JPH0593835A - Rotary extending mechanism - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a rotary payout mechanism that can take a large amount of payout of a movable annular body (inner annular body) and is less likely to fall. [Structure] An inner annular body and an outer annular body that are screwed together via a multiple-thread male thread and a multiple-thread female thread ;
In the rotary feeding mechanism, a gear formed by inclining in the same direction as the multiple-thread male screw ; and a pinion that meshes with the gear and relatively rotates the inner annular body with respect to the outer annular body, A plurality of gears are formed on the outer periphery of the annular body, at least one male screw is formed between the gears, and further, depending on the feeding position of the inner annular body, A plurality of small width pinions that can be sequentially meshed with the gears and are spaced apart from each other are formed on the same pinion shaft.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary feeding mechanism that feeds one of a pair of annular bodies screwed together via a multiple thread (helicoid) while rotating it via a gear mechanism.

[0002]

2. Description of the Related Art For example, in a lens barrel, a movable (inner) annular body is screwed into a fixed (outer) annular body via a multiple thread screw, and the movable annular body is rotated to generate an optical beam. A large number of axially extending mechanisms are adopted. In the zoom compact camera, in order to drive the movable annular body with power, a gear is provided on the outer periphery of the movable annular body, and this gear is meshed with a pinion driven by a motor.

In this rotary feeding mechanism, it is necessary to provide both the multiple thread and the gear on the outer circumference of the movable annular body. Conventionally, in order to shorten the axial length of the movable annular body, this multi-thread screw and gear cut off a part of the thread of the multi-thread screw, and the cut portion is a gear inclined in the same direction as the multi-thread thread. Was provided. Thus, if the multiple thread and the gear are mixed in the same axial position, the axial length of the movable annular body can be shortened as compared with the case where both are provided in different axial positions.

However, it has been found that the following problems are encountered when trying to further increase the amount of feeding of the movable annular body in this rotary feeding mechanism. That is, in order to increase the feed amount, it is necessary to increase the number of teeth of the gear or increase the width of the gear and increase the axial length of the pinion meshing with the gear. However, increasing the number of teeth of the gear implies that the gear extends obliquely in the direction of the multiple thread, that is, the axial length of the movable annular body increases. Further, if the width of the gear is increased, the ratio of the multiple threads to be formed in the circumferential direction is correspondingly decreased, and as a result, the movable annular body falls down.

In order to increase the zoom ratio in a zoom lens of a camera which is required to be miniaturized to the utmost limit, it is necessary to give a sufficient amount of extension without causing the movable annular body to fall down. I can't meet the demand.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rotary feeding mechanism which can take a large amount of feeding of a movable annular body (inner annular body) and is less likely to fall down, based on the above-mentioned awareness of the problems of the rotary feeding mechanism. With the goal.

A further object of the present invention is to obtain a rotary feeding mechanism which can be downsized, in particular downsized.

[0008]

SUMMARY OF THE INVENTION According to the present invention, an inner annular body and an outer annular body are screwed together via a multi-thread screw, and a gear is provided on the outer periphery of the inner annular body inclining in the same direction as the multi-thread screw. In a rotary feeding mechanism that meshes a gear with a pinion and rotates the inner annular body relative to the outer annular body by the rotation of the pinion, a plurality of gears are formed on the outer periphery of the inner annular body, and these plural At least one thread of the multiple thread is formed between the gears, while on the other hand, the inner circumference of the outer annular body is formed with a plurality of relief grooves through which the multiple gears pass, and at the same time Formed between the grooves is a screw thread that meshes with the screw thread of the inner annular body, and further, according to the feeding position of the inner annular body, a plurality of small width pinions that can be sequentially engaged with a plurality of gears and are spaced apart from each other are the same. Formed on the pinion shaft of It is characterized in that.

According to this structure, a sufficient feeding amount of the inner annular body can be ensured by the meshing relationship between the plurality of gears and the narrow width pinion that is sequentially meshed with the plurality of gears.
Moreover, the threads of the multi-threaded screws, which are also present between the plurality of gears and the clearance groove, and which mesh with each other, can prevent the inner annular body from collapsing.

