JP5031153B2 - Laminated electro-mechanical energy conversion element and vibration wave drive device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laminated electro-mechanical energy conversion element and a vibration wave driving device formed by alternately laminating a plurality of layers of a material layer having an electro-mechanical energy conversion function and an electrode material layer. The surface electrode connected to the through hole of the element is suitable for a vibration wave driving device such as a vibration wave motor.
[0002]
[Prior art]
As an example of an element as a vibration source of a vibration body constituting a vibration wave driving device such as a vibration wave motor, the element is sandwiched between blocks made of cylindrical metal or ceramic and bent into the block as follows. An element as a vibration generation source of a vibrating body of a rod-shaped vibration wave motor that causes vibration and rotationally moves a contact member in contact with the block by a circular or elliptical movement at any one point on the block surface caused by the bending vibration; There is an element as a vibration generation source of a ring-shaped vibrating body that fixes the element on one surface of a ring-shaped elastic body with, for example, an adhesive and applies a rotational motion by combining two standing waves.
[0003]
Further, as an example of an element used for a rod-like vibration wave motor, the piezoelectric elements described in Japanese Patent Laid-Open Nos. 3-40767 and 3-117384 are shown in FIG. A single plate-like single-plate piezoelectric element a shown in FIG. 2 is a circular region whose front surface coincides with regions (+) and (-) whose polarization directions are opposite in the left and right directions. The electrode material layers (hereinafter referred to as electrode layers) l ₁ and l ₂ are provided on the piezoelectric material a ′ through the slits S, and the entire back surface is provided with the electrode layer l ₃ . Using a plurality of single-plate piezoelectric elements a, a plurality of and 90-degree phase differences are given to some of the piezoelectric elements as in the vibrating body e of a rod-shaped vibration wave motor shown in FIG. Piezoelectric elements a _{1 to} a ₅ are laminated with metal electrode plates b _{1 to} b _{6 connected} to an external electric circuit, and assembled with blocks d ₁ and d ₂ made of metal or ceramics and bolts c. It is fixed.
[0004]
The piezoelectric elements a _{1 to} a ₄ are used for driving, and the piezoelectric element a ₅ is used as a sensor for outputting a control signal. In this piezoelectric element a, a piezoelectric material (piezoelectric ceramics), which is generally formed by firing a ceramic powder having piezoelectricity by pressing or extruding, is processed to a constant thickness, processed into a circular shape, and then deposited or printed. The electrode layers l _{1 to} l ₃ are formed by the method, and polarization treatment is performed using these electrode layers to give polarization directions (+) and (−).
[0005]
On the other hand, recently, laminated piezoelectric elements as laminated electro-mechanical energy conversion elements made by alternately laminating piezoelectric material layers and electrode material layers have attracted attention, and attempts have been made to reduce the size and voltage of vibration sources. For example, it is described in JP-A-8-213664. FIG. 13 shows a laminated piezoelectric element f developed for a rod-shaped vibration wave motor. Electrode material layers (hereinafter referred to as internal electrode layers) 4 and 5 are made of a piezoelectric material that has an electromechanical energy conversion function. It is an element that is provided on a layer, stacked alternately, and connected by eight interlayer wirings 2 for measuring conduction between the layers.
[0006]
The interlayer wiring 2 is called a so-called through hole in which a small hole is provided and a conductive metal is filled therein. In addition, eight interlayer wirings 2 are exposed on the front (front) surface which is one end surface to form eight surface electrodes 3, and the electrode layers 4 and 5 of the laminated piezoelectric element f are divided into four. A voltage can be applied to each of the areas. FIG. 14 is a view of the laminated piezoelectric element f as viewed from the front surface and the back surface, and the surface electrode 3 is exposed only on the front surface.
