CN1268861A

CN1268861A - Piezo-electric element and piezo-electric type acoustic device, and mfg. method therefor

Info

Publication number: CN1268861A
Application number: CN00105206A
Authority: CN
Inventors: 柿沼博美; 金井康弘; 高桥宪司
Original assignee: Taiyo Yuden Co Ltd
Current assignee: Taiyo Yuden Co Ltd
Priority date: 1999-03-29
Filing date: 2000-03-29
Publication date: 2000-10-04
Also published as: KR20000063055A; KR100676030B1; JP2000350293A

Abstract

The invention relates to a piezoelectric vibrator and a piezoelectric sound device which can generate a more natural sound by enabling even a small-diameter piezoelectric vibrator to increase the low-frequency side sound pressure level. The piezoelectric vibrator has a couple of piezoelectric ceramic plates polarized in the thickness direction and inside electrodes and outside electrodes formed of conductor films formed on both surfaces of the piezoelectric ceramic plates respectively. The inside electrodes each on one side of each of the piezoelectric ceramic plates are laminated or stuck together in a mutually electrically conductive state while the polarizing directions of the piezoelectric ceramic plates are made opposite, and the outside electrodes are electrically connected to each other. This piezoelectric vibrator has its peripheral part fixed to the peripheral wall of a case main body with an elastic adhesive and thus built in the case main body.

Description

Piezoelectric element and piezoelectric type acoustical device and manufacture method thereof

The present invention relates to a kind of piezoelectric element and use the piezoelectric type acoustical device of this piezoelectric element, they are used for portable phone, or the other-end device, and are used for respectively having the small size loud speaker and the receiver of a discoidal main body.More particularly, the present invention relates to at two blocks of polarized plate shaped piezoelectric ceramic of the thickness direction of this piezoelectric element stacked or a kind of piezoelectric element that is pasted together and the piezoelectric type acoustical device that uses this piezoelectric element, and manufacture method.

A piezoelectric element is installed or settled to a kind of piezoelectric type acoustical device that uses in portable phone or so-called cordless telephone in a disc-shaped body of its housing.A disc partition of this piezoelectric element, be to make by thin metallic plate (for example, brass, phosphor bronze etc.) material, on end face of this metallic plate or two end faces, pasting 70% the piezoelectric element (or a plurality of piezoelectric element) that diameter is approximately this separator material diameter.In this piezoelectric element, on two surfaces of piezoelectric ceramic thin plate, form two electrodes making by metallic film; One of them electrode is connected with this partition, can go up conducting with this partition is electric.

Along with the progress of portable phone miniaturization, the size of piezoelectric type acoustical device also will reduce, and at present, mainly uses diameter to be approximately the piezoelectric type acoustical device of the small shell of 20mm.In this undersized piezoelectric type acoustical device, the size that is placed on piezoelectric element wherein also must reduce certainly.Therefore, the diameter of the piezoelectric element that uses at present is equal to or less than 20mm.

In this piezoelectric type acoustical device, if the diameter of piezoelectric element is little, the sound pressure height that produces at high band then, and the sound pressure that produces in low-frequency range is low.As a result, have only the high high-pitched tone of frequency to be enhanced, thereby produce the factitious sound or sound.

In addition, usually in order to suppress to produce high-pitched tone, the various methods that are used to increase or increase the sound pressure of low pitch section have been proposed.As a kind of method in these methods, be to use extremely thin metal forming as partition.Yet when using this extremely thin metal forming as partition, the processing of this metal forming is difficulty very, also can bring the pretty troublesome problem of manufacture process of this metal forming.Therefore, the attenuate of this metal foil thickness size is restricted.

Consider the problem of the piezoelectric type acoustical device of above-mentioned common technology, an object of the present invention is to provide a kind of sound pressure can improve low pitch the time, thereby can produce the sound of nature or the piezoelectric element and the piezoelectric type acoustical device of sound.

According to the present invention, in order to achieve the above object, adopted one stacked or bond together by two blocks of plate shaped piezoelectric ceramic, but do not use the metallic plate partition, and the circumferential section of piezoelectric element is bearing in the piezoelectric element on the end face part of circumference wall of a housing by elastic adhesive.

When electrode two ends add signal voltage, these piezoelectric element 18 vibrations, and sound.According to the present invention, this piezoelectric element comprise pair of plates shape, at the polarized piezoelectric ceramic of its thickness direction; And each all is each internal electrode and each outer electrode that forms on two surfaces of each piece piezoelectric ceramic 16 and 17, made by conductive film.These two blocks of piezoelectric ceramic are in the opposite direction polarized each other, and the polarised direction that makes a piezoelectric ceramic is for pointing to internal electrode from this outer electrode; The polarised direction of another piece piezoelectric ceramic then is from this internal electrode directed outwards electrode, and lip-deep these two internal electrodes that are respectively formed at each piezoelectric ceramic link together, and makes their electricly mutually go up conducting; Also conducting each other of outer electrode simultaneously.

In addition, according to the present invention, in above-mentioned piezoelectric element, lead material, for example, and conductor leading, with each internal electrode of this two blocks of piezoelectric ceramic of mutual conducting, and each outer electrode connects; And,, signal voltage is added between each internal electrode and each outer electrode of piezoelectric element by these lead-in wires.

Work as lead material, for example conductor leading when being connected with each internal electrode, on a piezoelectric ceramic, being made one and is cut part.Thereby, these two blocks of piezoelectric ceramic connect or the state that is pasted together under, make the internal electrode of another piece piezoelectric ceramic cut part and expose by this.Cutting the internal electrode that partly exposes by this on lead-in wire and the piezoelectric ceramic is connected.

Each outer electrode of each piezoelectric ceramic is connected to each other; But this connection is to use conductor, rather than uses each outer electrode itself to realize.On the other hand, outer electrode can center on each piezoelectric ceramic, goes to the inside of this piezoelectric ceramic; This goes back to next part, can bond together, and makes their electric mutual conductings, as each internal electrode.

In addition, the internal electrode of at least one block of piezoelectric ceramic also can go to this piezoelectric ceramic outside around piezoelectric ceramic, and lead-in wire is connected with the part that this turns over.Like this, can make the above-mentioned part that cuts, get final product so that lead-in wire is connected with internal electrode.

This piezoelectric element is installed in the housing.This piezoelectric element is by a kind of elastic adhesive, and its circumferential section is bonded on the end face part of circumference wall of this housing.In this case, the circumferential section of this piezoelectric element, the best elastic adhesive of the circumference wall inside by stretching into this housing is bearing on the end face part of circumference wall of this housing.

Because the partition that this piezoelectric element is not made by metallic plate, so size can do very for a short time, thereby can easily obtain undersized piezoelectric type acoustical device.In addition, because the circumferential section of this piezoelectric element is the elastic adhesive by the circumference wall inside of stretching into this housing, be bearing on the end face part of circumference wall of this housing; Therefore, when making this piezoelectric type acoustical device, can not cause piezoelectric ceramic for example to crack the damage of a class; It is the productivity ratio height.In addition, because this piezoelectric element vibrates easily, the amplitude of vibration increases gradually, therefore can obtain high acoustic pressure.

The piezoelectric ceramic that can adopt a kind of parallel double piezo crystals chip is as piezoelectric element.At this moment, two blocks of plate shaped piezoelectric ceramic are stacked together, but do not have partition (shimmaterial) between two blocks of piezoelectric ceramic.For example, can use a kind of piezoelectric ceramic, in the middle of the two, put into internal electrode, the piezoelectric element that outer electrode then forms on the main body outer surface of these two blocks of piezoelectric ceramic in the above with following stacked.This piezoelectric element also can be stacked together with three layers or more multi-layered piezoelectric ceramic, and put into internal electrode between these piezoceramics layers; Or make this piezoelectric ceramic, and bonding or stacked together by internal electrode, form like this.

