JP2010240628A - Vibration type conveyor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric driving body capable of preventing peeling between a piezoelectric driving element and a metal spring plate, improving the durability of the piezoelectric driving element, and reducing the loss of driving force, and to provide a vibration type conveyor using the same. <P>SOLUTION: The piezoelectric driving body 10 includes: the metal spring plate 11; the piezoelectric driving element 12 arranged so as to be piled up on the metal spring plate 11 and formed by integrally sintering a piezoelectric ceramic layer 12a, first electrodes 12b and 12b' and a second electrode 12c disposed on the front and back of the piezoelectric ceramic layer 12a, and an insulating ceramic layer 12d exposed on the back surface to cover the first electrodes 12b and 12b' or the second electrode 12c; and an adhesive layer 13 for bonding the insulating ceramic layer 12d and the metal spring plate 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a vibration Doshiki conveying device, in particular, to a structure of a piezoelectric driving body having an adhesive structure of the piezoelectric drive elements in the metal spring plate.

  2. Description of the Related Art Conventionally, in various production lines, a vibratory transfer device is widely used to supply parts to an assembly device in a fixed posture. In this vibration type conveying apparatus, generally, a conveying body provided with a conveying path (track) is supported by an elastic spring, and a vibration exciter for vibrating the conveying body is provided. In recent years, a large number of vibrators have a piezoelectric drive type configuration using a piezoelectric drive body connected to the elastic spring from the conventional electromagnetic drive type configuration. The piezoelectric drive type exciter has advantages over the electromagnetic drive type in that smooth transferability is obtained, power consumption is low, and there is no possibility of magnetizing the transfer parts.

  As the above-described piezoelectric driving body, as shown in FIG. 7, a piezoelectric driving element 12 'bonded to the surface of a metal spring plate 11' such as a shim plate is used. Electrodes are formed on both the front and back surfaces of the piezoelectric drive element 12 '. By applying a voltage between both electrodes, the piezoelectric drive element 12' expands and contracts to cause bending vibration in the metal spring plate 11 '. However, a piezoelectric drive body 10 ′ in which a piezoelectric drive element 12 ′ is bonded to the front and back of the metal spring plate 11 ′ and connected in series with a plate spring-like vibration spring 3 is attached to the base 1. In the illustrated vibration type conveying apparatus which is fixed via the part 2 and fixed to the conveying body 5 via the attachment part 4, the electrode on the back side of the piezoelectric drive element 12 'is electrically connected to the metal spring plate 11'. Therefore, if the measurement voltage when checking the withstand voltage of the device is high, the piezoelectric drive element 12 'may be deteriorated, and it is necessary to provide an insulation transformer for electrical safety. There was a problem.

  Therefore, in order to obtain a sufficient withstand voltage and ensure electrical safety, a technique for insulating between the piezoelectric drive element 12 'and the metal spring plate 11', for example, described in Patent Documents 1 and 2 below. A proposed structure has been proposed. Patent Document 1 describes a structure in which an insulating film is interposed between a piezoelectric drive element and a metal spring plate. Patent Document 2 describes a structure in which an insulating ceramic plate is interposed between a piezoelectric drive element and a metal spring plate.

JP 11-31855 A JP 2003-134852 A

  However, as a result of examination by the inventors of the present application, in the method using the above-described insulating film, a soft insulating film is present on the bonding surface between the piezoelectric driving element and the metal spring plate, so that the piezoelectric driving element and the metal spring plate are separated from each other. There is a problem that bending vibration cannot be efficiently generated due to loss of energy transmission between the two. In addition, since the vibration-type transfer device operates in a state where the elastically supported transfer body resonates due to vibration by the piezoelectric drive body, a large stress is applied between the piezoelectric drive element and the metal spring plate. However, since the adhesive strength between the piezoelectric drive element and the metal spring plate is low, there is a problem that a peeling portion is generated on the bonding surface, and stress concentrates on the peeling portion, so that the piezoelectric driving element is destroyed due to excessive deformation. .

  On the other hand, in the method using the above-described insulating ceramic plate, the adhesive force between the insulating ceramic plate and the metal spring plate can be increased. However, bonding the insulating ceramic plate to both the piezoelectric drive element and the metal spring plate causes a problem of transmission loss of driving force and an increase in manufacturing cost. In general, since the insulating ceramic plate has a high hardness, the amount of bending deformation is limited by interposing the insulating ceramic plate, and as a result, a loss of driving force occurs and vibration cannot be generated efficiently. There is also a point. Furthermore, if the hardnesses of the piezoelectric drive element and the insulating ceramic substrate do not match, a peeled portion is generated on the bonding surface between the piezoelectric drive element and the insulating ceramic substrate, and stress is concentrated on the peeled portion, thereby destroying the piezoelectric drive element. There are also problems.

