JPH0749442A - Driving device using frictionally anisotropic material - Google Patents

Abstract

PURPOSE:To provide a driving device formed from a frictional anisotropic material in which the frictional coefficient between a driving member and a driven member is differed in positive and reversed vibrating directions of the driving member. CONSTITUTION:A driving member 12 consisting of a frictional anisotropic material is cut from a fiber-contained material in which a carbon fiber (f) is axially inclined, and electro polished to slightly expose the head part of the fiber (f) to the surface. The upper half of a driven member 13 makes frictional contact with the driving member 12, and the lower half is gently fitted to the driving member 12. When a sine wave alternate current is applied to a piezoelectric element 14, it is contractively and expansively displaced, and a driving shaft 11 fixed and connected thereto is also axially vibrated. In the arrowed directional (b) movement of the driving shaft 11, the arrowed directional (b) frictional resistance with the driven member 13 is small, and the arrowed directional (c) frictional resistance is large because the exposing direction of the fiber (f) in the driving member 12 is the arrowed direction (b), so that the driven member 13 is moved in an arrowed direction P together with the driving member 12, but in the arrowed directional (b) movement of the driving shaft 11, the driven member 13 is stayed in the position by the inertial force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device, and more particularly to a driving device using a friction anisotropic material suitable for driving a member constituting a camera or other precision equipment.

[0002]

2. Description of the Related Art A driving device using a piezoelectric element has been proposed for driving a camera and other members constituting precision equipment (Japanese Patent Laid-Open No. 4-69070 and Japanese Patent Laid-Open No. 63-110).
74 publication).

FIG. 7 shows an example thereof, which is applied to driving a zoom lens mounted on a camera, and a lens barrel 7 of the lens.
The sliding fitting portions 72a and 72b of the support body 72 that supports the sliding member 1 are slidably fitted to the drive shaft 73. Also, the drive shaft 7
3 is axially slidably supported by supporting portions 75 and 76 of the frame 77, and a piezoelectric element 78 that is displaced in the thickness direction is arranged at the axial end of the drive shaft 73. Both ends are fixed to the frame 77 and the drive shaft 73, respectively.

When a pulse voltage composed of a gentle rising portion and a rapid falling portion following it as shown in FIG. 8 is applied to the piezoelectric element 78, the piezoelectric element 78 is gently moved at the gentle rising portion of the pulse voltage. Since the expansion displacement occurs in the thickness direction, the drive shaft 73 gently moves in the axial direction in the direction indicated by the arrow a. Along with this, the support body 7 supported by the sliding fitting portions 72a and 72b with respect to the drive shaft 73.
2 is also coupled to the drive shaft 73 by the frictional force of the sliding fitting portions 72a and 72b, and therefore moves in the direction of arrow a, and the lens barrel 71 moves in the direction indicated by arrow a.

On the other hand, at the rapid falling portion of the pulse voltage, the piezoelectric element 78 rapidly contracts in the thickness direction, so that the drive shaft 73 moves axially in the direction opposite to the arrow a. At this time, the sliding fitting portion 72a on the drive shaft 73,
Since the support body 72 supported by 72b overcomes the frictional resistance force of the sliding fitting portions 72a and 72b by its inertial force and stays in that position, the lens barrel 71 does not move.

The pulse having the above waveform is continuously applied to the piezoelectric element 78.
, The lens barrel 71 can be continuously moved in the direction indicated by the arrow a. Lens barrel 7
The movement of 1 in the direction opposite to the arrow a can be achieved by applying to the piezoelectric element 78 a pulse voltage having a waveform having a rapid rising portion and a gentle falling portion following the rising portion.

[0007]

By the way, in the driving device using the piezoelectric element as described above, the coupling force due to the friction between the driving shaft coupled to the piezoelectric element and the driven member and the inertia of the driven member. Since force, i.e., mass is used, if sufficient coupling force due to friction cannot be secured between the drive shaft and the driven member, for example, a configuration in which a lubricant enters between the drive shaft and the driven member, Due to the relationship with other members, sufficient driving force cannot be obtained when the surface of the driven member has to be mirror-finished.

