JPH0593834A - Rotary extending mechanism - Google Patents

Abstract

PURPOSE:To provide the rotary extending mechanism which has a large extension quantity and reduce its size without the fall of an inside annular body. CONSTITUTION:Multi-thread gears 10d are formed on the outer periphery of the inside annular body 10, at least threads 12a and 12a' of the multi thread screws 10a and 12a are formed between those multi-thread gears, multi-thread escape grooves 12c that the gears 10d pass are formed in the inner periphery of an outside annular body 12; and threads which engage the threads of the inside annular body 10 are formed between those escape grooves 12c, the maximum diameter D2 of the threads 10a positioned between the multi-thread gears 10d is made smaller than the maximum diameter D1 of the threads 10a' of other multi-thread screws, a pinion 20 is arranged nearby the threads positioned between the multi-thread gears 10d corresponding to the maximum diameter of the threads, and this pinion 20 is engaged with one thread of the multi-thread gears regardless of the extension position of the inside annular body 10, thus constituting the rotary extending mechanism.

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 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 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 A thread that meshes with the thread of the inner annular body is formed between the grooves, and the maximum diameter of the thread located between the gears with multiple threads is smaller than the maximum diameter of the threads of other multi-thread screws. Formed and pinioned with this reduced diameter, multiple threads Corresponding to the maximum diameter of the screw thread located between the gears, the screw thread is disposed close to the screw thread, and this pinion is irrespective of the feeding position of the inner annular body, and It is characterized by meshing with gears.

According to this structure, a sufficient feed amount of the inner annular body can be ensured by the relationship between the plurality of gears and the pinion that meshes with any one of the plurality of gears. The inner threads of the inner annular body can be prevented from falling due to the threads of the multi-threaded screws which are also engaged with each other and which are also present between the clearance groove and the clearance groove.

Further, the pinion can be arranged on the inside by the amount that the maximum diameter of the screw thread located between the gears of the plurality of threads is smaller than the maximum diameter of the screw threads of the other multi-start screw, Therefore, 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 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 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 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 in a 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. These male multi-thread screw 10a, single thread 10a 'and gear 10d
The formation length s in the axial direction of is 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 winter 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.

Further, the maximum diameter D1 of the thread 10a 'is
Is smaller than the maximum diameter D2 of the thread of the female multi-start screw 10a. This difference in diameter is indicated by Δ in FIG.

A cutout 12d is formed in the helicoid ring 12, and the pinion 20 located in the cutout 12d.
, Meshes with the gear 10d. This pinion 20
Has an axial length capable of meshing with the three gears 10d at the same time, but meshes only with the rearmost and frontmost gears 10d at the front moving end and the rear moving end of the cam ring 10, respectively. The pinion 20 is located at a fixed position in the cutout 12d, and is rotationally driven by the motor 21.

In FIG. 1, the two pinions 20 are drawn at different positions, but this is to show the meshing relationship between the pinion 20 and the gear 10d at the forward end and the backward end of the cam ring 10. Actually, the pinion 20 does not move, but the cam ring 10 moves in the optical axis direction.

The pinion 20 has the maximum diameter D1 of the screw thread 10a 'smaller than the maximum diameter D2 of the screw thread 10a by Δ, as described above.
It is arranged as close as possible to the screw thread 10a 'within a range where it does not come into contact with a'.

Therefore, when the pinion 20 is rotationally driven via the motor 21, the rotation feeding mechanism of the above-described configuration transmits the rotation to the cam ring 10 via the gear 10d. Then, according to the engagement of the male multi-thread screw 10a (thread 10a ') and the female multi-thread screw 12a (thread 12a'), the cam ring 1
While 0 rotates forward and backward in the optical axis direction, zooming is performed.

When rotating the cam ring 10, the pinion 20 always meshes with one of the three gears 10d, and the thread 10a 'and the thread 12 are engaged.
The meshing of a'is maintained. Of course, the engagement between the male multi-thread screw 10a and the female multi-thread screw 12a is maintained, so that the helicoid ring 1
The cam ring 10 does not fall down with respect to 2.

