JP2004070235A - Image pickup lens device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image pickup lens device equipped with a zoom lens system whose zoom ratio is about 3, and made so compact and inexpensive that it is mounted in a thin housing such as a cellular phone. <P>SOLUTION: The zoom lens system (TL) is constituted of a 1st group (Gr1) positionally fixed at the time of zooming and having negative power, a 2nd group (Gr2) moving at the time of zooming and having positive power and a 3rd group (Gr3) moving at the time of zooming and having positive power in order from an object side, and an optical image formed by the zoom lens system (TL) is converted into an electrical signal by an imaging device (SR). The 1st group (Gr1) is constituted of a prism (PR) for bending an optical path, and the object side surface (S1) of the prism (PR) is an aspherical concave surface, and the reflection surface (S2) and the image side surface (S3) of the prism (PR) are plane. <P>COPYRIGHT: (C)2004,JPO

Description

【００３１】
［第１面（ｒ１）の非球面データ］
ε＝０．１００００×１０，Ａ４＝　０．４５３８４×１０^−２，Ａ６＝−０．２５５４９×１０^−３，Ａ８＝　０．１９２１２×１０^−４，Ａ１０＝−０．５０７０８×１０^−６
［第４面（ｒ４）の非球面データ］
ε＝０．１００００×１０，Ａ４＝−０．９４０２９×１０^−２，Ａ６＝　０．３７５８７×１０^−２，Ａ８＝−０．５７１４０×１０^−２，Ａ１０＝　０．２０２６４×１０^−２
［第７面（ｒ７）の非球面データ］
ε＝０．１００００×１０，Ａ４＝　０．２６１９６×１０^−１，Ａ６＝　０．５７６９５×１０^−３，Ａ８＝　０．２４６４０×１０^−２，Ａ１０＝−０．５４２１７×１０^−３
［第８面（ｒ８）の非球面データ］
ε＝０．１００００×１０，Ａ４＝　０．２２８００×１０^−１，Ａ６＝−０．１６９５４×１０^−１，Ａ８＝　０．３５２７２×１０^−２，Ａ１０＝−０．２６４１９×１０^−３
［第９面（ｒ９）の非球面データ］
ε＝０．１００００×１０，Ａ４＝　０．６３８６４×１０^−１，Ａ６＝−０．２１３１９×１０^−１，Ａ８＝　０．３７９２２×１０^−２，Ａ１０＝−０．１５８００×１０^−３
【００３２】

【００３３】
［第１面（ｒ１）の非球面データ］
ε＝０．１００００×１０，Ａ４＝　０．７３１６１×１０^−２，Ａ６＝−０．２４８２８×１０^−３，Ａ８＝　０．１８７５１×１０^−４，Ａ１０＝　０．１３９６８×１０^−６
［第４面（ｒ４）の非球面データ］
ε＝０．１００００×１０，Ａ４＝−０．７０７８５×１０^−２，Ａ６＝−０．３００７６×１０^−３，Ａ８＝−０．１０６９３×１０^−２，Ａ１０＝　０．３２１７２×１０^−３
［第５面（ｒ５）の非球面データ］
ε＝０．１００００×１０，Ａ４＝　０．３３６８３×１０^−１，Ａ６＝−０．６３３５２×１０^−２，Ａ８＝　０．８４９４２×１０^−２，Ａ１０＝−０．１５７７１×１０^−２
［第６面（ｒ６）の非球面データ］
ε＝０．１００００×１０，Ａ４＝　０．９０６９４×１０^−２，Ａ６＝−０．３４９９３×１０^−２，Ａ８＝−０．１０１４８×１０^−２，Ａ１０＝　０．３８７２５×１０^−３
［第７面（ｒ７）の非球面データ］
ε＝０．１００００×１０，Ａ４＝　０．４２６３８×１０^−１，Ａ６＝−０．１１３０３×１０^−１，Ａ８＝　０．２２７２９×１０^−２，Ａ１０＝−０．８７９８９×１０^−４
【００３４】
【表１】

【００３５】
【発明の効果】
以上説明したように本発明によれば、ズーム比３倍程度のズームレンズ系を備え、携帯電話等の薄型の筐体に搭載するのに充分な小型化と低コスト化が達成された撮像レンズ装置を実現することができる。そして本発明を、デジタルカメラ；ビデオカメラ；デジタルビデオユニット，パーソナルコンピュータ，モバイルコンピュータ，携帯電話，携帯通信端末，携帯情報端末（ＰＤＡ）等に内蔵又は外付けされるカメラに適用すれば、これらの機器のコンパクト化，低コスト化，高変倍化及び高性能化に寄与することができる。
【図面の簡単な説明】
【図１】本発明に係る撮像レンズ装置の概略光学構成を示す模式図。
【図２】第１の実施の形態（実施例１）のレンズ構成図。
【図３】第２の実施の形態（実施例２）のレンズ構成図。
【図４】実施例１の収差図。
【図５】実施例２の収差図。
【符号の説明】
ＴＬ　…撮影レンズ系（ズームレンズ系）
ＰＲ　…プリズム
Ｇｒ１　　…第１群
Ｇｒ２　　…第２群
Ｇｒ３　　…第３群
ＰＬ　…平行平面板
ＳＲ　…撮像素子
ＡＸ　…光軸[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an imaging lens device, and in particular, to an imaging lens device that optically captures an image of a subject by an optical system and outputs it as an electrical signal by an imaging device {for example, a digital camera; a video camera; a digital video unit; Main constituent elements of a camera built in or external to a personal computer, a mobile computer, a mobile phone, a mobile communication terminal, a personal digital assistant (PDA), etc., particularly an imaging lens having a small zoom lens system It concerns the device.
