JPH08248461A - Lens barrel - Google Patents

Abstract

PURPOSE: To prevent the decrease of the strength of a part by forming a spiral groove as the structure of restraining the rotation of a front barrel so as not to be formed through a straightly advancing cam barrel, etc., in a lens barrel provided with a three-stage moving barrel. CONSTITUTION: The straightly advancing cam barrel 7 attached to a straightly advancing key 3 provided on a fixed barrel 5 to be movable in an optical axial direction in the restrained state of the rotation is disposed inside a rear barrel 6, a rotary barrel 8 which is integrally rotated with the rear barrel 6 are moved in the optical axial direction is disposed inside the straightly advancing cam barrel 7 and an intermediate barrel 10 is rotated and moved in the optical axial direction in such a manner that a cam pin 10a provided on the intermediate barrel 10 inside the rotary barrel 8 is engaged with and inserted through a key groove 8b extended in the optical axial direction of the rotary barrel 8 and a top end part of the pin 10a is engaged with a recessed spiral cam groove 7a on the inner periphery of the straightly advancing barrel 7. Then, the front barrel 11 is arranged inside the intermediate barrel 10 so as to move in the optical axial direction in accordance with the rotation of the intermediate barrel 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is applicable to a zooming operation or the like.
The present invention relates to a lens barrel in which a movable barrel divided into a plurality of stages or more expands and contracts.

[0002]

2. Description of the Related Art Conventionally, in order to extend and move a front lens group in accordance with a zooming operation or the like, a structure in which a lens barrel is divided into two stages to perform expansion / contraction operation is generally adopted, but the expansion / contraction amount is further increased. There is known a lens barrel in which the lens barrel is divided into three stages or more so that the lens barrel can be expanded and contracted in order to achieve compactness when retracted and stored.

As an example of the structure of the three-stage telescopic lens barrel, the structure shown in FIGS. 5 to 7 has been implemented. That is, the camera body 2 installed inside the camera body 1
A fixed barrel 105 is fixed to the fixed barrel 105, and a movable barrel consisting of a split barrel including a rear barrel 106, an intermediate barrel 110 and a front barrel 111 is arranged on the fixed barrel 105 so as to be capable of expanding and contracting. Then, the front lens group 15 is held in the front barrel 111 and the shutter unit 14 is installed, and the front barrel 111 moves in the optical axis direction together with the front barrel 111. A flexible substrate 17 is connected to the shutter unit 14 for its drive control,
It is connected to the control unit on the camera body 1 side.

On the other hand, the expansion and contraction movement of the moving barrel is driven by the rotation driving force of the motor being transmitted through the cam mechanism or the screw mechanism, and any one of the moving barrels rotates. When the front cylinder 111 rotates, the flexible substrate 17 is twisted, which is not preferable. Therefore, the front cylinder 111 is provided so as to simply move back and forth in the optical axis direction without rotating.

More specifically, the fixed barrel 105 is fixed to the camera body 1 without moving back and forth and rotating, and a helicoid screw is provided on the inner peripheral surface thereof and a vertical groove is formed in the vertical groove. The protrusion of the ring-shaped straight advance key 103 is fitted and can be moved in the optical axis direction while the rotation is restricted. The straight-moving key 103 is fixed to the end of the straight-moving cam cylinder 107 by means of a screw, and is transmitted to a motor (not shown) via a reduction gear system to be rotationally driven.
The transmission gear 104 meshes with the gear 106b on the outer periphery of the rear end of the rear cylinder 106 to rotate and drive. The rear barrel 106 is disposed between the fixed barrel 105 and the straight-moving cam barrel 107, and the helicoid screw on the outer periphery meshes with the helicoid screw on the inner periphery of the fixed barrel 105, so that the rotation of the rear barrel 106 causes the optical axis direction. Move back and forth.

