JPH0257350B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a transducer that converts current to voltage or voltage to current using a piezoelectric material.

(Summary of the invention) The present invention forms a beam using a magnetic material and a piezoelectric material in a two-layer structure or a multi-layer structure, and drives the magnetic material by applying a magnetic field from the outside by a permanent magnet or by passing a current through a coil. This applies vibration to the piezoelectric material, causing the piezoelectric material to generate a voltage, and conversely, applying a voltage to the piezoelectric material drives the piezoelectric material, and the vibration causes a current to flow through the magnetic material to an external magnetic circuit. This is a transducer between current←→voltage, which generates a voltage.

(Background Art) FIG. 7A is a configuration diagram showing an example of a conventional transducer using a piezoelectric material, 21 and 22 are piezoelectric materials, and 23, 24, and 25 are formed by vapor deposition or conductive paint, etc. Electrodes 26 and 27 are terminals. Furthermore, there are several modes depending on the combination of directions in which voltages are generated in the piezoelectric material, and FIG. 7 shows a case of parallel specification among them. In the case of series specifications, the connections may be made so that the voltages generated when stress is applied in the same direction are in opposite directions. Note that in that case, the electrode 24 between both piezoelectric materials becomes unnecessary.

Therefore, if we choose the direction of the voltage generated as shown by the arrow in Figure 7 (a) (the direction of the voltage generated when compression is applied from the lateral direction), then if mechanical deformation is applied from the outside as shown in b, When the beam formed from the piezoelectric materials 21 and 22 is deflected so as to be convex upward, the upper side becomes tensile and the lower side becomes compressed with the neutral axis as the boundary, and due to the polarization action of the piezoelectric materials 21 and 22, the polarity shown in the figure is achieved. A voltage is generated at , and a voltage signal is taken out between terminals 26 and 27. On the other hand, when it is bent in the opposite direction as shown in (c), the polarity of the voltage generated at the terminals 26 and 27 is reversed.

Further, although the above operation is a case where mechanical deformation is converted into voltage, it is also possible to mechanically deform the beam by applying a signal voltage to the terminals 26 and 27.

The reason why the beam is formed by using a two-layer structure of piezoelectric material as shown in FIG. 7 is that the voltages generated inside the piezoelectric material cancel each other out in one layer, so that no voltage can be extracted. In other words, Figure 8A shows the case where the beam is composed of one layer, but if it is bent as shown in B and C, voltages of opposite polarity will be generated internally with the neutral axis l as the boundary. Therefore, the electrodes 29, 30
When viewed from both ends of the terminal, the voltages cancel each other out and cannot be taken out from the terminals 31 and 32.

By the way, although the conventional transducer operates as described above, its conversion function is only between mechanical displacement←→voltage, and it lacks applicability as a device.

(Object of the Invention) The present invention has been proposed in view of the above points, and its purpose is to provide a transducer that enables mutual conversion of current←→voltage using a piezoelectric material. It's about doing.

(Structure of the Invention) The present invention will be described in detail below with reference to the drawings showing examples.

FIG. 1 is a configuration diagram showing an embodiment of the transducer of the present invention, in which A is an external perspective view and B is a sectional view taken in the longitudinal direction. To explain the configuration in the figure, reference numeral 1 denotes a magnetic material forming the first beam, and a ceramic magnet or a normal magnet can be used. Further, 2 is a piezoelectric material that forms the second beam, and electrodes 3 and 4 are coated on both sides with vapor deposition or conductive paint.
is formed and joined to the first beam made of magnetic material 1 via electrode 3, achieving a beam with a two-layer structure as a whole. Note that the electrodes 3 and 4 are for extracting the voltage generated across the piezoelectric material 2 to the terminals 5 and 6, or for applying a voltage to both ends of the piezoelectric material 2, so if the magnetic material 1 is conductive. If a magnetic material is used, the electrode 3 may be omitted and the terminal 5 may be directly connected to the magnetic material 1, as shown in FIG.

Returning to FIG. 1 and explaining the configuration, magnetic material 1,
The beam composed of the piezoelectric material 2 and the electrodes 3 and 4 has one end fixed to the fixed wall 10, and has a so-called cantilevered structure. Note that the structure is not limited to a cantilevered structure, and a structure in which the structure is fixed on both sides by fixed walls 10 and 11 as shown in FIG. 3 may be used.

