CA1207854A - Piezoelectric resonator - Google Patents
Piezoelectric resonatorInfo
- Publication number
- CA1207854A CA1207854A CA000443948A CA443948A CA1207854A CA 1207854 A CA1207854 A CA 1207854A CA 000443948 A CA000443948 A CA 000443948A CA 443948 A CA443948 A CA 443948A CA 1207854 A CA1207854 A CA 1207854A
- Authority
- CA
- Canada
- Prior art keywords
- substrate
- electrode
- piezoelectric resonator
- major surface
- piezoelectric
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezo-electric or electrostrictive material
- H03H9/56—Monolithic crystal filters
- H03H9/562—Monolithic crystal filters comprising a ceramic piezoelectric layer
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02007—Details of bulk acoustic wave devices
- H03H9/02157—Dimensional parameters, e.g. ratio between two dimension parameters, length, width or thickness
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezo-electric or electrostrictive material
- H03H9/58—Multiple crystal filters
- H03H9/581—Multiple crystal filters comprising ceramic piezoelectric layers
Abstract
ABSTRACT OF THE DISCLOSURE
A piezoelectric resonator comprises a first resonating single mode thickness expansion vibration unit including a first substrate comprised of a piezoelectric material and having two major surfaces, a first common electrode disposed on one major surface of the first substrate, and a first electrode disposed on the other major surface of the first substrate, the first electrode being at least partially opposed to the first common electrode through the first substrate. A second single mode thickness expansion vibration resonating unit includes a second substrate comprised of a piezoelectric material and having two major surfaces, a second common electrode disposed on one major surface of the second substrate, and a second electrode disposed on the other major surface of the second substrate, the second electrode being at least partially opposed to the second common electrode through the second substrate. The first and second resonating units are arrayed and fixed so that the first and second common electrodes are opposed to each other and the first and second common electrodes are electrically connected at at least one portion thereof so that a third electrode is formed, whereby the piezoelectric resonator resonates in a dual mode thickness expansion vibration.
A piezoelectric resonator comprises a first resonating single mode thickness expansion vibration unit including a first substrate comprised of a piezoelectric material and having two major surfaces, a first common electrode disposed on one major surface of the first substrate, and a first electrode disposed on the other major surface of the first substrate, the first electrode being at least partially opposed to the first common electrode through the first substrate. A second single mode thickness expansion vibration resonating unit includes a second substrate comprised of a piezoelectric material and having two major surfaces, a second common electrode disposed on one major surface of the second substrate, and a second electrode disposed on the other major surface of the second substrate, the second electrode being at least partially opposed to the second common electrode through the second substrate. The first and second resonating units are arrayed and fixed so that the first and second common electrodes are opposed to each other and the first and second common electrodes are electrically connected at at least one portion thereof so that a third electrode is formed, whereby the piezoelectric resonator resonates in a dual mode thickness expansion vibration.
Description
~2~l55~
~he present invention relates to a piezoelectric resonator and/ more particularly, relates to a piezoelectric resonator having an improved structure and characteristic.
In the accompanying drawings:-Figs. lA and lB show a front surface and a rear surface of a substrate of a conventional piezoelectric ceramic resonator of TE vibration mode with two-stage structure, respectively;
Fig. 2 is a cross-sectional view of the piezoelectric resonator shown in Figs. 1~ and lB, ~ig. 3 shows a frequency characteristic of the piezoelectric resonator shown in Figs. lA and lB
Fig. 4 is a frequency spectrum diagram of a television signal after video signal detection;
Fig~ 5 shows an SIF filter using a conventional piezoelectric resonator employed in a television;
Figs. 6A and 6B show a front surface and a rear surface of a substrate of a conventional piezoelectric resonator of TS vibration mode with two-stage structure, respectively;
Fig. 7 shows a frequency characteristic of the TS
vibration mode piezoelectric resonator shown in Figs. 6A
and 6B;
Fi~s. 8A and 8B show a front cross-sectional view and a side view~ respectively, of a piezoelectric resonator of a single-stage structure which is a preferred embodiment o the present invention, Fi~. 9 is a perspective view showing a process step for forming a piezoelectric resonator of a preferred embodiment of the present invention;
Fig. 10 is a perspective view showing a piezoelectric resonator of a preferred embodiment oE the present invention~ which is formed through the step shown in Fig. 9;
and Figs. 11 and 12 show a frequency plot of a piezoelectric ~L2~78S~
resonator of a preferred embodiment of the present invention.
A piezoelectric resonator has been being employed widely in the prior art, for example, as a filter in a sound signal detecting circuit of a television and as a reactance element or a phase shifting element in an FM
demodulating circuit, utilizing a characteristic operating as an impedance transducer element to a frequency. A
piezoelectric resonator utilizing a substrate thickness expansion vibration (TE vibration3 mode and a piezoelectric resonator utilizing a substrate thickness shear vibration (TS vibration) mode have been d~veloped as a piezoelectric resonator in a frequency zone of mainly 1 to 50 MHzo These two piezoelectric resonators are generally structured as an energy trapping type dual mode piezoelectric resonator.
Figs. lA and lB show a typical example of a conventional piezoelectric ceramic resonator substrate (two-stage structure) utili~ing a TE vibration mode, wherein Fig. lA shows a front surface of the substrate and Fig. lB shows a rear surface thereof. In these ~igures, the hatched portion shows an electrode film formed on the surface of the resonator substrate.
The piezoelectric resonator having such an electrode structure exhi~its a distribution of electric field as shown in Fig. ~. Fig. 2 shows a cross-sectional view o~
the sub~trate of a piezoelectric ceramic resonator shown in Figs. lA and lB, wherein a verti~al electric field Ez i5 an electric field necessarily needed in this mode and a hori~ontal or parallel electric field Ey i3 an electric field generated between an input electrode and an output electrode, which electric field is not necessary. The horizontal electric field ~y localIy causes a TS vibration and as a result, a spurious appears due to the TS
vibration mode. Since the speed of the TS vibration propagating through the substrate is a half of that of the ~. ...
~20~i4 TE vibration, the spurious appears in the neighborhood of about a half of the necessary frequency.
Fig. 3 shows a frequency characteristic when a piezoelectric ceramic resonator as shown in Figs. lA
and lB is used as a filter. In Fig. 3 r the abscissa axis indicates frequency in MHz and the ordinate axis indicates attenuation in decibels (dB). As can be seen from Fig. 3, a signal having a frequency of ~.50 MHz passes through this filter and the spurious appears in the neighborhood of 1.8 MHz which is about a half of the frequency.
