of the present invention is effective for an imaging lens having a wide angle of view such that the maximum angle of view exceeds 62 °.

  The imaging lens of the present invention includes an aperture stop, a first lens having a positive refractive power, and a second lens in order from the object side to the image plane side. A meniscus lens having a convex surface facing the object side, and the second lens is characterized in that the surface facing the object side has a concave shape.

  According to the above-described configuration, the imaging lens of the present invention that has a desired resolving power with a small number of lenses and can obtain a good resolution that is not easily noticeable is obtained by two lenses, the first lens and the second lens. It can be composed of lenses.

  In the imaging lens of the present invention, the surface facing the image plane side of the second lens has a maximum surface inclination angle with respect to the normal direction of the optical axis in a portion other than the optical axis of the imaging lens itself. It is characterized by being 60 ° or more.

  According to said structure, an imaging lens becomes easy to satisfy conditional expression (3). On the other hand, when the maximum angle of surface inclination with respect to the normal direction of the optical axis is less than 60 °, the imaging lens has a large distC, and it is difficult to satisfy the conditional expression (3). In addition, according to the above configuration, it is possible to easily correct aberrations with respect to the periphery of an image by increasing the surface inclination.

  The imaging lens of the present invention is characterized in that the F number is less than 3.2.

  According to the above configuration, a bright image can be obtained. In the imaging lens of the present invention, the peripheral light amount ratio in the image can be increased by setting the distortion characteristic with respect to the periphery of the image to a negative value.

  Moreover, the imaging module of this invention is equipped with the imaging lens of this invention, and the solid-state image sensor which has the said light-receiving part, It is characterized by the above-mentioned.

  According to the above configuration, since the imaging module of the present invention has the same effect as the imaging lens of the present invention provided therein, an inexpensive digital camera having a good resolving power even with a small number of lenses can be obtained. It can be realized.

  Further, the imaging module of the present invention is characterized in that the number of pixels of the solid-state imaging device exceeds 1 million pixels.

  According to said structure, the imaging module which has favorable resolving power can be obtained by providing the solid-state image sensor suitable for the resolving power of an imaging lens. The imaging module of the present invention preferably includes a 1.3 M (mega) solid-state imaging device.

  In the imaging module of the present invention, the pitch of the pixels of the solid-state imaging device is less than 2.5 μm.

  According to the above configuration, by configuring the sensor using a solid-state imaging device having a pixel pitch of less than 2.5 μm, it is possible to realize an imaging module that sufficiently utilizes the performance of a high-pixel imaging device.

  Further, the imaging module of the present invention includes a lens array including a plurality of lenses on the same plane that are the most image plane side constituting the imaging lens, and a sensor array including a plurality of the solid-state imaging elements on the same plane. Each lens and each solid-state imaging device were joined so as to be opposed to each other in a one-to-one correspondence, and then the lens and the solid-state imaging device, which were arranged to face each other, were divided into units and manufactured. It is characterized by being.

  In the imaging module of the present invention, the imaging lens is composed of a plurality of lenses, and includes a first lens array including a plurality of adjacent lenses constituting the imaging lens on the same surface. And a second lens array including a plurality of the other adjacent lenses on the same surface, each lens included in the first lens array, and each lens included in the second lens array. After bonding so as to be opposed to each other corresponding to the pair 1, it is manufactured by dividing the pair of lenses arranged opposite to each other as a unit.

  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. The imaging module of the present invention realizes an imaging lens with a small number of lenses, so that the cost can be reduced by reducing the number of parts, and the above-described inexpensive manufacturing method can be applied. Can be manufactured. In particular, in the imaging lens according to the present invention, by reducing the number of lenses and reducing the process of attaching the lens array, the imaging module of the present invention also reduces factors that may cause manufacturing errors. Effective cost reduction can be expected.

  The imaging module according to the present invention is characterized in that at least one of the lenses constituting the imaging lens is made of a thermosetting resin or an ultraviolet curable resin.

  According to the above configuration, at least one of the lenses constituting the imaging lens of the present invention is made of a thermosetting resin or a UV (Ultra Violet) curable resin, whereby the imaging module of the present invention. In the manufacturing stage, it is possible to form a lens array by molding a plurality of lenses into a resin, and it is possible to reflow mount the imaging lens.

  According to the above configuration, for the purpose of reducing the mounting cost, a lens made of a thermosetting resin or an ultraviolet curable resin, the imaging lens or imaging module of the present invention that realizes an optical system with a small number of lenses, By applying together, more effective cost reduction becomes possible.

  As described above, the imaging lens of the present invention is an imaging lens that guides incident light to a square-shaped light receiving unit in which the ratio of the short side dimension to the long side dimension is a: b, Each of the distortions is adjusted so as to satisfy the conditional expressions (1) to (5).

  Therefore, the present invention has an effect that a desired resolution can be obtained with a small number of lenses, and a good resolution can be obtained with little distortion conspicuous.

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 one embodiment of this invention. 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 one embodiment of this invention. It is a top view which shows schematic structure of the solid-state image sensor combined with each imaging lens shown in FIGS. 2 is a graph showing MTF (Modulation Transfer Function) -spatial frequency characteristics of the imaging lens shown in FIG. 1. It is a graph which shows defocus MTF of the imaging lens shown in FIG. 2 is a graph showing MTF-image height characteristics of the imaging lens shown in FIG. 1. FIG. 9A is a graph showing image height-distortion characteristics of the imaging lens shown in FIG. 1, and FIG. 9B is an image diagram of a lattice image formed by the imaging lens shown in FIG. 3 is a graph showing MTF-spatial frequency characteristics of the imaging lens shown in FIG. 2. 3 is a graph showing defocus MTF 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. FIG. 13A is a graph showing image height-distortion characteristics of the imaging lens shown in FIG. 2, and FIG. 13B is an image diagram of a lattice image formed by 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 defocus MTF 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. FIG. 17A is a graph showing image height-distortion characteristics of the imaging lens shown in FIG. 3, and FIG. 17B is an image diagram of a lattice image formed by the imaging lens shown in FIG. 5 is a graph showing MTF-spatial frequency characteristics of the imaging lens shown in FIG. 4. 5 is a graph showing defocus MTF 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. FIG. 21A is a graph showing image height-distortion characteristics of the imaging lens shown in FIG. 4, and FIG. 21B is an image diagram of a lattice image formed by the imaging lens shown in FIG. 3 is a table showing design data of the imaging lens shown in FIG. 1. 3 is a table showing design data of the imaging lens shown in FIG. 2. 4 is a table showing design data of the imaging lens shown in FIG. 3. 5 is a table showing design data of the imaging lens shown in FIG. 4. It is the table | surface which showed an example of the specification of the imaging module comprised by arrange | positioning a solid-state image sensor on an image surface with respect to each imaging lens shown in FIGS. 27A to 27D are cross-sectional views illustrating an example of a method for manufacturing an imaging lens and an imaging module according to the present invention. 28A to 28D are cross-sectional views illustrating another example of the method for manufacturing the imaging lens and the imaging module of the present invention.

