JP4788025B2 - Lens barrel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens barrel with improved strength of a fixed barrel.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, parts used for lens barrels have been made into mold plastics. Particularly, in recent years, interchangeable lenses for interchangeable lens cameras have also been made into mold plastics. In such a molded plastic lens barrel, in order to reduce the number of parts, it may be used that a structure different from that of a conventional metal barrel can be configured. One example will be described with reference to a lens barrel shown in FIG.
[0003]
FIG. 4 is a cross-sectional view of a conventional lens barrel. The lens barrel includes a first lens group 31, a rotating member 32, an encoder brush 33, a restricting member 34, a fixed cylinder 35, a cam cylinder 36, a screw 37, a columnar portion 38, a zoom ring 39, a coupling gear 40, and a second lens group. 41, a straight guide key 42, and the like.
[0004]
The first lens group 31 is a focus lens that focuses by moving in the optical axis direction. The first lens group 31 is connected to the rotating member 32 via the helicoid portion 31a, and the rotational force is rotated by the rotation of the rotating member 32 or the user's manual operation. Obtains driving force and moves in the optical axis direction while rotating.
Further, the first lens group 31 moves together with the second lens group 41 even when the focal length is changed (hereinafter referred to as zooming).
[0005]
The rotating member 32 is a member that rotates by obtaining a rotational driving force from the coupling gear 40, and transmits the rotational driving force to the first lens group 31 by the linear key 32 a.
[0006]
The encoder brush 33 is a contact attached to the rotating member 32 and plays a role of reading an encoder pattern (not shown).
[0007]
The restricting member 34 is a member attached to the rotating member 32, and restricts the rotation of the rotating member 32 during focusing by being applied to the fixed cylinder 35.
[0008]
The fixed cylinder 35 is a fixed member that serves as a base of the lens barrel.
[0009]
The cam cylinder 36 is a member having a cam for driving the second lens group 41, is provided rotatably around the optical axis, and has an arm portion 36a on the outside.
[0010]
The zoom ring 39 is a member that is operated by the user during zooming, is provided so as to be rotatable about the optical axis, and has an arm portion 39a on the inner side.
The screw 37 is a screw that connects the arm portion 36a and the arm portion 39a.
[0011]
The columnar portion 38 is a portion to which the arm portion 36 a and the arm portion 39 a are connected, and the rotational force of the zoom ring 39 is transmitted to the cam cylinder 36 by the columnar portion 38.
In general, two or more columnar portions 38 are formed.
[0012]
The coupling gear 40 is a member that transmits a rotational driving force for autofocus from a camera body (not shown).
[0013]
The second lens group 41 is a lens group that moves during zooming. The second lens group 41 is cam-fitted with the cam barrel 36 and is guided by a straight guide key 42.
[0014]
The rectilinear guide key 42 is fixed to the fixed cylinder 35 and guides the second lens group 41 so as not to rotate.
[0015]
[Problems to be solved by the invention]
FIG. 5 is a development view of a fixed cylinder 35 used in a conventional lens barrel. As shown in FIG. 5, in the conventional lens barrel, it is necessary to cut out the fixed cylinder 35 and provide a cutout portion A that is a relief of the movable range of the columnar portion 38 in the range in which the columnar portion 38 rotates. is there.
Further, in the conventional lens barrel, since the columnar portion 38 is assembled to the reference position, the fixed barrel 35 also requires a notch B from the objective direction to the assembling position in the direction parallel to the optical axis.
Therefore, the fixed cylinder 35 requires a wide range of notches, and there is a problem that the strength is lowered.
[0016]
Further, the rotating member 32 is positioned in front of the columnar portion 38 (object side) because of the interlocking relationship with the first lens group 31, and thus is placed on the cantilever portion as shown in the portion 35a of FIG. There was a problem that it was necessary and structurally weak.
[0017]
Furthermore, the restricting member 34 is applied to the cantilever portion 35b, and there is a problem in strength as the position restriction.
[0018]
An object of the present invention is to provide a lens barrel having an excellent balance of strength without greatly changing the form of a conventional lens barrel.