[0002]
[Prior art]
A small zoom lens mounted on a mobile communication terminal, a digital camera, or the like is disclosed in JP-A-2002-55278, JP-A-11-196303, JP-A-2000-131610, and JP-A-9-138347. Proposed. The zoom lens described in Japanese Patent Application Laid-Open No. 2002-55278 achieves a reduction in the overall length and a zoom ratio of about three times with three lenses, and Japanese Patent Application Laid-Open Nos. 11-196303 and 2000-131610. The zoom lenses described in Japanese Unexamined Patent Publication No. Hei 9-138347 reduce the length in the depth direction by bending the optical path in the first group.
[0003]
[Problems to be solved by the invention]
The zoom lens described in Japanese Patent Application Laid-Open No. 2002-55278 has a total length of 10 mm or more, and when including a unit of an image sensor, is slightly large to be mounted on a thin housing such as a mobile phone or a mobile communication terminal. In the zoom lenses described in JP-A-11-196303, JP-A-2000-131610, and JP-A-9-138347, the first group is composed of two members, a lens and a reflecting member. Size and miniaturization are not enough. In addition, there is a problem of performance degradation due to a positional shift between the lens and the reflecting member that occurs when the lens and the reflecting member are assembled into the lens barrel.
[0004]
The present invention has been made in view of such a situation, and an object thereof is to provide a zoom lens system having a zoom ratio of about three times and to reduce the size enough to be mounted on a thin housing such as a mobile phone. And to provide an imaging lens device that achieves low cost.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, an imaging lens device according to a first aspect of the present invention includes a zoom lens system including a plurality of groups and performing zooming by changing an interval between the groups, and an optical system formed by the zoom lens system. An image pickup device for converting an image into an electric signal, wherein the zoom lens system includes, in order from the object side, a first group having a fixed negative power in zooming, and A second group of moving positive power, wherein the first group has at least a prism for bending the optical path closest to the object side, and the object side surface of the prism is concave.
[0006]
An imaging lens device according to a second aspect is characterized in that, in the configuration according to the first aspect, the image side surface of the prism is a flat surface.
[0007]
An imaging lens device according to a third aspect is characterized in that, in the configuration of the first or second aspect, the following conditional expression (1) is satisfied.
1.5 <−f1 / fW <8.0 (1)
However,
f1: focal length of the first group,
fW: focal length of the entire zoom lens system at the wide-angle end,
It is.
[0008]
According to a fourth aspect of the present invention, in the imaging lens device according to the first, second, or third aspect, the object side surface of the prism is an aspherical surface.
[0009]
According to a fifth aspect of the present invention, in the imaging lens device according to the fourth aspect, the aspheric surface satisfies the following conditional expression (2).
0.1 <R0 / R1 <0.7 (2)
However,
R0: radius of curvature on the axis of the aspherical surface,
R1: radius of curvature at the effective diameter position of the aspherical surface,
It is.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an imaging lens device embodying the present invention will be described with reference to the drawings. 2. Description of the Related Art An imaging lens device that optically captures an image of a subject and outputs it as an electrical signal is a camera used for still image shooting or moving image shooting of a subject {for example, a digital camera; a video camera; a digital video unit, a personal computer, and a mobile. It is a main component of a camera built-in or external to a computer, a mobile phone, a mobile communication terminal, a personal digital assistant (PDA), or the like. For example, as shown in FIG. 1, the imaging lens device includes, in order from an object (subject) side, a photographing lens system (TL) that forms an optical image of the object, and a parallel flat plate (PL) corresponding to an optical low-pass filter or the like. ) And an image sensor (SR) that converts an optical image formed by the taking lens system (TL) into an electric signal.
[0011]
The photographing lens system (TL) shown in FIG. 1 includes, in order from the object side, a first group (Gr1) having negative power, a second group (Gr2) having positive power, a third group (Gr3) having positive power, Is a zoom lens system having a three-group configuration. Then, the second group (Gr2) and the third group (Gr3) move along the optical axis (AX), and the magnification (magnification) is performed by changing the interval between the groups. The first group (Gr1) is a fixed group whose position is fixed in zooming, and includes only a prism (PR) for bending an optical path as an optical element. The object side surface (S1) of the prism (PR) is concave, and the reflection surface (S2) and the image side surface (S3) are flat. The negative power of the first lens unit (Gr1) is constituted by the concave object side surface (S1), and the bending of the optical path for using the imaging lens system (TL) as a bending optical system is performed by a flat reflecting surface (S2). ). Note that the zoom configuration of the photographing lens system (TL) is not limited to this as long as the zoom lens system includes a plurality of groups and changes the magnification by changing the interval between the groups.
[0012]
As the image sensor (SR), for example, a solid-state image sensor such as a CCD (Charge Coupled Device) comprising a plurality of pixels or a CMOS (Complementary Metal Oxide Semiconductor) sensor is used, and an optical image formed by a zoom lens system is used as the image sensor. (SR) is converted into an electrical signal. An optical image to be formed by the zoom lens system is composed of an optical low-pass filter / parallel plane plate (PL) having a predetermined cutoff frequency characteristic determined by the pixel pitch of the image sensor (SR). By passing through｝, the spatial frequency characteristic is adjusted such that so-called aliasing noise generated when converted into an electric signal is minimized. Examples of the optical low-pass filter include, for example, a birefringent low-pass filter made of quartz or the like whose crystal axis direction is adjusted, and a phase-type low-pass filter that achieves a required optical cutoff frequency characteristic by a diffraction effect. Etc. are applicable. The signal generated by the image sensor (SR) is subjected to predetermined digital image processing and image compression processing as necessary, and is recorded as a digital video signal in a memory (semiconductor memory, optical disk, or the like). Or is converted to an infrared signal and transmitted to another device.
