JP2011205861A - Piezoelectric actuator and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric actuator enabling precise operation, and to provide a method of manufacturing the piezoelectric actuator.SOLUTION: On the upper surface of the central part 103 of a dielectric 10, first electrodes 11, and second electrodes 12 to receive a voltage of polarity different from that of the first electrodes 11 are alternatively arranged and formed in the lateral direction. On the bottom surface of the central part 103, third electrodes 13, and fourth electrodes 14 to receive the voltage of polarity different from that of the third electrodes 13 are alternatively arranged and formed in the lateral direction. The first and second electrodes 11, 12 do not face the third and fourth electrodes 13, 14 formed on the bottom surface of the dielectric 10. The polarization direction in first gap parts 104 is a direction from the first electrodes 11 toward the second electrodes 12. The polarization direction in second gap parts 105 is a direction from the third electrodes 13 toward the fourth electrodes 14. The piezoelectric actuator 1 is vibrated by applying the voltage to the first to fourth electrodes 11, 12, 13, 14.

Description

  The present invention relates to a piezoelectric actuator having an electrode on a dielectric and a method for manufacturing the same.

  Conventionally, a piezoelectric actuator provided with an electrode on a dielectric is known. For example, in the piezoelectric actuator described in Patent Document 1, one electrode film is provided on one surface of a piezoelectric element that is a dielectric so as to cover the entire surface, and is connected to the ground. Also, two electrode films are provided side by side on the other surface of the piezoelectric element. The piezoelectric element vibrates by applying voltages having a phase difference of 90 ° to the two electrode films. Using the vibration of the piezoelectric element, the tip of the finger provided on the piezoelectric element is driven to draw a circular motion, and the movable body in contact with the finger can be moved.

JP 2006-271167 A

  However, in the above-described piezoelectric actuator, the electrodes provided on the piezoelectric element are opposed to each other with the piezoelectric element interposed therebetween. For this reason, parasitic capacitance is generated between the opposing electrodes. Due to this parasitic capacitance, there is a problem that the accuracy in controlling the vibration of the piezoelectric element by applying a voltage to the electrode film is lowered, and the operation of the piezoelectric actuator becomes unstable.

  An object of the present invention is to provide a piezoelectric actuator capable of operating with high accuracy and a method for manufacturing the same.

  A piezoelectric actuator according to a first aspect of the present invention includes a plurality of first electrodes provided on one surface among surfaces facing each other in a thickness direction of a polarized dielectric, and provided on the one surface, A plurality of second electrodes to which a voltage having a polarity different from that of the first electrode is applied; a plurality of third electrodes provided on the other surface of the dielectric facing the one surface; and the other surface. A plurality of fourth electrodes to which a voltage having a polarity different from that of the third electrode is applied, wherein the first electrode and the second electrode are alternately arranged at predetermined intervals on the one surface. The third electrode and the fourth electrode are provided alternately at positions opposite to the plurality of intervals between the first electrode and the second electrode on the other surface. The polarization direction of the polarized dielectric is between the first electrode and the second electrode. In the portion extending in the thickness direction of the dielectric, the direction is from the first electrode toward the second electrode, and the thickness direction of the dielectric between the third electrode and the fourth electrode. In the portion, the direction is from each third electrode toward each fourth electrode.

  In this case, the first electrode and the second electrode provided on one surface do not face the third electrode and the fourth electrode provided on the other surface. For this reason, parasitic capacitance is unlikely to occur between the electrode provided on one surface and the electrode provided on the other surface. Therefore, the piezoelectric actuator can be operated with high accuracy.

  In the piezoelectric actuator, the first wiring provided on the one surface side of the dielectric and connecting the plurality of first electrodes; the first wiring provided on the one surface side of the dielectric; A second wiring connecting electrodes, provided on the other surface side of the dielectric, a third wiring connecting the plurality of third electrodes, provided on the other surface side of the dielectric, You may provide the 4th wiring which connects a some 4th electrode.

  In this case, the number of electrical wires connected from the outside in order to apply a voltage to the first to fourth electrodes on the dielectric may be four for connecting the first to fourth wires. For this reason, it is not necessary to individually connect electric wiring from the outside of the dielectric to the plurality of first to fourth electrodes.

  In the piezoelectric actuator, the thickness of the dielectric in the portion where the first wiring and the second wiring are opposed to the third wiring and the fourth wiring with the dielectric interposed therebetween is the same as that of the dielectric. It may be larger than the thickness of the portion.

  In this case, since the thickness of the portion where the first and second wirings provided on one surface of the dielectric are opposed to the third and fourth wirings provided on the other surface is large, parasitic capacitance is unlikely to occur. . For this reason, the piezoelectric actuator can be operated with high accuracy even when the first and second wirings are opposite to the third and fourth wirings on the dielectric.

  The piezoelectric actuator manufacturing method according to the second aspect of the present invention includes a polarization step of polarizing a dielectric, a plurality of first electrodes on one surface of the dielectric, and a polarity different from that of the first electrode. A first forming step of alternately arranging a plurality of second electrodes to which a voltage is applied at a predetermined interval; and the first electrode and the first electrode on the other surface facing the one surface of the dielectric. A second forming step of alternately forming a plurality of third electrodes and fourth electrodes to which a voltage having a polarity different from that of the third electrode is applied at positions facing the plurality of intervals between the two electrodes. The polarization direction of the dielectric material polarized by the polarization step is from the first electrode in a portion across the thickness direction of the dielectric material between the first electrode and the second electrode. The direction toward each of the second electrodes, the third electrode and the fourth electrode In the dielectric portion across the thickness direction of between poles, the a direction toward the respective fourth electrodes from each third electrode.

  In this case, it is possible to manufacture a piezoelectric actuator that hardly generates parasitic capacitance and can operate with high accuracy.

  According to a third aspect of the present invention, there is provided a piezoelectric actuator manufacturing method comprising: a plurality of first electrodes; and a plurality of second electrodes to which a voltage having a polarity different from that of the first electrode is applied to a plate-like substrate. A first forming step of alternately arranging at predetermined intervals, a dielectric forming step of forming a dielectric so as to cover the first electrode and the second electrode formed in the first forming step; A polarization step for polarizing a dielectric, and a plurality of the gaps between the first electrode and the second electrode on the other surface of the dielectric facing the one surface that is the substrate-side surface A second forming step of alternately forming a third electrode and a plurality of fourth electrodes to which a voltage having a polarity different from that of the third electrode is applied, and polarized by the polarization step. The polarization direction of the dielectric is determined between the first electrode and the second electrode. In the thickness direction of the dielectric, the direction from the first electrode to the second electrode, and the thickness direction of the dielectric between the third electrode and the fourth electrode. In the extending portion, the direction is from each third electrode toward each fourth electrode.

  In this case, it is possible to manufacture a piezoelectric actuator that hardly generates parasitic capacitance and can operate with high accuracy.

  In the manufacturing method of the piezoelectric actuator, the second forming step includes a photoresist coating step of coating a photoresist on the other surface of the dielectric, and irradiating light from the one surface side, and the photoresist An exposure step of exposing a plurality of positions facing the gaps between the first electrode and the second electrode, and replacing the photoresist with a position corresponding to the exposed portion of the photoresist. And an electrode forming step of forming the third electrode and the fourth electrode.

