JP2010067787A - Stacked piezoelectric element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable stacked piezoelectric element capable of suppressing performance deterioration even under a driving environment in which the element is repeatedly used over a long period of time. <P>SOLUTION: The stacked piezoelectric element 1 includes: a ceramic laminate 10, in which positive and negative internal electrode layers 11 and 12 are alternately disposed with ceramic layers 13 interposed therebetween; and a pair of external electrodes 21 and 22, one of which is electrically connected to each of the positive and negative internal electrode layers 11 and 12. The stacked piezoelectric element 1 also has insulation resistance measuring sections 30, each of which measures the insulation resistance of a ceramic layer 13 between internal electrode layers 11, 11 having the same polarity. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multilayer piezoelectric element including a ceramic laminate having an internal electrode layer and an external electrode connected to the internal electrode layer, and in particular, a multilayer piezoelectric element capable of improving durability. It relates to an element.

  Conventionally, in order to control a displacement amount according to a voltage, for example, a piezoelectric element is sometimes used for opening and closing a fuel injection valve of an engine. As such a piezoelectric element, in order to improve controllability and responsiveness, a multilayer piezoelectric element including a ceramic laminate having a structure in which internal electrode layers and ceramic layers are alternately laminated is often used.

  As an example, a stacked piezoelectric element 90 shown in FIG. 4 has been proposed (see, for example, Patent Document 1). The multilayer piezoelectric element 90 includes a ceramic laminate 10 and a pair of external electrodes 21 and 22 that sandwich the ceramic laminate 10. In the ceramic laminate 10, positive and negative internal electrode layers 11 and 12 are alternately stacked via a ceramic layer 13. The positive or negative internal electrode layers 11 and 12 are connected to the corresponding positive or negative external electrodes 21 and 22. Furthermore, a slit-like gap 15 is partially formed in the ceramic layer 13 in order to relieve the stress generated by the expansion (displacement) of the multilayer piezoelectric element. Providing slit-shaped gaps in this multilayer piezoelectric element is also commonly performed in other multilayer piezoelectric elements (see, for example, Patent Document 2).

  In such a laminated piezoelectric element 90, an electric field is applied between the internal electrode layers 11 and 12 by connecting a power source to the pair of external electrodes 21 and 22 and controlling the voltage from the power source. Then, according to the strength of the electric field, each ceramic layer 13 is displaced in the longitudinal direction (lamination direction), and the displacement of the ceramic laminate 10 of the multilayer piezoelectric element 90 is adjusted. Furthermore, the stress acting on the ceramic laminate 10 is relieved by the slit-shaped gap 15 even under driving environment conditions in which the displacement of the multilayer piezoelectric element 90 is repeated for a long time.

JP-A-2005-223013 JP 2006-351602 A

  However, as shown in Patent Document 1, even when slit-like voids are provided in the ceramic laminate 10, cracks or the like may occur in the ceramic layer by repeatedly using the piezoelectric element for a long time. is there. And this crack progressed, the conductive material which comprises an internal electrode layer caused migration etc., and the insulation of the ceramic layer might fall.

  For example, in the case of a ceramic layer provided with slit-like voids, cracks are likely to occur at the tips of the voids, and these cracks may progress obliquely with respect to the stacking direction and reach the internal electrode layer. .

  In addition, when the multilayer piezoelectric element is used repeatedly over a long period of time, oxygen vacancies are generated in the ceramic material of the ceramic layer on the positive electrode side, and the oxygen vacancies move to the negative electrode side. The oxygen vacancies collected in the negative electrode are considered to form an internal electric field in the ceramic layer. As a result, the insulation between the internal electrodes of the negative electrode is lowered.

  As described above, if the deterioration of the insulating properties of the ceramic layer occurs even at one location, it is difficult to apply an electric field to a healthy ceramic layer. As a result, even if a voltage is applied between the electrodes of the multilayer piezoelectric element by the power source, it is impossible to expect a desired displacement of the multilayer piezoelectric element as a whole, and the performance of the multilayer piezoelectric element deteriorates.

