Proximity sensor works - Solutions - Huaqiang

Crystal oscillator

Quartz Oscillator 3225 20M OSC

Proximity sensor, formerly known as contactless travel switch, is not only a stroke control and limit protection, but also a non-contact type detection device, used for detecting part size and speed measurement, etc. It can also be used for inverter counters and variable frequency pulses. Automatic connection of generators, level control and machining programs. Proximity sensors can be classified into high frequency oscillation type, capacitance type, induction bridge type, permanent magnet type and Hall effect type according to the working principle. The proximity sensor can detect a metal target close to the sensor without actually contacting the target. According to the principle of operation, the proximity sensors can be roughly classified into the following three types: a high-frequency oscillation type using electromagnetic induction, a magnetic type using a magnet, and a capacitance type using a capacitance change. Capacitive proximity sensor works: Capacitive proximity sensor consists of a high-frequency oscillator and an amplifier. A capacitor is formed between the detection surface of the sensor and the ground. It participates in the oscillation circuit and starts to oscillate. When the object approaches the sensor to detect the surface, the capacitance of the loop changes, causing the high frequency oscillator to oscillate. The two states of oscillation and stoppage are converted into electrical signals that are converted into binary switching signals by an amplifier. The working principle of the inductive proximity sensor is composed of an LC high-frequency oscillator and an amplifier processor circuit. When a metal object approaches the oscillation induction head, eddy current is generated, so that the proximity sensor oscillation capability is attenuated, and the parameters of the internal circuit are changed, thereby identifying The presence or absence of a metal object is close to control the on or off of the switch. The working principle of the high-frequency oscillating proximity sensor: the inductive proximity sensor consists of high-frequency oscillation, detection, amplification, triggering and output circuits. The oscillator generates an alternating electromagnetic field on the sensor detection surface. When the metal object approaches the sensor detection surface, the eddy current generated in the metal absorbs the energy of the oscillator, so that the oscillation is weakened and the vibration is stopped. The oscillation and oscillation of the oscillator are converted into electrical signals and converted into binary switching signals by shaping amplification, which are output after power amplification. The working principle of all metal sensors: All metal sensors are basically high frequency oscillation type. Like the normal type, it also has an oscillating circuit in which the energy loss caused by the induced current flowing in the target affects the oscillation frequency. When the target approaches the sensor, the oscillation frequency increases regardless of the metal type of the target. The sensor detects this change and outputs a detection signal. Working principle of non-ferrous metal sensor: Non-ferrous metal sensor is basically a high-frequency oscillation type. It has an oscillating circuit in which the energy loss caused by the induced current flowing in the target affects the change of the oscillation frequency. When a non-ferrous metal object such as aluminum or copper approaches the sensor, the oscillation frequency increases; when a ferrous metal object such as iron approaches the sensor, the oscillation frequency decreases. If the oscillation frequency is higher than the reference frequency, the sensor outputs a signal. The working principle of the universal proximity sensor: the coil L in the oscillating circuit generates a high frequency magnetic field. When the target is close to the magnetic field, an induced current (eddy current) is generated in the target due to electromagnetic induction. As the target approaches the sensor, the induced current increases, causing the load in the oscillating circuit to increase. Then, the oscillation is weakened until it stops. The sensor detects the change in the oscillation state by the amplitude detecting circuit and outputs a detection signal.