JPH07306351A - Lens barrel - Google Patents

Abstract

PURPOSE:To directly turn a lens moving cam ring with an ultrasonic motor having the center of a rotation at a different axis from an optical axis. CONSTITUTION:A cam ring 38 is fitted in the outer periphery of a motor pedestal 37 so as to have the center of the rotation at the same axis as the center of the rotation of the ultrasonic motor 36, so that an output pin 39 extended outward in the diameter direction from the output member 36c of the ultrasonic motor 36 is fitted in a fitting hole 38b from the inner diameter side of the cam ring 38 without backlash. Thus, the output member 36c and the cam ring 38 are integrated, and the driving force of the rotor 36b of the ultrasonic motor 36 is directly transmitted to the cam ring 38 without necessitating a reduction gear system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens driving device using an ultrasonic motor as a driving source for moving a lens barrel, particularly a camera lens or a video lens in the optical axis direction.

[0002]

2. Description of the Related Art Conventionally, in an ultrasonic motor which does not have a rotation axis as an optical axis as a driving source for driving a lens, the rotation of the ultrasonic motor is reduced by using a reduction gear, and a cam ring having the optical axis as the rotation center. The lens is moved in the optical axis direction by rotating the or helicoid, and a conventional example is shown in FIG.

Reference numeral 1 denotes a rear main body barrel which is connected to a camera main body (not shown) by a mount 1a portion. A rear lens barrel 2 holds the rear lens groups L ₅ and L ₆ and is fixed to the inner diameter of the rear main body lens barrel 1. Reference numeral 3 denotes a diaphragm device fixed to the rear main body barrel 1, 4 denotes a focal ring holding the afocal lens L ₄ , and 5 denotes a focal ring fixed to the rear main body barrel 1, 5 denotes a front main body barrel, and a rear main body barrel. It is fixed at 1. 6 is a cam ring,
The front body barrel 5 is fitted into the inner diameter of the front body barrel 5 to be rotatably held, and the flange portion 6a restricts movement in the optical axis direction. Reference numeral 9 denotes a second-group lens barrel that holds the second-group lens L _2, and is fitted to bars 7 and 8 that are fixed by the front fixed barrel 5 and the afocal ring 4 and extend in the optical axis direction. A roller 10 that is movably held on the second group lens barrel 9 is fitted to the cam of the cam ring 6. Reference numeral 11 denotes a third-group lens barrel holding a third-group lens L ₃ , and similarly to the second-group lens barrel 9, it is movably held by the bars 7 and 8 and fixed to the third-group lens barrel 11. Takoro 12
Is fitted to the cam of the cam ring 6. 13 is the first lens group L
₁ 1 group lens barrel holding a female helicoid portion 13
It is helicoidally coupled to the male helicoid portion 5a of the front main body barrel 5 at a.

An ultrasonic motor 14 for zooming is fixed to the rear main body barrel 1, and is connected to a reduction gear and an output gear 15 from a motor output gear 14a through a reduction gear (not shown). Reference numeral 16 denotes a zoom transmission ring connected to the output gear 15, which is fitted to a pin 17 fixed to the cam ring 6 to rotate the cam ring 6.
Communicate to. A focusing ultrasonic motor 18 is fixed to the rear main body barrel 1, and an output gear 18a is connected to a transmission gear 19 from a reduction gear (not shown). 20 is screw 2
The focus transmission ring is fixed to the first group lens barrel 13 by 1, and is rotated by an output gear 19a of the transmission gear 19.

In the above structure, when the ultrasonic motor 14 for zooming is rotated, the output gear 14a is rotated and is transmitted through the reduction gear, the zoom transmission ring 16 and the pin 17, and the zoom ring is rotated to fit on the cam of the zoom ring. The combined rollers 10 and 12 are moved by the cam in the optical axis direction, and the second group lens L ₂ held by the second group lens barrel 9 is moved in the optical axis direction.
The third group lens L ₃ held by the third group lens barrel 11 moves in the optical axis direction to perform zooming.

