电气一班 1102120129 汪志杰.doc

郑州工业应用技术学院学生课程考核专业外文翻译原 文： 光电传感器原理研究 译 文： Study on the principle of photoelectric sensor 学 院： 机电工程学院 专 业： 电气工程及其自动化 班 级： 11电气工程及其自动化一班 课 程： 电气工程专业英语 学生姓名： 汪志杰 学 号： 1102120129 时 间： 2014.12.18 成绩评定： 光电传感器原理研究摘要：随着科技的发展，人类越来越注重信息和自动化，在日常的生产学习过程中，人们常常要进行自动筛选、自动传送，而为了实现这些，光电传感发挥了不可磨灭的作用。光敏传感器的物理基础是光电效应，即光敏材料的电学特性因受到光的照射而发生变化。关键词：光电效应、光电传感器、光敏材料一、 理论基础光电效应光电效应通常分为外光电效应和内光电效应两大类。外光电效应是指在光照射下，电子逸出物体表面的外发射的现象，也称光电发射效应，基于这种效应的光电器件有光电管、光电倍增管等。内光电效应是指入射的光强改变物质导电率的物理现象，称为光电导效应，大多数光电控制应用的传感器，如光敏电阻、光敏二极管、光敏三极管、硅光电池等都属于内光电效应类传感器。1.外光电效应光照在照在光电材料上，材料表面的电子吸收的能量，若电子吸收的能量足够大，电子会克服束缚逸出表面，从而改变光电子材料的导电性，这种现象成为外光电效应。根据爱因斯坦的光电子效应，光子是运动着的粒子流，每种光子的能量为hv(v为光波频率，h为普朗克常数)，由此可见不同频率的光子具有不同的能量，光波频率越高，光子能量越大。假设光子的全部能量交给光子，电子能量将会增加，增加的能量一部分用于克服正离子的束缚，另一部分转换成电子能量。根据能量守恒定律： 式中，m为电子质量,v为电子逸出的初速度,w为逸出功。由上式可知，要使光电子逸出阴极表面的必要条件是hvw。由于不同材料具有不同的逸出功，因此对每一种阴极材料，入射光都有一个确定的频率限，当入射光的频率低于此频率限时，不论光强多大，都不会产生光电子发射，此频率限称为“红限”。相应的波长为 式中，c为光速，w为逸出功。2.内光电效应 当光照射到半导体表面时,由于半导体中的电子吸收了光子的能量,使电子从半导体表面逸出至周围空间的现象叫外光电效应。利用这种现象可以制成阴极射线管、光电倍增管和摄像管的光阴极等。半导体材料的价带与导带间有一个带隙,其能量间隔为Eg。一般情况下,价带中的电子不会自发地跃迁到导带,所以半导体材料的导电性远不如导体。但如果通过某种方式给价带中的电子提供能量,就可以将其激发到导带中,形成载流子,增加导电性。光照就是一种激励方式。当入射光的能量hEg（ Eg为带隙间隔)时,价带中的电子就会吸收光子的能量,跃迁到导带,而在价带中留下一个空穴,形成一对可以导电的电子空穴对。这里的电子并未逸出形成光电子,但显然存在着由于光照而产生的电效应。因此,这种光电效应就是一种内光电效应。从理论和实验结果分析,要使价带中的电子跃迁到导带,也存在一个入射光的极限能量,即E=h0=Eg,其中0是低频限(即极限频率0=Egh)。这个关系也可以用长波限表示,即0=hcEg。入射光的频率大于0或波长小于0时,才会发生电子的带间跃迁。当入射光能量较小,不能使电子由价带跃迁到导带时,有可能使电子吸收光能后,在一个能带内的亚能级结构间跃迁。二、 光电传感器的应用 光敏电阻可用于进行光的测量和光的控制，测量方面主要是用于测量光强，控制方面最常见的就是路灯控制和楼道感应灯的控制，在电路接通的状态下，路灯会随着周围光强的变化而变化，楼道中的灯白天不亮晚上亮也利用了光敏电阻的对光的感应特点。光敏电阻还被应用于海上导航，通常海上的浮标用的就是光敏电阻作为航道灯的开关，到晚上光敏电阻阻值变小，接通控制电路，将灯打开；白天光敏电阻增大将控制电路断开，关掉电灯。光敏管大体有开关作用，环境光检测作用，各种光线接收作用。在太阳能自动跟踪控制中，做光电检测用，接受太阳光，校正方位。光敏二级管被应用于收音机、电视、电脑等设备中，比如用LED发光二极光替代液晶显示器背后的光源，能达到节能且稳定的作用。光敏三极管可用来控制开关的状态，其主要原因是三极管对光照强度十分敏感，可以根据根据光照强弱来控制电流大小，从而在继电器的配合下控制开关的通断状态，实现自动化控制。由于光敏管对光的敏感性很高，还可用于测量温度，因为不同温度的物体辐射的光不同，以此可以间接测量温度。此外，光敏三极管还可用于传输信号，如光藕合器，光耦合器亦称光电隔离器，简称光耦，光耦合器以光为媒介传输电信号，它对输入、输出电信号有良好的隔离作用，所以，它在各种电路中得到广泛的应用。另外，红光光敏管可用于测量红外线，这一点可用来做夜视仪硅光电池在日常生活中也是十分常见的，因为它能将光能转变为电能，像一些太阳能发电板和太阳能电池中就有硅光电池，被广泛用于卫星、太阳能发电、太阳能热水器以及手机等。光电传感器的用途很多很广，还有一些等待我们去发现。比如我们经常抱怨阳光下看不清手机和电脑，我们可以利用光敏器件来改变手机和电脑的屏幕亮度，从而更能看清楚，。还有我们的空调，可以通过检测红外线自动调至人的舒适温度，当温度过低或过高就开启调节装置，若在人体舒适范围左右则可关闭调节装置，从而节省能源。我们还可以穿一件有硅光电池板的衣服，衣服内有温度调节装置，由硅光电池提供能源，调节温度。 参考资料：大学物理（王磊 陈刚 聂娅） 现代传感技术（李科杰） 传感器原理与测试技术（李晓莹） 传感器原理及应用（王雪文 张志勇）Study on the principle of photoelectric sensorAbstract: with the development of science and technology, human pay more and more attention to information and automation, in the production process of learning everyday, people often to be automatic selection, automatic transmission, and to achieve these, photoelectric sensor has played an indelible role. The physical basis of photosensitive sensor is the photoelectric effect, that is, the electrical properties of photosensitive material by light irradiation and change.Keywords: photosensitive materials, photoelectric sensor, photoelectric effectOne, the theoretical basis - the photoelectric effect The photoelectric effect is usually divided into external photoelectric effect and the photoelectric effect two categories. The photoelectric effect is in the light, electron escape the surface of the launch of the phenomenon, also