[0007]
FIG. 15 shows a cross-sectional view of a vibration wave motor incorporating a laminated piezoelectric element f. The laminated piezoelectric element f is sandwiched between blocks d ₁ and d _{2 made of} an elastic body of metal or ceramics, and at the same time using a wiring board g. The vibrating body h is made by measuring the continuity between each surface electrode 3 exposed on the surface and an external electric circuit (not shown), and tightening and fixing with a bolt c.
[0008]
[Problems to be solved by the invention]
In the above two conventional examples, the difference between FIG. 12 which is an example of a vibration wave motor using a plurality of single-plate piezoelectric elements and FIG. 15 which is an example of a vibration wave motor using one laminated piezoelectric element is 2 There is one.
[0009]
One is that the metal blocks d ₁ and d ₂ and the bolt c are electrically connected to the electrical ground of the piezoelectric element through the metal plates b _{1 to} b ₆ and have the same potential in the example of FIG. _No. 15 was not electrically connected to the laminated piezoelectric element, and the metal blocks d ₁ and d ₂ and the bolt c were in an electrically floating state, that is, in an insulated state. For this reason, in the case of the vibration wave motor using the laminated piezoelectric element shown in FIG. 15, electrical noise is generated due to the generation of floating capacitance or the like.
[0010]
In the example of FIG. 12, one piezoelectric element a ₅ is used as a sensor for outputting a control signal, but in the case of FIG. 15, no sensor is provided and the sensor is not used. Since the vibration wave motor was controlled, the fine control performed while sensing the mechanical vibration state of the vibrating body could not be performed.
[0011]
Accordingly, an object of the present invention is to provide a laminated block which can be easily connected between the metal block and the ground of the laminated electro-mechanical energy conversion element and can be used as a sensor using the internal electrode layer of the laminated electro-mechanical energy conversion element. The present invention provides a mechanical energy conversion element and a vibration wave driving device using the electro-mechanical energy conversion element as a vibration source.
[0015]
[Means for Solving the Problems]
In the first invention, the laminated electro-mechanical energy conversion element is disposed between the first elastic body and the second elastic body, and the first elastic body and the second elastic body are fastened by fastening means. Accordingly, in the vibration wave driving apparatus including a vibrating body in which the laminated electro-mechanical energy conversion element is fixed between the first elastic body and the second elastic body, the laminated electro-mechanical energy conversion element A first circuit board provided between one end face of the first electrode and the first elastic body, and provided between the other end face of the laminated electro-mechanical energy conversion element and the second elastic body. The laminated electro-mechanical energy conversion element is formed by alternately laminating a plurality of layers of materials having an electro-mechanical energy conversion function and layers of electrode materials. Between the plurality of electrode material layers A plurality of through holes that tomb conduction, conduction with the plurality of through-holes and the first circuit board, a plurality of first electrodes formed on the surface opposite to the first circuit board, wherein A plurality of second electrodes formed on a surface facing the second circuit board , wherein the plurality of second electrodes are an electrode used as a ground, and the inside of the laminated electro-mechanical energy conversion element An electrode layer that is electrically connected to an electrode layer that generates electrical signals obtained by converting mechanical energy into electrical energy, and the electrode used as the ground is an electrode layer that generates the electrical signals The electrode layer that is electrically connected to the electrode layer that is electrically connected to the electrode layer that generates the electrical signal is insulated from the electrode layer that is electrically connected to the electrode used as the ground of the first electrode. and are And wherein the door.
[0018]
A second invention is the first aspect, wherein the plurality of first electrodes, and wherein the conductive Goku含 Mukoto for high-frequency voltage is applied.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 1 shows a first embodiment of the present invention.
[0021]
FIG. 1 shows an exploded perspective view and an external perspective view of a laminated piezoelectric element as a laminated electro-mechanical energy conversion element. The laminated piezoelectric element 1 has a diameter that becomes a through hole in a green sheet of piezoelectric ceramic that becomes a piezoelectric layer. Drill a 0.1mm hole, fill it with conductive paste, and then print the electrode pattern on the surface of the green sheet that will become the internal electrode layer by printing the conductive paste. And then calcined and then subjected to polarization treatment and finally machined.