Fig. 4 is a frequency spectrum diagram of a television signal after ~ideo detection. The abscissa axis indicates a fre~uency and the ordinate axis indicates a spectrum. As can be seen in Fig. 4~ a vid~o signal Y is distributed in a frequency region of 0 to fv and a sound signal S i9 superimposed in the frequency region the middle of which is a frequency fs, and a color signal C is superimposed in a frequency region the middle of which is a frequency fc-Now, it is assumed that the piezoelectric resonator of a conventional TE vibration mode ha~ing the above described characteristic of Fig. 3 is used as an SIF
filter which makes only the particular frequency fs pass therethrough. Then, a video signal having a fre~uency in the neighborhood of a half of the frequency fs is made to pass due to a spurious vibration of the filter and appears as a sound buzz of a television.
Accordingly, in case where such a piezoelectric resonator is conventionally used as an SIF filter, the original function as the SIF filter has been able to be achieved by using as assistant a separate high-pass filter 52 connected in series to the piezoelectric filter 51 as shown in Fig. 5.
Figs. 6~ and 6B show a typical example of a conventional piezoelectric ceramic resonator substrate . , .
~L2~71~1S~
(two-stage structure) utilizing a TS vibration mode, wherein Fig. 6A shows a front surface and Fig. 6B shows a rear surface. In these figuresr the hatched portion indicates an electrode film formed on the filter surface.
Fig. 7 indicates a fre~uency characteristic when a piezoelectric ceramic resonator of a TS vibration mode shown in Figs. 6A and 6B is used as a filter. In Fig. 7, the abscissa axis indicates a frequency in MHz and the ordinate a~is indicates attenuation in decibels (diB).
It can be understood through a cGmparison of Fig. 7 with Fig. 3 that the spurious attenuation in the fre~uency region of 0 to 4O0 MHz in the TS vibxation mod~
piezoelectric resonator is very superior to a piezoelectric resonator of the TE vibration mode~ However, even in the piezoelectric resonators of the TS vibration ~ode, the attenuation of 50 to 55 ~ which is practically needed as an SIF filter of a television signal can never be obtained.
Thus, only a circuit as shown in Fig. 5 can be prac-tically employed in the case where the conventional piezoelectric resonator of the TS vibration mGde is used as an SIF ilter as well as in case where the conventional pie~oelectric resonator of the TE vibration mode is used as an SIF filter.
In additionr the thickness of the substrate of the piezoelectric resonator of the TS vibration mode must be made to about one half the thickness of the substrate of the piezoelectric resonator of the TE vibration mode. The reason for this is that, due to different vibratlon manners in these modes, the same resonating frequency can be obtained, in the TS vibration mode, by usinq a substrate having the thickness which is a half o the thickness in case of theT~ vibration mode. As typically shown in Figs. 6A
and 6B, a structure of the piezoelectric resonator of the TS
vibration mode with two-stage structure should be in the t_~ ?
8~i~
form of U-shape in view o~ the nature of the vibration mode. For this reason, the yield of good products and relia~ility become poor in terms of mechanical strength.
Furthermore, a siæe or dimension of a substrate is determined so as to obtain a predetermined electrical characteristic. In this connection, for example, as shown in Figs. lA and 6A, the~size or dimension of the substrate for the conventional TE vibration mode piezoelectric resonator and a conventional TS vibration mode piezoelectric resonator is relatively larger and he~ce there is a defect that there is a limitation for making smaller parts or components u~ilizing such piezoelectric resonators.
The present invention is directed to a piezoelectric resonator having an improved structure and characteristic.
lS Accordingly, an object of the present invention is to provide a piezoelectric resonator ~hich may be made smaller and may have an improved frequency characteristic and enhanced mechanical strength.
The invention provides a piezoelectric resonator comprising a first resonating single mode thickness expansion vibration unit including a first substrate comprised of a piezoelectric material and having two major surfaces, a first common electrode disposed on one major surface of the first substrate, and a first electrode disposed on the other major surface of the ~irst substrate, the first electrode being at least partially opposed to the first common electrode through the first substrate, a second single mode thickness expansion vibration resonating unit including a secon~ substrate comprised of a piezo-electric material and havi~g two major surfaces, a secondcommon electrode disposed on one major surface of the second substrate, and a secon~ electrode disposed on the oth~r major surface of the second substrate, the second ~lectrode being at least partiall~ opposed to the second common electrode through the second substrate, and .
8~i~
~;
arraying means for arraying and ~ixing the ~irst and second resonating units so that the first and second common electrodes are opposed to each other and the first ana second common electrodes are electrically connected at at least one portion thereof so that a third electrode is formed whereby the piezoelectric resonator resonates in a dual mode thickness expansion vibration.
The present invention will become more readily apparent from the followin~ detailed description of an embodiment of the present invention when taken in conjunction with the accompanying drawinqs.
Referring to Figs. 8A and 8B, a piezoelectric resonator embodying the invention comprises a ~irst resonating unit 81 and a second resonating unit 82. Each of the resonating units 81 and 82 has the same shape and structure. The resonating unit 81 has a substrate 811 comprised of piezoelectric material, preferably, ceramic.
On one major surface of the pie~oelectric ceramic substrate 811 is formed an electrode film 812 in a longitudinal direction thereof from the one end to about three fifths, for example. Similarly, a common electrode film 813 is formed on the other major surface in a longitudinal direction thereof from the other end to about three fifths, for example. These electrode ilms 812 and 813 are partially opposed to each other in the middle portion of the piezoelectric ceramic substrate 811 therethrough.
Another resonating unit 82 is of the same structure as that of the resonatinq unit 81.
Two resonating units 81 and 82 are combined such that the common electrode films 813 and 823 are opposed ~o each other and affixed by a stronq and insulating adhesive 84 while leaving a connecting portion 83 of common electrodes.
The common electrodes 813 and 823 affixed in an opposed manner are electrically connected at the connectinq portion 83 so that a single electrode is formed. A common lead 86 3Si4 is connected to the common electrode connecting portion 83 by a solder or an electrically conductive adhesive 85.
An input lead 87 and an output lead 88 are connected to the electrodes 812 and 822, respec-tively, near the end portion thereoE by means of a solder 85 or an electrically conductive adhesive.
Fig. 8B is a side view of the piezoelectric resonator explained in the foregoing and shown in Fig. 8A, wherein the solder or electricaIly conductive adhesive 85 and the leads 86 and 87 are omitted.