  In this case, the wiring pattern of the third electrode and the fourth electrode is determined by the first electrode and the second electrode. For this reason, since the first electrode and the second electrode are formed so as not to face the third electrode and the fourth electrode, generation of parasitic capacitance is prevented, and the piezoelectric actuator can be operated with high accuracy. .

  In the manufacturing method of the piezoelectric actuator, a first wiring that connects the plurality of first electrodes and a second wiring that connects the plurality of second electrodes are formed on the one surface side of the dielectric. A fourth formation for forming a third wiring, a third wiring for connecting the plurality of third electrodes, and a fourth wiring for connecting the plurality of fourth electrodes on the other surface side of the dielectric; And a process.

  In this case, the number of electrical wires connected from the outside in order to apply a voltage to the first to fourth electrodes on the dielectric may be four for connecting the first to fourth wires. For this reason, it is not necessary to individually connect electric wiring from the outside of the dielectric to the plurality of first to fourth electrodes.

  In the manufacturing method of the piezoelectric actuator, the thickness of the dielectric in the portion where the first wiring and the second wiring are opposed to the third wiring and the fourth wiring with the dielectric sandwiched therebetween, It may be larger than the thickness of the other part of the dielectric.

  In this case, since the thickness of the portion where the first and second wirings provided on one surface of the dielectric are opposed to the third and fourth wirings provided on the other surface is large, parasitic capacitance is unlikely to occur. . Therefore, a piezoelectric actuator that operates with high accuracy can be manufactured even when the first and second wirings and the third and fourth wirings are formed on the dielectric.

1 is a perspective view of a piezoelectric actuator 1. FIG. It is arrow direction sectional drawing in the II line | wire of FIG. FIG. 2 is a cross-sectional view in the direction of the arrow in the II line of FIG. 1 when the piezoelectric actuator 1 vibrates. FIG. 2 is a cross-sectional view in the direction of the arrow in the II line of FIG. 1 when the piezoelectric actuator 1 vibrates. 3 is a flowchart showing a manufacturing process of the piezoelectric actuator 1. FIG. 2 is a sectional view taken along the line II in FIG. 1 showing a manufacturing process of the piezoelectric actuator 1. FIG. 2 is a sectional view taken along the line II in FIG. 1 showing a manufacturing process of the piezoelectric actuator 1. FIG. 2 is a sectional view taken along the line II-II in FIG. 1 showing a manufacturing process of the piezoelectric actuator 1. FIG. 2 is a sectional view taken along the line II-II in FIG. 1 showing a manufacturing process of the piezoelectric actuator 1. 2 is a perspective view of a piezoelectric actuator 2. FIG. It is arrow direction sectional drawing in the III-III line of FIG. FIG. 11 is a cross-sectional view in the direction of the arrows along the line III-III in FIG. 10 when the piezoelectric actuator 2 vibrates. FIG. 11 is a cross-sectional view in the direction of the arrows along the line III-III in FIG. 10 when the piezoelectric actuator 2 vibrates. 3 is a flowchart showing a manufacturing process of the piezoelectric actuator 2. FIG. 11 is a sectional view taken along the line III-III in FIG. 10 showing a manufacturing process of the piezoelectric actuator 2. FIG. 11 is a sectional view taken along the line III-III in FIG. 10 showing a manufacturing process of the piezoelectric actuator 2. FIG. 11 is a sectional view taken along the line IV-IV in FIG. 10 showing a manufacturing process of the piezoelectric actuator 2. FIG. 11 is a sectional view taken along the line IV-IV in FIG. 10 showing a manufacturing process of the piezoelectric actuator 2.

(First embodiment)
Hereinafter, a piezoelectric actuator 1 embodying a piezoelectric actuator according to the present invention and a manufacturing method thereof will be described with reference to the drawings. These drawings are used to explain the technical features that can be adopted by the present invention, and the configuration of the piezoelectric actuators described is not intended to be limited only to them, but merely illustrative examples. It is.

  First, the overall configuration of the piezoelectric actuator 1 will be described with reference to FIGS. 1 and 2. In the following description, the upper side in FIG. 1 is the upper side of the piezoelectric actuator 1, and the lower side of the paper is the lower side of the piezoelectric actuator 1. The lower left side of FIG. 1 is the front side of the piezoelectric actuator 1, and the upper right side of the paper is the rear side of the piezoelectric actuator 1. The lower right side of the drawing in FIG. 1 is the right side of the piezoelectric actuator 1, and the upper left side of the drawing is the left side of the piezoelectric actuator 1.

  As shown in FIGS. 1 and 2, the piezoelectric actuator 1 includes a dielectric 10 having a square shape in plan view. The dielectric 10 includes a front end portion 101, a rear end portion 102, and a central portion 103. The central portion 103 is a portion between the front end portion 101 and the rear end portion 102. In the dielectric 10, the vertical thickness of the front end portion 101 and the rear end portion 102 is formed to be larger than the vertical thickness of the central portion 103.

  On the upper surface of the central portion 103, a plurality of first electrodes 11 and a plurality of second electrodes 12 to which a voltage having a polarity different from that of the first electrode 11 is applied are left and right at a predetermined interval (for example, 1 mm). Are arranged alternately. More specifically, the first electrode 11 and the second electrode 12 are arranged on the left side of the piezoelectric actuator 1 from the first electrode 11, the second electrode 12, the first electrode 11, the second electrode 12, the first electrode 11, and the second electrode 12. The electrodes 12 are arranged in the order. The first electrode 11 and the second electrode 12 each extend in the front-rear direction on the upper surface of the central portion 103. A portion extending in the vertical direction of the dielectric 10 between the first electrode 11 and the second electrode 12 is referred to as a first spacing portion 104.

  As shown in FIG. 2, a third electrode 13 and a fourth electrode 14 to which a voltage having a polarity different from that of the third electrode 13 is applied to the bottom surface of the central portion 103 are a plurality of first spacing portions 104. On the opposite bottom surface, they are provided alternately in the left-right direction. More specifically, the third electrode 13 and the fourth electrode 14 are arranged in the order of the fourth electrode 14, the third electrode 13, the fourth electrode 14, the third electrode 13, and the fourth electrode 14 from the left side of the piezoelectric actuator 1. Are lined up. The third electrode 13 and the fourth electrode 14 extend in the front-rear direction on the bottom surface of the central portion 103, respectively. The third electrode 13 and the fourth electrode 14 are not provided below the first electrode 11 and the second electrode 12 provided on the upper surface of the central portion 103. A portion extending in the vertical direction of the dielectric 10 in a portion where the third electrode 13 and the fourth electrode 14 are not provided is referred to as a second spacing portion 105. That is, the first electrode 11 and the second electrode 12 are formed on the upper side of the second interval portion 105, and the third electrode 13 and the fourth electrode 14 are formed on the lower side of the first interval portion 104. ing. In the present embodiment, the first to fourth electrodes 11, 12, 13, 14, the first spacing portion 104, and the second spacing portion 105 all have the same width (length in the left-right direction, for example, 1 mm). Is formed.