The circumferential section of piezoelectric element, this circumferential section not with the circumference wall state of contact of housing under, be bearing on the end face part of circumference wall of this housing, form a piezoelectric type acoustical device.The circumferential section of piezoelectric element is by elastic adhesive, under the state that the circumference wall of this circumferential section and housing separates, is bonded on the end face part of circumference wall of this housing.In this case, can use the elastic adhesive that contains spheric granules, replace above-mentioned elastic adhesive.

Like this, chip, that do not have partition and be contained in piezoelectric element in the above-mentioned housing by using the parallel double piezo crystals, can not hinder because the expansion and the contractile motion of the piezoelectric element that the influence of the circumference wall of housing causes.Because when adding driving voltage, this piezoelectric element can be on one's own initiative expands in the whole zone of the thickness of piezoelectric element and radial direction and shrinks, and therefore, this piezoelectric element can carry out bending effectively or make bending motion greatly with displacement.In addition, the whole thickness of this piezoelectric element is done thin, and kept the effective driving diameter of this piezoelectric element bigger, can reduce the eigentone of piezoelectric element.Therefore,, also can increase the sound pressure of low segment, produce the sound of nature even use the less piezoelectric type acoustical device of diameter.

In addition, the stepped construction of using piezoelectric ceramic is easy to do the thickness of piezoelectric element very thin as piezoelectric element parallel bimorph formula, that do not use partition.By using the stepped construction of piezoelectric ceramic, can also guarantee bonding fully between the piezoelectric ceramic; Simultaneously, need between each piezoelectric ceramic, not carry out bondingly after the roasting, therefore, can high production rate obtain the piezoelectric element 18 of parallel double piezo crystals chip.

In addition, all include the connection or the sticking structure of the stacked body of many groups piezoelectric ceramic of two blocks of piezoelectric ceramic, can obtain having many piezoelectric ceramic by using each group, and the accurate or meticulous piezoelectric element 18 of the parallel double piezo crystals chip of electrode; Therefore, can provide a kind of high performance piezoelectric type acoustical device.

Not having the circumferential section of piezoelectric element 18 of the parallel double piezo crystals chip of partition, is under the state that the circumference wall with housing separates, and is undertaken bonding by elastic adhesive; Therefore, piezoelectric element can be done to expand and contractile motion in radial direction effectively, and can make bending motion at thickness direction, thereby displacement increases.In addition, when piezoelectric element, at the part place that its circumferential section is supported, the unnecessary skew or the motion of thickness direction are prevented from; Therefore, because the piezo-electric element displacement amount that the bending of piezoelectric element causes can be converted to the electric charge output variable effectively.

If the circumferential section of piezoelectric element by containing the elastic adhesive of spheric granules, under the state that the circumference wall of this circumferential section and housing separates, carries out bonding; Then spheric granules plays the effect of the spacer that the circumference wall with the circumferential section of piezoelectric element and housing separates.Like this, can support this piezoelectric element accurately at thickness direction, thereby can suppress the fluctuation of acoustic pressure.

If housing and Qi Gai, the boss of the excessive displacement of restricted piezoelectric element then can be protected this piezoelectric type sound generator on inner surface, not the damage that can cause because of the over-large displacement of the piezoelectric element that produces when piezoelectric element two ends add excessive voltage.

In addition, prevent the ribs that is out of shape if having on the inner surface of housing, then the rigidity of housing improves, and therefore, can protect when piezoelectric element, and housing is not twisted.Like this, can prevent the displacement that the piezoelectric element bending causes, the efficient that is converted to the electric charge output variable reduces, and therefore, can make the sound pressure characteristic of acoustical device much better.That this ribs also has is aforesaid, the effect of restriction piezoelectric element over-large displacement.

When considering the mobile phone that uses waterproof and/or the cordless telephone of family expenses etc., be preferably on the surface of this piezoelectric element, add a waterproof coating.Go to grip portable phone and/or home cordless phone with some wet hand or drenched hand sometimes, perhaps use them in very moist place, but when on the piezoelectric element waterproof coating being arranged, just can prevent through moisture and/or drenched etc., cause the performance of piezoelectric element to reduce.

This piezoelectric type acoustical device, available following manufacture method manufacturing.At first, prepare one and have internal diameter and equate with the external diameter of piezoelectric element or bigger circumference wall, and near the housing of the positioner of the positioner of the radial direction of this circumference wall and short transverse.Secondly, elastic adhesive is coated on the end face part of circumference wall of housing, and with above-mentioned piezoelectric element, is placed on the relative part of the end face part that scribbles elastic adhesive on the circumference wall with housing.When guiding the circumferential section of this piezoelectric element with the radial direction positioner, make the circumferential section of this piezoelectric element, contact with elastic adhesive on being coated in circumference wall end face, and be bonded on this bonding agent.Then, with this radial direction positioner, the part bonding with using elastic adhesive separated, or takes off from this part.

Utilize this manufacture method, by the positioner of this radial direction and the positioner of short transverse, can be with the circumferential section of the thin piezoelectric element that does not have partition that assembles, utilize elastic adhesive, be bonded on the end face part of circumference wall of this housing, and the circumferential section of piezoelectric element and the circumference wall of housing are separated.In addition, by elastic adhesive, the circumferential section of piezoelectric element is bonded on the end face part of circumference wall of housing after because separately or taken off the positioner of this radial direction, therefore, on housing, do not have barrier.

As mentioned above, owing to according to piezoelectric element of the present invention and the piezoelectric type acoustical device that uses this piezoelectric element, used piezoelectric element, piezoelectric element and piezoelectric type acoustical device that therefore easily manufacturing dimension is little without the partition of metal plate-like.In addition, because it is little to obtain size, and the good piezoelectric type acoustical device of frequency-sound pressure characteristic, therefore, can further reduce undersized portable communications terminal, for example, the size of portable phone etc.

Fig. 1 is the decomposition diagram of an example of expression a kind of piezoelectric type acoustical device according to an embodiment of the invention;

Fig. 2 is installed in above-mentioned piezoelectric type acoustical device for expression the vertical cross-section diagram of the state on the housing of a communication terminal device;

Fig. 3 A and 3B are used to represent to be installed in state on the housing of communication terminal device, at the cross-sectional view of the amplification of the major part of the above-mentioned piezoelectric type acoustical device at the opposite side place with it of a side that connects with lead-in wire;

Fig. 4 be used to represent this piezoelectric element is bonding or stick on process on the housing of this piezoelectric type acoustical device, the cross-sectional view of the amplification of the major part of anchor clamps;

Fig. 5 is the perspective view of expression according to the decomposition of another example of piezoelectric type acoustical device of the present invention;

Fig. 6 is for being installed under the state on the housing of a communication terminal device vertical cross-section diagram of the amplification of the major part of above-mentioned piezoelectric type acoustical device at above-mentioned piezoelectric type acoustical device;

Fig. 7 is illustrated in according to piezoelectric type acoustical device of the present invention, and the state on the housing of a communication terminal device of being installed in is measured down, the figure of the relation of audio frequency and sound pressure;

Fig. 8 is used to represent that the piezoelectric type acoustical device is installed in state on the housing of this communication terminal device, with the cross-sectional view of the amplification of the major part that is connected the opposite piezoelectric type acoustical device side place, according to another embodiment of the invention of a side with lead-in wire;

Fig. 9 is installed in state on the housing of this communication terminal device for expression piezoelectric type acoustical device, with be connected the opposite side place of a side, the cross-sectional view of the amplification of the major part of piezoelectric type acoustical device according to still another embodiment of the invention with lead-in wire;

Figure 10 A and 10B be installed in for the above-mentioned piezoelectric type acoustical device of expression state on the housing of this communication terminal device, be connected a side and an opposite side place thereof, the cross-sectional view of the amplification of the major part of above-mentioned piezoelectric type acoustical device according to still another embodiment of the invention with lead-in wire;

Figure 11 for expression piezoelectric type acoustical device be installed in state on this communication terminal device case, at the cross-sectional view of the amplification of the major part that is connected the piezoelectric type acoustical device side place, according to still a further embodiment with lead-in wire;

Figure 12 is installed in for expression piezoelectric type acoustical device on the housing of communication terminal device, the amplification cross-sectional view of the major part of piezoelectric type acoustical device according to still a further embodiment, but saved the part of this piezoelectric type acoustical device major part;

Figure 13 A and 13B are the A-A among Figure 12, the view of the major part shown in the B-B line upward arrow;

Figure 14 is the piezoelectric ceramic that is illustrated in another example of employed piezoelectric element in the piezoelectric type acoustical device according to an embodiment of the invention, the decomposition diagram before oven dry;

Figure 15 is the vertical cross-section diagram with the above-mentioned piezoelectric element after the piezoelectric ceramic oven dry stacked together;

Figure 16 is the piezoelectric ceramic that is illustrated in another example of employed piezoelectric element in the piezoelectric type acoustical device according to an embodiment of the invention, the decomposition diagram before oven dry;

Figure 17 A and 17B are the vertical cross-section diagram with the above-mentioned piezoelectric element after the piezoelectric ceramic oven dry stacked together;

Figure 18 is the vertical cross-section diagram that is illustrated in another example of employed piezoelectric element in the piezoelectric type acoustical device according to an embodiment of the invention;

Figure 19 is the vertical cross-section diagram that is illustrated in another example of employed piezoelectric element in the piezoelectric type acoustical device according to an embodiment of the invention;

Figure 20 A and 20B are the polarized and vertical cross-section diagram just in use of another example, particularly this piezoelectric element that is illustrated in employed piezoelectric element in the piezoelectric type acoustical device according to an embodiment of the invention;

Figure 21 be a housing and in piezoelectric type acoustical device according to an embodiment of the invention the decomposition diagram of employed piezoelectric element;

Figure 22 be this housing and in piezoelectric type acoustical device according to an embodiment of the invention the plane graph of employed piezoelectric element;

Figure 23 A～23C is installed in piezoelectric element for expression the part vertical cross-section diagram of the process in the above-mentioned housing;

Figure 24 is illustrated in to finish piezoelectric element to be installed under the state in the above-mentioned housing part vertical cross-section diagram of this piezoelectric type acoustical device;

Figure 25 is the plane graph of the piezoelectric type acoustical device under finishing the state that piezoelectric element is installed in the above-mentioned housing;

Figure 26 A and 26B support the vertical cross-section diagram of the state of this piezoelectric element circumferential section for representing when piezoelectric element being installed in the above-mentioned housing;

Figure 27 is at piezoelectric type acoustical device according to the present invention, the audio frequency that the state on the communication terminal device case that is installed in is measured down and the figure of the relation between the sound pressure;

Figure 28 is under finishing the state that piezoelectric element is installed in the housing, the vertical cross-section diagram of another example of completed piezoelectric type acoustical device;

Figure 29 be a housing and in piezoelectric type acoustical device according to an embodiment of the invention the decomposition diagram of another example of employed piezoelectric element;

Figure 30 is the plane graph of another example of employed housing in piezoelectric type acoustical device according to an embodiment of the invention;

Figure 31 is the plane graph of another example of employed housing in piezoelectric type acoustical device according to an embodiment of the invention;

Figure 32 is the plane graph of another example of employed housing in piezoelectric type acoustical device according to an embodiment of the invention;

Figure 33 is the plane graph of another example of employed housing in piezoelectric type acoustical device according to an embodiment of the invention; With

Figure 34 is the major part of above-mentioned housing, especially for the circle wall face portion of location and the cross-sectional view of the amplification of jut.

Below, will come with reference to the accompanying drawings in detail and specifically describe embodiments of the invention.

Fig. 1～Fig. 3 represents an example of piezoelectric type acoustical device according to an embodiment of the invention; Particularly Fig. 2 has represented that this piezoelectric type acoustical device is installed in a state on the communication terminal device case.

Referring now to Fig. 1 and Fig. 2, the component part of this piezoelectric type acoustical device is described.This piezoelectric type acoustical device comprises a housing 11, a piezoelectric element 18 that is installed in this housing 11, with the lead-in wire 22a and the 22b (see figure 2) that are connected on two electrodes with piezoelectric element 18 are electric.

Piezoelectric element 18 is with two blocks of plate shaped piezoelectric ceramic 16 and 17, utilizes stickups such as bonding agent or bonds together and make.Each piece piezoelectric ceramic 16 and 17 be shaped as disc, its diameter is 15mm, thickness is 0.1mm; On two main surfaces of these two blocks of piezoelectric ceramic, form electrode 19b respectively, 20b, 19a and 20a.The electrode that forms on a side of two blocks of piezoelectric ceramic 16 and 17 is

internal electrode

19b and 20b; And the electrode that forms on its opposite side is outer electrode 19a and 20a.These two blocks of piezoelectric ceramic 16 and 17 polarized direction are opposite each other.That is: when the polarized direction of piezoelectric ceramic 16 when electrode 19b is to outer electrode 19a internally, then the polarized direction of piezoelectric ceramic 17 is to internal electrode 20b from outer electrode 20a.

On the part of the circumference of a piezoelectric ceramic 16, a part that cuts 23 is arranged.Specific to the embodiment shown in Fig. 1～Fig. 3 B, this cuts part 23 and is similar to and uses straight line, the circumference of piezoelectric ceramic 16 is cut a part forms.

These two blocks of piezoelectric ceramic 16 and 17 stack by welding or adhesive linkage, make the electric each other upward conducting of one of them internal electrode 19b and another internal electrode 20b;

Outer electrode

19a and 20a are then on two side surfaces respect to one another.Under this condition, the part of the internal electrode 20b of a piezoelectric ceramic 17 is exposed outside from the above-mentioned part 23 that cuts.

Shown in Fig. 3 B, two blocks of piezoelectric ceramic 16 and 17 corresponding

outer electrode

19a and 20a by by the conductor 25 that uses solder or electrocondution slurry to form, electricly each other go up connection; And corresponding

internal electrode

19b and 20b, then with above-mentioned conductor 25 insulation.Again as shown in Figure 3A, lead-in wire 22a is connected with the outer electrode 19a of piezoelectric ceramic 16; And from the above-mentioned internal electrode 20b that cuts the piezoelectric ceramic 17 that part 23 exposes, then be connected with lead-in wire 22b.Article two, lead-in

wire

22a and 22b made by the lead that is covered with insulating barrier, and they utilize welding or the bonding agent by conduction etc. respectively, with the outer electrode 19a of above-mentioned piezoelectric ceramic 16, are connected with the internal electrode 20b of piezoelectric ceramic 17.

Be used to place and support the housing 11 of above-mentioned piezoelectric element 18, make round plate shape, and a space is arranged in circumference wall 13 inside.The internal diameter of circumference wall 13, preferably with piezoelectric ceramic 16 that constitutes above-mentioned

piezoelectric element

18 and 17 equal diameters, or a little more greatly.

At the center of the antetheca 12 that is surrounded by the circumference wall 13 of housing 11, do to have an acoustic emission hole 15 of playing the damper effect.This launch hole 15 is a through hole just, yet the inner face in acoustic emission hole 15 can adhere to one deck and be waited the damping cloth made etc. by the Tetron net, and the opening portion in this hole is covered.For example, use diameter to be approximately under the situation of piezoelectric element 18 of 15～20mm, can make a diameter at the center of the front face of housing 11 and be approximately the acoustic emission hole 15 of 1-2mm, and can on this hole, adhere to the damping cloth that the Tetron net that is approximately #380 is made.

This housing 11, for example, the usable resins injection molding process is made.This housing 11 has the function of echo box, therefore, the shape of housing, the thickness of its wall and the acoustic emission hole 15 with this damper effect should be designed to produce optimal echo effect.

As shown in Figures 2 and 3, on the end face of the circumference wall 13 of housing 11, scribble the elastic adhesive 24 of silicon system etc.During coating adhesive 24, this bonding agent is extended in the circumference wall 13 of this housing 11.Circumferential section with above-mentioned piezoelectric element 18, glued or be bonded on the inner circumferential part of circumference wall 13 that extends to this housing 11 with interior bonding agent, thereby, be bearing on the bonding agent on circumference wall 13 end faces of this housing 11 circumferential section of this piezoelectric element 18.In addition, the end of lead-in

wire

22a and 22b extends in the outside of this housing 11.

Fig. 4 represents to utilize bonding agent, adopts above-mentioned method, with the circumferential section of piezoelectric element 18, is bonded in the anchor clamps on the end face of circumference wall 13 of this housing 11.As shown in Figure 4, these anchor clamps have a part placing plate 71 and a housing placing plate 72.By a pin 76 is inserted in the pin-and-hole 77, this part placing plate and housing placing plate can be stacked, make to keep predetermined relation between them.

On the upper surface of this part placing plate 71, the coating of making by such as fluoroplastic polymer etc. is arranged, can make this part placing plate have character with model separation.On a predetermined position of the upper surface of this part placing plate, make a part placement part 74 of the negative area of line as shown in FIG.; Piezoelectric element 18 can be put into, and remains in this part placement part.On the other hand, above-mentioned housing placing plate 72, with above-mentioned part placement part 74 corresponding lower surfaces on, the housing placement part 75 of making a recessed shape; Housing 11 can be put into, and remains in this housing placement part.

At first, piezoelectric element 18 is put into part placement part 74 on the above-mentioned part placing plate 71.Then, with the method for silk screen printing, coating silicon is elastic adhesive 24 etc., is got up in the marginal portion of this piezoelectric element 18 and the outer side covers of above-mentioned part placement part 74.On the other hand, housing 11 is put into the housing placement part 75 of this housing placing plate 72, the opening portion that makes housing 11 is towards the outside.Then, make this housing placement part 75 more down, part placing plate 71 and housing placing plate 72 are gathered into folds, simultaneously pin 76 is inserted in the pin-and-hole 77.Make this two plate location.In this state, compressor heats this part placing plate 71 and housing placing plate 72, makes above-mentioned elastic adhesive sclerosis.Then, this part placing plate 71 and housing placing plate 72 are separated,, take out the housing placement part 75 from this housing placing plate 72 piezoelectric element 18 bonding superincumbent housings 11.Like this, just finished the installation of piezoelectric element 18 in this housing 11.

Though, in Fig. 4, only represented one group of housing 11 and piezoelectric element 18, yet, in anchor clamps, many above-mentioned part placement parts 74 and housing placement part 75 can be set with part placing plate 71 and housing placing plate 72; Therefore, can simultaneously many housings 11 and piezoelectric element 18 be bonded together.

Piezoelectric type acoustical device and for example shown in Figure 2, as to be assembled in this way is installed in a sound on the housing 61 of portable communications terminal by on the part 62.Fig. 2 has represented that the sound on this housing 61 passes through part 62.By in the part 62, doing has a plurality of little sound to pass through the hole at illustrated this sound.

At first, with an a kind of surface (for example, the double-sided adhesive band of annular etc.) of adhesives 64, the sound that is bonded at the housing 61 of this communication terminal device passes through on the periphery of part 62, makes this adhesives surround the sound of this housing 61 by part 62.In addition,, be bonded on the circumferential section in above-mentioned acoustic emission hole 15, make this adhesive material 64 be enclosed in acoustic emission hole 15 that make, that damping action is arranged on the front face 12 of above-mentioned housing 11 with damping action with another gluing of surfaces of above-mentioned adhesives 64.Like this, piezoelectric element 18 be at it under the state of the inside of communication terminal device case 61, be fixed on this housing 61; That is: the front face 12 of the housing 11 of piezoelectric element, towards the sound of above-mentioned housing 61 by part 62.In this state, lead-in wire 22a and the 22b that is connected with 20b with the outer electrode 19a of piezoelectric element 18 and 20a and internal electrode 19b respectively, then welded together with the circuit that is located on the printed circuit board (PCB) in the above-mentioned communication terminal device case 61, that do not illustrate among the figure.

From the signal voltage that is formed at the electronic circuit on the printed circuit board (PCB), be added in the internal electrode 19b and the 20b of piezoelectric element by above-mentioned lead-in

wire

22a and 22b, and between outer electrode 19a and the 20a, then constitute the piezoelectric ceramic 16 and 17 vibrations of this piezoelectric element 18, sound.

Fig. 5 and Fig. 6 represent an example of piezoelectric type acoustical device according to another embodiment of the invention.This embodiment is different with the foregoing description, particularly on the piezoelectric ceramic cut part 23 ' the shape difference.In the above-described embodiments, cut the form that part 23 is the straight lines on the circumferential section of a piezoelectric ceramic 16; And in Fig. 5 and embodiment shown in Figure 6, cutting part 23 ' be from the circumferential section of this piezoelectric ceramic 16, inwardly incision becomes " U " font to form.In addition, in this case, the internal electrode 20b on another piece piezoelectric ceramic 17 is under two blocks of piezoelectric ceramic 16 and 17 states that bond together by being connected to each other of

internal electrode

19b and 20b, from the above-mentioned part 23 ' to exposing outside of cutting.Lead-in wire 22b, with from above-mentioned cut part 23 ' internal electrode 20b on this piezoelectric ceramic 17 that exposes outside be connected.The structure of other structures and Fig. 1～embodiment illustrated in fig. 3 is identical.

Fig. 7 is illustrated in the audio frequency measured on the piezoelectric type acoustical device that uses piezoelectric element 18 and the relational graph between the sound pressure.This piezoelectric element 18 is to be 15mm with diameter, and thickness is that two blocks of piezoelectric ceramic 16 and 17 of 0.1mm bond together and make; And piezoelectric element 18 is installed in the above-mentioned housing 11; As shown in Figure 1.11 of described housings are installed on the housing of communication terminal device, as shown in Figures 2 and 3.The sound of housing 61 that AC signal is added in two ends of this piezoelectric element 18 and an artificial ear (IEC 318) is attached to the communication terminal device is by on the part 62; Can measure the sound pressure (decibel) that is produced by this artificial ear.When measuring sound pressure, make the internal electrode 19b and the 20b that are added in piezoelectric element 18, and the frequency of the AC signal between outer electrode 19a and the 20a, in 0.1KHz～10KHz scope, change, can measure the characteristic between audio frequency and the sound pressure.

Can find out that from figure shown in Figure 7 use can produce similar stable and uniform sound according to the portable phone of piezoelectric type acoustical device of the present invention in the frequency band range of 0.3KHz～3KHz.

Piezoelectric type acoustical device according to Fig. 8 and embodiment shown in Figure 9 is described below.In example shown in Figure 8, the neighboring part of

outer electrode

19a and 20a, the periphery surface around piezoelectric ceramic 16 and 17 goes to this piezoelectric ceramic inside; And being connected simultaneously between the connection between two outer peripheral portion of this of outer electrode are divided and each internal electrode 19b and the 20b carried out.In addition, in example shown in Figure 9, the neighboring part of

outer electrode

19a and 20a is by making the

conductor

26 and 27 near the through hole piezoelectric ceramic 16 and 17 excircles, rather than, go to the inside of piezoelectric ceramic 16 and 17 by piezoelectric ceramic 16 and 17 circumferential surface.Structure except above-mentioned is identical with structure shown in Figure 8.

