JPH02150109A - Mechanical filter for compound longitudinal oscillation - Google Patents

Abstract

PURPOSE:To reduce the transmission of oscillation generated in a longitudinal oscillation tone piece to a holding part, etc., by forming an insulation member on a supporting member to the neighborhood of a piezoelectric member and a conductive member on the insulation member, respectively, and connecting a good conductor wire to the piezoelectric member from an end part in the direction of the piezoelectric member in a direction almost intersecting orthogonally to the direction of longitudinal oscillation. CONSTITUTION:Insulation layers 54 and 56 are formed on the supporting members 40 and 42 and an outer frame member 50, and bonding pads 58 and 60 of conductive thin film are formed on the surface part of the insulation layer 54. Micro bonding wires 66 and 68 with low resistance values are connected to the bonding pads 58 and 60, respectively. Meanwhile, bonding pads 72 and 74 and a connection pattern 76 are also formed on the surface part of the insulation layer 56, and bonding wires 78 and 80 are connected to the bonding pads 72 and 74, and the other ends 78p and 80p of the bonding wires are connected in the direction almost intersecting orthogonally to electrode plates on the surface of piezoelectric ceramics 46a and 46b on an output side. In such a way, it is possible to reduce the propagation of the longitudinal oscillation in the bonding wires 66, 68, 78, and 80.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a composite longitudinal vibration mechanical filter, in particular a structure including a longitudinal vibrator (hereinafter referred to as a longitudinal vibrator) and a piezoelectric member. An insulating member is formed on the support member provided to support the piezoelectric member, and a conductor member is further provided on the insulating member, and a relatively fine good conductor is formed from the end of the conductor member near the piezoelectric member. By configuring the wire to be connected to the electrode plate of the piezoelectric member in a direction substantially perpendicular to the longitudinal vibration direction, it is possible to reduce transmission of vibrations generated in the longitudinal vibrating bar from the conductor wire to other members. The present invention relates to a composite longitudinally vibrating mechanical filter that prevents a decrease in the voltage amplification factor (Q) of a longitudinally vibrating vibrating bar.

[Background of the Invention] Recently, mechanical filters have been widely used in communication equipment and the like as an intermediate between LC filters and crystal filters. This is because mechanical filters have excellent selection characteristics due to their good Q value characteristics, are also excellent in stability against temperature changes, and can be miniaturized.

The first example of this type of composite longitudinal vibration mechanical filter is
As shown in the figure. As can be understood from the figure, the composite longitudinal vibration mechanical filter has an input side longitudinal vibration sound piece 2 and an output side longitudinal vibration sound piece 4, which are arranged on the same plane and made of a metal material or the like. There is. The input side longitudinally vibrating sound bar 2 and the output side vertically vibrating sound bar 4 are integrally connected by constant elastic coupling members 6 and 8. In this case, a support member 10 is provided at the outer central part of the input side longitudinal vibration sound piece 2 and the output side vertical vibration sound piece 4.
and 12 are provided protrudingly. A pair of input side piezoelectric ceramics 14a and 14 are provided on the input side longitudinal vibrating sound piece 2.
b are polymerized and fixed using soldering or the like, and a pair of output side piezoelectric ceramics 16a and 16 are also attached to the output side longitudinal vibrating sound piece 4.
b is polymerized and fixed. The support members 10 and 12
The upright pieces 24a and 2 of the holding member 24 have U-shaped ends.
It is fixed to the upper center of 4b by laser welding or the like.

The composite longitudinal vibration mechanical system constructed in this way
A supply line 1 for supplying a human signal is connected between the input side piezoelectric ceramics 14a, 14b and the upright piece 24a of the filter.
8 is connected to a grounding wire 18e, while a lead-out wire 20 for deriving an output signal and a grounding wire 20e are connected to the output-side piezoelectric ceramics 16a, 16b and the upright piece 24b.

According to the above configuration, the input side longitudinal vibration sound piece 2 and the output side vertical vibration sound piece 4, which are connected in series by the coupling members 6 and 8, are arranged substantially in the air, and their longitudinal vibration etc. It is understood that it is formed so that there is no problem. After the compound longitudinal vibration mechanical filter is housed in a frame (not shown) or the like, it is attached to an intermediate frequency amplification section of a communication device or the like to achieve its desired purpose.

