共查询到20条相似文献,搜索用时 171 毫秒
1.
本文使用两块平行极板及其测量、控制和显示电路,实现纸张计数和显示功能。具体方案采用555多谐振荡器电路将纸张数目变化引起的两极板间电容的变化,转化为谐振回路的振荡频率变化。通过大量实验校准拟合纸张数目和谐振回路频率的对应关系。进而通过STC12C5A60单片机构建的频率测量模块完成测频,计算校正后驱动LCD显示纸张数目或极板是否处于短路状态。 相似文献
2.
测量纸张含水量的双模式微波传感器 总被引:1,自引:0,他引:1
本文介绍一种用于纸张含水量测试的微波传感器。它是利用圆柱形微波谐振腔中的多模谐振现象,采用简并的TE_(011)和TM_(111)模式,利用其谐振频率对纸张含水量变化的不同敏感性,测量两模式谐振频率之差的变化,达到测量含水量变化的目的。文章给出了腔体设计公式、纸张对频差的微扰计算公式、最佳腔体尺寸的选取。对温度补偿特性也作了分析。并给出了一只实验传感器的测量结果。 相似文献
3.
针对石英晶体谐振器(QCR)的声负载敏感性,在一种三层结构力学模型的基础上,导出了具有广泛适用意义的谐振电阻及谐振频率随谐振器表面参数变化的公式。结合石英谐振式气、湿敏传感器的理论分析表明,QCR的谐振幅值与谐振频率均可作为传感器的检测参量。谐振幅值主要反映了表面阻尼情况,谐振频率则在反映表面质量负载情况的同时,受到表面阻尼的影响,在传感器研制中应引起足够的重视 相似文献
4.
5.
微悬臂谐振传感器闭环接口和嵌入式频率电路 总被引:1,自引:0,他引:1
设计了谐振式微悬臂梁传感器闭环接口和嵌入式频率读出电路。首先,谐振式微悬臂梁传感器和接口电路组成闭环自激振荡系统。为了提高该闭环系统的频率稳定性和频率跟踪性能,引入具有无相差频率跟踪的锁相环电路,并设计放大移相电路以满足闭环自激振荡条件。该闭环系统的频率稳定性可达±0.1Hz,并且能够实时跟踪悬臂梁谐振频率的变化。此外,单独设计了嵌入式的频率读出电路,用于检测并显示悬臂梁的谐振频率。将悬臂梁传感器、接口电路和频率读出电路集成在一起,做出了小巧便携式样机,用该样机可成功探测到体积分数低至约几个10-9量级的DMMP气体。 相似文献
6.
7.
8.
数字集成芯片构成的频率计数器设计 总被引:1,自引:1,他引:0
频率计数器是一种用数字显示的频率测量仪表,它不仅可以测量正弦信号、三角波信号、方波信号和尖脉冲信号的频率,而且还能对其他多种非电量信号的频率进行测量。系统采用555定时器组成的多谐振荡器作为时基产生电路,产生频率为1 kHz的控制信号,而被测信号经过一个放大整形电路,将其变化成满足系统要求的计数脉冲信号,然后用频率计数器测量单位时间内变化次数,即被测信号的频率。 相似文献
9.
基于双等强度悬臂梁的光纤光栅加速度振动传感器 总被引:13,自引:13,他引:0
研制了一种基于双等强度悬臂梁式光纤布 拉格光栅(FBG)振动传感器。首先采用ANSYS软件对 传感器进行数值计算与仿真,得到在各个阻尼比下传感器的幅频特性曲线和相频特性曲 线,不断变化 传感器结构参数,寻找最优谐振频率与加速度灵敏度,从而得到传感器最优结构参数;根据 仿真所得的最 优结构参数,进行传感器加工;利用所加工的振动传感器进行振动台试验研究并对所得实验 数据进行处理, 将处理后的数据与ANSYS软件仿真得到的数据进行比较,结果表明,振动平台所测得的 实验结果与ANSYS 软件仿真结果相吻合,传感器的谐振频率为80.74Hz,可实现50Hz以下低 频振动信号的实时监测,在5~50Hz之间的加速度灵敏度约为20.85pm/m·s-2。 相似文献
10.
数字电子钟是一个对标准频率(1Hz)进行计数的计数电路。由振荡电路形成秒脉冲信号,秒脉冲信号输入计数器进行计数,并把累计结果以"时"、"分"、"秒"的数字显示出来。秒计数器电路计满60后触发分计数器电路,分计数器电路计满60后触发时计数器电路,当计满24小时后又开始下一轮的循环计数。由振荡电路、计数器、数码显示器、校时电路、整点报时电路等几部分组成。 相似文献
11.