When the focusing ultrasonic motor 18 rotates, the output gear 18a moves to the reduction gear and the transmission gear 1
9, the focus transmission ring 20 is connected, and the first group lens barrel 1
By rotating 3 and the helicoid coupling, the first group lens barrel is extended, and the first group lens moves in the optical axis direction, whereby focus adjustment is performed.

It should be noted that the zoom ultrasonic motor 14 and the focus ultrasonic motor 18 have the same structure, and they are formed into a rod-like appearance and are combined with bending vibration excited with a phase difference of 90 °. By this, an elliptic motion is formed on the surface particles at one end of the vibrating body, and the rotor that pressurizes and contacts the one end of the vibrating body is frictionally driven to take out the rotational force. The gears 14a and 18a are connected.

[0008]

However, in the above-mentioned conventional example, since the driving force of the ultrasonic motor is transmitted by using the reduction gear, the backlash of the gear is large and it is difficult to control the minute movement. Is. Further, due to the reduction gear system, the cam ring or helicoid that rotates around the optical axis arranged on the outer or inner circumference side becomes large, which not only enlarges the lens barrel but also increases the load.

Further, since the reduction gear is used, it is necessary to rotate the motor at a very high speed in order to move the lens at a high speed, and it is difficult to drive the motor at a high speed because of the characteristics of the ultrasonic motor. As a result, there is a drawback that a gear sound is generated in the reduction gear unit.

[0010]

According to a first aspect of the present invention, there is provided a movable lens holding member movable along the optical axis direction, and an ultrasonic motor having a rotation center on a different axis from the optical axis. A lens having a rotation center coaxial with the rotation center of the ultrasonic motor, and a cam member directly coupled to the output member of the ultrasonic motor and cam-coupled to the movable lens holding member. It is in the lens barrel.

According to this structure, the rotation of the ultrasonic motor is directly transmitted to the cam member without the need for a reduction gear system to drive the movable lens holding member. Therefore, it is not necessary to provide a cam member for driving the cam on the outer periphery of the moving lens, and it is sufficient to provide it on the outer periphery of the ultrasonic motor having a diameter of, for example, a pencil, so that the cam member can be downsized and the lens barrel Of the ultrasonic motor, and the load on the ultrasonic motor becomes low.

Further, since the reduction gear system is unnecessary, the quietness of the ultrasonic motor can be effectively exhibited, and the noise of the camera can be reduced.

[0013]

FIG. 1 shows a first embodiment of the present invention.

Reference numeral 31 is a main body barrel, 32 is a first group lens barrel holding the first group lens L ₁₀ , and the first group lens barrel 32 is attached to the main body barrel 31 with screws 33. Reference numeral 35 denotes a second-group lens barrel holding the second-group lens L ₁₀ , and a bar 40 held by the main body barrel 31 and the first-group lens barrel 32,
It is held by 34 so as to be movable in the optical axis direction.

Reference numeral 36 is an ultrasonic motor, the basic construction of which is shown in FIG.
It is similar to that shown in FIG. 2 and is fixed to the motor pedestal 37 attached to the main body barrel 31. Reference numeral 38 denotes a cam ring fitted to the outer periphery of the motor pedestal 37 and rotatably attached. The cam ring fits with the ultrasonic motor output pin 39 and rotates integrally with the ultrasonic motor output pin. It is fitted with the convex portion 35 a of the group lens barrel 35. When the ultrasonic motor 36 rotates, the cam ring 38 is integrated with the output pin 39.
Rotates, and the second group lens barrel moves in the optical axis direction along the cam convex portion 38a.

In the ultrasonic motor of this embodiment, one end of a vibrator 36a, which is sandwiched and fixed between a plurality of vibrating elastic bodies by sandwiching a plurality of piezoelectric element plates and electrode plates, serves as a drive unit, and the rotor 3 is attached to the end face thereof.
6b is brought into pressure contact with the spring 36d, and the output member 36c is frictionally coupled to the rotor 36b.
The rotation of the rotor 36b is transmitted to the output member 36c.

