JPH05249979A - Piezoelectric sound producing body - Google Patents

Abstract

PURPOSE:To provide a piezoelectric sound producing body in which a sound can be released with a different tone even when the signal voltage and frequency of a driving source are constant, and clearly distinguished and identified from the sound of another sound producing body by providing a hole area variable disc for changing the hole area of a sound releasing hole by vibration, and changing the hole area by the rotating position angle of the disc to change the tone. CONSTITUTION:A sound releasing hole 5 has a hole area variable means 6 for changing the hole area of the sound releasing hole 5 by the vibration of a case body 1. The hole area variable means 6 is formed of, for example, a disc (rotating blade plate) 61 having a diameter slightly smaller than the hole diameter of the sound releasing hole 5, and both ends of a shaft 2 mounted on the disc 61 are mounted rotatably to the hole inner circumferential wall of the sound releasing hole 5. The disc 61 in the sound releasing hole 5 is rotated by the fine vibration of the case body 1, and the hole area of the sound releasing hole 5 is changed by the rotating position angle of the disc 61. When the produced sound resonated and extended in a resonant air chamber 4 is released to the outside through the sound releasing hole 5, thus, the resonance frequency is changed depending on the size of the hole area of the sound releasing hole 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric sounding body used for sounding various alarm devices.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view showing a conventional piezoelectric speaker. This piezoelectric speaker is a case body 1 with a bottom opening and a bottom.
And a piezoelectric vibrator 2 that is fitted and fixed inside the case body 1, and a fixing cap body 3 that fixes the peripheral edge of the piezoelectric vibrator 2 to the case body 1. The piezoelectric vibrator 2 has a piezoelectric ceramic element (ceramic piezoelectric body) 22 attached to the lower surface of a metal plate 21, and has an input terminal 23 connected to the metal plate 21 and an input terminal 24 connected to the piezoelectric ceramic element 22. Are led out from the cap body 3 respectively. In this state, the piezoelectric vibrator 2 and the case body 1
The inner space of and is set as the resonance air chamber 4. Further, a sound output hole 5 is opened in the surface of the upper surface wall 11 of the case body 1.

When the piezoelectric vibrator 2 vibrates due to the signal voltage from the drive source, this vibration is resonantly expanded in the resonance air chamber 4, and a sound is emitted from the sound output hole 5.

[0004]

The piezoelectric sounding body is driven by the signal voltage of an external circuit. In recent years, with the development of ICs and utilization of microcomputers, the frequency of driving the sounding body is also dividing the clock of the microcomputers. Therefore, the sound to be generated is similar to the sound, which is difficult to distinguish. That is, the sound emitted from the sound output hole becomes a sound of a certain constant frequency, and a sound similar to the sound of the drive signal source is generated, which is disadvantageous in that it is difficult to distinguish.

An object of the present invention is to solve the above problems and to provide a piezoelectric sounding body which can change the tone color without changing the voltage and frequency of the input signal and which can be easily recognized. .

[0006]

In order to achieve this object, the piezoelectric sounding body of the present invention has the following structure. The piezoelectric sounding body is a piezoelectric sounding body in which a sound emitting hole is opened at an appropriate position of a case body in which a piezoelectric vibrator formed by adhering a ceramic piezoelectric element to a metal plate is housed and arranged. The present invention is characterized in that the hole area varying means for changing the hole area of the sound output hole by the vibration of the case body is provided.

In the piezoelectric sounding body having such a structure,
A hole area varying means is provided in the sound output hole. The hole area varying means is, for example, a rotatable disc that is axially mounted on the inner peripheral surface of the hole. When the piezoelectric vibrator vibrates due to the signal voltage of the external circuit, the case body also vibrates slightly. Due to this slight vibration of the case body, the disk (rotating blade) pivotally supported by the sound output hole of the case body rotates. When the rotary blade rotates within the sound output hole, the hole area of the sound output hole changes, and the volume of sound emitted from the sound output hole changes. In other words, the frequency of the sound fluctuates depending on the rotational position angle of the disk, a modulated sound is emitted, and a tone color completely different from the sound of the drive source is obtained, so that the sound can be completely discerned.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing a specific embodiment of the piezoelectric sounding body according to the present invention.

As is well known, the piezoelectric speaker has a case body 1 having a bottom with a lower opening, a piezoelectric vibrator 2 fitted and fixed in the case body 1, and a peripheral edge of the piezoelectric vibrator 2 as a case. The fixing cap body 3 is fixed to the body 1. The piezoelectric vibrator 2 has a piezoelectric ceramic element (ceramic piezoelectric body) 22 attached to the lower surface of a metal plate 21, and has an input terminal 23 connected to the metal plate 21 and an input terminal 24 connected to the piezoelectric ceramic element 22. Are led out from the cap body 3 respectively. In this state, the internal space between the piezoelectric vibrator 2 and the case body 1 is set as the resonance air chamber 4. In addition, the sound output hole 5 is provided in the upper surface wall 11 of the case body 1.
Is open.

A feature of the present invention is that the sound emitting hole 5 is provided with a hole area varying means 6 for changing the hole area of the sound emitting hole 5 by the vibration of the case body 1. Pore area changing means 6
In the embodiment, is a disk (rotating blade) 61 having a diameter slightly smaller than the hole diameter of the sound output hole 5, and both ends of a shaft 62 attached to the disk 61 are the inner wall of the sound output hole 5. On the other hand, it is rotatably attached.

In the piezoelectric sounding body having such a structure,
The input terminals 23 and 24 are connected to a drive source (not shown) of an external circuit, and the piezoelectric vibrator 2 vibrates by a signal voltage (constant frequency) from the drive source. Due to this vibration, the case body 1 also vibrates slightly. The minute vibration of the case body 1 causes the disc 61 in the sound emitting hole 5 to rotate, and the hole area of the sound emitting hole 5 changes depending on the rotational position angle of the disc 61. Therefore, when the sound expanded by resonance in the resonance air chamber 4 is emitted from the sound emitting hole 5 to the outside, it is emitted by the rotational position angle of the disc 61 (the size of the hole area of the sound emitting hole 5). Sound pressure changes (resonance frequency changes). As a result, even if the voltage and frequency of the drive signal are constant, the timbre of sound emitted from the sound output hole 5 changes.

[0012]

As described above, according to the present invention, since the disk for varying the hole area, which changes the hole area of the sound emitting hole by vibration, is provided, the hole area changes depending on the rotational position angle of the disk. By doing so, the timbre emitted can be changed. Therefore, even if the signal voltage and frequency of the driving source are constant, it is possible to emit a completely different timbre, and clearly distinguish between the sound of the driving signal source and the sound of other sounding bodies of the same structure. It has an excellent effect of achieving the object of the invention such as being recognizable.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example piezoelectric speaker.

FIG. 2 is a sectional view showing a conventional piezoelectric speaker.

[Explanation of symbols]

 1 Case body 2 Piezoelectric vibrator 5 Sound emission hole 6 Hole area varying means

Claims (1)

[Claims] 1. A piezoelectric sounding body in which a sound emitting hole is opened at an appropriate place of a case body in which a piezoelectric vibrator formed by adhering a ceramic piezoelectric element to a metal plate is housed and arranged. A piezoelectric sounding body comprising a hole area varying means for changing a hole area of a sound emitting hole by vibration of a case body.