[0022]
In the figure, the laminated piezoelectric element 1 is passed through the interlayer wiring 2 by eight through holes and the front surface which is one end face of the element, like the conventional laminated piezoelectric element f in FIG. Eight surface electrodes 3 with holes exposed are formed.
[0023]
Further, the internal electrode layer 4 forms the same four-divided internal electrode layers A1, A2, B1, and B2 as in the conventional example, but the internal electrode layer 5 is also divided into four internal electrode layers GA1, GA2, GB1, and so on. GB2 is formed. Specifically, the laminated piezoelectric element 1 has an outer diameter of 10 mm, an inner diameter of 2.8 mm, a thickness of about 2.2 mm, a piezoelectric material layer thickness of 85 μm, an internal electrode layer thickness of 2 to 3 μm, and internal electrode layers 4 and 5. The outer diameter is 9.5 mm, and the number of internal electrode layers is 24. In order to drive a vibration wave motor as a vibration wave drive device, the internal electrode layers A1, A2, GB1, and GB2 corresponding to the electrical ground are substantially equal to the natural frequency of the vibrating body in the internal electrode layers A1 and A2, respectively. The matched high-frequency voltage is applied to the internal electrode layers B1 and B2 with a high-frequency voltage having a phase difference of 90 ° from A1 and A2.
[0024]
Further, in the present embodiment, as shown in FIG. 2, the other end surface (surface) different from the end surface (surface) having the surface electrode 3 to which a voltage is supplied via the circuit board g to drive the vibration wave motor ( On the back surface, four through-holes that measure electrical continuity with the internal electrode layers GA1, GA2, GB1, and GB2 that are electrical grounds are exposed on the end surface (back surface), and the surface electrode 6 is formed. As a result, as shown in FIG. 3, when incorporated in the vibrating body h of the vibration wave motor, the metal block d ₁ which is an elastic body and the surface electrode 6 are in contact with each other and are electrically connected, and further, the metal block d _1. Is also conducted to the bolt c and the metal block d ₂ through the same voltage as the laminated piezoelectric element.
[0025]
In the present embodiment, the number of the surface electrodes 6 is four. However, since these four surface electrodes are all equivalent at the ground, the number of the surface electrodes 6 may be one.
[0026]
Specifically, when a high frequency voltage Vp = 7 V, for example, is applied to the internal electrode layers A1 and A2 and the internal electrode layers B1 and B2 with a phase difference of 90 ° from the internal electrode layers A1 and A2, the rotational speed of the vibration wave motor is 600 rpm and torque is 25 g. Since the performance of cm was obtained and the metal block bolt c was also at the same potential, the stability of the performance was increased and the noise problem which was the above-mentioned drawback could be solved. In addition, since the surface electrode can be made very easily in the production of the laminated piezoelectric element, it can be produced with almost no increase in cost.
[0027]
(Second Embodiment)
In the second embodiment, a surface electrode of a through hole is provided for converting the mechanical vibration of the laminated piezoelectric element into an electrical signal and outputting it, that is, for taking out a control output as a sensor. Is.
[0028]
Conventionally, the voltage generated by the pressure applied to the piezoelectric element when the vibration wave motor is driven is used for controlling the vibration wave motor. In the conventional example, in FIG. 12, the piezoelectric element a ₅ is used as a control sensor. The output can be taken out through a metal plate b ₆ as an electrode plate. However, in detail, an insulating sheet is sandwiched between the electrode plate b ₆ and the metal block d ₂ to measure insulation, or an expensive but non-conductive ceramic block is used.
