, Product performance and uses: proximity switch, also known as non-contact limit switch, in addition to the completion of the stroke control and limit protection, or a non-contact detection device, used for detection part size and speed, can also be used automatic interface between the frequency counters, frequency pulse generator, liquid level control and processing procedures. Features reliable work, long life, low power consumption, high complex positioning accuracy, high operating frequency, and to adapt to the harsh working environment. Second, the main purpose close to the switch are widely used in aviation, aerospace technology and industrial production. In everyday life, such as hotels, restaurants, automatic garage doors, automatic hot air blower on the application. In security burglar aspects, such as data files, accounting, financial, museums, treasury powerhouse, usually are equipped with anti-theft devices by various proximity switches. In measurement techniques, such as length, position of the measurement; in control technology, such as displacement, velocity, acceleration of the measurement and control, are also using a large number of the proximity switch.