外文翻譯--傳感器的基礎(chǔ)知識(shí)

1、<p>　　中國地質(zhì)大學(xué)長(zhǎng)城學(xué)院</p><p>　　本科畢業(yè)論文外文資料翻譯</p><p>　　系 別： 信息工程系 </p><p>　　專 業(yè)： 電氣工程及其自動(dòng)化 </p><p>　　姓 名： 孫一峰 </p><p>　　學(xué)

2、 號(hào)： 04309435 </p><p>　　2013 年 3 月 22 日</p><p><b>　　外文資料翻譯譯文</b></p><p><b>　　傳感器的基礎(chǔ)知識(shí)</b></p><p>　　傳感器是一種把被測(cè)量轉(zhuǎn)換為光的、機(jī)械的或者更平常的電信號(hào)的裝置。能量

3、轉(zhuǎn)換的過程稱之為換能。</p><p>　　按照轉(zhuǎn)換原理和測(cè)量形式對(duì)傳感器進(jìn)行分類。用來測(cè)量位移的電阻式傳感器被歸為電阻式位移傳感器。分類如壓力波紋管、壓力膜和壓力閥等。</p><p><b>　　1傳感器元件</b></p><p>　　除特例外，大多數(shù)的傳感器都由敏感元件、轉(zhuǎn)換元件或控制元件組成。如振動(dòng)膜、波紋管、應(yīng)力管和應(yīng)力環(huán)、低音管和

4、懸臂都是敏感元件，它們對(duì)壓力和力作出響應(yīng)把物理量轉(zhuǎn)變成位移。然后位移可以改變電參數(shù)，如電壓、電阻、電容或者感應(yīng)系數(shù)。機(jī)械式和電子式元件合并形成機(jī)電式傳感設(shè)備或傳感器。這樣的組合可用來輸入能量信號(hào)。熱的，光的，磁的和化學(xué)的相互結(jié)合產(chǎn)生的熱電式、光電式、電磁式和電化學(xué)式傳感器。</p><p><b>　　2傳感器靈敏度</b></p><p>　　通過校正測(cè)量系統(tǒng)獲得的

5、被測(cè)物理量和傳感器輸出信號(hào)的關(guān)系叫做傳感器靈敏度K1，也就是K1=輸出信號(hào)增量/測(cè)量增量。實(shí)際中，傳感器的靈敏度是已知的，并且通過測(cè)量輸出信號(hào)，輸入量由下式?jīng)Q定，輸入量=輸出信號(hào)增量/K1。</p><p><b>　　3理想傳感器的特性</b></p><p>　　（1）高保真性：傳感器輸出波形應(yīng)該真實(shí)可靠地再現(xiàn)被測(cè)量，并且失真很小。</p><

6、p>　　（2）可測(cè)量最小的干擾，任何時(shí)候傳感器的出現(xiàn)不能改變被測(cè)量。</p><p>　?。?）尺寸：傳感器必須能正確地放在所需的地方。</p><p>　?。?）被測(cè)量和傳感器信號(hào)之間應(yīng)該有一個(gè)線性關(guān)系。</p><p>　?。?）傳感器對(duì)外部影響的靈敏度應(yīng)該小，例如壓力傳感器經(jīng)常受到外部振動(dòng)和溫度的</p><p><b>

7、;　　響。</b></p><p>　?。?）傳感器的固有頻率應(yīng)該避開被測(cè)量的頻率和諧波。</p><p><b>　　4電傳感器</b></p><p>　　電傳感器具有許多理想特性。它們不僅實(shí)現(xiàn)遠(yuǎn)程測(cè)量和顯示，還能提供高靈敏度。</p><p>　　電傳感器可分為兩大類。</p><p

8、><b>　　4.1變參數(shù)型</b></p><p><b>　　電阻式；</b></p><p><b>　　電容式；</b></p><p><b>　　自感應(yīng)式；</b></p><p><b>　　互感應(yīng)式；</b>&l