A preferred method of manufacturing a piezoelec~ric resonator according to a preEerred embodiment of the present invention as shown inFigs. 8A and 8B will now be described with reference to Figs. 9 and 10. Fig. 9 is a perspective view showing one manufacturing step for a piezoelectric resonator. First of all, resonating unit source substrates 91 and 92 comprised of a piezoelectric material, preferably, a ceramic, are prepared. The polarization axes of the resonating unit source substrates 91 and 92 are in the direction indicated in arrow P which is along the major surfaces thereof. Electrode films 912, 913, 922 and 923 coverinq about three fifths of the major surEaces are ~ormed on the respective major sur~aces of the source substrates 91 and 92. The electrode films 912 and 913 are partially opposed in the nei~hbo~hood of a middle portion and in a longitudinal dire~ion of the source substrate 91 and the electrode films 922 and 923 are partially opposed in the neighborhood oE a middle portion and the longitudinal direction of the source substrate 92. These electrode films may ~e of electrically conductive paint, for example, and are formed by means of painting~ vapor deposition or the like.
Source substrates 91 and 92 for t~o resonating units are brought together with the electrode ~ilms 913 and 922 thereof opposed to ~ach other. An insulating adhesive 840 (Fig. 10) is -Eirstly painted extremely thinly on the major surface 92a on which the electroae film 922 of the resonating ,~:
.. ~ . . . . .. .. .
source substrate 92 is formed. The -two resonating units source substrat~s 91 and 92 are affixed together in this way.
An electrically conductive adhesive 830 (Fig. 10) is painted on one end surface of the combined resonating units, in the middle portion of which the electrode films 91~ and 922 are disposed. The electrically conductive adhesive 830 soaks between the electrode films 913 and 922, whieh are opposed, so that an electrode eonnecting portion ~30a is formed, and hence the electrode films 91~ and 922 are electrically connected.
The thus affixed resonating unit source substrates are cut along line 1 indicated by arrows 95 in Fig. 9. As a result, a plurality of piezoeleetrie resonators, one of which is shown in Fig. 10, are obtained. It will be readily understood that the piezoelectric resonator as shown in Fig. 10 has substantially the same strueture as the piezoelectric resonator shown in Figs. 8A and 8B. In Fig. 10, the same portions as in Fig. 9 are indieated by correspondin~ primed reference numerals.
In the above-described embodiment, two resonating unit source substrates are affixed by using an inæulating adhesive. However, instead ~hereof, an electrically eonduetive adhesive may be employ~d. In sueh a ~ase, only the portion of the eleetrode films 91~ and 922 are affixed to each other. The electric conductive adhesive is painted thinly only on the surfaee 922a of the eleetrode film 922 and, thereafter, the two resonating unit source sub~trates 91 and 92 are combined. Aecordingly, the electrode films 913 and 922 are affixed so that substantially a single electrode is formed.
In the piezoelectrie resonator shown in FigO 10, the T~ vibration is excited in each of the resonating units 11 and 12. For example, in the resonating unit 12, the TS
vi~ration is exeited in the opposed portion o the electrodes 922' and 923' shown by the reference charaeter ~r ~
~ 2~
L in figure and the energy i5 trapped in the longitudinal direction of the substrate 92'. Accordinglyr if and when the length of the substrate 9Z' is made extremely large, for example, more than twenty times as compared with the thic]~ness thereof, neither of the end surfaces o~ -the substrate 92' vibrates. The same applies to the substrate 91'. Hence, it is possible to provide input and output leads in the end portions of electrodes 912' and 923l and a common lead in the common electrode portion 830 by means of solder~ electrically conductive adhesive, or the like so that the element as shown in Fig. 8A is obtained.
In the above-described embodiment, in order to obtain a desired elect~ical characteristic, the shape or configuration of the resonating unit source substrates 91 and 92 and the arrangement of the electrode films on the source substrates may be adequately changed.
Figs. 11 and 12 show electrical characteristics of the piezoelectric resonator of a preferred embodiment ~f the present invention as shown in Figs. 8A, 8B and 10.
Fig. 11 is a plot of admi~tance versus frequency 20 wherein the abscissa axis indicates a fre~uency in ~Hz and the ordina-~e axis indicates a~mittance. In thi.s igure, an S mode curve shows variation of an admittance between a connecting lead (no~ shown) provided for connecting an input lead 87 and an output lead 88 to each other and a common lead 86 in Fig. 8A when an a]ternating current of high frequency of 3 to 6 MHz is applied therebetween. An A mode indicates variation of an a~littance between the input lead 87 and the output lead 8~ when nothing is connected to the common lead 86 and an alternating current of high frequency of 3 to 6 M~z is applied therebetween. As seen fr~m Fig. 11, by chanqing the connecting manner of three terminals of the piezoelectric resonator in Fig. 8A two vibration responses can be obtained.
The two resonating frequencies in these vibration responses are slightly offset. Accordingly, it can be understood that 7~5~
the piezoelectric resonator ~orms a dual mod~ piezoelectric resonator as a conventional energy trapping type dual mode piezoelectric resonator stated above.
Fiq. 12 shows a characteristic of attenuation with respect to a frequency when a piezoelectric resonator shown in Fig. 8A is used as a filter. In Fig. 12, the abscissa axis indicates frequency (MHz) and the ordinate axis represents an attenuation (dB). As readily understood ~rom Fig. 12, the spurious response in the frequency reqion 13 o~ 0 to 10 MHz of the piezoelectric resonator is about 37 or 38 dB. This corresponds to the ~requency characteristic of the conventional TS vibration mode piezoelectric resonator with a two-stage structure as described in the oregoing. Thus, a single structure piezoelectric resonator in accordance with the present invention has per~ormance corresponding to a conventional two-stage structured piezoelectric resonator. Accordingly, an insertion loss of the present piezoelectric resonator is about a half of that o~ a conventional piezoelectric resonator, which means a great improvement.
The dimensions of the piezoelectric resonator shown in Fiqs~ 8A and 8B are such that the width is 0.8 mm, the height is 5.0 ~m and the thickness is 0.5 mm. Accordingly, the sur~ace area thereo~ is 4.0 ~Tl2~ On the other hand, the size of a conventional TE vibration mode piezoelectric resonator as shown in Figs. lA and 2 and having the same resonating frequencyas the resonator of the invention is such that the width is 9.0 mm, the height is 6.0 mm and the thickness 0.5 mm and hence the surface area is 54.0 mm2, In addition, the size o~ the conventional TS vibration mode piezoelectric resonat~x hauing the same resonating ~requency is such that the width is 3.0 ~mJ the height is 6.5 mm and the thickness is 0.23 mm and hence the sur~ace area is 19.5 mm . Thus, the piezoelectric resonator in accordance with the present invention can be made substantially smaller in size.
, . . . ... .. . . . .... . . . . . . . . . . . . .
7~
In addition, since the piezoelectric resonator embodying the present invention is of such structure -that two resonating substrates are affixed to each other, the ~hickness is thick as cornpared with a conventional piezoelectric resonator, particularly, a piezoelectric resonator of a TS vibration mode, and thus, the mechanical strength is enhanced and the mechanical reliability can be improved.
