JPS60186200A - Piezoelectric diaphragm - Google Patents

Abstract

PURPOSE:To obtain the piezoelectric diaphragm which has higher acoustic transducing efficiency than a conventional piezoelectric diaphragm by sticking a lightweight elastic thin plate which seals an opening on a circular piezoelectric ceramic plate. CONSTITUTION:The circular piezoelectric ceramic plate 7 is stuck on a circular elastic thin plate 4. An opening consisting of a hole 10 and slits 11 in the same as the opening consisting of a hole 5 and slits 6 formed in the thin plate 4 is formed in the ceramic plate 7 and electrodes 7 and 8. The thin plate 4 and ceramic plate 7 are stuck one over another so that the openings coincide with each other. Then, the circular lightweight elastic body 12 is stuck on the other side of the thin plate 4, i.e. at the opposite side of the ceramic plate 7. Consequently, a large amplitude is obtained by the piezoelectric diaphragm of conventional bimorph structure and the whole body is flat, so the acoustic transducing efficient is improved greatly because of flectional oscillations.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a piezoelectric diaphragm used in electroacoustic transducers using various piezoelectric elements such as piezoelectric buzzers, piezoelectric speakers, and ultrasonic ceramic microbons.

Structure of the conventional example and its problems A conventional piezoelectric diaphragm used in an electroacoustic transducer is made of an elastic body such as a metal plate, as shown in FIGS. Most of them have a bimorph structure in which a thin plate 1 and a piezoelectric ceramic plate 3 having electrodes 2 on both sides are bonded together with an adhesive or the like, and the most common shape is circular.

In such a piezoelectric diaphragm, pressure '- is converted into spreading vibration or bending vibration of the piezoelectric ceramic plate 3 by applying an alternating voltage to the electrodes 2 provided on both sides of the ceramic plate 3, and operates as an electroacoustic transducer. It is well known that As a method of supporting and fixing such a circular piezoelectric diaphragm, there are a method of supporting and fixing the outer periphery of the piezoelectric diaphragm, a method of supporting the inside of the outer periphery, and the like.

Pressure vibration used in such electroacoustic transducers! ] One of the most important characteristics for Kaboard is sound 145 conversion efficiency,
? It is desirable that the acoustic output is as large as possible with respect to the voltage applied to the Li pole 2. For that purpose, shake the pressure′・1χ diaphragm! The fII amplitude (vibration displacement) must not become as large as possible.

The vibration amplitude of a conventional piezoelectric diaphragm as shown in FIG. 1 is determined by its external dimensions, the method of supporting and fixing it, the material constant of the thin elastic plate 1, the pressure C; However, the increase in amplitude by these combinations has almost reached its limit, and it is currently difficult to hope for an improvement in the acoustic conversion efficiency unless there is a significant improvement in the piezoelectric constant.

If you want to obtain a large deflection amplitude, one side of the bimorph diaphragm, which is a rectangular plate-shaped bimorph diaphragm made by laminating a rectangular piezoelectric ceramic plate with 1b poles on both sides and a thin elastic plate, with a supporting material. A fixed piezoelectric diaphragm with a so-called cantilever structure provides a large deflection amplitude at its tip. however'
(i) Since the piezoelectric diaphragm used in the i-air sound auxiliary device must convert its vibrations into compressional waves in the air, the diaphragm with such a cantilever structure alone cannot convert It cannot be used as a vessel.

OBJECTS OF THE INVENTION The present invention is based on a method that directly performs the ``Ichi-Otoya'' transformation using the deflection amplitude of the pressure ``+-1i'' temporary storage, as in the conventional circular piezoelectric swing J-plate as shown in Figure 1. Breaking away from the current situation, using conventional materials and the conventional piezoelectric diaphragm's
? q 4! , 4H' conversion efficiency.

Structure of the Invention The present invention provides an opening consisting of a circular hole in the center of a circular elastic thin plate or a first circular piezoelectric ceramic plate and a small number of slits extending radially from the hole to the periphery. Elastic body plate or first circular pressure? a of the porcelain plate -(
+11! A second circular piezoelectric ceramic plate is bonded to the second circular piezoelectric ceramic plate, and the second circular piezoelectric ceramic plate is attached to An opening consisting of a circular hole and a slit is provided on the other side of the second circular piezoelectric ceramic plate or the circular elastic thin plate or the first circular pressure '[)N4+f
Light 1i elasticity that honeymoons the above opening on the other side of the plate::, 11
This is a piezoelectric vibrator for electroacoustic transducers made by bonding plates together.

The series of circular elastic thin plates can be any conventionally used thin plates, such as metal plates, and the first and second circular piezoelectric ceramic plates can also be made of conventional materials. It goes without saying that electrodes are provided on both sides of these circular piezoelectric ceramic plates.・l・F j The elastic thin plate will be described later.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

Fig. 2 shows the decomposition 1 threshold showing the pressure ν ([elastic thin plate constituting the diaphragm, piezoelectric ceramic plate, light) i elastic thin plate according to the present invention, and Fig. 3 shows the decomposition 1 threshold of the piezoelectric diaphragm according to the non-explosion [su J]. FIG.