Also, when the driven member is a lightweight member,
The inertial force of the driven member cannot be fully utilized, and as a result, the driven member cannot be moved.

Further, when switching the driving direction of the driven member, as described above, it is necessary to switch the waveform of the pulse voltage applied to the piezoelectric element, which complicates the configuration of the pulse oscillator. The present invention is intended to solve the above problems.

[0010]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems, and provides a driving device including a driving member that vibrates in the axial direction and a driven member that makes frictional contact with the driving member. The driving member is characterized by being made of a friction anisotropic material in which a friction coefficient between the driving member and the driven member differs in a positive direction and a reverse direction of a vibration direction of the driving member.

[0011]

The driving member that vibrates in the axial direction and the driven member that makes frictional contact with the driving member are made of a friction anisotropic material whose friction coefficient differs between the positive direction and the reverse direction of the vibration direction of the driving member. Therefore, the driven member can be driven in the predetermined direction only by applying a sinusoidal alternating current to the piezoelectric element and vibrating the driving member.

[0012]

Embodiments of the present invention will be described below.

First, the friction anisotropic material will be described.
Friction anisotropic material is a material whose surface friction coefficient differs depending on the direction.Here, the direction of the fiber material is specified from the composite material manufactured by mixing the base material with the fiber material in a fixed direction. It is cut out so as to be inclined with respect to the direction.

The method for producing the friction anisotropic material will be described below. As the base material, a metal material such as an aluminum alloy, a copper alloy, an iron alloy, a thermosetting synthetic resin, a thermoplastic synthetic resin, or an appropriate material such as ceramics can be used. Further, as the fiber material, various fibers such as carbon fiber, alumina fiber, glass fiber, aramid fiber, polyarylate fiber, etc. can be used. Select a material that does not exist.

Next, an example of a method for producing a friction anisotropic material using an aluminum alloy as a base material and carbon fiber as a fiber material will be described with reference to FIG.

In FIG. 1, 1 is a melting tank, 2 is a carbon fiber supply section, 3 is a rolling roll, 4 is a cutter, 5, 6,
Reference numerals 7 and 8 denote guide rolls. First, aluminum alloy A
A fiber bundle in which a large number of carbon fibers f are arranged in parallel is supplied from one end of the melting tank 1 in which L is melted, and the aluminum alloy AL is adhered to the surface of the fiber by making it dive in the melting tank.
A sheet-shaped aluminum alloy containing this fiber bundle is rolled by a rolling roll 3 and cut by a cutter-4 to produce an aluminum sheet S.

Next, as shown in FIG. 2, carbon fiber f
The aluminum sheets S are laminated in the same direction, and pressed in a state of being heated to around the melting temperature of the aluminum alloy to form blocks B.

Next, the block B shown in FIG. 2 is cut at an angle α with respect to the direction of the carbon fiber f, and is cut, and this is electrolytically polished to form an aluminum alloy A near the surface.
When L is eluted, as shown in FIG. 3, a rod-shaped friction anisotropic material T in which the head of the carbon fiber f is slightly exposed can be obtained. The cross section is arranged in an arbitrary shape such as a square or a circle according to the configuration of the driving device.

The angle of the carbon fiber f with respect to the axial direction of the material T is changed by selecting the angle α for cutting the friction anisotropic material T from the block B, and the friction coefficient is selected to a desired value. Can be adjusted. Further, although an aluminum alloy is used here, it is also possible to enhance the wear resistance by applying a surface treatment such as formation of an oxide film.

FIG. 3 is a cross-sectional view showing the structure of the rod-shaped friction anisotropic material T. Carbon fiber f slightly exposed from the surface.
Is inclined by an angle α with respect to the axial direction of the rod-shaped friction anisotropic material T, the arrow b direction and the opposite arrow c
The coefficient of friction differs from the direction. For this reason, when the member in frictional contact with the surface of the anisotropic friction material T moves in the direction of arrow b, it receives a small frictional resistance force, but when it moves in the direction of arrow c, it receives a large frictional resistance force. .

