中英文翻译

压输出，就可以实现设计要求。由试验，可以得知压电陶瓷片可以实现我们所要达到的目标。 整体电路分析

经实验可知,采用GaAs红外发光二极管作为光源时，可基本抑制由呼吸运动造成的脉搏波曲线的漂移。脉搏波检测以光电检测技术为基础，因此受周围杂散光、暗电流等各种干扰影响较大，为了克服这一问题本系统采用脉冲振幅光调制技术。脉冲调制传送的是调制信号的采样值，只要采样频率奈奎斯特采样频率，则可由采样脉冲来恢复原信号，而不会导致失真。系统对红外二极管的驱动脉冲信号的频率选定为工频整数倍400Hz以降低工频干扰，脉冲载波由ADuC841内部16位数模转换器产生。为了保证红外发光二极管的光源稳定，本文采用运放op495和NPN型三极管作为恒流源电路向发光二极管提供稳定的工作电流。

光敏二极管的特性是将光信号转换为电流，而随后的A/D转换电路是以电压为检测对象。因此，接收电路中应采用电流电压变换电路，将电流信号转换为电压信号。运算放大器与电阻R形成电流电压变换电路，如图4-2所示。（图中S_GND为信号地，运算放大器工作正负电源为5V、0V，为避免信号丢失，将信号抬高至VS_GND=1V）电路输出电压。

由于光电脉搏波属于缓慢变化的微弱生理信号，信噪比低，极易受到环境噪声和肢体运动的干扰。传统的光电脉搏波信号检测电路都采用高增益放大器，以获得较高的检测灵敏度，这种设计思路导致了检测信号动态范围缩小，在受到运动干扰时，将导致由于干扰信号而带来的光电脉搏波信号检测的饱和失真。本系统采用过采样技术，通过对信号的高速采样来提高采样精度，相当于用高分辨率的ADC对信号进行模数转换，达到了提高信噪比并改善动态范围的效果。因此对经过光电转换后的信号进行模数转换而不需要任何信号调理（放大和滤波）电路。

所谓过采样技术是指以远远高于奈奎斯特(Nyquist)采样频率的频率对模拟信号进行采样的方法。由信号采样量化理论可知，若输入信号的最小幅度大于量化器的量化电平，并且输入信号的幅度随机分布，则量化噪声的总功率是一个常数，在0～fs／2的频带范围内均匀分布。因此量化噪声电平与采样频率成反比，如果提高采样频率，则可以降低量化噪声电平，而由于基带是固定不变的，因而减少了基带范围内的噪声功率，提高了信噪比，从而提高分辨率，并且采样频率每提高4倍，则信噪比提高4倍，相当于A/DC的分辨率提高1位。滤波器为一个数字低通滤波器，主要是滤除采样信号频带以外的高频量化噪声，并维持信号频带以内的信号基本不变，抽取是将采样得到的高速低分

辨率的数字信号的抽样频率降至奈奎斯特采样频率，进而完成高分辨率数字信号的重构，抗混叠主要是滤除降低取样频率后可能出现的混叠噪声。

数字滤波和抽取均通过软件来实现，配置灵活。传感器主要由红外线发射二极管和接收二极管组成，测量的原理如下：将手指放在红外线发射二极管和接收二极管中间，随着心脏的跳动，由于手指放在光的传递路径中，血管中血液饱和程度的变化将引起光的强度发生变化，因此和心跳的节拍相对应，红外接收二极管的电流也跟着改变，这就导致红外接收二极管输出脉冲信号。脉冲信号由F1~F3、R3~R5、C1、C2等组成的低通放大器进行放大，再经由F4、R6、R7、C3组成的放大器进一步放大，其输出信号送给由F5、F6、RP1、R8等组成的施密特触发器进行整形后输出，输出的脉冲信号作为单片机的外部中断信号。可变电阻RP1用来调整施密特触发器的阀值电压，从而调整电路的灵敏度。

AT89C2051、X1、R10、C5等组成单片机电路，单片机电路对P3.2输入的脉冲信号进行计算处理后把结果送到数码管显示，发光二极管VD3作脉搏测量状态显示，脉搏每跳动一次发光二极管就点亮一次，数码管DS1~DS3、VT1~VT3、R12~R21等组成数码显示电路。本机P3.3-P3.5口作三个数码管的动态扫描位驱动码输出，通过三极管驱动数码管，P1.0-P1.6口作数码显示七段笔划字形码的输出，用以驱动数码管的各字段。

