JPH0453193Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a micro-rotation device that utilizes piezoelectric changes.

In the past, most of this type of micro-rotating devices used so-called motors that used electromagnetic force, but in recent years, piezoelectric ceramics with large piezoelectric constants have been developed, and the application of these piezoelectric displacements to actuators has become popular in many fields. The greatest benefit of using the piezoelectric effect in a displacement element, which has been studied and put into practical use, is superior energy efficiency. In other words, in the case of electromagnetic force, the driving source is the action of the magnetic field generated by passing a current through a coil, so it has the drawback of energy losses such as hysteresis loss, eddy current loss, and loss due to Joule heat. This is because the piezoelectric type uses a reverse voltage effect via the voltage applied between the electrodes, so the energy loss is essentially smaller than when using the action of a magnetic field.

However, in the case of piezoelectric type, the amount of displacement generated is extremely small, which limits its applicable applications, but in recent years, in machines and ultra-precision processing equipment that handle laser beams, displacement is generated in micron or submicron units. Due to the increasing demand for displacement control, piezoelectric displacement elements have come into the spotlight in this field. However, although the piezoelectric displacement element can easily control linear displacement, in order to obtain rotational displacement, it is necessary to convert the linear displacement into rotational displacement by some mechanism.

In view of this, the present invention is a micro-rotary device that converts linear displacement of a piezoelectric displacement element into rotational displacement by laminating piezoelectric bodies with different polarization directions to obtain circumferential displacement. The main purpose is to propose.

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic cross-sectional perspective view showing an example of the present device. 1 indicates a shaft, and six piezoelectric laminated elements 2 are fixed radially around the center of this shaft 1.
As shown in FIG. 2, the piezoelectric laminated element 2 includes a first element 21 in which a plurality of piezoelectric ceramic plates 2a are laminated, which are polarized in the thickness direction, and a plurality of piezoelectric ceramic plates 2b, which are polarized in the direction perpendicular to the thickness direction, are laminated. The sliding type second element 22 is laminated and bonded. The first element 21 connects electric terminals E ₁ and E ₂ to the electrodes of each ceramic plate 2a as shown in FIG. 3, and applies a DC voltage V in a positive direction to E ₁ and in a negative direction to E ₂ . As a result, the voltage V is applied to each ceramic plate 2a in the polarization direction and the thickness increases, so that the overall thickness of the first element 21 is equal to the increase in thickness of each ceramic plate 2a, as shown in FIG. The height increases several times, resulting in a height displacement as shown by the broken line. Further, the second element 22, as shown in FIG.
Electric elements E ₁ and E ₂ are connected to the electrodes of each ceramic plate 2b,
By applying a DC voltage V in the positive direction to E ₁ and in the negative direction to E ₂ , voltage is applied in the polarization direction of each ceramic plate 2b and it is displaced in the lateral direction, so that the displacement of the entire second element 22 is As shown in FIG. 6, a sliding displacement occurs in the state shown by the broken line. Therefore, piezoelectric laminated element 2
By electrically connecting the elements 21 and 22 as shown in FIG. 2, a combined displacement in the height direction and the lateral direction can be obtained as shown in FIG.

Referring again to FIG. 1, the piezoelectric laminated element 2 formed radially has an elastic body 3, for example, hard rubber, attached to its active end, and is connected between the inner surface of the cylindrical body 4 and the minute gap 〓g〓.
is formed. The cylindrical body 4 is provided concentrically with the shaft 1. The elastic body 3 and the inner surface of the cylindrical body 4 have a coefficient of friction greater than a certain value. Note that 5 indicates a bearing.

Now, when the central axis 1 is fixed and the cylindrical body 4 is set in a freely rotatable state, by applying a rectangular wave pulse as shown in FIG. Since the end contacts the inner circumferential surface of the cylinder 4 and shifts to the right in the figure, the cylinder 4 rotates by a small angle Δφ in the direction of arrow A. When the voltage is reduced to zero, the active end of each element 2 separates from the cylindrical body 4 and returns to its original position. Thereafter, by applying a similar DC pulse signal, rotational driving can be performed intermittently.