On the other hand, as described above, since the front cylinder 111 moves back and forth without rotating, the helicoid screw provided on the outer circumference of the front cylinder 111 is screwed into the inner circumference helicoid screw of the intermediate cylinder 110,
It is provided so as to move back and forth according to the rotation of the intermediate cylinder 110. Therefore, the intermediate cylinder 110 has a linkage structure that rotates integrally with the rear cylinder 106, and the cam pin 110a erected on the outer peripheral surface of the intermediate cylinder 110 is inserted into the key groove 106a provided on the inner surface of the rear cylinder 106 in the optical axis direction. Engage. Further, in order to move the intermediate cylinder 110 in the optical axis direction in accordance with the rotation, the cam pin 110a is formed in the spiral cam groove 107a of the straight-moving cam cylinder 107 (FIG. 7 shows a shape with a large rotation angle). Engaged.

Further, as a structure for restraining the rotation of the front barrel 111 in order to move the front barrel 111 only in the optical axis direction,
The locking piece 113a provided at the rear end of the straight-moving cylinder 113 locked inside the 111 is fitted to the inner peripheral keyway 10 of the straight-moving cam cylinder 107.
It is engaged with 7b.

Further, a cam pin 112a is also provided on the outer periphery of the lens frame 112 of the rear lens group 16, and the cam pin 112a penetrates the longitudinal groove 113b of the straight-moving barrel 113 to form a spiral cam groove on the inner peripheral surface of the intermediate barrel 110. It is provided so as to be engaged with 110b and rotationally restrained by the straight-moving barrel 113, and to move along the locus of the cam groove 110b in the optical axis direction in accordance with the rotation of the intermediate barrel 110.

With the above structure, the transmission gear 104
In the expansion and contraction operation of the lens barrel associated with the driving of, the rear barrel 106 and the intermediate barrel 110 rotate, but the front barrel 111 does not rotate.

[0010]

However, in the lens barrel having the movable barrel divided into three or more portions as described above, the rotation drive angle cannot be set large, and the operability and the like are taken into consideration. The problem arises.

That is, from the viewpoint of positional accuracy and operational stability, a cam pin that is usually provided on the outer periphery of the intermediate cylinder 110 so as to project.
Three 110a are provided at equal intervals, and three cam grooves 107a on the circumferential surface of the straight-moving cam cylinder 107 are formed correspondingly therethrough. Therefore, when the rotation angle of the intermediate cylinder 110 is large, Figure 7
As illustrated in FIG.
7a is formed. As a result, the straight-moving cam barrel 107 becomes a component having a weak strength in the optical axis direction, is deformed when a rotational driving force is applied, and the feed accuracy of the cam pin 110a is lowered, and the stop position accuracy of the lens is deteriorated. Further, difficulties in manufacturing the straight cam tube 107 can be expected. In order to avoid these adverse effects, the rotation angle of the intermediate cylinder 110 or the like is restricted to, for example, about 100 ° so that the spiral cam groove 107a does not become long. There is an upper limit, and the total amount of expansion and contraction is limited, so that the desired characteristics cannot be obtained.

Therefore, the present invention has been made in view of such circumstances, and an object thereof is to provide a lens barrel capable of setting a large rotation angle without forming a spiral cam groove penetrating therethrough. It is a thing.

[0013]