An electric characteristic of a piezoelectric resonator shown in Fig. 10 can be properly changed by properly selecting the opposed width L of the electrode ~ilms and a cut width W of a substrate. The opposed width L of the electrode Eilms can be easily changed by changing a printing pattern in forming the electrode films and the cut width W can be simply changed by initial adjustment of ~he cutting when the affixed resonating unit source substrate is cut. Accordingly, as compared with a con~entional piezoelectric resonator, the design of the piezoelectric resonator embodying the present invention can be easily changed so that desired electrical characteristicsJ such as passband width, maximum attenuation and insertion loss, are obtained. Particularly, it is easy to change the passband width.
Fi~. 13 shows c~nother preEerred embodiment of the piezoelectric resonator embodying the present invention.
The significant feature of the piezoelectric resona-tor shown in Fig. 13 resides in that the above described piezoelectric resonator is made to be a two-stage structured piezoelectric resonator. A gap 133 is formed in the two-stage structured piezoelectric resonator so that a firstresonating element 131 and a second resonating element 132 can independently operate. The gap 133 can be easily formed by using a stripe of conductive adhesive 134 having an appropriate width and thickness and extending perpendicular to the paper so as to adhere the first resonating element 131 to the second resonating element 13Z.
, -~;~07854 In manufacturing the piezoelectric xesonator 13 as shown in Fig. 13, many produc-ts can be simply made by fixing together the resonating unit source substrates and thereafter cuttinq them, which is similar to the manufacturing method explained in the foregoing referring to Figs. 9 and 10.
Since the Fig. 13 piezoelectric resonator is of a two-stage structure, the insertion loss thereof is the same as the above described conventional two-stage structured piezoelectric resonator. However, the spurious characteristic in the frequencY region of 0 to 10 MHz is greatly improved. Accordingly, such Fig. 13 piezoelectric resonator can be used solely as an SIF filter of a television signal.
lS Furthermore, the piezoelectric resonator in accordance with the present invention has the followiny advantages.
More particularly, conventionally, a piezoelectric resonator for an FM detection circuit is generally of a single-stage structure and a piezoelectric resonator for a filter is of a two-stage structure. Thus different size of piezoelectric resonator has been used for various usage in the past and, therefore, standardization of devices has never been achieved and an easy assembly has not been made by an automatlc assembly machine. As described above, the ~5 piezoelectric resonator of a single-stage in accordance with the present invention has the same characteristic as a conventional two-stage struc~ured piezoelectric resonator.
Therefore, it becomes possible to use the same size of piezoelectric resonator for various kinds of usage and standardi~ation of devices can be achieved. As a result, an easy assembly is made possible by means of an automatic assembly ma~hine, with a consequent decrease in the cost of manufacturing.
Although the present invention has been described and illustrated in detail, it is to be understood that the same is by way of illustration and example only and is not ~2~'7~54 to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.
..... ...
~he present invention relates to a piezoelectric resonator and/ more particularly, relates to a piezoelectric resonator having an improved structure and characteristic.
In the accompanying drawings:-Figs. lA and lB show a front surface and a rear surface of a substrate of a conventional piezoelectric ceramic resonator of TE vibration mode with two-stage structure, respectively;
Fig. 2 is a cross-sectional view of the piezoelectric resonator shown in Figs. 1~ and lB, ~ig. 3 shows a frequency characteristic of the piezoelectric resonator shown in Figs. lA and lB
Fig. 4 is a frequency spectrum diagram of a television signal after video signal detection;
Fig~ 5 shows an SIF filter using a conventional piezoelectric resonator employed in a television;
Figs. 6A and 6B show a front surface and a rear surface of a substrate of a conventional piezoelectric resonator of TS vibration mode with two-stage structure, respectively;
Fig. 7 shows a frequency characteristic of the TS
vibration mode piezoelectric resonator shown in Figs. 6A
and 6B;
Fi~s. 8A and 8B show a front cross-sectional view and a side view~ respectively, of a piezoelectric resonator of a single-stage structure which is a preferred embodiment o the present invention, Fi~. 9 is a perspective view showing a process step for forming a piezoelectric resonator of a preferred embodiment of the present invention;
Fig. 10 is a perspective view showing a piezoelectric resonator of a preferred embodiment oE the present invention~ which is formed through the step shown in Fig. 9;
and Figs. 11 and 12 show a frequency plot of a piezoelectric ~L2~78S~
resonator of a preferred embodiment of the present invention.
A piezoelectric resonator has been being employed widely in the prior art, for example, as a filter in a sound signal detecting circuit of a television and as a reactance element or a phase shifting element in an FM
demodulating circuit, utilizing a characteristic operating as an impedance transducer element to a frequency. A
piezoelectric resonator utilizing a substrate thickness expansion vibration (TE vibration3 mode and a piezoelectric resonator utilizing a substrate thickness shear vibration (TS vibration) mode have been d~veloped as a piezoelectric resonator in a frequency zone of mainly 1 to 50 MHzo These two piezoelectric resonators are generally structured as an energy trapping type dual mode piezoelectric resonator.
Figs. lA and lB show a typical example of a conventional piezoelectric ceramic resonator substrate (two-stage structure) utili~ing a TE vibration mode, wherein Fig. lA shows a front surface of the substrate and Fig. lB shows a rear surface thereof. In these ~igures, the hatched portion shows an electrode film formed on the surface of the resonator substrate.
The piezoelectric resonator having such an electrode structure exhi~its a distribution of electric field as shown in Fig. ~. Fig. 2 shows a cross-sectional view o~
the sub~trate of a piezoelectric ceramic resonator shown in Figs. lA and lB, wherein a verti~al electric field Ez i5 an electric field necessarily needed in this mode and a hori~ontal or parallel electric field Ey i3 an electric field generated between an input electrode and an output electrode, which electric field is not necessary. The horizontal electric field ~y localIy causes a TS vibration and as a result, a spurious appears due to the TS
vibration mode. Since the speed of the TS vibration propagating through the substrate is a half of that of the ~. ...
~20~i4 TE vibration, the spurious appears in the neighborhood of about a half of the necessary frequency.
Fig. 3 shows a frequency characteristic when a piezoelectric ceramic resonator as shown in Figs. lA
and lB is used as a filter. In Fig. 3 r the abscissa axis indicates frequency in MHz and the ordinate axis indicates attenuation in decibels (dB). As can be seen from Fig. 3, a signal having a frequency of ~.50 MHz passes through this filter and the spurious appears in the neighborhood of 1.8 MHz which is about a half of the frequency.
