JP2006186099A - Laminated piezoelectric element and oscillatory wave driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated piezoelectric element and an oscillatory wave driving device, wherein an oscillator is basically formed with a piezoelectric element, thereby enhancing performance of the oscillatory wave driving device, and also, miniaturization is easy and production costs can be reduced. <P>SOLUTION: The laminated piezoelectric element 1 is constituted as one body by laminating a piezoelectric active part 3 in which a material layer having a conversion function of converting an electric amount into a mechanical amount and an electrode material layer divided into a plurality of parts are overlapped by a plurality of layers, and a piezoelectric active part 4 in which the material layer having the conversion function is overlapped by at least one layer or the plurality of layers. On the surface of an end face 1-a of the piezoelectric active part 3 of the laminated pizoelectric element 1, a plurality of surface electrodes 7-2 are formed along a circumferential direction thereof. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laminated piezoelectric element and a vibration wave driving device in which a plurality of layers of materials having an electro-mechanical energy conversion function are laminated.

  Conventionally, piezoelectric materials, which are representative materials having an electro-mechanical energy conversion function for converting electrical energy into mechanical energy, are widely used as materials constituting various piezoelectric elements. In particular, recently, laminated piezoelectric elements obtained by laminating and sintering a large number of layers of piezoelectric elements have been used. This is because a large deformation strain and a large force can be obtained with a low applied voltage by stacking as compared with a piezoelectric element composed of only a single plate-like piezoelectric body.

  For example, various technologies have been proposed for a laminated piezoelectric element as a laminated electro-mechanical energy conversion element that constitutes a part of a vibrating body of a vibration wave motor as a vibration wave drive device, particularly a vibration wave motor formed in a rod shape. (For example, see Patent Document 1, Patent Document 2, and Patent Document 3). In addition to the vibration wave motor, many techniques related to the multilayer piezoelectric element have been proposed.

  The laminated piezoelectric element as described above is composed of a plurality of piezoelectric ceramic material layers (hereinafter referred to as piezoelectric layers) and electrode material layers (hereinafter referred to as internal electrodes) formed on the surface of each piezoelectric layer. And a plurality of piezoelectric layers and internal electrodes are laminated and laminated, and after sintering, a polarization treatment is performed so that the entire laminated piezoelectric element has piezoelectricity. That is, a laminated piezoelectric element in which a plurality of internal electrodes are arranged over the entire laminated piezoelectric element and the piezoelectric layer is a piezoelectric active portion having piezoelectricity is generally used.

  10 is an exploded perspective view and a perspective view showing a laminated piezoelectric element used in a vibrating body of a rod-shaped vibration wave motor disclosed in Patent Document 3. FIG.

  In FIG. 10, divided internal electrodes 43 are provided on the surface of a plurality of piezoelectric layers 42 excluding the uppermost piezoelectric layer constituting the laminated piezoelectric element 40. Connection electrodes 43a (parts painted in black in the drawing) connected to the electrodes 43 and extending to the outer edge of the piezoelectric layer 42 are formed. The internal electrode 43 is arranged so that the outer periphery is closer to the inner periphery than the outer periphery of the piezoelectric layer 42 and is divided into four parts (AG, AG, BG, BG, or A +, A−, B +, B−). The internal electrodes 43 are formed in a non-conductive state.

  The connection electrode 43 a is formed so as to have the same phase position in the axial direction of the multilayer piezoelectric element 40 with respect to the internal electrode 43 every other layer of the piezoelectric layer 42. The connection electrodes 43 a at the same phase position are connected by an external electrode 44 that is an electrode for providing conduction between layers provided on the outer peripheral portion of the multilayer piezoelectric element 40.

  A plurality of surface electrodes 45 are provided along the circumferential direction around the outer peripheral portion of the surface of the uppermost piezoelectric layer constituting the laminated piezoelectric element 40, and external electrodes provided in accordance with the phase position of the connection electrode 43a. 44. Then, a direct current voltage is applied to each internal electrode 43 through the surface electrode 45, and a polarization process is performed so as to obtain a polarization polarity capable of driving a vibration wave motor described later.

  Further, FIG. 11 is a cross-sectional view showing an example in which the laminated piezoelectric element 40 shown in FIG. 10 is incorporated in a vibrating body 51 of a rod-like vibration wave motor 50.

  In FIG. 11, the laminated piezoelectric element 40 having a through hole in the center portion is arranged between the hollow metal member 53 and the metal member 54 constituting the vibrating body 51 while the surface electrode 45 is in contact with the circuit board 52. Yes. By inserting the bolt 55 from the metal member 53 side and screwing it into the metal member 54, the laminated piezoelectric element 40 and the circuit board 52 are sandwiched and fixed between the metal member 53 and the metal member 54. The circuit board 52 is connected to a surface electrode 45 connected to the external electrode 44 of the multilayer piezoelectric element 40 and a drive circuit (not shown), and a driving high frequency voltage is applied to the multilayer piezoelectric element 40.

  On one side in the axial direction of the vibrating body 51, a rotor 58 that is in pressure contact with the tip of the metal member 54 is disposed via a spring 56 and a spring support 57, and a gear that rotates integrally with the rotor 58. 59, the rotational output of the vibration wave motor 50 can be taken out.

  The drive principle of the rod-shaped vibration wave motor 50 is that two bending vibrations perpendicular to the axial direction of the vibrating body 51 incorporating the laminated piezoelectric element 40 are generated with a temporal phase difference, and the vibrating body 51 is The metal member 54 moves like a swing using the tip portion of the metal member 54 as a drive unit, and the rotor 58, which is a contact member in pressure contact with the metal member 54, is rotated by frictional contact. .

  Conventionally, as a vibration wave motor for linear driving, one using a plate-like vibrating body has been proposed (see, for example, Patent Document 4 and Patent Document 5).

  12A and 12B are diagrams showing a configuration of a vibration wave motor that is linearly driven. FIG. 12A is a front view, FIG. 12B is a right side view, and FIG. 12C is a plan view.

  In FIG. 12, two piezoelectric elements 62 and 63 that simultaneously generate longitudinal vibration and bending vibration are disposed on one surface of a metal elastic body 61 that constitutes a part of the vibration body. Two protrusions 64 and 65 are formed on the other surface of the elastic body 61. The two piezoelectric elements 62 and 63 are bonded to the elastic body 61 with an adhesive.

