JPH10319300A - Lens barrel with ultrasonic motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens barrel with a ultrasonic motor capable of accomplishing both high assemblability and cost reduction without newly adding many parts. SOLUTION: A retainer 2 for a bearing 24 used for an ultrasonic motor is formed so as to be provided with plural notches 2a for storing balls 3, and at least one of the notches 2a is open to one way in the axial direction of the bearing, the other notch 2a is open to the other way in the axial direction, then, the retainer 2 is molded by pulling out two molds in one way, thus, the manufacturing cost is reduced. And also, the balls 3 are held by the retainer 2 after assembling the bearing 24, and simultaneously, the retainer 2 is held by the balls 3, then, the retainer 2 is prevented from falling off in the axial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel provided with an ultrasonic motor used for, for example, focusing driving.

[0002]

2. Description of the Related Art An ultrasonic motor has advantages such as a simple structure and an annular rotor, so that it is often installed in a lens barrel and used for focusing driving of a photographing lens.

In an ultrasonic motor installed in a lens barrel, a bearing is usually provided so as to rotatably support a rotor with respect to a stator. FIG.
7 to 7 are partially cutaway perspective views of a conventional bearing used in a lens barrel.

In FIGS. 4 to 7, each of the bearings includes an inner ring 1, an outer ring 4, and a ball 3 sandwiched between the two wheels.
And a retainer for holding the balls 3 at equal intervals, but only in the shape of the retainer. First, in the bearing shown in FIG.
Reference numeral 02 denotes a shape in which one elongated flat plate is rounded, and has holes 102a formed at equal intervals in the circumferential direction. The ball 3 is held in the hole 102a.

In the bearing shown in FIG. 5, a retainer 202 is a short and long rod-like member curved with a curvature substantially equal to the outer diameter of the inner ring 1, and holds the ball 3 between the respective rod-like members. .

In the bearing shown in FIG. 6, the retainer 302 has a shape obtained by rolling a single elongated flat plate, similarly to the bearing shown in FIG.
Letter-shaped notches 302a are formed at equal intervals in the circumferential direction, and the balls 3 are held in the notches 302a.

In the bearing shown in FIG. 7, the retainer 402 is two annular plates provided with recesses 402a at equal intervals in the circumferential direction. Such an annular plate 402 has a depression 4
02a are opposed to each other, and
The balls 3 are attached to each other so that the ball 3 is held between them.

[0008]

In the case of a bearing as shown in FIG. 4, when the retainer 102 is manufactured by machining, it takes time and effort to machine each hole 102a, and the manufacturing cost increases. Meanwhile, retainer 1
If it is attempted to integrally mold 02 from the resin material including the holes, the mold layout becomes complicated, and the manufacturing cost also increases.

Further, in the bearing as shown in FIG. 5, although the unit cost of the rod-shaped members 202 disposed between the balls 3 is relatively low, there is no means for connecting the rod-shaped members 202 to each other. When the outer race 4 is removed, the balls are easily separated from each other, and the assemblability is very poor.

On the other hand, in the bearing as shown in FIG. 6, unlike the retainer 102 shown in FIG.
Since the mold is released in one direction during the molding of No. 02, the mold is easily split, so that the production cost can be kept relatively low. However, since all the notches 302a of the retainer 302 are open in one direction, it is easy to fall off from the bearing at the time of transportation, for example, after assembling. It is.

Further, in the bearing shown in FIG.
A very common retainer 402 is provided, and the retainer 402 does not fall off from the bearing after the assembly, and the handling of the bearing is convenient. However, since the retainer 402 is formed by combining two parts, the assemblability is poor and the manufacturing cost is relatively high.

The present invention has been made in view of the above problems, and has as its object to provide a lens barrel having an ultrasonic motor that achieves both high assemblability and low cost without adding many new components. I do.

[0013]

In order to achieve the above object, a lens barrel having an ultrasonic motor according to the present invention comprises an ultrasonic motor (50) comprising a stator (21) and a rotor (22). , The stator (21) and the rotor (2)
A bearing (24) for rotatably supporting 2), wherein the bearing (24) comprises an outer ring (4) and an inner ring (1).
And a plurality of balls (3) arranged between the two wheels, and a retainer (2) for holding the balls (3), wherein the retainer (2) has a plurality of notches for accommodating the balls (3). (2a), at least one of the notches (2a) is open in one axial direction of the bearing, and the rest of the notches (2a) is open in the other axial direction. Features.

