JP2002258134A - Lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized lens barrel in which a lens group is smoothly moved and the focus position is stabilized and whose durability is high. SOLUTION: First and second bearings 6-1 and 6-2 are made to abut on both side surfaces of a cam groove 7a by a pressing member 8, to eliminate a backlash at the cam groove 7a so that the position of a rear group lens L2 is stabilized. Also, first and second outer ring regulating parts 4a-1, 4a-2, 5a-1 and 5a-2 to regulate first and second outer rings 6b-1 and 6b-2 are provided so that a stable operation is assured even though a caught amount between the first and second bearings 6-1 and 6-2 and the cam groove 7a is small, thereby obtaining high durability in this lens barrel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel such as a camera and a video camera, and a lens barrel such as an interchangeable lens used for the same.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view of a conventional lens barrel. The conventional lens barrel includes a fixed barrel 1, a front group lens L1,
It has a rear group lens L2, a moving frame 20, a guide pin 9, a cam member 70, and the like.

The fixed cylinder 1 has a bayonet 1a so that it can be mounted on a camera body (not shown), and is a member fixed to the camera body. It has a straight hole 1b that extends. The front group lens L1 is a lens group necessary for forming an image at an image forming position of the camera body, and is fixed to the fixed barrel 1. The rear lens group L2 is a focusing lens group that moves in the direction of the optical axis M. By moving the rear lens group L2, it is possible to focus on an image forming position of a camera body for various subjects. Front group lens L1 and rear group lens L
2 forms a photographing optical system. Moving frame 20
Is a frame member fixing the rear group lens L2. The guide pin 9 is a pin that is fitted into the rectilinear hole 1 b of the fixed cylinder 1, is further fitted into a cam groove 70 a of a cam member 70 described later, and is implanted in the moving frame 20. The cam member 70 is
It is a member that is fitted to the fixed cylinder 1 so that it can only rotate, and the guide pin 9 is fitted into the cam groove 70a.

Next, the operation of the conventional lens barrel when focusing will be described. The moving frame 20 includes a cam member 70.
When the guide pin 9 rotates, the cam pin 70a and the fixed cylinder 1
Is moved in the direction of the optical axis M while being guided by the rectilinear hole 1b.
Since the rear group lens L2 is fixed to the moving frame 20,
It moves in the direction of the optical axis M. Therefore, when the cam member 70 is rotated, the rear group lens L2 moves in the direction of the optical axis M, and can perform focusing.

[0005]

However, the above-mentioned conventional lens barrel has a problem that a play in the direction of the optical axis M occurs between the cam groove 70a and the guide pin 9. If there is play in the direction of the optical axis M, the optical axis M of the rear lens group L2
The position in the direction becomes unstable, and the focus position on the image plane becomes unstable. This instability is caused by the optical axis M of the rear lens group L2.
It becomes more serious as the ratio of the focus movement amount on the imaging plane to the movement amount in the direction increases. In order to reduce the backlash, it is necessary to increase the precision of the parts, which is a factor that causes a very high manufacturing cost. In addition, no matter how high the accuracy of the parts, the play can not be completely eliminated in order to move the moving frame 20 smoothly. To reduce the size of the lens barrel, it is effective to reduce the amount of engagement D between the cam groove 70a and the guide pin 9. However, if the amount of engagement D is reduced, the cam groove 70a and the guide pin 9 However, there is also a problem that abrasion is likely to occur due to wear and durability is deteriorated.

[0006] In order to solve the above-mentioned problem of the play, a lens play mechanism is provided in which a guide pin is applied to the cam groove by an urging member to eliminate the problem that the focus position becomes unstable due to the play. If the cylinder is, for example,
No. 122609 discloses this.

However, in the lens barrel provided with the above-described backlash removing mechanism, there is a problem that the durability is further deteriorated because the guide pin operates in a state where the guide pin is applied to the cam groove by the urging member.

An object of the present invention is to provide a small-sized lens barrel in which the movement of the lens group is smooth, the focus position is stable, and the durability is high.

[0009]

The present invention solves the above-mentioned problems by the following means. In addition, in order to make it easy to understand, description is given with reference numerals corresponding to the embodiment of the present invention, but the present invention is not limited to this. That is, the first aspect of the present invention provides a photographing optical system (L1, L2)
A first moving frame (2) provided with a part (L2) of the photographing optical system and movable at least in an optical axis direction of the photographing optical system; and a cam groove for driving the first moving frame. (7
a) and a first bearing (6-) fixed on the circumference of the first moving frame and having an outer ring (6b-1) engaged with at least one side surface of the cam groove. 1) and
An urging member (8) for urging the first bearing against the side surface of the cam groove via the first moving frame; Outer ring restricting portions (4) that are provided at an appropriate distance (A1, A2), and that restrict displacement of the outer ring in the direction along the rotation axis.
a-1, 4a-2, 5a-1, 5a-2).

According to a second aspect of the present invention, in the lens barrel according to the first aspect, at least the photographing optical systems (L1, L
2) a second moving frame (3) movable in the optical axis direction; A second bearing (6) engaged with and fixed on the circumference of the second moving frame.
-2), wherein the biasing member (8) biases the second bearing also to the opposite side surface via the second moving frame. It is a lens barrel.

