JP2000092875A - Piezoelectric actuator and method of manufacturing the same - Google Patents

Abstract

[PROBLEMS] To prevent a decrease in vibration characteristics of a vibrating body. [MEANS FOR SOLVING PROBLEMS] By making an angle between a piezoelectric element (15) and a lead wire (16) an acute angle, weakening a spring force of a lead wire. Ensure vibration characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric actuator in which a piezoelectric element and a lead wire are connected, and an improvement in a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, a piezoelectric actuator which causes a vibrating body to bend and vibrate by excitation of a piezoelectric element and which is driven by the bending vibration has attracted attention. Conventionally, as shown in FIG. 4, a stator used for this piezoelectric actuator includes a support 41, a central shaft 42 provided on the support 41, and a central shaft 4.
One end is connected to each of an elastic body 44 fixed to the piezoelectric element 45, a piezoelectric element 45 bonded to one surface of the elastic body 44, and electrode patterns 45a and 45b formed on the piezoelectric element 45 by means such as vapor deposition. Lead 46 for supplying the excitation signal
a, 46b. Here, the vibrating body 43 is constituted by the elastic body 44 and the piezoelectric element 45. The lead wire is C
It was bonded to the support 41 using a u-wire.

[0003]

However, in the lead wire 46 made of Cu wire, since the lead wires 46a and 46b other than the connection portion with the piezoelectric element 45 can move freely, the lead wires 46a and 46b and the piezoelectric element When the angle between the piezoelectric element 45 and the piezoelectric element 45 is 45 °, the spring force of the lead wire 46 adhered to the support base 41 is increased, and the excitation movement of the piezoelectric element 45 is reduced. Because of the obstruction, there has been a problem that the vibration characteristics of the vibrating body 43 are reduced.

Further, in a lead wire in which a conductive thin film is fixed to a film-like base material, a phenomenon that hinders the excitation motion appears more strongly than occurs in a Cu wire, and an angle formed between the piezoelectric element and the lead wire. When the angle is vertical or greater, the rigidity of the film-like base material significantly impedes the excitation motion of the piezoelectric element, thereby deteriorating the vibration characteristics of the vibrating body.

In addition, since there is no step of connecting the piezoelectric element and the lead wire and then deforming the piezoelectric element and the lead wire to an optimal angle, the yield is remarkably reduced. This phenomenon becomes more conspicuous as the size of the vibrator is smaller or the excitation signal (drive voltage) input to the piezoelectric element via the lead wire is smaller. SUMMARY OF THE INVENTION An object of the present invention is to provide a piezoelectric actuator in which disturbance of excitation motion caused by a lead wire is reduced and vibration characteristics of a vibrating body are improved, and a method of manufacturing the same.

[0006]

According to the present invention, the piezoelectric element and the lead wire are connected, and the angle between the piezoelectric element and the lead wire is set to be an acute angle. Further, the method for manufacturing a piezoelectric actuator of the present invention includes a step of connecting a piezoelectric element and a lead wire,
Setting the angle between the piezoelectric element and the lead wire to a predetermined angle.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a piezoelectric element and a lead wire are connected, and the angle between the piezoelectric element and the lead wire is set to an acute angle. Here, the lead wire is, for example, Cu, Au, A
1 and a flexible substrate in which a conductive thin film is fixed to a substrate.

[0008] The piezoelectric elements include those manufactured using lead zirconate titanate, barium titanate, lead titanate, lithium niobate, lithium tantalate, and electrostrictive resin. The connection between the piezoelectric element and the lead wire includes methods such as soldering, thermocompression bonding, and joining with an anisotropic conductive film. The angle between the piezoelectric element and the lead wire is adjusted by supplying an excitation signal to the piezoelectric element through the lead wire and detecting the vibration characteristics so that the angle becomes an acute angle, or predetermined within an acute angle range. For example, fixing the lead wire so that the angle is adjusted.

According to this, the excitation signal is supplied from the lead wire connected to the piezoelectric element, and the spring force of the lead wire can be reduced. Therefore, the excitation motion of the piezoelectric element is not hindered, and the vibration characteristics of the vibrating body are secured. Also,
The lead wire of the present invention may be composed of a conductive thin film and a film-like base material.

