JPH055755Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a piezoelectric speaker equipped with a vibrator using a piezoelectric diaphragm made of ceramics or the like.

[Prior Art] Moving coil type dynamic speakers have been the mainstream and widely used speakers for more than half a century. meanwhile,
Many improvements have been made, mainly due to advances in permanent magnet materials, but it seems as though they have reached a saturation point. On the other hand, due to the development of technology such as integrated circuits, electronic devices are becoming increasingly diversified in functions and miniaturized in form.
Speakers as built-in components are required to be thin, lightweight, and compact in many respects.

As a speaker that meets the above requirements,
2. Description of the Related Art Piezoelectric speakers are known that include a vibrator using a piezoelectric diaphragm made of ceramics or the like.

In recent years, strong piezoelectric ceramics mainly made of zirconium lead titanate have been developed, and piezoelectric vibration is produced by laminating this thin piece with an electrode surface on one side (unimorph type) or both sides (bimorph type) of a metal plate base. As plates became produced in large quantities and costs were significantly reduced, they became widely used as sources of vibration in electro-acoustic transducers.

The applicant of this invention previously proposed a piezoelectric speaker that was thin, flat, and compact, had high conversion efficiency, and had an expanded operating frequency band, using the strong piezoelectric ceramic described above. 62−
No. 294316).

FIG. 4 is a plan view showing the diaphragm of a conventional piezoelectric speaker, FIG. 5 is a sectional view showing the configuration of a piezoelectric speaker formed using the diaphragm of FIG. 4, and FIG.
FIG. 3 is a perspective view showing a part of the coupling portion between the diaphragm and the coupling ring shown in the figure.

In the figure, 1 is a diaphragm, in which a plurality of triangular feather-shaped wave folds 2 gradually expand from the central dome part 3 toward the outer periphery, and spread radially over the entire surface with a regular chrysanthemum pattern. configured to form a Each wave fold 2 is continuously integrated from the outer circular arc portion 4 of the triangular slope 5 at the outer end to the U-shaped groove-shaped edge portion 6 that serves as the fulcrum and the flat portion 7 that serves as the adhesive surface. In addition, the central terminal end of the wave folds 2 is connected to the outer periphery of the central dome part 3, and each wave fold 2 has a cantilever action with the edge part 6 as a fulcrum, and both stiffness distributions of each part are different from the center. It is configured to increase sequentially toward the outer periphery. As shown in the cross-sectional view of FIG. 5, on the back surface of the diaphragm 1, vibrators 9 made of disc-shaped piezoelectric vibrating elements are arranged concentrically and in parallel with a relatively narrow gap between them, and the outer edge portions 14 is surrounded by a rubber coupling ring 13 whose upper end is connected to the drive point 15 of each corrugation 2 of the diaphragm 1, forming a narrow air chamber 17. A weight 10 is attached to the center of the vibrator 9 via a viscoelastic layer 11, so that the vibrator 9 vibrates in a concave lens-like vibration mode as shown by the dotted line.
In FIG. 5, 8 is a frame, 12 is a fixed end of the diaphragm 1, and 16 is a terminal plate to which a signal voltage e from the outside is applied.

Now, when the signal voltage e is applied to the vibrator 9, the fifth
As shown by the dotted line in the figure, a concave lens-shaped curved vibration is performed, and the excitation force F generated at the outer edge 14 is applied to the driving point 15 via the coupling ring 13, excitation accelerates the entire surface of the diaphragm 1, and generates sound. configured to emit radiation.

[Problem to be solved by the invention] In the conventional piezoelectric speaker described above, if the air chamber 17 surrounded by the diaphragm 1 and the vibrator 9 is kept in a sealed state, the internal pressure of the air chamber 17 will decrease as the vibrator 9 vibrates. rises and biases the diaphragm 1 from the back, resulting in
This is harmful because it induces malignant parasitic vibrations around 2kHz, significantly degrading sound quality. After experimenting with various means to reduce and eliminate this negative effect, we found that
The best results were obtained by distributing a large number of small openings, one each at connection points around the wave folds 2 and the connection ring 13, and applying acoustic resistance to the air chamber 17.

For example, as shown in FIG. 6, a shallow triangular groove 19 is cut into the ring top surface 18 of the coupling ring 13, and this is fitted into the wave folds 2 and glued to form a gap 20, which is then inserted into the air chamber 17 as a distributed acoustic resistance. The addition method is effective as a means to eliminate the adverse effects of compliance.

However, this method has poor workability due to the complex triangular wave-like irregularities on the bonding surface of the coupling ring 13, and variations occur depending on the viscosity of the adhesive and the amount of application, resulting in misalignment during the bonding process. There was a problem that it was unsuitable for automatic mechanization of assembly work because it had drawbacks such as easy core deformation.

This idea was devised to solve these problems, and aims to shorten the process required for mass production, reduce manufacturing costs, and obtain high-quality, inexpensive piezoelectric speakers that can be supplied in large quantities. .

