CN101344633B - Imaging lens, camera module and portable terminal equipment - Google Patents
Imaging lens, camera module and portable terminal equipment Download PDFInfo
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Abstract
The invention provides a camera lens of which overall length can be shortened and chromatic aberration can be lowered, and a camera module which carries this camera lens and can obtain a camera signal of high resolution and a portable terminal device. The camera lens (20) is composed of an aperture diaphragm (St), a real lens portion (a refractive lens system portion formed of a first lens (G1) and a second lens (G2)), and a diffractive optical element (GC) orderly from the object side. At least one face of the diffractive optical element (GC) is a plane of which is set with a diffractive structure. The diffractive optical element (GC) has a function of compensating the chromatic aberration generated by the first lens (G1) and the second lens (G2) of the real lens portion.
Description
Technical Field
The present invention relates to an imaging lens for forming an optical image of a subject on an imaging device such as a ccd (charge coupled device) or a cmos (complementary Metal Oxide semiconductor), a camera module for converting an optical image formed by the imaging lens into an imaging signal, and a mobile terminal device such as a mobile phone with a camera and a Personal Digital Assistant (PDA) which is equipped with the imaging lens and performs imaging.
Background
In recent years, image pickup devices such as CCDs and CMOSs have been abnormally miniaturized and have high pixel count. Therefore, the imaging apparatus main body and the lens mounted therein are also required to be small and high in performance. Under such circumstances, in recent years, imaging lenses having a very small number of lenses, such as 2 lenses or 3 lenses, have been developed for miniaturization. For example, patent document 1 discloses an imaging lens having a 2-piece structure, which is reduced in size and improved in performance by effectively using an aspherical surface.
[ patent document 1 ] patent No. 3685486
However, there is a problem that it is difficult to shorten the total length of the lens system and to correct chromatic aberration with a small number of lenses. For example, in the case of an imaging lens having a 2-piece structure, it is conceivable to dispose a positive lens and a negative lens in this order from the object side and use a high dispersion material for the negative lens to correct chromatic aberration.
Disclosure of Invention
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 capable of reducing chromatic aberration while shortening the overall length, and a camera module and a mobile terminal device which are capable of obtaining an imaging signal with high resolution by mounting the imaging lens.
An imaging lens according to the present invention includes, in order from an object side: a diaphragm; a 1 st lens formed by a positive lens having a convex surface facing the image side; a 2 nd lens formed of a meniscus lens; the diffraction optical element has at least 1 plane and a diffraction structure in at least 1 plane, and satisfies the following conditional expression, where flash represents a focal length of the diffraction optical element, and fall represents a focal length of the entire lens.
5.0＜flast/fall＜6.0 ……(1)
In the imaging lens of the present invention, since the diffractive optical element is provided on the most image side, the diffractive optical element can have a function of correcting chromatic aberration generated in the actual lens portions (the 1 st lens and the 2 nd lens). Even if the chromatic aberration is not sufficiently corrected in the actual lens portion, the chromatic aberration can be corrected. Thus, the actual lens portion can be designed to be reduced in total length without increasing the number of actual lenses as an imaging lens, and not only can the total length be reduced but also chromatic aberration can be reduced as a whole.
Further, since the diffractive structure of the diffractive optical element is provided on a plane, it is possible to suppress deterioration in performance due to manufacturing errors to a small extent, and to achieve excellent manufacturing adaptability.
According to the imaging lens of the present invention, the following conditional expression is more preferably satisfied. In the formula, vd1 represents the abbe number of the 1 st lens with respect to the d-line, f1 represents the focal length of the 1 st lens, and Dlast represents the distance between the image-side surface of the diffractive optical element and the image plane. Satisfying these requirements further contributes to shortening the entire length and reducing chromatic aberration.
v d1＞45 ……(2)
0.6＜f1/fall＜1.0 ……(3)
0.3mm＜Dlast ……(4)
In the imaging lens according to the present invention, it is preferable that the diffractive optical element has a plane on the image side and a diffractive structure on the plane on the image side. Preferably, for example, the substrate is a parallel plane plate and has a diffractive structure in a plane on the image side. By providing the diffraction structure on the image-side plane, the diffraction structure is simplified and is advantageous for aberration correction.