[0029]
As shown in FIG. 4, the multilayer piezoelectric element 1 ′ of the present embodiment has a 1/4 area area on the other end face (back face) side different from the end face (front face) having the surface electrode 3. An electrode layer 7 for the sensor is provided. The sensor electrode layer 7 is electrically connected to the surface electrode 10 exposed on the element end face (back face) shown in FIG. Here, the number of internal electrode layers is a total of 25 layers obtained by adding one electrode layer for sensors, and is the number of layers obtained by adding one electrode layer to the laminated piezoelectric element of the first embodiment.
[0030]
FIG. 6 shows a state in which the laminated piezoelectric element 1 ′ of the present embodiment is incorporated in a vibration body of a vibration wave motor. An electric signal generated in the internal electrode layer 7 by the mechanical vibration of the vibration wave motor can be taken out from the surface electrode 10 to the external circuit using the circuit board g ′.
At this time, since the opposing electrode layer (GA2) of the internal electrode layer 7 which is an electrode layer for the sensor is the same as the ground of the laminated piezoelectric element, when it is electrically processed as a signal in an external circuit, the laminated piezoelectric element Use the ground.
[0031]
As a result of the above, it is possible to easily add an electrode layer for a sensor with almost no increase in manufacturing cost, and since it is distant from the surface electrode for driving, the influence of electrical noise is reduced. There is also a merit that it is difficult to receive, and the frequency control of the vibration wave motor can be easily performed.
[0032]
Further, FIG. 7 shows an embodiment in which the first embodiment and the second embodiment described above are used in combination.
[0033]
In FIG. 7, the ground layer GA2 opposite to the sensor electrode layer 7 is electrically connected by a through hole 9, and this through hole 9 is electrically connected to the surface electrode 11 shown in FIG. For example, a through-hole capable of conduction is made in the circuit board g ′ and directly bonded to the metal block d1, while the surface electrode 10 connected to the through-hole 8 is similarly connected to an external circuit using the circuit board g ′. It is also possible to make it.
[0034]
In the above example, through holes are exposed on the front and back surfaces, which are both end faces of the laminated piezoelectric element, to form surface electrodes. However, an electrode film may be provided on the surface around the exposed surface electrode to form an electrode having a larger area. .
[0035]
In FIGS. 5 and 7, the sensor electrode layer is a portion having an area of 1/4 facing the internal electrode layer GA2. However, the sensor electrode layer is 1/1 layer facing the internal electrode layers GA1, GA2 or GB1, GB2. You may provide in the part of 2 area.
[0036]
FIG. 9 shows a modification of the embodiment of FIG. 7. The laminated piezoelectric element 1′-2 of this embodiment is different from the laminated piezoelectric element of FIG. 7 in that a through hole 9 ″ is formed in the electrode layer 7 ′. In the piezoelectric material layer immediately above the ground layer 5 having the electrode layer 7 ', no through hole is formed corresponding to the through hole 9 ".
[0037]
That is, the electrode layer 7 ′, which is the sensor ground facing the sensor electrode layer 7, is independent (insulated) from the electrode layers GA 1, GB 1, GB 2 of the drive ground layer 5, and the through hole 9 ′. 10 is used to conduct to the surface electrode 11 ′ shown in FIG. 10, and the signal voltage for the sensor can be taken out between the surface electrodes 10 and 11 ′.
By doing so, the sensor signal is not affected by the driving voltage, and only a pure sensor signal can be extracted.
[0038]
In the above example, the slow hole on the back side is for ground or sensor,
When supplying a driving voltage, a surface electrode connected to the through hole may be formed using both the surface and the other surface. In the future, especially in small-sized vibration wave motors, it is considered that the laminated piezoelectric element is also reduced in diameter, and when the through-holes are all provided on one side and conduction with the substrate is attempted, the area of the wiring pattern will be insufficient. The present invention is effective.
[0039]
【Effect of the invention】
As described above, according to the present invention, it is possible to electrically drop the ground of a laminated electromechanical energy conversion element such as a laminated piezoelectric element to an elastic body or take out the output of the sensor. There is also an advantage that there is almost no increase in manufacturing and cost.