Fig. 4 is a frequency spectrum diagram of a television signal after ~ideo detection. The abscissa axis indicates a fre~uency and the ordinate axis indicates a spectrum. As can be seen in Fig. 4~ a vid~o signal Y is distributed in a frequency region of 0 to fv and a sound signal S i9 superimposed in the frequency region the middle of which is a frequency fs, and a color signal C is superimposed in a frequency region the middle of which is a frequency fc-Now, it is assumed that the piezoelectric resonator of a conventional TE vibration mode ha~ing the above described characteristic of Fig. 3 is used as an SIF
filter which makes only the particular frequency fs pass therethrough. Then, a video signal having a fre~uency in the neighborhood of a half of the frequency fs is made to pass due to a spurious vibration of the filter and appears as a sound buzz of a television.
Accordingly, in case where such a piezoelectric resonator is conventionally used as an SIF filter, the original function as the SIF filter has been able to be achieved by using as assistant a separate high-pass filter 52 connected in series to the piezoelectric filter 51 as shown in Fig. 5.
Figs. 6~ and 6B show a typical example of a conventional piezoelectric ceramic resonator substrate . , .
~L2~71~1S~
(two-stage structure) utilizing a TS vibration mode, wherein Fig. 6A shows a front surface and Fig. 6B shows a rear surface. In these figuresr the hatched portion indicates an electrode film formed on the filter surface.
Fig. 7 indicates a fre~uency characteristic when a piezoelectric ceramic resonator of a TS vibration mode shown in Figs. 6A and 6B is used as a filter. In Fig. 7, the abscissa axis indicates a frequency in MHz and the ordinate a~is indicates attenuation in decibels (diB).
It can be understood through a cGmparison of Fig. 7 with Fig. 3 that the spurious attenuation in the fre~uency region of 0 to 4O0 MHz in the TS vibxation mod~
piezoelectric resonator is very superior to a piezoelectric resonator of the TE vibration mode~ However, even in the piezoelectric resonators of the TS vibration ~ode, the attenuation of 50 to 55 ~ which is practically needed as an SIF filter of a television signal can never be obtained.
Thus, only a circuit as shown in Fig. 5 can be prac-tically employed in the case where the conventional piezoelectric resonator of the TS vibration mGde is used as an SIF ilter as well as in case where the conventional pie~oelectric resonator of the TE vibration mode is used as an SIF filter.
In additionr the thickness of the substrate of the piezoelectric resonator of the TS vibration mode must be made to about one half the thickness of the substrate of the piezoelectric resonator of the TE vibration mode. The reason for this is that, due to different vibratlon manners in these modes, the same resonating frequency can be obtained, in the TS vibration mode, by usinq a substrate having the thickness which is a half o the thickness in case of theT~ vibration mode. As typically shown in Figs. 6A
and 6B, a structure of the piezoelectric resonator of the TS
vibration mode with two-stage structure should be in the t_~ ?
8~i~
form of U-shape in view o~ the nature of the vibration mode. For this reason, the yield of good products and relia~ility become poor in terms of mechanical strength.
Furthermore, a siæe or dimension of a substrate is determined so as to obtain a predetermined electrical characteristic. In this connection, for example, as shown in Figs. lA and 6A, the~size or dimension of the substrate for the conventional TE vibration mode piezoelectric resonator and a conventional TS vibration mode piezoelectric resonator is relatively larger and he~ce there is a defect that there is a limitation for making smaller parts or components u~ilizing such piezoelectric resonators.
The present invention is directed to a piezoelectric resonator having an improved structure and characteristic.
lS Accordingly, an object of the present invention is to provide a piezoelectric resonator ~hich may be made smaller and may have an improved frequency characteristic and enhanced mechanical strength.
The invention provides a piezoelectric resonator comprising a first resonating single mode thickness expansion vibration unit including a first substrate comprised of a piezoelectric material and having two major surfaces, a first common electrode disposed on one major surface of the first substrate, and a first electrode disposed on the other major surface of the ~irst substrate, the first electrode being at least partially opposed to the first common electrode through the first substrate, a second single mode thickness expansion vibration resonating unit including a secon~ substrate comprised of a piezo-electric material and havi~g two major surfaces, a secondcommon electrode disposed on one major surface of the second substrate, and a secon~ electrode disposed on the oth~r major surface of the second substrate, the second ~lectrode being at least partiall~ opposed to the second common electrode through the second substrate, and .
8~i~
~;
arraying means for arraying and ~ixing the ~irst and second resonating units so that the first and second common electrodes are opposed to each other and the first ana second common electrodes are electrically connected at at least one portion thereof so that a third electrode is formed whereby the piezoelectric resonator resonates in a dual mode thickness expansion vibration.
The present invention will become more readily apparent from the followin~ detailed description of an embodiment of the present invention when taken in conjunction with the accompanying drawinqs.
Referring to Figs. 8A and 8B, a piezoelectric resonator embodying the invention comprises a ~irst resonating unit 81 and a second resonating unit 82. Each of the resonating units 81 and 82 has the same shape and structure. The resonating unit 81 has a substrate 811 comprised of piezoelectric material, preferably, ceramic.
On one major surface of the pie~oelectric ceramic substrate 811 is formed an electrode film 812 in a longitudinal direction thereof from the one end to about three fifths, for example. Similarly, a common electrode film 813 is formed on the other major surface in a longitudinal direction thereof from the other end to about three fifths, for example. These electrode ilms 812 and 813 are partially opposed to each other in the middle portion of the piezoelectric ceramic substrate 811 therethrough.
Another resonating unit 82 is of the same structure as that of the resonatinq unit 81.
Two resonating units 81 and 82 are combined such that the common electrode films 813 and 823 are opposed ~o each other and affixed by a stronq and insulating adhesive 84 while leaving a connecting portion 83 of common electrodes.
The common electrodes 813 and 823 affixed in an opposed manner are electrically connected at the connectinq portion 83 so that a single electrode is formed. A common lead 86 3Si4 is connected to the common electrode connecting portion 83 by a solder or an electrically conductive adhesive 85.
An input lead 87 and an output lead 88 are connected to the electrodes 812 and 822, respec-tively, near the end portion thereoE by means of a solder 85 or an electrically conductive adhesive.
Fig. 8B is a side view of the piezoelectric resonator explained in the foregoing and shown in Fig. 8A, wherein the solder or electricaIly conductive adhesive 85 and the leads 86 and 87 are omitted.