In piezoelectric type acoustical device, when the internal electrode 19b of piezoelectric element and 20b are bonded together, its

outer electrode

19a and 20a are coupled together according to these embodiment; Therefore, and utilize the conductor 25 shown in Fig. 3 B, the method that connects the outer electrode 19a of this piezoelectric element and 20a relatively, its manufacture method is much simple.

Piezoelectric type acoustical device according to the embodiment shown in Figure 10 A and the 10B is described below.In this example, the outer electrode 19a and the 20a of piezoelectric element by the

conductor

28 and 29 in the through hole of the perforation made, go to the inside of this piezoelectric ceramic 16 and 17 near piezoelectric ceramic 16 and 17 centers; And being connected simultaneously between the connection between these outer electrodes part and each internal electrode 19b of piezoelectric element and the 20b carried out.In addition, the internal electrode 19b of piezoelectric element and the neighboring part of 20b by the conductor in the through hole of making 26 and 27, go to the outside of these two blocks of piezoelectric ceramic 16 and 17 near the excircle of piezoelectric ceramic 16 and 17.

Shown in Figure 10 A, in this example, lead-in wire 22b, can with by the conductor 26 in the through hole, a part that goes to an internal electrode 19b of piezoelectric ceramic 16 outsides connects.Therefore, can use shape mutually the same, and its

internal electrode

19b and 20b, and all identical piezoelectric ceramic 16 and 17 of shape of each electrode among outer electrode 19a and the 20a.Like this, can generally use these parts, unnecessary center round two blocks of piezoelectric ceramic 16 and 17, the setting angle of adjusting piezoelectric ceramic, so production efficiency improves.

Yet, under the situation of this example, piezoelectric ceramic 16 and 17 corresponding

internal electrode

19b and 20b, the outside that can be not go to piezoelectric ceramic 16 and 17 by the conductor in the above-mentioned through

hole

26 and 27 is gone; But as shown in Figure 8,, go to the outside of piezoelectric ceramic round the circumferential surface of piezoelectric ceramic 16 and 17.

Piezoelectric type acoustical device according to embodiment shown in Figure 11 is described below.In this example, the neighboring part of the internal electrode 19b of a piezoelectric ceramic 16 by the circumferential surface of piezoelectric ceramic 16, goes to the outside of piezoelectric ceramic 16.In addition, in this example, can take and the identical mode of piezoelectric type acoustical device shown in Figure 10 A and the 10B, may realize at a certain position of a certain internal electrode 19b with being connected of lead-in wire 22b, at this position, its neighboring part goes to piezoelectric ceramic 16 outsides by the circumferential surface of piezoelectric ceramic 16.

Therefore, can use two blocks of mutually the same piezoelectric ceramic 16 of shape and 17.Yet, between piezoelectric ceramic 16 and 17 the corresponding

internal electrode

19b and 20b, and some difference are arranged each other between outer electrode 19a and the 20a.

Yet, under the situation of this example, the internal electrode 19b of piezoelectric ceramic 16, can be not circumferential surface by piezoelectric ceramic 16, but shown in Figure 10 A like that, by the conductor in the through hole, forward the outside of piezoelectric ceramic 16 to.

In addition, be connected with 17, can adopt following method for two blocks of piezoelectric ceramic 16.For example, utilize conductor 25, shown in Fig. 3 B such as film one class of solder or conductor; Perhaps utilize excircle, go to the internal electrode part of piezoelectric ceramic 16 and 17 outsides, piezoelectric ceramic 16 and 17 is linked together, as shown in Figure 8 by piezoelectric ceramic 16 and 17; Perhaps also can go to the outer electrode part that piezoelectric ceramic 16 and 17 inner faces go, piezoelectric ceramic 16 and 17 be linked together, as shown in Figure 9 by making the

conductor

26 and 27 near the through hole the excircle of piezoelectric ceramic 16 and 17.

The piezoelectric element of embodiment shown in Figure 13 A and the 13B and use the piezoelectric type acoustical device of this piezoelectric element is described below according to Figure 12.In this example, two blocks of piezoelectric ceramic 16 and 17 of piezoelectric element 18 link together, and form one, form

internal electrode

19b and 20b between two blocks of piezoelectric ceramic.In addition, the outer surface in piezoelectric ceramic 16 and 17 forms

outer electrode

19a and 20a respectively.Piezoelectric ceramic 16 and 17 can be made by the while roasting.

Shown in Figure 12 and Figure 13 A, the outer electrode 19a that forms on the outer surface of piezoelectric ceramic 16 is made by metallic film.This outer electrode 19a does on the whole outer surface except the excircle part of piezoelectric ceramic 16.In addition, on close a part of surface of its excircle of piezoelectric ceramic 16, form an outer electrode 19a ' who is used for soldering lead-in wire 22b.Yet this is used for the outer electrode 19a ' of soldering lead-in wire 22b, should the spaced-apart and insulation with above-mentioned outer electrode 19a.

The external electrode 20a that forms on the outer surface of another piece piezoelectric ceramic 17 is also made by metallic film.This outer electrode 20a does on the whole outer surface except its excircle part of piezoelectric ceramic 17.On the outer surface of piezoelectric ceramic 17, do not form the above-mentioned outer electrode that is used for the soldering lead-in wire.

And for example shown in Figure 12 and Figure 13 B, the internal electrode 19b and the 20b that form between piezoelectric ceramic 16 and 17 are made by conductor thin film.This two

internal electrode

19b and 20b do on piezoelectric ceramic 16 and 17 interconnected same aspects.An internal electrode 19b can cover the almost whole surface except its excircle part of these two blocks of piezoelectric ceramic 16 and 17.In this internal electrode 19b, there is one not with the part of conductor layer; Another internal electrode 20b promptly is formed in this part, and separates with internal electrode 19b and insulate.

On the surface of above-mentioned piezoelectric ceramic 16, form, be used for the outer electrode 19a ' of soldering lead-in wire, by run through conductor 26 in the through hole that piezoelectric ceramic 16 forms ', and the internal electrode 19b conducting between piezoelectric ceramic 16 and 17.In addition, another internal electrode 20b between piezoelectric ceramic 16 and 17, by the conductor in the through hole 27 ', with the outer electrode 20a conducting that on the surface of piezoelectric ceramic 17, forms.In addition, from another internal electrode 20b between piezoelectric ceramic 16 and 17,, form the through hole 30 of an opening to the outer surface of piezoelectric ceramic 16.

Under this condition, by respectively externally between electrode 19a and the 19a ', and externally between electrode 19a ' and the 20a; Or concentrated area making alive between electrode 19a and the 20a externally, can polarize to piezoelectric ceramic 16, make its polarised direction electrode 19b directed outwards electrode 19a internally; Simultaneously piezoelectric ceramic 17 is polarized, make its polarised direction point to internal electrode 20b from outer electrode 20a; Or opposite, polarized piezoelectric pottery 16 makes its polarised direction point to internal electrode 19b from outer electrode 19a; Simultaneously, polarized piezoelectric pottery 17 makes its polarised direction electrode 20b directed outwards electrode 20a internally.