  As shown in FIG. 1, the first wiring 111 is provided on the upper surface of the front end portion 101 and is connected to all the first electrodes 11. A second wiring 121 is provided on the upper surface of the rear end portion 102 and connected to all the second electrodes 12. Similarly, a third wiring 131 is provided on the bottom surface of the front end portion 101 and is connected to all the third electrodes 13. A fourth wiring 141 is provided on the bottom surface of the rear end portion 102 and is connected to all the fourth electrodes 14. External wires 151, 152, 153, and 154, which are electric wires provided outside the piezoelectric actuator 1, are connected to the first to fourth wires 111, 121, 131, and 141, respectively. More specifically, the external wiring 151 is connected to the first wiring 111, the external wiring 152 is connected to the second wiring 121, the external wiring 153 is connected to the third wiring 131, and the fourth wiring 141 is connected to the fourth wiring 141. The external wiring 154 is connected. The external wires 151, 152, 153, 154 are connected to a voltage control unit (not shown) that controls the voltage applied to the first to fourth wires 111, 121, 131, 141. As a result, a voltage is applied to the first to fourth electrodes 11, 12, 13, 14 via the external wirings 151, 152, 153, 154 and the first to fourth wirings 111, 121, 131, 141. .

  Next, the direction of polarization of the dielectric 10 will be described. In FIG. 2, the polarization direction is the direction of the arrow in the dielectric 10. As shown in FIG. 2, the polarization direction in the first spacing portion 104 is a direction from the first electrode 11 toward the second electrode 12. Further, the polarization direction in the second interval portion 105 is a direction from the third electrode 13 toward the fourth electrode 14.

  Next, the operation of the piezoelectric actuator 1 will be described with reference to FIGS. When a voltage is applied to the first to fourth electrodes 11, 12, 13, and 14 provided on the dielectric 10, the dielectric 10 expands and contracts. This is because an electric field between the electrodes is applied to the dielectric 10. More specifically, in the dielectric 10, a portion where a voltage is applied in the direction opposite to the direction of polarization extends, and a portion where a voltage is applied in the same direction as the direction of polarization contracts. The piezoelectric actuator 1 can emit sound by bending the dielectric 10 by using expansion and contraction of the dielectric 10.

  When a positive potential is applied to the first electrode 11 and a negative potential is applied to the second electrode 12, a voltage is applied to the first spacing portion 104 in the direction opposite to the polarization direction. At this time, the 1st space | interval part 104 between the 1st electrode 11 and the 2nd electrode 12 is extended in the left-right direction. In addition, since the first electrode 11 and the second electrode 12 are provided on the upper side of the dielectric 10, the electric field applied to the first gap 104 by the first electrode 11 and the second electrode 12 is The upper part is stronger than the lower part of the interval part 104. For this reason, the upper part of the 1st space | interval part 104 extends more largely than the lower part of the 1st space | interval part 104. FIG.

  Further, when a negative voltage is applied to the third electrode 13 and a positive voltage is applied to the fourth electrode 14, a voltage is applied to the second spacing portion 105 in the same direction as the polarization direction. At this time, the second spacing portion 105 between the third electrode 13 and the fourth electrode 14 contracts in the left-right direction. In addition, since the third electrode 13 and the fourth electrode 14 are provided on the lower side of the dielectric 10, the electric field applied to the second gap portion 105 by the third electrode 13 and the fourth electrode 14 is The lower part is stronger than the upper part of the two-interval part 105. For this reason, the lower part of the 2nd space | interval part 105 shrinks more largely than the upper part of the 2nd space | interval part 105. FIG.

  When a positive potential is applied to the first electrode 11 and the fourth electrode 14, and a negative potential is applied to the second electrode 12 and the third electrode 13, the piezoelectric actuator 1 as shown in FIG. The piezoelectric actuator 1 bends so that the central part in the left-right direction rises upward. This is because the upper portion of the first interval portion 104 extends in the left-right direction and the lower portion of the second interval portion 105 contracts in the left-right direction, so that the upper portion of the entire dielectric 10 extends and the lower portion of the dielectric 10 contracts.

  On the other hand, when a negative potential is applied to the first electrode 11 and a positive potential is applied to the second electrode 12, a voltage is applied to the first spacing portion 104 in the same direction as the polarization. At this time, the 1st space | interval part 104 between the 1st electrode 11 and the 2nd electrode 12 shrinks in the left-right direction. In addition, since the first electrode 11 and the second electrode 12 are provided on the upper side of the dielectric 10, the electric field applied to the first gap 104 by the first electrode 11 and the second electrode 12 is The upper part is stronger than the lower part of the interval part 104. For this reason, the upper part of the 1st space | interval part 104 shrinks more largely than the lower part of the 1st space | interval part 104. FIG.

  In addition, when a positive voltage is applied to the third electrode 13 and a negative voltage is applied to the fourth electrode 14, a voltage is applied to the second spacing portion 105 in the direction opposite to the polarization direction. At this time, the second space portion 105 between the third electrode 13 and the fourth electrode 14 extends in the left-right direction. In addition, since the third electrode 13 and the fourth electrode 14 are provided on the lower side of the dielectric 10, the electric field applied to the second gap portion 105 by the third electrode 13 and the fourth electrode 14 is The lower part is stronger than the upper part of the two-interval part 105. For this reason, the lower part of the 2nd space | interval part 105 extends more largely than the upper part of the 2nd space | interval part 105. FIG.

  When a negative potential is applied to the first electrode 11 and the fourth electrode 14 and a positive potential is applied to the second electrode 12 and the third electrode 13, the piezoelectric actuator 1 as shown in FIG. The piezoelectric actuator 1 bends so that the central portion in the left-right direction is recessed downward. This is because the upper portion of the first interval portion 104 is contracted in the left-right direction and the lower portion of the second interval portion 105 is extended in the left-right direction, so that the upper portion of the entire dielectric 10 is contracted and the lower portion of the dielectric 10 is extended.

  That is, the positive and negative potentials applied to the first electrode 11 and the second electrode 12 are alternately switched between the first electrode 11 and the second electrode 12, and at the same time, the third electrode 13 and the fourth electrode 14. The piezoelectric actuator 1 changes between the state shown in FIG. 3 and the state shown in FIG. 4 by alternately switching the positive and negative potentials applied to and between the third electrode 13 and the fourth electrode 14. Due to this change, the piezoelectric actuator 1 can vibrate and emit sound.

  Next, a method for manufacturing the piezoelectric actuator 1 will be described with reference to FIGS. 6 and 7 correspond to (A) to (K) in FIG. 8 and FIG. 9, and the I-I cross section and II-II cross section of the piezoelectric actuator 1 in each step. (See FIG. 1). FIGS. 6A and 8A show the dielectric 10 before polarization is performed in step S11 described later. An arrow in the dielectric 10 in FIG. 6A represents an example of the direction of polarization. In FIGS. 8 and 9, the description of the direction of polarization is omitted. As shown in FIG. 6A, the polarization direction of the dielectric 10 before polarization is performed in the step S11 described later is in various directions. The material of the dielectric 10 is a material that can transmit light. For example, a ferroelectric polymer such as PVDF or an organic charge transfer material such as tetrathiafulpalene bromilil (TTF-BF) is used. Can be used. In the dielectric 10, the thickness of the central portion 103 is 1 mm, for example. Moreover, the thickness of the front-end part 101 and the rear-end part 102 is 1.1 mm, for example.

  As shown in FIGS. 5 to 9, first, in the polarization step (S11), the polarization direction is formed as shown in FIG. 6 (B). In the polarization step (S11), a pair of polarization electrodes that apply a voltage for forming polarization are brought into contact with the top surface and the bottom surface of the central portion 103 of the dielectric 10, respectively. Then, the polarization direction as shown in FIG. 6B is formed by moving the polarization electrode in the left-right direction of the central portion 103 while changing the voltage applied to the polarization electrode. Details of the direction of polarization have been described with reference to FIG.

