JPH0943476A - Lens driving mechanism for lens interchangeable camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a motor arranging space in a lens barrel and to miniaturize a camera as a whole by arranging a ring-like traveling wave type ultrasonic wave motor used as a driving source for driving a lens at a specified position. SOLUTION: A piezoelectric element 10 and a vibrating body 11 for the ultrasonic wave motor are arranged in a lens mount 13, the surface of the vibrating body 11 is aligned with the surface of the lens mount 13. Besides, a vibration absorber 12 is arranged on the rear side of the piezoelectric element 10 in a contact state. On the other hand, a moving body 14 is installed in a projecting lens barrel 20, and a gear 16 is fixed on the moving body 14. And a gear 15 engaged with the gear 16 is installed so as to be integrally rotated with a reduction gear 9. In such a constitution, by impressing a voltage on the piezoelectric element 10 so as to generate the vibration, the rotation of the moving body 14 is transmitted to a rotary barrel 7 through the gears 16, 15, 9 and 8. Thus, a lens group 5 is moved in an optical axis direction so as to perform a focusing operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens driving mechanism for a camera with interchangeable lenses, and more particularly to an arrangement structure of a ring-shaped traveling wave ultrasonic motor used as a driving source for driving the lens.

[0002]

2. Description of the Related Art Conventionally, a taking lens barrel of a single-lens reflex camera using a ring-shaped traveling wave type ultrasonic motor as a drive source for autofocus driving of a lens has been put into practical use. If the lens is driven inside the lens barrel by an ultrasonic motor in this way, the space for arranging the motor in the body is not required, and the body can be downsized. It will be limited by the motor. On the other hand, in the method in which the lens is driven by the motor in the body, the taking lens barrel does not become large, but the size reduction of the body is limited.

[0003]

As described above, conventionally,
There has been a problem that the miniaturization of the body or the taking lens barrel is limited by the arrangement of the motors, which limits the miniaturization of the camera as a whole. Therefore, the technical problem to be solved by the present invention is to reduce the size of the entire camera by arranging an ultrasonic motor as a driving source for driving the lens so that the body and the lens barrel do not become large. Is to

[0004]

In order to solve the above-mentioned technical problems, a lens driving mechanism of a lens interchangeable camera according to the present invention is constructed as follows. That is,
A ring-shaped traveling-wave ultrasonic motor used as a driving source for driving the lens is arranged concentrically with the lens barrel in the vicinity of a lens mount for mounting the taking lens barrel and the body. . In this configuration,
The ultrasonic motor may be used for driving the zoom of the lens, and "near the lens mount for mounting the taking lens barrel and the body" may include two ultrasonic motors in the axial direction. It is divided into two parts, one is placed in the camera body and the other is placed in the shooting lens barrel, and the whole ultrasonic motor is placed inside the body so that it is near the lens mount. I am using.

[0005]

In the above structure, since the ultrasonic motor is not entirely located in the lens barrel of the taking lens, the lens barrel can be shortened as compared with the case where the lens is driven in the lens barrel. Further, since the space for arranging the ultrasonic motor in the camera body is extremely smaller than the space for arranging the conventional drive motor, the body can be downsized rather than upsized. Therefore, the camera can be downsized as a whole. Further, by arranging other functional components in the space where the motor is conventionally provided, it is possible to make the camera multifunctional without increasing the size.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The lens driving mechanism of the interchangeable lens camera according to the first embodiment of the present invention shown in FIGS. 1 to 4 will be described in detail below.

FIG. 1 is an exploded perspective view showing a schematic structure of a ring-shaped traveling wave type ultrasonic motor used in this drive mechanism. In the figure, 14 is a moving body configured as a rotor, 11 is an elastic vibrating body used as a stator, and 10 is a piezoelectric element bonded to the vibrating body 11 (not shown, but separated in the circumferential direction). The electrodes are provided on the lower surface), and the vibrating body 11 and the moving body 14 are in pressure contact with each other. In this ultrasonic motor, a voltage is applied to the polarized electrodes on the lower surface of the piezoelectric element 10 to apply the voltage to the vibrating body 11.
By exciting the traveling wave in one direction on the surface of
The moving body 14 pressed against the surface rotates. Further, when the sign of the voltage is reversed, the moving body 14 rotates in the opposite direction.

FIG. 2 is a sectional view showing a lens driving mechanism using the ultrasonic motor as a driving source in a state in which a photographing lens barrel 20 is attached to a body 19, and a block diagram of a driving circuit of the ultrasonic motor. Shown in combination. In the figure, 1 is a sine wave oscillator, 2 and 3 are amplifiers, and 4 is a mobile unit. The mover 4 switches the frequency of the sine wave generated in the sine wave oscillator 1 to generate the piezoelectric element 10
The frequency of the voltage applied to is changed to change the rotation speed of the moving body 14.

