JPH0847273A - Drive - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a drive device which eliminates the problems of the drive device using a stepping motor as a drive source. An electro-mechanical energy conversion element that vibrates by applying an electric signal, and a contact with the conversion element,
The conversion element is rotated by vibration, and has an output member having a threaded portion, and an abutting portion that abuts the threaded portion of the output member, and the contact portion is rotated by the rotation of the threaded portion. And a moving member that moves by moving in the axial direction of the output shaft. [Effect] The driving sound is low and the stopping accuracy is good.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device using an electro-mechanical energy conversion element that vibrates when an electric signal is applied.

[0002]

2. Description of the Related Art Conventionally, a focusing device or a focal length adjusting operation of a photographing lens of a video camera or the like is performed by using a driving device such as a motor and moving a part or all of the photographing lens in the optical axis direction. .

A detailed description will be given with reference to FIGS. 8 and 9. FIG. 8 is an exploded perspective view of a case where a stepping motor is mounted on a lens barrel of a video camera as the above-mentioned driving device to perform a focusing operation and a focal length adjusting operation. Reference numeral 61 is a focal length adjusting drive device using a stepping motor, and 62 is a focusing drive device using a stepping motor. The drive device 61 is a focal length adjusting lens holding member 63, and the drive device 62 is a focusing device. The lens holding members 64 are driven respectively.

Reference numeral 60 is a light quantity adjusting device, and 65, 66, 67 are fixed lens barrels, and the lens holding member 63 can be moved in the optical axis direction by guide bars 68a and 68b provided between the fixed lens barrels 65 and 67. Is supported and guided by the fixed lens barrels 66 and 6
The lens holding member 64 is supported and guided by the guide bars 68c and 68d provided between the lens holding member 64 and the guide bar 68.

The fixed lens barrel 66 is composed of four guide bars 6
8a, 68b, 68c, 68d are supported. 69a
And 70a are rack members each having a half-threaded female thread portion to be screwed with the respective lead screws (screw portions) 61a and 62a of the drive devices 61 and 62.
The spring members 69b and 70b are constantly pressed by the lead screws 61a and 62a.

Next, the structure of the drive devices 61 and 62 will be described in more detail. The structure is as shown in FIG.

In FIG. 10, reference numeral 71a is a permanent magnet, the outer peripheral surface of which is multi-pole magnetized. This permanent magnet 7
A lead screw 61a (62a) is fixed to 1a with an adhesive or the like to form an output shaft 71. 73, 7
Reference numeral 4 is a stator core having a plurality of pole teeth arranged so as to surround the permanent magnet 71a. 73, 7
4 is a coil for generating magnetic poles in the portions 73a, 73c, 74a, 74c. Further, 73e and 74e are stator cases for accommodating a stator core and a coil made of metal, and 75 is a lead screw 61a.
(62a) is a bearing support member having bearings 75a and 75b for supporting (62a), and 77 is a lead screw 61a (62
It is an urging spring that urges a) in the axial direction to prevent backlash.

The drive device shown in FIG. 10 uses a two-phase type PM stepping motor as a drive source.
The phase on the bearing side is the A phase and the phase on the biasing spring side is the B phase. For example, the A phase includes a status core 73a, a status core 73c, a coil 73b, a bobbin 73d around which the coil is wound, and a stator case 73e.

Further, each of the status cores 73a and 73c is formed with a plurality of pole teeth, and the respective status cores are arranged so as to interlock with each other so that the pole teeth are meshed with each other. Also,
The B phase is also composed of the same parts, and the respective parts are arranged in the same manner.

Next, regarding the positional relationship between the A phase and the B phase, the teeth are arranged so that the teeth form a predetermined phase with each other.
There are notches in the stator cases 73e and 74e,
By fitting the protrusions provided on the status cores 73c and 74a, respectively, a predetermined phase relationship is established.

Further, a plate made of a non-magnetic member is interposed between the stator cases 73e and 74e so that the magnetic paths of the respective phases do not influence each other.

[0012]

However, in the above-mentioned stepping motor, the output shaft makes a step-like movement during driving, so that vibration and noise are generated. In particular, if the frequency of the input pulse rate to the step motor synchronizes with the natural frequency of the output shaft and the members that interlock with it and causes a resonance phenomenon, products such as video cameras will lose their product quality. I will end up.

Further, in the stepping motor, since the stator is arranged so as to surround almost the entire circumference of the permanent magnet as described above, the motor main body is made larger in the cylindrical shape and the motor can be arranged accordingly. It requires some innovation in shape and arrangement.