  Next, in the first metal layer forming step (S12), a metal is vapor-deposited with a thickness of, for example, 100 nm on the dielectric 10 polarized in the step S11 to form the metal layer 21 (FIG. 6C and FIG. 8 (C)). For example, Al, Cu or the like can be used as the material of the metal layer 21. Next, in the first formation step (S13), the first electrode 11, the second electrode 12, the first wiring 111, and the predetermined pattern are etched from the metal layer 21 formed in the first metal layer formation step (S12). The second wiring 121 is formed (see FIGS. 6D and 8D). At this time, the first electrode 11 and the second electrode 12 are arranged alternately at predetermined intervals as described above.

  Next, in a photoresist coating step (S14), a positive type photoresist is applied to the bottom surface of the dielectric 10 by spin coating to form a photoresist layer 22 (FIGS. 6E and 8E). )reference). Next, in the exposure step (S15), exposure is performed by irradiating light from the upper surface side of the dielectric 10 (see FIGS. 6F and 8F). In FIG. 6F and FIG. 8F, the direction of the irradiated light is indicated by an arrow 30. Part of the light irradiated in the step S15 is blocked by the first electrode 11 and the second electrode 12. For this reason, in the photoresist layer 22, the part which opposes the 1st electrode 11 and the 2nd electrode 12 on both sides of the dielectric material 10 is not exposed, but solubility does not increase. On the other hand, in a portion where the first electrode 11 and the second electrode 12 are not present, the light passes through the transparent dielectric 10 and the photoresist layer 22 is exposed, so that the solubility is increased.

  Next, in the etching step (S16), the portion of the photoresist layer 22 that has been exposed in the exposure step (S15) and has increased solubility is removed by etching (FIGS. 7G and 9G). )reference). Next, in the second metal layer forming step (S17), the metal layer 23 is formed on the entire bottom surface including the portion where the photoresist has been removed in the etching step (S16) (FIGS. 7H and 9). H)). As a material of the metal layer 23, for example, Al, Cu, or the like can be used.

  Next, in the electrode formation step (S18), the photoresist layer 22 and the metal layer 23 formed under the photoresist layer 22 are removed by lift-off, so that the remaining metal layer 23 becomes the third electrode 13. And the fourth electrode 14 (see FIGS. 7I and 9I). That is, the third electrode 13 and the fourth electrode 14 are formed. As described above, the third electrodes 13 and the fourth electrodes 14 are alternately arranged at predetermined intervals.

  Next, in the wiring formation step (S19), the third wiring 131 is formed on the bottom surface of the front end portion 101 and the fourth wiring 141 is formed on the bottom surface of the rear end portion 102 by applying a metal by an ink jet method. FIG. 7 (J) and FIG. 9 (J)). Next, in the connection step (S20), the first to fourth wirings 111, 121, 131, and 141 are connected to the first to fourth electrodes 11, 12, 13, and 14, respectively, by applying a conductive paste by inkjet. (See FIGS. 7K and 9K). In FIG. 9K, the second electrode 12 and the second wiring 121 are connected.

  Through the above steps, the piezoelectric actuator 1 is formed. According to the present embodiment, the first and second electrodes 11 and 12 provided on the top surface of the dielectric 10 do not face the third and fourth electrodes 13 and 14 provided on the bottom surface of the dielectric 10. Therefore, the first and second electrodes 11 and 12 provided on the top surface of the dielectric 10 and the third and fourth electrodes 13 and 14 provided on the bottom surface of the dielectric 10 are opposed to each other. , Parasitic capacitance is less likely to occur. For this reason, it is difficult to be influenced by the parasitic capacitance, and the accuracy in controlling the vibration of the dielectric 10 by applying a voltage to the first to fourth electrodes 11, 12, 13, 14 is improved. Therefore, the piezoelectric actuator 1 can be vibrated with high accuracy.

  In the present embodiment, the light that is not blocked by the first electrode 11 and the second electrode 12 in the exposure step of S15 (see FIG. 5) is applied to the photoresist layer 22 applied to the bottom surface of the dielectric 10. Exposure. Then, the third electrode 13 and the fourth electrode 14 are formed in the exposed photoresist layer 22 in the electrode forming step of S18 (see FIG. 5). That is, the wiring pattern of the third electrode 13 and the fourth electrode 14 is determined by using the first electrode 11 and the second electrode 12. For this reason, since the first electrode 11 and the second electrode 12 are formed so as not to face the third electrode 13 and the fourth electrode 14, the generation of parasitic capacitance is prevented, and the piezoelectric actuator 1 is mounted with high accuracy. Can be vibrated. Further, when the third electrode 13 and the fourth electrode 14 are formed, it is not necessary to prepare a mask or the like separately. Therefore, the cost can be reduced.

  Further, the thickness of the front end portion 101 and the rear end portion 102 in the vertical direction is formed to be larger than the thickness of the central portion 103 in the vertical direction. As a result, the generation of parasitic capacitance between the first wiring 111 provided on the upper surface of the front end 101 and the third wiring 131 provided on the bottom of the front end 101 is prevented. In addition, the generation of parasitic capacitance between the second wiring 121 provided on the upper surface of the rear end portion 102 and the fourth wiring 141 provided on the bottom surface of the rear end portion 102 is prevented. For this reason, the voltage control unit applies a voltage to the first to fourth electrodes 11, 12, 13, and 14 via the first to fourth wirings 111, 121, 131, and 141 to thereby vibrate the dielectric 10. The accuracy when controlling is improved. Therefore, the piezoelectric actuator 1 can be vibrated with high accuracy.

  Further, since the first to fourth wirings 111, 121, 131, 141 are provided, the number of external wirings for applying a voltage to the first to fourth electrodes 11, 12, 13, 14 may be four. . That is, it is not necessary to connect an electric wiring from the outside of the dielectric 10 to each of the plurality of first to fourth electrodes 11, 12, 13, 14. For this reason, the number of external wirings can be reduced.

  In the present embodiment, when the upper portion of the dielectric 10 extends in the left-right direction, the lower portion of the dielectric 10 simultaneously shrinks in the left-right direction (see FIG. 3). For this reason, for example, only the upper part of the dielectric 10 extends in the left-right direction, and the deflection of the dielectric 10 becomes larger than when the lower part of the dielectric 10 does not change. On the other hand, when the upper portion of the dielectric 10 contracts in the left-right direction, the lower portion of the dielectric 10 simultaneously extends in the left-right direction (see FIG. 4). For this reason, for example, only the lower part of the dielectric 10 extends in the left-right direction, and the deflection of the dielectric 10 becomes larger than when the upper part of the dielectric 10 does not change. That is, in the present embodiment, the dielectric 10 is greatly bent, so that the vibration of the piezoelectric actuator 1 is large. Therefore, the piezoelectric actuator 1 can emit a loud sound.

