JP4646962B2 - Positioning device - Google Patents

Description

  The present invention relates to a positioning device equipped with a multilayer piezoelectric element.

  Laminated piezoelectric actuators can adjust the amount of displacement on the order of sub-microns, have fast response to electrical signals, and generate a large force. For example, they can be used in precision positioning devices such as an XY stage. It is used.

  FIG. 7 is a schematic cross-sectional view showing the structure of a general laminated piezoelectric actuator 90. The laminated piezoelectric actuator 90 includes piezoelectric ceramics 91 and internal electrodes 92 that are alternately laminated. The internal electrodes 92 are connected to the external electrodes 93a and 93b every other layer so that an electric field in the opposite direction is applied by the internal electrodes 92. Generally, the external electrodes 93a and 93b are formed by printing and baking a silver paste.

Further, lead wires 94a and 94b are attached to the external electrodes 93a and 93b by soldering or the like, respectively. A resin coating 96 having excellent moisture resistance is provided on the side surface of the laminate 95 composed of the piezoelectric ceramic 91 and the internal electrode 92 (referred to as a plane parallel to the lamination direction of the piezoelectric ceramic 91). The resin coating 96 serves to protect the laminated body 95 and the external electrodes 93a and 93b from water vapor in the environment where the piezoelectric actuator 90 is used.
JP 09-181368 A JP 2001-196656 A JP 2001-189499 A

  However, in the piezoelectric actuator 90, since the lead wires 94a and 94b are soldered to the thin external electrodes 93a and 93b, the attachment strength of the lead wires 94a and 94b is weak, and thus the lead wires 94a and 94b are disconnected. There is a problem that it is easy. In addition, since the lead wires 94a and 94b are provided on the side surfaces of the laminated body 95, when mounting the piezoelectric actuator 90 on a positioning device or the like, a wide mounting space is required. It becomes difficult to reduce the size.

  Further, in the method of coating the laminate 95 using the resin coating 96, water vapor contained in the air enters the side surface of the laminate 95 through the resin coating 96 under long-term use or severe temperature and humidity environment. There is a problem that causes side discharge. More generally, a silver (Ag) / palladium (Pd) electrode is used as the internal electrode 92, and a silver electrode is used for the external electrodes 93a and 93b. There is a problem that silver causes migration to lower the insulation resistance of the piezoelectric actuator 90, which causes dielectric breakdown.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a compact positioning device.

  That is, according to the present invention, a pair of lead members for sending a drive signal is taken out from the lower end surface, a cylindrical laminated piezoelectric element, a column having a threaded tip, and the pair of lead members are led out to the outside. A pedestal member that supports the multilayer piezoelectric element through the support column in the inner hole of the multilayer piezoelectric element, an inner hole, and the outer side surface is threaded to the inner hole. A cylindrical member placed on the multilayer piezoelectric element so as to contact the upper end surface of the multilayer piezoelectric element through the support column, an inner hole, and the cylindrical member passing through the support column in the inner hole. A disc spring held at the top, and a disc spring at the tip of the support column so that a predetermined holding force is applied to the stacked piezoelectric element between the cylindrical member and the pedestal via the disc spring. A nut member fixed in contact with the outer side of the cylindrical member; A cover member fitted to a threaded portion provided on a side surface and covering the multilayer piezoelectric element, and by applying a predetermined drive signal to the pair of lead members, the multilayer piezoelectric element is driven to expand and contract. A positioning device is provided that moves the cover member according to the displacement generated in the multilayer piezoelectric element via the cylindrical member.

  By using the laminated piezoelectric element from which the lead member is taken out from the end face, the positioning device can be made compact.

  Moreover, since the expansion and contraction of the disc spring can be adjusted by adjusting the position of the nut member, the holding force of the multilayer piezoelectric element can be easily set to a desired value.

  In addition, by providing a rotation prevention pin for preventing the rotation of the nut member around the nut member, the stacked piezoelectric element can be held with a constant holding force.

  According to the present invention, a compact positioning device can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic structure of a laminated piezoelectric actuator (hereinafter referred to as “piezoelectric actuator”) 10. The laminated body 11 which is a base body of the piezoelectric actuator 10 includes a protective layer 23a, a piezoelectric active part 21, a protective layer 23b, an electrode lead-out part 22, and a protective layer 23c which are integrally laminated in this order in the Z direction. The laminate 11 has a cylindrical shape in which a hole 24 is formed at the center.