[0040]
In particular, in the case of a surface electrode used as an output terminal of a sensor, the influence of the noise of the driving voltage is small, and it can be added to the end face of a conventional multilayer piezoelectric element if necessary, and a vibration wave driving device such as a vibration wave motor The design of laminated piezoelectric elements for use has also become easier.
[0041]
In the future, especially in a small vibration wave motor, if the laminated piezoelectric element is also reduced in diameter and all the through holes are provided on one side, it is possible that the area of the wiring pattern that conducts with the substrate will be insufficient. Even when a driving voltage is supplied by a vibration wave motor, the multilayer piezoelectric element of the present invention in which the surface electrode connected to the through hole is formed using both the surface and the other surface is effective.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view and an external perspective view of a multilayer piezoelectric element according to a first embodiment of the present invention. FIG. 2 is a diagram showing surface electrodes exposed on both end faces of the multilayer piezoelectric element of FIG. FIG. 4 is a cross-sectional view of a vibration wave motor incorporating the multilayer piezoelectric element of FIG. 1. FIG. 4 is an exploded perspective view and an external perspective view of the multilayer piezoelectric element in the second embodiment of the present invention. FIG. 6 is a cross-sectional view of a vibration wave motor incorporating the laminated piezoelectric element of FIG. 4; FIG. 7 is an exploded perspective view of the laminated piezoelectric element according to the third embodiment of the present invention. FIG. 8 is a perspective view of the multilayer piezoelectric element shown in FIG. 7. FIG. 9 is an exploded perspective view of the multilayer piezoelectric element according to the fourth embodiment of the present invention. FIG. 10 is a diagram showing surface electrodes exposed on both end faces of the multilayer piezoelectric element of FIG. FIG. 12 is a sectional view of a vibration wave motor incorporating the piezoelectric element of FIG. 11. FIG. 13 is an exploded perspective view of a conventional multilayer piezoelectric element. FIG. 14 is a perspective view of the multilayer piezoelectric element of FIG. 13. FIG. 15 is a sectional view of a vibration wave motor incorporating the multilayer piezoelectric element of FIG.
1,1 ′, 1 ″ Multilayer piezoelectric element 3 of the present invention Surface electrode 6, 10, 11 Surface electrode on the other end surface c Bolt d1, d2 Block g Circuit board h Vibration body

Claims (2)

A laminated electro-mechanical energy conversion element is disposed between the first elastic body and the second elastic body, and the first elastic body and the second elastic body are fastened by a fastening means, whereby the first In a vibration wave driving device including a vibrating body in which the laminated electro-mechanical energy conversion element is fixed between one elastic body and the second elastic body,
A first circuit board provided between one end face of the laminated electro-mechanical energy conversion element and the first elastic body;
A second circuit board provided between the other end face of the laminated electro-mechanical energy conversion element and the second elastic body,
The laminated electro-mechanical energy conversion element is formed by alternately laminating a plurality of layers of materials having an electro-mechanical energy conversion function and layers of electrode materials,
A plurality of through holes for conducting between the layers of the plurality of electrode materials;
A plurality of first electrodes formed on a surface that is electrically connected to the plurality of through-holes and the first circuit board and faces the first circuit board ;
Anda plurality of second electrodes formed on the surface facing the second circuit board
The plurality of second electrodes are electrically connected to an electrode that is used as a ground and an electrode layer that is provided inside the laminated electro-mechanical energy conversion element and generates an electrical signal obtained by converting mechanical energy into electrical energy. An electrode to be
The electrode used as the ground is electrically connected to the electrode layer facing the electrode layer that generates the electrical signal,
The vibration wave driving device characterized in that the electrode layer facing the electrode layer that generates the electrical signal is insulated from the electrode layer that is electrically connected to the electrode used as the ground in the first electrode. . Wherein the plurality of first electrodes, the vibration wave driving device according to claim 1, characterized in that it comprises electrodes for high-frequency voltage is applied.

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