On the pinion shaft, a small diameter portion having a diameter smaller than that of the small width pinion is formed between the small width pinions. And
By disposing the pinion shaft at a position where the small diameter portion is as close as possible to the screw thread located between the plurality of gears of the inner annular body, the pinion shaft is disposed inside, and The diameter can be reduced.

[0011]

The present invention will be described below with reference to the illustrated embodiments.
First, with reference to FIGS. 5 to 7, an example of a zoom lens barrel provided with a rotary feeding mechanism, which is a target of the present invention, will be described.

Fixed lens barrel 11 integrated with the camera body
The helicoid ring (outer annular body) 12 is fixed to the female multi-threaded screw 12a of the helicoid ring 12, and the male multi-threaded screw 10a formed on the outer peripheral surface of the cam ring (inner annular body) 10 is screwed into the helicoid ring 12. ing. A female multi-thread screw 10b and an inner cam groove 10c are formed inside the cam ring 10, and the female multi-thread screw 10b has a front lens group barrel (male helicoid body) 13
Male multi-threaded screw 13a is screwed. A linear guide plate 14 is located at the rear end of the cam ring 10, and a radial projection 14a of the linear guide plate 14 is fitted in a linear guide groove 11a formed in the fixed lens barrel 11. A linear guide ring 15 is fixed to the linear guide plate 14, and the cam ring 10 is rotatable with respect to the linear guide ring 15.

A shutter holding frame 13b, to which a rear end of an annular shutter unit 16 is fixed, is fixed to the front lens barrel 13, and a helicoid ring 17 integrally provided on the inner peripheral portion of the shutter unit 16 has a shutter holding frame 13b. The front lens group frame 18 holding the front lens group is screwed. Shutter unit 1
The drive pin 16a is engaged with a driven pin 18a which is integrated with the front lens group frame 18. Drive pin 16a
As is well known, the lens is driven to rotate by an angle according to the distance measurement signal from the distance measuring device, and this rotation is transmitted to the front lens group frame 18 via the driven pin 18a, and the front lens group frame 18 (front lens group) is moved. While L1) rotates, it moves in the optical axis direction for focusing. Further, the shutter unit 16 is
The shutter blade 16b is opened and closed according to the brightness signal of the subject.

Rear lens group frame 1 supporting the rear lens group L2
9 has a cam pin 19a protruding in the radial direction, and this cam pin 19a is fitted in the above-mentioned cam groove 10c formed on the inner surface of the cam ring 10. The rear lens group frame 19 and the shutter holding frame 13b are connected to each other by the linear guide ring 15 described above.
The vehicle is guided straight by the straight guide surface formed on. FIG. 5 shows the rectilinear guide surface 15a of the rectilinear guide ring 15 and the rectilinear guide surface 19b of the rear lens group frame 19 which are engaged with each other.

The cam pin 19a of the rear lens group frame 19 has a recess 13 formed in the rear end surface of the front lens barrel 13 during assembly.
fit in b. This is because when the male multi-thread screw 13a on the outer circumference of the front lens barrel 13 is screwed into the female multi-thread screw 10b of the cam ring 10, the cam pin 19a is simultaneously moved to the inner cam groove 10c.
It is a structure to fit in. After assembly, the front group lens barrel 13 is rotated by the cam ring 10 so that the front group lens barrel 13 has multiple threads 10b, 13a
Accordingly, the rear lens group frame 19 follows the cam groove 10c and independently moves in the optical axis direction.

That is, the zoom lens barrel having the above structure is
When the cam ring 10 is rotationally driven, the cam ring 10 itself moves in the optical axis direction according to the relationship between the male multi-thread screw 10a and the female multi-thread screw 12a. At the same time, female multi-start thread 10b and male multi-start thread 1
Due to the screwing relationship of 3a and the linear guide mechanism of the shutter holding frame 13b and the linear guide ring 15, the front group lens barrel 13 is provided.
The (front lens group L1) moves straight in the optical axis direction. When the cam ring 10 rotates, the relationship between the cam groove 10c on the inner surface of the cam ring 10 and the cam pin 19a provided on the rear lens group frame 19 and the rectilinear guide mechanism of the rear lens group frame 19 and the rectilinear guide ring 15 cause the rear group lens to move. The frame 19 (rear group lens L2) moves in the optical axis direction to perform zooming.

