压电式蜂鸣器构造与原理介绍 搭配, 蜂鸣器, 陶瓷片

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壓電式蜂鳴器構造與原理介紹　　壓電蜂鳴片是將高壓極壓化後的壓電陶瓷片黏貼於振動金屬片 上。當加入交流電壓後,會因為壓電效應,而產生機械變形伸展及收 縮，利用此特性使金屬片振動而發出聲響。
　　PIEZO BUZZER
　　以回授方式來做區分壓電蜂鳴片大致上分為回授式蜂鳴片(自 激式)與無回授式蜂鳴片(外激式)兩種。當回授式蜂鳴片搭配正回授 振盪電路會產生一個與共振腔頻率相同的單音;而無回授式蜂鳴片 則可以搭配外部振盪電路,選擇任意頻率發出聲音。
　　以下為兩種壓電蜂鳴片的固定方式: a. 週邊支持方式-將蜂鳴片外徑邊緣固定於共振腔內，一般採無 回授式蜂鳴片,而其蜂鳴片須與共振腔頻率搭配,才會有較高 的音壓輸出,並由外部振盪電路產生推動信號,使蜂鳴器發出 聲音.
　　b. 節點支持方式-將蜂鳴片固定於約與陶瓷片直徑同尺寸的環形 結構內。若共振腔設計得宜,並搭配頻率正確的回授式蜂鳴片 與正回授電路,將可產生較大音壓及正確的頻率。
　　以上兩種方式都需以矽膠粘合蜂鳴片於機構中。
　　Piezo buzzer structure and theory introduction
　　Piezoelectoric ceramic buzzer element have a simple structure in which piezoceramic element is glued to vibration plate. When alternating voltage is applied to piezoceramic element, the element expands or shrinks diametrically. This characteristic is utilized to make vibration plated bend to generate sounds. PIEZO BUZZER
　　The acoustic generating method can be roughly divided into self-drive oscillation method and external-drive oscillation method. The former shows the lowest impedance on the acoustic generator, and produces the sound by the positive feedback oscillation circuit to make resonance. Thereby, big sound pressure can be obtained by a simple circuit. While the latter selects an optional frequency and makes sound by the nonstable multivibrator, and it is used for the case having the oscillation circuit.
　　There are 2 support methods for piezoelectric ceramic buzzers products.
　　a. Circumference Fixing Method-This method is to fix the outside circumference of the buzzer element to the supporting ring of the plate. Considerable sound pressure can be obtained covering a wide frequency range around the resonant frequency.
　　b. Nodal Mounting Method-This Method is to fix the nodal diameter of the buzzer element to the supporting ring of the plate. Loud sound pressure can be obtained. Flexible adhesives, such as silicon rubber, should be used between the buzzer element and the support ring.