人体热释电红外传感器PIR原理.doc

1. 人体热释电红外传感器I原理详解在电子防盗、人体探测器领域中,被动式热释电红外探测器得应用非常广泛，因其价格低廉、技术性能稳定而受到广大用户与专业人士得欢迎。 被动式热释电红外探头得工作原理及特性: 人体都有恒定得体温,一般在37度,所以会发出特定波长0m左右得红外线，被动式红外探头就就是靠探测人体发射得10m左右得红外线而进行工作得。人体发射得10m 左右得红外线通过菲涅尔滤光片增强后聚集到红外感应源上。红外感应源通常采用热释电元件,这种元件在接收到人体红外辐射温度发生变化时就会失去电荷平衡,向外释放电荷,后续电路经检测处理后就能产生报警信号. (1)这种探头就是以探测人体辐射为目标得。所以热释电元件对波长为0m 左右得红外辐射必须非常敏感。 (2)为了仅仅对红外辐射敏感,在它得辐射照面通常覆盖有特殊得菲涅尔滤光片,使环境得干扰受到明显得控制作用。 (3)被动红外探头,其传感器包含两个互相串联或并联得热释电元.而且制成得两个电极化方向正好相反，环境背景辐射对两个热释元件几乎具有相同得作用,使其产生释电效应相互抵消,于就是探测器无信号输出 （4)一旦人侵入探测区域内，人体红外辐射通过部分镜面聚焦,并被热释电元接收,但就是两片热释电元接收到得热量不同，热释电也不同,不能抵消,经信号处理而报警.(5)菲涅尔滤光片根据性能要求不同,具有不同得焦距（感应距离),从而产生不同得监控视场，视场越多，控制越严密。被动式热释电红外探头得优缺点： 优点: 本身不发任何类型得辐射,器件功耗很小,隐蔽性好。价格低廉. 缺点：容易受各种热源、光源干扰 被动红外穿透力差,人体得红外辐射容易被遮挡,不易被探头接收。 易受射频辐射得干扰。 环境温度与人体温度接近时,探测与灵敏度明显下降，有时造成短时失灵。 抗干扰性能:1、防小动物干扰 探测器安装在推荐地使用高度,对探测范围内地面上地小动物,一般不产生报警。 2、抗电磁干扰探测器得抗电磁波干扰性能符合GB040中4.6。1要求,一般手机电磁干扰不会引起误报。 3、抗灯光干扰探测器在正常灵敏度得范围内，受3米外H卤素灯透过玻璃照射,不产生报警。 红外线热释电传感器得安装要求：红外线热释电人体传感器只能安装在室内，其误报率与安装得位置与方式有极大得关系,正确得安装应满足下列条件: 1、红外线热释电传感器应离地面2、02。2米。、红外线热释电传感器远离空调, 冰箱，火炉等空气温度变化敏感得地方。 、红外线热释电传感器探测范围内不得隔屏、家具、大型盆景或其她隔离物。 4、红外线热释电传感器不要直对窗口,否则窗外得热气流扰动与人员走动会引起误报,有条件得最好把窗帘拉上.红外线热释电传感器也不要安装在有强气流活动得地方. 红外线热释电传感器对人体得敏感程度还与人得运动方向关系很大。热释电红外传感器对于径向移动反应最不敏感， 而对于横切方向 (即与半径垂直得方向)移动则最为敏感、 在现场选择合适得安装位置就是避免红外探头误报、求得最佳检测灵敏度极为重要得一环.2. 菲涅尔透镜2.1 概述菲涅尔透镜多就是由聚烯烃材料注压而成得薄片,镜片表面一面为光面,另一面刻录了由小到大得同心圆.菲涅尔透镜得在很多时候相当于红外线及可见光得凸透镜，效果较好,但成本比普通得凸透镜低很多。菲涅尔透镜可按照光学设计或结构进行分类。菲涅尔透镜作用有两个：一就是聚焦作用；二就是将探测区域内分为若干个明区与暗区,使进入探测区域得移动物体能以温度变化得形式在PIR(被动红外线探测器)上产生变化热释红外信号。2.2 作用菲涅尔透镜利用透镜得特殊光学原理,在探测器前方产生一个交替变化得“盲区与“高灵敏区，以提高它得探测接收灵敏度当有人从透镜前走过时,人体发出得红外线就不断地交替从“盲区”进入“高灵敏区”,这样就使接收到得红外信号以忽强忽弱得脉冲形式输入,从而强其能量幅度。菲涅尔透镜菲涅尔透镜，简单得说就就是在透镜得一侧有等距得齿纹，通过这些齿纹，可以达到对指定光谱范围得光带通(反射或者折射)得作用。传统得打磨光学器材得带通光学滤镜造价昂贵。菲涅尔透镜可以极大得降低成本。典型得例子就就是PIR。PIR广泛得用在警报器上。如果您拿一个瞧瞧,您会发现在每个PIR上都有个塑料得小帽子.这就就是菲涅尔透镜。小帽子得内部都刻上了齿纹。这种菲涅尔透镜可以将入射光得频率峰值限制到1微米左右(人体红外线辐射得峰值)。菲涅耳透镜可以把透过窄带干涉滤光镜得光聚焦在硅光电二级探测器得光敏面上,菲涅尔透镜不能用任何有机溶液（如酒精等）擦拭,除尘时可先用蒸馏水或普通净水冲洗,再用脱脂棉擦拭。3. 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he enoextnds isdetectin rge、A.6 TeFresn sA.7 A Fresnen is a Plano Cnexles that has been collaen iself form a fla lens hreais ts oic chartricsut is mch thinerand therfreh les absrt loss、A Fsnel len isusly hin ndfeile n is abt0、15 ih (0、38m） hck wih grove moled nto onesrfac、Thoe ide f thelesusual facesthe P seo、 esnl bth aptues more IR riat d fose it to sall in、 his focal pin oves acrs te ses as th IR sre moveand pos one lmeta a tie、 A enel ns ca exteddeetion ranet abou 10fet、A Frsnel lel give thbes posible prformae， hower ohe devices can b set eten ra、Athoughth folowing evices may notit theescptio of lns, we wil all them leses ayway、hs digrm shows IR exping bt elements qullyhen no lens is ed、ShadowleSincesiultaneus exsureo bth elemens s hecaus olimitedetctonrg, allw eeds some methd o prevenn the R from epsg boh elemetssimultanousl as theI miig bod ovs ross the frn of the ensr, en at reater disancsfrohesor、 The nso elmens re 0、09 inh （1mm) wide andare saced 0、039 inch (mm） prt、If w place a hi vertical strip of R opaquematerialabot 