Therefore, the present invention solves the above-mentioned problems, and the problem is that it is possible to improve the durability of the piezoelectric drive element by preventing the peeling between the piezoelectric drive element and the metal spring plate, and to reduce the driving force loss. It is to realize a vibratory conveying apparatus using a piezoelectric driving body that can be reduced.

In view of such a situation, the vibratory transfer device of the present invention includes a base, a transport body disposed above the base, and a piezoelectric driving body connected between the base and the transport body. comprising a said piezoelectric driving body is a metal spring plate, is arranged so as to overlap in the metal spring plate, the piezoelectric ceramic layer, a first electrode disposed on the front surface of the piezoelectric ceramic layer, wherein the piezoelectric ceramic a second electrode disposed on the back surface of the layer, as well as to cover the second electrode before Symbol exposed on the element rear surface, said piezoelectric ceramic layers and the piezoelectric ceramic layer thinner than the insulating ceramic layer of the same material, the A piezoelectric driving element formed by sintering integrally and in which the insulating ceramic layer is integrated in direct contact with the piezoelectric ceramic layer in a plane range where the second electrode is not formed , the insulating ceramic layer and the Connect metal spring plate And having an adhesive layer, a.

  According to the present invention, the insulating ceramic layer formed by sintering integrally is exposed on the back surface of the piezoelectric drive element in a state of covering the electrode, and this insulating ceramic layer is bonded to the metal spring plate by the adhesive layer. As a result, the adhesive strength between the piezoelectric drive element and the metal spring plate can be increased, the insulating ceramic layer can be firmly integrated with the piezoelectric drive element, and only one layer of adhesive is required. Loss and manufacturing costs can be reduced.

Oite this onset Ming, the insulating ceramic layer is Ru is composed of the same material as the piezoelectric ceramic layer. According to this, since the insulating ceramic layer is made of the same material as the piezoelectric ceramic layer, the piezoelectric driving element can be easily manufactured and the manufacturing cost can be reduced, and the piezoelectric ceramic layer and the insulating ceramic layer have the same elastic characteristics. Therefore, the transmission efficiency of the driving force can be further increased.

Oite this onset Ming, the insulating ceramic layer is thinner than the piezoelectric ceramic layer. According to this, unlike the piezoelectric ceramic layer to which an electric field is applied with both the front and back electrodes sandwiched between the front surface side electrode and the back surface side electrode, the insulating ceramic layer acts as a driving resistance of the piezoelectric driving element because the electric field is not applied. However, since this insulating ceramic layer is thinner than the piezoelectric ceramic layer, loss of driving force can be further reduced. In particular, it is more desirable to reduce the loss of driving force by setting the thickness of the insulating ceramic layer to be equal to or less than half of the total thickness of the piezoelectric ceramic layer.

The optimum thickness range of the insulating ceramic layer varies depending on the material, but is usually preferably in the range of 0.02 to 2.0 mm, and more preferably in the range of 0.05 to 0.45 mm. The material of the insulating ceramic layer is preferably so-called soft ceramics. The _{ceramic, BaTiO 3, Pb (Zr ·} Ti) O 3, Fe 2 O 3, Al 2 O 3, AlN, Si 3 N 4, but fine ceramics such as SiC and the like, in _particular, BaTiO 3, PbTiO ₃ Pb (Zr · Ti) O ₃ , PbNb ₂ O _{6 and} other piezoelectric materials having piezoelectricity are preferable.

In one aspect of the present invention, the upper surface of the piezoelectric driving element includes the first electrode and an overhang electrode portion that is spaced apart from the first electrode and is conductively connected to the second electrode. Provided. According to this, since it is not necessary to draw the overhanging electrode portion conductively connected to the second electrode of the piezoelectric drive element to the outside of the formation range of the piezoelectric ceramic layer, it can be configured compactly and can be connected to the drive wiring. Since it becomes easy, manufacturing cost can further be reduced. At this time, the overhang electrode portion is preferably conductively connected to the second electrode via an outer surface connection portion provided on the side surface of the piezoelectric drive element.

  In this case, it is preferable that the overhang electrode portion is formed in the same layer as the first electrode and has a smaller area than the first electrode. If it does in this way, the manufacturing cost of a piezoelectric drive element can further be reduced by forming an overhang | projection electrode part in the same layer as a 1st electrode. On the other hand, the electric field generated by the first electrode cannot be applied to the piezoelectric ceramic layer in the range where the overhang electrode portion is formed. However, since the overhang electrode portion has a smaller area than the first electrode, the overhang electrode portion is formed. In the range, it is possible to suppress functional deterioration due to no electric field being applied to the piezoelectric ceramic layer.

  In another aspect of the present invention, in the piezoelectric driving element, a plurality of the piezoelectric ceramic layers are laminated via the first electrode or the second electrode. According to this, it is possible to reduce the driving voltage and increase the driving force by configuring the multilayer piezoelectric driving element.

Incidentally, in the vibratory conveying apparatus of the present invention, between the front Kimotodai and the carrier there is a case where vibration spring connected to said piezoelectric driving body is provided.

  According to the present invention, a piezoelectric driving body capable of preventing the peeling between the piezoelectric driving element and the metal spring plate to improve durability and reducing the loss of driving force, and vibration using the same. The outstanding effect that a type | formula conveying apparatus is realizable can be show | played.

The exploded partial sectional view showing the state before the assembly of the embodiment of the piezoelectric actuator of the present invention. The partial top view before the assembly of the same embodiment. The fragmentary sectional view after the assembly of the same embodiment. The top view (a) and side view (b) which show the whole structure after the assembly of the embodiment. The top view (a), the right view (b), and the left view (c) which show the detailed structure of different embodiment. The schematic block diagram which shows typically the structure of the vibration type conveying apparatus using the piezoelectric drive body of embodiment. The schematic block diagram which shows typically the structure of the conventional vibration type conveying apparatus.

  Next, an embodiment for a piezoelectric driving body and a vibration transfer device according to the present invention will be described in detail with reference to the accompanying drawings. 1 is an exploded partial cross-sectional view showing the configuration of the piezoelectric drive body before assembly according to the present embodiment, FIG. 2 is a partial plan view before assembly, and FIG. 3 is a partial cross-sectional view showing the configuration of the piezoelectric drive body after assembly. 4 is a plan view (a) and a side view (b) showing the overall configuration after assembly.

  As shown in FIG. 1, the piezoelectric driving body 10 of this embodiment includes a metal spring plate 11 having a thickness of about 1 to 10 mm, a piezoelectric driving element 12 having a thickness of about 0.3 to 1.0 mm, and a metal. An adhesive 13 for bonding the spring plate 11 and the piezoelectric drive element 12 is provided. The metal spring plate 11 is not particularly limited as long as it has a metal spring property. For example, a material obtained by quenching SK steel used as a spring material can be used. Generally, a thickness of about 2.5 to 8.0 mm is used.

  The piezoelectric driving element 12 includes a piezoelectric ceramic layer 12a, first electrodes 12b and 12b 'formed on either one of the front and back surfaces of the piezoelectric ceramic layer 12a, and any one of the front and back surfaces of the piezoelectric ceramic layer 12a. And a second electrode 12c formed on the other surface. More specifically, a plurality (five layers in the illustrated example) of piezoelectric ceramic layers 12a are arranged in the stacking direction, and the first electrodes 12b and 12b ′ and the second electrodes are disposed before and after the piezoelectric ceramic layers 12a in the stacking direction. 12c is arranged, and as a whole, the first electrodes 12b and 12b 'and the second electrode 12c are alternately arranged in the stacking direction. Each piezoelectric ceramic layer 12a is sandwiched between the first electrodes 12b and 12b 'and the second electrode 12c, and receives an electric field in the thickness direction by a driving voltage applied between the two electrodes.

The piezoelectric ceramic layer 12a is not particularly limited as long as it is a piezoelectric ceramic material having piezoelectricity such as BaTiO ₃ , PbTiO ₃ , Pb (Zr · Ti) O ₃ , PbNb ₂ O ₆ , and in particular, Pb (Zr · Ti) O. ₃ (hereinafter simply referred to as “PZT”). The piezoelectric ceramic layer is preferably formed by kneading a piezoelectric powder with an appropriate resin binder, a solvent, and the like to dry a ceramic raw sheet (so-called ceramic green sheet) and firing it.

  Further, as the first electrodes 12b, 12b 'and the second electrode 12c, silver electrodes obtained by firing a conductive paste (slurry) such as silver, silver / palladium are used. However, the electrode material is not particularly limited in the present invention, and other conductors such as gold and copper can be used.

  In the present embodiment, as described above, the piezoelectric ceramic layer 12a, the first electrodes 12b, 12b ', and the second electrode 12c have a laminated structure, which is usually formed as follows. A laminate in which a conductive paste is formed on the above-mentioned ceramic raw sheet by screen printing or the like, and the ceramic raw sheet with the electrode pattern thus formed is laminated, and the ceramic raw sheet and the electrode are alternately laminated. Form. Thereafter, the laminate is appropriately cut in a plane as necessary, and then fired to form the laminate structure. However, the manufacturing method of the piezoelectric driving element 12 of the present embodiment is not particularly limited. For example, the piezoelectric ceramic layer 12a is formed by compressing and molding a ceramic powder containing a binder in a mold. Thereafter, the piezoelectric drive element may be manufactured by applying and baking a silver paste or the like on the surface.