  By applying the high frequency voltage A and the high frequency voltage B to the two piezoelectric elements 62 and 63, respectively, and synthesizing two composite vibrations, an elliptical or circular motion can be generated at the tips of the protrusions 64 and 65. it can. The two piezoelectric elements 62 and 63 are polarized so that their polarities are in the same direction, and the high-frequency voltage A and the high-frequency voltage B have a temporal phase difference of 90 degrees.

As a result, when the tips of the protrusions 64 and 65 are brought into pressure contact with the fixed portion 66, the elastic body 61 that constitutes a part of the vibrating body runs on the fixed portion 66. In other words, when the other member is brought into pressure contact with the vibration body, a relative movement is formed between the vibration body and the vibration wave motor capable of linear drive. However, in this example, the piezoelectric elements 62 and 63 are single plate-like elements and are not laminated piezoelectric elements.
Japanese Patent Laid-Open No. 6-77550 JP-A-6-120580 JP-A-8-213664 Japanese Patent No. 3279020 Japanese Patent No. 3279021

  In the future, the above-described vibration wave motor is required to have a higher output and a reduced manufacturing cost due to downsizing and higher efficiency.

  However, the laminated piezoelectric element 40 is sandwiched between metal members as in the rod-shaped vibration wave motor shown in FIG. 11 or the piezoelectric element is attached to a metal component as in the linear drive vibration wave motor shown in FIG. Even in the method of bonding, there are a plurality of parts and the shape of the parts is complicated. For this reason, the assembled vibrator is subject to processing errors of each component, and the error between the assembled dimensions and the designed dimensions increases. In addition, vibration attenuation occurs at the interface or bonding surface of each component of the assembled vibrator. As a result, the conventional vibration wave motor has a problem that the motor performance tends to be lower than expected at the time of design.

  Furthermore, since the number of parts having a complicated shape is large and it takes time to assemble these parts, it is an essential cause of the high manufacturing cost of the vibration wave motor.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer piezoelectric element and a vibration which can improve the performance of a vibration wave driving device by forming a vibrating body basically by a piezoelectric element, and can be easily reduced in size and reduced in manufacturing cost. It is in providing a wave drive device.

  In order to achieve the above-described object, the multilayer piezoelectric element of the present invention is a multilayer piezoelectric element composed of a plurality of layers, and is divided into a material layer having a conversion function for converting an electrical quantity into a mechanical quantity and a plurality of layers. A piezoelectric active portion in which a plurality of electrode material layers are stacked and a piezoelectric inactive portion in which a plurality of layers having the conversion function are stacked are stacked and integrated, and the material of the end face of the piezoelectric active portion is integrated. An electrode material layer is provided on the surface of the layer.

  In the multilayer piezoelectric element of the present invention, the thickness of the piezoelectric inactive portion is set to a thickness capable of generating a plurality of vibrations in the multilayer piezoelectric element.

  In the laminated piezoelectric element of the present invention, only the piezoelectric inactive portion has a concave portion or a convex portion for expanding the displacement of the vibration.

  The multilayered piezoelectric element of the present invention is characterized in that power is supplied through a circuit board connected to the electrode material layer.

  The laminated piezoelectric element of the present invention is characterized in that the laminated piezoelectric element has a cylindrical shape and is integrated by laminating the piezoelectric inactive part in the laminating direction of the piezoelectric active part.

  The multilayer piezoelectric element of the present invention is characterized in that the plurality of vibrations are at least two bending vibrations intersecting a lamination direction of the multilayer piezoelectric element.

  The laminated piezoelectric element of the present invention is characterized in that the laminated piezoelectric element has a flat plate shape, and the piezoelectric inactive part is laminated and integrated on one side in the lamination direction of the piezoelectric active part.

  Further, a part of the material layer of the end face of the piezoelectric active part is polarized by an electrode material layer provided on the surface thereof.

  The multilayer piezoelectric element of the present invention is characterized in that a convex portion is formed on a part of the piezoelectric inactive portion.

  In the multilayer piezoelectric element of the present invention, the plurality of vibrations are two bending vibrations.

  In order to achieve the above object, a vibration wave driving device of the present invention comprises the multilayered piezoelectric element according to any one of claims 1 to 6, wherein the multilayered piezoelectric element is used as a vibrating body, and is added to the vibrating body. The contact body in pressure contact is rotated.

  According to another aspect of the present invention, there is provided a vibration wave driving device including the multilayered piezoelectric element according to any one of the first, second, and seventh to tenth aspects, wherein the multilayered piezoelectric element is a vibrating body. It is characterized by relatively moving the contact body in pressure contact.

  Furthermore, the multilayer piezoelectric element of the present invention may be configured such that a concave portion is formed by grinding an outer peripheral portion of the piezoelectric inactive portion constituting the cylindrical multilayer piezoelectric element along a circumferential direction.

  Furthermore, the multilayered piezoelectric element of the present invention has a plurality of convex portions by grinding a surface of the piezoelectric inactive part constituting the flat plate-shaped multilayered piezoelectric element opposite to the layered surface with the piezoelectric active part. It is good also as a structure to form.

  Furthermore, the vibration wave driving device of the present invention may be configured such that a member made of a material having wear resistance is disposed between the vibrating body and the contact body.

  In order to achieve the above-mentioned object, the vibration type driving device of the present invention is a vibration wave driving device that generates vibration in a vibrating body and rotates a contact body that is in pressure contact with the vibrating body. Includes a piezoelectric active portion in which a plurality of layers of a material having a conversion function for converting an electrical quantity into a mechanical quantity and a plurality of electrode material layers divided into a plurality of layers, and at least one or a plurality of layers of the material having the conversion function. It is composed of laminated piezoelectric elements that are laminated and integrated with a layered piezoelectric inactive part, and an electrode material layer is provided on the surface of the end face of the laminated piezoelectric element, and the contact body is added to the piezoelectric inactive part. It is characterized by pressure contact.

  According to the present invention, since the piezoelectric active part and the piezoelectric inactive part are laminated and integrated, it is possible to form a vibrating body with the laminated piezoelectric element itself and generate a plurality of vibration modes.

