JPH0418319Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field of the Invention) The present invention relates to the structure of a piezoelectric electroacoustic transducer using a diaphragm to which a piezoelectric ceramic element is attached.

(Prior art and its problems) A piezoelectric sounding body disclosed in Japanese Patent Application Laid-Open No. 54-21296 as an example of this type of electroacoustic transducer is composed of a piezoelectric material, a metal vibrating thin plate, and an insulating support member. , a thin film piezoelectric material and a thin film conductive material closely laminated at the center of the metal vibrating thin plate are formed by extending to the outer edge of the metal vibrating thin plate, and the thin film piezoelectric material is insulatingly supported as an insulating material between the metal vibrating thin plate and the conductive material. It has a structure in which the vibrating thin metal plate and the conductive material are connected by a driving terminal plate. For this reason,
The fundamental resonant frequency changes depending on the fixed state of the flat diaphragm, and the resonance box has a complex structure with a concave part in the center and many small holes and tap holes for set screws. Therefore, the mold is expensive and the assembly process is not economical. Furthermore, the installation of the drive terminals is not simple either.

Further, other conventional examples of this type of piezoelectric electroacoustic transducer include those shown in FIGS. 1a, b, and c.
Here, 1 is a vibration substrate made of a metal material, 2 is a piezoelectric ceramic element, 3-1 and 3-2 are electrodes provided on both sides of the piezoelectric ceramic element 2, 6 is a molded terminal plate, and 7-1 and 7-2 are An external terminal 8 provided on the molded terminal plate 6 is a metal case in which a vibrator and the like are fixed. An air chamber 9 is provided between the vibrating substrate 1 and the molded terminal plate 6 in order to give the required broadband characteristic ranging from 300Hz to 3400Hz to the single resonance characteristic of the combination of the vibrating substrate 1 and the piezoelectric ceramic element 2. It is being Electrodes 3 on both sides of piezoelectric ceramic element 2
-1, 3-2, the electrode 3-1 on the vibrating board 1 side is connected to the vibrating board 1 by adhesion, and the vibrating board 1 is connected by the soldered part 7-3 or the spring contact 7-5. The electrode 3-2 on the opposite side from the vibration board 1 is connected to the soldered part 7-4 or the spring contact 7.
A positive electrode is provided through the external terminal 7-2 connected by -6.

However, since this type of piezoelectric electroacoustic transducer is required to have a thin plate as a whole, the height of the air chamber 9 is extremely low at about 1 to 2 mm, and the height of the air chamber 9 is extremely low, about 1 to 2 mm. Parts 7-3 and 7-4 soldered to electrode 3-2 of No. 2
The process is complex and difficult to automate. Furthermore, since the connecting portion with the piezoelectric vibrator is located in a vibrating place, a load is applied during vibration, resulting in a decrease in characteristics, and there is also a drawback that stable frequency characteristics cannot be obtained. Moreover, the portion 7- connected to the vibration substrate 1 and the electrode 3-2 of the piezoelectric ceramic element 2
Even if 5 and 7-6 are spring contacts, if the spring pressure is large, a load will be applied during vibration, and if the spring pressure is small, contact failure will occur due to the vibration of the piezoelectric vibrator, and continuity will not be compensated. The disadvantage is that stable frequency characteristics cannot be obtained.

Further, a piezoelectric type electroacoustic transducer disclosed in Japanese Utility Model Publication No. 59-34239 as an improved version of these conventional ones is shown in FIGS. 2a, b, and c. In this case, conductive patterns 27-3 and 27-4 are attached to the terminal plate 26, and when trying to enlarge the air chamber 29 in order to obtain the necessary high sensitivity and frequency characteristics,
It is difficult to provide a recess in the terminal plate 26. Even if an attempt is made to make the concave portion 21-1 of the vibrating substrate 21 deep, it is very difficult to make the concave portion 21-1 deep, and it is also difficult to provide the insulating layer 24 and the conductive layer 25. In addition, the connection between the external terminals 27-1, 27-2 and the conductive patterns 27-3, 27-4 is usually done by soldering, etc., but due to this, poor soldering or external force applied to the terminals may cause the connection to fail. Failure to do so may result in poor conduction.