(Second embodiment)
Next, the piezoelectric actuator 2 according to the second embodiment and the manufacturing method thereof will be described with reference to the drawings. In the following description, the upper side of the sheet of FIG. 10 is the upper side of the piezoelectric actuator 2, and the lower side of the sheet is the lower side of the piezoelectric actuator 2. The lower left side in FIG. 10 is the front side of the piezoelectric actuator 2, and the upper right side of the paper is the rear side of the piezoelectric actuator 2. The lower right side in FIG. 10 is the right side of the piezoelectric actuator 2, and the upper left side of the paper is the left side of the piezoelectric actuator 2.

  The piezoelectric actuator 2 in the second embodiment includes a substrate 31, and a dielectric, an electrode, and the like are provided on the substrate 31. In the first embodiment, of the first to fourth electrodes 11, 12, 13, and 14, the electrode that is formed first, and the electrode that blocks light in the exposure step (see S15 in FIG. 5) is the first electrode. One electrode 11 and second electrode 12. In the second embodiment, the first electrode 41 and the second electrode 42 are electrodes that are formed first and that block light in the exposure step (S36 in FIG. 14, which will be described later). For this reason, in the present embodiment, the first electrode 41 and the second electrode 42 are disposed on the bottom surface of the dielectric 40, and a third electrode 43 and a fourth electrode 44 described later are disposed on the top surface of the dielectric 40. Yes.

  First, the overall configuration of the piezoelectric actuator 2 will be described with reference to FIGS. 10 and 11. As shown in FIGS. 10 and 11, the piezoelectric actuator 2 is provided with a plate-like substrate 31 having a square shape in plan view. A substrate front end portion 311 that is a front end portion of the substrate 31 and a substrate rear end portion 312 that is a rear end portion of the substrate 31 are respectively a central portion of the substrate that is a portion between the substrate front end portion 311 and the substrate rear end portion 312. It is recessed below 313.

  A dielectric 40 having a square shape in plan view is provided on the upper side of the substrate 31. The length of the dielectric 40 in the front-rear direction is slightly shorter than the length of the substrate 31 in the front-rear direction. Further, the length of the dielectric 40 in the left-right direction is the same as the length of the substrate 31 in the front-rear direction. The dielectric 40 includes a dielectric front end 401 that is a front end of the dielectric 40, a dielectric rear end 402 that is a rear end, and a dielectric central portion 403. The dielectric central portion 403 is a portion between the dielectric front end portion 401 and the dielectric rear end portion 402.

  The dielectric central portion 403 has a length in the front-rear direction and a length in the left-right direction corresponding to the substrate central portion 313. The dielectric 40 is provided on the upper side of the substrate 31 so that the dielectric central portion 403 and the substrate central portion 313 are in contact with each other. The upper part of the dielectric front end 401 provided on the front side of the dielectric central part 403 protrudes above the upper surface of the dielectric central part 403. Further, the lower portion of the dielectric front end portion 401 projects downward from the bottom surface of the dielectric central portion 403. A first wiring 411 is provided between the bottom surface of the dielectric front end 401 and the top surface of the substrate front end 311. The first wiring 411 is connected to a plurality of first electrodes 41 described later. The substrate front end portion 311 protrudes forward from the dielectric front end portion 401. The first wiring 411 is provided on the entire top surface of the substrate front end 311. As a result, the front portion of the first wiring 411 is exposed to the outside, and an external wiring 151 described later is connected to the exposed portion.

  The upper portion of the dielectric rear end portion 402 provided on the rear side of the dielectric central portion 403 protrudes above the upper surface of the dielectric central portion 403. Further, the lower portion of the dielectric rear end portion 402 protrudes downward from the bottom surface of the dielectric central portion 403. A second wiring 421 is provided between the bottom surface of the dielectric rear end portion 402 and the upper surface of the substrate rear end portion 312. The second wiring 421 is connected to a plurality of second electrodes 42 described later. The substrate rear end 312 protrudes rearward from the dielectric rear end 402. The second wiring 421 is provided on the entire top surface of the substrate rear end 312. Thereby, the rear portion of the second wiring 421 is exposed to the outside, and an external wiring 152 described later is connected to the exposed portion.

  As shown in FIG. 11, a plurality of first electrodes 41 and a plurality of second electrodes 42 to which a voltage having a polarity different from that of the first electrodes 41 is provided at a predetermined interval above the substrate central portion 313. (For example, 1 mm) are provided alternately in the left-right direction. More specifically, the first electrode 41 and the second electrode 42 are arranged in the order of the second electrode 42, the first electrode 41, the second electrode 42, the first electrode 41, and the second electrode 42 from the left side of the piezoelectric actuator 2. Are lined up. The first electrode 41 and the second electrode 42 each extend in the front-rear direction on the bottom surface of the dielectric central portion 403. The bottom surface of the dielectric central portion 403, the bottom surface of the first electrode 41, and the bottom surface of the second electrode 42 are in contact with the top surface of the substrate central portion 313. A portion extending in the vertical direction of the dielectric central portion 403 between the first electrode 41 and the second electrode 42 is referred to as a third spacing portion 404.

  On the upper surface of the dielectric central portion 403, the third electrode 43 and the fourth electrode 44 to which a voltage having a polarity different from that of the third electrode 43 is applied are arranged on the upper surface facing the plurality of third spacing portions 404. They are arranged alternately in the left-right direction. More specifically, the third electrode 43 and the fourth electrode 44 are arranged on the left side of the piezoelectric actuator 2 from the third electrode 43, the fourth electrode 44, the third electrode 43, the fourth electrode 44, the third electrode 43, and the fourth electrode. The electrodes 44 are arranged in the order. The third electrode 43 and the fourth electrode 44 extend in the front-rear direction on the upper surface of the dielectric central portion 403, respectively. The third electrode 43 and the fourth electrode 44 are not provided above the first electrode 41 and the second electrode 42 provided on the bottom surface of the dielectric central portion 403. A portion extending in the vertical direction of the dielectric central portion 403 in a portion where the third electrode 43 and the fourth electrode 44 are not provided is referred to as a fourth spacing portion 405. That is, the first electrode 41 and the second electrode 42 are formed below the fourth interval portion 405, and the third electrode 43 and the fourth electrode 44 are formed above the third interval portion 404. ing. In the present embodiment, the first to fourth electrodes 41, 42, 43, 44, the third spacing portion 404, and the fourth spacing portion 405 all have the same width (length in the left-right direction, for example, 1 mm). Is formed.

  As shown in FIG. 10, the third wiring 431 is provided on the upper surface of the dielectric front end 401 and is connected to all the third electrodes 43. A fourth wiring 441 is provided on the upper surface of the dielectric rear end portion 402 and connected to all the fourth electrodes 44. As described above, the first wiring 411 is provided between the bottom surface of the dielectric front end 401 and the substrate front end 311 and is connected to all the first electrodes 41. A second wiring 421 is provided between the bottom surface of the dielectric rear end portion 402 and the upper surface of the substrate rear end portion 312 and is connected to all the second electrodes 42. External wires 151, 152, 153, and 154 that are electric wires provided outside the piezoelectric actuator 2 are connected to the first to fourth wires 411, 421, 431, and 441. More specifically, the external wiring 151 is connected to the first wiring 411, the external wiring 152 is connected to the second wiring 421, the external wiring 153 is connected to the third wiring 431, and the fourth wiring 441 is connected to the fourth wiring 441. The external wiring 154 is connected. The external wires 151, 152, 153, 154 are connected to a voltage control unit (not shown) that controls the voltage applied to the first to fourth wires 411, 421, 431, 441 of the piezoelectric actuator 2. As a result, a voltage is applied to the first to fourth electrodes 41, 42, 43, and 44 through the external wirings 151, 152, 153, and 154 and the first to fourth wirings 411, 421, 431, and 441, respectively. The

  Next, the direction of polarization of the dielectric 40 will be described. In FIG. 11, the polarization direction is represented by an arrow in the dielectric 40. As shown in FIG. 11, the polarization direction in the third spacing portion 404 is a direction from the first electrode 41 toward the second electrode 42. Further, the polarization direction in the fourth interval portion 405 is a direction from the third electrode 43 toward the fourth electrode 44.

