JPH0284900A - Card type piezoelectric sounding body - Google Patents

Abstract

PURPOSE:To cause a card type piezoelectric sounding body to be thin by laminating and unifying a diaphragm, which has a groove to be formed with dislocating a position, and a substrate, in which a hole to be a fixing part is provided. CONSTITUTION:A piezoelectric material 11 is adhered to a metallic board 15. For this metallic board, a groove 14 is formed mutually on both front and rear sides between the outer circumferential part of this piezoelectric material 11 and a position corresponding to a fixing hole 13 of a peripheral fixing body 12 with dislocating the position. Then, this board is used as the diaphragm. This diaphragm is sandwiched from upper and lower directions by the peripheral fixing bodies 12 and a thermosetting adhesive, etc., is applied or a sheet is put in. Then, the diaphragm and fixing bodies are laminated and unified.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a thin type piezoelectric sounding element.

[Conventional technology]

Piezoelectric sounding bodies can be made smaller and thinner, and consume less power, so they are expected to be used in space-saving implementations in communication devices that use batteries. For example, there are limits to the thinness of electrodynamic types that use magnets, such as card-based pagers that notify incoming calls on telephone lines, and card-type handsets for cordless telephones. This electrodynamic type cannot be used because it is carried along with ID cards for information devices.

For these reasons, it has become desirable for piezoelectric sounding bodies to have wideband characteristics that can be used in the voice band, and a structure that can be used at low frequencies with a small structure, rather than something like a single-tone puzzer. Ta. In order to achieve these characteristics, the thickness of the piezoelectric material, which was conventionally 100 μm or more, has been reduced to 50 μm or less, and the thickness of the support plate to be bonded has also been reduced to 50 μm.
Thin ones with a thickness of less than m have come to be used. moreover,
As a support method for using these as a diaphragm, a support method in which the peripheral portion is fixed with an elastic adhesive in order to bring the peripheral portion closer to the pin end support has come to be used.

FIG. 6 is a perspective view showing the structure of a conventional piezoelectric sounding body in which a piezoelectric material 62 is attached to a metal plate 61 and its peripheral portion is fixed to a fixed body 64 with an elastic adhesive 63. At this time, it is assumed that the elastic adhesive 63 is close to the state in which the peripheral part of the metal plate 61 is supported by the pin end, and the metal plate 63 is
The thickness of the piezoelectric material 62 is becoming thinner, from 100 μm to 50 μm or less. The piezoelectric sounding body constructed in this manner is attached to the case of a device that generates sound by screws, adhesive, or the like. In some cases, the device is fixed to the case itself using an elastic adhesive.

[Problems to be Solved by the Invention] The conventional piezoelectric sounding body described above uses an elastic adhesive to fix the peripheral portion, so a fixing body is required as a frame for this fixation. In card radios, handy televisions, and the like, a sounding body attached to the fixed body is obtained by screwing or adhering to a circuit board or case. Therefore, in order to achieve this type of implementation, the overall thickness of the product is
This includes the thickness of the circuit mounting portion and the thickness of the sounding body, making it difficult to respond to thinning requirements. In order to make this thinner, it is possible to make a hole in the board of the circuit mounting part as a fixing part and adhere it directly to this hole with an elastic adhesive to form a piezoelectric sounding body that is integrated with the circuit mounting board. However, in this case, due to the relationship between the temperature of the wave solder and the curing temperature of the elastic adhesive for mounting the electronic components in the circuit mounting section, it is impossible to form them at the same time, and even if they are mounted separately, they can be formed at room temperature due to the relationship between the mounted components. It is difficult to reduce the thickness of the circuit mounting portion mounted on the substrate because it hardens and requires a long curing process. For this reason, it is necessary to separate the above-mentioned adhesive to the fixing body and the circuit mounting part, making it difficult to adapt to a thin card type.

In addition, if the thickness of the metal plate and piezoelectric material is reduced to 50 μm or less in response to lower frequencies, the influence of the elastic liquid adhesive part will be stronger, and the frequency band that can be sounded will change and unnecessary harmonics will be produced. This includes many variation factors such as the generation of waves, making it difficult to obtain a sounding body with good sound quality. Furthermore, piezoelectric sounding elements have a high Q as a diaphragm and have a narrow band of sound, so they usually form a semi-sealed air chamber with small sound emitting holes and leakage holes at the front and rear of the diaphragm. Alternatively, an acoustic resistance element (for example, a cloth mesh) is formed inside the air chamber in terms of an equivalent circuit, but the structure of these elements also makes it difficult to reduce the thickness.