On the other hand, in FIG. 1, 7 is a coil, and when converting current to voltage, an exciting current is supplied from terminals 8 and 9, and conversely, when converting voltage to current, the vibration of magnetic material 1 An electromotive force is generated between terminals 8 and 9.

4 shows the operation when the transducer of FIG. 1 is used for converting current to voltage, and the terminals 8 and 9 of the coil 7 are connected to the signal source
is connected. In operation, when the magnetic flux φ generated by the current i supplied from the signal source S is repelled by the magnetic material 1 of the beam, the beam is deflected downward as shown in A, and the polarity changes depending on the direction of the deformation. voltage is generated at terminals 5 and 6. Also, the signal source S
When the magnetic flux φ generated by the current i supplied from . By repeating these steps, a voltage proportional to the current of the signal source S is obtained from the terminals 5 and 6.

In the present invention, the piezoelectric material 2 is one layer, but the presence of the magnetic material 1 shifts the neutral axis from the center of the piezoelectric material 2, so the voltages do not cancel each other out inside the piezoelectric material 2. A voltage corresponding to the deformation can be extracted.

In addition, when converting voltage to current, applying a signal voltage to the terminals 5 and 6 causes the piezoelectric material 2 and eventually the magnetic material 1 to vibrate, and this vibration causes a current to be applied to the external coil 7. induce.

Thus, in the transducer of the present invention,
Especially when converting current to voltage, by applying a magnetic field from outside without contacting the beam,
Since it can generate voltage, it can be used in a variety of applications that were not previously available. For example, if the transducer of the present invention is implanted in biological tissue and the generated voltage is applied to the nervous system, it will be possible to control stimulation of the nervous system without contacting it from the outside, It can be applied to the following fields. Furthermore, in the field of electronic components, by applying it to movable contacts such as micro relays, it is possible to control the displacement of the contacts by applying current or voltage bias.

Next, FIG. 5 shows another embodiment of the present invention, in which a magnetic material 1, a piezoelectric material 2, electrodes 3, 4
By providing a weight 12 at one end of the beam, instead of fixing one end of the beam, the beam is deformed when a magnetic field is applied from the outside. In other words, although there is no stable fixing method within the biological tissue, by creating a weight imbalance in this way, the weight 12 side becomes difficult to move when a magnetic field is applied, thus creating a cantilevered structure. The operation is almost the same.

Next, Fig. 6 was considered from a similar point of view, and half of the first beam is made of non-magnetic material 13, and half of the beam is made so that no force acts even when a magnetic field is applied. The whole thing is deformed. Note that it is also possible to obtain still another configuration by applying the same idea.

(Effects of the Invention) As described above, in the present invention, a beam is formed by using a magnetic material and a piezoelectric material in a two-layer structure or a multi-layer structure, and a permanent magnet or a current is passed through a coil to form a beam. By applying a magnetic field, a magnetic material is driven to vibrate the piezoelectric material, causing the piezoelectric material to generate voltage. Conversely, by applying a voltage to the piezoelectric material to drive the piezoelectric material, the vibration causes the magnetic material to vibrate. Since the current is generated in the external magnetic circuit through the magnetic circuit, conversion between current and voltage can be easily performed, and various applications can be expected.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing one embodiment of the transducer of the present invention, A is an external perspective view, B is a longitudinal sectional view, and FIGS. 2 and 3 are configurations showing other embodiments. 4 is an explanatory diagram of the operation according to the embodiment shown in FIG. 1, FIGS. 5 and 6 are configuration diagrams showing other embodiments, and FIGS. 7 and 8 are diagrams showing the operation of the embodiment shown in FIG. FIG. 3 is an explanatory diagram of a transducer. 1... Magnetic material, 2... Piezoelectric material, 3, 4...
Electrode, 5, 6, 8, 9...terminal, 7...coil,
10, 11... fixed wall, 12... weight, 13... non-magnetic material, S... signal source.

Claims (1)

[Claims] 1 a first beam formed of a magnetic material;
A second beam formed of a piezoelectric material is joined to form a two-layer structure or a multilayer structure, and a magnetic field obtained by passing a current through a coil or a magnetic field obtained by a permanent magnet is applied externally to the first beam. is driven to deform both beams, a voltage corresponding to the deformation is obtained from the pair of surfaces of the second beam, and the second beam is driven by the voltage applied to the pair of surfaces of the second beam. A transducer is characterized in that both beams are deformed by deformation, and a current corresponding to the deformation is obtained from an external magnetic circuit.