  Next, the operation of the piezoelectric actuator 2 will be described with reference to FIGS. As in the case of the first embodiment, when a voltage is applied to the first to fourth electrodes 41, 42, 43, 44 provided on the dielectric 40, the dielectric 40 expands or contracts. The piezoelectric actuator 2 can emit sound by bending the dielectric 40 using the expansion and contraction of the dielectric 40.

  When a positive potential is applied to the first electrode 41 and a negative potential is applied to the second electrode 42, a voltage is applied to the third interval 404 in the direction opposite to the direction of polarization. At this time, the third spacing portion 404 between the first electrode 41 and the second electrode 42 extends in the left-right direction. In addition, since the first electrode 41 and the second electrode 42 are provided below the dielectric 40, the electric field applied to the third gap 404 by the first electrode 41 and the second electrode 42 is the third The lower part is stronger than the upper part of the interval part 404. For this reason, the lower part of the third interval part 404 extends more than the upper part of the third interval part 404.

  Further, when a negative voltage is applied to the third electrode 43 and a positive voltage is applied to the fourth electrode 44, a voltage is applied to the fourth spacing portion 405 in the same direction as the polarization direction. At this time, the fourth space portion 405 between the third electrode 43 and the fourth electrode 44 contracts. In addition, since the third electrode 43 and the fourth electrode 44 are provided on the upper side of the dielectric 40, the electric field applied to the fourth gap portion 405 by the third electrode 43 and the fourth electrode 44 is the fourth The upper part is stronger than the lower part of the interval part 405. For this reason, the upper part of the 4th space | interval part 405 shrinks more largely than the lower part of the 4th space | interval part 405.

  When a positive potential is applied to the first electrode 41 and the fourth electrode 44 and a negative potential is applied to the second electrode 42 and the third electrode 43, the expansion and contraction causes a piezoelectric actuator as shown in FIG. The piezoelectric actuator 2 bends so that the center part of 2 in the left-right direction is recessed downward. Since the lower part of the third spacing part 404 extends in the left-right direction and the upper part of the fourth spacing part 405 contracts in the left-right direction, the lower part of the entire dielectric 40 extends in the left-right direction, and the upper part of the dielectric 40 shrinks in the left-right direction. It is.

  On the other hand, when a negative potential is applied to the first electrode 41 and a positive potential is applied to the second electrode 42, a voltage is applied to the third spacing portion 404 in the same direction as the polarization. At this time, the third space 404 between the first electrode 41 and the second electrode 42 contracts in the left-right direction. In addition, since the first electrode 41 and the second electrode 42 are provided below the dielectric 40, the electric field applied to the third gap 404 by the first electrode 41 and the second electrode 42 is The lower part is stronger than the upper part of the three-interval part 404. For this reason, the lower part of the 3rd space | interval part 404 shrinks larger than the upper part of the 3rd space | interval part 404. FIG.

  Further, when a positive voltage is applied to the third electrode 43 and a negative voltage is applied to the fourth electrode 44, a voltage is applied to the fourth spacing portion 405 in the direction opposite to the polarization direction. At this time, the fourth space 405 between the third electrode 43 and the fourth electrode 44 extends in the left-right direction. In addition, since the third electrode 43 and the fourth electrode 44 are provided on the upper portion of the dielectric 40, the electric field applied to the fourth spacing portion 405 by the third electrode 43 and the fourth electrode 44 is the fourth The upper part is stronger than the lower part of the interval part 405. For this reason, the upper part of the 4th space | interval part 405 extends more largely than the lower part of the 4th space | interval part 405.

  When a negative potential is applied to the first electrode 41 and the fourth electrode 44, and a positive potential is applied to the second electrode 42 and the third electrode 43, the piezoelectric actuator 2 as shown in FIG. The piezoelectric actuator 2 bends so that the center in the left-right direction rises upward. This is because the lower portion of the third spacing portion 404 contracts and the upper portion of the fourth spacing portion 405 extends, so that the upper portion of the entire dielectric 40 extends and the lower portion of the dielectric 40 contracts.

  In other words, the positive and negative potentials applied to the first electrode 41 and the second electrode 42 are alternately switched between the first electrode 41 and simultaneously applied to the third electrode 43 and the fourth electrode 44. The piezoelectric actuator 2 changes between FIG. 12 and FIG. 13 by alternately switching the negative and negative potentials between the third electrode 43 and the fourth electrode 44. Due to this change, the piezoelectric actuator 2 can vibrate and emit sound.

  Next, a manufacturing method of the piezoelectric actuator 2 will be described with reference to FIGS. (A) to (J) in FIGS. 15 and 16 correspond to (A) to (J) in FIGS. 17 and 18, and the III-III section and the IV-IV section of the piezoelectric actuator 2 in each step. (Refer to FIG. 10).

  As shown in FIGS. 14 to 18, first, in the first formation step (S 31), a metal is deposited on the upper side of the substrate 31 to a thickness of, for example, 100 nm, and the first electrode 41, the second electrode 42, and the first A wiring 411 and a second wiring 421 are formed (see FIGS. 15A and 17A). The substrate 31 is a material that can transmit light. For example, PVDF (polyvinylidene fluoride), PVC (polyvinyl chloride), nylon 11 (polyamide), vinylidene cyanide-based copolymer, polylactic acid (PLA) Etc. Moreover, Al, Cu etc. can be used for the material of the 1st electrode 41, the 2nd electrode 42, the 1st wiring 411, and the 2nd wiring 421, for example. In the step S31, the first electrode 41 and the second electrode 42 are arranged alternately at predetermined intervals on the upper side of the substrate center portion 313 as described above. The first wiring 411 is formed above the substrate front end 311, and the second wiring 421 is formed above the substrate rear end 312. At this time, since the upper surfaces of the substrate front end portion 311 and the substrate rear end portion 312 are located below the upper surface of the substrate center portion 313, the first wiring 411 and the second wiring 421 are connected to the first electrode 41. It is not connected to the second electrode 42. For example, the substrate 31 has a front end 311 of 50 nm, a substrate rear end 312 of 50 nm, and a substrate center 313 of 200 nm.

  Next, in the second connection step (S32), the first wiring 411 is connected to all the first electrodes 41 and the second wiring 421 is connected to all the second electrodes 42 by applying a conductive paste by an ink jet method. (See FIGS. 15B and 17B). In FIG. 17B, the second electrode 42 and the second wiring 421 are connected.

  Next, in the dielectric formation step (S33), for example, a dielectric is applied with a thickness of 1 mm to form the dielectric 40 (see FIGS. 15C and 17C). At this time, a dielectric material thicker than the dielectric central part 403 (for example, 1.1 mm in thickness) is applied to a part where the dielectric front end part 401 and the dielectric rear end part 402 are formed. Thus, the dielectric front end portion 401 and the dielectric rear end portion 402 are formed so as to protrude in the vertical direction from the dielectric central portion 403 (see FIG. 17C). The material of the dielectric 40 is a material that can transmit light. For example, a ferroelectric polymer such as PVDF or an organic charge transfer material such as tetrathiafulpalene bromilil (TTF-BF) is used. be able to.