  On the outer peripheral side surface of the multilayer body 11, external electrodes 14a and 14b, a glass film 19a that protects the multilayer body 11 from water vapor, and a resin film 20a that protects the glass film 19a are provided. Further, a glass coating 19 b and a resin coating 20 b are provided on the inner peripheral side surface (side wall of the hole 24) of the laminate 11. The piezoelectric active portion 21 has a structure in which piezoelectric ceramics 12a and internal electrodes 13 are alternately stacked in the Z direction, and the internal electrodes 13 are electrically connected to the external electrodes 14a and 14b every other layer. . Hereinafter, the internal electrode connected to the external electrode 14a is referred to as an internal electrode 13a, and the internal electrode connected to the external electrode 14b is referred to as an internal electrode 13b.

  The external electrode 14a is electrically connected to the lead wire 16a via an extraction electrode 18a provided in the electrode extraction portion 22, and the external electrode 14b is connected to a lead wire via an extraction electrode 18b provided in the electrode extraction portion 22. 16b is electrically connected. The structure of the electrode extraction portion 22 will be described in detail later.

  The piezoelectric ceramic 12a is subjected to a polarization treatment by applying a predetermined voltage between the lead wires 16a and 16b. In this state, when a predetermined drive voltage is applied between the lead wires 16a and 16b, expansion / contraction displacement due to the piezoelectric characteristics of the piezoelectric ceramic 12a occurs in the Z direction.

  In general, as the piezoelectric ceramic 12a, a material having a large piezoelectric constant d33 and an electromechanical coupling coefficient k33, for example, a lead zirconate titanate (abbreviated as PZT) type piezoelectric ceramic is preferably used. A large displacement can be obtained with a smaller driving voltage. As will be described later, since the laminate 11 is preferably manufactured by a simultaneous firing method, silver (Ag) / palladium (Pd) electrodes are preferably used as the internal electrodes 13a and 13b. On the other hand, silver electrodes are preferably used as the external electrodes 14a and 14b.

  The protective layers 23a, 23b, and 23c are made of the same material as the piezoelectric ceramic 12a. The protective layers 23a and 23c are provided as necessary, for example, so that the displacement amount of the end face of the piezoelectric actuator 10 is constant over the entire end face, and considering the convenience when the piezoelectric actuator 10 is incorporated into various devices. . The protective layers 23a and 23c are piezoelectric inactive portions that do not exhibit voltage characteristics because no voltage is applied thereto.

  The protective layer 23 b is provided as a stress buffer layer between the piezoelectric active portion 21 and the electrode extraction portion 22. However, since the electrode lead-out portion 22 also has a function as a piezoelectric inactive protective layer, the protective layer 23b is not always necessary.

  In addition, as shown in FIG. 1, when the internal electrode 13b exists in the lowest part of the piezoelectric active part 21, the part between the extraction electrode 18a and the internal electrode 13b of the protective layer 23b is between external electrodes 14a and 14b. It becomes piezoelectrically active when a voltage is applied to. However, since the thickness of the protective layer 23b is larger than the thickness of the piezoelectric ceramic 12a, the amount of displacement is small. Therefore, the protective layer 23b can be handled as a substantially piezoelectric inactive portion. In contrast, the portion of the protective layer 23b between the internal electrode 13b and the extraction electrode 18b is piezoelectrically inactive because the internal electrode 13b and the extraction electrode 18b are at the same potential.

  The electrode lead-out part 22 has portions where the piezoelectric ceramics 12b and the extraction electrodes 18a are alternately stacked, and portions where the piezoelectric ceramics 12b and the extraction electrodes 18b are alternately stacked. The extraction electrode 18a and the extraction electrode 18b are located at the same height in the Z direction, but they are insulated in the XY plane. Even if a predetermined voltage is applied between the lead wires 16a and 16b, a potential difference in the Z direction does not occur in the electrode lead-out portion 22. For this reason, the electrode extraction part 22 is piezoelectrically inactive.

  The extraction electrode 18a is electrically connected to the external electrode 14a, and the extraction electrode 18b is electrically connected to the external electrode 14b. In the electrode lead-out portion 22 and the protective layer 23c, independent through holes 15a and 15b having openings on the end face of the laminate 11 are formed. The lead electrode 18a is exposed on the side surface of the through hole 15a, and the lead electrode 18b. Is exposed on the side surface of the through hole 15b. The through holes 15a and 15b are filled with metal 17 so that the extraction electrodes 18a and 18b do not directly contact the outside air in the through holes 15a and 15b, respectively, and the metal 17 filled in the through holes 15a. The lead wire 16a is attached to the metal 17 and the lead wire 16b is attached to the metal 17 filled in the through hole 15b.

  Thus, in order for the extraction electrodes 18a and 18b to play a role in electrically connecting the lead wires 16a and 16b and the external electrodes 14a and 14b, respectively, it is preferable that the resistance of the extraction electrodes 18a and 18b is small. As a method of reducing the resistance of the extraction electrodes 18a and 18b, a method of increasing the electrode area and a method of increasing the number of layers are preferably used. As described above, since the laminate 11 is preferably manufactured by the co-firing method, silver (Ag) / palladium (Pd) electrodes are preferably used as the extraction electrodes 18a and 18b.

  As the metal 17, a molten material can be poured into the through holes 15 a and 15 b, or a solid structure can be easily melted after filling the through holes 15 a and 15 b with a solid material to form a uniform structure However, a tin alloy such as solder is preferably used. By bringing the metal 17 into a molten state once in the through holes 15a and 15b, the metal 17 and the extraction electrodes 18a and 18b can be connected with low resistance, and the lead wires 16a and 16b can be easily attached. it can.

  As the lead wires 16a and 16b, single-core wires or multi-core wires coated with a resin such as silicon resin or fluororesin are preferably used. When such a covered electric wire is used as the lead wires 16a and 16b, the coating of the lead wires 16a and 16b is inserted into the through holes 15a and 15b.

  The electrode take-out portion 22 has a sealing structure in which the extraction electrodes 18a and 18b are not in direct contact with the outside air by the metal 17, so that water vapor permeates into the boundary between the extraction electrodes 18a and 18b and the piezoelectric ceramic 12b. Can be prevented, and thus reliability can be improved.

  In addition, by attaching the lead wires 16a and 16b to the piezoelectric inactive electrode lead-out portion 22, the detachment of the lead wires 16a and 16b can be prevented. In addition, by attaching the lead wires 16a and 16b to the inner portions of the through holes 15a and 15b, it is difficult to apply a large stress to the attachment portions of the lead wires 16a and 16b, thereby further preventing the lead wires 16a and 16b from being detached. And durability is increased. Furthermore, since the lead wires 16a and 16b are taken out from the end face of the piezoelectric actuator 10, the mounting volume required when mounting the piezoelectric actuator 10 to various devices can be reduced.

  A glass coating 19a is formed on the outer peripheral side surface of the laminate 11 so that the external electrodes 14a and 14b, the internal electrodes 13a and 13b, and the extraction electrodes 18a and 18b are completely covered. Since glass does not allow water vapor to permeate, this glass coating 19a can prevent water vapor from permeating into the outer peripheral side surface of the laminate 11. Thereby, generation | occurrence | production of the short circuit (side surface discharge) on the outer peripheral side surface of the laminated body 11 is prevented, and the fall of the insulation resistance by silver migration contained in the internal electrodes 13a * 13b is suppressed. Thus, the reliability and durability of the piezoelectric actuator 10 are improved.

  In the piezoelectric actuator 10, the internal electrodes 13 a, 13 b and the extraction electrodes 18 a, 18 b are not exposed on the inner peripheral side surface of the multilayer body 11, but by forming a glass film 19 b in this portion, the multilayer body 11 is made from water vapor. More reliably protected. Of course, when the internal electrodes 13a and 13b and / or the extraction electrodes 18a and 18b are exposed on the inner peripheral side surface of the laminated body 11, the insulation resistance of the internal electrodes 13a and 13b is reduced by forming the glass coating 19b. Can be prevented.

Examples of the material for the glass coatings 19a and 19b include borosilicate glass (B ₂ O ₃ —SiO ₂ system), borate glass (B ₂ O ₃ system), lead silicate glass (PbO—SiO ₂ system), and phosphate. Glass (PO ₃ series) can be mentioned. Here, in order to increase the insulation resistance of the glass coatings 19a and 19b themselves, the content of the alkali metal component is preferably 100 ppm or less. The thermal expansion coefficient of the glass coatings 19 a and 19 b is preferably slightly larger than the thermal expansion coefficient of the piezoelectric ceramic 12. In this case, when the glass coatings 19a and 19b are formed by firing and then cooled to room temperature, a compressive stress is applied to the glass coatings 19a and 19b. Increases durability and durability.

For the glass coatings 19a and 19b, for example, alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ) titania (TiO ₂ ), quartz (SiO ₂ ), lead titanate (PbTiO ₃ ), zirconium silicate (ZrO ₂ — It is preferable to disperse crystalline powders such as SiO ₂ ), cordierite (2MgO · 2Al ₂ O ₃ · 5SiO ₂ ), and piezoelectric ceramic powder having the same composition as the piezoelectric ceramic 12a substantially uniformly. Thereby, the thermal expansion coefficient of the glass coatings 19a and 19b can be brought close to the thermal expansion coefficient of the piezoelectric ceramics 12a, and the occurrence of cracks in the glass coatings 19a and 19b can be prevented. Further, when the closed cells are dispersed substantially uniformly in the glass coatings 19a and 19b, the durability of the glass coatings 19a and 19b can be enhanced by a stress relaxation effect by the closed cells.

