JP4724927B2 - Lens barrel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens barrel such as a camera or a video camera, and a lens barrel such as an interchangeable lens used therefor.
[0002]
[Prior art]
FIG. 4 is a cross-sectional view of a conventional lens barrel.
The conventional lens barrel includes a fixed barrel 1, a front group lens L1, a rear group lens L2, a moving frame 20, a guide pin 9, a cam member 70, and the like.
[0003]
The fixed cylinder 1 has a bayonet 1a so that it can be attached to a camera body (not shown), is a member fixed to the camera body, and extends straight in the direction of the optical axis into which a guide pin 9 described later is inserted. 1b.
The front lens group L1 is a lens group necessary for forming an image at the imaging position of the camera body, and is fixed to the fixed cylinder 1.
The rear group lens L2 is a focusing lens group that moves in the direction of the optical axis M. By moving the rear group lens L2, it is possible to focus on the imaging position of the camera body with respect to various subjects.
The front lens group L1 and the rear lens group L2 form a photographing optical system.
The moving frame 20 is a frame member that fixes 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 a member that is fitted to the fixed cylinder 1 so as to be rotatable only, and the guide pin 9 is fitted into the cam groove 70a.
[0004]
Next, the operation during focusing of the conventional lens barrel will be described.
When the cam member 70 rotates, the moving frame 20 moves in the direction of the optical axis M, with the guide pin 9 guided by the cam groove 70a and the rectilinear hole 1b of the fixed cylinder 1.
Since the rear lens group 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 be focused.
[0005]
[Problems to be solved by the invention]
However, the above-described conventional lens barrel has a problem that the play in the optical axis M direction is generated between the cam groove 70a and the guide pin 9. If there is a backlash in the optical axis M direction, the position of the rear lens group L2 in the optical axis M direction becomes unstable, and the focus position on the imaging plane becomes unstable. This instability becomes more serious as the ratio of the amount of focus movement on the imaging surface to the amount of movement of the rear lens group L2 in the direction of the optical axis M increases.
In order to reduce the backlash, it is necessary to increase the accuracy of the parts, which has been a factor in increasing the manufacturing cost. Moreover, no matter how high the accuracy of the parts, in order to move the moving frame 20 smoothly, the backlash cannot be completely eliminated.
In order 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 are reduced. There is also a problem that wear is likely to occur due to wear, and durability is deteriorated.
[0006]
In order to solve the above-mentioned backlash problem, a lens barrel that provides a backlash removal mechanism that applies a guide pin to the cam groove by a biasing member, and that solves the problem that the focus position becomes unstable due to backlash, For example, it is disclosed in JP-A-8-122609.
[0007]
However, the lens barrel having the above-described rattling mechanism operates in a state where the guide pin is applied to the cam groove by the urging member, so that there is a problem that durability is further deteriorated.
[0008]
An object of the present invention is to provide a small lens barrel in which the movement of the lens group is smooth, the focus position is stable, and the durability is high.
[0009]
[Means for Solving the Problems]
According to the first aspect of the present invention, a photographing optical system (L2), a part of the photographing optical system, a movable frame (2) movable at least in the optical axis direction of the photographing optical system, and a cam groove (7a) are provided. ) Having a cam frame (7), an outer ring (6b-1) rotating relative to the inner ring (6a-1), a bearing (6-1) engaging with the cam groove, and the moving frame. A support portion (4-1) for supporting the inner ring; and a fixing portion (5-1) for fixing the inner ring so as to sandwich the inner ring between the support portion and the fixing portion (5- 1) at least a part of the outer ring is opposed to the outer ring in a direction along the rotation axis of the outer ring, is provided at a distance from the outer ring , and restricts displacement in the direction along the rotation axis of the outer ring ; and At least a part of the support portion (4-1) is arranged in the direction along the rotation axis of the outer ring. And edge and opposite diameter, provided at a edge and spacing of the outer diameter side of the outer ring, to restrict the displacement in a direction along the rotation axis of the outer ring is the lens barrel, wherein .
[0011]
Direction of invention of claim 2, the lens barrel according to claim 1, in the direction along the rotary shaft, takes amount of said outer ring and said cam groove (7a) is along the rotation axis of the outer ring The lens barrel is characterized in that it is less than half the length of the lens barrel.
According to a third aspect of the present invention, in the lens barrel according to the first or second aspect , the bearing includes a first bearing (6-1) and a second bearing (6-2). One bearing (6-1) is urged by the urging member so as to engage with one side surface of the cam groove, and the second bearing (6-2) is urged by the urging member to the one side surface of the cam groove. It is urged | biased so that it may engage with the opposite side surface.
A fourth aspect of the present invention is the lens barrel according to any one of the first to third aspects, wherein the support portion is implanted in the moving frame and engages with a rectilinear groove. A lens barrel characterized by being a guide pin.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing an embodiment of a lens barrel according to the present invention.
