光電傳感器的制作(Fabricationofphotoelectricsensors)

1、光電傳感器的制作 (Fabrication of photoelectric sensors )發(fā)信人：Death (44death), 信區(qū) Robocon:標(biāo) 題：光電傳感器的制作(轉(zhuǎn)自中科大bbs)發(fā)信站：北京科大夢(mèng)想空間站(Wed Aug 13 01: 06: 50, 2004)光電傳感器探頭的制作光電傳感器探頭由發(fā)光二極管和接收管組成.一.元件介紹1 .發(fā)光二極管 的介紹(LED).做傳感器的led要求亮度高,顏色適宜,光斑形狀適宜.為了預(yù)防led損壞,應(yīng)該注意：1.led的伏安特性曲線很陡,測(cè)試和 使用時(shí)一定要串聯(lián)電阻限制電流或使用內(nèi)阻很大的廢舊電池.2.氮化錢材料的高亮度led容

2、 易被反向電壓,靜電或電源尖峰擊穿損壞,電源電壓較高時(shí)不可反接.不同的管子允許的工作電流不同.紅外的平均電流最大可以用到100 毫安,用作調(diào)制時(shí)幾十微秒的窄脈沖峰值甚至可以接近1安.3毫米的白色高亮度管子是最大電流20毫安不記得是平均值還是峰值.5毫米的允許電流要大一些,但一般也 不超過50毫安.一般低亮度的管子要小一些.工作電流的限制一是發(fā)熱限制平均電流 二是高電流下亮度飽和限制峰值電流.有些管子電流大了之后還會(huì)變色.常用的led有紅外,紅,橙,黃,黃綠,純綠,藍(lán),紫,紫外,白 等顏色.作為成品銷售的變色led是在一個(gè)管殼通常是乳白色的,用于使光線混合 均勻里封裝了多個(gè)不同顏色的led,如果

3、有紅,綠,藍(lán)三色那么非常適合作顏色傳感器 的照明.紅外線led配合紅外接收管抗干擾水平強(qiáng),但是不適合用于識(shí)別顏 色,由于物體在可見光下的顏色不能很好的代表它對(duì)于紅外線的反射率.驗(yàn)鈔用的管子發(fā) 光含有紫色光和紫外線,點(diǎn)亮?xí)r不要正對(duì)著眼睛,也不要靠近觀看或長(zhǎng)時(shí)間觀看.管殼無色透明的管子透光性能好一些,散射小,更適合做傳感器 變色管除外,孚L.白色管殼比無色透明管殼好.管殼有色的管子適合做指示燈.直徑5毫米的管子品種較多,亮度較高,發(fā)出的光束比直徑3毫米的管子要集中(頂角 小),照在物體上光斑小,適合用來識(shí)別白線.直徑3毫米或者貼片 的管子適合用來做電路板上的指示燈.紅外對(duì)管的發(fā)射管和接收管是平行的

4、,容易引起鏡面反射,只適用 于接近開關(guān).Led的伏安特性曲線很陡,可以作穩(wěn)壓用,給電路提供基準(zhǔn)電壓.紅 色的大約1.8v,藍(lán)色的可以超過3v.購(gòu)置的時(shí)候一般到城隍廟的臨江,這里品種比擬多.天香家具城里面的一家電子商店有超高亮度橙紅的管子.2 .接收管的介紹.常用的接收管有硅光電二極管,Silicon photoelectric triode, three kinds of photosensitive resistance.The current generated by the photodiode (microampere), small to high magnification, bu

5、t the speed is very high, high frequency can be adjustedSystem.Identification: characteristics in conditions similar to ordinary diode light.Use: reverse voltage or without voltage, and output light intensity of light is proportional to the current approximation.Phototriode generally does not lead t

6、o the base, only two pins, when buying, called tube.The photoelectric triode produces large current (a few hundred microamps above), without pre high magnification, but the speed is low,The modulation frequency is less than 100KHz.Under shading condition recognition: forward and reverse resistance a

7、re large, with strong light irradiation (such as lamp), can be measured in one directionThe resistance was smaller, the direction is positive.Use: forward voltage 1V, output light intensity and light approximately proportional to the current.The photoelectric receiving tube shell is colorless and tr

8、ansparent and black two, black shell almost only through infrared and infrared.Supporting the use of luminous tube.The electrical characteristics of the photosensitive resistance is not a constant flow resistance, light resistance is greatly reduced, the output current isA large number of similar le

9、vel, phototriode. The working frequency is generally low, but also a high. The most important in the regionDont lie in the photosensitive resistor receive light is a plane, no shell and tube condenser, directional difference. In general do not distinguish betweenThe light direction or to reduce the

10、cost of the circuit.3. receiving tube and distinguish the appearance of the launch tube.Colorless and transparent receiving tube core guard:From the head to look inside, the tube core is black, with a white spot. The tube core area is very large, almost filledtheThe vision, and the tube core around

11、without reflector.The LEDcore is generally around a relatively large area of the metal reflector, the center of the square of the small things die. Black shellThe tube is mostly the infrared receiving tube. Also has the infrared emission tube, but the tube is generally not all blackcolor.4. advanced

12、 materials and spectral characteristics.(1) LED material, color and brightness.The principle of LED light is a semiconductor pn junction in the recombination of electrons and holes generated photons. Different materials due to bandwidthDifferent colors and lead to the turn-on voltage of different. I

13、n addition, the luminous efficiency of different materials (generally in quantum efficiencyMeasure the photon number / emission quantum efficiency = electron number flows) also have great difference.The color of luminescence quantum efficiency (related to the process, here is typical)GaAs GaAs infra