9、t;/p><p>　　這些傳感器的工作依靠外部電壓。</p><p><b>　　4.2自激型</b></p><p><b>　　電磁式；</b></p><p><b>　　熱電式；</b></p><p><b>　　光柵式；</b&g

10、t;</p><p><b>　　壓電式；</b></p><p>　　這些傳感器根據(jù)測(cè)量輸入值產(chǎn)生輸出電壓，而且這一過程是可逆的。比如，在一般情況下，壓電式傳感器可根據(jù)晶體材料的變形產(chǎn)生一個(gè)輸出電壓；但是，如果在材料上施加一個(gè)可變電壓，傳感器可以通過變形或與變電壓同頻率的振動(dòng)來體現(xiàn)可逆效應(yīng)。</p><p><b>　　5電阻式傳感

11、器</b></p><p>　　電阻式傳感器可以分為兩大類：</p><p>　　那些表現(xiàn)為大電阻變化的物理量可通過分壓方式進(jìn)行測(cè)量，電位器就屬于此類。</p><p>　　那些表現(xiàn)為小電阻變化的物理量可通過橋電路方式進(jìn)行測(cè)量，這一類包括應(yīng)變儀和電阻溫度計(jì)。</p><p><b>　　5.1 電位器</b>

12、</p><p>　　繞線式電位器由許多繞在非導(dǎo)體骨架的電阻絲以及滑行在線圈上的觸頭組成。結(jié)構(gòu)原理如圖，觸頭能夠轉(zhuǎn)動(dòng)、直線式運(yùn)動(dòng)或者兩運(yùn)動(dòng)合成的螺旋式運(yùn)動(dòng)。 如果測(cè)量設(shè)備的電阻比電位器的電阻大，那么電壓既可以是交流也可以是直流，且輸出電壓與輸入運(yùn)動(dòng)成正比。 這樣的電位器存在著分辨率和電子噪聲的問題。分辨率是指?jìng)鞲衅髂軝z測(cè)到的最小的輸入增量，分辨率大小取決于線圈與滑動(dòng)觸頭圍成的面積。因此，輸出電壓為

13、觸頭從一端移到另一端時(shí)一系列階躍。 電子噪聲可以通過接觸電阻的振動(dòng)、觸頭摩擦形成的機(jī)械磨損以及從敏感元件傳出的觸頭振動(dòng)產(chǎn)生。另外，測(cè)得的運(yùn)動(dòng)量可以通過慣性和電位器中移動(dòng)元件的摩擦獲得較大的機(jī)械載荷。觸頭表面的磨損將電位器的壽命限制為多少轉(zhuǎn)。通常指的是生產(chǎn)商在說明書中提及的“壽命轉(zhuǎn)數(shù)”，一個(gè)典型值為20*1000000轉(zhuǎn)。空載電位器電路的輸出電壓V0由下式?jīng)Q定：設(shè)電阻R1= xi/xt *Rt，其中xi為輸入位移，xt為最大可能

14、位移，Rt為電位器的電阻。那么輸入電壓V0= V* R1/(R1+( Rt-R1))=V*R1/Rt=V*xi/xt*Rt/Rt=V*xi/xt 上式表明，對(duì)于空載電</p><p><b>　　5.2電阻應(yīng)變儀</b></p><p>　　電阻應(yīng)變儀是由機(jī)械應(yīng)變產(chǎn)生電阻變化的傳感器。它們可以是耦合的或者非耦合的</p><p>　　5.2.1

15、耦合應(yīng)變儀</p><p>　　運(yùn)用黏合劑可將應(yīng)變儀與被檢測(cè)的結(jié)構(gòu)或部件的表面粘合或粘牢。 耦合應(yīng)變儀分為：</p><p>　　粘合在絕緣紙背后的金屬細(xì)絲儀</p><p>　　在環(huán)氧樹脂上粘貼導(dǎo)電箔片的光柵</p><p>　　在環(huán)氧樹脂上粘貼銅或鎳的半導(dǎo)體絲</p><p>　　電阻應(yīng)變儀可作為單個(gè)元件僅