[0019]
[Means for Solving the Problems]
The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this. That is, the invention of claim 1 is an imaging optical system (3, 9), an operating ring (7) that can be rotated to operate the imaging optical system, and can rotate according to the rotation of the operating ring. Rotating cylinder (8), optical axis direction cutouts (2b-1, 2c-1) provided on the imaging plane side of the imaging optical system and provided parallel to the optical axis direction, and the optical axis direction A fixed cylinder (2) having a circumferential cutout (2b-2, 2c-2) provided in a direction perpendicular to the cutout, the optical axis cutout and the circumferential cutout A columnar part (15) that has a shape that can be inserted into the notch, and that connects the operating ring and the rotary cylinder, and is fixed to the fixed cylinder from the inside of the fixed cylinder on the imaging plane side of the fixed cylinder. Rutotomoni mount portion for detachably coupling said fixed barrel to the camera body (6), the image plane of the fixed cylinder A lens barrel, characterized in that it comprises the outer from outer barrel which is fixed to the fixed tube of the fixed cylinder (18), provided.
[0020]
According to a second aspect of the present invention, in the lens barrel according to the first aspect, the notch (2b-1, 2c-1) in the optical axis direction is not less than ½ of the total length of the fixed tube (2). It is a lens barrel characterized by having a length .
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view of a first embodiment of a lens barrel according to the present invention.
The lens barrel includes a fixed cylinder 2, a first lens group 3, a female helicoid cylinder 4, a male helicoid cylinder 5, a bayonet mount 6, a zoom ring 7, a cam cylinder 8, a second lens group 9, a lens chamber 10, and an idling gear 11. , Key 12, segment gear 13, columnar portion 15, screw 16, coupling gear 17, external cylinder 18 and the like.
[0027]
The fixed cylinder 2 is a fixed member that does not move during use and serves as the base of the lens barrel.
FIG. 2 is a perspective view of the fixed cylinder 2. As shown in FIG. 2, the fixed cylinder 2 is provided with notches 2b, 2c, and 2d having a deep cut depth from the image plane side. The notches 2b and 2c have optical axis direction notches 2b-1 and 2c-1, and circumferential notches 2b-2 and 2c-2, respectively. The notches 2b-1 and 2c-1 in the optical axis direction are escapes for incorporating a columnar part 15 to be described later into the fixed cylinder 2, and have a length that is ½ or more of the total length of the fixed cylinder 2. The circumferential notches 2b-2 and 2c-2 are escapes when the columnar portion 15 moves during zooming. The notch 2d is a relief for assembling the idling gear 11, the segment gear 13, the coupling gear 17 and the like.
Further, the fixed cylinder 2 has a rectilinear guide groove 2a that restricts the rotation of the male helicoid cylinder 5 and makes the movable direction of the male helicoid cylinder 5 only the rectilinear direction.
[0028]
The first lens group 3 is a focus lens that focuses by moving in the optical axis direction, and is fixed integrally to the female helicoid cylinder 4. The first lens group 3 is connected to the segment gear 13 via the female helicoid cylinder 4, and obtains a rotational force driving force by rotation of the segment gear 13 or manually by the user, and rotates by the action of the helicoid while rotating the optical axis. Move in the direction.
Further, the first lens group 3 performs only a straight movement together with the second lens group 9 without rotating during zooming.
[0029]
The female helicoid cylinder 4 is a member to which the first lens group 3 is fixed integrally. The female helicoid cylinder 4 is screwed into the male helicoid cylinder 5 with a helicoid 4b provided on the inner side, and the guide portion 4a is guided by the straight key portion 13a of the segment gear 13. The female helicoid cylinder 4 also serves as a distance ring. During manual focusing, the user rotates the female helicoid cylinder 4 so that the first lens group 3 moves in the front-rear direction while rotating, and is focused. Can be made. During autofocus, the female helicoid cylinder 4 is driven by obtaining rotational force from the segment gear 13.
[0030]
The male helicoid cylinder 5 is a member in which the guide portion 5a is guided in the rectilinear guide groove 2a of the fixed cylinder 2, and the movable direction is restricted only in the rectilinear direction. The male helicoid cylinder 5 has a cam follower 5 b combined with the cam portion 8 b of the cam cylinder 8, and moves in the straight direction by the rotation of the cam cylinder 8. The male helicoid cylinder 5 is provided with a helicoid 5c outside the vicinity of the tip on the objective side, and the female helicoid cylinder 4 is screw-fitted.