known as the photoelectric emission effect, the effect of optoelectronic devices based on photoelectric tube, photomultiplier tube etc. The photoelectric effect refers to the physical phenomenon of incident light intensity changing material conductivity, known as the photoelectric effect photoelectric sensor, most control applications, such as a photosensitive resistance, a photosensitive diode, light activated triode, silicon photocell belong to the inside of the photoelectric effect sensor.1 external photoelectric effect The light shines in the photo on photoelectric materials, the surface of the material of the electronic absorption energy, if the electronic absorption energy is large enough, the electronic will overcome bound escape surface, conductive and thus change the optoelectronic materials, this phenomenon become external photoelectric effect. According to Einstein of the photoelectron effect, the photon is the movement of the particle flow, each photon energy is HV (V is the optical frequency, h for the Planck constant), thus different frequency photons with different energy, wave frequency is higher, the greater the photon energy. All the energy to assume photon photon, electron energy will increase, part of the energy to increase to overcome the bound of the positive ions, the other part is converted into electronic energy. According to the law of conservation of energy: In the formula, M is the electron mass, V as the electron escape initial velocity, w for the work function. Based on the formula one, to make the necessary condition of photoelectron escape on the cathode surface is hvw. Because different materials have different work functions, so every kind of cathode material, the incident light has a certain frequency limit, when the incident light frequency below this frequency limit, no matter how large the intensity, will not produce the photoelectron emission, this frequency limits is called the red limit. The corresponding wavelength in the formula , C is the speed of light, w work.2 internal photoelectric effect When light is irradiated to a semiconductor surface, because the electrons in a semiconductor absorbs the photon energy, the electrons from the semiconductor surface escape into the surrounding space phenomena is called the outer photoelectric effect. This phenomenon can be made using a cathode ray tube, photomultiplier tubes and time camera tube pole etc. Valence and conduction band of the semiconductor material with a band gap, the energy interval is Eg. In general, the valence band electron not spontaneously to the conduction band, so the conductivity of the semiconductor materials far less conductor. But if to electrons in valence band to provide energy in a way that it can be excited into the conduction band, formation of the carrier, the increase in conductivity. Light is a kind of incentive mode. When the incident energy of H V is greater than or equal to Eg (Eg band gap), electrons will the valence band absorption of photon energy, to the conduction band, leaving a hole in the valence band, the formation of a conductive electron hole pairs. Here the electronic did not escape the photoelectron, but apparently there because the light generated