JPH1010147A - Piezoelectric acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prove the acceleration sensor comprising piezoelectric ceramic rectangular plates having a plurality of highly reliable inner electrodes. SOLUTION: A piezoelectric ceramic plate constituting this sensor has the laminated structure having two or more layers. Electrodes are formed at the upper surface, the lower surface and each laminated layer surface. The electrode one after the other is conducted through the first penetrating electrode provided at one end of the piezoelectric ceramic plate and used as a reference electrode 32. Furthermore, in the electrodes other than the reference electrode 32, the electrode, which is deviated to one side from the center of the direction of the laminated layer is conducted by the second electrode provided at one end at the piezoelectric ceramic plate, and used as a first detecting electrode 31. Furthermore, the electrode at the other one side from the center of the direction of the laminated layer is conducted by the third penetrating electrode and used as a second detecting electrode 33. In this case, the reference electrode 32, the first detecting electrode 31 and the second detecting electrode 33 are taken out on one surface of the end part of one above described ceramic plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor for detecting acceleration of a moving body or the like, and more particularly, to a structure and a manufacturing method of a piezoelectric element of a piezoelectric acceleration sensor using piezoelectric characteristics of a piezoelectric ceramic.

[0002]

2. Description of the Related Art Japanese Patent Application No. 216207/1992 proposes a sensor for detecting a low-frequency acceleration having a structure in which a piezoelectric ceramic rectangular plate having a plurality of internal electrodes is supported at one end. These acceleration sensors detect distortion of a piezoelectric ceramic rectangular plate caused by application of acceleration as a voltage by a piezoelectric effect, and are configured to increase output voltage with respect to acceleration by having a plurality of piezoelectric layers inside. ing.

[0003]

When an acceleration sensor is formed by a piezoelectric ceramic rectangular plate having a plurality of internal electrodes, it is conventionally necessary to connect the internal electrodes to one end face of the piezoelectric ceramic rectangular plate. Yes, reliability was poor. In addition, the ceramic rectangular plate is usually fired in a large plate state, and then cut into individual elements.
In the step of performing the polarization processing, it is necessary to cut the piezoelectric ceramic rectangular plate into individual elements and perform the conduction processing of the internal electrodes before performing the polarization processing, which hinders cost reduction.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a so-called piezoelectric acceleration sensor for detecting a distortion generated in accordance with an applied acceleration by converting the distortion into a voltage using a piezoelectric effect. The ceramic plate has a laminated structure composed of two or more piezoelectric ceramic layers and electrodes, electrodes are formed on the upper and lower surfaces of the piezoelectric ceramic plate, and every other electrode is provided at one end of the piezoelectric ceramic plate. Conducted by the first penetrating electrode provided and used as a reference electrode, of the other electrodes of the reference electrode, one electrode on one side from the center in the stacking direction is formed by the second penetrating electrode provided at one end of the piezoelectric ceramic plate Conduction is used as a first detection electrode, and an electrode on another side (opposite side) from the center in the stacking direction is conducted by a third penetrating electrode and used as a second detection electrode. Reference electrode, the first detection electrode and the second detection electrodes is a piezoelectric acceleration sensor, characterized by being drawn to one side of the piezoelectric ceramic plate.

In the manufacturing process, a plurality of acceleration sensor elements are formed on the same ceramic plate, and the first detection electrodes of each element are connected by electrodes on (or inside) the ceramic plate. Similarly, the second detection terminal and the reference electrode are also connected and pulled out on the ceramic plate,
After laminating and firing a ceramic plate and electrodes, a plurality of acceleration sensor elements are simultaneously polarized as a ceramic plate, and then disassembled (cut) into individual acceleration sensor elements. Between the piezoelectric ceramic reference electrode and the first detection electrode, and between the reference electrode and the second detection electrode.
A piezoelectric acceleration sensor element characterized in that polarization is applied in the opposite direction to that between the detection electrodes to cancel the pyroelectric effect, and this element is supported and fixed like a cantilever. Then, an acceleration sensor is obtained.

According to the present invention, a plurality of piezoelectric elements having a plurality of internal electrodes can be formed on the same ceramic plate, and a plurality of piezoelectric elements can be simultaneously subjected to polarization processing without cutting. Since it is not necessary to perform connection processing or polarization processing of the internal electrodes after cutting and dividing, an acceleration sensor having high sensitivity and a small pyroelectric effect can be manufactured at low cost. Also, the detection electrode 1, the detection electrode 2,
And since the reference electrode is drawn out only on one side of the end of the ceramic rectangular plate, it is easy to connect to the external terminal,
It is possible to obtain a small acceleration sensor.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be specifically described below with reference to embodiments.

FIG. 1 is a view for explaining the structure of internal electrodes of a piezoelectric ceramic rectangular plate for an acceleration sensor, a terminal structure, and positions of through holes according to an embodiment of the present invention.
1A is an exploded view, and FIG. 1B is a perspective view. The piezoelectric ceramic layers 11 to 18 and the electrode layers 21 to 29 are alternately laminated, the electrode layers 21, 23, 25, 27, and 29 have a protrusion at the center of one end, and the electrode layers 22, 24 are at the edges of one end. The electrode layers 27 and 29 have protrusions on the edges opposite to the ends 22 and 24. As shown in FIG. 1B, the electrode layers 22 and 24 are connected by a through hole 41 and connected to an external terminal 31. Electrode layer 2
1, 23, 25, 27, and 29 are connected by through holes 42 and are connected to external terminals 32. The electrode layers 27 and 29 are connected by a through hole 43 and are connected to an external terminal 33.