In the composite longitudinal vibration mechanical filter configured as described above, a high frequency signal S from a signal source OSC via a resistor R is attached between the supply line 18 and the ground line 18e on the input side piezoelectric ceramics 14a and 14b. The input side piezoelectric ceramics 14a and 14b are connected to an electrode (not shown) and connected to the input side longitudinal vibrating sound piece 2 which is electrically grounded.
generates an electric field corresponding to the high-frequency signal. This electric field causes the input side piezoelectric ceramics 14a and 14b to move in the thickness direction and in the directions indicated by arrows V and V in the figure.

Electrostriction occurs in the direction shown in
It resonates at a frequency F1 where l is a half wavelength of the longitudinal wave. If the average propagation velocity of the longitudinal wave in the input side vertically vibrating acoustic bar 2 is V, the frequency F is given by the following equation.

Fl = 2LI /V (1) The longitudinal vibration at this frequency F is mechanically coupled to the output side longitudinal vibrating sound piece 4 in the coupling members 6 and 8, and the output side longitudinal vibration sound piece 4 has a long length. It resonates with longitudinal vibration of frequency F2 due to length L2. Similar to equation (1), this frequency F2 is as follows, where V is the average propagation velocity of the longitudinal wave of the output longitudinally vibrating sound bar 4, F2=2L2/V (2). In the electric field generated in the output side piezoelectric ceramics 16a and 16b due to the longitudinal vibration of the output side vertically vibrating sound piece 4, a voltage generated at the unillustrated electrodes of the output side piezoelectric ceramics 16a and 16b is applied between the lead wire 20 and the ground wire 2Oe. It is derived as a high frequency signal S2 having a predetermined, for example, steep frequency characteristic.

Incidentally, the frequency characteristics of this type of composite longitudinal vibration mechanical filter depend on the Q value (hereinafter referred to as Q value) of the longitudinal vibration acoustic bar. A large Q value indicates sharp resonance, that is, steep frequency characteristics, which is expressed by the following equation.

...(3) As can be understood from the above equation (3), in a longitudinally vibrating sound piece that does not use nonlinear vibrations, that is, operates under boat-like vibrations, if the resonance vibration energy is increased, , the loss per period of the resonant frequency increases accordingly.

Therefore, even if the vibration energy is increased, it will not cause an increase in the Q value. The causes of loss per cycle of the resonant frequency are generally as follows.

The first factor is a loss caused by the conversion of the vibration energy of the longitudinally vibrating sound piece into natural energy by the material of the members that constitute the vertically vibrating sound piece. Furthermore, the second
This is a loss that occurs when vibration energy propagates through a support member provided to support the vertically vibrating acoustic bar and is transmitted to a holding member etc. attached to the support member. The third factor is the loss caused by propagation through the conductive wire electrically connected to the piezoelectric ceramic attached to the longitudinally vibrating acoustic bar.

Therefore, in order to improve the characteristics of the composite longitudinal vibration mechanical filter, it is necessary to eliminate the factors that reduce these Q values. As is known from well-known techniques or experiments, the third factor cannot be ignored compared to the first and second factors. In particular, the conducting wire is attached to a piezoelectric ceramic electrode plate by soldering or the like, and the Q value changes depending on the connection state of the soldering or the like. Further, when a tool or the like comes into contact with the conducting wire during the manufacturing process or the like, and the spatial arrangement thereof is deformed, the propagation state of vibration energy changes and the frequency characteristics change, making the frequency characteristics etc. unstable. Furthermore, if the conducting wire is connected in the same direction as the vibration direction of the vertical vibrating sound bar, for example, in parallel to the longitudinal direction of the longitudinal vibrating sound bar on the input side and the output side, the vibration energy transmitted through the conducting wire will be large and the Q value will decrease. The disadvantages of each are revealed.

[Object of the Invention] The present invention has been made to overcome the above-mentioned disadvantages, and includes a piezoelectric member superimposed on the input side and output side vertically vibrating sound pieces and the input side and output side longitudinally vibrating sound pieces. An insulating member is formed up to the vicinity of the piezoelectric member on each supporting member that holds a structure consisting of a structure such as Fine conductor wires are connected to the electrode plates of the piezoelectric members on the input side and the output side in a direction substantially perpendicular to the longitudinal vibration direction, so that the vibration energy generated in the longitudinal vibrating bar propagates through the conductor, for example. It is an object of the present invention to provide a composite longitudinal vibration mechanical filter configured to reduce the transmission of vibration to a holding member, etc., and to prevent a decrease in the Q value of a longitudinal vibration sound bar.