[0013]
Note that, in the imaging lens device shown in FIG. 1, the reduction projection from the object on the enlargement side (the side with the longer conjugate length) to the image sensor (SR) on the reduction side (the side with the shorter conjugate length) is performed by the imaging lens system (TL). However, if a display element (for example, a liquid crystal display element) for displaying a two-dimensional image is used instead of the imaging element (SR) and the taking lens system (TL) is used as a projection lens system, the image display surface on the reduction side can be obtained. , An image projection apparatus that performs enlarged projection from the image to the screen surface on the enlargement side can be configured. That is, the zoom lens system used in the imaging lens device of the present invention is not limited to use as a photographing lens system (TL), but can be suitably used as a projection lens system.
[0014]
FIGS. 2 and 3 show zoom lens systems constituting the first and second embodiments of the imaging lens device in terms of lens arrangement and optical cross section at the wide-angle end (W). Arrows m2 and m3 in each lens configuration diagram schematically show movement of the second group (Gr2) and the third group (Gr3) during zooming from the wide-angle end (W) to the telephoto end (T). . In each lens configuration diagram, the surface marked with ri (i = 1, 2, 3,...) Is the i-th surface counted from the object side (the surface marked with * is an aspheric surface). ) And di (i = 1, 2, 3,...) Are the variable distances that change during zooming among the i-th axial distances counted from the object side.
[0015]
In each of the zoom lens systems according to the first and second embodiments, in order from the object side, a first unit (Gr1) having a negative power, a second unit (Gr2) having a positive power, and a positive unit A third group (Gr3) having power, and a three-group zoom lens having a zoom ratio of about three times that performs zooming by changing the interval between the respective groups. As a zoom lens system used for a camera (for example, a digital camera) having an image sensor (SR) such as a CCD, an optical filter such as an optical low-pass filter and a cover glass of the image sensor (SR) are provided on the image side. And a glass plane-parallel plate (PL) corresponding to. The position of the parallel plane plate (PL) and the first lens unit (Gr1) is fixed during zooming.
[0016]
The lens configuration of each embodiment will be described in more detail. In the zoom lens systems according to the first and second embodiments, the negative, positive, and positive groups (Gr1, Gr2, Gr3) are configured as follows in order from the object side. The first lens unit (Gr1) includes a prism (PR) whose object side surface (S1) is formed of an aspherical concave surface and whose reflection surface (S2) bends the optical axis (AX) by about 90 °. In the first embodiment (FIG. 2), the second group (Gr2) includes a biconvex positive lens (object side surface is aspherical) and a biconcave negative lens (image side surface is aspherical). The third group (Gr3) is composed of a biconvex positive lens (both surfaces are aspheric). In the second embodiment (FIG. 3), the second group (Gr2) is composed of a positive meniscus lens (both surfaces are aspheric) convex on the object side, and the third group (Gr3) is convex on the image side. (Both surfaces are aspheric). Note that the zoom lens system (FIG. 2) of the first embodiment has the same lens type as the photographing lens system (TL) in FIG.
[0017]
In the zoom lens system according to each of the embodiments, the negative first unit (Gr1) is fixed during zooming, and at least the interval between the units is changed by zoom movement of the positive second unit (Gr2). By fixing the first lens unit (Gr1) in zooming, it is possible to suppress a change in the overall length of the zoom lens system and an increase in the diameter of the front lens. Further, if a prism (PR) is arranged at least on the most object side in the first group (Gr1) having a fixed zoom position, and the optical path is bent at the reflection surface (S2), the direction of the incident optical axis of the zoom lens system (that is, The length (in the depth direction) is short and constant, so that further miniaturization and higher magnification can be achieved as compared with the related art. Therefore, an apparently thinner and smaller camera can be achieved, and a camera that does not change its thickness due to zooming or collapsing can be configured. If necessary, other prisms or mirrors may be used as reflecting members instead of the prism (PR) that bends the optical axis (AX) by about 90 °, and the bending angle of the optical axis (AX) is set to a value other than 90 °. May be set. If necessary, the reflecting surface of the reflecting member may have power, and the optical axis (AX) may be bent using a refracting surface or a diffractive surface instead of the reflecting surface.
