驻极体电容传声器温度特性分析和改进对策

着重讨论了驻极体电容传声器的温度特性,分析了影响驻极体电容传声器温度特性的主要因素：振膜、J-FET等对驻极体电容传声器性能的影响,弄清温度特性对这些特性的作用,这对改进工艺,获得稳定的、高性能的传声器有参考意义。另外．还对改善ECM温度特性的对策作了说明。     

振膜系统材料特性对传声器相关特性影响分析

讨论了驻极体电容传声器的生产中作为零件的振膜在制成中的材料特性对驻极体电容传声器的影响。文中着重对灵敏度、共振频率、温度特性等进行了讨论。     

不同结构部件的等效电容对ECM灵敏度的影响

对于驻极体电容传声器(ECM),不同结构部件的等效电容,对灵敏度的影响不同.在掌握了不同类别电容对灵敏废的影响机理之后,在单体设计时,对不同部件进行针对性的设计,以便按需调节单体的灵敏度.主要探讨了振膜的有效电客和传声器内部的寄生电容这两者对灵敏度的影响,以及各部件对相应电容的影响.     

ECM电容及其对ECM特性影响的讨论

对驻极体电容传声器(ECM)电容的特性、电容的构成、计算等进行了较详细的分析,并用实验论证了讨论的结果。结合生产过程,由于工艺条件而造成装配不平行而出现的影响也进行了讨论。给出了从物理概念、物理意义上去分析,以解决ECM在生产制造工程中的问题的讨论实例。     

近代广播传声器的基本原理和应用(下)

3.5 驻极体传声器极头直流极化电容传声器的晶体管放大器,可由一个低压直流电源供电。只有极头的极化,要求高的电动势(并无电流)。为了简化这种电压源,近年电容传声器常具有永久极化的驻极体薄型振膜。这种薄膜主要是聚四氟乙烯。要把它加工成驻极     

驻极体电容传声器的构造与使用

驻极体电容传声器(以下简称ECM)具有体积小、结构简单、电声性能好、价格低廉等优点,广泛应用于盒式录音机、无线电话筒、助听器及声控电路中。ECM主要由驻极体材料提供极化电压的电容传声器极头和专用场效应管两部分组成。驻极体材料是一片极薄的塑料膜片,在其中一面蒸发上一层纯金薄膜,再经过高压电场驻极后,两面分别驻有异性电荷。     

结型场效应管在驻极体电容传声器中的应用与参数测试

本文从驻极体电容传声器的等效电路出发,导出Ku的计算公式;并对影响驻极体电容传声器性能和场效应管参数测试的一些因素进行计算分析,对生产测试中出现的一些问题作出解释.     

单指向驻极体传声器的探讨

作者的立意是将广播电容传声器中双振膜的结构推广应用到驻极体传声器领域中,想法有一定道理,但能否实现值得探讨及试验验证。作为一种探索性文章,发表于此供相关专业人员借鉴、探讨。     

国外电容传声器的发展趋向

传声器（俗称话筒）是一种声电换能器。它将声振动转换为相应的电信号,是广播、电视等领域获得声频电信号的重要电声器件。广播电视领域常用的传声器有：动圈传声器、铝带传声器（是两种电动式换能器）和电容传声器（是静电式换能器,包括驻极体传声器和无线传声器）。传声器的品种、性能和质量直接关系到所转换的电信号质量。因此,对传声器的选择是至关重要的问题。电容传声器是由一个振膜和一个固定极板间所形成电容量随振膜所受声压大小而改变的性质来工作的。它需要外加一极化电压。为了能够得到宽的频率响应还串有一个大阻值的负载电…     

压电传声器的设计与改进

用多孔压电驻极体薄膜替代传统驻极体电容式传声器(ECM)的声电转换单元,制作出压电传声器。利用压电驻极体超薄的优势和对结构进行改进,将压电传声器的厚度从3mm降低到了1mm。为了解决压电传声器灵敏度低的问题,在后端电路采用了30dB增益的管芯。同时,为了减小寄生电容对灵敏度的影响,采用了单面布铜的印刷线路板(PCB),但将该传声器接入手机使用时会有电磁干扰(EMI)。改进PCB的设计,采用双面布铜的PCB,加强了电磁屏蔽,成功解决了压电传声器的EMI问题。最后,利用压电驻极体薄膜的防水性,并对压电传声器的电路进行了防水保护,使得压电传声器达到了IPX7防水标准。     