14、red high, 30%GaAsP10%(red phosphorus GaAs, the purchase is called common)Orange, yellow phosphorus content increased with decreasing efficiency, shorter wavelength.Nitrogen doped GaP:Ngreen gap is low, less than 1%(at the time of purchase is called common)Zinc Oxide GaP:ZnOdoped gallium phosphide re

15、d to yellow in thelow (buy called general)AlGaAs (high aluminum gallium arsenide red when buying called high brightness)AlGaInP orange (30% AlGaInP high, buy called high brightness)Gan GaN(including In) from pure green to ultraviolet, 20%(at the time of purchase is called high or super high brightne

16、ss)GaN,The tube core coated with a fluorescent powder purple + yellow =white high (at the time of purchase is called high or super high brightness)Different materials and colors of the tube core is not energized when the color is different, can be used to recognize the tube.Material / color tube cor

17、e colorGaAs/ infrared, GaAsP/ red, red black AlGaAs/GaP/ GaP-ZnO/ green, yellow, red, AlGaInP/ ultra high brightness orange light brownGaN/ from pure green to ultraviolet white, with two metal wire chipGaN core is coated with a fluorescent powder in a large white / yellow and white, the invisible ch

18、ip, with two metal wire(2) receiving the spectral characteristics of tube.The photodiode and phototransistor are semiconductor pn junction photovoltaic element on the photoelectric effect of receiving light, so thePhoton energy exceeds the material band width to be accepted, in - sensitivity spectru

19、m characteristics in the long wave direction with itStop a steep. In the short wave direction if the wavelength is short, the sensitivity will decrease.General silicone tube for infrared to red and yellow light, but has been used for near ultraviolet.Offbeat applications: with a light emitting diode

20、 when the photodiode, its material band is wide, only to receive the short wave visibleLight. The theory can be used to identify the color, but no practical use.Some are more sensitive to visible light photosensitive resistor to the middle part of the.Install filter (can use cellophane) can change t

21、he spectral characteristics of the pipe is convenient to produce all kinds of color.For.Two. The actual production of the sensor probe1. line identification:White tube is definitely right. If the background is green, red or infrared is very good. But the site may haveOf red or blue. This is because

22、our team did not pay attention to this problem and suffer heavy losses. In thisThe case with blue, red or purple (with ultraviolet detector, tube).Geometry is the transmitting tube and the receiving tube an erect a tilt, pointing to the same position to eliminate specular light.(see technical report

23、, the first team in the compilation of 2002 document issued by a team)These pipes can be welded on a small circuit board, in front of a heat shrinkable sleeve reduces divergence, so.Head, but it is neither accurate nor strong interference, the most troublesome is a probe into the array when using a

24、performanceBy.It is a good practice in an aluminum block or woodafter punching the pipe inside, around a black cloth shading.The probe beamshould be small, so the white line was accurate recognition. The distance of the probe adjacent to the right.(see)The probe arrangement is out of control conveni

25、ent to consider, is to put a row of white middle probe tracking, on each side of a numberLine. The middle row probe should be put in front of the driving wheel, the distance as far as possible, the number of multi.Because the carWhen the body is the first line deviation angle deviation accumulated (

26、integral) for lateral deviation, adding two after a probeThe deviation and the white line.The probe is in the front angle deviation accounts for larger proportion, the feedback phase lag of smaller, more easily loop stability, oscillationSmall.Contrary ,On the probe will relatively large oscillation

27、 and divergence.The probe in the front, driving wheels at the back, will be able to use the 2 probe. Considering the turn mayproduce relativelylargeThe lateral deviation, the best placed 3.Probe of small robot direct cause of our failure in the competition this year is to track the white line wrecke

28、r is only two, andThere are two universal wheels, driving wheel skidding seriously. In the build site never a problem, but when we got to BeijingThe problem can not remove the obstacles get out of hand, the result, the top robot blocked.On the probe will put a few more. If placed between the two dri

29、ving wheels will put a long row, or by using PID algorithm.Two rows simultaneously identify transverse position and azimuth.2. kinds of color recognition:If you want to identify a variety of colors, can be used with different filter receiving tube, transmitting tube wheel or several different colors

30、Light flow (including extinguished state) with a receiving tube, then after A/D conversion by mcu.Several tubes must be the same place is to identify the color, and the relative distance can not change. Otherwise it will become black and white.Color.3. proximity switches:Identification of objects ne

31、ar, can use infrared tube + modulation, or directly buy products.Even if the world turns around,The world has changed,The doings of mankind,There is still not the slightest change. Yang WeiliLight source: Beijing science fiction space station.B FROM: 5Sender: death (44death),

32、letter: RoboconTitle: production of Re: photoelectric sensor (from USTC BBS)Transmitting station: Beijing science fantasy space station (Wed Oct 13 01:50:55 2004) (discussed below are reflective sensor color)Back of a few problems, the principle of optical fiber sensors is photoelectric emission and

33、 reception, only through the middle of the lightFiber communication only, why to use fiber, mainly for anti interference, someof the optical fiber sensor is used into some other(forget the specific elements), and the fiber itself has filter function, in order to filter out other stray light, but the

34、sensorThe wavelength of the light (or color) must be carefully chosen. And once using optical fiber as optical media, due to the small fiberCoincidentally, the optical fiber head is made small in very limited space, but also can accept and transmit fiber optical fiber and onTogether, it has an impor

35、tant influence on the accuracy of line tracking, some advanced sensors to the light emitted by diode light sourceBefore the incident focused into the fiber, the fiber head is a lens, which can get approximate linear light.The last method is the most enjoyable, generally the best and most accurate fiber color sensor takes the form of. In 3 LEDlights turn red and green basket provides 3 colors of light (i.e., followed by the RGBtricolor) signal receiving tube are processed into RGBColor combination is measured