A lens barrel according to the present invention that achieves the above object has a rear barrel, an intermediate barrel, and a front barrel which are separately movable with respect to a fixed barrel. When the front barrel holding the front lens group is arranged to move in the optical axis direction while the rotation is constrained in accordance with the rotational drive of, the fixed barrel is moved in the optical axis direction while the rotation is constrained. A rectilinear key is provided as much as possible, and a rectilinear cam cylinder that is coupled to the rectilinear key and moves in the optical axis direction integrally with the rear cylinder in a state in which the rotation is restrained is provided inside the rear cylinder. A rotary barrel that rotates integrally with the rear barrel and moves in the optical axis direction is provided inside the barrel, and a concave spiral cam groove is formed on the inner peripheral surface of the straight-moving cam barrel and extends in the optical axis direction on the rotary barrel. An outer circumference of an intermediate cylinder that is formed through the key groove and is inserted inside the rotary cylinder. Is provided with a plurality of cam pins projecting in the radial direction, the cam pins engage and penetrate the key groove of the rotary cylinder, and the ends thereof engage with the cam grooves of the straight-moving cam cylinder to rotate the intermediate cylinder. It is characterized in that it is provided so as to move in the optical axis direction, and a front cylinder is provided inside the intermediate cylinder so as to move in the optical axis direction in response to the rotation of the intermediate cylinder.

Specifically, a helicoid screw provided on the outer circumference of the front barrel is engaged with a helicoid screw provided on the inner circumferential surface of the intermediate barrel, and is linked to a key portion extending in the optical axis direction of the straight advance key. The rotation of the intermediate cylinder is restricted so that the intermediate cylinder can move in the optical axis direction with respect to the rotation of the intermediate cylinder.

Further, inside the intermediate cylinder, there is disposed a straight-moving cylinder which moves in the optical axis direction integrally with the intermediate cylinder while being engaged with the key portion of the straight-moving key and restrained in rotation. It is preferable that the outer peripheral key portion of the straight advance cylinder and the key portion of the inner peripheral surface of the front cylinder are engaged with each other to restrain the rotation of the front cylinder.

Further, a spiral cam groove is provided on the inner peripheral surface of the intermediate barrel, a key groove extending in the optical axis direction is provided on the rectilinear barrel, and a cam pin extending radially is provided on a lens frame holding the rear group lens. The cam pin may be provided so as to be engaged with the key groove of the straight-moving barrel, and the tip end thereof may be engaged with the spiral cam groove of the intermediate barrel so as to move the lens frame in the optical axis direction in a state in which the rotation is restricted. .

[0017]

According to the above construction, the intermediate barrel and the rotary barrel rotate in response to the rotational drive of the rear barrel, but the straight cam barrel, the straight barrel and the front barrel are restrained from rotating and move in the optical axis direction.
Then, the cam pin that restricts the movement of the intermediate cylinder in the optical axis direction penetrates the key groove extending in the optical axis direction of the rotating cylinder, engages with the spiral cam groove formed on the inner peripheral surface of the straight-moving cam cylinder, and rotates. The cam pin is rotated by the barrel and moves in the cam groove to move in the optical axis direction, and the front barrel is rotated by the rotation and the optical axis movement of the intermediate barrel and in association with the straight-ahead key. Without further movement, the flexible substrate can be expanded and contracted without causing twisting or the like in the flexible substrate.

Further, in the linking of the intermediate cylinder and the rear cylinder, the straight cam cylinder and the rotary cylinder interposed between them are:
Since the spiral cam groove that penetrates the inner and outer circumferences is not formed, there is no part whose strength is greatly reduced even if the rotation angle increases and the length of the cam groove increases. This rotation angle corresponds to the desired characteristics. It can be set to a value.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic vertical cross-sectional view of a camera including a lens barrel according to an embodiment of the present invention in a lens housed state, FIG. 2 is a cross-sectional view showing a telephoto end state, and FIG. 3 is an exploded perspective view of a lens barrel part.

The lens barrel includes a fixed barrel 5 fixed to the camera body 1, a rear barrel 6 that extends and contracts in the optical axis direction, and an intermediate barrel.
10 and a movable barrel including a front barrel 11 and a split lens barrel. The front lens group 15 is held in the front barrel 11 and the shutter unit 14 is installed, and the front barrel 11 moves in the optical axis direction together with the front barrel 11. Although not shown, a flexible substrate 17 is connected to the shutter unit 14 for drive control thereof, which is not shown, and is connected to a control unit on the camera body 1 side.