Secondly, by soldering or electrically conducting adhesive, around the through hole 30 of the opening on the outer surface of piezoelectric ceramic 16,22a is connected with the outer electrode 19a of piezoelectric element with lead-in wire.Be used to connect go between solder or the electrically conducting adhesive of 22a, be full of this opening through hole 30 inside, make the outer electrode 19a on piezoelectric ceramic 16 outer surfaces, and the internal electrode 20b conducting between piezoelectric ceramic 16 and 17.As a result, the outer electrode 20a on outer electrode 19a on piezoelectric ceramic 16 outer surfaces and piezoelectric ceramic 17 outer surfaces, by solder or electrically conducting adhesive, the conductor 27 in internal electrode 20b and the through hole ', conducting mutually.In addition, the outer electrode 19a ' on piezoelectric ceramic 16 outer surfaces, by soldering or electrically conducting adhesive, 22b is connected to each other with lead-in wire.

The mounting structure of piezoelectric element 18 on housing 11 is identical with mounting structure in the piezoelectric type acoustical device shown in Figure 11 or the above each figure.

Figure 14 and Figure 15 represent another example of piezoelectric element 18.In this example, the piezoelectric element 18 of bimorph formula has two piezoceramics layers 16 and 17.Figure 14 is illustrated in before piezoelectric ceramic 16 and the 17 stacked and roastings, piezoelectric ceramic 16 and 17 and an example of arrangement of electrodes.In fact, piezoelectric element 18 is not to be piled up one by one or stacked by the unit of as shown in figure 14 single-piece, handles efficiently but concentrated by the unit of a component sheets of extending a large amount of piezoelectric elements on an in-plane.Yet in the accompanying drawings, for convenience of description, only represented a piezoelectric element 18.

As shown in figure 14, not having a piezoelectric ceramic 116 of roasting before stacked is a discoidal thin layer, on main surface, its top, utilizes electrocondution slurry to print an outer electrode 119a; And on main surface, its underpart, print an internal electrode 119b.In addition, when printing said external electrode 119a and internal electrode 119b, above-mentioned electrocondution slurry is full of the through hole inside that gets out or dig out in advance on piezoelectric ceramic 116, can

forms conductor

130a and 130b in the through hole like this.Conductor 130a and outer electrode 119a in through hole separate, with this outer electrode 119a insulation, and only with internal electrode 119b conducting.Equally, conductor 130b and internal electrode 119b in another through hole separate, with the insulation of this internal electrode, and only with outer electrode 119a conducting.

Not having another piece piezoelectric ceramic 117 of roasting before stacked, also is discoidal thin layer; On main surface, its top, print internal electrode 120b with electrocondution slurry; And on main surface, its underpart, print an outer electrode 120a, as shown in figure 14.In addition, when printing this outer electrode 120a and internal electrode 120b, electrocondution slurry is full of the through hole inside that gets out or dig out in advance on piezoelectric ceramic 117, form the conductor 131 in the through hole.Conductor 131 in this through hole separates with internal electrode 120b, with this internal electrode insulation, and only with outer electrode 120a conducting.

These do not have the piezoelectric ceramic 116 and 117 of roasting, and portion's

electrode

119b and 120b toward each other and under the condition by compression within it pile up or stacked together.Then, in roasting piezoelectric ceramic body stacked together,

outer electrode

119a and 120a, and

internal electrode

119b and 120b formed

outer electrode

19a and 20a respectively also by roasting, and

internal electrode

19b and 20b, as shown in figure 15.In this case,

internal electrode

19b and 20b become one.In addition, conductor 130b in the through hole on the piezoelectric ceramic 116 is with conductor 131 conductings in the through hole on the piezoelectric ceramic 117.Like this, conductor links together in these two through holes, forms the

conductor

30b and 31 in the through hole.

Then, as shown in figure 15, by soldering or electrically conducting adhesive, with lead-in wire respectively with the piezoelectric ceramic 16 of roasting on outer electrode 19a, and be connected with the weld zone part of conductor 30a in the through hole that this electrode separates.

Again respectively externally between electrode 19a and the internal electrode 19b, and between internal electrode 20b and outer electrode 20a, add direct voltage; Perhaps the concentrated area externally adds direct voltage between electrode 19a and the 20a, can make piezoelectric ceramic 16 and 17 polarized.When piezoelectric ceramic 16 and 17 when polarized, the polarised direction of piezoelectric ceramic 16 is electrode 19b directed outwards electrode 19a internally; And the polarised direction of piezoelectric ceramic 17 is from outer electrode 20a, points to internal electrode 20b; Perhaps, another kind of scheme is that piezoelectric ceramic 16 and 17 is by polarized with above-mentioned opposite polarised direction.

Then,, couple together, can on this weld zone part, pile up the bonding agent of solder 32 or conduction with outer electrode 20a on the lower surface of piezoelectric ceramic 17 for weld zone part with the conductor in the through hole 31.

Figure 16, the piezoelectric element 18 shown in Figure 17 A and the 17B is a kind of variations.It has a bit to change in the outer electrode 19a of piezoelectric ceramic 16 and 17 and the connection between the 20a with aspect the conductor structure that stretches out of internal electrode 19b and 20b.Outer electrode 20a on the outer electrode 19a on piezoelectric ceramic 16 upper surfaces and the lower surface of piezoelectric ceramic 17 by running through near the via

conductors

30b and 31 piezoelectric ceramic 16 and 17 centers, is connected to each other.In addition, by the conductor 30a near the through hole of making the conductor 30b in the through hole that runs through piezoelectric ceramic 16, can make the lead-in wire with piezoelectric ceramic 16 lower surfaces on internal electrode 19b and the extension of the internal electrode 20b on piezoelectric ceramic 17 upper surfaces couple together.Other structures except said structure are identical with the structure of Figure 14 and piezoelectric element 18 shown in Figure 15.In the drawings, identical label is represented identical part or structure.

Figure 17 A represents the state of polarized piezoelectric element 18.Shown in the figure solid line, add direct voltage, just can make piezoelectric ceramic 16 and 17 polarization respectively.Figure 17 B is illustrated in after the polarization, the connection situation under service condition.At this moment available solder 32 or connect by electrically conducting adhesive, and the part of piezoelectric element is connected with drive circuit.

Piezoelectric element 18 shown in Figure 180 is a kind of variations.

Internal electrode

19b and 20b extend to the part of the upper surface of piezoelectric ceramic 16, are being used for and the position that is connected of lead-in wire, have same with Figure 14 and piezoelectric element 18 shown in Figure 15.That is: for the connection that goes between, the extending part that

internal electrode

19b and 20b forward to by via conductors 30a on the upper surface of piezoelectric ceramic 16 is positioned near the excircle of piezoelectric ceramic 16.In addition structure, identical with the structure of Figure 14 and piezoelectric element 18 shown in Figure 15, same, in the drawings, identical label is represented identical part or structure.

Piezoelectric element 18 shown in Figure 19 also is a kind of variations.It and piezoelectric element shown in Figure 180 18 relatively just connect the solder 32 or the electrically conducting adhesive of usefulness between two blocks of piezoelectric ceramic 16 and 17 outer electrode 19a and the 20a, moved on on the upper surface of piezoelectric ceramic 16.In addition structure is identical with the structure of piezoelectric element 18 shown in Figure 180.Among the figure, identical label is also represented identical part or structure.

Figure 20 A and 20B represent, each duplexer all is two duplexers that the

piezoceramics layer

16 and 17 by two so-called bimorph formulas constitutes, the back-to-back stacked or structure that bonds together.Internal electrode 19c and 20c in the middle of this duplexer are conductor 33a and the 33b in the through hole of piezoelectric ceramic two sides that passes two piezoceramics layer 16a and 16b or 17a and 17b by each, lead on the surface of piezoelectric ceramic 16a and 17a; Simultaneously, lip-deep outer electrode 19a of this internal electrode 19c and 20c and piezoelectric ceramic 16a and 17a and 20a separate.In addition,

internal electrode

19b and 20b in the above-mentioned internal electrode 19c and the 20c outside are to connect three piezoceramics layer 16a by each, 16b and 17b, or piezoelectric ceramic 16a, conductor 34a and 34b in the through hole of 17a and 17b lead on the surface of piezoelectric ceramic 16a and 17a; Simultaneously, lip-deep outer electrode 19a and the 20a of this

internal electrode

19b and 20b and piezoelectric ceramic 16a and 17a separate, toward each other.In addition, internal electrode 20b by conductor 35b in the through hole, leads on the surface of piezoelectric ceramic 17a; Separate with the lip-deep outer electrode 20a of piezoelectric ceramic 17a simultaneously.