[Means for Achieving the Object] In order to achieve the above object, the present invention provides a composite longitudinal vibration mechanical filter that forms and derives a supplied high frequency signal into a predetermined frequency band. A plurality of vibrating bodies including an input side and an output side, a piezoelectric member having an electrode plate superimposed on the input side vibrating body and the output side vibrating body for connecting a conductor, and the plurality of vibrating bodies. a plurality of coupling members to be connected, a support member formed to protrude from the input side vibrating body and the output side vibrating body, and a plurality of vibrating bodies including the input side and output side to which the support member is attached. a holding member for holding, an insulating member formed on each of the supporting members, a conductor member formed on the insulating member, and an electrode plate having one end connected to the conductor member and the other end of the piezoelectric member. and a conducting wire connected in a direction substantially perpendicular to the direction.

[Embodiment] Next, a preferred embodiment of the composite longitudinal vibration mechanical filter according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 2, reference numeral 30 indicates a composite longitudinal vibration mechanical filter according to the present embodiment, and the composite longitudinal vibration mechanical filter 30 includes an input side longitudinal vibration sound piece 32 and an input side longitudinal vibration sound piece 32. 32 and an output-side vertical vibrating sound piece 34 having the same shape.

The input side and output side longitudinal vibrating sound bars 32 and 34 are arranged on the same plane, and are connected to each other by coupling members 36 and 38 made of thin constant elastic material using laser welding or the like. Furthermore, support members 40 and 42 are provided on the input-side vertically vibrating sound piece 32 and the output-side vertically vibrating sound piece 34, protruding from their central portions. A pair of input side piezoelectric ceramics 44a and 44b are superimposed and fixed to the input side longitudinal vibrating sound piece 32 by soldering or the like. Similarly, output side piezoelectric ceramics 46a and 46b are also applied to the output side longitudinal vibrating sound piece 34.
is polymerized and fixed. Input side piezoelectric ceramic 44a,
44b and output-side piezoelectric ceramics 46a and 46b, electrodes (not shown) such as metallization are formed in advance on the surfaces thereof, respectively.

The respective ends of the support members 40 and 42 are attached to the inner end surface of a rectangular metal outer frame member 50 by laser welding or the like. In this case, the outer frame member 50, the input-side vertically vibrating sound piece 32, and the output-side vertically vibrating sound piece 34 are on the same plane.

Further, input side and output side piezoelectric ceramics 44a are provided on the outer peripheral surfaces of the support members 40 and 42 and the outer frame member 50.
, 44b and 46a, 46b are provided. The attachment portion of the conducting wire is shown in FIGS. 3 and 4. FIG. 4 shows the main part of the cross section taken along the line ■--■ in FIG.

As can be understood from the figure, in the attachment part of the conducting wire, an insulating layer 54 is first applied to the supporting members 40 and 42 and the outer frame member 50.
and 56, a thin film of polyimide material or the like is formed using, for example, screen printing or the like.

Bonding bats 58 and 60 are formed on the surface of the insulating layer 54 as conductive thin films using screen printing or the like using a conductive solvent or the like. Furthermore, a connection pattern 62 is provided that similarly connects bonding butts 58 and 60.

One ends 66t and 68t of bonding wires 66 and 68 made of extremely fine and low resistance wires, such as gold or aluminum materials, are connected to the bonding bats 58 and 60, respectively.

Further, the other ends 66p and 68p are connected to the electrode plates on the surfaces of the input side piezoelectric ceramics 44a and 44b, respectively, so as to be substantially orthogonal to each other.

On the other hand, there are also bonding bats 72 on the surface of the insulating layer 56.
and 74, and a wiring pattern 76 are formed. One ends 78t and 80t of bonding wires 78 and 80 are connected to the bonding bats 72 and 74, respectively. Further, the other ends 78p and 80p are connected in a direction substantially perpendicular to the electrode plates on the surfaces of the output side piezoelectric ceramics 46a and 46b, respectively.

