JPH07249392A - Tube scanner and actuator having this scanner - Google Patents

Abstract

PURPOSE:To provide an actuator having larger displacement corresponding to voltage applied by power source than that of conventional one. CONSTITUTION:In a tube scanner 10 having a cylindrical piezoelectric device 1, and electrodes 2, 3 arranged on the inner and outer circumferential surfaces of the device 1, each electrode is divided into plural in the corresponding positions on inner circumferential sides 3a-3d and outer circumferential sides 2a-2d, and electrodes forming plural pairs are formed with electrodes on inner circumferential side and outer circumferential side facing by interposing the piezoelectric device 1. An actuator is constituted with the tube scanner 10 and a power source for applying voltage to electrodes 2a-2d and 3a-3d of the scanner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator using a piezoelectric element and a tube scanner used therein.

[0002]

2. Description of the Related Art FIG. 5 is a schematic diagram showing the structure of a tube scanner used in a conventional actuator for three-dimensional movement. This tube scanner has electrodes 61a and 61b for scanning in the X direction and electrodes 62a for scanning in the Y direction on the outer peripheral surface of a piezoelectric ceramic 60 formed in a cylindrical shape.
62b are provided so as to face each other in the X direction and in the Y direction. The electrodes 61a, 61b, 62a, 6 are formed on the inner peripheral surface of the piezoelectric ceramic 60.
A common electrode 63 is provided for 2b. The object to be displaced is usually installed near one bottom surface of a cylinder made of piezoelectric ceramic 60, and the other bottom surface is fixed to a member (not shown).

When the actuator (object) is displaced in the X and Y directions, a power source (not shown) is controlled to apply electric potentials having the same magnitude but different signs between the respective electrodes in the respective directions. As a result, the piezoelectric ceramic 60 bends and a displacement in a desired direction is obtained. Further, when displacing in the Z direction, either positive or negative voltage is set, and this voltage is equally applied between the respective electrodes on the outer peripheral surfaces of all X and Y and the common electrode 63, whereby the piezoelectric ceramics. 60
Expands and contracts in the Z direction (G.Binnig and DPESmith, Re
v.Sci.Instrum.Vol.57, P1688 (1986)). An actuator equipped with such a tube scanner has a desired performance and is low in cost due to its simple structure. Therefore, it is used as a means for three-dimensionally scanning a probe (probe) in a scanning probe microscope. It is used.

[0004]

The displacement amount of the above-mentioned actuator depends on the potential difference between the electrode installed on the inner side (inner peripheral surface) and the outer electrode (outer peripheral surface) of the tube scanner. . Therefore, when the displacement amount of the actuator is increased, the voltage applied between the electrodes is also set to a high value. Therefore, there is a problem in that it is necessary to provide a power supply and a circuit corresponding to a high voltage, which increases the manufacturing cost of the drive circuit. In addition, the high-voltage power source is large and requires a large installation space. The present invention aims to solve such problems.

[0005]

For the above-mentioned purpose, the first
According to the invention (the invention according to claim 1), in a tube scanner including a piezoelectric element formed in a cylindrical shape and electrodes provided on an inner peripheral surface and an outer peripheral surface of the element, the inner circumference of each electrode is provided. The side and the outer side are divided into a plurality of portions at corresponding positions, and a plurality of pairs of electrodes (electrode pairs) are formed by the corresponding electrodes on the inner peripheral side and the outer side.

In the second invention (the invention according to claim 2), an actuator is constituted by the tube scanner and a power source for applying a voltage to the electrodes of the scanner. In a third invention (an invention according to claim 3), each electrode on the inner peripheral side of the tube scanner and an electrode on the outer peripheral side corresponding to the electrode constitute a plurality of electrode pairs, and the power source comprises each electrode pair. The electrodes having opposite polarities are applied to the respective electrodes.

In the fourth invention (the invention according to claim 4), in two sets of electrode pairs located at axially symmetrical positions of the cylinder formed by the piezoelectric element, the voltage is applied to the electrodes on the outer peripheral side of one electrode pair. The voltage and the voltage applied to the electrode on the inner circumference side of the other electrode pair, the voltage applied to the electrode on the inner circumference side of the one electrode pair, and the voltage applied to the electrode on the outer circumference side of the other electrode pair are ,
The polarities were the same.

[0008]

[Function] The conventional actuator tube scanner is
Only the outer (outer peripheral surface) electrode is divided according to the displacement direction (for example, the XY direction), and the inner (inner peripheral surface) electrode is shared regardless of the displacement direction. Further, the potential of the inner electrode was fixed (grounded) when it was displaced in the directions (the XY directions) orthogonal to the axial direction of the cylindrical body.

