JP2010055124A - Zoom lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zoom lens which is compact, has a simple structure with a small number of components, and surely operates by providing at least three cam grooves or cam protrusions on a synthetic resin-made cam cylinder. <P>SOLUTION: The zoom lens includes: a fixed cylinder; and the synthetic resin-made cam cylinder disposed outside the fixed cylinder, having a protrusion cam for an object-side first lens group and at least two cam grooves for at least two lens groups among the second and subsequent lens groups. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a zoom lens, and more particularly to a zoom lens in which at least two cams for moving at least two group lenses after the first group lens and the second group lens can be formed in one cam cylinder.

In the technique of molding the cam member of the zoom lens barrel with a synthetic resin, the cam follower is brought into surface contact with the cam to improve the impact resistance of both (see, for example, Patent Document 1).
Further, a configuration has been proposed in which a cam or cam follower of a cam mechanism is integrally provided on a zoom operation member made of synthetic resin for a zoom lens (see, for example, Patent Document 2).

As another zoom lens, there has been proposed a zoom lens in which a first group lens cam is provided on the movable frame cylinder, and a first group lens cam follower and a second group lens cam are provided on the inner peripheral surface side of the zoom operation ring. (For example, refer to Patent Document 3).
In another zoom lens, a zoom lens having a convex cam ring provided with cam surfaces on both sides of a molded convex cam that is die-cut in the optical axis direction is formed by a cam surface formed by a fixed side mold and a movable side mold. A configuration in which a parting line is provided between the cam surfaces along the lift amount of the cam surface is disclosed (for example, see Patent Document 4).

JP-A-4-104112 JP 9-203850 A JP-A-9-203851 Japanese Patent No. 2773586

  In these conventional zoom lenses, one or two cam grooves or cam ridges are provided in one cam cylinder to achieve a certain degree of compactness, but it is more compact and has a simple structure with fewer parts. Therefore, there is a demand for a zoom lens having a configuration that operates reliably.

(Object of invention)
The present invention has been made in view of the above-described problems. By providing at least three cam grooves or cam ridges on a synthetic resin cam cylinder, the present invention is compact and reliably has a small number of parts and a simple structure. An object of the present invention is to provide a zoom lens configured to operate.

The present invention
A fixed cylinder;
A synthetic resin cam cylinder disposed outside the fixed cylinder and formed with a projecting cam for the subject-side first group lens and at least two cam grooves for at least two group lenses after the second group lens. When,
A zoom lens characterized by having

Embodiments of the present invention are as follows.
The holding cylinder of the first group lens is arranged outside the cam cylinder.
The first group lens is a focusing lens.
The cam for the first group lens is a projecting cam provided on the outside of the cam cylinder, and the cams for at least two group lenses after the second group lens are cam grooves.
The cam grooves have the same angular phase.

  According to the present invention, by providing at least three cam grooves or cam ridges on a synthetic resin cam cylinder, a compact zoom lens having a small number of parts and a simple structure can be configured. Has the effect of

It is sectional drawing of the wide state of the zoom lens of embodiment of this invention. It is sectional drawing of the tele state of the zoom lens of embodiment of this invention. It is a perspective view of the cam cylinder of the zoom lens of the embodiment of the present invention.

  Next, embodiments of the invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a zoom lens according to an embodiment of the present invention in a wide state, and FIG. The lens system includes a first group lens 10 for focusing with positive power, a second group lens 12 with negative power, and a third group lens 14 with positive power.

  The zoom lens barrel 20 has a plurality of substantially cylindrical members, and is fixed to the mount portion 24 in order from the inside to guide the second group lens 12 and the third group lens 14 in parallel with the optical axis O. The first fixed cylinder 22, the cam cylinder 26 that slides on the outer surface of the first fixed cylinder 22, the first group lens cylinder 28 that slides on the outer surface of the first fixed cylinder 22, and a second, which will be described later, fixed to the mount portion 24. A focusing operation ring 40 that rotates and slides on the outer surface of the fixed cylinder 30, a zoom operation ring 44 that rotates and slides the outer surface of the second fixed cylinder 30 and the outer surface of the second fixed cylinder 30 behind the focusing operation ring 40. . The zoom operation ring 44 is connected to the cam cylinder 26 rearward, that is, on the mount portion 24 side, and both rotate integrally around the optical axis O.