  A resin coating 20a formed so as to cover the entire glass coating 19a on the outer peripheral side surface of the laminate 11, and a resin coating 20b provided so as to cover the entire glass coating 19b on the inner peripheral side of the laminate 11 are made of glass. The penetration of water vapor into the coatings 19a and 19b is suppressed, and consequently the penetration of water vapor into the laminate 11 is suppressed. As the resin material used for the resin coatings 20a and 20b, an epoxy resin having excellent moisture resistance is preferably used.

  Next, a method for manufacturing the piezoelectric actuator 10 will be described. FIG. 2 is an explanatory diagram (flow chart) showing a schematic manufacturing process when the piezoelectric actuator 10 is manufactured by the simultaneous firing method.

  First, by using a piezoelectric ceramic powder such as lead zirconate titanate having a predetermined composition, a known thick film manufacturing method such as a doctor blade method or an extrusion molding method, for example, a green having a predetermined thickness of about 20 μm to 150 μm. A sheet is produced (step 1). Subsequently, the green sheet is punched into a ring shape (step 2), and electrode paste is printed in a predetermined pattern on the punched green sheet by a screen printing method or the like (step 3). In addition, since the piezoelectric ceramic is generally fired at 1200 ° C. to 1300 ° C., a silver (Ag) / palladium (Pd) paste that can withstand such a high temperature is suitably used as the electrode paste.

  FIG. 3 is a plan view of various green sheets produced in Step 3. The green sheet 71 shown in FIG. 3A is used for forming the protective layers 23a and 23b. The electrode paste is not printed on the green sheet 71. 3B is printed with an electrode pattern of the internal electrode 13a, and the green sheet 73 shown in FIG. 3C has the electrode paste 13b ′ as an internal electrode. It is printed with an electrode pattern 13b. These green sheets 72 and 73 are used for forming the piezoelectric active portion 21. Note that the green sheet 72 and the green sheet 73 are symmetrical as shown in FIG. Therefore, the number of green sheets 72 that is twice the required number of green sheets 72 may be produced, and half of the green sheets 72 may be used as the green sheets 73.

  The green sheet 74 shown in FIG. 3D is used for forming the electrode extraction portion 22. On the green sheet 74, holes 15a 'and 15b' that become through holes 15a and 15b after firing are formed, and electrode pastes 18a 'and 18b' are printed in the electrode patterns of the extraction electrodes 18a and 18b, respectively. The green sheet 75 shown in FIG. 3 (e) is used for forming the protective layer 23c. No electrode paste is printed on the green sheet 75, but hole portions 15a 'and 15b' which become through holes 15a and 15b after firing are formed.

  After producing the green sheets 71 to 75 in this way, a predetermined number of green sheets 71 to 75 are stacked while being aligned with the pressing mold in a predetermined order (step 4). For example, first, several to tens of green sheets 75 for forming the protective layer 23c are stacked, and several green sheets 74 for forming the electrode take-out portion 22 are stacked thereon, and the protective layer 23b is formed thereon. A plurality of green sheets 71 for forming the piezoelectric active portion 21, and a predetermined number of green sheets 72 and green sheets 73 for alternately stacking the green sheets 71, and a protective layer 23a formed thereon. Several to dozens of green sheets 71 are stacked.

  Next, the green sheets 71 to 75 thus stacked are subjected to a hot press process (step 5). By this hot pressing, the upper and lower green sheets are pressure-bonded to obtain a green laminated body in which the green sheets 71 to 75 are integrated. Subsequently, the green laminate is fired under a predetermined condition (Step 6). Thereby, the laminated body 11 is obtained. Grinding or polishing is applied to the inner peripheral surface, outer peripheral surface and end surface of the obtained laminate 11 and the side surfaces of the through holes 15a and 15b as necessary.

  Next, a predetermined position on the outer peripheral side surface of the multilayer body 11 so that the internal electrodes 13a and the extraction electrode 18a are electrically connected, and the internal electrodes 13b and the extraction electrode 18b are electrically connected. Then, an electrode paste to be the external electrodes 14a and 14b is printed and fired at a predetermined temperature (step 7). As the electrode paste used at this time, a silver paste that can be fired at about 500 ° C. to 800 ° C. lower than the firing temperature of the green laminate is suitably used.