When the diffractive optical element is a parallel plane plate, an infrared cut filter coating film may be formed on the object-side plane of the diffractive optical element. This makes it possible to make 1 optical component have a plurality of optical functions, which is advantageous in reducing the number of components.
Further, an image pickup lens according to the present invention includes, in order from an object side: a diaphragm; a 1 st lens formed of a positive lens; a 2 nd lens formed of a meniscus lens; the diffractive optical element has a plane image-side surface and a diffractive structure on the image-side surface, and satisfies the following conditional expressions, where f1 represents a focal length of the 1 st lens and fall represents a focal length of the entire lens. SYL denotes a distance (mm) on the optical axis from the object-side surface of the 1 st lens to the diffraction surface of the diffractive optical element.
0.6＜f1/fall＜1.0 ……(3)
2.0＜SYL＜4.2 ……(5)
The camera module according to the present invention includes the imaging lens of the present invention, and an imaging element that outputs an imaging signal corresponding to an optical image formed by the imaging lens.
In the camera module according to the present invention, an image pickup signal of high resolution can be obtained based on the optical image of high resolution with chromatic aberration reduced by the image pickup lens of the present invention. Further, the diffractive optical element on the imaging lens side can be used as a protective glass for the imaging element, which is advantageous in reducing the number of components. Further, since the overall length of the imaging lens of the present invention can be reduced, the camera module combined with the imaging lens can be reduced in size as a whole.
Here, the camera module of the present invention may further include a sealing member for sealing between the surface of the diffractive optical element and the imaging surface of the imaging element. This protects the imaging surface and prevents adhesion of dust and the like. In addition, if the imaging surface of the diffractive optical element is a diffraction surface, the diffraction surface is also protected and adhesion of dust and the like can be prevented.
The mobile terminal device of the present invention includes the camera module according to the present invention.
In the mobile terminal device of the present invention, a high-resolution image pickup signal can be obtained based on the high-resolution optical image obtained by the camera module of the present invention, and a high-resolution image pickup image can be obtained based on the image pickup signal.
According to the imaging lens of the present invention, the actual lens portion is formed of 2 pieces of the 1 st lens and the 2 nd lens, and the diffractive optical element is disposed closest to the image side, so that the diffractive optical element can have a function of correcting chromatic aberration generated in the actual lens portion, and the actual lens portion can be designed to be focused on shortening the total length without increasing the number of actual lens pieces as the imaging lens. This can reduce the total length and the color difference as a whole.
Further, according to the camera module of the present invention, since the image pickup signal corresponding to the optical image formed by the high-performance image pickup lens with reduced chromatic aberration is output while the overall length of the camera module is shortened as described above, it is possible to achieve downsizing of the module as a whole and to obtain an image pickup signal with high resolution particularly with reduced chromatic aberration.
Further, according to the mobile terminal device of the present invention, since the camera module of the present invention is mounted, it is possible to obtain an image pickup signal with high resolution, particularly with reduced chromatic aberration, while downsizing the camera portion, and to obtain an image pickup image with high resolution based on the image pickup signal.
Drawings
Fig. 1 is a view showing a 1 st configuration example of an imaging lens according to an embodiment of the present invention, and is a lens cross-sectional view corresponding to example 1.
Fig. 2 is a view showing a 2 nd configuration example of an imaging lens according to an embodiment of the present invention, and is a lens cross-sectional view corresponding to example 2.
Fig. 3 is a view showing a 3 rd configuration example of an imaging lens according to an embodiment of the present invention, and is a lens cross-sectional view corresponding to example 3.
Fig. 4 is a perspective view showing an example of a configuration of a camera module according to an embodiment of the present invention.
Fig. 5 is a cross-sectional view showing an example of the configuration of an imaging device of a camera module according to an embodiment of the present invention.
Fig. 6 is a perspective view showing an example of a configuration of a mobile terminal device according to an embodiment of the present invention.
Fig. 7 is a diagram showing lens data of the imaging lens according to example 1, where (a) shows basic lens data, (B) shows data on an aspherical surface, and (C) shows data on a diffraction surface.
Fig. 8 is a diagram showing lens data of the imaging lens according to example 2, where (a) shows basic lens data, (B) shows data on an aspherical surface, and (C) shows data on a diffraction surface.
Fig. 9 is a diagram showing lens data of the imaging lens according to example 3, where (a) shows basic lens data, (B) shows data on an aspherical surface, and (C) shows data on a diffraction surface.
Fig. 10 is a diagram showing the values of the conditional expressions in an integrated manner in each example.
Fig. 11 is an aberration diagram showing aberrations of the imaging lens according to example 1, where (a) shows spherical aberration, (B) shows astigmatism, and (C) shows distortion.
Fig. 12 is an aberration diagram showing aberrations of the imaging lens according to example 2, where (a) shows spherical aberration, (B) shows astigmatism, and (C) shows distortion.
Fig. 13 is an aberration diagram showing aberrations of the imaging lens according to example 3, where (a) shows spherical aberration, (B) shows astigmatism, and (C) shows distortion.
In the figure:
GC-diffractive optical element, G1-lens No. 1, G2-lens No. 2, St-aperture stop, Ri-radius of curvature of lens surface No. i from the object side, Di-surface spacing of lens surfaces No. i and No. i +1 from the object side, Z1-optical axis, 11-image pickup element, 12-sealing member, 13-diffractive surface.
Detailed Description
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Fig. 1 shows a 1 st configuration example of an imaging lens according to an embodiment of the present invention. This configuration example corresponds to the lens configuration of numerical example 1 (fig. 7(a), (B), and (C)) described below. Similarly, cross-sectional configurations of 2 nd to 3 rd configuration examples corresponding to lens configurations of 2 nd to 3 rd numerical examples described below are shown in fig. 2 to 3. In fig. 1 to 3, reference symbol Ri denotes a curvature radius of the i-th surface to which reference symbol is attached so as to increase in order toward the image side (image forming side) with the surface of the most object side component being the 1 st surface. The symbol Di indicates the surface interval between the i-th surface and the i + 1-th surface on the axis Z1. The basic configuration of each configuration example is the same.
The imaging lens 20 is composed of an aperture stop St, an actual lens portion (a refractive lens system portion including a 1 St lens G1 and a 2 nd lens G2), and a diffractive optical element GC in this order from the object side along the optical axis Z1. The 1 st lens G1 is a positive lens with a convex surface facing the image side. The 2 nd lens G2 is composed of, for example, a positive or negative meniscus lens having weak optical power. The 1 st lens G1 and the 2 nd lens G2 are preferably aspheric surfaces.
On the image formation surface of this imaging lens 20, an imaging element 11 (fig. 5) of an imaging device 10 described below is arranged. The diffractive optical element GC can also function as a cover glass for protecting the imaging surface by being integrated on the imaging device 10 side as described below, for example. The diffractive optical element GC has a diffractive effect on the passing light by forming a plurality of concentric sawtooth-shaped step differences on the surface of a glass or plastic substrate, for example. Such a construction is called kinoform (kinoform). The diffractive optical element GC of the present embodiment has a function of correcting chromatic aberration generated by the 1 st lens G1 and the 2 nd lens G2 of the actual lens portion. The diffractive optical element GC has at least 1 plane as a plane, and has a diffractive structure such as a Keno hologram pattern on the plane. For example, a parallel plane plate is used as a substrate, and at least 1 surface thereof is made to have a diffraction structure. In this case, it is particularly preferable that the plane on the imaging side has a diffraction structure. In this case, an infrared cut filter coating film may be formed on the object-side plane.
The diffractive optical element GC may be configured to have a diffractive structure on a plane of a substrate including a surface having a curvature and a plane facing the curved surface. The "surface having a curvature" as used herein means a surface having a curvature different from zero. The plane having a curvature different from zero is a plane.