  The first fixed cylinder 22 has a second third rectilinear groove 54 used in common by the second group lens 12 and the third group lens 14, and has a first rectilinear piece 80 at the front end. The first rectilinear piece 80 engages with a first rectilinear groove 82 provided on the inner surface of the first group lens barrel 28. As shown in FIG. 3, the cam cylinder 26, which is a molded product of synthetic resin, includes a first group lens protrusion cam 60 having a rectangular parallelepiped section, and a second group having a section that is widened in the radial direction from the optical axis O. A lens cam groove 62 and a third group lens cam groove 64 having a constant width in the radial direction from the optical axis O are provided.

  The first group lens barrel 28 that supports the first group lens holding frame 70 of the first group lens 10 is a helicoid outer cylinder 90 and a helicoid outer side to which the first group lens holding frame 70 is attached. It consists of a tube 92. As shown in FIG. 2, the helicoid inner cylinder 90 is engaged with a first rectilinear piece 80 which is fixed to the first fixed cylinder 22 and extends beyond the cam cylinder 26 to the front outer side. A groove 82 is provided. The helicoid outer cylinder 92 is connected to the focusing operation ring 40 at the rear thereof via a focusing rotation member (not shown), is slidable in the direction of the optical axis O with respect to the second fixed cylinder 30, and Engagement is performed so that the rotational movement of the focusing ring 40 is transmitted.

  The first group lens barrel 28 has a cam follower 93 that engages with the first group lens protrusion cam 60 on the inner helicoidal cylinder 90. The second group holding frame 102 that holds the second group lens 12 includes a second group lens piece 104 that slides in the second group lens cam groove 62 and the second third rectilinear groove 54 and has an inverted conical portion. The third group holding frame 110 that holds the third group lens 14 has a cylindrical third group lens piece 112 that slides in the third group lens cam groove 64 and the second third rectilinear groove 54.

    Next, the operation of the zoom lens configured as described above will be described. The zoom operation rotates the zoom operation ring 44 and rotates the cam cylinder 26 on the first fixed cylinder 22. When the cam cylinder 26 rotates, the first group lens cylinder 28 whose rotation is restricted by the engagement of the first rectilinear piece 80 and the first rectilinear groove 82 is related to the first group lens protrusion cam 60 and the cam follower 93. As a result, the cam moves along the optical axis O. The second group lens holding frame 102, whose rotation is restricted by the second group lens piece 104 engaging with the second third rectilinear groove 54, is engaged with the second group lens piece 104 and the second group lens cam groove 62. To move the cam along the optical axis O. Further, the third group lens holding frame 110, whose rotation is restricted by the third group lens piece 112 engaging with the second third rectilinear groove 54, is formed between the third group lens piece 112 and the third group lens cam groove 64. The cam moves along the optical axis O by the engagement. In this way, the zoom operation is performed.

  In the focusing operation, the focusing operation ring 40 is rotated, and the helicoid outer cylinder 92 is rotated via a focusing rotating member (not shown). On the other hand, the rotation of the helicoid inner cylinder 90 is restricted by a first rectilinear piece 80 and a first rectilinear groove 82 attached to the first fixed cylinder 22, and the helicoid inner cylinder 90 and the helicoid outer cylinder 92 are engaged with each other. As the helicoid outer cylinder 92 rotates, the helicoid outer cylinder 92 supporting the first lens group holding frame 70 is cam-moved along the optical axis O. In this way, the focusing operation is performed.

O Optical axis 10 First group lens 12 Second group lens 14 Third group lens 21 Zoom lens barrel 22 First fixed barrel 26 Cam barrel 28 First group lens barrel 28
30 second fixed cylinder 40 focusing operation ring 44 zoom operation ring 54 second third straight groove 60 first group lens projection cam 62 second group lens cam groove 64 third group lens cam groove 70 first group lens holding frame 80 first 1 rectilinear piece 82 1st rectilinear groove 90 helicoid inner cylinder 92 helicoid outer cylinder 93 cam follower 102 second group holding frame

Claims (5)

A fixed cylinder;
A synthetic resin cam cylinder disposed outside the fixed cylinder and formed with a projecting cam for the subject-side first group lens and at least two cam grooves for at least two group lenses after the second group lens. When,
A zoom lens comprising:   2. The zoom lens according to claim 1, wherein a holding cylinder of the first group lens is disposed outside the cam cylinder.   The zoom lens according to claim 1, wherein the first group lens is a focusing lens.   2. The cam for the first group lens is a ridge cam provided outside the cam cylinder, and the cams for at least two group lenses after the second group lens are cam grooves. Zoom lens described in 1.   The zoom lens according to claim 1, wherein the cam grooves have the same angular phase.

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