JP4153784B2 - Zoom lens barrel - Google Patents

Description

[0001]
【Technical field】
The present invention relates to an interchangeable zoom lens barrel for a single-lens reflex camera, and more particularly, to a support structure for the focus cam barrel and the zoom cam barrel.
[0002]
[Prior art and its problems]
As an interchangeable zoom lens barrel with a relatively simple structure for a single-lens reflex camera, it supports a focus operation ring and a zoom operation ring that can be rotated independently of a fixed cylinder fixed to the camera body. A focus cam cylinder that rotates together with the zoom lens to advance and retract the focus lens group in the optical axis direction, and a zoom cam cylinder that rotates together with the zoom operation ring and advances and retracts the variable magnification lens group in the optical axis direction by rotation. A lens barrel provided with is known. The focus cam cylinder and the zoom cam cylinder have a mode in which they are screw-coupled to the fixed cylinder and a mode in which the movement in the optical axis direction is simply restricted and supported by the fixed cylinder.
[0003]
In the latter mode, conventionally, there is a configuration in which a pressing ring for restricting movement in the optical axis direction is provided for each of the focus cam barrel and the zoom cam barrel, or a configuration in which the focusing cam barrel and the zoom cam barrel are brought into contact with each other so that the pressing ring is single. Are known. However, the former requires two holding rings, and the latter is in contact with the focus cam barrel and the zoom cam barrel, which may cause unexpected rotation of each other.
[0004]
[Patent Literature]
Japanese Utility Model Publication No. 2-41210 [0005]
OBJECT OF THE INVENTION
The present invention is based on the above problem awareness of the conventional zoom lens barrel, and can control the position of the focus cam barrel and the zoom cam barrel in the optical axis direction with a single press ring. An object of the present invention is to obtain a zoom lens barrel that does not abut.
[0006]
SUMMARY OF THE INVENTION
The present invention relates to a fixed cylinder fixed to a camera body; a focus operation ring and a zoom operation ring that are supported so as to be independently rotatable by the fixed cylinder; and rotates together with the focus operation ring. A zoom lens barrel having: a focus cam barrel that advances and retracts the lens group in the optical axis direction; and a zoom cam barrel that rotates together with the zoom operation ring and advances and retracts the variable power lens group in the optical axis direction by rotation. A large-diameter portion that rotatably supports one of the two cam cylinders on the fixed cylinder, and a first abutting section having a larger diameter than the large-diameter section provided at one end of the large-diameter section When the diameter in which is located between a small diameter portion which rotatably supports the other of the two cam tube, the end portion and the small diameter portion opposite to said first contact portion of the large diameter portion, and a second contact portion which connects the middle diameter portion and a small diameter portion formed, this Supporting the ring retainer in diameter, one end face of one of the cam cylinder above is brought into contact with the first contact portion, at one end of the other of the cam barrel, abuts on the second abutting portion A first flange extending in the radial direction is formed, and the pressing ring is formed on one end face, and is formed on the other end face of the one cam cylinder and on the other end. And a second flange extending in the radial direction that sandwiches the first flange with the second contact portion .
[0007]
According to this configuration, the movement of the both cam cylinders in the optical axis direction can be restricted by a single pressing ring.
[0009]
The press ring may be in the form of being bayonet-coupled to the middle diameter part or fixed with a set screw, but the form of screwing is the simplest in structure and assembly.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
1 to 3 show an embodiment of a zoom lens barrel according to the present invention. The fixed cylinder 10 fixed to the camera body has an outer fixed cylinder 11 and an inner fixed cylinder 12. A focus operation ring 13 is rotatably supported on the outer periphery of the outer fixed cylinder 11 and a zoom operation ring 14 is rotatably supported on the rear outer periphery. Reference numeral 15 denotes a retaining ring that restricts movement of the zoom operation ring 14 in the optical axis direction.
[0011]
The inner fixed cylinder 12 includes a first lens group fixing portion 12a, a large diameter portion 12b, a medium diameter portion 12c, a small diameter portion 12d, and a bayonet portion 12e in order from the front. Further, a first contact portion 12f is formed between the first lens group fixing portion 12a and the large diameter portion 12b, and a second contact portion 12g is formed between the medium diameter portion 12c and the small diameter portion 12d. The lens system of the present embodiment includes, in order from the object side, a fixed lens group L1, a focus lens group L2, a variable power lens group L3, L4, and a fixed lens group L5. The fixed lens group L1 is fixed to the first group lens. The fixed lens unit L5 is fixed to the portion 12a, and is fixed to the rear portion of the small diameter portion 12d. The bayonet part 12e is attached to and detached from the camera body.
[0012]
A second group frame 16 to which the focus lens group L2 is fixed is positioned inside the large diameter portion 12b , and a focus cam cylinder 17 is rotatably positioned outside. The front end surface of the focus cam cylinder 17 is in contact with the first contact portion 12f. The follower pin 16a protruded from the second group frame 16 in the radial direction includes a straight guide groove 12b1 parallel to the optical axis formed in the large diameter portion 12b and a cam groove (lead groove) 17a formed in the focus cam cylinder 17 (see FIG. 2). ). Further, the rotation transmission pin 17b protruded in the radial direction from the focus cam cylinder 17 is fitted into a rotation transmission hole 13a formed in the inner peripheral surface of the focus operation ring 13 through a circumferential groove 11a formed in the outer fixed cylinder 11. waiting. Accordingly, when the focus operation ring 13 is rotated in the forward and reverse directions, the focus cam cylinder 17 is rotated together, and the second group frame 16 (focus lens group L2) guided in the straight advance guide groove 12b1 is guided by the cam groove 17a. Focusing is performed by moving back and forth in the axial direction.