FIG. 9 is a sectional view of essential parts showing another example of the device of the present invention. In this example, in order to prevent the cylindrical body 4 from rotating in the opposite direction when the voltage of each voltage laminated element 2 is zero when torque is generated in the opposite direction in the cylindrical body 4 in the structure of the example shown in FIG. Linear piezoelectric laminated elements 6 that are displaced only in the radial direction are provided alternately with synthetic piezoelectric laminated elements 2. Therefore, the first
As shown in Figure 0, by applying a short waveform pulse P ₁ to the composite element 2 and applying a pulse P ₂ whose phase is shifted by half a cycle from the pulse P ₂ to the linear element 6, the composite element 2 is During driving, the linear element 6 is not driven, so the free end of the linear element 6 does not contact the inner surface of the cylindrical body 4 and does not prevent rotation. At the same time that the voltage applied to the composite element 2 becomes zero, the linear element 6 contacts the inner surface of the cylindrical body 4 and the cylindrical body 4
brake. Therefore, even if external torque is applied to the cylindrical body 4, rotation in the opposite direction can be prevented.

FIG. 11 is a sectional view of essential parts showing still another example of the present invention. In this example, the cylindrical body 4 is configured to rotate in both forward and reverse directions. Reference numeral 7 denotes a reverse piezoelectric laminated element in which the combined displacement direction of the piezoelectric laminated element 2 is set in the opposite direction. The reverse direction elements 7 and the laminated elements 2 are arranged alternately. Therefore, the laminated element 2 and the reverse direction element 7
By driving the cylindrical body 4 with necessary pulses, the cylindrical body 4 can be minutely rotated in the forward and reverse directions. Furthermore, in this example, by further incorporating the linear element 6 shown in the example in FIG. 9, a forward/reverse minute rotation device having a braking function can be obtained.

In addition, in the above examples, the shaft 1 is fixed,
Although the cylindrical body 4 and its rotating structure have been explained,
Alternatively, it is also possible to configure the cylindrical body 4 to be in a fixed state, to adhere the laminated elements 2, 6, and 7, and to rotate the shaft 2.

As described above, according to the present invention, there is an element formed by laminating a plurality of piezoelectric ceramic plates polarized in the thickness direction and provided with electrodes, and a plurality of piezoelectric ceramic plates polarized in the direction perpendicular to the thickness and provided with electrodes. Since the laminated elements combined with the laminated elements are installed radially between the shaft and the cylindrical body, the electromechanical conversion efficiency is higher than that of conventional electromagnetic rotating devices (motors). Since it is possible to rotate a minute angle with a voltage, it is suitable for application to, for example, a laser tip drive device that requires minute rotational drive.

Further, according to the present invention, since the linear multilayer elements are provided radially together with the multilayer elements, microscopic A reliable braking effect after rotation can be achieved.

Furthermore, according to the present invention, since the reverse laminated elements acting in the direction opposite to the direction of the combined displacement of the laminated elements are provided radially, it is possible to create not only minute rotation in one direction but also minute rotation in the opposite direction.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional perspective view showing an example of the proposed device, FIG. 2 is a diagram showing an example of a piezoelectric laminated element, and FIG.
Figures 4 and 4 are diagrams showing the configuration and operating state of the linear element constituting the example in Figure 2, Figures 5 and 6.
The figure also shows the structure of the sliding type element and its operating state, FIG. 7 is a diagram for explaining the operation of the example in FIG. 2, and FIG. 8 is an explanation of the voltage applied to the piezoelectric multilayer element in the example in FIG. 9 is a sectional view of the essential parts showing another example of the device of the present invention, FIG. 10 is an explanatory diagram of the voltage applied to the piezoelectric laminated element of the example of FIG. 9, and FIG. 11 is a further example of the device of the present invention. It is a sectional view of the important part showing an example. 1... Axis, 2... Piezoelectric laminated displacement element, 4... Cylindrical body, 6... Linear piezoelectric laminated element, 7... Reverse direction piezoelectric laminated displacement element.

Claims (1)

[Claims for Utility Model Registration] 1. An element formed by laminating a plurality of piezoelectric ceramic plates polarized in the thickness direction and provided with electrodes, and a plurality of laminated piezoelectric ceramic plates polarized in the direction perpendicular to the thickness and provided with electrodes. 1. A micro-rotating device characterized in that a laminated element, which is a combination of elements made of 2. The micro-rotation device according to claim 1, which is a registered utility model, wherein the laminated element is fixed to the shaft or cylindrical body and the cylindrical body or shaft is rotationally driven. 3. The micro-rotation device according to claim 1 or 2 of the utility model registration claim, in which linear laminated elements are provided radially together with the laminated elements. 4. The micro-rotation device according to claim 1, 2, or 3 of the utility model registration claim, wherein reverse-direction laminated elements acting in a direction opposite to the combined displacement direction of the laminated elements are radially provided.