FIG. 2 is an enlarged view of the main part of FIG.
In addition, the same code | symbol is attached | subjected to the part which performs the function similar to the prior art mentioned above, and the overlapping description is abbreviate | omitted suitably.
The lens barrel in the present embodiment includes a fixed barrel 1, a front group lens L1, a rear group lens L2, a first moving frame 2, a second moving frame 3, first and second rectilinear guide pins 4-1, 4-2, first and second bearing fixed shafts 5-1, 5-2, first and second bearings 6-1, 6-2, cam member 7, pressure member 8 and the like. .
[0013]
The fixed cylinder 1, the front group lens L1, and the rear group lens L2 are members having functions similar to those of the above-described conventional technology.
The first moving frame 2 is a frame member that fixes the rear lens group L2.
The second moving frame 3 is a member fitted to the fixed cylinder 1.
[0014]
The first and second rectilinear guide pins 4-1 and 4-2 are inserted into the rectilinear holes 1b of the fixed cylinder 1 and are respectively implanted in the first moving frame 2 and the second moving frame 3. The first and second outer ring restricting portions 4a-1 and 4a-2 are provided in the rotation axis direction of the outer rings 6b-1 and 6b-2 of the first and second bearings 6-1 and 6-2. is doing. The first and second outer ring regulating portions 4a-1 and 4a-2 are provided such that a slight interval A1 is generated between the first and second outer rings 6b-1 and 6b-2.
[0015]
The first and second bearing fixing shafts 5-1 and 5-2 are implanted in the first and second linear guide pins 4-1 and 4-2, and the first and second bearing 6- 1, 6-2, and has first and second outer ring restricting portions 5 a-1 and 5 a-2 in the rotation axis direction of the first and second outer rings 6 b-1 and 6 b-2. ing. The first and second outer ring restricting portions 5a-1, 5a-2 are the same as the first and second outer ring restricting portions 4a-1, 4a-2, and the first and second outer rings 6b-1, 6b-. 2 is provided such that a slight gap A2 is generated.
[0016]
The first and second bearings 6-1 and 6-2 are provided on the first and second moving frames 2 and 3 via the first and second rectilinear guide pins 4-1 and 4-2, respectively. It is a ball bearing unit fixed to the first and second bearing fixing shafts 5-1 and 5-2. The first and second bearings 6-1 and 6-2 include first and second inner rings 6a-1 and 6a-2 and first and second outer rings 6b-1 and 6b-2. ing.
[0017]
The cam member 7 is fitted to the fixed cylinder 1 so as to be rotatable only, and is provided on the first and second moving frames 2 and 3 with respect to the subject side surface and the opposite side surface of the cam groove 7a. The cam frame is in contact with the first and second outer rings 6b-1 and 6b-2.
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 first and second outer rings 6b-1 and 6b-2. This is because the lens barrel can be reduced in size by reducing the amount of engagement.
[0018]
The pressure member 8 is provided between the first moving frame 2 and the second moving frame 3, and the first moving frame 2 and the second moving frame 3 are arranged along the optical axis M. It is the urging member which is urging | biasing in the direction which a mutual distance leaves | separates in a direction.
[0019]
According to the above-described configuration, the cam groove 7a and the first and second bearings 6-1 and 6-2 are firmly brought into contact with each other by the pressure member 8, so that no backlash occurs. The position in the direction of the optical axis M is stabilized and the operation is smooth.
Further, even if the amount of engagement between the first and second bearings 6-1 and 6-2 and the cam groove 7 a is small, the wear resistance is increased and the durability can be enhanced.
[0020]
Here, the first and second outer ring restricting portions 4a-1, 4a-2 and the first and second outer ring restricting portions 5a-1, 5a-2 (hereinafter, these are collectively referred to as the outer ring restricting portions 4a, 5a). Will be explained.
FIG. 3 is a diagram assuming a case where the outer ring restricting portions 4a and 5a are not provided in a lens barrel having the same form as the present embodiment.
In the present embodiment, in order to prevent backlash, the cam groove 7 a and the first and second bearings 6-1 and 6-2 are in contact with each other by the pressurizing member 8, so that a force is always applied. .
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 force by the pressing member 8 is as shown in FIG. A moment is generated to try to remove the first and second outer rings 6b-1, 6b-2 from the first and second inner rings 6a-1, 6a-2. Therefore, in the configuration as it is, when the focusing operation is repeated, the first outer ring 6b-1 or the second outer ring 6b-2 is dropped from the first inner ring 6a-1 or the second inner ring 6a-2. There is a case.
[0021]
In order to prevent this drop-off, a sufficient amount of engagement between the cam groove 7a and the first and second outer rings 6b-1 and 6b-2 may be ensured. The thickness in the direction must be increased, and the outer diameter of the lens barrel increases.