[0013]
Inside the small-diameter portion 12d, a third group frame 18 to which the variable power lens unit L3 is fixed and a fourth group frame 19 to which the variable power lens unit L4 are fixed are located in order from the front, and the zoom cam cylinder 20 is rotated to the outside. It is located freely. The front end surface of the outer flange (first flange) 20d formed at the front end portion of the zoom cam cylinder 20 is in contact with the rear end surface of the second contact portion 12g. The follower pin 18a protruded in the radial direction from the third group frame 18 is fitted into a straight guide groove 12d1 parallel to the optical axis formed in the small diameter portion 12d and a cam groove 20a (see FIG. 3) formed in the zoom cam barrel 20. . Similarly, the follower pin 19a protruded in the radial direction from the fourth group frame 19 is fitted into a rectilinear guide groove 12d2 parallel to the optical axis formed in the small diameter portion 12d and a cam groove 20b (see FIG. 3) formed in the zoom cam barrel 20. waiting. Further, the rotation transmission pin 20 c projected from the zoom cam cylinder 20 in the radial direction is fitted into a rotation transmission hole 14 a formed on the inner peripheral surface of the zoom operation ring 14 through a circumferential groove 11 b formed in the outer fixed cylinder 11. ing. Accordingly, when the zoom operation ring 14 is rotated in the forward and reverse directions, the zoom cam barrel 20 is rotated together, and the third group frame 18 (variable magnification lens group L3) guided in the straight direction by the straight guide groove 12d1 and the straight guide groove 12d2. The fourth group frame 19 (variable magnification lens group L4) is moved forward and backward in the optical axis direction according to the cam groove 20a and the cam groove 20b to perform zooming.
[0014]
A pressing ring 21 that regulates the position of the focus cam cylinder 17 and the zoom cam cylinder 20 in the optical axis direction is screwed into the middle diameter portion 12 c of the inner fixed cylinder 12. When the front end surface 21a is fully screwed into the middle diameter portion 12c so that the front end surface 21a contacts the step portion between the large diameter portion 12b and the middle diameter portion 12c, the front end surface 21a It contacts the rear end face. Further, an inner flange (second flange) 21 b is formed at the rear end portion of the presser ring 21, and an outer flange (first flange) formed at the front end portion of the zoom cam barrel 20 by this inner flange 21 b. Engage with 20d. That is, the front end face 21 a constitutes an optical axis direction position regulating surface that engages with the focus cam cylinder 17 and regulates its optical axis direction position, and the inner flange 21 b engages with the outer flange 20 d of the zoom cam cylinder 20. An optical axis direction position regulating surface for regulating the position in the optical axis direction is configured .
[0015]
Therefore, the zoom lens barrel having the above-described configuration can restrict the position of the focus cam barrel 17 and the zoom cam barrel 20 in the optical axis direction by the pressing ring 21 alone. Since the focus cam cylinder 17 and the zoom cam cylinder 20 are not in contact with each other, in the focusing performed by rotating the focus operation ring 13 or the zooming performed by rotating the zoom operation ring 14, one rotation is performed in the other direction. Does not affect movement.
[0016]
The inner fixed cylinder 12 of the above embodiment has the large-diameter portion 12b , the medium-diameter portion 12c, and the small-diameter portion 12d, but there is a degree of freedom in the configuration of the other portions. For example, the present invention can be applied to a zoom lens system in which the first group lens fixing portion 12a (fixed lens group L1) is omitted, and the support mode (presence / absence) of the fixed lens group L5 is not limited. Further, in the above embodiment, the focus cam cylinder 17 (focus operation ring 13) is disposed in the front and the zoom cam cylinder 20 (zoom operation ring 14) is disposed in the rear. However, the front-rear relationship may be reversed.
[0017]
4 and 5 show a conventional zoom lens barrel. 4 shows a conventional example in which a holding ring 31 and a holding ring 32 are provided for the focus cam cylinder 17 and the zoom cam cylinder 20, respectively, and FIG. 5 shows the front end surface of the zoom cam cylinder 20 at the rear end of the focus cam cylinder 17. This is an example in which an inner flange 17X that is in contact is provided and a single retaining ring 33 is used. Other parts are the same as those of the zoom lens barrel of FIG.
[0018]
【The invention's effect】
According to the present invention, a zoom lens barrel can be obtained in which the position of the focus cam barrel and the zoom cam barrel in the optical axis direction can be regulated with a single press ring, and the two cam barrels are not brought into contact with each other. be able to.
[Brief description of the drawings]
FIG. 1 is an upper half longitudinal sectional view showing an embodiment of a zoom lens barrel according to the present invention.
FIG. 2 is a development view taken along the arrow II in FIG. 1;
FIG. 3 is a development view taken along arrow III in FIG. 1;
FIG. 4 is an upper half sectional view showing an example of a conventional zoom lens barrel.
FIG. 5 is an upper half sectional view showing another example of a conventional zoom lens barrel.
[Explanation of symbols]
L1 fixed lens group L2 focus lens group L3 variable magnification lens group L4 variable magnification lens group L5 fixed lens group 10 fixed cylinder 11 outer fixed cylinder (fixed cylinder)
11a circumferential groove 11b circumferential groove 12 inner fixed cylinder (fixed cylinder)
12a First lens group fixing portion 12b Large diameter portion 12b1 Straight guide groove 12c Medium diameter portion 12d Small diameter portion 12d1 Straight guide groove 12d2 Straight guide groove 12e Bayonet portion
12f 1st contact part
12g 2nd contact part 13 Focus operation ring 13a Rotation transmission hole 14 Zoom operation ring 14a Rotation transmission hole 16 2nd group frame 17 Focus cam cylinder 18 3rd group frame 19 4th group frame 20 Zoom cam cylinder 20a Cam groove 20b Cam groove 20c Rotation transmission Pin 20d Outer flange (first flange)
21 Retaining ring
21b Inner flange (second flange)