  In the present embodiment, the second electrode 12c provided on the back surface side of the piezoelectric driving element 12 formed by sintering integrally is covered with the insulating ceramic layer 12d. Thereby, when the back surface of the piezoelectric driving element 12 is bonded via the adhesive 13, the piezoelectric driving element 12 and the metal spring plate 11 are reliably insulated. In the present embodiment, the insulating ceramic layer 12d is made of the same material as the piezoelectric ceramic layer 12a. In the illustrated example, the insulating ceramic layer 12d has a thickness approximately half that of the piezoelectric ceramic layer 12a. For example, when the thickness of the piezoelectric ceramic layer 12a is 50 to 150 μm, the thickness of the insulating ceramic layer 12d is 25 to 75 μm. The thicknesses of the first electrode 12b and the second electrode 12c are both about 5 to 10 μm.

  In the case of the illustrated example, the thickness of the piezoelectric ceramic layer 12a is set to a value at which optimum driving force and durability can be obtained in relation to the driving voltage. In general, the thickness of the piezoelectric ceramic layer 12a has an optimum value range from the viewpoint of driving force and durability when a predetermined driving voltage is used. When the thickness is larger than the value range, the driving force decreases, If the thickness is smaller than the range, the piezoelectric ceramic layer is likely to be deteriorated due to the pressure resistance.

  In the examples described later, by setting the driving voltage to 50 V, a thickness of 110 μm is selected as the piezoelectric ceramic layer 12a made of PZT, while a thickness of 55 μm is selected as the insulating ceramic layer 12d. did. This is because the insulating ceramic layer 12d is made thinner than the piezoelectric ceramic layer 12a to increase the flexibility of the insulating ceramic layer 12d, thereby reducing the stress generated between the piezoelectric ceramic layer 12a and the insulating ceramic layer 12d. This is for avoiding damage to the drive element 12 and reducing loss during transmission of the drive force from the piezoelectric drive element 12 to the metal spring plate 11. Also, in the manufacturing process, the piezoelectric ceramic layer 12a is formed by stacking two ceramic raw sheets, and the insulating ceramic layer 12d is formed by one ceramic raw sheet, so that ceramic raw sheets having different thicknesses are used. Since it is not necessary, there is an advantage that the manufacturing cost can be reduced. That is, in general, by changing the number of stacked raw ceramic sheets of the same thickness between the piezoelectric ceramic layer and the insulating ceramic layer, the thickness of the piezoelectric ceramic layer and the insulating ceramic layer is optimized while reducing the manufacturing cost. It becomes possible to do.

  In the illustrated example, in the piezoelectric driving element 12, a plurality of first electrodes 12b, 12b 'and a second electrode 12c are provided in the stacking direction (thickness direction), and a plurality of these electrodes 12b, 12b' and 12c are provided. The piezoelectric ceramic layer 12a is sandwiched between both sides. An outer surface connection portion 12e for conductively connecting the plurality of first electrodes 12b and 12b 'is provided on one outer surface of the element, and the plurality of second electrodes 12c on the other outer surface. An outer surface connection portion 12f for conductively connecting each other is provided. These outer surface connection portions 12e and 12f are formed by sintering a conductive paste such as a silver paste similar to the electrode 12c, or are formed of other conductive materials such as solder.

  In the piezoelectric driving element 12, the adhesion between the second electrode 12c and the insulating ceramic layer 12d is as high as the adhesion between the piezoelectric ceramic layer 12a, the first electrode 12b, and the second electrode 12c. Further, when the piezoelectric ceramic layer 12a and the insulating ceramic layer 12d are in direct contact with each other in a plane range where the second electrode 12c is not formed, for example, in the outer peripheral portion of the piezoelectric ceramic layer 12a, higher adhesion (integration) ) Is obtained. In FIG. 1 and FIG. 3, the piezoelectric ceramic layer 12a is drawn in a two-layer structure as indicated by a broken line. This is because one piezoelectric ceramic layer is formed by stacking two ceramic raw sheets as will be described later. It only shows that 12a is formed, and as a result, the integral piezoelectric ceramic layer 12a is formed. In addition, the piezoelectric ceramic layer 12a may be formed of a single layer of ceramic raw sheet, not limited to the case where the piezoelectric ceramic layer 12a is formed by stacking a plurality of ceramic raw sheets in this way. Further, the insulating ceramic layer 12d and the piezoelectric ceramic layer 12a adjacent to the insulating ceramic layer 12d have a portion directly connected to the portion where the electrode layer is interposed as shown in the illustrated example. Are integrated. The plurality of piezoelectric ceramic layers 12a are similarly integrated.

  After the piezoelectric drive element 12 is configured as shown in the drawing, a high voltage is applied between the first electrodes 12b and 12b 'and the second electrode 12c, so that the piezoelectric ceramic layer 12a is polarized. Is given. The polarization process is not performed on the insulating ceramic layer 12d in the present embodiment. However, the polarization treatment may be performed on the insulating ceramic layer 12d by using an auxiliary electrode (not shown) other than the electrodes 12b, 12b 'and 12c. In this case, although depending on the driving method and the electrode structure, the insulating ceramic layer 12d is also deformed in the same direction as the deformation of the other piezoelectric ceramic layers 12a in relation to the direction of the electric field applied to the insulating ceramic layer 12d during driving. It is preferable that the polarization treatment is performed in such a manner (direction). In the example of illustration, it implements, for example, applying the predetermined electric field of the above directions in the thickness direction between the 2nd electrode 12c and the auxiliary electrode which is not shown in figure.