In the present invention, for example, the helicoid ring (outer annular body) 12 in the zoom lens barrel having the above-mentioned structure
The gist of the present invention is the engagement structure between the cam ring (inner annular body) 10 and the rotation drive mechanism of the cam ring 10. Cam ring 1
As shown in the development view of FIG. 1 and FIG. 5, the male 0 is formed with a male multi-thread screw 10a and a plurality of threads (three threads in this embodiment) 10d parallel to each other. ing. The gear 10d is composed of a spur gear whose teeth are parallel to the axis of the cam ring 10, is inclined in the same direction as the direction of the ridges of the male multi-thread screw 10a, and between the gears 10d,
A single thread 10a 'is formed on the male multi-thread screw 10a. In other words, the male multi-thread screw 10a is cut off at one part in the circumferential direction except for one thread 10a ', and the cut portion is provided with the gear 10d. In this embodiment, the multi-start screw 10a is a triple-start screw, and the gear 10d is provided at the cut-out portion of the double-start screw. The axially formed lengths s of the male multi-thread screw 10a, the single thread 10a 'and the gear 10d are the same.

On the other hand, as shown in FIG. 2, the helicoid ring 12 has, on its inner surface, a male multithread screw 10 of the cam ring 10.
a, a female multi-start thread 12a, and a single thread 12 corresponding to the single thread 10a 'and the triple gear 10d, respectively.
a'and an escape groove 12c are formed. That is, the screw thread 10a ′ and the screw thread 12a ′ mesh with each other, and the gear 10d has the male multi-thread screw 10a (the screw thread 10a).
When the cam ring 10 rotates in accordance with the meshing of the a ′) and the female multi-thread screw 12a (thread 12a ′), the cam ring 10 moves in the escape groove 12c without contact.

A cutout 12d is formed in the helicoid ring 12, and the pinion shaft 20 is located in the cutout 12d. The pinion shaft 20 can be meshed with the three gears 10d depending on the rotational extension position of the cam ring 10.
It has a small width pinion 20a and a small diameter portion 20b located between the small width pinions 20a. Small diameter part 20
b has a smaller diameter than the narrow pinion 20a, and the thread 10
It is formed at a position corresponding to the position of a '. And
In the pinion shaft 20, the small diameter portion 20b has a thread 10a '.
Is arranged as close to the cam ring 10 as possible within a range where it does not come into contact with the tip of the cam ring. This pinion shaft 20 has a notch 1
It is located at a fixed position within 2d and is rotationally driven by the motor 21.

In FIG. 1, two pinion shafts 20 are drawn at different positions, but this is the engagement relationship between the narrow pinion 20a of the pinion shaft 20 and the gear 10d at the forward and backward ends of the cam ring 10. In practice, the pinion shaft 20 does not move, but the cam ring 10 moves in the optical axis direction.

Therefore, when the pinion shaft 20 is rotationally driven via the motor 21, the main rotary feeding mechanism having the above-described structure is arranged so that one of the narrow pinions 2 depending on the rotational feeding position of the cam ring 10.
Since 0a is meshed with the gear 10d, the cam ring 10 is rotationally driven. Then, the male multi-thread screw 10a (thread 1
0a ′) and the female multi-start screw 12a (thread 12a ′) are meshed with each other, the cam ring 10 advances and retreats in the optical axis direction while rotating, and zooming is performed.

When the cam ring 10 is rotated and fed, the three narrow pinions 20a are connected to each other by the three gears 10.
The thread 10a 'and the thread 12a' are maintained in mesh with each other. Of course, male multi-thread screw 1
Since the meshing between 0a and the female multithread screw 12a is also maintained, the cam ring 10 does not fall over the helicoid ring 12.

