JP5990082B2 - Piezoelectric constant measuring device - Google Patents

Description

  The present invention relates to a piezoelectric constant measuring apparatus used for measuring a piezoelectric constant of a piezoelectric member.

  Patent Document 1 describes a measuring device that measures the piezoelectric characteristics (piezoelectric constant) of a piezoelectric sample (piezoelectric member).

  And in this measuring apparatus, the lower end part vicinity of a piezoelectric material sample is fixed, and the upper end part side of a piezoelectric material sample is made self-supporting. Then, a voltage is applied to the piezoelectric sample, and the calculation control unit calculates the piezoelectric constant d31 and the piezoelectric constant d14 based on the displacement on the upper end side of the piezoelectric sample generated thereby and the voltage applied to the piezoelectric sample. (Displacement method).

JP2012-163502A

  However, in the conventional configuration, when the piezoelectric member to be measured is plate-like (film-like), it is difficult to stand the piezoelectric member, and even if the displacement on the upper end side of the piezoelectric member is measured, the displacement is accurately detected. Could not be measured.

  On the other hand, there is known a piezoelectric constant measuring device that measures a piezoelectric constant d33 of a piezoelectric member by pressing a plate-like piezoelectric member in the plate thickness direction by a pressing force applied to the piezoelectric member and a charge generated in the piezoelectric member. ing.

An object of the present invention is to accurately calculate the piezoelectric constant d31 and the piezoelectric constant d14 of a plate-like (film-like) piezoelectric member using the basic configuration of a piezoelectric constant measuring device that measures the piezoelectric constant d33 of the piezoelectric member. It is.

  According to a first aspect of the present invention, there is provided a piezoelectric constant measuring apparatus according to the first aspect, wherein one end portion of a plate-like piezoelectric member is gripped at one end side and the other end side is disposed on the opposite side with respect to the one end side. A jig, a second jig that grips the other end of the piezoelectric member at one end and the other end is disposed on the opposite side of the piezoelectric member with respect to the one end, and the other end of the first jig A movable member that applies a tensile force to the piezoelectric member by bringing the side and the other end of the second jig close to each other, and an electric charge generated in the piezoelectric member when the movable member applies a tensile force to the piezoelectric member Charge detecting means for detecting the pressure, and calculating means for calculating the piezoelectric constant of the piezoelectric member based on the tensile force applied to the piezoelectric member by the movable member and the charge detected by the charge detecting means. Features.

  According to the above configuration, the first jig grips one end portion of the piezoelectric member at one end side, and the other end side of the first jig is disposed on the opposite side of the piezoelectric member with respect to the one end side. The second jig holds the other end portion of the piezoelectric member at one end side, and the other end side of the second jig is arranged on the opposite side of the piezoelectric member with respect to the one end side.

  Then, the movable member applies a tensile force to the plate-like piezoelectric member by bringing the other end side of the first jig close to the other end side of the second jig.

  That is, a tensile force is applied to the piezoelectric member by bringing the other end of the first jig and the other end of the second jig close to each other. That is, the approaching force (compressing force) is converted into a tensile force.

In this way, the basic configuration of the piezoelectric constant measuring apparatus that measures the piezoelectric constant d33 of the piezoelectric member by compressing the plate-like piezoelectric member from the plate thickness direction by providing the configuration for converting the compressing force into the tensile force. By using and applying a tensile force to the piezoelectric member, the piezoelectric constant d31 and the piezoelectric constant d14 of the plate-like piezoelectric member can be accurately calculated.

  A piezoelectric constant measuring apparatus according to a second aspect of the present invention is the piezoelectric constant measuring apparatus according to the first aspect, wherein the first jig is detachable while supporting the other end of the first jig. A second support member that supports the other end side of the second jig and that can be attached to and detached from the second jig, and the movable member includes the first support member and the first jig. By bringing the two support members close to each other, the other end side of the first jig and the other end side of the second jig are brought close to each other.