[Means to solve the problem]

The card shop piezoelectric sounding body of the present invention is a piezoelectric sounding body obtained by pasting a piezoelectric material on a metal plate, in which both the front and back sides of the metal plate are alternately arranged between the outer periphery of the piezoelectric material and the fixing part that supports and fixes the piezoelectric material. A diaphragm having grooves formed at different positions and a base material provided with a hole serving as the fixing part are laminated and integrated, and at least one
A wiring pattern is formed on the base material having a number of small holes or another base hole having the small holes and an acoustic circuit element,
Connecting means or drive circuit elements for driving the diaphragm are formed.

[Effect]

The card-type piezoelectric sounding body of the present invention has circular grooves formed by pasting a piezoelectric material on a metal plate and alternately forming round grooves on both the front and back sides of the metal plate between the outer periphery of the piezoelectric material and the peripheral fixing part, and at different positions. By configuring a diaphragm having a diaphragm having a diaphragm, when the peripheral part of the groove is fixed, the groove acts as a damper, which facilitates flexural vibration and lowers the frequency.
188194. In the present invention, this diaphragm is sandwiched between base materials (for example, glass epoxy material, polyester film, etc. that constitute a printed circuit board) that have holes of the same diameter as fixing parts, and then laminated by thermocompression bonding or by applying an adhesive. It becomes one thing. At this time, since the diaphragm is a diaphragm with grooves formed around its periphery as described above,
Even if the periphery of the groove is fixed, the grooves formed alternately on both sides make it easy to bend and deform the diaphragm, so it has superior properties compared to fixing with conventional elastic adhesives, and is a base material for circuit mounting. If this is formed, it is possible to construct a communication device that is as thin as a card and can generate sound, including the sounding body.

In addition, sound can be produced by sandwiching the diaphragm between base materials with fixed body holes and then laminating a base material with sound emission holes and leakage holes on top of the fixed body to form an air chamber. The front band can be widened. In this case as well, the sounding body becomes thicker due to the air chamber, but since it can be integrated with the circuit board on which the circuit is mounted, a communication device having a sounding body as thin as a card can be obtained.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is an exploded perspective view of the first embodiment of the present invention before lamination;
Fig. 2 is an exploded perspective view of a second embodiment in which an air chamber is provided in the first embodiment before lamination, and Fig. 3 is a third embodiment in which an acoustic resistance element is provided in the second embodiment. FIG. 4 is an exploded perspective view of the fourth embodiment in which a card type circuit is mounted on the first to third embodiments before lamination, and FIG. 5 is an exploded perspective view of the fourth embodiment before lamination. FIG. 3 is a cross-sectional view showing a state in which the piezoelectric material and the metal plate are partially bonded.

In the first embodiment shown in FIG. 1, the piezoelectric material 11 is
It is glued to a metal plate 15 with grooves 14 alternately formed on both the front and back sides between the position where the piezoelectric material is fixed on the outer periphery and the position where it is fixed on the fixing hole 13 of the peripheral fixing body 12, and this is used as a diaphragm. used as Next, this diaphragm is sandwiched from above and below between peripheral fixing bodies 12 having fixing holes 13, and a thermosetting adhesive or the like is applied or a sheet is inserted and pressure bonded to form a laminated body. At this time, the periphery of the diaphragm is fixed by the base material that becomes the peripheral fixing body 12, but since there are grooves 14 formed between the outer periphery of the piezoelectric material 11 and this fixing part, alternating between the front and back sides, vibrations are prevented. Since the plate can be easily bent and deformed, the thickness of the sounding body is only the sum of the thickness of the base material (top and bottom) that becomes the peripheral fixed body 12 and the thickness of the metal plate 15 that makes up the diaphragm, which is different from the conventional technology. You can obtain a sounding body as thick as a card, which was not possible with other methods.

The metal plate 15 constituting the diaphragm used here has a diameter of 50 N.
A stainless steel or brass plate with a thickness of approximately μm is patterned and etched on both sides to form grooves 14 alternately on both sides. If the depth of the etching is set to about 315 mm of the thickness of the metal plate 15, a resonant frequency less than 1/2 of that of a peripherally fixed diaphragm without grooves with the same support diameter can be obtained. Furthermore, the piezoelectric material 11 that is bonded to the metal plate 15 is extremely thin, about 50 μm in thickness, and is made into a green sheet by the slip casting method used in multilayer ceramic capacitors. form,
After the external shape is processed, the product is obtained through a binder removal and firing process. Metal plate 1 with grooves 14 formed in this way
5 and the piezoelectric material 11 may be bonded together. At this time, the special request
The adhesion surface of the metal plate shown in No. 2-188195 may also be curved to allow partial adhesion between the piezoelectric material and the metal plate at the center and outer periphery.