Here, the conductive thin film is a conductive thin film of Cu, Ag, carbon or the like, and the film-shaped base material is made of polyimide resin, silicon resin, phenol resin, epoxy resin, polyether resin. And the like. The fixation between the conductive thin film and the film-shaped base material includes those made by bonding, electroforming, printing, and the like. The pattern formation of the conductive thin film includes those formed by screen printing, photolithography, or the like.

According to this, the excitation signal is supplied through the lead wire connected to the piezoelectric element, and the lead wire is maintained at a predetermined angle within an acute angle range by the rigidity of the film-shaped base material. Therefore, the excitation motion of the piezoelectric element is not hindered, the vibration characteristics of the vibrating body are secured, and the connection position of the lead wire can be easily positioned with respect to the electrode pattern of the piezoelectric element, thereby improving mass productivity.

Further, the lead wire of the present invention may be constituted by a conductive thin film and a film-shaped base material, and the conductive thin film may be formed by extending from the film-shaped base material. Here, the lead wire is a conductive thin film of Cu or the like, and the film-like base material is made of polyimide resin, silicon resin, phenol resin, epoxy resin, polyether resin, or the like.

[0013] The adhesion between the conductive thin film and the film-shaped substrate includes those formed by bonding, electroforming and the like. In addition, the patterning of the conductive thin film includes one manufactured by photolithography or the like. The connection between the piezoelectric element and the lead wire
Methods such as soldering, thermocompression bonding, and joining with a conductive adhesive or an anisotropic conductive film are included. Generally, connection methods called inner lead bonding (ILB) and outer lead bonding (OLB) correspond to this.

According to this, the excitation signal is supplied through the lead wire connected to the piezoelectric element, and the lead wire is maintained at a predetermined angle within an acute angle range by the rigidity of the base material. In the vicinity of the connection portion, the conductive thin film extends from the film-like base material, and is not affected by the rigidity of the base material. Therefore, the excitation motion of the piezoelectric element is not hindered, the vibration characteristics of the vibrating body are secured, and the connection position of the lead wire can be easily positioned with respect to the electrode pattern of the piezoelectric element, thereby improving mass productivity.

Further, according to the present invention, the lead wire may be fixed with a sufficient length from the connection portion between the piezoelectric element and the lead wire. Here, the lead wire is, for example, a so-called flexible substrate in which a wire such as Cu, Au, or Al, a conductive thin film is fixed to a film-shaped base material, and a so-called flexible substrate in which a conductive thin film is projected from the film-shaped base material. An ILB substrate or an OLB substrate is included. The fixing of the lead wire includes a method of bonding to a member arranged at a position distant from the piezoelectric element, a method of sandwiching with a screw or the like, and a method of soldering to a substrate of an excitation signal circuit.

According to this, the excitation signal is supplied through the lead wire connected to the piezoelectric element, and is fixed at the opposite end of the connection between the lead wire and the piezoelectric element, so that the acute angle range is obtained. , A predetermined angle is maintained. Also, since the lead wire and the piezoelectric element are fixed at a position sufficiently distant from the connection, the vibration propagating from the lead is attenuated, and the piezoelectric element is fixed at the fixed end opposite to the connection with the piezoelectric element. There is almost no suppression of the excitation motion of. Therefore, the excitation movement of the piezoelectric element is not hindered, the vibration characteristics of the vibrating body are secured, and the angle between the piezoelectric element and the lead wire can be secured at an acute angle in any posture of the piezoelectric actuator, thereby increasing reliability. is there.

Further, the method of manufacturing a piezoelectric actuator according to the present invention includes a step of connecting a piezoelectric element and a lead wire, and a step of making an angle between the piezoelectric element and the lead wire a predetermined angle. is there. Here, the lead wire includes, for example, a wire such as Cu, Au, or Al, a so-called flexible substrate in which a conductive thin film is fixed to a film-like base material, or the like.

The piezoelectric elements include those manufactured using lead zirconate titanate, barium titanate, lead titanate, lithium niobate, lithium tantalate, and electrostrictive resin. The connection between the piezoelectric element and the lead wire includes methods such as soldering, thermocompression bonding, and joining with an anisotropic conductive film. In the order of the manufacturing process, after connecting the piezoelectric element and the lead wire, the lead wire is deformed by applying a bending force so that the angle between the piezoelectric element and the lead wire becomes a predetermined angle. As a method of deformation, a method for pressing and deforming a tool for determining the angle of the lead wire near the connection part of the piezoelectric element and the lead wire, a piezoelectric element at the end opposite to the connection part of the piezoelectric element and the lead wire, or Examples include a method of fixing the lead wire at a predetermined angle while fixing it to another member such as a support base, a method of fixing the end opposite to the connection portion, and pressing and deforming a tool for deforming the lead wire to a predetermined angle.