  Subsequently, a glass paste is applied to the outer peripheral side surface and inner peripheral side surface of the laminate 11 with a predetermined thickness, for example, 30 μm to 300 μm, and baked (step 8). As a result, glass coatings 19a and 19b are formed. Here, the glass paste is applied so that the internal electrodes 13a and 13b, the external electrodes 14a and 14b, and the extraction electrodes 18a and 18b are not exposed to the outside. The firing temperature of the glass paste is set to be equal to or lower than the firing temperature of the external electrodes 13a and 13b. Examples of the method for applying the glass paste include brush coating and dipping.

  In addition, when the shape of a laminated body is a rectangular parallelepiped etc., glass paste can be apply | coated by screen printing. Moreover, when apply | coating a glass paste to the laminated body 11 by dipping, it is preferable to make a glass paste into a slurry form with a low viscosity. When the firing temperatures of the external electrodes 14a and 14b and the glass paste are the same, they can be fired simultaneously.

  Subsequently, resin coatings 20a and 20b are simultaneously formed on the outer peripheral side surface and the inner peripheral side surface of the laminate 11 (step 9). At this time, the end face of the laminate 11 is masked as necessary. Examples of the method for forming the resin coatings 20a and 20b include dipping and powder coating.

  Next, the lead wires 16a and 16b are inserted into the through holes 15a and 15b, solder is poured into the deep portions of the through holes 15a and 15b, and the lead wires 16a and 16b are attached (step 10). At this time, the extraction electrodes 18a and 18b exposed on the side surfaces of the through holes 15a and 15b are prevented from being exposed to the outside by the poured solder. The steps 9 and 10 can be performed in the reverse order. Finally, the piezoelectric ceramic 12a is polarized by applying a voltage between the lead wires 16a and 16b (step 11). Thus, the piezoelectric actuator 10 is obtained.

  Next, an embodiment of a positioner (positioning device) equipped with the piezoelectric actuator 10 will be described. FIG. 4 is a sectional view showing a schematic structure of the positioner 50. The positioner 50 includes the piezoelectric actuator 10, a pedestal member 51, a cylindrical member 52, a disc spring 53, a nut member 54, and a cover member 55.

  The pedestal member 51 includes a column portion 61 whose tip is threaded and lead wire outlet holes 62 a and 62 b that lead out lead wires 16 a and 16 b provided in the piezoelectric actuator 10 to the outside. The piezoelectric actuator 10 is supported in a state where the support 61 is passed through the hole 24. Further, the pedestal member 51 is formed with a screw hole 63, and the pedestal member 51 is fixed to a predetermined position such as an XY stage, for example, an immovable portion using the screw hole 63.

  The outer side surface of the cylindrical member 52 is threaded. The cylindrical member 52 is placed on the piezoelectric actuator 10 so that the support 61 is passed through the inner hole and is in contact with the upper end surface of the piezoelectric actuator 10.

  The disc spring 53 has a substantially ring shape (two disc springs are shown in FIG. 4). A helical spring may be used instead of the disc spring 53. The disc spring 53 is held on the upper part of the tubular member 52 in a state in which the support 61 is passed through the inner hole.

  The nut member 54 is attached to the threaded portion at the tip of the column portion 61. The nut member 54 is attached to the distal end portion of the support column 61 so as to contact the disc spring 53 so that a predetermined holding force is applied to the piezoelectric actuator 10 between the cylindrical member 52 and the base member 51 via the disc spring 53. Fixed. In other words, when the nut member 54 is gradually screwed, the disc spring 53 is contracted. Accordingly, the disc spring 53 strongly presses the cylindrical member 52 toward the piezoelectric actuator 10, and the piezoelectric actuator 10 receives an appropriate pre-pressure between the pedestal member 51 and the cylindrical member 52 by this pressing force. Held in.

  The cover member 55 is fixed (screwed) to the tubular member 52 at the threaded portion of the outer peripheral side surface of the tubular member 52 so as to cover the piezoelectric actuator 10. The cover member 55 is formed with a threaded screw hole. FIG. 4 shows a state in which a bolt 66 having a hemispherical head is attached to the screw hole, and a moving object 67 (for example, a movable part of the XY stage) is in contact with the bolt 66. Yes.

  A moving object that needs to be aligned may be directly connected to the screw hole provided in the cover member 55. Further, if the rotation prevention pin 65 for preventing the rotation of the nut member 54 is provided between the cover member 55 and the nut member 54, the holding force of the piezoelectric actuator 10 can be always kept constant.

