JP2792033B2 - Moving frame structure of zoom lens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention includes first, second, and third moving lens groups arranged in order from the subject side, and the first moving lens group and the third moving lens group move in the same direction in the optical axis direction. The present invention relates to a structure of a moving frame that holds each lens group of a zoom lens in which the moving lens group independently moves in the optical axis direction independently of the other two groups.

[Prior art and its problems]

In a zoom lens optical system having three or more motion components as the motion components of each lens group, two of the lens groups are linked to each other and move almost the same amount in the same direction in the optical axis direction almost simultaneously. Some are configured to do so. That is, these two lens groups as optical components move integrally. Further, the remaining lens groups are configured to move in the optical axis direction independently of the two lens groups. Each of these motion components is a motion for zooming or focusing, and is a motion for adjusting a relative positional relationship (distance between them) in the optical axis direction of each lens group. By the way, at the time of this adjustment movement, in the positional relationship on the optical system between one of the linked lens groups and the independent lens group, the inclination and eccentricity with respect to the optical axis are large in aberration fluctuation such as one-sided blur and coma. This may affect the optical performance of the zoom lens significantly.

[Object of the invention]

The present invention has been made in view of the above-described problems in the related art,
It was created to solve this effectively. Accordingly, an object of the present invention is to provide a moving frame structure of a zoom lens that does not cause aberration fluctuation during zooming or focusing.

[Means for Solving the Problems]

The moving frame structure of the zoom lens according to the present invention has the following configuration in order to solve the above-described problems of the related art and achieve the object. That is, it has first, second, and third moving lens groups arranged in order from the subject side, and the first moving lens group located on the subject side and the third moving lens group located on the image plane side have an optical axis. The second moving lens group, which makes the same movement in the direction and is located between the first moving lens group and the third moving lens group, moves in the optical axis direction different from the first and third moving lens groups. In the structure of the first, second, and third moving frames that hold the first, second, and third moving lens groups, the third moving frame is positioned with respect to the first moving frame. In addition, the movable frame is coupled so as to be relatively movable in a direction orthogonal to the optical axis, and is coupled to the second moving frame so as to be restricted with respect to the movement in the direction orthogonal to the optical axis. Have been. Also preferably, the second moving frame and the third moving frame are:
Between them, they are urged in a direction away from each other in the optical axis direction via a resilient means.

[Action]

In the moving frame structure of the zoom lens according to the present invention, the first moving lens group and the third moving lens group should be coupled so as to have a fixed relationship to each other in the optical axis direction. The third moving lens group is restrained by the first moving lens group only for the movement of, and relative movement is allowed in a direction perpendicular to the optical axis. Further, the third moving lens group is restricted only with respect to the movement in the direction orthogonal to the optical axis with respect to the second moving lens group. Therefore, the third moving lens group moves integrally with the first moving lens group (at the same time in the same direction) in the optical axis direction when performing zooming and focusing, and performs the second movement in the direction orthogonal to the optical axis. The movement is regulated by the lens group.