[Means for Solving the Problems] A piezoelectric speaker according to this invention has a diaphragm in which a large number of triangular feather-shaped wave folds are radially distributed from a central dome part to a peripheral edge part. A bonding plane for inserting a coupling ring is formed at the driving point on the back side of the corrugated fold, and the flat surface of the coupling ring inserted into this bonding plane is bonded, and each of the corrugated folds is individually attached to the coupling ring. It is configured to open a small acoustic opening that communicates with an air chamber surrounded by the diaphragm and the piezoelectric vibrating element.

[Function] In the piezoelectric speaker of this invention, a bonding plane for inserting the coupling ring is formed at the driving point of each wave fold, and the flat surface of the coupling ring inserted into this bonding plane is bonded. Therefore, assembly work is easy and can be done in a short time.

[Example] Fig. 1 is a plan view showing a part of a diaphragm of a piezoelectric speaker which is an embodiment of this invention, and Fig. 2 shows the configuration of a piezoelectric speaker formed using the diaphragm of Fig. 1. The sectional view and FIG. 3 are perspective views showing a part of the connecting portion between the diaphragm and the coupling ring shown in FIG. 2. Figure 4~
The same or corresponding parts as in FIG. 6 are indicated using the same reference numerals, and detailed explanation thereof will be omitted. In the figure, 21 is an adhesive plane for coupling with the coupling ring 13 provided in a circular shape on the slope above the driving point 15 of all the wave folds 2 on the back side of the diaphragm 1, 22 is a flat surface of the coupling ring 13, 23 is a distributed aperture which is a small acoustic aperture.

Adhesive is applied to the flat surface 22 of the coupling ring 13 fixed to the outer edge 14 of the vibrator 9, and this is applied to the adhesive plane 21 of the wave fold 2, which is the driving point 15 of the diaphragm 1.
As shown in FIGS. 2 and 3, the diaphragm 1 and the vibrator 9 are connected to the coupling ring 13.
and form a distributed opening 23.

Such a diaphragm 1 is usually produced in large quantities by molding paper pulp using water-paper molding or by heating and press-molding an engineering plastic film with excellent heat and weather resistance. In this case, the cutout surface of the bonding plane 21 can be easily and accurately set. Note that since the piezoelectric transducer using the diaphragm 1 and the coupling ring 13 is reversible, it can be applied not only to speakers but also to microphones.

[Effects of the invention] As explained above, this invention is an adhesive for inserting a coupling ring into the driving points of the wave folds distributed in large numbers from the central dome to the peripheral edges of the diaphragm in a piezoelectric speaker. Distributed openings forming a plane and bonding the flat surfaces of the coupling rings inserted into this bonding plane, each corrugation individually communicating with an air chamber surrounded by the coupling ring, the diaphragm, and the piezoelectric vibrating element. Since I configured it to open
Opening of the distributed opening and automatic alignment are performed at the same time, significantly shortening the assembly process.
Its automatic mechanization becomes easy. In addition, since the bonding surface of the coupling ring to the corrugated folds is a flat surface, the adhesive can be applied uniformly, so there is actually less variation in acoustic resistance, contributing to improved product quality and reduced manufacturing costs. It has excellent effects such as:

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a part of the diaphragm of a piezoelectric speaker that is an embodiment of this invention, FIG. 2 is a sectional view showing the structure of a piezoelectric speaker formed using the diaphragm of FIG. Fig. 3 is a perspective view showing a part of the joint between the diaphragm and the coupling ring in Fig. 2, Fig. 4 is a plan view showing the diaphragm of a conventional piezoelectric speaker, and Fig. 5 shows the diaphragm in Fig. 4. FIG. 6 is a cross-sectional view showing the structure of a piezoelectric speaker formed using the present invention, and FIG. 6 is a perspective view showing a connecting portion between the diaphragm and the coupling ring shown in FIG. In the figure, 1... diaphragm, 2... wave folds, 3
... Central dome part, 4 ... Arc part, 5 ... Triangular slope, 6 ... Edge part, 7 ... Flat part, 8 ... Frame, 9 ... Vibrator, 10 ... Weight, 11 ... …
Viscoelastic layer, 12... fixed end, 13... coupling ring, 14... outer edge end, 15... driving point, 16...
... terminal plate, 17 ... air chamber, 18 ... ring upper surface, 19 ... triangular groove, 20 ... gap, 21 ... adhesive plane, 22 ... flat surface, 23 ... distributed opening. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of utility model registration request] In a piezoelectric speaker whose excitation source is a piezoelectric vibrating element made of piezoelectric ceramics, etc., a large number of triangular feather-shaped wave folds are distributed radially from the central dome to the edge, which serves as a fulcrum supported by the surrounding frame. A bonding plane for inserting a coupling ring is formed at a drive point on the back side of each of the wave folds inside the fulcrum of the diaphragm, and a flat surface of the coupling ring inserted into this bonding plane is bonded, and each of the A piezoelectric speaker characterized in that each wave fold is configured to open a small acoustic opening that communicates with an air chamber surrounded by the coupling ring, the diaphragm, and the piezoelectric vibrating element.