02-5-超声仪器上应用-压电超声波清洗-传声器-医疗-雾化器CH-EN-OK

九、超声清洗和熔接用换能器Ultrasonic cleaning & weld transducer超声波清洗机，塑胶熔接机用的压电陶瓷换能器的工作频率一般在20500KHz 范围。在低频（2050KHz）大功率场合，多使用以螺栓紧固的郎之万换能器，在低频小功率（50100W）的场合，用径向模式振动的圆形单片或圆筒形换能器，在高频（50KHz以上）场合，则使用厚度振动的圆片或方片状单片换能器。 螺栓紧固郎之万行换能器结构如图1，其紧固的方式有：外螺栓紧固，中心螺栓如、四周螺栓紧固等三种。 塑胶熔接用换能器，根据不同的熔接要求，熔接功率要求大小，其后盖加工成不同的形状。In general, the working frequency of piezoelectric ceramic transducer ranges from 20 to 500 KHz on the application of ultrasonic cleaning machine. In low frequency (20 - 50KHz) and high-power condition, Langevin transducer with bolt tightened is widely used, while in the low frequency (50 - 100W) and low power condition, cylindrical transducer or cyclo-monolithic transducer with radial vibration mode will be used, while in high frequency condition, monolithic transducer in square-shaped or in disc-shaped with thickness vibration. Langevin transducer with bolt tightened is shown in Fig.1. There are three tighten methods, they are outside bolt, center bolt and round bolt. 十、超声波传感器Ultrasonic sensor 超声波陶瓷测距器是利用压电陶瓷的电能机械能相互转换的功能，在压电陶瓷上加一电信号后，产生机械振动，发射超声波；而当超声波振动作用于压电陶瓷时，就会有电信号输出。Ultrasonic ceramic ambulator utilizes piezoelectric ceramics mutual transformation between electric energy and mechanical energy. The electrical signal added on the piezoelectric ceramic generates mechanical vibration and transmit ultrasonic. Electrical signal outputs while ultrasonic vibration acting on the piezoelectric ceramic. 1、通用型超声波传声器 Universal ultrasonic ceramic microphone通用型超声波陶瓷测距器结构如图3，在用两片直径为8.0mm、厚度为0.3mm的压电陶瓷粘合成双膜片振子的中央，开0.8mm的孔，且孔中粘有铝制圆锥状谐振子，再把压电谐振子的结圆部分弹性固定在底板上。当传声器用作接受超声波用时，超声波信号由圆锥谐振子汇集并通过轴向传导至双膜片中央，双膜片谐振，进而在压电元件的两面的电极产生信号电压；如若加信号电压于双膜片振子时，双膜片振子产生振动，再由圆锥状谐振子向空中发射超声波，因为超声波传声器利用压电陶瓷振子的谐振特性，所以发射时输出的声压和接收时的灵敏度都具有频率选择性。图4例示了这种器件的频率特性。 Universal ultrasonic ceramic ambulators structural drawing is shown in Fig.3. Punch a 0.8mm diameter in the center of double diaphragm oscillator bonded with two pieces of piezoelectric ceramics in 8.0mm diameter and 0.3mm thickness, adhere aluminum and cone-shaped harmonic vibrator in the hole and fasten elasticity of piezoelectric harmonic vibrators round part. When microphone is used as receiving ultrasonic, the ultrasonic signal converges with cone-shaped and conduct to the center of double diaphragm with axial trend and make it resonant. It generates signal voltage on the electrode of piezoelectric elements both sides. The double diaphragm oscillator vibrates while receiving signal voltage, it transmits ultrasonic wave in the air via cone-shaped harmonic vibrator. The ultrasonic microphone utilizes piezoelectric ceramic oscillators resonance characteristic, thus its output sound pressure level while transmitting and response rate while receiving have the characteristic of frequency alternative. The Fig.4 illustrates the frequency characteristic of this device. 2、防水型超声波测距器（倒车雷达）Waterproof-type ultrasonic ceramic ambulator (parking sensor) 防水型传声器具有是水滴和灰尘难于附着的特点，其形状是密封型；振动外壳的设计，要考虑到压电陶瓷元件便于粘贴在外壳上而成为一体，还要能形成高效的振动部分；振动外壳的侧面既要便于与计测仪器装配，又不要影响振动。图5显示了较好能满足上述要求的振动外壳结构。如图所示，圆锥台形振动外壳的上内侧粘有压电元件，该振动外壳的上部分成为振动部分。图6是防水型超声波陶瓷传声器的结构图。 The waterproof type microphone has the characteristic of being difficult to adhere the drip and dust, it is sealed type in shape. We design the vibrating shell, not only need to consider piezoelectric ceramic element easily adhering the shell and becoming one but also to form high-efficiency vibration. The vibrating shells flank needs to be both easy to assemble with measuring devices and not to affect its vibration. Fig.5 illustrates well the vibrating shells structure of meeting requirements demand, as shown in figure, the cone-shaped vibrating shells inside adheres piezoelectric element, and it is vibration in its top part. Fig.6 illustrates the structure of waterproof-type ultrasonic ceramic microphone.3、窄指向型超声波传声器Narrow point type ultrasonic ceramic microphone 超声波用于照相机自动对焦距等准确测距方面，超声波波束的指向性必须尖锐；又为快速准确测距，必须要求这种超声波传声器的脉冲响应优越，过渡性良好，灵敏度高。此种器件的结构如图7所示；其音响变换部分与通用型超声波陶瓷传声器的相同，在双膜片的中央部分用结合轴与圆锥状谐振子连成为一体。在圆锥状谐振子的边缘部分装有圆环状弹性橡胶减震器，使之与圆筒状外壳固定。在电-声变换部分的前面，设有超声波波束整形板，它是对应锥状谐振子的振动模式设置了几个开口。超声波波束整形板能使在装喇叭板的情况下，不仅波束指向性尖锐，且具有能显著地抑制波束旁瓣的作用。 