A preferred method of manufacturing a piezoelec~ric resonator according to a preEerred embodiment of the present invention as shown inFigs. 8A and 8B will now be described with reference to Figs. 9 and 10. Fig. 9 is a perspective view showing one manufacturing step for a piezoelectric resonator. First of all, resonating unit source substrates 91 and 92 comprised of a piezoelectric material, preferably, a ceramic, are prepared. The polarization axes of the resonating unit source substrates 91 and 92 are in the direction indicated in arrow P which is along the major surfaces thereof. Electrode films 912, 913, 922 and 923 coverinq about three fifths of the major surEaces are ~ormed on the respective major sur~aces of the source substrates 91 and 92. The electrode films 912 and 913 are partially opposed in the nei~hbo~hood of a middle portion and in a longitudinal dire~ion of the source substrate 91 and the electrode films 922 and 923 are partially opposed in the neighborhood oE a middle portion and the longitudinal direction of the source substrate 92. These electrode films may ~e of electrically conductive paint, for example, and are formed by means of painting~ vapor deposition or the like.
Source substrates 91 and 92 for t~o resonating units are brought together with the electrode ~ilms 913 and 922 thereof opposed to ~ach other. An insulating adhesive 840 (Fig. 10) is -Eirstly painted extremely thinly on the major surface 92a on which the electroae film 922 of the resonating ,~:
.. ~ . . . . .. .. .
source substrate 92 is formed. The -two resonating units source substrat~s 91 and 92 are affixed together in this way.
An electrically conductive adhesive 830 (Fig. 10) is painted on one end surface of the combined resonating units, in the middle portion of which the electrode films 91~ and 922 are disposed. The electrically conductive adhesive 830 soaks between the electrode films 913 and 922, whieh are opposed, so that an electrode eonnecting portion ~30a is formed, and hence the electrode films 91~ and 922 are electrically connected.
The thus affixed resonating unit source substrates are cut along line 1 indicated by arrows 95 in Fig. 9. As a result, a plurality of piezoeleetrie resonators, one of which is shown in Fig. 10, are obtained. It will be readily understood that the piezoelectric resonator as shown in Fig. 10 has substantially the same strueture as the piezoelectric resonator shown in Figs. 8A and 8B. In Fig. 10, the same portions as in Fig. 9 are indieated by correspondin~ primed reference numerals.
In the above-described embodiment, two resonating unit source substrates are affixed by using an inæulating adhesive. However, instead ~hereof, an electrically eonduetive adhesive may be employ~d. In sueh a ~ase, only the portion of the eleetrode films 91~ and 922 are affixed to each other. The electric conductive adhesive is painted thinly only on the surfaee 922a of the eleetrode film 922 and, thereafter, the two resonating unit source sub~trates 91 and 92 are combined. Aecordingly, the electrode films 913 and 922 are affixed so that substantially a single electrode is formed.
In the piezoelectrie resonator shown in FigO 10, the T~ vibration is excited in each of the resonating units 11 and 12. For example, in the resonating unit 12, the TS
vi~ration is exeited in the opposed portion o the electrodes 922' and 923' shown by the reference charaeter ~r ~
~ 2~
L in figure and the energy i5 trapped in the longitudinal direction of the substrate 92'. Accordinglyr if and when the length of the substrate 9Z' is made extremely large, for example, more than twenty times as compared with the thic]~ness thereof, neither of the end surfaces o~ -the substrate 92' vibrates. The same applies to the substrate 91'. Hence, it is possible to provide input and output leads in the end portions of electrodes 912' and 923l and a common lead in the common electrode portion 830 by means of solder~ electrically conductive adhesive, or the like so that the element as shown in Fig. 8A is obtained.
In the above-described embodiment, in order to obtain a desired elect~ical characteristic, the shape or configuration of the resonating unit source substrates 91 and 92 and the arrangement of the electrode films on the source substrates may be adequately changed.
Figs. 11 and 12 show electrical characteristics of the piezoelectric resonator of a preferred embodiment ~f the present invention as shown in Figs. 8A, 8B and 10.
Fig. 11 is a plot of admi~tance versus frequency 20 wherein the abscissa axis indicates a fre~uency in ~Hz and the ordina-~e axis indicates a~mittance. In thi.s igure, an S mode curve shows variation of an admittance between a connecting lead (no~ shown) provided for connecting an input lead 87 and an output lead 88 to each other and a common lead 86 in Fig. 8A when an a]ternating current of high frequency of 3 to 6 MHz is applied therebetween. An A mode indicates variation of an a~littance between the input lead 87 and the output lead 8~ when nothing is connected to the common lead 86 and an alternating current of high frequency of 3 to 6 M~z is applied therebetween. As seen fr~m Fig. 11, by chanqing the connecting manner of three terminals of the piezoelectric resonator in Fig. 8A two vibration responses can be obtained.
The two resonating frequencies in these vibration responses are slightly offset. Accordingly, it can be understood that 7~5~
the piezoelectric resonator ~orms a dual mod~ piezoelectric resonator as a conventional energy trapping type dual mode piezoelectric resonator stated above.
Fiq. 12 shows a characteristic of attenuation with respect to a frequency when a piezoelectric resonator shown in Fig. 8A is used as a filter. In Fig. 12, the abscissa axis indicates frequency (MHz) and the ordinate axis represents an attenuation (dB). As readily understood ~rom Fig. 12, the spurious response in the frequency reqion 13 o~ 0 to 10 MHz of the piezoelectric resonator is about 37 or 38 dB. This corresponds to the ~requency characteristic of the conventional TS vibration mode piezoelectric resonator with a two-stage structure as described in the oregoing. Thus, a single structure piezoelectric resonator in accordance with the present invention has per~ormance corresponding to a conventional two-stage structured piezoelectric resonator. Accordingly, an insertion loss of the present piezoelectric resonator is about a half of that o~ a conventional piezoelectric resonator, which means a great improvement.
The dimensions of the piezoelectric resonator shown in Fiqs~ 8A and 8B are such that the width is 0.8 mm, the height is 5.0 ~m and the thickness is 0.5 mm. Accordingly, the sur~ace area thereo~ is 4.0 ~Tl2~ On the other hand, the size of a conventional TE vibration mode piezoelectric resonator as shown in Figs. lA and 2 and having the same resonating frequencyas the resonator of the invention is such that the width is 9.0 mm, the height is 6.0 mm and the thickness 0.5 mm and hence the surface area is 54.0 mm2, In addition, the size o~ the conventional TS vibration mode piezoelectric resonat~x hauing the same resonating ~requency is such that the width is 3.0 ~mJ the height is 6.5 mm and the thickness is 0.23 mm and hence the sur~ace area is 19.5 mm . Thus, the piezoelectric resonator in accordance with the present invention can be made substantially smaller in size.
, . . . ... .. . . . .... . . . . . . . . . . . . .
7~
In addition, since the piezoelectric resonator embodying the present invention is of such structure -that two resonating substrates are affixed to each other, the ~hickness is thick as cornpared with a conventional piezoelectric resonator, particularly, a piezoelectric resonator of a TS vibration mode, and thus, the mechanical strength is enhanced and the mechanical reliability can be improved.
