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1、南 京 理 工 大 学毕业设计(论文)外文资料翻译 教 学 点： 无锡科技职业学院 专 业： 电子工程 姓 名： 林祥 准考证号： 024912201033 (用外文写) 外文出处： Photoelectric sensor electromagnetic compatibility design thesi 附 件： 1.外文资料翻译译文；2.外文原文。指导教师评语： 签名： 年 月 日注：请将该封面与附件装订成册。附件1：外文资料翻译译文光电传感器的电磁兼容设计论文摘要: 在多个光电传感器构成的计算机控制系统中,电磁兼容是很重要的。经过电磁兼容设计,光电传感器的电磁辐射强度降低了,抗电磁干
2、扰能力显著提高。介绍了光电传感器主要部分及整体进行电磁兼容设计的方法,提供了电磁兼容试验方法。 关键词:光电传感器；电磁兼容； 设计；试验引言 广泛应用于工业自动化领域的光电传感器,一般是开关型的,被称为光电开关。光电传感器由投光器、受光器、集成电路、输出电路等组成,属弱电检测传感器。它容易受到强电设备的电磁干扰。它工作时,引起电磁辐射,形成电磁干扰。当动作频率较高、多个传感器相距较近时,仪器仪表、总线系统、计算机等弱电设备会受到强烈的干扰,传感器本身也会受到强烈的干扰,此时电磁兼容问题显得更突出。电磁兼容设计的目的,一是使传感器本身在电磁环境中能正常工作,避免出现误动作,二是避免传感器成为电
3、磁干扰源。 1.光干扰的抑制光电传感器以光为媒介进行无接触检测。光是一种频率很高的电磁波。光干扰也算是一种电磁干扰,光干扰是传感器误动作的主要因素之一。环境光、背景光和周围其它光电传感器发出的光是光干扰源。以红外线为媒介进行检测则可减小可见光的影响,红外光也不影响可见光。红外线光电传感器可用滤光镜滤去可见光。对于周围环境其它光电传感器的光干扰, 可用外壳、套筒、夹缝来抑。 投光器外壳结构设计得当,可使发出的光成为规则光束,而非散射状,使用时又安装得当,则投光器难成为光干扰源。传感器设计时,采用偏振光及高频调制的脉冲光,采用同步检波方式,都有利于抑制光干扰。 2.电路板电磁兼容光电传感器通过高频
4、调制产生高频电信号。在高频下,一根导线等效为一个电感。因此,须尽可能缩短传感器内高频线的长度。印制板迹线设计时要考虑尽可能减小电磁辐射。迹线辐射比集成电路辐射要强。迹线的大小相等、方向相反的电流环路,则会向空间辐射磁场,也会接受空间的磁场。 此时为差模辐射。可通过减小环路面积S 和环路电流i 来减小差模辐射。共模辐射可用对地电压激励的、长度小于1/ 4 波长的短单极天线来模拟。短单极天线长度共模电压转换成了差模电流i 。减小地电压和将差模电流旁路到地可减小共模辐射。总的来说,印制板迹线长度宜短,宜增加宽度,但不宜突然增宽,不宜突然拐弯。尽可能增大地线面积以减小地线阻抗。高频信号线、电源线应尽可
5、能平行地靠近地线。传感器应选用低功耗器件,如CMOS 集成电路。CMOS 器件抗干扰能力强,CMOS 逻辑电路抗扰度高达20 %。低功耗器件发热小,这有利于传感器设计得更紧密,有利于传感器稳定工作。 3.输出电路电磁兼容输出电路是传感器的末级电路,一般是无触点开关电路。常用输出元件有三极管和晶闸管。三极管状态改变时,引起电磁辐射。在三极管集电极与发射极之间并接RC 吸收电路,用电感L 来抑制d i/ d t , 就可减小电磁辐射的能量。 输出电路电磁兼容设计的另一种方法是屏蔽。晶闸管被屏蔽,LC 滤波网络用来抑制晶闸管动作时产生的浪涌。滤波网络与屏蔽罩均接地。 4.抗干扰编码现在,通信、接口、
6、总线技术的发展也促使二进制传感器的智能化。AS-Interface 是一个执行器-传感器- 接口总线系统。AS-Interface 总线系统最多可安装248 个二进制传感器。AS-Interface 芯片与光电传感器配合,可使传感器与AS-Interface 总线相连。同一总线上,多个传感器相互干扰的问题比较严重。这可在传感器通信时,在信息中加入监督码元（冗余码） 进行抗干扰。如用00000 、11111 代替0 、1 。当收到10111 ,那可认为错了一位,并自动纠正第二位。 5.电磁兼容试验电磁兼容设计靠电磁兼容试验来验证与改进。现在,有了比较完善的电磁兼容试验方法和专门的试验设备。开关电
7、器动作时,形成强烈的干扰,产生瞬态脉冲。IEC61000-4-4 标准对电快速瞬变脉冲干扰作出规定,分为单个脉冲、一群脉冲、脉冲群。脉冲群波形周期为300 ms , 脉冲束宽度为15 ms。 单个脉冲和一群脉冲中单个脉冲的宽度要小于15ms。IEC1024 规定的雷电模拟脉冲的宽度也要小于15 ms。光电传感器内部采用小电容对瞬变脉冲滤波比较适应。传感器若受主机控制,则可在软件中采用数字滤波、延时指令来抑制瞬变干扰。应考虑信号线阻抗匹配问题。所谓阻抗匹配就是信号线的负载应与信号线的特性阻抗相等。特性阻抗与信号线的宽度、与地线层的距离以及板村的介电常数等物理因素有关，是信号线的固有特性。阻抗不匹
8、配将引起传输信号的反向，使数字波形产生振荡，造成逻辑混乱。通常信号线的负载是芯片，基本稳定。造成不匹配的原因主要是信号线走线过程中本身的特性阻抗的变化，例如走线的宽窄不一，走线拐弯，经过过孔等。所以，布线时应采取以下措施，使得信号线全程走线的特性阻抗保持不变：高速信号线布置在同一层上，不经过过孔。一般数字信号线应避免穿过二个以上的过孔。信号线拐90直角会产生特性阻抗变化，所以拐角处应设计成弧形或轨线的外侧用两个45角连接。信号线不要离印制板边缘太近，留有的宽度应至少大于轨线层和地线层的距离（约为0.15mn），否则会引起特性阻抗变化，而且容易产生边缘场，增加向外的辐射。时钟发生器如有多个负载，
9、则不能用树型结构走线，而应用蜘蛛网型结构走线，即所有的时钟负载直接与时钟功率驱动器相互连接。6.电磁兼容性问题的规范和标准 干扰特别委员会（CISPR），主要研究无线电系统中干扰噪声的测量。1976年，CISPR开始制订电磁干扰的EMI标准。1900年10月在几经修订基础上公布再版标准，随后该委员会还与国际无线通信资询委员会一起审议，为电子产品电磁兼容性的检测制订数据要求及具体方法。制订了以信息技术装置噪声为对象的“工业、科学及医疗用无线电仪器的干扰特性允许值及其测量方法”（标准11号）；“车辆、机动船和火花点火发动驱动装置无线电干扰特性的测量方法及允许值”（标准12号）；“无线电和电视接收机
