JPH08234078A - Optical apparatus having ultrasonic motor - Google Patents

Abstract

PURPOSE: To make it possible to surely drive a lens with a simple construction by arranging the revolving shaft of an ultrasonic motor which is rotationally driven with respect to a rectilinearly movably held optical member so as to intersect this shaft approximately orthogonally with the moving direction of this optical member. CONSTITUTION: A stationary lens 14 is fixed in a lens barrel 12 and a moving barrel 16 moving a lens 15 for focusing is freely slidably fitted in the optical axis direction of the lens. This moving barrel 16 is added with a pin 11 which is fitted through a rectilinear guide groove 12b extending in the optical axis direction of the lens barrel 12 into the groove part 10a of a lever 10 for moving the lens. A motor shaft 3a revolves when a motor is driven by a motor control circuit 17. The lever 10 is then rotated around the motor shaft 3a. The pin 11 fitted into both of the groove part 10a of the lever 10 and the rectilinear guide groove 12b of the lens barrel 12 moves along the rectilinear guide groove 12a to move the moving barrel 16 in the optical axis direction. The lens 15 for focusing is thus moved in the optical axis direction and the state of the focus is made adjustable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device equipped with an ultrasonic motor.

[0002]

2. Description of the Related Art Motors which use ultrasonic vibrations generated in an elastic body by a piezoelectric element or the like as a driving force source, so-called ultrasonic motors, are roughly classified into an annular type and a disc type. In each of these, a progressive surface wave around the rotation center axis is generated in an annular or disk-shaped stator of a motor, and rotational output is taken out from a rotor that is in pressure contact with the stator.

[0003]

When these ultrasonic motors are built into the photographing lens structure of a camera and are used as a power source for focusing and zooming of the lens, the following is a method of supporting the motor. There was such a problem. An annular ultrasonic motor is disclosed in
As disclosed in 59-111609, by utilizing the fact that the motor is hollow, if the optical axis of the lens optical system and the central axis of the motor are arranged in the lens assembly,
It does not interfere with the optical path for shooting light. However, since the inner and outer diameters of the stator and the rotor must be supported, a radial space is required for the support.

On the other hand, since the disc type ultrasonic motor has a solid structure, it suffices to support the shaft center, and the above support can be easily achieved in a small space. However, the above arrangement which interferes with the optical path cannot be taken. Therefore, it is conceivable to arrange the optical axis of the lens optical system and the central axis of the motor in parallel in the lens structure. However, in this arrangement, compared to when using a conventional micromotor,
This is not preferable because the size of the entire lens structure is increased and a mechanism for transmitting driving force such as gears and helicoids is required.

The present invention solves these drawbacks, and provides a photographing lens structure for a camera which has an ultrasonic motor built-in, which can effectively use space and can reliably drive the lens with a simple structure. To aim.

[0006]

To achieve the above object, according to the present invention, an ultrasonic motor is rotatably driven with respect to an optical member held so as to be able to move straight, and the rotation axis of the motor is the optical member. Provided is an optical device arranged so as to be substantially orthogonal to the moving direction.

[0007]

2A and 2B show the structure of a disc type ultrasonic motor used in an embodiment of the present invention. Here, FIG. 2A is a side view of the ultrasonic motor, and FIG. 2B is a sectional view of the ultrasonic motor. 1
Is the casing of this motor. Inside the casing 1, a stator 2 and a rotor 3 are housed,
The protrusion 2a on the surface of the stator 2 and the friction material 4 adhered to the rotor 3 are in contact with each other in an annular shape. A piezoelectric ceramic element 5 is adhered to the back surface of the stator 2 and is in contact with the supporting projections 1a of the casing 1 in the shape of a ring. A compression spring 6, a washer 7, a nut 8, and a bearing 9 are provided on the right end of the shaft 3a of the rotor 3.
Therefore, when the nut 8 is tightened, the compression spring 6 is compressed between the casing 1 and the washer 7, so that an appropriate contact pressure can be applied to the stator 2 and the rotor 3. A lever 10 for moving the lens is fitted to the left end of the shaft 3a, and a pin 11 is fitted to the groove 10a at the tip thereof.