The ultrasonic wave is applied in automatic focus of camera, accurate location and other fields, whose directivity of beam must be sharp. It must demand the ultrasonic microphones impulse in superior response, good transitivity and high sensitivity to measure fast and accurately. This devices structure is as shown in Fig.7, and its sound transform is the same with general type ultrasonic ceramic microphone. It becomes one with axis of combination and cone-shaped harmonic oscillator in the center of the double diaphragm. In the cone-shaped harmonic oscillators edge, it is assembled with round-shaped elastic rubber shock absorber to fasten with cylindrical shell. In front of electricity-sound part, the ultrasonic beam plastic plate sets several opening to correspond to vibrating mode with the cone-shaped harmonic oscillator. It can not only make the beam sharp but also prominently restrain its side lobe while assembling horn support plate.十一、医用超声波诊断仪器（B超）Medical transducer超声波脉冲诊断，是具有指向性的超声波脉冲射向人体的有关部位，由于人体内部组织的声学阻抗（密度与声速的积）不同，就会产生不同形状、不同时延的反射波，从反射波的形状和反射波的回波时间可以探知反射对象，并对其做出病理诊断。The transducer of ultrasonic medical equipment utilizes piezoelectric ceramic, which is applied in diagnosis and treatment.使用时，手持探头触及被诊断部位，在诊断部位涂覆液体石蜡等传播介质，通过这种液体向人体内部器官发射或接收超声波，图8是脑神经外科常用来诊断紧急外伤引起的颅内血块。检测时，使用两个检测探头，从曲线BE部分与IC部分的差异，即可判断出血块的准确位置。Ultrasonic pulse diagnosis refers that directional ultrasonic pulse beams on the relative parts of human body, the reflected wave of different shape and time delay is generated with different acoustic impedance (product of density and sound velocity) of human bodys interior tissue. The reflection object can be ascertained from the shape and echo time of reflected wave. Pathological diagnosis is made. It is classified as A mode, B mode and C mode according to different notations of oscillight.用超声波波束扫描，并用超声波回波信号强弱来控制显像管的辉度变化，因为灰点扫描和超声波波束同步，从而得到以灰度变化为特征的超声波束横剖人体的断面层像。 B model diagnosis way utilizes ultrasonic beam to scan and control oscillights brightness changes with ultrasonic echo signals strength. Because of the synchronization of dot scanning and ultrasonic beam, it appears the humans axial tomography sectioned by ultrasonic beam with the characteristic of brightness changes.Its principle refers that utilize electronic switch to successively transform as vibrator and range several vibrators in straight line to make ultrasonic beam do linear movement. It illustrates in Fig.9.线性电子扫描超声波诊断的例子如图10所示。其探头是由200个宽0.5mm、厚1mm、长12mm的压电陶瓷振子直线排列而成，用电子电路按每次驱动20个振子的顺序扫描，其振子频率为2MHz。用这种方式，能以每秒12.5幅的速度，描绘出宽16cm、长25cm的断面层像。Fig.10 illustrates ultrasonic diagnosis with linear scan. Its probe consists of 200 piezoelectric ceramic vibrators ranged in straight line that is 0.5mm wide, 1mm thick and 12mm long. It utilizes sequential scanning of electronic circuit driving 20 vibrators each time, and its vibrator frequency is 2MHz. By using this way, it can describe an axial tomography in 16cm width and in 25cm length at the speed of 12.5 pictures per second.十二、压电超声雾化器Piezoelectric ultrasonic atomizer压电陶瓷超声雾化器，直接能将液体雾化成13m的微粒。机理如下：在图11的装置中，超声信号传输到做厚度振动的压电陶瓷振子上，振子的机械振动传给水，使水面隆起，并在隆起的周围发生空化作用，空化作用所产生的冲击波将以振子的振动频率不断反复振动，使水面上产生有限振幅的表面张力波，这种波的波头飞散，使水雾化，雾化的粒子由内藏的风机送出。Piezoelectric ceramic ultrasonic atomizer can directly atomize liquids into 13m particles. The principle is as follows, in the device of Fig.11, ultrasonic signal transmits on piezoelectric ceramic vibrator making thick vibration, it causes mechanical vibration to make water hunch and cavitation happen. The impulse wave generated by cavitation constantly repeat vibration with vibrators frequency, which makes water generate capillary wave with finite amplitude. This kind of waves head flies off, which atomizes water. Atomized particles are sent out via draught fan hidden inside. 图12给出超声波雾化器用压电振子的尺寸形状一例。极化时，环形电极和中心部分电极为同电位，与其相对的为主电极。环形电极仅在极化时使用，以使厚度方向的极化较均匀，从而使得在工作时振动畸变小，振动也较稳定。主电极直径D和中心部分电极直径d之比，一般取2.5D/d1.2,若超出这个比值，会使雾化量大幅下降。Fig.12 illustrates the size shape of ultrasonic atomizer with piezoelectric vibrator. The annular and central electrodes are idiostatic, and the opposition is main electrode. The annular is used only under polarization, which balances thick polarization. It diminishes the vibrating deformity while working and vibrates stably. The ratio of main electrodes diameter D and central electrodes diameter d ranges from 2.5D/d1.2, and it substantially decreases atomization if the ratio is beyond the range.十三、压电超声马达Piezoelectric ultrasonic motor超声压电马达由转子和定子组成，在转子和定子中至少应有一个压电振子作为驱动源。超声马达按振子在转子或定子中的状态分为无源转子式、无源定子式、有源转子和定子式等三种结构。图13是无源转