Further, a small diameter portion 20b is provided between the small width pinions 20a, and the pinion shaft 20 is arranged at a position where the small diameter portion 20b is as close as possible to the male multi-thread screw 10a (thread 10a '). Therefore, the diameter can be reduced. Now, considering the maximum external shape D1 of the male multi-thread screw 10a as a reference, in FIG.
The inscribed circle diameter inscribed in a is (D1-Y). on the other hand,
When the pinion shaft 20 is simply formed with the pinion 20a ′ having the same diameter, the pinion shaft 20 must be arranged further outside in order to avoid interference between the pinion 20a ′ and the screw thread 10a ′. FIG. 8 shows this state, and the diameter of the inscribed circle inscribed in the narrow pinion 20a ′ centering on the optical axis is (D1 + y). That is, according to the present invention,
As compared with the case of FIG. 8, the diameter can be reduced by (Y + y).

This (Y + y) is a small amount of about 1 mm in an ordinary lens barrel, but it is a non-negligible amount in a small zoom lens camera which is required to be miniaturized to a minimum size and a small diameter. In, for example, FPC
It is possible to place thin elements such as substrates.

By the way, FIGS. 6 and 7 show two comparative examples for obtaining the same feed amount of the cam ring 10 as in the embodiment of the present invention without forming the three gears 10d. FIG. 6 shows an example in which a gear 10d 'having the same width as the gear 10d of the embodiment of the present invention is formed as one line, and FIG. 7 shows a wide gear 10d having the same axial length s as the gear 10d of the embodiment of the present invention. In the comparative example of FIG. 6, the installation length of the gear 10d ′ in the axial direction, that is, the cam ring 1 is shown.
0 becomes long, and in the comparative example of FIG. 7, the installation length of the male multi-thread screw 10a in the circumferential direction becomes short, and the cam ring 10 easily falls.

The zoom lens barrel shown in FIGS. 3 to 5 is an example of a device to which the rotary feeding mechanism of the present invention can be applied. INDUSTRIAL APPLICABILITY The present invention can be widely applied to a rotary payout mechanism for another zoom lens barrel or a rotary payout mechanism other than the zoom lens barrel.

[0027]

As described above, according to the rotary feeding mechanism of the present invention, the feeding of the inner annular body which is rotationally driven through the gear formed on the outer peripheral surface by being screwed into the outer annular body through the multiple thread is carried out. A large amount can be taken and the fall can be prevented. Further, according to the second aspect, the pinion shaft can be arranged closer to the plurality of gears on the outer circumference of the inner annular body, so that the entire diameter can be reduced.

[Brief description of drawings]

FIG. 1 is a development view of an inner annular body (cam ring) showing an embodiment of a rotary feeding mechanism according to the present invention.

FIG. 2 is a cross-sectional view of a meshed state of the inner annular body and the outer annular body.

FIG. 3 is a cross-sectional view showing an example of a zoom lens barrel to which a rotary feeding mechanism according to the present invention can be applied.

4 is a cross-sectional view of a main part of a lens barrel of the zoom lens in FIG.

5 is an exploded perspective view of a main part of the zoom lens barrel of FIG.

FIG. 6 is a developed view corresponding to FIG. 1 and shown as a comparative example.

FIG. 7 is a development view corresponding to FIG. 1 and shown as another comparative example.

FIG. 8 is a sectional view corresponding to FIG. 2, which is shown as a comparative example.

[Explanation of symbols]

 10 cam ring (inner ring) 10a male multiple thread 10a 'screw thread 10d gear 12 helicoid ring (outer ring) 12a female multiple thread 12a' thread 12c escape groove 12d notch 20 pinion shaft 20a small pinion 20b small diameter part

[Procedure amendment]

[Submission date] December 24, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Rotational feeding mechanism

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary feeding mechanism that feeds one of a pair of annular bodies screwed together via a multiple thread (helicoid) while rotating it via a gear mechanism.

[0002]

2. Description of the Related Art For example, in a lens barrel, a movable (inner) annular body is screwed into a fixed (outer) annular body via a multiple thread screw, and the movable annular body is rotated to generate an optical beam. A large number of axially extending mechanisms are adopted. In the zoom compact camera, in order to drive the movable annular body with power, a gear is provided on the outer periphery of the movable annular body, and this gear is meshed with a pinion driven by a motor.