10、的无线电干扰特性的测量方法及允许值”（标准13号）等。直至1992年中期，国际EMI标准才最终完善起来。CISPR推荐的容限已为世界上许多国家所采纳，并作为其国家条例的基础。 频率规划在全国和全世界范围内已被广泛采用，是提高射频资源利用率的一种途径，也是保证无线电电子设备电磁兼容性的重要措施之一。因此应严格按照国际协议（无线电频率分配表）和全国文件，实行国家、地区的频带划分和业务之间的频带分配。根据频率空间分配的原理进行无线频道分配。频率规划必须保证每个无线电电子设备干扰电平最小，或消除干扰，由国家无线电管理委员会负责协调。 近年来，我国许多部门都在开展电磁兼容性的试验研究和有关技术标准的制定
11、工作，制定了一系列标准和规范。例如，国家标准GB3907-83为工业无线电干扰基本测量方法；GB4824.1-84为工业、科学和医疗射频设备无线电干扰允许值；GB6279-86为车辆、机动船和火花点火发动机驱动装置无线电特性测量方法及允许值等。国家无线电管理委员会对工、科、医等电子设备的使用频率、带宽和最大辐射场强都作出了具体规定。这对保证电子设备的正常工作和人民的正常生活以及促进现代科学技术更迅速发展，都起了重要的作用。 7.典型电磁兼容性问题的解决 电子技术在各行各业中的广泛应用，在人类活动的空间无处不充斥着电磁波，因此，电子设备不解决电磁波干扰问题，就不能兼容工作。在实际应用中，人们在研
12、究抗干扰技术方面也积累了大量的经验，不断地研究出许多实用的方法来消除电磁干扰。 实验发现汽车工作时，电磁干扰相当突出，严重时会损坏电子元器件。因此，汽车电子设备的电磁环境最为恶劣，汽车电子设备的电磁兼容性问题也特别受到人们的重视。汽车点火所产生的高频辐射最为突出。日本和美国等先进国家的环保部门为防止汽车电气噪声对环境的污染，规定只能使用带阻尼（如碳芯）的屏蔽线作为点火线，实践表明这是很有效的措施。 为了解决微电技术，尤其是计算机在汽车上的应用和推广，根据需要和实际要求，可以设计出效果良好的滤波电路，置于前级可使大多数因传导而进入系统的干扰噪声消除在电路系统的入口处；可以设置隔离电路，如变压器隔
13、离和光电隔离等解决通过电源线、信号线和地线进入电路的传导干扰，同时阻止因公共阻抗、长线传输而引起的干扰；也可以设置能量吸收回路，从而减少电路、器件吸收的噪声能量；或通过选择元器件和合理安排电路系统，使干扰的影响减小。 微机设备的软件抗干扰主要是稳定内存数据和保证程序指针。微机是一个可编程控制装置，软件可以支持和加强硬件的抗干扰能力。如果微机系统中随机内存RAM主要用于测量和控制时数据的暂时存放，内存空间较小，对存放的数据而言，若将采集到的几组数据求平均值作为采样结果，可避免在采集时因干扰而破坏了数据的真实性；如果存放在随机内存中的数据因干扰而丢失或者数据发生变化，可以在随机内存区设置检验标志；
14、为了减少干扰对随机内存区的破坏，可在随机存储器芯片的写信号线上加触发装置，只有在CPU写数据时才发。软件抗干扰的措施也很多，如数字滤波程序、抗窄脉冲的延时程序、逻辑状态的真伪判别等。有时候，必须采用软件和硬件相结合的办法才能抑制干扰，常用的办法是设置一个定时器，从而保护程序正常运行。 近年来，电子仪器向着“轻、薄、短、小”和多功能、高性能及成本低方向发展。塑料机箱、塑料部件或面板广泛地应用于电子仪器上，于是外界电磁波很容易穿透外壳或面板，对仪器的正常工作产生有害的干扰，而仪器所产生的电磁波，也非常容易辐射到周围空间，影响其它电子仪器的正常工作。为了使这种电子仪器能满足电磁兼容性要求，人们在实践
15、中，研究出塑料金属化处理的工艺方法，如溅射镀锌、真空镀（AL）、电镀或化学镀铜、粘贴金属箔（Cu或AL）和涂覆导电涂料等。经过金属化处理之后，使完全绝缘的塑料表面或塑料本身（导电塑料）具有金属那样反射（如手机）。吸收、传导和衰减电磁波的特性，从而起到屏蔽电磁波干扰的作用。实际应用中，采用导电涂料作屏蔽涂层，性能优良而且价格适宜。在需要屏蔽的地方，做成一个封闭的导电壳体并接地，把内外两种不同的电磁波隔离开。实践表明，若屏蔽材料能达到（3040）dB以上衰减量的屏蔽效果时，就是实用、可行的。 由于电子技术应用广泛，而且各种干扰设备的辐射很复杂，要完全消除电磁干扰是不可能的。但是，根据电磁兼容性原理
16、，可以采取许多技术措施减小电磁干扰，使电磁干扰控制到一定范围内，从而保证系统或设备的兼容性，例如，通信系统最初设计时，就应该严格进行现场电波测试，有针对性地选择频率及极化方式，避开雷达、移动通信等杂波干扰；高压线选择路径时，应尽量绕开无线电台（站）或充分利用接收地段的地形、地物屏蔽；接收设备与工业干扰源设备适当配置，使接收设备与各种工业干扰源离开一定距离；在微波通信电路设计中，为了减少干扰，可采用天线高低站方式调整微波电路反射点，并利用山头阻挡反射波，使之不能对直射波形成干扰。另外，微波铁塔是独立的高大建筑物，应采用完善的接地、屏蔽等避雷措施。8.结束语采用以上设计后, 光电传感器既没有干扰8
17、0C51 单片机实验系统, 也没有干扰F-40M 型PLC。它在断路器严酷环境中能稳定地工作。经过电磁兼容设计,光电传感器可靠性及质量显著提高。附件2：外文原文Photoelectric sensor electromagnetic compatibility design thesisAbstract：In a number of photoelectric sensor consisting of computer control systems, electromagnetic compatibility is very important. After electromagnetic
18、compatibility design, photoelectric sensor reduces the intensity of electromagnetic radiation, anti-electromagnetic interference ability to significantly improve. Introduce the main part of a photoelectric sensor for electromagnetic compatibility and overall design approach, provided the electromagn
19、etic compatibility test method.Keywords： photoelectric sensor； electromagnetic compatibility；design；testIntroductionWidely applies in the industrial automation domain photoelectric sensor, generally is the switch, is called the electro-optical switch. The photoelectric sensor by the floodlight, the