The fixed barrel 5 is fixed to the camera body 2 without moving back and forth and rotating, and has a helicoid screw 5b on its inner peripheral surface and a key groove 5a extending in the optical axis direction. Inside the fixed cylinder 5, a helicoid screw 5b on the inner circumference of the fixed cylinder 5 is screwed into a helicoid screw 6c on the outer circumference of the rear cylinder 6 so that the rear cylinder 6 moves in the optical axis direction as it rotates. Thus, the rectilinear cam cylinder 7 is inserted inside the rear cylinder 6.

At the rear end of the straight cam barrel 7, the rear barrel 6 is provided.
The ring-shaped rectilinear key 3 is fastened with a screw while rotatably sandwiching the inner protrusion 6b on the inner periphery of the rear end. The straight advance key 3 is provided with projections 3a at three locations on its outer peripheral portion, and engages with the key groove 5a of the fixed cylinder 5 to prevent rotation. This allows
The rectilinear key 3, the rear cylinder 6 and the rectilinear cam cylinder 7 move integrally in the optical axis direction, while the rectilinear key 3 and the rectilinear cam cylinder 7 are restrained from rotating and only the rear cylinder 6 rotates. Has been. A curved plate-shaped key portion 3b extending in the optical axis direction is connected at three locations on the inner circumference of the straight-ahead key 3.

A transmission gear 4 is provided on the straight-moving key 3 and is rotationally driven by a motor (not shown) through a reduction gear system. The transmission gear 4 is meshed with a gear 6d on the outer periphery of the rear end of the rear cylinder 6, and the transmission gear 4 is driven to rotate normally or reversely.
The rear barrel 6 moves in the optical axis direction while rotating by itself. The straight-moving key 3 moves in the axial direction together with the rear cylinder 6, but the transmission gear 4 part thereof moves in the vertical groove 5c of the fixed cylinder 5.

Further, a rotary cylinder 8 is inserted inside the straight-moving cam cylinder 7, and a protrusion 8a protruding on the outer periphery of the front end of the rotary cylinder 8 is provided on the inner periphery of the front end of the rear cylinder 6. The rotary cylinder 8 is engaged with the fitting protrusion 6a and rotates and moves back and forth integrally with the rear cylinder 6. A front frame 9 is fixed to the front end of the rear cylinder 6, and the front end of the rotary cylinder 8 is fixed and integrated. This rotary cylinder 8 has key grooves extending in the optical axis direction at three locations on the peripheral surface.
While 8b is formed so as to penetrate from the outer circumference to the inner circumference, a spiral cam groove 7a is formed on the inner circumferential surface of the straight-moving cam barrel 7 without penetrating in a three-row concave shape.

An intermediate cylinder 10 is inserted inside the rotary cylinder 8, and cam pins 10a extending in a direction perpendicular to the optical axis are provided at three locations on the outer periphery of the rear part of the intermediate cylinder 10 so as to project therefrom.
Engages with and penetrates the key groove 8b of the rotary cylinder 8, and further engages with the cam groove 7a provided on the inner circumference of the outermost linear cam cylinder 7. By the engagement of this cam pin 10a,
The intermediate cylinder 10 is rotated by the rotation of the rotary cylinder 8, and is moved in the optical axis direction along the cam groove 7a of the rectilinear cam cylinder 7 according to the rotation.

A helicoid screw is provided on the inner peripheral surface of the intermediate cylinder 10.
10c and the spiral concave cam groove 10d are arranged in parallel. The straight-moving cylinder 13 is inserted from the rear side inside the intermediate cylinder 10,
The key portion 3b of the straight-moving key 3 is engaged with a concave key groove 13a provided on the inner peripheral portion of the key portion 13b and is restrained in the rotational direction. Also, the rear end flange portion of this straight-moving cylinder 13 is an intermediate cylinder.
The engaging portion 10b is provided so as to be rotatable with respect to the engaging portion 10b so as to be restrained in the optical axis direction. As a result, the rectilinear barrel 13 does not rotate and moves integrally with the intermediate barrel 10 in the optical axis direction.
Incidentally, the straight-moving barrel 13 is formed with three key grooves 13c extending through it in the optical axis direction.