On the other hand, as the peripheral fixing body 12 in which the fixing hole 13 is formed,
Guide pin holes and fixing holes 13 for alignment are formed in a glass epoxy plate with a thickness of about 0.2 to 0.4 mm, adhesive is applied to this, the diaphragm is aligned, and the diaphragm is laminated. It may be crimped or heat-cured.

The second embodiment shown in FIG. 2 is based on the card-type piezoelectric sounding element shown in FIG. It is a card-shaped piezoelectric sounding body. In this figure 2, a diaphragm 2 with grooves is shown.
1 is laminated and integrated with the fixed body 22, and a sound emitting hole forming plate 24 having sound emitting holes 23 is laminated on the upper side thereof, and a leak hole forming plate 26 having leak holes 25 formed therein is further laminated. , since the hole part of the fixed body 22 becomes an air chamber, the sound emission hole 2
3 and the size of the leak hole 25 and the height of the air chamber (fixed body 2
From the relationship between As a characteristic, broadband characteristics can be obtained.

In this case as well, the thickness of the sounding body is determined by the thickness of the base materials 24 and 26 that form the sound emitting hole 23 and the leakage hole 25, and the thickness of the peripheral fixed body 22 in which the diaphragm 21 with grooves is laminated and integrated. Since it is only added, an extremely thin sounding body with the thickness of a card can be obtained.

A third embodiment shown in FIG. 3 is one in which a cloth mesh 31 which serves as an acoustic resistance element in terms of a circuit is added to the leak hole 25 of the sounding body forming the air chamber shown in FIG. When the cloth mesh 31 acts as a resistance at the leak hole 25, the resonance characteristics of the air chamber on the side of the leak hole 25 change (the Q decreases), and the frequency characteristics of the sound pressure of the entire sounding body can be improved. Further, the characteristics can be changed by forming the cloth mesh 31 not only on the side of the leakage hole 25 but also on the side of the sound emission hole 23. Furthermore, as the mesh of the acoustic resistance element, not only cloth but also materials such as paper and film may be used. In these cases as well, since the mesh material for improving the characteristics is formed inside the air chamber, the thickness of the sounding body is the same as in the case of FIG. 2, and a sounding body as thick as a card can be obtained.

The fourth embodiment shown in FIG. 4 is a piezoelectric type sounding body with a circuit based on the sounding body structure in which air chambers are formed as shown in FIG. 2, and a fixing hole 41 and a hole 42 for mounting parts are formed. The upper peripheral fixing body 43 has a terminal 45 for connecting to the diaphragm 44, and the lower peripheral fixing body 46 has a pattern for connecting to the terminal 45 and a one-chip control I.
A component mounting pattern 47 for mounting C, etc. is formed, and the upper peripheral fixing body 43, the diaphragm 44, the lower peripheral fixing body 46, and the leak hole forming plate 4B are laminated and integrated. After connecting the electrodes of the diaphragm 44 to the control IC
A card-shaped piezoelectric sounding body with a circuit is obtained by mounting the sound emitting hole forming plate 49 and peripheral circuit components, and then gluing the sound emitting hole forming plate 49. In this case as well, the sounding body is the same as in the case of Figure 3, and the thickness of the card size is ensured, and at the same time, the IC of the circuit that drives the sounding body and other communication functions is used.
Since it is integrated with the mounting part, it can be used as a card-sized mobile communication device.

FIG. 5 shows the configuration of a diaphragm that has grooves on the adhesive surface in addition to the grooves on the periphery, and the piezoelectric material 51
By forming grooves 53 on the bonding surface in the metal plate 52, this bonding is made partial bonding between the center portion 54 and the outer peripheral portion 55. The diaphragm made by this partial adhesion is manufactured by patent application No. 62-1.
88195, which prevents the reduction in sound pressure level that inevitably occurs when the thickness of the piezoelectric material 51 and metal plate 52 that constitute the diaphragm are made thinner in order to lower the frequency of the sounding body. However, in conventional full-surface adhesive bonding, as the thickness of the piezoelectric material becomes thinner, it approaches the bonding surface, so the elongation in the plane direction that occurs when an electric field is applied to the piezoelectric material is small. In contrast, if grooves 53 are formed on the bonded surface and partial bonding is performed, the elongation in the surface direction of the non-bonded portion will not be suppressed, resulting in a smaller deflection deformation. Even if it is made thinner, the deflection deformation is large, and the sound pressure level of the sounding body is high.