  A first electrode 12b ′ covering the upper surface of the piezoelectric ceramic layer 12a is disposed on the upper surface of the piezoelectric driving element 12, and is spaced apart from the first electrode 12b ′ and is formed in the same layer as the second electrode 12b ′. An overhanging electrode portion 12c ′ electrically connected to the electrode 12c is also disposed. In the illustrated example, both the first electrode 12b 'and the overhanging electrode portion 12c' are disposed on the piezoelectric ceramic layer 12a, whereby the piezoelectric driving element 12 can be made compact and at the same time the first electrode 12b 'and the overhanging electrode. Electrical connection to both of the portions 12c ′ is facilitated. In the illustrated example, as shown in FIGS. 3 and 4, connection terminal pieces 12 g and 12 h are provided on the surfaces of the first electrode 12 b ′ and the overhang electrode portion 12 c ′ exposed on the upper surface of the piezoelectric driving element 12, respectively. The drive wirings 14 and 15 are conductively connected to the connection terminal pieces 12g and 12h, respectively.

The first electrode 12b ′ and the overhanging electrode portion 12c ′ are different from the illustrated example in which the first electrode 12b ′ and the overhanging electrode portion 12c ′ are arranged in the same layer as described above. One electrode 12b 'is formed in the same plane area as the other first electrode 12b, or is formed so as to extend in a plane overlapping the illustrated extension electrode part 12c', and the extension electrode part 12c 'May be arranged in a planar manner on a part of the first electrode 12b' through an insulating layer (not shown). Even in this case, the first electrode 12b 'and the overhanging electrode portion 12c' are spaced apart with the insulating layer interposed therebetween. Even in this case, the connection terminal piece 12g or the drive wiring 14 can be conductively connected at the portion of the surface of the first electrode 12b 'that is not covered with the overhanging electrode portion 12c' and the insulating layer. Since the terminal piece 12h or the drive wiring 15 can be conductively connected to the overhanging electrode portion 12c ′, the same effects as described above can be obtained although the number of manufacturing steps increases.
In this case, as described above, the region where the drive voltage is not applied in the uppermost piezoelectric ceramic layer 12a can be further reduced or eliminated, so that the deterioration of the piezoelectric performance can be prevented.

  The formation area of the overhanging electrode portion 12c ′ is preferably smaller than the formation area of the first electrode 12b ′, in particular, preferably half or less, and more preferably 1/3 or less as in the illustrated example. desirable. This is to increase the voltage application range by the first electrode 12b 'for the uppermost piezoelectric ceramic layer 12a. In this case, the overhang electrode portion 12c ′ is conductively connected to the second electrode 12c through the outer surface connection portion 12f as shown in the example of the drawing.

  Moreover, in order to suppress the distortion accompanying the expansion / contraction operation of the piezoelectric ceramic layer 12a, it is preferable that the first electrode 12b ′ and the overhanging electrode portion 12c ′ are arranged in the length direction (left-right direction in the drawing). This is because the bending direction of the piezoelectric driving body 10 is the length direction, so that the electric field application region and the non-electric field application region are not arranged in a direction different from the bending direction, and this is affected by the distortion generated between the two regions. This is to reduce.

  The above configuration is an example. For example, only the first electrode 12b ′ covering the piezoelectric ceramic layer 12a is disposed on the upper surface of the piezoelectric driving element 12, and the side surface of the piezoelectric driving element 12 (for example, one of the longitudinal directions) The second electrode 12c may be conductively connected to the drive wiring 15 on the outer surface connection portion 12f) formed on the side surface. Of course, the first electrodes 12b and 12b ′ are also configured to be conductively connected to the drive wiring 14 on the side surface (for example, the outer surface connection portion 12e formed on the other side surface in the length direction). Also good.

  The adhesive 13 is not particularly limited, but an adhesive that can firmly fix the piezoelectric driving element 12 and the metal spring plate 11 is preferable, and an adhesive that does not peel off due to the driving force of the piezoelectric driving element 12 is selected. Such an adhesive 13 is not particularly limited, but an adhesive having good adhesion to the insulating ceramic layer 12d and the metal spring 11 is preferable. In addition, since the adhesive hardness may be insufficient if the urethane adhesive or silicone adhesive is used, the risk of peeling may increase, so an adhesive capable of obtaining high hardness, for example, an epoxy adhesive may be used. It is desirable to use it.