Next, a drive device using a friction anisotropic material will be described. 4, 5 and 6 are linear driving devices applicable to driving a zoom lens, etc., FIG. 4 is a perspective view showing the outline of the configuration, and FIGS. 5 and 6 are sectional views for explaining the operation.

In FIGS. 4, 5 and 6, 11 is a drive shaft, 12 is a drive member made of a friction anisotropic material coaxially fitted and fixed to the drive shaft 11, and 13 is a lens barrel of a zoom lens. The member to be driven is a driven member which is attached by an appropriate means. Hole 13a provided in driven member 13
Has an oval shape slightly longer in the vertical direction so that the upper half thereof comes into frictional contact with the drive member 12 and the lower half does not come into contact with the drive member 12, and is loosely fitted to the drive member 12.
Reference numeral 14 denotes a piezoelectric element that is displaced in the thickness direction, one end of which is fixed to the end of the drive shaft 11 and the other end of which is fixed to the gear 17. The driven member 13 is supported by the guide shaft 20 so as to be movable in the axial direction of the drive shaft 11, that is, the arrow P direction and the arrow Q direction, and not to rotate around the drive shaft 11.

A drive shaft 11 and a drive member 12 made of a friction anisotropic material are rotatably supported by bearings 15 and 16, and the shaft 1 is driven by a motor or other drive source (not shown).
By driving the gear 17 via the gear 18 and the gear 18, it is possible to rotate 180 ° via the piezoelectric element 14.

The drive member 12 made of a friction anisotropic material is
The block B manufactured by the above-described manufacturing method, which is cut into a circular cross section, is electropolished to slightly expose the head of the carbon fiber f on the surface.

Next, the operation of the driving device will be described. First,
When the driven member 13 is moved in the direction of arrow P (see FIG. 4), as shown in FIG. 5, the gear 17 is driven by the motor (not shown) via the gear 18, and the drive shaft is driven via the piezoelectric element 14. Carbon fiber f of the drive member 12 made of a friction anisotropic material that is coaxially fitted and fixed to the drive shaft 11 by rotating 11
The exposure direction of the head is set to face the direction of arrow b.

When a sinusoidal AC voltage is applied to the piezoelectric element 14, the piezoelectric element 14 expands and contracts in the thickness direction, and the piezoelectric element 1
The drive shaft 11 fixedly connected to the motor 4 also vibrates in the axial direction.
In the vibration of the drive shaft 11 in the axial direction, when the drive shaft 11 moves in the direction of arrow b (the extending direction of the piezoelectric element), the carbon fiber f of the drive member 12 is exposed in the direction of arrow b. Therefore, since the frictional resistance force between the driving member 12 and the driven member 13 in the arrow b direction is small and the frictional resistance force in the arrow c direction is large, the driven member 13 together with the driving member 12 is in the arrow P direction (see FIG. See).

As described above with reference to the structure of the driving device, the driven member 13 is in frictional contact with the driving member 12 in the upper half of the hole 13a, and the lower half of the hole 13a is in the driving member 1.
Not in contact with 2. The above-mentioned frictional resistance force between the driving member 12 and the driven member 13 refers to the frictional resistance force at this frictional contact portion. This point is the same in the following description.

When the drive shaft 11 moves in the direction of arrow c (the contraction direction of the piezoelectric element), the drive member 12 and the driven member 1 are moved.
Since the frictional resistance force with respect to 3 in the arrow b direction is small and the frictional resistance force in the arrow c direction is large, the driven member 13 remains at that position. Therefore, if the sinusoidal AC voltage is continuously applied to the piezoelectric element 14, the driven member 13 continues to move in the arrow P direction (see FIG. 4).

Next, the driven member 13 is moved in the direction of arrow Q (see FIG. 4).
6), the drive shaft 11 is rotated 180 ° from the position shown in FIG. 5 described above, and the carbon fiber f of the drive member 12 is exposed first. It is set so as to face the arrow d direction opposite to the direction shown in FIG.