Further, in addition to the above-described order of the manufacturing process, after fixing the end opposite to the connection portion between the piezoelectric element and the lead wire to another member such as a piezoelectric element or a support base, the connection between the piezoelectric element and the lead wire is made. A method of connecting a lead element with a piezoelectric element while deforming by applying a bending force to the lead wire so that the angle becomes a predetermined angle, pressing a tool for deforming to a predetermined angle after connecting the lead wire and the piezoelectric element A method for deformation is included.

Tools for deforming a lead wire to a predetermined angle include tools made using ceramics, metal, resin, and the like. When the positional relationship between the tool and the lead wire is vertical, the tool is pressed. How to deform, how to deform by pulling, if parallel, how to deform by sliding,
A method of rolling and deforming is included. It also includes indirect deformation methods such as blowing air. According to this, the lead wire is deformed to a predetermined angle, or an excitation signal is supplied from the lead wire connected to the piezoelectric element, and the connection between the piezoelectric element and the lead wire is made while detecting the vibration characteristics of the vibrating body. It is possible to deform so that the angle is optimal. Furthermore, immediately after the lead wire is connected to the piezoelectric element, the lead wire contacts the vibrating body or has an angle that suppresses the vibration characteristics. Even when a vibration failure occurs, the vibration failure is reduced. Thus, the lead wire can be deformed.

Therefore, regardless of the connection condition between the piezoelectric element and the lead wire and the variation in the connection condition, the angle between the piezoelectric element and the lead wire can be produced at the optimum angle with good reproducibility.
The excitation motion of the piezoelectric element is not hindered, the vibration characteristics of the vibrating body are secured, and the productivity is improved.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to FIGS. Embodiment 1 First, a piezoelectric actuator to which the present invention is applied will be described. FIG. 1 shows a sectional structure of the piezoelectric actuator, and FIG. 2 shows a planar structure of the piezoelectric actuator observed from the lead wire 16 side.

1 and 2, a piezoelectric actuator comprises an elastic body 14 and a piezoelectric element 15 bonded to the elastic body 14.
Form a vibrating body 13, a center axis 12 penetrating through the center of the elastic body 14, a support 11 for fixing the center axis 12, and a support base on the opposite side of the support 11 from the vibrator 13. 11
The lead wire 16 is formed of a film-like base material 16c and conductive thin films 16a and 16b wired on the base material.

The rotor 1 having the center axis 12 as a rotation axis
0, a pressure spring 19a for holding the rotor 10 between the elastic members 14 and pressurizing the same, and a pressure spring seat 19b for fixing the pressure spring 19a to the support base 11. Here, the piezoelectric element 15 is formed in a substantially disk shape and is made of lead zirconate titanate.

Further, the electrode patterns 15a and 15b are divided into twelve equal parts in the circumferential direction in a fan shape, and a total of six sets of polarization processing parts are provided with one set of adjacent divided parts. The polarization processing is performed so that each set of polarization processing units has an alternating polarity.
Further, as for the electrode patterns 15a and 15b, a short-circuit pattern for wiring the electrode patterns 15a and 15b on the outside and the inside of the piezoelectric element is formed by means such as vapor deposition in order to wire every other 12 electrode patterns. . Then, one electrode pattern 15a is connected to a lead wire 16a described later,
The other electrode pattern 15b is connected to a lead wire 16b.

The elastic body 14 has a disk shape corresponding to the piezoelectric element 15, and is made of an elastic material such as an aluminum alloy, stainless steel, or copper. Also, one of the piezoelectric elements 15
The columnar projections 14a are provided at equal intervals at positions corresponding to the boundaries of the equally divided electrode patterns. Also, the support base 11
Is a plate-like body obtained by cutting a rigid material into a predetermined shape,
A window hole 11a for connecting the lead wire 16 to the piezoelectric element 15 is formed in the center thereof.

The central shaft 12 is a rod made of a rigid material and supports the vibrating body 13. Conductive thin film 16
Copper is used for a and 16b, polyimide is used for the form-like base material 16c, and the conductive thin film and the film-like base material are fixed with an epoxy adhesive. The shape of the conductive thin film is produced (patterned) by photolithography. The conductive thin films 16a and 16b are extended from the base material 16 to be connected to the electrode patterns 15a and 15b from the window holes 11a.
6b is connected to the electrode patterns 15a and 15b, respectively.