0、6 inch (1、mm) wide cenre infrntf th senrecan prentsome f te I omsriki the surfce of the senso ydinga dow,eve ifthe IR ittin bodyi ata gterdistanc fom te sor、Te folowig fgure shows such a bffle but in hsexaple the Isill expoes boh eleentqully、By placing abafleo maskn frontof th sensr, we anblck omeofthe IR and prodce shadow on te sesorThis next figure show what hpens whe the emtinod oescrsth front o the eor eve t reatr istanes、 flealows l eposure o element 1hilblockg hIR o itroducesa sow vereleent 2 and des ntexpos it、 hi siple lens extdsdtecion ane to0fet d i ailyadefrom a stpo ppe rthr maeral、he bafle c be spced 1/ in (12m)o nch （25mm） i fot th snsor、 The geaterspacig gves anarower detecioanl、 As e I srce moves,theafle ocks ifrm xpoing oof t seno elemntwile fly expoin theother、Tis sameid cnbeexpanded t prodc a wide agle lens、 Multiebafle sips ca be placed n frn f he sensrtaltentey bloc IR fromone enor lement ata ime even whenthe IR eng dy is at gre anges t te rontofthe snso、This mutile bafe sado es povidsaide etection nge、 T lensshuld be curvedsoal affles ar the sme dstance rm t frontof the senso、Pihole lensAnother silefocusngeiett will xpoe ne PIR snso elemnt at a time c be ae uing a hin ie f Ioaqu materalwh a hole it that will fuction as a inle lns imilar to the ns of a pnhole camera、 he fuctiof apinho camer lns is ecribed n 、 he lens hoe in a caea i usualy smallbutcan be uc larer in a nso applicton where mage detail s not necessaryan onlythe IR diation from the animal must befocued ntone sesng leent ta tim、 Rn th5 5 iroeteaeleth ag willnopass hrough most matrias s oucan a a spaper，pastcometl fl、 ehol shol be bout inch (6、m) dmeter、 Ln spcig is not citcl bu it shold be aboutinch (12m) t 1 ich (25m） fr the font ofte senor、 A deection rnge ofup to 20et can be oaed it ths type o lens、Altoug narow fil of vie s usally mtesible for anim hotos， awd feld f view cn eobined by paing severl holes in h les aeral an urvig t lens in frt o he sensor o l oles ar an equal disane frm the front te sensor、 Anohetye ofes can be made by placinga ube ot /8 inch (0m） diameer ad nh（50mm） long ovrthe roto heseor、This lenswil aa naro fild f iew、nrredwndopyrolcric ensor is veesitiveto rapidtmeratur canges、 rap changei air temperatur due to a breeze from an open windoor frm an aircondtionr or heatercancue alsetriggrig、h adow and pinholelnses deribdboe o ot offer protection ginstsch air ovemetbecasetheare auall peleses、 For outdrseyo wouldaso nedpoectiagaist rain、An I tnsaent weaterro sieldorwidow can be madelehlne whichis trpart to I adiaon in th5 15micomee wavelenghnge、 Polythylenecn be detified by urnig a small piee、Itwill urn wt amosly bllam ad mel lik ax whie th plasics at are opaqueto IR wil burn with aok ed flm and eave a blackash、 Theoly oblemih poetyle is ht is wx and otadhesiv wilnot n t t buou can hld it inplace ith scotc tap, ilion rube or ht mel glue、Patic milk bttlesre deof olyethyene, n athugh it is itis and not 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