Proximity switch overview

Proximity switch overview

When a moving object is close to it When it reaches a certain position, it can send out a signal to control the position or stroke of a moving object, or a master electrical appliance that controls automatic counting. Since the proximity switch is a non-contact object detection device, it can be used as a non-contact and non-contact micro switch, travel switch and limit switch. Proximity switches can be divided into high-frequency oscillation type, capacitance type, inductive bridge type, permanent magnet type and Hall effect type according to their working principles. The most used

It is high frequency Oscillating proximity switches account for about 80%. The working principle of this switch is based on changes in the state of a high-frequency oscillation circuit.

When there is metal When an object (which is equivalent to a contact block on a moving part of a working machine) enters the coil magnetic field of a high-frequency oscillator oscillating at a certain frequency, eddy current losses are generated inside the metal object (if it is a ferromagnetic metal object, magnetism will also be generated) Hysteresis loss), causing the resistance of the oscillation circuit to increase and the energy consumption to increase, resulting in the oscillation weakening until it terminates. In this way, just by connecting a suitable switch behind the oscillation circuit, the presence of metal objects can be detected and corresponding control signals and instructions given. Proximity switches have the advantages of accurate positioning, high sensitivity (can detect micron-level position changes), high operating frequency (up to dozens to hundreds of times per second), resistance to mechanical shock and vibration, resistance to moisture, small size, and long life. , widely used in various automatic control systems.