The imaging lens 20 preferably satisfies the following conditional expression. In the formula, flash represents the focal length of the diffractive optical element GC, and fall represents the focal length of the entire lens system. V d1 denotes the abbe number of the 1 st lens G1 with respect to the d-line, f1 denotes the focal length of the 1 st lens G1, and Dlast denotes the distance between the image-side surface and the image surface of the diffractive optical element GC. SYL represents the distance (mm) on the optical axis from the object-side surface of the 1 st lens G1 to the diffraction surface of the diffractive optical element GC (see fig. 1).
5.0＜flast/fall＜6.0 ……(1)
v d1＞45 ……(2)
0.6＜f1/fall＜1.0 ……(3)
0.3mm＜Dlast ……(4)
2.0＜SYL＜4.2 ……(5)
Fig. 4 shows an example of a camera module in which the imaging lens 20 according to the present embodiment is incorporated. Fig. 5 shows an example of the configuration of the imaging device 10 incorporated in the camera module and used together with the imaging lens 20. Further, fig. 6(a) and (B) show a mobile phone with a camera as an example of a mobile terminal device equipped with the camera module of fig. 4.
As shown in fig. 5, the imaging device 10 includes an imaging element 11 that outputs an imaging signal corresponding to an optical image formed by an imaging lens 20. In the imaging device 10, a space between the surface on the imaging side of the diffractive optical element GC and the imaging surface 11A of the imaging element 11 is sealed and integrated by the sealing member 12. The imaging element 11 is a solid-state imaging element such as a CCD or a CMOS.
The camera-equipped mobile phone shown in fig. 6(a) and (B) includes an upper casing 2A and a lower casing 2B, both of which are configured to be rotatable in the direction of the arrow in fig. 6 (a). The lower housing 2B is provided with operation keys 21 and the like. The upper housing 2A is provided with a camera unit 1 (fig. 6B), a display unit 22 (fig. 6 a), and the like. The display unit 22 is formed of a display panel such as an LCD (liquid crystal panel) or an EL (Electro-Luminescence) panel. The display unit 22 is disposed on the side that becomes the inner surface when folded. The display unit 22 can display various menus related to telephone functions, as well as images captured by the camera unit 1. The camera section 1 is disposed on the back side of the upper housing 2A, for example. However, the position where the camera section 1 is provided is not limited thereto.
The camera section 1 includes a camera module according to the present embodiment. As shown in fig. 4, the camera module includes: a lens barrel 3 that houses the imaging lens 20 according to the present embodiment; a support substrate 4 that supports the lens barrel 3; and an imaging element 11 (fig. 5) provided on the support substrate 4 at a position corresponding to the image formation surface of the imaging lens 20. The camera module further includes: a flexible substrate 5 electrically connected to the image pickup device 11 on the support substrate 4, and an external connection terminal 6 electrically connected to the flexible substrate 5 and electrically connected to a signal processing circuit on the terminal device body side in a mobile phone with a camera or the like. These components are integrally formed.
The imaging device according to the present embodiment is not limited to a mobile phone with a camera, and may be, for example, a digital still camera, a PDA, or the like.
Next, the operation and effects of the imaging lens, the camera module, and the mobile terminal device configured as described above will be described.
In the imaging lens 20 according to the present embodiment, since the diffractive optical element GC is disposed on the most image side, the diffractive optical element GC can have a function of correcting chromatic aberration generated in the actual lens portions (the 1 st lens G1 and the 2 nd lens G2). Even if the chromatic aberration is not sufficiently corrected in the actual lens portion, the chromatic aberration can be corrected. Thus, the imaging lens 20 can be designed such that the actual lens portion is focused on the reduction of the total length without increasing the number of actual lenses, and not only can the total length be reduced but also chromatic aberration can be reduced as a whole. That is, even in a very small lens configuration in which the actual number of lenses is 2, since aberration correction can be performed on the entire combination with the diffractive optical element GC, an optical image with high resolution can be obtained.
