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气导式压电晶体换能器可用于测定心尖搏动和颈动脉搏动。近年来,国内外测定心尖搏动和颈动脉搏动用的换能器大部分是直压式的,即换能器直接压在人体被检测部位上。当我们把这类换能器安缚在人体上进行测量时,就会给这种直压式换能器一种静压强P。,使晶体表面出现静电荷。该电荷要比心尖搏动产生的电荷大1～2数量级。从而使仪器发生讯号的另点漂移。同时这种静压强P_0对换能器有相当大阻尼,直接影响测量结果,也增加了压电晶体的机械弹性疲劳,甚
Air-conduction piezoelectric crystal transducers can be used to measure apical and carotid pulsations. In recent years, at home and abroad for the determination of apical beats and carotid beating most of the transducers are direct pressure type, that transducer directly pressure on the human body is detected on the site. When we attach such transducers to the human body for measurement, we give a static pressure P to the transducer. , So that the crystal surface electrostatic charge. This charge is one to two orders of magnitude larger than the charge generated by the apical beating. Thus causing the other point of signal drift of the instrument. At the same time this static pressure P_0 considerable damping on the transducer, a direct impact on the measurement results, but also increased the piezoelectric elastic mechanical fatigue, and even