16、在一個(gè)方向測(cè)量應(yīng)力，或者幾個(gè)元件的組合體可在幾個(gè)方向同時(shí)進(jìn)行測(cè)量。</p><p>　　5.2.2非耦合應(yīng)變儀</p><p>　　一典型應(yīng)變儀表明細(xì)電阻絲在懸臂彈簧偏差作用下改變電阻絲張力進(jìn)而改變電阻絲的阻值。商業(yè)上通常在力、負(fù)載、壓力傳感器上運(yùn)用此方法。</p><p>　　5.3電阻溫度傳感器</p><p>　　此傳感器的材料有以下兩

17、大類</p><p>　　金屬（如鉑、銅、鎢、鎳）的阻值會(huì)隨著溫度的升高而增大，即有一個(gè)正溫度電阻系數(shù)。</p><p>　　半導(dǎo)體，如用錳、鈷、鉻或鎳的氧化物制成的電熱調(diào)節(jié)器，其阻值變化與溫度變化存在一個(gè)非線性關(guān)系，即通常有一個(gè)負(fù)溫度電阻系數(shù)。</p><p>　　5.3.1金屬電阻溫度傳感器</p><p>　　在窄溫度變化范圍內(nèi)，此類傳

18、感器取決于以下關(guān)系：R1=R0[1+a(b1-b0)]式中，a阻抗系數(shù)，R0為b0=0°時(shí)C的電阻</p><p>　　5.3.2電熱調(diào)節(jié)器（半導(dǎo)體）電阻溫度傳感器</p><p>　　電熱調(diào)節(jié)器為感溫電阻器，其阻值變化與溫度變化呈非線性關(guān)系。通常此類傳感器有一負(fù)溫度系數(shù)。對(duì)于小的溫度增量，阻值的變化大體呈線性，但是如果存在大的溫差，測(cè)量電路需運(yùn)用特定線性化技術(shù)生成電阻隨溫度變

19、化的線性關(guān)系。</p><p>　　電熱調(diào)節(jié)器通常被制成附有玻璃質(zhì)釉的半導(dǎo)體圓盤形狀。由于電熱調(diào)節(jié)器可以小到1mn，所以響應(yīng)的時(shí)間非?？臁?lt;/p><p><b>　　5.4 光敏元件</b></p><p>　　光敏元件采用光敏半導(dǎo)體材料做成。當(dāng)照射在半導(dǎo)體上的光強(qiáng)度增大，金屬電極間的阻抗就會(huì)降低。光敏元件常用的半導(dǎo)體材料有硫化鎘、硫化鉛和銅

20、鍺化合物。</p><p>　　頻率的有效范圍由所用材料決定。硫化鎘主要適用于可見光，硫化鉛在紅外線區(qū)有峰值響應(yīng)，所以最適合于光故障檢測(cè)以及溫度測(cè)量。</p><p>　　5.5 放射性光元件</p><p>　　當(dāng)光照射到放射性光元件的陰極時(shí)，電子就會(huì)獲取足夠能量到達(dá)陰極。陰極就會(huì)吸收這些電子產(chǎn)生一個(gè)通過電阻R的電流，從而形成一輸出電壓V。</p>

21、<p>　　產(chǎn)生的光電壓V=I.R式中，I為光發(fā)射電流，I=K.B且為靈敏度，B輸入照度（lm）盡管輸出電壓能夠表示照明的強(qiáng)度，這類元件卻更多的應(yīng)用于計(jì)算或調(diào)節(jié)，這里照射到陰極的光可被中斷。</p><p><b>　　6電容式傳感器</b></p><p>　　電容量隨著相對(duì)介電常數(shù)、截面面積、或者極板間的距離的變化而變化。電容的特征曲線表明，在空間的一

22、段范圍內(nèi)，截面面積和相對(duì)介電常數(shù)的變化與電容量變化成線性關(guān)系。不象電位器，變極距型電容傳感器有無限的分辨率，這最適合測(cè)量微小的位移增量的位移。</p><p><b>　　7電感式傳感器</b></p><p>　　電感可以通過改變電感電路的阻抗來調(diào)節(jié)。電容式和電感式傳感器的測(cè)量技術(shù)：</p><p>　　用差分式電容或電感作為交流電橋。&

23、lt;/p><p>　　用交流電位計(jì)電路做動(dòng)態(tài)測(cè)量。</p><p>　　用直流電路為電容器提供正比于容值變化的電壓。</p><p>　　采用調(diào)頻法，C或者L隨著振蕩電路頻率的變化而改變。</p><p>　　電容式和電感式傳感器的一些重要特性如下：</p><p><b>　　分辨率無限。</b>

24、</p><p>　　精確到滿量程的+-0.1%。</p><p>　　位移范圍從25*10-6m到10-3m。</p><p>　　上升時(shí)間小于50us</p><p>　　典型的被測(cè)量是位移、壓力、振動(dòng)量、聲音和液位。</p><p>　　8線性調(diào)壓器9壓電式傳感器10電磁式傳感器11熱電式傳感器12光電管

25、</p><p>　　13機(jī)械式傳感器及敏感元件</p><p><b>　　外文原文</b></p><p>　　Basic knowledge of transducers</p><p>　　A transducer is a device which converts the quantity being me

26、asured into an optical, mechanical, or-more commonly-electrical signal.  The energy-conversion process that takes place is referred to as transduction.Transducers are classified according to the transduction

27、principle involved and the form of the measured. Thus a resistance transducer for measuring displacement is classified as a resistance displacement transducer. Other classification examples are pressure bellows, force di

28、aphragm, </p><p>　　1、Transducer Elements</p><p>　　Although there are exception ,most transducers consist of a sensing element and a conversion or control element. For example, diaphragms,bellows

29、,strain tubes and rings, bourdon tubes, and cantilevers are sensing elements which respond to changes in pressure or force and convert these physical quantities into a displacement. This displacement may then be used to

30、change an electrical parameter such as voltage, resistance, capacitance, or inductance. Such combination of mechanical and electrical el</p><p>　　Transducer Sensitivity</p><p>　　The relationship

31、 between the measured and the transducer output signal is usually obtained by calibration tests and is referred to as the transducer sensitivity K1= output-signal increment / measured increment . In practice, the transdu

32、cer sensitivity is usually known, and, by measuring the output signal, the input quantity is determined from input= output-signal increment / K1. </p><p>　　3、Characteristics of an Ideal Transducer</p>

33、<p>　　The high transducer should exhibit the following characteristics</p><p>　　high fidelity-the transducer output waveform shape be a faithful reproduction of the measured; there should be minimum di

34、stortion.</p><p>　　There should be minimum interference with the quantity being measured; the presence of the transducer should not alter the measured in any way.</p><p>　　Size. The transducer m

35、ust be capable of being placed exactly where it is needed.</p><p>　　There should be a linear relationship between the measured and the transducer signal.</p><p>　　The transducer should have mini

36、mum sensitivity to external effects, pressure transducers,for example,are often subjected to external effects such vibration and temperature.</p><p>　　The natural frequency of the transducer should be well s

37、eparated from the frequency and harmonics of the measurand.</p><p>　　Electrical Transducers</p><p>　　Electrical transducers exhibit many of the ideal characteristics. In addition they offer high

38、 sensitivity as well as promoting the possible of remote indication or mesdurement. Electrical transducers can be divided into two distinct groups:</p><p>　　4.1 variable-control-parameter types,which inc

39、lude:</p><p>　　Resistance</p><p>　　Capacitance</p><p>　　Inductance</p><p>　　mutual-inductance types</p><p>　　These transducers all rely on external excitat

40、ion voltage for their operation.</p><p>　　4.2 self-generating types,which include</p><p>　　Electromagnetic</p><p>　　Thermoelectric</p><p>　　Photoemissive</p><

41、;p>　　piezo-electric types</p><p>　　These all themselves produce an output voltage in response to the measurand input and their effects are reversible. For example, a piezo-electric transducer normally pro