In the imaging lens 20 according to the present embodiment, by providing the diffraction structure of the diffractive optical element GC on a plane, it is possible to suppress deterioration in performance due to manufacturing errors to a small extent, and to achieve excellent manufacturing adaptability. In particular, when the plane on the image pickup side of the diffractive optical element GC is the diffraction surface 13, the diffraction structure is simplified and aberration correction is facilitated as compared with the case where the plane on the object side is the diffraction surface 13. When the plane on the image pickup side is one of the diffraction surfaces 13, it is easy to obtain the aberration correction effect with a small number of turns, and it is also easy to process the diffraction surface 13.
In addition, when the imaging device 10 is combined with the sealing member 12 for sealing between the surface on the imaging side of the diffractive optical element GC and the imaging surface 11A of the imaging element 11 as shown in fig. 5, the imaging surface 11A is protected to prevent adhesion of dust and the like. When the plane on the imaging side is the diffraction surface 13, the diffraction surface 13 is also protected, and adhesion of dust and the like can be prevented.
The diffractive optical element GC may have, in addition to the function of correcting chromatic aberration, other functions such as a glass cover or an infrared cut filter for protecting an imaging surface in the imaging device 10. For example, an infrared cut filter plating film may be formed on the object-side plane of the diffractive optical element GC. Conventionally, although an infrared cut filter or a cover glass is disposed on the front side of an imaging device, in the present embodiment, 1 optical component (diffractive optical element GC) can be made to have a plurality of optical functions of the infrared cut filter or the cover glass, which is advantageous in reducing the number of components. That is, it is possible to make 1 optical component have a plurality of functions without increasing the number of parts, and the configuration is also simple.
In the camera module shown in fig. 4, an optical image formed by the imaging lens 20 is converted into an electrical imaging signal by the imaging element 11 of the imaging device 10, and the imaging signal is output to a signal processing circuit on the terminal device body side via the flexible substrate 5 and the external connection terminal 6. Here, in this camera module, by using the imaging lens 20 according to the present embodiment, it is possible to obtain an imaging signal of a high resolution in which chromatic aberration is sufficiently corrected. On the terminal device body side, an image of high resolution can be generated based on the image pickup signal.
The conditional expression (1) represents a ratio of the focal length flash of the diffractive optical element GC to the focal length fall of the entire lens system. When departing from the upper limit of the conditional expression (1), the power of the diffractive optical element GC becomes small, and the balance of chromatic aberration cannot be maintained. Further, if the value is out of the lower limit, the sensitivity to manufacturing errors increases, and the assembling property deteriorates.
The conditional expression (2) defines an appropriate range of abbe number v d1 of the 1 st lens G1 with respect to the d-line. When the numerical range of the conditional expression (2) is deviated, chromatic aberration other than the diffractive optical element GC becomes too large, and the chromatic aberration cannot be sufficiently corrected by the diffractive optical element GC.
The conditional expression (3) represents a ratio of the focal length f1 of the 1 st lens G1 to the focal length fall of the entire lens system. When the upper limit of the condition (3) is exceeded, the total length becomes longer. If the aberration deviates from the lower limit, the amount of aberration generated by the 1 st lens G1 increases, and it becomes difficult to correct the aberration by the 2 nd lens G2 or the diffractive optical element GC.
The conditional expression (4) indicates an appropriate range of the distance Dlast between the image side surface of the diffractive optical element GC and the image plane (imaging plane 11A). When the distance Dlast is out of the range of the conditional expression (4), the distance between the diffractive optical element GC and the imaging surface 11A becomes too short, and the effect of reducing chromatic aberration due to diffraction cannot be sufficiently obtained.
The conditional expression (5) defines an appropriate range of the distance SYL on the optical axis from the object-side surface of the 1 st lens G1 to the diffraction surface of the diffractive optical element GC. If the upper limit of the conditional expression (5) is exceeded, the total length becomes longer, and the effect of the actual number of lenses being 2 is reduced. When the refractive power of the diffractive optical element GC deviates from the lower limit, the chromatic aberration becomes excessive.
In order to shorten the entire length and to correct the chromatic aberration more favorably, the range of the following conditional expression (5A) is preferable.
3.0＜SYL＜4.0 ……(5A)
More preferably, the range of the following conditional formula (5B).