FIG. 2 is a view for explaining the polarization direction of the piezoelectric ceramic rectangular plate for an acceleration sensor according to one embodiment of the present invention. Each of the piezoelectric ceramic layers 11 to 18 in FIG. 2 is subjected to a polarization process in a direction indicated by an arrow. FIG. 3 is a perspective view showing a structure of a ceramic plate for performing a plurality of lamination, firing and polarization simultaneously at the time of manufacturing a piezoelectric ceramic rectangular plate according to an embodiment of the present invention. At the time of manufacturing the ceramic rectangular plate described with reference to FIG. 1, a plurality of acceleration sensors can be simultaneously formed as shown in FIG. The detection terminals of the respective rectangular plates are connected, and are led out to the polarization terminals 51 at the ends of the ceramic plate. Similarly, the respective reference electrodes and the second detection electrodes are connected to each other and are led out to polarization electrodes 52 and 53 at the ends of the ceramic plate. The connection of the electrodes of each rectangular plate may be performed by electrodes formed on the surface of the ceramic plate, or may be performed by forming electrodes inside the laminate.

In the state of the ceramic plate shown in FIG. 3, as shown in FIG. 4, by connecting and applying a voltage and performing a polarization process, a plurality of ceramic rectangular plates are polarized in the direction shown in FIG. be able to.

After the polarization process, each ceramic rectangular plate is cut and used as an acceleration sensor as shown in FIG. FIG. 5 is a perspective view showing the structure of the acceleration sensor according to one embodiment of the present invention. One end of the above-described piezoelectric ceramic rectangular plate is supported and fixed as shown in FIG. The detection electrodes 31 and 33 on the upper surface are short-circuited and connected to an operational amplifier circuit as shown in FIG. In this state, if acceleration G is applied to the piezoelectric ceramic rectangular plate in the direction of the arrow shown in FIG. 5, distortion occurs in the piezoelectric ceramic rectangular plate, and a voltage proportional to the acceleration can be detected by the piezoelectric effect.

[0012]

As described above, in the acceleration sensor and the method of manufacturing the acceleration sensor according to the present invention, since a plurality of piezoelectric ceramic rectangular plates can be simultaneously laminated, sintered and polarized, individual pieces can be obtained. There is no need to perform electrode connection processing or polarization processing after cutting into pieces, and a piezoelectric ceramic rectangular plate for a piezoelectric acceleration sensor can be formed. Further, since the output terminals of the piezoelectric ceramic rectangular plate are drawn out to one side of the end of the rectangular plate, connection to a circuit can be easily performed. Therefore, it is possible to obtain a high-accuracy acceleration sensor which has high detection sensitivity, can detect even a low frequency, and is not easily affected by the pyroelectric effect, and has a great industrial value.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a structure of a piezoelectric ceramic rectangular plate of an acceleration sensor according to an embodiment of the present invention.
1A is an exploded view, and FIG. 1B is a perspective view.

FIG. 2 is a sectional view showing a polarization direction of a piezoelectric ceramic rectangular plate for an acceleration sensor according to one embodiment of the present invention.

FIG. 3 is a perspective view showing a structure of a ceramic plate when a plurality of layers are laminated, fired, and polarized simultaneously at the time of manufacturing a piezoelectric ceramic rectangular plate for an acceleration sensor according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram of electrical connection and polarization direction when performing polarization in manufacturing a piezoelectric ceramic rectangular plate for an acceleration sensor according to one embodiment of the present invention.

FIG. 5 is a perspective view showing an embodiment of an acceleration sensor having a cantilever structure using a piezoelectric ceramic rectangular plate for an acceleration sensor according to the present invention.

FIG. 6 is a block diagram showing a state connected to an operational amplifier circuit.

[Explanation of symbols]

 11-18 Piezoelectric ceramic layer 21-29 Electrode layer 31 First detection electrode (external terminal) 32 Reference electrode (external terminal) 33 Second detection electrode (external terminal) 41-43 Through hole for electrode connection 51-53 Polarization Electrode

Claims (3)

[Claims] 1. A piezoelectric acceleration sensor for detecting a distortion generated in accordance with an applied acceleration by converting the distortion into a voltage using a piezoelectric effect, wherein a piezoelectric ceramic plate constituting the acceleration sensor comprises two or more ceramic layers. An electrode is formed on the upper and lower surfaces of the piezoelectric ceramic plate having a laminated structure composed of electrodes, and every other electrode is a first electrode provided at the center of the width of one end of the piezoelectric ceramic plate. The electrode that is conducted by the through electrode and is used as a reference electrode, and the electrode other than the reference electrode on one side from the center in the stacking direction is a second electrode provided at one end of the piezoelectric ceramic plate.
Is used as a first detection electrode by conduction through the through electrode, and an electrode on the other side from the center in the stacking direction is conducted to a third penetration electrode to be used as a second detection electrode. A piezoelectric acceleration sensor, wherein the first detection electrode and the second detection electrode are extended to one surface of an end of the piezoelectric ceramic plate. 2. The polarization direction between the reference electrode and the first detection electrode according to claim 1 and the polarization direction between the reference electrode and the second detection electrode are opposite to each other to cancel the pyroelectric effect. A piezoelectric acceleration sensor characterized by being configured as described above. 3. The method for manufacturing a piezoelectric acceleration sensor according to claim 1, wherein a plurality of acceleration sensor elements are formed on the same ceramic plate, and a first detection electrode, a second detection electrode, and a second detection electrode of each element are provided. The reference electrode is connected by an electrode on the ceramic plate.
A method for manufacturing a piezoelectric acceleration sensor, comprising: sintering and then simultaneously polarizing and cutting a plurality of acceleration sensor elements to form individual acceleration sensor elements.