  The present invention has been made in view of the above-described problems, and the object of the present invention is to be able to suppress deterioration in performance even in a driving environment that is repeatedly used for a long time. An object of the present invention is to provide a highly multilayered piezoelectric element.

  In order to solve the above problems, a multilayer piezoelectric element according to the present invention includes a ceramic laminate in which a positive electrode and a negative internal electrode layer are alternately arranged with a ceramic layer interposed therebetween, and a positive electrode or a negative electrode internal electrode layer, respectively. And a pair of external electrodes electrically connected to each other, wherein the multilayer piezoelectric element has an insulation resistance of the ceramic layer between the internal electrode layers of the same polarity. An insulation resistance measuring unit for measuring the above is provided.

  According to the present invention, the insulation resistance measuring unit measures the insulation resistance of the ceramic layer between the internal electrode layers of the same polarity, so that the ceramic layer whose insulation resistance is lowered in real time when the multilayer piezoelectric element is used. Can be specified. As a result, it is possible to cut off the electrical connection between the internal electrode layer (with the same polarity) sandwiching the ceramic layer with reduced insulation resistance and the external electrode connected thereto. In this way, by cutting off the electrical connection, the electric field from the external electrode is not applied to the ceramic layer whose insulation resistance has been reduced, so that a desired electric field can be applied to another healthy ceramic layer. It is possible to suppress the deterioration of the displacement performance of the ceramic laminate.

  In the multilayer piezoelectric element according to the present invention, the electrical connection between the internal electrode layer and the external electrode is made through the insulation resistance measuring unit. According to the present invention, since it has a structure in which at least one of the internal electrode layers sandwiching the ceramic layer to be measured and the external electrode are connected by the insulation resistance measurement unit, it is determined that the insulation resistance has been reduced by measurement. In this case, the electrical connection with the insulation resistance measuring unit can be easily cut off. Thereby, it is possible to prevent the electric field from being easily applied to the ceramic layer having a reduced insulation resistance.

  In addition, such disconnection of the connection can be achieved by disconnecting either the connection between the external electrode and the insulation resistance measurement unit or the connection between the internal electrode layer and the insulation resistance measurement unit, More preferably, the insulation resistance measurement unit includes a connection blocking unit that blocks the electrical connection between the internal electrode layer and the external electrode.

  According to the present invention, the connection between the internal electrode layer and the external electrode can be more easily cut off by providing a connection cut-off portion in the insulation resistance measuring portion without removing the connection portion between the members. Can do. In addition, it is possible to control the shut-off operation using the control device.

  In addition, the multilayer piezoelectric element according to the present invention includes a stress relaxation ceramic layer in which a void is formed to relax the stress of the multilayer piezoelectric element as the ceramic layer, and is connected to the insulation resistance measurement unit. The internal electrode layer is more preferably an internal electrode layer adjacent to the stress relaxation ceramic layer.

  According to the present invention, the stress generated in the ceramic layer when the ceramic laminate is repeatedly displaced can be relaxed by providing the ceramic layer with a stress relaxation ceramic layer in which voids are formed. Further, such voids may develop due to repeated displacement and cracks may be generated from the tip, and the progress of the cracks may reduce the insulation of the stress relaxation ceramic layer and the adjacent ceramic layer. However, even in such a case, since the connection between the internal electrode layer adjacent to the stress relaxation ceramic layer and the external electrode can be cut off, the stress relaxation ceramic layer having a reduced insulation resistance and the adjacent ceramic layer In addition, it is possible not to apply an electric field from the external electrode, and it is possible to eliminate a decrease in insulation as a whole of the multilayer piezoelectric element.