  In the positioner 50 having such a structure, when a predetermined voltage is applied between the lead wires 16a and 16b led to the outside, the expansion / contraction displacement of the piezoelectric actuator 10 is transmitted to the cover member 55 via the cylindrical member 52, Expansion and contraction equivalent to that of the piezoelectric actuator 10 occurs in the cover member 55 and the bolt 66. Thereby, the bolt 66 can displace the moving object 67. In addition, the loss of the transmission of the force from the volt | bolt 66 to the moving object 67 can be made small by making the part which contact | abuts the volt | bolt 66 in the moving object 67 into a V groove shape.

  By using the piezoelectric actuator 10 in which the lead wires 16a and 16b are provided on the end surfaces, the inner diameter and the outer diameter of the cover member 55 can be shortened, thereby making the positioner 50 compact. Further, the lead wires 16a and 16b provided in the piezoelectric actuator 10 can be easily led out of the positioner 50. Furthermore, it is easy to change the holding force applied to the piezoelectric actuator 10 by changing the position of the nut member 54.

  Next, another embodiment of the present invention will be described. FIG. 5 is a cross-sectional view showing a schematic structure of a stacked piezoelectric actuator 30 according to another embodiment of the present invention, and FIG. 6 is a plan view showing various green sheets used for manufacturing the piezoelectric actuator 30. A laminated body 31 which is a base body of the piezoelectric actuator 30 is formed of a protective layer 33a made of piezoelectric ceramics, a piezoelectric active part 32 in which internal electrodes 35a and 35b and piezoelectric ceramics 36 are laminated, and piezoelectric ceramics in the Z direction. The protective layer 33b has a structure in which these layers are integrally laminated in this order.

  The laminated body 31 has a cylindrical shape in which a hole 44 is formed at the center, and a glass coating 39 for protecting the laminated body 31 from water vapor and glass on the inner peripheral side surface and the outer peripheral side surface of the laminated body 31, respectively. A resin coating 40 that protects the coating 39 is provided. Further, the through-hole electrodes 34 a and 34 b are formed so as to penetrate the piezoelectric active portion 32 and the protective layer 33 b and have an opening on the lower end surface of the multilayer body 31. The through-hole electrode 34a is electrically connected to the internal electrode 35a, and the through-hole electrode 34b is electrically connected to the internal electrode 35b.

  The lead wires 37a and 37b are attached using solder or the like so as to be electrically connected to the through-hole electrodes 34a and 34b in the laminated body 31, respectively. The piezoelectric actuator 30 also has a structure in which the lead wires 37a and 37b are taken out from the end face of the laminated body 31 and the lead wires 37a and 37b are not easily detached. Further, since the attachment portions of the lead wires 37a and 37b have a hermetic seal structure, it is possible to prevent water vapor from penetrating into the laminate 31 from the attachment portions of the lead wires 37a and 37b.

  Since the manufacturing method of the piezoelectric actuator 30 having such a structure conforms to the simultaneous firing method described above, only the green sheet used for manufacturing the piezoelectric actuator 30 will be described here. The green sheet 81 shown in FIG. 6A is used to form the protective layer 33a, and the green sheets 82 and 83 shown in FIGS. 6B and 6C are used to form the piezoelectric active portion 32. The green sheets 84 and 85 shown in FIGS. 6D and 6E are used to form the protective layer 33b.

  The protective layer 33b is formed by stacking a predetermined number of green sheets 85 and stacking a predetermined number of green sheets 84 thereon. The green sheet 85 has holes 85a and 85b so that the lead wires 37a and 37b can be inserted later. In addition, it is preferable to apply an electrode paste on the side surfaces of the holes 85a and 85b and in the vicinity thereof. Holes 84a and 84b for forming through-hole electrodes 34a and 34b are formed in the green sheet 84, and electrode pastes 86c and 86d are respectively applied to the side surfaces of the holes 84a and 84b and in the vicinity thereof. Yes.

  The piezoelectric active portion 32 is formed by alternately stacking a predetermined number of green sheets 82 and 83 on the green sheet 84. On the green sheet 82, an electrode paste 35a 'for forming the internal electrode 35a is printed, and holes 82a and 82b for forming the through-hole electrodes 34a and 34b are formed. An electrode paste (not shown) is applied to the side surface of the hole 82a so as to be continuous with the electrode paste 35a '. The electrode paste 86a is printed on the side surface of the hole 82b and the vicinity thereof, but the electrode paste 35a 'is not printed in a predetermined range around the hole 82b. The paste 35a 'is electrically insulated.

  On the green sheet 83, an electrode paste 35b ′ for forming the internal electrode 35b is printed, and holes 83a and 83b for forming the through-hole electrodes 34a and 34b are formed. An electrode paste (not shown) is applied to the side surface of the hole 83b so as to be continuous with the electrode paste 35b ′. The electrode paste 86b is printed on the side surface of the hole 83a and the vicinity thereof, but the electrode paste 35b 'is not printed in a predetermined range around the hole 83a. The paste 35b 'is electrically insulated.