Figure 20 A is illustrated under the polarized state, the connection of piezoelectric element 18.Under the condition that respective electrode connects as shown in phantom in FIG. like that, shown in solid line, add direct voltage like that, can be to piezoelectric ceramic 16a, 16b, each the piece piezoelectric ceramic among 17a and the 17b polarizes.After Figure 20 B is illustrated in polarization, under the state of use, the connection of piezoelectric element 18.Connection realizes by solder or electrically conducting adhesive 32, and the part of piezoelectric element is connected with drive circuit.

Figure 21 represents above-mentioned piezoelectric element 18 and lays the perspective view of its housing 11 that Figure 22 is the plane graph of expression housing 11.

Housing 11 is a disc, from its circumferential section rib shape circumference wall 13 of a circle on end.The internal diameter of circumference wall 13 is more slightly bigger than the diameter of piezoelectric element 18.From three positions of circumference wall 13 inner peripherys,, stretch out three locating convex blocks 41 towards the center of circumference wall 13.These three projections are triangularity in the plane.In the center of this circumference wall 13,, get out or dig out an acoustic emission hole 15 in the bottom of housing.

In three locating convex blocks 41 on the circumference wall 13 of above-mentioned housing 11, the position from wherein two projections outside vertically erects two guides 42 that are used in the radial direction location.These two guides 42 all are columns, and each guide sees it all is pentagonal in the plane, and its inboard top of protruding flushes with the inner periphery of circumference wall 13.

On the side of the circumference wall 13 of housing 11, there is a trapezoidal terminal connection part to divide 51 to highlight.In the center of this coupling part upper surface, founding the dividing plate 44 of a wall shape; In two sides of this dividing plate, the terminal that erects column connects projection 43.

A lid is arranged on this housing 11, and this will be described below.

Illustrate referring now to Figure 23 A～23C and to utilize this housing 11 and above-mentioned piezoelectric element 18, the process of piezoelectric type acoustical device is installed.

At first, shown in Figure 23 A, the inboard along the circumference wall 13 of housing 11 applies or smears elastic adhesive 24, for example, and silicon bonding agent etc.

Then, shown in Figure 23 A that above-mentioned piezoelectric element 18 is staggered relatively with this housing 11, and be placed in the housing 11.In this case, the circumference of piezoelectric element 18 contacts with the inside projection of the guide 42 of above-mentioned column.This guide 42 has two, when piezoelectric element 18 is installed, the piezoelectric element circumference is pressed on the projection of these two guides 42.Like this, the location of piezoelectric element 18 can be regulated, and the circumferential section of this piezoelectric element 18, the inner surface inner face of the circumference wall 13 of housing 11 can be just in time be placed in radial direction.

In this way, under the circumference of piezoelectric element 18 and condition that the inside projection of column guide 42 contacts, along this guide 42, push away this piezoelectric element 18 downwards, piezoelectric element 18 is moved downward, and a part that reaches its circumference is almost run into the position of the locating convex block 41 on the inner periphery of the circumference wall 13 that is located at this housing 11.Like this, piezoelectric element 18 is subjected to the restriction or the constraint of this locating convex block 41 and stops in short transverse; Simultaneously, the circumferential section of piezoelectric element 18 contacts with elastic adhesive 24.Therefore, the circumferential section of this piezoelectric element 18 by elastic adhesive 24, bonds together with the circumference wall 13 of housing 11.In this state, the circumferential section of piezoelectric element 18 is located on the locating convex block 41 of three positions on this circumferential section; And the circumferential section of piezoelectric element 18 is positioned at the inside of the circumference wall 13 of this housing 11, by these elastic adhesive 24 supportings.Simultaneously, the circumference wall 13 of the circumferential section of piezoelectric element 18 and housing 11 separates very a little bit smaller distance.

Then, shown in Figure 23 C,, fracture from its base portion office, and take off from housing 11 with above-mentioned guide 42.

Figure 24 and Figure 25 represent that this piezoelectric type acoustical device has been made and finish.The terminal connection part that two terminals 45 are connected housing 11 divides on 51, and lid 46 is placed on the outside of circumference wall 13 of housing 11.

These two terminals 45 utilize above-mentioned terminal to connect projection 43, are fixed on terminal connection part and divide on 51; And with the heating burned (thermal burn-in) method fix.The lead-in wire of piezoelectric element 18 also under this condition, is connected with these two terminals.

In addition, lid 46 is placed in the outside of the circumference wall 13 of housing 11, and by the little anaerobic adhesive of viscosity etc., is adhesively fixed with the outside of this circumference wall 13.On the upper surface of illustrated lid 46, have hole 47.

Figure 26 A and 26B represent the circumferential section of piezoelectric element 18, by elastic adhesive 24, are bearing in the state on the circumference wall 13 of housing 11.As can be seen from the figure, the circumferential section of piezoelectric element 18 is bonded on the elastic adhesive 24 on the circumference wall 13 that is coated in housing 11; And the circumference wall 13 of the circumferential section of piezoelectric element and housing 11 separates.In this state, owing to there is not the circumferential section of the piezoelectric element 18 of above-mentioned separator material (shim material), can not limited securely by the circumference wall 13 of housing 11; Therefore, this piezoelectric element is to a certain degree can free vibration.Like this, in the frequency band that reality is used, do as a wholely, can improve sound pressure.

Figure 26 A represents that circumferential section utilizes elastic adhesive, and for example, silicon bonding agent etc. is bearing in the piezoelectric element 18 on the circumference wall 13 of housing 11.In contrast, Figure 26 B represent the circumferential section utilization wherein contain the bonding agent 24 that average diameter is 50～1000 microns a spheric granules ', be bearing in the piezoelectric element 18 on the circumference wall 13 of housing 11.This spheric granules, for example, can be by metallic particles, ceramic particle or resin particle etc. is made.This particle is preferably accurate sphere, or accurate polygon, to play spacer.Like this, can support this piezoelectric element accurately at the thickness direction of piezoelectric element, thereby can suppress the dispersion and the fluctuation of acoustic pressure.

Figure 27 is illustrated in and uses by as Figure 14 and piezoelectric element 18 shown in Figure 15, that be made of as two blocks of piezoelectric ceramic 16 and 17 duplexers that are laminated together to form of 15mm above-mentioned diameter; And be installed in the audio frequency measured on the piezoelectric type acoustical device in the above-mentioned housing 11 and the figure of the relation between the sound pressure.Add AC signal at piezoelectric element 18 two ends, and artificial ear (IEC 318) is attached to sound in the housing 61 of communication terminal device, then can measure the sound pressure (decibel) that is produced by this artificial ear by on the part 62.When making internal electrode 19b and the 20b that adds piezoelectric element 18, and the frequency of the AC signal between outer electrode 19a and the 20a measures sound pressure when changing in 0.1～10KHz scope, then can measure the characteristic between audio frequency and the sound pressure.

Can find out from this figure, when the mobile phone that use to adopt according to piezoelectric type acoustical device of the present invention, can be in the frequency band range of 0.3～3KHz, produce stable and sound uniformly.And, as can be seen, can obtain very high sound pressure at audio frequency, for example near 130dB near 0.7KHz.