  In the multilayer piezoelectric element according to the present invention, the internal electrode layer connected to the insulation resistance measuring unit is more preferably a negative internal electrode layer. Based on the results of repeated experiments by the inventors, the ceramic layer in which the insulation resistance is likely to decrease is the ceramic layer adjacent to the negative electrode internal electrode layer, particularly the negative electrode internal electrode layer adjacent to the stress relaxation ceramic layer. It is understood that. From this, the insulation resistance of the ceramic layer between the internal electrode layers of the negative electrode is measured, and the connection between the negative electrode internal electrode and the external electrode is cut off as the insulation resistance decreases, thereby reducing the performance of the multilayer piezoelectric element. Can be further suppressed.

  Furthermore, the multilayer piezoelectric element according to the present invention further includes a control device that controls the shut-off operation of the connection shut-off unit, and the control device has an insulation resistance value based on a value measured by the insulation resistance measuring unit. It is more preferable to include an insulation resistance calculation means for calculating the above and an interruption operation means for causing the connection interruption portion to perform an interruption operation based on the insulation resistance value.

  According to the present invention, based on the calculated insulation resistance value, when the insulation resistance of the ceramic layer being measured falls below a predetermined value, the control device sends a control signal to the connection cutoff unit, It is possible to cause the part to perform a blocking operation for blocking the connection between the internal electrode layer and the external electrode layer. In this way, by using the control device, it is possible to collectively monitor the decrease in the insulation resistance of the ceramic layer whose insulation resistance is being measured, and further, the internal electrode adjacent to the ceramic layer whose insulation resistance has decreased. The electrical connection between the layer and the external electrode can be interrupted.

  According to the present invention, a ceramic layer with reduced insulation resistance can be identified, and an electric field from an external electrode can be prevented from being applied to the ceramic layer, and a desired electric field can be applied only to another healthy ceramic layer. Since it can be applied, it is possible to suppress a decrease in displacement performance of the ceramic laminate of the multilayer piezoelectric element.

Below, with reference to drawings, the lamination type piezoelectric element concerning the present invention is explained based on an embodiment.
FIG. 1 is an overall configuration diagram of the multilayer piezoelectric element according to this embodiment, and FIG. 2 is a perspective view of the ceramic laminate shown in FIG. As shown in FIG. 1, the multilayer piezoelectric element 1 according to the present embodiment includes at least a ceramic laminate 10, a pair of external electrodes 21 and 22, an insulation resistance measurement unit 30, and a control device 50, and an external This is an element for displacing the ceramic laminate 10 in the laminating direction by applying an electric field in the ceramic laminate 10 by the electrodes 21 and 22.

  As shown in FIGS. 1 and 2, the ceramic laminate 10 is a laminate obtained by alternately laminating internal electrode layers 11 and 12 and a ceramic layer 13, and on the outer surfaces 110 and 120 of the ceramic laminate 10, The external electrodes 21 and 22 are electrically connected to the internal electrode layers 11 and 12.

  The internal electrode layers 11 and 12 have a positive internal electrode layer 11 and a negative internal electrode layer 12, and the positive and negative internal electrode layers 11 and 12 are alternately arranged in the stacking direction (longitudinal direction). Yes. In this way, the ceramic laminate 10 has the positive and negative internal electrode layers 11 and 12 arranged alternately with the ceramic layer 13 interposed therebetween.

  Moreover, the internal electrode layer 11 of the positive electrode is the same as the ceramic layer in which the conductive internal electrode portion 111 and the outer peripheral end portion of the internal electrode portion 111 are held inward from the outer peripheral surface of the ceramic laminate 10. And a holding portion 112 made of a material. Similarly, the negative internal electrode layer 12 also has an internal electrode portion 121 and a holding portion 122.

  Both the positive electrode and the negative electrode internal electrode layers 11 and 12 expose the outer end portions of the internal electrode portions 111 and 121 only on either one of the outer surfaces 110 and 120 of the ceramic laminate 10, and Except for one outer surface from which the electrode portions 111 and 121 are exposed, the outer peripheral end portion of each internal electrode portion 121 is positioned inward.