【Example】

Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. 1 is a half sectional front view showing one embodiment of a moving frame structure of a zoom lens according to the present invention. In the figure, 1 is a first moving lens group, 2 is a second moving lens group, 3 is a third moving lens group, and 4 is a fixed lens group. The first moving frame 5 and the third moving frame 5 holding the first moving lens group 1 so that the first moving lens group 1 and the third moving lens group 3 can move integrally in the optical axis direction when performing zooming and focusing. The third moving frame 7 that holds the moving lens group 3 is assembled so that the relative movement in the axial direction and the circumferential direction is restricted, although the detailed configuration will be described later. The second moving frame 6 holding the second moving lens group 2 is fitted in the second cylindrical portion 15 of the third moving frame 7, and is independent of the third moving frame 7 during zooming. To move in the optical axis direction. The fixed lens group 4 includes a fixed inner cylinder 8
At the front end. Also, the second moving frame 6 and the third moving frame 6
A compression coil spring 25 is mounted between the moving frame 7. FIG. 2 is a perspective view showing the first moving frame 5 of the present embodiment. The first moving frame 5 includes a first cylindrical portion 9 that holds the first moving lens group 1 inward, on the front side (the subject side in a camera mounted state). From the rear end of the first cylindrical portion 9, each of the three first first cylindrical portions 9 extends in the axial direction (coincident with the optical axis direction).
The protrusions 10 and the second protrusions 11 are alternately arranged. First
The projection 10 has a first contact surface 12 whose tip surface is orthogonal to the optical axis direction.
Is formed. The tip of the second projection 11 is bent inward at a right angle in the radial direction to form a first overhang 13. The end face of the first protrusion 13 facing the first cylindrical portion 9 is formed as a second contact surface 14 which is also orthogonal to the optical axis direction. FIG. 3 is a perspective view showing the third moving frame 7 of the present embodiment. The third moving frame 7 has a second cylindrical portion 15 on the inner periphery of which the outer periphery of the second moving frame 6 (see FIG. 1) is fitted.
Therefore, the relative movement in the radial direction of the second moving frame 6 and the third moving frame 7 is restricted to each other, and shows an integral behavior. Further, a flange portion 16 is formed to extend radially outward from an outer peripheral portion on the front side of the second cylindrical portion 15. Flange part 16
In the outer peripheral portion, there is formed a portion that engages with each of the first projection 10 and the second projection 11 in a state where the third moving frame 7 is assembled with the first moving frame 5. First, a portion that engages with the first projection 10 projects further radially outward from the outer peripheral portion of the flange portion 16 and forms a third contact surface 18 that contacts the first contact surface 12. 17 are formed at three locations corresponding to the positions of the first projections 10. One end of each of the second overhangs 17 on the same side in the circumferential direction has a first contact surface.
A stopper portion 19 that protrudes and restricts rotation in the circumferential direction is provided in a state where the 12 and the third contact surface 18 are in contact with each other. A wedge-shaped protrusion 20 is formed on one of the second overhangs 17 at one end in the circumferential direction opposite to the stopper 19. The protrusion 20 allows one of the first moving frame 5 and the third moving frame 7 to relatively rotate in one direction and restricts the rotation in the opposite direction. Is a direction in which each contact surface shifts from a state in which the contact surfaces are separated from each other to a state in which they contact each other.
In addition, the rotation is restricted by the first contact surface 12 and the third contact surface.
This is the rotation from the state where 18 abuts. The contact between the first contact surface 12 and the third contact surface 13 regulates the distance between the first moving frame 5 and the third moving frame 7 so as not to be shortened in the optical axis direction. Next, the portion that engages with the second protrusion 11 is the first protrusion of the second protrusion 11.
It is constituted by a step portion 22 having a fourth contact surface 21 that engages with the overhang portion 13 and contacts the second contact surface 14. The first protrusion 10 is engaged with the step portion 22 by rotating the first protrusion 10 in the above-described permissible direction, and the second contact surface is formed.
The 14 and the fourth contact surface 21 contact each other. Second contact surface 14 and fourth
The contact of the contact surface 21 restricts the distance between the first moving frame 5 and the third moving frame 7 from increasing in the optical axis direction. Since the first projection 10 and the second projection 11 are arranged in a cylindrical shape, the flange portion 16 of the third moving frame 7 is located inside the first projection 10 and the second projection 11 arranged in a cylindrical shape and is mutually connected. Are connected, but the inner diameter of this cylindrical array is
The "play" is given by slightly increasing the outer dimensions of the 16 step portions 22. In addition, the first protrusion 10 and the second
Since there is no restriction on the engagement relationship with the overhang portion 17 in the radial direction, the coupling state between the first moving frame 5 and the third moving frame 7 is restricted only in the optical axis direction and the circumferential direction, and Relative movement is allowed. Therefore, when the cam ring 24 (see FIG. 1) is rotated, the first moving frame 5 and the second moving frame 6 independently move straight in the optical axis direction independently, and the third moving frame 7 is moved in parallel with the first moving frame 5. It moves straight ahead. At this time,
Even if there is a variation in the dimensional accuracy between the second and third moving frames 5, 6, and 7 and a "displacement" occurs in the direction perpendicular to the optical axis, the second moving frame 6 and the third moving frame Relative movement in that direction is restrained with respect to the frame 7, and no relative tilt eccentricity or relative parallel eccentricity occurs between the second moving lens group 2 and the third moving lens group 3. The zooming distance between the second moving lens group 2 and the third moving lens group 3 greatly affects the field curvature, but the relative movement between the second moving frame 6 and the third moving frame 7 is relatively large. If a slight gap is generated between the two as a result of the allowance, a reciprocating difference occurs in the zooming interval. However, in the present embodiment, the second moving frame 6 and the third moving frame 6
Since the compression coil spring 25 is mounted between the second moving frame 6 and the third moving frame 7, “rack” occurs between the second moving frame 6 and the third moving frame 7.
Therefore, the reciprocating difference does not occur. The above-described joining process of the first moving frame 5 and the third moving frame 7 includes:
FIG. 4 and FIG. 5 show the respective moving frames in an expanded manner. FIG. 4 shows a state before the connection, and FIG. 5 shows a state after the completion of the connection. One protrusion
The first contact surface 12 of the ten rides over the wedge-shaped protrusion 20. At this time, since both the first protrusion 10 and the wedge-shaped protrusion 20 are made of plastic, each of them is elastically deformed into a "spring" shape. The width dimension D of the third contact surface 18 is slightly larger than the width dimension d of the first contact surface 12, and the relative rotation between them is restrained with some "play" in the coupled state.