  According to the above configuration, the first jig can be attached to and detached from the first support member, and the second jig can be attached to and detached from the second support member. Accordingly, the piezoelectric constant d33 of the piezoelectric member can be easily measured simply by replacing the jig.

  A piezoelectric constant measuring apparatus according to a third aspect of the present invention is the piezoelectric constant measuring apparatus according to the second aspect, wherein the first support member and one end side of the second jig holding the other end of the piezoelectric member. The one end side of the first jig holding the one end portion of the piezoelectric member and the second support member are arranged in the pulling direction in which the piezoelectric member is pulled in this order.

  According to the above configuration, the first support member, the one end side of the second jig that holds the other end of the piezoelectric member, the one end side of the first jig that holds the one end of the piezoelectric member, and the second support member Are arranged in the pulling direction in which the piezoelectric members are pulled in this order.

  With this configuration, the force that causes the movable member to bring the first support member and the second support member close to each other is efficiently converted into a tensile force that pulls the piezoelectric member.

According to the present invention, the piezoelectric constant d31 and the piezoelectric constant d14 of a plate-like (film-like) piezoelectric member are accurately calculated using the basic configuration of the piezoelectric constant measuring device that measures the piezoelectric constant d33 of the piezoelectric member. Can do.

It is the schematic block diagram which showed the piezoelectric constant measuring apparatus which concerns on embodiment of this invention. It is the perspective view which showed the 1st jig, the 2nd jig, etc. which were used for the piezoelectric constant measuring apparatus which concerns on embodiment of this invention. It is the perspective view which showed the 1st holding part, the 2nd holding part, etc. which were used for the piezoelectric constant measuring apparatus which concerns on embodiment of this invention. It is sectional drawing which showed the 1st holding part, the 2nd holding part, etc. which were used for the piezoelectric constant measuring apparatus which concerns on embodiment of this invention. It is the front view which showed the piezoelectric member etc. which are measured by the piezoelectric constant measuring apparatus which concerns on embodiment of this invention. FIG. 3 is a schematic configuration diagram showing a piezoelectric constant measuring device for measuring a piezoelectric constant d33, using the basic configuration of the piezoelectric constant measuring device according to the embodiment of the present invention. It is sectional drawing which showed the piezoelectric constant measuring device for measuring the piezoelectric constant d33 using the basic composition of the piezoelectric constant measuring device which concerns on embodiment of this invention.

  An example of a piezoelectric constant measuring apparatus 10 according to an embodiment of the present invention and a piezoelectric member 100 whose piezoelectric constant is calculated by the piezoelectric constant measuring apparatus 10 will be described with reference to FIGS. In addition, arrow UP in a figure shows the upper direction of a perpendicular direction.

(overall structure)
As shown in FIG. 1, the piezoelectric constant measuring device 10 includes an external force applying system 12 that applies a tensile force to a long rectangular plate-shaped (film-shaped) piezoelectric member 100, and the external force applying system 12 pulls the piezoelectric member 100. Detected by the charge detection unit 14 as an example of charge detection means for detecting the charge generated in the piezoelectric member 100 by applying a force, the tensile force applied to the piezoelectric member 100 by the external force applying system 12, and the charge detection unit 14 And a calculation unit 16 as an example of a calculation unit that calculates the piezoelectric constant d31 and the piezoelectric constant d14 of the piezoelectric member 100 based on the generated charges.

(Piezoelectric member)
First, the piezoelectric member 100 will be described.

  The piezoelectric member 100 (so-called piezo) is a member that generates a charge (voltage) when a force such as vibration or pressure is applied, and conversely expands and contracts when a charge (voltage) is applied. As described above, the basic structure is a member in which the piezoelectric body 100A is sandwiched between two electrodes 100B.

  The piezoelectric body 100A of the piezoelectric member 100 is a long rectangular piece formed of a polylactic acid film that has been subjected to stretching treatment. As shown in FIG. 5, the stretching direction (arrow C in the figure) is viewed from the thickness direction. Is cut out with an angle of 45 ° as the longitudinal direction.