零部件材质物性对ECM特性影响的讨论

由于组成ECM的零部件的材质和这些零部件在制造过程中工艺特性的不同,使ECM组装后的电声特性受到了较显著的影响。分别对组成ECM的背极材料、振膜材料进行了较为详细的讨论,这种讨论对ECM的生产是有指导意义的。     

Linear theory of an electron cyclotron maser operating at the fundamental

The linear theory of an electron cyclotron maser (ECM) operating at the fundamental is developed. A set of analytic expressions, valid for all TE cavity modes, is derived for the starting current and frequency detuning using the Vlasov-Maxwell equations in the weakly relativistic limit. These results are applicable for an arbitrary electron velocity distribution as well as any longitudinal distribution of the RF field. It is shown that the starting current can be expressed in a simple form which contains the Fourier trans-form of the longitudinal field distribution. Analytic results are presented for specific longitudinal field variations, including uniform, sinusoidal, and Gaussian. It is found that the starting characteristics of an ECM are strongly influenced by the axial dependence of the RF field, but weakly affected by the velocity spread of the electron beam. The problem of multimode oscillation is treated in the linear theory by using a Slater expansion of the cavity field. The complete formulation for mode competition based on this expansion is presented and preliminary results are derived. This comprehensive analysis of ECM linear theory should be useful as a diagnostic of ECM performance and should facilitate comparison between theory and experiment.     

220 GHz折叠波导慢波结构的有损参数化模型

建立了自洽的考虑波导璧损耗的折叠波导等效电路模型,用来计算该慢波结构周期TE10模式中各次空间谐波的相速度,耦合阻抗和线衰减系数.分析结果将会用到220 GHz折叠波导返波管一维束波互作用模型的计算中.当微波频率上升到太赫兹波段时,粗糙波导表面电流导致的壁损将不能再忽略不计.进一步研究表明,起振电流和输出功率水平将和损耗特性的计算密切相关.从原有模型发展而来的有损电路模型可以给出更准确损耗估计.建立了折叠波导慢波线三维谐振腔模型来验证本文的等效电路理论,有较好的吻合.采用了该理论导出参数的一维束波互作用模型和三维数值PIC方法同样有很好的一致性.     

Analysis and design of an integrated silicon ARROW Mach-Zehndermicromechanical interferometer

An analysis and design procedure for an integrated silicon micromechanical (pressure sensitive) interferometer is presented. Optimized layer thicknesses of an SiO₂/Si₃N₄ /SiO₂/Si ARROW yield an attenuation of only 2.7×10^-3 dB/cm. Lateral confinement is accomplished with a rib in the core layer. Sensitivity to mechanical measurands is achieved by having the sensing arm of the interferometer on a thin silicon diaphragm, realized by micromachining a cavity from the back of the wafer. An applied pressure P deflects the diaphragm, causing a change in optical path length, leading to a phase shift φ with respect to the reference arm. Sensitivity is increased by thinning the diaphragm, although this increases the resonant attenuation envelope of the diaphragm. Sensitivity calculations based on a simple, first-order model of diaphragm deflection yield (∂φ)/(φ∂P)=1.29×10^-14 P for a specific diaphragm geometry. BPM simulations show that curvature losses due to the bending of the ARROW under deflection is negligible     

点目标成像红外遥感器探测信噪比测试研究

针对遥感器真空低温测试需求，设计并搭建了一套能够在低温真空环境中稳定工作的红外目标背景模拟器，模拟器主要由冷光阑、真空低温面源黑体、三维电移台三部分组成，冷光阑模拟探测背景，冷光阑上分布微孔用于模拟探测点目标。通过有效控制目标模拟器与背景模拟器间的隔热、控温以及背景模拟器与待测遥感器之间的隔热，实现稳定测试。另外，将仿真优化与实践经验相结合，通过仿真计算去除模拟器冷光阑板厚度、目标相位、平行光管等的影响，有效降低系统测量不确定度。文中的仿真分析方法和验证情况对于红外遥感器点目标探测信噪比检测试验具有参考意义。     