  In the polarization step (S34), the polarization direction is formed as shown in FIG. In the polarization step (S34), a pair of polarization electrodes for applying a voltage for polarization formation is brought into contact with the upper surface of the dielectric central portion 403 and the bottom surface of the substrate central portion 313, respectively. Then, the polarization direction as shown in FIG. 15C is formed by moving the polarization electrode in the left-right direction while changing the voltage applied to the polarization electrode. Details of the direction of polarization have been described with reference to FIG.

  Next, in a photoresist coating step (S35), a negative photoresist is applied to the upper surface of the dielectric 40 by spin coating to form a photoresist layer 52 (FIGS. 15D and 17D). reference). Next, in the exposure step (S36), exposure is performed by irradiating light from below to above the substrate 31 (see FIGS. 15E and 17E). In FIG. 15E and FIG. 17E, the direction of the irradiated light is indicated by an arrow 50. A part of the light irradiated in the step S <b> 36 is blocked by the first electrode 41 and the second electrode 42. For this reason, the portion of the photoresist layer 52 that faces the first electrode 41 and the second electrode 42 across the dielectric 40 is not exposed and is not cured. On the other hand, in a portion where the first electrode 41 and the second electrode 42 are not provided, light passes through the light-transmitting substrate 31 and the dielectric 40, and the photoresist layer 52 is exposed and cured.

  Next, in the etching step (S37), the photoresist in the photoresist layer 52 that is not exposed and not cured in the step S37 is removed by etching (see FIGS. 16F and 18F). . Next, in the waterproof material application step (S38), the waterproofing is performed on the upper side of the photoresist layer 52 that has not been removed in the step of S37 and on the upper side of the dielectric 40 where the photoresist layer 52 has been removed in the step of S37. Material 53 is applied and waterproof coated (see FIGS. 16G and 18G).

  Next, in the photoresist removal step (S39), the photoresist layer 52 that has not been removed in the process of S37 is removed by ultrasonic cleaning in an acetone solution. At this time, the waterproof material 53 applied on the upper side of the photoresist layer 52 is also removed (see FIGS. 16H and 18H).

  Next, in the electrode forming step (S40), a metal is applied to the upper side of the dielectric 40 by an ink jet method. The applied metal is not fixed on the upper side of the waterproof material 53 and is guided to the portion where the photoresist layer 52 is removed in the step of S39. Thereby, the third electrode 43 and the fourth electrode 44 are formed in the portion where the photoresist layer 52 has been removed in the step of S39 (see FIGS. 16I and 18I). For example, Al, Cu or the like can be used as the material of the third electrode 43 and the fourth electrode 44.

  Next, in the second wiring formation step (S41), the waterproof material 53 that has not been removed in the step S39 is removed by ultrasonic cleaning in an acetone solution. In addition, a third wiring 431 and a fourth wiring 441 are formed (see FIGS. 16J and 18J). In the step of S41, a metal is applied by an inkjet method, whereby a third wiring 431 is formed on the upper surface of the dielectric front end portion 401, and a fourth wiring 441 is formed on the upper surface of the dielectric rear end portion 402. Next, in the third connection step (S42), the third wiring 431 is connected to all the third electrodes 43 and the fourth wiring 441 is connected to all the fourth electrodes 44 by applying the conductive paste by inkjet. (Not shown).

  Through the above steps, the piezoelectric actuator 2 is formed. According to the present embodiment, the first and second electrodes 41 and 42 provided on the bottom surface of the dielectric 40 do not face the third and fourth electrodes 43 and 44 provided on the top surface of the dielectric 40. For this reason, compared with the case where the 1st, 2nd electrodes 41 and 42 provided in the bottom face of the dielectric 40, and the 3rd and 4th electrodes 43 and 44 provided in the upper surface of the dielectric 40 mutually oppose. , Parasitic capacitance is less likely to occur. For this reason, it is hard to be influenced by the parasitic capacitance, and the accuracy in controlling the vibration of the dielectric 40 by applying a voltage to the first to fourth electrodes 41, 42, 43, 44 is improved. Therefore, the piezoelectric actuator 2 can be vibrated with high accuracy.

  In the present embodiment, the light not blocked by the first electrode 41 and the second electrode 42 in the exposure step of S36 (see FIG. 14) is applied to the photoresist layer 52 applied to the upper surface of the dielectric 40. Exposure. Then, the third electrode 43 and the fourth electrode 44 are formed in the exposed photoresist layer 52 in the electrode forming step of S40 (see FIG. 14). That is, the wiring pattern of the third electrode 43 and the fourth electrode 44 is determined by using the first electrode 41 and the second electrode 42. For this reason, when forming the 3rd electrode 43 and the 4th electrode 44, it is not necessary to prepare a mask etc. separately. Therefore, the cost can be reduced. In addition, since the first electrode 41 and the second electrode 42 are formed so as not to face the third electrode 43 and the fourth electrode 44, generation of parasitic capacitance is prevented, and the piezoelectric actuator 2 is vibrated with high accuracy. Can be made.

  In addition, the vertical thickness of the dielectric front end portion 401 and the dielectric rear end portion 402 is formed to be larger than the vertical thickness of the dielectric central portion 403. This prevents a parasitic capacitance from being generated between the first wiring 411 provided on the bottom surface of the dielectric front end 401 and the third wiring 431 provided on the top surface of the dielectric front end 401. In addition, the generation of parasitic capacitance between the second wiring 421 provided on the bottom surface of the dielectric rear end portion 402 and the fourth wiring 441 provided on the upper surface of the dielectric rear end portion 402 is prevented. . For this reason, the voltage control unit applies a voltage to the first to fourth electrodes 41, 42, 43, 44 via the first to fourth wirings 411, 421, 431, 441, and vibrates the dielectric 40. The accuracy when controlling is improved. Therefore, the piezoelectric actuator 2 can be vibrated with high accuracy.

  Further, since the first to fourth wirings 411, 421, 431, and 441 are provided, the number of external wirings for applying a voltage to the first to fourth electrodes 41, 42, 43, and 44 may be four. . That is, it is not necessary to connect an electrical wiring from the outside of the dielectric 40 to each of the plurality of first to fourth electrodes 41, 42, 43, 44. For this reason, the number of external wirings can be reduced.

  In the present embodiment, when the lower portion of the dielectric 40 extends in the left-right direction, the upper portion of the dielectric 40 simultaneously shrinks in the left-right direction (see FIG. 12). For this reason, for example, only the lower part of the dielectric 40 extends in the left-right direction, and the deflection of the dielectric 40 becomes larger than when the upper part of the dielectric 40 does not change. On the other hand, when the lower portion of the dielectric 40 contracts in the left-right direction, the upper portion of the dielectric 40 simultaneously extends in the left-right direction (see FIG. 13). For this reason, for example, only the upper part of the dielectric 40 extends in the left-right direction, and the deflection of the dielectric 40 becomes larger than when the lower part of the dielectric 40 does not change. That is, in the present embodiment, the dielectric 40 is greatly bent, so that the vibration of the piezoelectric actuator 2 is large. Therefore, the piezoelectric actuator 2 can emit a loud sound.