When a sinusoidal AC voltage is applied to the piezoelectric element 14, the piezoelectric element 14 expands and contracts in the thickness direction, and the drive shaft 11
Also vibrates in the axial direction. In the axial vibration of the drive shaft 11, when the drive shaft 11 moves in the direction of arrow d (the contraction direction of the piezoelectric element), the carbon fiber f of the drive member 12 is exposed in the direction of arrow d. Therefore, since the frictional resistance force between the driving member 12 and the driven member 13 in the arrow d direction is small and the frictional resistance force in the arrow e direction is large, the driven member 13 together with the driving member 12 in the arrow Q direction (see FIG. See).

When the drive shaft 11 moves in the direction of arrow e (the extending direction of the piezoelectric element), the drive member 12 and the driven member 1
Since the frictional resistance force with respect to 3 in the direction of arrow d is small and the frictional resistance force in the direction of arrow e is large, the driven member 13 remains at that position. Therefore, when the sinusoidal AC voltage is continuously applied to the piezoelectric element 14, the driven member 13 continues to move in the arrow Q direction (see FIG. 4).

In the above embodiment, the driving member is made of a friction anisotropic material and the driven member is made of a usual material. Instead of this, the driven member or the contact surface portion of the driven member with the driving member is used. Can be driven in the same manner as described above even if is made of a friction anisotropic material and the driving member is made of a normal material.

Further, when both the driving member and the driven member are made of friction anisotropic material, the frictional friction resistance between the driving member and the driven member can be made particularly large.

Further, in the above embodiment, the driving member has a circular cross section. However, if the driving member has a rectangular cross section, the contact area with the driven member is increased and the frictional friction resistance is increased. be able to.

Further, the one using a metal material as the base material of the friction anisotropic material is suitable for a driving device used in a high load, durability, high temperature environment and the like. Further, the one using a synthetic resin material as the base material is suitable for a driving device which is required to be light in weight. The one using a ceramic material as the base material is suitable for a driving device which requires durability and dimensional accuracy.

[0036]

As described above, according to the present invention, in a drive device including a driving member that vibrates in the axial direction and a driven member that makes frictional contact with the driving member, the driving member and the driven member are Since the friction coefficient between the driven member and the driven member is different in the positive and reverse directions of the vibration direction of the driving member, frictional anisotropic material is applied, so that only sinusoidal alternating current is applied to the piezoelectric element to vibrate the driving member. The driven member can be driven in the predetermined direction.

Further, since it is only necessary to apply a sinusoidal alternating current to the piezoelectric element, there is no need for a pulse oscillator or the like which generates a voltage with a special waveform as in the conventional device.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of a method for producing a friction anisotropic material.

FIG. 2 is a cross-sectional view showing the structure of a block in the process of manufacturing a friction anisotropic material.

FIG. 3 is a cross-sectional view showing the structure of an anisotropic friction material.

FIG. 4 is a perspective view showing a schematic configuration of a linear drive device according to the present invention.

5 is a cross-sectional view explaining the operation of the linear drive device shown in FIG.

6 is a cross-sectional view explaining the operation of the linear drive device shown in FIG.

FIG. 7 is a perspective view showing an example of a conventional drive device using a piezoelectric element.

8 is a waveform diagram showing an example of a pulse voltage waveform applied to a piezoelectric element in the conventional driving device shown in FIG.

[Explanation of symbols]

 11 Drive Shaft 12 Drive Member Made of Friction Anisotropic Material 13 Driven Member 14 Piezoelectric Element 15, 16 Bearing T Rod-like Friction Anisotropic Material f Fiber Material

Claims (1)

[Claims] 1. A drive device comprising an axially vibrating drive member and a driven member frictionally contacting the drive member, wherein the drive member and the driven member are friction between the drive member and the driven member. A drive device using a friction anisotropic material, wherein the coefficient is made of a friction anisotropic material that is different in the positive direction and the reverse direction of the vibration direction of the driving member.