  Hereinafter, an imaging lens 1 according to an embodiment of the present invention will be described. There are four types of imaging lens 1, imaging lens 100, imaging lens 200, imaging lens 300, and imaging lens 400, depending on the specific design. Hereinafter, the term “imaging lens 1” is a generic term for the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400.

  FIG. 1 is a cross-sectional view illustrating a configuration of the imaging lens 100.

  FIG. 2 is a cross-sectional view showing the configuration of the imaging lens 200.

  FIG. 3 is a cross-sectional view illustrating a configuration of the imaging lens 300.

  FIG. 4 is a cross-sectional view showing the configuration of the imaging lens 400.

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

[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 S7 side, and a direction from the image plane S7 side to the object 3 side. The optical axis La of the imaging lens 1 extends in the Z direction. . The normal line direction of the imaging lens 1 with respect to the optical axis La is a direction extending straight from a certain optical axis La on a surface composed of an X (perpendicular to the paper surface) direction and a Y direction.

  The imaging lens 1 includes an aperture stop 2, a first lens L1, a second lens L2, and a cover glass CG in order from the object 3 side to the image plane S7 side.

  Specifically, the aperture stop 2 is provided around the surface (object side surface) S1 of the first lens L1 facing the object 3 side. The aperture stop 2 limits the diameter of the on-axis beam bundle of the incident light so that the light incident on the imaging lens 1 can appropriately pass through the first lens L1 and the second lens L2. It is provided for the purpose of doing.

  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 as being very close to each other. Actually, however, the distance between the object 3 and the imaging lens 1 is approximately 1000 mm, for example. .

  The first lens L1 is a known meniscus lens having positive refractive power. In the first lens L1, the surface S1 facing the object 3 side corresponds to the convex surface of the meniscus lens, and the surface (image side surface) S2 facing the image surface S7 corresponds to the concave surface of the meniscus lens. In the first lens L1, it is preferable that the surface S1 and the surface S2 have an aspherical shape. This makes it easier to better correct various aberrations that may occur in the imaging lens 1.

  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 convex surface of the lens indicates a portion where the spherical surface of the lens is bent outward.

  Strictly speaking, the aperture stop 2 is provided such that the convex surface S1 of the first lens L1 protrudes closer to the object 3 than the aperture stop 2, but in this way the surface S1. There is no particular limitation on whether or not the lens protrudes from the aperture stop 2 toward the object 3. It is sufficient that the aperture stop 2 has an arrangement relationship such that its representative position is closer to the object 3 than the representative position of the first lens L1.

  The second lens L2 is a lens having a positive or negative refractive power. The second lens L2 has a concave surface S3 facing the object 3 side. The surface S4 is a surface facing the image surface S7 side in the second lens L2. In the second lens L2, it is preferable that at least one of the surface S3 and the surface S4 has an aspherical shape, and this facilitates better correction of various aberrations that may occur in the imaging lens 1.

  The cover glass CG is provided between the second lens L2 and the image plane S7. The cover glass CG is for protecting the image surface S7 from physical damage and the like by being coated on the image surface S7. The cover glass CG has a surface (object side surface) S5 directed to the object 3 side and a surface (image side surface) S6 directed to the image surface S7 side.

  The image plane S7 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 S7.

  In the imaging module including the imaging lens 1, a sensor (solid-state imaging device) 4 is disposed on the image plane S7.

  The sensor 4 is disposed on the image plane S7 in the imaging lens 1, receives an image formed by imaging the object 3 by the imaging lens 1 as an optical signal, and uses the optical signal as an electrical signal. To convert to. The sensor 4 is configured by a known electronic image sensor represented by a solid-state image sensor constituted by a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). ing.

  FIG. 5 shows a cross-section of the sensor 4 facing the object 3 and composed of the Y (up and down) direction and the X (left and right) direction. 5 is the X direction in each of FIGS. 1 to 4, the Y direction in FIG. 5 is the Y direction in each of FIGS. 1 to 4, and the Z direction in FIG. 4 is the same as the Z direction in each figure, and FIG. 5 can be interpreted as a top view of the sensor 4 according to FIGS.

  The imaging lens 1 guides incident light to the light receiving unit 5 of the sensor 4.

  As shown in FIG. 5, in the sensor 4, the light receiving unit 5 has a rectangular shape (rectangular shape), the short side dimension of the rectangle is J times a, and the long side dimension is J times b. It is. Here, a, b, and J are arbitrary positive numbers. Therefore, the ratio of the long side dimension to the short side dimension in the rectangle is b: a. Hereinafter, this ratio b: a is referred to as “aspect ratio”.

  The imaging lens 1 having the basic configuration described above satisfies the following conditional expressions (1) to (5).

However,
distA: Distortion of the imaging lens 1 at a height corresponding to A of the maximum image height from the center of the image distB: Height of the imaging lens 1 corresponding to B of the maximum image height from the center of the image Distortion at distC: Distortion at maximum image height of the imaging lens 1 The imaging lens 1 can realize an optical system in which distortion is not noticeable even when it is difficult to correct distortion well. .

  In the case of distA ≦ 2.0%, the imaging lens can easily correct the distortion satisfactorily. Therefore, it is not necessary to apply the configuration according to the present invention.

  When 5.0% ≦ distA, the imaging lens is too much distortion, and the distortion becomes conspicuous.

  When distA−distB ≦ 0.5%, the imaging lens can easily correct distortion well, and therefore, it is not necessary to apply the configuration according to the present invention.

  When 1.4% ≦ distA−distB, the imaging lens is too much distorted, and the distortion becomes conspicuous.

  When 0% ≦ distC−distB, the imaging lens is distorted in a shape like Jinkasa, and the distortion becomes conspicuous.

  That is, the inventors of the present application have found the respective problems described above as a result of intensive studies, and are characterized by satisfying conditional expressions (1) to (5) in order to overcome these problems. I came up with a composition.

  From the above, it can be said that the imaging lens 1 has a desired resolving power with a small number of lenses, and can obtain a good resolution with less noticeable distortion.

  Conditional expression (3) allows distC, which is a distortion at an image height h1.0, to a relatively large value, and therefore, at a position far from the optical axis La due to the wide angle of view of the imaging lens 1. Even if the distortion becomes large, it can be easily satisfied.

  The imaging lens 1 preferably has a maximum angle of view (maximum value of the angle of view) exceeding 62 °.