Further, a supply line 84 and a ground line 84e are connected to the connection pattern 62 and the outer frame member 50, respectively, and a lead-out line 86 and a ground line 86e are connected to the connection pattern 76 and the outer frame member 50, respectively. With this configuration, the supporting members 40 and 42 and the connecting members 36 and 3
8, the input side longitudinal vibration sound piece 32 and the output side vertical vibration sound piece 34, etc., can be operated without affecting the operation of their longitudinal vibration.
It will be understood that the outer frame member 50 is disposed in a hollow state.

The composite longitudinal vibration mechanical filter 30 according to the present invention is constructed as described above, and its operation and effects in this embodiment will be explained next.

First, a pair of input side piezoelectric ceramics 44a and 44b
A high frequency signal S2 is generated from a signal source OSC via a resistor R via a supply line 84 and a ground line 84e between the input side longitudinally vibrating acoustic bar 32 and a frequency converter such as a superheterodyne receiver. A 455 KHz intermediate frequency signal is provided.

As a result, the electrically grounded input longitudinal vibrating sound bar 3
2, an electric field corresponding to the high frequency signal S is generated through the input side piezoelectric ceramics 44a and 44b. Due to this electric field, the input side piezoelectric ceramics 44a and 44b produce electrostriction in the thickness direction and in the directions indicated by arrows m1 and mo in the figure, and the input side longitudinal vibrating resonator 32 has a length L4 that is half the wavelength of the longitudinal wave. It resonates at frequency F4. Assuming that the average propagation velocity of longitudinal waves in the input side longitudinally vibrating sound bar 32 is V,
Frequency F4 is given by the following equation.

F4=2L4/V (4) This longitudinal vibration mechanically engages and propagates to the output side longitudinal vibration sound piece 34 via the coupling members 36 and 38, and the output side longitudinal vibration sound piece 34 becomes longer. Due to the length L5, it responds at a vibration of frequency F5, that is, it resonates at a longitudinal vibration. Similar to equation (4), this frequency F5 is calculated as follows, assuming that the average propagation velocity of the longitudinal wave of the output longitudinally vibrating sound piece 34 is V, then F5 = 2LS /v... (
5). The electric field generated in the output piezoelectric ceramics 46a and 46b due to the electrostriction of the longitudinal vibration of the output longitudinal vibrating sound bar 34 generates a voltage in the electrodes (not shown) of the output piezoelectric ceramics 46a and 46b, which is caused by the transmission of longitudinal vibration, etc. An intermediate frequency signal of, for example, 455 KHz having a predetermined steep frequency characteristic, that is, a narrow band frequency characteristic, is derived from the deriving line 86 and the grounding line 86e as the output signal S5.

In the composite longitudinal vibration mechanical filter 30 formed in this way, fine bonding wires 66.
68 and 78.80 are connected in a substantially perpendicular direction to the longitudinal vibration directions m, , mo of the input side and output side vertically vibrating sound pieces 32 and 34, respectively.

Therefore, the propagation of the longitudinal vibration through the bonding wires 66, 68 and 78, 80 is reduced, and a decrease in the Q value of the input and output longitudinal vibration bars 32, 34, etc. is effectively prevented. Become. Furthermore, even if, for example, a production tool comes into contact with the bonding wires 66.68 and 78.80 during the production process, causing deformation of the spatial arrangement, the input side In addition, the decrease in the Q value of the output longitudinally vibrating sound bars 32, 34, etc. is relatively reduced.

Although the above embodiment has been described using two longitudinally vibrating sound bars, the present invention is not limited to this, and for example, as shown in FIG. 5, a steeper frequency characteristic can be obtained. It is also possible to configure a plurality of vertically vibrating sound bars, each having three or more pieces. That is, in this composite longitudinal vibration mechanical filter 100, the input side longitudinal vibration sound piece 1
02, a pair of input side piezoelectric ceramics 104a and 10
4b is superimposed and fixed, and output side piezoelectric ceramics 108a and 108b are superposed and fixed to the output side longitudinal vibrating sound piece 106. Furthermore, longitudinal vibration sound pieces 112.114,
and 116 are formed on the same plane with coupling members 120 to 134, respectively. Further, it includes an outer frame member 136 that surrounds the entire structure, and the inner end surface of the outer frame member 136 and the input-side longitudinal vibration sound piece 102 are connected by a support member 138. Similarly, the output longitudinally vibrating sound piece 106 is connected to the support member 142.

