JP2005084151A - Zoom lens device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize the thinning in a depth direction and also the miniaturization and the reduction of cost of a zoom lens. <P>SOLUTION: In the zoom lens device constituted of a 1st lens group GR1 having a negative focal distance, a 2nd lens group GR2 having a positive focal distance and a 3rd lens group GR3 having a positive focal distance in order from an object side, the 2nd lens group GR2 moves to the object side, whereby light is taken in by a photodetector CCD through the zoom lens which varies power from a wide angle end to a telephoto end. The 1st lens group GR1 is constituted of at least one negative lens L11 and one positive lens L12, and a prism P reflecting an optical path is arranged behind the negative lens L11, and then the photodetector CCD is provided to move along in an optical axis direction so as to correct at least focus movement in the midst of varying power. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a zoom lens device that uses a reflecting member that bends an optical path to reduce the thickness in the depth direction.

  In recent years, further downsizing is demanded in digital still cameras and the like, and in particular, a zoom lens adapted to reduce the thickness of the camera is demanded. Patent Document 1, Patent Document 2, and Patent Document 3 have been proposed to reduce the size of the lens in the depth direction by using a bending member. The zoom lenses described in these three patent documents are thin in the depth direction by providing a reflecting member behind the most object side negative lens of the first lens group having a positive focal length and bending the optical path. Is realized.

JP-A-8-248318 JP-A-9-133858 JP-A-12-131610

  However, if an attempt is made to construct a zoom lens with such a power arrangement, there will be a problem that the number of lens groups and the number of lenses will increase, leading to an increase in cost and size.

  The present invention has been made to solve such problems. That is, the present invention is a zoom lens apparatus that takes in light with a light receiving element through a zoom lens in which a first lens group that is fixed on the most object side and has a negative focal length is arranged, and at least the first lens group Consists of one negative lens and one positive lens, a reflecting member is arranged after the negative lens, and the light receiving element is provided so as to be movable along the optical axis direction so as to correct at least the focus movement during zooming. It is a thing.

  In the present invention, the first lens group and the reflecting member can be downsized by setting the first lens group to a negative focal length. Further, since the light receiving element is moved by focus correction, the first lens group and the reflecting member can be fixed, and the layout on the camera is easy. Further, by arranging and moving in this way, the number of lens groups and the number of lens components can be reduced while reducing the depth.

  In the present invention, the reflecting member is disposed immediately after the first lens group. As a result, it is possible to reduce performance degradation due to manufacturing errors, mounting errors, etc. of the reflecting member.

  In the present invention, a reflecting member is disposed between a negative lens and a positive lens constituting the first lens group. Thereby, further reduction in thickness in the depth direction can be realized.

  Further, the present invention includes, in order from the object side, a first lens group having a negative focal length, a second lens group having a positive focal length, and a third lens group having a positive focal length, and the second lens group is an object. A zoom lens apparatus that captures light by a light receiving element through a zoom lens that changes magnification from the wide-angle end to the telephoto end by moving to the side, and includes a first lens group that includes at least one negative lens and one positive lens. A reflecting member that bends the optical path after the negative lens is disposed, and the light receiving element is provided so as to be movable along the optical axis direction so as to correct at least focusing movement during zooming. As a result, the depth can be reduced even if the number of lens groups is three.

  In the present invention, when the zoom lens is zoomed from the wide-angle end to the telephoto end, the third lens unit is moved so as to be positioned closest to the object side during zooming. Thereby, the amount of movement of the light receiving element can be reduced, and the drive mechanism can be simplified.

  Further, according to the present invention, the position of the third lens group is fixed during zooming of the zoom lens. Thereby, the number of members that move during zooming can be reduced, and the drive mechanism can be simplified.

  Further, according to the present invention, the image plane side of the negative lens in the first lens group and the positive lens in the second lens group are aspherical. This makes it possible to obtain high optical performance while reducing the number of constituent lenses of the first lens group and the second lens group.

  Therefore, it is possible to further reduce the size and cost while reducing the thickness direction in an imaging apparatus such as a camera using the zoom lens apparatus according to the present invention. This makes it possible to reduce the thickness, size, and cost of an imaging apparatus such as a video camera or a digital still camera.

  Embodiments of the present invention will be described below. In other words, the zoom lens device according to the present embodiment captures light with the light receiving element through the zoom lens in which the first lens group that is fixed on the most object side and has a negative focal length is arranged. The aim is to reduce the size and cost as well as to make the direction thinner.

  In order to achieve this object, in the present embodiment, the first lens group of the zoom lens device includes at least one negative lens and one positive lens, and a reflecting member is disposed after the negative lens to receive light. The element is configured to be movable along the optical axis direction so as to correct at least the focus movement during zooming.

  In addition, the zoom lens apparatus according to the present embodiment employs a configuration in which the reflecting member is disposed immediately after the first lens group, or further depth from the viewpoint of reducing performance deterioration due to manufacturing errors and mounting errors of the reflecting member. In order to achieve a reduction in direction, a configuration in which a reflecting member is disposed between a negative lens and a positive lens constituting the first lens group is employed.

  Next, specific examples of the zoom lens device according to the present invention will be described. FIG. 1 is a configuration diagram of a zoom lens apparatus according to the first embodiment, FIG. 2 is a diagram showing various aberrations at the wide-angle end of the zoom lens applied in the first embodiment, and FIG. 3 is applied in the first embodiment. FIG. 4 is a diagram of various aberrations at the telephoto end of the zoom lens applied in the first embodiment.

  5 is a block diagram of the zoom lens apparatus according to the second embodiment, FIG. 6 is a diagram showing various aberrations at the wide-angle end of the zoom lens applied in the second embodiment, and FIG. 7 is the second embodiment. FIG. 8 is a diagram of various aberrations at the telephoto end of the zoom lens applied in the second embodiment.

  In these figures, in the spherical aberration, the vertical axis represents the ratio to the open F value, the horizontal axis represents defocus, the solid line d represents the d-line, and the broken line g represents the g-line spherical aberration. In astigmatism, the vertical axis represents the image height, the horizontal axis represents the defocus, the solid line S represents the sagittal, and the broken line M represents the meridional image plane. Distortion is expressed in image height on the vertical axis and in% on the horizontal axis.

  In the first and second embodiments, the first lens group GR1 closest to the object side has a negative focal length, and the first lens group includes a negative lens L11 and a positive lens L12 in order from the object side. A prism P, which is a reflecting member, is disposed immediately after the first lens group, and the first lens group GR1 and the prism P are fixed to the camera body by a lens barrel (not shown).

  The optical axis is bent by 90 ° by the prism P, and the second lens group GR2 having a positive focal length is disposed on the optical axis on the imaging surface side.

  The second lens group GR2 includes, in order from the object side, a positive lens L21, a cemented lens of a negative lens L22 and a positive lens L23, and a negative lens L24. When zooming from the wide angle end to the telephoto end, the second lens group GR2 It moves so that the interval of becomes smaller.

  A third lens group GR3 having a positive focal length is disposed on the imaging surface side of the second lens group GR2. The third lens group GR3 is composed of one positive lens L31. Between the third lens group GR3 and the imaging surface IMG of the light receiving element CCD, a filter FL such as an infrared cut filter and a low-pass filter, and a cover glass CG are arranged. The cover glass CG and the light receiving element CCD are integrally moved in the optical axis direction so as to correct the focus fluctuation at the time of zooming.

  In the first example, the third lens group GR3 moves toward the object side between the wide-angle end and the telephoto end with respect to the position of the wide-angle end. As a result, the amount of movement of the light receiving element CCD can be reduced.

  In the second embodiment, since the third lens group GR3 is fixed, the drive mechanism can be simplified. A resin layer is bonded to the image plane side of the negative lens L11, and an aspheric surface is formed on the image plane side of the resin layer. An aspheric surface is formed on both surfaces of the positive lens L21 and on the image surface side of the positive lens L31.