Reference numeral 5 is a photographing lens group, 6 is a holding cylinder holding the lens group 5, and 7 is a rotary cylinder for transmitting a rotational force to the lens group 5 and the holding cylinder 6. Although not described in detail, when the rotary cylinder 7 rotates, the lens group 5 moves in the optical axis direction,
Focusing is performed on the subject. An internal gear 8 is formed at the rear end of the inner peripheral surface of the rotary cylinder 7, and a reduction gear 9 is arranged so as to mesh with the internal gear 8.

Next, the arrangement of ultrasonic motors in this camera will be described. Reference numeral 13 denotes a lens mount for mounting the taking lens barrel 20 on the camera body 19, the piezoelectric element 10 of the ultrasonic motor and the vibrating body 11 are arranged in the lens mount 13, and the surface of the vibrating body 11 is It is aligned with the surface of the lens mount 13. The vibration absorber 12 is arranged in contact with the back surface of the piezoelectric element 10. On the other hand, the moving body 14 is provided inside the taking lens barrel 20, and a gear 16 is fixed (or integrally formed) to the moving body 14. A gear 15 that meshes with the gear 16 is provided so as to rotate integrally with the reduction gear 9. When the photographing lens barrel 20 is viewed from the rear end side, the moving body 14 is exposed as shown in FIG. 3, and when the camera body 19 is viewed from the front, the vibrating body 11 is exposed as shown in FIG. There is.

In this configuration, when a voltage is applied to the piezoelectric element 10 to generate vibration, the rotation of the moving body 14 causes the gear 1 to rotate.
It is transmitted to the rotary cylinder 7 via 6, 15, 9, 8. Therefore, the lens group 5 moves in the optical axis direction and focusing is performed.

On the other hand, in this example, the constituent parts of the ultrasonic motor are divided into two parts, and the stator side (vibrator 11 and piezoelectric element 1
0) is arranged in the body 19, and the rotor side (moving body 14) is arranged in the lens barrel 20. Therefore, the lens barrel 20 can be shortened by the amount of the stators 11 and 10 of the ultrasonic motor, and the stators 11 and 10 can be accommodated in a small space in the lens mount 13 of the body 19, so that the size of the entire camera can be reduced. It will be possible.

Next, a second embodiment shown in FIGS. 5 to 7 will be described. In the second embodiment, the ultrasonic motor is divided between the vibrating body 11 and the piezoelectric element 10, and the vibrating body 11 and the moving body 14 are placed in the lens barrel 20 and the piezoelectric element 10 is used.
Are arranged in the body 19. The second embodiment has the same configuration as the first embodiment except for the arrangement of the ultrasonic motor, and the same reference numerals are given to the same parts, and therefore the details of the parts will be described. Detailed description is omitted.

As shown in FIG. 5, in this example, the piezoelectric element 1
0 is arranged so that its surface position is aligned with that of the lens mount 13, and when the lens barrel 20 is removed, the piezoelectric element 10 is exposed in the lens mount 13 as shown in FIG. In addition, the vibration absorber 12 is provided at the back of the piezoelectric element 10.
Is installed. On the other hand, the vibrating body 11 and the moving body 14 are built in the lens barrel 20, and when the lens barrel 20 is viewed from the mounting surface side, the vibrating body 11 is exposed.

A gear 16 is fixed to the moving body 14, and the gear 16 meshes with a gear 15 that rotates integrally with the reduction gear 9. Therefore, when the ultrasonic motor is rotated, its rotation is transmitted through the gears 16, 15, 9, 8 to the rotary cylinder 7
Therefore, the lens 5 can be driven for focusing. Also in this drive mechanism, the ultrasonic motor is divided into two parts, one on the body 19 side and the other on the lens barrel 20 side, so that the camera can be downsized as a whole as in the first embodiment described above. it can.

Next, a third embodiment shown in FIGS. 8 to 10 will be described. In this example, the ultrasonic motor is divided into two between the vibrating body 11 and the moving body 14, and the vibrating body 11 side is arranged in the body 19 and the moving body 14 side is arranged in the lens barrel 20. . Further, the configuration is the same as that of the above-described examples except for the arrangement portion of the ultrasonic motor and its peripheral portion, and thus detailed description thereof will be omitted.