In this rotary feeding mechanism, it is necessary to provide both the multiple thread and the gear on the outer circumference of the movable annular body. Conventionally, in order to shorten the axial length of the movable annular body, this multi-thread screw and gear cut off a part of the thread of the multi-thread screw, and the cut portion is a gear inclined in the same direction as the multi-thread thread. Was provided. Thus, if the multiple thread and the gear are mixed in the same axial position, the axial length of the movable annular body can be shortened as compared with the case where both are provided in different axial positions.

However, it has been found that the following problems are encountered when trying to further increase the amount of feeding of the movable annular body in this rotary feeding mechanism. That is, in order to increase the feed amount, it is necessary to increase the number of teeth of the gear or increase the width of the gear and increase the axial length of the pinion meshing with the gear. However, increasing the number of gear teeth means that the gear extends obliquely in the direction of the multiple thread, that is, the axial length of the movable annular body increases. Further, if the width of the gear is increased, the ratio of the multi-threaded screw to be formed in the circumferential direction is reduced accordingly, and as a result, the movable annular body falls or rattles.

In order to increase the zoom ratio in a zoom lens of a camera which is required to be miniaturized to the utmost limit, it is necessary to give a sufficient amount of extension without causing the movable annular body to fall down. I can't meet the demand.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rotary feeding mechanism which can take a large amount of feeding of a movable annular body (inner annular body) and is less likely to fall down, based on the above-mentioned awareness of the problems of the rotary feeding mechanism. With the goal.

A further object of the present invention is to obtain a rotary feeding mechanism which can be downsized, in particular downsized.

[0008]

SUMMARY OF THE INVENTION The present invention includes an inner annulus and outer annulus screwed through the multi-start external thread and multi-thread female screw <br/>; on the outer periphery of the inner annular body, the same direction as the multiple-start male thread And a pinion that meshes with the gear and that rotates the inner annular body relative to the outer annular body, wherein the gear is provided on the outer periphery of the inner annular body. A plurality of threads are formed, and at least one male thread is formed between the gears having a plurality of threads.Furthermore, depending on the feeding position of the inner annular body, the gears having a plurality of threads can be sequentially meshed with each other, respectively. It is characterized in that a plurality of small pinions separated from each other are formed on the same pinion shaft.

According to this structure, a sufficient feeding amount of the inner annular body can be ensured by the meshing relationship between the plurality of gears and the narrow width pinion that is sequentially meshed with the plurality of gears.
Moreover, the threads of the multi-threaded screws, which are also present between the plurality of gears and the clearance groove, and which mesh with each other, can prevent the inner annular body from collapsing.

On the pinion shaft, a small diameter portion having a diameter smaller than that of the small width pinion is formed between the small width pinions. And
By disposing the pinion shaft at a position where the small diameter portion is as close as possible to the screw thread located between the plurality of gears of the inner annular body, the pinion shaft is moved to the inner side (optical axis side). By arranging them, the diameter can be reduced as a whole.

[0011]

The present invention will be described below with reference to the illustrated embodiments.
First, with reference to FIGS. 5 to 7, an example of a zoom lens barrel provided with a rotary feeding mechanism, which is a target of the present invention, will be described.

Fixed lens barrel 11 integrated with the camera body
The helicoid ring (outer annular member) 12 is fixed, the multi-strip female ne Flip 12a of the helicoid ring 12, multi-start external thread 10a is screwed formed on the outer peripheral surface of the cam ring (inner annular member) 10 ing. Inside the cam ring 10, have multi-start internal thread 10b and inner cam groove 10c is formed, the multi-strip female
The screw 10b has a front lens group barrel (male helicoid body) 13
The multi-thread male screw 13a is screwed. A linear guide plate 14 is located at the rear end of the cam ring 10, and a radial projection 14a of the linear guide plate 14 is fitted in a linear guide groove 11a formed in the fixed lens barrel 11. A linear guide ring 15 is fixed to the linear guide plate 14, and the cam ring 10 is rotatable with respect to the linear guide ring 15.