  The present invention is not limited to the first and second embodiments, and various modifications can be made. For example, in the first embodiment, the thickness of the front end portion 101 and the rear end portion 102 is made larger than the thickness of the central portion 103, and in the second embodiment, the thickness of the dielectric front end portion 401 and the dielectric rear end portion 402. Is made larger than the thickness of the dielectric central portion 403 to prevent the generation of parasitic capacitance in the wiring, but is not limited thereto. For example, without increasing the thickness, by forming an insulating layer between the wirings facing each other across the front end 101, the rear end 102, the dielectric front end 401, and the dielectric rear end 402, Generation of parasitic capacitance may be prevented.

  Further, the front end portion 101, the rear end portion 102, the dielectric front end portion 401, and the dielectric rear end portion 402 may not be formed. In this case, in the first embodiment, the central portion 103 and the first to fourth electrodes 11, 12, 13, and 14 are formed. In the second embodiment, the substrate central portion 313, the dielectric central portion 403, and The first to fourth electrodes 41, 42, 43, and 44 may be formed. Also in this case, the piezoelectric actuators 1 and 2 can be vibrated by connecting external wiring to each electrode and supplying a voltage.

  Further, the number and size of the first to fourth electrodes 11, 12, 13, and 14 of the first embodiment and the first to fourth electrodes 41, 42, 43, and 44 of the second embodiment are not limited.

  In the first and second embodiments, the steps S14 to S18 (see FIG. 5) and the steps S34 to S40 (see FIG. 14) correspond to the “second forming step” of the present invention. Further, the process of S13 for forming the first wiring 111 and the second wiring 121 (see FIG. 5), the process of S20 for connecting the first wiring 111 to the first electrode 11 and connecting the second wiring 121 (see FIG. 5). ), The step of S31 (see FIG. 14) for forming the first wiring 411 and the second wiring 421, and the step of S32 (see FIG. 14) correspond to the “third formation step” of the present invention. Further, the process of S19, the process of S20 (see FIG. 5), the process of S41 for forming the third wiring 431 and the fourth wiring 441, and the process of S42 (see FIG. 14) are “fourth forming process” of the present invention. Is equivalent to.

1, 2 Piezoelectric actuator 10 Dielectric 11, 41 First electrode 12, 42 Second electrode 13, 43 Third electrode 14, 44 Fourth electrode 22, 52 Photoresist layer 31 Substrate 40 Dielectric 101 Front end 102 Rear end 103 Central portion 104 First spacing portion 105 Second spacing portions 111 and 411 First wiring 121 and 421 Second wiring 131 and 431 Third wiring 141 and 441 Fourth wiring 313 Substrate central portion 401 Dielectric front end portion 402 Dielectric rear portion End portion 403 Dielectric center portion 404 Third spacing portion 405 Fourth spacing portion

Claims (8)

A plurality of first electrodes provided on one of the faces opposed in the thickness direction of the polarized dielectric;
A plurality of second electrodes provided on the one surface and applied with a voltage having a polarity different from that of the first electrode;
A plurality of third electrodes provided on the other surface of the dielectric material facing the one surface;
A plurality of fourth electrodes provided on the other surface and applied with a voltage having a polarity different from that of the third electrode;
The first electrode and the second electrode are provided alternately on the one surface at predetermined intervals,
The third electrode and the fourth electrode are provided alternately in a position facing the plurality of intervals between the first electrode and the second electrode on the other surface,
The polarization direction of the polarized dielectric is
In the portion across the thickness direction of the dielectric between the first electrode and the second electrode, the direction from the first electrode to the second electrode,
The piezoelectric actuator according to claim 1, wherein a portion extending in the thickness direction of the dielectric between the third electrode and the fourth electrode is a direction from each third electrode toward each fourth electrode. A first wiring provided on the one surface side of the dielectric and connecting the plurality of first electrodes;
A second wiring that is provided on the one surface side of the dielectric and connects the plurality of second electrodes;
A third wiring provided on the other surface side of the dielectric and connecting the plurality of third electrodes;
The piezoelectric actuator according to claim 1, further comprising a fourth wiring provided on the other surface side of the dielectric and connecting the plurality of fourth electrodes.   The thickness of the dielectric in the portion where the first wiring and the second wiring face each other with the dielectric interposed between the third wiring and the fourth wiring is larger than the thickness of the other portion of the dielectric. The piezoelectric actuator according to claim 2, wherein A polarization step for polarizing the dielectric;
A first forming step of forming a plurality of first electrodes and a plurality of second electrodes to which a voltage having a polarity different from that of the first electrode is alternately arranged at a predetermined interval on one surface of the dielectric When,
The third electrode and the third electrode are located at positions facing the plurality of intervals between the first electrode and the second electrode on the other surface of the dielectric material facing the one surface. A second formation step of alternately forming a plurality of fourth electrodes to which voltages of different polarities are applied, and
The polarization direction of the dielectric material polarized by the polarization step is:
In the portion across the thickness direction of the dielectric between the first electrode and the second electrode, the direction from the first electrode to the second electrode,
Production of a piezoelectric actuator characterized in that a portion across the thickness direction of the dielectric between the third electrode and the fourth electrode is a direction from each third electrode toward each fourth electrode. Method. A first forming step in which a plurality of first electrodes and a plurality of second electrodes to which a voltage having a polarity different from that of the first electrode is applied are alternately arranged at predetermined intervals on a plate-like substrate;
A dielectric forming step of forming a dielectric so as to cover the first electrode and the second electrode formed in the first forming step;
A polarization step of polarizing the dielectric;
A third electrode at a position facing the plurality of intervals between the first electrode and the second electrode on the other surface facing the one surface that is the surface on the substrate side of the dielectric, A second forming step of alternately forming a plurality of fourth electrodes to which a voltage having a polarity different from that of the third electrode is applied, and
The polarization direction of the dielectric material polarized by the polarization step is:
In the portion across the thickness direction of the dielectric between the first electrode and the second electrode, the direction from the first electrode to the second electrode,
Production of a piezoelectric actuator characterized in that a portion across the thickness direction of the dielectric between the third electrode and the fourth electrode is a direction from each third electrode toward each fourth electrode. Method. The second forming step includes
A photoresist coating step of coating a photoresist on the other surface of the dielectric;
An exposure step of irradiating light from the one surface side and exposing a plurality of positions facing the gap between the first electrode and the second electrode in the photoresist;
5. An electrode forming step of forming the third electrode and the fourth electrode in place of the photoresist at a position corresponding to the exposed portion of the photoresist. A method for manufacturing the piezoelectric actuator according to claim 5. A third forming step of forming a first wiring connecting the plurality of first electrodes and a second wiring connecting the plurality of second electrodes on the one surface side of the dielectric;
A fourth forming step of forming a third wiring for connecting the plurality of third electrodes and a fourth wiring for connecting the plurality of fourth electrodes on the other surface side of the dielectric; A method for manufacturing a piezoelectric actuator according to any one of claims 4 to 6.   The thickness of the dielectric in the portion where the first wiring and the second wiring face each other with the dielectric interposed between the third wiring and the fourth wiring is larger than the thickness of the other portion of the dielectric. The method of manufacturing a piezoelectric actuator according to claim 7, wherein

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