【effect】

As apparent from the above description, according to the present invention, the following excellent effects are exhibited. That is, the third moving lens group is restricted by the first moving lens group with respect to the movement in the optical axis direction, and is allowed to move relative to the first moving lens group in the direction perpendicular to the optical axis, and the second moving lens As a result of being constrained by the group, it is possible to prevent the occurrence of aberration fluctuations during zooming and focusing even if there is a variation in dimensional accuracy between the moving frames.

[Brief description of the drawings]

FIG. 1 is a half sectional front view showing an embodiment of a moving frame structure of a zoom lens according to the present invention, FIG. 2 is a perspective view showing a first moving frame of the present embodiment, and FIG. FIG. 4 and FIG. 5 are perspective views showing the third moving frame, and FIG. 4 and FIG. 5 are exploded explanatory views showing the joining process of the first moving frame and the third moving frame. 1. First moving lens group 2. Second moving lens group 3,
... Third moving lens group, 5... First moving frame, 6.
Moving frame 7, 7 Third moving frame 25 Compression coil spring as resilient means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02B 7/10 G02B 7/04

Claims (2)

(57) [Claims] An image pickup apparatus includes first, second, and third moving lens groups (1, 2, 3) arranged in order from a subject side, and a first moving lens group (1) located on the subject side and an image. The third moving lens group (3) located on the surface side makes the same movement in the optical axis direction, and the second moving lens group (2) located in the middle between the first moving lens group and the third moving lens group. , Moves in the direction of the optical axis different from the first and third moving lens groups (1, 3), and holds the first, second, and third moving lens groups. In the structure of each of the third moving frames (5, 6, 7), the third moving frame (7) is relative to the first moving frame (5) in a direction orthogonal to the optical axis. And movably coupled to the second moving frame (6).
A moving frame structure of a zoom lens, wherein the moving frame structure is coupled so as to be restrained with respect to the movement in a direction perpendicular to the optical axis. 2. The second moving frame (6) and the third moving frame (7).
2. The moving frame structure of the zoom lens according to claim 1, wherein the movable frame is biased in a direction away from each other in the optical axis direction via a resilient means (25) therebetween.