According to the lens barrel having the ultrasonic motor of the present invention, the retainer (2) has a plurality of notches (2a) for accommodating the balls (3), and at least one of the notches (2a) is formed. One is open in one direction in the axial direction of the bearing, and the remaining notch (2a) is open in the other direction in the axial direction, so that the retainer (2) is pulled out of the two molds in one direction. , Whereby the manufacturing cost can be reduced. Also, retainer (2)
Is the ball (3) after assembling the bearing (24)
Is held from the ball (3) at the same time as
It does not fall off in the axial direction.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view in the optical axis direction of a lens barrel provided with an ultrasonic motor according to an embodiment of the present invention. The lens barrel shown in FIG. 1 is an autofocus-compatible lens barrel that can perform both manual focus adjustment and focus adjustment using a motor driving force.

In FIG. 1, a focus ring 12 rotatable with respect to a fixed cylinder 10 is a so-called focus adjustment operation member, and is connected to a connection member 18. In the case of performing the focus adjustment manually, the rotation of the focus ring 12 based on the manual force of the photographer is performed by the motor holder 2 supporting the motor via the connecting member 18 and the roller 19.
It is conveyed to 0.

The motor mounted on the motor holder 20 is a known annular ultrasonic motor 50, which comprises a stator 21 and a rotor 22. Motor 5
Numeral 0 denotes an annular disk, a part of which is elastically protruded by a pressing spring 25 on the inner fixed cylinder 23 attached to the motor holder 20 to form a bearing with a collar 26 from the rotor side to the stator side in the figure. Pressurized through 24. This pressing force is set to be at least larger than a force necessary for preventing the rotor 22 and the stator 21 from slipping and smaller than a force that hinders the operation of the bearing 24.

At the time of manual focus adjustment in the lens barrel according to the present embodiment, the focus ring 1
When the photographer rotates the motor holder 20 and the stator 2 via the connecting member 18 and the roller 19,
1, the rotor 22, and the bearing 24 are transmitted to the outer race 4 (FIG. 2) which is a component.

The rotation transmitted to the outer race 4 is transmitted to the rotary cylinder 27 by an engagement mechanism (not shown). The rotary cylinder 27 has a lead groove (not shown) for driving a drive pin 31 for moving the focus lens group 30 to a focal point.
Moves in the direction of the optical axis, thereby enabling a focal point movement.

On the other hand, at the time of autofocusing with the lens barrel according to the present embodiment, the stator 20 of the motor 50 is
Does not rotate, and only the rotor 21 rotates. The subsequent transmission of rotation is the same as during manual focus adjustment.

Next, the bearing 24 according to the present embodiment will be described.
Will be described in more detail with reference to FIG. FIG.
FIG. 3 is a partially cutaway perspective view of the bearing 24 according to the present embodiment. In FIG. 2, the bearing 24 includes the inner ring 1 and
Outer ring assembly 4 including first outer ring 4a and second outer ring 4b
And a ball 3 sandwiched between the two wheels, and a retainer 2 for holding the ball 3 at equal intervals.

The first outer ring 4a has an external thread 4c formed on the outer peripheral surface thereof, while the second outer ring 4b having a large diameter cylinder and a small diameter cylinder connected coaxially has a female screw 4d formed on the inner circumference of the large diameter cylinder. doing. By screwing the male screw 4c into the female screw 4d, the first outer ring 4a is attached to the second outer ring 4b, thereby forming the outer ring assembly 4.

The first outer ring 4a and the second outer ring 4b have conical surfaces 4e and 4f formed on the inner periphery, respectively. When the first outer ring 4a is attached to the second outer ring 4b, the conical surfaces 4e and 4f are formed.
4f oppose each other to form a V-shaped raceway surface of the ball 3.

On the other hand, the inner race 1 also has a V
The track surface 1a is formed. This V-shaped raceway surface 1
a, 4e, and 4f have the function of restricting the movement of the ball 3 in the axial direction with respect to both wheels, and preventing the ball 3 from falling off the bearing 24. It should be noted that by setting the amount of screwing of the first outer ring 4a into the second outer ring 4b appropriately, it is possible to eliminate play that occurs between the two wheels and the ball.