  Thus, the positive electrode internal electrode layer 11 is exposed on one outer surface (positive electrode outer surface) 110, the internal electrode portion 111 of the positive electrode internal electrode layer is exposed, and on the other outer surface (negative electrode side outer surface) 120, The holding portion 112 made of the same material as the ceramic layer is exposed. On the other hand, the negative internal electrode layers 12 are arranged alternately with the positive internal electrode layers 11, and on the other outer surface (the outer surface on the negative electrode side), the holding portion 122 made of the same material as the ceramic layer is exposed. In the outer surface (the outer surface of the positive electrode), the internal electrode portion 121 of the negative electrode internal electrode layer is exposed.

  As a result, the ceramic laminate 10 has a so-called partial electrode structure in which a part of the outer peripheral end portions of the internal electrode portions 111 and 121 are kept inward, and in connection with the external electrodes 21 and 22. Electrical insulation reliability can be ensured.

  Further, a ceramic layer 13 made of a piezoelectric ceramic material is disposed between the internal electrode layer 11 of each positive electrode and the internal electrode layer 12 of each negative electrode, and the ceramic laminate 10 includes the internal electrode layer 11 of the positive electrode, The ceramic layer 13, the negative electrode layer 12, the ceramic layer 13, the positive electrode layer 11, and so on are stacked in this order. The ceramic layer is made of a piezoelectric ceramic such as a barium titanate ceramic or a lead zirconate titanate (PZT) ceramic.

  Since the positive internal electrode layer 11 and the negative internal electrode layer 12 are alternately arranged in this way, an electric field can be applied to each of the ceramic layers 13 disposed between these layers, which is efficient. It is possible to displace the ceramic laminate 10.

  Furthermore, in some ceramic layers (stress relaxation ceramic layers) 13A among the plurality of stacked ceramic layers 13, a position constituting the surface of the ceramic laminate 10 in order to relieve the stress of the multilayer piezoelectric element, A slit-shaped gap 15 is formed. The gap 15 may be further filled with an insulating material having electrical insulation.

  On the outer surfaces 110 and 120 of the ceramic laminate 10 having such a structure, one of the pair of external electrodes 21 and 22 is further electrically joined to either the positive electrode or the negative electrode layer 11 or 12. Yes. Specifically, the positive external electrode 21 is electrically connected to the internal electrode portion 111 of the positive internal electrode layer 11 exposed on one outer surface (positive surface) 110 of the ceramic laminate 10. On the other hand, the negative external electrode 22 is electrically connected to the internal electrode portion 121 of the negative internal electrode layer 12 exposed on the other external surface (external surface of the negative electrode) 120 of the ceramic laminate 10.

  Furthermore, the insulation resistance measuring unit 30 measures the insulation resistance of the ceramic layer 13B or the stress relaxation ceramic layer 13A between the positive internal electrode layer 11 and the negative internal electrode layer 12. Specifically, the insulation resistance measuring unit 30 is connected between the negative internal electrode layer 12 adjacent to the stress relaxation ceramic layer 13 and the negative external electrode 22. That is, the electrical connection between the negative internal electrode layer 12 and the negative external electrode 22 in this portion is made through the insulation resistance measuring unit 30.

  The insulation resistance measurement unit 30 includes at least a voltmeter 31 for measuring insulation resistance, and a cutoff switch 32 (connection cutoff unit) that cuts off the connection between the negative internal electrode layer 12 and the negative external electrode 22. . Specifically, the voltmeter 31 is connected in parallel to a resistor in a wiring connecting the negative internal electrode layer 12 and the negative external electrode 22. Thereby, the insulation resistance of the ceramic layer 13 or the stress relaxation ceramic layer 13A between them can be measured from the value of the current flowing between the internal electrode layers 12 and 12 of the negative electrode (parameter indicating insulation resistance). In this way, the ceramic layer having a reduced insulation resistance can be identified using the insulation resistance measurement unit 30.