20、light, the integrated circuit, the output circuit and so on is composed, is the weak electricity examination sensor. It easy to receive the strong electricity equipments electromagnetic interference. When it works, causes the electromagnetic radiation, forms the electromagnetic interference. When th
21、e action frequency was high, many sensor closes recently, the instruments and meters, the bus system, the computer and so on weak electricity equipment can receive the intense disturbance, the sensor itself will also receive the intense disturbance, this time the electromagnetic compatibility questi
22、on appeared more prominent. Electromagnetic compatibility design goal; first, enables the sensor itself in the electromagnetic environment the normal work, avoids presenting the misoperation; second, avoids the sensor becoming the electromagnetism noise source.1 .Light disturbance suppressionThe pho
23、toelectric sensor carries on the non-contact inspection take the light as the medium. The light is one kind of frequency very high electromagnetic wave. The light disturbance is also one kind of electromagnetic interference, the light disturbance is one of sensor misoperations primary factors. The e
24、nvironment light, the background light and periphery other photoelectric sensor sends out the light is the light noise source. Carries on the examination take infrared as the medium to be possible to reduce the visible light the influence, the infrared light does not affect the visible light. The in
25、frared light electric pickup available light filter filter out the visible light. Regarding the environment other photoelectric sensors light disturbance, the available outer covering, the sleeve, the crevice damp.The floodlight outer covering structural design is appropriate, may cause the light wh
26、ich sends out to become the regular light beam, but non-scattering shape, time use installs appropriately, then the floodlight difficult to become the light noise source. When the sensor designs, uses the polarized light and the high frequency modulation pulse light, selects the synchronized detecti
27、on method, is advantageous in suppresses the light disturbance.2 .Circuit wafer electromagnetic compatibility The photoelectric sensor produces the high frequency electrical signal through the high frequency modulation. Under high frequency, a wire equivalent is an inductance. Therefore, must reduce
28、 in as far as possible the sensor the high frequency line length. When board pathline design must consider that reduces the electromagnetic radiation as far as possible. The pathline radiation compares integrated circuit radiation striving to excel. The pathline size is equal, direction opposite cur
29、rent loop, then to the space radiation magnetic field, also will accept spatial the magnetic field.This time for bad mold radiation. May through reduce ring circuit area S and the ring circuit electric current i reduces the bad mold radiation. The syntype radiation available to the place voltage dri