  When such green sheets 82 and 83 are alternately laminated, when the holes 82a, 83a, and 84a communicate with each other, the upper and lower sides conduct, thereby forming a through-hole electrode 34a. The through-hole electrode 34a is formed of the electrode paste 35a. '(That is, the internal electrode 35a) is continuous, but is not continuous with the electrode paste 35b' (that is, the internal electrode 35b). On the contrary, when the holes 82b, 83b, 84b communicate with each other, the upper and lower sides conduct, thereby forming the through-hole electrode 34b. The through-hole electrode 34b is continuous with the electrode paste 35b ', but the electrode paste 35a' Are not continuous.

  The protective layer 33 a is formed by stacking a predetermined number of green sheets 81 on the green sheets 82 and 83. No electrode paste is printed on the green sheet 81, and no hole is formed.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the said embodiment. For example, although the multilayer piezoelectric element has been described as having a cylindrical shape, the multilayer piezoelectric element may be a prismatic type or a columnar type. Further, as the internal electrode structure of the piezoelectric actuator 10, a structure generally referred to as a multilayer capacitor type is shown, but a known full surface electrode type structure or a slit type (stress relaxation type) structure may be used.

  As described above, in the multilayer piezoelectric element according to the embodiment of the present invention, the attachment strength of the lead member is large, and the attachment portion of the lead member is at the back of the through hole. Further, since the lead member is attached to the piezoelectric inactive portion, the effect of preventing the lead member from being detached is obtained. In addition, since the attachment portion of the lead member has a hermetic seal structure made of metal, the penetration of water vapor into the laminated body is prevented, and the effect of preventing the penetration of water vapor into the laminated body is also obtained by the glass coating. . Thereby, the multilayer piezoelectric element of the present invention has high reliability.

  Further, in the positioning device using the laminated piezoelectric element in which the lead member is taken out from the end face, the space for mounting the laminated piezoelectric element can be reduced. This makes it possible to reduce the size of the positioning device. Moreover, since the expansion and contraction of the disc spring can be adjusted by adjusting the position of the nut member, the holding force of the multilayer piezoelectric element can be easily adjusted to a desired value. Furthermore, by providing a rotation prevention pin for preventing the rotation of the nut member around the nut member, the stacked piezoelectric element can be held with a constant holding force.

Sectional drawing which shows one Embodiment of the laminated piezoelectric actuator which concerns on this invention Explanatory drawing (flowchart) which shows the manufacturing method of the piezoelectric actuator shown in FIG. A plan view of a green sheet used for manufacturing the piezoelectric actuator shown in FIG. Sectional drawing which shows schematic structure of the positioner using the piezoelectric actuator shown in FIG. Sectional drawing which shows another embodiment of the laminated piezoelectric actuator which concerns on this invention A plan view of a green sheet used for manufacturing the piezoelectric actuator shown in FIG. Schematic sectional view showing the schematic structure of a conventional multilayer piezoelectric actuator

Explanation of symbols

10; (Laminated type) piezoelectric actuator, 11; Laminated body, 12a and 12b; Piezoelectric ceramics, 13 and 13a and 13b; Internal electrodes, 13a 'and 13b'; Electrode paste, 14a and 14b; External electrodes, 15a and 15b; Through hole, 15a 'and 15b'; Hole, 16a and 16b; Lead wire, 17; Metal, 18a and 18b; Extraction electrode, 18a 'and 18b'; Electrode paste, Extraction electrode 19a and 19b; Glass coating, 20a 20b: Resin coating, 21: Piezoelectric active part, 22: Electrode extraction part, 23a, 23b, 23c; Protective layer, 24; Hole part, 30; (Laminated) piezoelectric actuator, 31; Laminated body, 32; 33a, 33b; protective layer, 34a, 34b; through-hole electrode, 35a, 35b; internal electrode, 35a ', 35b'; electrode paste, 36; Ceramics 37a, 37b; lead wire 39; glass coating 40; resin coating 44; hole 50; positioner 51; pedestal member 52; cylindrical member 53; disc spring 54; nut member 55 Cover member 61; struts 62a and 62b; lead wire outlet hole 63; screw hole 65; anti-rotation pin 66; bolt 67; moving object 71-75 81-85; green sheet; 82a, 82b, 83a, 83b, 84a, 84b, 85a, 85b; hole, 86a, 86b, 86c, 86d; electrode paste, 90; piezoelectric actuator (laminated type), 91; piezoelectric ceramic, 92; internal electrode, 93a 93b; external electrode, 94a, 94b; lead wire, 95; laminate, 96; resin coating