An electric characteristic of a piezoelectric resonator shown in Fig. 10 can be properly changed by properly selecting the opposed width L of the electrode ~ilms and a cut width W of a substrate. The opposed width L of the electrode Eilms can be easily changed by changing a printing pattern in forming the electrode films and the cut width W can be simply changed by initial adjustment of ~he cutting when the affixed resonating unit source substrate is cut. Accordingly, as compared with a con~entional piezoelectric resonator, the design of the piezoelectric resonator embodying the present invention can be easily changed so that desired electrical characteristicsJ such as passband width, maximum attenuation and insertion loss, are obtained. Particularly, it is easy to change the passband width.
Fi~. 13 shows c~nother preEerred embodiment of the piezoelectric resonator embodying the present invention.
The significant feature of the piezoelectric resona-tor shown in Fig. 13 resides in that the above described piezoelectric resonator is made to be a two-stage structured piezoelectric resonator. A gap 133 is formed in the two-stage structured piezoelectric resonator so that a firstresonating element 131 and a second resonating element 132 can independently operate. The gap 133 can be easily formed by using a stripe of conductive adhesive 134 having an appropriate width and thickness and extending perpendicular to the paper so as to adhere the first resonating element 131 to the second resonating element 13Z.
, -~;~07854 In manufacturing the piezoelectric xesonator 13 as shown in Fig. 13, many produc-ts can be simply made by fixing together the resonating unit source substrates and thereafter cuttinq them, which is similar to the manufacturing method explained in the foregoing referring to Figs. 9 and 10.
Since the Fig. 13 piezoelectric resonator is of a two-stage structure, the insertion loss thereof is the same as the above described conventional two-stage structured piezoelectric resonator. However, the spurious characteristic in the frequencY region of 0 to 10 MHz is greatly improved. Accordingly, such Fig. 13 piezoelectric resonator can be used solely as an SIF filter of a television signal.
lS Furthermore, the piezoelectric resonator in accordance with the present invention has the followiny advantages.
More particularly, conventionally, a piezoelectric resonator for an FM detection circuit is generally of a single-stage structure and a piezoelectric resonator for a filter is of a two-stage structure. Thus different size of piezoelectric resonator has been used for various usage in the past and, therefore, standardization of devices has never been achieved and an easy assembly has not been made by an automatlc assembly machine. As described above, the ~5 piezoelectric resonator of a single-stage in accordance with the present invention has the same characteristic as a conventional two-stage struc~ured piezoelectric resonator.
Therefore, it becomes possible to use the same size of piezoelectric resonator for various kinds of usage and standardi~ation of devices can be achieved. As a result, an easy assembly is made possible by means of an automatic assembly ma~hine, with a consequent decrease in the cost of manufacturing.
Although the present invention has been described and illustrated in detail, it is to be understood that the same is by way of illustration and example only and is not ~2~'7~54 to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.
..... ...
Claims (15)
1. A piezoelectric resonator comprising:
a first resonating single mode thickness expansion vibration unit including:
a first substrate comprised of a piezoelectric material and having two major surfaces;
a first common electrode disposed on one major surface of said first substrate; and a first electrode disposed on the other major surface of said first substrate, said first electrode being at least partially opposed to said first common electrode through said first substrate;
a second single mode thickness expansion vibration resonating unit including:
a second substrate comprised of a piezoelectric material and having two major surfaces;
a second common electrode disposed on one major surface of said second substrate; and a second electrode disposed on the other major surface of the second substrate, said second electrode being at least partially opposed to said second common electrode through said second substrate; and arraying means for arraying and fixing said first and second resonating units so that said first and second common electrodes are opposed to each other and said first and second common electrodes are electrically connected at at least one portion thereof so that a third electrode is formed whereby the piezoelectric resonator resonates in a dual mode thickness expansion vibration.
a first resonating single mode thickness expansion vibration unit including:
a first substrate comprised of a piezoelectric material and having two major surfaces;
a first common electrode disposed on one major surface of said first substrate; and a first electrode disposed on the other major surface of said first substrate, said first electrode being at least partially opposed to said first common electrode through said first substrate;
a second single mode thickness expansion vibration resonating unit including:
a second substrate comprised of a piezoelectric material and having two major surfaces;
a second common electrode disposed on one major surface of said second substrate; and a second electrode disposed on the other major surface of the second substrate, said second electrode being at least partially opposed to said second common electrode through said second substrate; and arraying means for arraying and fixing said first and second resonating units so that said first and second common electrodes are opposed to each other and said first and second common electrodes are electrically connected at at least one portion thereof so that a third electrode is formed whereby the piezoelectric resonator resonates in a dual mode thickness expansion vibration.
2. A piezoelectric resonator in accordance with Claim 1, wherein said arraying means includes fixing means for mechanically fixing said first and second resonating units so that said first common electrode and said second common electrode are opposed to each other; and electrical connection means for at least partially and electrically connecting said opposed first and second common electrodes, so that said third electrode is formed.
3. A piezoelectric resonator in accordance with Claim 2, wherein said fixing means includes an insulating adhesive being sandwiched between said first and second resonating units for mechanically connecting these units.
4. A piezoelectric resonator in accordance with Claim 2, wherein said electrical connection means includes an electrically conductive adhesive commonly painted on said first and second common electrodes for electrically connecting these electrodes.
5. A piezoelectric resonator in accordance with Claim 2, wherein said fixing means includes an insulating adhesive being sandwiched between said first and second resonating units for mechanically connecting these units, and said electrical connection means includes an electrically conductive adhesive commonly painted on the end portions-to-be-affixed of said first and second common electrodes so that the adhesive soaks between said first and second units, so that said first and second common electrodes are electrically connected.
6. A piezoelectric resonator in accordance with Claim 1, wherein said arraying means includes an electrically conductive adhesive being sandwiched between said first and second common electrodes for mechanically and electrically connecting these electrodes.
7. A piezoelectric resonator in accordance with Claim 1, wherein said piezoelectric resonator comprises a piezoelectric resonator of an energy trapping type.
