JPH0287800A - External vibration type piezoelectric sounder - Google Patents

Abstract

PURPOSE:To avoid synchronization between melody and accompanyment and to prevent generation of a change in tempo, distortion of sound and unpleasant sound by splitting an electrode formed on a piezoelectric element into plural parts, connecting a lead wire to each electrode and inputting an acoustic signal. CONSTITUTION:An electronic sound source IC 5 incorporates an electronic circuit outputting an acoustic signal such as single melody or accompanyment or the like as a voltage with a different period. When the IC 5 is driven, a melody signal and an accormpanyment signal are outputted respectively to electrodes 4a, 4b. In this case, since a voltage with a different period is applied to the piezoelectric element 3, a counter electromotive force due to the interference between frequencies corresponding to the scale is not almost induced. Thus, the diaphragm 2 is vibrated in response to each acoustic signal and the melody and the accompanyment are not synchronized with each other and the change in the tempo, and deterioration in the sound quality such as distorted sound or unpleasant sound are avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the structure of a separately excited piezoelectric sounder that performs electroacoustic conversion according to the period of voltage change to produce a melody or accompaniment.

2. Description of the Related Art A separately excited piezoelectric sounder and a similar piezoelectric buzzer are known as electroacoustic transducers that introduce a plurality of acoustic signals and generate sound. These basic types, as shown in FIG. 5, have a piezoelectric element 3 on which an electrode 4 made of a highly conductive thin film such as silver is attached to a single metal diaphragm 2.

Lead wires 7 and 9 from a sound source (frequency signal generation source) are connected to each of the electrode 4 and the diaphragm 2, and the piezoelectric element 3, the diaphragm 2 is vibrated to produce a single sound or multiple sounds.

Problems to be Solved by the Invention However, since the electrode 4 is composed of one single piece, when the sounds overlap or when an accompaniment is added to the melody, the piezoelectric element 3, There was a problem in that the diaphragm 2 did not vibrate in proper synchronization, making it impossible to obtain high-quality sound.

Therefore, a method has been proposed in which another lead wire 8 is connected to the electrode 4 and a plurality of acoustic signals are inputted via each lead wire 7.8, as shown by the chain line in FIG.

However, even in this case, since the diaphragm 2 is driven by acoustic signals from a plurality of sound sources via one electrode 4, there is still a limit to the improvement in sound quality. In other words, in a typical piece of music that has a melody made up of two or more notes,
The timing of the main melody and accompaniment must be completely asynchronous. However, as mentioned above, 1 formed on the piezoelectric element 3
If a plurality of lead wires were connected to one electrode 4, the main melody and accompaniment would synchronize and change the tempo, resulting in distortion of the sound. Furthermore, since a plurality of voltages having different periods are applied to the same electrode 4, a back electromotive force is generated in the diaphragm 2, which affects the sound generation function and causes the sound to become cloudy.

Therefore, in order to avoid these problems and obtain good sound quality, it is possible to provide a number of separately excited piezoelectric sounders corresponding to the sound sources, but in this case, at least two or more separately excited piezoelectric sounders are required. This makes the structure complicated and the production cost inevitably high.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a separately excited piezoelectric sounder that has a simple configuration and can obtain audibly good sound quality even when a plurality of sound sources are input. Take it as a challenge.

Means for Solving the Problems In order to achieve the above-mentioned problems, the separately excited piezoelectric sounder according to the present invention divides the electrode formed on the piezoelectric element into a plurality of parts, and transmits an acoustic signal to each of the divided electrodes. It is characterized by connecting the input lead wire.

Function In the configuration described above, necessary acoustic signals are inputted to each of the divided electrodes formed on the piezoelectric element via lead wires. Therefore, when a single note is layered or an accompaniment is added to the melody, the melody and accompaniment will not be synchronized due to electroacoustic conversion, and the tempo of the pronunciation will not change or distortion of the sound will occur. . In addition, back electromotive force is less likely to be generated on the metal diaphragm, and generation of humming noise is also prevented.

Embodiments Hereinafter, embodiments of a piezoelectric sounder according to the present invention will be described based on the accompanying drawings.

[First Embodiment] FIG. 1 is a vertical sectional view of a separately excited piezoelectric sounder as a first embodiment. This separately excited piezoelectric sounder has a piezoelectric element 3 in which an electrode 4 is formed on a metal diaphragm 2 assembled to a horn 1, and the electronic sound fiIc shown in FIG.
It is equipped with 5.