(Purpose of the invention) In order to eliminate these drawbacks in the prior art, the present invention is designed to contact and connect the external terminals of the terminal board with the peripheral edge of the vibrator to integrate them, and to take out the external terminals directly. The present invention provides a piezoelectric electroacoustic transducer that can stabilize conduction, and also allow recesses to be provided in the terminal plate, thereby easily achieving the required sensitivity and good frequency band characteristics.

(Structure of the invention) In order to achieve this objective, the piezoelectric electroacoustic transducer of the invention uses a piezoelectric vibrator in which one electrode of a piezoelectric ceramic element having a pair of electrodes on both sides is attached to a metal vibrating substrate. and a terminal plate having two external terminals respectively connected to the pair of electrodes, wherein the vibrating substrate has a recess formed in a central portion other than a peripheral portion, and the recess The piezoelectric ceramic element is attached to the vibrating substrate, an insulating layer is applied to at least a part of the surface of the vibrating substrate other than the area to which the piezoelectric ceramic element is attached, and the other electrode is different from the one electrode. A conductive layer is applied from the top to the top of the insulating layer, each of the two external terminals is integrally formed with a leg part and an extension part from which the leg part extends, and the terminal board has a conductive layer formed on each of the two external terminals. The leg portion is embedded and the elongated portion is disposed so as to extend to the peripheral edge of the vibrating substrate, and the elongated portion of one of the two external terminals is connected to the conductive portion by stacking the piezoelectric vibrator and the terminal plate. The structure is characterized in that the other extension part of the second external terminal is contact-connected to the layer and is integrated with the peripheral edge part of the vibration substrate.

(Example) Examples of the present invention will be described below.

FIGS. 3a and 3b are a bottom view and a sectional view of a piezoelectric vibrator in an embodiment of the piezoelectric electroacoustic transducer according to the present invention, and FIGS. 5a and 5b show the structure of the piezoelectric electroacoustic transducer according to the present invention. An example cross-sectional view and an enlarged view thereof are shown. Although the metal case is omitted, for example, a caulking structure as shown in FIG. 1 is employed for fixation. Here, 31 is a vibration substrate made of a metal material;
32 is a piezoelectric ceramic element, and 33 is an electrode provided on both sides of the piezoelectric ceramic element 32, consisting of an electrode 33-1 on the vibrating substrate 31 side and an electrode 33-2 on the opposite side from the vibrating substrate 31. 34 is an insulating layer on the side of the vibrating substrate 31 on which the piezoelectric ceramic element 32 is attached, and 35 is an electrode 33- on the side opposite to the vibrating substrate 31.
This is a conductive layer provided on the insulating layer 34 from 2 to 3. The electrode 33-1 on the vibration substrate 31 side is electrically connected to the vibration substrate 31. Piezoelectric ceramic element 3 of vibration substrate 31
An insulating layer 34 is applied to at least a portion other than the piezoelectric ceramic element 32 attached to the side marked with 2, that is, approximately half in the illustrated case, and a conductive layer 35 is arranged on the insulating layer 34 so as not to contact the vibrating substrate 31. A part of it is connected to the vibration substrate 31 and the electrode 33- on the opposite side.
I am trying to connect to 2.

Figures 4a, b, c, and d show specific examples of molded terminal boards according to the embodiment, in which external terminals 37-1 and 37-2, which have both external electrode and piezoelectric vibrator connections, are formed by insert molding or press-fitting. It is fixed to the terminal plate 36. These external terminals 37-1, 37-2 are
Leg portions 37-3 and 37-4 embedded in the center portion 36-4 of the terminal plate 36 and an extension portion 37-4 extending to the peripheral edge 36-3 of the terminal plate 36 where the legs contact the peripheral edge of the vibration board 31. 5, 37-6. terminal 3
The material of 7-1 and 37-2 may be a spring material or other metal. Furthermore, in order to ensure sufficient spring characteristics and increase the reliability of conduction, protrusions 36-1 and 36-2 may be provided on the molded terminal board as shown in c and d. In the specific example shown in FIG.
Since the concave portion 9a forming a part of the air chamber 9 is formed in the air chamber 4, it is possible to sufficiently secure the necessary volume of the air chamber 9, and there is an effect that the required frequency characteristics and sensitivity can be obtained.