30、ve, the length is smaller than 1/4 wave length short monopole antenna simulates.The short monopole antenna length syntype voltage transformed the difference mold electric current i. Will reduce the voltage and will miss the mold electric current bypass to arrive may reduce the syntype radiation.Gene
31、rally speaking, board pathline length suitable short, increases the width suitably, but is not suitable broadens suddenly, is not suitable turns round suddenly. Increases the grounding area to reduce the grounding impedance as far as possible. The high frequency holding wire, the power line should p
32、arallel approach the grounding as far as possible. The sensor uses the low power loss component elected, like CMOS integrated circuit. CMOS component antijamming ability, the CMOS logic circuit interference rejection reaches as high as 20%. The low power loss component gives off heat is small, this
33、is advantageous in the sensor designs closely, is advantageous in the sensor steady work. 3 .Output circuit electromagnetic compatibilityThe output circuit is sensors terminating circuit, generally is the non-contact switching circuit. The commonly used output element has the triode and the thyristo
34、r. When triode condition change, causes the electromagnetic radiation. Connects in parallel fashion the RC absorbing circuit between the triode collecting electrode and the emitter electrode, suppresses d i/d t with inductance L, may reduce the electromagnetic radiation the energy. Output circuit el
35、ectromagnetic compatibility designs another method is the shield. The thyristor is shielded, the surge which the LC filter network uses for suppresses when the thyristor movement to produce. The filter network and the screening can earth. For example, the national standard GB3907-83 for industrial b
36、asic measurements of radio interference; GB4824.1-84 for industrial, scientific and medical RF equipment permit the value of radio interference; GB6279-86 for vehicles, motor boats and spark ignition engine driven devices Radio characteristics measurements Ways and permit value. National Radio Manag
37、ement Committee of workers, Branch, medical electronic equipment, such as the use of frequency, bandwidth and maximum radiation field strength have made specific provisions. This electronic equipment to ensure the normal work and normal life of the people, as well as modern science and technology to
38、 promote more rapid development, have played an important role.4 .Antijamming codeThe present, the correspondence, the connection, the bussing technique development also urge the binary sensors intellectualization. AS-Interface is an actuator - sensor - interface bus system. As-Interface bus system
