JPH04185287A - Moving mechanism - Google Patents

Abstract

PURPOSE:To obtain a required moving displacement and reduce the size of a moving mechanism efficiently by a method wherein a voltage which is applied to an electro- mechanical energy transducer and gives extension and contraction to it is controlled so as to facilitate the movement of a moving unit. CONSTITUTION:If a voltage having a waveform given in the figure is applied to a piezoelectric device 3, the piezoelectric device 3 is suddenly extended to the direction of an arrow A in the sudden voltage rising part 10a of the voltage waveform and, accordingly, a vibration shaft 4 is also moved to the direction of the arrow A by a distance corresponding to the extension of the piezoelectric device 3. At that time, a moving unit 2 is hardly moved because it can not follow the movement of the vibration shaft 4 owing to an inertia given by its weight and a riction given by a first flat spring 5. Then, in the relatively slow voltage dropping part 10b of the voltage waveform, the piezoelectric device 3 is slowly contracted in accordance with the voltage drop. At that time, the vibration shaft 4 is also moved slowly to the direction of an arrow B and, as a friction given by a second flat spring 8 is larger than the friction given by the first flat spring 5, the moving unit 2 is moved to the direction of the arrow B. Therefor, the moving unit 2 can be moved to the direction of the arrow B.

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 DC motor,
BACKGROUND ART Conventionally, a method has been adopted in which rotational motion is generated by a rotational power source such as a stepping motor, and this is converted into linear motion by a mechanism such as a cam or a link. However, even if we try 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 essential, 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, motors use electromagnetism, no different from DC motors or stepping motors, and therefore the limits of miniaturization are determined theoretically. For these reasons, piezoelectric elements have attracted attention in order to miniaturize drive mechanisms. However, the very small amount of displacement of the piezoelectric element is a major obstacle when constructing a mechanism that moves larger than the amount of displacement.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide a moving mechanism that can obtain a desired amount of displacement and can be effectively miniaturized.

[Means for Solving the Problems] The configuration of the moving mechanism for realizing the object of the present invention includes an electric-mechanical energy conversion element whose one end in the expansion and contraction direction is in contact with a fixed body, and the electric-mechanical energy conversion element. a vibration shaft that is in contact with the other end in the expansion and contraction direction and is movable in the expansion and contraction direction of the electro-mechanical energy conversion element; a movable body that is movable in the expansion and contraction direction of the electric-mechanical energy conversion element; the fixed body; and the movable body. a first friction means that generates a friction force between the body and the body;
a second friction means that generates a friction force greater than the friction force generated by the first friction means between the movable body and the vibration shaft; and a stretching direction in which the electric-mechanical energy conversion element is applied. The present invention is characterized by comprising a voltage control circuit that controls the voltage with respect to the contraction direction so that the movable body can move.

[Function] The moving mechanism having the above-mentioned configuration uses an electric current composed of a piezoelectric element or the like.
For example, if a rapidly rising voltage is applied to a mechanical energy conversion element to extend the piezoelectric element, the vibration axis will move rapidly, and the moving body will stop at that position due to the rapid movement of the vibration axis. However, if the voltage applied when contracting the piezoelectric element is gradually lowered, the vibration axis will slowly return, and the movable body will move due to the frictional force with the second friction means.

[Example] The present invention will be described in detail below based on an example shown in the drawings.

FIG. 1 is a sectional view showing the first embodiment, and FIGS. 6 and 7 are diagrams showing waveforms of voltages applied to the piezoelectric element, respectively.

In the figure, 1 is a fixed part consisting of a frame, etc., and 4 is a fixed part 1.
A vibration shaft 2 which is supported and guided by and movable in the length direction is a moving body having a mass, and this movable body 2 is supported and guided by the vibration shaft 1 and the fixed part 1 while its movement direction is restricted.

3 is a piezoelectric element whose expansion/contraction direction (layering direction) is indicated by arrow A in the figure.
It is held by the fixed part 1 so as to coincide with the direction indicated by B, contacts the vibration shaft 4 in its expansion and contraction direction, and is bonded with an adhesive to form an integral body.

5 is a first leaf spring attached to the movable body 2, and the fixed part 1
is biased with a constant force to provide a frictional force between the fixed part 1 and the movable body 2.

8 is a second leaf spring attached to the movable body 2, and the vibration shaft 4
is biased with a constant force to apply frictional force between the movable body 2 and the vibration shaft 4. Furthermore, in order to prevent the movable body 2 from falling due to its own weight, the resultant frictional force of the leaf spring 5.8 is set to be larger than the gravitational force acting on the movable body 2. Further, the frictional force caused by the second leaf spring 8 is set to be larger than the frictional force caused by the first leaf spring 5. Here, the movable body 2 can be moved even without the first leaf spring 5, and by making the frictional force by the second leaf spring 8 larger than the gravity applied to the movable body 2, the self-weight of the movable body 2 Although falling can be prevented, if this is done, the frictional force caused by the spring 8 will become too large relative to the mass of the moving body 2, reducing the moving speed of the moving body 2. Therefore, in this embodiment, a plate spring is used. 5.8 gives a frictional force to the moving body 2.

10 and 11 are voltage waveforms applied to drive the piezoelectric element, and in FIG. 6 there is a rapid voltage rise part 10a and a relatively gentle voltage drop part 10b, and in FIG. It has a relatively gradual voltage rise section 11a and a rapid voltage drop section 11b.

12 is a voltage waveform adjustment circuit as a voltage control circuit;
The power source 13 and the piezoelectric element 3 are connected to each other by electric wires.