8. A piezoelectric resonator in accordance with Claim 1, wherein said piezoelectric material comprises a ceramic.
9. A multi-stage structured piezoelectric resonator, including a plurality of piezoelectric resonator stages, each stage comprising:
a first single mode thickness expansion vibration resonating unit including:
a first substrate comprised of a piezoelectric material and having two major surfaces;
a first common electrode disposed on one major surface of said first substrate; and a first electrode disposed on the other major surface of said first substrate, said first electrode being at least partially opposed to said first common electrode through said first substrate;
a second single mode thickness expansion vibration resonating unit including:
a second substrate comprised of a piezoelectric material and having two major surfaces;
a second common electrode disposed on one major surface of said second substrate; and a second electrode disposed on the other major surface of the second substrate, said second electrode being at least partially opposed to said second common electrode through said first substrate;
a second single mode thickness expansion vibrating resonating unit including:
a second substrate comprised of a piezoelectric material and having two major surfaces;
a second common electrode disposed on one major surface of said second substrate: and a second electrode disposed on the other major surface of the second substrate, said second electrode being at least partially opposed to said second common electrode through said second substrate; and arraying means for arraying and fixing said first and second resonating units so that said first and second common electrodes are opposed to each other and said first and second common electrodes are electrically connected at at least one portion thereof so that a third electrode is formed whereby the piezoelectric resonator resonates in a dual mode thickness expansion vibration.
a first single mode thickness expansion vibration resonating unit including:
a first substrate comprised of a piezoelectric material and having two major surfaces;
a first common electrode disposed on one major surface of said first substrate; and a first electrode disposed on the other major surface of said first substrate, said first electrode being at least partially opposed to said first common electrode through said first substrate;
a second single mode thickness expansion vibration resonating unit including:
a second substrate comprised of a piezoelectric material and having two major surfaces;
a second common electrode disposed on one major surface of said second substrate; and a second electrode disposed on the other major surface of the second substrate, said second electrode being at least partially opposed to said second common electrode through said first substrate;
a second single mode thickness expansion vibrating resonating unit including:
a second substrate comprised of a piezoelectric material and having two major surfaces;
a second common electrode disposed on one major surface of said second substrate: and a second electrode disposed on the other major surface of the second substrate, said second electrode being at least partially opposed to said second common electrode through said second substrate; and arraying means for arraying and fixing said first and second resonating units so that said first and second common electrodes are opposed to each other and said first and second common electrodes are electrically connected at at least one portion thereof so that a third electrode is formed whereby the piezoelectric resonator resonates in a dual mode thickness expansion vibration.
10. A piezoelectric resonator in accordance with Claim 9, which further comprises fixing means for fixing said portion of each stage in such a manner that the portions are arrayed and stacked with gap.
11. A piezoelectric resonator in accordance with Claim 10, wherein said fixing means includes coupling means being sandwiched between said second electrode in the former portion out of continuous stages in said multi-stages and said first electrode in the latter portion out of said continuous stages for mechanically and electrically coupling these electrodes.
12. A piezoelectric resonator in accordance with Claim 11, wherein said coupling means includes an electrically conductive adhesive having a suitable thickness.
13. A piezoelectric resonator in accordance with Claim 10, wherein said third electrode is provided commonly to all the stages.
14. A piezoelectric resonator comprising:
a first substrate comprised of a piezoelectric material and having two major surfaces;
a second substrate comprised of a piezoelectric material and having two major surfaces, one major surface of said second substrate being opposed to one major surface of said first substrate;
a first electrode disposed on the other major surface of said first substrate;
a second electrode disposed on the other major surface of said second substrate; and a third electrode commonly disposed on said one major surface of said first substrate and said one major surface of said second substrate, said third electrode being at least partially opposed to said first electrode through said first substrate and being at least partially opposed to said second electrode through said second substrate whereby the piezoelectric resonator resonates in dual mode thickness expansion vibration.
a first substrate comprised of a piezoelectric material and having two major surfaces;
a second substrate comprised of a piezoelectric material and having two major surfaces, one major surface of said second substrate being opposed to one major surface of said first substrate;
a first electrode disposed on the other major surface of said first substrate;
a second electrode disposed on the other major surface of said second substrate; and a third electrode commonly disposed on said one major surface of said first substrate and said one major surface of said second substrate, said third electrode being at least partially opposed to said first electrode through said first substrate and being at least partially opposed to said second electrode through said second substrate whereby the piezoelectric resonator resonates in dual mode thickness expansion vibration.
15. A multi-stage structured piezoelectric resonator wherein a portion of each stage of said multi-stages comprises:
a first substrate comprised of a piezoelectric material and having two major surfaces;
a second substrate comprised of a piezoelectric material and having two major surfaces, one major surface of said second substrate being opposed to one major surface of said first substrate;
a first electrode disposed on the other major surface of said first substrate;
a second electrode disposed on the other major surface of said second substrate; and a third electrode commonly disposed on said one major surface of said first substrate and said one major surface of said second substrate, said third electrode being at least partially opposed to said first electrode through said first substrate and being at least partially opposed to said second electrode through said second substrate whereby the piezoelectric resonator resonates in dual mode thickness expansion vibration.
a first substrate comprised of a piezoelectric material and having two major surfaces;
a second substrate comprised of a piezoelectric material and having two major surfaces, one major surface of said second substrate being opposed to one major surface of said first substrate;
a first electrode disposed on the other major surface of said first substrate;
a second electrode disposed on the other major surface of said second substrate; and a third electrode commonly disposed on said one major surface of said first substrate and said one major surface of said second substrate, said third electrode being at least partially opposed to said first electrode through said first substrate and being at least partially opposed to said second electrode through said second substrate whereby the piezoelectric resonator resonates in dual mode thickness expansion vibration.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP230731/1982 | 1982-12-22 | ||
| JP23073182A JPS59115609A (en) | 1982-12-22 | 1982-12-22 | Piezoelectric filter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1207854A true CA1207854A (en) | 1986-07-15 |
Family
ID=16912413
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000443948A Expired CA1207854A (en) | 1982-12-22 | 1983-12-21 | Piezoelectric resonator |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS59115609A (en) |
| CA (1) | CA1207854A (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS621422U (en) * | 1985-06-17 | 1987-01-07 | ||
| JPH0199310A (en) * | 1987-10-12 | 1989-04-18 | Murata Mfg Co Ltd | Electrostriction effect element |
| JPH0253315A (en) * | 1988-08-18 | 1990-02-22 | Murata Mfg Co Ltd | Piezoelectric filter |
| JP2924909B2 (en) * | 1989-09-20 | 1999-07-26 | 株式会社村田製作所 | Piezoelectric oscillator |
| JPH114133A (en) * | 1997-06-12 | 1999-01-06 | Murata Mfg Co Ltd | Thickness vertical piezoelectric resonator |
| JP3695615B2 (en) * | 1997-06-12 | 2005-09-14 | 株式会社村田製作所 | Energy-confined thickness longitudinal piezoelectric resonator |
-
1982
- 1982-12-22 JP JP23073182A patent/JPS59115609A/en active Granted
-
1983
- 1983-12-21 CA CA000443948A patent/CA1207854A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59115609A (en) | 1984-07-04 |
| JPH0149050B2 (en) | 1989-10-23 |
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