[0011] The invention of claim 3 is claim 1 or claim 2.
Wherein the cam groove (7a) engages with the first bearing (6-1) and / or the second bearing (6-2) in an amount of engagement of the outer ring. (6b-1, 6b-2) is not more than half the width of the lens barrel.

[0012]

Embodiments of the present invention will be described below in more detail with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of a lens barrel according to the present invention. FIG. 2 is an enlarged view of a main part of FIG. In addition, the part which performs the same function as the above-mentioned conventional technology includes:
The same reference numerals are given and duplicate description will be appropriately omitted. The lens barrel in the present embodiment includes a fixed barrel 1, a front lens group L1, a rear lens group L2, a first moving frame 2, a second moving frame 3, a first and a second straight guide pin 4-1. 4-2, first and second bearing fixed shafts 5-1 and 5-2, first and second bearings 6-1 and 6-2, a cam member 7, a pressing member 8, and the like are provided. .

Fixed cylinder 1, front lens group L1, rear lens group L
Reference numeral 2 denotes a member having the same function as the above-described conventional technology. The first moving frame 2 is a frame member fixing the rear group lens L2. The second moving frame 3 is a member fitted to the fixed cylinder 1.

First and second rectilinear guide pins 4-1 and 4
Reference numeral -2 denotes a pin fitted into the rectilinear hole 1b of the fixed cylinder 1 and implanted in each of the first moving frame 2 and the second moving frame 3, and the first and second bearings 6-1 and -1. The first and second outer ring regulating portions 4a-1 and 4a-2 are provided in the rotation axis direction of the outer rings 6b-1 and 6b-2 included in 6-2. First
The second outer ring restricting portions 4a-1 and 4a-2 are provided so as to have a slight interval A1 between the first and second outer rings 6b-1 and 6b-2.

First and second bearing fixed shafts 5-1 and 5-1.
5-2 are first and second straight guide pins 4-1 and 4-
2 and the first and second bearings 6-
1, 6-2, which are the shafts for fixing the first and second outer races 6
It has first and second outer ring regulating portions 5a-1 and 5a-2 in the rotation axis direction of b-1 and 6b-2. The first and second outer ring restricting portions 5a-1, 5a-2 are similar to the first and second outer ring restricting portions 4a-1, 4a-2, respectively. 2 is provided so that a slight interval A2 occurs.

First and second bearings 6-1 and 6-2
Are first and second bearing fixed shafts 5-1 and 5-1 provided on the first and second moving frames 2 and 3 via the first and second linear guide pins 4-1 and 4-2, respectively. It is a ball bearing unit fixed to 5-2. First and second
Bearings 6-1 and 6-2 of the first and second inner races 6
a-1, 6a-2 and the first and second outer rings 6b-1, 6b
b-2.

The cam member 7 is fitted to the fixed cylinder 1 so as to be rotatable only, and the first and second moving frames 2 and 3 are respectively fitted to the side of the cam groove 7a on the subject side and the side opposite to the side. Is a cam frame with which the first and second outer races 6b-1 and 6b-2 provided in the cam frame are in contact. First and second bearings 6
The amount of engagement between -1, 6-2 and the cam groove 7a is less than half the width of the first and second outer rings 6b-1, 6b-2. This is because the lens barrel can be reduced in size by reducing the amount of hanging.

The pressing member 8 is provided between the first moving frame 2 and the second moving frame 3, and is provided between the first moving frame 2 and the second moving frame 2.
Of the moving frame 3 in the direction along the optical axis M.

According to the above configuration, since the cam groove 7a and the first and second bearings 6-1 and 6-2 are firmly contacted by the pressing member 8, no backlash occurs. The position of the lens L2 in the direction of the optical axis M is stabilized, and the operation becomes smooth. Further, even if the amount of engagement between the first and second bearings 6-1 and 6-2 and the cam groove 7a is small, the abrasion resistance is increased and the durability can be enhanced.

Here, the first and second outer ring regulating portions 4a-
1, 4a-2 and the first and second outer ring regulating portions 5a-1, 5
a-2 (hereinafter, collectively referred to as outer ring regulating portions 4a, 5a
) Will be described. FIG. 3 shows a lens barrel having a form similar to that of the present embodiment, in which outer ring restricting portions 4a,
It is a figure assuming the case where 5a is not provided. In this embodiment, in order to prevent backlash, the cam groove 7a and the first and second
The bearings 6-1 and 6-2 are always in force because they are in contact with the pressing member 8. Further, since the amount of engagement between the first and second bearings 6-1 and 6-2 and the cam groove 7a is less than half the width of the outer ring 6b, the pressing member 8
As shown in FIG. 3, the first and second outer rings 6
b-1 and 6b-2 are replaced with first and second inner rings 6a-1 and 6a.
-2. Therefore, in this configuration, when the focusing operation is repeated, the first outer ring 6b-1 or the second outer ring 6b-2 falls off from the first inner ring 6a-1 or the second inner ring 6a-2. There are cases.