Therefore, in the present embodiment, the outer ring restricting portions 4a and 5a are provided, and the first and second outer rings 6b are regulated by restricting the shake in the rotation axis direction of the first and second outer rings 6b-1 and 6b-2. The load on the bearings -1 and 6b-2 is restricted, and wear of the bearing balls can be reduced. At the same time, the first and second outer rings 6b-1 and 6b-2 can be prevented from coming off due to repeated operations. Therefore, durability can be secured at a high level.
[0022]
Further, since the outer ring restricting portions 4a and 5a are provided so as to ensure the distances A1 and A2, when the first and second outer rings 6b-1 and 6b-2 are operating normally, the first In addition, since the second bearings 6-1 and 6-2 are not affected at all, the first and second moving frames 2 and 3 can perform a smooth operation.
[0023]
According to the present embodiment, the cam groove 7a and the first and second bearings 6-1 and 6-2 are firmly in contact with each other by the pressure member 8, so that no play occurs and the optical axis of the rear lens group L2 is not generated. The position in the M direction is stabilized and the operation is 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 wear resistance is also improved, and the outer ring does not fall off due to the applied pressure, and the durability is improved. Can be increased.
[0024]
(Deformation)
The present invention is not limited to the embodiment described above, and various modifications and changes are possible, and these are also within the equivalent scope of the present invention.
For example, in the present embodiment, the example in which the outer ring restricting portions 4a and 5a are provided on both sides of the first and second outer rings 6b-1 and 6b-2 is shown, but only the outer ring restricting portion 4a may be provided, or the outer ring restricting portions 4a and 5a may be provided. Only part 5a may be sufficient.
[0025]
In the present embodiment, the case where the lens related to the 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 related to zoom.
[0026]
Furthermore, 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, and any lens barrel can be used as long as it is a cam follower portion of a moving member driven by a cam groove. It may be.
[0027]
Furthermore, the moving frame is not limited to the moving frame that directly moves the lens, and may be a moving frame that moves something by using the relative movement between the cam and the bearing so as not to cause backlash.
[0028]
【The invention's effect】
As described above in detail, according to the first aspect of the present invention, the photographing optical system, a moving frame provided with a part of the photographing optical system, movable at least in the optical axis direction of the photographing optical system, and the cam A cam frame having a groove, a bearing in which an outer ring that rotates relative to an inner ring engages with the cam groove, a support part that is provided in the moving frame and supports the inner ring, and the support part. A fixing part for fixing the inner ring so as to sandwich the inner ring, and at least a part of the fixing part is opposed to the outer ring in a direction along the rotation axis of the outer ring, and is provided at a distance from the outer ring. Since the displacement in the direction along the rotation axis of the outer ring is restricted , the movement of the lens group is smooth and the durability can be increased. A first bearing that engages with at least one side surface of the cam groove; a biasing member that biases the first bearing against the side surface of the cam groove; and an outer ring regulation that regulates displacement of the outer ring in the direction along the rotation axis. The lens unit moves smoothly, the focus position is stable, and durability can be increased.
[Brief description of the drawings]
FIG. 1 is a cross-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 diagram assuming a case where outer ring restricting portions 4a and 5a are not provided in a lens barrel having the same form as that of the present embodiment.
FIG. 4 is a cross-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 1st moving frame 3 2nd moving frame 4-1, 4-2 1st and 2nd rectilinear guide pin 5-1, 5-2 1st and 2nd Two bearing fixed shafts 6-1 and 6-2 First and second bearings 7 Cam member 8 Pressure member

Claims (4)

Photographic optics,
A part of the photographing optical system is provided, and a moving frame that is movable at least in the optical axis direction of the photographing optical system;
A cam frame having a cam groove;
A bearing in which an outer ring rotating relative to an inner ring engages with the cam groove;
A support portion provided in the moving frame and supporting the inner ring;
A fixing part for fixing the inner ring so as to sandwich the inner ring between the support part and
At least a portion of the fixed portion is opposed to the outer ring in a direction along the rotation axis of the outer ring, provided at a distance from the outer ring , and restricts displacement in the direction along the rotation axis of the outer ring ; and ,
At least a part of the support portion is opposed to an outer diameter side edge portion of the outer ring in a direction along the rotation axis, and is provided at a distance from an outer diameter side edge portion of the outer ring. Regulating the displacement in the direction along the rotation axis,
A lens barrel characterized by The lens barrel according to claim 1,
In the direction along the rotation axis, the amount of engagement between the cam groove and the outer ring is not more than half of the length of the outer ring in the direction along the rotation axis,
A lens barrel characterized by In the lens barrel according to claim 1 or 2,
The bearing includes a first bearing and a second bearing;
The first bearing is biased by a biasing member so as to engage with one side surface of the cam groove,
The second bearing is biased by the biasing member so as to engage with a side surface of the cam groove opposite to the one side surface;
A lens barrel characterized by A lens barrel according to any one of claims 1 to 3 , wherein
The support portion is a guide pin that is implanted in the moving frame and engages with a straight groove;
A lens barrel characterized by

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