Further, when the stepping motor is switched from the energized state to the non-energized state, the stop position may change, and there is a problem in terms of stopping accuracy.

[0015]

The present invention relates to an electro-mechanical energy conversion element which vibrates by applying an electric signal, and an element which comes into contact with the conversion element and is rotated by the vibration of the conversion element. An output member having a screw portion and an abutting portion that abuts the screw portion of the output member, and the contact portion moves by moving in the axial direction of the output shaft as the screw portion rotates. And a driving device including a moving member that moves.

Further, the conversion element is characterized by a driving device for rotating the output member by causing an elliptical motion of the contact portion due to extension vibration and bending vibration.

[0017]

【Example】

(First Embodiment) The present invention will be described below with reference to the illustrated embodiment.

FIG. 1 is an exploded perspective view of the video camera as a first embodiment assembled in a lens barrel to perform a focusing operation and a focal length adjusting operation. The same reference numerals are given and the description thereof is omitted. 2 and 3 are enlarged views of a portion that best represents the features of the present invention in FIG. 1, FIG. 2 is an exploded perspective view, and FIG. 3 is a front view when seen from the optical axis direction. Furthermore, FIG.
FIG. 5 is a diagram showing only a portion of the driving device of this embodiment. In the figure, 101 is a lead screw (screw part)
An output shaft 101a is provided, and a cylindrical power transmission unit 102 is integrally formed with the output shaft 101 or fixed by an adhesive or the like. Reference numeral 103 denotes a perforated disk-shaped piezoelectric vibrator (electro-mechanical energy conversion element) that generates stretching vibration and bending vibration by applying a high-frequency voltage as an electric signal. Two electrode layers are provided.

Reference numeral 104 is a support member having a D-cut portion for supporting the piezoelectric vibrator 103 on its inner circumference and for stopping the rotation of the piezoelectric vibrator 103 so as to have a predetermined positional relationship with the power transmission portion 102. Reference numeral 105 is an elastic member such as a leaf spring that supports the support member 104 and presses the piezoelectric vibrator 103 against the power transmission unit 102 with a predetermined pressure.
The bearings of the output shaft 101 and the support member 104 are not shown.

Next, the operating principle of the above-mentioned driving device will be described with reference to FIGS. 6 (A) and 6 (B). The perforated disk-shaped piezoelectric vibrator is deformed as shown in FIGS. 6A and 6B when its inner circumference is fixed and a high frequency voltage is applied. Therefore, as shown in FIGS. 6 (A) and 6 (B), by applying a high frequency voltage orthogonal to each other (90 ° phase difference) simultaneously to the two electrode layers of the vibrator, it is shown in FIG. Such an elliptic motion can be generated. That is,
The displacement of the point P on the outer circumference can be expressed as follows.

P = Px coswt + Py sinwt where Px and Py are displacements at the point P.

As described above, the piezoelectric vibrator 103 causes an elliptical motion on the outer circumference of the piezoelectric vibrator 103 as shown in FIG. 4, so that the vibrator 103 is pressed against the power transmission portion 102 provided on the output shaft 101 by a predetermined amount. The output shaft 101 makes a rotary motion by being pressed into contact with.

Next, the case where the above-mentioned driving device is applied to an optical device will be described. FIG. 3 is a configuration diagram when the optical device is viewed from the optical axis direction, and FIG. 2 is an exploded perspective view of the optical device. In the figure, the same reference numerals are assigned to the parts described above.

101 is an output shaft having a lead screw 101a, and 102 is integrally formed with the output shaft 101,
Alternatively, it is a cylindrical power transmission unit fixed integrally by an adhesive or the like. Reference numeral 103 denotes a perforated disk-shaped piezoelectric vibrator that generates elliptic motion on its outer peripheral surface by applying a high-frequency voltage with a 90 ° phase shift, and two electrode layers are provided on its surface by vapor deposition or the like. . Reference numeral 104 is fixedly supported by the inner diameter of the piezoelectric vibrator 103, and the piezoelectric vibrator 1
Reference numeral 03 is a support member having a D cut portion for preventing rotation of the piezoelectric vibrator 103 so as to have a predetermined positional relationship with the power transmission portion 102. Reference numeral 105 is an elastic member that supports the support member 104 and press-contacts the piezoelectric vibrator 103 to the power transmission unit 102. Reference numerals 106a and 106b denote storage members for storing the piezoelectric vibrator 103, the support member 104, and the elastic member 105, and the member 106a includes the support member 104.
There is a D-cut hole that is in a fitting or press-fitting relationship with the D-cut provided in.