  As a result, the number of metal members for sandwiching and fixing the conventional laminated piezoelectric element can be reduced, and it is not necessary to bond a complicated-shaped metal member to the piezoelectric element with an adhesive.

  As a result, the performance of the vibration wave driving device can be improved, the number of parts is small, and the assembly is simple, and the manufacturing cost of the vibration wave driving device can be reduced. That is, not only the performance of the vibration wave driving device can be improved, but also the manufacturing process of the vibration wave driving device can be shortened, and the number of parts and the manufacturing cost can be reduced. In addition, the vibration wave driving device can be reduced in size.

  In addition, since the electrode material layer is provided on the surface of the material layer at the end face of the piezoelectric active portion of the multilayer piezoelectric element, conduction to the circuit board for supplying power to the multilayer piezoelectric element through the electrode material layer is provided. As a result, a plurality of vibrations can be efficiently generated by the laminated piezoelectric element itself.

  In addition, the piezoelectric material has better machinability than metal and can be easily micro-processed. Therefore, high-precision vibration can be achieved even in small dimensions by machining convex portions and concave portions in part of the piezoelectric inactive portion. The body can be formed.

  In addition, since a part of the material layer of the end surface of the piezoelectric active portion of the multilayer piezoelectric element is polarized by the electrode material layer provided on the surface, bending vibration is generated at a low voltage and a large amplitude in the multilayer piezoelectric element. Can be generated efficiently.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a diagram showing a configuration of a laminated piezoelectric element that is a laminated electro-mechanical energy conversion element according to a first embodiment of the present invention, in which the right half from the axis L is a sectional view and the left half from the axis L is It is an external view. FIG. 2 is a perspective view showing an intermediate stage of manufacturing the laminated piezoelectric element and showing the laminated structure. In the following description, the laminated piezoelectric element in the middle of manufacturing and the laminated piezoelectric element after manufacturing are given the same reference for convenience.

  1 and 2, the laminated piezoelectric element 1 has a cylindrical shape with a through hole formed in the center, and converts electrical energy (electric quantity) into mechanical energy (mechanical quantity). A piezoelectric active portion 3 having piezoelectricity in which a plurality of layers of a material having an electro-mechanical energy conversion function and a plurality of divided electrode material layers are stacked, and disposed in the axial direction of the piezoelectric active portion 3. -It is comprised from the piezoelectric inactive part 4 which does not have the piezoelectricity which piled up only the layer of the material which has a mechanical energy conversion function several layers.

  The piezoelectric active part 3 is composed of a plurality of piezoelectric layers 5. On the surface of the plurality of piezoelectric layers 5, there are internal electrodes 6-1 divided into four (A +, A−, B +, B−) and internal electrodes 6-2 divided into four (AG, AG, BG, BG). Connection electrodes 6a (portions painted in black in the drawing) that are formed respectively and extend to the outer edge of the piezoelectric layer 5 by being connected to the internal electrodes 6-1 and 6-2 are formed. The connection electrode 6a in each internal electrode 6-1 is formed at the same phase position in the axial direction of the multilayer piezoelectric element 1, and the connection electrode 6a in each internal electrode 6-2 is identical in the axial direction of the multilayer piezoelectric element 1, respectively. It is formed at the phase position.

  Further, the connection electrodes 6 a located at the same phase position in the axial direction of the multilayer piezoelectric element 1 are connected by an external electrode 7-1 that is provided on the outer peripheral portion of the multilayer piezoelectric element 1 and that conducts between layers. For example, eight external electrodes 7-1 are formed in a state along the circumferential direction of the laminated piezoelectric element 1 for each connection electrode 6a positioned in the same phase position in the axial direction of the laminated piezoelectric element 1.

  Each internal electrode 6-1 of the piezoelectric active part 3 is composed of internal electrodes A +, A−, B +, B− divided into four, as in the conventional example. 2 is composed of internal electrodes AG, AG, BG, and BG divided into four. The internal electrodes A +, A−, B +, B− and the internal electrodes AG, AG, BG, BG are opposed to each other in the axial direction of the multilayer piezoelectric element 1. And the piezoelectric active part 3 laminates | stacks alternately the piezoelectric layer 5 in which the internal electrodes 6-2 and 6-1 were formed from the 1st layer to the last layer.

  On the other hand, the piezoelectric inactive part 4 is composed of at least one or more integrated piezoelectric layers 5 without internal electrodes. The thickness of the piezoelectric inactive portion 4 is set to a thickness capable of generating two bending vibrations orthogonal to the axial direction of the multilayer piezoelectric element 1. In this case, if the piezoelectric inactive portion 4 is thin, bending vibration cannot be generated.

  Further, a plurality of surface electrodes 7-2 are formed along the circumferential direction on the surface of the end face 1-a of the multilayer piezoelectric element 1, and are electrically connected to the external electrodes 7-1.

  Here, the laminated piezoelectric element 1 of the present embodiment has, for example, an outer diameter of about 10 mm, an inner diameter of about 2.8 mm, and a length of about 8 mm, and the thickness of the piezoelectric layer 5 of the piezoelectric active portion 3 is about The thickness of 90 μm, the internal electrodes 6-1 and 6-2 was about 2 to 3 μm, and the number of internal electrodes was 25. The length of the external electrode 7-1 was about 2 mm, the width was about 1 mm, the thickness was about 0.05 mm, and the thickness of the piezoelectric layer 5 of the piezoelectric inactive portion 4 was also about 90 μm. However, the number of layers of the piezoelectric inactive portion 4 may be reduced by stacking thicker layers. In the present embodiment, if the thickness is such that two bending vibrations perpendicular to the axial direction of the laminated piezoelectric element 1 can be generated, a layer having a thick final layer of the end face 1-a is used. Alternatively, a plurality of layers may be stacked.

  The laminated piezoelectric element 1 is made of a piezoelectric ceramic powder to be the piezoelectric layer 5 and an organic binder, and is manufactured by the following manufacturing method by using a green sheet cut into a shape of a certain size (for example, a square of about 13 mm in length and width). The

  First, as shown in FIG. 2, the piezoelectric inactive portion 4 constituting the laminated piezoelectric element 1 is formed by stacking a predetermined number of green sheets, and the piezoelectric active portion 3 constituting the laminated piezoelectric element 1 is constituted by the internal electrode 6-1. 6-2 pattern is formed by screen printing on a green sheet using silver / palladium powder paste, and a predetermined number of the screen-printed green sheets are sequentially stacked, and these are laminated by pressing them while heating. Turn into.