The support members 138 and 142 and the outer frame member 136 are provided with attachment portions for conducting wires. The attachment portion of the conductive wire is provided with insulating layers 148 and 1 on the front and back surfaces of support members 138 and 142.
50 is provided, and further laminated for bonding para)
154a and 154b (not shown), and 158a and 158b (not shown) are formed.

Further, the bonding wires 154a and 154b are connected by a connection pattern 160, and bonding wires 164 and 166 are connected so as to be substantially perpendicular to the surfaces of the input side piezoelectric ceramics 104a and 104b.

Furthermore, bonding para) 158a and 158b
are connected by a connection pattern 168, and bonding wires 172 and 174 are connected so as to be substantially perpendicular to the surfaces of the output side piezoelectric ceramics 108a and 108b.

The configuration is similar to the embodiment shown in FIG. 2, so a detailed explanation is not necessary.

The attachment part of the conductor formed in this way is connected to the connection pattern 1.
Signal source 0.60. . A supply line 176 connected to is connected. Further, a ground wire 176e is connected to the outer frame member 136. The connection pattern 168 includes a lead-out line 17 for output.
8 is connected, and the ground wire 178e is connected to the outer frame member 136.
It is connected to the.

The functions and effects of the composite longitudinal vibration mechanical filter 100 configured as described above are basically the same as the configuration of the mechanical filter 30, and therefore, redundant explanation thereof will be omitted.

The composite longitudinal vibration mechanical filters 30 and 100 shown in FIGS. 2 and 5 are housed in a frame as shown in FIG. 6, and are used, for example, as a shock-resistant longitudinal vibration mechanical filter 200. In this shock-resistant longitudinal vibration mechanical filter 200, an insulating substrate 202 has signal input terminals 204a, 204b and a signal derivation terminal 20.
6a and 206b are provided, and a frame member 208 made of plastic or the like serving as an insulating spacer is placed on top of the frame member 208. Conductor layers 20111a, 2 (J8b, 208f, 208g) are formed on the frame member 208. Furthermore, the composite longitudinal vibration mechanical filter 100 is fitted and placed on the upper part of the frame member 208. Further, a frame member 212 is placed on the composite longitudinal vibration mechanical filter 100. As a result, the longitudinal vibration sound pieces formed in the outer frame member 136 of the composite longitudinal vibration mechanical filter 100 are in a hollow state. It will be understood that the terminal 204 for signal human power is located at
a and 204b are conductor layers 208 provided on the frame material 208
a, 208b and the wiring pattern 168 of the composite longitudinal vibration mechanical filter 100 and the outer frame member 136 are connected using separate conducting wire members (not shown), respectively.

On the other hand, the signal output terminals 206a and 206b are connected to the frame member 20.
The conductor layers 208f and 208g provided in the composite longitudinal vibration mechanical filter 100 are connected to the wire connection pattern 160 and the outer frame member 136 using separate conductor members or the like. By connecting in this way, it is possible to input and output the high frequency signal S and the output signal S5 with a relatively simple configuration. Furthermore, a cover plate 216 is placed on the upper part of the frame material 212 so as to close the opening of the frame material 212, and each of the above-mentioned members is joined with screws or an adhesive to form a sealed state. . With this configuration, the signal human power terminals 204a, 20 can be connected on the surface of the printed circuit board (not shown).
4b and a signal output terminal 206a.

206b is fixed using soldering, so-called surface-mount shock-resistant composite longitudinal vibration mechanical filter 200 is formed with a relatively simple member structure.

This type of structure is sufficiently compatible with multilayer substrates or three-dimensional structures of substrates that are frequently used these days, and has the advantage of improving convenience and freedom of use.

Next, FIG. 7 shows a main part of a modified example of the attachment part of the conducting wire.

As can be understood from the figure, this example includes a separate tubular insulator 222 that is passed through the support member 42, and a separate tubular insulator 222
The power supply member 224 is laminated on the outer peripheral surface of the power supply member 224. One end of the power feeding member 224 is connected to a wiring pattern 62 formed on the insulating layer 56 of the outer frame member 50.

