Basic knowledge of sensors

1.1 Definitions

A sensor is a device in an automatic detection device that directly senses the measurement and converts it into a usable signal output.

① Automatic detection is essential in the system composed of automatic devices.

(2) Direct feeling is measured, indicating that there is no other feeling device between the sensor and the measured.

(3) Most of the actual measurements are non-electric, of course, it may also be electric.

(4) The available signal of the output is the amount of electricity that has a definite correspondence with the measurement, usually voltage and current.

1.2 Composition

A sensitive element is a component in a sensor that directly feels the measured and outputs other quantities that are measured in a certain relationship. Its function is to detect and sense the information of the measured object.

(2) The conversion element is a component that only feels the other quantity output by the sensitive element and is measured into a certain relationship and converts it into electric output. Its function is to convert the information of the measured object into a usable output signal (electricity).

Auxiliary components: auxiliary power supply, fixed, supporting parts, etc.

1.3 Applications

Replace the human five senses (sight, hearing, smell, taste, touch) organs.

1.4.Classification

According to the nature of the output signal: digital sensor, analog sensor.

1.5 Output characteristics of digital quantity sensor

(1) NPN type: the output tube of the transducer's conversion element is NPN type.

The load (lamp) of the sensor is connected between the positive electrode of the sensor power supply (+DC24V) and the output signal of the sensor;

(2) When the sensor output tube is not induced, the output logic level of the output terminal is "1" (+DC24V), the load does not work;

When the sensor output tube is on, the output logic level of the output end is "0" (0V), and the load is powered to work.

(2) PNP type: the output tube of the conversion element of the sensor is PNP type.

The load of the sensor (lamp) is connected between the sensor output signal end and the negative electrode of the sensor power supply (0V);

(2) when the sensor output tube is not induced, the output logic level of the output end is "0" (0V), and the load does not work;

When the sensor output tube is on, the output logic level is "1" (+DC24V), and the load is powered.

Figure 1.2 Sensor output characteristics for an example of inductive proximity switch