CMP抛光液供给及分布系统的研究

从整体结构及硬件设计方面介绍了小批量生产及隔膜泵系统,分析隔膜泵的工作原理,循环机理及硬件控制和驱动电路,同时指出在湿度较大的生产厂里面产生的漂移及解决措施;从整体结构分析集中式抛光液供给系统,分析其抛光液混合中心具备的温度控制、无轴承磁悬浮泵工作机理及循环机制;对比隔膜泵与无轴承磁悬浮泵对颗粒凝聚的影响,并分析这种系统适用范围。     

泵腔结构参数对压电气泵性能影响

为了探究泵腔结构参数对压电气体隔膜泵性能的影响,该文设计了一种压电气体隔膜泵的泵腔结构。首先简述了泵腔的结构设计与工作原理,推导出泵腔出口气流速度的表达式,通过仿真得出泵腔高度、气孔直径对腔体内的瞬时气压、气流速度及气体流量的影响。最后制作了泵腔样机并应用在压电气体隔膜泵中,进行了实验测试及理论分析对比。结果表明,实验结果与理论分析相吻合,输出流量随着腔高的增大而减小,随着气孔直径的增大而增大,这为压电气体微泵的腔体设计提供了理论参考。     

平顶高斯光束在失调光学系统中的传输特性

为了研究平顶高斯光束经含失调窄缝光阑的失调光学系统的传输特性,采用广义衍射积分法和用有限个复高斯函数之和来逼近窄缝光阑孔径函数的方法,得出了输出光束场分布的近似解析公式,并针对给定的光学系统和平顶高斯光束进行了分析和数值模拟。结果表明,当光阑半宽度与光束束腰半宽度之比较大时(大于1),光学系统的失调量比光阑的失调量对输出光束特性影响更显著。这一结果对分析平顶高斯光束传输特性是有帮助的。     

Performance analysis of valveless micropump with disposable chamber actuated through Amplified Piezo Actuator (APA) for biomedical application

The precise manipulation of fluid through pumping systems has been the technological challenge in microfluidic applications. The biomedical applications call for precise and accurate delivery of fluid through miniaturized pumping systems. This paper presents a novel valveless micropump for biomedical applications operated by the Amplified Piezo Actuator. Integrating the disposable chamber and reusable actuator with the proposed micropump allows the actuator to be reused and eliminates the possibility of infection or contagion. The micropump was fabricated using low-cost polymeric materials like Polymethylmethacrylate (PMMA), Silicone rubber through CNC milling, Laser Cutting, conventional moulding operation. The micropump chamber, nozzle/diffusers, and a bossed diaphragm constituted disposable part and Amplified Piezo Actuator with structural support formed the reusable part of the micropump. The bossed diaphragm of the pump chamber consists of a central cylindrical protrusion to reduce the force of adhesion on the diaphragm and transmit force required for micropump actuation. A theoretical analysis was performed to assess the effect of diaphragm thickness and the bossed region on the effective stiffness of the diaphragm, which in turn influences the deflection achieved. Besides, an analytical approach has been presented to address the effect of adhesive force on the diaphragm surface due to the residual fluid and chamber depth. The experimental characterization of the micropump was carried out to determine the optimal performance parameters with water, fluids mimicking blood plasma, and whole blood. Based on the experimental results, the pumping rate and head developed by the micropump have been significantly affected by factors such as bossed ratio, diaphragm thickness, depth of the micropump chamber, and viscosity of the fluid. The optimum configuration of the micropump cosidered silicone rubber diaphragm with thickness of 0.20 mm having a bossed ratio of 0.33 and a chamber depth of 1.25 mm. With the optimal operating parameters of 150 V sinusoidal input of frequency 5 Hz, the proposed micropump was capable of delivering 7.192 ml/min, 6.108 ml/min, and 5.013 ml/min of water and blood plasma, whole blood mimicking fluid with the maximum backpressure of 294.00 Pa, 226.243 Pa, and 204.048 Pa respectively. The corresponding resolution, i.e., pumping volume/stroke of the micropump was about 23.972 µl, 20.358 µl, and 16.708 µl, respectively.