Further, the pinion 20 has a thread 10a '.
As a result of being arranged as close as possible to the screw thread 10a 'within a range that does not come into contact with, it is possible to reduce the overall diameter including the pinion 20 and to reduce the outer diameter of the helicoid ring 12. Become. For example, if the minimum outer diameter of the helicoid ring 12 is determined by the wall thickness t of the clearance groove 12c,
The outer diameter of the helicoid ring 12 can be reduced by Δ as compared with the case where the maximum diameters D1 and D2 are the same. Figure 8
Shows a state in which the maximum diameters D1 and D2 are equal as a comparative example.

This Δ is a small amount of about 1 mm in an ordinary lens barrel, but is not a negligible amount in a small zoom lens camera which is required to be miniaturized and reduced in diameter to the limit. It is possible to arrange thin elements such as 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 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.

[0029]

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 present invention, the pinion can be arranged closer to the plurality of gears on the outer circumference of the inner annular body, and thus 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.

[Explanation of symbols]

 10 cam ring (inner ring) 10a male multi-thread screw 10a 'thread 10d gear 12 helicoid ring (outer ring) 12a female multi-thread 12a' thread 12c escape groove 12d notch 20 pinion D1 thread 10a ' Maximum diameter D2 Maximum diameter of screw thread 10a Difference between ΔD1 and D2

[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 proportion of the multiple thread to be formed in the circumferential direction is reduced by that amount, 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-start internal thread; the outer periphery of the inner annular body, is inclined in the same direction as the multi-strip external thread And a pinion that meshes with the gear and rotates the inner annular body relative to the outer annular body; in a rotary feeding mechanism, a plurality of the gears are formed on the outer periphery of the inner annular body. In addition, at least one male thread is formed between these multiple-thread gears, and the outer diameter of the male thread located between the above-mentioned multiple-thread gears is smaller than the outer diameter of other multiple-thread male threads. The pinion is formed to have a diameter larger than the outer diameter of the male screw so that the pinion does not interfere with the male screw formed between the gears, and the pinion is extended from the inner annular body. Regardless of position The serial was engaged in plural rows of at least Ichijo gear of the gear, to have the features.

According to this structure, the maximum diameter of the screw thread located between the gears having a plurality of threads is made smaller than the maximum diameters of the screw threads of the other multi-thread screws while preventing the inner annular body from collapsing. Since the pinion can be arranged on the inner side by the formed amount, the diameter can be reduced as a whole.

The pinion is arranged on the inner side (on the optical axis side) by the maximum diameter of the screw thread located between the gears having a plurality of threads, which is smaller than the maximum diameter of the screw threads of the other multi-thread screws. Therefore, 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 developed view of FIG. 1 and FIG. 5, the 0 is provided with a multi-start male screw 10a and a plurality of (in this embodiment, three) gears 10d parallel to each other, which are located at the rear portion. There is. 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 multi- thread male screw 10a, and there are many gears between the gears 10d.
A single thread 10a ' of the male thread 10a is formed. In other words, in the multi- thread male screw 10a, one or a plurality of threads 10a 'are cut off in a part of the circumferential direction thereof.
A gear 10d is provided at this cutout portion. In this embodiment, the threads of the multi-thread male screw 10a are every other thread.
Article 3 is excision, gears 10d are provided on their cutting portion. These multi-thread male threads 10a and threads 10a '
The formation length s of the gear 10d in the axial direction is 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 according to the screwing of the screw 12a and the screw thread 10a 'and the trough 12a', the cam ring 10 moves in the clearance groove 12c without contact.

The maximum radius (outer diameter / 2) D1 of the thread 10a 'between the gears 10d is set smaller than the maximum radius (outer diameter / 2) D2 of the thread of the multi-start male screw 10a.
This diameter difference Δ is shown in FIG. Further, the tooth depth of the gear 10d is also reduced by the difference Δ in correspondence with the screw thread 10a ′ whose diameter is reduced by the difference Δ. Therefore, since the pinion 20 is arranged close to the cam ring 10 by the difference Δ, the overall diameter including the pinion 20 is reduced.