  Next, as shown in FIG. 2, the laminated piezoelectric element 1 having the laminated structure is drilled to form a through hole at a position corresponding to the inner diameter of the laminated piezoelectric element 1, and then a predetermined temperature (for example, 1100 to 1200). Firing in a lead atmosphere of degree C). After firing, lapping is performed on both sides, and both end surfaces of the laminated piezoelectric element 1 are smoothed.

  Next, as shown in FIGS. 1 and 2, the outer diameter of the multilayer piezoelectric element 1 is ground into a cylindrical shape by grinding, and the connection electrode 6 a is exposed on the outer peripheral portion of the multilayer piezoelectric element 1. Thereafter, using a screen printing machine for cylindrical surface printing, the external electrodes 7-1 are printed and dried at eight locations where the connection electrodes 6a on the outer peripheral portion of the multilayer piezoelectric element 1 are exposed. Further, the surface electrode 7-2 is printed at a position where it is electrically connected to the external electrode 7-1 and dried. After printing, heating is performed at a predetermined temperature (for example, about 750 ° C.), and the external electrode 7-1 and the surface electrode 7-2 on the outer peripheral portion of the multilayer piezoelectric element 1 are baked.

  Next, as shown in FIG. 1, an annular recess 8 (recess) is formed on the outer periphery of the piezoelectric inactive portion 4 by cutting along the outer periphery by mechanical (grinding) processing. By projecting the piezoelectric inactive portion 4 on the side of one end face 1-b in the axial direction of the laminated piezoelectric element 1 so as to partially enlarge the inner diameter, the convex portion 9 is formed.

  Here, the recess 8 is formed for the purpose of enlarging the vibration displacement. Since the portion where the recessed portion 8 is formed becomes a rigidly weak portion, the portion above the recessed portion 8 is likely to vibrate. Further, the convex portion 9 is formed for positioning when a member (for example, a metal or a ceramic having good wear resistance) is disposed on the end face of the laminated piezoelectric element 1 that is in pressure contact with the rotor 18 (see FIG. 3). The In this embodiment, the concave portion 8 is formed for the purpose of enlarging the vibration displacement of the vibrator. However, the convex portion is formed by increasing the mass of the end portion by forming the convex portion at the end portion of the vibrator. You may comprise so that the formed part may become easy to vibrate.

  Finally, as shown in FIG. 2, a specific polarization is applied to each of the four divided electrodes (A +, A−, B +, B−, AG, AG, BG, BG) in the internal electrodes 6-1 and 6-2. Polarize in the direction. Specifically, metal contact pins are pressed against the eight external electrodes 7-1, AG and BG are grounded (G) in oil at a predetermined temperature (for example, 100 to 150 degrees C), and the internal electrodes A +, A predetermined voltage (for example, 300 V) is applied with B + as plus (+) and internal electrodes A− and B− as minus (−), respectively, and polarization is performed for about 10 to 30 minutes.

  As a result, as shown in FIG. 2, the laminated piezoelectric element 1 has the internal electrodes A +, B + having a (+) polarity with respect to the internal electrodes AG, BG, AG, BG corresponding to the electrical ground. A- and B- are polarized differently to the polarity of (-).

  FIG. 3 is a cross-sectional view showing a configuration of a rod-shaped vibration wave motor 11 incorporating the laminated piezoelectric element 1.

  In FIG. 3, the vibration wave motor 11 (vibration wave driving device) uses the laminated piezoelectric element 1 as the vibration body 10. In the vibrating body 10, a bolt 12 is inserted into the inner diameter portion of the multilayer piezoelectric element 1, and the multilayer piezoelectric element 1 is sandwiched and fixed by a flange portion 13 of the bolt 12, a nut 14-1, and a metal ring-shaped component 14-2. It is composed of that. On the upper side of the flange portion 13 of the bolt 12, a rotor portion that is an upper structure of the vibration wave motor 11 is disposed. The rotor portion includes a rotor 18 (contact body) in pressure contact with the end face of the vibrating body 10 via a spring 16 and a spring support body 17, and a gear 19. The rotor 18 is configured integrally with the gear 19, and the rotation of the rotor 18 can be taken out from the gear 19.

  On the other hand, a circuit board 15 is connected to the surface electrode 7-2 (see FIG. 2) formed on the end face 1-a of the multilayer piezoelectric element 1 as the vibrating body 10, and the circuit board 15 and the surface electrode 7-2 are connected to the surface electrode 7-2. A drive circuit (not shown) is electrically connected. The surface electrode 7-2 formed on the end surface 1-a facilitates electrical connection with the circuit board 15, and as described above, the flange portion 13 of the bolt 12, the nut 14-1, and the metal ring-shaped component 14-2. By sandwiching and fixing the laminated piezoelectric element 1, the reliability can be improved. The circuit board 15 may have either a flexible board structure or a plate-like hard circuit board structure.

  The actual drive of the vibration wave motor 11 has the above-described polarity in the laminated piezoelectric element 1 as the vibrating body 10 and the positional relationship (AG and AG, BG and BG, A +) facing each other in the radial direction of the laminated piezoelectric element 1. In the two internal electrodes at A−, B + and B−), the AG phase and the BG phase are ground, A + and A− are the A phase, B + and B− are the B phase, and the vibration body 10 is in the A phase. A high frequency voltage substantially matching the natural frequency is applied, and a high frequency voltage whose phase is 90 degrees different from the A phase is applied to the B phase.

  By applying the high-frequency voltage, A + and A− of the piezoelectric active portion 3 constituting the laminated piezoelectric element 1 are alternately expanded and contracted in the thickness direction. Similarly, B + and B− of the piezoelectric active portion 3 are also expanded and contracted in the thickness direction. To do. The expansion / contraction operation of the piezoelectric active portion 3 is changed to bending vibration by the piezoelectric inactive portion 4 laminated and integrated on both sides in the axial direction of the piezoelectric active portion 3, thereby orthogonal to the laminated piezoelectric element 1 in the axial direction. Two bending vibrations can be generated.