[0018]
When the prism (PR) for bending the optical path is arranged in the first group (Gr1) for shortening in the depth direction, the negative power of the first group (Gr1) is given to the prism (PR) as in each embodiment. It is desirable. By appropriately setting the negative power of the first lens unit (Gr1), the first lens unit (Gr1) can be composed of one plastic member, and the cost and size can be reduced by reducing the number of lenses and the assembly process. It is possible to improve the optical performance by improving the accuracy of assembly and assembly. As a specific power setting for obtaining such an effect, it is preferable to satisfy the following conditional expression (1), and it is more preferable to satisfy the following conditional expression (1a).
[0019]
1.5 <−f1 / fW <8.0 (1)
2.5 <−f1 / fW <5.0 (1a)
However,
f1: focal length of the first lens unit (Gr1);
fW: focal length of the entire zoom lens system at the wide-angle end (W),
It is.
[0020]
If the upper limit of conditional expression (1) is exceeded, the power of the first lens unit (Gr1) will be too weak, and it will be difficult to secure a zoom ratio of about three times. Conversely, if the lower limit of conditional expression (1) is exceeded, the power of the first lens unit (Gr1) is too strong, and when a plastic member having a variance (ie, Abbe number) of 60 or less is used, particularly at the wide-angle end (W) Magnification chromatic aberration becomes large and cannot be corrected.
[0021]
As in each embodiment, the object side surface (S1) of the prism (PR) is desirably concave, and the image side surface (S3) of the prism (PR) is desirably flat. By providing the reflecting surface (S2) for bending the optical path and the refracting surface (S1) having a negative power on the same member, it is possible to prevent performance degradation due to a mounting error. Further, by making only the object side surface (S1) of the prism (PR) a curved surface, it is possible to prevent performance degradation due to misalignment between the object side surface (S1) and the image side surface (S3).
[0022]
Also, as in each embodiment, it is desirable that the object side surface (S1) of the prism (PR) be an aspherical surface, and the negative power becomes weaker as the object side surface (S1) of the prism (PR) goes to the periphery. More preferably, it is spherical. By making the object side surface (S1) of the prism (PR) an aspheric surface in which the negative power becomes weaker as going to the periphery, it is possible to satisfactorily correct the strong pincushion type distortion particularly occurring at the wide angle end (W). It becomes possible. As a specific surface shape setting for obtaining such an effect, it is preferable to satisfy the following conditional expression (2), and it is more preferable to satisfy the following conditional expression (2a).
[0023]
0.1 <R0 / R1 <0.7 (2)
0.2 <R0 / R1 <0.5 (2a)
However,
R0: radius of curvature on the axis of the aspherical surface,
R1: radius of curvature at the effective diameter position of the aspherical surface,
It is.
[0024]
The conditional expressions (2) and (2a) define a preferable surface shape of the aspheric surface used for the object side surface (S1) of the prism (PR). If the upper limit of conditional expression (2) is exceeded, it becomes difficult to sufficiently correct distortion (particularly strong pincushion distortion occurring at the wide-angle end (W)). If the lower limit of conditional expression (2) is exceeded, the correction will be excessive, and barrel distortion will occur.
[0025]
The zoom lens system according to each of the embodiments includes a refractive lens that deflects an incident light ray by a refraction action (that is, a lens of a type in which deflection is performed at an interface between media having different refractive indexes). Although used, usable lenses are not limited to this. For example, a diffractive lens that deflects an incident light beam by a diffractive action, a hybrid refraction / diffractive lens that deflects an incident light ray by a combination of a diffractive action and a refraction action, and a refractive index distribution that deflects the incident light ray by a refractive index distribution in a medium. A mold lens or the like may be used. Further, a light flux regulating plate, a diaphragm, and the like for cutting unnecessary light may be arranged as necessary.
[0026]
【Example】
Hereinafter, the configuration and the like of the zoom lens system used in the imaging lens device embodying the present invention will be described more specifically with reference to construction data and the like. Examples 1 and 2 listed here correspond to the first and second embodiments described above, respectively. The lens configuration diagrams (FIGS. 2 and 3) representing the first and second embodiments are shown in FIGS. And the corresponding lens configurations of Examples 1 and 2 are shown.