A relocatable resonant FBG-acoustic emission sensor with strain-insensitive structure 总被引:1,自引:0,他引:1
A novel resonant fiber Bragg grating (FBG) based acoustic emission (AE) sensor with relocatable, strain-insensitive and enhanced sensitivity structure is demonstrated for structure health monitoring (SHM) in this paper. With one end of the sensing FBG bonded to a polyimide (PI) plate acoustically the other end free, the sensor can be easily redeployed around coupled with the investigated structure via couplant and the monitored structure surface and get rid of the interference from the strain applied on the monitored structure. Experiment has been conducted to verify the characteristics of this FBG-AE sensor, whose results show that the sensor is insensitive to mechanical strain applied on the monitored structure. It is also shown experimentally that the sensitivity is enhanced by about 1.2 times than the conventiotlal design, while the novel sensor possesses good resonant frequency response to the standard AE waves. 相似文献
12.
针对热激励谐振型压力传感器在不同激励电压下会产生不同的热梯度场,进而影响传感器的谐振频率这一现象,采用开环测试系统进行试验,得到热激励谐振型压力传感器的热激励幅度与谐振频率的变化规律;并对实验结果进行了进一步的分析,为合理优化设计传感器的相关参数提供了一定的理论依据. 相似文献
13.
Baker M.D. Williams F.R. May G.S. 《Semiconductor Manufacturing, IEEE Transactions on》1998,11(2):254-265
This paper presents a novel technique for monitoring film thickness in reactive ion etching by incorporating a micromachined sensor. The prototype sensor correlates film thickness with the change in resonant frequency that occurs in a micromachined platform during etching. The platform is suspended over a drive electrode on the surface of the substrate and electrically excited into resonance. As material is etched from the platform, its resonant vibrational frequency shifts by an amount proportional to the amount of material etched, allowing etch rate to be inferred. As a proof-of-concept experiment, a platform made of DuPont 2611 polyimide has been fabricated. The sensor is driven into resonance electrostatically, and the shift in resonance is detected by monitoring the change in impedance between the drive electrode and platform as the drive frequency is swept. To enhance filtering of the sensor signal in the noisy plasma environment, the platform is designed so that the ratio of the plasma frequency to the fundamental mode of vibration is approximately 400:1. The prototype was etched in a Plasma Therm 700 series reactive ion etching (RIE) system in a CHF3/O2 plasma. Electrical contact was made with the sensor using a feedthrough attached to the vacuum line beneath the process chamber to facilitate in situ excitation and measurement. The sensor is shown to offer high resolution (approximately 1300 Hz/um), potentially permitting accurate in situ monitoring of etch rate and uniformity at a nominal cost 相似文献
14.
An optically driven, through photovoltaic conversion, pressure sensor is described which uses frustrated-total-internal-reflection between a critically cut optical fiber and a quartz crystal, mounted on a cantilever beam to sense the device resonant frequency. The change in this frequency as a function of applied pressure is measured in this sensor which relies upon an all-optical link to the control electronics. 相似文献
15.
16.
17.
薄膜体声波滤波器(FBAR)传感器的性能受结构和材料特性的影响很大。该文利用COMSOL Multiphysics有限元仿真软件,建立了FBAR传感器的二维、三维有限元结构模型。用氮化铝和氧化锌材料作为压电薄膜对建立的模型做了固体力学和静电学仿真分析,得到了FBAR传感器的谐振频率、导纳特性曲线和谐振频率处的位移分布情况。通过分析发现氮化铝压电薄膜阻抗特性曲线更平滑,而氧化锌压电薄膜存在明显的寄生谐振峰的问题。针对氧化锌压电薄膜存在的寄生谐振峰进行了优化,仿真分析了电极边长尺寸和电极厚度对寄生谐振的影响,实现了对寄生谐振峰的有效抑制。 相似文献
18.
19.
Kai Yang Zhigang Li Yupeng Jing Dapeng Chen Tianchun Ye 《Microelectronics Journal》2009,40(8):1196-1201
Resonant frequency is a key parameter in designing a resonant transducer with high sensitivity. Eigen-frequency calculation of a composite-layer microcantilever is quite useful for the design of a microcantilever resonant sensor. However, simple methods for predicting the resonant frequency of composite rectangular microcantilevers are poorly developed and invite further research. This paper presents a simple and accurate analytical method called “equivalent model method” to predict the fundamental resonant frequency of composite rectangular microcantilevers with equal width (CRMEW). This novel method, which is much more convenient for practical applications, is then confirmed by both experimental results and simulation results, and presents a strong potential to be used in the design and optimization of micromachined transducers. 相似文献
20.