The piezoelectric element 10 and the vibrating body 11 are arranged at positions on the inner diameter side of the lens mount 13, and the vibrating body 11 is exposed on the inner diameter side of the lens mount 13 when the lens barrel 20 is removed from the body 19. It has become. Further, a moving body 14 is arranged in the lens barrel 20 so as to come into pressure contact with the vibrating body 11 when the body barrel 20 is assembled to the body 19, and the moving body 14 includes a gear 15 and a moving body 14. A gear train 16 that transmits rotation is connected. Therefore, when the ultrasonic motor is started, the rotation of the moving body 14 is transmitted from the gear train 16 to the rotary cylinder 7 via the gears 15, 9, and 8, so that the focusing drive of the lens 5 can be performed as described above. . Further, also in the third embodiment, since the space for disposing the motor is small on both the lens barrel 20 side and the body 19 side, it is possible to downsize the entire camera.

Next, a fourth embodiment shown in FIGS. 11 to 13 will be described. In this embodiment, the entire ultrasonic motor is arranged inside the camera body 19. The piezoelectric element 10, the vibrating body 11, and the moving body 14 are arranged on the back surface of the lens mount 13, and the bracket 2
It is held at 1. An internal gear is formed on the inner peripheral surface of the moving body 14, and the bracket 21 holds a gear 18 that meshes with the internal gear of the moving body 14. This gear 18 is a coupler 1 protruding from the lens mount 13.
The coupler 17 is connected to the coupler receiver 22 when the lens barrel 20 is attached to the body 19. A gear 16 is connected to the coupler receiver 22, and the gear 16 meshes with a gear 15 that is integral with a reduction gear 9 that transmits rotation to the rotary cylinder 7.

In this embodiment, when the ultrasonic motor is started, its rotation is transmitted to the gears 16 and 15 via the coupler 17 and the coupler receiver 22 and further to the rotary cylinder 7 via the reduction gears 9 and 8. Therefore, focusing can be performed by moving the lens group 5. Moreover, since the ultrasonic motor can be housed in a small space near the lens mount 13, the camera can be downsized as a whole.

As described above, when the ring-shaped ultrasonic motor is arranged near the lens mount 13 as a driving source for driving the lens, the installation space in the camera is small and the motor in the lens barrel 20 is small. Since the arrangement space is reduced, the camera can be downsized as a whole.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a schematic configuration of a ring-shaped traveling-wave ultrasonic motor used in a lens driving mechanism of a camera according to the present invention.

FIG. 2 is a cross-sectional view showing the lens driving mechanism of the first embodiment with a taking lens barrel attached to a body, showing a block diagram of a driving circuit of an ultrasonic motor in combination.

FIG. 3 is a rear view of the taking lens barrel.

FIG. 4 is a front view of a camera body.

FIG. 5 is a cross-sectional view showing the lens driving mechanism of the second embodiment in a state where a taking lens barrel is attached to a body, and shows a block diagram of a driving circuit of an ultrasonic motor in combination.

FIG. 6 is a rear view of the taking lens barrel.

FIG. 7 is a front view of the camera body.

FIG. 8 is a sectional view showing a lens driving mechanism of a third embodiment in a state where a taking lens barrel is attached to a body, and shows a block diagram of a driving circuit of an ultrasonic motor in combination.

FIG. 9 is a rear view of the taking lens barrel.

FIG. 10 is a front view of the camera body.

FIG. 11 is a cross-sectional view showing a lens driving mechanism of a fourth embodiment in a state where a taking lens barrel is attached to a body, and shows a block diagram of a driving circuit of an ultrasonic motor in combination.

FIG. 12 is a rear view of the taking lens barrel.

FIG. 13 is a front view of the camera body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 sine wave transmitter 2, 3 amplifier 4 mover 5 photographing lens group 6 holding cylinder 7 rotating cylinder 8 internal gear 9 reduction gear 10 piezoelectric element 11 vibrating body 12 vibration absorber 13 lens mount 14 moving body 15, 16 gear 17 Coupler 18 Gear 19 Body 20 Photographic lens barrel 21 Bracket 22 Coupler receiver

Front Page Continuation (72) Inventor Hironori Kamishita 2-3-13 Azuchi-cho, Chuo-ku, Osaka-shi, Osaka Within Minolta Co., Ltd. (72) Inventor Katsuyuki Namba 2-chome, Azuchi-cho, Chuo-ku, Osaka-shi, Osaka 3-13 Osaka International Building Minolta Co., Ltd.

Claims (1)

[Claims] 1. A lens driving mechanism of a camera with interchangeable lenses, wherein a ring-shaped traveling wave type ultrasonic motor (10, 11, 14) used as a driving source for driving the lens is attached to a taking lens barrel (20). ) And a body (19) are mounted in the vicinity of a lens mount (13) concentric with the lens barrel (20).