On the other hand, one ends 78t and 80t of bonding wires 78 and 80 are connected to the other end of power supply member 224. Also, the other end 7 of the bonding wires 78 and 80
8p and 80p are connected to the not-illustrated electrode surfaces of output-side piezoelectric ceramics 46a and 46b, respectively, so as to be substantially orthogonal to each other.

Although the attachment portion of the conductor wire has been described as the attachment portion of the conductor wire connected to the output side piezoelectric ceramics 46a and 46b in the embodiment shown in FIG. 2, it may be constructed similarly for connection of other parts. Of course. The conductive wire attachment portion has the advantage that, for example, since the power supply member 224 is formed over the entire outer peripheral surface of the tubular insulator 222, the bonding wires 78 and 80 can be attached more freely.

In this embodiment, an insulating layer or a tubular insulator is formed on the attachment part of the conductor using a screen printing method, and a conductive thin film pad butt, a wiring pattern, etc. are formed using a screen printing method. Although it is laminated, it is not limited to this, and for example, it can be manufactured separately using a method of creating a flexible substrate in which the insulating layer, the bonding pad, the wiring pattern, etc. are formed on the flexible substrate, and the required This does not prevent the conductor from being inserted into the position and forming the attachment part for the conductor.

[Effects of the Invention] As described above, according to the present invention, a structure consisting of an input side and an output side vertically vibrating sound piece and a piezoelectric member etc. superimposed on the input side and output side longitudinally vibrating sound piece is held. An insulating member is formed on the supporting member provided for the purpose of the piezoelectric member, and a conductive member is further formed on the insulating member, so that a relatively fine conductive wire is formed from the end of the conductive member in the direction of the piezoelectric member. By configuring the piezoelectric member to be connected to the piezoelectric member in a direction substantially perpendicular to the longitudinal vibration direction, vibrations generated in the longitudinal vibration bar can be transmitted through the connected conductor and transmitted to, for example, the holding member. This effectively prevents a reduction in the Q value of the longitudinally vibrating sound bar, thereby reducing the insertion loss in the circuit network used.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments, and various improvements and changes in design can be made without departing from the gist of the present invention. Of course.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the configuration of a composite longitudinal vibration mechanical filter according to the prior art, FIG. 2 is a perspective view showing the configuration of a composite longitudinal vibration mechanical filter according to the present invention, and FIG. FIG. 4 is an enlarged view of the main part of the conductor attachment part in the composite longitudinal vibration mechanical filter shown in FIG. 2, and FIG. Complex longitudinal vibration mechanical
FIG. 6 is a perspective view showing another embodiment of the filter in which a plurality of vertically vibrating acoustic bars are configured. FIG. 6 is a perspective view showing an example of the composite longitudinally vibrating mechanical filter shown in FIG. 3 configured as a surface-mounted type. , FIG. 7 is a perspective view showing a modified example of the attachment portion of the conducting wire. 32...Input side vertical vibration sound piece 34...Output side vertical vibration sound piece 36.38...Coupling member 40.42...
Support members 44a, 44b...input side piezoelectric ceramic 4
6a, 46b... Output side piezoelectric ceramic 50... Outer frame member 54.56... Insulating layer 60.72,
? 4... Bonding pad 76... Connection pattern 68.78.80... Bonding wire... Composite longitudinal vibration mechanical filter... Shock-resistant composite mechanical filter FIG, 3

Claims (1)

[Claims] (1) A composite longitudinal vibration mechanical filter that forms and derives a supplied high-frequency signal into a predetermined frequency band, which includes a plurality of vibrating bodies including an input side and an output side of the high-frequency signal, and the input side vibrating body. and a piezoelectric member superimposed on the output side vibrating body and provided with an electrode plate for connecting a conductor;
A plurality of coupling members connecting the plurality of vibrating bodies; a supporting member formed to protrude from the input side vibrating body and the output side vibrating body; A holding member for holding a plurality of vibrating bodies including an output side, an insulating member formed on each of the supporting members, a conductor member formed on the insulating member, and one end connected to the conductor member and the other A composite longitudinal vibration mechanical filter comprising: a conducting wire whose end is connected in a direction substantially perpendicular to the electrode plate of the piezoelectric member.