  Here, the multilayer piezoelectric element 40 of the conventional example (see FIG. 10) can only expand and contract in the thickness direction, but the vibrating body 51 is configured by sandwiching and fixing the multilayer piezoelectric element 40 between the metal member 53 and the metal member 54. Thus, two bending vibrations were generated (note that the laminated piezoelectric element 40 has a piezoelectric inactive layer in which the uppermost layer and the lowermost layer are not polarized for insulation. Since this layer is thin, only one vibration (stretching) can be performed in the thickness direction).

  On the other hand, in the laminated piezoelectric element 1 of the present embodiment, the piezoelectric inactive portion 4 is laminated and integrated with the piezoelectric active portion 3 instead of sandwiching and fixing the laminated piezoelectric element with the metal member 54 as in the conventional example. Therefore, the two bending vibrations for driving the rod-shaped vibration wave motor 11 can be generated. The two bending vibrations can cause a swinging motion using the end face 1-b of the multilayer piezoelectric element 1 as the vibrating body 10 as a drive unit, and the rotor 18 that is in pressure contact with the drive unit rotates due to friction. .

  In the present embodiment, a metal or ceramic small component with good wear resistance is disposed on the end surface 1-b in pressure contact with the rotor 18 in the laminated piezoelectric element 1 as the vibrating body 10. It is also possible to improve durability.

  Further, in the present embodiment, the case where the shape of the recess portion 8 for expanding vibration displacement formed on the outer peripheral portion of the piezoelectric inactive portion 4 of the multilayer piezoelectric element 1 is an annular shape is described as an example. The shape can be any shape as long as vibration displacement can be expanded.

  In this embodiment, the external electrodes are electrically connected to each other by the external electrodes. However, surface electrodes that are electrically connected by through holes may be used as in the second embodiment to be described later.

  As described above, according to the present embodiment, the laminated piezoelectric element 1 includes the piezoelectric active portion 3 having piezoelectricity in which a plurality of layers of a material having an electro-mechanical energy conversion function and a layer of an electrode material are stacked. And a piezoelectric inactive portion 4 having no piezoelectricity, in which only a plurality of layers having a material having an electro-mechanical energy conversion function are stacked, and the thickness of the piezoelectric inactive portion 4 is set to the axis of the laminated piezoelectric element 1. Since the thickness is set such that two bending vibrations orthogonal to the direction can be generated, a plurality of vibration modes (two bending vibration modes) can be provided.

  Further, since the surface electrode 7-2 is formed on the end surface 1-a of the piezoelectric active portion 3 of the multilayer piezoelectric element 1, the surface electrode 7-2 facilitates electrical connection with the circuit board 15 and a plurality of vibrations. Can be efficiently caused by the laminated piezoelectric element itself.

  Moreover, as a result of reducing the cause of vibration attenuation at the interface between the metal members that has deteriorated the performance of the vibration wave motor, the performance of the vibration wave motor can be improved.

  In addition, the vibration wave motor can be easily downsized, and not only the performance of the vibration wave motor can be improved, but also the manufacturing process of the vibration wave motor can be shortened, and the number of parts and the cost can be reduced.

  Further, since the recess 8 is disposed by machining the outer peripheral portion of the piezoelectric inactive portion 4 constituting the laminated piezoelectric element 1, the design specification such as expansion of vibration displacement is appropriately handled and changed. In addition, the piezoelectric material has better processability than a metal and can be easily finely processed. Further, the conduction between the surface electrode on the end face of the laminated piezoelectric element 1 and the substrate is sandwiched and fixed, so that it can be reliably performed.

  As described above, for vibration wave motors that intend to realize new miniaturization and higher output in the future, the effects in terms of performance and manufacturing are great.

[Second Embodiment]
FIG. 4 is a perspective view showing the configuration of the laminated piezoelectric element according to the second embodiment of the present invention. FIG. 5 is a perspective view showing the laminated structure while showing the stage in the middle of manufacturing the laminated piezoelectric element. In the following description, the laminated piezoelectric element in the middle of manufacturing and the laminated piezoelectric element after manufacturing are given the same reference for convenience.

  In FIG. 5, the laminated piezoelectric element 2 has a flat plate shape before grinding, which will be described later, and includes a piezoelectric active portion 26 and a piezoelectric inactive portion 27-2. In the piezoelectric inactive portion 27-2, the uppermost first to seventh layers are constituted by the piezoelectric layer 22 having no internal electrode. The piezoelectric active portion 26 includes a piezoelectric layer 22 in which internal electrodes 23-1 and 23-2 divided into two layers from the eighth layer to the final layer (the eleventh layer, which is the lowest layer), and an internal electrode on the entire surface. The piezoelectric layer 22 formed with 23-3 is alternately overlapped and laminated.

  In FIG. 5, the piezoelectric active part 26 and the piezoelectric inactive part 27-2 are stacked and integrated at the same time and fired, for example.

  In each piezoelectric layer 22, the internal electrodes 23-1 and 23-2 that are divided into two and the internal electrodes 23-3 on the entire surface are respectively independently via through holes 24-1, 24-2, and 24-3. It is electrically connected and is electrically connected to the three divided surface electrodes 25-1, 25-2, and 25-3 disposed on the back surface of the lowermost piezoelectric layer. Then, a polarization process described later is performed, and each piezoelectric layer 22 is given a predetermined polarization polarity.

  As shown in FIG. 4, two projecting portions 21 (convex portions) are formed on the upper surface of the piezoelectric inactive portion 27-1 by grinding the piezoelectric inactive portion 27-2 in FIG. 5 by grinding. ing. The thickness of the piezoelectric inactive part 27-1 after processing is set to a thickness capable of generating bending vibration in the laminated piezoelectric element 2. In this case, if the thickness of the piezoelectric inactive portion 27-1 is small, bending vibration cannot be generated. That is, finally, the vibrating body 20 is configured by the laminated piezoelectric element 2 including the piezoelectric active portion 26, the piezoelectric inactive portion 27-1, and the two protruding portions 21.