The front cylinder 11 is located on the inner circumference of the intermediate cylinder 10.
The front cylinder 11 has a helicoid screw 11b provided on the outer circumference thereof engaged with a helicoid screw 10c provided on the inner circumference of the intermediate cylinder 10. , A concave key groove 11a in the optical axis direction provided on the inner circumference of the front barrel 11 is a convex key portion 13b in the optical axis direction provided on the outer circumference of the straight-moving barrel 13 (outside the key groove 13a). Part). As a result, the front barrel 11 is movable in the optical axis direction, but its rotation is restricted, and the front barrel 11 moves in the optical axis direction by an amount corresponding to the inclination angle of the helicoid screw 10c with respect to the rotation of the intermediate barrel 10.

The lens frame 12 holding the rear lens group 16 includes
Cam pins 12a projecting in the radial direction are provided at three locations on the outer periphery of the lens frame 12, and the lens frame 12 is inserted into the straight advance barrel. The cam pin 12a engages with and penetrates the key groove 13c of the rectilinear cylinder 13, and the tip of the cam pin 12a engages with the spiral cam groove 10d provided on the inner circumference of the intermediate cylinder 10. This allows the lens frame 12
Is movable in the optical axis direction, but its rotation is restricted, and the intermediate cylinder 10 moves in the optical axis direction by an amount corresponding to the spiral angle of the cam groove 10d with respect to the rotation.

With the above-mentioned structure, the moving barrels of the rear barrel 6, the intermediate barrel 10 and the front barrel 11 of the lens barrel are moved backward and housed in the camera body 1 as shown in FIG. From the state to the extended state as shown in Fig. 2 (TELE end state)
In order to operate, the driving force is transmitted to the transmission gear 4 and the rear cylinder 6 is rotationally driven. With the rotation of the rear cylinder 6,
The rotary cylinder 8 and the intermediate cylinder 10 rotate similarly.

When the rear cylinder 6 rotates, the helicoid screw 5b,
The rear cylinder 6 is moved forward by 6c, and along with this, the straight cam cylinder 7 and the rotary cylinder 8 are similarly moved forward. Also, the intermediate tube
In addition to moving forward with the forward movement of the straight-moving cam cylinder 7, the rotation of the straight-moving cam cylinder 7 causes the cam pin 10a to move in the cam groove 7a of the straight-moving cam cylinder 7 to further move forward.

By the forward movement of the intermediate cylinder 10, the front cylinder 11,
In addition to the rectilinear barrel 13 and the lens frame 12 moving forward in the same way, the rotation of the intermediate barrel 10 causes the helicoid screw 11b of the front barrel 11 against the helicoid screw 10c and the cam groove 10d on the inner periphery thereof.
Also, the engagement position of the cam pin 12a of the lens frame 12 changes, and the front barrel 11, the rectilinear barrel 13 and the lens frame 12 further move forward without rotating.

In the structure described above, the cam groove 7a of the straight-moving cam barrel 7 for moving the intermediate barrel 10 in the optical axis direction is formed in a concave shape on the inner peripheral surface and not formed on the outer peripheral surface. , The rotation angle of the intermediate cylinder 10 is increased to increase the cam groove.
Even if 7a is formed long, the strength of the intermediate barrel 10 in the optical axis direction can be made high, and a zoom lens barrel having a large zoom ratio can be constructed.

