02-2 压电扬声器送受话器-CH EN OK

四、压电陶瓷扬声器Pi ezoelectric ceramic speaker
图2.12所示,是一种改善了中、低频特性压电陶瓷扬声器。

它是由三个压电陶瓷振子5和一个压电陶瓷振子6所组成。

压电陶瓷振子5的直径为21毫米，6的直径为27毫米，3为压电陶瓷片，4为振动板，直径为50毫米。

1为纸质圆锥形振动板4的边缘部分与有底框2的开口边缘连接。

这种结构的扬声器，音频讯号将同时加在第一和第二层压电陶瓷振子5和6上，因此各振动片都是同相位的弯曲振动，从而驱动振板4将获得较大的振幅，如图2.12(b)所示的虚线和实线的距离。

Fig.2.12. It is one kind Piezoelectric ceramic speaker of improvement middle and low frequency.It is composed of three piezoelectric ceramic vibrators 5 and a piezoelectric ceramic vibrator 6. The piezoelectric ceramic vibrator 5 of diameter is 21 mm, the diameter of 6 is 27 mm, 3- the piezoelectric ceramic disk , 4-the vibration disk, and the diameter is 50 mm. 1 is the paper cone vibration plate edge portions of 4 and a frame of 2 connected with an opening edge.
The structure of speaker, the audio signal input the first and second piezoelectric ceramic vibrators o 5 and 6 at the same time, so that the bending vibration is the same of phase, It will drive vibration plate 4 to produce a larger amplitude, as shown in Fig.2.12 (b) the distance of the dashed and solid lines.
图2.12 (a) 剖面图
6
5 5
图2.12 (b) 振动工作示意图
f
图2.12 改进型压电陶瓷扬声器
图2.13为此种压电陶瓷扬声器的频响特性，虚线是单一结构的压电陶瓷扬声器的特性曲线。

由图可见，这种压电陶瓷扬声器在100-5000Hz频率范围内，有足够的放音声压，低频部分的声压特别明显。

图2.13 改进型压电陶瓷扬声器的频率响特性
放音频率 Hz
Fig.2.13 shown the frequency response characteristics for this kind of piezoelectric ceramic speaker; Dash line is the piezoelectric ceramic loudspeaker characteristic curve for the single structure.
Seen by the graph, the frequency range of piezoelectric ceramic speaker within the scope of 100-5000Hz, there is the enough sound pressure level of sound reproduction, the sound pressure level is Special obvious in the low-frequency range.
五、压电陶瓷受话器Pi ezoelectric ceramic receiver
压电陶瓷受话器具有重量轻、不怕电磁干拢等特点而受到重视，由于此受话器具有良好的防潮性能，主要使用在轻潜水通讯设备中。

由图2.19可见，它是由三个自由度音响振动系列构成。

振动板1由压电陶瓷片和薄金属片用导电胶粘结而成，经由框架2固定于内框上。

于是将受话器腔体分为：第一前气腔5与第一后气腔6，第二前气腔7（耳机）通过传声孔3与第一前气腔5相通，第一后气腔6由阻尼孔与外空间相连。

当交流信号由引线端8输入时，振动
板便随外加信号产生伸缩振动，其所产生的声压，由第二前气腔7引出，即可听到声音。

其频响特性如图2.20所示，图中实线是没有泄露时的特性，点划线是听筒紧贴耳朵压力为700g 时的特性，虚线是200g 的特性。

图2.19 压电陶瓷受话器
1.振动板；
2.框架；
3.传声孔；
4.阻尼孔;
5.第一前气腔；
6.第一后气腔；
7.第二前气腔；
8.引线端
-30
-20 -10 0
10 20 125
2505001K
2K 4K
图2.20 压电陶瓷受话器频响特性图
It has received attention because the advantage of piezoelectric ceramic receiver there is light weight, no electromagnetic interference (EMI) characteristics etc, the product has good moisture resistance, used in lightweight diving communication equipment mainly. Fig.2.19, it is composed of three degrees of freedom sound vibration. 1- the vibration plate, its edge on the inner frame 2: the edge of metal is fixed and bonded by electric conduction paste between the piezoelectric ceramic disk and the thin metal disk. Then the receiver chamber is divided into: 5-the first front air chamber and 6-the first behind air chamber, 7-the second front the air chamber( headphones ) and the first front air chamber 5 connected by 3-the sound hole, the first behind air chamber and the outside space connected by damping hole. When the AC signal input through 8- the terminal wire, the vibration will generate the stretching vibration with an external signal, the generating sound pressure level was leaded through the second front air chamber, So we can hear the sound.
The frequency response characteristics as shown in Fig.2.20, the solid line is no reveal, the point line is close to
the ear, the pressure is 700g, the dotted line is close to the ear, the pressure is 200g.
图2.19 压电陶瓷受话器
1.振动板；
2.框架；
3.传声孔；
4.阻尼孔;
5.第一前气腔；
6.第一后气腔；
7.第二前气腔；
8.引线端
-30
-20 -10 0
10 20 125
2505001K
2K 4K
图2.20 压电陶瓷受话器频响特性图。