DEVELOPMENT OF NEW ULTRASONIC SENSORS UTILIZING EVANESCENT ACOUSTIC FIELDS

1. 研究了利用纵模压电振子产生的气膜阻尼效应进行接近传感。振动器由从140°旋转y形切割LiNbO_3晶圆上切下的细棒组成，该晶圆一端有玻璃板。玻璃板靠近作为测试对象的亚克力板。对于工作在80.9 kHz第一共振频率的振子，在振子与物体的距离d小于0.5 mm的范围内，q值从8,000显著降低到1,000。在有两条节点线的第二模式下运行时，初始q值减小到3500。然而，在第一种模式下，振动器可以得到更稳定的支撑。从这些结果可以证实，所提出的利用气膜阻尼效应的系统可以应用于接近传感器。短句来源当陷能振子的周围区域（振动能量随距离呈指数衰减）浸入液体中时，其电导率G随浸入深度的变化而变化。在2.01 MHz的频率下，用厚度-扩展型振动器进行了实验，结果表明，g值随浸没深度几乎呈线性变化。还发现，使用厚度剪切型振动器对高粘度液体是有效的。推导了沿边参数变化的侧镀压电杆的长-伸振动模态的等效网络表示。该网络模型适用于具有抑制泛音模式的特殊电极形式的振子的运行仿真。该模型还可以有效地模拟用于激发和探测表面声波（saw）的数字间换能器（idt）的操作。少

1. Proximity sensing through the air-film damping effect caused by a longitudinal-mode piezoelectric vibrator has been studied. The vibrator is composed of a thin bar cut out from a 140° rotated Y-cut LiNbO_3 wafer having a glass plate on one end. The glass plate is approached to an acrylic plate served as a test object. It has been found for the vibrator operating at the first resonant frequency of 80.9 kHz that the Q-value decreases markedly from 8,000 to 1,000 in the range where the vibrator-to-object distance d is less than 0.5 mm.2. For the case of operation at the second mode having two nodal lines, the initial Q-value decreases to 3, 500. However, the vibrator can be supported more steadily than that in the case of the first mode operation. From these results, it has been confirmed that the proposed system utilizing the air-film damping effect can be applied for a proximity sensor.3. Trapped-energy mode thickness vibrators have been fabricated and applied for liquid level sensor … More s. When the surrounding region of the trapped-energy-mode vibrators, where the vibration energy decays exponentially with distance, is immersed in a liquid, the electric conductance G varies depending on the immersion depth. The experiments carried out using a thickness-extensional-mode vibrator operating at the resonance frequency of 2.01 MHz have shown that the G-value varies almost linearly with the immersion depth. It has also been found that the use of thickness-shear-mode vibrators is effective for liquids having high viscosity.4. Equivalent network representation has been derived for length-extensional vibration modes in a side-plated piezoelectric bar with a varying parameter along it. The network model is applicable to the simulation of the operation of vibrators that have a special electrode form devised for suppressing overtone modes. The model is also effective for modeling the operation of interdigital transducers (IDTs) for excitation and detection of surface acoustic waves (SAWs). Less