3.2＜SYL＜3.8 ……(5B)
As described above, according to the imaging lens 20 of the present embodiment, the total length can be shortened and chromatic aberration can be reduced. Further, according to the camera module of the present embodiment, since the image pickup signal corresponding to the optical image formed by the high-performance image pickup lens 20 whose total length is shortened and chromatic aberration is reduced is output, it is possible to obtain an image pickup signal of high resolution in which chromatic aberration is reduced, while downsizing the entire module. Further, according to the mobile terminal device of the present embodiment, since the small camera module with reduced chromatic aberration is mounted, it is possible to obtain an image pickup signal with high resolution with reduced chromatic aberration, and to obtain an image pickup image with high resolution based on the image pickup signal while downsizing the camera portion.
Examples
Next, a specific numerical example of the imaging lens 20 according to the present embodiment will be described. Hereinafter, numerical examples of 1 st to 3 rd will be described in general.
Fig. 7(a), (B), and (C) show specific lens data corresponding to the configuration of the imaging lens shown in fig. 1. In particular, fig. 7(a) shows basic lens data, fig. 7(B) shows data on an aspherical surface, and fig. 7(C) shows data on a diffraction surface. The column of the surface number Si in the lens data shown in fig. 7(a) shows the number of the i-th surface to which the number is added so that the surface of the most object-side component is the 1 st surface and which increases in the order of moving toward the image side in the imaging lens according to example 1. In the column of the radius of curvature Ri, a value (mm) of the radius of curvature of the i-th surface from the object side is indicated corresponding to the symbol Ri attached in fig. 1. The column of the surface interval Di also indicates the interval (mm) between the i-th surface Si and the i + 1-th surface Si +1 on the optical axis from the object side. Column Ndj shows the refractive index of the j-th optical element with respect to the d-line (587.6nm) from the object side. In the field of ν dj, the abbe number of the j-th optical element from the object side with respect to the d-line is shown.
In the imaging lens according to example 1, both surfaces of the 1 st lens G1 and the 2 nd lens G2 have aspherical shapes. The basic lens data in fig. 7(a) shows numerical values of the curvature radii of the aspherical surfaces in the vicinity of the optical axis.
Fig. 7(B) shows imaging in example 1Aspheric data in the lens. In the numerical values shown as the aspherical surface data, the symbol "E" indicates that the subsequent numerical value is a "power exponent" with a base 10, and indicates that the numerical value represented by an exponential function with a base 10 is multiplied by the numerical value before "E". For example, if [1.0E-02 ]]Then, it represents [ 1.0X 10 ]-2]。
As aspherical surface data of the imaging lens in example 1, each coefficient B in an aspherical surface shape expression represented by the following expression (a) is expressednAnd the value of KA. More specifically, Z represents the length (mm) of a perpendicular line from a point on the aspherical surface at a position having a height h from the optical axis to a tangential plane (plane perpendicular to the optical axis) to the vertex of the aspherical surface.
Z＝CC·h2/{1+(1-KA·CC2·h2)1/2}+∑Bn·hn ……(A)
(n is an integer of 3 or more)
Wherein,
z: depth of aspheric surface (mm)
h: distance (height) (mm) from optical axis to lens surface
KA: far heart rate
CC: paraxial curvature of 1/R
(R: paraxial radius of curvature)
Bn: nth aspheric coefficient
The imaging lens of example 1 shows the aspherical surface coefficient BnEffective and appropriate use of B3～B10The number of times.