A shutter holding frame 13b, to which a rear end of an annular shutter unit 16 is fixed, is fixed to the front lens barrel 13, and a helicoid ring 17 integrally provided on the inner peripheral portion of the shutter unit 16 has a shutter holding frame 13b. The front lens group frame 18 holding the front lens group L1 is screwed. The shutter unit 16 has its drive pin 16a engaged with a driven pin 18a integrated with the front lens group frame 18. Drive pin 1
As is well known, 6a is rotationally driven by an angle according to the distance measurement signal from the distance measuring device, and this rotation is transmitted to the front lens group frame 18 via the driven pin 18a, and the front lens group frame 18
The (front lens group L1) moves in the optical axis direction while rotating, and focusing is performed. Further, the shutter unit 16 opens and closes the shutter blade 16b according to the brightness signal of the subject.

Rear lens group frame 1 supporting the rear lens group L2
9 has a cam pin 19a protruding in the radial direction, and this cam pin 19a is fitted in the above-mentioned cam groove 10c formed on the inner surface of the cam ring 10. The rear lens group frame 19 and the shutter holding frame 13b are connected to each other by the linear guide ring 15 described above.
The vehicle is guided straight by the straight guide surface formed on. FIG. 5 shows the rectilinear guide surface 15a of the rectilinear guide ring 15 and the rectilinear guide surface 19b of the rear lens group frame 19 which are engaged with each other.

The cam pin 19a of the rear lens group frame 19 has a recess 13 formed in the rear end surface of the front lens barrel 13 during assembly.
fit in b. This is a multiple thread on the outer circumference of the front lens barrel 13.
When the male screw 13a is screwed into the multiple thread female screw 10b of the cam ring 10, the cam pin 19a is simultaneously moved to the inner cam groove 10c.
It is a structure to fit in. After assembly, the front group lens barrel 13 is rotated by the cam ring 10 so that the front group lens barrel 13 has multiple threads 10b, 13a
Accordingly, the rear lens group frame 19 independently moves in the optical axis direction according to the cam groove 10c.

That is, the zoom lens barrel having the above structure is
When the cam ring 10 is driven to rotate, the multi-thread male screw 10a and the multi- thread male thread 10a
The cam ring 10 itself moves in the optical axis direction according to the relationship of the female screw 12a. At the same time, multi-condition the female screw 10b and the multiple-start male thread 1
Due to the screwing relationship of 3a and the linear guide mechanism of the shutter holding frame 13b and the linear guide ring 15, the front group lens barrel 13 is provided.
The (front lens group L1) moves straight in the optical axis direction. When the cam ring 10 rotates, the relationship between the cam groove 10c on the inner surface of the cam ring 10 and the cam pin 19a provided on the rear lens group frame 19 and the rectilinear guide mechanism of the rear lens group frame 19 and the rectilinear guide ring 15 cause the rear group lens to move. The frame 19 (rear group lens L2) moves in the optical axis direction to perform zooming.

In the present invention, for example, the helicoid ring (outer annular body) 12 in the zoom lens barrel having the above-mentioned structure
The gist of the present invention is the engagement structure between the cam ring (inner annular body) 10 and the rotation drive mechanism of the cam ring 10. Cam ring 1
As shown in the development view of FIG. 1 and FIG. 5, the 0 is formed with a multi- thread male screw 10a and a plurality of threads (three threads in this embodiment) parallel to each other, which are located at the rear portion thereof. There is. Gear 10d is intended that the teeth consist of parallel spur gear to the axis of the cam ring 10 and is inclined mountain in the same direction as the direction of multiple-start male screw 10a, between each gear 10d, multithread
A single thread 10a 'of the male screw 10a is formed. With other words, the multi-strip male I Flip 10a, the circumferential direction of the Paragraph or plural rows in part thread 10a 'is excised, the gear 10d is provided in the cutting portion. In this embodiment, the threads of the multi-thread male screw 10a are placed every other thread.
Three cuts are made, and gears 10d are provided at those cuts. These multiple male threads 10a, one thread 1
0a 'and the formation length s of the gear 10d in the axial direction are the same.

On the other hand, as shown in FIG. 2, the helicoid ring 12 has, on its inner surface, a multi-thread male screw 10 of the cam ring 10.
a, a multi-thread female thread 12a, a two-thread female thread (valley portion) 12a ', and a clearance groove 12c corresponding to the two-thread male thread (thread) 10a' and the three-wheel gear 10d, respectively. That is, the thread 10a 'and the valley 12a' are screwed together, and the gear 10d has a multi-start male thread 10a and a multi-start female thread.
When the cam ring 10 rotates in accordance with the screwing of the screw 12a and the screw thread 10a 'and the trough 12a', the cam ring 10 moves in the escape groove 12c without contact.