  In the imaging lens, distortion is more likely to occur as the angle of view is wider, but the imaging lens 1 becomes inconspicuous even if distortion occurs due to optimization of distortion. For this reason, the imaging lens 1 is effective for an imaging lens having a wide field angle such that the maximum field angle exceeds 62 °.

  The basic configuration of the imaging lens 1 shown in FIGS. 1 to 4 is an imaging lens that has a desired resolution and a good resolution that is not easily noticeable with a small number of lenses. This can be realized by two lenses, two lenses L2.

  Further, in the imaging lens 1, the surface S4 of the second lens L2 facing the image surface S7 side is in the normal direction of the optical axis La, that is, in the X direction, except for the portion above the optical axis La of the imaging lens 1. Alternatively, the maximum angle θ of the surface inclination with respect to the Y direction (the Y direction in FIGS. 1 to 4) is 60 ° or more. 1 to 4, the maximum angle θ is the angle of the end of the surface S4.

  Thereby, the imaging lens 1 can easily satisfy the conditional expression (3). On the other hand, when the maximum angle θ of surface inclination with respect to the normal direction of the optical axis La is less than 60 °, the imaging lens has a large distC, and it is difficult to satisfy the conditional expression (3). In addition, according to the above configuration, it is possible to easily correct aberrations with respect to the periphery of an image by increasing the surface inclination.

  The imaging lens 1 preferably has an F number of less than 3.2. The F number is a kind of quantity indicating the brightness of the optical system. 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.

  Thereby, in the imaging lens 1, the incident light can be imaged and a bright image can be obtained. In the imaging lens 1, the peripheral light amount ratio in the image can be increased by setting the distortion characteristic with respect to the periphery of the image to a negative value.

  In the present embodiment, the light receiving unit 5 is rectangular, but a quadrilateral having a long side and a short side is sufficient, and may be a parallelogram, for example.

  The imaging lens 1 shown in FIGS. 1 to 4 is composed of two lenses (a first lens L1 and a second lens L2), but the imaging lens of the present invention is a single lens. It may be constituted by three or more lenses.

[Optical characteristics of the imaging lens 100]
FIG. 6 is a graph showing the relationship between the MTF (unit: none) 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 defocus MTF of the imaging lens 100, that is, the MTF shown on the vertical axis, and the focus shift position (unit: mm) shown on the horizontal axis.

  FIG. 8 is a graph showing the relationship between the MTF indicated on the vertical axis and the image height (unit: mm) indicated on the horizontal axis of the imaging lens 100.

  FIG. 9A shows the relationship between the image height (unit: ratio, that is, h0 to h1.0) shown on the vertical axis and the distortion (unit:%) shown on the horizontal axis of the imaging lens 100. FIG. 9B is an image diagram of a lattice image formed by the imaging lens 100.

  Note that the image height shown in the present embodiment is the absolute value of the image height based on the center of the image formed by imaging the object 3 by the imaging lens 1 or the ratio to the maximum image height. It is expressed with. When the image height is expressed as a ratio with respect to the maximum image height, the following correspondence relationship is assumed between the absolute value and the ratio.

0.0000 mm = image height h0 (image center)
0.1434 mm = image height h0.1 (a height corresponding to 10% of the maximum image height from the center of the image)
0.2868 mm = image height h0.2 (height corresponding to 20% of the maximum image height from the center of the image)
0.5736 mm = image height h0.4 (the height corresponding to 40% of the maximum image height from the center of the image)
0.8604 mm = image height h0.6 (the height corresponding to 60% of the maximum image height from the center of the image)
1.147 mm = image height h0.8 (a height corresponding to 80% of the maximum image height from the center of the image)
1.434 mm = image height h1.0 (maximum image height)
However, for convenience of measurement of optical characteristics, the image height expressed in mm (absolute value) has an error within 0.001 mm between the image height expressed in the corresponding image height hxxx (ratio). May exist.

  6, and FIGS. 10, 14, and 18 to be described later, all have an image height h 0, an image height h 0.2, an image height h 0. 4, each characteristic of the tangential image plane (T) and the sagittal image plane (S) with respect to each of the image height h0.6, the image height h0.8, and the image height h1.0 is illustrated.

  FIG. 7, and FIG. 11, FIG. 15, and FIG. 19, which will be described later, all have an image height h0, an image height h0.2, an image height h0.4, when the spatial frequency is “Nyquist frequency / 4”. Each characteristic in the tangential image plane (T) and the sagittal image plane (S) is illustrated with respect to each of the image height h0.6, the image height h0.8, and the image height h1.0.

  In FIG. 8, and also in FIGS. 12, 16, and 20 described later, the image height h0 to the image height h1 when the spatial frequency is “Nyquist frequency / 4” and “Nyquist frequency / 2”. .0 illustrates each characteristic in the tangential and sagittal image planes.

  FIG. 9 (a), and FIG. 13 (a), FIG. 17 (a), and FIG. 21 (a), which will be described later, all illustrate distortion characteristics with respect to light having a wavelength of 546.07 nm. .

The Nyquist frequency is a value corresponding to the Nyquist frequency of the sensor 4 and is a resolvable spatial frequency value calculated from the pixel pitch of the sensor 4. Specifically, the Nyquist frequency Nyq. (Unit: lp / mm)
Nyq. = 1 / (pixel pitch of sensor 4) / 2
Is calculated by In measuring each optical characteristic of the imaging lens 1, the sensor 4 is a 1.3M (mega) class, the size is 1/6 type, and the pixel size (pixel pitch) is 1.75 μm. The size of D (diagonal) is 2.869 mm, the size of H (horizontal) is 2.240 mm, and the size of V (vertical) is 1.792 mm.

  Further, in order to obtain each optical characteristic of the imaging lens 1, it is assumed that the object distance is 1000 mm, and the simulation light source (not shown) has the following weighting (the mixing ratio of each wavelength constituting white is as follows: White light) 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
As shown in FIG. 6, the imaging lens 100 has high MTF characteristics of 0.2 or more on both the tangential image surface and the sagittal image surface at any image height from h0 to h1.0. It can be said that it has excellent resolution from the center to the periphery of the image formed by imaging the object 3 with the imaging lens 100.

  As shown in FIG. 7, the imaging lens 100 has a tangential image plane and sagittal at any image height h0 to image height h1.0 on the image plane S7 (see FIG. 1) corresponding to the focus shift position of 0 mm. Both of the image planes have high MTF characteristics of 0.2 or more, and it can be said that the image plane has excellent resolution from the center to the periphery of the image formed by imaging the object 3 with the imaging lens 100.

