JPS61208018A - Lens barrel by using surface wave motor - Google Patents

Abstract

PURPOSE:To simplify the assembly work of a stator and to attain centering at high accuracy by forming integrally a supporting part on the inner peripheral surface of an exciting part comprising some part of the stator through a vibration attenuating part. CONSTITUTION:The vibration attenuating part 11 is integrally formed on the inner peripheral surface 3a of the exciting part 3 comprising some part of the stator of a surface wave motor 1, and thereon the rigid supporting part 12 fitted in the outer periphery of the supporting part 8a of an outer tube 8 is integrally formed and put together as one assembly. And the outer tube 8 of the motor 1 is rotatably and slidably incorporated in the fixed tube 14 of the lens tube 13 of a camera 7. With the conduction to the motor 1, a moving lens frame 18 where a photographing lens L1 is incorporated is moved to execute focusing. Accordingly the assembly of the stator of the motor 1 is extremely simplified, and centering can be executed at high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a lens barrel using a surface wave motor for driving a photographic lens.

(Background of the Invention) As a conventional lens barrel using a surface wave motor, there is one disclosed in, for example, Japanese Patent Laid-Open No. 129841/1983. That is, this lens barrel incorporates a surface wave motor consisting of a vibrating ring (stator) vibrated by a piezoelectric element, a movable member (rotor) driven by a traveling wave generated in the stator, etc. The inner circumferential surface of the stator is supported by a blade case back plate, which serves as a fixed part of the lens barrel, via a vibration absorbing member.

However, in such a conventional lens barrel, when incorporating a surface wave motor, it is necessary to assemble the vibration absorbing member to the fixing part (blade case back plate) and then assemble the stator etc. Assembling the stator is complicated, and since the stator is supported by the fixed part via the vibration absorbing member, the accuracy of centering the stator with respect to the optical axis is poor, and strong impact may occur. There was a problem in that the position of the stator with respect to the optical axis may shift when the optical axis is applied.

(Object of the Invention) The present invention has been achieved by focusing on the problems of the conventional art, and it is easy to assemble the stator to the fixed part of the lens barrel, and it is easy to center the stator with respect to the optical axis. The objective is to provide a lens barrel that uses a highly accurate surface wave motor.

(Summary of the Invention) The gist of the present invention for achieving the above object is to provide a piezoelectric element, a stator excited by the piezoelectric element, and a rotor rotated by a surface wave generated in the stator. In a lens barrel in which a surface wave motor is built-in and a photographing lens is driven by the rotor, the stator includes an excitation part that is excited by the piezoelectric element to generate a surface wave, and a fixing part for fixing the excitation part to the lens barrel. A support part for supporting and fixing to the part, and a vibration damping part formed between the excitation part and the support part and damping vibrations of the excitation part are integrally formed. The invention consists in a lens barrel using a surface wave motor, which is characterized by:

In the lens barrel having the above configuration, the stator can be easily attached to the fixed part by simply attaching the supporting part, which is integrally formed with the stator, to the fixed part via the vibration damping part. can be supported reliably.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

Figures 1 to 4 show one embodiment of the present invention.
FIG. 5 is a perspective view of the surface wave motor. FIG. 3 is a longitudinal sectional view of the lens barrel in which the surface wave motor is incorporated.

As shown in FIGS. 1 and 2, the surface wave motor l constitutes a part of a stator that is excited by a piezoelectric element 2, and has a ring-shaped excitation part that is excited by the piezoelectric element 2 and generates a surface wave. 3, a ring-shaped rotor 4 rotated by a traveling wave generated in the excitation part 3, a buffer material 5, and a thin disk 6.
0 rotor 4, which is composed of a biasing member 7 that brings the excitation part 3 into frictional contact with the rotor 4 through the A ball bearing 10 is interposed between the rotor 4 and the outer cylinder 3 so that the rotor 4 can rotate smoothly with respect to the outer cylinder θ.

A vibration damping section 11 is integrally formed on the inner circumferential surface 3a of the excitation section 3, and a support section 8a of the outer tube 8 (fixing section of the lens barrel) is fitted onto the outer periphery of the vibration damping section 11. A rigid supporting portion 12 is integrally formed.

The vibration damping section 11 is for damping vibrations generated in the excitation section 3, and is formed in a shape having a spring constant such that the amplitude is sufficiently smaller than the amplitude of the excitation section 3.

The stator is constructed by integrally forming the excitation section 3, vibration damping section 11, and support section 12.

Engagement grooves 4b extending in the optical axis direction are formed at several locations on the inner peripheral surface of the cylindrical portion 4a of the rotor 4.