The rotor 10 is made of a resin to which an inorganic filler is added, the pressure spring 19a is made of a highly elastic material such as iron, and the pressure spring seat 19b is made of a structural material such as a resin or metal. . The vibration characteristics of the vibrating body are determined by measuring the admittance using an impedance analyzer without the rotor 10 and the pressure spring 19a assembled, and by measuring the number of revolutions with the rotor 12 and the pressure spring 19a assembled. To compare.

As described above, according to the present embodiment, the thickness of the conductive thin film is 25 μm, the width is 80 μm, and the length is 20 μm.
Preset to twice, fix the film-shaped substrate on the opposite end to the connection between the piezoelectric element and the lead wire, connect the piezoelectric element and the lead wire, and set the angle between the piezoelectric element and the lead wire. When the angle is acute, the admittance, which indicates the vibration characteristics of the vibrating body, and the rotation speed are both good. When the angle is measured at a position close to the connection between the piezoelectric element and the lead wire, the admittance is high within approximately 45 °. , And both admittance and rotation speed showed higher values within approximately 30 °.

Further, by adjusting the length of the conductive thin film, the angle between the piezoelectric element and the lead wire can be arbitrarily selected. However, the conductive thin film is perpendicular to the connection portion, or If you make an obtuse angle to bend,
Both admittance and rotation speed have been reduced to 30%. This indicates that making the angle between the piezoelectric element and the lead wire an acute angle improves the vibration characteristics of the vibrating body.

Further, when a lead wire in which a conductive thin film is fixed to a film-like base material is connected with a piezoelectric element and an anisotropic conductive film, when the angle between the piezoelectric element and the lead wire is acute as described above, Compared to the case where the lead wire is bent at an obtuse angle, the admittance that represents the vibration characteristics of the vibrating body is
The obtuse angle was 鋭 of the acute angle. In addition, when the length of the conductive thin film was compared at 20 times, 10 times, and 5 times the width, there was no difference in admittance at 20 times and 10 times, but at 5 times the length, the admittance was up to 50%. Reduced. Embodiment 2 FIG. 3 shows a tool for deforming a stator cross-sectional structure and a lead wire of a piezoelectric actuator.

In FIG. 3, FIG. 3A shows the piezoelectric element 1
5 shows a state immediately after connecting the lead wire 36 to the piezoelectric element 5, and the angle between the piezoelectric element and the lead wire is substantially 90 °. FIG. 3B shows a state in which the tool 30 is pressed against the lead wire 36, and FIG.
Applies a bending force to the lead wire 36 at a predetermined angle, and
This shows a state of being deformed by 5 °.

Here, the tool 3 for deforming the lead wire 36
No. 0 is made of metal, and the flat portion 30a at the tip of the tool 30 is brought into contact with the connection portion between the piezoelectric element and the lead wire, and the inclined portion 30b
Apply bending force to the lead with. At this time, the deformation angle of the lead wire 36 can be determined by setting the inclination angle of the inclined portion 30b. As a comparative example, a method of forming a predetermined angle before connecting the lead wires was attempted.However, a variation in connection positions between the electrode pattern of the piezoelectric element and the lead wires was large, and disconnection and short-circuit were caused. It turned out to be inferior in mass production at most.

Also, the lead wire is temporarily fixed to the piezoelectric element,
Alternatively, even when the wires are pressed and connected, the lead wires and the piezoelectric element are not rubbed by using a tool that grips the lead wires, and by pulling and deforming the lead wires and bonding them to the support base or fixing them by sandwiching them. ,
The angle between the piezoelectric element and the lead wire could be set to a predetermined angle.

As described above, according to the present embodiment, the admittance was measured and compared between the state immediately after the lead wire was connected to the piezoelectric element and the state after the lead wire was deformed by the tool. In this state, an improvement of as much as 30% was observed. Therefore, when the electrode pattern of the piezoelectric element is connected to the lead wire, the positional accuracy is improved, and thereafter, the angle between the piezoelectric element and the lead wire is formed at a predetermined angle, thereby realizing a manufacturing method with high mass productivity.