  As shown in FIG. 8, the imaging lens 100 relates to a graph 81 showing the MTF of the sagittal image plane at the spatial frequency corresponding to “Nyquist frequency / 4” and a graph 82 showing the MTF of the tangential image plane at the same spatial frequency. Any image height of h0 to h1.0 (1.434 mm) has a high MTF characteristic of 0.2 or more. Similarly, the imaging lens 100 has an image height with respect to a graph 83 showing an MTF of a sagittal image plane having a spatial frequency corresponding to “Nyquist frequency / 2” and a graph 84 showing an MTF of a tangential image plane having the same spatial frequency. Any image height from h0 to image height h1.0 (1.434 mm) has a high MTF characteristic of 0.2 or more. Therefore, it can be said that 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.

  In FIG. 9A, when the sensor 4 having the light receiving unit 5 having an aspect ratio of 4: 3 is combined with the imaging lens 100, the imaging lens 100 satisfies the conditional expressions (1) to (3). This is also illustrated.

  Referring to FIG. 9A, the conditional expression (1) means that the distortion distA at the image height h0.6 (image height hA) is in the range of 2.0% to 5.0%. is doing.

  Referring to FIG. 9A, conditional expression (2) shows that the distortion distB at the image height h0.8 (image height hB) is 0.5% to 1.4% smaller than the distortion distA. I mean.

  Referring to FIG. 9A, conditional expression (3) means that the distortion distC at the image height h1.0 is smaller than the distortion distB.

  The image diagram of FIG. 9B shows the distortion of the image obtained by imaging the lattice. That is, FIG. 9B shows what kind of distortion the rectangular grid-like object is imaged by the imaging lens 100 as a whole. In the lattice image shown in FIG. 9B, since the distortion does not look so large visually, it can be said that the imaging lens 100 can obtain a good resolution that makes the distortion less noticeable in actual use.

[Optical characteristics of the imaging lens 200]
FIG. 10 is a graph showing the relationship between the MTF (unit: none) shown on the vertical axis and the spatial frequency (unit: lp / mm) shown on the horizontal axis of the imaging lens 200.

  FIG. 11 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 (unit: mm) shown on the horizontal axis.

  FIG. 12 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 200.

  FIG. 13A shows the relationship between the image height (unit: ratio, that is, h0 to h1.0) shown on the vertical axis and the distortion (unit:%) shown on the horizontal axis of the imaging lens 200. FIG. 13B is an image diagram of a lattice image formed by the imaging lens 200.

  As shown in FIG. 10, the imaging lens 200 has a high MTF characteristic of 0.2 or more on both the tangential image plane and the sagittal image plane at any image height from h0 to h1.0. It can be said that it has excellent resolving power from the center to the periphery of the image formed by imaging the object 3 with the imaging lens 200.

  As shown in FIG. 11, the imaging lens 200 has a tangential image plane and sagittal at any image height h0 to image height h1.0 on the image plane S7 (see FIG. 2) corresponding to the focus shift position of 0 mm. Both of the image planes have high MTF characteristics of 0.2 or more, and it can be said that the image plane has excellent resolution from the center to the periphery of the image formed by imaging the object 3 with the imaging lens 200.

  As shown in FIG. 12, the imaging lens 200 is related to a graph 121 showing the MTF of the sagittal image plane at the spatial frequency corresponding to “Nyquist frequency / 4” and a graph 122 showing the MTF of the tangential image plane at the same spatial frequency. Any image height of h0 to h1.0 (1.434 mm) has a high MTF characteristic of 0.2 or more. Similarly, the imaging lens 200 has an image height with respect to a graph 123 showing the MTF of the sagittal image plane having a spatial frequency corresponding to “Nyquist frequency / 2” and a graph 124 showing the MTF of the tangential image plane having the same spatial frequency. Any image height from h0 to image height h1.0 (1.434 mm) has a high MTF characteristic of 0.2 or more. Therefore, it can be said that 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.

  In FIG. 13A, when the sensor 4 having the light receiving unit 5 having an aspect ratio of 4: 3 is combined with the imaging lens 200 in the same manner as in FIG. The fact that the expressions (1) to (3) are satisfied is also illustrated.

  Referring to FIG. 13A, conditional expression (1) means that the distortion distA at the image height h0.6 (image height hA) is in the range of 2.0% to 5.0%. is doing.

  Referring to FIG. 13A, conditional expression (2) indicates that the distortion distB at the image height h0.8 (image height hB) is 0.5% to 1.4% smaller than the distortion distA. I mean.

  Referring to FIG. 13A, conditional expression (3) means that the distortion distC at the image height h1.0 is smaller than the distortion distB.

  The image diagram of FIG. 13B shows the distortion of the image obtained by imaging the lattice in the same manner as in FIG. 9B. That is, FIG. 13B shows what kind of distortion an object having a rectangular lattice shape is imaged by the imaging lens 200 as a whole. Since the lattice image shown in FIG. 13B does not appear to have a large amount of distortion visually, it can be said that the imaging lens 200 provides a good resolution that makes the distortion hardly noticeable in actual use.

[Optical characteristics of the imaging lens 300]
FIG. 14 is a graph showing the relationship between the MTF (unit: none) shown on the vertical axis and the spatial frequency (unit: lp / mm) shown on the horizontal axis of the imaging lens 300.

  FIG. 15 is a graph showing the relationship between the defocus MTF of the imaging lens 300, that is, the MTF shown on the vertical axis and the focus shift position (unit: mm) shown on the horizontal axis.

  FIG. 16 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 300.

  FIG. 17A shows the relationship between the image height (unit: ratio, that is, h0 to h1.0) shown on the vertical axis and the distortion (unit:%) shown on the horizontal axis of the imaging lens 300. FIG. 17B is an image diagram of a lattice image formed by the imaging lens 300.

  As shown in FIG. 14, the imaging lens 300 has a high MTF characteristic of 0.2 or more for both the tangential image plane and the sagittal image plane at any image height from h0 to h1.0. It can be said that it has excellent resolution from the center to the periphery of the image formed by imaging the object 3 with the imaging lens 300.

  As shown in FIG. 15, the imaging lens 300 has a tangential image plane and a sagittal at any image height h0 to image height h1.0 on the image plane S7 (see FIG. 3) corresponding to the focus shift position of 0 mm. Both of the image planes have high MTF characteristics of 0.2 or more, and it can be said that the image plane has excellent resolution from the center to the periphery of the image formed by imaging the object 3 with the imaging lens 300.