Figure 28 is illustrated on the inner surface of housing 11 and lid 46, makes boss 49, with an excessive displacement of restriction piezoelectric element 18 or an example of skew.Adopt this example, can protect when added voltage is excessive, can not cause the damage of piezoelectric element 18 owing to the over-large displacement of piezoelectric element.

Figure 29 is illustrated on the inner surface of housing 11, and an example of ribs 50 is set.When this ribs 50 was arranged in housing 11, the rigidity of housing 11 improved, thereby can be when piezoelectric element 18 vibrations, and the protection piezoelectric element can not twist; And making the displacement that causes by piezoelectric element 18 bendings, the efficient that is converted into the electric charge output variable can not reduce, thereby can obtain good or good sound pressure characteristic or acoustic pressure character.In addition, preferably make this ribs 50 have the function of above-mentioned boss 49; That is, aforesaid, the displacement that restriction piezoelectric element 18 is excessive.

Before Figure 30～Figure 33 represents that piezoelectric element 18 is installed in the housing 11, another example of this housing 11.

In housing shown in Figure 30 11, the top of each locating convex block 41 sees it all is circular in the plane.In housing shown in Figure 31 11, locating convex block 41 and guide 42 round the center configuration of housing 11, are offset 60 ° each other.In housing shown in Figure 32 11, guide 42 is fixed on three positions; And locating convex block 41 is placed on along the radial direction of housing 11, on these guide 42 corresponding positions.Again, in housing shown in Figure 33 11, guide 42 is fixed on three positions; And locating convex block 41 and guide 42 are placed round the center of housing 11, are offset 60 ° each other.In addition, in the example of this housing 11, terminal connection part divides 51 shape, and is different with the shape of above-described this part.

Figure 34 is the cross-sectional view of amplification of major part that comprises the piezoelectric element of the circumference wall 13 of above-mentioned housing 11 and locating convex block 41.As shown in the figure, this locating convex block 41 has a gradient; Therefore, when the outside from housing 11, when extended at its center, the upper surface of this projection is step-down gradually.

According to above-mentioned piezoelectric element 18, owing to there is not former described metalwork, therefore, the ceramic part of roasting can utilize silicon bonding agent etc., is fixed on the housing 11.Because the part of roasting has the scale error bigger than the part that stamps out, therefore, the size of locating convex block 41 must be in the radial direction of housing 11 more greatly.Yet the locating convex block size is too big, can adverse effect be arranged to the sound pressure characteristic of piezoelectric type acoustical device.In order to reduce or alleviate this adverse effect,, piezoelectric element 18 is moved easily by on this locating convex block 41, making above-mentioned gradient.The value at this angle of inclination on the locating convex block should be able to be adapted at keeping balance between ability to work and the characteristic, preferably is equal to or less than 5 °.

Claims

1. a piezoelectric element is used for vibrating along with being added in the signal voltage between its electrode, so that therefrom produce sound, comprising:

The piezoelectric ceramic of a pair of plate shape, it is polarized at thickness direction;

Internal electrode and the outer electrode made by the guiding element film, be respectively formed on two surfaces of each piezoelectric ceramic, wherein, piezoelectric ceramic is polarized in the opposite direction each other, make one of piezoelectric ceramic from the outer electrode to the internal electrode, polarize, and another of piezoelectric ceramic electrode is to outer electrode polarization internally, and each internal electrode that is respectively formed at each piezoelectric ceramic one side is connected to each other together, make them conduct each other, simultaneously the conducting each other of each outer electrode.

2. piezoelectric element as claimed in claim 1 wherein, is used to apply the lead-in wire of signal voltage, and with each all mutually conducting, the internal electrode of these two blocks of piezoelectric ceramic is connected with outer electrode respectively.

3. piezoelectric element as claimed in claim 1, wherein, a piezoelectric ceramic has one and cuts part, and the internal electrode of another piece piezoelectric ceramic under the state that these two blocks of piezoelectric ceramic link together, cuts part by this and exposes.

4. piezoelectric element as claimed in claim 3, wherein, lead-in wire is connected with the internal electrode that cuts a piezoelectric ceramic that partly exposes by this.

5. piezoelectric element as claimed in claim 1, wherein, the outer electrode of piezoelectric ceramic goes to piezoelectric ceramic inside around this piezoelectric ceramic; And this outer electrode goes back to next part, as internal electrode, links together, electric mutually upward conducting.

6. piezoelectric element as claimed in claim 1, wherein, the internal electrode of at least one block of piezoelectric ceramic around this piezoelectric ceramic, goes to the piezoelectric ceramic outside; And this produces the part of coming and is connected with lead-in wire.

7. piezoelectric type acoustical device, it comprises:

Housing as an echo box; With

Be placed on a piezoelectric element in this housing; Wherein, use as any one described piezoelectric element in the claim 1～6; Utilize a kind of elastic adhesive, the circumferential section of this piezoelectric element is bonded on the circumference wall of this housing.

8. piezoelectric type acoustical device as claimed in claim 7, wherein, the circumferential section of this piezoelectric element, the elastic adhesive of the circumference wall inboard by stretching into this housing is supported on the circumference wall of this housing.

9. a piezoelectric type acoustical device is equipped with a piezoelectric element, forms a wall portions in a housing, wherein, this piezoelectric element is the piezoelectric element of parallel bimorph formula, in this device, plate shaped piezoelectric ceramic does not pass through partition, but is laminated to each other together; And this piezoelectric element is bearing on the circumferential wall portion of this housing, but does not contact with the sidewall of housing.

10. piezoelectric type acoustical device as claimed in claim 9, wherein, this piezoelectric element is by with two piezoelectric ceramic stacked on top of one another together, between them, put into internal electrode, and on the outside main surface of these two blocks of piezoelectric ceramic, form outer electrode, constitute like this.

11. piezoelectric type acoustical device as claimed in claim 10, wherein, the piezoelectric ceramic of this piezoelectric element is three layers or more multi-layered stacked together.

12. piezoelectric type acoustical device as claimed in claim 10, wherein, each all has the polylith piezoelectric ceramic of outer electrode on the outside main surface of piezoelectric ceramic, stacked together by internal electrode; And each internal electrode is to form on a main surface relative with this outer electrode.

13. piezoelectric type acoustical device as claimed in claim 9, wherein, this piezoelectric element by elastic adhesive, is bonded on the circumference wall of this housing under the state that the circumference wall of its circumferential section and housing separates.

14. piezoelectric type acoustical device as claimed in claim 9, wherein, this piezoelectric element by containing the elastic adhesive of spheric granules, is bonded on the circumference wall of housing under the state that the circumference wall of its circumferential section and housing separates.

15., wherein, on the inner surface of a lid of this housing, the projection of a restriction piezoelectric element over-large displacement is arranged as any described piezoelectric type acoustical device among the claim 9-14.

16. piezoelectric type acoustical device as claimed in claim 9 wherein, has ribs, is used to suppress the distortion of housing on the inner surface of this housing.

17. piezoelectric type acoustical device as claimed in claim 9 wherein, on a surface of this piezoelectric element, has a lid of being made by damp-proof material.

18. a method of making the piezoelectric type acoustical device, this method comprises the following steps:

Prepare a housing, it has that internal diameter is equal to or greater than the circumference wall of piezoelectric element external diameter and near the positioner of the radial direction of this circumference wall and the positioner of short transverse;

Elastic adhesive is coated on the circumference wall of this housing;

Will be as any one described piezoelectric element in the claim 9～17, relatively place with the part that scribbles elastic adhesive on the circumference wall of housing;

Utilize the positioner of radial direction, guide this piezoelectric element, make the circumferential section of piezoelectric element, contact with elastic adhesive on the circumference wall that is coated in housing, and bonding with this bonding agent; With the positioner with radial direction, the part bonding with using elastic adhesive separated.