As shown in the above explanation, the card-type piezoelectric sounding body of this example uses a ring-shaped groove formed in the peripheral part as a diaphragm, so that it can be used as a peripheral fixing body with holes for the fixing part. A communication device including a sounding body as thick as a card can be obtained by sandwiching and laminating the materials together.

In this example, the diaphragm is shown only as a sounding body, but since the diaphragm usually has reversibility and generates electrical output in response to external sounds, it can also operate as a microphone. Since it has a ring-shaped groove around its periphery, it can be deflected and deformed greatly in response to external voice input, making it a highly sensitive transmitter. Therefore, it is possible to form a single card including this transmitter, and in this case, the control IC and peripheral circuits installed are used as a yawless telephone circuit, and a loop antenna is installed around the periphery of the card. By forming a pattern like this, it is possible to realize a cordless telephone that can fit in a pocket. In addition, although the shape of the diaphragm is circular, it is also possible to use a rectangular diaphragm by forming grooves on the periphery. In this case as well, a card-shaped sounding body can be realized.

〔Effect of the invention〕

As explained above, the present invention uses a diaphragm in which ring-shaped grooves are alternately formed on the front and back sides of the periphery, so that the diaphragm can be fixed simply by sandwiching the diaphragm, compared to support using conventional elastic adhesives. The same or better broadband characteristics can be obtained, and even if the diaphragm becomes thinner like when using elastic adhesive, the support part is isotropic and uniform, so unnecessary vibrations (harmonics) are not generated. This has the effect of creating a sounding body with far fewer occurrences. Further, at this time, the thickness is extremely thin even including the support and fixing body, and the sounding body can easily be formed into a card type sounding body. Furthermore, since no elastic adhesive is used at this time,
Since the diaphragm can be laminated and integrated with the substrate on which the peripheral ICs that drive the piezoelectric diaphragm are mounted, it is possible to easily create card-type communication devices with circuits, card-type cordless telephones, and card-type mobile communication devices. There is.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of the first embodiment of the present invention before lamination;
Fig. 2 is an exploded perspective view of a second embodiment in which an air chamber is provided in the first embodiment before lamination, and Fig. 3 is a third embodiment in which an acoustic resistance element is provided in the second embodiment. Exploded perspective view before lamination, No. 4
The figure is an exploded perspective view of a fourth embodiment in which a card type circuit is mounted on the first to third embodiments before lamination, and FIG. FIG. 6 is a partially cutaway perspective view showing an example of a conventional piezoelectric sounding body using an elastic adhesive. 11... Piezoelectric material, 12... Peripheral fixed body, 13...
Fixing hole, 14...Groove, 15...Metal plate, 21...
Vibration plates 1, 22...Fixed body, 23...Sound emission hole, 24
...Base material, 25...Leak hole, 26...Base material, 31
... Cloth mesh, 41 ... Fixing hole, 42 ... Part mounting hole, 43 ... Upper peripheral fixing body, 44 ... Vibration plate, 45 ... Terminal, 46 ... Bottom peripheral fixation body on the side,
47... Component mounting pattern, 48... Leak hole forming plate, 49... Sound emission hole forming plate, 51... Piezoelectric material, 52...
...Metal plate, 53... Groove on adhesive surface, 54... Adhesive part at center, 55... Adhesive part at outer periphery, 61... Metal plate, 62... Piezoelectric material, 63...・Elastic adhesive, 64・
...Fixed body. Figure 1 Agent: Susumu Uchihara Figure 4 Figure 3 Figure 5

Claims (3)

[Claims] 1. In a piezoelectric sounding body obtained by pasting a piezoelectric material on a metal plate, grooves are formed alternately and at different positions on both the front and back sides of the metal plate between the outer periphery of the piezoelectric material and a fixed part for supporting and fixing. A card-type piezoelectric sounding element characterized in that a diaphragm held by the diaphragm and a base material provided with holes serving as the fixing part are laminated and integrated. 2. A claim characterized in that at least one small hole or another base material having the small hole and an acoustic circuit element are laminated and integrated with the base material having a hole serving as a fixing part to form an air chamber. The card-type piezoelectric sounding body according to item 1. 3. 3. A wiring pattern is formed on the base material having a hole serving as a fixing part, and a connecting means or a driving circuit element for driving the diaphragm is formed thereon.
The card-type piezoelectric sounding body described.