FIG. 5a is a cross-sectional view showing the lead extraction structure of the piezoelectric vibrator of the embodiment, and FIG. The part without layer 35 is terminal 3
It is possible to easily integrate the vibrating board 31 by crimping the terminal plate 36 by caulking or the like so as to make contact with the electrode 33-1 and the terminal 37-1. -2 and terminal 37
-2 conducts. Two terminals 37-1, 37-2
By applying a voltage between the terminals 37-1
is directly connected to the metal vibrating board 32, and the terminal 37-
2 is electrically connected to the conductive layer 35, and the piezoelectric ceramic element 3
A voltage is applied to the electrodes 33-1 and 33-2 on both sides of 2.

In the above embodiment, the recessed portion 31-1 is formed in the central portion of the vibrating substrate 31 so that the peripheral portion of the vibrating substrate 31 protrudes from the central portion.
Since the piezoelectric ceramic element 32 is attached to the terminal board 36, the contact between the terminals 37-1, 37-2 of the terminal board 36 and the electrodes 33-1, 33-2 is stable, and the air chamber 39 is Shape and volume are stabilized. Furthermore, since the terminals 37-1 and 37-2 also have external electrodes, they can be electrically connected by being inserted into a terminal board provided with a conductive pattern, so that it is possible to easily stabilize electrical continuity.

(Effects of the invention) As explained above, the piezoelectric acoustic transducer according to the invention has a simple assembly structure and easy manufacturing because the conduction between both electrodes of the piezoelectric ceramic element and the external terminals is simple, and the assembly can be automated. It is suitable for
Further, by using a molded terminal plate, it is possible to integrally mold the terminal with the terminal, and it is possible to manufacture the terminal at low cost and to stabilize conduction. Further, the volume of the air chamber can be partially shared by the terminal plate, and by increasing or decreasing the volume of the air chamber, it is easy to provide desired sensitivity and stable broadband characteristics to a thin plate.

[Brief explanation of the drawing]

Fig. 1 a, b, c and Fig. 2 a, b, c are plan views and cross-sectional views showing an example of the structure of a conventional piezoelectric electroacoustic transducer, and Fig. 3 a, b are piezoelectric transducers used in the present invention. Plan view and cross-sectional view showing an example of the structure of a vibrator, No. 4
Figures a, b, c, and d are plan views and cross-sectional views of molded terminal plates used in the present invention, and Figures 5 a and b are cross-sectional views showing an embodiment of the piezoelectric electroacoustic transducer of the present invention excluding the case. and a partially enlarged view. 1, 21, 31... Vibration board, 2, 22, 32
...Piezoelectric ceramic element, 3-1, 3-2, 23
-1, 23-2, 33-1, 33-2...electrode,
4, 24, 34...Insulating layer, 5, 25, 35...
Conductive layer, 6, 26, 36...Mold terminal plate, 7
-1, 7-2, 27-1, 27-2, 37-1,
37-2...External terminal, 7-3, 7-4, 7-
5, 7-6... End of external terminal, 8... Metal case, 9, 29, 39... Air chamber, 9a... Part of air chamber, 27-3, 27-4... Conductive pattern,
36-1, 36-2...protrusion, 36-3...periphery, 36-4...flat plate portion, 37-3, 37-4...
...Leg portions of external terminals, 37-5, 37-6...extension portions of external terminals.

Claims (1)

[Scope of utility model registration request] A piezoelectric vibrator having one electrode of a piezoelectric ceramic element having a pair of electrodes on both sides attached to a metal vibrating substrate, and a terminal board having two external terminals respectively connected to the pair of electrodes. In the piezoelectric electroacoustic transducer, the vibrating substrate has a recessed portion formed in a central portion other than the peripheral portion, the piezoelectric ceramic element is pasted to the recessed portion, and the piezoelectric ceramic element on the vibrating substrate is pasted. An insulating layer is applied to at least a part of the surface other than the part where the external terminal is connected, and a conductive layer is applied from the other electrode different from the one electrode to the insulating layer, and each of the two external terminals has a leg part and a conductive layer. The leg portions are integrally formed with an elongated portion, and the leg portions of the two external terminals are embedded in the terminal plate, and the elongated portions are disposed so as to extend to the peripheral edge of the vibration substrate; Due to the stacked connection of the piezoelectric vibrator and the terminal board, the extension of one of the two external terminals is in contact with the conductive layer, and the extension of the other of the second external terminal is connected to the vibration substrate. A piezoelectric electroacoustic transducer characterized in that the piezoelectric electroacoustic transducer is configured to be contact-connected and integrated with the peripheral portion.