Reference numeral 303 is a holding member for holding the lens.

Reference numerals 308a and 308b denote guide bars that allow the lens holding frame 303 to move only in the optical axis direction. 309 is a lead screw 101a of the output shaft 101.
A rack member (abutting member) having a female screw portion (abutting portion) of a half-shape that is screwed with, and is engaged with an engaging portion 303a provided on the lens holding frame 303 to be integrated with the lens holding frame 303. In addition, the spring member (Fig. 1
69b, 70b) are constantly pressed against the output shaft 101.

The operation of the optical apparatus thus configured will be described. As described above, the piezoelectric vibrator 103 has 9
When a high-frequency voltage having a phase difference of 0 ° is applied, the piezoelectric vibrator 103 causes an elliptical motion in a portion in contact with the power transmission member 102. By this elliptical movement, the power transmission member 102
That is, the output shaft 101, which is integrated with this, starts rotating motion. Further, with the rotation of the output shaft 101, the rack member 309 screwed with the lead screw 101a of the output shaft 101 makes a linear motion in a direction parallel to the optical axis, and finally the lens holding frame 303 is moved in the optical axis direction. Will be moved to.

Further, as shown in FIG. 4, by changing the diameter φD ₁ of the power transmission member 102 or the diameter φD ₂ of the output shaft 101, it is possible to easily change the rotational speed or the rotational force of the output shaft 101. it can.

(Second Embodiment) In the first embodiment, the output shaft is rotated by using one piezoelectric vibrator, but it goes without saying that a plurality of piezoelectric vibrators may be provided.

In the second embodiment shown in FIG. 7, two piezoelectric vibrators are arranged in a fan shape. The advantage of this embodiment is that since two piezoelectric vibrators are used, there is a margin in torque accordingly. Therefore, it is possible to reduce the size of the piezoelectric element by the amount of margin, and it is possible to downsize the device to which the drive device is attached.

The principle of operation is the same as that of the first embodiment and will not be described.

[0032]

As described above, according to the present invention,
Since the vibrating electro-mechanical energy conversion element is used as the driving source, a quiet driving device with less driving sound can be realized. Moreover, at the time of stop, it is the same as mechanically locking the output member, and the stop position accuracy of the moving member can be improved.

Further, unlike the stepping motor, the power generation part does not need to surround almost the entire circumference of the output member, so that the size of the device can be reduced and the degree of freedom in designing the device can be increased.

Further, if the diameter of the conversion element and the diameter of the contact portion of the output member are properly selected, a desired rotation speed and rotation force can be easily obtained.

Further, since the output member is provided with the screw portion, the rotation amount of the output member and the movement amount in the axial direction have a linear relationship, and the driven object can be easily controlled.

[Brief description of drawings]

FIG. 1 is an exploded perspective view when a drive device as a first embodiment of the present invention is incorporated in a video lens.

FIG. 2 is an exploded perspective view best showing the features of the first embodiment of the present invention.

FIG. 3 is a front view of FIG. 2 viewed from the optical axis direction.

FIG. 4 is a diagram showing a main part of a driving device according to a first embodiment of the present invention.

5 is a side view of FIG.

FIG. 6 is a diagram showing a driving principle of the present invention.

FIG. 7 is a configuration diagram of a drive device according to a second embodiment of the present invention.

FIG. 8 is an exploded perspective view when a conventional stepping motor is incorporated in a video lens.

9 is a rear view of the assembled state of FIG.

FIG. 10 is a configuration diagram of a conventional stepping motor.

[Explanation of symbols]

 101 Output Shaft with Lead Screw 103 Piezoelectric Vibrator 104 Support Member 105 Pressure Contact Member 106 Storage Member 303 Lens Holding Member 309 Rack

Claims (2)

[Claims] 1. An electro-mechanical energy conversion element that vibrates when an electric signal is applied, and an output member that comes into contact with the conversion element and is rotated by the vibration of the conversion element, the output member having a screw portion. A moving member that has a contact portion that contacts the screw portion of the output member, and the contact portion moves by moving in the axial direction of the output shaft as the screw portion rotates. Characteristic drive device. 2. The drive unit according to claim 1, wherein the conversion element rotates the output member by causing an elliptical movement of the contact portion due to extension vibration and bending vibration.