  Further, the voltmeter 31 is connected to the control device 50 so that an output signal having the voltage value of the current flowing through the resistor can be output to the control device 50. Here, the voltmeter 31 is used to measure the insulation resistance of the ceramic layer 13 between the negative internal electrode layers 12, 12, but if the device configuration can measure this insulation resistance, The apparatus configuration is not limited.

  The cut-off switch 32 is a switch that cuts off the electrical connection between the negative internal electrode layer 12 and the negative external electrode 22, so that the electrical connection is cut off by a control signal from the control device 50. It has become.

  In FIG. 1, the electrical connection between the negative internal electrode layer 12 and the negative external electrode 22 is interrupted by the cutoff switch 32, but as described later, the initial stage of using the multilayer piezoelectric element 1 is used. At the stage, these switches are in the ON state (closed state), and the cutoff operation by the cutoff switch 32 is not performed.

  The control device 50 controls the cutoff operation of the cutoff switch 32 of the insulation resistance measuring unit 30, and is based on an input device 51 that converts a measurement signal from the voltmeter 31 and a signal value converted by the input device 51. An arithmetic unit (CPU) 52 that performs a computation for controlling the shut-off operation, a storage device 53 that stores initial data necessary for the computation, and a control signal for the shut-off operation based on the result computed by the computing device 52 Is output to the cut-off switch 32, and has a hardware configuration including at least the output device 54.

  The calculation device 52 includes an insulation resistance calculation unit 52A, a blocking operation determination unit 52B, and a blocking operation unit 52C as a software configuration. The insulation resistance calculation means 52A is a means for calculating the insulation resistance value of the ceramic layer 13 measured by the insulation resistance measurement unit 30, and the signal value of the voltmeter converted by the input device 51 and read from the storage device 53. The insulation resistance value is calculated based on the data.

  The shut-off operation determination unit 52B determines whether the calculated insulation resistance value is equal to or less than a reference value. This reference value is a value previously input to the storage device 53 and is read from the storage device 53. Further, this reference value is the minimum value of the insulation resistance value of the ceramic layer when the ceramic laminate 10 can be displaced normally, and by measuring the insulation resistance between the internal electrode layers 12 and 12 of the negative electrode, Can be sought.

  The shutoff operation means 52C is for causing the shutoff switch 32 to perform a shutoff operation. When the calculated insulation resistance value is determined to be equal to or less than the reference value, in response to the determination result, the output device 54 sends a control signal for the shutoff operation. It is designed to output.

  The thus configured multilayer piezoelectric element 1 operates as follows. A voltage acts between the pair of external electrodes 21 and 22 according to a voltage output from a power source (not shown). Based on this voltage, an electric field is applied to the ceramic layer 13 between the positive and negative internal electrode layers 11 and 12 and the stress relaxation ceramic layer 13A (hereinafter referred to as a ceramic layer). The ceramic laminate 10 is displaced as a whole by displacement in the stacking direction.

  At this time, the insulation resistance measuring unit 30 measures the insulation resistance of the ceramic layer between the internal electrode layers 12 and 12 of the negative electrode. Specifically, the current value of the voltmeter 31 that is the source of the insulation resistance is measured, and this measurement signal is input to the input device 51 of the control device 50. Then, the insulation resistance calculation means 52A of the calculation device 52 calculates the insulation resistance value from the current value, and the cutoff operation determination means 52B determines whether the calculated insulation resistance value is equal to or less than a reference value.

  At this time, if the insulation resistance value is equal to or less than the reference value, it can be determined that the ceramic layer 13 is internally damaged and the insulation resistance is lowered. Therefore, a control signal is output by the cutoff operation means 52C, and the cutoff switch 32 is turned on. Shut off operation.