  In the present embodiment, the dimensions of the portion to which the tensile force is applied in the piezoelectric member 100 are as follows. As shown in FIGS. 3 and 5, the longitudinal direction L [mm], the lateral direction W [mm], the thickness The vertical direction is t [mm].

(External force application system)
Next, the external force application system 12 will be described.

  As shown in FIG. 1, the external force application system 12 includes a first jig 20 that grips one end portion (upper end portion in the drawing) of the piezoelectric member 100 at one end side, and a first jig 20 that supports the other end side of the first jig 20. One support member 22, a second jig 24 that grips the other end (lower end in the figure) of the piezoelectric member 100 at one end, and a second support member 26 that supports the other end of the second jig 24. I have.

  Furthermore, the external force application system 12 moves the first support member 22 upward in the vertical direction and moves the first support member 22 close to the second support member 26 to apply a tensile force to the piezoelectric member 100. 30 and an external force applying unit 32 that operates the movable member 30.

[First jig]
First, the first jig 20 will be described.

  The first jig 20 is detachably attached to the first support member 22. Further, as shown in FIG. 1, the first jig 20 has a U shape in which one side (left side shown in FIG. 1) in the horizontal direction of the apparatus width direction (H direction in the drawing) is opened. One main body portion 36 and a first grip portion 38 (see FIG. 2) that grips one end portion of the piezoelectric member 100 are provided.

[First body part]
The first main body portion 36 is an insulator and includes a horizontal portion 36A (an example of the other end side) extending in the apparatus width direction as shown in FIG. The first main body 36 is disposed above the horizontal portion 36A and on the opposite side of the horizontal portion 36A with the piezoelectric member 100 interposed therebetween, and is narrower than the horizontal portion 36A so as to be in the device width direction. And a horizontal portion 36B (an example of one end side) to which the first grip portion 38 is fixed by a fixture (not shown).

  Further, the first main body portion 36 includes a connecting portion 36C that extends in the vertical direction and connects one end portion (right end portion in the drawing) of the horizontal portion 36A and one end portion (right end portion in the drawing) of the horizontal portion 36B. . The horizontal portion 36 </ b> A is supported by the upper end portion of the first support member 22.

  Here, as the first support member 22 moves upward, the first main body 36 is deformed so that the dimension between the horizontal portion 36B to which the first gripping portion 38 is fixed and the horizontal portion 36A becomes narrow. It is possible to end up. However, in order to effectively apply a tensile force to the piezoelectric member 100, the material of the first main body portion 36, the cross-sectional shape of each part, and the like are determined so as to suppress deformation of the first main body portion 36 (stiffness). Is high).

[First gripping part]
As shown in FIGS. 3 and 4, the first gripping portion 38 sandwiches one end portion of the piezoelectric member 100 and makes a pair of gripping plates 38 </ b> A and a pair of gripping plates 38 </ b> A close to each other. And two screws 38B for holding one end of the member 100 by a pair of holding plates 38A.

  Furthermore, as shown in FIG. 4, the first grip 38 is L-shaped when viewed from the device width direction, is a conductor that contacts one electrode 100 </ b> B of the piezoelectric member 100, and the charge detector 14. A conductive member 38 </ b> C connected to each other through a conductive wire 40 is provided.

[Second jig]
Next, the second jig 24 will be described.

  The second jig 24 is detachably attached to the second support member 26. And the 2nd jig 24 is the 2nd main-body part made into the reverse U shape by which the other side (right side shown in FIG. 1) of the apparatus width direction (H direction in a figure) was open | released, as FIG. 1 shows. 46 and a second grip 48 (see FIG. 2) for gripping the other end of the piezoelectric member 100.