FIG. 3 is a development view of the retainer 2 and is a view together with the ball 3. The retainer 2 is a resin molded product, and a plurality of U-shaped cutouts 2a corresponding to the balls 3 are opened in the axial direction, but the opening directions are alternately different in the adjacent cutouts 2a.

In actual assembly of the bearing 24,
After arranging the retainer 2 at the installation position with respect to the inner ring 1, the ball 3 is attached to the U-shaped notch 2 using a jig (not shown).
a and in the V-shaped raceway surface 1a. Furthermore,
The first outer ring 4a and the second outer ring 4b are fitted and fitted from both sides to complete the assembly.

Once the outer ring assembly 4 is assembled, the retainer 2 is held against the ball 3 by the U-shaped notch 2a, so that the retainer 2 does not fall off even if the bearing 24 is inclined. On the other hand, the notches 2a are alternately opened in the axial direction, so that when the retainer 2 is formed of resin, the two dies for forming the notches can be pulled out in both axial directions. Becomes

As described above, in the present embodiment, the bearing is a part of the pressing member of the motor. However, the present invention is not limited to this. The outer ring of the bearing may be integrated with the rotor or the stator of the motor. Further, the inner ring of the bearing may be integrated with the rotor or the stator of the motor. Also, the U-shaped notch does not need to alternately change direction, and it suffices if at least one of the cutouts faces one of the axial directions.

[0029]

As described above, according to the lens barrel having the ultrasonic motor of the present invention, the retainer has a plurality of notches for accommodating the balls, and at least one of the notches has The bearing is open in one axial direction and the remaining notch is open in the other axial direction, so the retainer can be formed by pulling out two molds in one direction, thereby reducing manufacturing costs. Can be done. Further, since the retainer holds the ball after assembling the bearing and at the same time holds the ball from the ball, the retainer does not fall off in the axial direction and is easy to handle.

[Brief description of the drawings]

FIG. 1 is a sectional view in the optical axis direction of a lens barrel provided with an ultrasonic motor according to an embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view of the bearing 24 according to the present embodiment.

FIG. 3 is a development view of the retainer 2 and is a view together with the ball 3;

FIG. 4 is a partially cutaway perspective view of a prior art bearing used in a lens barrel.

FIG. 5 is a partially cutaway perspective view of a prior art bearing used in a lens barrel.

FIG. 6 is a partially cutaway perspective view of a prior art bearing used in a lens barrel.

FIG. 7 is a partially cutaway perspective view of a prior art bearing used in a lens barrel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Inner ring 2 ... Retainer 3 ... Ball 4 ... Outer ring assembly 24 ... Bearing 50 ... Ultrasonic motor

Claims (5)

[Claims] 1. An ultrasonic motor comprising a stator and a rotor, and a bearing rotatably supporting the rotor with respect to the stator, wherein the bearing is provided between an outer ring, an inner ring, and both wheels. And a retainer for holding the ball, wherein the retainer forms a plurality of notches for accommodating the ball, and at least one of the notches is provided in the bearing. A lens barrel provided with an ultrasonic motor, wherein the lens barrel is open in one axial direction, and the remaining cutout is open in the other axial direction. 2. A pressing mechanism for pressing the stator and the rotor in a direction approaching each other, wherein the bearing supports a pressing force transmitted from the pressing mechanism. Item 2. A lens barrel provided with the ultrasonic motor according to Item 1. 3. The lens barrel according to claim 1, wherein the ultrasonic motor supplies power for driving a lens. 4. The ultrasonic motor according to claim 4, wherein an outer ring of the bearing is formed integrally with a rotor of the ultrasonic motor, and an inner ring of the bearing is formed integrally with a stator of the ultrasonic motor. Item 2. A lens barrel provided with the ultrasonic motor according to Item 1. 5. An ultrasonic motor according to claim 5, wherein an outer ring of said bearing is formed integrally with a stator of said ultrasonic motor, and an inner ring of said bearing is formed integrally with a rotor of said ultrasonic motor. Item 2. A lens barrel provided with the ultrasonic motor according to Item 1.