In the imaging lens of example 1, the diffractive optical element GC is a parallel plane plate (the curvature of both surfaces is 0), and the plane on the imaging side is a diffractive surface. The diffraction structure of the diffractive optical element GC is obtained by measuring the amount of change φ in the phase of the wave surface given by an arbitrary distance r from the optical axis Z1 by the following phase difference functionHowever, the optical path length difference is given to the optical path length difference. Fig. 7C shows the values of the coefficients Ci (i is 1 to 10) of the phase difference function. In the numerical values, the notation "E" indicates that the value following it is a "power exponent" with a base 10, indicating that the numerical value represented by the exponential function with a base 10 is multiplied by the value preceding "E". For example, if [1.0E-02 ]]Then, it represents [ 1.0X 10 ]-2]。
φ(r)＝C1·r2+C2·r4+C3·r6+C4·r8+C5·r10+…
As with the imaging lens of example 1 described above, specific lens data corresponding to the imaging lens configuration shown in fig. 2 is shown in fig. 8(a), (B), and (C) as example 2. Similarly, specific lens data corresponding to the imaging lens configuration shown in fig. 3 is shown in fig. 9(a), (B), and (C) as example 3. In examples 2 and 3, both surfaces of the 1 st lens G1 and the 2 nd lens G2 are aspheric, as in the imaging lens of example 1. The diffractive optical element GC is a parallel flat plate (curvature of both surfaces is 0), and a plane on the imaging side is a diffraction plane.
In fig. 10, values of the conditional expressions are shown in a comprehensive manner for each example. Note that f1 denotes a focal length of the 1 st lens G1, f2 denotes a focal length of the 2 nd lens G2, and f3 denotes a focal length of the diffractive optical element GC. As can be seen from fig. 10, the values of the examples fall within the numerical ranges of the conditional expressions.
Fig. 11a to 11C show spherical aberration, astigmatism, and distortion (distortion aberration) in the imaging lens of example 1. Each aberration chart shows aberration with a d-line (587.6nm) as a reference wavelength. The spherical aberration diagrams also show aberrations for the F-line (wavelength 486.1nm) and C-line (wavelength 656.3 nm). In the astigmatism diagram, S represents a sagittal direction, and a broken line T represents an aberration in a meridional direction.
Similarly, various aberrations of the imaging lens of example 2 are shown in fig. 12(a) to 12 (C). Similarly, various aberrations of the imaging lens of example 3 are shown in fig. 13(a) to 13 (C).
As is clear from the above numerical data and aberration diagrams, the imaging lens according to each embodiment can achieve reduction in total length and reduction in chromatic aberration.
The present invention is not limited to the above-described embodiments and examples, and various modifications can be made. For example, the curvature radius, the surface interval, the refractive index value, and the like of each lens component are not limited to the values shown in the numerical examples, and may be other values.
Claims (10)
1. An image pickup lens includes, in order from an object side:
a diaphragm;
a 1 st lens formed by a positive lens having a convex surface facing the image side;
a 2 nd lens formed of a meniscus lens; and
a diffractive optical element at least 1 plane of which is a plane and at least 1 plane of which has a diffractive structure,
the imaging lens satisfies the following conditional expression:
5.0＜flast/fall＜6.0 ……(1)
wherein,
and (4) flash: the focal length of the diffractive optical element is,
fall: focal length of the lens system as a whole.
2. The imaging lens according to claim 1, further satisfying the following conditional expression:
v d1＞45 ……(2)
0.6＜f1/fall＜1.0 ……(3)
0.3mm＜Dlast ……(4)
wherein,
v d 1: abbe number of the 1 st lens with respect to d-line,
f 1: the focal length of the 1 st lens is,
and Dlast: distance between image side surface and image surface of diffractive optical element
3. An image pickup lens includes, in order from an object side:
a diaphragm;
a 1 st lens formed of a positive lens;
a 2 nd lens formed of a meniscus lens; and
a diffractive optical element having a plane image side surface and a diffractive structure on a plane on the image side,
the imaging lens satisfies the following conditional expression:
0.6＜f1/fall＜1.0 ……(3)
2.0mm＜SYL＜4.2mm ……(5)
wherein,
f 1: the focal length of the 1 st lens is,
fall: the focal length of the lens system as a whole,
SYL: a distance on the optical axis from the object-side surface of the 1 st lens to the diffraction surface of the diffractive optical element.
4. The imaging lens according to any one of claims 1 to 3,
the diffractive optical element has a function of correcting chromatic aberration generated by the 1 st lens and the 2 nd lens.
5. The imaging lens according to any one of claims 1 to 3, characterized in that:
the diffractive optical element has a plane on the image side and a diffractive structure on the plane on the image side.