42、duces an output voltage in response to the deformation of a crystalline material; however, if an alternating voltage is applied across the material, the transducer exhibits the reversible effect by deforming or vibrating

43、 at the frequency of the alternating voltage.</p><p>　　Resistance Transducers</p><p>　　Resistance transducers may be divided into two groups, as follows:</p><p>　　Those which experi

44、ence a large resistance change, measured by using potential-divider methods. Potentiometers are in this group.</p><p>　　Those which experience a small resistance change, measured by bridge-circuit methods. E

45、xamples of this group include strain gauges and resistance thermometers.</p><p>　　5.1 Potentiometers</p><p>　　A linear wire-wound potentiometer consists of a number of turns resistance wire woun

46、d around a non-conducting former, together with a wiping contact which travels over the barwires. The construction principles are shown in figure which indicate that the wiper displacement can be rotary, translational, o

47、r a combination of both to give a helical-type motion. The excitation voltage may be either a.c. or  d.c. and the output voltage is proportional to the input motion, provided the measuring device </p>&l

48、t;p>　　Such potentiometers suffer from the linked problem of resolution and electrical noise. Resolution is defined as the smallest detectable change in input and is dependent on the cross-sectional area of the winding

49、s and the area of the sliding contact. The output voltage is thus a serials of steps as the contact moves from one wire to next.</p><p>　　Electrical noise may be generated by variation in contact resistance,

50、 by mechanical wear due to contact friction, and by contact vibration transmitted from the sensing element. In addition, the motion being measured may experience significant mechanical loading by the inertia and friction

51、 of the moving parts of the potentiometer. The wear on the contacting surface limits the life of a potentiometer to a finite number of full strokes or rotations usually referred to in the manufacture’s specifica</p>

52、;<p>　　The output voltage V0 of the unload potentiometer circuit is determined as follows. Let resistance R1= xi/xt *Rt where xi = input displacement, xt= maximum possible displacement, Rt total resistance of the

53、potentiometer. Then output voltage V0= V* R1/(R1+( Rt-R1))=V*R1/Rt=V*xi/xt*Rt/Rt=V*xi/xt. This shows that there is a straight-line relationship between output voltage and input displacement for the unloaded potentiometer

54、.It would seen that high sensitivity could be achieved simply by increasi</p><p>　　5.2 Resistance Strain Gauges</p><p>　　Resistance strain gauges are transducers which exhibit a change in elect

55、rical resistance in response to mechanical strain. They may be of the bonded or unbonded variety .</p><p>　　5.2.1 bonded strain gauges</p><p>　　Using an adhesive, these gauges are bonded, or cem

56、ented, directly on to the surface of the body or structure which is being examined.</p><p>　　Examples of bonded gauges are</p><p>　　fine wire gauges cemented to paper backing</p><p>

57、;　　photo-etched grids of conducting foil on an epoxy-resin backing</p><p>　　a single semiconductor filament mounted on an epoxy-resin backing with copper or nickel leads.</p><p>　　Resistance gau

58、ges can be made up as single elements to measuring strain in one direction only, or a combination of elements such as rosettes will permit simultaneous measurements in more than one direction.</p><p>　　5.2.2

59、 unbonded strain gauges</p><p>　　A typical unbonded-strain-gauge arrangement shows fine resistance wires stretched around supports in such a way that the deflection of the cantilever spring system changes th

60、e tension in the wires and thus alters the resistance of wire. Such an arrangement may be found in commercially available force, load, or pressure transducers.</p><p>　　5.3 Resistance Temperature Transducers

61、</p><p>　　The materials for these can be divided into two main groups:</p><p>　　metals such as platinum, copper, tungsten, and nickel which exhibit and increase in resistance as the temperature

62、rises; they have a positive temperature coefficient of resistance.</p><p>　　semiconductors, such as thermistors which use oxides of manganese, cobalt, chromium, or nickel. These exhibit large non-linear resi

63、stance changes with temperature variation and normally have a negative temperature coefficient of resistance.</p><p>　　5.3.1 metal resistance temperature transducers</p><p>　　These depend, for m

64、any practical purpose and within a narrow temperature range, upon the relationship R1=R0*[1+a*(b1-b2)] where a coefficient of resistance in ℃-1,and R0 resistance in ohms at the reference temperature b0=0℃ at the referenc

65、e temperature range ℃.</p><p>　　The international practical temperature scale is based on the platinum resistance thermometer, which covers the temperature range -259.35℃ to 630.5℃.</p><p>　　5.3

66、.2 thermistor resistance temperature transducers</p><p>　　Thermistors are temperature-sensitive resistors which exhibit large non-liner resistance changes with temperature variation. In general, they have a

67、negative temperature coefficient.For small temperature increments the variation in resistance is reasonably linear; but, if large temperature changes are experienced, special linearizing techniques are used in the measu

68、ring circuits to produce a linear relationship of resistance  against temperature.</p><p>　　Thermistors are normally made in the form of semiconductor discs enclosed in glass vitreous enamel. Since

69、 they can be made as small as 1mm,quite rapid response times are possible.</p><p>　　5.4 Photoconductive Cells</p><p>　　The photoconductive cell , uses a light-sensitive semiconductor material. T

70、he resistance between the metal electrodes decrease as the intensity of the light striking the semiconductor increases. Common semiconductor materials used for photo-conductive cells are cadmium sulphide, lead  

71、;sulphide, and copper-doped germanium.</p><p>　　The useful range of frequencies is determined by material used. Cadmium sulphide is mainly suitable for visible light, whereas lead sulphide has its peak respo

72、nse in the infra-red region and is, therefore , most suitable for flame-failure detection and temperature measurement.</p><p>　　5.5 Photoemissive Cells </p><p>　　When light strikes the cathode o

73、f the photoemissive cell are given sufficient energy to arrive the cathode. The positive anode attracts these electrons, producing a current which flows through resistor R and resulting in an output voltage V.</p>

74、<p>　　Photoelectrically generated voltage V=Ip.Rl</p><p>　　Where Ip=photoelectric current(A),and photoelectric current Ip=Kt.B</p><p>　　Where Kt=sensitivity (A/im),and B=illumination input

75、 (lumen)</p><p>　　Although the output voltage does give a good indication of the magnitude of illumination, the cells are more often used for counting or control purpose, where the light striking the cathode

76、 can be interrupted.</p><p>　　Capacitive Transducers</p><p>　　The capacitance can thus made to vary by changing either the relative permittivity, the effective area, or the distance separating t

77、he plates. The characteristic curves indicate that variations of area and relative permittivity give a linear relationship only over a small range of spacings. Thus the sensitivity is high for small values of d. 

78、60;Unlike the potentionmeter, the variable-distance capacitive transducer has an infinite resolution making it most suitable for measuring small increments of</p><p>　　Inductive Transducers</p><p&

79、gt;　　The inductance can thus be made to vary by changing the reluctance of the inductive circuit.Measuring techniques used with capacitive and inductive transducers:</p><p>　　A.C. excited bridges using diff

80、erential capacitors inductors.</p><p>　　A.C. potentiometer circuits for dynamic measurements.</p><p>　　D.C. circuits to give a voltage proportional to velocity for a capacitor.</p><p&

81、gt;　　Frequency-modulation methods, where the change of C or L varies the frequency of an oscillation circuit.</p><p>　　Important features of capacitive and inductive transducers are as follows:</p>&l

82、t;p>　　resolution infinite</p><p>　　accuracy+- 0.1% of full scale is quoted</p><p>　　displacement ranges 25*10-6 m to 10-3m</p><p>　　rise time less than 50us possible</p>&

83、lt;p>　　Typical measurands are displacement, pressure, vibration, sound, and liquid level.</p><p>　　8、 Linear Variable-differential Ttransformer9、 Piezo-electric Transducers10、Electromagnetic Transducers