[0027]
In the construction data of each embodiment, ri (i = 1, 2, 3,...) Is the radius of curvature (mm) of the i-th surface counted from the object side, and di (i = 1, 2, 3,. ...) indicate the i-th axial top surface interval (mm) counted from the object side, and Ni (i = 1, 2, 3,...), Νi (i = 1, 2, 3,. .) Indicate the refractive index (Nd) and Abbe number (νd) of the i-th optical element counted from the object side with respect to the d-line. In the construction data, the distance between the upper surfaces of the axes that changes during zooming is variable air at the wide-angle end (short focal length end, W) to the middle (intermediate focal length state, M) to the telephoto end (long focal length end, T). The interval. The focal length (f, mm) and F number (FNO) of the entire system corresponding to each focal length state (W), (M), (T) are shown together with other data, and the corresponding value of each conditional expression is shown. It is shown in Table 1.
[0028]
Surfaces marked with an asterisk (*) in the radius of curvature ri are aspherical surfaces (refracting optical surfaces having an aspherical surface, surfaces having a refracting action equivalent to an aspherical surface, and the like), and the following expression representing the aspherical surface shape ( AS). The aspherical surface data of each embodiment is shown together with other data (however, the case of Ai = 0 is omitted).
^{X (H) = (C0 ·} H 2) / {1 + √ (1-ε · C0 2 · H 2)} + Σ (Ai · H i) ... (AS)
However, in the expression (AS),
X (H): displacement amount in the optical axis (AX) direction at the position of height H (based on the surface vertex),
H: height in a direction perpendicular to the optical axis (AX),
C0: paraxial curvature (= 1 / radius of curvature),
ε: quadratic surface parameter,
Ai: i-th order aspherical coefficient,
It is.
[0029]
4 and 5 are aberration diagrams respectively corresponding to the first embodiment and the second embodiment. (W) denotes the wide-angle end, (M) denotes the middle, (T) denotes various aberrations at the telephoto end. Aberration, astigmatism, and distortion. Y ′: maximum image height (mm)｝. In the spherical aberration diagram, the solid line (d) represents the spherical aberration (mm) for the d line, the dashed line (g) represents the spherical aberration (mm) for the g line, and the dashed line (SC) represents the sine condition (mm). In the astigmatism diagram, a broken line (DM) represents astigmatism (mm) with respect to the d-line on the meridional surface, and a solid line (DS) represents astigmatism (mm) with respect to the d-line on the sagittal surface. I have. In the distortion diagrams, the solid line represents the distortion (%) with respect to the d-line.
[0030]

[0031]
[Aspherical surface data of first surface (r1)]
ε = 0.10000 × 10, A4 = 0.45384 × 10 ⁻² , A6 = −0.25549 × 10 ⁻³ , A8 = 0.19212 × 10 ⁻⁴ , A10 = −0.50708 × 10 ⁻⁶
[Aspherical surface data of fourth surface (r4)]
ε = 0.10000 × 10, A4 = −0.94029 × 10 ⁻² , A6 = 0.37587 × 10 ⁻² , A8 = −0.57140 × 10 ⁻² , A10 = 0.02264 × 10 ⁻²
[Aspherical surface data of the seventh surface (r7)]
ε = 0.10000 × 10, A4 = 0.26196 × 10 ^-1 , A6 = 0.57695 × 10 ^-3 , A8 = 0.24640 × 10 ^-2 , A10 = -0.54217 × 10 ^-3
[Aspherical surface data of eighth surface (r8)]
ε = 0.10000 × 10, A4 = 0.22800 × 10 ⁻¹ , A6 = −0.16954 × 10 ⁻¹ , A8 = 0.35272 × 10 ⁻² , A10 = −0.26419 × 10 ⁻³
[Aspherical surface data of ninth surface (r9)]
ε = 0.10000 × 10, A4 = 0.63864 × 10 ⁻¹ , A6 = −0.21319 × 10 ⁻¹ , A8 = 0.37922 × 10 ⁻² , A10 = −0.15800 × 10 ⁻³