When a high frequency electric input (AC voltage) is applied to the piezoelectric ceramic element 5 by the motor control circuit shown in FIG. 1, a flexural vibration is generated in the piezoelectric ceramic element 5, and then the piezoelectric ceramic element 5 progresses around the central axis of the motor on the surface of the stator 2. A surface acoustic wave can be obtained. The vibration of the stator 2 has different amplitudes in the radial direction. The amplitude is maximum in the annular zone with the protrusion 2a and almost zero in the annular zone with the protrusion 1a. The output is taken out and supported by the radius of. Due to the friction of the friction material 4 that is in pressure contact with the protrusion 2a, the progressive surface wave around the central axis of the motor is converted into output torque of the motor. That is, the rotor 3 is rotated and the lens moving lever 10 is moved.
Rotates about the axis of the motor and moves a pin 11 (described later) fitted in the groove 10a at the tip thereof.

Next, referring to FIGS. 1A, 1B and 1C, an embodiment will be described in which a disk type ultrasonic motor is incorporated inside the photographing lens structure of a camera. Figure 1
(A) is a partial cross-sectional view of the photographic lens structure seen from the side,
FIG. 1B is a cross-sectional view of the taking lens structure taken along a plane perpendicular to the optical axis, and FIG. 1C is a cross-sectional view of the taking lens structure seen from above.

A lens barrel 12 having a lens mount portion 12a which can be attached to a mount of a camera (not shown) is covered with a casing 13 on the outside thereof. A fixed lens 14 is fixed inside the lens barrel 12, and a movable barrel 16 holding a focusing lens 15 is slidably fitted in the optical axis direction of the lens. A pin 11 is planted in the movable barrel 16, and a linear guide groove 12 extending in the optical axis direction of the lens barrel 12 is provided.
It is fitted into the groove 10a of the lever 10 for moving the lens through b.

When the motor is driven by the motor control circuit 17, the motor shaft 3a rotates. Then, the lever 10 is rotated around the motor shaft 3a. Groove portion 10a of lever 10 and straight guide groove 12b of lens barrel 12
The pin 11 fitted in both of them moves along the straight-ahead guide groove 12a and moves the movable barrel 16 in the optical axis direction. In this way, the focusing lens 15 moves in the optical axis direction, and the focus state can be adjusted.

As described above, in the present embodiment, the disc type ultrasonic motor is arranged so that its central axis is oriented in the direction orthogonal to the optical axis of the lens optical system, and direct focusing is performed by the tangential force of the motor rotation. The lens 15 is driven straight ahead to adjust the focus. Further, since the focusing lens 15 is driven straight ahead by the tangential force of the motor rotation to adjust the focus, the lens can be reliably driven with a simple structure without an additional mechanism such as a gear or a helicoid. .

[0013]

As described above, according to the present invention, the ultrasonic motor is arranged so that its rotation axis is oriented in the direction orthogonal to the moving direction of the optical member. The space of can be used effectively.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an embodiment in which a disc type ultrasonic motor is incorporated inside a photographing lens of a camera. FIG.
(A) is a partial cross-sectional view of the photographic lens structure seen from the side,
1B is a cross-sectional view of the taking lens structure taken along a plane perpendicular to the optical axis, and FIG. 1C is a cross-sectional view of the taking lens structure seen from above.

FIG. 2 is a diagram illustrating a structure of a disc type ultrasonic motor. 2A is a side view of the ultrasonic motor, FIG.
(B) is a cross-sectional view of the ultrasonic motor.

[Explanation of symbols for main parts]

 2 stator 3 rotor 4 friction material 5 piezoelectric ceramic element 6 compression spring 11 lens moving lever 12 lens barrel 12a straight guide groove

Claims (2)

[Claims] 1. An optical member, which is held so as to be able to move linearly, and an ultrasonic motor that is rotationally driven and that is arranged with its rotation axis oriented in a direction substantially orthogonal to the moving direction of the optical member. An optical device equipped with a characteristic ultrasonic motor. 2. The optical device provided with the ultrasonic motor according to claim 1, wherein the optical member is a focus adjusting member in the optical device.