  As shown in FIG. 16, the imaging lens 300 is related to a graph 161 showing the MTF of the sagittal image plane at the spatial frequency corresponding to “Nyquist frequency / 4” and a graph 162 showing the MTF of the tangential image plane at the same spatial frequency. Any image height of h0 to h1.0 (1.434 mm) has a high MTF characteristic of 0.2 or more. Similarly, the imaging lens 300 has an image height with respect to a graph 163 showing an MTF of a sagittal image plane having a spatial frequency corresponding to “Nyquist frequency / 2” and a graph 164 showing an MTF of a tangential image plane having the same spatial frequency. Any image height from h0 to image height h1.0 (1.434 mm) has a high MTF characteristic of 0.2 or more. Therefore, it can be said that the imaging lens 300 has an excellent resolution from the center to the periphery of the image formed by imaging the object 3 by the imaging lens 300.

  In FIG. 17A, when the sensor 4 having the light receiving unit 5 having an aspect ratio of 4: 3 is combined with the imaging lens 300 in the same manner as in FIG. The fact that the expressions (1) to (3) are satisfied is also illustrated.

  Referring to FIG. 17A, the conditional expression (1) means that the distortion distA at the image height h0.6 (image height hA) is in the range of 2.0% to 5.0%. is doing.

  Referring to FIG. 17A, conditional expression (2) indicates that the distortion distB at the image height h0.8 (image height hB) is 0.5% to 1.4% smaller than the distortion distA. I mean.

  Referring to FIG. 17A, the conditional expression (3) means that the distortion distC at the image height h1.0 is smaller than the distortion distB.

  The image diagram of FIG. 17B shows the distortion of the image obtained by imaging the lattice in the same manner as in FIG. 9B. That is, FIG. 17B shows what kind of distortion an object having a rectangular lattice shape is imaged by the imaging lens 300 as a whole. In the lattice image shown in FIG. 17B, since the distortion does not appear to be so large visually, it can be said that the imaging lens 300 can obtain a good resolution that makes the distortion less noticeable in actual use.

[Optical characteristics of the imaging lens 400]
FIG. 18 is a graph showing the relationship between the MTF (unit: none) shown on the vertical axis and the spatial frequency (unit: lp / mm) shown on the horizontal axis of the imaging lens 400.

  FIG. 19 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 (unit: mm) shown on the horizontal axis.

  FIG. 20 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 400.

  FIG. 21A shows the relationship between the image height (unit: ratio, that is, h0 to h1.0) shown on the vertical axis and the distortion (unit:%) shown on the horizontal axis of the imaging lens 400. FIG. 21B is an image diagram of a lattice image formed by the imaging lens 400.

  As shown in FIG. 18, the imaging lens 400 has a high MTF characteristic of 0.2 or more for both the tangential image surface and the sagittal image surface at any image height from h0 to h1.0. It can be said that it has excellent resolving power from the center to the periphery of the image formed by imaging the object 3 with the imaging lens 400.

  As shown in FIG. 19, the imaging lens 400 has a tangential image plane and sagittal at any image height h0 to image height h1.0 on the image plane S7 (see FIG. 4) corresponding to the focus shift position of 0 mm. Both of the image planes have high MTF characteristics of 0.2 or more, and it can be said that the image plane has excellent resolution from the center to the periphery of the image formed by imaging the object 3 with the imaging lens 400.

  As shown in FIG. 20, the imaging lens 400 relates to a graph 201 that shows the MTF of the sagittal image plane at the spatial frequency corresponding to “Nyquist frequency / 4” and a graph 202 that shows the MTF of the tangential image plane at the same spatial frequency. Any image height of h0 to h1.0 (1.434 mm) has a high MTF characteristic of 0.2 or more. Similarly, the imaging lens 400 has any image height from an image height h0 to an image height h1.0 (1.434 mm) with respect to the graph 203 showing the MTF of the sagittal image plane having a spatial frequency corresponding to “Nyquist frequency / 2”. , High MTF characteristics of 0.2 or more.

  Note that the imaging lens 400 has an MTF near an image height h0.9 (1.291 mm) with respect to the graph 204 showing the MTF of the tangential image plane having a spatial frequency corresponding to “Nyquist frequency / 2” shown in FIG. However, there is still a portion where MTF is slightly below 0.2, but MTF that can be regarded as being approximately 0.2 is secured, and MTF is below 0.2 There is almost no degradation of resolution due to.

  Therefore, it can be said that the imaging lens 400 has excellent resolving power from the center to the periphery of the image formed by imaging the object 3 with the imaging lens 400.

  In FIG. 21A, when the sensor 4 having the light receiving unit 5 having an aspect ratio of 4: 3 is combined with the imaging lens 400 in the same manner as in FIG. The fact that the expressions (1) to (3) are satisfied is also illustrated.

  Referring to FIG. 21A, the conditional expression (1) means that the distortion distA at the image height h0.6 (image height hA) is in the range of 2.0% to 5.0%. is doing.

  Referring to FIG. 21A, conditional expression (2) indicates that the distortion distB at the image height h0.8 (image height hB) is 0.5% to 1.4% smaller than the distortion distA. I mean.

  Referring to FIG. 21A, conditional expression (3) means that the distortion distC at the image height h1.0 is smaller than the distortion distB.

  The image diagram of FIG. 21B shows the distortion of the image obtained by imaging the lattice in the same manner as in FIG. 9B. That is, FIG. 21B shows what kind of distortion an object having a rectangular lattice shape is imaged by the imaging lens 400 as a whole. Since the lattice image shown in FIG. 21B does not visually appear to be so large in distortion, it can be said that the imaging lens 400 provides a good resolution that makes distortion hardly noticeable in actual use.

[Design data of each imaging lens 1]
FIG. 22 is a table showing design data of the imaging lens 100.

  FIG. 23 is a table showing design data of the imaging lens 200.

  FIG. 24 is a table showing design data of the imaging lens 300.

  FIG. 25 is a table showing design data of the imaging lens 400.

  FIG. 26 is a table showing an example of the specifications of an imaging module configured by disposing the sensor 4 on the image plane S7 for each of the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400. It is.

  In measuring each data of FIGS. 22 to 25, the sensor 4 is 1.3M class, the size is 1/6 type, and the pixel size ( Pixel pitch) is 1.75 μm, D (diagonal) size is 2.869 mm, H (horizontal) size is 2.240 mm, and V (vertical) size is 1.792 mm. Applied.

  Further, in order to obtain each data of FIG. 26, as shown in FIG. 26, it is assumed that the object distance is 1000 mm using the same sensor 4 as that for measuring each data of FIG. 22 to FIG. As the simulation light source, white light having the following weighting (the mixing ratio of each wavelength constituting white was 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 item “configuration” in FIGS. 22 to 25, the design data related to the first lens L1 is written in the row labeled “L1”, and the design data related to the second lens L2 is written in the row labeled “L2”. The design data related to the cover glass CG is shown in the line labeled “CG”, and the design data related to the sensor 4 arranged on the image plane S7 is shown in the line labeled “sensor”.