  Here, the two protrusions 21 are formed for the purpose of enlarging the vibration displacement. However, the two protrusions 21 do not necessarily have the same width and the square shape as the laminated piezoelectric element 2. These are determined from the influence on the vibration of the vibrating body and the ease of processing.

  FIG. 6A is a cross-sectional view in the longitudinal direction of the multilayer piezoelectric element 2 shown in FIG. 5, where the multilayer piezoelectric element has a surface electrode.

  In FIG. 6A, the laminated piezoelectric element 2 is laminated in the order of the uppermost first layer (1), the second layer (2),... The electrodes 23-1, 23-2, 23-3, the surface electrodes 25-1, 25-2, 25-3 of the lowermost eleventh layer (11) serving as end faces, and the through holes 24-1, 24 -2 and 24-3. Internal electrode 23-1 and internal electrode 23-3, internal electrode 23-2 and internal electrode 23-3, internal electrode 23-3 and surface electrode 25-1, internal electrode 23-3 and surface electrode 25-2 indicated by hatching. The region from the eighth layer (8) to the eleventh layer (11) sandwiched between the layers is polarized and piezoelectrically activated.

  Here, the surface electrodes 25-1 and 25-2 have substantially the same outer dimensions as the internal electrodes 23-1 and 23-2. That is, the piezoelectric layer on which the surface electrodes 25-1 and 25-2 are formed, that is, the lowermost eleventh layer (11) (final layer) on the end face of the laminated piezoelectric element 2 is also polarized and piezoelectrically activated. Yes.

  In this way, the eleventh layer (11), which is the lowermost layer of the multilayer piezoelectric element 2, is polarized and subjected to piezoelectric activation, so that the layers that can be expanded and contracted are the eighth layer (8) to the eleventh layer (11) indicated by hatching. In the plate-like multilayered piezoelectric element 2, bending vibration can be efficiently generated with a low voltage and a large amplitude.

  FIG. 6B is a longitudinal sectional view of the multilayer piezoelectric element 2 shown in FIG. 5 and shows a case where the multilayer piezoelectric element has no surface electrode.

  In FIG. 6B, the polarization activation region of the piezoelectric active portion 26 ′ is only the three layers from the eighth layer (8) to the tenth layer (10) indicated by oblique lines. Since the final layer (11 ′) is not polarization-activated, it cannot expand and contract, and conversely, the final layer (11 ′) expands and contracts from the eighth layer (8) to the tenth layer (10). It is the result that will be restrained. Conventionally, since the surface electrode has a small area and is used only for polarization treatment, and then scraped off by double-sided lapping, the final layer is not used as an active region.

  Moreover, in this Embodiment, as shown in FIG.4 and FIG.5, using this surface electrode, it is a circuit in the predetermined position of each edge part of the surface electrode layers 25-1, 25-2, and 25-3. By attaching the substrate 28 and conducting the connection, connection with a drive circuit (not shown) can be easily performed. The circuit board 28 may have either a flexible board structure or a plate-like hard circuit board structure.

  As in the conventional example, a high-frequency voltage having a temporal phase difference of 90 degrees, for example, is applied to the internal electrodes 23-1, 23-2, 23-3 of the multilayer piezoelectric element 2 to simultaneously generate two bending vibrations. . By synthesizing a composite vibration composed of two bending vibrations, an elliptical motion or a circular motion is caused at the tips of the two protrusions 21 on the piezoelectric inactive portion 27-1 of the laminated piezoelectric element 2 constituting the vibrating body 20. Can be generated.

  As a result, when the tip of the protrusion 21 of the vibrating body 20 is brought into pressure contact with a fixed portion (not shown), the vibrating body 20 self-runs with respect to the fixed portion due to elliptical motion or circular motion generated at the tip. Accordingly, when another member (contact body) is brought into pressure contact with the vibration body 20, a relative movement is formed between the vibration body 20 and the vibration wave motor configured to drive linearly (linear). can do.

  In the present embodiment, the end surfaces of the two projecting portions 21 on the piezoelectric inactive portion 27-1 of the multilayer piezoelectric element 2 as the vibrating body 20 that are in pressure contact with other members are extremely thin. Durability can be improved by disposing metal or ceramics having good wear characteristics.

  Here, in the laminated piezoelectric element 2 of the present embodiment, for example, the length is 20 mm, the width is 5 mm, the thickness is about 0.44 mm, the thickness of the piezoelectric layer 22 is 40 μm, and the thickness of the internal electrode is 1. And the diameter of the through hole is 0.1 mm. Moreover, the piezoelectric layer 22 of the piezoelectric inactive part 27-2 may use a thicker sheet to reduce the number of layers.

  The manufacturing method of the laminated piezoelectric element 2 is basically the same as that of the first embodiment, and the following steps are performed.

  First, a green sheet without an internal electrode and a green sheet with an internal electrode are laminated and integrated, and then fired in a lead atmosphere at a predetermined temperature (for example, 1100 to 1200 ° C.).

  Next, as shown in FIG. 5, a metal contact pin is pressed against each of the surface electrodes 25-1, 25-2, and 25-3 connected to the three through holes, and the surface electrode 25 electrically connected to the internal electrode 23-3. -3 is a ground (G), and surface electrodes 25-1 and 25-2 respectively conducted to the internal electrodes 23-1 and 23-2 are plus (+), and oil at a predetermined temperature (for example, 100 to 150 degrees C) In particular, a predetermined voltage (for example, 200 V) is applied, and the polarization process is performed for about 10 to 30 minutes.

  Finally, after the above-described polarization treatment, one surface of the multilayer piezoelectric element 2 is smoothed by lapping only one surface of the multilayer piezoelectric element 2 on the piezoelectric inactive portion 27-2 side, and the multilayer piezoelectric element 2 shown in FIG. The piezoelectric active portion 27-2 is ground, and the protrusions 21 which are two convex portions are cut out on the piezoelectric inactive portion 27-1, as shown in FIG.

  In the present embodiment, the case where the shape of the protrusion 21 for expanding vibration displacement formed on the piezoelectric inactive portion 27-1 of the multilayer piezoelectric element 1 is a rectangular parallelepiped and the number of arrangements is two is taken as an example. As mentioned above, the shape and number of the protrusions 21 can be any shape and number as long as the vibration displacement can be expanded.

