JPH04193077A - Shifting mechanism - Google Patents

Abstract

PURPOSE:To get a small-sized shifting mechanism by making the combined friction force of a first friction means and the friction means of a second friction means larger than the gravity falling on a shifter. CONSTITUTION:A first leaf spring 5 is attached to a shifter 2 so as to energize an oscillating shaft 4 with constant spring force, whereby it gives friction force between the shifter 2 and the oscillating shaft 4. A second leaf spring 6 is attached to the shifter 2, and energizes the fixing part 1 with constant certain force, whereby it gives friction force between the shifter 2 and the fixing part 1. And to prevent the falling by dead weight of the shifter 2, combined frictional force of the first and second leaf springs 5 and 6 is set larger than the gravity falling on the shifter 2. Hereupon, by enabling the shifter 2 to be shifted even if the second leaf spring 6 doe not exist, and making the friction force by the first leaf spring 5 larger than the gravity falling on the shifter 2, the falling by dead weight of the shifter 2 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a moving mechanism that moves an object by expanding and contracting a piezoelectric element.

(Prior Art) Conventionally, in order to move an object in a straight line, a method of generating rotational motion using a rotary power source such as a DC motor or a stepping motor and converting this into a straight motion using a mechanism such as a cam or a link has been used. It was getting worse. However, even if an attempt is made to miniaturize the above mechanism, the size of the motor is determined by the required output torque, and a mechanism that converts rotational motion into linear motion is required, so there are significant restrictions on miniaturizing the entire mechanism. . Therefore, recently, various linear motors have been proposed.

[Problem to be solved by the invention] However, this linear motor is also largely based on a combination of magnetic force generated by electricity and permanent magnets.
In principle, it is a motor that uses electromagnetism, no different from a DC motor or a stepping motor, so
The limits of miniaturization are determined theoretically. For these reasons, piezoelectric elements have attracted attention in order to miniaturize drive mechanisms.

However, the fact that the amount of displacement of piezoelectric elements is extremely small is a major obstacle when constructing a mechanism that moves larger than the amount of displacement.

An object of the present invention is to solve the above problems and provide a compact moving mechanism.

To! Means for Solving IQ] The structure of the moving mechanism for realizing the purpose of the present invention is as follows: a pair of piezoelectric elements that are in contact with each other or face each other with a slight gap and whose other ends in the expansion and contraction direction are held by the fixed body; and a movable body that is held movably along the expansion and contraction direction of the piezoelectric elements. and a first friction means that generates a friction force between the vibration shaft and the moving body;
A second friction means that generates a smaller frictional force between the movable body and the fixed body than the first friction means, and a voltage waveform adjustment means that adjusts the output of the voltage source to the piezoelectric element. The present invention is characterized in that the resultant force of the friction force of the first friction means and the friction force of the second seven friction means is larger than the gravitational force applied to the movable body.

(Function) When the moving mechanism configured as described above applies minute vibrations to the vibration axis using one of the piezoelectric elements, the vibration axis is suddenly moved by applying a sudden displacement in the direction of extension of the piezoelectric element. , the moving body is held in that position by inertia, and as the piezoelectric element slowly returns to the contraction direction, the moving body also moves due to the frictional force of the friction means.By repeating this, the moving body is moved in a predetermined direction. Even if the movable body is directed in any direction, it will not become inoperable due to falling of its own weight.

〔Example〕

The present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 1 is a schematic diagram showing an embodiment of a moving mechanism according to the present invention.

1 is a fixed part, 2 is a movable body, and 3a and 3b are piezoelectric elements, which are held facing the fixed part 1 so that the stretching force (in the stacking direction) coincides with arrows A and B in the figure. Reference numeral 4 denotes a vibration axis, and both ends thereof are either in contact with each other in the direction of expansion and contraction of the piezoelectric elements 3a and 3b, or are opposite to the direction of expansion and contraction of the piezoelectric elements 3a and 3b with a slight gap therebetween. This gap is set smaller than the elongation of the piezoelectric element when voltage is applied. Further, the vibration shaft 4 is held by the fixed part 1 so as to be freely movable in the direction of the arrow A%B.

Reference numeral 7 denotes a guide shaft, which is fixed to the fixed part 1 and guides the movement of the moving body 2 in the axial direction while restricting rotation of the moving body 2 passing therethrough around the vibration shaft 4.

Reference numeral 5 denotes a first leaf spring, which is attached to the moving body 2 and is connected to the vibration shaft 4.
is biased with a constant spring force to apply frictional force between the moving body 2 and the vibration shaft 4.

6 is a second leaf spring, which is attached to the moving body 2 and fixed to the fixed KS.
By biasing l with a constant force, the moving body 2 and the fixed part 1
It provides a frictional force between the In order to prevent the movable body 2 from falling due to its own weight, the resultant force of the friction forces of the first and second leaf springs 5.6 is set to be larger than the gravitational force acting on the movable body 2.

