传感器的基础知识中英文对照外文翻译文献.docx

1、传感器的基础知识中英文对照外文翻译文献中英文对照外翻译Basic knowledge of transducersA transducer is a device which converts the quantity being measured into an optical, mechanical, or-more commonly-electrical signal.The energy-conversion process that takes place is referred to as transduction. Transducers are classified accor

2、ding to the transduction 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 diaphragm, pressure flapper-nozzle, and so on.1、Transduce

3、r ElementsAlthough there are exception ,most transducers consist of a sensing element and a conversion or control element. For example, diaphragms,bellows,strain tubes and rings, bourdon tubes, and cantilevers are sensing elements which respond to changes in pressure or force and convert these physi

4、cal quantities into a displacement. This displacement may then be used to change an electrical parameter such as voltage, resistance, capacitance, or inductance. Such combination of mechanical and electrical elements form electromechanical transducing devices or transducers. Similar combination can

5、be made for other energy input such as thermal. Photo, magnetic and chemical,giving thermoelectric, photoelectric,electromaanetic, and electrochemical transducers respectively.2、Transducer SensitivityThe relationship between the measured and the transducer output signal is usually obtained by calibr

6、ation tests and is referred to as the transducer sensitivity K1= output-signal increment / measured increment . In practice, the transducer sensitivity is usually known, and, by measuring the output signal, the input quantity is determined from input= output-signal increment / K1. 3、Characteristics

7、of an Ideal TransducerThe high transducer should exhibit the following characteristicsa)high fidelity-the transducer output waveform shape be a faithful reproduction of the measured; there should be minimum distortion.b)There should be minimum interference with the quantity being measured; the prese

8、nce of the transducer should not alter the measured in any way.c)Size. The transducer must be capable of being placed exactly where it is needed.d)There should be a linear relationship between the measured and the transducer signal.e)The transducer should have minimum sensitivity to external effects

9、, pressure transducers,for example,are often subjected to external effects such vibration and temperature.f)The natural frequency of the transducer should be well separated from the frequency and harmonics of the measurand.4、Electrical TransducersElectrical transducers exhibit many of the ideal char

10、acteristics. In addition they offer high sensitivity as well as promoting the possible of remote indication or mesdurement.Electrical transducers can be divided into two distinct groups:a)variable-control-parameter types,which include:i)resistanceii)capacitanceiii)inductanceiv)mutual-inductance type

11、sThese transducers all rely on external excitation voltage for their operation.b)self-generating types,which includei)electromagneticii)thermoelectriciii)photoemissiveiv)piezo-electric typesThese all themselves produce an output voltage in response to the measurand input and their effects are revers

12、ible. For example, a piezo-electric transducer normally produces 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 at the frequency of

13、the alternating voltage.5、Resistance TransducersResistance transducers may be divided into two groups, as follows:i)Those which experience a large resistance change, measured by using potential-divider methods. Potentiometers are in this group.ii)Those which experience a small resistance change, mea

14、sured by bridge-circuit methods. Examples of this group include strain gauges and resistance thermometers.5.1 PotentiometersA linear wire-wound potentiometer consists of a number of turns resistance wire wound around a non-conducting former, together with a wiping contact which travels over the barw

15、ires. The construction principles are shown in figure which indicate that the wiper displacement can be rotary, translational, or a combination of both to give a helical-type motion. The excitation voltage may be either a.c. ord.c. and the output voltage is proportional to the input motion, provided

16、 the measuring device has a resistance which is much greater than the potentiometer resistance.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 windings and the area of the sliding contact. The output voltage is thus a serials of steps as the contac