[0033]

As described above, according to the present invention, since the spiral cam groove is not provided so as to penetrate the straight-moving cam barrel, it is possible to prevent the member strength from being lowered due to the formation of the cam groove. Meanwhile, it can be provided in a structure that moves in the optical axis direction while restraining the rotation of the front barrel that holds the front lens group, and it is possible to set the rotation angle to a large value and to lengthen the cam groove. It is possible to provide a characteristic expansion / contraction operation, and at the same time, it is possible to obtain a good stop position control characteristic.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing a lens housed state of a camera including a lens barrel according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the telephoto end state.

3 is a cross-sectional view of the lens barrel of FIG.

FIG. 4 is an exploded perspective view of the lens barrel of FIG.

FIG. 5 is a schematic vertical sectional view showing a lens housed state of a camera including a conventional lens barrel.

FIG. 6 is a sectional view showing the state at the telephoto end.

7 is an exploded perspective view of the lens barrel of FIG.

[Explanation of symbols]

 2 Camera body 3 Straight key 3b Key part 4 Transmission gear 5 Fixed cylinder 6 Rear cylinder 7 Straight cam cylinder 7a Cam groove 8 Rotating cylinder 8b Key groove 10 Intermediate cylinder 10a Cam pin 11 Front cylinder 12 Lens frame 12a Cam pin 13 Straight cylinder 14 Shutter Unit 15 front group lens

Claims (4)

[Claims] 1. A rear barrel, an intermediate barrel and a front barrel are separately movable with respect to a fixed barrel, and the front barrel holding a front lens group is rotated in response to rotational driving of the rear barrel. In the lens barrel provided so as to move in the optical axis direction in a state of being constrained, a straight-moving key is provided so as to be movable in the optical axis direction in a state in which rotation is restrained with respect to the fixed barrel, and inside the rear barrel. Is provided with a straight cam barrel which is coupled to the straight-running key and which rotates in the optical axis direction integrally with the rear barrel in a state where the rotation is restrained, and the rear barrel is provided inside the straight-running cam barrel. A rotary cylinder that rotates together with the rotary cylinder that moves in the optical axis direction is provided, a concave spiral cam groove is formed on the inner peripheral surface of the straight-moving cam cylinder, and a key groove that extends in the optical axis direction is formed through the rotary cylinder. The intermediate cylinder inserted inside the rotary cylinder projects radially in the outer peripheral surface. A plurality of cam pins are provided, the cam pins engage and penetrate the key groove of the rotary cylinder, and the tips are engaged with the cam grooves of the straight-moving cam cylinder, and the intermediate cylinder rotates and moves in the optical axis direction. A lens barrel, wherein a front barrel is provided inside the intermediate barrel so as to move in the optical axis direction in response to rotation of the intermediate barrel. 2. The front cylinder is provided so that a helicoid screw provided on an outer circumference thereof is engaged with a helicoid screw provided on an inner peripheral surface of the intermediate cylinder and extends in an optical axis direction of the straight advance key. The rotation is restricted by being linked to the key part
The lens barrel according to claim 1, wherein the lens barrel moves in the optical axis direction with respect to the rotation of the intermediate barrel. 3. A straight advancing cylinder that moves integrally with the intermediate cylinder in the optical axis direction in a state of being engaged with a key portion of the straight advancing key and restrained in rotation is disposed inside the intermediate cylinder. 3. The lens mirror according to claim 1, wherein the outer peripheral key portion of the straight-moving barrel and the key portion of the inner peripheral surface of the front barrel are engaged with each other to restrain the rotation of the front barrel. Cylinder. 4. A spiral cam groove is formed on the inner peripheral surface of the intermediate cylinder.
A key groove extending in the optical axis direction is provided on the rectilinear barrel, and a cam pin extending in the radial direction is provided on the lens frame holding the rear group lens. The cam pin is engaged with the key groove of the rectilinear barrel, and the tip end thereof is 3. The lens barrel according to claim 1, wherein the lens barrel is moved in the optical axis direction while being engaged with the spiral cam groove of the intermediate barrel and restraining the rotation of the lens frame.