The horn 1 is box-shaped and has a sound emitting port 1a at the center of the bottom plate, and the metal diaphragm 2 has a stepped portion 1b formed on the inner peripheral wall of the horn 1.
is fixed to. The electrode 4 is formed by dividing a highly conductive thin film such as silver into two at the center to form first and second electrodes 4a and 4b, and each electrode 4a and 4b has the same area. One ends of lead wires 7, 8.9 are connected to the picture electrodes 4a, 4b and the diaphragm 2 by soldering, respectively. Also, each lead wire 7°8.9 is connected to the notch 1 of bone 1.
The solder is connected to the wiring of the printed circuit board 6 fixed to the horn 1 through c. Further, the wiring of the printed circuit board 6 is connected to the electronic sound source IC5.

The electronic sound source IC5 receives an acoustic signal such as a single melody or accompaniment,
It has a built-in electronic circuit that outputs voltages with different periods, and a power supply voltage is introduced into input terminals a and b. and,
The output terminal C is connected to the first electrode 4a via the lead wire 7, and outputs a melody signal. Output terminal d is lead wire 8
It is connected to the second electrode 4b via the electrode 4b, and outputs an accompaniment signal. The input terminal is on the ground side and is read directly to the diaphragm 2 via a lead wire 9.

With the above configuration, when the electronic sound source IC5 is driven, a melody signal and an accompaniment signal are output to the first and second electrodes 4a and 4b. At this time, each electrode 4a.

4b, signals having frequencies corresponding to the intervals between each note are inputted from a single sound source.

However, for the piezoelectric element 3, the electrode 4a+4 divided into two
Since voltages with different periods can be applied through b, there is almost no possibility that one frequency signal will interfere with the other frequency signal and a back electromotive force will be induced. Therefore, the diaphragm 2 vibrates in accordance with each acoustic signal, eliminating the problem of the melody and accompaniment becoming muddy and deteriorating the sound quality.

By the way, in a typical musical piece in which the main melody is accompanied by an accompaniment, electroacoustic conversion between the main melody and the accompaniment must be performed completely asynchronously. In this embodiment, since voltage is applied to the piezoelectric element 3 from the electrodes 4a and 4b which are divided into two parts as described above, the main melody and accompaniment are not synchronized. Therefore, there are no problems such as changes in the tempo of pronunciation or out-of-order musical scales, and it is possible to obtain good sound quality with no perceptible distortion.

[Second and Third Embodiments] FIG. 3 shows a second embodiment in which the electrode 4 is divided into three equal parts, and FIG. 4 shows a third embodiment in which the area and shape of the electrode 4 are changed. As a result, the first, second and third electrodes 4a, 4b
, 4c by inputting each acoustic signal to the piezoelectric elements 3, 4c.
The diaphragm 2 can be driven at three different frequencies, making it possible, for example, to generate two types of double tones, a main melody and an accompaniment. On the other hand, since the sound pressure caused by the acoustic signal depends on the amount of charge of the separately excited piezoelectric sounder, in the example shown in FIG. 4, weighting can be given according to the area of each electrode 4a, 4b, 4c. Each electrode 4a, 4b, 4c
It is also possible to obtain different sound pressures.

As described in detail of the invention, the separately excited piezoelectric sounder according to the present invention has a structure in which the electrode formed on the piezoelectric element is divided into a plurality of parts, and a lead wire for inputting an acoustic signal is connected to each divided electrode. , 1! It is possible to generate sound by introducing an acoustic signal corresponding to the number of poles, such as a signal that overlaps a single tone or adds an accompaniment to a melody.

At this time, since the electrodes are divided, the melody and accompaniment are not synchronized, and sound distortion due to changes in the tempo of pronunciation does not occur, making it possible to obtain good sound quality. In addition, since voltages with different periods are applied through each electrode, the problem of muddying the sound due to back electromotive force as in the conventional case is eliminated, and it is also possible to improve the audibility. Furthermore, since it has a simple configuration in which lead wires are connected to each divided electrode, it also has the advantage of reducing manufacturing costs.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of a separately excitation type piezoelectric sounder showing a first embodiment of the present invention, FIG. 2 is a plan view showing a state in which an electronic sound source IC is connected to the other excitation type piezoelectric sounder, and FIG. FIG. 4 is a plan view showing a second embodiment of the invention, FIG. 4 is a plan view showing a third embodiment of the invention, and FIG. 5 is a plan view showing a conventional separately excited piezoelectric sounder. 2... Metal diaphragm, 3... Piezoelectric element, 4... Electrode, 4a, 4b, 4c... Divided electrode, 5... Electronic sound iIc. Patent applicant Murata Manufacturing Co., Ltd.

Claims (1)

[Claims] 1. In a separately excited piezoelectric sounder in which a piezoelectric element is attached to a metal diaphragm, the electrode formed on the piezoelectric element is divided into a plurality of parts, and a lead wire is provided to input an acoustic signal to each of the divided electrodes. A separately excited piezoelectric sounder characterized by: