Piezoelectric resonator

[Detailed Description of the Invention]

[Industrial Application] The present invention relates to the improvement using Shooting by a piezo-electric horizontal effect like spread vibration of a piezo-electric resonance device, and relates to what was equipped with the structure which controls spurious one based on especially thickness vibration. [Description of the Prior Art] Conventionally, the kHz belt filter and oscillation child using spread vibration of electrostrictive ceramics, such as a lead-zirconate-titanate system, are used widely. As this kind of a piezoelectric resonator, what formed the electrode in both sides of electrostrictive ceramics, the laminated type thing on which the piezo-electric ceramic layer was laminated via the internal electrode, etc. exist. [The technical issue which an invention tends to solve] However, in the impedance frequency characteristic of this kind of piezo-electric resonance device, as shown in Drawing 2, response B based on a comparatively big thickness vibration arises besides beak A based on spread vibration. That is, when spread vibration was used, thickness vibration was induced unescapable and it had become spurious [ with a big response level based on this thickness vibration ]. It is in order to enlarge the output of a piezo-electric resonance device in a use like an ultrasonic sensor, It is piezoelectric constant d by enlarging piezoelectric constant d for that purpose, making dielectric constant c0 small, however changing composition with a piezo-electric material, although piezo-electric power coefficient g8. may be enlarged! When 2 is enlarged, dielectric constant tsx also becomes large at -m. Therefore, it is difficult by changing composition to enlarge piezo-electric power coefficient g0. Therefore, the object of the present invention is to provide the piezo-electric resonance device provided with the structure where spurious one based on thickness vibration can be reduced effectively, and a big electric power output can be realized in a use like an ultrasonic sensor, when using vibration by a horizontal effect like spread vibration. [The means for solving a technical subject] The present invention is characterized by that a piezo-electric resonance device using vibration based on a horizontal effect like the spread mode of vibration comprises: A sintered compact which has at least two-layer piezo-electric ceramic layer which is arranged so that a thickness direction may be overlapped, and from which a rate of a stoma differs, An electrode provided in the surface of this sintered compact. At least two-layer piezo-electric ceramic layer which is arranged so that a thickness direction may be overlapped and from which the rate of a stoma differs can be constituted by making which [ one or more ] piezo-electric ceramic layer into a porous layer. In order to form this porous layer, the substance which may disperse when sintering carbon, an organic binder, etc. in a piezo-electric ceramic green sheet before sintering may be added, and may be calcinated. As a layer with a high rate of a stoma, it is among the piezo-electric ceramic layers from which the rate of a stoma differs so that clearly from the following examples, It is preferred to form the layer which has a rate of a stoma of 5~10%, and to constitute the remaining piezo-electric ceramic layers from a precise usual sintered compact layer, The effect of reducing the spurious level based on [ in the rate of a stoma of a piezo-electric ceramic layer with a big rate of a stoma ] thickness vibration at 5% or less is not enough, It is because degradation of electrical properties, such as specific inductive capacity, a frequency constant, and an electromechanical coupling coefficient of spread vibration, becomes large gradually, so it is not desirable in the thing exceeding 10%. [Function] In the present invention, in order to use the sintered compact which has at least two-layer piezo-electric ceramic layer from which the rate of a stoma differs, thickness vibration is effectively dumped by the piezo-electric ceramic layer with a big rate of a stoma. Therefore, it becomes possible to reduce the spurious level based on thickness vibration effectively. [Example] Drawing 1 is a sectional view of the piezo-electric resonance device of one example of the present invention. In Drawing 1, piezo-electric ceramic J12~4 is IIJI(ed) by the thickness direction in sintered compact l. Here, central piezo-electric ceramic layer 3 comprises a porous layer which has a stoma of the path which is 1O-100micrometer, and piezo-electric ceramic layer 2.4 of both sides comprises a precise piezo-electric ceramic sintered compact layer. And the poling process of the sintered compact 1 whole is carried out in the direction which intersects perpendicularly with a thickness direction. 5 and 6 show the electrode for a drive. In this example, since it has piezo-electric ceramic layer 3 from which the rate of a stoma differs so that clearly from the following concrete explanation, when spread vibration is used, it is supposed that it is possible to reduce effectively the spurious level based on a thickness longitudinal oscillation. This example is described in detail, referring to the manufacturing process of 1st [ The ] figure example. First, the 1st piezo-electric ceramic green sheet of two or more sheets is prepared with the usual doctor blade method. On the other hand, similarly the 2nd piezo-electric ceramic green sheet is prepared with a doctor blade method using the slurry produced by mixing organic matter powder (what may disperse in the calcination temperature of a ceramic sintered compact) insoluble in an isovolumic solvent in the end of piezo-electric ceramic powder. the [ above-mentioned ] -- it calcinated, after superimposing the 1. 2nd ceramic green sheet so that it might become desired thickness and press-fitting it, as shown in Drawing 3, and the sintered compact was obtained. In Drawing 3, the green sheet shown with reference number 7.8 is the 1st ceramic green sheet, and the ceramic green sheet shown with reference number 9 is the 2nd ceramic green sheet. The poling process of the sintered compact produced by performing it above was carried out, and the piezo-electric resonance device which formed the electrode in both sides after an appropriate time, and was shown in Drawing 1 was obtained. it was shown in Drawing 3 -- as -- the 1st ceramic green sheet 7.7 ... and the 2nd ceramic green sheet 9 and 9 ... and the 1st ceramic green sheet 8 and 8 -- if the laminating device shown, for example in Drawing 4 is used when laminating ..., it can laminate continuously. As shown in Of course and Drawing 4, at least 1 side of roller 11*12 is rotated in the state where it pressed to the other side so that roller 11*12 which rotates in the direction of arrow X of illustration may be made to approach relatively. between such rollers 11 and 12 -- the -- if it supplies like illustration of the 1. 2nd ceramic green sheet 7~9 (although ceramic green sheet 7~9 of one sheet is illustrated in Drawing 4 in order to make illustration easy) The green sheet of the number according to lamination number of sheets is supplied between rollers 11 and 12 in fact. It is pressurized with rollers 11 and 12 and lamination sheet 13 can be obtained. the -- although it is necessary to fabricate and dry beforehand the 1. 2nd ceramic green sheet 7~9 to a sheet shaped This with desirable applying water to a sheet surface beforehand, when sticking by pressure and laminating between rollers 11 and 12 is a thing of water solubility [ binder / which is contained in a ceramic green sheet ]. Therefore, it is because press-fit will become easy if water is applied to the surface. As mentioned above, the press-fit To can obtain easily the layered product which laminated the sheet of a heterogeneous material by extrusion molding using roller 11.12 shown in Drawing 4. But it is in order to form the piezo-electric ceramic layer from which the rate of a stoma by the piezo-electric resonance device of the present invention differs, the [ which does not necessarily need to use the laminating device of Drawing 4 / of the rectangle beforehand cut by the predetermined size as shown in Drawing 3 ] -- the 1. 2nd ceramic green sheet 7~9 is laminated up and down, and it is stuck by pressure with arbitrary pressurizers from the upper and lower sides, and by it, a forming object may be acquired and the forming object may be sintered. Next, it explains per concrete experimental result of 1st [ The ] figure example. Lamination number of sheets T of ceramic Green See's 7 and 8.9 each laminated in Drawing 3. T, T', and of -- it was considered as T and -T' among them, T/T was changed, and various piezo-electric resonance devices were obtained. Thus, the impedance frequency characteristic at the time of changing the ratio to the lamination number of sheets of the 1st ceramic green sheet 7 or 8 of the 11-layer number of sheets of the 2nd ceramic green sheet 9 was investigated. A result is shown in Drawing 5. Drawing 5 shows San-ya ratio 20 Xj!og[(impedance value in impedance value / resonance frequency in anti-resonance frequency)] of the spread vibration at the time of fluctuating T/T, and thickness vibration. Although it spreads compared with the time (equivalent to a conventional example) of T, being 0 as T, increases and the response of vibration does not change so much so that clearly from Drawing 5, it turns out that it decreases rapidly as Th increases the San-ya ratio based on a thickness longitudinal oscillation. Therefore, when the lamination number of sheets of the 2nd ceramic green sheet 9 for forming a porous layer in Drawing 3 is made to increase, it turns out that it can reduce spurious one based on thickness vibration. But it is Th /so that clearly from Drawing 5. When T- exceeds 0.5, the spurious reduction effect based on thickness vibration becomes close to the saturation point. On the other hand, the San-ya ratio of spread vibration takes both into consideration, in order to fall a little as T and /T, increases, and it is considered that it is preferred that they are T/T, and 0.5 or less Is. Change of specific inductive capacity e and piezo-electric power coefficient g0 which receives the lamination ratio of Drawing 3, i.e., T/T, in the example of Drawing 1 is shown in Drawing 7. In this example, it turns out that the value of piezo-electric power coefficient g, becomes more than twice the usual (1-0) piezo-electric resonance device which does not contain a porous layer so that clearly from Drawing 7. Therefore, it becomes possible to constitute a highly efficient pressure sensor, an ultrasonic microphone, etc. Although piezo-electric ceramic layer 3 with a high rate of a stoma was formed in the center in 1st [ The ] figure example, Even if it uses the sintered compact by which the piezo-electric ceramic layer with a high rate of a stoma of two or more was laminated on the inside, and a sintered compact which are different in Drawing 1 and by which the both sides of the precise piezo-electric ceramic layer were equipped with the piezo-electric ceramic layer with a high rate of a stoma, it can reduce spurious one based on a thickness longitudinal oscillation similarly. These constructional examples are shown in Drawings 8 and 9. In the example shown in Drawing 8, porous piezo-electric ceramic layer 25.26 with a high rate of a stoma is laminated between precise piezo-electric ceramic layers 22 and 23.24 in sintered compact 21. 27.28 shows an electrode. In sintered compact 31 shown in Drawing 9, precise piezo-electric ceramic layer 32 is formed in the center of a thickness direction, and piezo-electric high ceramic layer 33.34 is laminated on the both sides relatively [ the rate of a stoma ]. 35.36 shows an electrode. the [ which all mentioned above sintered compact 21.31 shown in Drawings 8 and 9 ] -- it is obtained by choosing the number of sheets, laminating and sintering the 1. 2nd ceramic green sheet so that it may become the thickness shown in Drawings 8 and 9. Drawing 10 is a figure showing the relation of the San-ya ratio of thickness *i Motion of an example and Tl/Ta which were shown in Drawings 8 and 9. With the structure of 1, 'rb/T, Is, and Drawing 8, it is equivalent to the thickness of porous piezo-electric ceramic layer 25 or 26 with a high rate of a stoma, and equivalent to the thickness of T and precise piezo-electric ceramic layer 21 of Is the center. Similarly, in the structure of Drawing 9, T, is equivalent to the thickness of piezo-electric ceramics N33.34 with a high rate of a stoma of both sides, and T, is equivalent to the thickness of precise piezo-electric ceramic Ji32 of a center. The San-ya ratio of a thickness longitudinal oscillation is Tb/so that clearly from Drawing 10, since porous piezo-electric ceramic layer 25.26 or 33.34 was used also in each example shown in Drawings 8 and 9. It turns out that it decreases rapidly along with the increase in T-. Below, it explains per concrete example of an experiment. On Hisashi Takeshi 4% of the weight, 3 % of the weight, glycerin, and 10 % of the weight of water (pure water) was mixed as a plasticizer, and the methyl cellulose binder was kneaded with 3 rolls in the end of lead-zirconate-titanate system piezo-electricity ceramic powder. After an appropriate time, with a vacuum extrusion device, carried out extrusion formation of the 1st 0.2-m green sheet, and it was made to dry with a film drier, and rolled round on the roll. The binder of next of the same kind in the end of the same lead-zirconate-titanate system piezo-electricity ceramic powder, and an equivalent amount, After adding glycerin and water, insoluble cellulose was mixed 3% of the weight, it kneaded with 3 rolls, extrusion molding of the 2nd green sheet of 0*2 countries of thickness was carried out like the 1st green sheet after an appropriate time, and it rolled round on the roll. the [ which was produced by performing it above ] -- between rolls 11.12 of the laminating device mentioned above, the 1. 2nd green sheet was press-fitted and laminated, and the lamination sheet was obtained. When laminating, water was beforehand applied to the surface of each green sheet. Between rolls 11*12, as the pressure of lQkg/cj was added, both ceramic green sheets were press-fitted. The obtained lamination green sheet was pierced to 30 Kakugaku, was stored to Box of alumina, and was calcinated at the temperature of 1160 degreeC for 2 hours. The silver paste was applied to the surface of the obtained sintered compact, and it printed at the temperature of 800 degreeC for 0.5 hour, and formed the electrode. After giving polarization by the direct-current electric field of 3 kV / - and Dying-izing by 150'C for 0.5 hour, the impedance frequency characteristic was measured. As a result, the impedance frequency characteristic shown in Drawing 6 was acquired. The impedance value in anti-resonance frequency fell to 115 compared with the conventional thing, and the resonance impedance value became