  In the present embodiment, the piezoelectric drive element 12 is bonded to the metal spring plate 11 via the adhesive 13 in the state shown in FIGS. 1 and 2, thereby being configured as shown in FIGS. 3 and 4. In the present embodiment, a pair of piezoelectric drive elements 12 are bonded to the front and back surfaces of the metal spring plate 11 to form a bimorph type piezoelectric drive body. Alternatively, a unimorph type piezoelectric driving body in which the piezoelectric driving element 12 is bonded may be configured. In the case of the illustrated example, the connection terminal pieces 12g and 12h are each composed of a strip-shaped conductive film.

  The connection terminal piece 12g is conductively connected to the first electrode 12b 'of one piezoelectric driving element 12, and passes from the side in the width direction of the piezoelectric driving element 12 and the metal spring plate 11 from there. The piezoelectric drive element 12 further passes on the side surface in the width direction and extends on the upper surface of the first electrode 12b ′ of the other piezoelectric drive element 12 to be conductively connected. The connection terminal piece 12h is conductively connected to the overhanging electrode portion 12c 'of one piezoelectric drive element 12, and passes from the side in the width direction of the piezoelectric drive element 12 and the metal spring plate 11 from here. One piezoelectric drive element 12 further passes on the side surface in the width direction and extends onto the upper surface of the overhanging electrode portion 12c ′ of the other piezoelectric drive element 12 to be conductively connected.

  FIG. 4 is a plan view (a) and a side view (b) showing an overall shape close to the dimensions of the actual piezoelectric driving body 10. As shown in FIG. 4, the metal spring plate 11 has mounting portions 11 b and 11 b each provided with a fixing hole 11 a at both ends in the length direction (the left-right direction in the drawing), and the metal spring plate 11. Between the attachment portions 11b and 11b, an adhesion region 11c to which the above-described piezoelectric driving element 12 is adhered is provided. On the upper surface of the piezoelectric driving element 12, the first electrode 12b 'and the overhanging electrode portion 12c' are formed in a state of being arranged in the length direction.

  FIG. 5 is a plan view (a) showing the structure of the piezoelectric driving body 10 of a different embodiment, a right side view (b) and a left side view (c) partially showing a cross section. 5 (b) and 5 (c), the piezoelectric drive element 12 is shown enlarged in the thickness direction, and the actual dimension in the thickness direction is close to the mode shown in FIG. 4 (b). In FIG. 5, the same reference numerals are given to the same parts as those in the previous embodiment, and the description thereof is omitted.

  In this embodiment, what is equivalent to the connection terminal pieces 12g and 12h in the previous embodiment is constituted by the wiring member 16 constituted by a flexible wiring board (FPC) or the like. The wiring member 16 is formed by forming wiring patterns 16b and 16c made of a copper foil, an aluminum layer, etc. on the surface (outer surface in the illustrated example) made of a synthetic resin such as a polyimide resin. . Conductive connection portions 16b 'and 16c' are provided at the tips of the wiring patterns 16b and 16c, and these conductive connection portions 16b 'and 16c' are connected to the first electrode 12b 'and the overhang through the conductive adhesive 16d and the like. The electrode portion 12c 'is conductively connected.

  The conductive connection portions 16b 'and 16c' are connected to the wiring patterns 16b and 16c formed on the surface of the base body 16a and are exposed on the back surface of the base body 16a so as to penetrate the front and back surfaces of the base body 16a. Conductive connection is made to the first electrode 12b 'and the overhanging electrode portion 12c' via an adhesive 16d or the like. The wiring patterns 16 b and 16 c are conductively connected to a pair of piezoelectric drive elements 12 and 12 bonded to the front and back of the metal spring plate 11, respectively. The wiring patterns 16b and 16c are preferably conductively connected to the drive wirings 14 and 15 at the connection positions 14a and 15a such as solder at the side positions of the metal spring plate 11, respectively. Therefore, the wiring member 16 of the present embodiment integrally constitutes the connection terminal pieces 12g and 12h of the previous embodiment.

  In the present embodiment, the first electrode 12b ′ and the overhanging electrode portion 12c ′ are disposed on the upper surface of the piezoelectric driving element 12 as in the previous embodiment, so that the first wiring member 16 is provided on the integrated wiring member 16. The wiring patterns 16b and 16c can be connected to the piezoelectric drive element 12, respectively, and the wiring connection structure can be simplified.