A cutout 12d is formed in the helicoid ring 12, and the pinion shaft 20 is located in the cutout 12d. The pinion shaft 20 can be meshed with the three gears 10d depending on the rotational extension position of the cam ring 10.
It has a small width pinion 20a and a small diameter portion 20b located between the small width pinions 20a. Small diameter part 20
b has a smaller diameter than the narrow pinion 20a, and the thread 10
It is formed at a position corresponding to the position of a '. And
The pinion 20 shaft has a narrow pinion 20a and a gear 10d.
It is placed close to the cam ring 10 to the meshing position.
It And this pinion shaft 20 rotates in the notch 12d.
It is rotatably supported and is driven to rotate by a motor 21.

In FIG. 1, two pinion shafts 20 are drawn at different positions. This is because the pinion shaft 20 meshes with the small width pinion 20a of the pinion shaft 20 at the forward and backward ends of the cam ring 10. This is to show the relationship, and in reality, the pinion shaft 20 does not move, but the cam ring 10 moves in the optical axis direction. The pinion 20 is a narrow pinion.
20a contacts cam ring 10 until it meshes with gear 10d.
It is placed close to each other. And this pinion 20
It is rotatably supported in the notch 12d and is driven by the motor 21.
Driven to rotate.

Therefore, when the pinion shaft 20 is rotationally driven via the motor 21, the main rotary feeding mechanism having the above-described structure is arranged so that one of the narrow pinions 2 depending on the rotational feeding position of the cam ring 10.
Since 0a is meshed with the gear 10d, the cam ring 10 is rotationally driven. Then, the multi-thread male screw 10a (thread 1
0a ′) and the female multi-start screw 12a (thread 12a ′) are meshed with each other, the cam ring 10 advances and retreats in the optical axis direction while rotating, and zooming is performed.

When the rotation of the cam ring 10 is extended,
The three small width pinions 20a surely mesh with any of the three gears 10d, and the thread 10a 'and the thread 1
The meshing of 2a 'is maintained. Of course, the engagement between the multiple male thread 10a and the female multiple thread 12a is also maintained, so that the cam ring 10 does not tilt or rattle with respect to the helicoid ring 12.

The pinion 20 has three small width pinions 20a that can be engaged with the three gears 10d according to the feeding position of the cam ring 10, and a small diameter portion 20b located between the small width pinions 20a. ing. Small diameter part 20b
Has a smaller diameter than the narrow pinion 20a and has a thread 1
It is formed at a position corresponding to the position of 0a '.

A gear 10d having teeth parallel to the axial direction of the cam ring arranged along the thread 10a 'is formed between the threads 10a'. On the other hand, a small-diameter portion 20b is provided between the small-width pinions 20a ', and the small-diameter portion 20b is a multi-row male.
The screw 10a (thread 10a ') is not interfered with. Therefore, since the pinion 20 and the screw thread 10a 'do not interfere with each other, it is possible to form the tooth depth of the gear 10d in consideration of only the meshing with the narrow pinion 20a.

Therefore, in the present embodiment, the tooth depth of the gear 10d is set to be the same as the tooth depth of the narrow pinion 20a from the surface of the cam ring 10. In this way, the pinion shaft 20 can be arranged closer to the cam ring 10 by the amount that the tooth depth of the gear 10d is reduced, so that the overall diameter can be reduced.

Further, the thickness T of the helicoid ring 12 is the sum of the thickness t at the bottom of the clearance groove 12c and the tooth depth d (T = t +).
d). Here, as shown in FIG. 8, the pinion shaft 1
20 simply forms the pinion 120a 'having the same diameter.
And the tooth of the multi-thread male screw 110a (from the valley bottom to the peak
Height) d1, a cylindrical surface connecting the crest multiple-start male thread 110a
To tooth tip of gear 1 10d is d2, relief groove 1
If the thickness of the bottom of 12c is t, the helicoid ring 112
Has a wall thickness T1 of T1 = d1 + d2 + t . Accordingly, in the present real 施例is helicoid ring 1 2
The radius of the tooth is smaller than the thickness T1 of the helicoid ring 112.
It became possible to make it smaller by d1 minutes.