6. The imaging lens according to any one of claims 1 to 3,
the diffractive optical element has a diffractive structure on a plane on the image side of the substrate, which is a parallel plane plate.
7. The imaging lens according to any one of claims 1 to 3,
an infrared cut filter coating film is formed on the object-side plane of the diffractive optical element.
8. A camera module includes:
the imaging lens according to any one of claims 1 to 3; and
and an image pickup element for outputting an image pickup signal corresponding to an optical image formed by the image pickup lens.
9. The camera module of claim 8,
further provided with: and a sealing member for sealing a space between a surface on the image pickup side of the diffractive optical element and the image pickup surface of the image pickup element.
10. A mobile terminal device comprising the camera module according to claim 8 or 9.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2007-184713 | 2007-07-13 | ||
| JP2007184713A JP4953953B2 (en) | 2007-07-13 | 2007-07-13 | Imaging lens, camera module, and portable terminal device |
| JP2007184713 | 2007-07-13 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101344633A CN101344633A (en) | 2009-01-14 |
| CN101344633B true CN101344633B (en) | 2010-11-03 |
Family
ID=40246657
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2008101285718A Expired - Fee Related CN101344633B (en) | 2007-07-13 | 2008-06-27 | Imaging lens, camera module and portable terminal equipment |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP4953953B2 (en) |
| CN (1) | CN101344633B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI662840B (en) * | 2014-06-27 | 2019-06-11 | 日商新力股份有限公司 | Camera and electronic equipment |
| CN108873311B (en) * | 2018-08-06 | 2023-10-24 | 中山市众盈光学有限公司 | Endoscope optical system of small-size |
| CN110441887A (en) * | 2019-08-20 | 2019-11-12 | Oppo广东移动通信有限公司 | Lens module and mobile terminal |
| CN112202999B (en) * | 2020-09-30 | 2022-02-15 | 维沃移动通信有限公司 | Imaging device and electronic apparatus |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000089107A (en) * | 1998-09-17 | 2000-03-31 | Fuji Photo Optical Co Ltd | Image reading lens |
| JP2002023051A (en) * | 2000-07-13 | 2002-01-23 | Asahi Optical Co Ltd | Optical spatial transmitting device |
| JP3717487B2 (en) * | 2002-03-29 | 2005-11-16 | フジノン株式会社 | Imaging lens |
| JP3881955B2 (en) * | 2002-12-11 | 2007-02-14 | 財団法人工業技術研究院 | Two-piece diffractive refractive image forming system |
| JP2004191844A (en) * | 2002-12-13 | 2004-07-08 | Minolta Co Ltd | Imaging lens |
| CN100419488C (en) * | 2004-08-27 | 2008-09-17 | 清华大学 | Micro-camera lens system |
| JP4822005B2 (en) * | 2004-09-03 | 2011-11-24 | ナルックス株式会社 | Imaging optical system including an optical element having a discontinuous surface |
| DE102005009238A1 (en) * | 2005-02-25 | 2006-09-07 | Carl Zeiss Ag | Lens system for digital camera module, has one of two lens with concavely designed side in one area corresponding to two-thirds of diameter of side and flatly designed side in other area corresponding to two-thirds of diameter of other side |
| DE102005033746A1 (en) * | 2005-07-15 | 2007-01-25 | Schott Ag | Compact lens for e.g. cell phone camera, has diffractive optical element imaging incident light, and refractive optical element provided as compound lens with lens elements having two indices of refraction, respectively |
| JP2008107389A (en) * | 2006-10-23 | 2008-05-08 | Nec Tokin Corp | Fixed focus lens |
| JP2009008758A (en) * | 2007-06-26 | 2009-01-15 | Fujinon Corp | Imaging device, camera module and portable terminal equipment |
-
2007
- 2007-07-13 JP JP2007184713A patent/JP4953953B2/en not_active Expired - Fee Related
-
2008
- 2008-06-27 CN CN2008101285718A patent/CN101344633B/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2009020447A (en) | 2009-01-29 |
| JP4953953B2 (en) | 2012-06-13 |
| CN101344633A (en) | 2009-01-14 |
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