Claims (10)

A cylindrical laminated piezoelectric element in which a pair of lead members for sending drive signals are taken out from the lower end surface;
A pedestal member that has a column portion threaded at a tip and a hole portion that leads out the pair of lead members to the outside, and supports the multilayer piezoelectric element through the column portion in an inner hole of the multilayer piezoelectric element; ,
A cylindrical member that has an inner hole, the outer side surface of which is threaded, and is placed on the multilayer piezoelectric element so as to contact the upper end surface of the multilayer piezoelectric element through the support column in the inner hole;
A disc spring that has an inner hole and is held on the upper part of the cylindrical member through a support column in the inner hole;
A nut member that is fixed in contact with the disc spring at the tip of the column so that a predetermined holding force is applied to the multilayer piezoelectric element between the cylindrical member and the pedestal via the disc spring; ,
A cover member fitted to a threaded portion provided on the outer side surface of the tubular member and covering the multilayer piezoelectric element;
Comprising
The laminated piezoelectric element is extended and contracted by applying a predetermined drive signal to the pair of lead members, and the cover member is moved according to the displacement generated in the laminated piezoelectric element via the cylindrical member. A positioning device.   The positioning device according to claim 1, wherein an anti-rotation pin for preventing rotation of the nut member is provided around the nut member. The cylindrical laminated piezoelectric element is
Piezoelectric ceramics and internal electrodes are alternately laminated, and a piezoelectric active portion in which displacement is generated in the piezoelectric ceramics by applying an electric field to the piezoelectric ceramics by the internal electrodes, and a piezoelectric comprising a piezoelectric ceramic and a pair of positive and negative lead electrodes A cylindrical laminate having an inactive electrode extraction portion;
A pair of positive and negative external electrodes provided on the side surface of the laminate so that the internal electrodes are electrically connected every other layer and electrically connected to the positive electrode or the negative electrode of the extraction electrode;
A glass film covering the outer peripheral side surface and the inner peripheral side surface of the laminate so that the external electrode, the internal electrode and the extraction electrode are completely covered;
A pair of through holes formed in the electrode lead-out part so as to have an opening on the end face of the laminate,
The positive electrode and the negative electrode of the extraction electrode are separately exposed on the inner side surfaces of the pair of through holes,
The positioning device according to claim 1, wherein the pair of lead members are electrically connected to a positive electrode and a negative electrode of the extraction electrode exposed in the through hole, respectively.   The cylindrical laminated piezoelectric element is made of the same material as the piezoelectric ceramic of the piezoelectric active part and the electrode extraction part between the lowermost electrode of the piezoelectric active part and the extraction electrode, and the piezoelectric active The positioning device according to claim 3, further comprising a protective layer that is thicker than a thickness of the piezoelectric ceramic of the portion.   5. The positioning device according to claim 3, wherein the electrode take-out portion of the cylindrical laminated piezoelectric element has a structure in which the piezoelectric ceramics and the extraction electrodes are alternately laminated.   The through hole is filled with metal so as to connect the lead electrode and the lead member so that the lead electrode of the cylindrical laminated piezoelectric element does not directly contact the outside air. The positioning device according to claim 3 or 4.   7. The piezoelectric inactive protective layer is formed on a side of the cylindrical laminated piezoelectric element facing the electrode extraction portion with the piezoelectric active portion interposed therebetween. The positioning device according to claim 1. The cylindrical laminated piezoelectric element is
A lower protective layer made of piezoelectric ceramic, a piezoelectric active portion made by laminating first and second internal electrodes and piezoelectric ceramic, and an upper protective layer made of piezoelectric ceramic were laminated, and a hole was formed at the center. A tubular laminate,
A first through-hole electrode penetrating the lower protective layer and the piezoelectric active portion and electrically connected to the first internal electrode in the laminate;
A second through-hole electrode penetrating the lower protective layer and the piezoelectric active portion and electrically connected to the second internal electrode in the laminate;
A first lead wire that is electrically connected to the first through-hole electrode in the stacked body, and is taken out from an end face of the stacked body, and is electrically connected to the second through-hole electrode in the stacked body The positioning apparatus according to claim 1, further comprising: a pair of lead members including a second lead wire taken out from an end face of the laminate.   The positioning device according to claim 8, further comprising a glass coating that covers a side surface of the laminate.   The resin film is formed in the side surface of the said laminated body so that the glass film of the said cylindrical laminated type piezoelectric element may be coat | covered, The Claim 1 characterized by the above-mentioned. Positioning device.

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