Here, the second leaf spring 6 can at least move the movable body 2, and the frictional force by the first leaf spring 5 can be transferred to the movable body 2.
Although it is possible to prevent the movable body 2 from falling under its own weight by making the gravity force larger than the gravity applied to the movable body 2, by doing so, the frictional force exerted by the first leaf spring 5 becomes too large relative to the mass of the movable body 2, and the movable body Since it will reduce the movement speed of 2, the 1st
, a frictional force is applied to the movable body 2 by the second leaf spring 5.6.

12 is a voltage waveform adjustment circuit, which adjusts the voltage from the power supply 13 to the sixth
Rapid voltage rise portions 10a, l as shown in FIG.
The piezoelectric element 3a is converted into a waveform 10.11 having la.
3b, and piezoelectric elements 3a,
It has a selection circuit section that selectively applies the waveform alternately to the terminals 3b.

The moving mechanism configured in this way has a voltage waveform adjustment circuit 12.
For example, if the waveform 10 shown in FIG.
When the voltage is applied to a, the piezoelectric satin 3a becomes ! Stretch in the direction of the arrow in the diagram and swing accordingly! j @ 4 suddenly suddenly in the direction of the arrow? , (acceleration (city! rate).

At this time, the movable body 2 cannot follow the moving group of the vibration axis 1 due to inertia due to its own weight, and hardly moves. and,
As the voltage applied to the piezoelectric element 3a decreases, the piezoelectric element 3a contracts, and accordingly, the vibration shaft 4 returns to its original position due to the reaction force of the impact with the other piezoelectric element 3b. This sharpening moving body 2 has a vibration shaft 4
Since the frictional force of the leaf spring 5 with 5 < 1 between the two is larger than the frictional force of the second leaf spring 6, the vibration shaft 4 moves together with the second leaf spring 6. In other words, the moving body 2 moves in the direction of arrow B in the figure, albeit very slightly. Then, by repeating the above-described operation (period T), the moving body 2 moves in the B direction.

Conversely, by applying a voltage having the above waveform to the other pressure TLi element 3b, the movable body 2 moves in the opposite direction.

In the embodiment described above, the impact of the vibration shaft 4 is applied to the piezoelectric element located on the opposite side, and as shown in FIG. ! By forming step portions at both ends of the II shaft 4 and fitting these step portions into the fixing portion 1, it is possible to prevent the impact of the vibration shaft 4 from being applied to the pressure Tl element.

Furthermore, although the second leaf spring 6 is provided on the movable body, it may be provided on the fixed KSL side or both, as shown in FIG.

Furthermore, in the embodiment shown in FIG. 1, the first leaf spring 5 is provided on the moving body 2, but it may be provided on the vibration shaft 4 as shown in FIG. 4, or it may be provided on both. As shown in FIG. 5, the moving body 2 is passed through only the guide shaft 7 and shaken!
A frictional force may be applied between the movable body 2 and the vibration shaft 4 by the first leaf spring 5 provided at J+@4.

Note that each of the above embodiments uses a leaf spring as the friction means.
However, it may also be a coil spring, a single-layer member such as rubber, or a 6i1 stone.

〔Effect of the invention〕

As explained above, the invention uses piezoelectric elements to construct a moving mechanism with a very simple structure.Therefore, a compact moving mechanism is provided, and the amount of displacement of the piezoelectric element when voltage is applied is extremely large. Although it is small, it is a big move! This has the effect of increasing the amount of IJ.

Furthermore, since the amount of displacement of the piezoelectric element is very small when voltage is applied, it is possible to position the moving body with very high precision.

In particular, the moving mechanism of the invention can easily perform minute feeding of a movable object, and is therefore effective as a moving mechanism for an optical system and a feeding Ia mechanism for 611 and optical disk heads.

In addition, 'fs1. Since the resultant force of the frictional force by the friction means of %2 is larger than the m force applied to the moving body, the moving body has the effect of not falling by itself no matter how the moving direction is set.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view showing one embodiment of the moving mechanism according to the wooden invention, Figs. 2 to 5 are schematic sectional views showing other embodiments, and Figs. It is a figure which shows a waveform. 1...Fixed part 2...Moving body 3a, 3b
... Piezoelectric element 4 ... Vibration shaft 5 ... Leaf spring
6... Leaf spring 7... Guide @ 1o.
...Voltage waveform 11...Voltage waveform 12...Voltage waveform adjustment circuit 13...Power supply T...Period C
...Voltage (a and 4 other people Figure 1 Figure 5 Kugin- Kushu- □)

Claims (1)

[Claims] 1 A vibration shaft held movably in the axial direction with respect to a fixed body, and a vibration shaft that is in contact with both ends of the vibration shaft in the expansion and contraction direction or faces with a slight gap, and the other end in the expansion and contraction direction is connected to the fixed body. a pair of piezoelectric elements held in the piezoelectric element, a movable body held movably along the direction of expansion and contraction of the piezoelectric element, and friction means for generating a frictional force between the vibration shaft and the movable body; comprising a second friction means that generates a smaller friction force between the moving body and the fixed body than the first friction means, and a means for adjusting the output of the power applied to the piezoelectric element,
A moving mechanism characterized in that the resultant force of the frictional force of the first frictional means and the frictional force of the second frictional means is greater than the gravitational force applied to the moving body.