  Further, in the present embodiment, the conduction between the internal electrodes is taken by the through-hole, but a surface electrode that is conducted by the external electrode as in the first embodiment may be used.

  As described above, according to the present embodiment, conventionally, two bending vibrations are caused by bonding of an elastic body, which is a metal member, and a piezoelectric element. Since the inactive portion 27-2 is laminated and integrated, and the protruding portion 21 for pressure contact with other members is formed by cutting out from the piezoelectric inactive portion 27-2, the laminated piezoelectric element 2 It can be used as the vibration body 20 of the vibration wave motor alone, and two bending vibrations can be generated simultaneously.

  In addition, the surface electrodes 25-1 and 25-2 are formed on the lowermost eleventh layer (11) of the laminated piezoelectric element 2, and the layer that can be expanded and contracted by polarization treatment and piezoelectric activation is the eighth layer (8). To the eleventh layer (11), and the plate-like multilayer piezoelectric element 2 can efficiently generate bending vibration with a low voltage and large amplitude.

  Further, by disposing the surface electrodes 25-1 and 25-2 on the lowermost eleventh layer (11) of the laminated piezoelectric element 2, it is possible to polarize the lowermost piezoelectric layer and between the internal electrodes. As a conductive portion that contacts a metal contact pin for polarization processing, it can further serve as a terminal for connection with a circuit board for power supply when the motor is driven.

  In addition, since it is not necessary to bond the piezoelectric element and the thick metal member as in the conventional case, the cause of vibration attenuation that has deteriorated the performance of the vibration wave motor can be removed. Therefore, the performance of the vibration wave motor can be improved.

  Further, since it is not necessary to use a metal member, it is easy to reduce the size of the vibration wave motor, and not only the performance of the vibration wave motor can be improved, but also the manufacturing process of the vibration wave motor can be shortened. In addition, the number of parts and the cost can be reduced.

  Further, since the projecting portion 21 is formed by grinding the piezoelectric inactive portion 27-2 constituting the laminated piezoelectric element 2, it is possible to accurately respond to or change the design specifications such as expansion of vibration displacement. In addition, the piezoelectric material has better workability than metal and can be easily processed finely.

[Third Embodiment]
FIG. 7 is a perspective view showing a configuration of a vibration wave motor using the laminated piezoelectric element according to the third embodiment of the present invention.

  In FIG. 7, a vibration wave motor 31 is a linear vibration wave motor using the flat plate-shaped multilayered piezoelectric element 2 shown in FIG. 5 of the second embodiment described above. The vibration wave motor 31 includes a vibrating body 32 and a slider 33 that is held in a pressure contact state at a contact portion of the vibrating body 32. In addition to the vibrating body 32 and the slider 33, the ultrasonic motor 31 includes a circuit board that electrically connects the vibrating body 32 and the outside, a support member that supports the vibrating body 32, a guide member for the slider 33, and a vibrating body. And a pressurizing mechanism for applying a pressure between the slider 32 and the slider 33.

  The vibrating body 32 includes a friction plate 32-1 and a laminated piezoelectric element 32-2. The vibrating body 32 transmits a feeding force in the X direction shown in FIG. The slider 33 is formed by joining a rectangular bar-shaped slider base 33-1 and a plate-shaped friction material 32-2. The slider 33 performs relative movement in the X direction with respect to the vibrating body 32 by the feed force transmitted from the vibrating body 32.

  On the other hand, the friction plate 32-1 of the vibrating body 32 is formed of a material having both a high friction coefficient and friction durability. In this embodiment, the surface of SUS420J2 can be nitrided to obtain desired characteristics. It was. A frictional force can be obtained by bringing the vibrating body 32 and the slider 33 into pressure contact with a pressurizing mechanism or the like that applies pressure.

  FIG. 8 is a perspective view showing the configuration of the vibrating body 32 made of a laminated piezoelectric element.

  In FIG. 8, a vibrating body 32 is obtained by attaching a very thin rectangular flat friction plate 32-1 to the laminated piezoelectric element 32-2 corresponding to the laminated piezoelectric element 2 shown in FIG. It is configured. The shape and position of the friction plate 32-1 and the laminated piezoelectric element 32-2 are defined so that the edges in the X direction and the Y direction substantially coincide. The long side of the vibrating body is 20 mm, the short side is 5 mm, and the thickness is 0.6 mm. The friction plate 32-1 is processed from a plate material of SUS420J2, and has a maximum thickness of 0.16 mm.

  The thick portion of the friction plate 32-1 constitutes two contact portions 32-1-a and two edge portions 32-1-b. The contact portion 32-1-a and the edge portion 32-1-b have the same thickness of 0.16 mm and the surfaces are continuous. Other portions of the friction plate 32-1 are processed so that the plate thickness is further reduced from the surface side. The thin plate portion 32-1-c near the center of the friction plate and the two thin plate portions 32-1 near the single portion. -D.

  These thin plate portions 32-1 -c and 32-1 -d are formed by removing the material from the surface side of the plate-shaped material by an etching process. The thickness of the thin plate portions 32-1-c and 32-1-d is 0.05 mm. Since the thin plate portions 32-1-c and 32-1-d are configured to be recessed from the contact portion 32-1-a, the thin plate portions 32-1-c and 32-1-d are the sliders 33. A desired feeding force can be transmitted to the slider 33 by contacting only the contact portion 32-1-a with the slider 33 without interfering with the slider 33.

  The laminated piezoelectric element 32-2 is the same as the laminated piezoelectric element 2 shown in FIG. 5, and includes a piezoelectric active part and a piezoelectric inactive part. The vibrating body 32 has first and second vibration modes. The phases are excited with a phase shift of approximately 90 degrees.

  FIG. 9 is a perspective view showing two vibration modes excited by a vibrating body 32 made of a laminated piezoelectric element. FIG. 9A shows a first vibration mode, and FIG. 9B shows a second vibration mode. FIG.

  In FIG. 9, these two vibration modes are out-of-plane bending modes of the plate-like vibrating body 32. The first vibration mode shown in FIG. 9 (a) is an out-of-plane primary bending mode in which a node is generated in the X direction in the figure, and the second vibration mode shown in FIG. 9 (b) is in the Y direction in the figure. This is an out-of-plane secondary bending mode in which nodes are formed. In these two vibration modes, the shape of the vibrating body is designed so that the resonance frequencies substantially coincide.