[0032]

[0033]
[Aspherical surface data of first surface (r1)]
ε = 0.10000 × 10, A4 = 0.73161 × 10 ⁻² , A6 = −0.24828 × 10 ⁻³ , A8 = 0.18751 × 10 ⁻⁴ , A10 = 0.13968 × 10 ⁻⁶
[Aspherical surface data of fourth surface (r4)]
ε = 0.10000 × 10, A4 = −0.70785 × 10 ⁻² , A6 = −0.30076 × 10 ⁻³ , A8 = −0.10693 × 10 ⁻² , A10 = 0.32172 × 10 ⁻³
[Aspherical surface data of fifth surface (r5)]
ε = 0.10000 × 10, A4 = 0.36883 × 10 ⁻¹ , A6 = −0.63352 × 10 ⁻² , A8 = 0.84942 × 10 ⁻² , A10 = −0.15771 × 10 ⁻²
[Aspherical surface data of sixth surface (r6)]
ε = 0.10000 × 10, A4 = 0.90694 × 10 ⁻² , A6 = −0.34993 × 10 ⁻² , A8 = −0.10148 × 10 ⁻² , A10 = 0.38725 × 10 ⁻³
[Aspherical surface data of the seventh surface (r7)]
ε = 0.10000 × 10, A4 = 0.42638 × 10 ⁻¹ , A6 = −0.11303 × 10 ⁻¹ , A8 = 0.22729 × 10 ⁻² , A10 = −0.87989 × 10 ⁻⁴
[0034]
[Table 1]

[0035]
【The invention's effect】
As described above, according to the present invention, an imaging lens including a zoom lens system having a zoom ratio of about three times and achieving a sufficiently small size and low cost to be mounted on a thin housing such as a mobile phone. The device can be realized. If the present invention is applied to a digital camera; a video camera; a digital video unit, a personal computer, a mobile computer, a mobile phone, a portable communication terminal, a personal digital assistant (PDA), or a camera built in or externally attached thereto, It can contribute to downsizing, low cost, high magnification and high performance of the equipment.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a schematic optical configuration of an imaging lens device according to the present invention.
FIG. 2 is a lens configuration diagram of the first embodiment (Example 1).
FIG. 3 is a lens configuration diagram of a second embodiment (Example 2).
FIG. 4 is an aberration diagram of the first embodiment.
FIG. 5 is an aberration diagram of the second embodiment.
[Explanation of symbols]
TL: photographing lens system (zoom lens system)
PR Prism Gr1 First group Gr2 Second group Gr3 Third group PL Parallel plane plate SR Image sensor AX Optical axis

Claims (5)

An imaging lens that includes a plurality of groups and includes a zoom lens system that changes magnification by changing the interval between the groups, and an imaging element that converts an optical image formed by the zoom lens system into an electric signal. A device,
The zoom lens system includes, in order from the object side, at least a first group having a fixed negative power at zooming and a second group having positive power moving at zooming, wherein the first group is closest to the object side. An optical path bending prism, wherein the object side surface of the prism is concave. The imaging lens device according to claim 1, wherein an image side surface of the prism is a flat surface. The imaging lens device according to claim 1, wherein the following conditional expression (1) is satisfied;
1.5 <−f1 / fW <8.0 (1)
However,
f1: focal length of the first group,
fW: focal length of the entire zoom lens system at the wide-angle end,
It is. The imaging lens device according to claim 1, wherein an object side surface of the prism is an aspheric surface. The imaging lens device according to claim 4, wherein the aspheric surface satisfies the following conditional expression (2):
0.1 <R0 / R1 <0.7 (2)
However,
R0: radius of curvature on the axis of the aspherical surface,
R1: radius of curvature at the effective diameter position of the aspherical surface,
It is.

Images