Since the cam ring 38 is fitted on the outer periphery of the motor pedestal 37 so as to have a center of rotation coaxial with the center of rotation of the ultrasonic motor, the output member 36 of the ultrasonic motor 36.
The output pin 39 extending radially outward from c is the cam ring 38.
The output member 36c and the cam ring 38 are integrated by fitting the output member 36c into the fitting hole 38b from the inner diameter side without rattling, and the driving force of the rotor 36b of the ultrasonic motor is directly cam ring without requiring a reduction gear system. 38c will be transmitted.

FIG. 2 is a sectional view showing the second embodiment.

Reference numeral 41 is a main lens barrel, and 42 is a first-group lens L ₁₂
Is a first-group lens barrel that holds the lens, and is fixed to the main body barrel 41. Reference numeral 44 denotes a second group lens barrel that holds the second group lens L _13, and is held by bars 46 and 47 fixed by the main body barrel 41 and the first group lens barrel 42 so as to be movable in the optical axis direction. Reference numeral 48 denotes a third group lens barrel which holds the third group lens L _14, and is held by bars 46 and 47 so as to be movable in the optical axis direction. Reference numeral 50 denotes an ultrasonic motor fixed to a motor pedestal 51 fixed to the main body barrel 41. Reference numeral 52 denotes a cam ring fitted to the outer diameter of the motor pedestal 51 and rotatably held, fitted to the motor output pin 53, and fitted to the roller 49 fixed to the second group lens barrel 44 by the cam groove 52a. ing.

When the ultrasonic motor 50 rotates, the output pin 5
3, the output pin 53 rotates the cam ring 52. The rollers 45 and 49 move along the cam grooves 42a and 42b, and the second group lens barrel 44 and the third group lens barrel 48 move in the optical axis direction.

[0021]

According to the present invention, the rotation of the ultrasonic motor is directly transmitted to the cam member without driving the reduction gear system to drive the movable lens holding member. Therefore, it is not necessary to provide a cam member for driving the cam on the outer periphery of the moving lens, and it is sufficient to provide it on the outer periphery of the ultrasonic motor having a diameter of, for example, a pencil, so that the cam member can be downsized and the lens barrel Of the ultrasonic motor, and the load on the ultrasonic motor becomes low.

Further, since the reduction gear system is unnecessary, the quietness of the ultrasonic motor can be effectively exhibited, and the noise of the camera can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a lens barrel showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a lens barrel showing a second embodiment of the present invention.

FIG. 3 is a sectional view showing a conventional lens barrel.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rear body lens barrel 2 ... Rear group lens barrel 3 ... Diaphragm device 4 ... Afocal ring 5 ... Front body lens barrel 6 ... Cam ring 7,8 ... Bar 9 ... 2 group lens barrel 10 ... Roll 11 ... 3 Group lens barrel 12 ... Roller 13 ... First group lens barrel 14 ... Ultrasonic motor 15 ... Reduction gear 16 ... Zoom transmission ring 17 ... Pin 18 ... Ultrasonic motor 19 ... Transmission gear 20 ... Focus transmission ring 21 ... Screw L ₁ 1st group lens L ₂ 2nd group lens L ₃ 3rd group lens L ₄ ... Afocal lens L ₅ , L ₆ ... Rear group lens 31 ... Main lens barrel 32 ... 1st group lens barrel 33 ... Screw 34 ... Bar 35 ... 2 group lens barrel 36 ... ultrasonic motor 37 ... motor base 38 ... cam ring 39 ... output pin 40 ... bar L ₁₀ ... first lens L ₁₁ ... the second lens group 41 ... body barrel 42 ... first group lens barrel 43 ... screw 44 ... second group lens barrel 45 ... Rollers 46, 47 ... bar 48 ... third lens barrel 49 ... roller 50 ... ultrasonic motor 51 ... motor seat 52 ... cam ring 53 ... output pins L ₁₂ ... 1 group lens L ₁₃ ... 2 group lens L ₁₄ ... 3 group lens

Claims (1)

[Claims] 1. A movable lens holding member movable along the optical axis direction, an ultrasonic motor having a rotation center on a different axis from the optical axis, and a rotation center coaxial with the rotation center of the ultrasonic motor. And a cam member that is directly connected to the output member of the ultrasonic motor and that is cam-connected to the moving lens holding member.