Furthermore, the maximum outer diameter of the helicoid ring 12 (half
Diameter is determined by the wall thickness t of the escape groove 12c.
And, since the escape up the groove 12c is shallower only difference Δ, helicoid
The outer diameter of the ring 12 is such that the maximum radii D1 and D2 are the same.
The difference Δ is smaller than that of the comparative example shown in FIG . Tsuma
The thickness of the helicoid ring 12 is T2, and the screw 10a
The gear 10 from the cylindrical surface connecting the crest of the screw 10a with d12
Assuming that the tooth depth of d to the tip of the tooth is d2, the wall thickness T2 is T2 = t + d12 + d2-Δ = T1−Δ , so the maximum outer diameter (radius) of the helicoid ring 12 is
The difference Δ from the maximum outer diameter of the helicoid ring 112 shown in FIG.
Can be made smaller.

This difference Δ is a small amount of about 1 mm in an ordinary lens barrel, but is not a negligible amount in a small zoom lens camera which is required to be miniaturized and reduced in diameter to the limit. It is possible to arrange thin elements such as FPC boards.

A cutout 12d is formed in the helicoid ring 12, and the pinion 20 located in the cutout 12d.
, Meshes with the gear 10d. This pinion 20
Has an axial length capable of meshing with the three gears 10d at the same time, but meshes only with the rearmost and frontmost gears 10d at the front moving end and the rear moving end of the cam ring 10, respectively. The pinion 20 is rotatably supported by a fixed portion (not shown), is positioned at a fixed position in the notch 12d, and is rotationally driven by a motor 21.

In FIG. 1, the two pinions 20 are drawn at different positions, but this is to show the meshing relationship between the pinion 20 and the gear 10d at the forward end and the backward end of the cam ring 10. Actually, the pinion 20 does not move, but the cam ring 10 moves in the optical axis direction.

Therefore, when the pinion 20 is rotationally driven via the motor 21, the rotation of the main rotation feeding mechanism having the above-described structure transmits the rotation to the cam ring 10 via the gear 10d. Then, the cam ring 10 follows the engagement of the multi- thread male screw 10a (thread 10a ') and the multi- thread female screw 12a (thread 12a').
While rotating, moves back and forth in the direction of the optical axis for zooming.

When rotating the cam ring 10, the pinion 20 surely meshes with one of the three gears 10d, and the thread 10a 'and the thread 12a'.
Meshing is maintained. Of course, multi- thread male screw 10a and multi- thread female
Since the meshing of the threads 12a is also maintained, the cam ring 10 does not fall with respect to the helicoid ring 12.

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 multi-thread male screw 10a in the circumferential direction becomes short, and the cam ring 10 is likely to fall or rattle.

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.

[0028]

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 present invention, the pinion can be arranged closer to the plurality of gears on the outer circumference of the inner annular body, and thus 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.

[Explanation of Codes] 10 Cam Ring (Inner Ring) 10a Multi-thread Male Thread 10a 'Thread 10d Gear 12 Helicoid Ring (Outer Ring) 12a Multi-thread Female Thread 12a' Thread 12c Relief Groove 12d Notch 20 Pinion D1 Thread 10a 'Maximum diameter D2 Maximum diameter of screw thread 10a Δ D1 and D2 difference

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

[Procedure 3]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

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[Figure 8]

Claims (1)

[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, Forming a screw thread that meshes with the screw thread of the inner annular body, further, forming the maximum diameter of the screw thread located between the gears of the plurality of threads to be smaller than the maximum diameter of the screw threads of other multi-start threads, The pinion is made into this small diameter So as to correspond to the maximum diameter of the thread located between the strip of the gear, it is brought closer to the thread disposed, and the pinion, irrespective of the extended position of the inner annular body,
A rotary feeding mechanism characterized by meshing with at least one gear of the plurality of gears.