As mentioned above, the surface wave motor 1 is assembled as one assembly.

Next, the lens barrel 13 in which the surface wave motor 1 is incorporated will be explained based on FIGS. 3 and 4.

In addition, in FIGS. 3 and 4, the surface wave motor 1
is shown with its internal structure omitted.

As shown in FIG. 3, in the surface wave motor 1, the outer cylinder 8 is built into the lens barrel 13 so that the outer cylinder 8 can rotate and slide around the fixed cylinder 14 of the lens barrel 13. As shown in FIG.

The fixed cylinder 14 is fixed to the fixed cylinder 15.
mount) 1B is fixed. A fixed lens frame 17 holding a second optical system L2 is fixed to the fixed barrel 15. The helicoid screw 17a of the fixed lens frame 17 is engaged with the helicoid screw 18a of the movable lens frame 18. A focusing optical system (hereinafter referred to as a first optical system) Ll is held in this movable lens frame 1. Engagement projections 18b that fit into the engagement grooves 4b of the rotor 4 of the surface wave motor 1 are formed at several locations on the outer periphery of the movable lens frame 18, extending in the optical axis direction. A pin 18c is fixed to the movable lens frame 18. A stopper 19 that comes into contact with this bottle 18c and limits the rotation angle (the amount of movement in the optical axis direction) of the movable lens frame 18 is fixedly provided on the fixed barrel I4. Furthermore, a scale plate 20 having a display section 20a indicating the object distance is fixed to the rear end of the movable lens frame 18. The distance aiI scale of the display section 20a can be visually recognized through the window section 21 provided in the fixed cylinder 14.

A manual ring 22 is rotatably supported at the tip of the fixed cylinder 14.

A movable lens frame 18 is attached to the fixed barrel 14, and a surface wave motor 1 is connected to the movable lens frame 18.
There is an automatic mode (the mode shown in FIG. 3, hereinafter referred to as A mode) in which the moving lens frame 18 is driven by the rotational force of the manual ring 22, and a manual mode (in which the moving lens frame 18 is driven by the rotational force of the manual ring 22).
A switching mechanism 30 is provided for switching to the mode shown in FIG. 4 (hereinafter referred to as M mode).

The mode selector 31 of the switching mechanism 30 is formed in a ring shape, is slidably fitted to the outer periphery of the fixed cylinder 14, and can be switched between the A mode position and the M mode position. . The mode selector 31 is connected to the movable ring 33 by a screw 32 passing through the elongated hole 14a of the fixed cylinder 14. The movable ring 33 is disposed so as to be slidable in the optical axis direction between the fixed tube 014 and the outer cylinder 8, and between the movable ring 33 and the fixed tube 14, the movable ring
A spring member 34 is provided that biases the movable ring 33 in a direction in which the end surface of the movable ring 33 comes into contact with the end surface of the clamped portion 8b of the outer cylinder 8. An annular ring 35 and a spring member 3B are provided between the moving ring 33 and the outer cylinder 8. Further, the switching mechanism 30 is provided with a stopper 37 that locks the mode selector 31 at each position when the mode selector 31t is switched to the A mode position or the M mode position. This stopper 37 is constituted by a pin member 37a that penetrates the elongated hole 14a of the fixed barrel 14 and is slidable in the optical axis direction by a guide groove (not shown) of the fixed barrel 14.

This bottle member 37a is biased in the protruding direction by a spring member 37b, and has an engaging portion 37c formed at its tip. This engaging portion 37c is a fixed cylinder in the A mode position shown in FIG. 4, and in the M mode position shown in FIG. 4, it is fitted into a locking hole 14b formed at the end of the guide groove (not shown).

Note that when the mode selector 31 is switched to the A mode position, an automatic focusing control mechanism (not shown) is activated and power can be supplied to the surface wave motor 1, and the mode selector 31 is switched to the A mode position. When the surface wave motor 1 is switched to the M mode position, the control mechanism (not shown) becomes inactive and power cannot be supplied to the surface wave motor 1.

The spring members 34 and 38 prevent the outer barrel 8 from rotating relative to the fixed barrel 14 when the movable lens frame 1B is driven by the rotating force of the surface wave motor 1 in the A mode of FIG. The clamped portion 8b of the outer cylinder 8 is brought into pressure contact with the fixed cylinder 14. The biasing force of the spring member 36 is set so that the frictional force at the contact surface between the manual ring 22 and the outer barrel 9 in the M mode shown in FIG. 4 is greater than the driving force that drives the movable lens frame.

The operation will be explained below.