Claims (2)

A fixed cylinder fixed to the camera body;
A focus operation ring and a zoom operation ring supported by the fixed cylinder so as to be independently rotatable.
A focus cam cylinder that rotates together with the focus operation ring and moves the focus lens group forward and backward in the optical axis direction by rotation; and a zoom cam ring that rotates together with the zoom operation ring and rotates the zoom lens group to the optical axis Zoom cam barrel that advances and retracts in the direction;
In a zoom lens barrel having
A large-diameter portion that rotatably supports one of the two cam cylinders on the fixed cylinder, and a first abutting section having a larger diameter than the large-diameter section provided at one end of the large-diameter section When the diameter in which is located between a small diameter portion which rotatably supports the other of the two cam tube, the end portion and the small diameter portion opposite to said first contact portion of the large diameter portion, Forming a second abutting portion connecting the medium diameter portion and the small diameter portion ;
Support the press ring on this medium diameter part ,
One end surface of the one cam cylinder contacts the first contact portion,
Forming a first flange extending in a radial direction in contact with the second contact portion at one end of the other cam cylinder;
The holding ring is formed between one optical axis position regulating surface formed on one end surface and contacting the other end surface of the one cam cylinder, and the second contact portion formed on the other end. A zoom lens barrel , comprising: a second flange extending in a radial direction that sandwiches the first flange . 2. The zoom lens barrel according to claim 1, wherein the holding ring is screwed into the middle diameter portion.

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