Displacement sensor, also known as linear sensor, is a linear device belonging to metal induction. The function of the sensor is to convert various measured physical quantities into electrical quantities. In the production process, the measurement of displacement is generally divided into two types: measuring physical size and mechanical displacement. According to the different forms of transformation of the measured variable, displacement sensors can be divided into analog and digital types. Analog type can be divided into physical type and structural type. The most commonly used is analog structure type, including potentiometer displacement sensor, inductive displacement sensor, synchro, capacitive displacement sensor, eddy current displacement sensor, Hall displacement sensor, etc. An important advantage of digital displacement sensor is that it is easy to send the signal directly into the computer system. This type of sensor is developing rapidly and is increasingly widely used.

The working principle of the straight line is the same as that of the sliding rheostat. It is used as a voltage divider. The displacement sensor (Figure 5) presents the actual position of the measured position with a relative output voltage. There are several requirements for the operation of this device: 1. If the electronic ruler has been used for a long time, and the seal has aged, and there are many impurities, and the water mixture and oil will seriously affect the contact resistance of the brush, which will cause the displayed numbers to jump constantly. At this time, it can be said that the electronic ruler of the linear displacement sensor has been damaged and needs to be replaced.

2. If the capacity of the power supply is very small, many situations will occur, so the power supply needs to have sufficient capacity. Then, insufficient capacity will cause the following situations: the movement of the melt will cause the display of the mold electronic ruler to change and fluctuate, or the movement of the mold will cause the display of the injection electronic ruler to fluctuate, resulting in a large error in the measurement result. If the driving power supply of the solenoid valve is used at the same time as the power supply of the linear displacement sensor, the above situation is more likely to occur. In severe cases, the voltage range of the multimeter can even measure the relevant fluctuations of the voltage. If the situation is not caused by high-frequency interference, electrostatic interference or poor neutrality, then it may be caused by too low power of the power supply.

3. Both FM interference and electrostatic interference may cause the displayed numbers of the electronic ruler of the linear displacement sensor to jump. Displacement sensor (Figure 6) The signal line of the electronic ruler and the strong power line of the equipment should be separated by a cable trough. The electronic ruler must be compulsorily grounded, and at the same time, the outer shell of the electronic ruler must be in good contact with the ground. The signal line needs to use a shielded line, and a section of the electrical box should be grounded to the shielded line. If there is high-frequency interference, the voltage measurement using a multimeter will usually show normal, but the displayed number will jump continuously; and when static interference occurs, the situation is the same as high-frequency interference. To prove whether it is static interference, you can first use a section of power cord to short-circuit the cover screw of the electronic ruler with some metal on the machine. As long as it is short-circuited, the static interference will be eliminated immediately. However, it is difficult to use the above method to eliminate high-frequency interference. Frequency converters and robot arms often have high-frequency interference, so you can try to stop the high-frequency converter or robot arm to verify whether it is high-frequency interference.

4. If the electronic ruler of the linear displacement sensor regularly jumps at a certain point during operation, or does not display data, it is necessary to check whether the insulation of the connecting wire is damaged, and whether it is in regular contact with the shell of the machine, resulting in a short circuit to the ground.

5. The power supply voltage must be stable. The industrial voltage needs to meet the stability of ±[%]. For example, if the reference voltage is 10V, it can allow a fluctuation of ±. If not, it will cause the display to fluctuate. Displacement sensor (Figure 7) However, if the amplitude of the display fluctuation does not exceed the amplitude of the fluctuation voltage at this time, then the electronic ruler is normal.

6. The alignment of the linear displacement sensor needs to be very good, but the parallelism can allow an error of ±, and the angle can allow an error of ±12°. However, if the parallelism error and the angle error are both large, the displayed digital will jump. When this happens, you must adjust the parallelism and angle.

7. During the connection process, you must pay more attention to the three wires of the electronic ruler. The power cord and the output cord cannot be interchanged. If the above wires are connected incorrectly, there will be a large linear error, it will be difficult to control, the control accuracy will become very poor, and the display will easily jump, etc.