In order to prevent this drop, the cam groove 7a
It is sufficient to secure a sufficient amount of engagement between the first and second outer rings 6b-1 and 6b-2. In such a case, the radial thickness of the cam member 7 must be increased, and the lens The outer diameter of the lens barrel increases. Therefore, in the present embodiment, the first and second outer rings 6b are provided by providing the outer ring regulating portions 4a and 5a to regulate the runout of the first and second outer rings 6b-1 and 6b-2 in the rotation axis direction. -1 and 6b-2, the wear of the bearing balls can be reduced, and the first and second outer races 6b are repeatedly operated.
-1, 6b-2 can be prevented from coming off. Therefore, durability can be secured at a high level.

The outer ring restricting portions 4a and 5a are spaced from each other by a distance A1.
And A2, the first and second bearings 6-1 and 6-2 are provided when the first and second outer races 6b-1 and 6b-2 are operating normally. Does not affect the first and second moving frames 2 and 3 smoothly.

According to the present embodiment, since the cam groove 7a and the first and second bearings 6-1 and 6-2 abut firmly by the pressing member 8, no backlash occurs and the rear lens group L2 Is stabilized in the direction of the optical axis M, and the operation becomes smooth. Further, the first and second bearings 6-1 and 6-1.
Even if the amount of engagement between 6-2 and the cam groove 7a is small, the wear resistance is increased, and the outer ring does not fall off due to the pressing force, so that the durability can be increased.

(Modifications) Various modifications and changes are possible without being limited to the above-described embodiments, and these are also within the equivalent scope of the present invention. For example, in the present embodiment, an example is shown in which the outer ring restricting portions 4a, 5a are provided on both sides of the first and second outer rings 6b-1, 6b-2, but only the outer ring restricting portion 4a may be provided, or the outer ring restricting portion may be provided. Only the part 5a may be used.

Further, in this embodiment, the case where the lens relating to focus is moved has been described. However, the present invention is not limited to this. For example, the present invention may be applied to the case relating to zoom.

Further, in the present embodiment, the configuration of the lens group of the lens barrel, the arrangement of the cam members, and the like are merely examples, so long as the cam followers of the moving member driven by the cam grooves are used. It may be a lens barrel.

Further, the moving frame is not limited to the moving frame for directly moving the lens, and may be a moving frame for moving something by using the relative movement between the cam and the bearing so as to prevent play.

[0028]

As described above in detail, according to the first aspect of the present invention, the first bearing that engages with at least one side surface of the cam groove, and the first bearing is attached to the side surface of the cam groove. Since the urging member and the outer ring restricting portion for restricting displacement of the outer ring in the direction along the rotation axis are provided, the movement of the lens group is smooth, the focus position is stable, and the durability can be increased. .

According to the second aspect of the present invention, the second moving frame and the second bearing are provided, and the urging member urges the second bearing also on the opposite side surface. A stable urging force can be easily obtained, the movement of the lens group can be made smoother, the urging members can be arranged with a good space efficiency, and the lens barrel can be downsized.

According to the third aspect of the present invention, the amount of engagement of the portion where the cam groove engages with the first bearing and / or the second bearing is less than half the width of the outer ring. The lens barrel is smooth, the focus position is stable, and the lens barrel having high durability can be reduced in size.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a lens barrel according to the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a view assuming a case where outer ring regulating portions 4a and 5a are not provided in a lens barrel having the same configuration as that of the present embodiment.

FIG. 4 is a sectional view of a conventional lens barrel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed cylinder L1 Front group lens L2 Rear group lens 2 First moving frame 3 Second moving frame 4-1 and 4-2 First and second straight guide pins 5-1 and 5-2 First and second 2 bearing fixed shaft 6-1, 6-2 first and second bearings 7 cam member 8 pressure member

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Kunihiro Fukino 3-2-3 Marunouchi, Chiyoda-ku, Tokyo F-term in Nikon Corporation (reference) 2H044 BD01 BD07 BD08 BD10 BD16 BD18

Claims (3)

[The claims] 1. An imaging optical system, a first moving frame provided with a part of the imaging optical system and movable at least in an optical axis direction of the imaging optical system, and driving the first moving frame. A cam frame having a cam groove, a first bearing fixed on a circumference of the first moving frame, and an outer ring engaged with at least one side surface of the cam groove, via the first moving frame A biasing member for biasing the first bearing against the side surface of the cam groove; and a biasing member provided at a slight distance from the outer ring in at least one of directions along a rotation axis of the outer ring to rotate the outer ring. A lens barrel comprising: an outer ring regulating unit that regulates displacement in a direction along an axis. 2. The lens barrel according to claim 1, wherein the second lens barrel is movable at least in an optical axis direction of the photographing optical system.
And a second bearing fixed on a circumference of the second moving frame, the second bearing being engaged with a side surface of the cam groove with which the first bearing is engaged and opposite to the one side surface. And a biasing member that biases the second bearing also to the opposite side surface via the second moving frame. 3. The lens barrel according to claim 1, wherein the cam groove is formed on the first bearing and / or the second bearing.
Wherein the amount of engagement of the portion engaging with the bearing is not more than half of the width of the outer ring.