electricity effect. Therefore, the photoelectric effect is a kind of photoelectric effect. From the theoretical analysis and experimental results, in order to make the electronic transitions in the valence band to the conduction band, there is a limit of the energy of incident light, i.e. E lambda =h V 0=Eg, V 0 is the lowest one (i.e. frequency limit V 0=Egh). This relationship can also be expressed by the long wave limit, i.e. lambda 0=hcEg. The incident light frequency is greater than 0 or less than V wavelength lambda 0, electronic interband transition will occur. When the energy of incident light is small, cannot make the electrons from the valence band to the conduction band, may make the electronic light is absorbed in a sub level structure with internal .Two, photoelectric sensor Photosensitive resistance can be used to control the measurement and light is light, the measurement is mainly used for the measurement of light intensity, the most common control control is the control of street lamp and corridor induction lamp, the circuit on state, street lamps will change with the ambient light intensity, the building during the day not bright lights in the evening light is using the induction characteristics of light photosensitive resistor. Photosensitive resistance has also been used in maritime navigation, switches are usually the buoy is used as channel light photosensitive resistor, until the evening of photosensitive resistance small, connected to the control circuit, the lights will be opened; the day of photosensitive resistance increase general control circuit is off, turn off the lights. The photosensitive tube generally have switch function, ambient light detection function, various light receiving function. In the solar energy automatic tracking control, do the photoelectric detection, to accept the sun, calibration range. Photo two tubes were used in radio, television, computer and other equipment, light source such as the use of LED light emitting diode instead of the back of a liquid crystal display, to achieve energy saving and stable effect. The photosensitive triode can be used to control the state of the switch, the main reason is the triode to light intensity is very sensitive, can according to the light intensity to control the current size, so as to control the switch in the relay coordination under the off state, automation control. Because the photosensitive tube and the sensitivity to light is very high, can also be used to measure temperature, because of the different temperature radiation object light is different, which can indirectly measure the temperature. In addition, the photosensitive triode can also be used to transmit signals, such as optical coupling device, optical coupler, also known as optical isolators, referred to as coupler, optical coupler to transmit light signals for the media, its input and output signals have good isolation effect, so it was widely used in a variety of circuit. In addition, the red light sensitive tube can be used for measuring the infrared, this point can be used for night vision instrument Silicon light battery is very common in daily life, because it can convert the energy of sunlight into electricity, like some