This d1 is a small amount of about 1 mm in a normal lens barrel, but is not a negligible amount in a small zoom lens camera which is required to be downsized and its diameter to the limit, and within the space. It is possible to place thin elements, eg FPC boards.

By the way, FIGS. 6 and 7 show two comparative examples for obtaining the same feed amount of the cam ring 10 as in the embodiment of the present invention without forming the three gears 10d. FIG. 6 shows an example in which a gear 10d ′ having the same width as the gear 10d of the embodiment of the present invention is formed as one thread, and FIG. 7 shows a wide gear having the same axial length s as the gear 10d of the embodiment of the present invention. 10d ″ is formed. In the comparative example of FIG. 6, the installation length of the gear 10d ′ in the axial direction, that is, the cam ring 1 is shown.
0 becomes long, and in the comparative example of FIG. 7, the installation length of the multi-thread male screw 10a in the circumferential direction becomes short, and the cam ring 10 easily falls.

The zoom lens barrel shown in FIGS. 3 to 5 shows an example of an apparatus to which the rotary feeding mechanism of the present invention can be applied. INDUSTRIAL APPLICABILITY The present invention can be widely applied to a rotary payout mechanism for another zoom lens barrel or a rotary payout mechanism other than the zoom lens barrel.

[0030]

As described above, according to the rotary feeding mechanism of the present invention, the feeding of the inner annular body which is rotationally driven through the gear formed on the outer peripheral surface by being screwed into the outer annular body through the multiple thread is carried out. A large amount can be taken and the fall can be prevented. Further, according to the second aspect, the pinion shaft can be arranged closer to the plurality of gears on the outer circumference of the inner annular body, so that the entire diameter can be reduced.

[Brief description of drawings]

FIG. 1 is a development view of an inner annular body (cam ring) showing an embodiment of a rotary feeding mechanism according to the present invention.

FIG. 2 is a cross-sectional view of a meshed state of the inner annular body and the outer annular body.

FIG. 3 is a cross-sectional view showing an example of a zoom lens barrel to which a rotary feeding mechanism according to the present invention can be applied.

4 is a cross-sectional view of a main part of the zoom lens barrel in FIG.

5 is an exploded perspective view of a main part of the zoom lens barrel of FIG.

FIG. 6 is a developed view corresponding to FIG. 1 and shown as a comparative example.

FIG. 7 is a development view corresponding to FIG. 1 and shown as another comparative example.

FIG. 8 is a sectional view corresponding to FIG. 2, which is shown as a comparative example.

[Description of reference numerals] 10 cam ring (inner annular member) 10a multi-start external thread 10a 'thread 10d gear 12 helicoid ring (outer annular member) 12a female multiple thread 12a' threads 12c relief groove 12d notch 20 pinion shaft 20a slightly Pinion 20b Small diameter part

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Claims (2)

[Claims] 1. An inner annular body and an outer annular body which are screwed together via a multi-start screw; a gear formed on the outer periphery of the inner annular member so as to be inclined in the same direction as the thread of the multi-start screw; and In a rotary feeding mechanism including a pinion that meshes with the gear and rotates the inner annular body relative to the outer annular body, a plurality of the gears are formed on the outer periphery of the inner annular body, and the plurality of gears are formed. , At least one thread of a multi-thread screw is formed, and a plurality of escape grooves through which the gear passes are formed on the inner circumference of the outer annular body, and between the escape grooves, A plurality of small width pinions that are spaced apart from each other and that form a thread that meshes with the threads of the inner annular body and that can be sequentially engaged with the plurality of gears according to the feeding position of the inner annular body are provided on the same pinion shaft. Formed into Rotating feeding mechanism, characterized in that. 2. The pinion shaft according to claim 1, wherein a small diameter portion having a diameter smaller than that of the small width pinion is formed between the small width pinions, and the pinion shaft has a small diameter portion of the plurality of gears. A rotary feeding mechanism arranged at a position as close as possible to a thread located between them.