When the mode selector 31 is switched to the A mode position as shown in FIG.
The fixed cylinder 14 and the movable ring 33 are moved by the urging force of 4.36.
and the engaging portion 3 of the stopper 37
7c comes into contact with the inner circumferential surface of the fixed cylinder 14, whereby the mode selector 31 is locked in the A mode and the DO position. At this time, the control mechanism (not shown) is in an operating state, and when power is supplied to the surface wave motor 1 by the control mechanism (not shown), a traveling wave is generated in the excitation section 3, so that the rotor The rotor 4 rotates with respect to the fixed cylinder 14 and the outer cylinder 8, and the rotation of the rotor 4 is caused by the engagement between the engagement groove 4b and the engagement protrusion 18b. It is transmitted to the lens frame 18. The helicoid screw 18a of the movable lens frame 18 is the helicoid screw 1 of the fixed lens frame 17.
7a, the movable lens frame 18 moves in the optical axis direction while rotating, and focus alignment is achieved.

In addition, in the A mode position of FIG. 3, the outer cylinder 9 of the surface wave motor 1 is separated from the manual ring 22.

Next, in FIG. 3, when the mode selector 31 is slid forward (to the left in the figure) to the M mode position, the moving ring 3
3 slides in the same direction, the spring members 34.38 are compressed, the ring 35 and the outer cylinder 8.8 are displaced forward by the biasing force of the spring member 38, and the outer cylinder 9 is forced into the manual ring 22 by the spring. Pressed by the urging force of the member 36 (state shown in FIG. 4)
. When the mode selector 31 is switched to the M mode position in this way, the retaining portion 37c of the stopper 37
It fits into the locking hole 14b of the fixed cylinder 14 by the biasing force b, thereby locking the mode selector 31 at the M mode position. At this time, the control mechanism (not shown) is in an inactive state, and no power is supplied to the surface wave motor 1.

When the manual ring 22 is rotated in the state shown in FIG. The movement is the outer cylinder 3. Outer cylinder 8. Biasing member 7. Thin disk 6, M member 5. The vibration is transmitted to the movable lens frame 18 by the excitation unit 3 and the rotor 4 rotating together.

When the stopper 37 is pushed in in the M mode of FIG. 4 and the mode selector 31 is slid backward (to the right in the figure), the mode selector 31 is switched to the A mode position.

In the above embodiment, the rigid body support part 12 is supported by the support part 8a of the outer cylinder 8, but the rigid body support part 12 may be supported by a support part on the lens barrel 13 side, for example, the fixed cylinder 14. Needless to say, it may be configured.

Furthermore, in the above embodiment, if one of the rigid body support part 12 and the support part 8a of the outer cylinder 8 is provided with an engagement groove, and the other is provided with an engagement protrusion that engages with the engagement groove, the stator Even if a strong torque is applied to the stator, the stator will not rotate.

(Effects of the Invention) According to the lens barrel using the surface wave motor according to the present invention, the support part is integrally formed on the inner peripheral surface of the excitation part that constitutes a part of the stator via the vibration damping part. As a result, the work of assembling the stator to the lens barrel becomes easy, and the stator can be assembled by simply attaching the supporting part of the stator to the fixed part of the lens barrel, so that the stator can be easily assembled to the optical axis. The centering accuracy of the stator is improved, and since the stator is supported by the fixed part by the supporting part, there is no fear that the position of the stator with respect to the optical axis will shift when a strong impact is applied.

[Brief explanation of the drawing]

Figures 1 to 4 show one embodiment of the present invention.
This figure is a perspective view of the surface wave motor, FIG. 2 is an enlarged perspective view of the main part, and FIGS. 3 and 4 are longitudinal sectional views of the lens barrel. 1...Surface wave motor 2...Piezoelectric element 3...
Excitation part 3a...Inner peripheral surface 4...Rotor 8a...Supporting part of the outer cylinder (fixing part of the lens barrel) 11.
...Vibration damping part 12...Support part 13...Lens barrel Fig. 1 Fig. 2

Claims (1)

[Claims] A lens that includes a built-in surface wave motor having a piezoelectric element, a stator excited by the piezoelectric element, and a rotor rotated by surface waves generated in the stator, and a photographing lens is driven by the rotor. In the lens barrel, the stator includes an excitation part that is excited by the piezoelectric element to generate a surface wave, a support part for supporting and fixing the excitation part to a fixed part of the lens barrel, and a combination of the excitation part and the support part. 1. A lens barrel using a surface wave motor, characterized in that the lens barrel is configured by integrally forming a vibration damping part formed between the parts and damping the vibration of the excitation part.