On the other hand, in the tube scanner of the first aspect of the invention, the inner electrode is divided so as to correspond to the outer electrode. The actuators of the second, third, and fourth inventions can each apply a desired potential difference between the inner and outer electrodes (both form an electrode pair) facing each other via the piezoelectric element of the tube scanner. Therefore, when a power supply with the same voltage as the conventional one is used, if the potential of the inner electrode and the potential of the outer electrode are set to have opposite polarities (+ or −), the potential difference between these electrodes can be maximized. It can be doubled up to the conventional level. Further, if the desired maximum displacement amount is the same as the conventional one, the voltage applied by the power supply can be half that of the conventional one. That is, the amount of displacement corresponding to the voltage applied by the power supply can be made larger than before.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic structural view showing an example of a tube scanner of the present invention, FIG. 1a is a plan view of the tube scanner, and FIG. 1b is a perspective view. The tube scanner 10
The piezoelectric ceramic 1 formed in a cylindrical shape, and the outer electrode 2a provided on the outer peripheral surface of the piezoelectric ceramic 1 in such a manner that one outer peripheral surface is divided into four equal parts along the axial direction of the cylinder. .About.2d and four inner electrodes 3a to 3d, which are separately provided on the inner peripheral surface of the piezoelectric ceramic 1 so as to correspond to the outer electrodes 2a to 2d. Here, two pairs of electrodes, that is, the outer electrode 2a and the inner electrode 3a and the outer electrode 2c and the inner electrode 3c constitute an electrode for X-direction displacement, and the outer electrode 2b and the inner electrode 3b and the outer electrode 2d and the inner electrode 3d. The two pairs of electrodes constitute a Y-direction displacement electrode.

FIG. 2 is a schematic view showing the structure of the actuator of the present invention. This actuator comprises a tube scanner 10 of FIG. 1 and each outer electrode 2 of this scanner 10.
a to 2d and inner electrodes 3a to 3d, and a total of eight bipolar power supplies 4a to 4h for applying a predetermined voltage (+ A volt to −A volt) to each of these electrodes. Each of the power supplies 4a to 4h is set so that voltages are applied to the inner electrode and the outer electrode in opposite phases. At that time, from the state where the inner electrode is + A volt and the outer electrode is -A volt, the inner electrode is -A volt and the outer electrode is + A volt.
The value of the applied voltage can be arbitrarily changed up to the state of A volt. Note that the object to be displaced (not shown) is as shown in FIG.
The piezoelectric ceramics 1 shown in FIG. The other bottom surface of the piezoelectric ceramic 1 is fixed to a base (not shown) for use.

Next, a method of controlling the actuator of this embodiment will be described. When the actuator is displaced in a direction (X or Y direction) orthogonal to the axial direction of the cylinder of the piezoelectric ceramics 1, as in the conventional case, the inner electrode and the outer electrode of the two pairs of electrode pairs facing each other according to the displacement direction, The voltage may be applied so that the expansion and contraction of the piezoelectric ceramic 1 are reversed. For example, in the case of displacing in the X direction, in the power supplies 4a and 4b respectively connected to the outer electrode 2a and the inner electrode 3a forming the electrode pair for displacing in the X direction, the power supply 4a is -A volt and the power supply 4b is + A volt. Is applied to each connected electrode. Further, in the power supplies 4e and 4f connected to the outer electrode 2c and the inner electrode 3c that form the remaining electrode pair for X-direction displacement, -A volt is connected to the power supply 4e and + A volt is connected to the power supply 4f. Applied to the electrode. As a result, the piezoelectric ceramics 1 at the portion corresponding to the X-direction displacement electrode expands and contracts according to the polarity of the applied voltage and bends in the X direction, so that displacement in the X direction is obtained. The amount of displacement can be adjusted by changing the value of the applied voltage. As for the displacement in the Y direction, the voltage applied to the electrodes may be set similarly to the displacement in the X direction, and thus the description thereof will be omitted. Further, when the piezoelectric ceramics 1 is displaced in the axial direction (Z direction) of the cylinder, the piezoelectric ceramics 1 may be expanded and contracted by applying the same voltage to all the electrodes as in the conventional case.

As described above, in the actuator of this embodiment, the potential difference between the inner electrode and the outer electrode can be set up to 2 A volt at the maximum. In other words, assuming a case where the same power supply as in the conventional case in which the maximum applied voltage is A volt is used, the inner electrode is fixed (for example, 0 V) and only the outer electrode is -A.
The maximum potential difference between the inner electrode and the outer electrode is twice as large as that of the conventional actuator that changes in the range of + A volts. As a result, it is possible to obtain a displacement amount that is twice as large as the conventional displacement amount. Further, assuming that the desired maximum displacement amount is the same as the conventional one, it is only necessary to apply a voltage of absolute value (A / 2) volt whose polarities are opposite to each other to the inner electrode and the outer electrode. It suffices to prepare a power supply for applying (A / 2 to + A / 2 volt).

