The automatic hand dryer works by automatically sensing far infrared rays, and consists of an infrared emitter, a receiver, a monostable delay switch, a solid-state relay and a blower. And form a simple self-excited multivibrator. The infrared emission tube emits modulated infrared light with a frequency of about 40kHz.

When that hand reach under the automatic hand dry,

The emitted infrared rays are partially reflected by human hands,

And is received by the phototransistor,

Converted into electrical signals with the same frequency,

Then output a low-level pulse signal after amplification, shape and band-pass comparison by an integrated circuit of an infrared receiving special preamplifier,

Thereby triggering the monostable circuit to enter a transient state,

Make it output a high level,

Glow,

The AC solid state relay is turned on,

So that the electric hair dryer can send out hot air when being electrified.

When the hand dries and leaves,

Lose infrared pulse signal, restore high level,

The monostable circuit is quickly reset,

Due to the delay, the hair dryer will automatically resume after working for about 10s at most, thus stopping working.

Simply put: infrared detection-relay-hot air blower.

When the human hand approaches the infrared probe, the probe detects the human body signal; Logic circuit flip; Signal that drive circuit; The relay works; Turn on the power supply of the hot air blower; Leave by hand; Circuit restoration; The hot air blower stops working; Wait for the next working signal.

Principle of induction hand dryer: induction is convenient and fast, blowing hot air can speed up the evaporation of water on hands and save users time.

In other words, in the shortest time, the water on the user's hands will evaporate in a cleaner way.

This method of drying hands is cleaner than wiping with a towel, and it is less prone to infection with bacteria.