39、are most may install 248 binary sensors. As-Interface chip and the photoelectric sensor coordination, may cause the sensor and as-Interface main line are connected. On the identical main line, many sensors disturb mutually the question is quite serious. This may when the sensor corresponds, joins th
40、e surveillance element in the information (redundant codes) to carry on the antijamming. Like with 00000, 11111 replaces 0, 1. When receives 10111, that may think that mistakenly, and corrected second automatically.Frequency planning at the national and world-wide has been widely used, is to improve
41、 the RF resource utilization as a way to ensure electromagnetic compatibility of radio electronic equipment one of the important measures. Therefore should be strictly in accordance with international agreements (radio frequency allocation table) and the national papers, the implementation of nation
42、al, regional and operational division of the frequency band between the frequency bands allocated. According to the frequency - the principles of space allocation for wireless channel allocation. Frequency planning must ensure that each radio interference with electronic equipment-level minimum, or
43、eliminate the interference by the State Radio Management Committee is responsible for coordinating. 5 .Electromagnetic compatibility experiments The electromagnetic compatibility design confirms and the improvement depending on the electromagnetic compatibility experiment. Now, had the quite perfect
44、 electromagnetic compatibility testing method and the special test equipment. When switch electric appliance movement, forms the intense disturbance, produces the transient state pulse. The IEC61000-4-4 standard makes the stipulation to the electricity fast transient pulse interference, divides into
45、 the individual pulse, crowd of pulses, the pulse group. The pulse group profile cycle is 300 ms, the pulse ties the width is 15 ms.In the individual pulse and crowd of pulses individual pulses width must be smaller than 15ms. IEC1024 stipulated the thunder and lightning analog pulses width must be
46、smaller than 15 ms. The photoelectric sensor interior uses the small electric capacity quite to adapt to the transient pulse filter. If sensor main engine control, then may use the digital filtering, the time delay instruction in the software to suppress the transient disturbance.Consideration shoul
47、d be given to the signal line impedance matching problem. The so-called impedance matching is the signal lines should be consistent with the load signal line characteristic impedance equal. Characteristic impedance and signal line width, and distance from the ground layer as well as the village boar
48、d dielectric constant and other physical factors are the inherent characteristics of signal lines. Impedance mismatch will cause the transmission of the reverse signal to digital waveform generator oscillation, resulting in the logic of chaos. Usually load signal lines are chips, basically stable. Does not match the re