  In this way, the electrical connection between the negative internal electrode layer 12 sandwiching the ceramic layer with reduced insulation resistance and the external electrode 22 connected thereto can be cut off. By cutting off the connection, the electric field from the external electrodes 21 and 22 is not applied to the ceramic layer whose insulation resistance is reduced. Therefore, a desired electric field can be applied only to the other healthy ceramic layers. A decrease in the displacement performance of the laminate 10 can be suppressed.

  In particular, the void 15 formed in the stress relaxation ceramic layer 13A is caused by a crack generated from the tip due to repeated displacement of the ceramic laminate 10, and the insulation of the stress relaxation ceramic layers 13A and 13B is caused by the progress of the crack. It tends to decline. However, even in such a case, the connection between the negative internal electrode layer 12 adjacent to the stress relaxation ceramic layer 13A and the negative external electrode 22 can be cut off, so that the laminated piezoelectric element can be more reliably connected. It is possible to suppress the performance degradation of the element.

  Further, by using the control device 50, it is possible to collectively monitor the decrease in the insulation resistance of the ceramic layer whose insulation resistance is being measured, and further, the inside of the negative electrode adjacent to the ceramic layer whose insulation resistance has decreased. The electrical connection between the electrode layer 12 and the negative external electrode 22 can be cut off.

Examples of the present invention will be described below.
(Example)
Using the multilayer piezoelectric element according to the present embodiment, a repeated voltage was applied to the external electrode to repeatedly operate the piezoelectric element. Then, the insulation resistance value of the ceramic laminate of the multilayer piezoelectric element and the displacement of the ceramic laminate with respect to this operating time were measured. If the insulation resistance value falls below the reference value when the multilayer piezoelectric element is operated repeatedly, the cutoff switch connected to the measurement location is activated to cut off the connection between the internal electrode layer and the external electrode. did. The shutoff switch was shut off manually without using a control device. The result is shown in FIG.

(Comparative Examples 1 and 2)
Similar to the example, the multilayer piezoelectric element was operated repeatedly. The difference between the first comparative example and the first embodiment is that the conventional multilayer piezoelectric element shown in FIG. 4 is used, that is, the insulation resistance measuring unit is not provided. Comparative Example 2 is different from Example 1 in that the conventional multilayer piezoelectric element shown in FIG. 5 is used, that is, the insulation resistance measurement unit is not provided, and the ceramic layer provided with a gap is provided. The difference is that a ceramic laminate sandwiched between internal electrode layers of the negative electrode is used. In FIG. 5, the same reference numerals are assigned to the common configurations of the multilayer piezoelectric elements. And the change of the insulation resistance and the displacement amount were measured with respect to these. The result is shown in FIG.

  The operation time shown in FIG. 3 is normalized by the time when the insulation resistance of the multilayer piezoelectric element of Comparative Example 1 starts to decrease, and the insulation resistance is the initial value of the multilayer piezoelectric element of the example. The displacement is normalized by the insulation resistance, and the displacement is normalized by the initial displacement of the ceramic laminate of the example.

[Results and discussion]
The insulation resistance (R) of the multilayer piezoelectric element of the example was less decreased with the passage of operation time than the insulation resistance (R) of Comparative Examples 1 and 2. As the insulation resistance decreased, the displacement (D) of the ceramic laminate decreased.

In addition, in the example and the comparative example 1, the insulation resistance starts decreasing at substantially the same timing, but in the case of the example, the cut-off switch is operated at this timing, so that the stacked piezoelectric element decreases. Insulation resistance recovered. As shown in FIG. 3, in the embodiment, three cutoff switches are operated with a change with time. Thus, in the embodiment, by blocking the electrical connection between the external electrode and the internal electrode layers, the ceramic layers insulation resistance is lowered, the electric field from the external electrodes is not applied. As a result, a desired electric field can be applied only to other healthy ceramic layers, a decrease in insulation resistance as a ceramic laminate can be suppressed, and a decrease in displacement performance of the ceramic laminate can be suppressed. It is thought that it was made.

