Definition and composition of the sensor
1 Definition and composition of the sensor
1.1 Definition of the sensor
According to the national standard "Sensor General Terminology" (GB / T 7665-2005) released on July 29,2005, the sensor (transduce r/sensor) is defined as a device or device that can be measured and converted into usable output signals according to certain rules, usually composed of sensitive components and conversion components.
The sensitive element (sensing element) refers to the part of the sensor that can directly feel or respond to the measured; the conversion element (transducing element) refers to the part of the sensor that can convert the sensitive element into an electrical signal suitable for transmission or measurement; when the sensor output is the specified standard signal, it is called the transmitter (transmitter); the English transducer and sensor of the sensor are common.
This definition contains information in the following areas:
1) The sensor is a measuring "device" or "device", which can complete the detection task.
2) Its input is "measured," it may be physical, chemical or biomass, etc.
3) Its output is "available" electrical signals, such as voltage, current, frequency, etc., easy transmission, conversion, processing, display, etc.
4) The corresponding relationship between output and input should have "certain rules", and should have a certain accuracy, which can be described by a definite mathematical model.
Note that the concept of the sensor and the transmitter is clearly distinguished, or called the transmitter, when the output of the sensor is the "specified standard signal". For the so-called "specified standard signal", the current output standard signal is 4 ~ 20 mA or 0 ~ 10 mA, and the voltage output standard signal is 1~5V, 0~5V, 0~10V or-10~10V.
1.2 Composition of the sensor
According to the definition of sensor, the basic composition of sensor usually includes two parts: sensitive element and conversion element, which complete the two basic functions of detection and conversion respectively. However, the sensor composed only of sensitive elements and conversion elements usually has a weak output signal, and the conversion circuit needs to amplify and convert the output signal into easy transmission, processing, recording and display. Therefore, the sensor generally consists of three parts: sensitive element, conversion element and conversion circuit.
In the figure, the respective components are described below:
1) The sensitive element is directly measured, and a physical quantity is output in a determined relationship.
2) The conversion element converts the non-electric physical quantity output by the sensitive element into electric parameters.
3) The conversion circuit converts the electrical parameters into easy to measure the electricity quantity. The type of the conversion circuit is also related to the type of the conversion element,
Therefore, the conversion circuit is often regarded as one of the components of the sensor.
The armature is fixed at the free end of the spring tube, symmetrical with the inductive coil A and B, and the two inductive coils are connected to the conversion circuit behind it. When the internal pressure of the spring tube changes, the resulting deformation shifts the free end of the spring tube. The spring tube here is the sensitive element, which converts the change of the measured pressure into a change in the displacement amount. Inductor coil A and coil B are conversion elements that convert displacement changes into inductance changes, and the subsequent conversion circuit convert inductance into voltage.
It needs to be pointed out that not all sensors can obviously distinguish between sensitive components and conversion elements the two parts, such as semiconductor gas sensitive or wet sensitive sensor, thermocouple, piezoelectric crystal, photoelectric devices, etc., they can generally feel be measured directly into electrical signal output, namely sensitive elements and the function of the combination of conversion elements.
Some sensors have more than one conversion element. In practice, there are very few sensors composed of only one conversion element, and the conversion elements with different performance are usually combined to complete the conversion function.