[0036]

The present invention is embodied in the form described above and has the following effects. An excitation signal is supplied via a lead wire connected to the piezoelectric element, and the spring force of the lead wire can be reduced. Therefore, the excitation motion of the piezoelectric element is not hindered, and the vibration characteristics of the vibrating body are secured.

Further, the lead wire is maintained at a predetermined angle within an acute angle range by the rigidity of the film-like base material. Therefore, the excitation motion of the piezoelectric element is not hindered, the vibration characteristics of the vibrating body are secured, and the connection positions of the lead wires can be easily positioned, thereby improving mass productivity. In addition, the lead wire keeps a predetermined angle within an acute angle range due to the rigidity of the base material, and the metal thin film extends from the film-like base material near the connection portion of the piezoelectric element. Not affected by the rigidity of the material. Therefore, the excitation motion of the piezoelectric element is not hindered, the vibration characteristics of the vibrating body are secured, and the connection positions of the lead wires can be easily positioned, thereby improving mass productivity.

Further, since the connection between the lead wire and the piezoelectric element is fixed at the opposite end, a predetermined angle is maintained within an acute angle range. Also, since the lead wire and the piezoelectric element are fixed at a position sufficiently distant from the connection, the vibration propagating from the lead is attenuated, and the piezoelectric element is fixed at the fixed end opposite to the connection with the piezoelectric element. It hardly suppresses the excitatory movement. Therefore, the excitation movement of the piezoelectric element is not hindered, the vibration characteristics of the vibrating body are secured, and the angle between the piezoelectric element and the lead wire can be secured at an acute angle in any posture of the piezoelectric actuator, thereby increasing reliability. is there.

Then, the lead wire is deformed to a predetermined angle, or an excitation signal is supplied from the lead wire connected to the piezoelectric element, and the connection between the piezoelectric element and the lead wire is made while detecting the vibration characteristics of the vibrating body. It is possible to deform so that the angle is optimal. Furthermore, the lead wire contacts the vibrator,
Even when a vibration failure occurs, the lead wire can be deformed so as to reduce the vibration failure. Therefore, since the angle between the piezoelectric element and the lead wire can be produced at the optimum angle with good reproducibility, the excitation movement of the piezoelectric element is not hindered,
Vibration characteristics of the vibrating body are secured, and productivity is improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a cross-sectional structure of a piezoelectric actuator.

FIG. 2 is an explanatory diagram showing a planar structure of a piezoelectric actuator observed from a lead wire side.

FIG. 3 is an explanatory view showing a stator cross-sectional structure of a piezoelectric actuator and a tool for deforming a lead wire.

FIG. 4 is an explanatory view showing a cross-sectional structure of a stator of a conventional piezoelectric actuator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Rotor 11 Support stand 11a Window hole 12 Center axis 13 Vibrating body 14 Elastic body 15 Piezoelectric element 15a, 15b Electrode pattern 16 Lead wire 16a, 16b Conductive thin film 16c Film-shaped base material 18 Adhesive 19a Pressure spring 19b Pressure Spring seat 30 Tool 30a Flat part 30b Inclined part 36 Lead wire

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takuo Osaki 1-8-8 Nakase, Mihama-ku, Chiba-shi, Chiba F-term in Seiko Instruments Inc. 5H680 AA00 AA06 AA06 AA12 BB16 DD01 DD23 DD39 DD40 DD53 DD73 DD84 DD85 DD92 FF01 FF08 FF17 FF19 GG02 GG23 GG25 GG27 GG42

Claims (5)

[Claims] A piezoelectric actuator in which a lead wire (16) is connected to a piezoelectric element (15).
5) The piezoelectric actuator, wherein the angle between the lead wire (16) and the lead wire (16) is an acute angle. 2. A lead wire (16) comprising a conductive thin film (16a,
2. A piezoelectric actuator according to claim 1, wherein said piezoelectric actuator comprises a film-like base material. 3. A lead wire (16) comprising a conductive thin film (16a,
16b) and a film-like substrate (16c),
The conductive thin film (16a, 16b) is a film-like substrate (1
The piezoelectric actuator according to claim 1, wherein the piezoelectric actuator extends from (6). 4. The piezoelectric actuator according to claim 1, wherein the lead wire is fixed with a sufficient length from a connection portion between the piezoelectric element and the lead wire. 5. A step of connecting a lead wire (16) to the piezoelectric element (15), and a step of setting an angle between the piezoelectric element (15) and the lead wire (16) to a predetermined angle. Manufacturing method of a piezoelectric actuator.