[0031]
The bayonet mount 6 is a coupling member that detachably couples the lens barrel to a camera body mount (not shown). The fitting portion 6 a is fitted and fixed on the inner diameter side of the fixed cylinder 2. It also plays a role of reinforcing means to reinforce.
[0032]
The zoom ring 7 is an operation member that is operated by a user during zooming, is supported by the fixed cylinder 2, is attached to be rotatable about the optical axis, and has an arm portion 7a on the inner side.
[0033]
The cam cylinder 8 is a cam member having a cam groove 8 a on the inner diameter side and a cam portion 8 b on the outer diameter side, and the arm portion 8 c is coupled to the arm portion 7 a with a screw 16 so that the light is integrated with the zoom ring 7. It can rotate around its axis.
[0034]
The second lens group 9 is a lens group that moves in the straight direction during zooming, and is held in the lens chamber 10. The first lens group 3 and the second lens group 9 form an imaging optical system of the lens barrel of this embodiment.
[0035]
The lens chamber 10 is a lens frame member that holds the second lens group 9, and a groove 10 a provided on the outer diameter side is slidably combined with the cam groove 8 a and is prevented from rotating by the key 12. Then, the cam cylinder 8 is moved back and forth by the rotation of the cam cylinder 8.
[0036]
The idling gear 11 is an idling gear that transmits the rotation of the coupling gear 17 to the segment gear 13.
[0037]
The key 12 is a member that regulates the rotation of the lens chamber 10 and guides the movement in the straight direction.
[0038]
The segment gear 13 is a member that is supported in the vicinity of the distal end of the fixed cylinder 2 on the objective side, meshes with the idling gear 11, and is provided so as to be rotatable around the optical axis. The segment gear 13 includes a rectilinear key portion 13a, and the guide portion 4a of the female helicoid cylinder 4 is slidably fitted to the rectilinear key portion 13a.
In the vicinity of the tip of the fixed cylinder 2 on which the segment gear 13 is supported, there is no large notch as in the prior art. Therefore, the fixed cylinder 2 can secure sufficient strength against the force received by the fixed cylinder 2 when the segment gear 13 rotates, and can stably support the segment gear 13.
[0039]
The columnar portion 15 is a coupling portion in which the arm portion 7 a of the zoom ring 7 and the arm portion 8 c of the rotating cylinder 8 are coupled by screws 16. In the present embodiment, two coupling portions are provided. The zoom ring 7 and the columnar part 15 form a main part of a drive mechanism that drives the first lens group 3 and the second lens group 9 during zooming.
[0040]
The screw 16 is a screw that connects the arm portion 7 a of the zoom ring 7 and the arm portion 8 c of the rotating cylinder 8. The zoom ring 7 and the rotating cylinder 8 using the screw 16 are coupled in a process before the assembling to the fixed cylinder 2, and at the time of assembling, the columnar portion 15 from the rear (image forming surface side) of the fixed cylinder 2. Is inserted through the notches 2b-1 and 2c-1 in the optical axis direction.
[0041]
The coupling gear 17 is a coupling gear that transmits a rotational driving force from the camera body during autofocus driving, and is engaged with the idling gear 11. The idling gear 11, the segment gear 13, and the coupling gear 17 form the main part of the drive mechanism that drives the first lens group 3 during autofocus.
[0042]
The external cylinder 18 is an external member that forms a part of the external appearance of the lens barrel, and the inner peripheral side is fitted and fixed to the outer diameter side of the fixed cylinder 2, and together with the bayonet mount 6, the fixed cylinder 2 is reinforced. It also serves as a reinforcing means.
[0043]
As described above, the fixed cylinder 2 is not provided with a notch (not opened) at the end on the objective side, but is provided with a notch on the image plane side. The strength of is not much different from the conventional example. However, the fixed cylinder 2 of the present embodiment is fixed by fitting the bayonet mount 6 on the inner diameter side. Further, an outer appearance cylinder 18 is fitted and fixed to the outer diameter side of the fixed cylinder 2. As described above, the fixed cylinder 2 is sandwiched between the bayonet mount 6 and the external cylinder 18 so that it can have a strength equal to or higher than that in the case where there is no notch.