[Second body part]
As shown in FIG. 2, the second main body portion 46 is provided with a horizontal portion 46A (an example of the other end side) that is disposed above the horizontal portion 36B and extends in the apparatus width direction. The second main body 46 is disposed on the opposite side of the horizontal part 46A with the piezoelectric member 100 therebetween and above the horizontal part 36A, and is narrower than the horizontal part 46A in the apparatus width direction. The horizontal part 46B (an example of one end side) is provided that extends and the second gripping part 48 is fixed by a fixture (not shown).

  Further, the second main body portion 46 includes a connecting portion 46C that extends in the vertical direction and connects one end portion (left end portion in the drawing) of the horizontal portion 46A and one end portion (right end portion in the drawing) of the horizontal portion 46B. . The horizontal portion 46 </ b> A is supported by the lower end portion of the second support member 26.

  Here, in order to apply a tensile force to the piezoelectric member 100, the second main body portion 46 is deformed so that the dimension between the horizontal portion 46B to which the second gripping portion 48 is fixed and the horizontal portion 46A becomes narrow. It can be considered. However, in order to effectively apply a tensile force to the piezoelectric member 100, the material of the second main body portion 46, the cross-sectional shape of each part, etc. are determined so as to suppress the deformation of the second main body portion 46 (rigidity). Is high).

[Second gripping part]
As shown in FIGS. 3 and 4, the second gripping portion 48 sandwiches the other end portion of the piezoelectric member 100 and makes a pair of gripping plates 48 </ b> A and an pair of gripping plates 48 </ b> A close to each other. And two screws 48B for gripping the other end of the piezoelectric member 100 by a pair of gripping plates 48A.

  Further, as shown in FIG. 4, the second grip 48 is L-shaped when viewed from the device width direction, is a conductor that contacts the other electrode 100 </ b> B of the piezoelectric member 100, and the charge detector 14. 48C is provided with a conductive member 48C connected through a conductive wire 50.

[First support member / movable member]
Next, the first support member 22 and the movable member 30 will be described.

  As shown in FIG. 2, the first support member 22 is a member having a circular cross section extending in the vertical direction, and supports the horizontal portion 36 </ b> A of the first main body portion 36 at the upper end portion of the first support member 22. . Furthermore, a movable member 30 that connects the first support member 22 and the second support member 26 by moving the first support member 22 in the vertical direction is connected to the lower end portion of the first support member 22.

(Second support member)
Next, the second support member 26 will be described.

  The second support member 26 is disposed to face the first support member 22 in the vertical direction, and as shown in FIG. 2, the second support member 26 is a member having a circular cross section extending in the vertical direction. And the upper end part of the 2nd support member 26 is being fixed to the frame member 52 (refer FIG. 1).

In the above configuration, the first support member 22, the second gripping portion 48 (an example of one end side of the second jig 24), the first gripping portion 38 (an example of one end side of the first jig 20 ), the second Each member is arranged so as to be aligned with the support member 26 in this order in the vertical direction (the tensile direction in which the piezoelectric member 100 is pulled (the vector direction of the tensile force)).

(Configuration for measuring piezoelectric constant d33)
Next, the piezoelectric constant measuring apparatus 102 that replaces the first jig 20 and the second jig 24 of the piezoelectric constant measuring apparatus 10 and measures the piezoelectric constant d33 of the piezoelectric member 100 using the basic configuration of the piezoelectric constant measuring apparatus 10 will be described. To do. Specifically, the difference between the piezoelectric constant measuring device 10 and the piezoelectric constant measuring device 102 is a jig attached to the first support member 22 and the second support member 26.

  In the piezoelectric constant measuring apparatus 102, the piezoelectric member 100 is sandwiched between the third jig 110 and the fourth jig 120 from the plate thickness direction as shown in FIGS.

  Specifically, the third jig 110 is an insulator and is detachably attached to the upper end portion of the first support member 22, and is a plate-like member whose plate surface faces the vertical direction. Further, as shown in FIG. 7, the third jig 110 is L-shaped when viewed from the device width direction, is a conductor that contacts one electrode 100 </ b> B of the piezoelectric member 100, and is connected to the charge detection unit 14. A conductive member 112 connected via the conductive wire 40 is provided.