原文：

Pulse transducer and circuit design

Pulse has 2600 years of clinical practice,is the essence of

the four diagnostic methods of traditional Chinese medicine.Pulse in traditional Chinese medicine,Western medicine has a very important significance.The Qiemo skills in traditional Chinese pulse diagnosis is difficult to grasp and apply the doctors subjective factors, along with the development of science and technology,PVdF(polyvinylidene fluoride) piezoelectric film developed to determine the different pulse instrument the objective of the pulse,the sensitive part of the design of the pulse instrument sensor finger. Thisarticle from the perspective of the analog pulse diagnosis,the developmentof PVdF piezoelectric volume to obtain a large output power.Because of the change of unit-body thin film sensors, an applied to the pulse instrument.Plot the maximum output power is proportional

tothe electromechanical coupling coefficient and able to withstand the quantitative has become the inevitabletrend of Chinese medicine diagnosis.Decades,

the state selected PVdF piezoelectric film, because it follows several advantages:

First,film light and flexible, easy preparation and human tissue impedance coupling can be closeto the skin, without distortion of the pulse signal through the film. In addition, the film is similar to human skin, you can create a biomimetic tactile sensor. The piezoelectric constant (d33 = 20 pC / N), the inotropic easy to study, but the development of the situation, most of the sensor can not be simulated in the sensitivity.10 times higher than the quartz crystal, the piezoelectric voltage output constant Qiemo take three, floating,\zoelectric. Detection pulse signal depends mainly on the pressure calibration, the applicability is not good enough.

Then,mechanical quality factor low, damping, low density, with broadband features to address the frequency characteristics of the pulse signal. If not depolarization in the very high alternating electric field.

PVdF membrane flexibility and its thickness direction of the

stretchingvibration of the resonant frequency is high, making a wide range of flat frequency. PVdF membrane above advantages, according to Chinese medicine Qiemo model, we developed a three-sensor, three square sheet made by the PVdF film transducer, an area equivalent to the force the Qiemo when pulp area in the piezoelectric film bipolar charge generated steam the aluminum electrode and leads to the wire, flexible organic plastic film packaging made of a circular substrate, mounted on a table to bring. Taking into account the patient's signs, young and old, and other factors, the three transducer independently corresponds to the vertical and horizontal adjustment by floating an inch three parts, and can bring in the table. Strap-beam measurements in the wrist, and the doctor finger corresponding to enlarge three transducer

s can. The doctor can feel through the thin slices pulse fluctuations. Floating, mode pulse process can artificially control the intensity, do vary from person to person to overcome the pressure of the past cylinder transducer calibration taken floating inadequate. When a periodic pulse pressure transducer, mechanical energy converted to electricity.

The pulse spectrum analysis shows that 99% of the energy in the pulse spectrum is concentrated below 10 Hz, the highest frequency of no more than 40 Hz. Tune to achieve communication with the computer. PVdF piezoelectric film transducer is sensitive components in this design, is also designed one of the key links of the role of simulation in which the pressure sensation can, will the pulse pressure of the weak low-frequency signal conversion into electrical signals. Set of pre-charge amplifier role there are two: First, with the transducer impedance matching, high-impedance input into a low impedance output; second is the weak charge into a voltage signal and zoom. In order to improve the measurement accuracy and sensitivity, pre-amplifier circuit using a linear correction of the charge amplifier to lower the lower limit frequency, eliminating the cable distribution of feed-forward capacitor.

Capacitance on the sensitivity of the impact of the design of the small sensor size. The first low-pass filter circuit formed by R1 and C1, the cutoff frequency of about 1000 Hz, so that the higher harmonic of the pulse signal through the pulse signal reflected pathological feature information to get the full reservation. While theupper limit cut-off frequency and the time constant circuit (formed by C2 and R2) will decisively influence the distortion of the pulse waveform. If the circuit time constant is selected too small, will cause a serious low-frequency component of the signal attenuation and phase shift. The experiments show that when the time sufficient to ensure that the pulse wave of low frequency components without distortion. Voltage amplifier, the charge amplifier output voltage signal amplification. And provide different gain. According to our experience, set the upper cut-off frequenc