  In the present embodiment, as shown in FIG. 6, the above-described piezoelectric driving bodies 10 and 10 are connected to the base 1 via the mounting portion 2, and the plate-like vibration is further added to these piezoelectric driving bodies 10 and 10. By connecting the springs 3 and 3 and connecting to the transport body 5 via the attachment portion 4, the component transport device 20 can be configured. Here, the plurality of piezoelectric driving bodies 10 and 10 are connected to the conveying body 5 via the vibration spring 3 at positions separated in the conveying direction F. In the component conveying device 20, the conveying body 5 can be reciprocated in the conveying direction F by alternately applying positive and negative driving voltages to the piezoelectric driving body 10. A linear transport track (not shown) extending in the transport direction F is formed on the transport body 5, and components not shown move along the transport direction F on the transport track. In the illustrated example, a linear vibrator for configuring a linear part feeder that vibrates the transport body 5 in the left-right direction in the figure is configured. However, for example, a spiral transport track is formed by the piezoelectric drive body 10 of the present embodiment. It is also possible to constitute a rotary vibrator that vibrates the provided transport body in the rotational direction. In this case, the transport direction F is a rotational direction around the axis.

  In the illustrated example, by alternately applying positive and negative drive voltages between the drive terminals T1 and T2, the piezoelectric drive body 10 bends and vibrates in the length direction, and this vibration is transmitted through the vibration springs 3 and 3 through the conveying body 5. Vibrate. At this time, the resonance frequency of the vibrator is determined by the vibration characteristics of the piezoelectric drive body 10, the elastic constant of the vibration spring 3, and the inertia weight mainly of the transport body 5. In such a component conveying device 20, although vibration is induced by the piezoelectric driving body 10, the vibration mode itself is determined by the elastic constant and inertia weight of the vibration system, and thus a large load is applied to the piezoelectric driving body 10. As a result, stress also acts between the piezoelectric drive element 12 and the metal spring plate 11. Normally, the metal spring plate 11 has sufficient toughness, but the piezoelectric ceramic layer 12a generally has low toughness, and breaks when an excessive load is applied. In particular, when peeling occurs on a part of the bonding surface between the piezoelectric drive element 12 and the metal spring plate 12, the stress load is concentrated on the peeling portion, and the piezoelectric ceramic layer 12a is often cracked at the portion.

  Next, as the piezoelectric drive element 12 having the above-described configuration, a PZT-made piezoelectric ceramic layer 12a having a thickness of 110 μm is stacked, and a PZT-made insulating ceramic layer 12d having a thickness of 55 μm is used. A JIS SUP10 (chrome vanadium steel) having a width of 24 mm, a length of 43 mm, and a thickness of 3 mm was used as an example, and a piezoelectric driving body 10 having a bimorph structure was manufactured as an example. The piezoelectric driving body 10 of this example was incorporated in the component conveying apparatus shown in FIG. 5, and was driven by alternately applying a frequency of 240 Hz and a positive / negative driving voltage of 50V. The horizontal amplitude was 0.94 mm. When operated continuously for one month under these conditions, it was confirmed that there was no change in frequency, no change in amplitude, and there was no problem in durability.

[Comparative Example 1]
On the other hand, a piezoelectric driving element having the same piezoelectric ceramic layer 12a as that of the piezoelectric driving element 12 but not provided with the insulating ceramic layer 12d is bonded to the metal spring plate 11 similar to the above to form a bimorph piezoelectric driving body. Formed. At this time, an insulating substrate made of glass epoxy and having a wiring pattern made of copper foil on the surface is interposed between the piezoelectric driving element and the metal spring plate 11, and the insulating substrate, the piezoelectric driving element, A comparative example 1 was manufactured by bonding an insulating substrate and a metal spring plate 11 with an epoxy adhesive. The wiring pattern is conductively connected to the electrode on the back surface side and is connected to the driving wiring. The comparative example 1 was incorporated in the component conveying apparatus shown in FIG. 5 and driven by alternately applying a frequency of 246.1 Hz and a positive / negative drive voltage of 50V. The horizontal amplitude was 0.94 mm. The piezoelectric driving element was broken immediately after the horizontal amplitude dropped to 0.52 mm 5 minutes after starting driving under these conditions. When this piezoelectric driving body was examined, a peeling portion extending in the width direction was observed between the insulating substrate and the metal spring plate, and the piezoelectric driving element was cracked at a position corresponding to the peeling portion. This is because the adhesion between the insulating substrate and the metal spring plate is inadequate, and the insulating substrate has low rigidity, so that peeling occurs and stress concentrates on the peeling portion, resulting in damage to the piezoelectric drive element. Conceivable.