FIG. 3 is a schematic diagram showing the structure of the actuator when the power source is a single power source (applicable in the range of 0 to + A volt). In FIG. 3, only the power source connected to one pair of electrodes is shown. In order to use the power supply voltage most effectively, the power supply 6 has a half (+) of the maximum voltage A.
A / 2) Add a bolt offset. Further, an inverting amplifier 5 is installed on the circuit which goes to the electrode on one side. Then, the inner electrode 2 is controlled by the variable power source 7 and the amplifier 8.
By applying a voltage to each electrode so that the a to 2d and the outer electrodes 3a to 3d have opposite polarities, the output to the electrodes is made to swing in reverse with the offset voltage as the center. As a result, the voltage applied to each electrode can be controlled from the state where the inner electrode is + A volt and the outer electrode is 0 volt to the state where the inner electrode is 0 volt and the outer electrode is + A volt. The variable power source 7 can be configured by reducing the potential of the power source 6 based on the power source 6. Therefore, in the configuration of FIG. 3, it is sufficient to prepare one power source for the pair of inner and outer electrodes. Therefore, the number of power sources is halved compared to the configuration of FIG. 2, and the configuration of the drive circuit is simplified.

FIG. 4 is a diagram showing the construction of a tube scanner which is constructed so as to be displaced in two directions, the axial direction of a cylinder and the direction orthogonal to this axial direction. The voltage may be applied in the same manner as described above. In this case, the tube scanner is displaced uniaxially.

[0016]

As described above, according to the present invention, the amount of displacement corresponding to the voltage applied by the power source becomes larger than in the conventional case.
Therefore, when the desired displacement amount is the same as the conventional one, it is possible to set the voltage of the power source to half the conventional voltage. As a result, it is possible to reduce the manufacturing cost of the actuator (driving circuit) generated by providing the high-voltage power supply and the circuit corresponding to the high voltage. Moreover, since the voltage of the power supply is lowered, the power supply can be downsized, and the degree of freedom of the installation location is increased. Further, since the voltage is lowered, there is an effect that the safety is improved.

[Brief description of drawings]

1A and 1B show an example of the configuration of a tube scanner of the present invention, FIG. 1A is a plan view, and FIG. 1B is a perspective view.

FIG. 2 is a schematic diagram showing an example of a configuration of an actuator of the present invention.

FIG. 3 is a schematic diagram showing an example of a configuration of an actuator of the present invention.

4A and 4B show an example of a structure of an actuator of the present invention, FIG. 4A is a plan view, and FIG. 4B is a perspective view.

FIG. 5 is a schematic perspective view showing the configuration of a conventional tube scanner.

[Explanation of symbols for main parts]

 1 Piezoelectric Ceramic 2 Outer Electrode 3 Inner Electrode 4 Power Supply 5 Inverting Amplifier 6 Power Supply 10 Tube Scanner

Claims (4)

[Claims] 1. A tube scanner having a piezoelectric element formed in a cylindrical shape and electrodes provided on an inner peripheral surface and an outer peripheral surface of the element, respectively, wherein each electrode is provided on an inner peripheral side and an outer peripheral side, respectively. A tube scanner characterized in that it is divided into a plurality of parts at corresponding positions, and a plurality of pairs of electrodes are formed by electrodes on the inner peripheral side and the outer peripheral side facing each other with the piezoelectric element interposed therebetween. 2. An actuator comprising the tube scanner according to claim 1 and a power source for applying a voltage to each electrode of the scanner. 3. An electrode of the tube scanner comprises a plurality of electrode pairs, each electrode on the inner peripheral side and an electrode on the outer peripheral side corresponding to the electrode, and the power source is arranged on each electrode of each electrode pair. The actuator according to claim 2, wherein voltages having mutually opposite polarities are applied. 4. In two pairs of electrodes located at axially symmetrical positions of a cylinder formed by the piezoelectric element, a voltage applied to an electrode on the outer peripheral side of one electrode pair and a voltage applied to the inner peripheral side of the other electrode pair. The voltage applied to the electrodes, the voltage applied to the electrodes on the inner circumference side of the one electrode pair, and the voltage applied to the electrodes on the outer circumference side of the other electrode pair have the same polarity. The actuator according to claim 3.