  FIG. 9 is a configuration diagram of a zoom lens apparatus according to the third embodiment, FIG. 10 is a diagram of various aberrations at the wide-angle end of the zoom lens applied in the third embodiment, and FIG. 11 is applied in the third embodiment. FIG. 12 is a diagram of various aberrations at the telephoto end of the zoom lens applied in the third example.

  FIG. 13 is a block diagram of the zoom lens apparatus according to the fourth embodiment, FIG. 14 is a diagram showing various aberrations at the wide-angle end of the zoom lens applied in the fourth embodiment, and FIG. 15 is the fourth embodiment. FIG. 16 is a diagram of various aberrations at the telephoto end of the zoom lens applied in the fourth example.

  In these figures, in the spherical aberration, the vertical axis represents the ratio to the open F value, the horizontal axis represents defocus, the solid line d represents the d-line, and the broken line g represents the g-line spherical aberration. In astigmatism, the vertical axis represents the image height, the horizontal axis represents the defocus, the solid line S represents the sagittal, and the broken line M represents the meridional image plane. Distortion is expressed in image height on the vertical axis and in% on the horizontal axis.

  In the third and fourth embodiments, the first lens group GR1 closest to the object side has a negative focal length, and the first lens group GR1 includes a negative lens L11 and a positive lens L12 in order from the object side. A prism P, which is a reflecting member, is disposed immediately after the most object side negative lens L11 of the first lens group GR1, the optical axis is bent by 90 °, and a positive lens L12 is disposed immediately thereafter.

  The first lens group GR1 and the prism P are fixed to the camera body by a barrel (not shown).

  The second lens group GR2 includes, in order from the object side, a positive lens L21, a cemented lens of a negative lens L22 and a positive lens L23, and a negative lens L24. When zooming from the wide angle end to the telephoto end, the second lens group GR2 It moves so that the interval of becomes smaller.

  A third lens group GR3 having a positive focal length is disposed on the imaging surface side of the second lens group GR2. The third lens group GR3 is composed of one positive lens L31. Between the third lens group GR3 and the imaging surface IMG of the light receiving element CCD, a filter FL such as an infrared cut filter and a low-pass filter, and a cover glass CG are arranged.

  The cover glass CG and the light receiving element CCD are integrally moved in the optical axis direction so as to correct the focus fluctuation at the time of zooming.

  In the third embodiment, the third lens group GR3 is displaced to the most object side between the wide-angle end and the telephoto end. As a result, the amount of movement of the light receiving element CCD can be reduced.

  In the fourth embodiment, since the third lens group GR3 is fixed, the drive mechanism can be simplified. A resin layer is bonded to the image plane side of the negative lens L11, and an aspheric surface is formed on the image plane side of the resin layer. An aspheric surface is formed on both surfaces of the positive lens L21 and on the image surface side of the positive lens L31.

  Table 1, Table 2, Table 3, and Table 4 below show the specifications of the first, second, third, and fourth embodiments, respectively. In each table, FNO is the F number, f is the focal length, ω is the half field angle, surface is the lens surface number, r is the radius of curvature, D is the lens surface spacing, Nd is the refractive index with respect to the d line, and νd is the Abbe number. Indicates. The surface indicated by STOP is the diaphragm surface. The shape of the aspherical surface is a shape represented by the following formula.

The shape of the aspherical surface is a shape represented by the following formula.
x = {(y ² / R) / (1+ (1−κ · y ² / R ² ) ^1/2 )} + A4 · y ⁴ + A6 · y ⁶ + A8 · y ⁸ + A10 · y ¹⁰
However,
x: distance in the optical axis direction from the apex of the lens surface,
y: Distance from the optical axis
R: radius of curvature at the top of the lens,
κ: Conical constant.
A4, A6, A8, and A10 are fourth-order, sixth-order, eighth-order, and tenth-order aspheric coefficients, respectively.

  In this embodiment, the zoom lens can be focused by moving the light receiving element CCD or the third lens group GR3.