  In the column “Nd” in the item “Material” of FIGS. 22 to 25, refraction of the first lens L1, the second lens L2, and the cover glass CG with respect to the d-line (wavelength: 587.6 nm). Shows the rate. In the item “material” of FIGS. 22 to 25, the column denoted by “νd” indicates the Abbe numbers of the first lens L1, the second lens L2, and the cover glass CG with respect to the d-line. 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.

  “S1” to “S7” in the item “surface” in FIGS. 22 to 25 correspond to the surfaces S1 to S6 and the image surface S7, respectively, and the design data relating to these surfaces is shown in the same row. ing. “S1” further corresponds to a position where the aperture stop 2 is provided.

  The item “curvature” in FIGS. 22 to 25 indicates the curvatures of the surfaces S1 to S4, respectively.

  The item “center thickness” in FIGS. 22 to 25 indicates the optical axis La direction from the center of the corresponding surface to the center of the next surface toward the image surface S7 (see the Z direction in FIGS. 1 to 4). Shows the distance.

  The item “effective radius” in FIGS. 22 to 25 indicates the effective radii of the surfaces S1 to S4, that is, the radii of the circular regions in which the range of the luminous flux can be regulated.

  The item “aspheric coefficient” in FIGS. 22 to 25 is the i-th order aspheric coefficient Ai (i is an even number of 4 or more) in the aspheric expression (6) constituting the aspheric surface of each of the surfaces S1 to S4. ). In the aspherical expression (6), 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 FIGS. 22 to 25, in the present embodiment, both the first lens L1 and the second lens L2 are given a certain aspheric coefficient on both surfaces. Thus, the surfaces S1 to S4 are all aspherical. The imaging lens 1 in which both surfaces of the first lens L1 and the second lens L2 are aspherical shapes can easily be corrected more favorably, and can be said to be a preferable configuration.

  The relationship between each item of FIG. 26 and the content shown is as follows.

  The item “F number” indicates the F number of each of the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400.

  In the item “Focal length”, the focal lengths (of the entire lens system) of the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400 are indicated by a unit: mm.

  In the item “Field of view”, the angle of view of each of the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400, that is, the angle that can be imaged by the corresponding imaging lens 1, is expressed in units: deg ( (°), each of which is represented by a three-dimensional parameter such as Diagonal, Horizontal, and Vertical.

  In the item “Optical distortion”, the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 300 shown in FIGS. 9A, 13A, 17A, and 21A, respectively. The distortion (optical distortion) at each of the image height h0.6, the image height h0.8, and the image height h1.0 of each of the imaging lenses 400 is indicated by a specific numerical value (unit:%). .

  In the item “TV distortion”, TV (Television) distortion of the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400, that is, a so-called television distortion value, is shown in units:%.

  The item “Relative illumination” includes an image height h0.6, an image height h0.8, an image height h1... Of the peripheral light amount ratios of the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400. Each peripheral light quantity ratio (the ratio of the light quantity with respect to the light quantity at the image height h0) at 0 is shown in units:%.

  The item “CRA” includes the main components of the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400 at the image height h0.6, the image height h0.8, and the image height h1.0, respectively. The ray angle (Chief Ray Angle: CRA) is shown in units: deg (°).

  The item “Optical length” includes the distance from the aperture stop 2 to the image plane S7 in the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400, that is, the imaging lens 1. The optical total length is shown in unit: mm. 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.

  In the item “CG thickness”, the thickness of the cover glass CG in the optical axis direction in each of the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400 is indicated by a unit: mm.

  In the item “Hyper focal distance”, when focusing is performed so that the farthest point of the depth of field extends to infinity in each of the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400. The hyperfocal distance that is the object distance (distance from the lens to the subject) is shown in units of mm.

  Further, the table of FIG. 26 exemplifies numerical values of a and b constituting the aspect ratio. The table of FIG. 26 shows the numerical values of A and B calculated by substituting the numerical values of a and b into the conditional expressions (4) and (5), respectively. Furthermore, the table of FIG. 26 also shows numerical values of distA, distB, distC, distA-distB, and distC-distB, which are values constituting conditional expressions (1) to (3). In the table of FIG. 26, these numerical values indicate the numerical values in the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400, respectively.

  As shown in FIG. 26, 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 that is less than 3.2, a bright image is obtained. It is

  According to the table of FIG. 26, the item corresponding to the maximum value of the angle of view according to the present invention is the item “Field of view” in any of the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400. "Diagonal" (diagonal). This item is 67.0 ° for the imaging lenses 100 and 200 and 65.0 ° for the imaging lenses 300 and 400. Therefore, the imaging lens 100, the imaging lens 200, the imaging lens 300, and the imaging lens 400 all have a maximum angle of view exceeding 62 °.

[Example 1 of Manufacturing Method of Imaging Lens and Imaging Module of the Present Invention]
From here, an example of the manufacturing method of the imaging lens and imaging module of this invention is demonstrated with reference to Fig.27 (a)-(d).

  The first lens L1 and the second lens L2 are produced mainly by injection molding using a thermoplastic resin 131. In the injection molding using the thermoplastic resin 131, the thermoplastic resin 131 softened by heating is pushed into the mold 132 while applying a predetermined injection pressure (approximately 10 to 3000 kgf / c), so that the thermoplastic resin 131 is molded into the metal mold. The mold 132 is filled (see FIG. 27A). For convenience, FIG. 27A shows only the state when the first lens L1 is molded. Similarly, when the second lens L2 is molded, a person skilled in the art also determines the shape according to the shape of the mold 132. If it is so, shaping | molding can be implemented easily.

  The thermoplastic resin 131 formed with the plurality of first lenses L1 is taken out from the mold 132 and divided for each first lens L1 (see FIG. 27B). Although not shown for convenience, similarly, the thermoplastic resin 131 formed with a plurality of second lenses L2 is taken out from the mold 132 and divided for each second lens L2.

  Each of the divided first lens L1 and second lens L2 is assembled into the lens holder 133 by fitting or press-fitting (see FIG. 27C). In addition, the aperture stop 2 (refer FIG. 1) has shown the example currently formed in the lens holder 133. FIG. The intermediate product before completion of the imaging module 136 shown in FIG. 27C can be used as the imaging lens 1.

  The intermediate product before completion of the imaging module 136 shown in FIG. 27C is fitted into the lens barrel 134 and assembled. Further, after that, the sensor 4 in which the cover glass CG is attached to the light receiving unit 5 on the image plane S7 (see FIGS. 1 to 4) of the imaging lens 1 configured to include the first lens L1 and the second lens L2. Mount. Thus, the imaging module 136 is completed (see FIG. 27D).