  In addition, the initial displacement (D) of Comparative Example 2 is smaller than the initial displacement (D) of the example because the electrode sandwiching the ceramic layer in which the slit is formed is the negative electrode, and the ceramic layer during this period This is probably because it is not caused by the displacement of the ceramic laminate.

  From this, since the operation time until the predetermined displacement shown in FIG. 3 is longer than that of Comparative Examples 1 and 2, the multilayer piezoelectric element of the example has an improved life compared to these. It can be said.

  As mentioned above, although embodiment of this invention has been explained in full detail using drawing, a concrete structure is not limited to this embodiment, Even if there is a design change in the range which does not deviate from the gist of the present invention. These are included in the present invention.

  For example, in the present embodiment, the ceramic laminate has a cross-sectional barrel shape formed by forming a pair of planes facing each other on the outer surface of the laminate having a substantially cylindrical shape as shown in FIG. The cross-sectional shape of the body is not limited to the barrel shape of the present example, and may be changed to a polygonal shape such as a quadrangle according to the application and usage conditions.

  In the present embodiment, the shut-off switch is operated using the control device. However, when the ceramic layer where the insulation is likely to be lowered can be specified in advance, the switch may be manually operated. It is.

1 is a schematic cross-sectional view of a multilayer piezoelectric element according to an embodiment. The perspective view of the ceramic laminated body shown in FIG. The figure which showed the result of the evaluation test of the laminated piezoelectric element which concerns on an Example and Comparative Examples 1 and 2. FIG. FIG. 6 is a schematic cross-sectional view of a conventional multilayer piezoelectric element. 4 is a schematic cross-sectional view of a multilayer piezoelectric element according to Comparative Example 2. FIG.

Explanation of symbols

  1: laminated piezoelectric element, 10: ceramic laminate, 11: internal electrode layer of positive electrode, 12: internal electrode layer of negative electrode, 13: ceramic layer, 15: void, 21: external electrode of positive electrode, 22: external of negative electrode Electrode, 30: Insulation resistance measurement unit, 31: Voltmeter, 32: Switch (connection cutoff unit), 50: Control device, 51: Input device, 52: Calculation device (CPU), 52A: Insulation resistance calculation means, 52B: Blocking operation determining means, 52C: Blocking operation means, 53: Storage device, 54: Output device, 111, 121: Internal electrode section, 112, 122: Reserving section

Claims (6)

A ceramic laminate in which positive electrode and negative electrode internal electrode layers are alternately arranged with a ceramic layer interposed therebetween;
Each of the positive electrode and the negative electrode internal electrode layer, and a pair of external electrodes, one of which is electrically connected,
The multilayer piezoelectric element includes an insulation resistance measurement unit that measures an insulation resistance of the ceramic layer between the internal electrode layers having the same polarity.   2. The multilayer piezoelectric element according to claim 1, wherein electrical connection between the internal electrode layer and the external electrode is made through the insulation resistance measuring unit.   The multilayer piezoelectric element according to claim 2, wherein the insulation resistance measurement unit includes a connection blocking unit that blocks the electrical connection between the internal electrode layer and the external electrode.   The ceramic layer includes a stress relaxation ceramic layer in which a gap is formed to relieve stress on the multilayer piezoelectric element, and the internal electrode layer electrically connected to the insulation resistance measurement unit includes the stress relaxation ceramic layer. The multilayer piezoelectric element according to claim 2, wherein the laminated piezoelectric element is an internal electrode layer adjacent to the layer.   The multilayer piezoelectric element according to claim 2, wherein the internal electrode layer electrically connected to the insulation resistance measurement unit is a negative internal electrode layer.   The multi-layer piezoelectric element further includes a control device that controls a blocking operation of the connection blocking unit, and the control device calculates an insulation resistance value based on a value measured by the insulation resistance measurement unit. The multilayer piezoelectric element according to any one of claims 3 to 5, further comprising: a calculation unit; and a blocking operation unit that causes the connection blocking unit to perform a blocking operation based on the insulation resistance value.

Images