[0044]
(Focus operation)
In the lens barrel of the present embodiment, the user can arbitrarily select manual focus (manual focus) and auto focus (auto focus). The operation of the lens barrel in each case will be described below.
During manual focusing, the user directly rotates the female helicoid cylinder 4 that also serves as a distance ring. At this time, since the cam cylinder 8 does not rotate, the male helicoid cylinder 5 does not move in the front-rear direction, and since the rotation is restricted by the rectilinear guide groove 2a of the fixed cylinder 2, it cannot be rotated. Therefore, the male helicoid 5 is fixed, and the female helicoid 4 moves in the front-rear direction while being rotated by the helicoid screw. Since the first lens group 3 is integrally attached to the female helicoid 4, the first lens group 3 can also move in the front-rear direction while rotating, and the focus can be adjusted.
[0045]
Since the female helicoid 4 is guided by the straight key part 13a of the segment gear 13 via the guide part 4a, the segment gear 13 also rotates at the same time. During manual focus, the segment gear 13, the idling gear 11, and the coupling gear 17 can freely rotate because the clutch body (not shown) on the camera body side is disconnected from the driving source for autofocus driving. it can.
[0046]
During autofocus, the coupling gear 17 rotates by obtaining a driving force from the camera body side, and the female helicoid 4 rotates through the idling gear 11, and the focusing operation is performed in the same manner as during manual focusing. Is called.
[0047]
(zooming)
Next, zooming will be described. The lens barrel shown in this embodiment can be zoomed only manually. When the user manually rotates the zoom ring 7, the cam cylinder 8 connected by the columnar portion 15 also rotates.
The male helicoid 5 is cam-fitted with the cam cylinder 8 by a cam follower 5b, and the guide portion 5a is regulated by the fixed cylinder 2 so as not to rotate. Therefore, the male helicoid 5 moves straight without rotating by the rotation of the cam cylinder 8. As the male helicoid 5 moves, the first lens group 3 and the female helicoid 4 also move straight.
In the lens chamber 10, the groove 10 a provided on the outer diameter side is slidably combined with the cam groove 8 a, and the rotation is stopped by the key 12. Therefore, the second lens group 9 also moves straight along with the lens chamber 10.
[0048]
According to this embodiment, since the part holding the segment gear 13 of the fixed cylinder 2 can be made into a substantially connected cylindrical shape, the segment gear 13 can be held stably.
Moreover, the fixed cylinder 2 can be equal to or stronger than the case where there is no notch by being sandwiched between the bayonet mount 6 and the external cylinder 18.
[0049]
(Second Embodiment)
FIG. 3 is a diagram showing a second embodiment of the present invention.
Since the second embodiment has the same configuration except that the reinforcing rings 51 and 52 are added to the lens barrel of the first embodiment, description of overlapping parts is omitted.
[0050]
The reinforcing ring 51 is a reinforcing means fitted to the inner diameter of the fixed cylinder 2 and is a metal ring-shaped member. Since the reinforcing ring 51 has a C shape with a part cut away, the zoom ring 7 and the cam cylinder 8 can be assembled to the fixed cylinder 2 and then assembled to the fixed cylinder 2. The fixed cylinder 2 has notches 2b, 2c, and 2d, and has a disadvantageous shape in terms of strength. Therefore, by adding a reinforcing ring 51 made of a material different from that of the fixed cylinder 2, the first The strength can be further increased as compared with the embodiment. The reinforcing ring 51 is effective when the strength higher than that of the first embodiment is required, or when the fixed cylinder 2 cannot be reinforced by the bayonet mount 6, the external cylinder 18, or the like. The reinforcing ring 51 is assembled as a C-shape. However, in order to further increase the strength, the reinforcing ring 51 may be provided at the image plane end of the fixed cylinder 2 as a ring shape with the entire circumference connected.