Reference numeral 4 in FIG. 2(A) is a circular elastic thin plate such as a thin metal plate, and an opening consisting of a circular hole 5 and a plurality of slits 6 extending radially from the hole toward the periphery is provided in the center. It is. As shown in FIG. 3, a circular piezoelectric ceramic plate 7 made of a conventionally used material shown in FIG. 2 (13) is bonded onto the circular elastic thin plate 4. Of course, this circular piezoelectric ceramic plate 7 is provided with electrodes 8 and 9 on both the front and back surfaces (see FIG. 3, 4).

In addition, this circular piezoelectric ceramic plate 7 and electrodes 8 and 9 (second
(not shown in Fig. 2(B)) is provided with an opening consisting of a hole 10 and a slit 11 having the same shape as the opening consisting of the hole 5 and slit 6 provided in the circular elastic thin plate 4 of Fig. 2(A). put. When the circular elastic thin plate 4 and the circular piezoelectric iG device plate 7 are bonded together, their openings are made to coincide with each other. Next, according to this embodiment of the present invention, FIG.
A circular lightly bonded elastic thin plate 12 as shown in FIG. Light jl) The elastic thin plate 12 is made as light as possible so as not to be a load on the bimorph diaphragm composed of the circular elastic thin plate 4 and the circular piezoelectric ceramic plate 7 (so that the opening can be sealed, and the vibration form of the diaphragm is It is preferable to make it from a material with high elasticity that allows it to move freely, and it is preferable to use rubber or foamed polyethylene.

As another embodiment of the present invention, the central opening of the circular piezoelectric ceramic plate 7 used in the present invention has only a circular hole 10 and a slit 1.
1 may not be provided. However, in this case, the conversion efficiency is slightly lower than when the slit 11 is provided, but it is advantageous in manufacturing, that is, in terms of mass production, since it is not necessary to form the slit.

In the above embodiment, the lightweight elastic thin plate 12 is attached to the circular elastic thin plate 4 as shown in FIG. 3, or in another example, it may be attached to the circular piezoelectric ceramic plate 7. In another embodiment, the same circular piezoelectric ceramic plate as the circular piezoelectric ceramic plate 7 may be used instead of the circular elastic thin plate 4, and two circular piezoelectric ceramic plates 7 may be stacked to form a bimorph structure.

The openings (circular holes or circular holes and slits) of the circular elastic thin plate 4 and the circular piezoelectric ceramic plate 7 may be drilled in advance and then bonded together; Holes may be formed by laser processing or the like after the layers are formed into a laminated state.

Effects of the Invention The piezoelectric diaphragm according to the present invention has a structure in which a large number of bimorph diaphragms with a cantilever structure are arranged radially by supporting and fixing the outer periphery of the piezoelectric diaphragm.
2, it is possible to obtain a larger amplitude than the conventional bimorph structured piezoelectric diaphragm shown in Fig. 1, and since the entire structure is flat, bending vibration Therefore, the acoustic conversion efficiency is also very high. The piezoelectric diaphragm according to the present invention has a diameter of about 1.3 to 1
．． Five times the vibration amplitude can be obtained. Therefore, the piezoelectric diaphragm according to the present invention is a very practical high-Q material that greatly improves acoustic conversion efficiency when used in an electroacoustic transducer.

[Brief explanation of the drawing]

FIG. 1 shows a plan view (A) and a side view (B) of a conventional piezoelectric diaphragm, and FIG. 2 shows an elastic thin plate, a piezoelectric ceramic plate, and a lightweight elastic thin plate constituting the piezoelectric diaphragm according to the present invention. FIG. 3 is an exploded view showing a side wall 1 of an example of a piezoelectric diaphragm according to the present invention. 04 is a circular elastic thin plate, 5 is a hole, 6 is a slit, 7 is a circular piezoelectric ceramic plate, 8 and 9 is an electrode, 10 is a hole, 11 is a slit, and 12 is a lightweight elastic thin plate. Patent applicant: Matsushita Electric Industrial Co., Ltd. ~ Figure 3

Claims (1)

[Claims] 1. An opening consisting of a circular hole and Jj number of slits extending radially from the hole toward the periphery is provided in the center of the circular elastic thin plate or the first circular piezoelectric ceramic plate, and A second circular piezoelectric ceramic plate is bonded to one side of the circular piezoelectric ceramic plate, and an opening consisting of a circular hole that matches the circular hole is provided in the second circular piezoelectric ceramic plate, or an opening consisting of a circular hole and slit that corresponds to the hole and slit of
An electroacoustic device characterized in that a light elastic thin plate for sealing the opening is bonded to the other side of the second circular piezoelectric porcelain plate, the circular elastic thin plate, or the other side of the first circular piezoelectric ceramic plate. Pressure fji dvj board for converter.