[Comparative Example 2]
Further, a piezoelectric driving element having a laminated structure of the same piezoelectric ceramic layer 12a as the above-described piezoelectric driving element 12 but not provided with an insulating ceramic layer 12d (having a structure in which the second electrode 12c is exposed on the back surface) is described above. A piezoelectric drive body having a bimorph structure was formed by adhering to the same metal spring plate 11. In this case, alumina _(Al 2 _{O 3)} made in the thickness 0.625mm and 0.5mm of insulating ceramic substrate were respectively interposed between the piezoelectric drive element and the metal spring plate 11, the insulating ceramic substrate and the piezoelectric drive element Two types of comparative examples 2 were produced by bonding the insulating ceramic substrate and the metal spring plate 11 with an epoxy adhesive. These Comparative Examples 2 were incorporated in the component conveying apparatus shown in FIG. 5, and were driven by alternately applying a frequency of 240 to 250 Hz and a positive / negative drive voltage of 50V. The horizontal amplitudes were all 0.60 mm or less. This indicates that the driving force is greatly reduced as compared with the above-described example and comparative example 1. Further, the piezoelectric driving element broke after a while after starting driving under these conditions. When this piezoelectric driving body was examined, a peeling portion extending in the width direction was observed between the insulating ceramic substrate and the piezoelectric driving element, and the piezoelectric driving element was cracked at a position corresponding to the peeling portion. The time of break was after a lapse of time from Comparative Example 1 above. This is because the adhesive force between the insulating ceramic substrate and the metal spring plate 11 is strong, but since the insulating ceramic substrate is difficult to deform, a loss of driving force occurs and the piezoelectric driving element and the insulating ceramic substrate are not deformed. It is considered that the piezoelectric drive element was damaged as a result of the stress being applied to the adhesive layer to cause peeling and the stress being concentrated on the peeled portion.

  As described above, in the present embodiment, the insulating ceramic layer 12d is previously formed integrally with the piezoelectric driving element 12, so that the adhesive strength with the metal spring plate 11 is increased, and the piezoelectric driving element 12 is damaged due to peeling. It was found that the loss of driving force and the loss of driving force were reduced. That is, the piezoelectric driving body 10 of the present embodiment has excellent durability and high driving efficiency. In particular, it has been found that the loss of driving force is reduced by using a thinner insulating ceramic layer 12d than the piezoelectric ceramic layer 12a. Moreover, since the difference in mechanical characteristics is eliminated by using the same material for the insulating ceramic layer 12d as that of the piezoelectric ceramic layer 12a, it may be difficult to peel off.

In addition, the piezoelectric drive body and the vibration type conveying device for the vibration type conveying device of the present invention are not limited to the above illustrated examples, and various modifications can be made without departing from the gist of the present invention. Of course. For example, in the above embodiment using the laminated piezoelectric driving element formed by stacking a plurality of piezoelectric ceramic layers, but it may be a piezoelectric drive device having a piezoelectric ceramic layer of a single layer.

DESCRIPTION OF SYMBOLS 10 ... Piezoelectric drive body, 11 ... Metal spring board, 12 ... Piezoelectric drive element, 12a ... Piezoelectric ceramic layer, 12b, 12b '... 1st electrode, 12c ... 2nd electrode, 12c' ... Overhang connection part, 12d ... Insulating ceramic layer, 12e, 12f ... External connection part, 12g, 12h ... Connection terminal, 13 ... Adhesive (adhesive layer), 14, 15 ... Drive wiring, 16 ... Wiring member, 16a ... Base, 16b, 16c ... Wiring Patterns, 16b ', 16c' ... conductive connection part, 1 ... base, 2 ... mounting part, 3 ... vibration spring, 4 ... mounting part, 5 ... transport body, 20 ... vibratory transfer device

Claims (7)

A metal spring plate;
The piezoelectric ceramic layer, the first electrode and the second electrode arranged on the front and back surfaces of the piezoelectric ceramic layer, and the first electrode or the first electrode exposed on the back surface are arranged to overlap the metal spring plate. A piezoelectric driving element formed by integrally sintering an insulating ceramic layer covering two electrodes;
An adhesive layer for bonding the insulating ceramic layer and the metal spring plate;
A piezoelectric driver characterized by comprising:   The piezoelectric driver according to claim 1, wherein the insulating ceramic layer is made of the same material as the piezoelectric ceramic layer.   The piezoelectric driver according to claim 1, wherein the insulating ceramic layer is thinner than the piezoelectric ceramic layer.   The upper surface of the piezoelectric driving element is provided with the first electrode, and an overhang electrode portion that is separated from the first electrode and is conductively connected to the second electrode. The piezoelectric driving body according to any one of 1 to 3.   5. The piezoelectric driver according to claim 4, wherein the overhang electrode portion is formed in the same layer as the first electrode and has a smaller area than the first electrode.   6. The piezoelectric drive according to claim 1, wherein in the piezoelectric drive element, a plurality of the piezoelectric ceramic layers are stacked via the first electrode or the second electrode. 7. body. A base, a transport body disposed above the base, and a piezoelectric driving body connected between the base and the transport body,
The piezoelectric driver is arranged to overlap the metal spring plate, the piezoelectric ceramic layer, the first electrode and the second electrode arranged on the front and back of the piezoelectric ceramic layer, and the back surface A piezoelectric driving element formed by integrally sintering an insulating ceramic layer exposed to the first electrode or the second electrode, and an adhesive layer for bonding the insulating ceramic layer and the metal spring plate And a vibratory transfer device.

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