  On the other hand, the fourth jig 120 is an insulator and is detachably attached to the lower end portion of the second support member 26. As shown in FIG. 6 and FIG. 7, the plate surface has a plate shape facing the vertical direction. It is a member. Further, as shown in FIG. 7, the fourth jig 120 is L-shaped when viewed from the device width direction, is a conductor that contacts the other electrode 100 </ b> B of the piezoelectric member 100, and is connected to the charge detection unit 14. A conductive member 122 connected via the conductive wire 50 is provided.

  When the piezoelectric constant d33 is measured (calculated) using the piezoelectric constant measuring apparatus 102, as shown in FIG. 6, the external force applying unit 32 operates the movable member 30 and moves the first support member 22 upward. Move. By moving the first support member 22 upward, the piezoelectric member 100 is sandwiched between the third jig 110 and the fourth jig 120 from the thickness direction. Thereby, the compression force F1 [N] compressed in the plate thickness direction acts on the piezoelectric member 100.

  On the other hand, when the compressive force F1 [N] acts on the piezoelectric member 100, a charge Q1 [C] is generated in the piezoelectric member 100, and the charge detection unit 14 detects the charge Q1 [C].

  Further, the calculation unit 16 uses the following formula (1) to calculate the piezoelectricity from the charge Q1 [C] detected by the charge detection unit 14 and the compression force F1 [N] applied to the piezoelectric member 100 by the movable member 30. A constant d33 is calculated.

d33 [C / N] = Q1 / F1 (1)
(Operation and effect of the piezoelectric constant measuring apparatus 10)
Next, a method (action) for calculating the piezoelectric constant d31 and the piezoelectric constant d14 using the piezoelectric constant measuring apparatus 10 will be described. In other words, a method (action) for calculating the piezoelectric constant d31 and the piezoelectric constant d14 using an apparatus in which the first jig 20 and the second jig 24 are attached to the basic configuration of the piezoelectric constant measuring apparatus 102 described above will be described.

  When calculating (measuring) the piezoelectric constant d31 and the piezoelectric constant d14 using the piezoelectric constant measuring apparatus 10, the external force applying unit 32 operates the movable member 30 and the first support member 22 as shown in FIG. Is moved upward. The first jig 20 moves upward by moving the first support member 22 upward. Accordingly, one end portion of the piezoelectric member 100 is pulled upward, and a tensile force F2 [N] that is pulled in the vertical direction acts on the piezoelectric member 100.

  On the other hand, when the tensile force F2 [N] acts on the piezoelectric member 100, a charge Q2 [C] is generated in the piezoelectric member 100, and the charge detection unit 14 detects this charge Q2 [C].

  Further, the calculation unit 16 uses the following formula (2) to calculate the piezoelectricity from the charge Q2 [C] detected by the charge detection unit 14 and the tensile force F2 [N] applied to the piezoelectric member 100 by the movable member 30. A constant d31 is calculated.

d31 [C / N] = Q2 / F2 × ((film thickness t) / (chuck distance L)) (2)
Further, the calculation unit 16 calculates the piezoelectric constant d14 from the calculated piezoelectric constant d31 [C / N] using the following formula (3): d14 [C / N] = 2 · d31 .... (3)
As described above, by applying a tensile force to the plate-like (film-like) piezoelectric member 100, the piezoelectric constant d31 and the piezoelectric constant d14 of the piezoelectric member 100 are calculated (charge method). For this reason, compared with the case where a plate-like (film-like) piezoelectric member is self-supported and the piezoelectric constant d31 and the piezoelectric constant d14 are calculated by a displacement method, a piezoelectric member that is difficult to stand by, for example, an organic polymer such as polylactic acid. Therefore, the piezoelectric constant d31 and the piezoelectric constant d14 can be accurately calculated.