  The weighted deflection temperature of the thermoplastic resin 131 used for the first lens L1 and the second lens L2 which are injection molded lenses is about 130 degrees Celsius. For this reason, the thermoplastic resin 131 has insufficient resistance to thermal history (maximum temperature is about 260 degrees Celsius) when performing reflow, which is a technique mainly applied in surface mounting, and thus occurs during reflow. Can't withstand heat.

  Therefore, when mounting the imaging module 136 on the substrate, only the sensor 4 portion is mounted by reflow, while the first lens L1 and the second lens L2 portions are bonded with resin, or the first lens L1 and the second lens. A mounting method in which the mounting portion of L2 is locally heated is employed.

  Note that the cover glass CG is shown as a square in the sensor 4 as being included in the sensor 4. In the imaging module 136, an example in which the cover glass CG is pasted only on the light receiving unit 5 of the sensor 4 is shown.

[Example 2 of Manufacturing Method of Imaging Lens and Imaging Module of the Present Invention]
Subsequently, another example of the manufacturing method of the imaging lens and the imaging module of the present invention will be described with reference to FIGS.

  In recent years, as a material of the first lens (one of the adjacent lenses) L1 and / or the second lens (the lens closest to the image plane constituting the imaging lens, the other of the adjacent lenses) L2, a thermosetting resin or UV is used. A so-called heat-resistant camera module using a curable resin is being developed. The imaging module 148 described here is this heat-resistant camera module. As a material for the first lens L1 and the second lens L2, a thermosetting resin 141 is used instead of the thermoplastic resin 131 (see FIG. 27A). Is used. Instead of the thermosetting resin 141, a UV curable resin may be used.

  The reason why the thermosetting resin 141 or the UV curable resin is used as the material of the first lens L1 and / or the second lens L2 is that a large number of imaging modules 148 are manufactured in a short time and imaged. This is to reduce the manufacturing cost of the module 148. In particular, the reason why the thermosetting resin 141 or the UV curable resin is used as the material of the first lens L1 and the second lens L2 is to enable the reflow of the imaging module 148.

  Many techniques for manufacturing the imaging module 148 have been proposed. Among them, typical techniques are the above-described injection molding and wafer level lens process. 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 first lens L1 and the second lens L2 due to heat. Because of this necessity, as the first lens L1 and the second lens L2, wafers using a thermosetting resin material or a UV curable resin material that are not easily deformed even when heat is applied and that have excellent heat resistance are used. Level lenses (lens arrays) are 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, the thermosetting resin 141 is collectively molded into the first lens array 144 and the second lens array (lens array) 145 by the lens array molding dies 142 and 143, respectively, and then bonded. After mounting the sensor array 147, the image pickup module 148 is manufactured by dividing the image pickup module 148 into one.

  From here, the details of the wafer level lens process will be described.

  In the wafer level lens process, first, a thermosetting resin is formed by a lens array mold 142 having a large number of concave portions and a lens array mold 143 having a large number of convex portions corresponding to the concave portions. 141, and the thermosetting resin 141 is cured by heat generated in the lens array molds 142 and 143, and a lens array is produced in which a lens is molded for each combination of the concave and convex portions corresponding to each other. (See FIG. 28 (a)).

  The lens array manufactured in the process shown in FIG. 28A is a first lens array 144 in which a large number of first lenses L1 are molded on the same surface with a thermosetting resin 141. Although illustration is omitted for the sake of convenience, even when the second lens array 145 in which a large number of second lenses L2 are molded on the same surface with the thermosetting resin 141 is manufactured by a lens array molding die, FIG. What is necessary is just to implement the process similar to 28 (a).

  For the first lens array 144 and the second lens array 145, with respect to each of the first lens L1 and the second lens L2, both the optical axis of the first lens L1 and the corresponding optical axis of the second lens L2 Are joined so as to be positioned on the optical axis La of the imaging lens 1 shown in FIG. 1 (see FIG. 28B). From the viewpoint of mass production of imaging modules (including imaging lenses), the first lens array 144 and the second lens array 145 are a combination of the optical axis of the first lens L1 and the corresponding optical axis of the second lens L2. With respect to each of at least two sets, these two optical axes are bonded to each other so as to be positioned on the optical axis La.

  However, specifically, as an alignment method for performing alignment between the first lens array 144 and the second lens array 145, the optical axes of the first lens L1 and the second lens L2 are optical axes. In addition to aligning on La, there are various methods such as aligning while imaging, and the alignment is also affected by the pitch finish accuracy of the wafer.

  A large number of sensors such that each optical axis La and the center 4c of each corresponding sensor 4 overlap each other in which the first lens array 144 and the second lens array 145 are joined as shown in FIG. A sensor array 147 on which 4 is integrally mounted is mounted (see FIG. 28C). Each sensor 4 is disposed on an image plane S7 (see FIGS. 1 to 4) of each corresponding imaging lens 1, and a cover glass CG is attached to the light receiving unit 5.

  At this time, the aperture stop 2 (see FIG. 1) is attached so as to expose the portions corresponding to the surface S1 (see FIG. 1) of each first lens L1, which are the convex portions in the first lens array 144. . However, the timing of attaching the aperture stop 2 and the mounting method are not particularly limited.

  By the process shown in FIG. 28 (c), a large number of imaging modules 148 in the form of an array are taken as a unit of a combination of the optical axis of the first lens L1 and the corresponding optical axis of the second lens L2. That is, in other words, the image pickup module 148 is completed by dividing the image pickup module 148 into units (at least one image pickup module 148 as a unit) (see FIG. 28D).

  Note that the cover glass CG is shown as a square in the sensor 4 as being included in the sensor 4. In the imaging module 148, an example in which the cover glass CG is pasted only on the light receiving unit 5 of the sensor 4 is shown.

  If the step of mounting each sensor 4 (sensor array 147) shown in FIG. 28C is omitted and only the cover glass CG is mounted, and the image sensor is omitted from the image pickup module 148, a wafer level lens can be obtained. The imaging lens 1 can be easily manufactured by the process.

  However, the timing for attaching the cover glass CG and the attaching method are not particularly limited. As described above, the form in which the cover glass CG is provided on the imaging lens 1 or the imaging module 148 may be the form shown in FIG. 1 or the like, or the form shown in FIGS. 27D and 28D. either will do.

  As described above, the manufacturing cost of the imaging module 148 can be reduced by collectively manufacturing a large number of imaging modules 148 by the wafer level lens process shown in FIGS. Furthermore, when the completed imaging module 148 is mounted on the substrate, the first lens L1 and the first lens L1 are arranged in order to avoid plastic deformation due to heat generated by reflow (maximum temperature is about 260 degrees Celsius). It is more preferable to use a thermosetting resin or a UV curable resin that has a resistance of 10 seconds or more to heat of 260 to 280 degrees Celsius for the two lenses L2. Thereby, reflow can be performed on the imaging module 148. 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.