about 10 times conversely. Therefore, it turns out that dumping of a thickness longitudinal oscillation is performed effectively. Major cusp After mixing 3 % of the weight of glycerin, and 100 weight of water as a plasticizer and kneading a methyl cellulose binder 4% of the weight, extrusion molding of the sheet of 0.3am was carried out with the vacuum extrusion machine, and it wound around the dried post-roll in the end of lead-zirconate-titanate system piezo-electricity ceramic powder. On the other hand, fixed weight kneading of the cellulose of insoluble in water nature was carried out, and it was made five-fold methyl cellulose lid % solution with sheet adhesives. Insoluble in water cellulose was mixed in order to form a layer with a high rate of a stoma into a sintered compact. Two ceramic green sheets mentioned above were prepared, the above-mentioned sheet adhesives were applied to the surface of each sheet by squeegee printing etc., and the lamination sheet was obtained by being pressurized and stuck by pressure by IL/cd pressure using the pressurizing roller. The sintered compact which clips the obtained lamination sheet on a 30+m++ square, and it calcinates at the temperature of 1160 degreeC for 2 hours using alumina type Reason and by which the porous layer of 20~3otIm thickness was formed in the center by thickness 500 mum was obtained. The silver paste was applied on the surface of the sintered compact, and it printed for 30 minutes at the temperature of 760 degreeC, and formed the electrode. Next, after carrying out the poling process to the thickness direction for 30 minutes and Dying-izing for 30 minutes by 150 degreeC by the direct-current electric field of 3 kV / big building, the characteristic of spread vibration and thickness vibration was measured. As a result, the result shown in Drawing (a) (d) 11 ~ was obtained. When the rate of a stoma of a portion with a high rate of a stoma constituted using Of course and sheet adhesives becomes 5~10%, it turns out that the spurious level based on a thickness longitudinal oscillation becomes below in OdB, and the level of spread vibration can also maintain the range which does not fall so much. When the rate of a stoma of a porous piezo-electric ceramic layer is 5% or less, Moreover the spurious level of a thickness longitudinal oscillation serves as a positive value (refer to Drawing 11 (a)), characteristic degradation of specific inductive capacity, a frequency constant, an electromechanical coupling coefficient (spread vibration), etc. becomes large, and a required thing is no longer obtained at 10% or more of case. Therefore, as for the rate of a stoma of a porous piezo-electric ceramic layer, it is preferred that it is 5~10%. Effect] of [invention As mentioned above, it is since the piezo-electric resonance device is constituted using the sintered compact on which the piezo-electric ceramic layer from which the rate of a stoma differs was laminated in the present invention, When using the vibration based on a piezo-electric horizontal effect like spread vibration, it becomes possible to reduce effectively spurious one based on the thickness longitudinal oscillation ordered unescapable. Piezo-electric power coefficient g. Also -- since it can raise effectively, it becomes possible to obtain a highly efficient ultrasonic microphone, a pressure sensor, etc.

[Brief Description of the Drawings]

It is a figure in which Drawing 1 shows the sectional view of one example of the present invention, and Drawing 2 shows the impedance frequency characteristic of a conventional example, Drawing 3 is a perspective view showing the ceramic green sheet used for constituting 1st [ The ] figure example, Drawing 4 is a schematic illustration side view showing the laminating device for laminating a ceramic green sheet, The figure showing change of the San-ya ratio of spread vibration when Drawing 5 changes the lamination number-of-sheets ratio of the 2nd ceramic green sheet, and thickness vibration, the figure in which Drawing 6 shows the impedance frequency characteristic of Example 1, and Drawing 7 are piezo-electric power coefficient gzs, and T/T. Drawings 9 are a figure showing a relation, a sectional view showing the example of everything [ Drawing / 8 ] but the present invention, and a sectional view showing the example of further others of the present invention, The figure showing the San-ya ratio of a thickness longitudinal oscillation and the relation of T b /T, to Drawing 8 and 9th [ The ] figure example and Drawing (a) (d) 11 ~ are each figure showing the characteristic of Example 2. [ Drawing / 10 ] In a figure, the piezo-electric ceramic layer in which 1 and 21.31 are precise as for a sintered compact and 2,422.23.24, a piezo-electric ceramic layer with porous 3*25.26.32, 5.6, 27.28, and 35.36 show an electrode. Drawing 1 Drawing 2 The number of Tomokoshi Drawing 4 Drawing 6 Zone Po Number Drawing 5 Tb /Ta Drawing 7 theta rho, 5 7b/Ta Drawing 9 the --O [ 1 ] figure theta, 5 It gives and is /lower a.