  In other words, the piezoelectric constant d31 and the piezoelectric constant d14 of the piezoelectric member 100 can be accurately calculated using the basic configuration of the piezoelectric constant measuring apparatus 102 that measures the piezoelectric constant d33 of the plate-like piezoelectric member 100.

  Further, as described above, the first jig 20 can be attached to and detached from the first support member 22, and the second jig 24 can be attached to and detached from the second support member 26. For this reason, the piezoelectric constant d33 of the piezoelectric member 100 can be easily measured only by exchanging the jig.

  Further, as described above, the first support member 22, the second grip portion 48, the first grip portion 38, and the second support member 26 are arranged in the vertical direction in this order. For this reason, compared with the case where these members are meandering in the vertical direction, the force that the movable member 30 brings the first support member 22 and the second support member 26 close together pulls the piezoelectric member 100. Efficiently converted to tensile force.

  Further, as described above, since only the first support member 22 is moved to generate a tensile force on the piezoelectric member 100, for example, both the first support member 22 and the second support member 26 are provided. Compared with the structure to move, the tensile force which arises in the piezoelectric member 100 can be controlled easily.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments can be taken within the scope of the present invention. This will be apparent to those skilled in the art. For example, in the above-described embodiment, the piezoelectric member 100 is pulled along the vertical direction, but the piezoelectric member 100 may be pulled along another direction.

The piezoelectric body is not limited to a polylactic acid film that has been subjected to stretching treatment, and may be a film obtained by stretching a helical chiral polymer having optical activity such as a polypeptide. The shape of the first jig and the second jig is not limited to U-shaped, one end of the piezoelectric member 100 is gripped at one end of the jig, the piezoelectric member 100 and the other end portion of the jig is in between the piezoelectric member 100 Any shape may be used as long as the jig is not in contact with the piezoelectric material other than the one end of the jig.

Although not particularly described in the above embodiment, the first main body portion when the free end portion of the horizontal portion 36A and the free end portion of the horizontal portion 36B are connected by another member to apply a tensile force. The deformation of 36 may be suppressed. Similarly, the free end portion of the horizontal portion 46A and the free end portion of the horizontal portion 46B may be connected by another member to suppress deformation of the second main body portion 46 when a tensile force is applied. Thereby, the piezoelectric constant d31 and the piezoelectric constant d14 can be calculated with higher accuracy.

10 Piezoelectric Constant Measuring Device 14 Charge Detection Unit (Example of Charge Detection Unit)
16 Calculation unit (an example of calculation means)
20 First jig 22 First support member 24 Second jig 26 Second support member 30 Movable member

Claims (3)

A first jig that grips one end of a plate-like piezoelectric member on one end side and the other end is disposed on the opposite side of the piezoelectric member with respect to the one end side;
A second jig in which the other end of the piezoelectric member is gripped at one end and the other end is disposed on the opposite side of the piezoelectric member with respect to the one end.
A movable member that applies a tensile force to the piezoelectric member by bringing the other end of the first jig and the other end of the second jig close to each other;
Charge detecting means for detecting charges generated in the piezoelectric member by applying a tensile force to the piezoelectric member by the movable member;
Calculating means for calculating a piezoelectric constant of the piezoelectric member based on the tensile force applied to the piezoelectric member by the movable member and the charge detected by the charge detecting means;
A piezoelectric constant measuring apparatus comprising: While supporting the other end side of the first jig, the first support member to which the first jig can be attached and detached,
A second support member that supports the other end side of the second jig and that allows the second jig to be attached and detached.
2. The movable member according to claim 1, wherein the movable member brings the first support member and the second support member close to each other, thereby bringing the other end side of the first jig close to the other end side of the second jig. Piezoelectric constant measuring device.   The first support member, one end side of the second jig holding the other end of the piezoelectric member, one end side of the first jig holding one end of the piezoelectric member, and the second support member The piezoelectric constant measuring device according to claim 2, wherein the piezoelectric members are arranged in a tensile direction in which the piezoelectric members are pulled in this order.

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