  As shown in the respective aberration diagrams, the zoom lenses applied in the first to first embodiments are balanced at the wide-angle end, at the intermediate focal length between the wide-angle end and the telephoto end, and at the telephoto end. It is well corrected.

  It should be noted that the specific shapes and structures of the respective portions shown as the embodiment and the examples are merely examples of actualization in carrying out the present invention, and these are the technical aspects of the present invention. The range should not be interpreted in a limited way.

  The zoom lens device according to the present invention can be applied to an imaging function part incorporated in a mobile phone, a personal computer, a portable terminal (PDA), etc., in addition to an imaging device such as a digital still camera and a digital video camera. .

It is a lens block diagram of a 1st Example. FIG. 6 is a diagram illustrating various aberrations at the wide-angle end of the first example. FIG. 6 is a diagram showing various aberrations at an intermediate focal length of the first example. FIG. 6 is a diagram showing various aberrations at the telephoto end of the first example. It is a lens block diagram of a 2nd Example. FIG. 10 is a diagram illustrating all aberrations at the wide-angle end of the second example. FIG. 6 is a diagram illustrating various aberrations at an intermediate focal length of the second example. FIG. 10 is a diagram illustrating all aberrations at the telephoto end of the second example. It is a lens block diagram of a 3rd Example. FIG. 10 is a diagram illustrating all aberrations at the wide-angle end of the third example. FIG. 10 is a diagram illustrating all aberrations at the intermediate focal length according to the third example. FIG. 10 is a diagram illustrating all aberrations at the telephoto end of the third example. It is a lens block diagram of a 4th Example. FIG. 10 is a diagram illustrating all aberrations at the wide-angle end of the fourth example. FIG. 12 is a diagram illustrating various aberrations at the intermediate focal length according to the fourth embodiment. FIG. 10 is a diagram illustrating all aberrations at the telephoto end of the fourth example.

Explanation of symbols

  GR1: first lens group, GR2: second lens group, GR3: third lens group, CCD: light receiving element, CG: cover glass

Claims (10)

A zoom lens device that takes in light with a light receiving element through a zoom lens in which a first lens group that is fixed on the most object side and has a negative focal length is disposed,
The first lens group includes at least one negative lens and one positive lens,
A reflective member is disposed after the negative lens;
The zoom lens apparatus according to claim 1, wherein the light receiving element is provided so as to be movable along the optical axis direction so as to correct at least focusing movement during zooming. The zoom lens device according to claim 1, wherein the reflecting member is disposed immediately after the first lens group. The zoom lens device according to claim 1, wherein the reflecting member is disposed between the negative lens and the positive lens constituting the first lens group. 4. The zoom lens device according to claim 1, wherein an image surface side of a negative lens in the first lens group is an aspherical surface. 5. In order from the object side, a first lens group having a negative focal length, a second lens group having a positive focal length, and a third lens group having a positive focal length are arranged, and the second lens group moves to the object side. A zoom lens device that captures light with a light receiving element through a zoom lens that zooms from a wide-angle end to a telephoto end,
The first lens group includes at least one negative lens and one positive lens,
A reflecting member for bending the optical path is disposed after the negative lens,
The zoom lens apparatus according to claim 1, wherein the light receiving element is provided so as to be movable along the optical axis direction so as to correct at least a focus movement during zooming. The zoom lens device according to claim 5, wherein the reflecting member is disposed immediately after the first lens group. The zoom lens device according to claim 5, wherein the reflecting member is disposed between the negative lens and the positive lens constituting the first lens group. The zoom lens apparatus according to claim 5, wherein when zooming from the wide-angle end to the telephoto end, the third lens unit moves so as to be positioned closest to the object side during zooming. The zoom lens apparatus according to claim 5, wherein the position of the third lens group is fixed during zooming of the zoom lens. The zoom lens according to any one of claims 5 to 9, wherein an image surface side of the negative lens in the first lens group and a positive lens in the second lens group are aspherical surfaces. apparatus.

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