[0051]
The reinforcing ring 52 is a reinforcing means provided on the inner diameter side of the bayonet mount 6 and is a metal ring-shaped member. The reinforcing ring 52 is particularly effective when the fixed cylinder 2 and the bayonet mount 6 are reinforced when the bayonet mount 6 is formed of resin.
[0052]
According to this embodiment, since the reinforcing rings 51 and 52 are provided, the strength of the lens barrel can be further improved.
[0053]
(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.
In each embodiment, the lens barrel example of the two-group configuration has been described. However, the present invention is not limited to this. For example, a three-group configuration or a four-group configuration may be used. However, the present invention is not limited to this example.
[0054]
In the second embodiment, an example in which both the reinforcing ring 51 and the reinforcing ring 52 are provided has been described. However, the present invention is not limited to this. For example, only the reinforcing ring 51 may be provided, or only the reinforcing ring 52 is provided. May be.
[0055]
Furthermore, in each embodiment, the example using the bayonet mount 6, the external cylinder 18, the reinforcing rings 51, 52, and the like as the reinforcing means has been shown. However, the present invention is not limited thereto. A member for attaching the lens barrel (for example, a camera body) may be used as the reinforcing means.
[0056]
【The invention's effect】
As described above in detail, according to the first aspect of the present invention, the fixed cylinder is mounted on the inside of the fixed cylinder on the imaging plane side of the fixed cylinder in which the notch in the optical axis direction is open. And an external cylinder fixed to the outside of the fixed cylinder. The optical axis direction cutout portion of the fixed cylinder prevents the optical axis direction cutout portion of the fixed cylinder from being deformed inward (direction toward the optical axis) in a direction orthogonal to the optical axis. Further, since the external cylinder is fixed to the fixed cylinder from the outside of the fixed cylinder, the notch portion of the fixed cylinder in the direction orthogonal to the optical axis is deformed outward (in a direction away from the optical axis). To prevent. According to this, it is possible to reliably suppress a decrease in rigidity of the fixed cylinder having the notch in the optical axis direction. Therefore, a lens barrel having an excellent balance of strength can be obtained without greatly changing the form of the conventional lens barrel .
[0057]
According to the second aspect of the present invention, since the cut-out portion has a length that is ½ or more of the total length of the fixed cylinder, sufficient strength can be obtained by the reinforcing means even in the case of fixing or the like that inherently decreases the strength. Can be secured.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a first embodiment of a lens barrel according to the present invention.
FIG. 2 is a perspective view of a fixed cylinder 2. FIG.
FIG. 3 is a diagram showing a second embodiment of the present invention.
FIG. 4 is a cross-sectional view of a conventional lens barrel.
FIG. 5 is a development view of a fixed cylinder 35 used in a conventional lens barrel.
[Explanation of symbols]
2 Fixed cylinder 3 First lens group 4 Female helicoid cylinder 5 Male helicoid cylinder 6 Bayonet mount 6
7 Zoom ring 8 Cam cylinder 9 Second lens group 10 Lens chamber 11 Idling gear 12 Key 13 Segment gear 15 Column 16 Screw 17 Coupling gear 18 External cylinder 18
51,52 Reinforcement ring

Claims (2)

An imaging optical system;
An operating ring rotatable to operate the imaging optical system;
A rotating cylinder rotatable according to the rotation of the operation ring;
An optical axis direction notch portion that opens to the image plane of the imaging optical system and is provided in parallel to the optical axis direction, and a circumferential direction cut direction that is orthogonal to the optical axis direction notch portion. A fixed cylinder having a notch;
A columnar part that has a shape that can be inserted into the notch part in the optical axis direction and the notch part in the circumferential direction, and that connects the operation ring and the rotary cylinder,
A mount portion that is fixed to the fixed cylinder from the inside of the fixed cylinder on the imaging plane side of the fixed cylinder, and that detachably couples the fixed cylinder to the camera body ;
An external appearance cylinder that is provided on the imaging surface side of the fixed cylinder and is fixed to the fixed cylinder from the outside of the fixed cylinder;
A lens barrel. The lens barrel according to claim 1,
The lens barrel according to claim 1, wherein the notch in the optical axis direction has a length equal to or more than ½ of the total length of the fixed barrel.

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