  When the first vibration mode is excited, the two contact portions 32-1-a repeatedly move up and down in the Z direction. When the second vibration mode is excited, the two contact portions 32-1-a repeatedly move up and down in the X direction. When excitation of each vibration mode is performed such that the temporal phases of the first vibration mode and the second vibration mode are shifted by 90 degrees, for example, the contact portion 32-1-a generates a substantially elliptical motion in the XZ plane. . By this substantially elliptical motion, the slider 33 that is in pressure contact with the contact portion 32-1-a can receive a feeding force in the X direction and perform a relative movement motion with the vibrating body 32.

  As described above, according to the present embodiment, the vibrating body 32 is mainly composed of the laminated piezoelectric element 32-2, and the friction plate 32-1 that is a metal having thin wear resistance is attached to the surface thereof. Since the configuration is adopted, basically, the first vibration mode and the second vibration mode can be excited only by the laminated piezoelectric element 32-2.

It is the external view and sectional drawing which show the structure of the laminated piezoelectric element which concerns on the 1st Embodiment of this invention. It is a perspective view which shows the middle stage of manufacture of a laminated piezoelectric element, and shows the laminated structure. It is sectional drawing which shows the structure of the rod-shaped vibration wave motor incorporating the laminated piezoelectric element. It is a perspective view which shows the structure of the laminated piezoelectric element which concerns on the 2nd Embodiment of this invention. It is a perspective view which shows the stage in the middle of manufacture of a laminated piezoelectric element, and shows the laminated structure. It is sectional drawing of the longitudinal direction of a laminated piezoelectric element, (a) is a case where there is a surface electrode, (b) is a case where there is no surface electrode. It is a perspective view which shows the structure of the vibration wave motor using the laminated piezoelectric element which concerns on the 3rd Embodiment of this invention. It is a perspective view which shows the structure of the vibrating body which consists of a laminated piezoelectric element. It is a perspective view which shows two vibration modes excited by the vibrating body which consists of laminated piezoelectric elements, (a) is a figure which shows 1st vibration mode, (b) is a figure which shows 2nd vibration mode. It is a perspective view which shows the laminated piezoelectric element which concerns on a prior art example. It is sectional drawing which shows the structure of the rod-shaped vibration wave motor incorporating the laminated piezoelectric element. It is a figure which shows the structure of the vibration wave motor which carries out the linear drive which has arrange | positioned the laminated piezoelectric element, (a) is a front view, (b) is a right view, (c) is a top view.

Explanation of symbols

1, 2, 32-2 Multilayer piezoelectric element 1-a End face 3, 26 Piezoelectric active part 4, 27-1, 27-2 Piezoelectric inactive part 5, 22 Piezoelectric layer 6-1, 6-2, 23-1, 23-2, 23-3 Internal electrode 7-1 External electrode 7-2, 25-1, 25-2, 25-3 Surface electrode 8 Depression 9 Protrusion 10, 20, 32 Vibrating body 11, 31 Vibration wave motor 15 Circuit board 18 Rotor 21 Protrusion 24-1, 24-2, 24-3 Through hole 33 Slider

Claims (13)

In a laminated piezoelectric element composed of a plurality of layers,
A piezoelectric active part in which a plurality of layers of a material having a conversion function for converting an electric quantity into a mechanical quantity and a plurality of electrode material layers divided into at least one layer or a plurality of layers of the material having a conversion function are stacked. Laminate and integrate the stacked piezoelectric inert parts,
A laminated piezoelectric element comprising an electrode material layer provided on a surface of a material layer at an end face of the piezoelectric active portion. The multilayer piezoelectric element according to claim 1, wherein the thickness of the piezoelectric inactive portion is set to a thickness capable of generating a plurality of vibrations in the multilayer piezoelectric element.   2. The multilayer piezoelectric element according to claim 1, wherein only the piezoelectric inactive portion has a concave portion or a convex portion for enlarging the displacement of the vibration.   4. The laminated piezoelectric element according to claim 1, wherein power is supplied through a circuit board connected to the electrode material layer.   5. The laminated piezoelectric element according to claim 1, wherein the laminated piezoelectric element has a cylindrical shape, and the piezoelectric inactive part is laminated and integrated in a laminating direction of the piezoelectric active part.   The multilayer piezoelectric element according to claim 1, wherein the plurality of vibrations are at least two bending vibrations intersecting a stacking direction of the multilayer piezoelectric element.   3. The laminated piezoelectric element according to claim 1, wherein the laminated piezoelectric element has a flat plate shape, and the piezoelectric inactive part is laminated and integrated on one side in the laminating direction of the piezoelectric active part.   8. The multilayer piezoelectric element according to claim 7, wherein a part of the material layer of the end face of the piezoelectric active portion is polarized by an electrode material layer provided on the surface thereof.   8. The multilayer piezoelectric element according to claim 7, wherein a convex portion is formed on a part of the piezoelectric inactive portion.   The multilayer piezoelectric element according to claim 1, wherein the plurality of vibrations are two out-of-plane bending vibrations.   7. A vibration wave driving device comprising the laminated piezoelectric element according to claim 1, wherein the laminated piezoelectric element is a vibrating body, and a contact body that is in pressure contact with the vibrating body is rotated.   11. The multilayer piezoelectric element according to any one of claims 1, 2, 7 to 10, wherein the multilayer piezoelectric element is a vibrating body, and the vibrating body and a contact body that is in pressure contact with the vibrating body are relatively disposed. A vibration wave driving device characterized by being moved. In the vibration wave driving device that generates vibration in the vibrating body and rotates the contact body that is in pressure contact with the vibrating body,
The vibrator has a piezoelectric active portion in which a plurality of layers of a material having a conversion function for converting an electrical quantity into a mechanical quantity and a plurality of electrode material layers divided into a plurality of layers, and a plurality of layers of the material having a conversion function. It is composed of laminated piezoelectric elements that are laminated and integrated with a layered piezoelectric inactive part, and an electrode material layer is provided on the surface of the end face of the laminated piezoelectric element, and the contact body is added to the piezoelectric inactive part. A vibration wave drive device characterized by pressure contact.

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