  The imaging module 148 can be interpreted as a configuration including the imaging lens 1 and the sensor 4 having the light receiving unit 5.

  Since the imaging module 148 has the same effect as the imaging lens 1 provided in itself, it is possible to realize an inexpensive digital camera having a good resolving power even when the number of lenses is as small as two, for example. .

  In the imaging module 148, the number of pixels of the sensor 4 preferably exceeds 1 million pixels.

  By providing the sensor 4 suitable for the resolving power of the imaging lens 1, an imaging module 148 having a good resolving power can be obtained. The imaging module 148 preferably includes a 1.3M class sensor 4.

  The imaging module 148 preferably has a pixel pitch of the sensor 4 of less than 2.5 μm.

  By configuring the sensor 4 using a solid-state imaging device having a pixel pitch of less than 2.5 μm, it is possible to realize an imaging module 148 that fully utilizes the performance of a high-pixel imaging device.

  By the wafer level lens process shown in FIGS. 28A to 28D, the imaging module 148 has the second lens array 145 including a plurality of second lenses L2 on the same surface, and the sensor 4 on the same surface. A plurality of sensor arrays 147 are prepared, and the sensor array 147 is mounted on the second lens array 145 so that each second lens L2 and each sensor 4 are arranged to face each other in a one-to-one relationship. After that, it can be interpreted that it is manufactured by dividing the combination of the second lens L2 and the sensor 4 that are arranged to face each other as a unit.

  By the wafer level lens process shown in FIGS. 28A to 28D, the imaging module 148 has the second lens on the same plane as the first lens array 144 having a plurality of first lenses L1. A second lens array 145 having a plurality of lenses L2, and the first lens array 144 is arranged so that the first lenses L1 and the second lenses L2 face each other in a one-to-one correspondence. After the second lens array 145 is bonded to the first lens array 145, it can be interpreted that the first lens L1 and the second lens L2 that are arranged to face each other are divided and manufactured as a unit.

  According to the above configuration, a large number of imaging modules 148 can be manufactured in a short time, and thus the manufacturing cost of the imaging module 148 can be reduced. By realizing the imaging lens 1 with a small number of lenses, the imaging module 148 can reduce the cost by reducing the number of parts, and can apply the above-described inexpensive manufacturing method. Can be manufactured. In particular, by reducing the number of lenses in the imaging lens 1 and reducing the process of attaching the lens array, the imaging module 148 also reduces factors that may cause manufacturing errors, and thus more effective cost reduction. Can be expected.

  In the imaging module 148, at least one of the lenses constituting the imaging lens 1 is preferably made of a thermosetting resin or a UV curable resin.

  In the manufacturing stage of the imaging module 148 shown in FIGS. 28A to 28D, at least one of the lenses constituting the imaging lens 1 is made of a thermosetting resin or a UV curable resin. A lens array can be manufactured by molding a plurality of lenses into a resin, and the imaging lens 1 can be reflow mounted.

  According to the above configuration, for the purpose of reducing the mounting cost, a lens made of a thermosetting resin or an ultraviolet curable resin, the imaging lens or imaging module of the present invention that realizes an optical system with a small number of lenses, By applying together, more effective cost reduction becomes possible.

  Moreover, the portable information device provided with the imaging module 148 has the same effects as the provided imaging module of the present invention and by extension, the imaging lens of the present invention. Examples of such portable information devices include various portable terminals such as information portable terminals and cellular phones.

  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 is applicable to an imaging lens and an imaging module for the purpose of mounting a portable terminal on a digital camera or the like. In particular, the present invention can be used for an imaging module using a solid-state imaging device and an imaging lens convenient for application to the imaging module.

1, 100, 200, 300, and 400 Imaging lens 2 Aperture stop 3 Object 4 Sensor (solid-state imaging device)
5 Light Receiving Unit 141 Thermosetting Resin 144 First Lens Array 145 Second Lens Array (Lens Array)
147 Sensor arrays 136 and 148 Imaging module L1 First lens (one of adjacent lenses)
L2 second lens (the most image side lens constituting the imaging lens, the other of the adjacent lenses)
S1 Surface of the first lens facing the object side S2 Surface of the first lens facing the image surface S3 Surface of the second lens facing the object side S4 Surface of the second lens facing the image surface S7 Image surface La optical axis

Claims (11)

An imaging lens that guides incident light to a square-shaped light receiving unit having a ratio of a short side dimension to a long side dimension of a: b,
Conditional expressions (1) to (5)

However,
distA: Distortion at a height corresponding to A of the maximum image height from the center of the image distB: Distortion at a height corresponding to B of the maximum image height from the center of the image distC: At the maximum image height An imaging lens, wherein each of the distortions is adjusted so as to satisfy the distortion.   The imaging lens according to claim 1, wherein the maximum value of the angle of view exceeds 62 °. In order from the object side to the image surface side, an aperture stop, a first lens having a positive refractive power, and a second lens are provided,
The first lens is a meniscus lens having a convex surface facing the object side,
The imaging lens according to claim 1, wherein the second lens has a concave surface directed toward the object side.   The surface facing the image plane side of the second lens is characterized in that the maximum angle of surface inclination with respect to the normal direction of the optical axis is 60 ° or more in a portion other than the optical axis of the imaging lens itself. The imaging lens according to claim 3.   The imaging lens according to claim 1, wherein the F number is less than 3.2.   An imaging module comprising: the imaging lens according to any one of claims 1 to 5; and a solid-state imaging device having the light receiving unit.   The imaging module according to claim 6, wherein the number of pixels of the solid-state imaging device exceeds 1 million pixels.   The imaging module according to claim 6 or 7, wherein the pixel pitch of the solid-state imaging device is less than 2.5 µm. Each lens and each solid-state imaging device includes: a lens array including a plurality of lenses on the same surface that constitute the imaging lens; and a sensor array including a plurality of the solid-state imaging devices on the same surface. After joining so as to face each other in a one-to-one relationship,
The imaging module according to any one of claims 6 to 8, wherein the imaging module is manufactured by dividing the pair of the lens and the solid-state imaging device that are arranged to face each other as a unit. The imaging lens is composed of a plurality of lenses,
A first lens array that includes a plurality of adjacent lenses on the same surface and a second lens array that includes a plurality of the other adjacent lenses on the same surface, which form the imaging lens. After bonding each lens included in the lens array and each lens included in the second lens array so as to face each other in a one-to-one correspondence,
10. The imaging module according to claim 6, wherein the imaging module is manufactured by dividing the pair of lenses arranged opposite to each other as a unit.   The imaging module according to any one of claims 6 to 9, wherein at least one of the lenses constituting the imaging lens is made of a thermosetting resin or an ultraviolet curable resin.

Images