The operation of the moving mechanism configured in this way will be explained below.

For example, when the voltage waveform shown in FIG. 6 is applied to the piezoelectric element 3, the piezoelectric element 3 suddenly extends in the direction of the arrow A at the rapid voltage increase portion 10a, and accordingly, the vibration axis 4 also suddenly moves into the direction of the arrow A. The piezoelectric element 3 moves in the same direction as the piezoelectric element 3 extends. At this time, the movable body 2 is unable to follow the movement of the vibration shaft 4 due to inertia due to its own weight and frictional force due to the first leaf spring 5, and hardly moves, and the voltage drop is relatively small. In section 10b, the piezoelectric element slowly contracts as the voltage drops. At this time, the vibration shaft 4 also moves slowly in the direction of arrow B, and since the frictional force caused by the second leaf spring 8 is greater than the frictional force caused by the first leaf spring 5, the movable body 2 moves in the direction of arrow B. By repeating this series of operations, the moving body 2 moves in the direction of arrow B.

Furthermore, when a voltage waveform as shown in FIG. 7 is applied to the piezoelectric element 3, the piezoelectric element 3 slowly extends in the six directions of arrows in the figure as the voltage rises, and the vibration axis 4 also extends at a relatively gradual voltage rise portion 11a. Accordingly, it moves in the direction of arrow A. At this time, the movable body 2 moves in the direction A together with the vibration shaft 4 due to the frictional force of the second leaf spring 8, and at the rapid voltage drop portion 11b, the piezoelectric element 3 rapidly contracts, and the vibration shaft accordingly 4 also rapidly moves in the direction of arrow B by the amount that piezoelectric element 3 has shrunk.

At this time, the movable body 2 cannot follow the movement of the vibration shaft 4 due to inertia due to its own weight and frictional force due to the first leaf spring 5, and hardly moves B, that is, the voltage waveform shown in FIG. 7 is applied. By doing so, the moving body 2 moves in six directions.

In this embodiment, the piezoelectric element 3 and the vibration shaft 4 are fixed with adhesive so that the movement of the vibration shaft 4 follows the expansion and contraction of the piezoelectric element 3. However, as shown in FIG. A coil spring 6 is provided on the opposite side of the element, and the vibration shaft 4 and the piezoelectric element 3 are brought into contact with each other. The vibration axis 4 is prevented from separating from the piezoelectric element 3 by the expansion and contraction of the piezoelectric element 3.

Further, although the movable body 2 is restricted from rotating around the vibration shaft 4 by the fixed part 1, the same effect can be obtained by passing the movable body 1 through the guide shaft 7, as shown in FIG. can get.

FIG. 4 shows an embodiment in which the embodiments shown in FIGS. 2 and 4 described above are combined.

On the other hand, although the movable body 2 is supported through the vibrating shaft 4, it can also be supported and guided by the guide shaft 7 and the fixed part 1, as shown in FIG.

Further, the first leaf spring 5 is attached to the fixed portion 1 as shown in FIG.
The same effect can be obtained even if the second plate spring 8 is provided on the vibration shaft 4 side as shown in FIG.

Although the friction means generated in the movable body is a plate spring, it may also be an elastic member such as a coil spring or rubber.

In this way, each of the above-mentioned embodiments has an electrical connection such as a piezoelectric element.
Since the movement mechanism can be configured with a very simple structure using mechanical energy conversion elements, it is possible to provide a compact movement mechanism, and even though the amount of displacement of the piezoelectric element when voltage is applied is very small, it is possible to construct a movement mechanism with a very simple structure. The amount of movement can be obtained.

Furthermore, since the amount of displacement of the piezoelectric element is very small when voltage is applied, the moving body can be positioned with very high precision.

Further, since the resultant force of the frictional force by the leaf spring 5.8 is greater than the gravity applied to the movable body, the movable body will not fall under its own weight no matter what direction the movable body is set.

[Effects of the Invention] As explained above, the moving mechanism of the present invention can obtain a desired amount of movement displacement, and can effectively downsize the device.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a first embodiment of the moving mechanism according to the present invention, Fig. 2 is a schematic diagram showing a second embodiment, and Fig. 3 is a schematic diagram showing a third embodiment. Figure 4 is a schematic diagram showing the fourth embodiment, Figure 5 is a schematic diagram showing the fifth embodiment, Figures 6 and 7 are waveform diagrams, and Figures 8 and 9 are respectively Figure 3. , shows a modification of the embodiment of FIG. 1...Fixed part 2...Moving body 3...Piezoelectric element 4...Vibration shaft 5...Plate spring
6...Spring 7...Guide shaft 8...
- Leaf spring 10... Voltage waveform 10a... Voltage rising part 10b... Voltage falling part 11... Voltage waveform 11a... Voltage rising part 11b... Voltage falling part 12... Voltage waveform adjustment Circuit 13...power supply and others 4
Figure 1 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1 An electric-mechanical energy conversion element whose one end in the expansion and contraction direction is in contact with a fixed body, and a vibration that is in contact with the other end of the electric-mechanical energy conversion element in the expansion and contraction direction and is movable in the expansion and contraction direction of the electric-mechanical energy conversion element. a shaft, a movable body movable in the direction of expansion and contraction of the electro-mechanical energy conversion element, a first friction means for generating a frictional force between the fixed body and the movable body, and the movable body and the vibration. a second friction means that generates a friction force greater than the friction force generated by the first friction means between the shaft and the electric-mechanical energy conversion element; A moving mechanism comprising: a voltage control circuit for movably controlling the moving body.